Bidhan Chandra Roy
Editor’s Note: The Vietnamese diaspora comprises a significant population among California’s immigrant communities. For some of these, the trauma of involuntary migration and the subsequent necessity to negotiate Vietnamese and American identities did not lead to enriching new experiences or cultural formations. A less visible demographic than those currently celebrated by food, literary, or cultural critics today are the Vietnamese Americans currently incarcerated in California’s vast prison system. Not long ago, almost 65% of California’s Asian and Pacific Islander prison population was comprised of either immigrants or refugees, and Vietnamese Americans represented the largest segment of the Asian and Pacific Islander California prison demographic at 22%. This constitutes a significant number of Vietnamese Americans currently incarcerated in California—a fact remaining largely unknown to many Californians.
One such person, for whom the trauma of migration and the negotiation of identities in California produced a path to prison is Tin Nguyen, who is currently serving a “Life Without the Possibility of Parole” sentence at Los Angeles County Prison, Lancaster. As a former Vietnamese gang member, Tin is now a student in Cal State LA’s BA program at Lancaster, as well as a published writer. Boom editorial board member Bidhan Chandra Roy sat down with Tin over three meetings to discuss his childhood experiences of fleeing Vietnam as a child in the 1970s, his role in establishing a new wave of Vietnamese street gangs in Southern California in the 1990s, and his hard-fought transformation into the man he is today. Since recording equipment is not allowed in the prison during the interview, Tin wrote up his responses to the questions following the three meetings.
Boom: Can you tell us about your experiences traveling from Vietnam to California as a child in the 1970s? What do you remember of that journey? Do you ever recall these memories today?
Tin: At 145 pounds and thirty-two years of age, I was standing in front of the ‘C’ section shower in Building 3 on a maximum-security prison yard. A group of muscular, heavyset Crip members surrounded me, disputing for a shower that none of us own; really, the State of California owned the shower. I knew if I didn’t back down, I could expect at the very least a severe beating, and quite likely, a knife to the gut or a sliced throat. Yet I stood there, at the risk of my own life, because this shower was claimed by the Asians; the marking of our territory. At that moment, I thought, “So this is how I’m going to die… this is how my life sentence was going to end….”
In that moment, I couldn’t help but rapidly wonder, “How did I get here? What happened to the once little Vietnamese boy who pulled his small red wagon along the streets of Pomona and sold flowers to help his mother buy milk for his baby brother?” How did that innocent kid become a monster now tagged P24706?
At that moment, I thought, “So this is how I’m going to die… this is how my life sentence was going to end….”
I remember the boat journey in the late ’70s as flashes of images. There is an image of my godparents hugging me tight; through their tears, they tried to act as if everything was normal. I guess, because of the tension in Vietnam, they didn’t want any suspicion of what was going to happen, an attempt to escape Vietnam. Then there are images of my mother under the cover of darkness passing—or should I say, throwing (my mother would disapprove of this characterization)—me from boat to boat. Thinking of how our boat sped away from two other boats, I remember the word, “pirates,” repeated on everyone’s lips and a throng of rowdy men with all sorts of objects in their hands for weapons.
I remember us all on the boat’s roof, bowing our heads, and me trying to look over, seeing for the first time, men with pale skin standing on the deck of a large ship. We begged for their assistance, to no avail; they just passed by leaving us to fend for ourselves in the great ocean.
Then our boat finally landed. At the island where I have the fondest memories, images and feelings of happiness, swimming all day and following my brother on the shore as the tide was low, catching crabs and fishes. After that, I remember feeling frightened on a plane as I encountered people of different ethnicities, on our way to California.
Boom: What was it like for you growing up in Pomona during the 1980s and 1990s?
Tin: In Pomona, everything was different. In second grade, I was the only Vietnamese kid in class, and not speaking a word of English, I hated school. Kids can be cruel. Yet, the constant taunts of “ching-chong,” “jap,” and “dirty gook,” were the least of my miseries. Because they wanted to test my kung fu, I was punched in the throat and smacked on the back of my head during long walks home from school. To this day, I still have a vivid memory of being run over by a bike—my books were everywhere, I was facedown, and a BMX wheel was on my back, pinning me to ground, while the guy snickered, “You should’ve gotten out my way,” and spit on me. He then rode over me. I cried as I picked up my stuff off the ground, while other kids walked by and laughed, but no one helped. I cried all the way home, and then some. I thought it was my fault for being in his way, but then it occurred to me that all his friends had rode around me with plenty of room. That’s when a spark of anger ignited within me. But that anger from those physical discomforts didn’t compare to what ultimately fueled my anger with a real hate.
What truly fueled my anger was the thought of my family being subjected to the same abuse and discrimination. I remember my older sister sitting in the schoolyard lunch area crying, while other Vietnamese kids were making fun of her. What made this especially painful was the American kids were laughing about how they’d gotten us to turn on each other for their amusement. When I was nine or ten years old, I tried to help an older Vietnamese gentleman who didn’t speak English. There was a misunderstanding at a store, where the sales clerk was accusing the Vietnamese man, hurling crude comments at him, like, “You gook! You’re a thief, coming to the US just to steal and cause trouble. You should’ve stayed in Vietnam.” I remember a feeling of heavy degradation. With my broken English, I attempted to serve as a translator and tried to explain that the Vietnamese man had a receipt. But it was no use. The clerk kept ranting and ended up reducing the Vietnamese man to tears. From that experience, I had the sinking realization that my parents must be suffering similar indignities.
Once I was sitting outside of my older sister’s bedroom door, I heard her crying as she told my cousin how an African-American woman had mistreated her at the college’s financial aid office. I don’t quite recall the exact words, but I do remember clearly the feelings of anger and hate. Hurting me was one thing, but hurting my family was another matter. What made it worse was the helplessness I felt to do anything about it. This is the reason why I’m very protective of my little sister.
I couldn’t claim I was Vietnamese because I barely spoke Vietnamese, and I couldn’t say I was American because I wasn’t born here and barely spoke proper English.
I suppose all these external hardships contributed to who I eventually became, but no less significant were the internal dynamics of my family. Let me start by acknowledging that my father was a very good man who loved his children and always sacrificed for his family. Yet, there were a number of factors that enabled his violent behavior. First, he was raised in a traditional culture where the father’s words are absolute and indisputable, and corporal punishment was the norm. Back in Vietnam, my father was a person of some importance and social standing, so for him, it was a letdown being in America—after losing everything and making all the sacrifices that he did—to become a nobody who had to rely on his wife and whose children wouldn’t even listen to him. I can only imagine how this ate away at his pride, driving him to the edge. Typical days in our house had fights and arguments; I don’t remember a happy moment at home. The Christmas tree tumbled a few times every Christmas. During the year, my mother would vigorously defend her children from her husband’s wrath, after she’d worked all day to put food on the table. Even though my father never made a fist, he did freely use the backhand, the front smack, the belt, the telephone cord, the clothes hanger, and my own favorite—the chopsticks, with a hand full of them, they hurt like hell. I remember like yesterday… I was huddled in the kitchen corner while my mother used her petite body to shield me from being hit by an inch-thick stick as she told my father in Vietnamese: “you’re not going to hit my son with that.” But this was the Vietnamese way, right? Our culture? In such moments, I envied my American friends.
I think what made things worse was that I didn’t know where I belonged, who I was. I couldn’t claim I was Vietnamese because I barely spoke Vietnamese, and I couldn’t say I was American because I wasn’t born here and barely spoke proper English. I felt trapped between two generations of immigrants, one who knew they’re Vietnamese, and one who knew they’re American. My father pushed me to read more and to keep up with my sister in school, and when I couldn’t, I was “dumber than a cow” (English translation). During times when I could, I wasn’t “dumber,” but merely “dumb as a cow.” Either way, I was always dumb. This wasn’t just my father’s assessment, it was everyone’s. I guess they hoped I’d at least be good with my hands. To my mother though, I was always good and smart, but her opinion wasn’t enough. So I ended up with low self-esteem, insecure, lost, and filled with anger and hate.
Boom: How did this childhood trauma pave the way for you joining a gang? How did you see Vietnamese gangs begin to proliferate in South California during your adolescence, and what attracted you to join one?
Tin: In America, the first Vietnamese generation’s youth trend was “New Wave,” with its tight pants, pointy shoes, and spiky hair, and dancing to European bands like Modern Talking, CC Catch, and Bad Boys Blue. With no one I deemed worthy as a role model, I turned to my two older brothers. They were cool, and if someone wanted to test their kung fu, they didn’t have any problem showing that their kung fu was better. Seeing them fighting and winning, I developed a sense of Vietnamese pride, so it wasn’t long before I showed others my kung fu was good too. My first violent act was during a summer camp at Cal Poly. When a Caucasian kid tested me, I didn’t hold back, but instead, I punched him. Next thing I knew, a counselor was holding me and a crowd of kids was cheering me on. The counselor sternly stated that I was going to be suspended, and I replied that I didn’t give a fuck, at which point the crowd got even louder. This was not only my first act of violence, but also my first act of rebellion, and I knew then that this was how I must act in order to be respected, like my brothers. The final straw came when some of my boy scout troop and I were jumped by a group of African-American teens. After the teens’ laughter and us lying on the ground of the parking lot, we looked at each other and decided then that the boy scouts was not for us. We chucked our uniforms and donned blue jeans and chains, going from scouts to hoodlums.
In Southern California, there tended to be two kinds of Vietnamese gangs. The first was the street gang, largely unstructured. But unlike their Hispanic or African-American counterparts, it was rare for Vietnamese street gangs to truly represent a street or neighborhood. Rather, they were just some Vietnamese teens who got together and named themselves, mostly in accord with the city they were from—like “Pomona Boys” or “Santa Ana Boys”—or something to do with Vietnamese pride, like “V-Boys” or “Vietnamese For Life.” Since I was Vietnamese and from Pomona, my boys and I decided to call ourselves Vietnamese Gangster (VNG) Pomona V-Boys. We used the appendage “V-Boys” because we were the V-Boys’ younger association and under their protection. We started with minor things like cracking arcade games for money, and then moved up to GTA. Fighting was the norm now, and I soon landed in juvenile camp. Three months later, I came out bigger because I finally hit puberty. Everyone who mattered to me knew that I’d just come from the “box” and it wasn’t long before I went back to camp. My father still had hope for me, but after this second stretch, I disappointed him again and was no longer welcome under his roof. So with no place of my own, at age sixteen, I reached out to my brother Tony in Los Angeles, where I met the Black Dragon for the first time.
This is the second kind of Vietnamese gang, more exclusive to the LA area. This second kind was more engaged in organized crime, after the pattern of triads, perhaps because of the close cultural proximity of the Vietnamese to the Chinese. Black Dragon (Hac Lun) was one of these, and unlike the unstructured street gangs, Black Dragon had an ordered hierarchy where a soldier could move up the ranks and, if he is lucky and doesn’t land in prison for life or die, become an “Anh Hai” or a “Tai Lu”—the equivalent of a “Capo” in the Italian crime families.
The history of the Black Dragon began in the early 1980s. Its predecessor, the Viet Thanh, actually yielded three successors: Cool Boys, LA V-Boys, and Black Dragon. Since each came from Viet Thanh, these three were always at war with its rival, the Chinese gang Wa Ching. In the late 1970s and early 1980s, Chinatown consisted of both Chinese businesses and Vietnamese businesses. But the Wa Ching began harassing Vietnamese businesses, so the youths of the Vietnamese businesses decided to stand against the Wa Ching. That was how Viet Thanh started. But what started out as noble acts eventually were corrupted as the Viet Thanh became thugs themselves. After the three-way split, Black Dragon migrated to the San Gabriel Valley where it established new territories.
I chose to be part of the Black Dragon mainly because of the respect their members received. For example, one time my boys and I were walking into a nightclub associated with the Black Dragon, and a new bouncer stopped us and pointed us to the back of the line, but then the regular bouncer told him to let us through. (We were all still minors and this club was for those over twenty-one.) When we entered, the new bouncer insisted that we walk through the metal detector, which, of course, we weren’t going to do. This was when the older bouncer stepped in and told the new bouncer, “These guys are the real security of this club.” I still remember his words, and the pride I felt then was overwhelming, but it didn’t compare with what happened next. After my boys and I settled in at a VIP table, this new bouncer asked if he could speak with me. Sitting across from me, he asked for my forgiveness, pleading that he didn’t know since he was new. Here was a middle-aged man humbled, apologizing for his mistake and offering me his services. Respect… at long last.
When I became a member of the Black Dragon gang, I was known as Tin Hac Lun, or Tin BD. I carried that name with pride. When others thought of Black Dragon, I wanted them to think of me. When I was twenty-two, the Temple City Sheriff led the Asian Gang Task Force and rounded up my crew, now known as the “gangbanging” side of Black Dragon. I was facing possible of fifty-eight years for numerous counts of extortion and robbery, so I took a deal for two years and did my time at San Quentin. Obviously, I didn’t learn anything, and worse, I was now connected and moved up the ranks because I’d been to the big house. During this time, my crew and I broke away from our Anh Hai, because we no longer wanted or needed to be under his thumb. We could protect ourselves without him, and we wanted to keep all our earnings and not have to give him a cut. No longer a soldier, I had my own crew. However, we still kept the “Black Dragon” name because we’d earned it, and our loyalty was still to the gang.
Boom: Tin Hac Lun sounds like a completely different person to the Tin I have known for the past four years. How did the lifestyle you led as Tin Hac Lun end in a prison sentence of life without the possibility of parole?
Tin: Drugs were a major detriment in my life. At a young age, I inadvertently unleashed a demon so voracious that it consumed me. I started drinking in seventh grade, and met Mary Jane (marijuana) and Coco (cocaine) when I was fourteen. A couple years later, at a party, I was sitting on the bathroom floor across from a beautiful woman in her twenties, and she passed me a pipe with some crack…. Part of me screamed, “No!” But the demon within me seductively whispered, “Don’t embarrass yourself in front of this glorious girl—just take a hit, that’s all.” And the demon was right; that was all. I became the demon himself. Mary Jane, Coco, and later Crystal (Methamphetamine) became the three loves of my life. They destroyed me and brought me to the edge of suicide. Yet for one reason or another, I couldn’t find the nerve to do it myself, so I went crazy with drugs and gangs, hoping to end it all.
In 1996, during a robbery in San Jose, I killed Mr. Stanko Vuckovic. Throughout the years, I have replayed that moment repeatedly. I asked myself, “Did I pull the trigger?” or “Did the gun go off during the struggle?” After years of contemplating, I realized there were other factors just as significant. The point that I cocked the gun, that I chose to use the gun in the robbery, and above all my decision to rob this man and take what was not mine were all what caused his death. Yet, these were not the only factors. Other elements, such as abusing drugs, joining a gang and choosing a life of crime, were all the bad choices I made that led me to that very moment. I was going to kill someone eventually. Thus, I am responsible for Mr. Stanko Vuckovic’s death; I pulled the trigger and my only hope is that I can make amends for my actions and decisions.
I was arrested a year after I killed Mr. Vuckovic, and in late 1998 I was convicted and sentence to Life With Out the Possibility of Parole. Let me express now, with all respect, what I have wanted to say for two decades. I’ve run this in my head thousands of times…. I mean, how do I express my remorse and say, “I am so sorry” to a man whose life and future I took, to a family whom I hurt, or to the community I damaged? It’s not enough, and I realize that I must do this in person, for words on paper can never be adequate to sincerely express my contrition.
Boom: Thank you for saying that, Tin. I know that you want to return to your remorse and desire to make amends for past actions. But before you had this realization, what was your life like in a maximum-security prison? Was there anything unique about it from a Vietnamese perspective?
Tin: At age twenty-six, I began my journey on the gravel yard track at Pelican Bay, California’s most dangerous state prison. On my first day, an elder Vietnamese convict approached me and said, “Welcome to Pelican Bay, we’re the worst of the worst in California. You’re with us. You run Asian.” As we approached a table full of Asians and Pacific Islander, he expounded on the first rule, concerning “the boundaries.” He explained that the Whites, Blacks, and Mexicans have their tables, workout areas, and basketball and handball courts, and approximately ten feet around those areas was an invisible line that I was not to cross without their permission—if I did, my well-being would be at risk. Likewise, I was not to allow any other race to cross over our line; my job (and the job of all Asians and Pacific Islanders) was to stop the other races from crossing over, and if necessary, to “take flight” (i.e., stab them). So, that was the creed I lived by for many years. In prison, racial segregation was (and is) the norm; this was one of the many rules I had to abide by.
Here, there are two sets of rules. One is the Administration’s. As a prisoner, if you violate those, then you’ll be put in “the Hole.” The other set of rules is the convicts’. If you violate them, then you’ll have holes put in you.
As for the Vietnamese culture in prison, we might be small, but we’re no less vicious than the other races. Maybe it’s the pride we have. I’d read in a Vietnam War book that there are two nationalities that never stop fighting: one is the Irish; the other, the Vietnamese. At Pelican Bay, we Vietnamese were a tight group, and we helped each other with most things, like food, clothes, etc. Even though we had divisions among ourselves, such as North Cali versus South Cali, we united when troubles came our way—we bowed down to no one, even at the risk of our lives.
Boom: That life seems a long way behind you now at Lancaster. Tell us about the man you are today, Tin. How did such a remarkable transformation take place?
Tin: This leads me back to the beginning of this interview. I believe there was someone up above divinely watching over me. When I was once surrounded and it looked like it was going to go badly for me, suddenly a big, muscular African American guy and his friends approached the crowd. These guys were Bloods, and they intervened and had a side meeting with the Crips surrounding me. Ultimately, the situation was resolved, and I survived another day. The Good Samaritan’s name was Jimmy, and we eventually became best friends, a big African American and a little Vietnamese. Today, Jimmy and I are both Golden Eagle classmates at California State University, Los Angeles.
Now, during my incarceration, I’ve experienced much pain, and I would shut this pain away, because to feel pain was to be weak, and early in my incarceration I chose never to be weak so that I would not be preyed upon. With this attitude, I felt dead, and in a way I was dead, just a walking corpse with no purpose, hope, or love. Approximately two years ago, I was in a very dark place. I know this sounds cliché, but a dog saved my life. It was part of the Paws for Life Program.
I used to be petrified of dogs— definitely not a dog person. However, all that changed one evening when a Boxer put his head on my lap. Before this happened, my ex-girlfriend had left me. A broken heart is never easy, especially while doing “Life,” and it is not uncommon to feel depressed. However, it should not make one feel hopeless, or even destitute. In hindsight, I realize that this was the pivotal point of my life; whether I was going make it or break it. All the pains of my life, that I had carefully locked away, came rushing out. The pains of my childhood, the regret and remorse of my crime, the loss of my freedom, and the death of my father and brother during my incarceration came back to haunt me. The break up was the key that unlocked my miseries. The pains were excruciating. I wanted to end it one way or another, wanted the pain to go away. I’d kept on like this until I was so broken that I couldn’t deal with it anymore. Once again, I contemplated the forever night, the long sleep. However, an angel came to rescue me. It didn’t come with its majestic wings or divine presence, nor even a halo, but rather with four paws and a mean mug. My angel turned out to be “Vic,” a battered Boxer-breed dog who’d been used as bait for fighting pit bulls. My encounter with Vic happened in a most unusual way.
One evening as I was talking to my friend Bernik, I noticed a Boxer dog full of anxiety. He stood there constantly watching as if something might attack him. Then all of a sudden, he came over and laid his head on my lap. I was scared, yet touched. Then he proceeded to lay down, and Bernik said, “Wow!” It didn’t seem out of the ordinary to me, so I asked why all the excitement. Bernik explained that the Boxer named Vic was a bait dog, who had come here all scarred up with a smashed paw. He had a rough life. Bernik said that since he came in, he hadn’t been able to relax, so lying down and sleeping at my feet was amazing. This broke through me in a way I did not think possible. I knew that I couldn’t help him amid my own pain, but he was offering his pain for me to help with. So I reached down, put my hand on his head, and whispered, “I got your back, bud. No one on this yard is going to hurt you.” From then on, I made sure that I spent as much time as I could to comfort him, train him, and protect him. Through this relationship, Vic got better, and that was the goal. However, though I thought that I was there for him, it was also the other way around; Vic was there for me. He comforted me when I was down and out. He trained me to be strong and get back up, and protected me from my destructive self. The funny thing was that I believed that when Vic came over to me, he was thinking “that guy is suffering like me; maybe I should help and protect him.”
What PFL did for me is extraordinary. PFL not only saved my life, but it also gave me life.
Though Vic gave me love, I was still somewhat lost, still believing that I was irredeemable and doomed to a life of constant bad decision-making. Then through PFL came a second angel—you Dr. Roy. With your kindness and untiring passion to see the good in all, in everyone, you amazed me and became for me the role model that I’d never had before. No words can express my full appreciation for what you have done for incarcerated people, me especially. You looked at us not through the eyes of an enemy or through hate, but through the eyes of love, and with respect for our humanity. As a result, you gave us confidence, hope, and purpose.
Now I’m a student on this extension campus inside this prison, and I’m on my way to attaining my dream of obtaining a BA degree. I once thought I was irredeemable, meaning that I thought I had to die first and be reincarnated or something else if I were to have any hope of ever being a good person again. Now, the professors and faculty and students at Cal State LA have taught me that I can take down those walls that I built around my heart. Even if it’s day by day, I can take down those walls, because I am the builder. I don’t need them to protect me from pain, failure, or disappointment, because I’m not inherently bad. I know now that being good is a choice that I’ll be faced with making every day of my life. I once was an advocate of all that’s dark and hate surrounded me with those walls. I promoted the Black Dragon and Vietnamese gangs’ lifestyles to other Vietnamese youth, but now, I encourage them to get their education, to transform their lives and live with hope and goodness.
I’m serving a sentence of Life Without the Possibility of Parole, which means that if the laws do not change or society has no mercy for me, then I will die in prison. “Life Without the Possibility of Parole” is a death sentence—the only difference between it and lethal injection is that Death Row prisoners get a final meal and a team of lawyers. Still, as bleak as my circumstances are, I find myself happier than at any time in my life since childhood. That little Vietnamese kid with his little red wagon that was imprisoned as P24706, today I walk my dog in the evening on the prison yard, and no longer feel the cold concrete walls with their sharp razor-wire, nor the tower with its gunner and Mini-14. Here, it is just me and my dog… and I feel free.
Editor’s Postscript: When the interview was completed at the end of the third meeting, without explanation Tin prostrated himself before Dr. Roy in the middle of the prison yard in front of all the guards and other prisoners. He performed a deeply meaningful ritual, later explaining it in the following way, asking that it be included in this interview to honor the family of Stanko Vuckovic—the man whose life he took.
Tin: I may never have that chance to apologize in person, so I’d like to do this now at least.
I would like to do this in the Vietnamese traditional way.
I am on my knees, and bow my head, prostrating myself, three times.
With each: “I am so sorry, please forgive me.”
I promise for the rest of my life, as a living amends, I will do my best to impact others’ lives for the good in homage of you, your family, and your community. Thank you for allowing me to be honest and express my remorse.
 These numbers, while a bit dated, are provided by the Asian Prisoner Support Committee, https://apscinfo.wordpress.com/2010/10/06/apis-in-ca-prisons/. More up to date details can be found in the California Department of Corrections and Rehabilitation’s offender data points demographic, comprising the most recent demographic information for those incarcerated in CDCR, https://www.cdcr.ca.gov/Reports_Research/docs/Data_Points_Dec_2016.pdf. From December 2016, the “Others” population (which includes American Indian, Hawaiian/Pacific Islander, and Asians, many of whom are Vietnamese) consisted of 8,907 individuals incarcerated in the state system (6.9% of the total population of incarcerated people). Of this number, 598 were born in Vietnam (in December 2014, it was 660). See pp. 10, 17, 85 of the report.
 Paws for Life (PFL) is a therapeutic program and unique partnership between the organization Karma Rescue and the California State Prison–LA County that began in 2014. See http://karmarescue.org/paws-for-life/ and also Jackie Fernandez, “CSP-Los Angeles County launches Paws For Life program,” Inside CDCR, 3 July 2014, https://www.insidecdcr.ca.gov/2014/07/csp-los-angeles-county-launches-paws-for-life-program/.
Tin Nguyen has been incarcerated for nineteen years, serving a Life Without the Possibility of Parole sentence. A son, brother, uncle, and capable of change. He is a student in Cal State LA’s BA program, as well as a dog trainer in the “Paws For Life” dog program at Los Angeles County Prison, Lancaster.
Bidhan Chandra Roy is an associate professor of English Literature at California State University, Los Angeles. He is the founder of WordsUncaged, a platform for men sentenced to life sentences in California prisons to dialogue and critically engage with the world beyond the prison walls. He is also the faculty director of Cal State LA’s BA program at Los Angeles County Prison, Lancaster, as well co-chairman of the board of Karma Rescue, an organization that runs the “Paws for Life” dog rescue and training programs in prisons throughout California.
Copyright: © 2018 Tin Nguyen and Bidhan Chandra Roy. This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International License (CC-BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. See http://creativecommons.org/licenses/by/4.0/.