Staff Bios

Leadership Team


Jun Usaka, President

Mr. Usaka is President of Second Language Testing, Inc. (SLTI), Princeton, NJ, where he provides leadership and oversight of test development, test item writing, and test translation. He also develops and manages new business opportunities. From 2016, he has assumed responsibilities of the Global Test of English Communication (GTEC) expansion project as Global Director, being responsible for collaboration and implementation across Benesse group companies.

Throughout his career, Mr. Usaka has served as an administrator and product manager in the education industry. In 2008, Mr. Usaka joined Berlitz Corporation as an executive assistant to the CEO and later became a manager of the corporate strategy department to engage in numerous international projects. In 2010, Mr. Usaka served as the global leader of Berlitz Kids & Teens and revitalized the business by leading key initiatives. From 2014, he assumed the position of worldwide director of Berlitz Kids & Teens where he managed the business in 40 countries worldwide as product manager.

Prior to joining Berlitz, Mr. Usaka worked for Benesse Corporation, where he closely cooperated with school teachers and educators to help students’ academic success as well as support their career development. During his career at Benesse, Mr. Usaka promoted various testing and assessment products to schools, including but not limited to GTEC for STUDENTS and other diagnostic assessments. He also conducted International English assessments and education research projects in South Korea, China, and Japan as the project leader, and was involved in establishing the All Japan High School English Debate Association.

In 2007, Mr. Usaka was selected as the ambassador of Rotary International Ambassadorial Scholarships for graduate management study, and he earned his MBA degree at the University of Michigan, Ross School of Business in 2008, with a concentration in Corporate Strategy and Marketing. He obtained his BA degree at Tohoku University, where his areas of study were East Asian political history and philosophy. He has published an article in Education Public Opinion, and he has presented on language education across various media.


Charles W. Stansfield, Ph.D., President Emeritus

Dr. Charles W. Stansfield is the Founder and President Emeritus of SLTI and is an authority on second language testing. He has developed and published proficiency tests in English as a second language and in 15 other languages. He is the author or editor of over a dozen books and research monographs and 50 research articles published in professional journals. He is currently a member of the editorial boards of Language Testing and the Journal of Second Language Writing. Since 1994, when SLTI was incorporated, Dr. Stansfield has devoted himself full-time to the management of SLTI projects. During his 40-year career, he has also served as a secondary school teacher of Spanish, a tenured professor of Spanish and teacher trainer at the University of Colorado, a test program administrator at Educational Testing Service, director of the ERIC Clearinghouse on Languages and Linguistics, and director of the Division of Foreign Language Education and Testing at the Center for Applied Linguistics in Washington, DC.

Test Development Team

The Team


Rachel Kim

Rachel Kim is a test production and asset management specialist at SLTI.  Ms. Kim has played a major role in the translation and layout of several high stakes state exams and the parental information letters associated with these exams. She continues to play an increasingly important role in the test translation component of SLTI’s business. Prior to joining SLTI, Ms. Kim served as a freelance graphic designer at Weather Bug, PICTO Lab, Future Media Concepts, and IPAS Tech & Design Inc. Ms. Kim received a BA in Imaging Digital Art from The University of Maryland Baltimore County. Her software proficiencies include Adobe Photoshop, InDesign, Illustrator, Flash, Dreamweaver, Premiere, and various other design applications. She has experience with composition, page layout and design, multimedia development, digital video editing, photo image development, retouching and color correction, image slicing, web development, desktop publishing, and basic html. In addition to her extensive knowledge of graphic and digital imaging design, Rachel is also fluent in both English and Korean.  She has worked at The Korean American Christian Heritage Institute and currently teaches Korean at Howard County Community College.

Olga Pereira

Olga Pereira is a test production and asset management specialist at SLTI. She has participated in a number of projects involving translation and layout, including the New Jersey Assessment of Skills and Knowledge, the New Mexico Standards Based Assessment, the Massachusetts Comprehensive Assessment System, and the Edvantia-Linguafolio project. Ms. Pereira received a BA in International Relations from the University of Maryland, College Park and a degree in Information Technology from Montgomery College. She has a broad proficiency with design software, including Adobe products (e.g. InDesign, Photoshop, Illustrator) and various other design applications. Prior to joining SLTI, Ms. Pereira worked in the Communications Department of Montgomery College and for the Washington Times.

Alexa Kaltenberg

Alexa Kaltenberg is a test developer at SLTI. She obtained a B.A. in Spanish Studies at the University of Minnesota Twin Cities and a graduate certificate in TESOL at the University of Wisconsin River Falls. For the last three years, she has been teaching academic English to students from all over the globe at ELS centers in both Grand Forks, North Dakota and Houston, Texas.

Andy Tang

Andy is a Test Developer at SLTI. He has a Master’s of Cognitive Science and Language with a specialization in Linguistics from the Universitat de Barcelona. There, his coursework ultimately culminated in a thesis about the link between creativity and trilingualism. He has a BS in Biology with minors in Linguistics and Psychology from Syracuse University. For three years on and off, he has taught English as a Foreign Language to learners of all ages in various countries of South America and East Asia, namely in Caotun, Taiwan; Lima, Perú; and Jingjiang, China. He is eager to create unbiased cultural content and language services for a global audience. Andy is also a firm believer in the direct method of language learning, and he speaks conversational Spanish and conversational Mandarin.

Jerome Quelin

Jerome Quelin is a test developer at SLTI. A native of Versailles, France, he has over seven years of experience as a teacher and researcher in French language, culture, and literature. Jerome holds a B.A. in Comparative Literature from Emory University, and a M.A. in French Literature from Princeton University. After teaching French to adults, graduate students, undergraduates, and more recently high school students, he is thrilled to join SLTI where he looks forward to deepening his knowledge of second language testing and making a valuable contribution as a member of the test development team.

Kristen Cooper

Kristen Cooper is a test developer at SLTI.  She has over 12 years of Spanish language education experience.  She has studied in several locations in the Spanish-speaking world, including Spain, Peru and Bolivia.  She previously worked in public education, teaching Spanish language, culture and literature to students in grades K-12.  She has also designed thematically based, communicative curricula to promote language acquisition and increase proficiency for multiple school districts.  She holds a B.A. in Spanish and History from Rider University and a M.A. in Teaching from Rutgers University.

Liubou Shefarevich

Liubou is a Project Lead at SLTI. She majored in Linguistics, TESOL and German at Minsk State Linguistics University, Belarus. She holds a BA in Linguistics and an MA in Applied Linguistics from Montclair State University. During the course of her studies, she participated in numerous research projects by faculty members in such areas as code-switching, morphology, and prosody. The projects involved a range of languages: from Spanish and Tagalog to Upper Sorbian and Albanian. She also contributed her research expertise to privately-led product development projects. Liubou speaks Russian, Belarussian, Spanish, and German.

Mark Riggleman

Mark is a Project Lead at SLTI. He has a BA in Linguistics and in German Literature from the College of William and Mary and an MA in Foreign Language Education from the same institution. Mark previously worked as a content lead developing EFL materials for the Japanese and Korean markets. He also helped create foreign language products for German, Pashto, Irish, Swedish and Hebrew. Mark is proficient in German, and he hopes to reach that same level in his Irish one day.

Payman Vafaee

Payman Vafaee is a project lead at SLTI. He has a Ph.D. in Second Language Acquisition from the University of Maryland (UMD). Prior to UMD, Payman completed two years of a doctoral program of Applied Linguistics at Columbia University. Before joining SLTI, Payman worked as a researcher, psychometrician, test item writer and reviewer, second language teacher trainer and instructor (English and Persian) at Center for Advanced Study of Language (CASL), the Persian Flagship program at UMD, Oxford University Press, and Teachers College of Columbia University.

Payman conducts research in the areas of second language testing and assessment, instructed second language acquisition, task-based language teaching and testing, and cognitive individual differences in second language acquisition. He has publications in academic journals such as Studies in Second Language Acquisition, and he has presented his research at numerous international conferences, including Language Testing Research Colloquium (LTRC), East Coast Organization of Language Testers (ECOLT), and Second Language Research Forum (SLRF), Roundtable on Learning Oriented Assessment (TCCRISLS), and Georgetown University Round Table on Languages and Linguistics (GURT).

Paul Bartley

Paul H Bartley is the newest member of the SLTI test-development team. Prior to joining SLTI, Paul worked for eleven years as an ESL/EFL teacher at a variety of institutions, most notably in Prague, NYC, and Cincinnati, Ohio. From 2010 to 2016, Paul taught in the EAP (English for Academic Purposes) program at ELS Cincinnati, where he also functioned as local coordinator for the GTEC CBT 2014 and 2015 field tests. Additionally, while at ELS, Paul served as a Speaking and Writing Examiner for the International English Language Testing System (IELTS). Paul has a B.A. in English Literature from the University of Cincinnati, and a TEFL Certificate from NLLI in Prague, CZ.