Min-Seok Kim, Ha-Jin Yu, Keun-Chang Kwak and Su-Young Chi,
"Robust Text-Independent Speaker Identification Using Hybrid PCA&LDA,"
Lecture Note in Artificial Intelligence MICAI 2006, LNAI 4293, pp. 1067 - 1074, Nov. 2006.

Ha-Jin Yu, "Speaker Recognition in Unknown Mismatched Conditions using Augmented PCA," ISCIS 2005, Lecture Note in Computer Science 3733, pp. 668-676, Springer-Verlag Berlin Heidelberg Oct. 2005

Ha-Jin Yu, Yung Hwan Oh, "A Neural Network for 500 Word Vocabulary Word Spotting Using Non-Uniform Units", Neural Networks, Elsevier Science Ltd., Volume 13, Issue 6, July 2000, pp. 681-688

Hajin Yu, Yung Hwan Oh, Yoichi Yamashita, Riichiro Mizoguchi, "Fuzzy Expert System for Continuous Speech Recognition," Expert Systems with Applications, Elsevier Science Ltd., Vol. 9, No. 2, 1995, pp. 81-89