1. Department of Children Welfare, Woosuk University, Wanju, Jeonbuk, Korea;
2. Department of Computer Science, Dongshin University, Naju, Chonnam, Korea;
3. Department of Applied Statistics, Dongguk University, Gyeongju, Gyeongbuk, Korea;
4. Statistics Discipline, Division of Science and Mathematics, University of Minnesota-Morris, Morris, MN, USA