• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.7B
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• pp.1236-1243
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• 2000

본 논문은 LAN의 대역폭을 증가 시키기 위하여, 여러 개의 링크를 논리적인 하나의 링크처럼 동작하도록 하는 다중링크통함(link aggregation)기술에 대한 것이다. 우리는 망 구성에 따라 이 기술의 동작방식이 상이함에 착안하여, 두 가지의 새로운 프레임 분배방식을 제안하고 SIMULA를 이용한 모의실험으로 성능을 분석하였다. 먼저, LAN스위치와 스위치간에 적용 가능한 동적 프로엠 분배방식을 제안하였다. 이 방식은 특정 포트로 집중되는 프레임들을 분산시키기 위하여 가장 이용율이 낮은 링크를 동적으로 추가하는 것으로서, 링크 추가시 프레임들의 전달순서를 지킬 수 있도록 특별한 플러쉬 버퍼를 사용하였다. 모의실험 결과, 프러임간의 순서가 유지되면서도 스위치의 내부 버퍼에서의 프레임 폐기율이 기존 방식에 비해 감소됨을 확인하였다. 그리고, 단말과 단말간에 다중링크가 사용된 경우, 수신된 프레임들 간의 순서 뒤바뀜 문제에 대한 해결책으로 패딩 방법과, 태깅 방법, 프레임 분할 방식 등의 세가지으 프레임 분배방식을 제안하고 성능을 분석하였다. 이러한 세가지 방법 중에서 프레임 분할방식이 가장 성능면에서 우수함이 모의실험결과\ulcorner서 알 수 있지만, 패딘 방식도 구현관점에서 장점이 있다.

• The Korean Journal of Applied Statistics
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• v.27 no.6
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• pp.909-922
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• 2014

This paper reviews Bayesian inference with inequality constraints. It focuses on ⅰ) comparison of models with various inequality/equality constraints on parameters, ⅱ) multiple tests on equalities of parameters when parameters are under inequality constraints, ⅲ) multiple test on equalities of score parameters in models for contingency tables with ordinal categorical variables.

• Proceedings of the Korean Statistical Society Conference
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• 2005.11a
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• pp.101-105
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• 2005

호남지역에 대한 대설특보 예보를 위한 통계모형 개발을 수행하였다. 일 신적설량에 따라 세법주(0: 비발생, 1: 대설주의보, 2: 대설경보)로 구분되는 순서형 자료 형태를 지니고 있다. 두가지 통계 모형(다등급 로지스틱 회귀모형, 신경회로망 모형)을 고려하였으며, 수치모델 출력자료를 이용한 역학-통계모형 기법의 하나인 MOS(model output statistics)를 적용하여 축적된 수치모델 예보자료와 관측치의 관계를 통계모형식으로 추정하여 예측모형을 개발하였다. 군집분석을 사용하여 훈련자료와 검증자료를 구분하였으며, 예보치 생성을 위하여 문턱치를 고려하였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.16 no.12
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• pp.1300-1312
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• 1991

In this paper we syudy the time slot sequence integrity(TSSI) of multi-slot calls in the single-buffered switching networks and analyze their traffic characteristics in terms of traffic mixture ratio, number of random searches for idle time slots, and their blocking probablities. This result can be utilized in the design of wideband switching networks in the single buffered systems, such as TDX IA/B swithcing systems, for accommodating multi slot calls.

• Proceedings of the Korean Information Science Society Conference
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• 2006.06b
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• pp.121-123
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• 2006

베이지안 네트워크 병합은 여러 개의 베이지안 네트워크를 하나의 네트워크로 합치는 것을 말한다. 일반적으로 사용되는 병합 알고리즘은 병합 순서에 따라 최종결과 네트워크의 복잡도가 달라지는 문제를 갖고 있고, 최종 병합 네트워크의 에지 수를 최소화하는 병합 순서를 찾는 것은 NP-hard라고 증명되었다. 본 논문에서는 최적의 병합 순서를 결정하기 위해 진화 알고리즘을 사용하는 방법을 제안한다. 해공간 분석을 통해 permutation index 표현방법이 해탐색에 유리함을 보이고 이를 이용한 진화 알고리즘을 제안한다. 실험결과, 기존의 휴리스틱과 greedy 탐색 방법에 비해 제안한 방법이 우수한 성능을 보였다.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.12 no.6
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• pp.636-642
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• 2019

In this paper, we analyzed BER (Bit Error Rate) communication performance according to the detection order of MMSE (Minimum Mean Square Error) based soft decision interference cancellation. As the detection order method, antenna index order method, absolute value magnitude order method of channel elements, absolute value sum order method of channel elements, and SNR (Signal Noise Ratio) order method are proposed. BER performance for the scheme was measured and analyzed. As a simulation environment, 16-QAM (Quadrature Amplitude Modulation) modulation is used in an uncoded environment of an M×M multiple-input multiple-output system, and an independent Rayleigh attenuation channel is considered. The simulation results show that the performance gain is about 1.5dB when the SNR-based detection order method is M=4, and the performance gain is about 3.5dB when M=8 and about 3.5dB when M=16. The more BER performance was confirmed, the more the detection order method of the received signal prevented the interference and error spreading occurring in the detection process.

• Journal of the Korean Institute of Intelligent Systems
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• v.15 no.6
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• pp.661-667
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• 2005

In this paper, we propose a new hybrid genetic algorithm for sequential ordering problem (SOP). In the proposed genetic algorithm, the Voronoi quantized crossover (VQX) is used as a crossover operator and the path-preserving 3-Opt is used as a local search heuristic. VQX is a crossotver operator that uses the epistasis information of given problem instance. Since it is a crossover proposed originally for the traveling salesman problem (TSP), its application to SOP requires considerable modification. In this study, we appropriately modify VQX for SOP, and develop three algorithms, required in the modified VQX, named Feasible solution Generation Algorithm, Precedence Cycle Decomposition Algorithm, and Genic Distance Assignment Method. The results of the tests on SOP instances obtained from TSPLIB and ZIB-MP-Testdata show that the proposed genetic algorithm outperforms other genetic algorithms in stability and solution quality.

• The Korean Journal of Applied Statistics
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• v.31 no.6
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• pp.825-833
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• 2018

We examined the relationship between the order of signs and the order of vote within parties in electing local district councilors during the 7th nationwide local election held on June 13th, 2018. We analyzed election data for respective cases that include two, three, four candidates within the same party. In most cases, the candidate with sign 'Ga' gained more than other candidates in the same party, showing a need for provisional measures. In addition, a difference in voting tendency was found between in-house voting and early outside voting when there were two candidates in the Democratic Party of Korea as well as for when there were two candidates in the Liberty Korea Party.

• Journal of the Korean Data and Information Science Society
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• v.27 no.2
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• pp.373-380
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• 2016

Even though Likert type data is ordinal scale, many researchers who regard Likert type data as interval scale adapt as parametric methods. In this research, simulations have been used to find out a proper analysis of Likert type data. The locations and response distributions of five point Likert type data samples having diverse distribution have been evaluated. In estimating samples' locations, we considered parametric method and non-parametric method, which are t-test and Mann-Whitney test respectively. In addition, to test response distribution, we employed Chi-squared test and Kolmogorov-Smirnov test. In this study, we assessed the performance of the four aforementioned methods by comparing Type I error ratio and statistical power.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.8
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• pp.2113-2119
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• 1998

The optimization problem of BDDs plays an improtant role in the area of logic synthesis and formal verification. Since the variable ordering has great impacts on the size and form of BDD, finding a good variable order is very important problem. In this paper, a new variable ordering scheme called incremental optimization algorithm is presented. The proposed algorithm reduces search space more than a half of that of the conventional sifting algorithm, and computing time has been greatly reduced withoug depreciating the performance. Moreover, the incremental optimization algorithm is very simple than other variable reordering algorithms including the sifting algorithm. The proposed algorithm has been implemented and the efficiency has been show using may benchmark circuits.