• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2000.10a
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• pp.307-312
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• 2000

In this paper, in order to improve the performance of TCP short traffic services in wireless Internet environments, the Split-ACKs(SPACK) scheme is proposed. In wireless networks, unlike wired networks, packet losses will occur more often due to high bit error rates. Therefore, each packet loss over wireless links results in congestion control procedure of TCP being invoked at the source. This causes severs end-to-end performance degradation of TCP. In this paper, to alleviate the TCP performance, the SPACK method split acknowledgement packets in the base station is proposed. Using computer simulation the performance of TCP using SPACK is analyzed and shows better performance than traditional TCP protocol.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.5
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• pp.923-930
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• 2001

In this paper, in order to improve the performance of TCP short traffic services in wireless Internet environments, the Split-ACKs(SPACK) scheme is proposed. In wireless networks, unlike wired networks, packet losses will occur more often due to high bit error rates. Therefore, each packet loss over wireless links results in congestion control procedure of TCP being invoked at the source. This causes severe end-to-end performance degradation of TCP. In this paper, to alleviate the TCP performance, the SPACK method, split acknowledgement packets in the base station, is proposed. Using computer simulation, the performance of TCP using SPACK is analyzed and shows better performance than traditional TCP protocol.

• Journal of the Earthquake Engineering Society of Korea
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• v.5 no.6
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• pp.65-76
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• 2001

Determination of ductility demand and prediction of nonlinear seismic responses of a structure under the earthquake ground motions have become a very important subject for evaluation of seismic performance in the performance based seismic design. In this study, the system ductility demand and nonlinear seismic responses of the steel moment framed structures by the nonlinear time history analysis are estimated and compared with those obtained from the capacity spectrum method suggested in ATC-40 and proposed method that is an improvement on the capacity spectrum method using the equivalent responses derived directly from a multi degree of freedom system. the adequacy and validity of the proposed method is verified by comparing the results evaluated by the method proposed in this study and the results obtained from method suggested in ATC-40 to the nonlinear seismic responses of the example structures from the nonlinear time history analysis.

• The Korean Journal of Applied Statistics
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• v.27 no.7
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• pp.1229-1241
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• 2014

Most of sampling surveys have outliers and non-response missing values simultaneously. In that case, due to the effect of outliers, the result of imputation is not good enough to meet a given precision. To overcome this situation, outlier treatment should be conducted before imputation. In this paper in order for reducing the effect of outlier, we study outlier imputation methods and outlier weight adjustment methods. For the outlier detection, the method suggested by She and Owen (2011) is used. A small simulation study is conducted and for real data analysis, Monthly Labor Statistic and Briquette Consumption Survey Data are used.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.44 no.1
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• pp.25-32
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• 2007

In this paper, a new method for first order plus dead time(FOPDT) model identification is proposed, which can identity multiple points on a process step response in terms of classification of time response. The process input and output to the test are decomposed into the transient part and the steady-state part. The steady-state part express one FOPDT model and the transient part express variously FOPDT model using least square estimation method. The optimum parameter tuning algorithm for PID controller of the Smith Predictor is proposed through ITAE as performance index. The Simulation results show the validity and improvement of performance for various processes.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.5
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• pp.125-133
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• 2006

This paper presents comparison results of Step Response Model of Dynamic Matrix Control(DMC) for a drum-type boiler-turbine system of a fossil power plant. Two possible kinds of step response models are investigated in designing the DMC, one is developed with the linearization of theoretical model and the other is developed with the process step-test data. Then, the control performances of each model-based DMC are simulated and evaluated. It is observed that the simulation results with the step-response model based on the test data show satisfactory results, while the linearized model is not suitable for the control of boiler-turbine system.

• KEPCO Journal on Electric Power and Energy
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• v.6 no.4
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• pp.439-445
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• 2020

In this paper, the seismic performance evaluation was performed on 100 existing open-cut power cable tunnels, including ones that did not consider seismic design, in order to verify that the government's demand level (seismic special grade, 0.22 g). The results of the seismic performance evaluation show that most of the tunnels have seismic performance of 0.3 to 1 g, satisfying the level of the seismic special grade and securing the seismic safety. Meanwhile, the earthquake response analysis and structural test were performed to verify the validity of the method and the results of the seismic performance evaluation of the tunnels by the response displacement method, and to verify their seismic safety. As a result, the relative displacement due to the response displacement method under the 0.22 g earthquake was conservative than the results of the earthquake response analysis, and the results of load-displacement curves and response modification coefficient calculation by real scale structural tests showed the safety of the tunnels.

• Proceedings of the Korean Society for Cognitive Science Conference
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• 2000.06a
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• pp.190-197
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• 2000

본 연구에서는 사용자의 질의에 대해 대답을 제시하는 질의응답시스템의 평가를 위한 테스트컬렉션을 구축하였다. 질의응답시스템 평가를 위한 테스트컬렉션은 207,067개의 문서, 90개의 질의, 각 질의에 대한 적합성 판정 집합으로 구성되어 있다. 문서집합은 신문기사로 SGML형식으로 가공되었고, 질의는 다양한 유형의 질의와 변형질의를 포함한다. 적합성 판정 집합은 각 질의에 대해서 문서에 대답을 포함하는지의 여부에 따라 적합/부적합으로 판정하였고, 적합한 문서에 대해서는 대답을 표시하였다. 본 연구를 통해 구축된 질의응답시스템 평가를 위한 테스트컬렉션은 질의응답시스템의 객관적인 신뢰성 평가를 위한 기반을 마련하였다.

• Proceedings of the Korea Society for Industrial Systems Conference
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• 2000.05a
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• pp.193-199
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• 2000

본 논문에서는 인터넷을 이용한 전자상거래에서 메모리 상주 DBMS를 이용하여 사용자 수가 증가하는 경우에도 최종 사용자에 대한 응답 시간을 빠르게 유지하는 새로운 캐슁 기법을 제안한다. 지금까지 인터넷 서버 시스템 구조의 성능에 관한 연구에서는 멀티-티어(multi-tier)시스템 구조가 제안되었으나 메모리 상주 DBMS를 이용한 새로운 서버 시스템 구조의 연구는 시작단계이다. 본 연구에서는 전자상거래에서 최종 사용자에게 빠른 응답시간을 보장하기 위해 전자상거래용 웹 데이터베이스에서 다수의 사용자가 공통으로 빈번하게 사용하는 hot data를 메모리 상주 DBMS가 관리하도록 하는 성능 향상 방안을 제시한다.

• Proceedings of the Korean Information Science Society Conference
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• 2002.10c
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• pp.376-378
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• 2002

가상 메모리 관리에서 가장 근 문제점은 느린 보조기억 장치의 속도와 빠른 주기억장치의 속도 차이에서 나타나는 성능 저하라고 할 수 있다 요구 페이징 기법에서 Page Fault가 일어나면 페이지 교체 정책에 의해 필요 없는 page들을 swap device로 이동을 시킨다. 이때 느린 보조기억장치의 접근 속도로 인한 응답시간의 지연은 전체적인 시스템 성능의 저하를 초래한다. 그래서 Swap Device로의 접근 횟수와 페이지의 크기를 줄일 수 있다면 Page Out되는 응답시간을 높일 수 있을 것이다. 따라서 본 논문에서는 가상 메모리 압축 시스템을 설계하여 Swap Out 되는 시간을 줄여 시스템의 전체적인 성능 향상을 위한 시스템을 구현한다.