• Proceedings of the Korean Statistical Society Conference
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• 2002.05a
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• pp.159-163
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• 2002

직교성은 실험계획에서 중요한 성질이다. 직교계획을 이용할 수 없는 경우 우리는 이러한 근사직교배열에 대하여 직교성의 정도를 평가할 수 있는 측도가 필요하다. 본 논문에서 는 근사직교배열에 대하여 직교성의 정도를 평가할 수 있는 그래픽방법들을 제안하고자 한다.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.16 no.4
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• pp.64-75
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• 2017

Previous count models using fixed parameter can not consider the unobserved heterogeneity, as the standard error of the count value is underestimated, excessive t-values are derived thereby reducing the reliability of the model. Also, the study of unsignalized intersections are inadequate because of the difficulty of collecting data and statistical limits for accurate analytical processes compared to the signalized intersections. The purpose of this study is to analyze the factors affecting traffic accidents by constructing the count model using random parameters, and it aimed to distinguish between existing studies based on the rural unsignalized intersections. As a result of the analysis, 7 variables were presented as significant variables, and 2 variables(presence of crosswalk, speed limit) were presented as random parameter.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.7
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• pp.1224-1233
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• 1994

The error performance of BPSK and QPSK signals in mobile satellite channel is investigated considering nonlinearity of TWTA (Traveling Wave Tube Amplifier) in the presence of AWGN(Additive White Gaussian Noise) on the uplink and downlink paths. It is assumed that the fading on the downlink path forms a Rician distribution. The Rician distribution is approximated by discrete probability values. The values are firstly found by Classical Moment Technique. Finally, the error probability is evaluated using approximate discrete values of Rician distribution and the Gaussian Quadrature Formula.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.33B no.1
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• pp.25-37
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• 1996

To process computer graphics in real time, the high-speed operations(multiplier and adder) are needed to increase the speed of graphic process. RNS(Residue Number System) is integer number system that has the parallel and high-speed operation. Also, it is able to design both high-speed multiplier and adder, since a cyclic group has an isomorphic relation between multiplication and addition in RNS. So in this paper, DRNS(Double Residue Number System) is proposed, it is used for the multiplier and the adder, which are designed using a circulative code for the high-speed graphic processor in RNS. The designed multiplier would operate with the speed of 87Mzz two TTL using 74s09 and 74s32.

• Journal of Korean Society of Transportation
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• v.28 no.2
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• pp.135-150
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• 2010

This paper focuses on finding out which covenants are different among the concession agreements of Korean BTO projects and how these influenced IRR(Internal Rate of Return). That is, to figure out the political and economical determinants of IRR by analyzing the concession agreements which are the basic contract of implementing projects. As IRR is an index of profitability, so spread is an indicator of risk to collect debts. That's the reason why the analysis of spread is included. For the empirical analysis, the data of concession agreements for 75 projects and financial models are used. These 75 concession agreements are contracted from 1995 to 2008. The dependent variables are after tax nominal IRR and the spread of long term interest rates of 75 BTO projects. The independent variables are project's proceeding factors, the feasibility variables, the variables related to financial character and the variables related to covenants or the government's policy. The analysis shows that IRR has been influenced by the equity level of financial investors, the national government managed projects, the projects with minimum revenue guarantee (MRG), etc. And the equity level of financial investors, the national government managed projects and the implementation of supplementary project have an effect on spread also.

• Journal of Korea Technology Innovation Society
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• v.13 no.2
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• pp.365-378
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• 2010

For sustainable economic growth, the Korea government continues to increase its investment in R&D and at the same time, have reinforced the management of R&D outcomes and enlargement of its infrastructure for utilization. However, a strategic R&D planning that draws an outstanding outcomes is more important than the management of its post-outcomes. The purpose of this study is to propose an implication on the policy of R&D planning for obtaining a good R&D outcomes such as a high quality patent. We compared and analyzed the determinants of the patent quality in fuel cell and solar cell technology using the count data models. Estimated results showed that the determinants of the patent quality in technologies were different from each other. Therefore, having appropriate R&D planning strategies for all technologies was more effective than applying one same strategy for all because of technological differences, and based on the estimated results, we suggested the R&D planning strategy in fuel cell and solar cell technologies that could in result in high R&D outcomes.

• The Korean Journal of Financial Management
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• v.22 no.1
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• pp.93-118
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• 2005

This paper examines credit spreads in Korea corporate market using one of structural models, the mean reverting leverage ratio model (Collin-Dufresne and Goldstein (2001)). Compared to the actual credit spreads, we show that the credit spreads induced by the model are overpredicted. We also investigate the systematic errors that cause the over-pre-diction of credit spreads using the t-test. We show that the systematic errors are affected by the current leverage ratio and asset volatility.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.8A
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• pp.1298-1310
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• 2001

이 논문에서는 채널 상태가 천천히 변할 때, 직교 주파수 분할 다중화-부호분할 다중접속 시스템에 적합한 채널 추정 방법을 제안하고 성능을 분석한다. 제안한 채널 추정 방법은 시간과 주파수 영역 모두에 파일럿 심볼을 삽입하고, 이산 퓨리에 변환 후 영을 채워 넣는 방법을 이용한 내삽법으로 모든 부채널의 전달 함수를 얻는다. 또한 변환 영역에서 저대역 여파를 통해 받은 파일럿 신호에 존재하는 가산성 백색 정규 잡음의 영향을 상당히 줄일 수 있다. 이 때 저대역 여파기의 차단 주파수는 채널의 다중경로 수에 따라 정해진다. 같은 방법을 이용한 내삽법을 시간축으로 적용하여 시간에 따라 변하는 부채널의 채널 응답을 얻을 수 있다. 이 논문에서는 여러 가지 내삽법에 대한 평균 제곱 오차 성능을 수식적으로 제시한다. 제안한 저대역 여파를 결합한 내삽법을 쓰면 채널의 통계적 특성에 관한 정보 없이, 그리고 훨씬 적은 계산량으로 선형 최소 평균 제곱 오차 추정기와 비슷한 성능을 얻는다. 레일리 감쇄 채널에 대한 모의 실험을 통해 같은 비트 오류율에 대한 신호 대 잡음 비의 이득이 있음을 보인다.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.6
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• pp.198-206
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• 1999

An automobile outside rear view mirror system has been analyzed and designed to reduce vibration with a finite element model. model analysis is conducted for the calculation of natural frequencies. harmonic analysis is utilized to estimate the displacements of the glass surface under dynamic loads. The model is verified with the vibration experiment of the parts and the assembled body. The structure of the mirror system is optimized for the robustness defined by the Taguchi concept. At first, many potential design variables are defined. Final design variables are selected based on the amount of contribution on the objective function. That is, sensitive variables are chose. The SN ratio in the Taguchi method is replaced by an objective function with the mean and the standard deviation of the quality characteristic. The defined objective function is appropriate in the structural design in that the vibration displacements are minimized while the robustness is improved.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.4
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• pp.1019-1026
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• 1996

A modulation type classifier based on statistical moments has been successfully employed to classify PSK signals. Previously, developed Classifiers were analyzed in AWGN channel only. In this paper, a moments-based modulation type classifier to classify BPSK and QPSK signals over Rayleigh fading channel is proposed and analyzed. The moments of received signal are evaluated with the exact distribution of the received signal and a moments-based classifier is proposed. The performance evaluation of the proposed classifier in terms of the misclassification probability for BPSK and QPSK is investigated under Rayleigh fading environment.