• 한국자동차공학회논문집
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• 제19권5호
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• pp.35-44
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• 2011

In a spark ignition engine, a variable valve lift (VVL) system has been developed for high fuel efficiency and low power loss. However, changes in valve lift cause deviations of cylinder air charge which lead to individual cylinder equivalence ratio maldistribution. In this study, in order to reduce the maldistribution, we propose individual cylinder equivalence ratio estimation and control algorithms. The estimation algorithm calculates the equivalence ratio of each cylinder by using a mathematical engine model which includes air charging, fuel film, exhaust gas, and universal exhaust gas oxygen sensor (UEGO) dynamics at various valve lifts. Based on the results of estimated equivalence ratio, the injection quantity of each cylinder is adjusted to control the individual cylinder equivalence ratio. Estimation and control performance are validated by engine experiments. Experimental results represented that the equivalence ratio maldistribution and variation are decreased by the proposed algorithms.

• Journal of Electrical Engineering and Technology
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• 제13권1호
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• pp.240-249
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• 2018

Individual DC voltage balance problem is an inherent issue for cascaded H-bridge (CHB) based converter. When the CHB-based static synchronous compensator (STATCOM) is operating at zero current mode, the software-based individual DC voltage balancing control techniques may not work because of the infinitesimal output current. However, the different power losses of each cell would lead to the individual DC voltages unbalance. The uneven power losses on the local supplied cell-controllers (including the control circuit and drive circuit) would especially cause the divergence of individual DC voltages, due to their characteristic as constant power loads. To solve this problem, this paper proposes an adaptive voltage balancing module which is designed in the cell-controller board with small size and low cost circuits. It is controlled to make the power loss of the cell a constant resistance load, thus the DC voltages are balanced in zero current mode. Field test in a 10kV STATCOM confirms the performance of the proposed method.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권10호
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• pp.4808-4824
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• 2016

Signal individual reconnaissance and identification is an extremely important research topic in non-cooperative domains such as electronic countermeasures and intelligence reconnaissance. Facing the characteristics of the complexity and changeability of current communication environment, how to realize radiation source signal individual identification under the low SNR conditions is an emphasis of research. A novel emitter individual identification method combined bi-spectrum analysis with wavelet feature is presented in this paper. It makes a feature fusion of bi-spectrum slice characteristics and energy variance characteristics of the secondary wavelet transform coefficient to identify MFSK signals under the low SNR (signal-to-noise ratios) environment. Theoretical analyses and computer simulation results show that the proposed algorithm has good recognition performance with the ability to suppress noise and interference, and reaches the recognition rate of more than 90% when the SNR is -6dB.

• 한국안광학회지
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• 제13권3호
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• pp.61-64
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• 2008

목적: 정시안의 임상자료를 기초로 설계한 개별모형안의 파장에 따른 수차 변화를 분석하였다. 방법: 측정된 안구의 임상 자료를 기초로 설계한 모형안은 4개의 굴절면과 균일한 굴절률을 갖는 형태로 설계하였다. 설계한 12안의 개별모형안에 대하여 프라운호퍼선 6개의 파장 변화를 주어 그에 따른 수차 변화를 분석하였다. 결과: 각 모형안에 대하여 파면수차의 파장에 따른 변화를 Zernike 계수로 분석한 결과 파장이 짧을수록 Defocus는 증가하였고 구면수차(spherical aberration)와 RMS는 개별모형안간의 편차가 크게 나타났다. 결론: 파장의 변화에 따른 Defocus양은 12안의 개별모형안이 비슷한 기울기로 짧을수록 크게 나타났고, 구면수차(spherical aberration)와 RMS는 대부분의 모형안의 경우 변화가 적었으며, 변화가 크게 나타난 일부 모형안은 성능 저하가 발생될 수 있다.

• 수산해양교육연구
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• 제27권1호
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• pp.1-12
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• 2015

This article starts with a review of the system characteristic(easiness, flexibility, reliability) and individual characteristic(self-efficacy, achievement motive, computer ability) through education satisfaction especially in relation to the education performance(perceived usefulness, educatee value). We found that all variables significantly affect the education satisfaction, but only computerized ability doesn't significantly affect the education satisfaction. Education satisfaction significantly affect the education performance. This paper suggests that the followings; first, response time of systems is valuable factor in KcLep. Second, self-efficacy and achievement motive are more important then computer ability in KcLep educatee. Finally, software developer and teacher always think about rapid response time of systems and exchange of data for the education performance in KcLep.

• 정보기술응용연구
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• 제3권4호
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• pp.1-18
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• 2001

본 논문은 그룹 성과모형, 그룹 프로세스 유형, 그룹의 장단점을 살펴보았고, 현존하는 그룹웨어와 회의 지원시스템에 대해 조사하였다. 특히, 대부분의 기업에서 중요시하는 신상품 개발 팀의 업무 성과를 높이기 위한 방안으로 그룹 지원시스템이 제공해야 할 기능에 대해 논의하였다. 신상품 개발 팀을 위한 그룹 지원시스템은 프로세스에 참여하는 모든 구성원이 언제든지(Anytime), 어디에서든지(Anyplace) 신상품개발을 위해 협력할 수 있도록 지원기능을 제공하는 시스템이라 볼 수 있다. 지원시스템이 그룹의 성과를 높이려면 필요시에는 개별성, 병렬성, 익명성을 보장할 수 있어야 하며, 팀원 개인이 수행하는 업무와 공동으로 수행하는 업무를 둘 다 지원할 수 있어야 하고, 사전준비, 회의진행, 사후정리의 모든 과정에서 그룹 프로세스를 지원하면서 구성원의 창의력을 촉발시키고 그룹의 약점을 보완해주는 기능을 갖추어야 한다.

• 노동경제논집
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• 제31권3호
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• pp.47-74
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• 2008

본 연구는 임금과 생산성의 관계에 대한 선행 연구에서 근호자의 생산성 지표로서 인사고과 정보를 활용한 Medoff and Abraham과 Flabbi and Ichino의 연구를 한국 대기업의 인사데이터(2000년, 제조업 근로자)에 적용하여 재현하였다. 임금함수의 OLS 추정과 임금 및 인사고과 분포를 활용한 다항로짓함수 추정을 통해 분석한 결과, 근로자 개인의 생산성을 통제한다고 하더라도 연공임금은 계속 나타났다. 이는 선행연구와 동일하게 연공임금을 설명함에 있어 인적자본 이론보다는 인센티브 이론이 더 적절하다는 것을 시사한다.

• 한국경영과학회지
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• 제40권4호
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• pp.145-156
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• 2015

Incorporation of individual learning and forgetting behaviors within worker-task assignment models produces a mixed integer nonlinear program (MINLP) problem, which is difficult to solve as a NP hard due to its nonlinearity in the objective function. Previous studies commonly assume homogeneity among workers in workforce scheduling that takes account of learning and forgetting characteristics. This paper expands previous researches by considering heterogeneous individual learning/forgetting, and investigates the impact of worker heterogeneity in initial expertise, steady-state productivity, learning and forgetting on system performance to assist manager's decision-making in worker-task assignments without tackling complex MINLP models. In order to understand the performance implications of workforce heterogeneity, this paper examines analytically how heterogeneity in each of the four parameters of the exponential learning and forgetting (L/F) model affects system performance in three cases : consecutive assignments with no break, n breaks of s-length each, and total b break-periods occurred over T periods. The study presents the direction of change in worker performance under different assignment schedules as the variance in initial expertise, steady-state productivity, learning or forgetting increases. Thus, it implies whether having more heterogenous workforce in terms of each of four parameters in the L/F model is desired or not in different schedules from the perspective of system productivity measurement.

• 동아시아경상학회지
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• 제5권2호
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• pp.1-11
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• 2017

This study attempts to verify effects of CEO' supports, compensation and educational training and those of individual annual salaries and company's sales on promotion of knowledge management expected to contribute to enhancing construction industry's competitiveness, from the perspective of person-organization fit. For the analysis, a total of 368 effective questionnaires were used to conduct independent sample t-test, regression analysis and hierarchical moderated regression analysis. The findings show that individual annual salaries have a positive relationship with company's performance and company's sales also have positive relationships with both knowledge management activities and company performance, and CEO's supports, compensation and educational training are important factors that can improve knowledge management activities. In addition, the principle that the rich get richer and the poor get poorer is also operated in construction industry, as in other industries. Therefore, members in a company should conduct optimal strategies to enhance the knowledge management activities through selection and concentration, while governmental agencies require the establishment of IT system for it and supports for related cost and consulting of it.

• 대한안전경영과학회지
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• 제19권1호
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• pp.131-143
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• 2017

The purpose of this study is to review the relationship between CEO's transformational leadership and performance, and the mediating effect of corporate entrepreneurship in entrepreneurs' cooperative. In order to verify and achieve the purposes mentioned above, questionnaire data were gathered and analysed from 379 employees of entrepreneurs' cooperative in Kangwon-do province. Empirical survey's findings are as follows; First, charisma and individual consideration appeared to be positively related with risk-taking and proactiveness. Also, intellectual stimulation appeared to be positively related with proactiveness only. Second, charisma and individual consideration appeared to be positively related with sales volume and employment increase, but intellectual stimulation appeared to be positively related with employment increase only. Third, corporate entrepreneurship(risk-taking, proactiveness) appeared to be positively related with sales volume and employment increase. Fourth, corporate entrepreneurship(risk-taking, proactiveness) had mediating effect on the relationship between CEO's transformational leadership and performance. But, intellectual stimulation had not mediating effect.