• Management & Information Systems Review
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• v.32 no.3
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• pp.83-105
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• 2013

There are many literatures about the herding behavior of institutional investors but there is lack of literatures about the relation among several investor groups consisting of institutional investors. So we investigate the relation among sub-institutional investor groups like bank, insurance companies, pension funds using KRX intraday trading data of 2009. As the result, we find that foreign, individual, and securities firm investors trade in the opposite direction of other investor groups including pension funds. And pension, insurance, asset management, private equity funds, other companies, government, and banks are cross-mimicking each other, so we conclude that these investors make herding behavior. In 2009 institutional investors except securities firms make herding in a short period, and insurance, asset management, pension funds and other companies make herding and self-mimicking in all period, but there is no herding and mimicking after foreign investors.

• Journal of Korean Society of Transportation
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• v.18 no.6
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• pp.19-32
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• 2000

우리나라 비신호 교차로의 운영방법은 미국과는 다르게 대부분 완전 비제어식 운영(Totally Uncontrol)방법으로 되어있다. 본 연구에서는 우리나라 비신호 교차로들 중 미국 HCM의 TWSC 교차로에 관한 분석방법이 적용 가능하다고 판단되는 비신호 교차로들을 대상으로 임계간격과 추종시간의 기준을 분석하였다. 본 연구에서는 수도권을 중심으로 총 11개의 4-지 비신호 교차로들을 대상으로 이동류별, 차량의 종류별에 따른 차량들의 임계간격과 추종시간을 조사 및 분석하였다. 그 결과 임계간격은 3.8초 - 5.4 초로 나타났으며, 추종시간은 2.4초- 2.7초 범위를 나타내었다. 또한, 임계간격의 경우 차량의 종류별에 따른 차이는 나타나지 않았으나, 이동류별로는 차이를 나타내었다. 이에 반하여, 추종시간은 이동류별에 따른 차이가 없으며, 차량의 종류별에 따라 차이가 존재하는 것으로 분석되었다. 본 연구의 분석 결과인 임계간격과 추종시간의 기준치를 국외 나라들의 연구결과와 비교 분석한 결과는 국외보다 낮게 분석되었으며, 이는 우리나라와 국외의 운전자 운전특성과 비신호 교차로의 운영방식의 차이에서 나타난 결과로 판단된다. 본 연구에서 제안한 임계간격과 추종시간의 기준은 수도권 지역의 4-지 비신호 교차로들 중 주도로와 부도로의 교통량과 속도 등의 현저한 차이가 있는 교차로 분석시 이 기준으로 적용할 수 있고, 우리 나라의 TWSC 방법을 갖는 비신호 교차로에 관한 용량과 지체시간의 이론적 모형 개발과 용량 및 지체시간의 분석을 위한 기초 자료로 활용할 수 있을 것으로 판단된다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.3
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• pp.369-374
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• 2010

Linear motors are easily affected by load disturbances, force ripples, friction, and parameter variations because there are no mechanical transmissions that can reduce the effects of model uncertainties and external disturbance. In this study, a nonlinear adaptive controller to achieve high-speed/high-accuracy position control of a two-axis linear motor is designed. The operation of this controller is based on a cross-coupling algorithm. Nonlinear effects such as friction and force ripples are estimated and compensated for. An enhanced cross-coupling algorithm is proposed for effectively improving the biaxial contour accuracy while achieving closed-loop stability. The proposed controller is evaluated by performing computer simulations.

• Journal of Korean Society of Transportation
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• v.19 no.2
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• pp.89-98
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• 2001

The objective of this Paper is to derive an adjustment factor for the presence of heavy vehicles when estimating capacity at unsignalized intersections (and/or at modern roundabouts). According to the 1997 and 2000 Highway Capacity Manual (HCM), potential capacity in such cases is estimated by simply adjusting base critical gap and base follow-up time. However, the procedure suggested in the HCM may lead to some errors in the adjustment, hence resulting in poor evaluation and design for the intersections, because it determines the value of adjusting factors by only the number of lanes on main streets regardless of the types of heavy vehicles. This paper shows a simple formula for making the adjustment. This formula is much like the HCM formula used for heavy vehicles in estimating highway capacity by the adoption of passenger car units (PCU). In contrast to the traditional approaches seen in the HCM, the PCU value of this case is explicitly expressed by the flow rate in the major streams and the gap difference in critical gaps chosen by passenger cars and particular heavy vehicles. Computational results of the adjustment factor are graphically illustrated.

• Proceedings of the KIPE Conference
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• 2017.11a
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• pp.71-72
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• 2017

본 논문에서는 비선형 최적화 기법을 이용하여 자기 포화(magnetic saturation) 및 교차 결합 현상(cross-coupling effect)을 고려한 매입형 영구자석 전동기(IPMSM)의 실시간 MTPA 제어 방법을 제안한다. 이는 토크 지령 추종과 최소 동손 운전을 만족하는 제한 최적화(constraint optimization) 문제로 접근할 수 있다. 이를 통해 유도한 연립 비선형 방정식의 경우, Levenberg-Marquardt 수치 해석법을 적용하여 안정적이면서 빠르게 해를 구할 수 있다. 이러한 방법을 이용하면 참조표(look-up table) 없이 운전 환경의 실시간 변동을 고려한 효율적인 MTPA 운전이 가능하다. 시뮬레이션을 통해 제안된 알고리즘의 전류 해가 최적 운전점과 일치함을 확인하였다.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.5 s.182
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• pp.93-102
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• 2006

This paper proposes a controller design analysis for three-axis CNC systems considering both contouring and tracking performance. The proposed analysis inclusively combines axial controllers for each individual feed drive system together with cross-coupling controller at the beginning design stage as an integrated manner. These two controllers used to be separately designed and analyzed since they have different control objectives. The proposed scheme includes a stability analysis for the overall control system and a performance analysis in terms of contouring and tracking accuracy. Computer simulation is performed and the results show the validity of the proposed methodology. Further, the results can be used as a basic guideline in systematic and comprehensive controller design for multi-axis CNC systems.

• Korean Journal of Social Welfare
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• v.63 no.1
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• pp.241-266
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• 2011

This study aimed to examine the relationship between students' power types and the roles taken by students in school bullying situation. Four types of power relationship were identified by crossing two dimensions of power relationships among students, which are 'possibility of power acquisition,' and 'need for power acquision.' Salmivalli et al.'s(1996) six particpatants' roles taken by individual student were employed as possible roles for students in school bullying situations. Samples of 1822 cases were analyzed to test the relationships. Results showed that control type youth tend to be bullies, assistants of the bullies, or reinforcers of the bullies; both the followers of bullies and the recluse type youth tend to be victims. Surprisingly influential youth did not take any vivid roles in school bullying situations. Implications as well as suggestions were presented.

• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.1
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• pp.31-37
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• 2008

Traffic flow which is prescribed under previous traffic effect/access act is analyzed by traffic volume, V/C, mean speed on road and LOS on the intersection. These indexes based on analytical method can not consider stochastic characteristics of traffic flow. Moreover it is hard to analyze traffic flow visually in whole traffic effect area because only individual road and intersections are targeted. In this study, it is devised to show traffic flow analysis method within traffic effect area visually applying microscopic-simulation by car-following theory, and then based on this, effect analyze ways are studied according to space range plan, improvement measure establishment and etc. To execute this study, effect area is set up using V/C, and the change of traffic current around development area is analyzed using microscopic-simulation program.

• The Journal of the Korea institute of electronic communication sciences
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• v.12 no.5
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• pp.837-844
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• 2017

The weir to regulate water level in a tide generation tank is above and below carried by two electric cylinders which are mounted on right and left of weir itself. In this case, a movement difference between right and left cylinder causes unbalance of weir and friction between weir and guide. And then, the weir will not be sent to target point. In this study, a synchronous control system is developed to take accurate and quick equilibrium of the weir. The control system based on cross coupled structure consists of two I-PD controllers and a lead compensator. Each of the I-PD controllers is designed in order that the electric cylinder may exactly follow the reference signal without overshoot and input saturation. And the lead compensator is designed to achieve stable and accurate synchronization. Finally, the simulation result shows that the designed synchronous control system is effective for elimination of synchronous error.

• 한국HCI학회:학술대회논문집
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• 2008.02b
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• pp.7-12
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• 2008

This study aims to extract the factors which constitute use tendency on digital product, and to devide korean generation. We surveyed to digital product users who are 15 through 49 years old, executed factor analysis, cluster analysis, and so on, The results of factor analysis, we selected 11 factors, named as interest, entertainment, simplicity, anxiety of mal-operation, practicality, personality, consistency, multi-functionality, learning style of how-to-use, responsibility of disorder, and lending degree. The results of cluster analysis, we classified subjects into following three types: positive acceptor, passive follower, and conservative indifference. And, we executed frequency analysis iteratively. We devide korean digital product users to 4 generations -1727G, 2834G, 3538G, 3949G- by means of synthesizing the results. It can be said that generation is strong factor effect to use tendency, but the other factors like sex, occupation, school career, income become weak factor or not matters. Finally, we considered the reason, 3538G takes a crossing point role through comparison the generation division with cohort research on product use experience.