• Journal of Labour Economics
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• v.30 no.3
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• pp.43-75
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• 2007

This study reviews the trend of job separation rates for three years from 2002 to 2005 and investigates the various elements which influence this trend, especially the role of the labor unions, by using Korean Labor Panel data. In the basic statistics, the job retention rate of union members were higher by an average of 28.3% points compared to non-union members, but in the results of controlling the observed variables of individual influences in changing jobs, it was estimated that unions increase the job retention rate by 11% to 13% points. To investigate the effect of unions on the job stability of workers in detail, the non-linear decomposition method developed by Fairlie (2003) was used in the analysis. In examining the difference of job separation rates between union members and non-union members through observed variables of workers in explainable parts and unexplainable parts by using the non-linear decomposition technique, the contribution of the explainable part was estimated to be 67% to 74% and the unexplainable part accounted for the rest which was 26% to 33%. This suggests that not only does the union contribute to the job stability of its members, but the propensity to change jobs for a worker who is a union member is on average lower than that of a worker who is not a union member or who works at an establishment that does not have a union. The results of the empirical analysis show that the job stability effect of labor unions is limited within the boundary of a maximum 7% to 9% points. The reason for the effect of labor unions on job stability being so low is due to various reasons such as collective bargaining structure by company, intensified business competition after the financial crisis, and labor market segmentation.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.33 no.1 s.60
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• pp.1-6
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• 2007

It has been generally known that liposomes become unstable when they contain cyclodextrins (CDs). Our present studies demonstrate that these liposomes can be stable by association of amphiphilic polyelectrolytes. Transmission electron microscopy and photocorrelation spectroscopy results showed that polymer-associated liposomes containing CDs (${\beta}-CD$(${\beta}CD$) and hydroxypropyl-${\beta}CD$ ($HP{\beta}CD$)) were more stable than phosphatidylcholine (PC)-cholesterol (Chol) liposomes containing these CDs. We also compared the stability of PC-Chol liposomes with polymer-associated liposomes containing $HP{\beta}CD$ complexed with water-insoluble drug, rhaponticin (Rh). Two liposomes were relatively stable when $HP{\beta}CD$ did not contain Rh, but Rh-$HP{\beta}CD$ complexes triggered the disruption of PC-Chol liposomes. In contrast, polymer-associated Liposomes containing Rh-$HP{\beta}CD$ complexes maintained its stability over 6 months. The skin permeation test demonstrated that drugs solubilized by CDs were delivered better into the skin of guinea pig by using polymer-associated liposomes than by using PC-Chol liposomes. Above results showed that polymer-associated liposomes gave an effective way to stabilize the liposomes containing drug-loaded CDs, which gives an application of liposomes in drug delivery systems.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.2
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• pp.228-236
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• 2012

In this paper, a controller for two wheeled inverted pendulum robot is designed to have more stable balancing capability than conventional controller. Fuzzy control structure is chosen for the two wheeled inverted pendulum robot, and fuzzy membership function factors for the controller are obtained for specified 3 users' weights using trial-and-error method. Next a neural network is employed to generate fuzzy membership function factors for more stable control performance when the user's weight is arbitrarily selected. Through the simulation study we find that the designed fuzzy controller using the neural network is superior to the conventional fuzzy controller.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.5 no.3
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• pp.266-272
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• 2004

In this paper, an observer-based adaptive controller is proposed to control the longitudinal motion of vehicles. The standard gradient method will be used to estimate the vehicle parameters such as mass, time constant, etc. The nonlinear model between the driving force and the vehicle acceleration will be chosen to design the state observer for the vehicle velocity and acceleration. It will be shown that the proposed observer is exponentially stable, and that the adaptive controller proposed in this paper is stable by the Lyapunov function candidate. It will be proved that the errors of the relative distance, velocity and acceleration converge to zero asymptotically fast, and that the overall system is also asymptotically stable. The simulation results are presented to investigate the effectiveness of the proposed method.

• Journal of the Korean Institute of Intelligent Systems
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• v.20 no.4
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• pp.469-475
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• 2010

This paper presents controller design of a two wheeled mobile inverted pendulum robot for one man transportation vehicle. Since the overall mass is varying with different drivers, suitable controller gains are obtained through experimental studies. Variation of the center of gravity due to different masses also affects stable balancing control. Thus, the desired balancing angle si required to be modified with respect to different masses. To measure masses for different drivers, a weight scale is used and those data are used for balancing control through communication. The gain scheduling method of using data obtained from experimental studies allows the robot to have stable balancing performances.

• Proceedings of the KIPE Conference
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• 2011.07a
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• pp.81-82
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• 2011

전력 계통에서 풍력발전기 용량의 증가는 계통운영자에게 계통 신뢰도 및 안정도 유지를 위한 새로운 방법론을 제시하게 한다. 풍력발전기의 불확실성과 가변성은 고스란히 계통에 영향을 끼치며, 계통 운영자는 이로 인해 변화되는 계통 상황을 분석하고 계통 신뢰도 유지를 위한 적절한 기준과 장치를 마련해야 할 것이다. 본 논문에서는 PSCAD/EMTDC를 이용하여 풍력발전기의 용량에 따라 변화되는 선로의 무효전력 및 모선 전압을 검토하고 풍력발전기 전기제어 시스템에서의 제어방식에 따라 계통에 미치는 영향을 평가하였다.

• Polymer(Korea)
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• v.38 no.5
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• pp.671-675
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• 2014

Well-defined star shaped and linear block copolymers were synthesized to study the dispersion stability of copper phthalocyanine (CuPc). We synthesized dispersants using (2-dimethylamino) ethyl methacrylate (DMAEMA) and poly(ethylene glycol) methyl ether methacrylate) (PEGMA) by activators generated by electron transfer (AGET) atom transfer radical polymerization (ATRP). pDMAEMA-b-pPEGMA copolymers were characterized by GPC and NMR. Furthermore, we studied the effect of the dispersion stability of copper phthalocyanine by controlling the degree of polymerization of PEGMA as a stabilizing group. The 4-arm star shaped polymeric dispersant showed better dispersion stability of CuPc at $25^{\circ}C$ for 7 days.

• Proceedings of the Korea Information Processing Society Conference
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• 2015.10a
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• pp.835-838
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• 2015

최근 IT기술이나 하드웨어 기술이 발달함에 따라 공격자의 능력 또한 크게 향상되었다. 이런 공격자를 막기 위해 많은 암호 프로토콜을 사용하여 상호 인증을 하고 암호화 통신을 하거나 PKI 시스템 등을 통해 상호인증을 통한 방어를 하고 있다. 암호화 통신을 할 때 사용되는 AES 알고리즘은 암호학적 안정성과 성능 우수성을 인정받아 국제적으로 많이 활용 되고 있다. 국내에서는 최근 LEA 암호 알고리즘이 개발되었고 AES와 같은 암호학적 안정성 또한 인정받았다. 본 논문에서는 다양한 트래픽 양과 암호화 통신의 유무에 따라 공격자의 존재 유무를 실제 서비스를 하는 서버나 클라이언트가 감지 할 수 있는지에 대해 확인해 보고자 한다.

• Proceedings of the KIPE Conference
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• 2019.07a
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• pp.410-411
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• 2019

본 논문에서는 홀 센서를 사용하지 않고 단상 영구자석 동기 전동기의 초기 회전자 자극을 검출하여 안정적인 오픈루프 기동 및 센서리스 운전 기법을 제안한다. 제안한 회전자 초기 자극 검출 방법은 비대칭 공극을 갖는 단상 영구자석 동기 전동기에 고주파 전압을 인가한 후 회전자 초기 극성에 따른 자기회로의 비 포화 및 포화여부를 저역통과필터를 이용하여 빠르게 검출하는 방법을 제안하였다. 제안된 초기 자극 검출 방법은 다수의 실험 결과를 통해 안정적 기동 및 센서리스 운전이 가능함을 입증하였다.

• 주택과사람들
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• s.204
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• pp.46-49
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• 2007

1997년 아시아 외환위기를 겪은 인도네시아는 아직 환란을 완전히 극복하지 못했다. 환율은 여전히 안정적이지 않고, 부실 대출 비율이 증가하는 등 불안 요인도 많다. 정부 차원에서 외국인 투자 유치를 위한 정책을 내놓는 등 시장 활성화에 힘쓰고 있는 인도네시아 자카르타 부동산 시장을 짚어보았다.