• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.8
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• pp.574-581
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• 2019

This paper investigates the effects of thrust misalignments and offsets of the lateral center of gravity of a space launch vehicle on its guidance performance. Sensitivity analysis and Monte Carlo simulations are applied to analyze their effects by computing changes in orbit injection errors when including the error sources. To compensate their effects, the attitude controller including an integrator additionally and the Steering Misalignment Correction (SMC) routine of the Saturn V are considered, and then Monte Carlo simulations are performed to evaluate their performances.

• Journal of Labour Economics
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• v.39 no.1
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• pp.33-55
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• 2016

This paper examines the role of adverse working environments in the determination of workers' compensation in South Korean. I use the Third Korean Working Conditions Survey(2011), Occupational Safety and Health Research Institute that provide relevant variables in objective and subjective compensation and workers of diverse working environment. I find that risk factors in adverse working environments have a very minor role in the determination of individual wages. In contrast, adverse working environments have significant relationship with the level of compensation satisfaction. In addition, the results show that workers are more likely to receive compensation from psychological risk than physical risk. And women receive much more compensation in the psychological risk. These results provide useful information for improvement of working environments.

• 월간산업보건
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• s.288
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• pp.45-49
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• 2012

• Electronics and Telecommunications Trends
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• v.18 no.2 s.80
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• pp.53-66
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• 2003

고출력 증폭기(HPA)는 위성통신 등 무선통신 시스템의 송신단에서 필수적으로 요구되는 요소 중의 하나이다. 그러나, 대부분의 HPA들은 비선형적인 출력 특성을 가지고 있으므로 이로 인한 신호의 왜곡으로 전송 손실을 야기하게 된다. 이러한 문제점을 해결하기 위하여 HPA를 선형화하는 가장 효율적인 방법으로 제안되어온 것이 사전왜곡(predistortion) 기법이다. 본 고에서는 고출력 증폭기의 비선형성을 보상하기 위한 사전왜곡 방식의 기본 개념과 다양한 사전왜곡 방식에는 어떤한 것들이 있는지 그 기본 원리 및 기술 개발 동향에 관하여 고찰한다.

• Proceedings of the KIEE Conference
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• 2004.07d
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• pp.2158-2160
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• 2004

본 논문에서는 불확실한 비선형 시스템에 대하여 새로운 고장진단 방법을 이용한 고장 허용 제어기를 설계한다. 잔류 신호는 비선형 관측기 구조를 이용하여 얻을 수 있다. 고장 성분은 neuro-fuzzy 근사기로 추정한다. 제안된 고장 허용 제어기는 강인 제어기와 고장 성분을 보상할 수 있는 보상제어기로 구성된다. 여기서 제안된 고장진단 방법은 고장으로 인해 발생되는 보상제어기의 크기로 고장을 진단함으로써 고장 전후의 강인 제어기의 특성을 계속유지 할 수 있게 설계하였다. 본 논문에서 제안한 고장 허용 제어기의 성능은 컴퓨터 모의실험을 통하여 증명하였다.

• The Journal of the Korea Contents Association
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• v.17 no.4
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• pp.108-118
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• 2017

This study focuses on an effectiveness of socially recommended advertising on social network sites (SNSs) and investigates the impact of three critical factors on SNS advertising effectiveness - reward type for advertising recommenders' intention, product type on advertisements, and tie strength. A $2{\times}2$ factorial design was used to test the interaction effects between the two variables, reward type and product type on advertisements, moderated by tie strength. The results indicate that when participants observe socially recommended advertising, hedonic product ads with non-monetary reward shows the most effectiveness, and reward type and product type are also effective. In the combination of reward type and product type, we have confirmed the regulating factor influencing the effectiveness of social advertising according to the tie strength between the recommenders and the consumers. Strong-tie recommenders have more influence on the effectiveness of the social advertising than weak-tie recommenders. Based on these results, theoretical and practical implications were provided to refine marketing environments on SNSs.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.49 no.5
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• pp.27-36
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• 2012

We propose a new scheme combining the calibration of the path imperfections and the compensation of HPA nonlinearity in the downlink OFDM smart antenna systems. We use a two term third-order polynomial (without second-order term) and the indirect learning architecture for calibration and compensation, to make each path of the antenna array have equal characteristics. We test our scheme with computer simulations. The result shows that, with the addition of only one third-order term, the adverse nonlinear effects as well as the those of linear imperfections can be effectively compensated.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.4A
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• pp.197-204
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• 2012

We propose a new scheme combining the compensation of HPA nonlinearity and the calibration of the path imperfections in the downlink OFDM smart antenna systems. We use a two term third-order polynomial (without second-order term) and the feedforward method for compensation and calibration to make each path of the antenna array have equal characteristics. Since the proposed scheme does not alter the base-band signal, it can be applied to the smart antenna system independently of the base-band signal processing section. The result of computer simulations shows that, with the addition of only one third-order term, the adverse nonlinear effects can be effectively compensated, and the those of linear imperfections can be calibrated as well.

• Journal of the Institute of Convergence Signal Processing
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• v.3 no.4
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• pp.49-56
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• 2002

In this paper, a new controller using non-linear compensator for position control is presented, which we can satisfy the given specifications more easily than the existing one. We suggest an improved PDFE(Integral with Proportional-Derivative-plus-Feedforward) controller by which both phase margin and bandwidth are controlled simultaneously in the controller design problem. Replacing the feed forward term in the PDFF system with a CDIDF(Complex Dual Input Describing Function), the desired phase margin is obtained without diminishing the bandwidth of the closed loop system. The effectiveness of the proposed controller is confirmed through simulations and experiments. As The results of these, we know that it is possible to adjust overall specifications by varying parameters in the improved PDFF system.

• Environmental and Resource Economics Review
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• v.23 no.2
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• pp.281-304
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• 2014

This research presents that exogenous characteristics of consumers affect eco-friendly vehicle preference. The car consumers are classifies into two groups by their characteristics - sex, age, and fuel expense. To find differences in the preference for eco-friendly vehicle, marginal utilities and compensate variations of vehicle attributes are estimated. The results suggest that there are significant differences in marginal utilities and compensate variations. However, the compensate variation is more reliable standard to test the preference differences because utility is a subjective measure. Men and old people have stronger preference for the fuel efficiency than women and young people. High fuel expense people have more preference for short time charging vehicles than low fuel expense people. In addition, gasoline vehicles are more attractive to young people than old people.