• 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.

• Korea Journal of Hospital Management
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• v.21 no.3
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• pp.65-70
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• 2016

The Long-Term Care Hospital (LTCH) accreditation system was initiated in 2013 in the form of mandatory accreditation system in order to improve patient safety and the quality of medical service at LTCHs. By June 2016, the accredited LTCHs were 76.2%. This research was conducted to review the implementation process in the first cycle and to promote development of the second cycle of LTCH accreditation system. There are some changes which reinforced the accreditation standards, accreditation survey, and public access to accreditation results in order to strengthen patient safety in the first cycle LTCH accreditation system. LTCHs which participated in the accreditation system achieved certain outcomes in respect to patient safety and employee satisfaction. However, there are several urgent problems in placement criteria of night duty health care providers, reinforcement plans in the accreditation system, and incentives for accredited hospitals. In order to solve these problems, the most important thing is to clearly recognize the fact that the healthcare accreditation system is not the means for control and regulate hospitals but a system to induce hospitals to continue to strive for improvements in patient safety and medical service quality. In addition, it is required that LTCHs, accrediting agency and the Ministry of Health and Welfare compromise and cooperate to seek solutions every time issues related to the accreditation system arise.

• Journal of Electrical Engineering and Technology
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• v.12 no.2
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• pp.541-548
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• 2017

An increasing concern is paid to short-term voltage stability with the growth of penetration of induction motor loads. Reactive power reserve(RPR) of power system is critical to improve voltage stability. A definition of short-term voltage stability-related RPR(SVRPR) is proposed. Generators vary their contributions to voltage stability with their location and system condition, etc. Voltage support coefficient based on the second-order trace sensitivity method is proposed to evaluate SVRPR's contribution to short-term voltage stability. The evaluation method can account for the generator's reactive support in transient process and the contingency severity. Then an optimization model to improve short-term voltage stability is built. To deal with multiple contingencies, contingency weight taking into account both its probability and severity is proposed. The optimization problem is solved by primal dual interior point method. Testing on IEEE_39 bus system, it is indicated that the method proposed is effective. Short-term voltage stability is improved significantly by the way of SVRPR optimization. Hence, the approach can be used to prevent the happening of voltage collapse during system's contingency.

• Journal of applied mathematics & informatics
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• v.28 no.3_4
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• pp.763-772
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• 2010

This paper deals with the existence of triple positive solutions for the nonlinear second-order three-point boundary value problem z"(t)+a(t)f(t, z(t), z'(t))=0, t $\in$ (0, 1), $z(0)={\nu}z(1)\;{\geq}\;0$, $z'(\eta)=0$, where 0 < $\nu$ < 1, 0 < $\eta$ < 1 are constants. f : [0, 1] $\times$ [0, $+{\infty}$) $\times$ R $\rightarrow$ [0, $+{\infty}$) and a : (0, 1) $\rightarrow$ [0, $+{\infty}$) are continuous. First, Green's function for the associated linear boundary value problem is constructed, and then, by means of a fixed point theorem due to Avery and Peterson, sufficient conditions are obtained that guarantee the existence of triple positive solutions to the boundary value problem. The interesting point is that the nonlinear term f is involved with the first-order derivative explicitly.

• 제어로봇시스템학회:학술대회논문집
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• 1995.10a
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• pp.123-126
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• 1995

Characteristics of control system design using Universal Learning Network (U.L.N.) are that a system to be controlled and a controller are both constructed by U.L.N. and that the controller is best tuned through learning. U.L.N has the same generalization ability as N.N.. So the controller constructed by U.L.N. is able to control the system in a favorable way under the condition different from the condition of the control system in learning stage. But stability can not be realized sufficiently. In this paper, we propose a robust control method using U.L.N. and second order derivatives of U.L.N.. The proposed method can realize better performance and robustness than the commonly used Neural Network. Robust control considered here is defined as follows. Even though initial values of node outputs change from those in learning, the control system is able to reduce its influence to other node outputs and can control the system in a preferable way as in the case of no variation. In order to realize such robust control, a new term concerning the variation is added to a usual criterion function. And parameter variables are adjusted so as to minimize the above mentioned criterion function using the second order derivatives of criterion function with respect to the parameters. Finally it is shown that the controller constricted by the proposed method works in an effective way through a simulation study of a nonlinear crane system.

• Journal of Engineering Education Research
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• v.21 no.1
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• pp.44-55
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• 2018

The purpose of this study is to investigate the relationship between post - employment job satisfaction and both short-term (4-12 weeks) and long-term (12+weeks) on-site training. For this purpose, 405 graduates who had completed on-site training (205 short-term, 200 long term) during the school year were surveyed. The results of the comparative analysis of both short-term and long-term on-site training participants are as follows: In both short-term and long-term on-site training, it was found that on-site performance during the school year did not directly affect post-employment job satisfaction. In the case of short-term on-site training participants, job match and organizational commitment were found to have no mediating effect on the correlation between on-site training performance and job satisfaction. On the other hand, in the case of long-term on-site training participants, the analysis showed that job match and organizational commitment had mediating effects on the correlation between on-site training performance and job satisfaction. These effects are not solely attributable to differences in duration of training; the differences in operating systems and the degree of preparation derived from these systems also affect the level of on-site training for students, businesses, and schools. This paper summarizes these findings and suggests the following improvement plans for on-site training in the future: First, short-term on-site training is required to establish a systematic basis in order to enhance students' preparedness level. Second, both short-term and long-term on-site training should improve the skills and field understanding for students' majors through systematic quality management during the training period. Third, it is necessary for universities to increase expectations and quality of short-term on-site training for all involved while simultaneously reducing the gap between educational goals and practice in this field.

• Journal of the Korean Society for information Management
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• v.17 no.2
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• pp.119-138
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• 2000

The purpose of this study is to present solutions to expanding added-term relations which will fit new information retrieval environment. This report reviews standards for ISO 2788 and ANSI/NISO Z 39.19, and compares and analyzes 20 thesaurus added-term relations currently used to find out problems and limitations. Based on findings of the study, this report suggests how to expand thesaurus added-term relations to accomodate changes in information retrieval environment. In order to solve those problems, this report presents solutions to expanding added-term relationships as follows: First, definition was separated from scope note and scope note is categorized by type. Second, principles for the use of qualifiers are presented. Third, principles for expanding of descriptor term information are presented.

• The Korean Journal of Health Service Management
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• v.7 no.4
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• pp.131-141
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• 2013

The purpose of this study was to investigate the long-term care hospital nurse's recognition and performance level of hospital infection control. The subjects of the study were 147 long-term care hospital nurses. The period of data collection was from April 1 to 30, 2013. The data were analyzed by SPSS 19.0 program. The result are as followed; First, the total average scores of the recognition and performance by long-term care hospital nurses of hospital infection control were $4.64{\pm}0.32$ and $4.21{\pm}0.23$. Second, recognition of hospital infection control was significantly different according to position and hospital infection control education experience. Performance of hospital infection control was significantly different according to education level and hospital infection control education experience. Third, there was a positive correlation between the degree of recognition and performance of hospital infection control. Therefore, it is suggested to apply the concrete education program to enhance the recognition in order to improve the performance of hospital infection control of the Long-term hospital nurses.

• Genomics & Informatics
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• v.20 no.1
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• pp.9.1-9.6
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• 2022

Mendelian randomization (MR) uses genetic variation as a natural experiment to investigate the causal effects of modifiable risk factors (exposures) on outcomes. Two-sample Mendelian randomization (2SMR) is widely used to measure causal effects between exposures and outcomes via genome-wide association studies. 2SMR can increase statistical power by utilizing summary statistics from large consortia such as the UK Biobank. However, the first-order term approximation of standard error is commonly used when applying 2SMR. This approximation can underestimate the variance of causal effects in MR, which can lead to an increased false-positive rate. An alternative is to use the second-order approximation of the standard error, which can considerably correct for the deviation of the first-order approximation. In this study, we simulated MR to show the degree to which the first-order approximation underestimates the variance. We show that depending on the specific situation, the first-order approximation can underestimate the variance almost by half when compared to the true variance, whereas the second-order approximation is robust and accurate.