• 대한교통학회지
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• 제33권3호
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• pp.247-255
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• 2015

신규 고속도로가 개통될 때는 통상 신규 노선은 기존의 노선과 연계 또는 경합의 관계를 가지게 된다. 이러한 네트워크의 변화는 신규노선 주변의 다른 노선에서도 통행량 변화를 가져올 수 있으며, 이로인한 통행료 수입의 변화도 아울러 발생하게 된다. 본 연구에서는 통합채산제하에서의 신규 고속도로로 인해 발생하는 통행료 수입 변동에 대하여 고찰하고, 신규 사업이 재정 또는 민자사업으로 추진되었을 때 통행료 수입 변동이 공공기관이나 고속도로 민간사업자에게 의미하는 바를 제시하였다. 또한 통행료 수입 변동의 크기를 개별 사업 평가 및 다수 사업 간 평가에 반영할 수 있도록 지표화 하고자 하였다. 논문의 한계와 향후 연구과제에 대해서도 언급하였다.

• 한국생산제조학회지
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• 제26권3호
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• pp.306-312
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• 2017

Press rolls are constantly exposed to physical and heat stresses on their surface and are prone to crack, bruise, and spall if the accumulated stress goes beyond the critical point. Such surface phenomenon can cause them to lose their functionality and eventually lead to a halted production line. Eddy current testing can be considered a useful method to investigate the surface of the roll. The method involves the application of a high intensity magnetic field onto the surface of the roll, and thereby finding any early stage of possible defects. When the method was applied for roll inspection, the cross section of the sensor was regulated as per the overall testing speed. A smaller cross sectional area implied a better resolution but a longer testing time. In this paper, a convenient method to increase both overall system resolution and inspection speed of eddy current roll inspection is suggested by using a devised array sensor structure.

• Journal of Power Electronics
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• 제19권2호
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• pp.487-496
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• 2019

For a solid-state transformer (SST), some factors, such as signal delay, switching loss and differences in the system parameters, lead to unbalanced DC-link voltages among the cascaded H-bridges (CHB). With a control method implemented in the ${\alpha}{\beta}$ frame, the DC-link voltages are balanced, and the reactive power is equally distributed among all of the H-bridges. Based on the ${\alpha}{\beta}$ frame control, the system can achieve independent active current and reactive current control. In addition, the control method of the high-voltage stage is easy to implement without decoupling or a phase-locked loop. Furthermore, the method can eliminate additional current delays during transients and get the dynamic response rapidly without an imaginary current component. In order to carry out the controller design, the vector refactoring relations that are used to balance DC-link voltages are derived. Different strategies are discussed and simulated under the unbalanced load condition. Finally, a three-cell CHB rectifier is constructed to conduct further research, and the steady and transient experimental results verify the effectiveness and correctness of the proposed method.

• Asia pacific journal of information systems
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• 제34권1호
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• pp.321-350
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• 2024

When a competent employee leaves an organization, the technical skills and know-how possessed by that employee also disappear, which may lead to various problems, such as a decrease in organizational morale and technology leakage. To address such problems, it is important to increase employees' job satisfaction. Due to the advancement of both information and communication technology and social media, many former and current employees share information regarding companies in which they have worked or for which they currently work via job portal websites. In this study, a web crawl was used to collect reviews and job satisfaction ratings written by all and incumbent employees working in nine industries from Job Planet, a Korean job portal site. According to this analysis, regardless of the industry in question, organizational culture, welfare support, work system, growth capability and relationships had significant positive effects on job satisfaction, while time and attendance management, performance management, and organizational flexibility had significant negative effects on job satisfaction. With respect to the path difference between former and current employees, time and attendance management and organizational flexibility have greater negative effects on job satisfaction for current employees than for former employees. On the other hand, organizational culture, work system, and relationships had greater positive effects for current employees than for former employees.

• 대한전기학회논문지
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• 제41권1호
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• pp.18-23
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• 1992

Magnet core and rail of a magnetically levitated vehicle are usually made of highly conductive materials. Accordingly, eddy currents are induced in those members. Eddy currents often lead to a decrement of levitation and guidance force. This paper has calculated the decrement of both forces due to eddy current generated by magnet's vertical and lateral motion. U-shaped electromagnet and rail were chosen as amodel of 2D finite element analysis. Calculated results proved that both forces dropped significantly at high speed. Consequently, effects of eddy current should be considered in designing the magnet and control system.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2006년도 춘계학술대회 논문집
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• pp.43-48
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• 2006

This paper presents a scheme on the characteristics of induction motor under the combination of linear & non-linear loads at the three phase 4-wire power distribution system. Under the combination operation of single & three phase load, voltage unbalance will be generated and current unbalance will be more severe by the dropped voltage quality. All power electronic converters used in different types of electronic systems can increase harmonic disturbances by injecting harmonic currents directly into the feeder grid of three phase 4-wire. Harmonic current may cause torque to decrease. Moors may also overheat or become noisy and torque oscillation in the rotor can lead to mechanical resonance and vibration.

• 한국임상약학회지
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• 제15권2호
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• pp.139-148
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• 2005

Appropriate drug classification is important fur rational drug consumption. This study was conducted to evaluate the appropriateness of current drug classification system and suggest possible ways for improving the system. Nonprescription drug market has been decreased. Since total 27,962 products had been classified (prescription 17,187 vs. nonprescription 10,775 products, 61.5% vs. 38.5%) in July 2000 for implementing separation of drug prescribing and dispensing system, there are no classification changes. Reclassification is not motivated by product holder and regulatory system did not lead classification change either. Consumers' ease access to some nonprescription drugs is demanded. But point of public awareness and cultural and health environmental views, saff drug use rather than advantages from broad supply of nonprescription drugs is more critical. We concluded that current 2-categorized (prescription and nonprescription) drug classification system is appropriate, and addition of general sale category should be approached carefully with long term Preparations such as establishment of better nonprescription drug consuming infrastructure by public information provision and education for improving public medicinal knowledge and strengthening self medication guidance, and review of current classification status of marketed drugs and switching possibilities. For systemizing and encouraging reclassification, introduction of regulatory renewal system as a continuous reevaluation program which is the best way to review appropriateness of drug classification as well as provision of detailed guidance for industry including policy, requirement and process fer reclassification application, are necessary.

• 한국멀티미디어학회논문지
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• 제18권9호
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• pp.1068-1082
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• 2015

Due to the rapid advancement of the mobile technology, smart phones have been widely used in the current society. This lead to an easier way to retrieve video contents using web and mobile services. However, it is not a trivial problem to retrieve particular video contents based on users' specific preferences. The current movie recommendation system is based on the users' preference information. However, this system does not consider any emotional means or perspectives in each movie, which results in the dissatisfaction of user's emotional requirements. In order to address users' preferences and emotional requirements, this research proposes a movie recommendation technology to represent a movie's emotion and its associations. The proposed approach contains the development of emotion ontology by representing the relationship between the emotion and the concepts which cause emotional effects. Based on the current movie metadata ontology, this research also developed movie-emotion ontology based on the representation of the metadata related to the emotion. The proposed movie recommendation method recommends the movie by using movie-emotion ontology based on the emotion knowledge. Using this proposed approach, the user will be able to get the list of movies based on their preferences and emotional requirements.

• 전력전자학회논문지
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• 제5권6호
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• pp.610-619
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• 2000

본 논문에서는 현재 전력저장시스템으로써 가장 많이 사용하고 있는 배터리를 대체할 목적의 5MB (Superconductive Magnetic Bearing)를 이용한 off-line UPS에 관해 연구하였다 영구자석의 덩어리형 고온 초전도 체위에서의 부상득성을 이용하여 베어링 문제의 해결방안에 접근함으로써 고효율의 FES찰 구성하여 단상 off-line UPS에 적용하였으며 제어회로에는 80C 1 96KC 마이크로프로세서를 사용하였고 빠픈 응답윤 요구하는 부분 은 아날로그회로를 사용하여 구성하였다. 에너지 저장모드에서 컨버터 입력천류는 전원전압과 동상의 정현파로 제어하였으며 에너지 회생모드에서는 출력잔압윤 정현파로 제어하기위해 필터커패시터전류릎 직접 제어하였다. 시작 품제작을 통해 시스템의 안장된 동작특성을 확인함으로써 제안된 FES가 Off-line UPS 에서의 에너지 저장매체로써 우수함을 입증하였다.

• 한국결정성장학회지
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• 제31권1호
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• pp.55-62
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• 2021

CO2 가스 발생 감소와 연비향상을 위해서 HEV 차량은 ISG 시스템을 채용하고 있다. 이 ISG 시스템은 배터리가 감당해야 하는 전기 부하를 증대시켰고, 시동 횟수도 급격히 늘어나게 하였다. 이를 위해 AGM 연축전지가 개발되어 사용되고 있으나, 종래의 연축전지에 비해서 formation 중 전해액량 조절이 더 높은 수준으로 유지해야 됨에 따라 충전시간이 약 3배 가량 길어지게 되었다. 본 연구에서는 formation pattern의 최적화를 통해서 충전효율을 증대시켜 충전시간을 단축하고자 하였다. formation pattern의 최적화를 위해서, 16개 multi step에 10개 충전 step과 6개의 방전 step을 적용하고, step별 충전 전류를 조절한 4가지 조건(21 hr, 24hr, 27 hr, 30 hr)으로 시험을 진행하였다. 그 결과 24 hr 시험 조건이 PbO2 변환율이 가장 높게 분석되었고, 용량 103.3 %, 저온시동성능 38 sec, 충전수입성 37.36 A로 나타났다. Multi-step과 방전 step을 적용한 충전 프로그램의 결과, 충전 중에 국부적으로 급격히 발생된 분극화를 제거하고 전류의 손실을 최소함으로써 충전효율을 증가시킬 수 있음을 검증하였다. 이렇게 충전효율을 증가시킴으로써 본 연구에서는 충전시간을 기존에 비해서 약 30 % 감소시키는 탁월한 결과를 얻을 수 있었다.