• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 합동 추계학술대회 논문집 정보 및 제어부문
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• pp.517-520
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• 2002

This paper has been studied Operational Amplification Circuit that has high power specification of 90 W is designed. In the input differential amplifier stage, the current source for circuit bias is designed to protect device from high voltage source. the criving state has the voltage gain more than input differential stage. With temperature compensation design, output stage works stable in different to temperature.

• Journal of international Conference on Electrical Machines and Systems
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• 제1권1호
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• pp.67-76
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• 2012

Due to the increasing amount of applications of power electronic ac-dc converters, it is necessary to design a single-stage converter that can reliably perform both buck and boost operations. Traditionally, this can be achieved by double-stage conversion (ac/dc-dc/dc) which ultimately leads to less efficiency and a more complex control system. This paper discusses two types of modern ac-dc converters. First, the novel impedance-source ac-dc converter, abbreviated as custom Z-source rectifier, is analyzed; and then, switched inductor (SL) Z-source ac-dc converter is proposed. This paper describes the Z-source rectifiers' operating principles, the concepts behind them, and their superiorities. Analysis and simulation results show that the proposed custom Z-source rectifier can step up and step down voltage; and the main advantage of the SL Z-source ac-dc converter is its high step-up capability. Low ripple of the output dc voltage is the other advantage of the proposed converters. Finally, the SL Z-source ac-dc converter is compared with the custom Z-source ac-dc converter.

• 정보처리학회논문지D
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• 제8D권6호
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• pp.753-760
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• 2001

디자인패턴은 어플리케이션 개발 시에 고려된 문제들로부터 독립적이며 확장성과 유지보수성에 대한 문제를 해결하기 위한 디자인 지식이며 현재 광범위하게 이용되고있는 분야이다. 그러나 이러한 광범위한 디자인패턴의 활용에도 불구하고 디자인 패턴에 명세와 활용은 주로 개발자의 수작업에 의존하고 있다. 그 결과 일관된 형태의 분석과 활용이 어렵고 오류 발생 빈도를 높일 뿐 아니라 프로그램 개발에 많은 시간을 필요로 한다. 따라서 이러한 문제를 해결하기 위해 본 논문에서는 디자인 패턴을 구조화하기 위해 XML을 사용한 표현방법, 이를 이용한 디자인 패턴 활용시스템 구조를 제시한다. 또한 이러한 표기법과 활용구조를 통해 소스코드 자동생성 지원 시스템을 제시하고 적용 예를 보이고자한다. XML을 이용한 구조화된 문서활용은 소스코드 생성시 사용자들에게 더 작은 코드를 작성하게 만들고, 더 안정된 시스템을 구축할 수 있게 한다.

• JSTS:Journal of Semiconductor Technology and Science
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• 제8권2호
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• pp.170-177
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• 2008

In the present work a methodology to minimize short channel effects (SCEs) by modulating the effective channel length is proposed to design 25 nm single and double gate-source/drain underlap MOSFETs. The analysis is based on the evaluation of the ratio of effective channel length to natural/ characteristic length. Our results show that for this ratio to be greater than 2, steeper source/drain doping gradients along with wider source/drain roll-off widths will be required for both devices. In order to enhance short channel immunity, the ratio of source/drain roll-off width to lateral straggle should be greater than 2 for a wide range of source/drain doping gradients.

• Journal of Information Technology Applications and Management
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• 제15권4호
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• pp.137-157
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• 2008

Fashion merchandiser profession is a highly information-intensive job. In fact, a merchandiser is to acquire a variety of information mainly from external environment and to analyze it in order to come to an informed decision. Despite a significant amount of past studies on environment scanning, their main concern was of managerial work. And, some fashion design studies have only touched the issue of information source in a descriptive tone. Here, we attempt to analyze empirically fashion merchandisers' environmental scanning activities. Our results can be stated as follows : 1) Though the quality of information source has a positive relationship with its use, the accessibility does not. 2) There is no significant difference between the use of relational source and the use of non-relational source. 3) Internet is being used more at the initial stage(opening) of information seeking than at the orientation and consolidation stage.

• Journal of Electrical Engineering and Technology
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• 제7권5호
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• pp.714-723
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• 2012

A new Z-source inverter (ZSI) topology is developed to improve voltage boost ability. The proposed topology is modified from the switched inductor topology by adding some more inductors and diodes into inductor branch to the conventional Z-source network. The modulation methods developed for the conventional ZSI can be easily utilized in the proposed ZSI. The proposed ZSI has an ability to obtain a higher voltage boost ratio compared with the conventional ZSI under the same shoot-through duty ratio. Since a smaller shoot-through duty ratio is required for high voltage boost, the proposed ZSI is able to reduce the voltage stress on Z-source capacitor and inverter-bridge. Theoretical analysis and operating principle of the proposed topology are explicitly described. In addition, the design guideline of the proposed Z-source network as well as the PWM control method to achieve the desired voltage boost factor is also analyzed in detail. The improved performances are validated by both simulation and experiment.

• 한국유체기계학회 논문집
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• 제18권1호
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• pp.5-10
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• 2015

The "Ondong tunnel" is not used now where is one of the tunnels in the Janghang line which is from Cheonan to Iksan. The length of the tunnel is 214 m. The location of the fire source is center of the tunnel and the pool fire with heptane is for the fire source. Tests are carried out for the various fire sizes, the height and obstructed/open condition of the fire source. Temperature on the top of the tunnel is measured. Even if the fire size is same, the maximum temperature on the ceiling of the tunnel for the elevated fire source is very larger than the maximum for the ground fire source. As the fire size is lager the maximum temperature on the ceiling is higher. These test results can be very useful for design and guidelines of fire detectors in tunnels.

• 한국지열·수열에너지학회논문집
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• 제17권3호
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• pp.21-29
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• 2021

In this study, the current regulation of the water source energy, one of the renewable energy, was analyzed, and the improvement plan for the high efficient data center cooling system was suggested. In the improvement plan, the design and construction guidelines of the water source energy system permit to adopt the cooling and heating system with or without heat pump. In addition, it should also include the system operated in the cooling mode only all year-round. The domestic test standards to consider the water source operating conditions should be developed. Especially, it is highly recommended that the test standards to include the system with forced cooling and free cooling modes related with the enhanced data center cooling system adopting the water source energy.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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• pp.115-116
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• 2002

This study was carried out as one of efforts to overcome difficulties in air bearing design due to low stiffness and low damping. Hydrodynamic effects on hydrodynamic stiffness of a fluid film in a high speed air bearing with tow-row air sources are investigated. The hydrodynamic effects by the high speed over DN 1,000,000 and eccentricity of a proceeding which are not considered in conventional design of an air bearing need to be reconsidered. The hydrodynamic effects, which dominantly influence on the load capacity of air bearing, are caused mainly by proceeding speed, eccentricity, and the source positions. The two-row source arrangement in the air bearing produces quite unique hydrodynamic effects with respect to pressure distribution of the air film. Optimal arrangement of the two-row sources improves performance of an air bearing in film reaction force and loading capacity of high speed spindles. This study compares the pressure distribution by numerical simulation as a function of eccentricity of proceeding and the source positions. The air source position 1/7L form one end of an air bearing was found to be superior to source position of 1/4L. The dynamic stiffness were obtained using a two-dimensional cutting method which can directly measure the cutting reaction forces and the displacements of the spindle in two directions using a tool dynamometer and transducer sensors. Heat generation in the air film can not be negligible over the speed of DN 2,000,000. In order to analysis effects of heat generation on the characteristics of air bearing, high cooling bearing spindle and low cooling bearing spindle were tested and compared. Characteristics of the frequency response of shaft and motion of run out errors were different for the spindle. The test results show that, in the case of low cooling bearing spindle, the stiffness became smaller due to heat generation. The results, which were obtained for high speed region, may be used as a design information for spindle which can be applied to precision devices such as ultra precision grinding and ultra high speed milling.

• 한국의류학회지
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• 제41권5호
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• pp.809-824
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• 2017

Interest in and use of social media as a communication channel are consistently evolving; in addition therefore, corporate social responsibility (CSR) activities have been often conducted on online channels such as social media due to the advantages offered by the rapid spread of information. Consumers can be persuaded differently and their cognition can be influenced depending on who delivers what message. This study examines the influence of information source characteristics on eWOM acceptance of CSR messages and attitudes toward a company. This study compares cases: when a company sends their CSR message versus when an individual (i.e., consumer's acquaintance) sends the company's CSR message. A total of 320 respondents were presented with online stimuli and responded to the questionnaire to identify this phenomenon. Vegan fashion (which refers to products made from raw materials without animal cruelty) was used as stimuli in this study because it is a representative example of CSR activities. As a result, when consumers are exposed to CSR messages online, perceived expertise, trustworthiness and attractiveness of information source affect consumer's electronic word-of-mouth (eWOM) acceptance and attitude toward a company. However, only trustworthiness influences eWOM acceptance in cases of a corporation information source. This study confirms the differences in eWOM acceptance and in attitudes to the company depending on to whom the messages were sent and with what content.