• Proceedings of the KIPE Conference
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• 2003.07b
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• pp.648-653
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• 2003

영벡터로 V(000)이 적용된 종전의 2상 RCD-PWM(Random Centered Distribution PWM)은 변조지수 M이 1에 가까울수록, 모터 전압 및 전류 스펙트럼의 광대역화 효과가 증가되지 않는 단점이 있다. 본 연구에서는 M에 따라서 영벡터를 선택하는 2상 MZRCD(Multi-Zero Vectors RCD)기법을 제안하였다. 2상 MZRCD기법은 M이 0.7보다 크게되면 영벡터로 V(111)을 선택하고, 작은 경우에는 V(000)을 선택하여, M의 전 영역에 걸쳐서 스펙트럼의 광대역화를 이룰 수 있는 방법이다. 본 연구의 타당성을 입증하기 위하여 Matlab simulink에 의하여 시뮬레이션을 수행하였다. M의 변화에 따른 모터 전압 및 전류의 스펙트럼을 검토하였으며, M과 무관하게 모터 전압 및 전류 스펙트럼이 광대역으로 선형화된 분포를 얻을 수 있었다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.715-716
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• 2015

최신 IT 기술 변화의 중심점에 있는 3D 가상현실이란, 어떤 특정한 환경이나 상황을 컴퓨터로 만들어서, 그것을 사용하는 사람이 마치 실제 주변 상황 환경과 상호작용을 하고 있는 것처럼 만들어 주는 인간-컴퓨터 사이의 인터페이스를 하는 컴퓨터 프로그래밍 기법이다. 이처럼 무한한 가능성을 가진 3D 가상현실을 이용한 여러 가지 프로젝트가 쏟아져 나오고 있다. 현재 의학에 관한 실습 지식을 배우는데 있어서 장비 및 상황이 여의치 않은 경우가 많다. 위와 같은 필요성을 기본으로 하여, 본 논문에서는 가상현실을 기반으로 만든 간단한 의학시술 과제를 통해 교육생들이 실습해보고 기본적인 실습 흐름 및 의학 지식을 습득할 수 있는 간호 교육 시뮬레이션을 개발하였다. 환자의 상태와 병명을 표기해주며 위 환자에게 투여할 수 있는 약에 대한 선택을 교육생에게 주어준다. 교육생은 환자에게 투여할 약을 선택하고 투약할 약의 양을 조절하며, 마지막으로 투약하는 방법에 대해서 선택지를 통해 선택한다. 가상현실을 통해 몰입감을 높일 수 있어 간호교육에 효율적이다.

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2003.05a
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• pp.12-17
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• 2003

본 연구에서는 MICP Etching system 을 이용한 Via contact 및 Deep contact hole etch process 특성을 연구하였다. Langmuir probe 를 이용한 MICP source 의 Plasma density & electron temperature 측정하였고 탄소와 플로우르를 포함하는 혼합 Plasma 를 형성하여 RF frequency, wall temperature, chamber gap, gas chemistry 등의 변화에 따른 식각 특성을 조사하였다. Plasma density 는 1000w 에서 $10^{11}$/$cm^3$ 이상의 high density plasma와 uniform plasma 형성을 확인하였고 $CH_{2}F_{2}$와 CO의 적절한 혼합비를 이용하여 Oxide to PR 선택비가 10 이상인 고선택비 조건을 확보하였다. 고선택비 형성에 따라 Polymer 형성이 많이 되었고 이를 개선하기 위하여 반응 챔버의 온도 조절을 통하여 Polymer 증착 방지에 효과적인 것을 확인하였다. MICP source를 이용하여 탄소와 플로우르의 혼합 가스와 식각 챔버의 온도 조절에 의한 선택비 증가를 확보하여 High Aspect Ratio Contact Hole Etch 가능성을 확보하였다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.6B
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• pp.499-505
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• 2011

The mixing behavior of turbidity currents in a reservoir is closely related with the annual temperature change of the reservoir. In the summer, the reservoir has a well defined structure: one or two thermoclines and some layers of different densities. This density stratification inhibits vertical mixing and affects various hydrodynamic processes within the reservoir. Therefore, many reservoirs can be operated to release water of the specific quality with the selective withdrawal. In this study, the hydraulic experiments were performed to analyze the efficiency of selective withdrawal. The velocity distributions are measured with PIV in the stratified tank with the "two-tank" method. The relationship between the Richardson number and the selective withdrawal efficiency are provided using the measured velocity distributions.

• International Commerce and Information Review
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• v.18 no.3
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• pp.227-248
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• 2016

World aviation market has been expanded every year caused by improvement of economic level quality of individual life, increase of the development of tourist industry. Aviation companies have compete to develpe the service program for the maintaining of sustainable choice by customer and develop the market share. This study aims to suggest customer service strategy which is based on the relations between satisfaction by providing a differentiated service quality. This paper is focusing on the investigation with the mediating role of commitments on customer satisfaction in Aviation company. For this purpose, we do literature reviews, develop research model and conduct an empirical research. The literature review covers theoretical discussion on customer satisfaction and core variables for hypothesis setting. This analysis shows the airline service factors have a positive effect on the customers' satisfaction and re-choice intention. And it is necessary to improve airlines' systematic management and strategic development on airline service factors for better airlines' customer service.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.5 no.4
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• pp.35-49
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• 2010

The purpose of this study is to help the venture business innovate the purchasing process. This study reviewed the types of transaction governance structure, and researched the change of transaction governance structure, while using information technology. According to transaction cost theory, the transaction governance structure can be moved from hierarchy to market. It can be moved to the middle, because of economies of scale, incentive for supplier, and increasing search cost. And it can be moved from market exchange to relational exchange, using electronic marketplace. In order to innovate the purchasing process, the venture business can select the transaction governance structure that fits the its purchasing contexts.

• Environmental and Resource Economics Review
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• v.15 no.3
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• pp.555-574
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• 2006

This study conducts a choice experiment to estimate the recreational values of major dam reservoirs in Korea. A discrete-choice econometric model is estimated with the data of experimented choices. Not only the recreation value of each dam lake but also the values of the characteristics of the lakes are estimated. It is shown that the value function of the amount of reserved water is not monotonically increasing. Water quality is the most important characteristic that affects the recreation value. Various other characteristics of the dams such as the availability of education facility, restaurants, hotels and parking lots also generate substantial amounts of recreational benefits.

• Applied Chemistry for Engineering
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• v.19 no.4
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• pp.432-438
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• 2008

Hydrogenation reactions of p-toluidine over Ru/C were performed while varying reaction temperature, the hydrogen pressure, catalyst loading, solvent, and alkali additive and the effects on the reaction rates and product distribution were examined. 4-Methylcyclohexylamine was generated as a main product and bis(4-methyl cyclohexyl)amine was obtained as a resentative side-product for the hydrogenation reaction of p-toluidine. The selectivity of MCHA decreased with reaction temperature and the hydrogen pressure while increased with catalyst loading. IPA was the best solvent for MCHA. A mechanism of hydrogenation reaction of p-toluidine was suggested from the results. It was found that the presence of alkali salt increased MCHA by reducing BMCHA and rates of hydrogen reaction increased.

• Journal of the Korea Society of Computer and Information
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• v.11 no.1 s.39
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• pp.87-96
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• 2006

Selectivity estimation is one of the query optimization techniques. It is difficult for the previous selectivity estimation techniques for moving objects to apply the position change of moving objects to synopsis. Therefore, they result in much error when estimating selectivity for queries, because they are based on the extended spatial synopsis which does not consider the property of the moving objects. In order to reduce the estimation error, the existing techniques should often rebuild the synopsis. Consequently problem occurs, that is, the whole database should be read frequently. In this paper, we proposed a moving object histogram method based on quad tree to develop a selectivity estimation technique for moving object queries. We then analyzed the performance of the proposed method through the implementation and evaluation of the proposed method. Our method can be used in various location management systems such as vehicle location tracking systems, location based services, telematics services, emergency rescue service, etc in which the location information of moving objects changes over time.

• Membrane Journal
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• v.28 no.6
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• pp.388-394
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• 2018

Carbon nanotube (CNT) based membranes are promising candidates for separation membranes by showing high water transport rate and ion rejection rate according to their radii. The ion selectivity is an important factor to discover the full potential of CNT membranes, and it is affected by the functionalization of CNTs. With multivalent/size ion mixtures, the ion selectivity is affected by not only ion-functional groups interaction but also ion-ion interactions and ion size exclusion in a complex manner. In this study, molecular dynamics simulations are performed to study the ion selectivity of functionalized carbon nanotubes when multivalent/size ions are contained. The permeation energy barriers are calculated by plotting potential of mean force profiles, and various factors, such as CNT size and partial charges, affecting ion selectivity are investigated. The results presented here will be useful for designing CNT membranes for ion separation, biomimetic ion channels, etc.