• 천문학회보
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• 제37권2호
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• pp.160.1-160.1
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• 2012

We present an alternative approach for satellite formation reconfiguration by an optimal impulsive-thrust strategy to minimize the total characteristic velocity in a near-circular-orbit. Linear transformation decouples the Hill-Clohessy-Wiltshire(HCW) dynamics into a new block-diagonal system matrix consisting of 1-dimensional harmonic oscillator and 2-dimensional subsystem. In contrast to a solution based on the conventional primer vector theory, the optimal solution and the necessary conditions are represented as times and directions of impulses. New analytical expression of the total characteristic velocity is found for each sub systems under general boundary conditions including transfer time constraint. To minimize the total characteristic velocity, necessary conditions for times and directions of impulses are analytically solved. While the solution to the 1-dimensional harmonic oscillator has been found, the solution to the 2-dimensional subsystem is currently under construction. Our approach is expected to be applicable to more challenging problems.

• Journal of Contemporary Eastern Asia
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• 제19권2호
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• pp.216-233
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• 2020

Over the last 70 years, South Korea has gone through countless provocations from North Korea. Provocation is something that must be delicately calculated before the actual action, since it can be extended to a serious conflict. Among the possible factors, this paper focuses on the leader's characteristic, because 1) under North Korean dictatorship, the leader's thoughts are critical influence to policies and 2) personal characteristic, especially if it is the dictator's, hardly changes even when the external circumstances change. The purpose of this paper is in analyzing the correlations between North Korean leader's characteristics and provocation pattern. First, three generations of Kim Il-sung, Kim Jong-il, and Kim Jong-un's personal characteristics will be described. Next, particular provocation features in respective leader's period will follow. Lastly, how each leader's characteristic and concerns were reflected on the provocations will be analyzed.

• 기술경영경제학회:학술대회논문집
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• 기술경영경제학회 1997년도 제11회 하계학술발표회 논문집
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• pp.286-306
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• 1997

본고는 정보통신망의 경제적관점을 중점적으로 하여 향후 광대역정보통신망구축이 경제사회에 미치는 영향을 국가경쟁력과 삶의 질 측면에서 분석하였다. 즉 광대역망이 갖는 생산재, 소비재적인 특성과 기술개발과 투자시점간의 시차에 따른 경제적 효과를 고려하였다. 또한 이러한 경제적 접근이외에도 광대역망구축에 대한 현실적인 접근을 위하여 진화단계 특성 등 기술적인 측면을 고려하여 실현가능한 시나리오를 제시하고 그에 따른 영향을 추가하였다. 이에 따라 기술개발 선점에 따른 망구축을 실현하는 기술기반 우위국가는 국가 전반적인 경쟁력을 강화시킬 수 있을 뿐만 아니라 국민의 삶의 질 향상에도 기여할 것임이 제시된다. 또한 우리나라와 같이 기술수준이 낮은 기술기반 열위국가의 경우에 실현가능한 3가지 시나리오를 고려하였다.

• 한국콘텐츠학회논문지
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• 제7권10호
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• pp.250-261
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• 2007

본 연구는 최근 왕릉의 활용논의가 가장 활발히 전개되는 있는 서삼릉을 대상으로 그의 사회적 변용과 이용 및 공간적 특성을 통해 왕릉의 관광자원화 방향을 검토한 것이다. 연구결과, 왕릉의 관광레크레이션적 가치는 왕릉이라는 문화적 요인 못지않게 주변지역의 특성적인 환경 요인이 중요한 것으로 밝혀졌다. 또한 왕릉의 개발수요는 기본적으로 관광개발에 앞서 시민휴식공간으로서의 개발이 요구되고 있는바, 시민휴식공간과 관광레크레이션을 어떻게 양립시켜 나갈 것인가가 공간개발의 중요한 문제가 되는 것으로 확인된다. 그리고 왕릉의 특성은 문화적 요인, 환경적 요인과 더불어, 왕릉을 구성하는 인물적 특성과 왕릉을 둘러싼 식생 또는 경관학적 특성에도 관련이 깊은 것으로 나타나고 있어, 이러한 공간, 식생, 인물 구성에 대한 스토리 연구가 반드시 필요할 것으로 판단된다.

• 산업경영시스템학회지
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• 제41권2호
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• pp.159-166
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• 2018

The proliferation of information technologies made it possible to produce information products of different versions at much lower cost comparing to traditional physical products. Thus it is common for information product manufacturers to consider vertically differentiated product line for more profit through improved market coverage. Another salient characteristic of most information product is network externality. Existing researches dealing with vertical differentiation and network externality usually assumed oligopolistic market where vertically differentiated products are provided by competing companies, respectively. Moreover, they analyzed the essentially dynamic characteristic of network externality statically. In this study, different from the previous researches, the vertical differentiation strategy of a monopolistic company under network externality is dynamically analyzed. We used a two-period model to accommodate the dynamic feature of network externality. Based on the two-period model, the profit maximizing solutions are analyzed. The results showed that a monopolistic company has no incentive to differentiate products vertically when the network externality is absent. On the contrary, when the network externality exists, the monopolistic company can derive more profit by vertically differentiating the product line. It is also shown that, for more profit, the monopolistic company should keep the quality difference between the high quality product and the low quality product as greater as possible.

• Journal of Information Technology Applications and Management
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• 제22권4호
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• pp.1-37
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• 2015

Micro small business start-ups are receiving financial and marketing support from government or public authority, but business closure rate is very high and it causes a hugh burden to households and national economy. This study aims to verify the causal relationship between the self-determination characteristic of small business start-ups and entrepreneurial intention through learning orientation and innovation ability. The man's intrinsic motivation of self-determination theory is expected to have an impact on the entrepreneurial intention of small business start-ups. The self-determination theory includes perceived autonomy, perceived competence, perceived relationship as independent variables. This study presented a research model for explaining the entrepreneurial intention of small business start-ups, and collected 260 survey responses from the small business start-ups In order to validate the proposed research model, PLS analysis is performed with valid 246 questionnaires. By PLS technique, the measurement reliability and validity of research variables are tested and the path analysis is conducted to do the hypothesis test. Path analysis shows that perceived autonomy does not significantly affect the learning orientation and innovation ability. On the other hand, perceived competence significantly influences learning orientation and innovation ability. Perceived relationships had significant influence on learning orientation. It is found that the parameters of learning orientation and innovation ability significantly influence the dependent variable of entrepreneurial intention. Based on the results, a policy and strategy for supporting small business start-up are presented.

• Journal of Power Electronics
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• 제18권6호
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• pp.1771-1779
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• 2018

Modern trams with a super capacitor have gained a lot of attention in recent years due to its reliability, convenience, energy conservation and environmental friendliness. Because of its special charging characteristic, the traditional charging structure and control strategy cannot satisfy its charging requirements. This paper presents a new charging topology for fast charging modern trams with a super capacitor and it designs a controller using continuous control set model predictive control (CCS-MPC). There are three contributions in this paper. First, a new charging structure is designed and its mathematics model is derived. The cascade structure is adopted instead of the parallel structure to simplify the control process and to keep the rated power of the controllable part low. Second, a MPC control strategy is proposed to satisfy the charging characteristic. The optimal control signal can be obtained by solving the designed optimization problem. The optimal control signal is related to the discrete control action. In addition, mapping between the continuous control signal and the discrete control action is designed. Third, a semi-physical experimental platform is built to verify the proposed topology and control method. The simulation model and experiment platform are built to verify the correctness of the new structure and its control method. The results obtained show that the new topology can work effectively.

• Journal of Electrical Engineering and Technology
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• 제13권2호
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• pp.631-636
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• 2018

This paper proposed an optimal operation strategy for a hybrid energy storage system (HESS) with a lithium-ion battery and lead-acid battery for mild hybrid electric vehicles (mild HEVs). The proposed mild HEV system is targeted to mount the electric motor and the battery to a conventional internal combustion engine vehicle. Because the proposed mild HEV includes the motor and energy storage device of small capacity, the system focuses on low system cost and small size. To overcome these limitations, it is necessary to use a lead acid battery which is used for a vehicle. Thus, it is possible to use more energy using HESS with a lithium battery and a lead storage battery. The HESS, which combines the lithium-ion battery and the secondary battery in parallel, can achieve better performance by using the two types of energy storage systems with different characteristics. However, the system requires an operation strategy because accurate and selective control of the batteries for each situation is necessary. In this paper, an optimal operation strategy is proposed considering characteristics of each energy storage system, state-of-charge (SOC), bidirectional converters, the desired output power, and driving conditions in the mild HEV system. The performance of the proposed system is evaluated through several case studies with respect to energy capacity, SOC, battery characteristic, and system efficiency.

• 한국산학기술학회논문지
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• 제11권6호
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• pp.1978-1990
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• 2010

본 연구에서는 지식관리시스템(KMS)을 도입하여 활용 중인 공공기관을 중심으로 활용도와 만족도에 미치는 영향요인에 대한 연구이다. 공공기관의 경우 1999년 하반기부터 지식관리시스템을 본격적으로 도입하여 현재 국방부, 행정자치부, 기획예산처 등 대부분의 정부부처에서 시스템을 구축하여 운용하고 있다. 이로 인해 지식관리시스템의 편리성과 필요성을 이해하고, 지식자산의 중요성에 대한 인식이 확산되고 있다. 하지만 부서별 KMS 활용도에 많은 차이가 있으며 사용자 간에도 만족도에 많은 차이가 있음을 발견할 수 있다. 이는 KMS에 대한 최고책임자 관 심, 전담 인력 요인의 지원, 교육훈련 여부, KM 프로세스 지원 등의 많은 부분에서 영향을 받는 것으로 기대되었다. 따라서 본 연구는 KMS에 미치는 영향요인으로 조직특성, 지식정보특성, 전략특성의 하위요인을 도출하고 이러한 하위요인들이 KMS 활용도 및 KMS 만족도에 어떠한 영향을 미치는지 분석하여 향후 지식관리시스템을 활성화하기 위한 방안을 제시하고자 한다.

• 한국의류학회지
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• 제27권9_10호
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• pp.1081-1092
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• 2003

The purpose of this study was to identify the current situation of textiles and apparel firms in the overseas markets and to examine the relationship between firms' characteristic(i.e., sales volume) and international marketing strategies. A random sample of 311 textiles and apparel firms were selected. The survey design method was used to test conceptual framework. Adjusted response rate was 33.4%(n=115). Descriptive analysis (i.e., frequency, percent) and $\chi$$^2$-test were used for data analysis. About the current situation of textiles and apparel firms in the overseas markets, the motivation for international market entry was highly found to expand their operation from domestic to international market, and most firms were found to be involved with OEMs(Original Equipment Manufacturers) as an entry mode for international market. China and US market were the most popular market among Korean textiles and apparel firms. Product differentiation strategy, pricing strategy based on manufacturing cost and buyer's offering price, place strategy using foreign buyers and participating a few international exhibition were frequently used among Korean textiles and apparel firms for international marketing. Among textile firms, sales volume was related to product strategies(product development), price strategy(buyer's offer) and place strategy(channel). Among apparel firms, product strategy(product labeling), price strategy(price satisfaction). The findings of this can be used when Korean textiles and apparel firms do strategic planning and evaluate the international marketing strategies. Also information and results of this study may assist policy makers to develop better ideas and strategies for textiles and apparel industry.