• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.235-242
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• 2008

An innovative Panel ExTension SATellite(PETSAT) and propulsion system for PETSAT, are presented in this paper. First, we outline what PETSAT is. Next, based on PETSAT ethos, design policy of the propulsion system is provided. According to the policy, we designed propulsion system and concretely estimated and assembled mono-propellant and bi-propellant systems, and it indicated that mono-propellant propulsion with 50-60 seconds of specific impulse and 1 N of thrust is probable. In the case of bi-propellant, 120-150 seconds of specific impulse is valid even based on the design policy. We conducted captive tests of mono-propellant and bi-propellant propulsions with a breadboard model of propulsion system for PETSAT, and obtained good operations and performances. Based on the test results, we designed and manufactured flight model propulsion system for PETSAT. We are planning to demonstrate it in SOHLA-2L project progressed by the Space Oriented Higashiosaka Leading Association(SOHLA). SOHLA-2L will be the first on-orbit demonstrator of PETSAT in 2008.

• Proceedings of the Korean Information Science Society Conference
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• 2002.04a
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• pp.10-12
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• 2002

사용자의 요구와 인터넷 어플리케이션의 발달로 규모가 큰 미디어 오브젝트의 수가 급증하고 있다. 따라서 네트워크 전송비용은 반드시 고려해야 하는 중요한 요소이다. 본 논문에서는 기존 프락시 캐시 교체 정책들을 분석하고, 이를 개선한 G-N 및 L-N 정책을 제안한다. 이것은 프락시 캐시 소프트웨어인 'Squid'에서 채택하고있는 GDSF와 LFU-DA 정책에 네트워크 전송 비용을 추가하여 확장한 알고리즘이다. 시뮬레이션을 통하여 기존의 알고리즘과 비교해 본 결과, 평균 응답 시간을 10%이상 감소시킬 수 있었으며, 추가로 드는 비용(Processing Overhead)은 3게 증가하지 아니 하였음을 확인하였다.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.19 no.39
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• pp.205-218
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• 1996

본 연구는 써버의 고장을 허용하는 단수써버 Queueing 시스템의 확률적 모델을 제시한 것으로, 써버는 N 제어 정책에 의하여 작동되며, 도착은 Stationary compound poisson에 의하여 이루어지고, 서비스 시간에 대한 분포는 Erlang에 의하여 발생하며, 수리시간에 대한 분포는 평균이 일정한 분포에 의하여 생성되는 경우를 고려하였다. 또한 고장간격 시간은 일정한 평균을 가진 임의의 분포를 가진 Renewal process에 의한다고 가정하였고, 완료 시간의 개념은 재생과정의 적용방법에 의하여 유도할 수 있으며, 시스템 크기의 확율 생성 함수의 값이 구해진다는 것을 제시하였다.

• Journal of the Korean Society of Fashion and Beauty
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• v.2 no.1 s.1
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• pp.75-85
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• 2004

Since, N-Generation equipped with internet seek for more reasonable consumption, they are seeking positive toward the latest vogue and having strong desires for better consumption. In such, the makeup industry produces makeup products specially made for the N-Generation. The products not only directly reflect the skin features of the N-Generation but also form different. Therefore, the purpose of this study tries to find out the distinctive consumption of the N-Generation that rises as the new consumer group of the new millennium in the makeup industry and their purchase behaviors. The investigation was done on 200 females aging from 13 to 23. Investigation method was done face-to-face interview conducted from Dec. 1st to Dec. 8th, 2003 for a week. Through the study, it can be seen that the network generation is interested in e-commerce and such trend show the possibility of makeup market in the e-commerce. Also, it is suggested that the study can be used as useful data when establishing marketing strategies in the relevant industry. The result where the N-generation demands for distinctive products just for them can be used as an alternative plan of market division policy.

• Korean Journal of Childcare and Education
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• v.9 no.1
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• pp.81-100
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• 2013

This study has attempted to suggest the direction for child care policy for 0-2 year old children in Korea from analysis on the issues included in the policy for free child care services of the Korean Government. For the analysis, such materials as governmental statistical reports of child care and policy and articles regarding free child care service in daily news papers during 2012 have been collected. From this study, it has been suggested that the policy for free child care for 0-2 year old children, in future, should take into account reliably carrying out matemity leave and parental leave arrangements, equity childcare support for working couples, realization of parental subsidies, expand parental choice, introduction of a small family day care system, providing information and knowledge on the development of infants and parenting. The suggestions of this study will contribute to the development and practice of an effective child care policy for 0-2 year children, which consider the needs and requirements of young children and their parents.

• Journal of the Korean Solar Energy Society
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• v.39 no.4
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• pp.41-54
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• 2019

The proportion of solar photovoltaic power generation has steadily increased in the power trade market. Solar energy forecast is highly important for the stable trade of volatile solar energy in the existing power trade market, and it is necessary to identify accurately any forecast error according to the forecast lead time. This paper analyzes the latest study trend in solar energy forecast overseas and presents a consistent comparative assessment by adopting a single statistical variable (nRMSE) for forecast errors according to lead time and forecast technology.

• Journal of KIISE:Computer Systems and Theory
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• v.29 no.7
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• pp.369-376
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• 2002

Although LRU is not adequate for database that has non-uniform reference pattern, it has been adopted in most database systems due to the absence of the proper alternative. We analyze database block reference pattern with the realistic database trace. Based on this analysis, we propose a new cache replacement policy. Trace analysis shows that extremely non-popular blocks take up about 70 % of the entire blocks. The influence of recency on blocks' re-reference likelihood is at first strong due to temporal locality, however, it rapidly decreases and eventually becomes negligible as stack distance increases. Based on this observation, RCB(Reference Characteristic Based) cache replacement policy, which we propose in this paper, classifies the entire blocks into four block groups by blocks' recency and re-reference likelihood, and operates different priority evaluation methods for each block group. RCB policy evicts non-popular blocks more quickly than the others and evaluates the priority of the block by frequency that has not been referenced for a long time. In a trace-driven simulation, RCB delivers a better performance than the existing polices(LRU, 2Q, LRU-K, LRFU). Especially compared to LRU. It reduces miss count by 5~l2.7%. Time complexity of RCB is O(1), which is the same with LRU and 2Q and superior to LRU-K(O(log$_2$N)) and LRFU(O(l) ~ O(log$_2$N)).

• Journal of Digital Convergence
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• v.20 no.5
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• pp.599-608
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• 2022

There has been criticism that the government-led makerspace did not reflect the actual demand of makers, so there was a limit to performance creation. In this regard, the study aims to diagnose the current status and problems of makerspace and to suggest the implication to respond to policy demand. To this end, we analyzed the current status of makerspace by utilizing the government documents. Then, we conducted a survey of SMEs related to ICT devices that experienced makerspace, and analyzed their opinions on D·N·A technology demand, management difficulties, and governments' support policies. As results, the study proposed several improvement measures to upgrade makerspace as a digital conversion platform as follows. First, due to the nature of the existing industry for introducing D·N·A technology, there is a limit for companies to enter the market on their own, so comprehensive support from the government is needed. Second, it is necessary to establish and expand an empirical test bed for the development of new products and services so that various types of metaverse contents can be discovered and digital transformation convergence models of existing businesses can be derived. Third, by modifying the support method to operate the makerspace as a platform that implements the government-led start-up support policy, boldly transfer what the private sector can do well to the private sector. The participants of Industry·University·Institute Collaboration should freely share ideas and help the common problem be solved. Based on the problems and the findings for improvement, it is expected that the current makerspace would be upgraded to a digital conversion platform suitable for the demand of the field.

• Health Policy and Management
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• v.26 no.3
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• pp.219-225
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• 2016

Background: Intention to leave was an important managerial issue among physicians working in public health centers. This study was conducted to explore the relationship between job participations and intention to leave among physicians working in health centers. Methods: A cross-sectional questionnaire survey was conducted to gather information about job participation, intention to leave and demographics among physicians (n=243) in public health centers in Korea. Job participation was measured by 15 items categorized 3 dimensions. Multiple regression analysis was performed to determine the effect of job participation on intent to leave among physicians working in public health center. Results: Participation of medical treatment and administrative job were significantly associated with intention to leave adjusted for sex, age, income, working area, working duration, tenure, and overall job satisfaction. Therefore, physicians who actively participated in administrative job showed a lower turnover intention. Physicians who actively participated in medical treatment job had a higher quit intention. Conclusion: To retain qualified physicians in public health center, education should be reinforced to physician for administrative capacity building.

• Industrial Engineering and Management Systems
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• v.8 no.1
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• pp.1-13
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• 2009

This paper presents a coordinated planning model of price-dependent demand for a single-manufacturer and a single-retailer. The demand is assumed to be normally distributed, with its mean being price dependent. The manufacturer and retailer coordinate with each other to jointly and simultaneously determine the retail selling price and the retailer order quantity to maximize the joint expected total profit. This model is then compared to a 'returns' policy model where manufacturer buys back unsold items from the retailers. It is shown that the optimal total profit is higher for coordinated planning model than that for the returns policy model, in which the retail price is set by the retailer. A compensation or profit sharing scheme is then suggested and it is shown that the coordinated model with profit sharing yields a 'win-win' situation. Numerical results are presented to illustrate the profit patterns for both linear and nonlinear demand functions. The coordinated planning model, in addition, has a lower optimal price than for a returns policy model, which would result in higher sales, thus expanding the markets for the whole supply chain.