• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2012년도 제38회 춘계학술대회논문집
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• pp.304-308
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• 2012

본 연구는 에틸렌-공기 혼합물로 채워져 있는 변형 가능한 구리 관에서의 초음속 화염 전파를 수치적으로 살펴보았다. 탄화수소의 화염 전파를 해석하기 위하여 지배방정식으로 Navier-Stokes 방정식과 Arrhenius 형태의 1단계 화학 반응식을 활용하였으며 변형 가능한 관을 해석하기 위하여 Inviscid Euler 방정식을 활용하였다. 또한, 두 물질 간 경계면 추적을 위하여 Level-set 기법을, 경계값 결정을 위하여 ghost fluid 기법을 사용하였다. 이러한 수치적 기법을 바탕으로 관의 변화에 따른 초음속 화염 내 팽창파의 전파 및 그에 따른 간섭 현상을 밀도 및 속도 변화를 통해 확인하였으며 초음속 화염 전파에도 안전성이 확보되는 최소 관 두께를 예측할 수 있는 수치적 기반을 마련하였다.

• 한국게임학회 논문지
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• 제15권4호
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• pp.169-178
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• 2015

다양한 수준의 게임 난이도를 사용자에게 제공하는 것은 게임 개발 시 주요 고려 사항 중 하나이다. 본 논문에서는 1인용 자동차 주행 게임에서 주어진 난이도를 갖도록 주행 트랙에 도전들을 배치하는 방법을 제안한다. 여기서 도전은 자동차 주행을 방해하는 장애물을 말하고, 게임 난이도는 트랙 한 바퀴를 도는데 필요한 예상 주행 시간으로 나타낼 수 있다. 제안된 방법에서는 도전 배치 문제를 IP(Integer Programming) 문제로 모델링한 후, LP 완화 및 시뮬레이티드 어닐링 방법으로 해를 구한다. 실험 결과, 주어진 목표 시간에 맞는 주행 시간을 갖는 도전 배치를 구할 수 있었다. 이들 도전 배치를 트랙에 적용한 후 시험 주행해 봄으로써, 실제 주행 시간은 평균적으로 해당 도전 배치의 목표 시간과 일치함을 보였다. 제안된 방법은 사용자에게 다양한 난이도의 게임 플레이를 제공함으로써, 게임의 흥미와 몰입감을 높일 것이다.

• Asia pacific journal of information systems
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• 제18권3호
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• pp.1-20
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• 2008

Based on the multi-attribute utility theory (MAUT), we present a survey method to measure consumer preferences. The multi-attribute utility theory has been used to make decisions in OR/MS field; however, we show that the method can be effectively used to estimate the demand for new services by measuring individual level utility function. Because conjoint method has been widely used to measure consumer preferences for new products and services, we compare the pros and cons of two consumer preference survey methods. Further, we illustrate how swing weighing method can be effectively used to elicit customer preferences especially for new telecommunications services, Multi-attribute utility theory is a compositional approach for modeling customer preference, in which researchers calculate overall service utility by summing up the evaluation results for each attribute. On the contrary, conjoint method is a decompositional approach, which requires holistic evaluations for profiles. Partworth for each attribute is derived or estimated based on the evaluation, and finally consumer preferences for each profile are calculated. However, if the profiles are quite new and unfamiliar to the survey respondents, they will find it very difficult to accurately evaluate the profiles. We believe that the multi-attribute utility theory-based survey method is more appropriate than the conjoint method, because respondents only need to assess attribute level preferences and not holistic assessment. We chose swing weighting method among many weight assessment methods in multi-attribute utility theory, because it is designed to perform in a simple and fast manner. As illustrated in Clemen and Reilly (2001), to assess swing weights, the first step is to create the worst possible outcome as a benchmark by setting the worst level on each of the attributes. Then, each of the succeeding rows "swings" one of the attributes from worst to best. Upon constructing the swing table, respondents rank order the outcomes (rows). The next step is to rate the outcomes in which the rating for the benchmark is set to be 0 and the rating for the best outcome to be 100, and the ratings for other outcomes are determined in the ranges between 0 and 100. In calculating weight for each attribute, ratings are normalized by the total sum of all ratings. To demonstrate the applicability of the approach, we elicited and analyzed individual-level customer preference for new telecommunication services-WiBro and HSDPA. We began with a randomly selected 800 interviewees, and reduced them to 432 because other remaining ones were related to the people who did not show strong intention for subscription to new telecommunications services. For each combination of content and handset, number of responses which favored WiBro and HSDPA were counted, respectively. It was assumed that interviewee favors a specific service when expected utility is greater than that of competing service(s). Then, the market share of each service was calculated by normalizing the total number of responses which preferred each service. Holistic evaluation of new and unfamiliar service is a tough challenge for survey respondents. We have developed a simple and easy method to assess individual level preference by estimating weight of each attribute. Swing method was applied for this purpose. We believe that estimating individual level preference will be quite flexibly used to predict market performance of new services in many different business environments.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권11호
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• pp.5588-5613
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• 2018

Virtualization technology has been widely applied in the area of computer security research that provides a new method for system protection. It has been a hotspot in system security research at present. Virtualization technology brings new risk as well as progress to computer operating system (OS). A multi-level perception security model using virtualization is proposed to deal with the problems of over-simplification of risk models, unreliable assumption of secure virtual machine monitor (VMM) and insufficient integration with virtualization technology in security design. Adopting the enhanced isolation mechanism of address space, the security perception units can be protected from risk environment. Based on parallel perceiving by the secure domain possessing with the same privilege level as VMM, a mechanism is established to ensure the security of VMM. In addition, a special pathway is set up to strengthen the ability of information interaction in the light of making reverse use of the method of covert channel. The evaluation results show that the proposed model is able to obtain the valuable risk information of system while ensuring the integrity of security perception units, and it can effectively identify the abnormal state of target system without significantly increasing the extra overhead.

• 한국정밀공학회지
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• 제9권1호
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• pp.96-105
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• 1992

A study on the construction of a CAD/CAM system operated by 16 Bit PC basic language, for machining sculptured surface of die, was carried out. The system consists of 2 steps i.e., process for geometric modelling by wire frame and process for machining data generation. Geometric modelling for sculptured surface is made by the point data fitting, parallel sweeping, normal sweeping and linear connection of cross section curve. Machining data are gained by cutter off-set of geometric model data and machining carried out by DNC. This system is to be proved enough for rough cutting by actual machining experiment. But, for becoming a high level system, another method of cutter off-set has to be regarded and system must be reconstructed by another program language.

• 국제학술발표논문집
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• The 5th International Conference on Construction Engineering and Project Management
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• pp.494-496
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• 2013

Cost-Benefit Analysis (CBA) is a systematic optimization process that allows users to compare different alternatives and to determine if a project is a solid investment. Many state DOTs have included CBA in their pavement management systems (PMSs) to help allocate state funds for maintenance, rehabilitation, resurfacing, and reconstruction of pavements. In a typical CBA, each pavement type has an assigned weight factor which represents the level of importance of this pavement type. To conduct an accurate CBA, it is essential to select appropriate weight factors. Arbitrarily assigning weights factors to pavements can lead to biased and inaccurate funding allocation decisions. The purpose for this paper is to outline a method to develop an ideal set of weight factors that can be utilized to conduct more accurate CBA. To this end, a matrix of all possible weight factors sets was developed. CBA was conducted for each set of weight factors to obtain a population of possible optimization solutions. Then a regression analysis was performed to establish the relationship between benefit and weight factors. Finally, a multi-objective genetic algorithm was applied to select the optimal set of weight factors. The findings from this study can be used by state DOTs to strategically manage their roadway systems in a cost effective manner.

• 대한수학회보
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• 제55권4호
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• pp.1161-1178
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• 2018

In this paper, we consider the Cauchy problem for a class of nonlinear sixth-order wave equation. The global existence and the finite time blow-up for the problem are proved by the potential well method at both low and critical initial energy levels. Furthermore, we present some sufficient conditions on initial data such that the weak solution exists globally at supercritical initial energy level by introducing a new stable set.

• Journal of Electrical Engineering and Technology
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• 제12권4호
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• pp.1649-1656
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• 2017

This paper addresses the control problem of a laboratory-level 2 degree-of-freedom helicopter. The exact fuzzy model in a Takagi - Sugeno form is constructed by the sector nonlinearity technique, and is then represented as a set of uncertain linear systems. Output-tracking controller is designed in terms of linear matrix inequalities and the closed-loop stability is rigorously analyzed. Experimental evaluation shows that the proposed method is of benefit to many real industrial plants.

• 대한안전경영과학회지
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• 제11권3호
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• pp.1-9
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• 2009

The present management of the domestic and international advanced enterprises is transferring the systems and the regulations to the prevention system management. Expecially, KOSHA (Korea Occupational Safety & Health Agency) in Korea has supported to set up the OSHMS (Occupational Safety & Health Management System) by KOSHA 18001 since 1997. But small & medium enterprises (SMS) has many difficulties to set up the OSHMS system because of limited natural and human resources. In this study, the rating system as a judgment method of an OSHMS based on the certification standard of the OSHMS, which was suggested in previous study, was developed for SMS to adopt voluntarily the OSHMS, certify KOSHA 18001, and improve the safety and health level.

• 한국산학기술학회논문지
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• 제22권3호
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• pp.671-678
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• 2021

2020 국방기술통제목록 연구는 기술보호 등급분류 설정 시 전문가 의견을 수렴하여 조사항목 설정, 등급분류 기준 설정 방법으로 정성적 기준에 의존했다. 이를 보완하여 기술보호 등급분류 설정의 정량적 기준을 제시하고자 본 연구를 수행했고, 본 논문에서는 통계기법을 적용한 기술보호 등급분류 설정 방법론을 제시하였다. 연구절차는 3단계로 진행하여 조사항목 설정, 기술보호 등급분류의 당위성을 입증하고자 하였다. 첫째, 판단지표를 선정하기 위해 2020 국방기술통제목록 작성 시 조사되었던 6개 조사항목, 즉 요소기술의 상대기술수준, 체계구현관점중요도, 국가안보관점중요도, 난이도, 기술이전기피, 파급효과에 대한 통계적 분석, 신뢰도 검증을 수행하여 조사항목을 설정하였다. 둘째, 선정된 조사항목을 AHP기법으로 계층화하여 전문가 설문조사를 수행하고 의견을 점수화했다. 도출된 조사항목의 가중치를 이용하여 요소기술의 점수를 산출했다. 마지막으로 정규분포 산포도와 사분위수 산출 방식, 카플란마이어 추정치 비율을 연계하여 3단계 등급설정을 하고, 723개 요소기술 점수의 카플란마이어 추정치값에 적용하여 기술보호등급을 3단계 기준점수를 제시하였다. 본 연구를 통해 설정된 등급설정표를 이용하여 일관성 있는 객관적인 기준을 제시할 수 있을 것이라 판단된다.