검색결과

검색조건
좁혀보기
검색필터
결과 내 재검색

간행물

    분야

      발행연도

      -

        검색결과 949

        321.
        2016.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Quality function deployment (QFD) is a widely adopted customer-oriented product development methodology by translating customer requirements (CRs) into technical attributes (TAs), and subsequently into parts characteristics, process plans, and manufacturing operations. A main activity in QFD planning process is the determination of the target levels of TAs of a product so as to achieve a high level of customer satisfaction using the data or information included in the houses of quality (HoQ). Gathering the information or data for a HoQ may involve various inputs in the form of linguistic data which are inherently vague, or human perception, judgement and evaluation for the information and data. This research focuses on how to deal with this kind of impreciseness in QFD optimization. In this paper, it is assumed as more realistic situation that the values of TAs are taken as discrete, which means each TA has a few alternatives, as well as the customer satisfaction level acquired by each alternative of TAs and related cost are determined based on subjective or imprecise information and/or data. To handle these imprecise information and/or data, an approach using some basic definitions of fuzzy sets and the signed distance method for ranking fuzzy numbers is proposed. An example of a washing machine under two-segment market is provided for illustrating the proposed approach, and in this example, the difference between the optimal solution from the fuzzy model and that from the crisp model is compared as well as the advantage of using the fuzzy model is drawn.
        4,300원
        322.
        2016.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This paper considers the allocation and engagement scheduling problem of interceptor missiles, and the problem was formulated by using MIP (mixed integer programming) in the previous research. The objective of the model is the maximization of total intercept altitude instead of the more conventional objective such as the minimization of surviving target value. The concept of the time window was used to model the engagement situation and a continuous time is assumed for flying times of the both missiles. The MIP formulation of the problem is very complex due to the complexity of the real problem itself. Hence, the finding of an efficient optimal solution procedure seems to be difficult. In this paper, an efficient genetic algorithm is developed by improving a general genetic algorithm. The improvement is achieved by carefully analyzing the structure of the formulation. Specifically, the new algorithm includes an enhanced repair process and a crossover operation which utilizes the idea of the PSO (particle swarm optimization). Then, the algorithm is throughly tested on 50 randomly generated engagement scenarios, and its performance is compared with that of a commercial package and a more general genetic algorithm, respectively. The results indicate that the new algorithm consistently performs better than a general genetic algorithm. Also, the new algorithm generates much better results than those by the commercial package on several test cases when the execution time of the commercial package is limited to 8,000 seconds, which is about two hours and 13 minutes. Moreover, it obtains a solution within 0.13 ~33.34 seconds depending on the size of scenarios.
        4,800원
        323.
        2016.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Recently, owing to the development of ICT industry and wide spread of smart phone, the number of people who use car sharing service are increased rapidly. Currently two-way car sharing system with same rental and return locations are mainly operated since this system can be easily implemented and maintained. Currently the demand of one-way car sharing service has increase explosively. But this system have several obstacle in operation, especially, vehicle stock imbalance issues which invoke vehicle relocation. Hence in this study, we present an optimization approach to depot location and relocation policy in one-way car sharing systems. At first, we modelled as mixed-integer programming models whose objective is to maximize the profits of a car sharing organization considering all the revenues and costs involved and several constraints of relocation policy. And to solve this problem efficiently, we proposed a new method based on particle swarm optimization, which is one of powerful meta-heuristic method. The practical usefulness of the approach is illustrated with a case study involving satellite cities in Seoul Metrolitan Area including several candidate area where this kind systems have not been installed yet and already operating area. Our proposed approach produced plausible solutions with rapid computational time and a little deviation from optimal solution obtained by CPLEX Optimizer. Also we can find that particle swarm optimization method can be used as efficient method with various constraints. Hence based on this results, we can grasp a clear insight into the impact of depot location and relocation policy schemes on the profitability of such systems.
        4,000원
        324.
        2016.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study deals with optimized structural analysis of stainless rectangular water reservoirs with 5,000ton capacity for various combined load cases. The objective of this study is to propose most efficient structural models through the comparison of various model cases. In order to perform an optimized analysis, three dimensional finite element analyses are carried out for large sized models. The numerical results obtained provides the detailed size and thickness for optimal design of water reservoir. In particular, results reported in this paper show the influence of various types of loading and dimensions of the wall and stiffened column on the structural behavior of the large sized water tanks.
        4,000원
        325.
        2016.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        As a preparation of a design standard regarding road facilities, such as cantilever columns for traffic lights, optimum design and risk assessment for foundation of street lights on highways are proposed. The preliminary evaluation of optimization with reliability assessment resultantly makes it possible to reduce not only the duration of construction but the cost of construction as well. Ultimate limit states and constraints functions are selected for the sliding, overturning and settlement of the foundation under external loads from super and sub-structures itself. An example foundation under the super structure of height 12m, is optimized as 30% decreased embedded depth of foundation, in which as increasing the depth of embedded connection parts, the necessary depth of foundation is deceased. However, the optimum depths and the reliability indices are sensitively dependent with earth properties and dimensions of foundation.
        4,000원
        328.
        2016.05 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Sea cucumber (SC) or Stichopus japonicas is widely used in East Asia as a traditional medical component for the treatment of asthma, arthritis, and sinus congestion. The hydrolysate of SC (HSC) after treatment with a protease is also widely used as an ingredient for processed food application such as noodles. Tensile force and deformation are important texture properties of noodle. The peptides prepared by hydrolyzing SC could affect the tensile properties of noodle, as well as DPPH radical scavenging. The objectives of this study were to characterize the tensile properties, the texture properties, color, and DPPH radical scavenging of noodle with HSC and to determine an optimum formulation of dough with HSC for noodle. The HSC was prepared by hydrolyzing dried SC powder with distilled water (DW) and a protease, Protamex (Novozyme Nordisk, Bagsvaerd, Danmark). The tensile properties and antioxidant activity were used as major constraint functions for the optimization. The optimum ratio was determined as flour:water:HSC=69.27:22.48:7.05 (w/w). Increasing the amount of HSC in the formulation increased the tensile force but no significant difference was observed in the deformation.
        4,000원
        329.
        2016.05 구독 인증기관·개인회원 무료
        공기를 이용한 분리막 세정은 MBR공정에서 fouling 억제 및 장기간 성능을 유지시키는 주요 핵심 방법이다. 기존의 MBR은 공기의 부상하는 힘을 이용한 방식으로 적은 동력을 이용하지만 주변환경, 유체흐름 및 원수성상 등으로 다양한 문제가 예기치 못하게 발생한다. 이를 개선하기 위하여 본사에서는 간헐적으로 가압 공기를 이용하여 fouling 억제 및 플럭스의 안정화를 이루는 i-MBR 모듈을 개발하였다. i-MBR 모듈에 들어가는 산기관을 개량하여 공기에 의한 파울링 억제 효과를 최대한 높이는 연구를 진행하였다. 산기관과 air의 상관관계를 진행하고, 이를 기반으로 pilot-scale 장치를 세팅하여 flux recovery 및 내구성 등을 비교분석하 였다.
        330.
        2016.05 구독 인증기관·개인회원 무료
        재래식 해수담수화 수평적 압력용기 설계는 후단에 있는 역삼투막에는 농축수에 의해 수질악화 및 생산수저감 등이 동반된다. 이를 해결하기 위해 본 연구에서는 개념적인 중앙 주입식 압력용기가 생산수 단가에 미치는 영향과 역삼투 공정 설계 시 주요 인자들이 성능에 미치는 영향을 조사를 위해 상업화된 역삼 투 프로그램인 ROSA를 이용하여 분석하였다. 그 결과 중앙 주입식 압력용기를 이용할 경우 총괄적인 회수율과 SEC 측면에서 성능이 저하하지만, 막 모듈 당 생산되는 생산수량이 증가하는 것으로 나타났다. 또한 생산수의 수질개선은 2단 설계의 용량 감소로 인하여 건설비 저감으로 연계되는 것으로 조사되었다. 본 연구는 국토교통부 플랜트연구사업의 연구비지원(과제번호 16IFIP-B089908-03)에 의해 수행되었습니다.
        331.
        2016.05 구독 인증기관·개인회원 무료
        분리막은 해수담수화를 포함한 수처리 분야에 폭 넓게 사용되고 있으며, 현장 적용을 위해서는 분리막의 모듈 적용은 필수적이다. 본 발표는 막 모듈 최적화 연구를 통해 해수담수화용 분리막 모듈의 성능저하 요인 분석을 분석하고 모듈 최적화 방향을 제시하고자 한다. 분리막 모듈 최적화 연구 진행을 위해 전산유 체역학과 이동현상 모델을 도입하였다. 이를 바탕으로 유한요소법을 이용하여 해수담수화 막 모듈 모델을 개발하였다. 개발된 모델을 기반으로 해수담수화용 막 모듈 형태에 따른 모듈 내 유체 거동 및 위치에 따른 성능 분포를 계산하였다. 본 연구를 통해 해수담수화 막 모듈 모델을 개발하였으며, 이를 기반으로 다양한 형태의 모듈 내 성능 분포를 도출하였다. 본 연구는 막 모듈 성능 분석 및 개선에 활용될 수 있다.
        332.
        2016.05 구독 인증기관·개인회원 무료
        다단 분리막 공정은 압력변환, 열교환, 수분제거등을 위한 공정 설비들과 연계 운영된다. 또한 sweeping 가스를 도입하기도 하고, 분리막 연결 형태를 변경 하기도 하며, 압력비등을 조절하기도 한다. 따라서, 분리막 공정설계는 막 면적 및 운전 압력을 결정을 포함하여 다단 분리막의 configuration 선정, 분리막 소 재의 선택, 공정의 시스템적 구성, 부가 설비와의 통합 설계 등 여러 설계 요소 들을 통합적으로 분석하며 최적 공정을 구성하게 된다. 본 발표에서는 컴퓨터를 활용한 모델링, 전산 모사 및 최적화를 통해 최적의 분리막 공정 및 운전 조건 을 도출하는 기법들을 설명하며, 이러한 전산적 설계 기법들을 분리막 공정 스케일업과 신공정 개발에 활용하는 방안에 대하여 소개하고자 한다.
        333.
        2016.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The objective of this study is to investigate the effect of closed and open type on the load characteristics and amount of waste in tubular shaft and solid shaft for optimal design. The open and closed type were designed by 6 stage processes and applied for analysis. The coefficient of friction was set to Oil_Cold conditions as refer to the analysis library. It is found that the actual underfill phenomenon was not observed on the closed and open type. The metal flow of the closed and open type are revealed that the folding phenomenon was not occurred, thus there is no problem in actual production. The load characteristics are similar from stage 1 to stage 3 due to the same geometry of upper and lower die. However, tubular shaft and solid shaft are decreased 26% and 32% load from stage 4 to stage 6. In case of open type, amount of waste of tubular shaft and solid shaft are 11g and 14g, respectively.
        4,000원
        334.
        2016.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The objective of this study was to investigate the optimal design on the tubular shaft and solid shaft for A-IMS of commercial vehicle. The tubular shaft and the solid shaft were designed by 6 stage processes and the results were analyzed by using a finite element analysis method. The coefficient of friction was set to Oil_Cold conditions as referred to the analysis library. It was found that the actual underfill phenomenon was not observed on the tubular shaft and solid shaft. The metal flow of the tubular shaft and solid shaft revealed that the folding phenomenon was not occurred, so there is no problem in actual production. Principal stress and load characteristics of tubular shaft were higher than those of solid shaft since the tubular shaft has many deformation from stage 1 to stage 3.
        4,000원
        335.
        2016.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The purpose of this study was to determine the optimum conditions of solvent extraction type and solvent concentration (60, 70, 80%, v/v), extraction time (30, 80, 130 mins) and extraction temperature (10, 15, 20℃) in order to increase the antioxidant activity of the chia seed. The total polyphenol content and DPPH radical scavenging activity was measured by using response surface methodology (RSM) to establish the optimal conditions. Using ethanol and methanol extractions at extraction concentrations of 60%, and time and temperature of 130 mins and 20℃, the maximum total polyphenol content was 871.00 mg% (R2=0.9507) and 557.70 mg% (R2=0.9784) for ethanol and methanol extraction respectively. Using the same extraction conditions, the maximum level of DPPH radical scavenging activity was 72.14% (R2=0.9675) and 52.79% (R2=0.9524) for ethanol and methanol extraction respectively. The results indicate that ethanol extracts showed a higher antioxidant activity than methanol extracts. The ethanol extraction conditions of response surface analysis (RSA) were affected more by ethanol concentration than by extraction time or temperature. In contrast, the methanol extraction conditions of response surface analysis (RSA) were affected more by extraction time. Based on the RSM, the optimum ethanol extraction conditions were the following: extraction concentration, 63%: time, 100 mins: and temperature, 18℃. The optimum methanol extraction conditions were the following: extraction concentration, 65%; time, 120 mins; and temperature, 16℃.
        4,000원
        336.
        2016.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The purpose of this study was to determine the optimal composite recipe of rice muffins with 3 concentrations of Spergularia marina L. Griseb, sugar and grape seed oil, using central composite design. In addition, the mixing condition of rice muffins was optimized by subjecting it to sensory evaluation and mechanical and physicochemical analysis using response surface methodology (RSM). In regard to its antioxidant effects, Spergularia marina L. Griseb had a total phenol and flavonoid contents and DPPH free radical scavenging activity of 17.03 mg/g, 5.13 mg/g and 17.21%, respectively. The results of mechanical and physicochemical analysis showed significant values for lightness, redness, yellowness, hardness, springiness, chewiness, gumminess, cohesiveness, height, volume, weight, specific volume, loss rate, pH, moisture, sweetness and saltiness (p<0.05), and the results of sensory evaluation showed significant values for color, flavor, taste, softness, appearance and overall quality (p<0.05). As results, optimal sensory ratio was found to be 6.69 g of Spergularia marina L. Griseb, 41.89 g of sugar and 30.48 g of grape seed oil.
        4,600원
        337.
        2016.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        국지적 스케일에서 작동하는 주택시장의 공간성을 반영하는 개념 중 하나가 주택시장지역(housing market area, HMA)이다. 주택시장의 역동성을 분석하고 주택 수요와 공급에 대한 체계적인 계획 수립을 위한 틀을 제공하기 위해서는 먼저 HMA를 구획할 필요가 있다. 본 연구의 목적은 HMA 구획을 위한 혼합 정수 계획법(mixed integer programming, MIP) 형태의 공간 최적화 모형을 개발하는 것이다. HMA 구획을 위한 가장 중요한 기준은 HMA의 내적 응집력을 의미하는 자족성이다. 구획된 HMA 전체를 대상으로 평가되는 전역적 자족성을 목적함수 형태로, 개별 HMA 별로 평가되는 국지적 자족성을 제약조건 형태로 고려하였다. 서울시 구별 인구이동을 사례로 개발된 최적화 모형을 적용한 결과 2010년의 경우 공급-측면 및 수요-측면 자족도 수준이 0.70일 때 3개, 0.65일 때 4개의 HMA가 구획되었다. 휴리스틱 기법인 Intramax 결과와 비교한 결과 첫째, Intramax와는 달리 MIP 접근을 통하여 얻은 HMA는 계층적으로 조직되지 않았다. 둘째, Intramax 결과는 국지적인 해인데 반하여, MIP 결과는 전역적 최적해였다. 셋째, 전역적 자족도의 극대화가 반드시 모든 HMA에서 국지적 자족도의 향상을 가져오지는 않았다. 이러한 결과는 HMA의 구조를 보다 명확하게 이해하기 위해서는 MIP 접근이 필요하며, HMA 구획 방법론으로서 Intramax 접근이 분명한 한계를 갖는다는 것을 의미한다.
        4,500원
        339.
        2016.04 구독 인증기관·개인회원 무료
        감자녹말을 이용하여 제조한 무정형입자감자녹말(Amorphous Granular Potato Starch, AGPS)은 호화가 되었지만 녹 말입자의 모양은 유지되고 복굴절성은 소실되는 화학적 변성녹말(modified starch)이다. 이러한 AGPS를 만들기 위한 최적화 조건을 찾기 위해서 반응표면분석법(Response Surface Methodology)과 central composite design (CCD)를 사용 하였다. 최적화시키기 위한 변수는 에탄올 함량과 열처리 온도로 선정하였고, 예비실험을 거쳐 그 범위를 각각 48~62%, 88~96℃로 정하였다. 실험 디자인은 55%, 92℃를 중심점으로 총 11개의 실험이 디자인되었다. 11개의 실험 디자인은 녹말입자관찰의 결과인 녹말입자의 유지와 복굴절성 손실의 정도를 관능평가방법을 이용하여 그 결과 값을 모델적용 에 적용하였다. 그 결과 AGPS 제조의 최적 조건으로 에탄올 함량 53%, 열처리 온도 94℃가 선정되었다. 선정된 조건 을 바탕으로 10g의 일반감자녹말을 100mL EtOH (53%)에 분산시킨 후 94℃에서 20분간 가열하였다. EtOH 수세는 3000 rpm으로 4℃에서 5분간 원심분리를 이용해 3회 반복하였다. 건조는 40℃에서 24시간 하였고 건조가 끝난 시료들 은 100 mesh 체를 이용해 거른 후 시료로 사용하였다. 최적화 조건으로 제조된 감자녹말이 AGPS가 맞는지 확인하기 위해 녹말입자관찰, Differential Scanning Calorimeter (DSC), X ray Diffraction (XRD) 을 측정하였다. 녹말입자관찰은 광학 및 편광현미경을 이용하여 분석하였다. AGPS는 물에 잘 분산되어 냉수에 분산시킨 후 관찰하였다. 실험 결과 녹 말입자는 부피가 조금 더 커졌지만 모양을 유지하였고 복굴절성은 완전히 소실되었다. DSC 분석결과 일반감자녹말은 60℃부근에서 감자녹말의 전형적인 호화피크를 보였고 AGPS는 호화피크를 보이지 않아 호화가 이미 되어있음을 확 인하였다. X-ray diffraction 분석 결과 일반감자녹말은 전형적인 B-type crystal pattern을 보였다. 하지만 AGPS는 결정 영역에서 피크가 보이지 않으며 완만한 곡선의 무정형 패턴을 보였다. 일반감자녹말과 AGPS를 서로 비교하여 물리화 학적 특성을 알아본 결과 RSM을 이용하여 제시한 조건으로 제조된 AGPS는 녹말입자의 모양을 유지하며 복굴절성은 소실되었고, 일반감자녹말의 호화온도에서 아무런 호화피크를 보이지 않았고 결정영역에서도 아무런 피크가 보이지 않아 제시된 조건이 최적화 조건임을 알 수 있었
        340.
        2016.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        We consider a satellite mission scheduling problem, which is a promising problem in recent satellite industry. This problem has various considerations such as customer importance, due date, limited capacity of energy and memory, distance of the location of each mission, etc. Also we consider the objective of each satellite such as general purpose satellite, strategic mission and commercial satellite. And this problem can be modelled as a general knapsack problem, which is famous NP-hard problem, if the objective is defined as to maximize the total mission score performed. To solve this kind of problem, heuristic algorithm such as taboo and genetic algorithm are applied and their performance are acceptable in some extent. To propose more efficient algorithm than previous research, we applied a particle swarm optimization algorithm, which is the most promising method in optimization problem recently in this research. Owing to limitation of current study in obtaining real information and several assumptions, we generated 200 satellite missions with required information for each mission. Based on generated information, we compared the results by our approach algorithm with those of CPLEX. This comparison shows that our proposed approach give us almost accurate results as just less than 3% error rate, and computation time is just a little to be applied to real problem. Also this algorithm has enough scalability by innate characteristic of PSO. We also applied it to mission scheduling problem of various class of satellite. The results are quite reasonable enough to conclude that our proposed algorithm may work in satellite mission scheduling problem.
        4,000원