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        검색결과 259

        81.
        2017.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The study for reducing friction in elevation motion of a large television stand using over 50 inches is performed in this paper. The first study attempted to reduce the frictional force the gas seal lip technology. The second study is for optimized piston structure development by comparison pipe orifice and labyrinth orifice. As the result of the first study, in the gas seal lip technology, the outer-inner diameter of Ø20 × Ø8 in the test result of hollow rod is revealed more proper if the weight of 50 inch television assumed as 30. As the result of the second study, the optimized piston structure development through experiment is fixed orifice specification as labyrinth orifice because pipe orifice is founded slip up/down phenomenon of the Ø0.4~1.0 orifice and the labyrinth orifice is not founded that of the Ø0.4~0.6 orifice both tests on 300 mm intervals.
        4,000원
        82.
        2016.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        An injection unit is the important part which guide the melted resine into the mold. Once injection molding is performed, there will be a pressure of 33 MPa built up inside of injection cylinder body. It was confirmed that the crack occurs by internal stress on the 9 mm material when the machine is used for long time. Because the cylinder rod has material thickness of 9~12 mm during manufacturing process on the cylinder body, there would be 3 mm thickness differences. In this experiment, IDEAS, a computer aided structure analysis software, is used to present the optimized design condition. Insert rod with inner diameter of 9 mm was set as a normal and vary 3 mm in x, y axis direction. When the internal pressure of 33 MPa occurs at the injection unit, fix the x and y direction and find out the stress acting only in z axis. It was confirmed that the stress of 45~82 N/mm 2 was built up when the left of cylinder body had been set 9 mm by using a structure analysis. Also, it has been verified the thickness of the material on the left need to be greater and equal than 12 mm to prevent a material crack by an internal stress.
        4,000원
        83.
        2016.12 구독 인증기관 무료, 개인회원 유료
        본 연구에서는 대기 중 용액공정으로 유기발광다이오드(OLED)를 구현하였으며, 발광재료로서 고분자와 저분자 가 혼합된 하이브리드 host 물질과 저분자 dopant를 사용하였고, 고분자 소재의 홀이동층과 저분자 소재의 전자이동층 을 사용하였다. 모든 유기층들을 대기 중에서 용액공정으로 스핀코팅 되었으며, 용액공정 기반 OLED의 효율 향상을 위 해서 발광층의 두께 및 열처리 공정의 최적화 조건에 대해서 살펴보았다.
        4,000원
        84.
        2016.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        목 적 : 최근 관상동맥 경화반(coronary plaque)을 진단하기 위해 X-ray를 이용한 관상동맥 조영술(coronary angiography), fractional flow wire를 통한 관상동맥 혈류측정 (fractional flow reserve, FFR),혈관내초음파(intravascular ultrasound. IVUS), 심혈관 광간섭 단층촬영(optical coherence tomography, OCT) 등 여러 가지 기법들이 사용되고 있다. 이 중 관상동맥 경화반(coronary plaque) 을 평가할 수 있는 PC-VENC를 이용한 MR- FFR(fractional flow reserve)이 개발되어 기존의 비침습적 영상기법인 관상동맥 CT와 OCT, FFR등 침습적 영상기법과 비교하여 연구가 진행되고 있다. 이에 본 연구는 관상동맥 경화반(coronary plaque)을 평가하는 MR-FFR 검사에서 사용되는 2D PC-VENC 기법의 최적화 요인에 대하여 알아보고자 한다. 대상 및 방법 : 2015년 8월부터 2016년 1월까지 관상동맥의 근위부에 의미 있는 동맥경화반이 관찰되어 침습적 관상동맥 조영술과 OCT 또는 FFR측정이 예정된 환자 30명을 대상으로 MR-FFR 검사를 진행하였다. 3.0T MR(Trio, Siemens Healthcare, Erlangen, Germany) 장비를 사용하였다. 코일은 phased-array body coil을 사용하였고 parameter는 fat saturation을 사용하고 in-plane resolution은 0.5-0.6 × 0.5-0.6 mm², slice thickness 는 3.2 mm, VENC 범위는 동맥 경화반 상태에 따라 40-80 cm/s(3방향 z, x, y), cardiac phases는 2 (segments/phase), scan time은 slice당 4-8min/slice으로 설정하였다. 결 과 : Stenosis 정도 40%이하는 4명(13%), 40~70% 에서는 25명(77%), 70%이상은 3명(10%)으로 검사하였다. 40%이하에서의 VENC측정값은 normal 구간에서 40cm/sec, plaque 구간에서는 41±2.5cm/sec로 나타났고, 40~70%에서의 VENC측정값은 normal에서 40cm/sec, plaque구간에서는 46±4.6cm/sec로 70%이상에서의 VENC 측정값은 normal, plaque구간 모두 45cm/sec로 나타났다. VENC측정값 별 평균 검사시간은 35~40cm/sec에서 91.2분, VENC 40~45cm/sec에서 98.4분, VENC 45~50cm/sec에서 98.4분, VENC 50cm/sec 이상에서 107분이 소요되었다. 결 론 : 관상동맥 경화반 진단을 위한 2D PC-VENC 기법 사용 시, 본 연구에서 측정된 stenosis 정도에 따라 적정 VENC측정값을 사용하여 장시간의 검사시간 낭비를 최소화 할 수 있다. 또한 미리 알고 있는 stenosis정보를 통해 guide가 될 수 있는 VENC값을 사용함으로써 검사시간의 효율화를 구현할 수 있다.
        4,000원
        85.
        2016.11 구독 인증기관·개인회원 무료
        국내 양송이 재배에서 가장 많이 사용되는 재료는 볏짚으로서, 볏짚은 재배현장에서 가장 손쉽게 구할 수 있 는 재료이다. 볏짚은 단독 또는 다른 원재료를 혼합하여 사용하는데 본 연구에서는 다수의 재배농가에서 선 호하는 솜을 배합하여 볏짚대비 솜의 첨가비율의 최적화를 위한 재배시험을 실시하였다. 솜은 볏짚에 비하여 질소원인 단백질이풍부하고 야적 시 퇴비화 기간을 단축하는 효과를 가지고 있어서 계절에 따라서 적합한 비율을 혼합하면 수확량의 증가시킬 수 있는데 본 실험결과 볏짚 100%로 시료군보다 솜을 첨가 시 첨가량에 따라 생산량 및 상품 비율의 차이가 있는 것으로 확인하였다. 가장 우수한 시료군으로는 솜을 20% 첨가 시 에 생산량이 19% 증가하고 상품의 비율도 6% 증가하여 경제성이 높아지는 결과를 얻었으며, 볏짚을 주재료 로 사용 시 솜의 적정 혼합량은 20% 수준으로 기대한다.
        87.
        2016.09 구독 인증기관 무료, 개인회원 유료
        본 연구에서는, F4-ZnPc 광활성층 기반의 저분자 유기태양전지의 성능을 최적화 하기 위해서 다 양한 조건의 홀이동층과 전자이동층을 조합하는 연구를 진행하였다. BF-DPB 호스트 유기물에 C60F36 또 는 NDP9 도펀트를 도핑한 조합을 홀이동층으로 사용하였고, 전자이동층으로는 W2(hpp)4가 도핑된 C60 또는 순수 C60/Bphen 물질을 사용하였다. 다양한 홀/전자이동층의 조합은 유기태양전지의 단락전류밀도와 fill factor, 효율에 영향을 끼치는 것을 관찰할 수 있었다.
        4,000원
        88.
        2016.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구에서는 건축폐기물로 분류되는 레미콘회수수를 재활용함과 동시에 지구온난화의 주범 인 CO2의 자원화를 위한 시스템의 공정최적화를 진행하였다. 레미콘회수수를 이용한 액상탄산화 반응에 서 가장 중요한 공정은 Ca2+를 용출하는 공정이다. 일정량의 레미콘회수수를 이용해 고순도의 CaCO3을 생성하기 위해 Ca2+ 용출시 질산에 의해 낮아지는 pH 농도를 기준으로 실험을 진행하였으며, CO2는 발전기 배기가스를 이용해 MEA용액에 포집하였다. 본 연구를 통해 1톤의 레미콘회수수에서 최대 11 kg의 CaCO3를 합성할 수 있었다. 생성된 CaCO3 분석결과 제지용으로 사용 가능한 것을 확인하였다.
        4,000원
        89.
        2016.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study Muffins adding each 0, 1, 3, 5 7% of Acai Berry powder, which has very high anti-oxidant constituent, have been made, and its quality characteristics have been surveyed. From the volume and specific volume measurement, it has been decreased for MA1, 1% of Acai Berry powder added muffin, but the tendency thereafter has shown increasing (p<0.001). From texture characteristics gumminess and chewiness of MA0, reference group, was the highest by 885.86 g/ cm and 6645.71 g, and has shown decreasing tendency as per the adding rate of Acai Berry powder increased (0.001). The electronics scavenging activity of MA7, 7% added muffin, was the highest by 68.91%, and the ascending order was MA1 < Reference Group < MA3 < MA5 < MA7. From the preference test of Acai Berry powder added muffin, MA3, 3% added muffin, was the most preferable one from color, taste as well as total preference. As the added volume of Acai Berry powder is 5% or more, the typical taste and flavor of Acai Berry gives influence to the taste and flavor of muffin, so the preference level has been decreased. Thus the added volume of Acai Berry powder 5% or more is not recommendable.
        4,000원
        90.
        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
        92.
        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.
        93.
        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
        95.
        2015.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        PURPOSES : The purpose of this study is to present a linear programing optimization model for the design of lane-based lane-uses and signal timings for an isolated intersection. METHODS: For the optimization model, a set of constraints for lane-uses and signal settings are identified to ensure feasibility and safety of traffic flow. Three types of objective functions are introduced for optimizing lane-uses and signal operation, including 1) flow ratio minimization of a dual-ring signal control system, 2) cycle length minimization, and 3) capacity maximization. RESULTS : The three types of model were evaluated in terms of minimizing delay time. From the experimental results, the flow ratio minimization model proved to be more effective in reducing delay time than cycle length minimization and capacity maximization models and provided reasonable cycle lengths located between those of other two models. CONCLUSIONS : It was concluded that the flow ratio minimization objective function is the proper one to implement for lane-uses and signal settings optimization to reduce delay time for signalized intersections.
        4,200원
        96.
        2015.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Recently, the Ministry of Labour, published clause 2 of Article 41 (Risk Assessment) of the Act "Industrial Safety and Health" dated 12 June 2013 in connection with continuous increase of accidents at construction sites in order to prevent accidents in industrial safety and health in new construction in accordance with the risk assessment on construction projects are realized after March 13, 2014. In this paper, positive method of calculating risk discussed by performing research the awareness of general contractors and sub-contractors with presenting risky situation is considered. The purpose will be a positive method of calculating risk and would be a sufficient basе and give a positive direction in the development of new systems currently working in the construction and risk assessment which consider the characteristics of sufficient risk assessment system for future research.
        4,000원
        97.
        2015.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The risk assessment carried out on the construction site at the beginning of the implementation depends on the subjective judgment of risk of general contractor and subcontractors, whose opinion about frequency and intensity of risk is different. In this paper, research the awareness of general contractors and subcontractors about process of risk assessment at the construction site and its effectiveness. Researching of the main factors "frequency", "intensity" which determines the degree of risk gives the opportunity to find an option for improving the effective implementation of risk assessment.
        4,000원
        98.
        2015.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This research carried out an analysis on input cost and leakage reduction effect by leakage reduction method, focusing on the project for establishing an optimal water pipe network management system in the Taebaek region, which has been executed annually since 2009. Based on the result, optimal cost-benefit analysis models for water distribution network rehabilitation project were developed using DEA(data envelopment analysis) and multiple regression analysis, which have been widely utilized for efficiency analysis in public and other projects. DEA and multiple regression analysis were carried out by applying 4 analytical methods involving different ratios and costs. The result showed that the models involving the analytical methods 2 and 4 were of low significance (which therefore were excluded), and only the models involving the analytical methods 1 and 3 were suitable. From the result it was judged that the leakage management method to be executed with the highest priority for the improvement of revenue water ratio was installation of pressure reduction valve, followed by replacement of water distribution pipe, replacement of water supply pipe, and then leakage detection and repair; and that the execution of leakage management methods in this order would be most economical. In addition, replacement of water meter was also shown to be necessary in case there were a large number of defective water meters.
        4,300원
        100.
        2015.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study was performed to determine the total anthocyanin contents, DPPH radical scavenging activity, and SODlike activity of extracted anthocyanins from Bokbunja for analyzing the optimal conditions of enzyme treatment by response surface methodology (RSM) based on three factors: concentration of Pectinex Ultra SP-L, reaction temperature, and reaction time. The optimal enzyme treatment conditions of Pectinex Ultra SP-L concentration, reaction temperature, reaction time, and overall desirability by analysis of multiple response surface methodology with the same weighed value of each dependent variable were 0.5 mL/100 L, 20oC, 2 hr, and 0.63, respectively. Total anthocyanin content, DPPH radical scavenging activity, and SOD-like activity of the conditions stated above were 5.2 mg/ 100 g, 61.3% and 30.5%, respectively. Meanwhile, those of the control were 1.1 mg/100 g, 11.8% and 1.1%, respectively.method.
        4,000원
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