A one-shot system (device) refers to a system that is stored for a long period of time and is then disposed of after a single mission because it is accompanied by a chemical reaction or physical destruction when it operates, such as shells, munitions in a defense weapon system and automobile airbags. Because these systems are primarily related with safety and life, it is required to maintain a high level of storage reliability. Storage reliability is the probability that the system will operate at a particular point in time after storage. Since the stored one-shot system can be confirmed only through inspection, periodic inspection and maintenance should be performed to maintain a high level of storage reliability. Since the one-shot system is characterized by a large loss in the event of a failure, it is necessary to determine an appropriate inspection period to maintain the storage reliability above the reliability goal. In this study, we propose an optimal inspection policy that minimizes the total cost while exceeding the reliability goal that the storage reliability is set in advance for the one-shot system in which periodic inspections are performed. We assume that the failure time is the Weibull distribution. And the cost model is presented considering the existing storage reliability model by Martinez and Kim et al. The cost components to be included in the cost model are the cost of inspection c1, the cost of loss per unit time between failure and detection c2, the cost of minimum repair of the detected breakdown of units c3, and the overhaul cost c4 of  ≤ . And in this paper, we will determine the optimal inspection policy to find the inspection period and number of tests that minimize the expected cost per unit time from the finite lifetime to the overhaul. Compare them through numerical examples.

Abstract It has come to attention that a risk-assessing organization, that will benchmark a company’s safety department, is imperative, following an increase in large-scale SOC-business project, construction of higher-raised buildings, development of underground space; all that have increase accident rates. Having faced problems that arise in firms that demand diversity, complexity and instantaneity, the purpose of the thesis is to arrive at efficient and practical problem-solving means. In order to solve the problems that would surface theoretically during an actual risk assessment, the state of the operation systems of the top five national construction firms having a hazard rate of 0.25 times less than the average rate have been analyzed, while a hierarchal recognition research of the employees who not only function at the operating level but are the practice subjects of a firm, has also been conducted, bringing the main text.

This study is to conduct the optimal design of the fluid mixing blades in the test fluid tank for sewage treatment process. The design was made with various shapes and angles of mixing blades. Fluid mixing blades in the tank are numerically analyzed with FLUENT V.13.0. Blade1 and Blade4 had the biggest fluid pressure difference of 8.1% around the blades. And, Blade1 and Blade3 had the least fluid pressure difference of 2.55%. The biggest turbulence kinetic energy of 12.5% existed around Blade1 and Blade4. Blade1 and Blade3 had the least turbulent kinetic energy difference of 4.8%. Blade4 is the optimal design shape due to the highest turbulent kinetic energy around the blades in comparison to the other cases.

Acetic acid bacteria strains were isolated from a variety of fermented foods and fallen fruits. Among them, the strain MAK88, whose acetic acid fermentation ability, acid-tolerance, and alcohol-tolerance were high, was selected and identified as Acetobacter orientalis. A seed culture of A. orientalis MAK88 was inoculated into onion juice, and the optimum conditions of acetic acid fermentation was investigated. The optimum initial concentration of ethanol in onion juice was 5% (v/v) and in that condition, acidity was 4.31% at 144 h of fermentation. The optimum initial concentration of acetic acid was 1% and the final acidity was 5.32%. The optimum fermentation temperature was determined to be 28oC. The most appropriate preparation method of onion juice was to heat the onion at 121oC for 15 min and produce juice with pressure followed by filtering, and then sterilization at 121oC for 15 min. Prepared onion juice was used for fermentation without dilution.

Glucansucrase is an enzyme classified as a glycoside hydrolase (GH) 70 family, which catalyzes the synthesis of glucooligosaccharides with a low molecular weight using sucrose as a donor of D-glucopyranose and maltose as a carbohydrate acceptor. In this study, glucansucrase-producing lactic acid bacteria strain was isolated from the fermented foods collected in traditional markets, and the optimum conditions for the oligosaccharide production were investigated. The strain CCK940 isolated from Chinese cabbage kimchi was selected as an oligosaccharide-producing strain due to its high glucansucrase activity, with 918.2 mU/mL, and identified as Leuconostoc lactis. The optimum conditions for the production of oligosaccharides using Leu. lactis CCK940 were to adjust the initial pH to 6.0, add 5% (w/v) sucrose and 10% (w/v) maltose as a donor and acceptor molecules, respectively, and feed 5% (w/v) sucrose at 4 and 8 h of cultivation. When Leu. lactis CCK940 was cultured for 12 h at optimum conditions, at least four oligosaccharides with a polymerization degree of 2-4 were produced.

Fish skin peptide-loaded liposomes were prepared in 100 mL and 1 L solution as lab scales, and 10 L solution as a prototype scale. The particle size and zeta potential were measured to determine the optimal conditions for the production of fish skin peptide-loaded liposome. The liposome was manufactured by the following conditions: (1) primary homogenization at 4,000 rpm, 8,000 rpm, and 12,000 rpm for 3 minutes; (2) secondary homogenization at 40 watt (W), 60 W, and 80 W for 3 minutes. From this experimental design, the optimal conditions of homogenization were selected as 4,000 rpm and 60 W. For the next step, fish peptides were prepared as the concentrations of 3, 6, and 12% at the optimum manufacturing conditions of liposome and stored at 4ºC. Particle size, polydispersion index (pdI), and zeta potential of peptide-loaded liposome were measured for its stability. Particle size increased significantly as manufacture scale and peptide concentration increased, and decreased over storage time. The zeta potential results increased as storage time increased at 10 L scale. In addition, 12% peptide showed the formation of a sediment layer after 3 weeks, and 6% peptide was considered to be the most suitable for industrial application.

즉석조리 죽 제품들은 선호화(pre-gelatinized) 쌀가루와 기타 부재료(곡류, 채소 및 약용식물 등) 가루들을 단순 혼합한 형태로 제공되고 있지만, 물을 가하였을 때 선호화 쌀가루가 응집되어 조리가 불편한 단점이 있다. 본 연구는 쌀가루의 응집현상을 최소화할 수 있는 쌀가루를 활용하고, 식이섬유를 강화할 수 있는 비지분말을 활용한 즉석조리 비지죽 프리믹스를 개발하기 위해 비지분말, 멥쌀가루 및 찹쌀가루의 최적혼합비율을 조사하고자 하였다. 멥쌀 및 찹쌀 가루들은 멥쌀과 찹쌀을 습식제분, 건조, 분쇄, 선별(100 mesh)을 통해 제조하였다. 비지분말은 두부제조공정에서 배출된 생비지를 120°C에서 3시간 동안 습열처리한 후 건조, 분쇄, 선별(100 mesh)을 통해 제조하였다. 즉석조리 비지죽 프리믹스의 혼합비율은 비지분말, 멥쌀가루 및 찹쌀가루의 제한범위를 각각 10-40%, 10-30% 및 50-70%로 하여 modified distance mixture design에 의해 16개의 혼합비율들을 설계하였다. 혼합물설계법의 반응표면분석을 위한 반응들은 비지분말-멥쌀가루-찹쌀가루 혼합물을 물과 혼합하여 5%(w/w) 고형분 함량의 분산물을 제조하여 페이스팅 점도 특성치들과 마이크로웨이브 가열(1,000 W, 80 s)을 통해 제조된 비지분말-멥쌀가루-찹쌀가루 혼합물 페이스트의 겉보기 점도 특성치들을 이용하였다. 가루소재 혼합물들의 페이스팅 점도 특성치들에 대해서 반응표면분석을 수행하였을 때, 최고점도, 최저점도, 붕괴점도, 최종점도 및 치반점도들은 1차항 요인들에 대해서만 유의적인 차이를 나타내었으나, 최고 및 최저 점도들은 멥쌀가루의 함량에 영향을 받지 않았다. 또한 혼합물 내에서 비지분말 및 찹쌀가루 함량의 증가는 가루소재 혼합물의 페이스팅 점도 특성치들을 각각 유의적으로 감소시키거나 증가시켰다. 마이크로웨이브 가열에 의한 가루소재 혼합물 페이스트들의 겉보기 점도 특성치들에 대해서 η-00 (마이크로웨이브 가열 즉시 50°C에서 측정된 점도)와 η-A20 (혼합물 페이스트를 20분간 상온에서 방치한 후 50°C에서 측정된 점도)의 선형(linear) 모델에 적합하였으며, Δη (20분간 방치 전후의 혼합물 페이스트의 50°C에서 측정된 점도 차이), η-00-RH (마이크로웨이브 가열 후 재가열하고 50°C로 냉각된 혼합물 페이스트의 점도)와 Δη-RH (재가열된 후 50°C로 냉각된 혼합물 페이스트의 점도 차이)는 3차항(cubic) 모델에 적합하였고, η-A20-RH (혼합물 페이스트를 20분간 상온에서 방치한 후 재가열하고 50°C로 냉각된 혼합물 페이스의 점도)은 2차항(quadratic) 모델에 적합한 것으로 분석되었다. 반응표면분석된 결과에 기초하여 수치해석법을 이용하여 최적혼합비율을 결정하였을 때, 즉석조리 비지죽 프리믹스는 36% 비지분말, 11% 멥쌀가루, 53% 찹쌀가루로 구성되었고, 비지분말을 30%로 고정할 경우 멥쌀가루는 16%, 찹쌀가루는 54% 이었다.

Ceramic membranes can be applied under extreme operating conditions such as low pH, high pressure and high temperature. In particular SiC has excellent mechanical properties and also has excellent properties related to membrane performance. However, high processing temperature increases cost of SiC products and thus limit’s its use. In this study oxidation bonding technique was used to fabricate cost-effective SiC microfiltration membrane at low temperature. The oxidation behavior at different thermal treatments was related with pore morphology and ultimately the membrane permeability. We have found that the membrane made by coating of oxidation bonded SiC layer over clay-bonded SiC support, sintered at 1000-1100°C could make a defect-free microfiltration membrane with pure water permeability above 700 LMH per bar. The membrane has narrow pore size distribution with average pore size about 0.1 μm.

The object of this paper is to examine the optimum sintering condition which have excellent mechanical properties compared to the conventional oilless bearing. It is shown that the sintering rate is the most excellent at 850°C, especially KAB-23, KAB-23G, PBF-8 specimens. With increasing the nitrogen injection rate, the apparent porosity increased gradually. In contrast, with increasing the hydrogen injection rate, the apparent porosity decreased gradually. It is shown that the apparent porosity is very useful in the range of nitrogen injection rate 2Nm 3 and hydrogen injection rate 10Nm 3 .

As the size of the wind turbine tower becomes larger and larger, research on assembled wind turbine tower that is advantageous for transportation and installation is continuing. Large wind turbine tower require door openings for maintenance. The opening of the tower has an irregular cross section, and an excessive stress is generated due to the door opening. The result is structural damage to the tower and many accidents. In this research, stress analysis was performed on a model with internal stiffener to prevent excessive stress. The stress was investigated around the openings where the tower was resonant and excessive stressed, and the shape of the openings was optimized. Through optimization, we confirmed that the maximum stress was reduced by about 6% with respect to the initial value.

The object of research is based on 1.5 MW wind turbine blade. This paper has carried out the aerodynamic shape optimization design of wind turbine blade. Based on the aerodynamic basic theory of wind turbine blade design and combined with particle swarm optimization algorithm(PSO), the design optimization model of the aerodynamic shape of blade is established. Through this study, the optimization results of the angle inducing ′ and tangential inducing  were obtained. The calculation programs are written and calculated chord length and torsion angle of the blade used by ′ and . The calculation result for the optimized wind turbine was 1.38 MW when the wind speed was 16 m/s. The 8 % error could be considered as an engineering acceptable error and the calculated values can be proved the correctness of the design value.

The navy that operates a large size of weapon systems, relatively a small quantity of, in order to minimize the loss of war potential caused by the breakdown of weapon system during long-term naval area of operation assigns allowance parts such as Maintenance Float (M/F), Combat Exchange Components, Concurrent Spare Parts (CSP) and so on to each unit and makes them use the allowance parts. Among them, Combat Exchange Components is being calculated in accordance with heuristic method because there is no standardized method to calculate it differently from Maintenance Float and Concurrent Spare Parts. In this article, more systematic calculation optimization method of it is suggested by selecting the optimum Combat Exchange Components in accordance with integer programming and presenting it, comparing it with the list of Combat Exchange Components calculated by actual heuristic method.

최근에 와서 해양연구활동은 국가적 영토관리개념을 넘어 전지구적인 연구영역으로 급속히 확장되고 있다. 이와 같은 연구 추세는 기후, 자원, 환경과 영토관리 등 해양을 대상으로 하는 연구스펙트럼이 급격하게 확대되고 있다는 것을 의미하며, 이에 따른 해 양연구인프라 또한 대형화되고 정밀화되는 것이 불가피하다. 그러나 한편으로는 이와같은 연구인프라는 운용과 관리 측면에서 소요되 는 비용부담이 크고 국가재정 의존도가 높기 때문에 효율성을 고려한 국가전략적 차원의 대응방안 마련이 필요하다. 본 연구에서는 국 내기관간 또는 국가간 해양연구의 기본인프라인 연구·조사선 공동활용체계를 구축하여 시행하고 있는 주요 선행국의 운용체계 형태와 특성을 분석하고 연구조사선을 보유하고 있는 국내 주요 기관을 중심으로 공동활용 운영체계 유형과 각 유형별 효율성을 비교·분석하 였다. 주요 선행국의 운영형태와 국내 여건을 고려하였을 때, 구현 가능한 국내 공동활용 운영체계는 공동활용위원회(유형 1), 민간기 업 위탁(유형 2), 정부출연기관내 기관출자(유형 3)과 위탁집행형(유형 4)로 요약될 수 있다. 현재의 운영체계와 4가지 유형의 운영체계 에 대한 비용-편익 분석 결과, 유형 1, 2, 3과 4의 효과성 비율은 각각 9.17, 5.82, 11.2와 -1.72%로 나타남에 따라 유형 1(공동활용위원회 운영체계)가 소요비용측면에서 가장 효율적인 대안인 것으로 나타났으며, 편익적 측면에서는 유형 3(정부출연기관내 기관출자)의 기관 출자 방식 운영체계가 가장 효과적인 것으로 해석되었다.