비선형 유한요소해석 결과를 이용하여 철근콘크리트 부재를 설계를 하고자 할 경우 위험단면에서의 휨모멘트를 산정하여 야 한다. 본 논문에서는 연속체 요소를 사용한 철근콘크리트 유한요소해석 결과를 이용한 휨 모멘트 계산식을 제시하고 유한요소의 변위 함수의 차수에 따른 최적의 요소 크기를 제안하였다. 해석으로부터 산출된 응력을 적분하여 구한 휨 모멘트 와 정역학적 평형 조건을 이용하여 계산한 휨 모멘트를 비교하였다. 응력을 적분하는 방법에서는 철근에 의한 응력과 콘크 리트의 응력을 모두 고려하였다. 또한 유한요소해석으로 산출된 응력의 정확도에 영향을 주는 여러 요인들을 분석하고 적용 요소의 변위 함수와 요소 크기를 다르게 설정하여 그 영향을 확인하였다. 해석의 목적이 부재의 거동을 대략적으로 살펴보 는 목적이라면 1차 변위 함수를 사용하고 요소 크기가 해석 모델의 단면 높이의 25%정도라도 적절하다고 판단된다. 정확도가 높은 부재의 내력을 도출해야 할 경우에는 2차 변위 함수를 사용하고 요소 크기를 12.5%로 할 것을 제안한다.

Recently, interest in the development of alternative water resources has been increasing rapidly due to environmental pollution and depletion of water resources. In particular, seawater desalination has been attracting the most attention as alternative water resources. As seawater desalination consumes a large amount of energy due to high operating pressure, many researches have been conducted to improve energy efficiency such as energy recovery device (ERD). Consequently, this study aims to compare the energy efficiency of RO process according to ERD of isobaric type which is applied in scientific control pilot plant process of each 100 m3/day scale based on actual RO product water. As a result, it was confirmed that efficiency, mixing rate, and permeate conductivity were different depending on the size of the apparatus even though the same principle of the ERD was applied. It is believed that this is caused by the difference in cross-sectional area of the contacted portion for pressure transfer inside the ERD. Therefore, further study is needed to confirm the optimum conditions what is applicable to the actual process considering the correlation with other factors as well as the factors obtained from the previous experiments.

The purpose of this study was that the optimal hydrolysis conditions of endo- and exo-type enzymes were selected to utilize organic cheese byproducts. Optimal substrate concentration and optimum enzyme ratio were measured by using 4 kinds of endo-type enzymes (alcalase, neutrase, protamex, and foodpro alkaline protease) and two exo-type enzymes (flavourzyme and prozyme 2000P) for whey protein hydrolysis were analyzed using liquid chromatography. As a result, the optimal endo-type enzyme through the first enzyme reaction was selected as alcalse, and as a result of the secondary enzyme reaction, flavourzme was selected as the Exo type enzyme. The concentration of whey protein substrate for optimal primary and secondary enzyme reactions was 10%. In addition, the optimum ratio of enzyme was 0.5% of alcalase and 0.2% of flavourzyme, which showed low molecular weight chromatography pattern compared to 2% of alcalase and 1% of flavourzyme hydrolyzate. Therefore, hydrolyzing the endo-type enzyme alcalase at a concentration of 0.5% for 10 hours and then hydrolyzing the exo-type enzyme flavouryme at a concentration of 0.2% for 4 hours was considered to be the optimum condition.

함정 외부 탑재 장비의 복잡한 형상에 의해서 발생하는 다중반사는 경로를 예측하기 어렵고 높은 RCS(Radar Cross Section) 의 원인이 된다. 따라서 함정의 외부 탑재 장비의 최적배치 설계가 RAS(Radar Absorbing Structure) 방법으로 고려되어야 한다. 본 논문에 서는 함정 외부 탑재 장비에서 발생하는 다중반사와 RCS를 최소화하기 위하여 함정 외부 탑재 장비 최적배치를 수행하였다. 외부 탑 재 장비 최적배치에 사용된 알고리즘은 순차적 내림차순 방법을 이용하였다. 함정 외부 탑재 장비 최적배치를 수행하기 위하여 LCS-2 type을 해석 모델로 선정하였다. 계산 비용을 줄이기 위해서 장비의 기여도 분석 및 다중반사 경로 분석 등을 통해 최적 배치를 수행 할 장비를 선정하였고 최적배치를 통해 RCS가 최소가 되는 최적배치 위치를 도출하였다. 또한 RCS 변화에 따른 레이다의 탐지거리 변 화율을 이용하여 RCS 감소효과를 분석 하였다.

신·재생에너지 보급통계에 의하면 바이오매스 발전실적은 2013년 부터 급증하고 있으며 그 중에서 가장 급격하게 증가한 연료는 Wood pellet으로 2013년 696Gwh, 2014년 2,764Gwh, 2015년에는 2,512Gwh를 발전 하였고 국내 Wood pellet 총 소비량은 2015년 기준 148만톤이며 그 중 발전용으로 소비된 Wood pellet은 108만톤으로 약 73%를 차지하고 있다. 본 연구에서 Wood pellet 소요량을 예측한 결과 국내 발전용으로 필요한 Wood pellet 소요량은 2020년 261만톤, 2025년 685만톤, 2030년 1,139만톤이 필요하며, 최적 바이오매스 발전량 산정을 위하여 바이오매스 발전소에서 국내 생산 Wood pellet 사용량을 50% 사용한다는 가정하에 기허가 신청된 발전소를 가동하기 위해서는 2021년 226만 톤의 Wood pellet이 국내에서 생산되어야 한다는 결론이 도출되었다.

현 경비 함정의 위치는 해양사고 위치와의 접근성이 떨어져 있어 합리적이고 과학적인 기준이 아닌 주관적인 판단으로 배치되 어 있다. 이에 본 연구에서는 과거 해양사고 데이터를 기반으로 정량적으로 최적의 경비 함정 배치 위치를 도출하고자 한다. 연구 해역은 포항 연안을 대상으로 하였다. 본 연구에서는 k-평균 군집화 알고리즘으로 경비 함정의 배치 위치를 도출한 후, 보로노이 다이어그램으로 각 경비 함정 간 경비 구역을 구획하였다. 연구 결과, 해양사고 1건당 경비 함정의 평균 항해 거리는 4.4해리, 평균 도착 시간은 13.2분이 개선될 수 있었다. 경비 함정을 유동적으로 배치 수를 달리해야 할 경우 본 연구에서 적용한 기법을 활용하여 최적 배치가 가능하며, 신 속한 구조 지원 체계가 더욱 확보될 것으로 판단된다.

Desalination plants have been recently constructed in many parts of the world due to water scarcity caused by population growth, industrialization and climate change. Most seawater desalination plants are designed with a submarine pipeline for intake and discharge. Submarine pipelines are installed directly on the bottom of the water body if the bottom is sandy and flat. Intake is located on a low-energy shoreline with minimal exposure to beach erosion, heavy storms, typhoons, tsunamis, or strong underwater currents. Typically, HDPE (High Density Polyethylene) pipes are used in such a configuration. Submarine pipelines cause many problems when they are not properly designed; HDPE pipelines can be floated or exposed to strong currents and wind or tidal action. This study examines the optimal design method for the trench depth of pipeline, analysis of on-bottom stability and dilution of the concentrate based on the desalination plant conducted at the Pacific coast of Peru, Chilca. As a result of this study, the submarine pipeline should be trenched at least below 1.8 m. The same direction of pipeline with the main wind is a key factor to achieve economic stability. The concentrate should be discharged as much as high position to yield high dilution rate.

This study aimed to develop a method to optimize residual chlorine concentrations in the process of providing water supply. To this end, this study developed a model capable of optimizing the chlorine input into the clearwell in the purification plant and the optimal installation location of rechlorination facilities, and chlorine input. This study applied genetic algorithms finding the optimal point with appropriate residual chlorine concentrations and deriving a cost-optimal solution. The developed model was applied to SN purification plant supply area. As a result, it was possible to meet the target residual chlorine concentration with the minimum cost. Also, the optimal operation method in target area according to the water temperature and volume of supply was suggested. On the basis of the results, this study derived the most economical operational method of coping with water pollution in the process of providing water supply and satisfying the service level required by consumers in the aspects of cost effectiveness. It is considered possible to appropriately respond to increasing service level required by consumers in the future and to use the study results to establish an operational management plan in a short-term perspective.

관주처리에 의한 벼멸구 흡즙 섭식 독성, 잎 침지처리에 의한 접촉독성과 식물체내 침투에 의한 섭식독성, 미량국소처리에 의한 표피 접촉 독성 등, 처리 방법에 따른 카보퓨란의 벼멸구에 대한 살충 작용 특성을 분석하였다. 카보퓨란 관주처리는 시간에 따른 벼멸구의 살충력 변화가 2 가지 패턴으로 나타났다. 상대적으로 높은 농도(8~30 ppm)의 처리에서는 급격히 사충율이 올라가다가 시간이 지남에 따라 증가율이 낮아지는 로그곡선의 형태와 낮은 농도(1~4 ppm)의 처리에서는 사충율 증가 패턴이 S 자 모양의 곡선 형태를 보였다. 관주처리 시 높은 농도에서는 처리 효과가 즉시 나타나 하루 만에 치사율이 40% 이상 도달하였으나 상대적으로 낮은 1~2 ppm의 농도에서는 처리 5일 후에야 80~100%에 달하는 사충율을 얻을 수 있었다. 침지처리는 사충율이 처리 1일 후 약효가 급격히 증가하고 이 후 증가율이 낮아졌다. 국소처리도 침지처리와 비슷한 경 향을 보이나 침지처리와는 달리 처리 후 3일 이후에는 사충율이 거의 증가하지 않았다. 약효 최적 조사 시간은 관주처리에서 처리 후 2일 (42시 간)이었으며 침지처리와 국소처리에서는 처리 후 1~2일이 약효 조사 적기였다.

Solar energy has been known as a successful alternative energy source, however it requires a large area to build power generation facilities compared to other energy sources such as nuclear power. Weather factors such as rainy weather or night time impact on solar power generation because of lack of insolation and sunshine. In addition, solar power generation is vulnerable to external elements such as changes in temperature and fine dust. There are four seasons in the Republic of Korea hereby variations of temperature, insolation and sunshine are broad. Currently factors that cause find dust are continuously flowing in to Korea from abroad. In order to build a solar power plant, a large area is required for a limited domestic land hereby selecting the optimal location for the plant that maximizes the efficiency of power generation is necessary. Therefore, this research analyze the optimal site for solar power generation plant by implementing analytic hierarchy process based on weather factors such as fine dust. In order to extract weather factors that impact on solar power generation, this work conducts a case study which includes a correlation analysis between weather information and power generation.

A smart tuned mass damper (TMD) was developed to provide better control performance than a passive TMD for reduction of earthquake induced-responses. Because a passive TMD was developed decades ago, optimal design methods for structural parameters of a TMD, such as damping constant and stiffness, have been developed already. However, studies of optimal design method for structural parameters of a smart TMD were little performed to date. Therefore, parameter studies of structural properties of a smart TMD were conducted in this paper to develop optimal design method of a smart TMD under seismic excitation. A retractable-roof spatial structure was used as an example structure. Because dynamic characteristics of a retractable-roof spatial structure is changed based on opened or closed roof condition, control performance of smart TMD under off-tuning was investigated. Because mass ratio of TMD and smart TMD mainly affect control performance, variation of control performance due to mass ratio was investigated. Parameter studies of structural properties of a smart TMD was performed to find optimal damping constant and stiffness and it was compared with the results of optimal passive TMD design method. The design process developed in this study is expected to be used for preliminary design of a smart TMD for a retractable-roof spatial structure.

PURPOSES : The objective of this research is establishing system components and optimizing operational procedures in order to systematically manage road cave-ins in urban areas.METHODS: Based on the literature review and alternative comparison, optimization methods is suggested.RESULTS : Throughout the study, location referencing system, database structure, and operation strategy(procedure) were clarified, and the optimization methods for each item were suggested.CONCLUSIONS: Road cave-in management should be focused on user safety rather than focusing on economic aspects. The occurrence of road cave-in should be addressed thoroughly by road management system(location referencing system, database structure, and operation strategy(procedure), and the optimization methods), since they are closely related to road users' safety.

사회적으로 안전에 대한 관심이 많아지고 있는 상황에서 계속되는 북한의 미사일 실험은 이를 대비한 민방위 대피시설의 운영 실태를 점검하는 계기가 되었다. 본 연구에서는 공간 최적화 접근을 통하여 개별 대피시설 수준에서 서비스 커버리지와 수용 능력을 평가하였다. 특히 수요를 상주인구로 재현하였을 때와 현주인구로 재현하였을 때 모델링 결과가 어떻게 달라지는지 분석하였다. 사례지역으로 대구광역시 서구의 민방위 대피시설의 커버리지를 평가하였다. 그 결과, 지정된 민방위 대피시설에 의해서 커버되지 않은 현주인구가 상주인구에 비하여 절대적으로 뿐만 아니라 상대적으로 많았다. 또한 기존 대피시설에 의해서 커버되지 않는 상주인구와 현주인구의 위치가 달랐다. 마지막으로 개별 대피시설에 할당된 인구를 수용가능 인구와 비교해 본 결과 대체로 시설의 규모가 클수록 실제 수용률이 낮게 나타났다. 이러한 공간 최적화 접근을 통하여 도출한 정보는 재난관리를 보다 구체적이고 체계적으로 만드는데 기여할 것이다.

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.