• 한국연소학회지
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• 제16권2호
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• pp.40-46
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• 2011

The diesel pre-heater has being used in cabin heating and coolant heating of engine to reduce the engine warm up time for commercial vehicle. The pre-heaters are classified as diesel spray combustor and it forms diffusion flame. By using swirler, a recirculation flow of hot product gases is established near the fuel nozzle and it helps the maintaining of diffusion flame. The design difference of swirler can affect on reaction characteristics and temperature distribution inside pre-heater. The purpose of this study is the investigation of the effect of swirler configuration on combustion characteristics. To solve spray combustion problem, the Euler-Lagrange approach discrete model is used to track droplet trajectory and evaporation history. The PDF equilibrium model is used for chemical reaction model. These models are implemented into the FLUENT code.

• 국제초고층학회논문집
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• 제7권4호
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• pp.389-396
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• 2018

This paper presents a numerical investigation on the structural response of a multi-story building subjected to spreading multi-compartment fires. A recently proposed simple fire model has been used to simulate two spreading multi-compartment fire scenarios in a 10-story steel-framed office building. By assuming simple temperature rising and distribution profiles in the fire exposed structural components (steel beams, steel column and concrete slabs), finite element simulations using a three-dimensional structural model has been carried out to study the failure behavior of the whole structure in two multi-compartment fire conditions and also in a standard fire condition. The structure survived the standard fire but failed in the multi-compartment fire. Whilst more accurate fire models and heat transfer models are needed to better predict the behaviors of structures in realistic fires, the current study based on very simple models has demonstrated the importance and necessity of considering spreadingmulti-compartment fires in fire resistance design of multi-story buildings.

• 한국산학기술학회논문지
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• 제17권1호
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• pp.244-251
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• 2016

본 연구에서는 폼 모니터의 유로 형상에 따라 유동 특성 및 분사거리에 비치는 영향을 수치적 해석기법인 유동해석을 통해 예측, 비교하고 실제 분사 성능 시험을 통해 검증하였다. 폼 모니터의 유로 형상에 따라 유체의 유동 양상이 달라지며, 유동손실이 발생함에 따라 분사거리에 영향을 미치는 것을 수치해석을 통해 계산하였다. 폼 모니터의 기본 형상은 N사에서 설계한 형상을 사용 하였고, 변경모델은 유로의 길이를 증가시킨 모델과 직선형태의 모델을 사용하였다. 입구압력은 6.5bar를 주었고, 계산 결과 유로의 길이를 증가시킨 모델과 직선형상 모델 모두 노즐에서의 분사거리가 향상되었다. 분사 성능시험결과와 비교한 결과 오차율은 7.43%로 비교적 잘 일치 하여 해석 기법의 타당성을 검증하였다.

• 한국식품저장유통학회지
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• 제3권1호
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• pp.39-53
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• 1996

Ginseng, one of the important economic crops, is processed into medicine, teas, beverages and even foods. Drying is the most important and burdensome work in the processing of ginseng, so development of ginseng dryer is needed for efficient drying and good quality of ginseng. Investigation of drying model is essential for development of ginseng dryer. Drying models for peeled ginseng were investigated to determine dominant drying factors and fitted with five selected drying models and an empirical model. Thompson and the empirical model showed best fit with the experimental data. Pother experiment is necessary to prove the superiority of the empirical models.

• 대한인간공학회지
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• 제35권3호
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• pp.143-153
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• 2016

Objective: The purposes of this study are to survey needs for changing accident investigation from blaming to systems approach and to briefly summarize systems-based accident analysis techniques. Background: In modern complex socio-technical systems, accidents are caused by a variety of contributing factors including human, technical, organizational, social factors, not by just a single violation or error of a specific actor, but accidents investigation used to be focused on the incorrect action of individuals. A new approach investigating causes of accidents as a symptom of a deficient system is required. Method: This study was mainly based on survey of literatures related to accidents, accidents investigation, which included academic journals, newspapers, etc. Results: This study showed that accidents investigation of Korea focusing on blaming is problematic. This was confirmed by two concepts of migration and hindsight bias frequently found in accident causation studies, and an attribute of accidents having varying causes. This was illustrated with an example of Sewol ferry capsizing accident. Representative systems-based accident analysis models including Swiss cheese model, AcciMap, HFACS, FRAM and STAMP were briefly introduced, which can be used in systematic accidents investigations. Finally, this study proposed a procedure for establishing preventive measures of accidents, which was composed of two steps: public inquiry and devising preventive measures. Conclusion: A new approach considering how safety-critical components such as technical and social elements, and their interactions lead to accidents is needed for preventing reoccurrence of similar accidents in complex socio-technical systems. Application: The results would be used as a reference or guideline when the safety relevant governmental organizations investigate accidents.

• 한국항공운항학회지
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• 제28권2호
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• pp.63-70
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• 2020

Many organizations apply reactive safety management to prevent the same or similar types of accidents by through investigation and analysis of the accident cases. Although research on investigation techniques has contributed a lot to the objective results of safety accidents and the preparation of countermeasures, many accident investigation techniques currently in use treat accidents from a linear perspective, revealing limitations in reflecting current systems dominated by complexity and uncertainty. In order to overcome these limitations, this study will review recent studies and concepts from a system safety perspective and predict future research trends through a case analysis of aviation accident. The models used in the analysis are STAMP, HFACS, and FRAM, and the characteristics of each technique are presented so that analysts who perform related tasks in the field can refer to them.

• 한국보육지원학회지
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• 제6권3호
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• pp.45-63
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• 2010

본 연구는 부모애착, 자아통제력이 청소년의 경비행에 영향을 미치는 과정에서 경비행 친구의 매개적 효과를 검증하기 위해 실행되었다. 이를 위하여 사회통제이론과 일반이론을 토대로 연구모형을 설정한 후, 구조방정식 모형을 활용하여 검증하였다. 분석자료는 한국청소년패널조사 초등학교 4학년 5차년도 자료 2,448사례였다. 분석 결과 구조방정식모형의 측정모형과 구조모형이 모두 자료에 적절한 모형적합도를 보여주었으며, 구조모형의 모든 경로들이 유의미한 것으로 나타났다. 청소년의 부모애착과 자아통제력, 경비행친구는 청소년 경비행에 직접효과를 갖는 것으로 나타났을 뿐 아니라, 부모애착과 자아통제력은 경비행친구의 매개 과정을 통하여 간접효과도 갖는 것으로 나타났다. 본 연구결과를 토대로 청소년 비행 예방 및 실천적 개입에 대한 논의가 이루어졌다.

• Ocean Systems Engineering
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• 제8권3호
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• pp.329-343
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• 2018

The inclination of seabed profile (sloped seabed) is one of the known topographic features which can be observed at different seabed level in the large offshore basin. A mooring system connected between the platform and global seabed is an integral part of the floating structure which tries to keep the floating platform settled in its own position against hostile sea environment. This paper deals with an investigation of the motion responses of an FPSO platform moored on the sloped seabed under the combined action of wave, wind and current loads. A three-dimensional panel discretization method has been used to model the floating body. To introduce the connection of multi-segmented non-linear elastic catenary mooring cables with the sloped seabed, a quasi-static composite catenary model is employed. The model and analysis have been completed by using hydrodynamic diffraction code AQWA. Validation of the numerical model has been successfully carried out with an experimental work published in the latest literature. The analysis procedure in this study has been followed time domain analysis. The study involves an objective oriented investigation on platform motions, in order to identify the effects of the slopped seabed, the action of the wave, wind and current loads and the presence of riser system. In the end, an effective analysis has been performed to identify a stable mooring model in demand of reducing structural responses of the FPSO.

• International Journal of Railway
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• 제6권2호
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• pp.69-77
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• 2013

In this study, numerical analysis and model experiments were conducted to analyze behavioral characteristics acting on the track roadbed with excavation through steel pipe injection, a non-exclusive method of crossing construction under railroad as primary target. In model experiments that simulate injection excavation behaviors with an increase in the depth of soil cover, the upper displacement was measured by construction of the first and the second pipes in order to predict actual behaviors, and the behavior characteristics were verified through numerical analysis. The investigation results showed that surface displacement was smaller under the condition of higher soil cover. In the case of injecting two pipes, when the first pipe was injected, deformation of the surface increased linearly in both settlement and uplift experiments. However, when the second pipe was injected, the amount of change was found to be very small due to the relaxation and plastic zones around the first pipe. In addition, the results of numerical analysis on the same cross section with the model experiment found that the results of investigation into settlement ratio and volume loss were in very good agreement with those obtained by the model experiment.

• 터널과지하공간
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• 제17권3호
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• pp.234-243
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• 2007

본 연구에서는 시추공 조사 결과를 바탕으로 수리지질학적 모델 구축과정에 요구되는 해석과정의 체계화 및 고도화의 일환으로 균열 암반에서의 조사 시추공을 통해 얻어진 균열 정보로부터 지하수 유동경로를 제공하는 구조(Water Conducting Feature, WCF)를 선별하고, 선별된 WCF 정보를 이용하여 HydroDFN 모델을 구축하였다. HydroDFN 모델 내부를 세분한 정육면체 블록에서의 등가투수계수를 계산하고, 계산된 등가블록투수계수는 시추공 투수시험 결과와 비교함으로써 구축된 HydroDFN 모델의 검증에 이용하였다. 이러한 해석과정을 통해 투수량 계수 등으로 대표되는 WCF 파라미터의 설정 및 수리지질학적 모델 구축시의 효과적인 방안을 제안하였다.