• 해양환경안전학회지
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• 제20권1호
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• pp.78-85
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• 2014

일반상선 중 액화천연가스(LNG) 재기화 선박은 기존의 LNG 운반선에 액화된 LNG를 다시 기화할 수 있는 추가설비를 갖춘 선박이다. 이 선박은 해상에서 천연가스를 해저 터미널을 통해 이송하는 수중 터렛 시스템을 보유한다. 하역작업을 완료한 선박이 운항 시에는 수중 터렛이 없음으로 인해 선수부 바닥이 열려 있는 개구부 즉, 오프닝 상태가 발생한다. 본 연구의 주 목적은 오프닝 상태로 운항 시 발생되는 속도손실을 CFD를 이용한 유동해석과 예인수조에서의 모형시험을 통하여 정확하게 파악하였다. 모형시험에서는 나선 상태와 오프닝 상태에서 저항 및 자항성능을 평가하였다. 실험에서는 터프트 법에 의한 유선조사시험을 이용하여 오프닝 내부유동의 변화를 정량적 또는 정성적으로 보다 더 상세한 조사를 하였다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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• pp.225.1-225.1
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• 2010

Within recent years attention has been focused on the method of hydrogen storage using metal hydride reactor due to its high energy density, durability, safety and low operating pressure. In this paper, a numerical study is carried out to investigate the coupled heat and mass transfer process for absorption in a cylindrical metal hydride hydrogen storage reactor using a newly developed model. The simulation results demonstrate the evolution of temperature, equilibrium pressure, H/M atomic ratio and velocity distribution as time goes by. Initially, hydrogen is absorbed earlier from near the wall which sets the cooling boundary condition owing to that absorption process is exothermic reaction. Temperature increases rapidly in entire region at the beginning stage due to the initial low temperature and enough metal surface for hydrogen absorption. As time goes by, temperature decreases slowly from the wall region due to the better heat removal. Equilibrium pressure distribution appears similarly with temperature distribution for reasons of the function of temperature. This work provides a detailed insight into the mechanism and corresponding physicochemical phenomena in the reactor during the hydrogen absorption process.

• 한국터널지하공간학회 논문집
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• 제6권3호
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• pp.259-267
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• 2004

The practice of introducing and grouting reinforced fiber glass pipes or bar into the core to be excavated to maintain stable the tunnel face during excavation has been applied to many tunnels, where difficult geotechnical conditions are present, with good results in terms of safety and speed of works. This reinforcing technique, initially developed to be used jointly with the mechanical precut in clay, has been widely used with other geotechnical conditions as the only type of reinforcement or joined with other ground consolidation and/or reinforcement techniques (i.e. steel pipes or jet-grouting umbrella). At present same numerical researches have been carried out to find which are the real working conditions of the reinforcing elements but no final results have been obtained for the definition of the best design approaches. In this work the results of a three dimensional parametric numerical model is presented.

• 소성∙가공
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• 제29권4호
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• pp.188-193
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• 2020

Piping work of large ships or offshore plants is often done in a narrow and confined space, requiring precise bending and safety. In order to realize an accurate bending angle, it is very important to predict and correct a deformation that may be caused by elasticity in the bending process, that is, an angular deviation due to springback. Therefore, by using CAE analysis to develop a correction angle model for springback based on multiple tube bending angles and using trend line data derived from this correction angle model, at bending the tube as the diameter of the base former and the tube outer diameter change, the springback compensation angle at any angle can be obtained. In this study, the bending mechanism was analyzed to increase the bending precision, and a correction angle model was developed and a trend line was derived in consideration of springback occurring in the bending process. In order to derive a more accurate and reliable trend line, a tube tensile test was performed, and the reliability of the corrected angle trend line was verified by comparing the bending angle measurement and analysis results with a 3D scanner.

• Structural Engineering and Mechanics
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• 제71권1호
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• pp.45-56
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• 2019

A modified mechanical model of pre-pressed spring self-centering energy dissipation (PS-SCED) brace is proposed, and the hysteresis band is distinguished by the indication of relevant state variables. The MDOF frame system equipped with the braces is formulated in an incremental form of linear acceleration method. A multi-objective genetic algorithm (GA) based brace parameter optimization method is developed to obtain an optimal solution from the primary design scheme. Parameter sensitivities derived by the direct differentiation method are used to modify the change rate of parameters in the GA operator. A case study is conducted on a steel braced frame to illustrate the effect of brace parameters on node displacements, and validate the feasibility of the modified mechanical model. The optimization results and computational process information are compared among three cases of different strategies of parameter change as well. The accuracy is also verified by the calculation results of finite element model. This work can help the applications of PS-SCED brace optimization related to parameter sensitivity, and fulfill the systematic design procedure of PS-SCED brace-structure system with completed and prospective consequences.

• International Journal of Advanced Culture Technology
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• 제9권2호
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• pp.72-79
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• 2021

This study is to develop a strategy to prepare an improvement strategy according to the environmental change of the hotel. Currently, domestic hotels are implementing marketing through food and beverage as a countermeasure against the sales decrease, and in order to develop effective marketing plan, 5 Force Model environmental analysis and STP analysis are analyzed. 5 Force Model Environmental Analysis showed that domestic hotels are facing various difficulties such as the expansion of accommodation sharing system, the decrease of Chinese tourists due to the THAAD problem, the increase of hotels, the introduction of PMS, the increase of minimum wage, the introduction of 52 hours work week, and the increase in product preference As an STP response strategy to correspond these difficulties, it is necessary to develop products for the main customers of the hotel food and beverage, such as those in the 20s-30s, the workers, smartphones and SNS users. And also hotels should seek ways to lower price of the product to the level desired by the user to compete against substitutes. In conclusion we suggest that hotels are committed to fulfilling their role by meeting guest safety and COVID-19 compliance requirements, but a focus on immediate cleanliness and quarantine against infectious diseases, like Airbnb, will enable greater growth.

• International Journal of Naval Architecture and Ocean Engineering
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• 제12권1호
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• pp.354-366
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• 2020

This work mainly focuses on determination of the fully plastic J-integral solutions for welded center cracked plates subjected to remote tension loading. Detailed three-dimensional elasticeplastic Finite Element Analyses (FEA) were implemented to compute the fully plastic J-integral along the crack front for a wide range of crack geometries, material properties and weld strength mismatch ratios for 900 cases. According to the database generated from FEA, Back-propagation Neural Network (BPNN) model was proposed to predict the values and distributions of fully plastic J-integral along crack front based on the variables used in FEA. The determination coefficient R2 is greater than 0.99, indicating the robustness and goodness of fit of the developed BPNN model. The network model can accurately and efficiently predict the elastic-plastic J-integral for weld centerline crack, which can be used to perform fracture analyses and safety assessment for welded center cracked plates with varying strength mismatch conditions under uniaxial loading.

• 대한안전경영과학회지
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• 제9권6호
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• pp.123-135
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• 2007

In the recent years, the companies have manually recorded a production status in a work diary or have mainly used a bar code in order to collect each process's progress status, production performance and quality information in the production and logistics process in real time. But, it requires an additional work because the worker's record must be daily checked or the worker must read it with the bar code scanner. At this time, data's accuracy is decreased owing to the worker's intention or mistake, and it causes the problem of the system's reliability. Accordingly, in order to solve such problem, the companies have introduced RFID which comes into the spotlight in the latest automatic identification field. In order to introduce the RFID technology, the process flow must be analyzed, but the ASME sign used by most manufacturing companies has the difficult problem when the aggregation event occurs. Hence, in this study, the RFID logistic flow analysis Modeling Notation was proposed as the signature which can analyze the manufacturing logistic flow amicably, and the manufacturing logistic flow by industry type was analyzed by using the proposed RFID logistic flow analysis signature. Also, to monitor real-time information through EPCglobal network, EPCISEvent template by industry was proposed, and it was utilized as the benchmarking case of companies for RFID introduction. This study suggested to ensure the decision-making on real-time information through EPCglobal network. This study is intended to suggest the Modeling Notation suitable for RFID characteristics, and the study is intended to establish the business step and to present the vocabulary.

• 한국BIM학회 논문집
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• 제12권4호
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• pp.70-79
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• 2022

As BIM(Building Information Modeling) technology advances in architecture around the world, projects and industries using BIM are increasing. Unlike previous developments that were limited to buildings, BIM is now spreading to other fields such as civil engineering and electricity. In architecture, BIM is used in the entire process from design to maintenance of a building, and IFC(Industry Foundation Classes), a neutral format with interoperability, is used as an open BIM format. Since firefighting requires intuitive 3D models for evacuation and fire simulations, BIM models are desirable. However, due to the BIM model, which was developed centered on building objects, there are no objects and specific properties for fire evacuation in the IFC scheme. Therefore, in this study, when adding a new object in the firefighting area to the IFC schema, the IFC interoperability is not broken and the building WBS(Work Breakdown Structure) is analyzed with a hierarchical system similar to the IFC format to define the scope for a new object and the firefighting part within of the building WBS to derive a firefighting HBS(Hierarchy Breakdown Structure) with the extension of the object-oriented IFC file. And according to HBS, we propose an IFC schema extension method. It is a methodology that allows BIM users to instantly adapt the IFC schema to their needs. Accordingly, the methodology derived from this study is expected to be expanded in various areas to minimize information loss from IFC. In the future, we will apply the IFC extension methodology to the actual development process using HBS to verify that it is actually applicable within the IFC schema.

• 한국건축시공학회지
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• 제21권6호
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• pp.629-640
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• 2021

2018년 국토교통부 통계에 따르면 재건축 연한이 도래한 주거용 건축물은 2018년 기준 약 37%에 달한다, 해체물량의 증가는 해체산업의 성장과 함께 환경 및 안전사고 등 많은 부작용을 일으키고 있다. 이에 본 연구는 해체공법 선정에 있어 안전성, 경제성, 환경성 등을 종합적으로 고려하여 현장 적용에 가장 적합한 공법 의사결정 방법을 제시하고, 특히 해체공사의 안전성을 고려하여 현장 공법 적용 시 위험요인에 대한 사전평가를 통해 공법선정뿐만 아니라 선정 공법의 현장 적용성을 평가한다. 이를 위해 본 연구는 QFD 기반의 TOPSIS 해체공법선정과 FMEA 위험성평가 통합모델을 제안한다.