• 방사성폐기물학회지
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• 제8권4호
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• pp.279-291
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• 2010

고준위방사성폐기물처분을 위한 부지특성평가 기술을 구축하고, 이를 활용하여 심부지질환경을 이해하기 위해 1997년부터 지금까지 한국원자력연구원 주변 지역을 고준위폐기물처분을 위한 연구지역으로 선정하여 다양한 지질 관련 연구를 수행해왔다. 특히, 2002년에는 고준위폐기물의 처분 대상 심도의 시추공(지하 500 m)을 굴착하였으며, 2006년에는 지하처분연구시설(KURT, KAERI Underground Research Tunnel)을 준공하여 연구지역에 대한 심부지질환경 규명을 위해 노력하고 있다. 현재, 지하처분연구터널의 좌측 연구용 모듈 내에 500 m 길이의 장심도 시추공을 굴착하여 다양한 부지특성평가 연구를 수행 중에 있다. 본 연구는 고준위폐기물의 심지층 처분을 위한 요소 기술인 심부영역의 부지특성평가기술 구축을 위해 장심도 시추공 자료를 이용하여 KURT 주변의 지질구조 분석하였다. 연구지역의 장심도 시추공에서 지구물리탐사, 시추공 지질조사 등 다양한 현장 조사를 수행하였으며, 그 결과 총 7개의 지질구조를 도출하였다. 이 연구 결과는 KURT 지역의 부지특성연구의 주요한 한 부분으로서 기존에 구축된 지질모델을 보완하는데 이용될 예정이다.

• 한국BIM학회 논문집
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• 제6권1호
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• pp.25-32
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• 2016

In BIM environments for infrastructures, civil structures such as road, bridge and tunnel etc., created into 3D objects, integrated with their properties, securing BIM design productivity is very critical during 3D modeling. To solve this issue, configuring BIM libraries so that the users can utilize prefabricating in advance 3D objects that have been applying repeatedly during BIM design is essential so much. Current BIM libraries have made focused on Ready-Made for architectural facilities. However, establishing environment for delivering BIM library for civil facilities is very sparse. Accordingly, this study developed a web-based sharing system for delivering BIM library contents based on standardized drawing for civil area. To do this, we have analyzed core features and operation system of BIM library sharing system in domestic and overseas. Besides, functional requirements that are necessary for developing BIM library sharing system was derived, and through operation scenario configuration, the web-based system was developed according to the detailed mechanism. It is expected that this system can enhance BIM design productivity during library based modeling, and can be utilized as construction supporting tools that can help construction managers to make a design change.

• Wind and Structures
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• 제22권4호
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• pp.503-524
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• 2016

The suitability of Computational Fluid Dynamics (CFD) simulations on the built environment for the purpose of estimating average roughness characteristics and for studying wind flow patterns within the environment is assessed. Urban models of various levels of complexity are considered including an empty domain, array of obstacles arranged in regular and staggered manners, in-homogeneous roughness with multiple patches, a semi-idealized built environment, and finally a real built environment. For each of the test cases, we conducted CFD simulations using RANS turbulence closure and validated the results against appropriate methods: existing empirical formulas for the homogeneous roughness case, empirical wind speed models for the in-homogeneous roughness case, and wind tunnel tests for the semi-idealized built environment case. In general, results obtained from the CFD simulations show good agreement with the corresponding validation methods, thereby, giving further evidence to the suitability of CFD simulations for built environment studies consisting of wide-ranging roughness. This work also provides a comprehensive overview of roughness modeling in CFD-from the simplest approach of modeling roughness implicitly through wall functions to the most elaborate approach of modeling roughness explicitly for the sake of accurate wind flow simulations within the built environment.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 1993년도 추계학술강연 및 발표대회강연 및 발표논문 초록집
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• pp.2-2
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• 1993

The present status of the thennomechanica1 evaluation of functionally gradient materials(FGMs) for space plane application was reviewed, in which research activities and the cooperation of the national project team organized to study FGM science were demonstrated. The project team was divided into three working groups; de singing, processing and evaluation, each of which had their own tasks in the project cooperation. The testings details of the various thennomechanical tests for the FGM samples fabricated by the processing groups were described, along with their corresponding heating conditions of the real environments in the space plane application. For small-sized samples, laser beam heating test and burner heating test were well applied to study the heat shielding and heat resisting properties. Arc-heated wind tunnel test and high temperature!high velocity gas flow test were used for large-sized panel assemblies having cooling structures. The criteria for the evaluation of the heat shielding and heat resisting properties of the FGMs, as well as a crack activation mechanism in their differential temperature heating, were proposed on the basis of the observation in the burner heating test.

• International Journal of Aerospace System Engineering
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• 제2권2호
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• pp.50-53
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• 2015

It would encounter some complicated flow fields, such as transition, separation, reattachment and disturbances, in the hypersonic flight. Thus, it is difficult to theoretically analyze the hypersonic aerothermodynamics effects, so that the ground-test simulation is thought of as one of the most important methods to improve the understanding level of the hypersonic aerothermodynamics. However, the aero-heating tests could not simulate all aerodynamics and geometry parameters in the real flight due to the differences between the experimental environments supplied by the ground facilities and the flight, so that the feasible technique for the ground-test simulation of the hypersonic aerothermodynamics effects is required to be advanced. The key parameters that are especially required to simulate for aero-heating tests are analyzed and one detailed approach is suggested to perform the experimental investigation on the hypersonic aero-heating effects in the ground facilities in this paper, and the tests are performed in the FD-20 gun tunnel of CAAA (China Academy of Aerospace Aerodynamics) to give out the data which could be used to confirm the equation from the theoretical analysis.

• Smart Structures and Systems
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• 제7권5호
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• pp.365-378
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• 2011

Piezo-based active structural health monitoring (SHM) requires amplifiers specifically designed for capacitive loads. Moreover, with the increase in number of applications of wireless SHM systems, energy efficiency and cost reduction for this type of amplifiers is becoming a requirement. General lab grade amplifiers are big and costly, and not built for outdoor environments. Although some piezoceramic power amplifiers are available in the market, none of them are specifically targeting the wireless constraints and low power requirements. In this paper, a piezoceramic transducer amplifier for wireless active SHM systems has been designed. Power requirements are met by two digital On/Off switches that set the amplifier in a standby state when not in use. It provides a stable ${\pm}180$ Volts output with a bandwidth of 7k Hz using a single 12 V battery. Additionally, both voltage and current outputs are provided for feedback control, impedance check, or actuator damage verification. Vibration control tests of an aluminum beam were conducted in the University of Houston lab, while wireless active SHM tests of a wind turbine blade were performed in the Harbin Institute of Technology wind tunnel. The results showed that the developed amplifier provided equivalent results to commercial solutions in suppressing structural vibrations, and that it allows researchers to perform active wireless SHM on moving objects with no power wires from the grid.

• 국제초고층학회논문집
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• 제11권4호
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• pp.265-276
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• 2022

Double-Skin Facades (DSF) on tall buildings are becoming increasingly common in urban environments due to their ability to provide architectural merit, passive design, acoustic control and even improved structural efficiency. This study aims to understand the effects of porous DSF on the aerodynamic characteristics of tall buildings using wind tunnel tests. High Frequency Force Balance and pressure tests were performed on the CAARC standard tall building model with a variable porous DSF on the windward face. The introduction of a porous DSF did not adversely affect the overall mean forces and moments experienced by the building, with few differences compared to the standard tall building model. There was also minimal variation between the results for the three porosities tested: 50%, 65% and 80%. The presence of a full-height porous DSF was shown to effectively reduce the mean and fluctuating wind pressure on the side face of the building by about 10%, and a porous DSF over the lower half height of the building was almost as effective. This indicates that the porous DSF could be used to reduce the design load on cladding and fixtures on the side faces of tall buildings, where most damage to facades typically occurs.

• 한국생활과학회지
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• 제17권4호
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• pp.661-677
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• 2008

The purpose of this study is to develop the playground environment model for child care center by analyzing user needs of playground environment. To systemize the playground environment design factors and guidelines, we reviewed the previous research, actual measurement and observation were used as the research methodology. And to recognize the needs of users, the survey and picture survey was conducted to the staffs and children. The scope of survey included child care centers in Seoul and Daejeon, ultimately selecting 12 places in Seoul and 13 places in Daejeon. In terms of the survey period, actual measurement was conducted from June of 2006 to February of 2007, survey and picture survey was conducted from August to September of 2006. For analysis, we used SPSS 10.0 to check the frequency and percentage, as well as to perform cluster analysis. The findings of research can be summarized as below: 1. In playground environment, we observed the area of play ground and ground cover, the independence of play area, play equipment, and the composition of play area. The result of observation showed that while playground area varied widely, ground cover, play equipment, and the composition of play area turned out to be identical, regardless of the playground's area. Therefore, in order to classify various playground environments, we categorized them into 5 types, using the number of children and the area of play ground as a category. Type A had large facilities and small playground area. Type B had small sized facilities and large playground area. Type C had medium sized facilities and small playground area. Type D had medium sized facilities but large playground area. Type E had large sized facilities and large playground area. 2. On the other hand, staffs wanted a tunnel, playhouse, comprehensive play equipment, and a maze to be installed as play facilities, and there were requests for adventure play area and carpenter play area. The picture survey to children showed that they wanted equipments that can provide more thrill, adventure and challenge to them than the ones they see now. Therefore, existing child care center play environments must change from the monotonous and identical environments to the ones that can provide diversities, challenges, and adventures. In the contexts of 5 playground types suggested by this research, type B and D, E where the area of playground were larger than the legally required, should include various play areas and install appropriate play equipments and facilities. Type A and C where the area were small, should provide multipurpose play area to attract the various play behaviors of children.

• 설비공학논문집
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• 제23권6호
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• pp.449-469
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• 2011

This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigerating Engineering during 2010. It is intended to understand the status of current research in the areas of heating, cooling, ventilation, sanitation, and indoor environments of buildings and plant facilities. Conclusions are as follows. (1) Research trends of thermal and fluid engineering have been surveyed as groups of general thermal and fluid flow, fluid machinery, and new and renewable energy. Various topics were presented in the field of general thermal and fluid flow. Research issues mainly focused on the thermal reliability of axial fan and compressor in the field of fluid machinery. Studies on the design of ground source heat pump systems and solar chemical reactors were executed in the field of new and renewable energy. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics and industrial heat exchangers. Researches on heat transfer characteristics included heat transfer in thermoelectric cooling/power generation systems, combined heat and power systems, carbon nano fluid with PVP, channel filled with metal foam and smoke ventilation in a rescue station of a railroad tunnel. Also the studies on flow boiling of R123/oil mixture in a plain tube bundle and R410A charge amount in an air cooled mini-channel condenser were reported. In the area of industrial heat exchangers, researches on plate heat exchanger, shell and tube heat exchanger, enthalpy exchanger, micro channel PCHE were performed. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics and industrial heat exchangers. Researches on heat transfer characteristics included heat transfer in thermoelectric cooling/power generation systems, combined heat and power systems, carbon nano fluid with PVP, channel filled with metal foam and smoke ventilation in a rescue station of a railroad tunnel. Also the studies on flow boiling of R123/oil mixture in a plain tube bundle and R410A charge amount in an air cooled mini-channel condenser were reported. In the area of industrial heat exchangers, researches on plate heat exchanger, shell and tube heat exchanger, enthalpy exchanger, micro channel PCHE were performed. (3) Refrigeration systems with alternative refrigerants such as hydrocarbons, mixed refrigerants, and CO2 were studied. Performance improvement of refrigeration systems are tried applying various ideas of refrigerant subcooling, dual evaporator with hot gas bypass control and feedforward control. The hybrid solar systems combining the solar collection devices with absorption chillers or compression heat pumps are simulated and studied experimentally as well to improve the understanding and the feasibility for actual applications. (4) Research trend in the field of mechanical building facilities has been found to be mainly focused on field applications rather than performance improvements. Various studies on heating and cooling systems, HVAC facilities, indoor air environments and energy resources were carried to improve the maintenance and management of building service equipments. In the field of heating and cooling systems, papers on a transformer cooling system, a combined heat and power, a slab thermal storage and a heat pump were reported. In the field of HVAC facilities, papers on a cooling load, an ondol and a drying were presented. Also, studies on HVAC systems using unutilized indoor air environments and energy resources such as air curtains, bioviolence, cleanrooms, ventilation, district heating, landfill gas were studied. (5) In the field of architectural environment and energy, studies of various purposes were conducted such as indoor environment, building energy, renewable energy and green building. In particular, renewable energy and building energy-related researches have mainly been studied reflecting the global interest. In addition, many researches which related the domestic green building certification of school building were performed to improve the indoor environment of school.

• 한국대기환경학회지
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• 제26권5호
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• pp.543-553
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• 2010

Almost five million citizens a day are using subways as a means of traffic communication in the Seoul metropolitan. As the subway system is typically a closed environment, indoor air pollution problems frequently occurs and passengers complain of mal-health impact. Especially $PM_{10}$ is well known as one of the major pollutants in subway indoor environments. The purpose of this study was to compare the indoor air quality in terms of $PM_{10}$ and to quantitatively compare its source contributions in a Seoul subway platform before and after installing platform screen doors (PSD). $PM_{10}$ samples were collected on the J station platform of Subway Line 7 in Seoul metropolitan area from Jun. 12, 2008 to Jan. 12, 2009. The samples collected on membrane filters using $PM_{10}$ mini-volume portable samplers were then analyzed for trace metals and soluble ions. A total of 18 chemical species (Ba, Mn, Cr, Cd, Si, Fe, Ni, Al, Cu, Pb, Ti, $Na^+$, $NH_4^+$, $K^+$, $Mg^{2+}$, $Ca^{2+}$, $Cl^-$, and ${SO_4}^{2-}$) were analyzed by using an ICP-AES and an IC after performing proper pre-treatments of each sample filter. Based on the chemical information, positive matrix factorization (PMF) model was applied to identify the source of particulate matters. $PM_{10}$ for the station was characterized by three sources such as ferrous related source, soil and road dust related source, and fine secondary aerosol source. After installing PSD, the average $PM_{10}$ concentration was decreased by 20.5% during the study periods. Especially the contribution of the ferrous related source emitted during train service in a tunnel route was decreased from 59.1% to 43.8% since both platform and tunnel areas were completely blocked by screen doors. However, the contribution of the fine secondary aerosol source emitted from various outside combustion activities was increased from 14.8% to 29.9% presumably due to ill-managed ventilation system and confined platform space.