• Title/Summary/Keyword: Optimum Shape Design

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Shape Optimization of the Plane Truss Structures with the Statical and Natural Frequency Constraints (정적(靜的) 및 고유진동수(固有振動數) 제약조건식(制約條件式)을 고려(考慮)한 평면(平面) 트러스 구조물(構造物)의 형상최적화(形狀最適化)에 관(關)한 연구(硏究))

  • Lee, Gyu Won;Lee, Gun Tea
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.10 no.2
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    • pp.23-38
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    • 1990
  • In this study, decompositive optimization method of two levels was selected to optimize effectively the geometry of the truss which takes the multi-loading condition, and the allowable stress, bucking stress, displacement and natural frequency constraints into consideration. The algorithm of this study is made up of sectional optimization using the feasible direction method in level 1, and geometrical optimization employing Powell's one-direction search method which menimizes only objictive function in level 2. The results of this study acquired by beenning applied to structural model of the truss are as follows : 1. It is verified that the algorithm of this study effectively converges, independent of the initial geometry of the truss and the applied various constraints. 2. The optimum goemetry of the truss varies more considerably according to the constraints selected. 3. Under the condition of the same design, the weight of the truss can be decreased more considerably by means of optimizing even the geometry of truss than by means of optimizing the section of truss while fixing geometrical configuration of it, even though there might be a little difference according to the initial geometry of the truss and the design condition.

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Measurement of Joint-Orientation and Monitoring of Displacement in Tunnel using 3D Laser Scanning System (3차원 레이저 스캐닝 시스템을 이용한 불연속면의 방향성 측정과 터널 변위 모니터링)

  • Shon, Ho-Woong;Oh, Seok-Hoon;Kim, Young-Kyung
    • Journal of the Korean Geophysical Society
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    • v.9 no.1
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    • pp.47-62
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    • 2006
  • More than 70% of Korean Peninsula is consisted of mountains, so that lots of roads, rail-roads and tunnel,which play a pivotal role in the industry activity, are existed along the rock-slope and in the rock-mass. Thus,it is urgent that tegration of management system through the optimum survey and design of rock-slope excavation, proper stabilization method and database of rock-slope. However, conventional methods have shortcoming with the economy of survey time and human resources, and the overcome of difficulties of approach to the in-situ rock-slope. To overcome the limitation of conventional method, this paper proposed the development of remote measurement system using Terrestrial Laser Scanning System. The method using Terrestrial 3D Laser Scanning System, which can get 3D spatial information on the rock-slope and2)Dept. Geosystem Engineering, Kangwon National University, Korea tunnel, has an advantage of reduction of measurement time and the overcome of difficulties of approach to the in-situ rock-slope/dam/tunnel. In the case of rock-slope, through the analysis of 3D modeling of point-cloud by Terrestrial Laser Scanning System, orientation of discontinuity, roughness of joint surface, failure shape and volume were successively achieved. in the case of tunnel face, through reverse-engineering, monitoring of displacement was possible.

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Simulation of Remote Field Scanner for Defect Evaluation of Water Wall Tube Within the Fluidized Bed Boiler (유동층보일러 수냉벽튜브 결함평가를 위한 원격자장 스캐너 시뮬레이션에 관한 연구)

  • Gil, Doo-Song;Jung, Gye-Jo;Seo, Jung-Seok;Kim, Hak-Joon;Kwon, Chan-Wool
    • KEPCO Journal on Electric Power and Energy
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    • v.6 no.2
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    • pp.145-150
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    • 2020
  • Water wall tube is one of the major factors consisting of a fluidized bed boiler and it plays very important role for the generation of electricity within the boiler. But these water wall tubes within the fluidized bed boiler are subject to the ware and corrosion caused by the high temperature gas and the flowing medium. If water leak is occurred, the secondary damage by the water leak will occur. As a result of that, the power generation efficiency decreases noticeably. Therefore, the maintenance of the water wall tube is very important. In this study, we designed a exciter sensor based on simulation and composed a remote field eddy current system for the defect evaluation of the outer water wall tube. Starting from the shape design of exciter, we conducted simulations for various design factors such as the water wall tube size, material, frequency, lift-off and so on. Based on the results, we designed the optimum exciter sensor for the water wall tube test within the fluidized bed boiler.

Development of Optimum Grip System in Developing Design Tensile Strength of GFRP Rebars (GFRP 보강근의 설계 인장강도 발현을 위한 적정 그립시스템 개발)

  • You Young-Chan;Park Ji-Sun;You Young-Jun;Park Young-Hwan;Kim Keung-Hwan
    • Journal of the Korea Concrete Institute
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    • v.17 no.6 s.90
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    • pp.947-953
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    • 2005
  • Previous test results showed that the current ASTM(American Standard for Testing and Materials) grip adapter for GFRP(Glass Fiber Reinforced Polymer) rebar was not fully successful in developing the design tensile strength of GFRP rebars with reasonable accuracy. It is because the current ASTM grip adapter which is composed of a pair of rectangular metal blocks of which inner faces are grooved along the longitudinal direction does not take into account the various geometric characteristics of GFRP rebar such as surface treatment, shape of bar cross section as well as physical characteristics such as poisson effect, elastic modulus in the transverse direction and so on. The objective of this paper is to provide how to proportion the optimum diameter of inner groove in ASTM grip adapter to develop design tensile strength of GFRP rebar. The proportioning of inner groove in ASTM grip adapter is based on the force equilibrium of GFRP rebar between tensile capacity and minimum frictional resistance required along the grip adapter. The frictional resistance of grip adapter is calculated based on the compressive strain compatibility in radial direction induced by the difference between diameter of GFRP rebar and inner groove In ASTM grip. All testing procedures were made according to the CSA S806-02 recommendations. From the preliminary test results on round-type GFRP rebars, it was found that maximum tensile loads acquired under the same testing conditions is highly affected by the diameter of inner groove in ASTM grip adapter. The grip adapter with specific dimension proportioned by proposed method recorded the highest tensile strength among them.

Manufacture and Evaluation of Reference Samples for Low Magnetic Moment (저자기 모멘트용 표준시료 제작 및 성능평가)

  • Park, I.W.;Hong, Y.S.;Kim, Y.M.;Yoon, H.;Lee, K.J.;Cho, S.H.
    • Journal of the Korean Magnetics Society
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    • v.18 no.1
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    • pp.1-8
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    • 2008
  • We have manufactured and evaluated reference samples for the use of low magnetic moment measurements. Before the measurements, SQUID magnetometers were magnetically shielded from external magnetic noise. We considered the purity including magnetic impurities, the optimum thickness, the modification method, and the shape in the preparation of the samples. Three paramagnetic polycrystaline metal plates of Ti, W, and Al with the area of $4mm{\times}6mm$ were prepared finally. The magnetic moments of these three samples are measured very linear up to the field of 5 T without magnetic hysteresis. The temperature deviated ratios of the magnetic moments for Ti, Al, and W from 290 K to 310 K are 0.7, 1.5, and 0.1 %, respectively. The measured magnetic moments for Ti and W samples by our research team are very well agreeable with those by two SQUID magnetometers and a VSM at Quantum Design via international round robin test. The results suggest that the prepared reference samples are well suited for the use in the low magnetic moment measurement with SQUID based magnetometers.

DEM-based numerical study on discharge behavior of EPB-TBM screw conveyor for rock (EPB-TBM 암반굴착시 스크류컨베이어의 배토 거동에 대한 DEM 기반 수치해석적 연구)

  • Lee, Gi-Jun;Kwon, Tae-Hyuk;Kim, Huntae
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.21 no.1
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    • pp.127-136
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    • 2019
  • Tunnel construction by TBMs should be supported by the performance of a screw conveyor in order to obtain the optimum penetration rate, so studies related to the screw conveyor performance have been being conducted. Compared to the study on the performance of the screw conveyor for the soil, however, the research on the performance of the screw conveyor for the rock is insufficient. Considering the domestic tunnel sites with more rock layers than soil layers, simulation of discharge of 6 types of rock chips by the screw conveyor was conducted using DEM. Regardless of the shape and volume of the rock chips, the discharge rates of the rock chips by the parallel placed screw conveyor at a speed of 10 RPM in the same rock mass were about 20% (standard deviation: 1.3%) of the maximum volume of discharge rate by the screw conveyor. It is expected that this study can be used as a reference material for screw conveyor design and operation in TBM excavations in rock masses.

Analysis and Evaluation of CPC / COLSS Related Test Result During YGN 3 Initial Startup (영광 3호기 초기 시운전 동안 CPC / COLSS 관련시험 결과 분석 및 평가)

  • Chi, S.G.;Yu, S.S.;In, W.K.;Auh, G.S.;Doo, J.Y.;Kim, D.K.
    • Nuclear Engineering and Technology
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    • v.27 no.6
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    • pp.877-887
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    • 1995
  • YGN 3 is the first nuclear power plant to use the Core Protection Calculator (CPC) as the core protection system and the Core Operating Limit Supervisory System (COLSS) as the core monitor-ing system in Korea. The CPC is designed to provide on-line calculations of Departure from Nucleate Boiling Ratio (DNBR) and Local Power Density (LPD) and to initiate reactor trip if the core conditions exceed the DNBR or LPD design limit. The COLSS is designed to assist the operator in implementing the Limiting Conditions for Operation (LCOs) in Technical Specifications for DNBR/Linear Heat Rate (LHR) margin, azimuthal tilt, and axial shape index and to provide alarm when the LCOs are reached. During YGN 3 initial startup testing, extensive CPC/COLSS related tests ore peformed to ver-ify the CPC/COLSS performance and to obtain optimum CPC/COLSS calibration constants at var, -ious core conditions. Most of test results met their specific acceptance criteria. In the case of missing the acceptance criteria, the test results ore analyzed, evaluated, and justified. Through the analysis and evaluation of each of the CPC/COLSS related test results, it can be concluded that the CPC/COLSS are successfully Implemented as designed at YGN 3.

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Recent Progress in Air-Conditioning and Refrigeration Research : A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2013 (설비공학 분야의 최근 연구 동향 : 2013년 학회지 논문에 대한 종합적 고찰)

  • Lee, Dae-Young;Kim, Sa Ryang;Kim, Hyun-Jung;Kim, Dong-Seon;Park, Jun-Seok;Ihm, Pyeong Chan
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.26 no.12
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    • pp.605-619
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    • 2014
  • This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2013. 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) The research works on the thermal and fluid engineering have been reviewed as groups of fluid machinery, pipes and relative parts including orifices, dampers and ducts, fuel cells and power plants, cooling and air-conditioning, heat and mass transfer, two phase flow, and the flow around buildings and structures. Research issues dealing with home appliances, flows around buildings, nuclear power plant, and manufacturing processes are newly added in thermal and fluid engineering research area. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics, pool boiling and condensing heat transfer and industrial heat exchangers. Researches on heat transfer characteristics included the results for general analytical model for desiccant wheels, the effects of water absorption on the thermal conductivity of insulation materials, thermal properties of Octadecane/xGnP shape-stabilized phase change materials and $CO_2$ and $CO_2$-Hydrate mixture, effect of ground source heat pump system, the heat flux meter location for the performance test of a refrigerator vacuum insulation panel, a parallel flow evaporator for a heat pump dryer, the condensation risk assessment of vacuum multi-layer glass and triple glass, optimization of a forced convection type PCM refrigeration module, surface temperature sensor using fluorescent nanoporous thin film. In the area of pool boiling and condensing heat transfer, researches on ammonia inside horizontal smooth small tube, R1234yf on various enhanced surfaces, HFC32/HFC152a on a plain surface, spray cooling up to critical heat flux on a low-fin enhanced surface were actively carried out. In the area of industrial heat exchangers, researches on a fin tube type adsorber, the mass-transfer kinetics of a fin-tube-type adsorption bed, fin-and-tube heat exchangers having sine wave fins and oval tubes, louvered fin heat exchanger were performed. (3) In the field of refrigeration, studies are categorized into three groups namely refrigeration cycle, refrigerant and modeling and control. In the category of refrigeration cycle, studies were focused on the enhancement or optimization of experimental or commercial systems including a R410a VRF(Various Refrigerant Flow) heat pump, a R134a 2-stage screw heat pump and a R134a double-heat source automotive air-conditioner system. In the category of refrigerant, studies were carried out for the application of alternative refrigerants or refrigeration technologies including $CO_2$ water heaters, a R1234yf automotive air-conditioner, a R436b water cooler and a thermoelectric refrigerator. In the category of modeling and control, theoretical and experimental studies were carried out to predict the performance of various thermal and control systems including the long-term energy analysis of a geo-thermal heat pump system coupled to cast-in-place energy piles, the dynamic simulation of a water heater-coupled hybrid heat pump and the numerical simulation of an integral optimum regulating controller for a system heat pump. (4) In building mechanical system research fields, twenty one studies were conducted to achieve effective design of the mechanical systems, and also to maximize the energy efficiency of buildings. The topics of the studies included heating and cooling, HVAC system, ventilation, and renewable energies in the buildings. Proposed designs, performance tests using numerical methods and experiments provide useful information and key data which can improve the energy efficiency of the buildings. (5) The field of architectural environment is mostly focused on indoor environment and building energy. The main researches of indoor environment are related to infiltration, ventilation, leak flow and airtightness performance in residential building. The subjects of building energy are worked on energy saving, operation method and optimum operation of building energy systems. The remained studies are related to the special facility such as cleanroom, internet data center and biosafety laboratory. water supply and drain system, defining standard input variables of BIM (Building Information Modeling) for facility management system, estimating capability and providing operation guidelines of subway station as shelter for refuge and evaluation of pollutant emissions from furniture-like products.

Recent Progress in Air-Conditioning and Refrigeration Research: A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2014 (설비공학 분야의 최근 연구 동향: 2014년 학회지 논문에 대한 종합적 고찰)

  • Lee, Dae-Young;Kim, Sa Ryang;Kim, Hyun-Jung;Kim, Dong-Seon;Park, Jun-Seok;Ihm, Pyeong Chan
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.27 no.7
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    • pp.380-394
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    • 2015
  • This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2014. 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) The research works on the thermal and fluid engineering have been reviewed as groups of heat and mass transfer, cooling and heating, and air-conditioning, the flow inside building rooms, and smoke control on fire. Research issues dealing with duct and pipe were reduced, but flows inside building rooms, and smoke controls were newly added in thermal and fluid engineering research area. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics, pool boiling and condensing heat transfer and industrial heat exchangers. Researches on heat transfer characteristics included the results for thermal contact resistance measurement of metal interface, a fan coil with an oval-type heat exchanger, fouling characteristics of plate heat exchangers, effect of rib pitch in a two wall divergent channel, semi-empirical analysis in vertical mesoscale tubes, an integrated drying machine, microscale surface wrinkles, brazed plate heat exchangers, numerical analysis in printed circuit heat exchanger. In the area of pool boiling and condensing, non-uniform air flow, PCM applied thermal storage wall system, a new wavy cylindrical shape capsule, and HFC32/HFC152a mixtures on enhanced tubes, were actively studied. In the area of industrial heat exchangers, researches on solar water storage tank, effective design on the inserting part of refrigerator door gasket, impact of different boundary conditions in generating g-function, various construction of SCW type ground heat exchanger and a heat pump for closed cooling water heat recovery were performed. (3) In the field of refrigeration, various studies were carried out in the categories of refrigeration cycle, alternative refrigeration and modelling and controls including energy recoveries from industrial boilers and vehicles, improvement of dehumidification systems, novel defrost systems, fault diagnosis and optimum controls for heat pump systems. It is particularly notable that a substantial number of studies were dedicated for the development of air-conditioning and power recovery systems for electric vehicles in this year. (4) In building mechanical system research fields, seventeen studies were reported for achieving effective design of the mechanical systems, and also for maximizing the energy efficiency of buildings. The topics of the studies included energy performance, HVAC system, ventilation, and renewable energies, piping in the buildings. Proposed designs, performance performance tests using numerical methods and experiments provide useful information and key data which can improve the energy efficiency of the buildings. (5) The field of architectural environment was mostly focused on indoor environment and building energy. The main researches of indoor environment were related to the evaluation of work noise in tunnel construction and the simulation and development of a light-shelf system. The subjects of building energy were worked on the energy saving of office building applied with window blind and phase change material(PCM), a method of existing building energy simulation using energy audit data, the estimation of thermal consumption unit of apartment building and its case studies, dynamic window performance, a writing method of energy consumption report and energy estimation of apartment building using district heating system. The remained studies were related to the improvement of architectural engineering education system for plant engineering industry, estimating cooling and heating degree days for variable base temperature, a prediction method of underground temperature, the comfort control algorithm of car air conditioner, the smoke control performance evaluation of high-rise building, evaluation of thermal energy systems of bio safety laboratory and a development of measuring device of solar heat gain coefficient of fenestration system.