• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.13 no.4
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• pp.253-262
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• 2015

Radionuclide deposited on the surface of several internal and external systems in a nuclear power plant is created by the activation of corrosion products from nuclear reactor structural materials and fission products. Especially, the constant contact between water and the surface corrodes the inside where primary system makes coolants and corrosion products mixed. Also, these are circulated along the systems. For comparing models, CRUDTRAN, DISER, MIGA-RT and CPAIR codes are analyzed to predict the quantity of radionuclide and corrosion product of primary reactor that are used at the stage of designing. The corrosion products behavior of domestic PWR primary system was predicted by using CRUDTRAN. This study aims to increase the reliability of corrosion product evaluation model by comparing the actual values and calculated values with the data of a Westing House-type Nuclear Power Plant.

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.2029-2033
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• 2007

오늘날 특정 유역에서의 수문현상 및 수문순환에 대한 분석을 위한 연구가 활발히 진행되고 있다. 이를 위해서는 수문자료의 관측은 반드시 수반되어야 하며, 관측자료의 품질관리 및 원시자료의 관리 등이 요구되고 있는 실정이다. 관측된 수문자료의 품질관리라 함은 자료의 신뢰도 분석과 자료의 보완의 두 과정을 포함한다. 여기서, 신뢰도 분석이라 함은 자료 속에 포함된 불확실성을 판별하는 작업을 의미하며, 자료의 불확실성은 위에서 언급된 자료의 불충분 및 불안정을 제외한 부정확, 불일관성에서 비롯된다. 자료의 보완이라 함은 자료의 신뢰도 분석을 통하여 자료 속에 포함된 불확실한 성분들을 찾아내고, 이를 제거한 후 완전한 자료로 대체하고, 자료가 결측된 경우 공백을 연결함으로써 자료의 완전성을 유지하거나 또는 불충분한 자료를 확장하는 일련의 보완작업이라고 정의한다. 자료의 품질을 결정하는 주요 인자는 크게 관측소 관리의 하드웨어적인 측면과 자료 분석의 소프트웨어적인 측면이 있다. 하드웨어적인 측면에서의 수문자료 품질관리를 위해서 본 과제에서는 현장에 설치된 수위계, 강우량계의 센서 등에 대한 장비를 점검하고, 현장실측을 통해 지속적으로 측정값을 보정해주는 역할을 수행하고 있으며, 소프트웨어적인 측면에서 수문자료의 품질관리를 위해서는 수문자료의 수집 단계부터 시작하여 데이터베이스 저장, 필터링, 통계분석, 웹 및 C/S(Client Server)를 통한 배포 등의 일련의 자료 처리 과정을 수행할 수 있는 수문자료관리 프로그램을 웹 시스템과 C/S로 분류하여 정의내릴 수 있다. 본 연구에서는 수문자료의 관리자 입장에서의 보다 효율적이고 체계적으로 자료를 관리하고 분석하기 위한 방안으로 수문자료관리시스템(Hydrologic Data Aquisition and Management System, HDAMS)을 개발하였다. 이 시스템은 안양천 유역에서 시범 적용하고 있으며, 범용성을 전제로 개발되었다. 또한 수문자료 관리 프로그램의 DB 구조 및 DB 자료를 활용한 다양한 분석기능은 갖도록 설계하였으며 계획된 데이터베이스 구조를 바탕으로 계측기 인터페이스와 사용자 인터페이스, 데이터베이스 간의 연동이 원활히 이루어지도록 개발하고자 한다.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.21 no.5
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• pp.391-404
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• 2009

A small hydropower plant(SHP) using cooling water discharged from the power plant was constructed in Samcheonpo. This study presents predicted and measured hydrological data in the construction process of small hydropower plant in order to evaluate characteristics of water level variation of cooling water discharge channel which is a key factor in the design of SHP since the water level rise of channel is related to impact on circulating water system of the existing power plant. Various methods were applied for prediction of water level variation in the design stage from simple empirical formula to sophisticated 3-dimensional CFD method. Measured results reveal that mean value was similar between measured and predicted, but measured results were larger than predicted in deviation. Moreover, simple formula, i.e. standard weir equation and Honma equation, were more useful before installation of SHP, but sophisticated methods during operation of SHP.

• Journal of Biomedical Engineering Research
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• v.10 no.2
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• pp.139-150
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• 1989

A new motor-driven blood pump for artificial heart was developed. In this blood pump, a small size, high torque brushless DC motor was used as an energy converter and the motor rolls back and forth on a circular track. This movement of the "rolling-cyliner" causes blood ejection by alternately pushing left or right polyurethane blood sacs. This moving-actuator mechanism could be eliminate two potential problems of other motor-driven artificial hearts such as large size and poor anastomosis for the implantation. Theoretical analyses on the pump efficiency, the temperature rise, and the inflow mechanism were also performed. In a series of mock circulation tests, the theoretical analyses were compared to the measured hemodynamic and mechanical values. The pump system was shown to have sufficient cardiac output (upto 9 L/min), sensitivity to preload, and mechanical stability to be tested as an implantable total artificial heart.ial heart.

• Applied Chemistry for Engineering
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• v.25 no.4
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• pp.409-413
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• 2014

This study was carried out to design the optimum mixing ratio of aggregate, cyclic aggregate, and binder (moisture, emulsified asphalt, and emulsion type additives) and produce recycling cold asphalt paving mixture satisfying site work standard. The cyclic aggregate satisfying KS F 2572 was collected from waste asphalt by adequate processing. As the moisture content increased, the shearing strength was decreased. The maximum marshall stability was shown at the 3.0 wt% moisture content. So the optimum moisture content was 3.0 wt%. The marshall stability and flow value with the amount of emulsified asphalt was satisfied in the range of 0.5~2.5 wt%, and the porosity was satisfied in the range of 0.7~2.5 wt%. So the optimum amount of emulsified asphalt was 1.6 wt%. The optimum amount of emulsion type additive was 0.1 wt% in the light of marshall stability and degree of saturation of recycling cold asphalt mixture.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.04a
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• pp.322-325
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• 2007

This paper shows the development procedure of the low pressure LOX feed system which is used in the liquid rocket with a turbopump. Korean Air has cooperated with KARI in developing the LOX feed system to turbopump. The LOX feed system is characterized with cryogenic temperature and the thin-thickness tube for weight saving. The system in this project is composed with a main feed line and a recirculation line for the LOX temperature conditioning. Each piping system has many components, namely, bellows, filter, orifice, valves, flange and support. In this paper, system design & manufacturing, structural & thermal analyses, and component tests are explained. Finally, the system was assembled to the KARI's PTF test facility and functioned well to meet its required performance.

• Journal of the Korea Society for Simulation
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• v.20 no.2
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• pp.11-17
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• 2011

The purpose of this study is 3 dimensional modeling of lower part of drilling system in offshore rig and simulation of drilling process. Recently, shipbuilding companies have been focusing on offshore rigs due to their high added-value and the reduced demand of new shipbuilding. In most cases, however, the basic design, installation and management of offshore rig are carried out by foreign companies. Therefore, it is difficult to obtain the knowledge and information of drilling system. In this study drilling devices, BOP(Blowout Preventor) and cementing job and mud circulation related components are included as the main components of offshore rig. The structure and function of them were analyzed from a viewpoint of object-oriented technique. On the basis of this analysis they were modeled in the 3 dimensional structure with 3D software tool such as CATIA and 3DVIA Composer. The drilling process was simulated according to the scenario of drilling operation. This simulation system can be effectively used for an educational tool for students and engineers in ocean plant industries.

• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.1
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• pp.104-111
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• 2017

This research focuses on simulation and visualization of flow field characteristics inside a centrifugal pump. The 3D numerical analysis was carried out by using a numerical CFD tool, addressing a Reynolds Average Navier-Stock code with a standard k-${\varepsilon}$ two-equation turbulence model. The simulation accounts for friction head loss due to rough walls at suction, impeller, discharge areas and volumetric head loss at impeller wear ring. A comparison of performance curves between simulation and experimentation is included, and it reveals a same trend of those results with a small difference of maximum 5 %. At best efficiency point, velocity vectors are smooth but it changes significantly under off-design point, a strong recirculation appears at the outlet of impeller passages near tongue area. A relatively uniform preassure distribution was observed around the impeller in despite of the tongue. Within the volute, because of its geometry, spiral vortexes formed, proving that the flow field in this region was relatively turbulent and unsteady.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.38 no.3
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• pp.282-291
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• 2001

In this paper, an efficient VLSI architecture of Shape Adaptive Discrete Cosine Transform(SADCT) based on systolic array is proposed. Since transform size in SADCT is varied according to the shape of object in each block, it are dropped that both usability of processing elements(PE´s) and throughput rate in time-recursive SADCT structure. To overcome these disadvantages, it is proposed that the architecture based on a systolic way structure which doesn´t need memory. In the proposed architecture, throughput rate is improved by consecutive processing of one-dimensional SADCT without memory and PE´s in the first column are connected to that in the last one for improvement of usability of PE. And input data are put into each column of PE in parallel according to the maximum data number in each rearranged block. The proposed architecture is described by VHDL. Also, its function is evaluated by MentorTM. Even though the hardware complexity is somewhat increased, the throughput rate is improved about twofold.

• Proceedings of the Korea Society for Simulation Conference
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• 1994.10a
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• pp.7-8
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• 1994

최근 들어 원자재, 재공품 또는 완제품을 신속하고 정확하게 공급/배분하기 위해 저장과 인출을 담당하는 Material Handling System을 이용하여 작업자의 개입요소를 줄이며, 제고관리 Computer를 이용하여 입고/출고 명령을 유효적절하게 처리하는 ASRS(Atomated Storage and Retreival System : 자동창고 시스템)가 널리 공급되고 있다. 중앙은행의 현금창고, 병원의 약품창고, 식품/화장품 회사의 배송창고, 군수물자의 군납창고에 이르기까지 물품의 저장 또는 공급의 필용성을 갖는 곳에서는 어디든지 찾아볼 수 있는 ASRS는 가깝게는 관공소나 대형빌딩의 주차장에도 이의 개념이 도입되어 사용됨을 볼 수 있다. 최근의 인금인상, 구인난등의 이유로 ASRS설치는 계속 증가할 추세에 있으나 자동 창고 시스템을 설치하기 위해서는 막대한 초기 투자가 필요하며 시스템의 설계 및 설치후 운영에 대한 연구가 반드시 필요하다. ASRS의 운영 Rule 검증, 수행능력 분석등의 목적을 갖는 연구에는 여러 접근방법이 있을 수 있으나 구성 설비와 운영 Rule의 복잡한 관계로 컴퓨터 시뮬레이션의 거의 유일한 문제해결 방법이다. ASRS의 Modeling에 관한 기존의 연구로는 수리모델 수립. 이산사건 시스템의 관점에서 event-graphy, petri-net을 이용한 modeling이 있으며 ASRS에 대한 전용 Simulator 개발등이 진행되었다. 본 연구의 대상 시스템은 2개의 Rack과 하나의 Stacker Crane 으로 구성된 Aisle과 입출고의 물류를 처리하는 순환 RGVS(Rail Guided Vehicle System), 입/출고장을 구성하는 Conveyor Net등으로 이루어진 제조-물류시스템의 일반적인 ASRS이다. 또 이 ASRS의 입/출고 방식은 전수 입/출고만을 포함하며 Blocking 방지를 위한 Capaicty 예약, 다중설비 선택등의 문제등을 고려하고 있다. 본 연구의 접근방법으로는 ASRS의 개념적인 Reference Model을 수립하고 이 Reference Model에 대한 Formal Model로 DEVS(Discrete Event System Specification)을 이용하여 시스템을 Modeling하였다. 이의 Computer Simulation을 위하여 DEVS형식론 환경에서의 Simulation Language인 DEVSim ++ⓒ를 이용하여 시스템을 구현하였다.