• Nuclear Engineering and Technology
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• 제51권4호
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• pp.1008-1016
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• 2019

In the SG (steam generator) of PWR (pressurized water reactor) for a nuclear plant, hundreds of U-shaped tubes are used for the heat exchanger system. They interact with primary pressurized cooling water flow, generating flow-induced vibration in the secondary flow region. A simplified U-tube model is proposed in this study to apply for experiment and its counterpart computation. Using the commercial code, ANSYS-CFX, we first verified the Moody chart, comparing the straight pipe theory with the results derived from CFD (computational fluid dynamics) analysis. Considering the virtual mass of fluid, we computed the major modes with the low natural frequencies through the comparison with impact hammer test, and then investigated the effect of pump flow in the frequency domain using FFT (fast Fourier transform) analysis of the experimental data. Using two-way fluid-structure interaction module in the CFD code, we studied the influence on mean flow rate to generate the displacement data. A feasible CFD method has been setup in this research that could be applied potentially in the field of nuclear thermal-hydraulics.

• 한국산림과학회지
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• 제97권3호
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• pp.274-284
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• 2008

입목자산의 경제적 가치를 평가하기 위해서는 벌채수확을 비롯하여 조림 육림 등과 관련된 많은 투입요소들이 고려되어야만 한다. 특히 임가경제조사를 통한 입목자산가치의 평가를 위해서는 이러한 투입요소들을 지역별/수종별로 표준화하는 것이 요구되며, 따라서 좀더 효율적인 입목자산가치의 평가를 위해서는 각 투입요소들의 조사방법 및 표준화 기준 등을 구체화할 필요가 있다. 또한 지역별/수종별로 표준화된 투입요소들을 이용하여 실제로 입목자산의 가치를 산정하는 방법 및 절차에 대해서도 구체적인 지침을 마련할 필요가 있다. 따라서 본 연구에서는 기존의 평가사례 및 연구문헌들을 토대로 투입요소들의 표준화를 위한 합리적인 대안을 제시하고, 표준화된 투입요소를 이용하여 실제로 입목자산을 평가하는 세부적인 업무내용 및 절차 등을 분석하였다. 분석된 결과들은 네 단계의 자료유형, 즉 시스템 흐름도(system flow chart), 프로세스 흐름도(process flow chart), 상세 흐름도(detail flow chart), 스키머 데이터(skimmer data)의 형태로 제시되었으며, 이러한 분석결과를 토대로 '입목자산가치 평가표'를 산출할 수 있는 프로그램(EnVAST)을 개발하여 임가경제조사에 활용할 수 있도록 하였다.

• Nuclear Engineering and Technology
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• 제32권6호
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• pp.618-635
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• 2000

A total of 17 experimental data for the onset of slugging, which is assumed to be the precursor of the condensation-induced waterhammer (CIWH), have been obtained for various How rates of water Incorporating the most recent correlations of interfacial heat transfer and friction factor developed for a circular geometry and using an improved criterion of transition from stratified to a slug flow, two existing analytical models to predict lower and upper bounds for CIWH have been upgraded. Applicability of the present as well as existing CIWH models has been tested by comparison with two sets of CIWH data. The result of this comparison shows that the applicability of the present as well as existing models is reasonably good. Based on the present models for CIWH, a computer code entitled as“KAIST-CIWH”has been developed and sample guide charts to find CIWH free regions for a given combination of major flow parameters in a long horizontal pipe have been presented along with the results of parametric studies of major parameters (D, P, $T_{f,in}$, and L/D) on the critical inlet water flow rate（$W_{f,in}_crit$ for both lower and upper bounds. In addition, two simple formulas for lower and upper bounds that can be used in an emergency for quick results have been presented.

• 전기학회논문지
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• 제56권8호
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• pp.1373-1381
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• 2007

This paper presents a graphical windows-based software for the education and training of transmission network charge. The motivation for the development of the simulator is to provide students with a simple and useable tool for gaining an intuitive feel for transmission network charge. The developed simulator consists of the main module (MMI, GUI), the power flow module (PF), the power flow tracing module (PFT), and usage cost DB module (UCD). Each module has a separate graphical and interactive interfacing window. The developed simulator provides with two power system analysis methods (i.e., DC-PF and Modified DC-PF) and supports the PSS/E input data format to load input data of power system. Also, power flow tracing can be calculate using four methods such as "Felix Wu", "Modified Felix Wu", "DCLF ICRP", and "Reverse MW mile". Results of calculation for transmission usage cost are displayed and compared on the window through the table and/or chart. Therefore, the developed simulator can be utilize as a useful tool for effective education and training of transmission network charge.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.1362-1366
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• 2003

Workload programming is allocating suitable workloads of production process according to the needs of products, which would minimize the total cost of both work and stock under some constraint conditions. In this paper, a production process flow chart of discrete manufacturing is presented by a Petri net, and the optimization model of workload-stock is established. An approach of the optimal workloads is provided by means of the integer matrix theory. An example is given to verify this method.

• 대한안전경영과학회지
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• 제8권6호
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• pp.149-157
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• 2006

This paper suggests the design and operation of value stream mapping(VSM) applied to project management, such as R&D, IT Investment. First this study represents design methodology of VSM process using SIPOC(Supplier, Input, Process, Output, Costumer). Second, this paper considers the identification and improvement plan about non-added value time for VSM using FPC(Flow Process Chart) and PERT/CPM. Last, this paper proposes VSM scheduling method using PERT/CPM and CCPM(Critical Chain Project Management)

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1989년도 가을 학술발표회 논문집
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• pp.39-42
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• 1989

This paper suggests a systematic procedure for maintenance of reinforced concrete (R/C) structures. In this paper the deteriorations of R/C structures are classified by eleven causes and diagonistic techniques are devided into six major steps. The suggested diagonisis steps are summarized in the flow chart and it would be helpful to develop the expert system for maintenance of R/C structures.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 B
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• pp.1064-1066
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• 2001

In this paper, the harmonic components generated by those two sources are analyzed separately based on the transfer function and shown as the closed form considering the switching frequency, speed of the control processor, gain of the controller, and the inductor and capacitor value of L-C filter. A design procedure is described with one flow chart and explained step by step.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년 학술대회 논문집 정보 및 제어부문
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• pp.273-275
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• 2006

Ladder Diagram(LD) is the most widely utilized among many sorts of existing programs using for the design of process control system. But it is very difficult to grasp sequential flow of control logic. In this paper, we proposed the method that we can control a lot of blocks. We used PLC in process control system. And, in order to design we used Sequential Function Chart(SFC). In this paper, we proposed the method of block contro. and confirmed feasibility through a simulation.

• 대한치과의사협회지
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• 제54권4호
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• pp.252-257
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• 2016

This manuscript aims at discussing the technical and biological aspects of peri-implant disease. The following contents will be discussed. -The difference between peri-implantitis and peri-implant mucositis. -Prevalence of peri-implant disease. -Risk factors for peri-implantitis. -Indications and boundaries of non-surgical and surgical treatment -Treatment flow-chart by Schwarz -Limitations of non-surgical treatment -Methods to decontaminate diseased surfaces -Importance of defect configuration in surgical treatment -Biomechanical factors that influence the progression and decontamination related to peri-implantitis -Maintenance of implants.