• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.2
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• pp.157-164
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• 2017

A parallel slide gate valve (PSGV) is located between the heat recovery steam generator (HRSG) and the steam turbine in a combined cycle power plant (CCPP). It is used to control the flow of steam and runs with repetitive operations such as startups, load changes, and shutdowns during its operation period. Therefore, it is necessary to evaluate the fatigue damage and the structural integrity under a large compressive thermal stress due to the temperature difference through the valve wall thickness during the startup operations. In this paper, the thermal-structural analysis and the fatigue life evaluation of a 16-inch PSGV, which is installed on the HP steam line, is performed according to the fatigue life assessment method described in the ASME B&PVC VIII-2; the method uses the equivalent stress from the elastic stress analysis.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.9
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• pp.923-932
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• 2011

Because of the instability of a flow pattern in the inlet transition square duct (hereinafter referred to as "transition duct") of a heat recovery steam generator (hereinafter referred to as "HRSG") in a combined cycle power plant, the Reynolds number in the first row of a tube bank is differs sharply from that in the sectional area of the transition duct. This causes differences in the heat flux in each tube in the tube bank. The computational fluid dynamics (CFD) predictions provide three-dimensional results for velocity, temperature, and other flow parameters over the entire domain of the duct and HRSG. A renormalization group theory (RNG) based k-${\epsilon}$�� turbulent model is used for obtaining the results cited in this study. A porous media option is used for modeling the tube banks and the number of transfer units method is used for determining the heat transfer characteristics. This study describes a comparison between the numerical simulation results and actual design output.

• Proceedings of the SAREK Conference
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• 2007.06a
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• pp.200-200
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• 2007

• Proceedings of the SAREK Conference
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• 2003.07a
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• pp.39-39
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• 2003

• Journal of KIISE:Computer Systems and Theory
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• v.27 no.11
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• pp.881-889
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• 2000

프로그램의 실행시간은 캐쉬메모리의 효율적 사용과 밀접한 관계가 있다. 특히 간섭 실패는 프로그램의 성능에 큰 영향을 미치지만 나타나는 형태가 불규칙적이므로 예측하기가 매우 어렵다. 본 논문에서는 직접 사상 캐쉬전략을 사용한 완전 중첩 루프 내 배열의 캐쉬 실패율(cache miss ratio)을 구하는 분석적 모델을 제시한다. 논문에서 제시한 모델을 임의의 캐쉬 위치에 각 배열이 접근한 시간을 기반으로 다음주기에서 캐쉬 실패의 발생 여부를 예측하는데, 간섭으로 발생한 캐쉬 실패 개수에 대해 기존에 제시된 모델보다 더 빠르고 정확한 예측이 가능하다. 특히, 한문장의 수행시간 예측시간은 배열의 크기와 독립적이기 때문에, 전체 프로그램의 수행시간 예측은 배열의 크기 및 문장의 반복 회수 배만큼 빠른 결과를 보여준다. 본 모델은 프로그램의 성능예측 뿐만 아니라 데이터 지역성의 최적화, 캐쉬 구성, 스케쥴링 등에서도 이용 가능하다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.8
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• pp.44-54
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• 2018

Stress and fatigue of the distributor, an equipment of the high-pressure evaporator for the HRSG, were evaluated according to ASME Boiler & Pressure Vessel Code Section VIII Division 2. First, from the results of the piping system analysis model, reaction forces of the tubes connected to the distributor were derived and used as the nozzle load applied to the detailed analysis model of the distributor afterward. Next, the detailed model to analyze the distributor was constructed, the distributor being statically analyzed for the design condition with the steam pressure and the nozzle load. As a result, the maximum stress occurred at the bore of the horizontal nozzle, and the primary membrane stress at the shell and nozzle was found to be less than the allowable. Next, for the transient operating conditions given for the distributor, thermal analysis was performed and the structural analysis was carried out with the steam pressure, nozzle load, and thermal load. Under the transient conditions, the maximum stress occurred at the vertical downcomer nozzle, and of which fatigue life was evaluated. As a result, the cumulative usage factor was less than the allowable and hence the distributor was found to be safe from fatigue failure.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1812-1813
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• 2011

• The Magazine for Energy Service Companies
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• s.28
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• pp.34-47
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• 2004

열병합 발전시스템의 경우 전력과 열을 균형있게 사용하고 배열의 유효이용을 극대화하여 에너지 절약을 실천함으로서 초기투자비용을 빠른 기간 내에 회수할 수 있도록 시스템 선정의 신중한 계획 및 검토가 요구되며 이에 따른 정량적인 경제성의 추산을 실시하여야한다.

• Journal of Advanced Marine Engineering and Technology
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• v.29 no.6
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• pp.685-691
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• 2005

In this study, high performance waste heat recovery heat exchanger was developed using the bayonet tube with spiral serrated fins. Especially, heat exchanger of the bayonet tube type was operated well because of double water passes mechanism and characteristics. A cooling water Passes down inner tubes to thimble-form tubes, then flows back up as it boils. The heat exchanger of bayonet tube type was composed of steel tube with 7channels$(I.D_1\;14mm.\;I.D_2\;31.6mm)$ and spiral serrated fins. The performance tests were conducted under the following conditions A cooling water flow rate was 273kg/h and engine l·pm was varied from 750rpm to 3500 rpm. From the experimental result. waste heat recovery was 9.21kW when engine rpm was 3500. and pressure drop was $15\~260mmHg/m^3$ The effectiveness of heat exchanger was about /$0.7\~0.9$. The performance of heat exchanger was evaluated by using the $\varepsilon-NTU$ method. In the study the NTU of the heat exchanger was $1.57\~2.33$.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.4
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• pp.150-159
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• 2018

The present research deals with a finite element analysis and fatigue evaluation of a steam separator of a high-pressure evaporator for the Heat Recovery Steam Generator (HRSG). The fatigue during the expected life of the HRSG was evaluated according to the ASME Boiler and Pressure Vessel Code Section VIII Division 2 (ASME Code). First, based on the eight transient operating conditions prescribed for the HRSG, temperature distribution of the steam separator was analyzed by a transient thermal analysis. Results of the thermal analysis were used as a thermal load for the structural analysis and used to determine the mean cycle temperature. Next, a structural analysis for the transient conditions was carried out with the thermal load, steam pressure, and nozzle load. The maximum stress location was found to be the riser nozzle bore, and hence fatigue was evaluated at that location, as per ASME Code. As a result, the cumulative usage factor was calculated as 0.00072 (much less than 1). In conclusion, the steam separator was found to be safe from fatigue failure during the expected life.