• Journal of Advanced Marine Engineering and Technology
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• 제18권4호
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• pp.13-24
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• 1994

The demand of clean energy, like liquefied gas(LNG), increase suddenly because it generates few polluting substances when burned and from the point of view with caloric value it generates ralatively less $CO_2$ gas than the other energy sources. LNG transpotion method of our country is marine transportion by ships because the LNG producing district is far away from Korea. Main engines for most LNG ships are steam turbines, and the efficiency of steam turbine is influenced by the degree of vacuum of main steam condenser. This paper introduce the design method of the vacuum system for high efficiency marine steam turbine. Especially, it is developed the CAD program for the large steam condenser and steam ejector. Also, it is designed the pilot plant including high pressure boiler for the performance test and maked a part of this plant.

• 한국전산유체공학회지
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• 제20권3호
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• pp.87-93
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• 2015

In this study, a numerical analysis was performed to simulate the thermal-hydraulic response of the secondary side of a steam generator(SG) model equipped with an orifice-type SG outlet flow restrictor to a main steam line break(MSLB) at a pressurized water reactor(PWR) plant. The SG analysis model includes the SG upper steam space and the part of the main steam pipe between the SG outlet and the broken pipe end. By comparing the numerical calculation results for the present SG model to those obtained for a simple SG model having no flow restrictor, the effects of the flow restrictor on the thermal-hydraulic response of SG to the MSLB were investigated.

• 한국가스학회지
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• 제17권2호
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• pp.70-77
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• 2013

본 연구는 화력발전소 최종과열기에서 고압터빈 사이 배관과 고압터빈을 지난 곳에 있는 체크밸브와 1차 재열기 사이 배관을 포함한 수증기 배관시스템에서 터빈의 급작스런 사고로 인해 터빈으로 들어가는 수증기를 차단할 때 발생하는 수증기 충격이 배관시스템에 미치는 영향을 분석하는 연구이다. 이를 위해서 수격현상 해석에 많이 사용하는 Flowmaster 소프트웨어로 배관시스템을 모델링하고 시간 변화에 따라 배관 내부의 압력, 질량유량률의 특성을 파악하였다. 이러한 특성으로부터 수증기 충격이 주로 영향을 미치는 곡관에서 수증기 충격에 의한 힘을 도출하였다. 본 연구를 통해서 수증기 충격은 주증기 차단 밸브 직전의 곡관과 체크밸브 이후에 바이패스 배관과 연결되는 곡관에서 수증기 충격에 의한 힘이 가장 크게 나타남을 밝혀냈다. 본 연구에서는 이렇게 도출한 힘의 기본 자료를 이용하여 차후 연구에서 화력발전소 수증기 배관시스템의 수증기 충격 시 곡관과 지지대의 안전성을 진단하는 토대를 구축하였다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2002년도 ICCAS
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• pp.70.2-70
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• 2002

In the thermal power plant, it is difficult to maintain strict control of the steam temperature in order to avoid thermal stress, because of variation of the heating value according to the fuel source, the time delay of changes in main steam temperature versus changes in fuel flow rate, difficulty of control on the main steam temperature control and the reheater steam temperature control system owing to the dynamic response characteristics of changes in steam temperature and the reheater steam temperature, fluctuation of inner fluid water and steam flow rates widely during load-following operation. Up to the present time, the PID controller has been used to operate this system...

• KIEE International Transaction on Systems and Control
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• 제2D권2호
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• pp.78-91
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• 2002

In the thermal power plant, there are six manipulated variables: main steam flow, feedwater flow, fuel flow, air flow, spray flow, and gas recirculation flow. There are five controlled variables: generator output, main steam pressure, main steam temperature, exhaust gas density, and reheater steam temperature. Therefore, the thermal power plant control system is a multinput and output system. In the control system, the main steam temperature is typically regulated by the fuel flow rate and the spray flow rate, and the reheater steam temperature is regulated by the gas recirculation flow rate. However, strict control of the steam temperature must be maintained to avoid thermal stress. Maintaining the steam temperature can be difficult due to heating value variation to the fuel source, time delay changes in the main steam temperature versus changes in fuel flow rate, difficulty of control of the main steam temperature control and the reheater steam temperature control system owing to the dynamic response characteristics of changes in steam temperature and the reheater steam temperature, and the fluctuation of inner fluid water and steam flow rates during the load-following operation. Up to the present time, the Proportional-Integral-Derivative Controller has been used to operate this system. However, it is very difficult to achieve an optimal PID gain with no experience, since the gain of the PID controller has to be manually tuned by trial and error. This paper focuses on the characteristic comparison of the PID controller and the modified 2-DOF PID Controller (Two-Degrees-Freedom Proportional-Integral-Derivative) on the DCS (Distributed Control System). The method is to design an optimal controller that can be operated on the thermal generating plant in Seoul, Korea. The modified 2-DOF PID controller is designed to enable parameters to fit into the thermal plant during disturbances. To attain an optimal control method, transfer function and operating data from start-up, running, and stop procedures of the thermal plant have been acquired. Through this research, the stable range of a 2-DOF parameter for only this system could be found for the start-up procedure and this parameter could be used for the tuning problem. Also, this paper addressed whether an intelligent tuning method based on immune network algorithms can be used effectively in tuning these controllers.

• Journal of Advanced Marine Engineering and Technology
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• 제22권6호
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• pp.854-861
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• 1998

The demand of LNG as a cheap and clean energy which does not cause an environmental problem has sharply been increased in Korea. In general LNG is stored in a cargo tank specially designed as a liquid state below $-162^{\circ}C$. The main engine of a LNG carrier is generally a steam boiler because LNG is a highly flammable fluid with the possibility of explosion. The main engine of a cargo ship has to be capable of the propulsion load and various auxiliary loads for the safe navigation since it is the primary energy source. Therefore the evaluation of a main boiler's energy capacity is a key design point in the planning of LNG carrier's construction. This research is to develop the computational program for the analysis of steam boiler Heat balance for LNG carrier.

• 한국압력기기공학회 논문집
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• 제7권3호
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• pp.40-47
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• 2011

KSNPs(Korea Standard Nuclear Power Plant) have been applied the break exclusion criteria to the high energy lines passing through containment penetration area to ensure that piping failures would not cause the loss of containment isolation function, and to reduce the resulting dynamic effects. Systems with the criteria are the Main Steam system, Feed Water system, Steam Generator Blowdown system, and Chemical & Volume Control system. In accordance with FSAR(Final Safety Analysis Report), a 100% volumetric examination by augmented in-service inspection of all pipe welds appled the break exclusion criteria is required for the break exclusion application piping. However, it is difficult to fully satisfy the requirements of inspection because 12", 8" and 6" weldolet weldments of Main Steam pipe line have complex structural shapes. To resolve the difficulty on the application of conventional UT(Ultrasonic Testing) technique, realistic mock-ups and UT calibration blocks were made. Simulations of conventional UT were performed utilizing CIVA, a commercial NDE(Nondestructive Examination) simulation software. Phased array UT experiments were performed through mock-up including artificial notch type flaws. A phased array UT technique is finally developed to improve the reliability of ultrasonic test at main steam line pipe to 12", 8" and 6" branch connection weld.

• 한국압력기기공학회 논문집
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• 제11권1호
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• pp.74-78
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• 2015

Nuclear power plant steam generator that is one of the main component has several thousands of thin tubes. And the steam generator tube is subject to damage because of the severe operation conditions such as the high temperature and pressure. Therefore periodic inspections are conducted to ensure the integrity of steam generator component. Hanul unit 3 also has been inspected in accordance with in-service inspection program and is scheduled to be replaced for exceeding the plugging rate which was recommended by manufacturer. During the steam generator replacement activity, we found several clustered porosity on inner surface of main feed water pipe. Additionally crack-like indications were found at weld interface between base material and weld of main feed water pipe. This paper describes the field experience and visual testing results for inner surface of main feed water pipes. The destructive test result had shown that these indications were porosities which were caused by manufacturing process not by operation service.

• 동력기계공학회지
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• 제7권3호
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• pp.23-28
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• 2003

In heavy nuclear power plant, high energy through main steam line is provided to turbine that generate the electric power. Since plant had generated power, high noise has been occurred. Noise make equipments and work environment worse. For finding out the location and the cause of making noise, noise was measured along main steam line at open/close test of Main Steam Isolation Valve (MSIV hereafter). As the result, it was identified that the vortex shedding in the cavity of MSIV is main noise source. The profile change of MSIV seat ring was proposed as the method of noise reduction. After filletting MSIV seat ring, the noise level reduced $10{\sim}20dB$ compared before the change of profile.

• 대한수학교육학회지:수학교육학연구
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• 제24권3호
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• pp.429-442
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• 2014

본 연구에서는 최근 우리나라에서 논의되고 있는 STEAM 교육에 대하여 등장 배경, 주요 주장, 교육 방안 등을 살펴보고, 수학교육학의 관점에서 STEAM 교육을 분석하고자 하였다. STEAM 교육에서 기본적으로 가정하는 창의, 소통, 내용융합, 배려라는 네 가지 핵심 역량 중 다른 것과 달리 내용융합에 대한 근거는 매우 미약하며, STEAM 교육의 주요 원리는 그 동안 수학교육학이나 창의성 교육과 관련하여 논의되어 온 것에 상당히 유사함을 알아보았다. 결론적으로 STEAM 교육을 너무 급진적으로 추구하는 것은 조심스러우며, 기존에 수학교육학 분야나 창의성 교육과 관련된 논의를 고려하여 보다 많은 기초 연구가 필요함을 주장하였다.