• 드라이브 ㆍ 컨트롤
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• 제18권4호
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• pp.28-34
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• 2021

Among the currently available types of fuel, LNG emits a relatively small amount of nitrogen oxide and carbon dioxide when it burns in the engine. However, since LNG is a flammable material, leakage during bunkering can lead to accidents, such as fires. Therefore, it is necessary to install a remote operation emergency shut-down (ESD) valve to block the flow and leakage of LNG in an emergency situation that occurs during bunkering. The ESD valve uses a hydraulic driving device consisting of a hydraulic control valve and a hydraulic motor to control globe valve disc displacement, which regulates the flow path for LNG transfer. At this time, there are various nonlinearities in hydraulic driving devices; hence, it is necessary to design a controller with robust control performance against these uncertainties. In this study, modeling of the ESD valve was carried out, and a sliding mode controller to control the displacement of the globe valve disc was designed. As a result, it was confirmed that the designed control performance could be achieved by overcoming nonlinearity characteristics using the designed controller.

• 한국소음진동공학회논문집
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• 제19권8호
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• pp.843-849
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• 2009

The reliable operation of a swing check valve in the main feed water system of a power plant is most essential for successful shout-down process. A failure to close the valve at proper time often leads to the instability of the main feed water system, or even to an emergency stop of the power plant. In reality it is a very difficult task to monitor the behavior of a swing check valve. Furthermore it is impossible to see the motion of the valve. In this work two measurements were carried out simultaneously to determine the precise valve closure time. The dynamic pressure measurements were made at the inlet and outlet regions of the swing check valve. The transient vibration of the valve housing in the direction of water flow was also measured, which enabled the measurement of the transient vibration of the valve housing near valve closure. By comparing the results produced from these measurements the precise valve closure time could be determined. By carrying out order tracking technique using the dynamic pressure signals and pump rpm signal, the complicated dynamic problems inside the main feed water system can be more easily dealt with. This measurement scheme might be implemented in a power plant on a real-time basis without much difficulty. If this could be implemented, valuable information essential for shut-down operations can readily be passed on to the main control room. The feasibility of this implementation was demonstrated by this experimental work.

• Journal of Biosystems Engineering
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• 제22권4호
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• pp.439-450
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• 1997

Most of Korean feed mill has a pregrind system which was suitable for the processing of less number of ingredients and finished products, and good for the mash type feed product. But industries has been changed in production volume and cost, and also from mash to further processed products such as pelleted and extruded. Therefore, Korea feed industries now should change the process, especially the grinding system from the current pregrind to other grind system, but this change will cost a lot of investment and also loosing current grinding system, and should have production shut down during the construction period. To solve these problems, combined grinding system based on a new model mill has been developed. The combined grind system is combination of pregrind and postgrind system, which has the advantages of those two grind systems, and also which can allow to utilize existing pregrind system continuously without any production interruption due to new postgrind system construction. This newly developed model has been applied to the feed mill expansion project of `B`feed company in 1994, and it was very successful application and showed excellent results as we intended. The new model mill, combined grind system applied can save fixed asset investment because old pregrind system can be used as is, and also can reduce production cost and improve product quality. And the possibility of critical production shut down can be much lowered. Within this new grinding model development, multi-screen combination system has been developed for the better grinding texture quality and safer operation. This new model mill with combined grind system will be applied by most feed manufacturing plant and may enhance their production competitiveness, and the further study and development should be continued.

• 한국화재소방학회논문지
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• 제26권3호
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• pp.29-34
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• 2012

본 논문에서는 소방전원 및 소방전원 부족시 용량 보완을 위한 인터록 시스템의 한계점 등을 분석하고 소방전원 보존형 발전기(RFP)의 작동방법 등을 제시하여 화재와 같은 상황에 효율적으로 대응할 수 있는 방법을 제시하는데 있다. 소방전원보존형 발전기에서 일괄제어방식은 발전기에 과부하가 걸리면 소방전원보존용 제어기에서 신호를 발신하여 소방부하는 남겨두고 비상부하용 주차단기를 일괄 차단하고, 발전기가 마지막까지 소방부하에 전원이 공급되도록 한 시스템이다. 순차제어방식은 과부하가 걸리면 소방전원보존용 제어기에서 1차 신호를 발신하여 설정된 비상부하의 1단계 부하를 차단한다. 그리고 지속적인 감시 상태에서 소방부하가 증가하여 발전기가 다시 과부하가 걸리면 제어기에서 2차 신호가 발신하여 비상부하의 2단계 부하를 차단하는 시스템이며 각각의 작동 상태를 표시하는 표시장치를 가진다.

• 한국화재소방학회:학술대회논문집
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• 한국화재소방학회 2003년도 춘계학술논문발표회논문집
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• pp.259-264
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• 2003

The fire protection system of Nuclear Power Plants(NPPs) is an integrated system that is applied multi-field technology. So, it needs synthetic design and analysis, that is, the plan of fire protection, fire compartment, fire detection, fire suppression, and success of safety shut down, etc. In case of a fire in NPPs, secure the safety of reactor and minimize the radioactivity contamination. For this purpose, perform the fire risk analysis and make up the deducted problem through the improvement of design or the change of operation process.

• 대한안전경영과학회지
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• 제19권4호
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• pp.35-42
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• 2017

A number of plating companies have been exposed to the risk of fire due to unexpected temperature increasing of water or other reasons in a plating bath. Since the companies are not able to forecast the unexpected temperature increasing of plating bath and most of raw materials in the bath have low ignition temperature, it is easy to be exposed to the risk of fire. Thus, in previous study, we tried to monitor and notice the dangerous change of temperature of water immediately to prevent the risk of fire from plating process. However, unfortunately previous studies were not able to shut out the fundamental cause of fire since bath temperature sensor can detect air temperature when the level sensor was malfunctioned. In this paper we developed the Teflon heater which contains a built in temperature sensor and improved plating equipment system. Teflon heater is improved using Pt $100{\Omega}$ sensor which can detect until $600^{\circ}C$. When the bath temperature sensor detects over $60^{\circ}C$ or the Teflon heater sensor detects over $240^{\circ}C$ they temporarily shut down the heater to control temperature. Also relay completely shuts down main power when detects instant temperature is detected over 5% of $240^{\circ}C$ by the heater sensor to prevent teflon melting down and fire spreads. Developed plating equipment system can monitor a real time temperature in the teflon tube and bath water. Therefore we think the proposed plating equipment can eliminate the possibility of fire in plating processes fundamentally.

• 한국정밀공학회지
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• 제15권9호
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• pp.25-32
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• 1998

The forced cooling system is designed to shorten the overhaul time of steam turbine, which is important in view of economic concern of utility companies, Forced cooling of the hot turbine is achieved by suction of air flow into the turbine after the turbine shuts down. The heat transfer process by suction of air flow can cause thermal stress due to the thermal gradients. In this paper, the analysis of heat transfer is performed to calculate the air flow rate. Based on the prediction of cyclic fatigue damage and the experience, the cooling equipment is designed for shortening the cooling time of steam turbine.

• 한국산학기술학회논문지
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• 제19권9호
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• pp.526-535
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• 2018

최근, 도서지역에서는 $CO_2$ 배출의 저감을 위하여, 디젤발전기의 가동률을 줄이고 신재생에너지전원의 비중을 높여, 계통을 안정적으로 운용할 수 있는 방안들이 연구되고 있다. 특히, Carbon free를 목표로 하는 도서지역용 Micro-grid에서는 CVCF(constant voltage & constant frequency) 인버터를 기반으로 운용되는데, CVCF 인버터용 배터리의 SOC(state of charge) 상태에 따라, 계통의 부하소비 보다 신재생에너지전원의 출력이 큰 경우에 CVCF 인버터 내에서 발생하는 에너지 Sinking에 의하여, 배터리측 전압이 급격히 상승하여, 인버터의 과전압 보호동작에 의해 CVCF 인버터가 급격하게 탈락되어 계통에 정전이 발생하는 문제점이 일어날 수 있다. 따라서, 본 논문에서는 CVCF 인버터를 기반으로 한 도서지역용 Micro-grid의 안정적인 운용을 위하여, 에너지 Sinking 시에 발생 가능한 CVCF 인버터의 탈락을 사전에 방지하는 과도상태 운용알고리즘을 제안한다. 또한, PSCAD/EMTDC의 모델링을 이용하여, 제안한 알고리즘을 적용한 Micro-grid의 과도상태 운용특성을 분석한 결과, 배터리의 전압과 SOC에 따라 CVCF 인버터가 탈락하는 과도상태를 사전에 방지할 수 있어, 본 논문의 유용성을 확인하였다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.1198-1205
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• 2003

Most domestic fossil power plant have exceeded 100,000 hours of operation with the severe operating condition. Among the critical components of fossil power plant, high temperature steam pipe system have had a many problems and damage from unstable displacement behavior because of frequent start up and shut down. In order to prevent the serious damage and failure of the critical pipe system in fossil power plant, 3-dimensional displacement measurement system were developed for the on-line monitoring system. 3-D Measurement system was developed with using the LVDT type sensor and rotary encoder type sensor, this system was installed and operated on the real power plant successfully. In the future time, network system of on-line diagnosis for critical pipe will be designed.

• 대한임베디드공학회논문지
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• 제9권3호
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• pp.173-182
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• 2014

The CRT monitor display system for SONAR signal that are commonly used in ships or naval vessels uses vector scanning method. Therefore the processing circuits of the system are complex. Also the purchase of parts is difficult as well as high-cost because the production had been shut down. FPGA-based embedded system is flexible to various digital applications because it can be able to simplify processing circuits and to make a easy customized design for end user, and it provides low-cost high-speed performance. In this paper, we describe an implementation of FPGA embedded system for real-time SONAR signal display using the triple buffering method to overcome some weakness of existing CRT system. Our system provides real-time acquisition and display capability of SONAR signal, and removes afterimage effect that is a critical problem of the system proposed in the preceding study.