• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2017년도 제48회 춘계학술대회논문집
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• pp.1006-1010
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• 2017

본 논문은 발사체의 지상대기 및 운용 중 격실 내부의 열제어 및 화재/폭발 방지를 위해서 적용되는 열제어/화재안전계에 대한 설계 및 시험에 대해서 기술한다. 고려된 시스템은 한국형발사체 개발의 일환으로 진행되고 있는 시험발사체의 열제어/화재안전 시스템으로 이 시스템은 나로호의 경험을 토대로 고압 시스템을 적용한다. 고압 및 저압 시스템의 선정은 발사대의 가스공급 설비 및 발사체의 특성을 고려해서 선정하며 이에 따라 시스템의 구성도 달라진다. 결과적으로 개발된 시스템은 시험을 통해서 초기의 설계 조건을 만족하는 결과를 얻을 수 있음이 확인되었으며, 이러한 시스템은 한국형발사체의 개발에 그대로 확장되어 적용될 예정이다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.1201-1204
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• 2004

This paper suggests a DCS (Distributed Control System) model for steam temperature system of the thermal power plant. The model calculated within sectional range is linear. In order to calculate mathematical models, the system is partitioned into two or three sectors according to its thermal conditions, that is, saturated water/steam and superheating state. It is divided into three sections; water supply, steam generation and steam heating loop. The steam heating loop is called 'superheater' or steam temperature system. Water spray supply is the control input. A first order linear model is extracted. For linear approach, sectional linearization is achieved. Modeling methodology is a decomposition-synthetic technique. Superheater is composed of several tube-blocks. For this block, linear input-output model is to be calculated. Each tiny model has its transfer function. By expanding these block models to total system, synthetic DCS linear models are derived. Control instrument include/exclude models are also considered. The resultant models include thermal combustion conditions, and applicable to practical plant engineering field.

• 설비공학논문집
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• 제29권11호
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• pp.592-604
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• 2017

A chiller, having a thermal storage system, can contribute to load-leveling and can reduce the cost of electricity by using electricity at night. In this study, the control experiments and simulations are conducted using both conventional and advanced methods for the building cooling system. Advanced approaches, such as the "region control method", divide the control region into five zones according to the size of the building load, and determines the cooling capacities of the chiller and thermal storage. On the other hand, the "dynamic programming method" obtains the optimal cooling capacities of the chiller and thermal storage by selecting the minimum-cost path by carrying out repetitive calculations. The "thermal storage priority method" shows an inferior chiller performance owing to the low-part load operation, whereas the chiller priority method leads to a high electric cost owing to the low utilization of thermal storage and electricity at night. It has been proven that the advanced control methods have advantages over the conventional methods in terms of electricity consumption, as well as cost-effectiveness. According to the simulation results during the winter season, the electric cost when using the dynamic programming method was 6.5% and 8.9% lower than that of the chiller priority and the thermal storage priority methods, respectively. It is therefore concluded that the cost of electricity utilizing the region control method is comparable to that of the dynamic programming method.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1989년도 한국자동제어학술회의논문집; Seoul, Korea; 27-28 Oct. 1989
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• pp.567-571
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• 1989

This paper describes the improvement of thermal power plant turbine control system by analyzing nonlinear characteristics. The turbine control depends on the frequency variation and boiler condition. The nonlinearity of turbine control is the result of governor/valve properties, steam condition and boiler thermal unbalance. Nonlinear analysis is divided into two; main steam valve position - turbine output anal governor response. Of course, every analysis must be done on considering plant operating condition. In this paper, after analyzing turbine control nonlinearity by numerical method and actual results, the sensitive operating load which corresponds to frequency is proposed, on guarranteed boiler stability. This idea is implemented at Pyung Tack thermal power plant, and the practical results are showed.

• 전기전자학회논문지
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• 제18권3호
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• pp.409-419
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• 2014

본 논문에서는 온열치료기의 온도제어 알고리즘 및 시스템을 구현하였다. PWM(Pulse Width Modulation) 파형의 온 타임 펄스폭을 제어함으로서 온열치료기의 마사지 기능에 적합한 온열요법이 내장된 안정된 온도제어를 구현 할 수 있었으며 의료기기의 온열마사지, 온열지압, 온열 뜸 기능에 적용 하였다. 온도설정 범위는 $40^{\circ}C$에서 $70^{\circ}C$까지이며 $5^{\circ}C$ 단위로 설정하였고 제어량은 실시간으로 $1^{\circ}C$ 단위로 제어하였으며 $1^{\circ}C$ 간격으로 온도를 표시하였다. 제어범위는 설정온도와 현재온도의 차가 $4^{\circ}C$이하부터 4단계로 PWM 펄스폭을 가변하여 램프의 출력을 제어하였다. 현재온도가 설정온도와 같을 경우 PWM 신호를 최소로 하였고 현재온도가 설정온도 보다 클 경우는 PWM 출력 신호를 정지시켜 오버헌팅을 방지했으며 연산차가 $4^{\circ}C$이상인 경우 PWM 제어량을 최대폭으로 하여 시스템을 빠른 상승시간 안에 목표치에 도달할 수 있도록 제어하는 방식으로 구현하였다.

• 한국수소및신에너지학회논문집
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• 제23권4호
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• pp.323-329
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• 2012

A thermal management system of a proton exchange membrane fuel cell is taken charge of controlling the temperature of fuel cell stack by rejection of electrochemically reacted heat. Two major components of thermal management system are heat exchanger and pump which determines required amount of heat. Since the performance and durability of PEMFC system is sensitive to the operating temperature and temperature distribution inside the stack, it is necessary to control the thermal management system properly under guidance of operating strategy. The control study of the thermal management system is able to be boosted up with hardware in the loop simulation which directly connects the plant simulation with real hardware components. In this study, the plant simulation of fuel cell stack has been developed and the simulation model is connected with virtual data acquisition system. And HIL simulator has been developed to control the coolant supply system for the study of PEMFC thermal management system. The virtual data acquisition system and the HIL simulator are developed under LabVIEWTM Platform and the Simulation interface toolkit integrates the fuel cell plant simulator with the virtual DAQ display and HIL simulator.

• 설비공학논문집
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• 제15권6호
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• pp.524-532
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• 2003

In this paper, a personal air-conditioning system considering the human thermal adaptability is analyzed. Although the conventional personal air-conditioner was proofed to be satisfactory in providing for the thermal comfort, it is being questioned on the term of its energy efficiency. Therefore, it is important and urgent to develop new types of personal air-conditioning system with sustainable control strategy that can ensure energy saving and thermal comfort simultaneously. In this study, we first examined the problems of the conventional personal air-conditioning system with field interview and laboratory experiment in terms of usage, management and thermal comfort, and proposed the energy-saving personal air-conditioning system considering the human thermal adaptation. Then a laboratory experiment was performed to analyze the characteristics of the human thermal comfort under severe indoor thermal conditions, which were controlled using a new personal air-conditioning unit designed according to the proposal. The results help to illustrate the alleviation effect of the new personal air-conditioning system, and indicate that the thermal alleviation time is useful to maintain the thermal comfort with efficient usage of energy.

• Nuclear Engineering and Technology
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• 제55권10호
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• pp.3898-3906
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• 2023

The paper notes that the most common way of handling spent nuclear fuel (SNF) of power reactors is its temporary long-term dry storage. At the same time, the operation of the dry spent fuel storage facilities almost never use the modern capabilities of information systems in safety control and collecting information for the next studies under implementation of aging management programs. The author proposes a structure of an information system that can be implemented in a dry spent fuel storage facility with ventilated storage containers. To control the thermal component of spent fuel storage safety, a database structure has been developed, which contains 5 tables. An algorithm for monitoring the thermal state of spent fuel was created for the proposed information system, which is based on the comparison of measured and forecast values of the safety criterion, in which the level of heating the ventilation air temperature was chosen. Predictive values of the safety criterion are obtained on the basis of previously published studies. The proposed algorithm is an implementation of the information function of the system. The proposed information system can be used for effective thermal monitoring and collecting information for the next studies under the implementation of aging management programs for spent fuel storage equipment, permanent control of spent fuel storage safety, staff training, etc.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2005년도 전력전자학술대회 논문집
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• pp.501-503
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• 2005

The improvement of load following operation of the thermal power plant is influenced to the electrical quality. Analysis of boiler, turbine, and governor system, and the study of control algorithm are preceded. The thermal power plant is operated by various control systems. In the case of faulty governor system, it takes long days to solve the problem and impossible to repair the mechanism without outage. A non-planned out-age is taken into consideration because of economical power production. In this paper, to clear the continuous swings of an old turbine governor system(YEOSU #1), the trend, the control logic, and the hydraulic mechanism are analyzed, and then the control circuit with ADAPT function and the 1st order lag circuit are inserted and modified. After that, the power plant comes to automatic governor control operation.

• 한국태양에너지학회 논문집
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• 제27권4호
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• pp.167-173
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• 2007

This study analyzed by simulation using TRNSYS as well as by experiment on the solar district heating system installed for the first time for the district heating system in Bundang. Simulation analysis using TRNSYS focused on the thermal behavior and long-term thermal efficiency of solar system. Experiment carried out for the reliability of simulation system. This solar system where the circuits of two different collectors, flat plate and vacuum tube collector, are connected in series by a collector heat exchanger, and the collection characteristics of each circuit varies. Therefore, these differences must be considered for the system's control. This system uses variable flow rate control in order to obtain always setting temperature of hot water by solar system. Specifically, this is a system that heats returning district heating water (DHW) at approximately $60^{\circ}C$ using a solar collector without a storage tank, up to the setting temperature of approximately $85{\sim}95^{\circ}C$ To realize this, a flat plate collector and a vacuum tube collector are used as separate collector loops. The first heating is performed by a flat plate collector loop and the second by a vacuum tube collector loop. In a gross collector area basis, the mean system efficiency, for 4 years, of a flat plate collector is 33.4% and a vacuum tube collector is 41.2%. The yearly total collection energy is 2,342GJ and really collection energy per unit area ($m^2$) is 1.92GJ and 2.37GJ respectively for the flat plate vacuum tube collector. This result is very important on the share of each collector area in this type of solar district heating system.