• Journal of Biosystems Engineering
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• v.34 no.5
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• pp.371-376
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• 2009

Microwave digestion is a preferred pretreatment method for agricultural samples because of its quick chemical reaction and minimum loss of analytes. In this research, a feedback temperature controller was developed to control the temperature inside a vessel for the microwave-assisted digestion system. An existing industrial microwave oven was fitted with the temperature controller for controlling inside temperature of the vessel. Four control methods, On/Off, proportional (P), proportional integral (PI), and proportional integral derivative (PID) were used and compared. Experimental results showed that PID control produced best temperature control performance. The PID controller could maintain the temperature of water sample and rice sample in the digestion system with error range of $-2.5{\sim}3.3^{\circ}C$ and $-1.9{\sim}0.5^{\circ}C$ at set temperature of $170^{\circ}C$, respectively.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.764-767
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• 2004

This paper present the temperature control of aluminum plate using Peltier element. Peltier effect is heat pumping phenomena by electric energy as one of the thermoelectric effect. So if current is asserted to Peltier element, it absorbs heat from low temperature side and emits to high temperature side. In this experiment, Peltier element is used to control the temperature of small aluminum plate with ON/OFF control scheme and fan ON/OFF. As the result of experiments, it is proper to act fan only while cooling duration and there exist a proper cooling current to drop temperature rapidly. It takes about 100sec to increase to 7$0^{\circ}C$ and drop to 35$^{\circ}C$ of aluminium plate temperature and about 90sec to increase to 7$0^{\circ}C$ and drop to 4$0^{\circ}C$ in ambient temperature 3$0^{\circ}C$ while fan is on only in cooling duration. Future aim is to realize more rapid temperature control and develop SMHA(special metal hydride actuator) by using Peltier element to heating and cooling.

• International Journal of Advanced Culture Technology
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• v.4 no.2
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• pp.47-56
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• 2016

In transformer cooling systems, oil temperature is controlled through the use of a blower and oil pump. For this paper, set-point algorithms, a reset algorithm and control algorithms of the cooling system were developed by neural networks and fuzzy logics. The oil inlet temperature was set by a $2{\times}2{\times}1$ neural network, and the oil temperature difference was set by a $2{\times}3{\times}1$ neural network. Inputs used for these neural networks were the transformer operating ratio and the air inlet temperature. The inlet set temperature was reset by a fuzzy logic based on the transformer operating ratio and the oil outlet temperature. A blower was used to control the inlet oil temperature while the oil pump was used to control the oil temperature difference by fuzzy logics. In order to analysis the performance of these algorithms, the initial start-up test and the step change test were performed by using the dynamic model of a transformer cooling system. Test results showed that algorithms developed for this study were effective in controlling the oil temperature of a transformer cooling system.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.1
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• pp.59-65
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• 2001

The work presented here is an implementation of PID control to achieve a required supply air temperature in PEM(Personal environment module). In PEM, the air is heated to the required temperature while it flows through the supply duct, without any mixing chamber. This makes the control of air temperature in PEM difficult. Linear dynamic model of heat transfer in PEM is first obtained. Then P, PD and PID type control systems, to provide the rapid response without overshoot and saturation, are designed and implemented experimentally. Data obtained shows that the control system satisfied the design criteria and works properly in controlling the supply air temperature.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.9
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• pp.881-888
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• 2004

Control algorithms for a dual source chiller air conditioning system were developed. These are control algorithms for the supply air temperature control, the supply header chilled water temperature control, the chiller chilled water temperature control, and the cooling tower water temperature control. These algorithms were analyzed by using a dynamic simulation program. Simulation results showed the energy savings and the satisfactory controls of an absorption and centrifugal chiller air conditioning system. Therefore, control algorithms developed for this study may effectively be used for the improved controls of the dual source chiller air conditioning system.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.675-680
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• 2006

Capacities of a tandem-type air-conditioner may be modulated by turning on and off of multiple compressors, and adjusting the position of a electronic expansion valve. In this study, control algorithms for compressors and a electronic expansion valve were developed by using fuzzy logics. The pressure control algorithm was also developed for the safe operation of compressors. There algorithms were implemented in a test lab and proved to be effective for the control of indoor air temperature and superheat temperature,

• Journal of Environmental Health Sciences
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• v.28 no.2
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• pp.161-171
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• 2002

The number of food establishments selling raw and convenience foods are increasing in Korea, and people enjoy purchasing and eating foods at these shops. However, there are only a few reports on the temperature control of the refrigerators and freezers at retail food shops. This study was performed to investigate the temperature control of refrigerators and freezers in retail food shops in Daegu. The survey was carried out from July 20 to August 30 in 2001. The trained surveyors visited the twenty retail food shops (four department stores, eight marts/supermarkets and eight convenience stores) in the 8 major areas of Daegu and inspected the temperature control of 48 refrigerators for dairy products, fruits & vegetables, and rolled rice & sandwiches, and 52 freezers for ice cream & sherbet, frozen food, and frozen fish. The percentage of the refrigerators, and freezers with unsafe temperatures higher than the recommended safe temperature (10℃ for refrigerators, and -18℃ for freezers) was 42%; 45.8% in refrigerators; 38.5% in freezers. On an average, the bigger the size of the shop, the better than the other freezers. On the other hand, the temperature control of refrigerator for fruits & vegetables was the worst because they were usually open. Actual temperatures in the refrigerators and freezers were found to be significantly higher than the reading on the thermometers attached to the refrigerators and freezers(p<0.05). These results indicate that temperature control of refrigerators and freezers at retail food shops should be monitored several times each day, and should have strict inspection. There should be more detailed legal standard and specification for temperature control of refrigerators and freezers at retail food shops to prevent foodborne illness from unsafely stored food.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.900-904
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• 1991

It is important and difficult to control the steam temperature in the once through boiler. Generally, steam temperature of once through boiler not only is controlled by boiler spray water flow, but also is influenced by feed water flow and fuel flow. So we have to make the same gain of fuel flow controller and feed water flow controller. This paper is shown the design and test of steam temperature and feed water flow control system for once through boiler in pusan thermal power plant.

• 제어로봇시스템학회:학술대회논문집
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• 1986.10a
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• pp.468-470
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• 1986

An optimal control in heat-up operation was formulated for minimizing the quadratic performance criterion which is a function of temperature, temperature gradient in the wall and fuel flow rate. For optimal control law computations mathematical model was simplified with assumptions and then linearized by use of orthogonal collocation in radial direction. Effects of weighting function assigned to temperature and temperature gradient and final time were compared with industrial data.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2012.06a
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• pp.130-132
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• 2012

In this paper, a temperature control for LED(Light Emitting Diode) lamp using a cooling fan is studied. An efficient temperature control scheme for the LED lamp using the fan wind at the lowest sound noise is studied. For the study, after measurement of the minimum sound noise of the fan and related temperature of the LED lamp through tests, experiments on temperature control of the LED lamp using the fan with various size of heat sinks was performed. To minimize the fan sound noise, optimal size of the heat sink was studied. Also, a teleoperting control of LED lamps using RF communication was studied.