• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.451-454
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• 2003

The Oil Coolers is very important unit for the stable thermal performance in machine tools, semiconductor equipments and high precision measuring systems. To select a proper oil cooler for the temperature control of core unit in a machine, not only cooling ability but also static and dynamic sensitivity of temperature sensors are considered. In this paper, the relationship between cooling ability and inflow oil temperature is identified. The cooling ability is increased with the increase of inflow oil temperature. The oil temperature control errors of a cooler are influenced by mainly sensitivity of temperature sensors and heating velocity in a machine. The validity of error cause analysis for temperature control is proved by real cooling experiments with inflow and outflow temperature sensors.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.10
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• pp.833-839
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• 2013

Thermal vacuum test should be performed prior to launch to verify satellites' functionality in a harsh space environment which is represented by extremely cold temperatures and vacuum conditions. A thermal vacuum chamber which consists of a vacuum vessel, a pumping system, and a thermal control system are used to perform thermal vacuum tests of a satellite system and its components. A cryogenic blower is a core component of the closed loop thermal control system for thermal vacuum chambers. This paper describes the fan design of the cryogenic blower, the design of the thermal protection interface between the driving part and the fluid part, which were verified by thermal and structural analyses. The performance of the cryogenic blower is confirmed by similarity test on the test bench.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.4 no.2
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• pp.63-70
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• 2003

In this paper, an MFC (Mass Flow Controller) which is widely used in many semiconductor manufacturing processes for controlling the mass flow rate of a gas is designed and implemented using the PIC 16F876 of Microchip, Inc. The MFC implemented in this thesis has the form of hybrid-type, i.e., the mixed-type of the analog-type MFC, which has many problems such as low accurary, and digital-type MFC, which use an expensive DSP (Digital Signal Processor) and an ADC (Analog to Digital Convertor) with high precision. The MFC is consists of the sensor unit, the control unit and the actuator unit, and it has used the automatic calibration algorithm and the reference table method for the improvement of the performance.

• Journal of Electrical Engineering and Technology
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• v.4 no.3
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• pp.323-329
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• 2009

This paper presents a new approach for thermal unit commitment (UC) using a differential evolution (DE) algorithm. DE is an effective, robust, and simple global optimization algorithm which only has a few control parameters and has been successfully applied to a wide range of optimization problems. However, the standard DE cannot be applied to binary optimization problems such as UC problems since it is restricted to continuous-valued spaces. This paper proposes binary differential evolution (BDE), which enables the DE to operate in binary spaces and applies the proposed BDE to UC problems. Furthermore, this paper includes heuristic-based constraint treatment techniques to deal with the minimum up/down time and spinning reserve constraints in UC problems. Since excessive spinning reserves can incur high operation costs, the unit de-commitment strategy is also introduced to improve the solution quality. To demonstrate the performance of the proposed BDE, it is applied to largescale power systems of up to 100-units with a 24-hour demand horizon.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1352-1357
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• 2004

Thermal error compensation has been developed for CNC (Computer Numerical Control) machining center with moving heat sources. The thermal error in CNC machining center has an effect on machining accuracy more than the geometric error does. Thus, temperature distributions of a spindle unit have been analyzed numerically by a Finite Differential Method and experimentally by an infrared (IR) camera in this study. A multiple variable method has been derived to estimate the thermal deformation of the machine origin stably and effectively after measuring deformation and temperature data. The experimental results for a vertical machining center have shown that the thermal errors of the machine origins were reduced more than 30% by the developed method.

• Journal of Biosystems Engineering
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• v.31 no.3 s.116
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• pp.161-167
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• 2006

The purpose of this study is to find the optimal conditions of PCM slurry manufacturing equipment for saving the marketing cost and keeping the original quality of products. In addition, the characteristics of the movable container for shipping or distributing products is analysed. The major results are as follows. 1. PCM thermal storage system is designed with the conditions of temperature($-5{\sim}10^{\circ}C$), cold chain time(30 minutes), and one time usage(50 liter). This system includes tank, freezer, circulating pump, cycle type heat exchanger, swelling tank, equipment of supplying PCM supplying unit includes cold tank, cycle type heat exchanger, suction unit and control equipments, etc. 2. After ability test of PCM thermal storage system, it shows that the required freezing time of PCM thermal storage system is less than one of the previous system. The reason is that churn (top and bottom) and compulsion circulation are occurred simultaneously and unit cooler type method is better than chiller type method. 3. By the experiment of transportation latent heat container, it is decided that the best container is $K_1$ with latent heat temperature($0{\sim}5^{\circ}C$) and density(0.15%). However, for $K_l\;and\;K_2$, it is necessary more studies on latent heat thermal conditions and conditions of making method.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.20 no.6
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• pp.685-691
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• 2011

The Bearing preload units are used for stable rotational movements of high speed spindles. The feeding mechanism of the preload unit is important to prevent overheat of bearings and to keep constant bearing load under thermal deformation of spindle unit. In this study, ball slide guide and ball bush as feeding mechanism of preload unit are selected. The maximum static friction force, radial stiffness and damping ratio of ball slide guide with ball load, ball number and ball size are widely investigated. In conclusion, the surface of ball slide guide must be heat treated to reduce static friction force. The number and size of ball are increased to control sensitive bearing preload force.

• Environmental Analysis Health and Toxicology
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• v.17 no.1
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• pp.63-71
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• 2002

The thermal desorption-gas chromatographic (TD-GC) system has been constructed for the measurement of volatile organic compounds. The thermal desortion unit is composed of four major parts: 1) the control part; 2) the thermal desorption part; 3) the focusing part; and 4) the injection part. The peltier element was introduced to the focusing part for the temperature of the focusing tube to reach-35$^{\circ}C$. The system was tested for the linearity of the calibration curves and reproducibility of instrumental analyses using some disinfection by-products (DBPs) and BTXs (benzene, toluene and p-xylene). The coefficients of determination (r$^2$) for all the calibration curves made were higher than 0.998, and the coefficients of variation (CV) for triplicate measurements were all within 10％. The system also has been tested for field applicability. The analysis of field samples showed that there was no breakthrough problem in the sampling system and that the system could be applied to field measurements.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.1 no.2
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• pp.9-14
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• 2000

State feedback with integral control for a variable air volume(VAV) unit which is recently taken notice of for the energy efficiency and saving in the building is studied to investigate the performance of the digital control methodology for the possible practical application. The digital controller which acquires the targat zone temperature and the air flow rate of the supplied air to the zone controls the opening of the damper in the VAV unit. Simulation results are performed for the conditions including reference changes and external thermal variations. In the simulation. simplified conditioned zone and the damper actuator modelling is considered. and relationships between controller gain Parameters and the system dynamics are investigated.

• Journal of Convergence for Information Technology
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• v.9 no.1
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• pp.54-60
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• 2019

The recent climate change is exacerbating the external thermal environment and increasing the amount of energy used in building. Energy Plus was used to evaluate low energy technology performance of buildings responding to climate change. The test types of basic building(control) and evaporative mist system + basic building(EMS), and the analysis results of each type are compared. Energy performance evaluation result, Cooling peak load were EMS reduction compared to control is about 9%. Annual cooling load per unit area were EMS reduction compared to control is about 17%. Annual energy use per unit area were EMS reduction compared to control is about 10%. Therefore, the effect of the evaporative cooling system is considered to be good through energy reduction technology of building, according to the amount and distance of the evaporative mist system in the future research on building energy performance evaluation should be carried out.