• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.23 no.12
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• pp.836-842
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• 2011

It has been shown that the air-conditioning system with slab cooling storage is effective in cutting peak load and utilizing nighttime electric power. The stochastic properties of internal heat generation which has great influence on the cooling load are examined in this paper. Based on the measured cooling load and electric power consumption in an office building with slab cooling storage, stochastic time series models to simulate these random processes are investigated. Furthermore, a calculated result by an optimal control method of thermal analysis taking into account the internal heat is compared with the measured cooling load.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.11
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• pp.937-942
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• 2003

In the present study, low-temperature low-pressure refrigerant storage method is proposed to achieve higher cooling capacity during a short period of time than that of a compressor in steady operation. Experimental apparatus was designed and set up to analyze the performance of the new-conceptual cooling system. Two reservoirs for sequential storage of refrigerant were used in the cooling system. Several on/off solenoid valves were installed for control of refrigerant flow. From the experimental results, the initial rapid cooling by low temperature low-pressure refrigerant storage method was ascertained for successful operation. This rapid cooling methodology shall be useful for other low-capacity refrigeration system.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.1119-1124
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• 2006

The objectives of this paper are to investigate the performance of silica gel-water adsorption refrigeration system with heat recovery process from the system experiment. This system can be driven by waste heat at near ambient temperature from $60^{\circ}C$ to $90^{\circ}C$. The cooling capacity and coefficient of performance(COP) were measured from various experimental conditions. An experimental results revealed the influence of operating temperatures(hot, cooling and chilled water), water flow rates, and adsorption-desorption cycle times on cooling capacity and COP. Under the standard conditions of $80^{\circ}C$ hot water, $25^{\circ}C$ cooling water, $14^{\circ}C$ chilled water inlet temperatures and 420sec cycle time, a cooling capacity of 1.14kW and a COP for cooling of 0.55 can be achieved.

• Nuclear Engineering and Technology
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• v.51 no.2
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• pp.402-409
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• 2019

When a loss of coolant accident (LOCA) occurs in a nuclear power plant, accident scenarios which can prevent core damage are defined based on break size. Current probabilistic safety assessment evaluates that core damage can be prevented under small-break LOCA (SBLOCA) and steam generator tube rupture (SGTR) with rapid cool down (RCD) strategy when all safety injection systems are unavailable. However, previous research has pointed out a limitation of RCD in terms of initiation time. Therefore, RCD success criteria estimation based on allowable coping time under a SBLOCA or SGTR when all safety injection systems are unavailable was performed based on time-line and thermal-hydraulic analyses. The time line analysis assumed a single emergency operating procedure flow, and the thermal hydraulic analysis utilized MARS-KS code with variables of break size, cooling rate, and operator allowable time. Results show while RCD is possible under SGTR, it is impossible under SBLOCA at the APR1400's current cooling rate limitation of 55 K/hr. A success criteria map for RCD under SBLOCA is suggested without cooling rate limitation.

• Journal of Bio-Environment Control
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• v.10 no.1
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• pp.10-14
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• 2001

The cooling effect of a fog cooling system has a close relationship to air flow and relative humidity in the greenhouse. From the VETH chart for cooling design, a cooling efficiency can be improved by means of increasing the air exchange rate and the amount of sprayed water. In the no shading experimental greenhouse by time control, when average air exchange rate was 0.77 times.min$^{-1}$ and spray water amount was 2,009g, inside temperature of the greenhouse was 31$^{\circ}C$ that was almost close to outside temperature and cooling efficiency was 82%. When average air exchange rate was close to temperature of the greenhouse that was no cooling and 70% shading greenhouse environment. When average air exchange rate was 2.59times.min$^{-1}$ , spray water amount was 2,009g and shading rate was 70%, inside relative humidity of the greenhouse was increased was 2,009 g and shading rate was 70%, inside relative humidity of the greenhouse was increased, but temperature was not decreased. When average air exchange rate was 2.33 times.min$^{-1}$ and spray water amount was 2,009g, inside temperature was 31.4 and at that time maximum wind speed at the air inlet of greenhouse was 1.9m.s$^{-1}$ . Since time controller sprayed amount of constant water at a given interval, some of sprayed water remained not to be evaporated, which increased relative humidity and decreased cooling efficiency. Because the shading screen prevented air flow in the greenhouse, it also caused the evaporation efficiency to be decreased. In order to increase cooling efficiency, it was necessary to study on controling by relative humidity and air circulation in the greenhouse.

• Journal of Navigation and Port Research
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• v.36 no.1
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• pp.35-41
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• 2012

In this paper, we analyze the current submarine cooling system and study control algorithms for cooling system. Cooling system are installed in the submarine propulsion motor to protect the motor from high-temperature by iron loss and copper loss. The cooling system control the sea water and fresh water pump RPM to keep the motor temperature stable by external environment and motor RPM holding time. The cooling system simulation program is made for checking the cooling performance, and simulation is performed with various control strategy. The results with proposed cooling algorithm is shown to improve the thermal stability and efficiency of cooling system.

• Design & Manufacturing
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• v.1 no.1
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• pp.27-32
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• 2007

In the optical application demand for high quality lens is increasing. Plastics lenses are demanded more than glass lenses for large size lenses as well as micro-size lenses. It is difficult to apply typical straight cooling channels of injection mold to lens molding due to its non-uniform temperature distribution. In this study, we manufactured molds for plastic lenses with the conventional cooling channels and conformal cooling channels produced by the DMLS process. We evaluated cooling performance for the 2 molds by injection molding experiment. Also, uniformity of the temperature distribution was tested by infrared camera and temperature monitoring. We confirmed that the cooling performance and temperature uniformity with the conformal cooling channels is much improved from the ones with the conventional. The cooling time with the conformal cooling channels was reduced 30% compared with the conventional cooling channels.

• Journal of Trauma and Injury
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• v.22 no.2
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• pp.227-232
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• 2009

Purpose: Numerous experimental studies have shown the benefits of treating thermal burns by cooling. Nevertheless, few studies have shown the clinical effect of cooling therapy on thermal burns. This study aimed to identify the clinical effect of immediate cooling therapy. Methods: The research was conducted as a retrospective, case-control study. All patients had thermal injuries characterized as a superficial second-degree burn. In the cooling group, 14 patients had first-aid cooling therapy delivered by either parents, caregivers, general practitioners, local hospitals, and/or Myongji hospital. Included in the study were 22 control patients who were not treated with any cooling therapies. Other clinical factors, such as age, sex, cause of burn injury, and burn area (Total Body Surface Area %), were taken into consideration. The duration of treatment was defined as the time from the occurrence of the injury to the presence of complete re-epithelialization, as confirmed by two surgeons. Results: The duration of treatment in the cooling group was significantly less than that the control group (p<0.05). Conclusion: Cooling therapy as an initial emergent treatment is clinically effective for superficial second-degree burn injuries.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.22 no.2
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• pp.86-96
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• 2010

The paper describes development and evaluation of a simple method for determining gradient of modified linear setpoint variation to reduce peak electrical cooling demand in buildings using building precooling and setpoint adjustment. The method is an approximated approach for minimizing electrical cooling demand during occupied period in buildings and involves modified linear adjustment of cooling setpoint temperature between $26^{\circ}C$ and $28^{\circ}C$. The gradient of linear variation or final time of linear increase is determined based on the cooling load shape in conventional cooling control having a constant setpoint temperature. The potential to reduce peak cooling demand using the simple method was evaluated through building simulation for a calibrated office building model considering four different weather conditions. The simple method showed about 30% and 20% in terms of reducing peak cooling demand and chiller power consumption, respectively, compared to the conventional control.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.4
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• pp.424-431
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• 2003

The evaporation cooling phenomenon of a droplet containing a surfactant on a heated surface has been studied experimentally. The two kinds of heater modules made of brass and Teflon$^{TM}$ were tested to investigate the cooling characteristics of droplet. Solutions of water containing Sodium Lauryl Sulfate(0 ppm, 100 ppm, 1000 ppm) were tested in the experiments. The results showed that the contact angle decrease as the concentration of surfactant increases. The tendency did not very with different heated solid materials. As initial temperature of the heated surface becomes high, time averaged heat flux increases and evaporation time decreases with the denser concentration of surfactant. Therefore, water with denser concentration of surfactant could be effective to cool flammable materials. However, the effect of surfactant becomes low as the material temperature is higher than the boiling temperature of water.