• Journal of Acupuncture Research
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• 제15권2호
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• pp.173-182
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• 1998

In order to evaluate calorie rate of moxa-combustion(direct moxibustion=DM, indirect moxibustion with stainless steel tube=IMS, indirect moxibustion with ginger slice=IMG), calorie rate(%) in the preheating period, heating period, retaining period, and cooling period was calculated respectively to the total combustion calories in all the periods. The result are as follow: 1. Indirect moxibustion with stainless steel tube had the highest rate with the statistical significance than other groups during the preheating period, represented statistical differences between IMS group and IMG group, and also between DM group and IMS group. 2. Indirect moxibustion with ginger slice group showed the highest rate with the statistical significance and followed by DM group and IMG group during the heating period, represented statistical difference among DM, IMS, and IMG group. 3. Direct moxibustion group had the highest rate with the statistical significance than other group during the retaining period, represented statistical difference between DM group and IMG group, and also between DM group and IMS group. 4. Indirect moxibustion with stainless steel tube had the highest rate with the statistical significance than other groups during the cooling period, represented statistical differences between IMS group and IMG group, and also between IMS group and DM group.

• 설비공학논문집
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• 제16권8호
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• pp.741-747
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• 2004

The purpose of this study was to develop a cooler/heater using a thermoelectric module combined with a parallel flow type oscillating heat pipe with R-142b as a work ing fluid. The experiment was performed for 16 thermoelectric modules (6 A/15 V, size: 40${\times}$40${\times}$4 mm), varying design parameters of the heat pipe (inclination angle, working fluid charging ratio, etc) . Experimental results indicate that the optimum charging ratio and the inclination angle of the parallel flow type oscillating heat pipe were 30% by volume and 30%, respectively. The maximum cooler/heater capacity were 479W (COP : 0.47) and 630W (COP : 0.9), respectively.

• International Journal of Air-Conditioning and Refrigeration
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• 제16권4호
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• pp.109-116
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• 2008

Ground temperature restoration characteristics are the crucial factors to evaluate whether a ground source heat pump system can keep long time steady operation. They are mainly dependent on soil thermal properties, layout of pile group, operation/shutoff ratio, cooling/heating load, thermal imbalance ratio and so on. On the one hand, several types of vertical pile foundation heat exchangers are intercompared to determine the most efficient one by performance test and numerical method. On the other hand, according to the layout of pile group of a practical engineering and running conditions of a GSHP system in Shanghai, the temperature distribution during a period of five years is numerically studied. The numerical results are analyzed and are used to provide some guidance for the design of large-scale GSHP system.

• International Journal of Air-Conditioning and Refrigeration
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• 제15권1호
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• pp.34-45
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• 2007

In order to reduce the compression power and to use the overall energy contained in LNG effectively, a combined cycle is devised and simulated. The combined cycle is composed of two cycles; one is an open cycle of liquid/solid carbon dioxide production cycle utilizing LNG cold energy in $CO_2$ condenser and the other is a closed cycle gas turbine which supplies power to the $CO_2$ cycle, utilizes LNG cold energy for lowering the compressor inlet temperature, and uses the heating value of LNG at the burner. The power consumed for the $CO_2$ cycle is investigated in terms of a solid $CO_2$ production ratio. The present study shows that much reduction in both $CO_2$ compression power (only 35% of the power used in conventional dry ice production cycle) and $CO_2$ condenser pressure could be achieved by utilizing LNG cold energy and that high cycle efficiency (55.3% at maximum power condition) in the gas turbine could be accomplished with the adoption of compressor inlet cooling and regenerator. Exergy analysis shows that irreversibility in the combined cycle increases linearly as a solid $CO_2$ production ratio increases and most of the irreversibility occurs in the condenser and the heat exchanger for compressor inlet cooling. Hence, incoming LNG cold energy to the above components should be used more effectively.

• KIEAE Journal
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• 제13권2호
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• pp.3-12
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• 2013

Recently, New Han-ok is in prevail because it has many good qualities as a dwelling. But the New Han-ok dwellers' needs and satisfaction ratio on their houses are not investigated yet. So, surveys on satisfaction ratio for New Han-ok were carried out to know New Han-ok's existing conditions and inhabitant's responses on New Han-ok dwellings. Followings are results. 1) Dwellers response that it is cool in summer and it is cold in winter. So, design and construction method against cold is needed for New Han-ok. 2) Window is the most picking element of New Han-ok for house improvement. 3) Window opening is main control method for cooling in summer. Warming sources in winter are various such as electricity, gas, oil, wood, etc. 4) PVC window structure and glasses were used for New Han-ok's window system as well as wooden window structure and Han-gi. 5) Interviewees are generally satisfied with New Han-ok's exterior view and inner spaces. Almost no humidifier is used. These results could be used for improvement of Han-ok and basic material for New Han-ok design.

• 한국주조공학회지
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• 제34권4호
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• pp.123-129
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• 2014

This work presents the results of a thixo-extrusion process applied to aluminum alloy and and reheating characteristics of semi-solid A356 Alloy using have been discussed. The reheating experiment was performed using an electric resistance furnace and multi-stage heating for uniform reheating. The thixo-extrusion was performed at the optimal reheating conditions of the semi-solid A356 alloy, the the extrusion conditions were an extrusion ratio of 33 and ram speed of 6 mm/sec. The results showed that the thixo-extrusion of semi-solid A356 alloy fabricated by the cooling slope reduced the extrusion pressure by 180% in comparison with hot extrusion, and that a sound extrusion could be obtained in spite of the same extrusion ratio and strain rate.

• 한국태양에너지학회 논문집
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• 제31권3호
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• pp.67-72
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• 2011

The aim of this study is to evaluate how much would the building energy consumption be saved by applying DSSC BIPV window which is possible to control the transmittance and express the color in the office building. For this, physical characteristics such as transmittance and reflectance, U-factor of DSSC areanalyzed and an annual energy consumption that is connected to dimming control is calculated when DSSC BIPV window is applied by alternate clear window system. As a result, It is possible to reduce the anannual energy consumption as much as4.1% by just change the clear double window system to DSSC BIPV double window system because the major factor to reduce energy consumption in the office that has much cooling load than other building is SHGC. When the thermal insulation properties of DSSC BIPV window with low-e coating and making triple window are improved, energy saving ratio is about 9%. Plus, energy saving ratio of 25~28% in lighting energy consumption is possible when the dimming control system with DSSC BIPV window is adopt.

• Journal of Advanced Marine Engineering and Technology
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• 제29권1호
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• pp.42-48
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• 2005

Because Impinging jet has excellent heat & mass transfer characteristics. it has many advantages of cooling. drying. etc and widely applied at industrial fields. Therefore, there have been many experimental investigations and theoretical studies about Impinging jet. The present study is about a cooling characteristic by Impinging jet for a Square Plate on Duct and investigated this characteristic through three-dimensions numerical analysis, using FLUENT. As the result of this study, heat transfer effect is the most appropriate condition when the ratio of distance is 6 between nozzle exit diameter and heat source. diameter of duct is 90mm and height of duct is 60mm. In addition. under the influence of injected jet. stagnant fluid flow into free jet field and this affected the whole flow field. So the shape of duct is a important factor and the researcher confirmed the need of investigation about duct.

• 설비공학논문집
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• 제4권1호
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• pp.48-56
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• 1992

The purpose of this study was to investigate the enhancement of heat transfer without additional external power in the case of rectangular air jet impinging vertically on the flat heating surface. In an attempt to enhance the heat transfer rate in two-dimensional impinging jet, the technique used in the present study was placement of square rod bundles as a turbluence promoter in front of the heat transfer surface. The effects of the clearance between the flat plate and square rod, and the nozzle exit velocity on the heat transfer characteristics have been investigated experimentally. The results obtained through this study were summerized as follows. High heat transfer enhancement was achived by means of flow acceleration and thinning of boundary layer by inserting rods in front of the heating flat plate. The smaller the clearance between rod and heating plate was, the larger heat transfer effect became. Average Nusselt number reached maximum at $Re=5.76{\times}10^4$ and C＝1㎜ and the enhancement rate of heat transfer became maxium at this condition with the enhancement ratio as high as about 1.427 when normalized by the flat plate value. The correlating equation of average Nusselt number and Reynolds number was obtained, which is $\bar{N}uo=1.324{\cdot}Re^{0.459}{\cdot}(C/A)^{-0.034}$.

• 한국주거학회논문집
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• 제23권2호
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• pp.99-106
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• 2012

Compared to Packaged Terminal Air Conditioning Systems, Radiant Cooling Systems have the advantage of energy saving and thermal comfort. Thermally Activated Building System (TABS) is one of the radiant heating and cooling systems. The main difference between TABS and other radiant systems lies in the usage of the time-lag effect of storing heat energy in the concrete. Current energy usage in summer time is concentrated within a specific time by using Packaged Terminal Air-Conditioner (PTAC). Due to the time-lag effect of TABS, energy usage can be distributed to other time zones. To maximize this effect, it is important to determine the appropriate operating mode, which for TABS is dependent upon the cooling load generated by the occupancy schedule. In this study, occupancy schedules are determined for various residential types. The operating modes of TABS for these residential types are estimated by using a dynamic computational simulation method. The results indicate that the operating modes of TABS can be determined by residential type and occupancy schedule. The load handled ratio by TABS is set up differently according to the cooling load profile obtained from residential type and occupancy schedule. By using TABS, energy consumption could be reduced by 20% compared to PTAC.