• Journal of Korean Society of Forest Science
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• v.85 no.2
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• pp.288-299
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• 1996

This is the basic study to investigate the amount of transpirational water loss in thrifty mature Quercus mongolica stand by the heat pulse method. The differences of heat pulse velocity by direction and depth, differences of heat pulse velocity by dominant, codominant and suppressed trees, diurnal changes of heat pulse velocity due to the change of leaf water potential, vapor pressure deficit and radiation, and sap flow path way in sapwood by dye penetration were measured in stems. Finally the amounts of daily and annual transpiration in stand were calculated by the heat pulse velocity. The results obtained were summarized as follows : 1. Relationship between heat pulse velocity(V) and sap flow rate(SFR) was obtained as a equation of SFR=1.37V. 2. The sap flow rate was high in the order of dominant, codominant, and suppressed trees. The daily heat pulse velocity changed with radiation, temperature and vapor pressure deficit. 3. The heat pulse velocity showed the similar diurnal variation as the leaf water potential change. 4. The heat pulse velocity showed the highest value in May(4.0cm/hr in average), the lowest one in July(2.9cm/hr in average). 5. The heat pulse velocity in the same stem presented the highest value in the northern direction, medium in western, and the lowest in southern and eastern. 6. The heat pulse velocity in stem was highest in 0.5cm, medium in 1.0cm, and lowest in 1.5cm depth from the surface of stem. 7. The sap flow path way in stem showed sectorial straight ascent pattern in four sample trees. 8. The amount of sap flow(SF) was presented as a equation of $SF=1.37A{\cdot}V$(A: the cross-sectional area of sapwood, V: heat pulse velocity), and especially SF was larger in dominant tree than codominant and suppressed trees. 9. The amount of daily transpiration was 5.6ton/ha/day, and its composition ratio was 72% at day and 28% at night. 10. The amount of stand transpiration per month was largest in May(168ton/ha/month), lowest in July(125ton/ha/month). The amount of stand transpiration per year was 839ton/ha/year.

• Magazine of the Korean Society of Agricultural Engineers
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• v.40 no.3
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• pp.94-102
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• 1998

This experiment was carried out to study on the effect of greenhouse heating by water-to-water heat pump system employing heating water tank(ground water) as the heat source. Followings are the results obtained from this study ; 1. The heat amount absorbed from evaporator and the heat amount rejected from condenser were approximately 9, 000~ 12, 000kcal/h and 13, 000~ 17, OOOkcal/h, respectively. 2. The heat efficiencies of evaporator and condenser used in this experiment were approximately 79% and 83%, respectively. 3. The maximum heating load estimated for the experimental greenhouse was about 18, 000 ~ 25, OOOkcal/h, which was found to be about 28 ~ 32% higher than the heating capacity of the heat pump system adopted for this experiment. 4. The coefficients of performance(COP) for the heat pump and the total heat pump system were approximately 2.9~3.5 and 1.5~2.4, respectively. 5. The coefficient of performance(COP) calculated from the Mollier Diagram was about 3.2 ~ 3.4, which was reasonably close to the COP estimated on the basis of measured values. 6. The temperature of experimental greenhouse heated by the heat pump system could be maintained about 12~15 。C higher than that of a control greenhouse.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.10 no.3
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• pp.1-7
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• 2014

Heat pumps have received a fair amount of attention all over the world for their high efficiency and low environmental impact. Employing heat pumps for residential heating and cooling produces only about 2038 kg-$CO_2$/year, an amount which is less than half that of conventional boiler systems. However, the use of single-stage heat pumps becomes uneconomical when they are operated at very low evaporating temperature or high condensing temperature. Two-stage heat pumps systems can be used successfully for low or high temperature applications. In this paper, the experimental study on the performance of two-stage heat pump with an economizer was executed in heating mode. When the secondary fluid inlet temperature to the indoor heat exchanger increased, the COP enhancement rate of two-stage heat pump with an economizer was increased. For all outdoor inlet temperature conditions, the performance of the heat pump with an economizer was higher than it without an economizer.

• Journal of Environmental Science International
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• v.25 no.2
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• pp.239-246
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• 2016

This study aims to analyze region-specific trends in changing greenhouse gas emissions in incineration plants of local government where waste heat generated during incineration are reused for the recent five years (2009 to 2013). The greenhouse gas generated from the incineration plants is largely $CO_2$ with a small amount of $CH_4$ and $N_2O$. Most of the incineration plants operated by local government produce steam with waste heat generated from incineration to produce electricity or reuse it for hot water/heating and resident convenience. And steam in some industrial complexes is supplied to companies who require it for obtaining resources for local government or incineration plants. All incineration plants, research targets of this study, are using LNG or diesel fuel as auxiliary fuel for incinerating wastes and some of the facilities are using LFG(Landfill Gas). The calculation of greenhouse gas generated during waste incineration was according to the Local Government's Greenhouse Emissions Calculation Guideline. As a result of calculation, the total amount of greenhouse gas released from all incineration plants for five years was about $3,174,000tCO_2eq$. To look at it by year, the biggest amount was about $877,000tCO_2eq$ in 2013. To look at it by region, Gyeonggido showed the biggest amount (about $163,000tCO_2eq$ annually) and the greenhouse gas emissions per capita was the highest in Ulsan Metropolitan City(about $154kCO_2eq$ annually). As a result of greenhouse gas emissions calculation, some incineration plants showed more emissions by heat recovery than by incineration, which rather reduced the total amount of greenhouse gas emissions. For more accurate calculation of greenhouse gas emissions in the future, input data management system needs to be improved.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.2
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• pp.292-298
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• 2008

This study was experimentally investigated to understand the ice making characteristics of ice on a coil type ice maker. The experiment was carried out under the following conditions which are the brine temperatures of $-10[^{\circ}C],\;-8[^{\circ}C],\;-6[^{\circ}C]$, brine flow velocities of 1.0[m/s], 1.4[m/s], 1.8[m/s] and initial water temperatures of $6[^{\circ}C],\;9[^{\circ}C],\;12[^{\circ}C]$, ect. The acquired conclusions shows: 1) Ice making amount is increased with decreasing in the temperature of brine. 2) Total ice making amount shows higher value in larger size coil. However, the ice making amount per heat transfer area is increased in smaller one. 3) The ice making amount is increased with decreasing in the initial water temperature. 4) It is cleared that the overturn of natural convection existed in this experimental result.

• Journal of Welding and Joining
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• v.24 no.1
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• pp.64-70
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• 2006

570MPa grade weldable steels were gas metal arc welded with various heat inputs and interpass temperatures using flux cored wires. Effects of heat input and interpass temperature on the strength and impact toughness of weld metal were investigated in terms of microstructural change, recovery of alloying elements, and the amount of reheated weld metal. Increase of heat input and interpass temperature resulted in decrease of weld metal strength. This is because of the small amount of acicular ferrite, large columnar size and low recovery of alloying elements such as manganese and silicon. In addition to the microstructural change, weld metal toughness was also influenced by the deposition sequence. It increased with an increase of the amount of reheated weld metal.

• Asian-Australasian Journal of Animal Sciences
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• v.33 no.4
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• pp.634-639
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• 2020

Objective: This study was conducted to investigate the effect of heating of foot-and-mouth disease (FMD) vaccine before injection, on the incidence of lesions at the injection site (pork butt), amount of discarded meat, and economical benefit. Methods: In total, 101,086 piglets raised in 30 farms, were vaccinated in the neck with 2 mL of FMD vaccine at 56 d and 84 d of age using a commercial syringe. The heat treatment group (48,511 pigs) was injected with the FMD vaccine after it had been heated in a water bath at 40℃ for 20 min. After slaughter, the incidence of lesions on the pork butt was inspected, and the subsequent amount of discarded meat was recorded. Results: Heat treatment of FMD vaccine reduced the incident rate of lesions on the pork butt (p<0.01). Overall, 17.81% of the pigs in the heat treatment group had lesions, while the incident rate in the control group was 21.70%. The amount of discarded meat per head of total pigs and per head of pigs with lesions were significantly lower in the heat treatment group than the control group (p<0.01). Thus, the proportion of discarded meat to dressed carcass was lower in the heat treatment group (0.249%) compared with the control group (0.338%) (p<0.01). Farms that rear 1,000 sows can gain 1,863,289 KRW (1,600 USD) in one year when they adopt heat treatment of FMD vaccine before injection. Conclusion: Heat treatment of FMD vaccine using simple heat equipment (water bath) can be effective in reducing lesions caused by FMD vaccination and increase the economic benefits in pig farms.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.8 no.1
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• pp.13-20
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• 2012

This is an experimental study on the performance characteristics of effective heat pump in the cooling mode using a single-stage compression $CO_2$ cycle with an IHX(internal heat exchanger). The performance of a single-stage compression with IHX was investigated according to charge amount and operating condition. Moreover, the performance characteristic of cooling operating was analyzed with the length of IHX. As a result, the optimum refrigerant charge amount was 2.2 kg. The optimal system COP for compressor frequency of 30, 40, 50, and 60 Hz was 3.493, 3.228, 2.978, and 2.659, respectively. Since the system with IHX can maintain large cooling capacity regardless of operating condition, the system performance doesn't reduce considerably under unfavorable condition. When the compressor frequency was 40 Hz, the COP for a system with IHX length of 3 m and 5 m was 3.361 and 3.51, respectively. By using the IHX into a $CO_2$ cooling system, the performance and reliability improves simultaneously.

• Journal of the Korean Society of Clothing and Textiles
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• v.21 no.4
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• pp.669-676
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• 1997

The purpose of this study is to examine the effect of the improved cold tolerance resulting from cool clothing in winter on heat tolerance in summer. Ten healthy women were divided into two groups, cold group(C group) (n=5) and warm group(W group) (n=5) . In the previous study, C group was proved that their cold acclimatization was achieved through wearing cool clothing from September to February of the following year, while Wgroup was not proved because of wearing warm clothing during same period. After February, no more clothing training was continued in two groups. To determine the heat tolerance, both groups were exposed from a thermoneutral environment(25$\pm$1$^{\circ}C$, 50$\pm$5% R.H.) to a hot environment (35$\pm$1$^{\circ}C$, 50$\pm$5% R.H.) before and after clothing training, respectively September in 1994 and truly in 1995. Rectal temperature, skin temperatures, thermal sensation and comfort were measured every 10 min., and Os uptake was measured at 10, 45, 85 min. after entering the chamber for 5 min. Body weight was measured before and after the experiment and amount of local sweat was measured during the 90 min long experiment. The results are as follows: Rectal temperatures in 35'c environment of C group were increased after training when compared with before clothing, while those of W group were not changed. But the changes of rectal temperature and heat production during 90 min in hot environment were almost the same in two groups after training. And mean skin temperatures, the changes of mean skin temperatures during 90 min in hot environment, total sweat amount and local sweat amount after training were also the same in two groups. From these results, it might be supposed that the heat loss of two groups were the same but the heat production, especially heat production during rest in C group was higher than in Wgroup. This fact suggests that the increase of rest heat production from cold acclimatization in winter is maintained to summer of the following year. And mild cold acclimatization coming from westing cool clothing does not have a negative effect on heat tolerance.

• Journal of Power System Engineering
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• v.7 no.4
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• pp.31-37
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• 2003

This paper is a study on application of warm air circulator by using the carbon heating element with particle type. The main variables are the input current and amount of carbon heating source for experimental characteristics. The experimental results are obtained as follows. As the input current and temperature are increased, the resistance of heat source is decreased about $20{\sim}25%$ by the effect of negative resistance. As the amount of heating source is small, Joule heat is large with the input current. When the amount of heating source is 300 and the input current is 15A, the value of Joule heat is about 4604.6kJ/h. The heat production efficiency of carbon heating source is larger about 10% than the sheath heater.