• Carbon letters
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• v.5 no.4
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• pp.164-169
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• 2004

Carbon-ceramic composites refer to a special class of carbon based materials which cover the main drawbacks of carbon, particularly its proneness to air oxidation, while essentially retaining its outstanding properties. In the present paper, the authors report the results of a systematic study made towards the development of C-SiC-$B_4C$ composites, which involves the effects of compositional parameters, namely, carbon-to-ceramic and ceramic-to-ceramic ratios, on the oxidation behaviour as well as other characteristics of these composites. The C-SiC-$B_4C$ composites, heat-treated to $1400^{\circ}C$, have shown that their oxidation behaviour at temperatures of 800~$1200^{\circ}C$ depends jointly on the total ceramic content and the SiC : $B_4C$ ratio. Good compositions of C-SiC-$B_4C$ composites exhibiting zero weight loss in air at temperatures of 800~$1200^{\circ}C$ for periods of 4~9 h, have been identified. Composites with these compositions undergo a weight gain or a maximum weight loss of less than 3% during the establishment of a protective layer at the surface of carbon in a period of 1~6 h. Significant improvement in the strength of C-SiC-$B_4C$ composites has been observed which increases with an increase in the total ceramic content and also with an increase in the SiC : $B_4C$ ratio.

• Solar Energy
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• v.10 no.2
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• pp.10-17
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• 1990

Short-term tests were conducted on a house at KIER, Daejon for its thermal performance evaluation. The test procedure and data analysis were made according to the PSTAR method. Each test period was 3 days during which the building was unoccupied. The data measured with 8 channels were used to renormalize an audit based simulation model of the house. The following are the key parameters obtained in the present analysis: 1) the building loss coefficient(skin conductance plus infiltration conductance during coheating period); 2) the effective building heat capacity; and 3) the effective solar gain. An estimation of total heat required to maintain a standard level of comfort during a typical winter season is also calculated on the basis of the renormalized simulation model and typical long term weather data.

• Journal of Korean Society of Disaster and Security
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• v.7 no.1
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• pp.27-33
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• 2014

This research has been shown the strategic disaster prevention and safety management's methodology that minimize the demage and loss from environmental disaster: it is made the renewable energy using the urban wastes causing the main environmental disaster, it minimize the generating cost from the environmental disaster, it gain the energy source for preparing the large-scale shutdown electricity, it gain the profit from the continuous electric power and heat energy's generating, it gain the renewal energy source from the old urban wastes' landfill, it give back the citizen the clean environment, the construction cost is able to be solved form the profit which the power plant is made the plasma gasification generation of the urban wastes, it create the new related jobs in the local government, it base to be invested the local industrial zone's commercialization due to the renewal energy power plant. Especially, in happen to the large-scale natural disaster's typhoon and earthquake, in the result generating the large-scale urban wastes, it is shown the prepared and robust model which contribute the preventing recovery of the local economy using the renewal energy of the urban wastes, and the strategic disaster prevention and safety management's method in the future city.

• Journal of the Korean Society of Clothing and Textiles
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• v.32 no.6
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• pp.991-998
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• 2008

This study is to determine the effects of PCM concentration on the temperature changes of the air layers of a garment when the environmental temperature changes. The selected PCM was Nonadecane and coated on cotton fabrics with PCM concentrations 10%, 20%, and 30%. The temperature changes of the air layers between fabrics were measured by Human-Clothing-Environment Simulator which measure a dynamic heat transfer. After stabilizing at $34^{\circ}C$ for 1 hour, the multi layered garment system were exposed to $5^{\circ}C$ or $10^{\circ}C$ for 30 minutes and then, exposed to $34^{\circ}C$ for 30minutes. The results like following could be obtained. When the environmental temperature changed high to low, temperature of the air layer increased by heating effect of PCM. In the contrast, when the environmental temperature changed low to high, the temperature increase of the air layer was delayed because of cooling effect by PCM. Also, the more concentration of PCM, the bigger the heating effect. Cooling effect showed more clearly at PCM concentration 20%. The temperature differences of the air layers between with PCM fabrics and with non-PCM fabrics were bigger at $10^{\circ}C$ than at $5^{\circ}C$. Consequently, though PCM has influenced on the temperature of the air layer by heating and cooling effect, those effects haven't shown in all layers equally. It was shown that the effect of PCM varied according to the layer in the case of multi layered garment system and heat gain as well as heat loss in the outermost layer had to be taken into account.

• Journal of Korean Living Environment System
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• v.21 no.6
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• pp.959-964
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• 2014

Energy performance of building envelope components, including external walls, floors, roofs, windows and doors, is crutial for determining how much energy is required for heating and cooling in a building. Among various building technologies, a green roof system can be a good option for reducing heat gain and loss in new buildings as well as existing buildings for green remodeling. This paper evaluates the performance of green roof systems according to soil depth and Leaf Area Index (LAI) for existing buildings. It also attempts to quantify the energy saving effects on new and existing buildings with different insulation levels. Thermal performance of green roofs is mainly dependent on soil thickness and LAI. Installation of green roofs in deteriorated existing buildings can lead to improvements in roof insulation, due to the soil layer. An increase in soil depth leads to a decrease in heating load, regardless of conditions of vegetation on the green roof. Larger LAI values may reduce cooling loads in the cooling season. Installation of green roof in deteriorated existing buildings showed bigger energy saving effect in comparison to a case in new buildings. A simulation study showed that the installation of green roof systems in deteriorated existing buildings with low insulation levels, due to low thermal performance requirements when constructed, could improve the energy performance of the buildings similar or better to the peformance on new buildings with the most updated insulation standard. Thus, when remodeling a deteriorated building, green roofs could be a good option to meet the most recent energy requirements.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.6
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• pp.493-500
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• 2014

Nonlinear characteristics of cellular counterflow diffusion flame near the radiative extinction limit at large Damk$\ddot{o}$hler number are numerically investigated. Lewis number is assumed to be 0.5 and flame evolution is calculated by imposing an infinitesimal disturbance to a one-dimensional(1-D) steady state flame. The early stage of nonlinear development is very similar to that predicted in a linear stability analysis. The disturbance with the wavenumber of the fastest growing mode emerges and grows gradually. Eventual, an alternating pattern of reacting and quenching stripes is developed. The cellular flame temperature is higher than that of 1-D flame because of the gain of the total enthalpy. As the Damk$\ddot{o}$hler number is further increased, the shape of the cell becomes circular to increase the surface area per unit reacting volume. The cellular flames do not extinguish but survive even above the 1-D steady state extinction condition.

• Asian-Australasian Journal of Animal Sciences
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• v.13 no.6
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• pp.761-773
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• 2000

Eighteen growing male Murrah buffalo (Bubalus bubalis) calves were divided into three groups consisting of six animals each and fed three urea ammoniated wheat straw (UAS) -based rations supplemented with concentrate mixtures (roughage: concentrate ratio 58:42) containing deoiled ground nut cake, GNC (8%), formaldehyde treated GNC (8%) or fish meal (8%) to undertake comparative evaluation of these rations in terms of their $CH_4$ production and growth (285 d duration) potential. A digestibility trial (10 d duration) was followed by a comparative calorimetric study in respiration chamber. Dry matter (DM) intake (84.3 to $89.3g/kg\;W^{0.75}d^{-1}$) did not differ between treatments. The digestibility coefficient of DM, organic matter (OM), crude protein (CP), neutral and acid detergent fiber did not differ significantly in different diets. Urinary energy loss as a percent of gross energy (GE) was not affected by diets. Average values of $CH_4$ production were 84.3, 77.6 and 99.1 g/d and $CH_4$ energy losses as percent of gross energy were 5.7, 5.2 and 6.1 percent on .GNC, formaldehyde treated GNC and fishmeal, respectively, and did not differ significantly. When expressed per unit of digestible OM intake, $CH_4$ production (g) was lower (p<0.05) on formaldehyde treated GNC (30.6) than on untreated GNC (30.6) and fish meal (31.9). Total ME intake and heat production were similar and hence the energy balances on different diets were similar. Nutritive value of rations in terms of digestible CP and ME were similar. Average daily gain calculated on the basis of regression of fortnights on cumulative liveweight gain in calves fed on concentrate containing unprotected GNC, protected GNC and fish meal were 437.1, 483.9 and 481.6 g, respectively. This indicated that the intake of energy was sufficient to meet the requirement of calves growing at 400 g per d. However, CP intake was around 150% of the stipulated standard (Kearl, 1982). Feed conversion ratios on unprotected GNC, protected GNC and fish meal were 11.60, 11.10 and 10.4 respectively. It was concluded that because significantly (p<0.05) low $CH_4$ is produced on protected GNC (8%), it is very good and sustainable protein source in comparison to poor quality fish meal and untreated GNC to be used in concentrate mixture for supplementing UAS-based diets.

• Journal of the Ergonomics Society of Korea
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• v.36 no.3
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• pp.169-181
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• 2017

Objective: The aim of this study was to explore the influence of outdoor weather conditions on subjective responses during physical activity. Background: The largest difference between indoor and outdoor conditions is the existence of the sun. The heat load from the sun has an influence on the heat gain of the human body and the intense degree of solar radiation affected thermal comfort. Method: Thirty eight people were exposed to a range of climatic conditions in the UK. Weather in England does not have extremely hot and cold temperature, and the current study was conducted under warm (summer and autumn) and cool (spring and summer) climates. Measurements of the climate included air temperature, radiant temperature (including solar load), humidity and wind around the subjects. Subjective responses were taken and physiological measurements included internal body temperature, heart rate and sweat loss. Results: This study was conducted under four kinds of environmental conditions and the environmental measurement was performed in September, December, March, and June. The values for sensation, comfort, preference, and pleasantness about four conditions were from 'neutral' to 'warm', from 'not uncomfortable' to 'slightly comfortable', from 'slightly cooler' to 'slightly warmer', and from 'neither pleasant nor unpleasant' and 'slightly unpleasant', respectively. All subjective responses showed differences depending on air temperature and wind speed, and had correlations with air temperature and wind speed (p<0.05). However, subjective responses showed no differences depending on the radiant temperature. The combined effects of environmental parameters were showed on some subjective responses. The combined effects of air temperature and radiant temperature on thermal sensation and pleasantness were significant. The combined effects of metabolic rate with air temperature, wind speed and solar radiation respectively have influences on some subjective responses. In the case of the relationships among subjective responses, thermal sensation had significant correlations with all subjective responses. The largest relationship was shown between preference and thermal sensation but acceptance showed the lowest relationship with the other subjective responses. Conclusion: The ranges of air temperature, radiant temperature, wind speed and solar radiation were $6.7^{\circ}C$ to $24.7^{\circ}C$, $17.9^{\circ}C$ to $56.6^{\circ}C$, $0.84ms^{-1}$ to $2.4ms^{-1}$, and $123Wm^{-2}$ to $876Wm^{-2}$ respectively. Each of air temperature and wind speed had significant relationships with subjective responses. The combined effects of environmental parameters on subjective responses were shown. Each radiant temperature and solar radiation did not show any relationships with subjective responses but the combinations of each radiant temperature and solar radiation with other environmental parameters had influences on subjective responses. The combinations of metabolic rate with air temperature, wind speed and solar radiation respectively have influences on subjective responses although metabolic rate alone hardly made influences on them. There were also significant relationships among subjective responses, and pleasantness generally showed relatively high relationships with comfort, preference, acceptance and satisfaction. Application: Subjective responses might be utilized to predict thermal stress of human and the application products reflecting human subjective responses might apply to the different fields such as fashion technology, wearable devices, and environmental design considering human's response etc.

• Asian-Australasian Journal of Animal Sciences
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• v.32 no.9
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• pp.1407-1413
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• 2019

Objective: This experiment aimed to investigate the effect of different sources and inclusion levels of dietary fat on productive performance and egg quality in laying hens raised under hot environmental conditions. Methods: A total of 480 Hy-Line Brown laying hens at 31 wk of age were randomly allotted to 1 of 5 experimental diets. The control diet contained 2,800 kcal/kg nitrogen-corrected apparent metabolizable energy with no fat addition. Four additional diets were prepared by adding 2.0% or 4.0% of animal fat (AF) or soybean oil (SO). Energy and nutrient concentrations were consistent among all diets. Diets were fed to hens for 4 weeks. Average daily room temperature and humidity were $26.7^{\circ}C{\pm}1.52^{\circ}C$ and $77.4%{\pm}4.50%$. The heat stress index was approximately 76, indicating that hens were raised under heat stress conditions. Results: Final body weight (BW) was greater (p<0.05) for hens fed diets containing 2.0% or 4.0% AF than for those fed the control diet or diets containing 2.0% or 4.0% SO. The BW gain and feed intake were greater (p<0.05) for hens fed diets containing additional AF or SO than those fed the control diet. Eggshell thickness was the greatest (p<0.05) for hens fed the control diet, but the least (p<0.05) for hens fed diets containing 4.0% SO. Egg yolk color was the greatest (p<0.05) for hens fed the control diet, but the least (p<0.05) for hens fed diets containing 4.0% SO. Conclusion: Inclusion of supplemental fat (AF and SO) in diets exhibits preventative effects on BW loss for hens raised under hot environmental conditions when energy and nutrient concentrations in diets were maintained. The effects were greater for AF than for SO. However, inclusion of supplemental fat in diets decreases eggshell thickness and egg yolk yellowness, possibly due to a reduction in Ca absorption and intake of egg yolk colorants.

• Nuclear Engineering and Technology
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• v.28 no.2
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• pp.137-149
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• 1996

The present study is to analyze an integral test, BETHSY test 6.9c, which represent loss of RURS accident under mid-loop operation. Both the pressurizer manway and the steam generator outlet plenum manway are opened as vent paths in order to prevent the system from pressurization by removing the steam generated in the core. The main purposes are to gain insights into the physical phenomena and identify sensitive parameters. Assessment of capability of CATHARE2 prediction can be established the effective recovery procedures using the code in an actual plant. Most of important physical phenomena in the experiment could be predicted by the CATHARE2 code. The peak pressure in the upper plenum is predicted higher than experimental value by 7 kPa since the differential pressure between the pressurizer and the surge line is overestimated. The timing of core uncovery is delayed by 500 seconds mainly due to discrepancy in the core void distribution. It is demonstrated that openings of the pressurizer manwey and the steam generator manway can prevent the core uncovery using only gravity feed injection. Although some disagreements are found in the detailed phenomena, the code prediction is considered reasonable for the overall system behaviors.