• Proceedings of the Korean Society of Crop Science Conference
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• 2000.11a
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• pp.28-45
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• 2000

It was unusual crop weather for 1998 and 1999 compared with normal in Korea. The consecutive days of the optimum ripening period for rice plant that had daily mean temperature 21-23C for 40 days after heading, increased with long anomalies in 1998-99. The air temperature during ripening period was much higher than the optimum temperature and lower sunshine hour than normal in the local adaptability tests of newly developed rice lines during those years. In response of rice cultivation to warming and cloudy weather during crop season, the yield shall be decreased. Most scientists agree that the rate of heating is accelerating and temperature change could become increasingly disruptive. Weather patterns should also become more erratic. Agrometeorologists could be analyzed yearly variations of temperature, sunshine hour and rainfall pattern focused on transient agroclimate change for last a decade. Rice agronomists could be established taking advantage of real time agricultural meteorology information system for fertilization, irrigation, pest control and harvest. Also they could be analyzed the characteristics of flowering response of the recommended and newly bred rice cultivars for suitable cropping plan such as cultural patterns and sowing or transplanting date. Rice breeders should be deeply considered introducing the characteristics of basic vegetative type of flowering response like Tonsil rices as prospective rice cultivars corresponding to global warming because of the rices needed higher temperature at ripening stage than Japonica rices, photoperiod sensitive and thermo-sensitive ecotypes

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.10 no.6
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• pp.695-701
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• 1998

Researches on unused energy are being continued because of the limited fossil fuel and the destruction of environment. Therefore this study was peformed as follows. The collectable amount of exhausted heat for an air-conditioning was calculated by the subway thermal environment prediction program. And the electric power needed by conventional heat source equipments was compared with one by unused heat source equipments when the exhausted heat was used by heat pump in heating and hot water supplying. The results are summarized as follows; 1) Forced ventilation should be conducted to keep optimal temperature in subway tunnel in summer as well as in winter. According to the simulation, temperature in tunnel was higher than that on the ground in summer when the forced ventilation was conducted only in winter. 2) Ventilating time should be calculated out to the optimal condition for not only saving power of ventilation fan but reusing exhausted heat. By the simulation, it is certain that the exhausted heat should be eliminated in air-conditioning time. 3) The use of exhausted heat source heat pump could save 8% of electric power per hour in comparison with existing heat pump. It was based on a present heat generation and traffic for ventilating time of general air-conditioning, but could be different by ventilating time. 4) As the traffic increases up to 1.5 or 2 times, electric power consumption of the conventional heat pump increases to 11% or 13.5% per mean hour in comparison with that of the exhausted heat source heat pump, though all-day ventilation.

• Korean Chemical Engineering Research
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• v.43 no.6
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• pp.683-690
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• 2005

The microwave carbonization of rice chaff was performed, and their kinetics were compared to those of conventional thermal carbonization. Thermal carbonization was carried out at $300-600^{\circ}C$ for 30 minutes. The weight loss and C/H mole ratio remarkably increased as increase of temperature, while there was no carbonization by microwave dielectric heating in spite of increasing incident power and irradiation time. However, microwave carbonization was successfully performed by addition of 6 wt％ of thermal carbonized rice chaff, it's C/H mole ratio is larger than 3.0, as a catalytic initiator to uncarbonized rice chaff, and the kinetics was depended on the incident power and irradiation time, resulting in the coincide with thermal carbonization to the Arrhenius equation. The activation energy of microwave carbonization was quite low as compared to that of thermal carbonization, while the kinetic constant was large. This is due to the internal volumetric heating characteristics of carbonized rice chaff by microwave. The effect of ash, and C/H mole ratio and amount of carbonized rice chaff were investigated on microwave carbonization.

• Journal of Environmental Science International
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• v.19 no.3
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• pp.281-293
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• 2010

The present study explores time and spatial thermal environment for Daegu, which is a city built on a basin area, according to varying land cover conditions of the earth's surface by analyzing data derived from meteorological observation and satellite images. The study has classified land use by utilizing MODIS satellite images and analyzed land surface temperature. Also, by using data acquired from automatic weather system, the study has evaluated the effects of atmospheric heating caused by city pavements by analyzing the sensible heat flux between the city's land surface and the atmosphere. The results are as follows. 1) Classification of land use in the Daegu area shows 46.64% of urban and built-up area, 1.39% of watersides, 35.19% of forest, 11.43% of crops, and 5.37% grasslands. 2) During the weekdays throughout the year, the land surface temperature was high for Dalseogu, Bukgu, and Seogu regions where industrial complexes could be found. Comparatively, lower temperature could be observed in the woodlands. 3) While the land surface temperature displayed the effects of pushing air upwards during the weekdays in urban areas, the reverse was true for forest regions. During the night, the temperature did not exert any significant influence on air movement.

• Journal of the Korea Concrete Institute
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• v.15 no.4
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• pp.541-548
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• 2003

This study is to investigate the temperature curve and development of compressive strength due to the curing conditions and to evaluate the optimum curing condition of test specimens showing the same development of strength to that of real structures in cold weather. The results of temperature curve with curing conditions in mock-up tests showed the trend of decrease plain concrete with insulation form, plain concrete with heating, concrete with accelerator for freeze protection, and control concrete in turn. The strength development of plain concrete of inside and outside of shelter showed the very slow strength gains due to early freezing, but that of concrete with accelerator for freeze protection showed the gradual increase of strength with time. From this, it is clear that accelerator for freeze protection has the effects of reducing the freezing temperature and accelerating the hardening under low temperature. Strength test results of small specimens embedded in members and located in insulation boxes at the site are similar to that of cores drilled from the members at the same ages, thus it is clear that these curing methods are effective for evaluation in-place concrete strength.

• Nuclear Engineering and Technology
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• v.35 no.6
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• pp.529-536
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• 2003

The objective of this study is to investigate the reorientation of hydrides with applied stress intensity factor, the peak temperature and the time when to apply the stress intensity factor in a Zr-2.5Nb pressure tube during its thermal cycle treatment. Cantilever beam (CB) specimens with a notch of 0.5 mm in depth made from the Zr-2.5Nb tube were subjected to electrolytic hydrogen charging to contain 60 ppm H and then to a thermal cycle involving heating to the peak temperature of either 310 or $380^{\circ}C$, holding there for 50 h and then cooling to the test temperature of $250^{\circ}C$. The stress intensity factor of either 6.13 or $18.4\;MPa\sqrt{m}$ was applied at the beginning of the thermal cycle, at the end of the hold at the peak temperatures and after cooling to the test temperature, respectively. The reorientation of hydrides in the Zr-2.5Nb tube was enhanced with the increased peak temperature and applied stress intensity factor. Furthermore, when the CB specimens were subjected to $18.4\;MPa\sqrt{m}$ from the beginning of the thermal cycle, the reoriented hydrides occurred almost all over the Zr-2.5Nb tube, surprisingly suppressing the growth of a DHC crack. In contrast, when the CB specimens were subjected to the stress intensity factor at the test temperature, little reorientation of hydrides was observed except the notch region, leading the Zr-2.5Nb to grow a large DHC crack. Based on the correlation between the reorientation of hydrides and the DHC crack growth, a governing factor for DHC is discussed along with the feasibility of the Kim's DHC model.

• Journal of Korean Society for Atmospheric Environment
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• v.12 no.4
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• pp.369-376
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• 1996

Major atmospheric stability classification methods were evaluated with meteorological data obtained by scoustic sounding profiler (SODAR/RASS) in Seoul. The Psequill classificatio method, the method most widely used because of its good agreement in respect of synoptic scope under the steady state, fails to describe the time lag, the response time on stability by heating or cooling caused by daily insolation or noctrunal surface radiation. Horizontal and vertical standard deviation of wind fluctuation $(\sigma_A and \sigma_E)$ method tend to classify night-time stable condition (E, F class) into unstable condition (A, B class). The classification matrix tables for Vogt's vertical temperature difference and wind speed using method ($\Delta$T $\cdot$ U) and bulk Richardson number (Rb) were amended for practical use over Seoul. The modified tables for $\Delta$T $\cdot$ U and Rb method were made by using comprehensive frequency distribution from Pasquill's method and other existing results, and the correlation coefficient(r) was equal to 0.829. It was confirmed that atmospheric stability could be changed with monitoring site characteristics, height and vertical difference between sensors of monitoring station, and classification method itself.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.8 no.3
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• pp.508-512
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• 1998

The NTC thermistors were sintered by using microwave hybrid heating method at $1100^{\circ}C$~$1300^{\circ}C$ and those electrical properties were investigated. The obtained $B_{25^{\circ}C/85^{\circ}C}$ values from temperature dependence of electrical resisitivity were around 3100~3200 K which were almost the same values as conventionally sintered ones. Compared with conventional sintering process, this process could complete whole sintering process within 20 minutes. This the processing time and energy consumption could be reduced through this rapid heating by using microwave hybrid heating.t there were showed only two peaks, glycolide melting peak and lower molecular weight melting peak without lauryl alcohol. Conversion increased slowly with the reaction time up to 50 minutes, and then gave a sudden increase above that. The reaction time to disappear in glycolide melting peak during polymerization was shortened with the increase of lauryl alcohol content. Zero-shear viscosity of polyglycolic acid decreased with the increase of free acid content in glycolide.ssional energy and bending hysteresis increased. \circled3 Surface characteristics such as friction coefficient and thickness variation of highly shrinkage fabrics became relatively roughened state. \circled4 Since stiffened and roughened characteristics of highly shrinkage fabrics, drapabilities of them were significantly lowered. Additionally thermal insulation property of high shrinkage fabric was higher than that of low shrinkage fabric due to bulky and thickened feature. From the results, it is considered that the silk fabrics with high filling shrinkage have the good bulkiness and heat keeping properties and thus they have the suitable characteristics for high quality men's and women's formal garments.

• Journal of the Korean Dietetic Association
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• v.19 no.3
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• pp.236-252
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• 2013

The purpose of this study was to assess the microbiological quality of home-delivered meals during production and delivery for children from low-income families. Production flows from a facility in Seoul that provides home-delivered meals were analyzed and the time-temperature of the food was measured. Microbiological assessment was performed for the production environment, personal hygiene, and food samples at each production and delivery step based on the process approach. It took 2 hours or longer from completion of production to meal delivery. An aerobic colony count (ACC) and coliform were not detected at knives, cutting boards, and dish towels. However, ACC (at pre-preparation, preparation, and packing areas) and coliform (at the preparation area) were detected on the hands and gloves of employees. Air-borne bacterial counts varied according to day and preparation area (ND~6 CFU/plate/15 min). Food temperatures, on the completion of production and meal delivery, fell into temperature danger zones. ACC and coliform counts of raw ingredients did not decrease after pre-preparation (washing and sanitizing) for menus involving food preparation with no cook step. ACC decreased after cooking step for menus of food preparation with cook step, but the ACC of the stir-fried and seasoned dried filefish fillet on the completion of cooking was too numerous to count due to improper heating. The ACC of seasoned young Chinese cabbages (a menu with complex food preparation) increased during delivery (from 2.5 log CFU/ml to 5.0 log CFU/ml). This qualitative assessment of foodborne pathogens revealed that B. cereus was detected in vegetable and meat product menus. These results suggest time-temperature control is necessary during production and delivery and management guidelines during production of home-delivered meals are provided for safe production.

• 한국태양에너지학회:학술대회논문집
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• 2011.04a
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• pp.162-167
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• 2011

Thermal storage plays an important role in building energy saving, which is greatly assisted by the incorporation of latent heat storage in building materials. A phase change material is a substance with a high heat of fusion which, melting and solidifying at a certain temperature, can be storing and releasing large amount of energy. Heat is stored or released when the material changes from solid to liquid. Integration of building materials incorporating PCMs into the building envelope can result in increased efficiency of the built environment. The aim of this research is to identify thermal performance of PCMs impregnated building materials which is applied to interior of building such as gypsum and red clay. In order to analyze thermal performance of phase change materials, test-cell experiments and simulation analysis were carried out. The results show that micro-encapsulated PCM has an effect to maintain a constant indoor temperature using latent heat through the test-cell experiments. PCM wallboard makes it possible to reduce the fluctuation of room temperature and heating and cooling load by using EnergyPlus simulation program. Phase change material can store solar energy directly in buildings. Increasing the heat capacity of a building is capable of improving human comfort by decreasing the frequency of indoor air temperature swings so that the interior air temperature is closer to the desired temperature for a long period of time.