• Journal of Astronomy and Space Sciences
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• v.25 no.2
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• pp.129-138
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• 2008

This study attempts to show how the geomagnetic indices, AU, AL and Dst, respond to the interplanetary parameters, more specifically, the solar wind electric field VBz during southward interplanetary magnetic field (IMF) period. The AU index does not seem to respond linearly to the variation of southward IMF. Only a noticeable correlation between the AU and VBz is shown during summer, when the ionospheric conductivity associated with the solar EUV radiation is high. It is highly likely that the effect of electric field on the eastward electrojet intensification is only noticeable whenever the ionospheric conductivity is significantly enhanced during summer. Thus, one should be very cautious in employing the AU as a convection index during other seasons. The AL index shows a significantly high correlation with VBz regardless of season. Considering that the auroral electrojet is the combined result of electric field and ionospheric conductivity, the intensification of these two quantities seems to occur concurrently during southward IMF period. This suggests that the AL index behaves more like a convection index rather than a substorm index as far as hourly mean AL index is concerned. Contrary to the AU index, the AL index does not register the maximum value during summer for a given level of VBz. It has something to do with the findings that discrete auroras are suppressed in sunlight hemisphere (Newell et al. 1996), thus reducing the ionospheric conductivity during summer. As expected, the Dst index tends to become more negative as VBz gets intensified. However, the Dst index (nT) is less than or equal to 15VBz(mV/m) + 50(Bz < 0). It indicates that VBz determines the lower limit of the storm size, while another factor(s), possibly substorm, seems to get further involved in intensifying storms. Although it has not been examined in this study, the duration of southward IMF would also be a factor to be considered in determining the size of a storm.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.94-97
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• 2005

For the fabrication of poly-crystalline silicon ingot, CCCC (Cold Crucible Continuous Casting) method under a high frequency alternating magnetic field, was utilized in order to prevent crucible consumption and ingot contamination and to increase production rate. In order to effectively and continuously melt and cast silicon, which has a high radiation heat loss due to the high melting temperature and a low induction heating efficiency due to a low electric conductivity, Joule and pinch effects were optimized. Throughout the present investigation, poly-crystalline Si ingot was successfully produced at the casting speed of above 1.5 mm/min under a non-contact condition.

• KIEAE Journal
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• v.5 no.1
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• pp.11-18
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• 2005

The optimized HVAC system design in tall buildings enable owners to save unnecessary energy consumption and residents to have comfort environments. The purpose of this study is to develop design process for optimized HVAC system design in tall buildings. As basic researches, literature researches and case studies of HVAC system design in tall buildings were performed. Survey was processed among expert in the field and key considerations on HVAC system design were drew as conclusions. With these conclusions, studies were performed on effects of wind velocity, outdoor air temperature, and solar radiation that are main factors of load calculation in tall buildings. Finally, air-tightness and stack effect were analyzed and estimated by literature studies, field measurements and computer simulations.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.3
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• pp.277-284
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• 2005

The purpose of this study is to analyze the effect of sunshine on the heating energy consumption of apartment houses by a field investigation in Haeundae, Busan. In the field, heating energy consumption of every household is researched by reading a calorimeter and the duration of sunshine of every household is calculated by Sunlight V1.0. Then, the duration of sunshine and heating energy are done regression analysis by SPSS 10. According to this study the apartment houses by orientation spend more energies order of east, west, southeast, southwest, and south. When apartment houses are same orientation, there is difference of $29{\sim}58\%$ in heating energy consumption by the duration of sunshine. And the heating energy consumption in worst condition of sunshine increases $67\%$ on the best condition of sunshine.

• Journal of Korean Society for Atmospheric Environment
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• v.7 no.3
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• pp.169-179
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• 1991

Atmospheric $O_3$ in the biosphere is formed under the favourable meteorological condition, when the primary pollutants, such as $NO_2, HC, CO, CH_4$, etc., react with over constituents. Observed annual average concentrations for 1989 and 1990 were 11.8 and 10.4 ppb, respectively. THe number of days measured ozone over 80 ppb in Seoul were 36 in 1989 and 39 in 1990. In general, monthly maximum values occurred in May and August. In comparison with 1 $\sim$ 2 maxima of $O_3$ distribution in large cities in other countries, it was found that there were 3 $\sim$ 4 maxima in Seoul and its suburbs. Topographic effects, resulted by wind channelling in the Han River valley and by the blocking of air pollutants in the mountain, appeared to produce multiple centres of $O_3$ maxima in Seoul. Surface $O_3$ values were low with decreasing solar radiation, when the cloudiness increased and precipitation occurred. According to 12 cases examined, 2 cases shown here, $O_3$ values exceeding 80 ppb were occurred when the Korean peninsular was under the influence of the backside airflows with high intensity of solar radiation. Occasionally, sea breezes were observed to occur in warm seasons, and the chanelling effect of the Han River valley appeared to increase the general wind (speed) to the east side of Seoul. In this meso-scale situation $O_3$ in downwind is highly correlated with precursors. The sea breeze of 2 $\sim$ 4 m $s^{-1}$ will take 3 $\sim$ 5 hours to transport photochemical precursors for 20 $\sim$ 50 km. In turn the areas of maximum $O_3$ occurrence in Seoul are in the range of meso-scale transport of air pollutants.

• Journal of Korea Water Resources Association
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• v.44 no.9
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• pp.741-751
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• 2011

In this study, a methodology was devised to overcome that difficulty for thermal stratification modeling using EFDC. For the increase of reproductability for thermal stratification analysis, the effect of parameter such as distribution of solar radiation, depth of active bed temperature layer, heat transfer coefficients were analyzed. The simulation period was from June to December in 2005 and statistical index is used to analyze the model results. The results showed that distribution of solar radiation is zero and depth of active bed temperature layer is 10 m are suitable for simulation of thermal stratification in Yongdam Dam reservoir. This study results can be used for guideline to analyze the thermal stratification of large dam reservoir in Korea.

• Journal of Radiation Protection and Research
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• v.43 no.3
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• pp.114-119
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• 2018

Background: The retrospective dosimetry using RTL quartz can be improved by information for an optical sensitivity of sample connected with the equivalent dose determination. Materials and Methods: The quartz sample from a volcanic rock of Japan was used. After correcting the thermal quenching effect, RTL peaks of quartz were separated by the CGCD method cooperated with the general order kinetics. The number of overlapped glow peaks were ascertained by the $T_m-T_{stop}$ method. The optical sensitivity was examined by comparing the change of intensity on RTL glow peaks measured after exposure to light from a solar simulator with various illumination times. Results and Discussion: Seven glow peaks appeared to be overlapped on the RTL glow curve. The general order kinetics model was appropriate to separate glow peaks. After exposure to light from a solar simulator from a few minutes to 416 hr, the signals for peaks P4 and P5 decayed following the form of $f(t)=a_1e^{-{\lambda}1t}$, while the signals for peaks P6 and P7 decayed by the form of $f(t) = a_1e^{-{\lambda}1t}+a_2e^{-{\lambda}2t}+a_3e^{-{\lambda}3t}$. Conclusion: For dosimetric peaks, the times taken to reduce the RTL signal to half of its initial value were 70 sec for the peak P4, 54 s for the peak P5, 9,840 sec for the peak P6 and 26,580 sec for the peak P7, respectively. We conclude that the optical sensitivity of peaks P4, and P5 gives much higher than that of peaks P6 and P7.

• Solar Energy
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• v.12 no.3
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• pp.47-59
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• 1992

In the concentric tube type recuperator, which is the most typical type of radiation recuperator, installed on the exhaust-secion of industrial furnace, air flows between the adiabatic outer tube and the inner tube in which exhausted gas flows with high temperature. The waste heat of the exhausted gas is transferred to the inner tube, and transferred from the inner tube to the flowing air. The heat transfer by radiation In the concentric tube type recuperator is modeled using spherical harmonics approximation, namely, P-N method and numerically analyzed considering the effect of dynamic flow field. The results are compared with the existing empirical data. In addition, a theoretical method is presented for the analysis of the heat transfer characteristics of a recuperator with a reradiator installed in the inner tube, which causes re-radiant in the inner tube, and the characteristics of the recuperator is analyszed and defined.

• Korean Journal of Agricultural Science
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• v.49 no.4
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• pp.697-706
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• 2022

The effect of varied light intensities on the growth of daughter plants during propagation and after transplant to raised beds were examined in 'Sulhyang' strawberry. To this end, four treatments in controlling solar radiation inside a plastic house were made: 55% retractable shading and 35, 55, and 75% fixed shading. The plastic house was shaded only from 11:00 to 16:00 in June and 10:00 to 16:00 in July to September for the treatment of 55% retractable shading. The mean solar radiation inside the plastic house in the retractable 55% shading treatment was 317 W·m^-2 and those in the 35, 55, and 75% fixed shading treatments were 183, 165, and 116 W·m^-2, respectively, at 10 o'clock in the morning. The 55% and 75% fixed shading resulted in taller daughter plants with wider leaf areas than 55% retractable shading. The retractable shading also showed higher leaf numbers, crown diameters, root weights, and fresh weights compared to fixed shading treatments. Regarding the inorganic element contents, daughter plants grown under 75% fixed shading had 1.35% total nitrogen content followed by 1.19% in 35% fixed shading, 1.14% in 55% fixed shading, 1.14% in open culture, and 1.10% in 55% fixed shading. After 54 days following the transplant of daughter plants to a raised bed, the fresh weight of the aboveground part was the heaviest in the 55% retractable shading and non-shading treatments. The 75% fixed shading treatment had the lowest fresh weight of the aboveground plant parts. The results of this study could be used for the production of high-quality daughter strawberry plants.

• Journal of Bio-Environment Control
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• v.29 no.3
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• pp.306-312
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• 2020

This study was conducted to investigate cucumber plants response to greenhouse environments by solar shading in greenhouse in the summer. In order to estimate heat stress reduction of cucumber plants by solar shading in greenhouse, we measured and analyzed physiological conditions of cucumber plants, such as leaf temperature, leaf-air temperature, rubisco maximum carboxylation rate, maximum electron transport rate, thermal breakdown, light leaf respiration, etc. Shading levels were 90% mobile shading of full sunlight, 40% mobile shading of full sunlight and no shading(full sunlight). The 90% shading screen was operated when the external solar radiation is greater than 650 W·m^-2. Air temperature, solar radiation, leaf temperature, leaf-air temperature and light leaf respiration in the 90% shading of full sunlight was lower than those of 40% shading and no shading. Rubisco maximum carboxylation rate, arrhenius function value and light leaf respiration of the 90% shading were significantly lower than those of 40% shading and no shading. The thermal breakdown, high temperature inhibition, of 90% shading was significantly higher than that of 40% shading and no shading. Therefore, these results suggest that 90% mobile shading made a less stressful growth environment for cucumber crops.