• Journal of Energy Engineering
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• v.15 no.4 s.48
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• pp.235-242
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• 2006

This study experimentally investigates the performance improvement of the heat pump by adopting the hot gas bypass method and using the internal heat exchanger according to the automatic defrost test conditions of ISO 5151 This study compares the hot gas bypass method with the time step method, and investigates effect on outdoor coil fan speed when the hot gas of compressor outlet enter outdoor coil inlet after the frost formation. The tests were made for the fan speeds of the outdoor coil controlled at 90, 60 and 30% of the normal speed together with the case of the stationary fan. The performance of the heat pump is evaluated by variables such as COP, heat capacity, and the average COP during the 210 minutes heating mode. Results show that average COP of the hot gas bypass mettled is $2.2{\sim}6%$ higher than that of the time step method. When the outdoor coil fan speed is 60% (780 rpm) of the normal speed, it shows the best COP and heating capacity.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.5
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• pp.2545-2552
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• 2014

This study is aiming to suggest the effective thermal management system design technologies for the high voltage and capacity battery system of the electricity driven vehicles and introduce the theoretical designing methods. In order to investigate the effective operation of the battery system for the electricity driven vehicles, the heat generation model for Li-ion battery system using the chemical reaction while charging and discharging was suggested and the thermal loads of the heat sources (air or liquid) for cooling and heating were calculated using energy balance. Especially, the design methods for the cooling and heating of the battery system for maintaining the optimum operation temperature were investigated under heating, cooling and generated heat (during charging and discharging) conditions. The battery thermal management system for the effective battery operation of the electricity driven vehicles was suggested reasonably depending on the variation of the season and operation conditions. In addition, at the same conditions under summer season, the cooling method using the liquid and active cooling technique showed a relatively high capacity, while cooling method using the passive cooling technique showed a relatively low capacity.

• Journal of the Korean Geotechnical Society
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• v.33 no.2
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• pp.35-47
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• 2017

Thermal behavior of soils is mainly focused on thermal conduction, and the study of natural convection is very limited. Increase of soil temperature causes natural convection due to buoyancy from density change of pore water. The limitations of the analysis using fluid dynamics for natural convection in the porous media is discussed and a new numerical analysis is presented for natural convection in porous media using THM governing equations fully coupled in the macroscopic view. Numerical experiments for thermal probe show increase in the uncertainty of thermal conductivity estimated without considering natural convection, and suggest appropriate experimental procedures to minimize errors between analytical model and numerical results. Burial of submarine power cable should not exceed the temperature changes of $2^{\circ}C$ at the depth of 0.2 m under the seabed, but numerical analysis for high permeable ground exceeds this criterion. Temperature and THM properties of the seafloor are important design factors for the burial of power cable, and in this case effects of natural convection should be considered. Especially, in the presence of heat sources in soils with high permeability, natural convection due to the variation of density of pore water should be considered as an important heat transfer mechanism.

• Journal of the Korean Geotechnical Society
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• v.33 no.11
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• pp.45-57
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• 2017

Temperature change affects consolidation behavior of soft clays. The increase of temperature in soft clays induces the increase of pore water pressure. The dissipation of the excess pore water pressure decreases volume and void ratio. Also, the consolidation rate is accelerated by high temperature which induces the decrease of viscosity of pore fluid. The effects of temperature on the consolidation behavior such as consolidation settlement, consolidation time, and pore water pressure were investigated in this study. A numerical analysis of hydro-mechanical (HM) and thermo-hydro-mechanical (THM) behavior was performed. The combination of heat injection and sand drain for consolidating the soft ground, with varying temperature (40 and $60^{\circ}C$) and sand drain diameter (40, 60, and 80 mm), was considered. The results show that the temperature inside soil specimen increases with the increase of the temperature of heating source and the diameter of sand drain. Moreover, the heat injection increases the excess pore water pressure and, accordingly, induces additional settlement in overconsolidated (OC) state and reduces the consolidation time in normally consolidated (NC) state.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.1158-1161
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• 2004

This paper presents structural characteristics of station class lightning arresters and electrical characteristics of manufactured ZnO varistor blocks which are usable in those arresters. Three types of station class lightning arresters were investigated and those are a ceramic arrester, a FRP tube type polymer arrester, and a FRP rod type polymer arrester. Each arrester has merits and demerits with structural characteristics. In general, polymer arresters were made of silicon rubber for housing materials, FRP tube or rod for mechanical strength, ZnO blocks for electrical characteristics, and metal parts for electrical contact and the silicon rubber, the housing materials, was directly injected to the arrester module which was assembly composed of electrodes, ZnO blocks and FRP tube or rod, and to prevent the nonlinear electric fields distribution on upper parts of arresters, the grade ring was adopted to the upper electrodes. The reference voltage, nonlinear coefficient, residual voltage, and voltage ratio of manufactured ZnO varistors are 4.90kV, 50, 9.54kV, 1.94, respectively. Compared to designed electrical characteristics, the reference voltage was low for 600v and the voltage ratio was slightly high. However, the characteristics of discharge withstand was so excellent that the mechanical destruction does not occur at the impulse current of $8/20{\mu}s$ 10kA for 100 times.

• Anxiety and mood
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• v.4 no.1
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• pp.62-67
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• 2008

Objectives : Gender differences in demographic characteristics, symptom presentation, and severity may influence the selection of target behaviors as well as the course and outcome of therapeutic interventions for patients with social phobia. The purpose of this study was to explore the gender differences in the symptomatic characteristics of Korean patients with social phobia. Methods : A total of 256 outpatients with social phobia at Kangbuk Samsung Hospital were included in this study. All subjects were evaluated using the Korean version of the MINI International Neuropsychiatric Interview Plus. Potential differences in demographic characteristics, severity of anxiety, and situational fear and avoidance were examined. Self-report questionnaires and interviewer-administered instruments, including the Social Phobia Scale (SPS), Social Phobia subscale of the Fear Questionnaire (FQ-social), Appraisal of Social Concerns (ASC), and Liebowitz Social Anxiety Scale (LSAS), were used to evaluate the severity of the patients' symptoms. Results : There were no gender differences in demographic characteristics, age, age at onset of social phobia, total SPS score, FQ-Social score, ASC score, and LSAS score. In addition, there was no gender difference in the severity of fear in specific social situations. However, women reported significantly higher total scores on the social helplessness category of the ASC than men (p=0.009). Conclusion : Previous studies reported that the severity of social phobia symptoms is greater in women than in men, but our results suggest that there are no significant gender differences in the severity of social phobia symptoms. Thus, gender differences among patients with social phobia are discussed in the context of traditional sex-role expectations.

• Journal of the Korean Magnetics Society
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• v.25 no.5
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• pp.144-148
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• 2015

We grew spinel structured $CoMn_2O_4$ thin films and have studied post-growth annealing effects on their physical properties. After post-growth annealing at $700^{\circ}C$ that is lower than the growth temperature ($720^{\circ}C$), crystal structure became cleared accompanying a change of surface structure. In the temperature dependences of magnetization, phase transitions were observed at ~100 K for both before and after post-growth treated samples which were not observed for the bulk. For both samples, ferromagnetic behaviors were observed above 100 K while it turned to ferrimagnetism at low temperature below 100 K. In particular, the ferrimagnetic behavior became strong after the post-growth treatment. These results indicate that the post-growth annealing process plays an important role in determining the physical properties of spinel $CoMn_2O_4$ thin film.

• Korean Journal of Soil Science and Fertilizer
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• v.21 no.1
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• pp.15-19
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• 1988

Heat energy distribution forming net radiation above corn canopy was determined by means of the Bowen ratio-energy balance method. Total-global solar radiation above crop canopy during the growing season was $1,559MJm^{-2}$ and total latent heat flux density was $960MJm^{-2}$. The data showed that 61.6% of the global solar radiation was used for a heat source of evapotranspiration (ETa) above corn canopy. Mean daily ETa ranged from 2.7 to 5.6mm. Total ETa, total drymatter, and water use efficiency were 394mm, $2,214gm^{-2}$, and $5.6gm^{-2}mm^{-1}$, respectivively.

• The Journal of the Society of Stroke on Korean Medicine
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• v.20 no.1
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• pp.17-24
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• 2019

■ Objectives The purpose of this case report is to show the effect of Bojungiki-tang on a patient complaining dysuria and urinary pain caused by repeated urinary tract infection(UTI) occurred after onset of cerebral infarction. ■ Methods A cerebral infarction patient with repeated UTI was treated with herbal medication, Bojungiki-tang. Then we evaluated the improvement with amount of total urine output, nelaton catheterization urine output and self voiding urine output. ■ Results Increase in amount of total and self voiding urine output and decrease in amount of nelaton urine output were observed after taking Bojungiki-tang. ■ Conclusion This case showed the effect of Bojungiki-tang on dysuria and urinary pain caused by repeated UTI.

• The Journal of the Society of Stroke on Korean Medicine
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• v.21 no.1
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• pp.11-20
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• 2020

■ Objectives The purpose of this study is to report on a case that showed improvement in type 2 diabetic patients by using herbal medicine, Yeoldahansotang-gami. ■ Methods Yeoldahansotang-gami was given to patients with type 2 diabetes for 71days. To evaluate the effect, blood glucose was measured 4 times a day. As measured blood sugar, the frequency of hyperglycemia, changes in fasting blood sugar, changes in postprandial blood sugar, and changes in glucose variability were analyzed. The patient's insulin injection dose change was observed, and HbA1c and glycated albumin were measured. Follow-up was performed for 7 months to observe whether the treatment effect was maintained. ■ Results During treatment, the patient's blood sugar control, glucose variability, and HbA1c were improved, and insulin injection dose was gradually reduced and stopped. HbA1c and glycated albumin levels maintained improvement without insulin injection during the follow-up period. ■ Conclusion This study showed the effect of yeoldahansotang-gami on type 2 diabetes patient.