• Smart Structures and Systems
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• v.17 no.4
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• pp.631-646
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• 2016

Although the deployment of wireless sensors for structural sensing and monitoring is becoming popular, supplying power to these sensors remains as a daunting task. To address this issue, there have been large volume of ongoing energy harvesting studies that aimed to find a way to scavenge energy from surrounding ambient energy sources such as vibration, light and heat. In this study, a magnetic resonance based wireless power transfer (MR-WPT) system is proposed so that sensors inside a concrete structure can be wirelessly powered by an external power source. MR-WPT system offers need-based active power transfer using an external power source, and allows wireless power transfer through 300-mm thick reinforced concrete with 21.34% and 17.29% transfer efficiency at distances of 450 mm and 500 mm, respectively. Because enough power to operate a typical wireless sensor can be instantaneously transferred using the proposed MR-WPT system, no additional energy storage devices such as rechargeable batteries or supercapacitors are required inside the wireless sensor, extending the expected life-span of the sensor.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.21 no.12
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• pp.703-714
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• 2009

One of the biggest problems in smoke control systems for high-rise buildings is stack effect, but there are no recognized methods or measures to solve the problem of stack effect as yet. The stack effect can be overcome by forming the uprising current inside the stair hall properly, but there is a limit to the height in supplying into the stair hall the smoke control air volume to be supplied to a floor in case of escape from fire. The limit to the height can be extended by over-coming the stack effect by pressurizing the stair hall and the ancillary room simultaneously. It can also be anticipated that the stack effect can be overcome by connecting the air supply shaft to the stair hall at the top. As a result of computer simulations using a network type of tool, it is found that adequate performance can be achieved by pressurizing the stair hall only for a building of 190m or less, and up to 360m when pressurizing the stair hall and the ancillary room simultaneously. In all those cases, however, an overpressure venting damper is required which operates within a suitable range for venting the overpressure outside.

• Journal of the Korean Institute of Gas
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• v.23 no.2
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• pp.61-67
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• 2019

Korea is natural gas importer which imports a lot quantities which 20% of the volume of US exports in 2018. Biogas which can satisfy gas demand and respond effectively to climate change, will be an alternative. However, only 20% of biogas production is sold, which is also not efficient and difficult to use. The purpose of this study develops an optimal purification system for supplying biogas as city gas. We develope an optimal system by analyzing biogas for system selection, finding cases for system design, developing scenario, and developing a cost - benefit tool.

• Journal of Astronomy and Space Sciences
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• v.25 no.3
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• pp.299-320
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• 2008

We study on the astronomical calendars that was used in the Silla era. The calendars are deduced from the records in Samguksagi. They were influenced from calendaric system of Tang Dynasty, which are Lin duk calendar(麟德曆), Ta yen calendar(大衍曆) and Sun myung calendar(宣明曆). We analyse them in detail according to the time and duration of use. Water clock system of Unified Silla was used four water vessels for supplying water. We found the model from documents on ancient water clock that are appeared in the old Korean, Chinese and Japanese historical records. We have assumed the model of Unified Silla clepsydra is similar type with Chinese records during Tang dynasty and with Japanese reconstructed water clock in Temple Asoka. After fluid dynamic experiment, we decide the suitable diameter of supplying pipe and volume of the vessels used in the clepsydra. We introduce the experimental instruments and methods for accomplishing the clock. We designed and reconstructed the water clock of Unified Silla and float rods for measuring time, that is based on the Silla's calendaric system.

• Membrane Journal
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• v.10 no.4
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• pp.192-197
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• 2000

Gas permeation and separation characteristics of ozone treated polysulfone (PSF) membranes were investigated. The PSF is one of the most widely used commercial membranes. Ozone treatment of the PSF membrane was performed for certain hours by continuously supplying 5 vol.% ozone-containing oxygen to the chamber, in which the membrane samples were charged. The permselectivity of PSF increased with ozone treatment time, and it was found that one and half hour was enough to ozone treatment. Increase in the selectivity of the membrane for He/$N_2$, HY$N_2$, O:J$N_2$, COJ$CH_4$ by ozone treatment was found to be due to decrease in the permeability of gases with larger molecular size such as $N_2$ and $CH_4$ The decrease in the permeability of gases with smaller molecular size was negligible. The increase in the selectivities of the PSF by ozone treatment would be due to decrease in the free volume of the polymer because of the oxygen complexes generated by the reaction between ozone and the polymer.

• Archives of Reconstructive Microsurgery
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• v.9 no.2
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• pp.172-178
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• 2000

With esthetic concern in the reconstruction of skin and soft tissue defects of face, the use of local flap has been the method of choice. However, when there is extensive tissue loss in the face, local flaps do not provide satisfactory results. The amazing development of microsurgical technique has decreased the percentage of free flap failure, thus making free flap use in reconstruction of facial soft tissue defects. Many free flaps has been applied for reconstruction of face defects. Especially, the radial forearm flap has numerous advantages with which facial reconstruction is made possible. But, its disadvantages are ; the sacrifice of one major artery supplying the hand and donor site complications. In order to circumvent these disadvantages, we employed posterior interosseous artery(PIA) forearm free flap for the reconstruction of the face defects. The posterior interosseous forearm island flap was first described by Zancolli and Angrigiani(1985). Currently, the PIA island flap and free flap have been used for hand reconstructions. The disadvantages of the PIA flap are ; the small caliber of the pedicle, different locations of the perforating branches, and the proximity of the motor branch of the radial nerve. But, its advantages lies in preserving the major artery of the hand, minimal donor site morbidity, and fairly well matched skin texture and color, and that the flap volume is sufficient, not too bulky with convenient handling. By using this flap, we performed 1 case of tumor resection and 1 case of traumatic defect. From our experiences we conclude that it is one of many useful methods in the reconstruction of the skin and soft tissue defects of the face. We also have discussed advantages and some limitations of various free flaps for reconstruction of the face.

• Journal of Physiology & Pathology in Korean Medicine
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• v.18 no.6
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• pp.1860-1868
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• 2004

Geijibokryunghwan has a wide range of therapeutic applications, and some reports have indicated that it has protective activity against atherosclerosis, and more specifically stroke and myocardial infarction. A recent report showed that atherosclerotic plaque volume can be reduced by supplying Geijibokryunghwan extracts for several years. In this study, we used a component of Geijibokryunghwan, which has been used for the prevention of atherosclerosis in Korea for several years, and has proven to be useful in lowering the occurrence of cerebral infarction. In a preliminary study, we found that Geijibokryunghwan potently suppressed platelet aggregation induced by various agonists. In this study, we sought to explore the mechanism by which Geijibokryunghwan inhibits platelet aggregations.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.286-286
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• 2009

A small PEM fuel cell has two different stack configurations such as active and passive stacks. The active stack has a distintion of high power density although it makes system complex by using alr blower and related BOPs resulting in large system volume. On the contrary, passive stack has an advantage of compact system because it doesn't need air supplying devices although it reveals relatively low stack power density. In this study we fabricated two 10W PEMFC stacks with different stack configurations, active and passive stacks, and tested their performance and stability. The active stack consists of 13cells with an active area of $5cm^2$. The passive stack has 12cells with an active area of $16cm^2$. When we compared the stack performance of those stacks, the active stack showed higher power density compared to the passive stack, particularly at high voltage regions. However, at low voltage and high current regions, the passive stack performance was comparable to the active stack. The stack stability was largely dependent on the fuel humidity, particularly for active stack. At low humidity conditions, the active stack performance was decreased continuously and the cell voltage distribution was not uniform showing seriously low cell voltage at center cells mainly due to the cell drying. The passive stack showed relatively stable behavior at low humidity and the stack performance was largely dependent on the atmospheric conditions.

• Asian-Australasian Journal of Animal Sciences
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• v.19 no.5
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• pp.734-738
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• 2006

The present study was conducted to determine the effect of cold stress on broiler performance and ascites susceptibility. Male chicks were obtained from a commercial strain of broiler breeders. The trial was divided into two treatments (control and cold stress groups). Ascites was induced in broiler chickens in the trial by exposing the chickens to low temperature (Ta) and by supplying a pelleted diet. The two experimental treatments consisted of: 1) Control group, $33.3^{\circ}C$ the $1^{st}$ wk, $30.2^{\circ}C$ the $2^{nd}$ wk, and $27.5^{\circ}C$ the $3^{rd}$ wk. 2) Cold stress group, $29.0^{\circ}C$ the $1^{st}$ wk, $26.4^{\circ}C$ the $2^{nd}$ wk, and $23.1^{\circ}C$ the $3^{rd}$ wk. From the end of the $3^{rd}$ wk all broilers were reared to 6 wk of age at a constant temperature of $21^{\circ}C$. There was significant difference in live BW during wk 1 to 5. The control group was consistently the heaviest; however, at 6 wk of age, both groups weighed the same. Body weight gain up to 3 wk was significantly decreased by cold stress. During wk 3 and 6 the chicks in the cold stress group had greater BW gain compared with the chicks in the control group. There were significant differences in mortality due to ascites between the groups. During wk 3 and 6 the cold stress group exhibited the most ascites mortality (9.52%) when compared with the control group (1.90%). At 5 wk of age cold stress condition caused significant changes in packed cell volume (PCV), hemoglobin (Hb) and red blood cell counts (RBC). Right ventricle weight was significantly heavier in the cold stress group than the control. There were also significant differences in right ventricle/total ventricle (RV/TV) ratios at 5 wk. the right ventricle/total ventricle ratios in the cold stress group was higher (0.25) than the control group (0.20). It was concluded that, fast growth and cold temperatures are the primary triggers for ascites during commercial broiler production.

• Plant Journal
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• v.10 no.4
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• pp.35-41
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• 2014

The height and capacity of the thermal storage tank can be decided by the altitude and heat load of the heat supply area. Evaporation in heat pipe can be prevented by pressurizing it with the hydraulic head of the thermal storage tank. In addition, it absorbs the expanded volume from the temperature changes and supplies water to the pipelines in case of the shortage of water. One of the most important roles of the thermal storage tank is a stable heat supply facility. It can control the heat demand by accumulating the surplus heat and supplying in changing heat demand time. The purpose of this thesis is to be helpful for the operation and maintenance of the thermal storage tanks. The study has been carried out for 18 thermal storage tanks, which have been used polyurethane foam as insulation, among 27 tanks in district heating plants. The characteristics of the insulation materials, the reasons for the damages of the insulation and how impact the insulation damages to the corrosion of the thermal storage tank have been studied.