• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.05a
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• pp.74-77
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• 2000

The main objective of this paper is to design and test a new type of polymer ZnO surge arrester for AC power system of railroad vehicles. Metal oxide surge arrester for most electric power system applications, electric train and must not have explosive breakage of the housing to minimize damage to other equipment when subjected to internal high short circuit current. When breakdown of ZnO elements in a surge arrester occurs due to flashover, fault short current flows through the arrester and internal pressure of the arrester rises. The pressure rise can usually be limited by fitting a pressure relief diaphragm and transferring the arc from the inside to the outside of the housing. However, there is possibility of porcelain fragmentation caused by the thermal shock. pressure rise, etc. Non-fragmenting of the housing is the most desired way to prevent damage to other equipment. The pressure change which is occurred by flashover become discharge energy. This discharge energy raises to damage arrester housing and arrester housing is dispersed as small fragment. Therefore, the pressure relief design is requested to obstruct housing dispersion. The main research works are focused on the structure design by finite element method, pressure relief of module, and studies of performance of surge arrester for electric railway vehicle.

• Genomics & Informatics
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• v.4 no.2
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• pp.71-76
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• 2006

We have investigated biological responses to radiofrequency (RF) radiation in in vitro and in vivo models. By measuring the levels of heat shock proteins as well as the activation of mitogen activated protein kinases (MAPKs), we could not detect any differences upon RF exposure. In this study, we used more sensitive method to find the molecular responses to RF radiation. Jurkat, human T-Iymphocyte cells were exposed to 1763 MHz RF radiation at an average specific absorption rate (SAR) of 10 W/kg for one hour and harvested immediately (R0) or after five hours (R5). From the profiles of 30,000 genes, we selected 68 differentially expressed genes among sham (S), R0 and R5 groups using a random-variance F-test. Especially 45 annotated genes were related to metabolism, apoptosis or transcription regulation. Based on support vector machine (SVM) algorithm, we designed prediction model using 68 genes to discriminate three groups. Our prediction model could predict the target class of 19 among 20 examples exactly (95% accuracy). From these data, we could select the 68 biomarkers to predict the RF radiation exposure with high accuracy, which might need to be validated in in vivo models.

• Reproductive and Developmental Biology
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• v.33 no.3
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• pp.183-187
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• 2009

This study analyzed change of proteins in granulosa cells during the porcine follicuar development by proteomics techniques. Granulosa cells of the follicles, of which the diameter is $2{\sim}4\;mm$ and $6{\sim}10\;mm$, were collected from ovary of slaughtered pig that each follicle of diameter $1{\sim}4\;mm$ and $6{\sim}10\;mm$. We extracted glanulosa cell proteins by M-PER Mammalian Protein Extraction Reagent. Proteins were refined by clean-up kit and quantified by Bradford method until total protein was $200{\mu}l$. Immobilized pH gradient(IPG) strip used 18 cm, $3{\sim}10\;NL$. SDS-PAGE used 10% acrylamide gel. After silver staining, Melanie 7 and naked eye test were used for spot analyzation. Increasing proteins in glanulosa cell of $6{\sim}10\;mm$ follicle were 7 spots. This spots were analyzed by MALDI-TOF MS and searched on NCBInr. In results, 7 spots were similar to zinc/ling finger protein 3 precursor (RING finger protein 203), angiomotin, heat shock 60 kDa protein 1 (chaperonin) isoform 1 (HSP60), similar to transducin-like enhancer protein 1 (TLE 1), SH3 and PX domains 2A (SH3PXD2A). Those proteins were related with transfer between cells. Increase of proteins has an effect on follicular development.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.10
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• pp.1017-1026
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• 2009

The solar cell system operates by facing the sun-light. Minor cracks, static discharge, and thermal shock that can happen during production/testing phase can lead to degradation in performance during operation, since solar cells are exposed to extreme thermal/mechanical environment in space. In order to detect small cracks and internal damages in the solar cells due to thermal shocks, which are the core units of a solar cell system, expensive equipment, complicated test process, and much time are required. Therefore, a qualitative method for easily and quickly testing the 'health' of solar cell functionality is required. This dissertation describes a theoretical and technical grounds for quickly and easily evaluating the health of solar cells using electroluminescence effect of Gallium-Arsenide solar cells that are most widely used by spacecrafts in recent years. Also described in the dissertation is the technical issues and constraining factors for applying the proposed method to actual space-rated solar cell systems.

• International Journal of Automotive Technology
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• v.6 no.2
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• pp.149-159
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• 2005

A full nonlinear finite element P185/70Rl4 passenger car radial-ply tire model was developed and run on a 1.7-meter-diameter spinning test drum/cleat model at a constant speed of 50 km/h in order to investigate the tire transient response characteristics, i.e. the tire in-plane free vibration modes transmissibility. The virtual tire/drum finite element model was constructed and tested using the nonlinear finite element analysis software, PAM-SHOCK, a nonlinear finite element analysis code. The tire model was constructed in extreme detail with three-dimensional solid, layered membrane, and beam finite elements, incorporating over 18,000 nodes and 24 different types of materials. The reaction forces of the tire axle in vertical (Z axis) and longitudinal (X axis) directions were recorded when the tire rolled over a cleat on the drum, and then the FFT algorithm was applied to examine the transient response information in the frequency domain. The result showed that this PI 85/70Rl4 tire has clear peaks of 84 and 45 Hz transmissibility in the vertical and longitudinal directions. This result was validated against more than 10 previous studies by either theoretical or experimental approaches and showed excellent agreement. The tire's post-impact response was also investigated to verify the numerical convergence and computational stability of this FEA tire model and simulation strategy, the extraordinarily stable scenario was confirmed. The tire in-plane free vibration modes transmissibility was successfully detected. This approach was never before attempted in investigations of tire in-plane free vibration modes transmission phenomena; this work is believed to be the first of its kind.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.93-94
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• 2007

An essential step for SERGI is to show the TRANSFORMER PROTECTOR (TP) efficacy for all transformers and all types of rupture of insulation. Its research program philosophy is thus to maintain a strong connection between experiments and the theoretical developments. Up to now, two TP test campaigns have been performed, both under the worst conditions by creating low impedance faults leading to electrical arcs inside the transformer tank dielectric oil. In 2002, Electricite de France performed 28 TP tests. Then, in 2004, a second campaign of 34 TP tests was carried out by CEPEL, the Brazilian independent High Voltage Laboratory. For the 62 tests, each transformer was equipped with the TP, which reacts directly to the moving dynamic pressure peak, shock wave, caused by the low impedance fault. When an electrical arc occurs, only one pressure peak is generated. The initial energy transfer is almost instantaneous, and so is the phase change. Because of the oil inertia, the gas is very quickly pressurised. As it is more difficult to vaporise a liquid than to crack oil-vapour into smaller molecules, the arc location would mainly remain in the gaseous phase after and less gas will be produced. As a result, when comparing tests for which pressure peaks are respectively equal to 8 bar (116 psi) and 8.8 bar (127 psi), the corresponding arc energies vary by an order 10 of magnitude (0.1 MJ and 1 MJ respectively). The correlation of the results obtained between arc energy and dynamic pressure demonstrates that the arc energy is not the key parameter during transformer tank explosion, which is in opposition with the common electrical engineers belief.

• Korean Journal of Applied Biomechanics
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• v.22 no.4
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• pp.379-386
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• 2012

The aim of this study was to investigate and identify the differences in lower extremity energy dissipation strategies between drop-landing and countermovement-jump maneuvers. Fourteen recreational athletes(Age : $23.3{\pm}2.1years$, Height : $172.3{\pm}4.0cm$, Weight : $69.2{\pm}4.7kg$) were recruited and instructed to perform drop-landing from 45 cm height and countermovement-jump from 45 cm to 20 cm height. The landing phase was taken as the time between initial contact and peak knee flexion. A motion-capture system consisting of eight infra-red cameras was employed to collect kinematics data at a sampling rate of 200 Hz and a force-plate was used to collect GRF data at a sampling rate of 2000 Hz. Paired t-test was performed to determine the difference in kinematics and kinetics variables between each task. During the countermovement-jump task, all of lower extremity joint ROM and the hip joint eccentric moment were decreased and the ankle joint plantarflexion moment was increased than drop-landing task. In the eccentric work during countermovement-jump task, the ankle joint displayed greater while knee and hip joint showed lesser than drop-landing. Therefore, the knee joint acted as the key energy dissipater during drop-landing while the ankle joint contributed the most energy dissipation during countermovement-jump. Our findings collectively indicated that different energy dissipation strategies were adopted for drop-landing and countermovement-jump.

• The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
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• v.30 no.1
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• pp.74-86
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• 2017

Objectives : This study aimed to assess the scientific evidence for the use of Hwanglyeonhaedok-tang, a traditional herbal formula, in the treatment of rhinitis, and prepare the basis for the investigational new drug application by analyzing the experimental studies. Methods : Ten electronic databases were searched up to December, 2016 without language limitation. Experimental studies on the anti-inflammatory and anti-allergic effects of Hwanglyeonhaedok-tang against rhinitis were included. We extracted data about study design, characteristics of intervention, outcomes, and pharmacological effects from the included studies and summarized them. Results : Eight hundred and thirty-three potentially relevant studies were identified, of which 18 experimental studies met our inclusion criteria. Of 18 included studies, 5 had conducted cell viability test, and all studies had reported that Hwanglyeonhaedok-tang was non-cytotoxic. Hwanglyeonhaedok-tang exhibits anti-inflammatory effect by regulating the inflammation-related cytokines including nitric oxide(NO), prostaglandin $E_2(PGE_2)$, interleukin-6(IL-6), and tumor necrosis $factor-{\alpha}(TNF-{\alpha})$ in vitro and in vivo. Hwanglyeonhaedok-tang exhibits anti-allergic effect by suppressing eosinophil, and histamine levels. Hwanglyeonhaedok-tang helps in the recovery of nasal mucous membrane by supressing goblet cells, heat shock protein 70, and substance P. Conclusions : This study suggests that Hwanglyeonhaedok-tang has the potential to be developed as therapeutic agent for rhinitis. Further experimental and clinical studies needed to be performed to prove the safety and efficacy.

• Journal of Chest Surgery
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• v.25 no.7
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• pp.693-701
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• 1992

Extracorporeal cardiopulmonary bypass[CPB] has been associated with a wide variety of hematologic derangements, including a transient deformation and hemolysis of red blood cells[RBCs], which is supposed to be due to mechanical trauma and/or metabolic alterations. Since membrane integrity is, in part, maintained by energy requiring process, inadequate function of erythrocyte glycolytic pathway, which is inevitalble during CPB, may cause depletion of high energy phosphate pool and result in hemolysis. The authors performed an investigation to assess whether administration of Fructose-l, 6-diphsphate [FDP], which has been known to enhance intracellular glycolytic activities, could counteract erythrocyte hemolytic events caused by CPB. Sixty pateints with cyanotic congenital heart diseases, who underwent open heart surgery under CPB longer than 60 minutes, were randomly divided into two groups depending on whether use of FDP[Group FDP] or not[Group Control]. The age, sex, CPB time, preoperative hemoglobin level, disease entities were all similar[Table 1], and membrane type oxygenators were used in all patients. In Group, FDP, a dose of 250mg/kg body weight of FDP was administered by intravenous dripping every 12 hours from the morning of the operation to postoperative 48 hours, To demonstrate the degree and pattern of hemolysis of erythrocyte, reticulocyte count, indirect /direct bilirubin, haptoglobin, plasma hemoglobin, lactate dehydrogenase were measured every 12 hours from the time of cessation of CPB to 48 hours and RBC morphologic study, osmotic fragility test were done every 24 hours. All parameters revealed less hemolytic in group FDP [Fig. 1~5], though the differences between two groups were not significant, except plasma hemoglobin, lactate dehydrogenase changes. A pattern of sequential changes of plasma hemoglobin, lactate deh-ydrogenase showed the highest level at the time of CPB stop and abrupt decrease in following 24 hours in both groups, and statistically significant differences were demonstrated in group FDP at least for the first 12 hours postoperatively[p<0.05]. The authors conclude that they can expect the benificial effect of FDP on the maintenance of membrane stability of RBC probably by energy enhancement during the shock status of CPB, but FDP could not completely prevent the damaging effect on RBC by cardiopulmonary bypass

• Korean Journal of Microbiology
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• v.38 no.3
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• pp.168-172
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• 2002

Budding yeasts maintain an effective system to regulate intracellular pH in response to environmental pH fluctuation. In a previous study we reported that SHC1 plays a role in cell growth at alkaline condition, not at acid pH. We constructed a null mutant deleted an entire open reading frame for SHC1. To test whether the retardation in cell growth was caused by the absence of intracellular pH buffering capacity, we measured intracellular pH with a pH-sensitive fluorescent dye, C.SNARE. The intracellular pH of the mutant cell was much higher than that of wild-type cells, indicating that the mutant cells lack some types of buffering capacity. We also investigated the level of $Na^＋ and K^＋$ content with atomic mass spectroscopy after alkali shock. Wild-type cell showed a higher level of intracellular K^＋$ content, whereas there was no difference in $Na^＋$ level. The result suggested that K^＋$ is more important in the regulation of intracellular pH in yeasts.