• Proceedings of the Korean Society of Applied Pharmacology
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• 2003.11a
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• pp.113-113
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• 2003

A number of studies have demonstrated recently nonthermal interactions of extremely low frequency electromagnetic fields with cellular systems, such as the cells of the immune system. Particular concern came from epidemiological findings, which correlated environmental exposure of human body to weak electromagnetic fields with an elevated risk for developing certain type of leukemias and cancers. Several home/environmental sources generating extremely low frequency electromagnetic fields, such as 50 - 60 Hz high-voltage transmission lines, video display terminals, electric blankets, clinical nuclear magnetic resonance imaging procedures, etc., may interact with the human body. In this study we examined the effects of static magnetic fields (SMF) on the phagocytosis of the murine peritoneal macrophages (C57BL/6). The cells were exposed in vitro for 24 h at 37$^{\circ}C$ to 400 G SMF. The phagocytic activity of peritoneal macrophages was determined with a luminometer. Exposure to the SMF decreased phagocytic activity of murine peritoneal macrophages. In order to provide a more exact mechanism of the phenomenon, we analyzed peritoneal macrophages for alteration in their proteomes. The expression levels of these 5 proteins were increased in the SMF. In total 5 proteins which were differentially expressed in the SMF compared with control group were identified. The expression levels of these 5 proteins were increased in the SMF.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.2204-2205
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• 2008

2005년도에 저압 지중함에서 감전사고가 발생한 후 감전예방을 위한 다양한 개선대책이 현장에 적용되었다. 사고발생 직후에는 지중전선의 접속부에 테이핑처리에 의한 보완조치가 적용되었으며, 그 이후 전선 접속 부를 방수형접속재로 교체하는 작업이 시행되었으며 전선 접속부 위를 감전방지용 절연고무판으로 덮거나 차량의 통행이 없는 일부 지중함의 뚜껑을 절연재질인 고강도플라스틱(FRP)으로 교체하거나 그 이외에 다중접지된 중성선과 지중함의 틀을 본딩하는 개선대책 등이 현장에 적용되었다. 이러한 다양한 개선대책은 지중함에서의 감전사고를 예방하기 위한 것으로 그중 틀접지는 이미 적용된 지중함 내의 접지설비와 중성선이 공통접속된 상태에서 지중함과 맞닿는 틀에 접지도체를 연결하는 것이다. 계통의 중성선을 이용한(TN-C)방식의 틀접지는 효과가 있으나 뚜껑부분의 진동방지를 위하여 삽입한 고무패킹은 성능저하를 일으키므로 그에 대한 대책이 필요하였다.

• Journal of radiological science and technology
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• v.43 no.5
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• pp.337-341
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• 2020

Although the screening with a mammography has been shown to be economical, simple and effective in detecting breast cancer, it is accompanied by the risk from radiation. Therefore, this study analyzed the glandular dose and organ dose according to the target-filter combination and the presence and absence of implants using Monte Carlo simulation. The results indicate that at a tube voltage of 30 kV and a tube current of 50 mAs, the dose increased in the order of Mo/Mo. Mo/Rh, Rh/Rh and W/Rh in proportion to the atomic number of the target-filter. In addition, in phantom without implant a reduction in dose was seen when compared to the phantom with implant. The organ dose was highest in the lens except for the breast on the examination side regardless of the presence or absence of the implant. These results may contribute to use basic data for the diagnostic reference level of breast plastic surgery patients.

• Journal of Applied Biological Chemistry
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• v.43 no.4
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• pp.185-191
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• 2000

Pest insect control is dependent on about 200 insecticides that work by relatively few mechanisms. The targets they disrupt are mostly involved in the nervous system, respiratory chain, growth and development, or the gut. The major nerve targets are: acetylcholinesterase for the organophosphates and methylcarbamates; the nicotinic acetylcholine receptor for the neonicotinoids; the $\gamma$-aminobutyric acid receptor for several chlorinated hydrocarbons and fipronil; the voltage-gated sodium channel for DDT and pyrethroids. Selection of resistant strains often confers cross-resistance to some or all other insecticides working at the same site. The toxicological properties of different compounds acting on the same target are increasingly considered together, summating the risk even though the compounds are of quite diverse chemical types. Continuing attention is also being given to secondary targets not involved in the primary mechanism of toxicity but instead in side effects that must be considered in the overall safety evaluation. Research on insecticide targets is important in learning to keep up with resistance and changing concepts and policies on safety. These relationships are illustrated by recent studies in the Environmental Chemistry and Toxicology Laboratory of the University of California at Berkeley.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.12
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• pp.38-44
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• 2014

The photovoltaic power system is performing power generation by being installed in outdoors. Therefore it has the characteristics affected by environmental factors. In particular, if the solar power generation facility connected to the grid, the power can be generated continuously in a state of being secured operating voltage of the inverter and solar irradiation. In that case, if an abnormal situation such as flooding or heavy rains has occur, the possibility of electric shock or damage of facilities due to current leakage or a floating matters is present. In this paper, we performed electrical safety assessment about the connection part, junction box and cable of the solar module when the solar power system was flooded. we also assessed whether or not the leakage current is occurred in case of the cable was damaged. As a result, in case of the leakage current is large, we can be known that it is the risk of electric shock as well as cause of inverter damage.

• Journal of Electrical Engineering and Technology
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• v.9 no.3
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• pp.957-963
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• 2014

Converter transformers play important roles in high-voltage direct current transmission systems. This paper presents experimental and analysis results of the combined electrical and thermal aging of oil-impregnated paper at pulsating DC voltages. Breakdown voltages and time-to-breakdown of oil-paper specimens were measured by using short-time and constant-stress tests. The breakdown characteristics of combined electrical and thermal aging on insulation system were discussed. According to the relationship between failure time and aging temperature, the two-parameter Weibull model was improved. On the basis of the competing risk algorithm and the improved Weibull model, the two factors failure model was calculated. And the influence of temperature in the insulation system has been analyzed. This model performs better than the two-parameter Weibull model when both time and temperature are considered as variables in estimating the lifetime of oil-paper insulation.

• Journal of Power Electronics
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• v.11 no.3
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• pp.311-318
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• 2011

LCL filters installed at converter outputs offer a higher harmonic attenuation than L filters. However, as a three order resonant circuit, it is difficult to stabilize and has a risk of oscillating with the power grid. Therefore, careful design is required to damp LCL resonance. Compared to a passive damping method, an active damping method is a more attractive solution for this problem, since it avoids extra power losses. In this paper, the damping capabilities of capacitor current, capacitor voltage, and grid-side current feedback methods, are analyzed under the discrete-time state-space model. Theoretical analysis shows that the grid-side current feedback method is more suitable for use in active power filters, because it can damp LCL resonance more effectively than the other two methods when the ratio of the resonance and the control frequency is between 0.225 and 0.325. Furthermore, since there is no need for extra sensors for additional states measurements, this method provides a cost-efficient solution. To support the theoretical analysis, the proposed method is tested on a 7-kVA single-phase shunt active power filter.

• Journal of Power Electronics
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• v.10 no.6
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• pp.777-783
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• 2010

In order to drive gas discharge lamps, DC-AC converters with a LCC resonant tank, whose output voltage is adjusted by a variable frequency control are frequently used. However, when they are activated by varying the operating frequency, converters are frequently damaged by unstable operation, due to the rising and falling of the operating frequency near the resonant frequency. To solve this problem, a simple protection circuit for the power supply of a gas discharge lamp is proposed in this paper. This circuit senses the primary current of the main transformer. Using this protection circuit, the operating frequency of the lamp driving inverter system is kept close to and on the right side of the resonant frequency and the inverter is always operated in the ZVS condition. The resulting stable variable frequency operation allows various gas discharge lamps to be tested without the risk of damaging the main switches, because the protection circuit can protect the power MOSFETs of bridge converters from abnormal conditions. The validity and effectiveness of the proposed protection circuit are verified through the experimental results.

• The Journal of Internal Korean Medicine
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• v.27 no.3
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• pp.751-761
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• 2006

Atrial fibrillation (AF) is a common arrhythmia that is a potent independent risk factor for stroke. The incidence of AF increases with age and most affected people have underlying cardiac disease. An aging society increases the incidence of AF patients. The case was designed to evaluate the improving effect of Chengsim Yeunja-tang (CYT) for atrial fibrillation (AF) with Cb-infarction patients. This patient was treated with CYT and had significant improvement in symptoms and change of EKG. -Heart rate decreased in patients with higher than normal heart rate -RV5+SV1 voltage decreased (LVH improved) -Arrhythmia remained steady. -Palpitation. chest discomfort, dyspnea, headache, dizziness diminished. Results suggest that CYT is an effective treatment for Taeumin AF patients.

• Journal of the Korean Society of Safety
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• v.33 no.6
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• pp.22-27
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• 2018

Fire fighters are exposed to the risk of many accidents during fire suppression, especially near the high voltage circuit. In order to prevent and analyze the electric shock accidents, measurement of water resistance is crucial. However, this has been one of the overlooked research areas and it has been very difficult to measure the mixed up resistance components separately. In this paper, we measured a total resistance of apparatus and regarded it as a serial resistance of contact resistance and length dependant resistance. Measuring the resistance by varying the length of water stream, the variable resistance and fixed contact resistance appear, which are used to calculate the both components of resistances. In addition, the resistance of fire hose can be calculated from the parallel circuit which is formed by grounding the fire hose with the resistance of water stream. Results show that we can successfully measure the resistance per unit length of water stream and fire hose, thereby proving that this method is a facile way to measure water and fire hose resistance. However, many experiments are still required to obtain the precise contact resistance of ground under various condition and the resistance between the human body and fire hose.