• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.155-155
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• 2009

AC-PDP의 유전체 보호막 물질로 사용 종인 다결정 MgO의 전기적 특성을 개선하기 위하여 본 연구에서는 MgO에 doping 물질과 첨가량에 따른 전기적 특성을 고찰하였다. 박막을 증착시키기 위해 MgO pellet target을 만드는데 이때 pellet의 밀도, XRD, 비커스경도, 파괴인성, 표면 grain size와 이차전자방출계수와의 관계 및 박막의 표면거칠기, 표면의 형태, 투과율과 이차전자방출계수와의 관계를 고찰하였다. 이에 여러 dopant를 첨가하여 특성 평가한 실험데이터를 정리하여 이차전자방출계수와의 연계성을 조사 하였다.

• Journal of the Korean Society of Radiology
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• v.14 no.4
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• pp.433-437
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• 2020

Principles of Radiation Detection and measurement include luminescence, ionization and chemical reactions. In this study, thermoluminescent properties were analyzed by exposure radiation on the glass for protective glass of smart phone. In order to analyze the thermoluminescent characteristics by radiation, 6 MV X-ray 100 cGy was irradiated to the powder annealing at 300 ℃ by grinding the tempered glass and original tempered glass. As a result of measuring the amount of thermoluminescent respectively irradiated material, the thermoluminescent increased by 3 times in the tempered glass, and when the tempered glass was grinding by powder the thermoluminescent was 2.4 times increased. Based on these results, the liquid crystal protective glass of the smart phone is evaluated as a tracer material to evaluate the radiation exposure and dose of the personal radiation monitoring.

• Journal of the Korean Society of Safety
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• v.23 no.6
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• pp.62-69
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• 2008

As the concerns of dermal exposure of spray painters to isocyanates in the automobile industry, glove performance was examined like permeation rate and breakthrough time including fatigue test. Methylene chloride was used as the solvent for derivatization of the isocyanates with a 97.5% recovery. Ghost wipe pads were used to wipe the surface of the glove material after chemical penetration through the glove material placed under a disposable test cell. Several solvents were tested, such as thinner(xylene, toluene) and cleaning agent(acetone) by using a standard permeation test cell(AS/NZS standard 2161. part 10.3). Solvents accelerate chemical permeation through the gloves more quickly than pure HDI hardener products. The longest breakthrough times were from Nitrosolve gloves, not detected in 8 hours, compared with others like Latex, Neoprene, TNT and Dermo Plus. Therefore Nitrosolve gloves could be recommended as personal protective equipment in crash repair shops. In addition, revised exposure limit of korean regulation should be suggested for employee to minimize the risk of health symptoms.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.481-482
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• 2006

플라즈마 화상표시기 (PDP)의 보호막 물질로 사용 중인 다결정 MgO의 특성을 개선하기 위하여 본 연구에서는 MgO에 희토류계 원소를 치환하여 제조하였으며, 치환량에 따른 MgO 보호막의 광학적 특성과 전기적 특성을 고찰하였다. MgO + 100 ppm $Gd_2O_3$조성으로 제작한 MgO 박막의 이차전자 방출계수 값이 순수 MgO 보다 35% 높게 나타났다. $Gd_2O_3$ dopant가 100 ppm 첨가시까지 밀도가 증가하였으나, 그 이상 첨가시 감소하는 경향을 나타냈다. 가속전압 200 V에서 이차전자 방출계수는 0.138 이었고 표면거칠기는 5.77 nm 이었으며 투과율은 550 nm 에서 95.76% 이었다.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.21 no.2
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• pp.103-109
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• 2011

Object: we investigated some factors which can affect workers' comprehension of chemical hazard information and their actions to protect themselves from the hazard. Method: Comprehension score of chemical hazard information and the rate of wearing personal protective equipment (PPE) was surveyed for the 109 workers from 15 factories who were exposed to N, N-dimethylformamide. Difference of the worker's comprehension score of hazard information was analyzed by education interval, work duration and the way of occupational safety and health management between self-managed or sub-contracted. Result: Mean comprehension score of N, N-dimethylformamide hazard, which was given as a short quiz composed of 10 "true" or "false" problems, was 65%. Mean percentage of wearing PPE was improved as the education program was done within a month but decreased after 6 months. Eighty seven % of workers got the chemical hazard information from the material safety data sheet placed at workplace. Conclusion: Education interval and comprehension score affected the rate of wearing PPE. The way of occupational safety and health management self-managed or sub-contracted did not affect the workers' comprehension score on hazard information nor the rate of wearing PPE.

• Textile Coloration and Finishing
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• v.30 no.4
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• pp.227-236
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• 2018

As consciousness of safety becomes an important social issue, the demand for protective clothing is increasing. Conventional flame-retardant cotton working wear has low durability, and working wear with m-aramid fibers are stiff, heavy, less permeable, and expensive. In this study, recycled m-aramid and cotton have been blended to produce woven fabric of different compositions to enhance high performance and comfort to solve aforementioned problems. The fabrics were analyzed according to constituents and various structural factors. Mechanical properties were measured using KES-FB system. The measured thermal properties are TGA, $Q_{max}$, TPP and RPP. Fabric with polyurethane yarn covered by m-aramid/cotton spun yarn is observed to have good wearability. The fabric of open end spun yarn showed more stiffness than that of ring spun yarn. The sample with the high count of yarn has more smooth surface. In addition, high m-aramid content fabric is considered to have relatively high stiffness when using as clothing. In TGA the fabric with higher m-aramid content showed more stable decomposition behavior. The fabric having rough surface showed lower heat transfer properties in $Q_{max}$. The influence of the fabric thickness was important in convection and radiant heat test.

• Journal of the Korean Geotechnical Society
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• v.20 no.6
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• pp.11-17
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• 2004

This study focused on the protection effects of geosynthetics installed on HDPE to resist against puncture loads. The study was conducted by a model test with various types of puncture loads created by different shapes of tools. The puncture resistance of geosynthetics installed as a protective material on HDPE is varied depending on the sizes of geosynthetics and types of puncture loads. In this study, it was found that the protection effect far all kinds of geosynthetics when a truncated cylindrical shape of puncture tool is used is lower than others. Also, geocomposite has the most excellent protection effect against all types of puncture loads.

• The Korean Journal of Community Living Science
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• v.21 no.4
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• pp.595-603
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• 2010

The present study was performed on humans to investigate the physiological strain of wearing protective clothing for shielding electromagnetic waves and to compare control clothing that are currently on the market and new clothing that are developed for improving thermal comfort and material weight. Experiments were conducted in a climatic chamber of $28.8{\pm}0.6^{\circ}C$, $37{\pm}5%$RH under three differed experimental clothing conditions: None, Control, New. The results were as follows. Mean skin temperature and rectal temperature in New were significantly lower than that in None and Control (p<.05). The temperature and humidity inside clothing were lower in None (p<.05). Total weight loss was lower in New. Thermal sensation and thermal comfort were less hot and more comfortable in New than those in Control. It was concluded that wearing the protective clothing for shielding electromagnetic waves affects physiological responses such as distribution of body temperature, sweat rate, etc.

• Journal of the Korean Society of Clothing and Textiles
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• v.41 no.4
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• pp.771-781
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• 2017

The helmet is an imperative personal protective equipment. This protective device must be able to guard the human head against potential risks. Helmets are classified according into the purpose of use; therefore, the required performance and specifications depend on the type of products. Military helmets are intended to protect the wearer's head from bullets and shrapnel. Generally, lightweight super fibers and fiber reinforced composite materials are used as helmet shell materials, and NIJ STD of U.S. Department of Justice is most widely used as international standard related to bulletproof helmets. Safety helmets are widely used for industrial application and sports leisure. In general, the performance of shock absorption must be ensured, and various lining systems are applied in material, design, and combination methods. Evaluation standards have also been classified and strictly controlled for each purpose; therefore, it is difficult to certify with the existing standards such as the recently developed convergence helmets. However, it is possible to launch the product through a separate national integrated certification procedure.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.53 no.2
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• pp.43-50
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• 2004

Percentage differential characteristic relaying(PDR) has been recognized as the principal basis for power transformer protection. Second harmonic restraint PDR has been widely used for magnetizing inrush in practice. Nowadays, relaying signals can contain 2nd harmonic component to a large extent even in a normal state, and 2nd harmonic ratio indicates a tendency of relative reduction because of the advancement of material. Further, as the power system voltage becomes higher and more underground cables are used, larger 2nd harmonic component in the differential current under internal fault is observed. And then, conventional 2nd harmonic restraint PDR exposes some doubt in reliability. It is, therefore, necessary to develop a new algorithm for performance improvement of conventional protective relaying. This paper proposes an advanced protective relaying algorithm by using voltage-current trend and flux-differential current slope characteristic. To evaluate the performance of the proposed algorithm, we have made comparative studies of PDR, fuzzy relaying and DWT relaying. The paper is constructed power system model including power transformer, utilizing the WatATP, and data collection is made through simulation of various internal faults and inrush. As the results of test, the new proposed algorithm was proven to be faster and more reliable.