• The Safety technology
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• no.190
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• pp.24-26
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• 2013

최근 화학물질 안전사고가 잇따라 발생하면서 사업장 내 안전제품을 구비하고 안전한 작업환경을 조성하려는 움직임이 확산되고 있다. (주)유민에쓰티(대표 유흥근)는 이러한 화학물질 안전사고를 예방하기 위해 불산, 염소 등의 화학약품 유출을 감지하는 센서장치를 생산하는 곳이다. 이곳은 누수감지센서를 비롯해 스팀검출센서, 옥외용 강산 검출센서, 유기성액체 검출센서 등을 개발하면서 산업안전제품시장에서 무서운 신장세를 드러내고 있다. 특히 지난 2008년에는 인쇄전자 기반의 필름형 누수감지센서를 세계 최초로 개발해 국무총리상을 수상하면서 우수한 기술력을 자랑하기도 했다. 또한 국내외 약 50여 건에 이르는 특허 획득을 통해 품질을 인증받았으며, 미국전기전자공학회(IEEE)에 소개되는 등 해외에서도 기술력을 인정받고 있다. 이처럼 (주)유민에쓰티는 끊임없는 기술 개발로 안전한 작업현장을 조성하는 데 이바지하고 있다. 하지만 유민에스티의 모든 관계자들은 사업장 내 안전이 먼저 확보됐었기에 이 같은 성장이 가능했다고 입을 모아 말한다. 제조업 특성상 안전사고 발생률이 높은데도 불구하고 2003년 설립된 이후 단 한 건의 안전사고와 산재가 발생하지 않았을 만큼 철저한 안전관리를 전개하고 있는 것이다. 안전을 바탕으로 눈부신 성장을 하고 있는 (주)유민에쓰티를 찾아가봤다.

• Proceedings of the Korea Information Processing Society Conference
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• 2012.11a
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• pp.543-544
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• 2012

객체 추적 및 모니터링 시스템에서 안개와 같은 환경적 불완전 요소는 비전 처리 성능에 많은 영향을 준다. 특히 안개는 빛의 산란과 흡수에 의한 감쇠로 탐지 영역내의 물체의 색상이 비슷해지고 채도가 매우 떨어지게 되어 객체의 형태를 구별하기 어려워진다. 따라서 실외에서 신뢰할 수 있는 비전 처리를 위해서는 안개와 같은 환경적 불완전 요소의 제거가 필수라 할 수 있다.

• Journal of the Semiconductor & Display Technology
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• v.16 no.4
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• pp.16-19
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• 2017

For the economical and environmental-friendly fabrication of polisher, Mo mask layer were sputtered on glass substrate instead of Cr mask material. Mo mask layers were sputtered by pulsed-DC sputtering and Photoresist patterns were formed on Mo mask layer for different develop times and optimized. After Mo mask layer were patterned and exposed glass was wet etched by HF solution for different etching times, the remaining Mo mask was stripped by using Al etchant. Develop time of 30 sec and HF wet etching time of 3 min were selected as optimized process condition and applied to the fabrication of polisher.

• Journal of Wetlands Research
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• v.17 no.1
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• pp.45-52
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• 2015

We obtained the following results from investigation on vegetation damage from 5 to 6 August, 2013, about one year after an accident that hydrofluoric acid leaked from a chemical maker, Hube Globe in Gumi. Pinus densiflora and Pinus strobus showed very severe damage. Ginko biloba, Quercus acutissima, Pinus rigida, Salix glandulosa, Hibiscus syriacus, and Lagerstroemia indica showed severe damage. Quercus variabilis, Lespedeza cyrtobotrya, and Miscanthus sinensis showed moderate damage. Quercus aliena, Smilax china, Arundidinella hirta, Ailanthus altissima, Robinia pseudoacacia, and Paulowinia coreana showed slight damage. We did not find any plants without leaf damage around there. This result means that fluoride damage still persists in this area as was known that fluoride remains for a long time in air, soil and water and exerts negative effects at all levels of an ecosystem. In addition, fluoride content contained in plant leaf depended on the distance from a fertilizer producing factory and vegetation damage tended to proportionate to the concentration in the Yeocheon industrial complex. In these respects, a measure for removal or detoxification of the remaining fluoride is urgently required around the hydrofluoric acid leak spot. Fertilizing of dolomite containing Ca and Mg, which can trap fluoride, was prepared as one of the restoration plans. In addition, phosphate fertilizing was added in order to enhance soil ameliorating effects. Furthermore, we recommend the introduction of tolerant plants as the second measure to mitigate fluoride damage. As the tolerant plants to make a new forest by replacing trees died due to hydrofluoric acid gas damage, we recommended Q. aliena and S. china, A. hirta, etc. were recommended as plant species to add mantle vegetation to the forest margin to ensure stable interior environment of the forest.

• The Journal of Korean Academy of Prosthodontics
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• v.52 no.1
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• pp.1-8
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• 2014

Purpose: The purpose of this study is to evaluate the effect of applying Silano-pen to feldspathic porcelain and zirconia on shear bond strength with composite resin. Materials and methods: Feldspathic porcelain and zirconia specimens were produced into 30 per each 2 mm thick and 12 mm in diameter and their surface was made smooth and even and then embedded in acrylic resin. The specimens were divided into each Group F (Feldspathic porcelain) and Group Z (Zirconia), (1) Hydrofluoric acid etching and silane (F1 & Z1), (2) Silano-pen and silane (F2 & Z2), (3) Hydrofluoric acid etching and Silano-pen, silane (F3 & Z3). After surface conditioning, substrate surfaces of the specimen were examined by SEM. Composite resin cylinders (2 mm high, 3 mm in diameter)were bonded to specimen and shear bond strength between ceramic and composite resin was measured by using universal testing machine. The measured values were statistically analyzed by using two way ANOVA and Tukey's multiple comparison test (${\alpha}=.05$). Results: In the scanning electron micrograph of the treated ceramic surface, Group F2 and F3 appeared the high roughness and Group Z3 appeared the highest density of silica particle. In Feldspathic porcelain, the result of measuring shear bond strength showed that Group F3 was measured to be highest and Group F1 was measured to be lowest but there was no statistical significance among Groups. In zirconia, Group Z3 was measured to be highest and Group Z1 was measured to be lowest and there was statistical significance among Groups (P<.05). Conclusion: In zirconia, applying hydrofluoric acid etching and then Silano-pen and silane is effective for composite resin adhesion.

• Journal of the Society of Disaster Information
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• v.9 no.4
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• pp.449-461
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• 2013

As the hydrofluoric acid leak in Gumi-si, Gyeongsangbuk-do or hydrochloric acid leak in Ulsan, Gyeongsangnam-do demonstrated, chemical related accidents are mostly caused by large amounts of volatile toxic substances leaking due to the damages of storage tank or pipe lines of transporter. Safety assessment is the most important concern because such toxic material accidents cause human and material damages to the environment and atmosphere of the surrounding area. Therefore, in this study, a hydrofluoric acid leaked from a storage tank was selected as the study example to simulate the leaked substance diffusing into the atmosphere and result analysis was performed through the numerical Analysis and diffusion simulation of ALOHA(Areal Location of Hazardous Atmospheres). the results of a qualitative evaluation of HAZOP (Hazard Operability)was looked at to find that the flange leak, operation delay due to leakage of the valve and the hose, and toxic gas leak were danger factors. Possibility of fire from temperature, pressure and corrosion, nitrogen supply overpressure and toxic leak from internal corrosion of tank or pipe joints were also found to be high. ALOHA resulting effects were a little different depending on the input data of Dense Gas Model, however, the wind direction and speed, rather than atmospheric stability, played bigger role. Higher wind speed affected the diffusion of contaminant. In term of the diffusion concentration, both liquid and gas leaks resulted in almost the same $LC_{50}$ and ALOHA AEGL-3(Acute Exposure Guidline Level) values. Each scenarios showed almost identical results in ALOHA model. Therefore, a buffer distance of toxic gas can be determined by comparing the numerical analysis and the diffusion concentration to the IDLH(Immediately Dangerous to Life and Health). Such study will help perform the risk assessment of toxic leak more efficiently and be utilized in establishing community emergency response system properly.

• Clean Technology
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• v.2 no.1
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• pp.96-108
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• 1996

$NO_x$ is mainly emitted from mixed acid pickling process in the stainless industry and its impact to the environment has been worried over. This study which may be considered as one of the development of clean technologies, differing from the traditional end pipe technology is about how to reduce $NO_x$ emission through the modification of corresponding process. This study consists of two parts. First, the influence of various reaction parameters in a acid pickling process on $NO_x$ emission was investigated. Second, the influence of hydrogen peroxide on $NO_x$ formation, which is known as inhibitor of $NO_x$ emission, was investigated. Major findings in this study are as follows. The important reaction parameters which have a great influence on $NO_x$ emission are the reaction temperature and the concentration of fluoric acid. The concentration of nitric acid, some of which results in $NO_x$ compound is not as important as the concentration of fluoric acid. Synthetic mixed acid of nitric acid and fluoric acid itself in absent of pickling plate contributed the $NO_x$ emission, however, its impact was negligible in terms of quantity. The addition of hydrogen peroxide to the acid pickling process significantly contributed to the reduction of $NO_x$ emission and successfully achieved 80% reduction of $NO_x$ emission at the condition of $9.51{\times}10^{-2}mole\;hydrogen\;peroxide/m^2$ pickling area. This result was compared to literature value from Avesta steel process, indicating a sixth of hydrogen peroxide addition of Avesta's in achieving a same amount of $NO_x$ reduction. The region of the economic hydrogen peroxide addition per unit area of plate to be pickled from the result of this study was established.

• The korean journal of orthodontics
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• v.38 no.4
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• pp.275-282
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• 2008

Objective: The purpose of this study was to investigate the effect of using laser for ceramic bracket bonding of porcelain surfaces and to compare it with conventional treatment of porcelain surfaces. Methods: Ninety feldspathic porcelain specimens were divided into 9 groups of 10, with each group having different surface treatments performed. Surface treatment groups were orthophosphoric acid, orthophosphoric acid with silane, hydrofluoric acid, hydrofluoric acid with silane, sandblasted, sandblasted with silane, laser etched, laser etched with silane, and glazed surface served as a control group. In the laser etched groups, the specimens were irradiated with 2-watt superpulse carbon dioxide ($CO_2$) laser for 20 seconds. Ceramic brackets were bonded with light-cure composite resin and all specimens were stored in water at $37^{\circ}C$ for 24 hours. Shear bond strength was determined in megapascals (MPa) by shear test at 1 mm/minute crosshead speed and the failure pattern was assessed. For statistical analysis, one-way ANOVA and tukey test were used. Results: Statistical analysis showed significant differences between the groups. The HFA + S group showed the highest mean shear bond strength ($13.92{\pm}1.94\;MPa$). This was followed by SB + S ($10.16\;{\pm}\;1.27\;MPa$), HFA ($10.09\;{\pm}\;1.07\;MPa$), L + S ($8.25\;{\pm}\;1.24\;MPa$), L ($7.86\;{\pm}\;0.96\;MPa$), OFA + S ($7.22\;{\pm}\;1.09\;MPa$), SB ($3.41\;{\pm}\;0.37\;MPa$), OFA ($2.81\;{\pm}\;0.37\;MPa$), G ($2.46\;{\pm}\;1.36\;MPa$), Bond failure patterns of HFA and silane groups, except L + S, were cohesive modes in porcelain while adhesive failure was observed in the control group and the rest of the groups. Conclusions : A 2-watt superpulse $CO_2$ laser etching of porcelain surfaces can provide a satisfactory result for porcelain surface treatment for ceramic bracket bonding. Laser irradiation may be an alternative conditioning method for the treatment of porcelain surfaces.

• Journal of Preventive Medicine and Public Health
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• v.26 no.4 s.44
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• pp.587-598
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• 1993

Hydrofluoric acid is one of the strongest irritating, corrosive and poisonous inorganic chemicals. Hydrofluoric acid burns are occurring with ever-increasing frequency due to the wide use of this acid in industries. Hydrofluoric acid burns are characterized by severe progressive tissue destruction and excruciating pain due to the unique properties of the freely dissolvable fluoride ion. The authors reviewed medical records of 32 cases (36 spells) of hydrofluoric acid burns which occurred in a hydrofluoric acid manufacturing factory from Sep. 1, 1990 to June 30, 1993. The results are as follows; 1. Eleven measurements of air concentrations of hydrofluoric acid by detection tube method from 1990 to 1992 were all below TLV (Department of Labor, R.O. K). 2. There were 19 cases (22 spells) of hydrofluoric acid burns which occurred during the study period among regular employees. The overall incidence density of hydrofluoric acid was 17.8 cases (20.6 spells) per 100 person-year. Incidence density was 19.0 cases (22.0 spells) per 100 person-year among male workers and there were no female cases. Incidence density was 32.9 cases (38.3 spells) per 100 person-year among production workers and 1.9 cases (1.9 spells) per 100 person-years among management workers with the difference being statistically significant (P<0.01). 3. Of 32 cases (36 spells) of hydrofluoric acid burns among workers who were regularly employed or temporarily employed, 26 spells (81.2%) were between age 20 to 39. In 15 spells(41.7%) burns occurred between 12:00 and 17:59 with 16 spells(44.3%) having arrived at hospital within 2 hours after the accident. 4. Of 36 spells, the main cause of hydrofluoric acid burns were by splashes (8 spells, 22.2 %). The most frequent site of burns were fingers and pain was the most frequent symptom. Thirty spells (83.3%) of the hydrofluoric acid burns were treated with local injection of antidote (calcium gluconate). Complete recovery without scarring were observed in most of the cases (34 out of 36 cases, 94.4%). The study results suggest that to prevent hydrofluoric acid burns, environmental control and the wearing of hydrofluoric acid resistant protective clothes and gloves are important. It is also stressed that establishment of an emergency management and a transfer system for hydrofluoric acid burn victims is necessary.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.10
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• pp.774-781
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• 2011

Nitric acid and hydrofluoric acid are used for acid pickling in zirconium alloy tubing manufacturing process. Nitrate and fluoride in the wastewater were treated by chemical coagulation and SOD (Sulfur Oxidation Denitrification) process. This study is investigated the effect of fluoride concentration and the optimal condition for SOD process. The limited fluoride concentration for SOD process was below 20 mg F-/L. The adjusted pH and alkalinity by NaOH and $NaHCO_3$ was shown to be more effective for removal of nitrate compared with using NaOH. Furthermore, the microbial activator mixed trace elements and ingredient for alkalinity did not only supplement with alkalinity but also enhance the growth and proliferation for sulfur-oxidizing bacteria. As a result, the inorganic industrial wastewater was successfully treated by the microbial activator in SOD process without continuous addition of seed sludge. Finally, SOD process was shown to remove nitrate in industrial wastewater and to contribute the microbial activator for activation of sulfur-oxidizing bacteria.