• 한국표면공학회지
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• 제31권6호
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• pp.334-344
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• 1998

Yew coating pmccss t.o form a surface layer ol CrN phasc on mild steel (A81 1020!, AlSI Hi3, 1Cr-0.5Mo steel (ASTM A213 and Nickrl-base superalloy (Inconel 718) was developed. Surlaces of various alloys t,n.ateii by chromizing for the formation ol Cr diffusion layer was subsequently trcaled by plasma nitriding in order t.o form the hard CrS coating layer on the surfaces. This duplex plasma surface tri-atments of chromizing and plasma nitriding have induced a lormation of a duplex-lrcated surfacr hyer of approximat~ls 70-80 $\mu\textrm{m}$thickncss with a iargcly improved microiiardnrss up to approxiniateW 1500Hv(50gf). The main cause for the lage improvment in the surface hardncss is altribilted to [.he fact that CrN and $Fe_xN$ phases are created successfully by ccliromizins and plasma nilriding treatment. High tenipera1,urc wear resislance of the duplex-treated mild steel and HI3 steels at $600^{\circ}C$ was examined. Comparing the duplex-treated specimens with the specimens treated only by chromizing, the rcsults shovmi that, thc wear volume of the duplex-treated mild skcl and 1113 stcel aSt.er a wear test, at $600^{\circ}C$ were reduced hy a Iactor of 8 and 3, respectively. Characteristics of the CrS phase by duplrx treatment were compared with $CrN_x$,/TEX> film by ion plating and the wear behaviors of CrN film lormed by two different nroccsses arc nea.riy identical.

• 한국환경보건학회지
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• 제44권2호
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• pp.133-142
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• 2018

Objectives: The pathogenic Vibrios genus denotes halophilic bacteria that are distributed in aquatic environments, including both sea and freshwater. Vibrio cholerae, Vibrio vulnificus, and Vibrio parahaemolyticus are the most important species since they can be potent human pathogens and leading causes of septicemia, wound infections, and seafood borne gastroenteritis. The recent emergence of a potential pandemic clone, V. cholera serotype O1 and the cholera outbreak in South Korea in 2016 indicates the importance of consistent surveillance of pathogenic Vibrio genus within coastal areas. Methods: The present study was undertaken to determine where and how vibrios live in the aquatic environment adjacent to coastal areas of South Korea. For this survey, a total of 838 samples were obtained at 35 different sites in South Korean coastal areas during the period from January 2016 to December 2016. Pathogenic vibrios was determined using the real-time PCR method, and its clones were isolated using three selective plating media. We also monitored changes in seawater and atmospheric temperature, salinity, turbidity, and hydrogen ion concentration at the collection points. Results: The total isolation rates of V. vulnificus, V. cholera (non-pathogenic, non-O1, non-O139 serogroups), and V. parahaemolyticus from seawater specimens in 2016 were 14.2, 13.48, and 67.06%, respectively. Conclusions: The isolation rates of pathogenic vibrios genus showed a positive correlation with temperature of seawater and atmosphere but were negatively correlated with salinity and turbidity.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2016년도 추계학술대회 논문집
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• pp.33-55
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• 2016

PVD(Physical Vapour Deposition)코팅은 70년대 미국의 Multi-arc이란 기업에 의해 질화물계나 탄화물계 피막 증착이 가능한 아크이온플레팅(Arc Ion Plating) 기술이 산업에 소개되어, 주로 내마모나 내구성을 요구하는 금형, 절삭공구, 산업용 부품 분야 등에 적용되면서 꾸준한 성장세를 거듭해 왔다. 최근 들어 PVD기술은 그 수요의 급증과 더불어 보다 진화된 형태의 코팅장치 및 코팅피막들이 산업에 소개 되고 있다. 먼저 절삭가공분야에는 new composition, nano composite, multi-element composition, multi-layer, SML(Self Modification Layer)등의 코팅피막들이 단독 또는 조합된 형태로 개발되어 철계 소재를 대상으로 고경도 소재의 고속가공, 저경도~중경도 소재의 중속~고속 광범위영역에서 동시 절삭을 가능케 하였고, 비철.비금속 소재 절삭용으로 종전의 가스방식의 DLC(a-C:H)코팅을 훨씬 능가하는 ta-C Plus(Ultra super DLC) 코팅이 개발되어 고 Si함량의 Al-Si계 합금, Cu-W계, 고 섬유 CFRP, CFRM 및 반소결 상태의 세라믹 소재들을 황삭에서 정삭까지 단일 공정으로 절삭이 가능한 고성능 공구들이 개발보급되고 있다. 금속 성형분야에는 고장력 강판을 냉간에서 성형 가능한 Lubricative multi-layer coating, 열간 또는 고온에서 성형이 가능한 functional multi layer과 이형성이 더한층 개선된 dimpled(or embossed) functional multi layer 코팅들이 개발되어 산업현장에 빠르게 확산되고 있다. PVD 코팅의 또 다른 주요 적용분야로 의료분야를 들 수 있는데, 이는 코팅의 대다수가 고경도의 생체친화적인 특성을 가진데 착안되었으며, 흔히 현대성 질환이라 일컫는 과민성 체질, 과체중 및 허약체질 환자의 증가와 각종 재해 및 사고의 증가 및 인간 수명 증가에 따른 인공적인 시술의 요구증가에 편승하여 이 분야의 시장 또한 가파르게 성장하고 있다. 또한 대량으로 양산 적용단계에 접어든 자동차 핵심부품들을 비롯해서 각종 산업용, 방산용 기계 부품에도 성능 향상, 내구성 향상, 환경친화성 등 다양한 목적으로 확대 적용되고 있는 사례들을 본 발표를 통해 간략하게나마 소개하고자 한다.

• 한국광학회지
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• 제18권5호
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• pp.362-366
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• 2007

본 연구에서는 3 메가픽셀, 2.5배 줌 카메라폰 모듈용 비구면 유리렌즈 개발을 목적으로 실험계획법(DOE)을 적용하여 성형용 초경 코어의 연삭가공조건을 구하고, 이를 활용하여 비구면 Glass렌즈 성형용 초경합금(WC) 코어를 초정밀 연삭가공을 수행하였다. 또한 가공된 성형용 코어의 가공면 위에 이온증착법으로 다이아몬드상 탄소(Diamond-Like Carbon; DLC) 코팅을 수행하여 DLC 코팅이 성형용 코어의 형상정도(PV)와 표면조도(Ra)에 미치는 영향을 평가하였으며, 비구면 Glass렌즈를 동일한 조건에서 성형하여 성형렌즈의 광학적 특성을 비교하여 성형용 코어면의 DLC 코팅 효과에 대하여 검토하였다.

• 한국수소및신에너지학회논문집
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• 제7권1호
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• pp.29-37
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• 1996

Alkaline water electrolysis has been commercialized as the only large-scale method for a long time to produce hydrogen and the technology is superior to other methods such as photochemical, thermochemical water splitting, and thermal decomposition method in view of efficiency and related technical problem. However, such conventional electrolyzer do not have high electric efficiency and productivity to apply to large scale hydrogen production for energy or chemical feedstocks. Solid polymer electrolyte water electrolysis using a perfluorocation exchange membrane as an $H^+$ ion conductor is considered to be a promising method, because of capability for operating at high current densities and low cell voltages. So, this is a good technology for the storage of electricity generated by photovoltaic power plants, wind generators and other energy conversion systems. One of the most important R&D topics in electrolyser is how to minimize cell voltage and maximize current density in order to increase the productivity of the electrolyzer. A commercialized technology is the hot press method which the film type electrocatalyst is hot-pressed to soild polymer membrane in order to eliminate the contact resistance. Various technologies, electrocatalyst formed over Nafion membrane surface by means of nonelectrolytic plating process, porous sintered metal(titanium powder) or titanium mesh coated with electrocatalyst, have been studied for preparation of membrane-electrocatalyst composites. In this study some experiments have been conducted at a solid polymer electrolyte water electrolyzer, which consisted of single cell stack with an electrode area of $25cm^2$ in a unipolar arrangement using titanium mesh coated with electrocatalyst.

• 한국환경보건학회:학술대회논문집
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• 한국환경보건학회 2002년도 춘계 국제 학술대회
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• pp.40.1-43
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• 2002

The purpose of this study was to evaluate a new sampling and analytical method for the determination of hexavalent chromium, Cr(VI) in mist from field plating operation. The Procedures of this new method (Shin & Paik's Method) are as the following: Airborne hexavalent chromium is collected on polyvinyl chloride (PVC) filter according to the National Institute for Occupational Safety and Health (NIOSH) Method 7600, and the filter sample is placed in a screw-capped vial and soaked with 2％ NaOH/3％ Na₂CO₃ solution immediately after sampling. The Cr(VI) sample is analyzed by ion chromatography/visible spectrophotometry (IC/VS) according to the U.S. Environmental Protection Agency (EPA) Method 218.6. The airborne Cr(VI) concentrations measured by this method were compared with those determined by three reference methods: One (NIOSH/EPA Method) consisted of sampling airborne Cr(VI) on PVC filters and storing the sample filters in screw-capped vials according to the NIOSH method, and analyzing Cr(VI) in samples using IC/VS according to the EPA method. The second method (Impinger Method/NaHCO₃) consisted of absorbing airborne Cr(VI) into 0.02 MN/sub a/Hco₃ solution in midget impinger, and analyzing the Cr(VI) in samples using IC/VS. The third method was the OSHA Method Id-215. Using these four different methods, four replicates of air samples were collected at an electroplating process and analyzed simultaneously. Two-way ANOVA and Paired t-test were used to test difference among values determined by the methods. There was no significant difference and a strong correlation (r/sup 2/=0.99) between Cr(VI) concentrations measured by the shin & Paik's Method and an impinger method (p＞0.05). However, Cr(VI) concentrations determined by Shin & Paik's Method were Significantly different form those by the NIOSH/EPA Method (p＜0.05) or the OSHA method (p＜0.05). The Cr(VI) concentrations of Shin & Paik's Method were Significantly higher than those of the NIOSH/EPA Method or the OSHA method. We concluded that the Shin & Paik's Method could prevent Cr(VI) losses caused by reduction and give more reliable results of airborne Cr(VI) concentrations in work environments.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 The 6th International Symposium of East Asian Resources Recycling Technology
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• pp.259-263
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• 2001

There are several steps such as slicing, lapping, chemical etching and mechanical polishing in the silicon wafer production process. The chemical etching step is necessary to remove damaged layer caused In the slicing and lapping steps. The typical etching liquor is the acid mixture comprising nitric acid, acetic acid and hydrofluoric acid. At present, the waste acid is treated by a neutralization method with a high alkali cost and balky solid residue. A solvent extraction method is applicable to separate and recover each acid. Acetic acid is first separated from the waste liquor using 2-ethlyhexyl alcohols as an extractant. Then, nitric acid is recovered using TBP(Tri-butyl phosphate) as an extractant. Finally hydrofluoric acid is separated with the TBP solvent extraction. The expected recovered acids in this process are 2㏖/l acetic acid, 6㏖/1 nitric acid and 6㏖/l hydrofluoric acid. The yields of this process are almost 100% for acetic acid and nitric acid. On the other hand, it is important to recover and reuse the metal values contained in various industrial wastes in a viewpoint of environmental preservation. Most of industrial products are made through the processes to separate impurities in raw materials, solid and liquid wastes being necessarily discharged as industrial wastes. Chemical methods such as solvent extraction, ion exchange and membrane, and physical methods such as heavy media separation, magnetic separation and electrostatic separation are considered as the methods for separation and recovery of the metal values from the wastes. Some examples of the application of solvent extraction to the treatment of wastes such as Ni-Co alloy scrap, Sm-Co alloy scrap, fly ash and flue dust, and liquid wastes such as plating solution, the rinse solution, etching solution and pickling solution are introduced.

• Journal of Electrochemical Science and Technology
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• 제11권1호
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• pp.60-67
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• 2020

In this study, copper (II) oxide powder for electroplating was prepared by recovering CuCl₂ from NaClO₃ type etching wastes via recovered non-sintering two step chemical reaction. In case of alkali copper carbonate [mCuCo₃·nCu(OH)₂], first reaction product, CuCo₃ is produced more than Cu(OH)₂ when the reaction molar ratio of sodium carbonate is low, since m is larger than n. As the reaction molar ratio of sodium carbonate increased, m is larger than n and Cu(OH)₂ was produced more than CuCO₃. In the case of m has same values as n, the optimum reaction mole ratio was 1.44 at the reaction temperature of 80℃ based on the theoretical copper content of 57.5 wt. %. The optimum amount of sodium hydroxide was 120 g at 80℃ for production of copper (II) oxide prepared by using basic copper carbonate product of first reaction. At this time, the yield of copper (II) oxide was 96.6 wt.%. Also, the chloride ion concentration was 9.7 mg/L. The properties of produced copper (II) oxide such as mean particle size, dissolution time for sulfuric acid, and repose angle were 19.5 mm, 64 second, and 34.8°, respectively. As a result of the hole filling test, it was found that the copper oxide (II) prepared with 120 g of sodium hydroxide, the optimum amount of basic hydroxide for copper carbonate, has a hole filling of 11.0 mm, which satisfies the general hole filling management range of 15 mm or less.

• 한국환경보건학회지
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• 제28권2호
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• pp.109-116
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• 2002

The purpose of this study was to evaluate a new sampling and analytical method for the determination of airborne hexavalent chromium, Cr(Ⅵ), in a field plating operation. The procedures of this new method (Shin & Paik's Method) are as the following: Airborne hexavalent chromium is collected on polyvinyl chloride (PVC) filter according to the National Institute iota Occupational Safety and Health (NIOSH) Method 7600, and the filler sample is placed in a screw-capped vial and soaked with 2% NaOH/3% Na₂CO₃ solution immediately after sampling. The Cr(Ⅵ) sample is analyzed by ion chromatography/visible spectrophotometry (IC/VS) according to the U.S. Environmental Protection Agency (EPA) Method 218.6. The airborne Cr(Ⅵ) concentrations measured by this method were compared with those determined by three reference methods: One (NIOSH/EPA Method) consisted of sampling airborne Cr(Ⅵ) on PVC filters and storing the sample filters in strew-capped vials according to the NIOSH method, and analyzing Cr(Ⅵ) in samples using IC/VS according to the EPA method. The second method (Impinger Method/NaHCO₃) consisted of absorbing airborne Cr(Ⅵ) into 0.02 M NaHCO₃ solution in midget impinger, and analyzing the Cr(Ⅵ) in samples using IC/VS. The third method was the OSHA Method ID-215. Using these four different methods, lour replicates of air samples were collected at an electroplating process and analyzed simultaneously. Two-way ANOVA and paired t-test were used to test difference among values determined by the methods. There was no significant difference and a strong correlation (r²:0.99) between Cr(Ⅵ) concentrations measured by the Shin & Paik's Method and an impinger method (p>0.05). However, Cr(Ⅵ) concentrations determined by Shin & Paik's Method were significant1y different from those by the NIOSH/EPA Method (p<0.05) or the OSHA method (p<0.05). The Cr(Ⅵ) concentrations of Shin & Paik's Method were significantly higher than those of the NIOSH/EPA Method or the OSHA method. This result indicated that the Shin & Paik's Method may prevent Cr(Ⅵ) losses caused by reduction and give more reliable results of airborne Cr(Ⅵ) concentrations in work environments.

• 한국산학기술학회논문지
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• 제15권3호
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• pp.1253-1258
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• 2014

CA 이온도금기술에 의한 TiC와 TiN 그리고 TiC/TiN 코팅재를 비교하기 위하여 트라이볼로지 물성을 연구하였다. 실험은 Falex journal V block 시스템을 이용한 터보시험기에서 수행하였다. 코팅재의 마찰과 마모특성은 작용된 하중과 미끄럼 속도에 의하여 다양하게 결정되었다. TiC와 TiN 그리고 TiC/TiN 코팅재는 표면에서 트라이볼로지 특성이 현저하게 증가하였다. 단층코팅에서는 TiC보다 TiN이 좋은 결과를 얻었다. 그러나, TiC/TiN의 다층코팅은 다른 어떤 단층코팅보다 좋은 성능을 보였다. 다층코팅의 성능이 향상된 핵심요소는 TiN층 외부와 강 사이에서 부착이 증가하게된 TiC의 역할 때문이다.