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이명훈(Myeong-Hoon Lee),신승중(Seung-Jung Shin),곽계달(Kae-Dal Kwack) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.11
LEDs which have many merits are widely used in the field of light devices, and have rapidly replaced old light devices such as incandescent or fluorescent lamps. Long life, on the order of 50,000 to 100,000 hours, is one of the key features of light emitting diodes(LEDs) that has attracted the lighting community to this technology. High Power white LEDs have yet to demonstrate this capability. This paper planed accelerated life test that has two factor(temperature, current) and two levels. Finally, using ALTA programs, we estimated the common shape parameter of Weibull distribution, life-stress relationship, B10 life and accelerating factors.
건습식 혼합공정을 이용한 유연소재 상 전자파 차폐용 다층막 코팅
이훈성(Hoon-Seung Lee),이명훈(Myeong-Hoon Lee) 한국표면공학회 2017 한국표면공학회지 Vol.50 No.5
Dry processes like evaporation and sputtering in vacuum chamber are difficult to make a uniform, large area and high quality film on thin PET substrate because of PET degradation and bad adhesion. On the other hand, wet processes like electro or electroless plating have complex processes and require high environmental cost. In this study, we successfully prepared 2 μm Zn/Cu/Ni multilayers coated on 12 μm polyethylene terephthalate (PET) substrate by using dry-wet mixing processes. Their surface electric resistances were evaluated around 0.2 Ω by using 4 probe measurements. Furthermore, their corrosion resistance also evaluated by natural potential test and compared with other wet, dry and mixing process samples.
스테인리스강 프로펠러축의 가공에 따른 재질특성에 관한 연구
손영태,정광교,이명훈,Son, Yeong-Tae,Choung, Kwang-Gyo,Lee, Myeong-Hoon 선박안전기술공단 2008 선박안전 Vol.24 No.-
Stainless steel 304 or stainless steel 630 types using propeller shaft of a small ship or a FRP fishing boat generally restrain localization corrosion and abrasion damage occurrence to shaft bearing or grand packing contact. In general, the residual stress which remains after welding or heat treatment in material can cause the stress concentration or localization corrosion. In case of small ship, stainless steel such as STS304 has long been used for propeller shaft. Meanwhile, crew of small ship tend to reuse damaged propeller shaft after repair by welding and performing heat treatment to save cost. However, it was found that reused propeller shaft by repair often caused troubles in ship's operation. In this study, the basic guideline for maintenance and treatment of propeller shaft are investigated. From the results of investigation, remarkable deterioration of the material properties and corrosion resistance on the welded work part was observed.
천연해수 중 전류밀도 변화에 따라 형성된 환경친화적인 전착 코팅막의 특성 분석
이찬식(Chan-Sik Lee),배일용(Il-Yong Bae),김기준(Ki-Joon Kim),문경만(Kyung-Man Moon),이명훈(Myeong-Hoon Lee) 한국표면공학회 2004 한국표면공학회지 Vol.37 No.5
Calcareous deposits are the consequence of pH increase of the electrolyte adjacent to metal surface affected by cathodic current in seawater. It obviously has several advantages over conventional coatings, since the calcareous deposit coating is formed from coating (Mg²?, Ca²?) naturally existing in seawater. In consideration of this respect, environment friendly calcareous deposit films were formed by an electro deposition technique on steel substrates submerged in 48℃ natural seawater. And the influence of current density, coating time and attachment of steel mesh on composition ratio, structure and morphology of the electrodeposited films were investigated by Scanning Electron Microscopy(SEM), Energy Dispersive Spectroscopy(EDS) and X-Ray Diffractor(XRD), respectively. Accordingly, this study provides a better understanding of the composition between the growth of Mg(OH)₂ and CaCO₃ during the formation of electro deposit films on steel substrate under cathodically electrodeposition in 48℃ natural seawater. The Mg compositions, in general, are getting decreased regardless of current density but Ca compositions are getting increased as electrodeposition time runs. That is, Mg(OH)₂ compounds of brucite structure shaped as flat type is formed at the initial stage of electrodeposition, but CaCO₃, compounds of aragonite structure shaped as flower type is formed in large scale. Besides, Mg(OH)₂ compounds were much formed at 5 A/㎡ environment condition compared to the 3 A/㎡ and 4 A/㎡ environment conditions. This is because that OH? which was comparatively largely generated at the metal surface is preferably combined with Mg²?.
무전해 Ni-P 도금막의 형성과 Turn over에 따른 막의 특성비교
이영호(Yeong-Ho Lee),윤용섭(Yong-Sub Yun),장지연(Ji-Yon Jang),문경만(Kyung-Man Moon),이명훈(Myeong-Hoon Lee) 한국해양대학교 해사산업연구소 2002 海事産業硏究所論文集 Vol.12 No.-
Electroless Nickel(EN) plating method among the surface modification techniques is today one of the most fastly growing sectors in the material surface finishing industry. EN plating, in general, provides high precision functional coatings for industrial applications requiring; corrosion protection, high hardness, uniform thickness, less porosity, increased lubricity and wear resistance, etc. During EN plating, however, by-products of the chemical reaction, including orthophosphite, sodium sulfate, and ammonia, build up and decrease bath performance. As the concentrations of by-products increase, the nickel deposition rate decreases. In addition, the nickel plating becomes more porous and intrinsic-stressed, and its appearance becomes less lustrous. Physical properties such as magnetics and solderability may also be adversely affected. With the increase of metal turn over, the deposition rate, hardness and bath performance in the electro less plating are decreased, however, the corrosion behaviors of the electroless plated Ni-P films showed nearly low corrosion tendency. And the film morphology became from columnar to granular structure and the surface grain size decrease with the increase of metal turn over. On the other hand, the phosphorous content of electroless plated Ni-P films becomes increase, and the films tend to show more porous. Eventually, the properties comparison of the electroless plated Ni-P films can be explained by analyzing the content ratio of nickel and phosphorous, the grain size of surface, the morphology of cross section in the plated film in relation with metal turn over.
해수 중 CO₂ 기체의 유입에 의한 환경 친화적인 전착 코팅막의 형성과 그 내식특성
이성준(Sung-Joon Lee),김혜민(Hye-Min Kim),이슬기(Seul-Gee Lee),문경만(Kyung-Man Moon),이명훈(Myeong-Hoon Lee) 한국표면공학회 2014 한국표면공학회지 Vol.47 No.1
The peculiar feature of cathodic protection in seawater has the capability to form mineral calcareous deposits such as magnesium and calcium on metal surfaces. It is assumed that OH? ions are generated close to the metal surface as a result of cathodic protection and generated OH? ions increases the pH of the metal/seawater interface outlined as the following formulae. (1) O₂+ 2H₂O + 4e→4OH?, or (2) 2H₂O + 2e→H₂+ 2OH?. And high pH causes precipitation of Mg(OH)₂ and CaCO₃ in accordance with the following formulae. (1)Mg<SUP>2+</SUP>+ 2OH?→Mg(OH)₂, (2) Ca<SUP>2+</SUP>+ CO₃<SUP>2?</SUP>→CaCO₃. The focus of this study was to increase the amount of CO₃<SUP>2?</SUP> with the injection of CO2 gas to the solution for accelerating process of the following formulae. (1) H₂O+CO₂→H₂CO₃, (2) HCO<SUP>3?</SUP>→ H++ CO₃<SUP>2?</SUP>. Electrodeposit films were formed by an electro-deposition technique on steel substrates in solutions of both natural seawater and natural seawater dissolved CO₂ gas with different current densities, over different time periods. The contents of films were investigated by scanning electron microscopy(SEM) and X-ray diffraction(XRD). The adhesion and corrosion resistance of the coating films were evaluated by anodic polarization. From an experimental result, only CaCO₃ were found in solution where injected CO₂ gas regardless of current density. In case of injecting the CO₂ gas, weight gain of electrodeposits films hugely increased and it had appropriate physical properties.
선박 해수배관에서 용접봉의 종류에 따라 직류 아크 용접한 용접부위의 부식특성에 관한 전기화학적 평가
이성열(Sung-Yul Lee),이규환(Kyu-Hwan Lee),원창욱(Chang-uk Won),나승수(Shane Na),윤영곤(Young-Gon Yoon),김윤해(Yun-Hae Kim),이명훈(Myeong-Hoon Lee),문경만(Kyung-Man Moon),김진경(Jin-Gyeong Kim) 한국해양공학회 2013 韓國海洋工學會誌 Vol.27 No.3
The seawater pipes in the engine rooms of ships are surrounded by severely corrosive environments caused by fast flowing seawater containing chloride ions, high conductivity, etc. Therefore, it has been reported that seawater leakage often occurs at a seawater pipe because of local corrosion. In addition, the leakage area is usually welded using shielded metal arc welding with various electrodes. In this study, when seawater pipes were welded with four types of electrodes(E4311, E4301, E4313, and E4316), the difference between the corrosion resistance values in their welding zones was investigated using an electrochemical method. Although the corrosion potential of a weld metal zone welded with the E4316 electrode showed the lowest value compared to the other electrodes, its corrosion resistance exhibited the best value compared to the other electrodes. In addition, a heat affected zone welded with the E4316 electrode also appeared to have the best corrosion resistance among the electrodes. Furthermore, the corrosion resistance of the weld metal zone and heat affected zone exhibited relatively better properties than that of the base metal zone in all of the cases welded with the four types of electrodes. Furthermore, the hardness values of all the weld metal zones were higher than the base metal zone.
강맹훈(Kang, Maeng-Hoon),송혜승(Song, Hye-Seung),이명훈(Lee, Myeong-Hun) 대한건축학회 2017 대한건축학회논문집 Vol.33 No.6
The purpose of this study is to suggest implications for policy direction about urban regeneration projects in Seoul. This study compares different factors affecting a resident group"s and an expert"s group"s satisfaction level on the urban regeneration projects. The results are as follows: First, the expert group is happier with the urban regeneration projects than the resident group. Second, two groups think a promotional project is important for urban regeneration. Third, there are various factors affecting the risident"s group"s satisfaction level on urban regeneration. And the resident group has high expectation for the local government. Forth, the expert group considers that the higher local attachment is, the happier the residents are. However, local attachment is not related to satisfaction of residents on urban regeneration project. These are implications for the future policy. First, we need projects or programs which can make residents realize they are a main body of urban regeneration projects because they don"t usually think they are an important part of urban regeneration projects. Second, expert group should consider additional factors which can make residents happy when they make a plan of urban regeneration.