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직조된 SiC 섬유에 무전해 구리도금 시 도금 조건의 영향
이기환(Kee Hwan Lee),손유한(Youhan Sohn),한태양(Taeyang Han),이경진(Kyung Jin Lee),김혜성(Hye Hung Kim),한준현(Jun Hyun Han) 한국표면공학회 2017 한국표면공학회지 Vol.50 No.4
Effects of plating conditions (dispersant concentration, plating time, and ultrasonication) on electroless Cu plating on SiC fabric woven by crossing of SiC continuous fibers vertically were studied. The ultrasonic dispersion treatment not only did not improve the dispersion of the SiC fibers, but also did not change the plating thickness. The ultrasonication in the pretreatment step of electroless plating did not improve the dispersion of the fibers, while the ultrasonication in the plating step enhanced the dispersion of the fibers and decreased the thickness of the Cu films. It was possible to control the thickness of the Cu coating layer as well as the dispersion of the fibers in the fabric by changing the plating conditions such as dispersant concentration, plating time, and ultrasonication, but it was very difficult to coat copper on the intersection of vertical fibers in the fabric.
무전해 Cu 도금층의 두께와 표면조도에 미치는 도금조건의 영향
이기환 ( Kee Hwan Lee ),박상진 ( Sang Jin Park ),한준현 ( Jun Hyun Han ) 대한금속재료학회(구 대한금속학회) 2016 대한금속·재료학회지 Vol.54 No.4
Copper thin films were coated on polyethylene terephthalate(PET) substrates by electroless plating. The effects of the ultra-sonication, the initial roughness of the PET substrates, and the plating time on the thickness and roughness of the electroless-plated Cu deposits were studied. The thickness and roughness of the Cu deposits were measured by scanning electron microscopy(SEM) observations and a surface profiler. In the early stage of Cu plating, the ultra-sonication and high initial roughness of the PET substrates promoted an increase in the thickness of the Cu deposits, but they suppressed the increase in thickness of the Cu deposits when plated for a long time. The surface roughness of the Cu deposits plated on PET with a very low initial roughness increased with plating time due to the agglomeration of Cu atoms. However, the surface roughness of the Cu deposits on the PET with a high initial roughness decreased with increasing plating time, since the deep valleys of the rough PET surface were filled with Cu atoms preferentially.
Modeling Technology on Free-form Surface of a New Military Personal Head using Quick Surface Method
Yong-Moon Lee(이용문),Tae-Son Hwang(황태선),Hun-Kim(김훈),Hee-Tae Nam(남희태),Kee-Hwan Lee(이기환),Myungchang Kang(강명창) 한국기계가공학회 2018 한국기계가공학회지 Vol.17 No.6
Recently, weapon system requires personal protection products due to the explosion of rapid-fire explosion, which is considered to be multi threat in modernization, complication and war against terrorism. However, the conventional Korean military bullet protection helmets are not suitable for wearing convenience and combatant interoperability in terms of ergonomic. In this paper, we propose a suitable 3D Scanning method for the head, and compare the measured 3D dimension with the existing 2D measurement value to identity the reliability. Reverse engineered soldier head using the quick surface method was realized with a perfect free-form surface and satisfactory tolerance range (±0.2 mm). Through the comparison of 3D and 2D measured head dimensions, the absolute error value was 0.73 mm on average and relative error was 0.35 %, confirming the high accuracy of the 3D scan modeling. Also, quick surface method using 3D scanner is suggested a fast and accurate skill for ergonomics in obtaining the head modeling needed for military’s personal bullet protection helmet design.
이동원 ( Dong Won Lee ),석기준 ( Kee Joon Seok ),이기환 ( Ki Hwan Lee ) 한국환경정책평가연구원 2010 환경정책연구 Vol.9 No.4
최근 환경문제는 사회적 이슈가 되고 있을 뿐만 아니라 기업경영에서 차지하는 비중이 증가하는 추세이다. 본 연구는 환경경영체제의 하나인 ISO 14001 인증을 받은 철강기업을 대상으로 인증 전후, 인증 기업의 규모 및 인증 유지기간 등이 경영성과와 어떤 관계에 있는지를 분석하였다. 분석결과를 요약하면 다음과 같다. 첫째, 인증 전ㆍ후의 경영성과 분석결과 인증 이후 부채비율이 유의하게 낮아졌으며, 매출액증가율은 유의하게 높아졌다. 둘째, 인증 유지기간에 대한 분석결과 기업의 위험성을 나타내는 유동비율, 부채비율 및 고정장기적합률이 인증기간이 길수록 개선되는 것으로 나타났다. 셋째, 인증기업의 기업규모변수로 상시근로자 수를 이용한 분석결과 매출액총이익률과 총자산회전율이 유의한 차이를 나타냈다. 넷째, 인증 전후에 대한 로지스틱 회귀분석 결과 부채비율과 매출액증가율이 유의한 것으로 나타났다. This paper analyzes the firm`s financial characteristics, influence over the adoption of the ISO 14001 adoption in our analyses. We used the T-test, a logistic regression analysis. We chose 112 Steel Enterprises from Korea Accreditation Board. The independent variables are current ratio, debt ratio, fixed assets to net worth and fixed liabilities, gross margin on sales, total assets turnover, net sales growth rate. This study tests three hypotheses on management performance of adoption of ISO 14001. The main findings are as follows. The first hypothesis is supported in terms of debt ratio, fixed assets to net worth and fixed liabilities, net sales growth rate at the 1%, 5%, 5% significance level. The second one is supported in terms of current ratio, debt ratio, fixed assets to net worth and fixed liabilities at the 10%, 1%, 1% significance level. The third one is supported in terms of gross margin on sales, total assets turnover at the 1%, 10% significance level. These findings have important implications for future research. Regulatory, market and social pressures for environmental consideration may prompt many facilities to adopt EMS`s when they lack the complementary resources and capabilities that foster continual environmental improvement over time.