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Plasma post-oxidation of nitrocarburized SUM 24L steel
Jeon, Eun-Kab,Park, Ik Min,Lee, Insup Elsevier 2007 Materials science & engineering. properties, micro Vol.449 No.-
<P><B>Abstract</B></P><P>Plasma nitrocarburizing and plasma oxidizing treatments were performed to improve the wear and corrosion resistance of SUM 24L steel. Plasma nitrocarburizing was conducted for 3h at 570°C in the nitrogen, hydrogen and methane atmosphere to produce the ϵ-Fe<SUB>2–3</SUB>(N, C) phase. It was found that the compound layer produced by plasma nitrocarburising was predominantly composed of ϵ-phase, with a small proportion of γ′-Fe<SUB>4</SUB>(N, C) phase. The thickness of the compound layer was about 10–15μm and the diffusion layer was about 150μm in thickness, respectively. Plasma post-oxidation was performed on the nitrocarburized samples with various oxygen/hydrogen ratio at constant temperature 500°C for 1h. The very thin magnetite (Fe<SUB>3</SUB>O<SUB>4</SUB>) layer 1–2μm in thickness on top of the compound layer was obtained by plasma post-oxidation. It was observed that the thickness of the compound layer decreased with decreasing oxygen/hydrogen ratio. It was also confirmed that the corrosion characteristics of the nitrocarburized compound layer was further improved by the application of the superficial magnetite layer.</P>
Jeon, Min-Yeong,Kyung, Kab-Soo,Lee, Sung-Jin,Park, Jin-Eun Springer-Verlag 2018 International Journal of Steel Structures Vol.18 No.1
<P>Currently, there is increased concern regarding environmental pollution, and research has been conducted to assess the life cycle of environmental pollutants to determine environmental compatibility. In particular, an SOC facility is expected to severely affect the environment since various materials are used through complex processes. However, countermeasures and research regarding environmental pollution in SOC facilities are insufficient. This study built design data about the steel box girder bridges of 120 that have been designed since 2000, and life cycle assessments were carried out in the planning stage. First, a standard classification of steel bridges was established, and a detailed statement of the design for basic design data and input materials for each target bridge was analyzed, and the environmental load amounts for each material that is used was estimated by applying LCI DB, presented as a characteristic value and weighted value. A correlation analysis was conducted to select the influence during the planning stage. We developed an environmental load amounts calculation model using casebased reasoning. The environmental load amounts and the estimation of the environmental load models was derived from this study and considered to be useful to produce basic data in life cycle assessment when designing steel bridges.</P>
생애주기비용 분석을 통한 소수거더교의 경제성 분석에 관한 연구
전은경(Jeon Eun-Kyoung),경갑수(Kyung Kab-Soo),박혜연(Park Hye-Yeon),강신화(Kang Sin-Hwa) 한국철도학회 2009 한국철도학회 학술발표대회논문집 Vol.2009 No.11월
Recently, the technical development of steel plate girder railway bridge like 2-girder are developing in ways to maximize its durability of materials in use of high strength and efficiency of maintenance, ets. In addition, it is also expected to reduce the cost of bridge construction. Also, It makes a demand of LCC that rises the one of the essential ways in economic evaluation of the construction. In case of Korea, so many projects about LCC have been carried out only PSC bridge, RC bridge, ST.box girder bridge that have construction accomplishment. But there is a study of phase steel plate bridge. Therefore, in this study, we performed the analysis of economic efficiency of steel plate girder bridge around the road bridge having high accomplishment to extend the application of Steel plate girder bridge and railroad bridge. In this paper, representative item and representative section was calculated with analysis of weight and quantity in accordance with item and designed section about the steel plate girder bridge. Be based on this result, analysis of economic efficiency is performed through LCC. Results of study, And 3 girder is economic when discounr rate is under 2% and 2 girder is economic when discounr rate is over 2% in results of sesitivity analysis.
사업 수행 단계별 강박스거더교 공사비 산정 모델 제시 및 검증
전은경,경갑수,박진은,강신화,Jeon, Eun-Kyoung,Kyung, Kab-Soo,Park, Jin-Eun,Kang, Sin-Hwa 한국강구조학회 2010 韓國鋼構造學會 論文集 Vol.22 No.1
공공 건설공사에서 공사 단계별 합리적인 공사비를 산정하는 것은 국가 예산의 효율적 확보 및 집행 등에 있어 매우 중요한 요소이다. 일반적으로 공사예정가격은 대상 구조물의 설계 종료시점에서 산출된다. 그러므로 대상 구조물의 구체적인 상세 단면이 주어지지 않은 기획단계 및 설계초기단계에서 교량 구조물에 대한 단순 정보만을 가지고 개략공사비를 추정하는 것은 상당히 어려운 문제일 것으로 생각된다. 본 연구에서는 선행연구에서의 61개의 강박스거더교 공사비 분석에 의해 효율적이고 적절한 기획단계 및 설계초기단계의의 개략공사비 산정 모델의 제시 및 타당성을 검증하고자 한다. 연구결과, 본 연구에서 제시된 공사비 산정 모델에 의해 얻어진 추정공사비는 기존에 사용된 방법과 비교할 때 매우 높은 신뢰도를 갖는 것을 알 수 있었다. To effectively secure and execute the national budget, it is very important to estimate the reasonable construction cost of each process in the construction of public facilities and works. The construction cost is generally estimated at the time when the design of the targeted structures has been completed. Without detailed sectional drawings and with only simple information on bridge structures in the planning stage or in the early design stage. it would be very difficult to predict the approximate construction cost. In this study, a more efficient and appropriate approximate construction cost estimation model in the planning stage and in the early design stage is presented and verified as reliable by analyzing the construction cost data of 61 existing steel box girder bridges from previous studies. The results of this study show that when the construction cost that was predicted using the construction cost estimation model in the design stage was compared with the cost from the conventional standards, the suggested model in this study produced results with a very high confidence level.
자동차 엔진부품용 Shaft에 플라즈마 산질화기술 적용
전은갑,박익민,이인섭,Jeon, Eun-Kab,Park, Ik-Min,Lee, In-Sup 한국재료학회 2006 한국재료학회지 Vol.16 No.11
Plasma nitrocarburising and plasma post oxidation were performed to improve the wear and corrosion resistance of S45C and SCM440 steel by a plasma ion nitriding system. Plasma nitrocarburizing was conducted for 3h at $570^{\circ}C$ in the nitrogen, hydrogen and methane atmosphere to produce the ${\varepsilon}-Fe_{2-3}$(N, C) phase. Plasma post oxidation was performed on the nitrocarburized samples with various oxygen/hydrogen ratio at constant temperature of $500^{\circ}C$ for 1 hour. The very thin magnetite ($Fe_3O_4$) layer $1-2{\mu}m$ in thickness on top of the $15{\sim}25{\mu}m$ ${\varepsilon}-Fe_{2-3}$(N, C) compound layer was obtained by plasma post oxidation. A salt spray test and electrochemical testing revealed that in the tested 5% NaCl solution, the corrosion characteristics of the nitrocarburized compound layer could be further improved by the application of the superficial magnetite layer. Throttle valve shafts were treated under optimum plasma processing conditions. Accelerated life time test results, using throttle body assembled with shaft treated by plasma nitrocarburising and post oxidation, showed that plasma nitrocarburizing and plasma post oxidation processes could be a viable technology in the very near future which can replace $Cr^{6+}$ plating.