고온 코팅용 Cr-Al합금의 미세조직 및 특성에 미치는 Si 첨가의 영향

김정민,김일현,김현길,Kim, Jeong-Min,Kim, Il-Hyun,Kim, Hyun-Gil 한국재료학회 2019 한국재료학회지 Vol.29 No.1

Cr-Al alloys are attracting attention as oxidation resistant coating materials for high temperature metallic materials due to their excellent high temperature stability. However, the mechanical properties and oxidation resistance of Cr-Al alloys can be further enhanced, and such attempts are made in this study. To improve the properties of Cr-Al alloys, Si is added up to 5 wt%. Casting specimens with different amounts of Si content are prepared by a vacuum arc remelting method and isothermally heated under steam conditions at $1,100^{\circ}C$ for 1 hour. The as-cast microstructure of low Si alloys is mainly composed of only a Cr phase, while $Al_8Cr_5$ and $Cr_3Si$ phases are also observed in the 5 % Si alloy. In the high Si alloy, only Cr and $Cr_3Si$ phases remain after the isothermal heating at $1,100^{\circ}C$. It is found that Si additions slightly decrease the oxidation resistance of the Cr-Al alloy. However, the microhardness of the Cr-Al alloy is observed to increase with an increasing Si content.

레이저 표면 용융공정으로 Al-Cr 코팅한 Zr합금의 미세조직 특성

김정민,이재철,김일현,김현길,Kim, Jeong-Min,Lee, Jae-Cheol,Kim, Il-Hyun,Kim, Hyun-Gil 한국재료학회 2017 한국재료학회지 Vol.27 No.10

In this study, the coating of an Al-Cr layer on the surface of a Zircaloy-4 alloy was carried out through plasma pretreatment coating and a laser surface melting process. Two different conditions for laser treatment, severe or minimal surface melting of the Zr alloy substrate, were applied to form the final coating. When there was significant surface melting of the Zr alloy, the solidification microstructure of the newly formed coating layer was mainly composed of needle-shaped $Al_3Zr$, Al(Cr) and $Al_7Cr$ phases. On the other hand, the solidification microstructure of the coating layer was mainly composed of Al(Cr) and $Al_7Cr$ phases when there was minimal surface melting of Zr base in the laser process. However, when the coating was maintained at $1100^{\circ}C$ for 2 hours, significant inter-diffusion occurred between the phases in the coating. As a result, the upper part of the coating layer was observed to mainly consist of $Al_3Zr$ and $Al_8Cr_5$ phases, regardless of the laser treatment conditions.

건축건설공사의 공종별 위험도와 직무스트레스의 상관관계

김정민,이종빈,장성록,Kim, Jeongmin,Lee, Jong-Bin,Chang, Seong Rok 한국안전학회 2017 한국안전학회지 Vol.32 No.4

In this study, the risk level of architectural works was calculated by applying work period and number of input workers based on accidents records from 2012 to 2014 and the architectural works were divided into four groups(High-High, High-Low, Low-High, Low-Low) according to risk levels of fatal accidents and loss time accidents. And then questionnaire on the job stress level of workers was performed for 670 workers working in the architectural work using Korean Occupational Stress Questionnaire Form developed by KOSHA. And then the relationship between the risk level and job stress level of four groups was analyzed. Results showed that 1) risk levels of fatal and loss time accidents applied by work period and input workers were analyzed to be different with those of previous research based on the number of fatal and loss time accidents; 2) job stress level of workers has been analyzed to have a significant relationship with the risk level of fatal and loss time accident; 3) specially, the average of job stress level of 'HH(High-High)' group was higher than those of other groups; 4) among the subfactors of job stress, interpersonal conflict, job insecurity, organizational system and lack of reward were analyzed to be key factors to affect the risk level.

'항행의 자유 작전'의 전략적 접근

김정민,Kim, Jeong-Min 한국해양전략연구소 2021 해양안보 Vol.3 No.1

남중국해는 풍부한 해저 및 어로자원 뿐만 아니라 매년 4만여 척 이상의 선박이 통과하고, 세계 해양물류 50%, 원유 66%가 통과하는 중요한 해상교통로이다. 특히 대한민국의 수입 물동량의 30%, 에너지 수입량의 90%가 당 해역을 통과하고 있다. 미국과 중국은 이 해역의 중요성을 일찍이 깨달아 각각 '인도-태평양 전략', '일대일로(一帶一路) 전략'을 시행하는 등 국가전략적 차원에서 해양안보를 통한 국익을 구체화 하고 있다. 이런 지정학적 갈등은 남중국해에서 미국이 실시하는 '항행의 자유 작전'이라는 양상으로 드러나고 있다. 이러한 중요성에도 불구하고, 항행의 자유 작전에 대한 국내 연구는 미흡한 것이 사실이며, 기존 연구 대부분도 국제법과 국제 협약에 대한 분석을 중심으로 수행되었다. 본 논문은 항행의 자유 작전에 대한 전략적 인식을 통해 그 기원과 배경을 분석하고, 미·중 전략경쟁이 장기화되는 상황에서 한반도 안보에 주는 함의를 도출하고자 한다. The South China Sea is a significant maritime shipping route with abundant submarine and fishing resources. Over 40,000 ships pass through the South China Sea every year, constituting around 50% of global shipping and 66% of crude oil. In particular, 30% of Korea's import cargo and 90% of energy imports pass through this body of water. The US and China realized the significance of this sea area from early on and are embodying national interest through maritime security at the national strategic level by implementing the 'Indo-Pacific' and 'One Belt One Road' strategies, respectively. Such geopolitical conflicts are manifested in the 'freedom of navigation operations' by the US in the South China Sea. Despite its significance, there is a lack of studies in Korea on the freedom of navigation operations, and most previous studies only focus on analyzing international law and agreements. This article examines the origin and background of the strategic perception of the freedom of navigation operations and derives implications for the peace and security of the Korean Peninsula as the strategic competition between the US and China continues.

이슈&피플-제1회 <2007 윤이상 페스티벌>

김정민,Kim, Jeong-Min 대한출판문화협회 2007 출판저널 Vol.382 No.-

측두하악장애를 가진 성인여성에 있어 중절치부 최대교합력 유지양상

김정민,신금백,Kim, Chung Min,Shin, Geum Baek 대한안면통증구강내과학회 1987 Journal of Oral Medicine and Pain Vol.12 No.1

In order to evaluate the effect of signs and symptoms of temporomandibular disorders on the bite force of anterior teeth, the author estimated a feature of maintaining the maximum bite force on central incisors in Korean 34 adult females with signs and symptoms of temporomandibular disorders (TMD group) and in Korean 31 adult females within normal masticatory function far from any sign or symptom of TMD (control group), and analyzed the data statistically. The obtained results were as follows: 1. There was not a significant difference of the maximum bite force on central incisors between TMD group and control group (P>0.05). 2. The duration of maintaining the maximum bite force on central incisors in TMD group was shorter than it in control group (P<0.01).

내산화성 Cr-Si-Al합금의 주조상태 및 고온가열 후의 미세조직 특성

김정민,김채영,양원철,박준식,Kim, Jeong-Min,Kim, Chae-Young,Yang, Won-Chul,Park, Joon-Sik 한국재료학회 2021 한국재료학회지 Vol.31 No.3

Cr-Si based alloys are not only excellent in corrosion resistance at high temperatures, but also have good wear resistance due to the formation of Cr3Si phase, therefore they are promising as metallic coating materials. Aluminum is often added to Cr-Si alloys to improve the oxidation resistance through which stable alumina surface film is formed. On the other hand, due to the addition of aluminum, various Al-containing phases may be formed and may negatively affect the heat resistance of the Cr-Si-Al alloys, so detailed investigation is required. In this study, two Cr-Si-Al alloys (high-Si & high-Al) were prepared in the form of cast ingots through a vacuum arc melting process and the microstructural changes after high temperature heating process were investigated. In the case of the cast high-Si alloy, a considerable amount of Cr3Si phase was formed, and its hardness was significantly higher than that of the cast high-Al alloy. Also, Al-rich phases (with the high Al/Cr ratio) were not found much compared to the high-Al alloy. Meanwhile, it was observed that the amount of the Al-rich phases reduced by the annealing heat treatment for both alloys. In the case of the high temperature heating at 1,400 ℃, no significant microstructural change was observed in the high Si alloy, but a little more coarse and segregated AlCr phases were found in the high Al alloy compared to the cast state.

디지털화상의 기본특성

김정민,Kim, Jeong-Min 대한디지털의료영상학회 2005 대한디지털의료영상학회논문지 Vol.7 No.1

커뮤니티 검출기법을 이용한 소프트웨어 아키텍쳐 모듈 뷰 복원

김정민,이찬근,Kim, Jungmin,Lee, Changun 한국정보과학회 소프트웨어공학 소사이어티 2012 소프트웨어공학회지 Vol.25 No.4

본 논문은 소프트웨어 클러스터링 기법과 커뮤니티 검출 기법의 비교를 통하여 아키텍쳐 모듈 복원 프로세스에 커뮤니티 검출 알고리즘의 적용가능성을 제시한다. 또한, 대표적인 클러스터링 알고리즘과 커뮤니티 검출 알고리즘의 값과 나눠진 모듈간의 상관관계와 차이점을 분석한다. 이를 통하여 커뮤니티 검출 알고리즘이 소프트웨어 아키텍쳐 모듈 뷰 복원에 활용되어질 수 있다는 몇 가지 근거를 제시하였고, 기존의 클러스터링 결과와 커뮤니티 알고리즘의 결과치를 비교함으로써, 서로의 결과 데이터가 어떠한 연관성을 가지는지 제시하였다. This article suggests applicability to community detection algorithm from module recovering process of software architecture through compare to software clustering metric and community dectection metric. in addition to, analyze mutual relation and difference between separated module and measurement value of typical clustering algorithms and community detection algorithms. and then only sugeested several kinds basis that community detection algorithm can use to recovering module view of software architecture and, by so comparing measurement value of existing clustering metric and community algorithms, this article suggested correlation of two result data.

시나리오 플래닝기법을 활용한 한.중 FTA 체결이후의 한의서비스 시장 분석 및 대응전략

김정민,임병묵,신미숙,Kim, Jung-Min,Lim, Byung-Mook,Shin, Mi-Sook 대한예방한의학회 2012 대한예방한의학회지 Vol.16 No.2

Objectives : This study aimed to analyze the fundamentals of a Korea-China FTA and suggest strategies for Korean medicine market that correspond with each scenario selected from foreseen circumstances after the conclusion of the FTA through the scenario planning, which is one of management techniques. Methods : Four scenarios have been established by means of key questions : the scope of FTA, health care policies, and the combination of western medicine(WM) and Korean medicine(KM). Each scenario is defined as the Maximized Competitive Market, Neutral Market, General Completive Market, and Conservative Market. This study suggests brand marketing, extending of health insurance coverage, launching local network, and strategy for Korean medicine based health promotion programs. Results and Conclusions : Although Korean medicine could be prompted by the trade policies between countries, related studies are very limited. Therefore, more research is needed to suggest the detailed strategies for change of Korean medicine market through various strategic analysis tools.