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.

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.

'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.

일본뇌염바이러스의 Mutant M 단백질에 반응하는 다클론항체의 생산: 극성 아미노산 잔기의 바이러스 생산과정에서의 역할

김정민,윤상임,송병학,김진경,이영민,Kim, Jeong-Min,Yun, Sang-Im,Song, Byung-Hak,Kim, Jin-Kyoung,Lee, Young-Min 한국미생물학회 2010 미생물학회지 Vol.46 No.2

일본뇌염바이러스(Japanese encephalitis virus)는 모기 매개성 플라비바이러스에 속하며, 주로 동남아시아 지역에서 유행성 바이러스성 뇌염을 일으킨다. 일본뇌염바이러스는 외피를 가진 작은 바이러스로서, 양성가닥 RNA 게놈을 가지고 있다. 감염성을 띤 바이러스 입자는 capsid (C), membrane (M; prM 전구체로부터 생성), 및 envelope (E)과 같은 3개의 구조단백질로 이루어져 있다. 본 연구에서는 일본뇌염바이러스 생산과 정에 M 단백질의 N-말단부위에 위치한 극성 아미노산 잔기의 역할을 분석하였다. 일본뇌염바이러스의 infectious cDNA를 활용하여, M 단백질의 $E^9$와 $K^{15}K^{16}E^{17}$ 잔기를 알라닌으로 치환시킨 2개의 mutant cDNA (Mm1과 Mm2)를 각각 제작하였다. 각각의 cDNA로부터 합성된 mutant RNA를 세포에 트랜스펙션시킴으로써, 비록 세포 내에 축적된 3개의 구조단백질양은 변화가 없으나, 이들 세포로부터 생산된 바이러스의 양은 Mm2 RNA의 경우 ~1,000배 감소됨을 관찰하였다. 흥미롭게도, Mm2 RNA로부터 발현된 mutant M 단백질은 wild-type M 단백질을 인지하는 항혈청에는 반응하지 않았으나, mutant M 단백질을 항원으로 제작된 항혈청에는 반응하는 것을 알 수 있었다. 본 실험결과는 일본뇌염바이러스 M 단백질을 구성하는 3개의 극성 아미노산 잔기($K^{15}K^{16}E^{17}$)가 바이러스의 생산과정에 관여한다는 것을 암시한다. 앞으로, wild-type 또는 mutant M 단백질(Mm2)을 인식하는 2개의 항혈청은 이 단백질의 기능연구에 유용한 재료로 사용될 것으로 기대된다. Japanese encephalitis virus (JEV), a member of the mosquito-borne flaviviruses, causes epidemics of viral encephalitis in the Southeastern Asia. JEV is a small enveloped virus with a positive-sense RNA genome; the infectious virion consists of three structural proteins, namely capsid, membrane (M; a mature form of its prM precursor), and envelope proteins. Here, we investigated a role of the charged residues found at the N-terminus of the JEV M protein in virus production. Using an infectious JEV cDNA, we generated two mutant cDNAs, Mm1 and Mm2, by charged-to-alanine substitution for $E^9$ and $K^{15}K^{16}E^{17}$ residues of the M protein, respectively. By transfection of wild-type or each of the two mutant RNAs transcribed from the corresponding cDNAs, we found that Mm2, but not Mm1, had a ~3-log decrease in virus production, even though a comparable amount of all three structural proteins were produced in transfected cells. Interestingly, the prM protein expressed in Mm2 RNA-transfected cells was not recognized by the polyclonal antiserum raised against the N-terminal 44 amino acids of the wild type M protein, but reacted to the antiserum raised against the corresponding region of the mutant Mm2. Our results indicate that three charged residues ($K^{15}K^{16}E^{17}$) in JEV M protein play a role in virus production. Two polyclonal antisera specifically recognizing the wild-type or Mm2 version of the M protein would provide a useful reagent for the functional study of this protein in the virus life cycle.

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).

타워크레인 설치 및 해체

김정민,Kim, Jeong-Min 한국건설안전협회 1995 建設 安全技術 Vol.17 No.-

의료용 디지털영상계의 특성곡선의 작성법

김정민,Kim, Jeong-Min 대한디지털의료영상학회 2006 대한디지털의료영상학회논문지 Vol.8 No.1

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.

전 상악골 절제술 후 양경 유리 견갑 골-피부 피판을 이용한 재건 3례

김정민,하범준,문구현,현원석,방사익,오갑성,Kim, Jung-Min,Ha, Bom-Jun,Mun, Goo-Hyoun,Hyun, Won-Sok,Bang, Sa-Ik,Oh, Kap-Sung 대한미세수술학회 2003 Archives of reconstructive microsurgery Vol.12 No.1

We used bipedicled scapular osteocutaneous free flap for total maxillectomy defect reconstruction in 3 cases of malignant maxillary tumor. We elevated two flaps of the skin paddle and the bone flap with one common pedicle - the subscapular artery - which was devided to the angular branch of the thoracodorsal artery and the circumflex scapular artery to reconstruct the nasal cavity, the palate and the zygoma. The angle between the two flaps was free enough so that we could transfer the two flaps through a single microanastomosis. After the operation, patients could swallow and pronounce well, and the wound contracture was minimal so that we could get aesthetically good result.