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.

송강(松江)의 한시(漢詩)에 나타난 자연관(自然觀)

김정민 ( Jeong Min Kim ) 한국한자한문교육학회 2007 漢字 漢文敎育 Vol.18 No.-

송강 정철(1536~1593)은 조선시대 중기에 가장 활발한 활동을 한 위정자이자 문인이기도 하다. 당시의 시대상황은 사화(1544)와 당쟁, 그리고 임란(1592) 등으로 혼란했던 시대였다. 정철은 이러한 사회상을 배경으로 처절했던 삶의 체험을 대자연의 관계 속에서 형상화 내어 독창적인 창작세계를 구축해 많은 작품을 남겼다. 본고는 송강 한시의 자연관의 연구의 일면으로 그의 삶의 체험에 의한 사상과 감정의 주관적인 세계가 자연물에 대한 객관적인 대상의 실경보다 그의 주관적인 심회에 치중하여 시적 형상화한 심미적 특징을 검토하였다. 그의 한시에 나타난 자연물 중에 운과 월, 강과 산, 꽃과 나무, 새 등이 주요 소재로 다루어졌다. 연군의 상징적 의미로 시적 형상화된 자연물은 달, 산(봉래산·종남산), 물(한강)이며, 연군을 향한 충정의 상징된 시어는 해와 학, 그리고 매화가 표현되었다. 벗과의 별리의 상징의 자연물은 대나무·소나무·연꽃에서 나타난다. 송강의 은거의 처지가 상징된 자연물은 백운·벽운 등의 구름과 매화·난초·국화의 꽃과 학·갈매기·기러기 등의 새, 그리고 대나무·소나무·잣나무 등의 나무에서 우국충정과 송강의 깊은 심회에 대한 외로운 신하의 애절한 정을 표현하고 있었다. 한시에 나타난 자연물들은 대부분이 직관에 의한 즉흥즉사로 표현한 것이 많았다. 이는 대자연의 관계에서 객관적인 대상보다 주관적인 심회가 유정화된 창작특징으로 나타났다. 당대 문학창작의 조탁의 진통을 통한 단아완숙한 창작세계와는 다른 독특한 한시세계의 특질과 의의가 있다는 것을 파악하게 되었다. 따라서 송강의 한시는 조탁되지 않은 즉흥즉사의 창작세계였지만 그만의 진면목이 그대로 표출되는 역동적인 기운생동의 미적특질을 지닌 독특한 창작세계로 이후 국문시가의 창작에 지대한 영향을 주었다고 본다. Song-gang(1536~1593), as Jeong-cheol by real name, was a man of letters and administrator who worked more actively than any other in the middle period of Chosun Dynasty. Under those circumstances, by scholar-massacre(1544), intra-party conflicts and Im-jin Japanese infiltration(1592), it was thrown into extremely confusional age. With these social backgrounds Jeong-cheol left a lot of his literary works behind by means of constructing his original creative poetry world with the embodiment of his heartbreaking experience of life in the relationship between man and nature. This study aims to review carefully his aesthetic keynote poetically embodied by concentrating his own thought and feeling from his life experience on his subjective envisagement more than the entity of objective thing of a natural object as an aspect of studying for a view of nature in Song-gang`s Chinese poems. Of all his natural objects expressed in Chinese poems, the moon with clouds, rivers and mountains, flowers, trees and birds were treated main literary motifs. The natural object as the symbolic poetic metaphor of yearning for his king of lord was embodied as the moon and mountains (Bongnae-san, Jongnam-san) and waters (the Han-Gang). And the poetic words of loyalty toward his king of lord were symbolized in the expression of the sea, a crane, and an apricot blossom. As a parting symbol of natural objects from the bosom friends were easily found in a bamboo, a pine tree, a lotus blossom. Moreover his retire to hermitage in the mountain were also found in the white clouds and green clouds and the flowers of an apricot tree, an orchid, a chrysanthemum and the birds of a crane, a pigeon and a wild goose, and further, the trees of a bamboo, a pine and a cone pine with his deep sense of worrying the nation expressed as a lonesome vassal`s pathetic feeling. Most of his natural objects expressed in Chinese poems were expressed by intuition as a pointing-an-enthusiastic-thing-means-a-poetic-matter way. In this sense, in the relationship between man and nature, his subjective envisagement appeared as sympathetic creative writing feature more than the entity of objective thing of a natural object. Thus, Song-gang`s Chinese poems was a creative writing world of a pointing-a-thing-means-a-poetic-matter way without any carving and polishing, but all of them seemed to reveal his true character as-it-is base and as a unique world of creative literature with a dynamic and aesthetic property with high-spirited vitality, Song-gang`s Chinese poems have exerted enormous influence on the creative works of Korean poetry.

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.

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.

바디 구동 차동 입력단과 Self-cascode 구조를 이용한 0.5 V 2단 연산증폭기 설계 및 제작

김정민,이대환,백기주,나기열,김영석,Gim, Jeong-Min,Lee, Dae-Hwan,Baek, Ki-Ju,Na, Kee-Yeol,Kim, Yeong-Seuk 한국전기전자재료학회 2013 전기전자재료학회논문지 Vol.26 No.4

This paper presents a design and fabrication of 0.5 V two stage operational amplifier. The proposed operational amplifier utilizes body-driven differential input stage and self-cascode current mirror structure. Cadence Virtuoso is used for layout and the layout data is verified by LVS through Mentor Calibre. The proposed two stage operational amplifier is fabricated using $0.13{\mu}m$ CMOS process and operation at 0.5 V is confirmed. Measured low frequency small signal gain of operational amplifier is 50 dB, power consumption is $29{\mu}W$ and chip area is $75{\mu}m{\times}90{\mu}m$.

단결정 반금속 비스무스 단일 나노선의 Shubnikov-de Haas 진동

김정민,함진희,심우영,이경일,전계진,정원용,이우영,Kim, Jeong-Min,Ham, Jin-Hee,Shim, Woo-Young,Lee, Kyoung-Il,Jeon, Kye-Jin,Jeung, Won-Young,Lee, Woo Young 한국재료학회 2008 한국재료학회지 Vol.18 No.2

The magneto-transport properties of an individual single crystalline Bi nanowire grown by a spontaneous growth method are reported. A four-terminal device based on an individual 400-nm-diameter nanowire was successfully fabricated using a plasma etching technique that removed an oxide layer that had formed on the surface of the nanowire. Large transverse ordinary magnetoresistance (1401%) and negative longitudinal ordinary magnetoresistance (-38%) were measured at 2 K. It was observed that the period of Shubnikov-de Haas oscillations in transverse geometry was $0.074^{T-1}$, $0.16^{T-1}$ and $0.77^{T-1}$, which is in good agreement with those of bulk Bi. However, it was found that the period of SdH oscillation in longitudinal geometry is $0.24^{T-1}$, which is larger than the value of $0.16^{T-1}$ reported for bulk Bi. The deviation is attributable to the spatial confinement arising from scattering at the nanowire surface boundary.

이슈&피플-제1회 <2007 윤이상 페스티벌>

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

Ceromer (Targis)에 의한 법랑질 마모에 관한 연구

김정민,이선형,양재호,Kim, Jeong-Min,Lee, Sun-Hyung,Yang, Jae-Ho 대한치과보철학회 2000 대한치과보철학회지 Vol.38 No.4

The ideal restorative material should mimic the properties of the tissues it replaces. Dental composite resins have been used widely as restorative materials due to its advantages such as excellent esthetics and ease of manipulation. But inadequate wear resistance has been a major factor limiting the use of composite restorative materials. Improved manufacturing techniques have allowed the development of hybrid composites, with a greater percentage volume filler loading, which have improved physical and mechanical properties. However they are lacking in the study of wear resistance. The purpose of this study was to evaluate the wear of human enamel against ceromer by the use of a pin-on-disk type wear testers. Discs of ceromer(Targis ; lvoclar Vivadent, Amherst. NY) and discs of type III gold alloy as a control were used f9r test specimens. Intact cusp of premolar and molar were used for enamel specimens. The wear of enamel was determined by weigh-ing the cusp before and after each test, and the weight converted to volumes by average densi-ty of enamel. Surface profilometer was used to quantify wear of the ceromer and gold specimens. Vicker's hardness tester was used to evaluate the surface hardness of test specimens. The SEM was used to evaluate the wear surfaces The results were as follows; 1. Ceromer produced less enamel wear than gold(p<0.05) 2. The wear volume of ceromer was greater than that of gold(p<0.01) 3. The hardess of ceromer was lower than that of gold, but there was no correlation between the hardness and wear of the ceromer and gold. 4. SEM analysis revealed that there were many voids and microcracks in the wear tract of ceromer In gold group, many minute V-shaped grooves were examined.

디지털화상의 기본특성

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

'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.