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양극산화에 의해 CP Ti와 Ti-10Ta-10Nb 합금 표면에 형성된 산화 피막의 형상 및 표면 특성
김현승,이광민,이도재,박상원,이경구,Kim, Hyun-Seung,Kee, Kwang-Min,Lee, Doh-Jae,Park, Sang-Won,Lee, Kyung-Ku 한국재료학회 2007 한국재료학회지 Vol.17 No.1
In the present study, we investigated the formation of self-organized nanostructure oxide layers on CP Ti and Ti-10Ta-10Nb alloy in an electrolyte of 1M phosphoric acid and 1.5 wt% Hydrofluoric acid. The morphology of oxide film on substrate was observed using scanning electron microscopy and transmission electron microscopy The surface roughness of titanium oxide film was analyzed by atomic force microscopy and the crystalline of specimen was investigated using X-ray diffractometer. The results of this study showed that well-aligned titanium oxide nanotubes are formed with diameter of approx. 100nm and length of approx. 500nm with CP Ti. However, it is clear that TiTaNb alloy highly irregular structure with various diameters. Transmission electron microscope investigations show that the specimens were confirmed as amorphous. Such titanium oxide nanotubes are expected a well-adhered bioacitive surface layer on titanium substrate for orthopedics and dental implants.
기계적 합금화 방법에 의한 금속-카본계에서의 나노복합금속분말의 제조
김현승,이광민,Kim, Hyun-Seung,Lee, Kwang-Min 한국재료학회 1998 한국재료학회지 Vol.8 No.4
본 연구에서는 기지금속과의 고상이나 액상의 고용한이 거의 없는 금속-카본(carbon)계에서 고에너지 볼밀공정을 이용하여 고체 윤활 청동베어링용 Cu-C-X계 나노복합금속분말을 제조하고자 하였다. Cu-10wt.%C-5wt.%AI과 Cu-10wt.%C-5wt.%Fe의 혼합분말을 이르곤 분위기의 attritor내에서 기계적 합금화한 후 Cu-C-X의 나노복합금속분말의 미세조직 특성을 조사하였다. AI, Fe를 첨가하였을 때 10시간 이상의 MA공정에서부터 약 $10\mu\textrm{m}$이하의 미세한 Cu-C-X나노복합금속분말을 얻을 수 있었으며, MA 시간에 따른 분말의 형상과 미세구조 변화는 금속-금속계의 MA 과정과 유사하게 진행되는 것을 알 수 있었다. Cu-C-X 나노복합금속분말의 X-선 회절시험 결과, MA 시간에 따라 Cu와 C분말의 회절피크의 폭은 넓어지고 회절강도는 감소하였으며, 특히 흑연피크의 MA시간에 따른 소멸은 흑연의 낮은 원자산란계수 때문에 의한 X-선 흡수 영향으로 고찰하였다. Williamson-Hall식으로 계산된 Cu-C-X 나노복합금속분말내의 Cu의 결정립은 15시간 이상의 MA공정에서부터 약 10nm이하의 크기를 가졌으며, TEM 분석결과로는 불규칙한 형상의 약 10-30nm 크기로 복합화된 Cu결정립을 확인할 수 있었다. In metal-carbon system with no mutual solubility between matrix and alloying elements as solid or liquid phases, Cu-C-X nanocomposite metal powders were prepared by high energy ball milling for solid-lubricating bronze bearings. Elemental powder mixtures of Cu-lOwt.%C- 5wt. %Fe and Cu- lOwt. %C- 5wt. %Al were mechanically alloyed with an attritor in an argon atmosphere, and then microstructural evolution of the Cu-C-X nanocomposite metal powders was examined. It has been found that after 10 hours of MA, the approximately 10$\mu\textrm{m}$ sized Cu-C- X nanocomposite metal powders can be produced in both compositions. Morphological characteristics and microstructural evolution of the Cu-C-X powders have shown a similar MA procedure compared to those of metal-metal system. As a result of X - ray diffraction analysis, diffraction peaks of Cu and C were broaden and peak intensities were decreased as a function of MA time. Especially, the gradual disappearance of C peaks in the X- ray spectra is proved to be due to the lower atomic scattering factor of C. The calculated Cu crystallite sizes in Cu- C- X nanocomposite metal powders by Williamson- Hall equation were about lOnm size, on the other hand, the observed ones by TEM were in the range of 10 to 30nm.
Guillain-Barre 증후군과 뇌경색 양상을 보인 신경정신 루푸스
김현승 ( Hyun Seung Kim ),이승찬 ( Seung Chan Lee ),홍현일 ( Hyun Il Hong ),한군희 ( Koon Hee Han ),이순금 ( Soon Keum Lee ),김성수 ( Sung Soo Kim ) 대한류마티스학회 2004 대한류마티스학회지 Vol.11 No.4
Systemic lupus erythematosus (SLE) is a disease of unknown etiology in which tissues and cells damaged by pathogenic autoantibodies and immune complexes. Nervous system involvement in patients with SLE encompasses a wide spectrum of neurologic and psychiatric features and the frequency of neuropsychiatric manifestations has been estimated at around 25% to 70%. American College of Rheumatology Ad Hoc Committee on neuropsychiatric lupus nomenclature developed case definitions for 19 different neuropsychiatric manifestations observed in SLE in 1999. Among them, Guillain-Barre syndrome and cerebral infarction are very rare neuropsychiatric manifestation. We experienced a 28-year-old woman with neuropsychiatric lupus which presented as Guillain-Barre syndrome and cerebral infarction. She was recovered after treatment with intravenous immunoglobulin, high dose methylprednisolone, cyclophosphamide and anticoagulants.
김현승(Hyun-Seung Kim),박춘식(Choon-Sik Park) 한국정보보호학회 2010 情報保護學會誌 Vol.20 No.2
클라우드 컴퓨팅의 다양한 구현은 서비스, 플랫폼, 인프라 각 서비스 영역에서 데이터 보호와 자원의 관리, 가용성 확보, 개인 정보보호 등 해결되어야 할 다양하고 복잡한 보안 문제를 포함하고 있다. 본 논문에서는 클라우드 컴퓨팅 보안의 다양한 요구사항 중에서 개인 인증에 대해서 검토해 보고자 한다. 특히, PC에서 스마트폰까지 확대되는 다중 플랫폼 및 다중 브라우저 환경에 최적화된 표준 웹기반 클라우드 플랫폼에서의 가장 큰 문제인 중간자 공격에 대응할 수 있는 개인 인증 방법의 보안성과 접근 용이성 및 상호운영성에 대해서 집중 검토하고자 한다.
김현승(Hyun-Seung Kim),박상섭(Sang-Sup Park),유창경(Chang-Kyung Ryoo) 한국항공우주학회 2015 韓國航空宇宙學會誌 Vol.43 No.8
본 논문에서는 기동하는 표적에 대한 입사각 제어 유도법칙을 제안하였다. 제안된 유도법칙은 정지표적에 대한 최적입사각제어 유도법칙을 변형한 것으로서 기존의 PN(Proportional Navigation) 유도법칙에 입사각제어 항이 추가된 바이어스 PN 유도법칙의 형태를 갖는다. 시선각, 비행경로각, 그리고 표적에 대한 상대 비행경로각 관점에서의 세 가지 다른 종류의 입사각을 정의하였다. 다양한 공대공 교전 시나리오에 대한 수치 시뮬레이션을 통해 제안한 유도법칙의 성능을 검증하였다. In this paper, a guidance law for intercepting maneuvering target with a desired impact angle is proposed. The proposed guidance law is modified from the optimal impact angle control law for a fixed target and given by a biased PN law with the impact angle control term in addition to the conventional PN law. Three different kinds of desired impact angles in the respect of LOS angle, flight path angle, and relative flight path angle to the target are defined. The performance of the proposed guidance law is investigated via numerical simulations for various air-to-air engagement scenarios.
김현승(Hyun Seung Kim),조준성(Jun Sung Jo),김현성(Hyeon Seong Kim),임효혁(Hyo Hyuc Im) 한국마린엔지니어링학회 2007 한국마린엔지니어링학회 학술대회 논문집 Vol.2007 No.-
From the research which it sees as the expression standard against the seabed terrain which the tsunami passes first after deciding the space grid size which is appropriate, it will reach and it used and the numerical model it established. And it used the numerical model established then it carried out the understanding of the characteristic for the past tsunami propagation which occurred from the East China Sea. After all there is the virtual tsunami against the earthquake which is possible and then the effect which is evaluated for the south coast of the Korean Peninsula.
김현승(Hyun Seung Kim),김현성(Hyeon Seong Kim),강영승(Young Seung Kang) 한국마린엔지니어링학회 2008 한국마린엔지니어링학회 학술대회 논문집 Vol.2008 No.-
Earthquake Tsunami should be occurred between Japan and Korea. There exist long distance fault gone in the sea. So that we can not ignoring tsunami dangerous activity, along the east sea shore line need investment preventing the worst effect roughly tsunami wave reduce the scale of the disaster. Tsunami was generated by the magnitude 90 earthquake which occurred near Indonesia. An energetic tsunami will display vertical water displacement of th order of ten meters and lateral scales of the order of tens of kilometers. The tsunami destroyed many coastal villages in Asia. So, there are many victims in southeastern part Asia by tsunami. Therefore, the construction of tsunami prediction and warning system is needed for minimize the damage by seismic sea waves.