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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.
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.
김현승(Hyun Seung Kim),조준성(Jun Sung Jo),김현성(Hyeon Seong Kim),임효혁(Hyo Hyuc Im),박선기(Seon Ki Park) 한국마린엔지니어링학회 2007 한국마린엔지니어링학회 학술대회 논문집 Vol.2007 No.-
This study is an analysis of the inundation in Youngkwang by the damage instance of the inundation which occurs and the observed tidal elevation at tide gauge station in the west coast. Additionally there is an analyzing the inundation cause from the result of the numerical circulation model using the meteorological data.
4차 산업혁명시대 중국의 해양 지능화작전 추진과 대응 방안
김현승 ( Kim Hyun-seung ),신진 ( Jin Shin ) 국방대학교 안보문제연구소 2020 국방연구 Vol.63 No.2
한반도를 포함한 서태평양 해역에서는 해양에서부터 중국을 적극적으로 압박하려는 미국과 자국의 핵심해역에 미국의 진입을 거부하고 외해로 적극적 진출을 추구하는 중국 간의 경쟁이 날로 증대되고 있다. 이러한 경쟁에서 승리하기 위해 미국과 중국은 상대방을 압도할 수 있는 4차 산업혁명기술을 접목한 혁신적 전력을 확보하고 이를 효과적으로 운용할 있는 개념을 정립하기 위해 적극 노력 중이다. 특히 중국은 무인수상정, 무인잠수정 및 해양작전용 무인항공기의 개발 및 배치를 가속화하고 있으며, 인공지능의 군사적 활용 역시 적극 추진 중이다. 이렇게 중국은 4차 산업혁명기술을 접목한 해양 지능화작전을 펼쳐 미국의 해양압박전략에 대응함과 동시에 원해로의 진출을 가속화 할 것으로 예상된다. 이러한 중국의 해양 지능화작전 추진은 중국과 인접한 한국에 잠재적 위협이 될 가능성이 높다. 현재 중국은 서해에 다수의 함정을 상시 배치하고 있는데, 지능화작전을 추진하면서 무인수 상정, 무인잠수정 등도 배치할 가능성 높다. 이는 서해가 중국의 무인체계의 시험장이 될 수도 있다는 의미이다. 이러한 주변국 군사역량의 급속한 변화에 대응하여 한국 역시 전투용 무인체계의 실용화, 인공지능의 군사적 활용성 등을 적극 추진해야한다. 그래야만 미래 해양전장에서 주변국의 도발행위에 대응할 수 있는 역량을 갖출 수 있을 것이다. In the Western Pacific region, including off the coast of the Korean Peninsula, the competition between the United States, which is actively pressuring China from the sea, and China, has been increasing. In order to win this competition, the U.S. and China are actively working to procure innovative smart weapons combining fourth industrial revolution technologies and establish operational concepts to effectively operate them that can overwhelm their adversaries. In particular, the U.S. Navy's Distributed Maritime Operations and Chinese Navy’s Maritime Intelligent Operations are different in their procedures, but they are similar in the basic concept of using evolving fourth industrial revolution technologies to react more quickly than the adversaries and attack more rapidly. This means that China wants to achieve real-time battlefield awareness and speed up the decision cycle and the decision-making process to gain an upper hand in the maritime battlefield. The Korean Navy should also be able to cope with the rapidly changing maritime battlefields by making combat unmanned systems practical and improving the military utilization of artificial intelligence.
김현승(HYUN-SEUNG KIM),김현성(HYEON-SEONG KIM),강영승(YOUNG-SEUNG KANG) 한국해양공학회 2008 韓國海洋工學會誌 Vol.22 No.5
The numerical simulation of tsunami against the South Coapt of the Korean Peninsula has been performed by adopting the standard propriate grid Size the numerical model has been constructed to include the characteristics of the tsunami propagation applied for the care of the East china Sea The artificial tsunami has been modelled first and then, it has been used ars the boundary condition for the detailed model which Showed tho south coapt of the Korean Peninsula.
담낭관의 해부학적 특성과 십이지장 팽대부주위 게실유무의 담석형성과의 관계
김현승(Hyun Seung Kim),박창영(Chang Young Park) 대한내과학회 2000 대한내과학회지 Vol.58 No.6
N/A Background : There are many factors that may affect the lithogenesis. These factors are age, sex, nutrition, diet, hormones, drugs, heredity, infection, etc. Moreover, it is known that morphology, implantaion site, diameter, length of cystic duct may also play an important role in the lithogenesis. It is also known that juxtapapillary duodenal diverticulum is associated with lithogenesis. This study investigated correlation between lithogenesis and anatomical characteristics of cystic duct and juxtapapillary duodenal diverticulum. Methods : Between January 1996, and April 1999, 461 endoscopic retrograde cholangiopancreatography were performed. Patients excluded from the study were those with previous cholecystectomy, carcinoma of the pancreas or biliary tract, benign stenosis of the sphincter of Oddi, lack of visualization of the entire cystic duct, and biliary endoprostheses. Finally, 90 patients were included in the study. The length and diameter of cystic duct was measured by means of string. The patients were divided into three groups.(Group I, absence of lithiasis in the biliary tract and gallbladder ; Group II, presence of lithiasis in the gallbladder but not in the CBD; Group III, lithiasis in the CBD with or without gallbladder lithiasis.) Results : Lithiasis is associated significantly with sex, age, triglyceride level, site of implantation, length of cystic duct, morphology, existence of juxtapapillary duodenal diverticulum. The patients with gallstones or CBD stones(Group II, III) has significantly longer cystic duct than others(Group I) in the length(p≤0.001). Furthermore, the patient with left marginal insertion of cystic duct on the CBD is associated with a length greater than 3cm(p=0.002) and spiral morphology(p<0.001). Conclusion : Age, sex, level of triglyceride, implantation site, morphology, length of the cystic duct and juxtapapillary duodenal diverticulum is associated with lithiasis. It seems that left marginal insertion of cystic duct can play an important role in lithogenesis by increasing cystic duct resistance