Investigation of Application for ELCIRC (Eulerian-Lagrangian CIRCulation) Model

김현승(Hyun-Seung Kim),강영승(Yung-Seung Kang),김국진(Kuk-Jin Kim3) 대한조선학회 2011 대한조선학회 학술대회자료집 Vol.2011 No.6

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.

항만구조물 설계를 위한 실무형 BM라이브러리 개발 연구

김현승(Kim, Hyeon Seung),이헌민(Lee, Hyun Min),김남일(Kim, Nam Il),이선우(Lee, Sun Woo),이일수(Lee, Il Soo) 대한토목학회 2019 대한토목학회 학술대회 Vol.2019 No.10

폐질환에서 201 Thallium 의 섭취양상

김현승(Hyun Seung Kim),권혁문(Hyuck Moon Kwon),장양수(Yang Soo Jang),임상욱(Sang Uk Lim),남문석(Moon Suk Nam) 대한내과학회 1991 대한내과학회지 Vol.41 No.3

N/A 201 Thallium chloride has been described by Cox, Salvatore, Tonami as a positive indicator for lung neoplasm 201 Thallium scintiscan was performed in 10 patients with lung cancer and in 21 patients with benign lung diseases. Early scan demonstrated abnormal accumulation in 9 of 10 lung cancer and in 8 of,.,1 benign conditions(P=0.0066) and revealed strong positive uptake in all of 4 adenocarcinoma. Eight of twenty one benign conditions (4 in 8 active or cavitary pulmonary tuberculosis, 1 in 5 inactive pulmonary tuberculosis and 3 in 8 pneumonia or lung abscess) showed abnormal accumulation of 201Tl. And the fading apperance of radioactivity on some delayed scans was noted in benign conditions compared with persistent high radioactivity in lung cancer. 201Thallium scintiscan is useful in the differentiation of a pulmonary lesion whether is benign or malignant.

클라우드 컴퓨팅과 개인 인증 서비스

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.

한반도 남해안에 대한 지진해일 수치실험

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.

과학의 창의성에 대한 철학적 접근 -창의성 연구와 과학적 발견의 관계를 중심으로-

김현승 ( Hyun Seung Kim ) 한국과학철학회 2010 과학철학 Vol.13 No.2

Creativity has been regarded as one of the main research topics in the field of psychology, in a direct relation with human cognitive thoughts or abilities. Besides, the creativity research has been one of the main research sections in psychology. Creativity of science is no exception as well. However, scienceis conducted through particular activities called ``scientific discovery`` differentiated from other studies. If a scientific discovery could be a topic of the creativity research, science would be able to obtain a position of creativity unlike other studies. This paper will examine three courses, such as ``The Process of Forming the Creativity Research Focusing on Psychology``, ``Approaches and Limits of the Creativity Research on Science`` and ``The Category of Scientific Discoveries and Discussions on Creativity of Science``. Thus, the writer is attempting to provide a basic foundation for the fact that creativity of science acquires an important meaning from the analysis of a scientific discovery.

LDPC Codes에서 PEG 알고리듬과 IPEG 알고리듬의 성능 비교 평가 및 분석

김현승(Hyun-Seung Kim),고재현(Jae-Hyun Ko),장민(Min Jang),김상효(Sang-Hyo Kim) 한국방송·미디어공학회 2009 한국방송공학회 학술발표대회 논문집 Vol.2009 No.11

1962년 R.G Gallager가 제안한 LDPC(Low Density Parity Check)부호는 Shannon의 채널 용량의 한계에 근접한 우수한 오류정정 부호이다. 우수한 LDPC부호 생성 조건 중 가장 중요한 부분은 바로 최소 사이클 길이(girth) 를 최대화 하는 과정인데, PEG(Progressive Edge Growth)알고리듬은 이 조건을 만족시키는 우수한 알고리듬으로 인정받고 있다. 이후 높은 SNR범위에서 PEG알고리듬의 성능을 개선한 IPEG (Improved PEG) 알고리듬을 포함한 다양한 알고리듬이 제안 되었다.본 논문은 PEG와 IPEG 알고리듬을 이용해 생성한 LDPC 부호를 이용하여 부호길이, 부호율을 변화시키면서 실험하여 그 결과를 비교 분석하였고, 더 좋은 성능을 가질 수 있는 알고리듬에 대해 논의한다.

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