• 한국자동차공학회논문집
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• 제15권1호
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• pp.171-176
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• 2007

An important challenging issue in the automotive industry is the light-weight, safe design and enhancement of crash response of an auto-body structures. These objectives lead to increasing adoption of high strength steel sheet for inner and outer auto-body members. This paper evaluates the dynamic tensile characteristics of high strength steel sheets, HS45R, TRIP60, DP60 and DP100, along the rolling direction and transverse direction. Static tensile tests were carried out at the strain rate of 0.003/sec using the static tensile machine (Instron 5583). Dynamic tensile tests were carried out at the range of strain rate from 0.1/sec to 200/sec using a high speed material testing machine developed. The tensile tests acquire stress-strain relation and strain rate sensitivity of each material. The experimental results show two important aspects for high strength steels: the flow stress increases as strain rate increases; the strain hardening decreases as the tensile stress increases. The experiments also produce interesting results that the elongation does not decrease even when the strain rate increases.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 Techno-Fair 및 추계학술대회 논문집 전기물성,응용부문
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• pp.165-166
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• 2007

In these days $SF_6$ mixtures and alternative gas have been studied because of global warming and liquefying at low temperature and high pressure. At present work the breakdown characteristics of $SF_6/CF_4$ mixture in non-uniform field was performed. The experiments were carried out under positive and negative standard lightning impulse (SLT) voltages. The point-plane electrode was used with 3 mm gap distance in the test chamber. The $SF_6/CF_4$ mixture which contain 20% of $SF_6$ was compared with pure $SF_6$ and $CF_4$ gas. Experimental gas pressure ranged from 0.1 to 0.4 MPa. The breakdown voltage under negative SLI is higher than the breakdown voltage under positive voltage. And the breakdown voltage of $SF_6$ 20%, $CF_4$ 80% mixture is similar to that of pure $SF_6$.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2014년도 추계학술발표대회
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• pp.126-127
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• 2014

현재 방송에서는 제공되지 않은 해상도, 촬영 시점 등에 대한 사용자 요구에 따라 방송 서비스를 선택적으로 제공받고자 하는 요구가 생겨나고 있다. 기존 서비스들은 촬영 시점에 따라 정지 영상을 보여주는 정도의 연구가 진행되어 왔다. 본 논문에서는 그 한계점을 극복하고자 가상실세계에서 스트리밍을 제공할 수 있는 방법에 대해 연구하였으며, 실시간 멀티뷰 중계 서비스를 구현하고자 한다. 이를 통해 시청자는 다양한 각도에서 자신이 원하는 화면을 선택적으로 서비스 받을 수 있으며, 미래형 서비스를 위한 원천기술 확보에 도움이 될 것이다. 특히 스포츠 분야에 적용할 때 사용자가 즐길 수 있는 콘텐츠의 질적 향상을 가져올 것으로 기대된다.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2002년도 춘계학술발표논문집 (하)
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• pp.1349-1352
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• 2002

Handset 을 통한 m-Commerce 시장의 확장과 더불어 커머스를 기반으로 한 물류서비스, 무선 인트라넷, 모바일 증권거래 등에 PDA(Personal Digital Assistant)를 정보단말로 이용하는 서비스가 늘어나면서 PDA 무선 보안솔루션 개발에 관련된 관심이 잇따르고 있다. 특히 PDA 무선 보안솔루션은 무선 PKI를 비롯해 암호화 솔루션, 백신, 파이어월 등 다양한 분야에서 독특한 기술이 개발되고 있으며 보안분야의 새로운 시장을 형성할 것으로 기대된다. PDA 무선 보안 솔루션은 증권, 뱅킹 등에서 시도되어지고 있는 Application layer 에서 암호/복호화 하는 방식, 유선과 동일하게 브라우저/ 웹서버에서 제공하는 SSL 암호화 방식, SSL v3 및 TLS v1 과 호환되는 자체 암호화 모듈 방식등의 3 가지로 크게 나누어 볼 수 있다. 본 논문에서는 WinCE OS 의 iPaq PDA 에 SSL v3 및 TLS v1 과 호환되는 자체 암호화 모듈 방식의 시스템을 설계한다. PDA 와 서버 간의 인증, 메시지 기밀성 및 무결성을 충족시킬 수 있는 보안 서비스를 제공하고 유선과 동일한 수준의 보안 수준을 유지하면서도 지금까지 무선 암호인증의 문제점이었던 소용량 무선단말기의 한계를 극복하는 PDA 용 무선 보안 솔루션을 설계하는데 목적을 두고 있다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
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• pp.227-228
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• 2007

Although many studies have been carried out about binary gas mixtures with $SF_6$, few studies were presented about breakdown characteristics of $SF_6/CF_4$ mixtures. At present study the breakdown characteristics of SFJCF4 mixtures in uniform field was performed. The experiments were carried out under AC and standard lightning impulse (SLI) voltages. The sphere-sphere electrode whose gap distance was 1 mm was used in a test chamber. $SF_6/CF_4$ mixtures contained from 0 to 100% $SF_6$ and the experimental gas pressure ranged from 0.1 to 0.4 MPa. The results show that addition of $SF_6$ to $CF_4$ increase AC and SLI breakdown voltages. Under AC voltages the breakdown voltages of each mixture were linearly increased according to the quantity of $SF_6$. However under SLI voltages the breakdown voltages of each mixture were similar.

• 한국건축시공학회지
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• 제9권3호
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• pp.117-125
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• 2009

With construction industry recession, many construction companies are increasingly conducting the development projects by themselves. However, housing projects requested by developers still stand large portion. Although many studies on feasibility analysis were released, they mainly focused on economic feasibility and lacked research on factors and criterions of overall project. Also, because previous studies overly break downed factors related to project, they rarely used in practice. Therefore, this study developed the feasibility analysis model of housing development projects to help main contractors to easily and effectively decide if it is feasible enough to promote the projects requested by developers, and verified the reliability of the model. In this study, thirty one driving factors were identified under seven different categories and the criterion of each factor was also developed. The survey on important index of each factor found 'salability', 'economic feasibility', 'site location' and 'method of raising fund' significant. 12 projects were tested by the model and its results showed resonable reliability.

• 대한방사선기술학회지:방사선기술과학
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• 제11권2호
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• pp.21-26
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• 1988

Newly developed orthochromatic film HR series have many different types according to high speed, high resolution and special latitude. And now authors have practiced various screen-film combinations, those were usual regular type Fuji new RX film-LT screen and orthochromatic type HR films-rare earth G3, G4 screens. As a result of the experiment, we obtained high speed with high resolution and expansion of diagnostic range on the following combinations compared with usual new RX/LT series. Those combinations were RXO-G and HR-L films to skull, HR-G films to knee joint and hand part, HR-L film to abdomen. Therefore it may be desirable to select adquate kinds of HR series films according to investigated parts.

• 대한방사선기술학회지:방사선기술과학
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• 제3권1호
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• pp.81-86
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• 1980

To compare three-phase 12-pulse full-wave X-ray generators with single-phase full-wave X-ray generators on their performance of outputs, authors studied the generating X-ray by means of exposure dose and radiographic density. The results were as follows; 1. The exposure doses of three-phase full-wave X-ray generators showed a 30%-60% increase as compared against of single-phase full-wave generators. 2. The transmitted doses of three-phase full-wave generators were more increased than single-phase full-wave X-ray generators. 3. To obtain the same density, 60kVp in three-phase full-wave generators were equivalent to $60{\sim}65kVp$ in single-phase full-wave generators, and 100kVp in those generators were equivalent to $100{\sim}125kVp$ in these generators.

• 대한방사선기술학회지:방사선기술과학
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• 제3권1호
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• pp.37-41
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• 1980

In an attempt to provide optimum kVp for four spot films of stomach examinations, we measured experimentally film density and scatter radiation with field size. And to investigate the effect of concentrations in barium sulphite and kVp in spot films of stomach fluoroscopy were carried out and the following results were obained. 1. The entire density of film by field size has the sharpest increase from $10cm^2$ to $100cm^2$, and relatively flattened curve beyond $500cm^2$ in field size. 2. The quantity of scatter radiation reaching an X-ray film depends upon field size: the larger the fields, the more scatter radiation. 3. It is necessary for increasing 3 to 5kVp as for the absence of barium sulphite and 5 to 7 kVp in the case of 20 per cent and 25 per cent in barium sulphite concentrations to produce uniform density in the four spot films for stomach fluoroscopy.

• 한국자기공명학회논문지
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• 제1권1호
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• pp.7-20
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• 1997

The mapping of the spin-spin relaxation time T2 in pixed-by-pixel was suggested as a quantitative diagnostic tool in medicine. Although the CPMG pulse sequence has been known to be the best pulse sequence for T2 measurement in physics NMR, the supplied pulse sequence by the manufacture of MRI system was able to obtain the maximum of 4 CPMG images. Eight or more images with different echo time TEs are required to construct a reliable T2 map, so that two or more acquisitions were required, which easily took more than 10 minutes. 4-echo CPMG imaging pulse sequence was modified to generate the maximum of 8 MR images with evenly spaced echo time TEs. In human MR imaging, since patients tend to move at least several pixels between the different acquisitions, 8-echo CPMG imaging sequence reduces the acquisition time and may remove any misregistration of each pixel's signal for the fitting T2. The resultant T2 maps using the theoretically simulated images and using the MR images of the human brain suggested that 8 echo CPMG sequence with short echo spacing such as 17∼20 msec can give the reliable T2 map.