• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.661-661
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• 2013

열전재료는 열-전기가 상호 가역적으로 변하는 재료로서, 에너지 변환소재 분야에서 널리 각광받고 있다. 열전재료의 성능은 무차원 열전성능지수(dimensionless figure of merit, $ZT={\alpha}^2{\sigma}T/{\kappa}$)로 평가된다. 여기서 ${\alpha}$는 제벡계수(Seebeck coefficient), ${\sigma}$는 전기전도도(electrical conductivity), ${\kappa}$는 열전도도(thermal conductivity), T는 Kelvin 온도를 나타낸다. 500 K에서 800 K까지의 중온 영역에서 우수한 열전특성을 보이는 $Mg_2X$ (X=Si, Ge, Sn)와 이들의 고용체는 성분원소가 독성이 없고, 매장량이 많아 친환경 열전재료로 각광받고 있다. $Mg_2X$ 고용체 중 $Mg_2Si-Mg_2Sn$ 고용체는 Si와 Sn의 큰 원자량 차이로 인해 낮은 열전도도와 높은 성능지수(ZT)를 얻을 것이라 예상되며 열전발전 소자로서의 응용이 기대된다. Sb가 도핑된 $Mg_{2+x}Si_{0.7}Sn_{0.3}Sb_y$ (x=0, 0.1, 0.2, y=0, 0.01) 고용체를 고상합성과 기계적 합금화로 합성한 후, 진공 열간압축 성형을 통해 성공적으로 제조하였다. X선 회절분석으로 상합성과 고용체 형성 여부를 확인하였고, Mg의 과잉첨가와 Sb 도핑에 따른 열전특성의 변화를 조사하였다.

• Journal of the Korean Applied Science and Technology
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• v.6 no.2
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• pp.67-74
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• 1989

The Kinetics of the Hydrolysis of benzalacetophenone derivatives has been investigated by ultraviolet spectrophotometry in 5% dioxane - $H_2O$ at $50^{\circ}C$. A rate equation which can be applied over wide pH range was obtained. The substituent effect on the hydrolysis of benzalacetophenone derivatives were facilitated by electron attracting groups. Based on the rate equation, substituent effect, general base effect, activation parameters and final product, the hydrolysis of benzalacetophenone derivatives seems to be initiated by the netural molecule of $H_2O$ which does not dissociate at below pH 9.0 but proceeded by the hydroxide ion at above pH 11.0. In the range of pH $9.0{\sim}11.0$ these two reactions occur competitively.

• Communications of the Korean Institute of Information Scientists and Engineers
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• v.24 no.5 s.204
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• pp.46-52
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• 2006

본 글에서는 최근 건설분야에 대한 적용이 적극적으로 모색되고 있는 그리드 기술에 대한 기존의 연구와 현재 국내에서 진행되고 있는 연구를 정리하고 소개하였다. 그리드 기술은 자원의 공유와 연계활용이라는 장점을 바탕으로 연구의 새로운 패러다임을 창출하는데 활용될 수 있다. 특히 건설현장에서 발생하는 복잡한 문제를 해결하기 위해 실험 및 해석을 병행하여 검증을 거쳐야 하는 경우가 많은 건설분야에서 시도되고 있는 하이브리드실험 및 분산실험 등의 연구는 그리드 기술이 제공하는 분산협업 환경을 활용함으로써 새로운 연구 형태로의 변화로 이어지고 있다. 그리고 국내건설업체에서도 마찬가지지만, 건설 및 계측현장이 전세계적으로 분산되고, 설계 및 시공의 전문가들 역시 분산되어 있는 상황이 빈번하게 발생할 경우, 전국 어느 곳에서나, 넓게는 세계 어느 곳에서나, 필요한 경우 협업이 가능하고 모든 필요 정보와 자원의 공유가 가능하도록 한다는 것은 지금까지의 독립적이고 제한적인 연구와는 차원이 다른 형태의 연구 환경을 제공하는 것이라 할 수 있다. 따라서 그리드 기술 및 그 활용기술의 개발은 이러한 새로운 형태의 연구를 보다 효과적이고 실효성 있게 진행하게 해줄 핵심기술로 기대된다. 이러한 상황에서 진행되고 있는 건설교통부의 '분산공유형 건설연구인프라 구축사업'은 건설/토목 분야 기술개발을 가속화시킬 수 있음은 물론 타 분야의 연구 활동에 변화를 촉진시킴으로써 우리나라 전체 과학 기술 발전에 크게 기여할 수 있는 사업이 될 것으로 기대된다.

• Proceedings of the KIEE Conference
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• 2006.07d
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• pp.2229-2230
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• 2006

자기누설탐상법은 비파괴검사 방법의 하나로 대상물체를 외부에서 착자시켜 결함이 발생할 경우에 결함부위에서 자기누설이 발생하도록 하여, 누설된 자기장을 측정하여 결함의 유무와 크기 등을 판정하는 시스템이다. 본 논문에서는 MFL 방식의 범용 NDT 검사기의 개발을 위해 영구자석을 이용하여 소형 비파괴 검사기를 설계하고, 3차원 유한요소법을 이용하여 해석하고 실제 데이터를 측정하여 그 결과를 비교 분석하였다.

• Journal of Trauma and Injury
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• v.28 no.4
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• pp.272-275
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• 2015

Pelvic bone fracture with unstable vital signs is a life-threatening condition demanding proper diagnosis and immediate treatment. Unlike long bones, the pelvic bone is a three dimensional structure with complex holes and grooves for vessels and nerves. Because of this complexity, a pelvic bone fracture can lead to complicated and serious bleeding. We report a case of a fifty-year-old male suffering from a pelvic bone fracture due to a fall. An imaging study showed fractures of both the superior and the inferior ramus of the pubic bone, with contrast extravasation underneath them, resulting in a large preperitoneal hematoma. He was sent for angiography, which revealed a hemorrhage from a branch of the left obturator artery. Embolization was done with a glue and lipiodol mixture. The patient recovered without complication, and was discharged at four weeks after admission.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.3 s.174
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• pp.550-559
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• 2000

One of the most important factor to be considered for the analysis of sheet metal forming processes is the tool surface description for arbitrarily- shaped sheet metal parts. In the present study , finite element approach is used to describe the arbitrarily shaped tool surface. In finite element mesh approach, tool surfaces ar, described by finite elements. The finite elements mesh description of the tool surface, which is originally described by CAD data, needs much time and time-consuming graphic operation. The method, however, has been widely used to describe a complex tool surface. In the present study, the contact searching algorithm for the finite element mesh approach is developed based on cell strategy method and sheet surface normal scheme. For the verification purpose, a clover cup drawing, Baden-Baden oilpan problem and a trunk floor drawing were investigated. The computational results based on the finite element approach were compared with the results of available parametric patch approach and experiments.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.755-760
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• 2007

The research will be essential that the method for strengthening safety are safe installations in a hardware portion, a safe running ceremony of the vehicle employee (an engine driver) and the estimate of the situation which is accurate. In railway car the window wiper which is auxiliary equipment for safe operation is changed the existing manual control method with automatic correspondence precipitation used raindrops censor which can assure the vision of driving. It can be easy to safe driving as might have expected the object. We carried out studies technical review investigation which can accomplish the best suited wiping speed in maintaining an introduction existing system in the manual control system applied the existing train and corresponding to precipitation. The observation fact in the studies can be possible to ensure safety operation. That is, Manual operation method (of the driver) to add the automatic speed adjust function can operate improved window wiper drive system when it rains and, as was expected, it is able to ensure the range of a good railroad driver's vision and to concentrate in working at rainfall.

• Journal of Advanced Marine Engineering and Technology
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• v.20 no.2
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• pp.75-75
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• 1996

The rapid expansion for the auto-industry and the worldwide trend toward non-asbestos friction materials for brake lining force our industry to transfer into non-asbestos ones from asbestos-based friction materials. Furthermore, it is imperative for the friction materials to have technological excellence and lower production cost to be competitive in the world market. There is no known theoretical procedures to formulate friction materials. It, rather, depends on the trial and error process. Thus, it is quite clear how important it is to accumulate the know-how on the formulation and manufacturing the friction material. This study concerns the practical ways of conceptualizing the formulation and optimizing the manufacturing process. This study focused on the development of formulation for non-asbestos friction material as well as deriving the physical properties of the trial product to prove its validity and applicability. Elaboration of the formula and optimizing scheme of the manufacturing process to get better quality are also sought. Physical properties were obtained by constant velocity test dynamotest, hardness test and strength test. Differential scanning calorimeter was also used to analyze the thermal reactions of organic constituents, microstructures, bond effects, and degree of mixture.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.27 no.5
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• pp.488-491
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• 2005

A 3-year-old female, 5kg, Shih-tzu developed an acute onset of depression, disorientation, hypersalivation, nystagmus after falling down 2 meter height place. In plain skull radiography, there was fracture line in the frontal and parietal bones and next day magnetic resonance imaging examination was performed. Magnetic resonance imaging of the brain was performed with 3.0 Tesla unit. Under general anesthesia, the dog was placed in prone with its head positioned in a birdcage coil. Transverse, sagittal and coronal fast spin echo images of the brain were obtained with the following pulse sequences: T1 weighted images (TR = 560 ms and TE = 18.6 ms) and T2 weighted images (TR = 3500 ms and TE = 80 ms). Magnetic resonance imaging showed epidural hematoma in the left frontal area resulting in compression of the adjacent brain parenchyma. Left lateral ventricle was compressed secondarily and the longitudinal fissure shifted to the right, representing mass effect. The lesion was iso-to slightly hyperintense on T1 weighted image and iso-slightly hypointense signal on T2 weighted image. At necropsy, there was a skull fracture and epidural hematoma in the left frontal area. Magnetic resonance imaging of epidural hematoma is reviewed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.4A
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• pp.336-343
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• 2007

Due to the ultrawide band property of an UWB pulse, it is difficult to digitally implement a TR-UWB system in time domain. In order to overcome this problem, we propose two types of TR-UWB systems which can be implemented in frequency-domain. One of thorn is derived from the Parseval's theorem, which results in its system performance equitable to that of time-domain based system. In addition, we propose another receiver structure which can improve the performance by exploiting the complex nature of the frequency components. Finally, through simulations, we compare the performances of two receiver structures with the time domain counterpart.