• 한국화재소방학회논문지
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• 제16권4호
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• pp.77-84
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• 2002

본 연구는 플라스틱재료 중 비드발포폴리스티렌폼, 압출발포폴리스티렌폼, 연질폴리우레탄폼, 경질폴리우레탄폼, 경질PVC파이프, 비닐장판, 폴리에틸렌폰(비난연), 폴리에틸렌폼(난연)를 대상으로 연소가스 독성평가를 위하여 NES 713 방법에 따라 발생되는 연소가스를 가스텍(GASTEC) 가스검지관을 이용하여 조사하였다. 연구결과 플라스틱재료의 연소시 발생되는 연소가스에 인간이 30분 동안 노출될 경우 사망에 이르는 독성지수 1 이상을 갖고 있었으며, 각 실험체의 독성지수 결과는 4.3∼179.2로 나타났으며 경질 PVC파이프가 179.2로 가장 높았다.

• Nuclear Engineering and Technology
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• 제46권5호
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• pp.681-688
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• 2014

Hydride reorientation behaviors of PWR cladding tubes under typical interim dry storage conditions were investigated with the use of as-received 250 and 485ppm hydrogen-charged Zr-Nb alloy cladding tubes. In order to evaluate the effect of typical cool-down processes on the radial hydride precipitation, two terminal heat-up temperatures of 300 and $400^{\circ}C$, as well as two terminal cool-down temperatures of 200 and $300^{\circ}C$, were considered. In addition, two cooling rates of 2.5 and $8.0^{\circ}C/min$ during the cool-down processes were taken into account along with zero stress or a tensile hoop stress of 150MPa. It was found that the 250ppm hydrogen-charged specimen experiencing the higher terminal heat-up temperature and the lower terminal cool-down temperature generated the highest number of radial hydrides during the cool-down process under 150MPa hoop tensile stress, which may be explained by terminal solid hydrogen solubilities for precipitation, and dissolution and remaining circumferential hydrides at the terminal heat-up temperatures. In addition, the slower cool-down rate generates the larger number of radial hydrides due to a cooling rate-dependent, longer residence time at a relatively high temperature that can accelerate the radial hydride nucleation and growth.

• 한국전산구조공학회논문집
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• 제19권4호
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• pp.337-345
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• 2006

본 연구에서는 개발된 중공단면 복합소재 교량 바닥판에 대해 피로거동을 평가하기 위하여 거더 지지부에서의 압축피로 시험과 2.8m 길이의 휨시험체 모델에 대한 휨피로시험을 수행하였다. 피로하중은 도로교설계기준의 제시된 DB24 트럭 후륜 축하중에 대해 200만회까지 반복 재하하였으며, 압축피로시험의 경우에는 복합소재 바닥판 부재와 바닥판 튜브간의 연결부에 대한 피로성능을, 휨피로시험의 경우에는 복합소재 바닥판 및 주형연결부에 대한 피로성능을 분석하였다.

• Journal of Magnetics
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• 제21권1호
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• pp.57-60
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• 2016

Non Destructive Testing (NDT) methods that are capable of detecting the wall thinning and defects through insulation and cladding sheets are necessary. In this study we developed a Pulsed Eddy Current (PEC) system to detect wall thinning of ferro magnetic steel pipes covered with 95 mm thick fiber glass thermal insulator and shielded with aluminum plate of thickness 0.4 mm. In order to confirm the thickness change due to wall thinning, two different sensors, a hall sensor and a search coil sensor were used as a detecting element. In both the cases, the experimental data indicates a considerable change in the detected pulse corresponding to the change in sample thickness. The thickness of the tube was made to change such as 2.5 mm, 5 mm and 8 mm from the inner surface to simulate wall thinning. Fast Fourier Transform (FFT) was calculated using window approach and the results were summarized which shows a clear identification of thickness change in the test specimen by comparing the magnitude spectra.

• Steel and Composite Structures
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• 제20권6호
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• pp.1205-1219
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• 2016

This paper presents a new type of pre-pressed spring self-centering energy dissipation (PS-SCED) bracing system that combines friction mechanisms between the inner and outer tube members to provide the energy dissipation with the pre-pressed combination disc springs installed on both ends of the brace to provide the self-centering capability. The mechanics and the equations governing the design and hysteretic responses of the bracing system are outlined, and a series of validation tests of components comprising the self-centering mechanism of combination disc springs, the friction energy dissipation mechanism, and a large scale PS-SCED bracing specimen were conducted due to the low cyclic reversed loadings. Experimental results demonstrate that the proposed bracing system performs as predicted by the equations governing its mechanical behaviors, which exhibits a stable and repeatable flag-shaped hysteretic response with excellent self-centering capability and appreciable energy dissipation, and large ultimate bearing and deformation capacities. Results also show that almost no residual deformation occurs when the friction force is less than the initial pre-pressed force of disc springs.

• 한국기계가공학회지
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• 제13권6호
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• pp.23-29
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• 2014

In this study, cooling and heat-transfer tests are performed to compare and evaluate the thermal conductivity in a prepared CNT TIM (thermal interface material). A polymerized CNT heat-transfer resin and commercial thermal grease (Shinetsu G-747) were applied for a comparison test in both cases. Cooling experiments with an aluminum foil specimen were performed in order to measure the temperature distribution using an infrared camera, and in heat radiation experiments, performance testing of the thermal conductivity was conducted using high-power LEDs. Carbon resin with the polymerization of graphite and carbon black, and CNT-polymerized CNT resin with graphite and carbon black were tested and compared with using G-747. It was found that the cooling performance and the heat transfer ability in both the carbon resin and the CNT-polymerized CNT resin were greater than those of G-747 because the temperature by 5. $0^{\circ}C$ in both cases appeared lower than that of the G-747.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 B
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• pp.900-902
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• 2003

Critical current($I_c$) degradation of HTS tapes after bending is one of the holiest issues in HTS development and application studies. Many people are measuring $I_c$ degradations for effect of tending radius. However even if the bending radius is larger than the breaking radius a HTS tapes can be damaged by repetitive bending, which is unavoidable in the winding processes. Therefore, We studied the $I_c$ degradation after repetitive bending, at 77K with self-field, of Bi-2223 tapes processed by "Powder-in-Tube" technique, which was made by America Superconductor Corporation(AMSC), Innova Superconductor Technology(InnoST) and Korea Electro-technology Research Institute(KERI). For each specimen $I_c$ degradation was measured various bending radius as function of repetitive bending number.

• 한국전기전자재료학회논문지
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• 제13권3호
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• pp.254-258
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• 2000

Current leads of high $T_{c}$ superconductor were fabricated with Bi excess B $i_{2.2}$/S $r_{1.8}$/C $a_{1}$/C $u_{2}$/ $O_{x}$ composition by rapid cooling method. The dimensions of final samples were fixed 3 mm and 8 mm diameter with 50 mm length each To control uniform density the samples were preformed by CIP(Cold Isostatic Press) process and followed by partial or full melting process after raising up to 90$0^{\circ}C$ for 30min. Plate shaped microstructure was clearly observed adjacent to the Ag tube wall and the size of plate was about 100$\mu$m. However the severe destruction of growth orientation was shown in the inner growth part. critical temperature ( $T_{c}$) was about 53~71K after directional growth while Tc was decreased about 77~80 K before directional growth. After directional growth critical current( $I_{c}$) and critical current density( $J_{c}$) in the specimen of 8 mm diameter at 50 K were about 110 A and 280 A/c $m^2$ respectively.pectively.ely.

• Restorative Dentistry and Endodontics
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• 제4권1호
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• pp.35-38
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• 1978

The purpose of this study was to measure micro-knoop hardness and coefficient of thermal expansion on composite resins (Epolite, Adaptic, Hipol and Compo T.) Four different type of composite resins were measured at the varying depth of 30, 60, 90, 150, 200, 400, 700 and 1000 micron from the surface to deep portion. The specimens were stored both in the air room temperature for 2 days, 30 days and in water at $37^{\circ}C$ for 30 days. Thermal expansions of specimens(4mm in diameter and 50mm in height) were measured in quartz tube dilatometer from $20^{\circ}$ to $70^{\circ}C$ The following results were obtained. 1. The hardness of superficial portion were lower than inner portion of resin. 2. The value of hardness obtained from the specimen stored in room temperature in the water at $37^{\circ}C$ for 30 days were lower than above described Cases. 3. The coefficient of thermal expansion of Adaptic had $29.75{\times}10^{-6}/^{\circ}C$, Hipol had $30{\times}10^{-6}/^{\circ}C$, Epolite had $39.85{\times}10^{-6}/^{\circ}C$ and Compo T had $36.95{\times}10^{-6}/^{\circ}C$.

• Journal of Chest Surgery
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• 제3권2호
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• pp.127-132
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• 1970

A patient was 29 year old house wife who was admitted to the Yonsei University Medical Center on 6 th of Nov., in 1970, with chief complaints of complete loss of bilateral visual acuity, generalized weakness, frequent palpitations, claudication of masseter muscles and intermittent fainting. These symptoms were developed 5 years prior to admission. Physical finding on admission revealed complete loss of bilateral visual acuity, absence of both radial and carotid pulse, but there was good femoral and popliteal pulse. She couldn't open her mouth as she desired and had weakness of mastication. Radiological findings of plane chest PA were not significant. Aortogram(Cineangiogram) showed non-visualization of both carotid and subclavian arteries. It showed only innominate and interal mammary artery preoperatively. The operative findings were as follows: There were complete obliterative changes in both common carotid and subclavian arteries, and periarteritis in the innominate artery. Tube Dacron Prosthesis Bypass with V-arm between innominate artery and both common carotid arteries was performed after thromboendarterectomy. Histopathological finding of the thromboend arterectomy specimen was compatible with pulseless disease, which showed marked fibrous thickening of intima and a diffuse inflammatory cell infiltration of the whole layers. Her postopererative course was uneventful. Follow up aortogram(Cineangiogram) was taken on 11th postoperative day, which revealed both common carotid arteries patent. Her preoperative Subjective symtoms disappeared remarkably, such as her visual acuity improved much, fainting and vertigo disappeared completely and she can go to bath room without difficulty and help. Another patient was 34 year old house wife who was admitted on August, 1964 with chief complaints of frequent fainting and progresive visual loss. She was operated only thromboendarterectomy of both common carotid arteries. Postoperative course was smooth and subjective symptoms were disappeared.