• 한국공작기계학회논문집
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• 제10권4호
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• pp.7-13
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• 2001

This Study is to investigate the influence of weld residual stresses on the fatigue crack growth behaviors in pressure ves-sel reinforcement. In order to perform this study, the automatically welded specimens are prepared. The material is ASTM A516 grade 60 steel used in pressure vessel mainly. For pad-on-plate of skip welding continuous welding and PWHT specimen, fatigue crack initiation is generally initiat-ed at weld starting and end toe zone, and ruptured at weld starting toe zone, Fatigue life if pad-on-plate continuous speci-men is increased more than that of pad-on-plate skip fillet welding specimene about 85% under low load, about 20% under high load, and decreased than that of two-pad continuous welding specimen about 85%. In da/dN-$\Delta$ Κ curve under low load, pad-on-plate skip fillet welding specimen showed retardation on the initial crack, and the fatigue crack growth rate at the low region of $\Delta$Κ greater specimene E(3.8{\times}10^{-6}$mm/cycle). And the fatigue life of welding specimen was smaller than that of PWHT specimen.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2003년도 Proceedings of the international symposium on the fusion technology
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• pp.455-458
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• 2003

A combination of drilling, hydrogeochemical survey, geophysical survey and the numerical modelling for the flow and transport of groundwater was performed to evaluate the seawater intrusion in Baeksu-eup, Yeonggwang-gun, Korea. The survey area extends to over 24 $km^2$. Twelve wells were also drilled for the collection of geologic, geochemical, hydrologic, and geophysical logging data to delineate the degree and vertical extent of seawater intrusion. To evaluate and map the salinity in a coastal aquifer, geophysical data and hydrogeochemical results were used. Layer parameters derived from VES data, various in situ physical properties from geophysical well loggings, and the estimated equivalent NaCl concentration were used as the useful input parameters for the numerical simulation with density-dependent flow. Our multidisciplinary approach for evaluating the seawater intrusion can be considered as a valuable attempt to enhancing the utilization of various data and the reliability of numerical ground modelling.

• 한국공간구조학회논문집
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• 제15권2호
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• pp.61-68
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• 2015

The performance enhancement of various structural building systems from natural hazards has become an inctreasingly important issue in engineering field. In this paper, visco-elastic(VE) CST30 damping systems were tested under cyclic loadings to evaluate their performance in terms of ductility and energy dissipation. Main test variables are relative shear stiffness, rate of loading frequency, and thickness of specimens to evaluate the seismic capacity based on the performance criteria. This experiment was performed using a total of 12 specimens, subjected to cyclic loadings up to a shear deformation of 500%. All the CST30 dampers provided a ductile and stable hysterestic behavior when subjected to the demands of large shear stiffness and different loading frequencies. The test results showed that the CST30 dampers are an effective damping systems to enhance the buildings performance for remodeling and retrofit of buildings.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 B
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• pp.1123-1125
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• 2005

본 논문에서는 3차원 공간에 종이와 같은 박막형 유전체가 있을 때 임의의 점에서의 전계$\vec{E}$를 구하기 위해 유전체의 분극벡터$\vec{P}$를 미지수로 하는 경계적분법(Boundary integral method)을 사용한다. 경계적분법의 사용으로 FEM 3차원 해석에 있어서의 요소분할의 난이성 및 계수 행렬의 대형화로 인한 컴퓨터 수행능력의 한계를 극복할 수 있다. 여기서 분극벡터$\vec{P}$를 구하기 위해 전하에서의 전계${ves{E}}_s$에 의한 유전체내의 분극벡터$\vec{P}$를 수식으로 정리하여 $[\vec{K}][\vec{P}]=[\vec{E}]$ 형태의 $\vec{P}$를 미지수로 하는 system matrix를 구성한다. 위의 system matrix 통해 구해진 분극벡터 $\vec{P}$를 이용하여 유전체 밖의 한 점에서의 전계세기 ${\vec{E}}_m$를 구한 후 우리가 구하고자 하는 전계$\vec{E}$를 계산한다.

• Journal of Animal Science and Technology
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• 제59권3호
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• pp.5.1-5.10
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• 2017

Background: Bovine respiratory disease (BRD) is one of the leading causes of economic losses in the beef and dairy industry. Reliable antemortem tools for diagnosing BRD would improve the efficacy of treatment and reduce costs. Here we examined whether the relatively simple technique of thoracoscopy can support BRD diagnosis under field conditions. We also compared various equipment set-ups in order to optimize the safety and efficacy of the procedure. A total of 24 thoracoscopic procedures were performed in 17 calves diagnosed with BRD and in 2 healthy control calves. Rigid and flexible endoscopes and industrial videoscopes were tested using various insertion approaches. The suitability of the technique was assessed in terms of duration, volume of air extracted, visualization score, and image quality. Safety was assessed in terms of rectal temperature, body weight, breaths/min, presence of fibrinogen, pain score, recovery time, intraoperative complications and risk of laceration or threatening collapse. Results: Insertion of a flexible endoscope via a right, dorso-caudal approach at the $5^{th}$ intercostal space allowed complete examination of the right lung in 15 min, as well as identification of main lung lesions and adherences in calves with BRD, without compromising calf welfare. While the dorso-caudal approach was optimal, it was associated with substantial discomfort when rigid endoscopes were used, minimal complications or mortality due to thoracoscopy were observed up to 28 days after the procedure. Videoscopes were as safe and easy to use as endoscopes, but endoscopes provided better image quality. Conclusion: This study provides the first field evidence that thoracoscopy can be safe to explore BRD-diseased calves. These results justify a larger study to rigorously assess the diagnostic performance of the technique.

• 한국도로학회논문집
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• 제7권1호
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• pp.73-82
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• 2005

공극구조 분석 방법은 ASTM C 457의 리니어트레버스 포인트카운트법이 있으나, 이러한 방법들은 분석하는데 시간과 노력이 너무 많이 소요되어 현재에는 거의 사용되어지지 않고 있다. 근래에는 현미경과 디지털 카메라, 컴퓨터의 프로그램 발달로 화상분석법이 많은 연구자에 의해 연구되고 있다. 본 연구에서는 화상분석법을 통하여 라텍스개질 콘크리트의 공극 구조 특성을 분석하고자 시멘트 종류(보통포틀랜드시멘트, 초속경시멘트)와 라텍스 혼입율(0,15%)에 따라 실험을 수행하였다. 실험결과, 라텍스는 경화 후 콘크리트에서 AE제의 공기연행효과보다 더 우수한 연행공기 량을 갖는 것으로 나타났다. 또한, 화상분석법을 이용할 경우 경화 후 콘크리트 내부 공극 구조에 대한 다양한 정보를 분석할 수 있을 것으로 판단되었다.

• 펄프종이기술
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• 제43권5호
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• pp.17-26
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• 2011

Drying behavior and physical properties of HwBKP, SwBKP, and OCC handsheets depending on kneading, refining and wet pressing were analyzed. The maximum drying shrinkage velocity was newly adopted to verify the effect of mechanical treatment of pulps by evaluating drying behavior according to varying the kneading, refining and wet pressing treatments. Those various treatments were changed to evaluate the relationship between the maximum drying shrinkage velocity and handsheets properties. When the drying shrinkage and the maximum drying velocity increased by refining and wet-pressing, handsheets strength was increased. The maximum drying shrinkage velocity showed higher correlation with physical properties of paper than WRV at different refining loads at SwBKP and mixed pulp. At high wet-web dryness, drying shrinkage, the maximum drying shrinkage velocity and strength properties of handsheet were increased. It meant that drying shrinkage behavior was highly affected by not only fibers' shrinkage but also fiber bonding. Kneading pre-treatment for KOCC and SwBKP effectively modified fiber properties and increasing paper strength and drying shrinkage. The effect of kneading pre-treatment was also confirmed by the maximum drying shrinkage velocity. Strength properties of mixed pulp handsheets were not increased by the kneading pre-treatment, although the maximum drying shrinkage velocity and WRV was increased. It meant that fibers network bonding of HwBKP was limited because of ves sels and ray cells' interference for bonding. Therefore in order to improve paper strengths containing HwBKP by mechanical treatments, interference of vessels and ray cells for fiber bondings should be carefully controlled.

• 한국동물학회지
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• 제37권4호
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• pp.478-487
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• 1994

The developmental changes of three enteroendocrine cells, i.e. gastrln, somatostatin and serotonin, of gastric and small intestinal mucosa in pre- and postnatal rat were examined by peroxidase-antiperoxidase (PAP) method. In the course of development, gastrin cells were obsenred in the pyloric gland region and the whole part of small intestine, while somstostatin and serotonin cells in the whole gastric gland region and small intestine. More entroendocrine cells were detected in the pyloric gland region and duodenum than in the other portion. In the stomach, gastrin, somatostatin and serotonin ceils were first obsenred in the pyloric Bland region on 17, 19 and 19 days of gestation respectively. The small intestinal gastrin and serotonin cells were first appeared in the duodenum and iriunum on 17 and 15 days of gestation respectively, and somatostBtin cells in duodenum on 17 days of gestation. The number of cells examined from the stomach were increased from fetal to weanling period and showed a decrease during adult period: the notable increase was shown at the end of suckling period or at early weanling period. The cells of the small intestine increased from fetal to suckling period, especially, these cells markedly increased at the end of fetal period or at early suckling period, and decreased from weanling period. The shape of these cells was oval or fusiform during fetal period. In the stomach, most of gastrin cells turned out to be oval and open-type from suckling period, while the remaining two tripes of cells were oval and open- or closed-type. In the small intestine, 311%Ves of cells examined were changed to fusiform and open-type from the end of fetal period. Three types of cell were distributed over the stratified epithelium on 15 and 17 days of gestation. In the stomach, these cells were distributed lower gastric pit and gland from the following fetal period, and were detected mainly on the upper part of gland from suckling period, and then obsenred on the whole part of gland. In the small intestine, most of cells distributed over only between epithelium of villi on 19 days of gestation, increased in number on the crypt from following fetal period, and also observed abundantly in the crypt at adult period.

• 한국정보과학회논문지:소프트웨어및응용
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• 제32권1호
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• pp.34-40
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• 2005

엔지니어링 정보와 같은 3차원 정보의 시각화에는 CAD, 2D 컴퓨터그래픽, 3D 컴퓨터그래픽, 가상현실(VE)을 이용한 3차원적 표현 등 다양한 정보표현방식이 이용될 수 있으나, 이들 방식의 효과에 대한 비교연구는 매우 부족하다. 본 연구의 목적은 CAD, 2D 컴퓨터그래픽, 3D 컴퓨터그래픽, 가상현실의 한 형태인 증강현실 방식(AR)의 정보표현 방식에 대한 사용자의 호의도 및 심리적, 신체적 업무부하의 차이를 비교하는 것이다. 실험결과 사용자들은 정보제공방식 간에 업무부하의 차이는 없다고 보고하였으나, 2D 정보표현보다 3D 정보표현을 선호하였다 우리가 물체를 인식하는 방식과 동일한 방식으로 정보를 제공하는 AR방식은 인식정보의 병렬처리를 통하여 엔지니어링 정보제공에 유용한 수단으로 사용될 수 있음을 보여 주었다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제7권3호
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• pp.3-17
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• 2002

본 연구는 부산시 동남해안 지역에서 해수침입의 지역적 특성과 해수침입의 범위를 파악하기 위하여 지하수 모니터링공의 자료분석과 지구통계학적 기법을 이용하였다. 강수에 의한 직접적인 지하수의 충진으로 모니터링 우물에서의 지하수위는 강수량과 비례하지만 전기전도도는 강수량과 대체로 반비례하는 것으로 나타났다. 모니터링 우물에서 전기전도도는 약 24m심도에서 급격히 증가되어 26m전후에서 20,000$\mu\textrm{s}$/cm를 초과하였고, 지하수위와 전기전도도를 비교한 결과, 지하수위가 낮아질수록 해수와 담수의 경계면이 상승하는 경향을 보인다. 교차상관성 분석에 의하면 지하수위와 강수량은 시차가 0일 때 교차상관 계수가 최대이지만, 전기전도도와 강수량의 교차상관계수는 시차가 9일 때 최대로 나타났다. 이것은 지하수위 변동이 강수에 의하여 단시간에 영향을 받고 있으나, 해수와 담수의 경계면은 강수에 의하여 매우 느리게 반응한다는 것을 나타낸다. 2개의 측선에서 실시된 수평전기탐사 자료의 역산결과, Line 1에서는 동쪽 끝에서 내륙으로 약 14m지점까지, Line 2에서는 동남쪽 끝에서 내륙으로 약 25m지점까지 해수가 침투한 것으로 나타났다 5월과 7월에 슬럼버져 배열의 수직전기탐사를 실시하여 획득한 자료는 각각 대수정규분포를 나타내었고, 크리깅에 의한 겉보기비저항 분포도와 전기비저항 분포도를 비교하면 5월보다 7월에 비저항치가 상승한 것으로 나타났다. 이것은 6, 7월에 내린 강수로 지하수의 함양량이 증가하여 대수층내 해수의 농도가 감소하였기 때문이다 겉보기비저항의 수직단면도 및 평면도 그리고 전기비저항 분포도를 분석한 결과. 지구통계학적 기법은 해안 지역에서의 전기비저항 분포 변화를 파악하는데 매우 유용하였다.