• 설비공학논문집
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• 제16권4호
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• pp.318-323
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• 2004

When a strong electric field is applied between a sharply curved electrode and a blunt surface, the corona may result in a gas movement in the electrode gap which is directed toward the blunt surface. That is called the corona wind. It enhances heat and mass transfer between the surface and the surrounding gas. Moreover such enhancement causes no noise or vibration, which can be applied in complex, isolated geometries, and allows simple control of surface temperatures. This paper examines the relationship between the corona wind and the relative humidity. The facility consists of high voltage power supply thin tungsten wire, plate electrode, multimeter, microammeter and flow meter. Gas velocity is a linear function of voltage, relative humidity and is proportional to the square root of the current. The maximum velocities for the positive and negative corona discharge are 1.9 m/s (2.74 CMM/m), 1.5 m/s(2.15 CMM/m), respectively.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2009년 추계학술발표대회
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• pp.22-22
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• 2009

Laser forming is a promising technology in manufacturing, such as in the shipbuilding, automobile, microelectronics, aerospace and other manufacturing industries. This process forms the sheet metal by utilization of laser-induced thermal stresses. Laser forming process has been studied extensively for rectangular shape geometry. This basic study presents the change in deformation behavior of sheet metal during transition from linear to curved geometries and irradiations as well. A series of experiments have been conducted on a wide range of specimen geometries such as quarter-circular and half circular plate. The reasons for this behavior have been analyzed. Results are compared and analyzed by simulations using ABAQUS. Influence of developed stresses on the bending has been investigated. This study provides the more understanding of forming mechanism influenced by geometry effect.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2009년도 춘계학술대회 논문집
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• pp.215-219
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• 2009

For the effective manufacture of doubly curved metal plates, a line array roll set (LARS) process is proposed. The suggested process utilizes a pair of upper and lower symmetric roll assemblies. In the process, the initial plate is progressed into the final shape in a stepwise or pathwise manner according to the basic principle of the incremental forming process. In this work, the intermediate shape which is closest to a final shape is proposed to fabricate the desired shape effectively in design of forming schedule. The intermediate shape has homogeneous curvature in a longitudinal and transverse direction so that it can be fabricated easily without complicated controls of rolls in the roll set. The method of approximation using genetic algorithm is proposed and applied to some actual ship hulls to evaluate the efficiency of the algorithm.

• 대한토목학회논문집
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• 제11권2호
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• pp.1-14
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• 1991

평면내에서의 비틀림에 대한 강성도를 갖는 3절점 삼각형 shell요소를 사용하여 박판으로 이루어진 곡석 또는 직선부재의 선형 탄성좌굴 해석을 위한 컴퓨터 프로그램을 개발 하였다. 판의 좌굴 해석과 보의 횡 비틈 좌굴해석을 통하여 본 프로그램의 타당성을 입증하였고, 이를 순수 휨을 받는 양단의 단순지지된 원호 아치의 좌굴해석에 적용시켜 그 결과들을 다른 연구 결과들과 비교 검토하여 보았다.

• Mycobiology
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• 제43권3호
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• pp.366-370
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• 2015

Acanthopanax divaricatus, a member of the Araliaceae family, has been used as an invigorant in traditional Korean medicine. During disease monitoring, a stem with small, irregular, brown lesions was sampled at a farm in Cheonan in 2011. The symptoms seen were sunken cankers and reddish-brown needles on the infected twig. The isolated fungal colonies were whitish, having crenated edges and aerial mycelium on the surface, and with black gregarious fruiting bodies. The reverse plate was creamy white. Conidia were $17{\sim}22{\times}3.5{\sim}4.2{\mu}m$, fusiform, 4-septate, and straight to slightly curved. The nucleotide sequence of the partial translation elongation factor 1 alpha gene of the fungal isolate, shares 99% sequence identity with that of known Pestalotiopsis ellipsospora. Based on the results of the morphological and molecular analyses, the fungal isolate was identified as P. ellipsospora. In Korea, this is the first report of canker on A. divaricatus.

• 소성∙가공
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• 제31권2호
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• pp.96-102
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• 2022

The multi-point dieless forming technology is one of flexible forming technologies that can form 3D curved surfaces of various shapes utilizing a lot of punch arrangements. A new technology that can simultaneously apply high-temperature forming and flexible forming technology by fusing local heating effect to such multi-point dieless forming technology was proposed in the present study. A simple local heating multi-point dieless forming apparatus was fabricated to confirm the applicability of this new technology. This equipment was designed to be used as a heat source by inserting heating cartridges in the head of the multi-point punch. Cartridges were used for all individual punches. Using the manufactured equipment, the time to raise the temperature to the target temperature and the surface temperature of the punch head part in contact with the plate were measured. In addition, forming experiments were carried out according to sheet material temperature (100 ℃, 200 ℃, and 300 ℃) to obtain forming results for each condition. The applicability and feasibility of this technology were confirmed through experimental results.

• The Journal of Advanced Prosthodontics
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• 제2권3호
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• pp.92-96
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• 2010

PURPOSE. The aim of this study was to evaluate the thickness of buccal and palatal alveolar bone and buccal bony curvature below root apex in maxillary anterior teeth of Korean adults using Cone-beam CT images. MATERIALS AND METHODS. The 3D image was reconstructed with dicom file obtained through CBCT from 20 - 39 year old Korean subjects (n = 20). The thickness of buccal and palatal plate, root diameter, the buccal bony curvature angle below root apex and the distance from root apex to the deepest point of buccal bony curvature were measured on maxillary anterior teeth area using OnDemand3D program. RESULTS. Mean thickness of buccal plate 3 mm below CEJ was $0.68{\pm}0.29\;mm$ at central incisor, $0.76{\pm}0.59\;mm$ at lateral incisor, and $1.07{\pm}0.80\;mm$ at canine. Mean thickness of palatal plate 3 mm below CEJ was $1.53{\pm}0.55\;mm$ of central incisor, $1.18{\pm}0.66\;mm$ of lateral incisor, $1.42{\pm}0.77\;mm$ of canine. Bucco-lingual diameter 3 mm below CEJ was $5.13{\pm}0.37\;mm$ of central incisor, $4.58{\pm}0.46\;mm$ of lateral incisor, and $5.93{\pm}0.47\;mm$ of canine. Buccal bony curvature angle below root apex was $134.7{\pm}17.5^{\circ}$ at central incisor, $151.0{\pm}13.9^{\circ}$ at lateral incisor, $153.0{\pm}9.5^{\circ}$ at canine. Distance between root apex and the deepest point of buccal bony curvature of central incisor was $3.67{\pm}1.28\;mm$ at central incisor, $3.90{\pm}1.51\;mm$ at lateral incisor, and $5.13{\pm}1.70\;mm$ at canine. CONCLUSION. Within the limitation of this study in Korean adults, the thickness of maxillary anterior buccal plate was very thin within 1mm and the thickness of palatal plate was thick, relatively. The buccal bony curvature below root apex of maxillary central incisor was higher than that of lateral incisor and canine and it seems that the buccal bony plate below root apex of central incisor is most curved.

• 대한토목학회논문집
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• 제30권6A호
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• pp.495-502
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• 2010

이 논문에서는 비부착 프리스트레스트 CFRP 판으로 보강된 콘크리트 거더의 비선형 휨거동에 대한 해석방법을 제시하였다. 비부착 프리스트레스트 CFRP 판으로 보강된 콘크리트 거더는 CFRP 판의 슬립(slip)으로 인해 인장력이 재분배되어 CFRP 판이 콘크리트에 부착된 경우에 비해 복잡한 비선형 거동을 보이게 된다. 따라서 이 논문에서는 비부착 프리스트레스트 CFRP 판을 여러 개의 곡선 요소로 모사하고, 화이버 뼈대요소의 각 절점에서 힘의 평형 관계를 이용하여 CFRP 판의 인장력을 재분배함으로써 슬립효과를 고려하였다. 이 논문에서 제시한 해석방법을 비부착 프리스트레스트 CFRP 판으로 보강된 콘크리트 보의 해석에 적용하여 해석방법의 정당성을 확인하였다. 또한 비부착 CFRP 판의 보강시점과 보강 전후에 발생한 콘크리트의 시간의존적 변형은 보의 처짐 거동에는 영향을 미치나 극한내력에는 영향을 미치지 않음을 확인하였고, 비부착 CFRP 판으로 보강하기 전에 발생한 콘크리트의 균열유무도 비부착 CFRP 판으로 보강한 후의 보의 극한거동에는 거의 영향을 미치지 않음을 확인하였다.

• 한국컴퓨터그래픽스학회논문지
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• 제4권1호
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• pp.79-88
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• 1998

현재까지 불과 같은 유체를 렌더링하기 위한 많은 모델들이 개발되었다. 특히 메타볼은 단순성과 유동성의 특정으로 인해 눈이나 물과 같은 유체의 곡면을 모델링하기 위한 기법으로 많이 사용되어졌다. 본 논문은 중력장내에서 변형되는 물방울을 모델링하기 위한 새로운 방법을 제안한다. 이전의 연구에서 물방울은 단순한 메타볼에 의해 표현되었다. 물방울에 중력이 고려되지 않았기 때문에 렌더링 결과는 실제적인 물방울의 형태를 표현할 수 없었다. 우리는 기존의 메타볼에 실세계의 중력과 마찰력을 고려함으로서 평탄한 지면위에 놓여진 물방울의 형태를 생성하는 새로운 방법을 보여준다. 본 연구의 새로운 메타볼 모델은 이전의 메타볼이 가지는 스칼라 공간의 isosurface값을 중력을 고려한 벡터 공간으로 이동하여 얻어진다. 결과로서 광선 추적 기법과 물방울의 그림자 형성을 통해 실제적인 물방울의 형태를 렌더링한다.

• Steel and Composite Structures
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• 제37권2호
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• pp.117-136
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• 2020

Curved steel-concrete composite box girder has been widely adopted in urban overpasses and ramp bridges. In order to investigate its mechanical behavior under complicated and combined bending, shear and torsion load, two large-curvature composite box girders with interior angles of 25° and 45° were tested under static hogging moment. Based on the strain and deflection measurement on critical cross-sections during the static loading test, the failure mode, cracking behavior, load-displacement relationship, and strain distribution in the steel plate and rebar were investigated in detail. The test result showed the large-curvature composite box girders exhibited notable shear lag in the concrete slab and steel girder. Also, the constraint torsion and distortion effect caused the stress measured at the inner side of the composite beam to be notably higher than that of the outer side. The strain distribution in the steel web was approximately linear; therefore, the assumption that the plane section remains plane was approximately validated based on strain measurement at steel web. Furthermore, the full-process non-linear elaborate finite element (FE) models of the two specimens were developed based on commercial FE software MSC.MARC. The modeling scheme and constitutive model were illustrated in detail. Based on the comparison between the FE model and test results, the FE model effectively simulated the failure mode, the load-displacement curve, and the strain development of longitudinal rebar and steel girder with sufficient accuracy. The comparison between the FE model and the test result validated the accuracy of the developed FE model.