• Journal of Welding and Joining
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• 제3권2호
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• pp.27-34
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• 1985

The mechanical properties and bonding mechanism of aluminum, copper and mild steel have been determined in cold pressure welding. The brittle cover layer to be established by scratch-brushing plays an important role in bond strength and has an influence on the threshold of deformation. The cold pressure welding was achieved at 54% of height reduction in A1-A1, 75% in Cu-Cu, 56% in Al-Cu, and 74% in Cu-steel. The height reduction at which the bond strength of weld interface was the same as the tensile strength of base metal should be over 76% in Al-Al, 82% in Cu-Cu, and 78% in Al-Cu.

• 한국콘텐츠학회:학술대회논문집
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• 한국콘텐츠학회 2019년도 춘계종합학술대회
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• pp.275-276
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• 2019

The purpose of this study was to assess condylar size in volumetric 3D imaging in patients with class I, class II, class III malocclusions. To evaluate the differences among the three experimental groups, the condylar values of men were analyzed. There was a significant difference in the measured values of height. Among the three experimental groups, the condylar measurements in women showed significant differences in height and width. This study is expected to be used for determining the connection between malocclusion and condyle as a base line data.

• 대한치과교정학회지
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• 제6권1호
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• pp.39-46
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• 1976

This study was undertaken to establish the cephalometric standards, using lateral cephalometric roentgenograms of 48 male and 53 female Korean adults with normal occlusion and acceptable profile. By Cohen's method, measurement of depth was taken parallel to the FH plane and expressed as a percentage of the cranial base depth (BA-N). And vertical height was measured along the line perpendicular to the FH plane and expressed as a percentage of the anterior face height (N-M). The following conclusions were obtained: 1) Means and standard deviations of craniofacial proportions of Korean adults were tabulated. 2) Cranial babe depth of male was greater than that of female. 3) The proportionate depth of the middle face was greater in female than in male. 4) The proportionate total anterior face height was greater in male than in female. And it was greater in Korean than in the white.

• 신재생에너지
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• 제5권1호
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• pp.40-46
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• 2009

Optimization of a rectangular profile annular fin with variable pipe inside radius is presented. This optimum procedure is based on fixed fin height and is made by using variables separation method. The optimum heat loss, corresponding optimum fin length and optimum fin efficiency are presented as a function of pipe inside radius, fin half height, inside fluid convection characteristic number and ambient convection characteristic number. One of results shows that the optimum fin length increases linearly with increase of pipe inside radius for fixed fin height and fin base radius.

• Structural Monitoring and Maintenance
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• 제4권4호
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• pp.351-364
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• 2017

In this study effects of various parameters like a number of bays, the stiffness of the structure along with the height of the structure was examined. The fundamental period of vibration T of the building is an important parameter for evaluation of seismic base shear. Empirical equations which are given in the Indian seismic code for the calculation of the fundamental period of a framed structure, primarily as a function of height, and do not consider the effect of number of bays and stiffness of the structure. Building periods predicted by these expressions are widely used in practice, although it has been observed that there is scope for further improvement in these equations since the height alone is inadequate to explain the period variability. The aim of this study is to find the effects of a number of bays in both the directions, the stiffness of the structure and propose a new period equation which incorporates a number of bays, plan area, stiffness along with the height of the structure.

• 한국산림과학회지
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• 제108권3호
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• pp.364-371
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• 2019

본 연구는 전라도 지역의 주요 수종인 소나무와 편백의 흉고직경에 따른 우세목의 수고생장모델과 지위지수곡선을 개발하여 합리적인 경영과 지속가능한 산림경영체계의 기초자료를 제공할 목적으로 실시하였다. 데이터는 맞춤형 조림지도 제작을 위한 전라도 지역에 생육하고 있는 소나무 3,055본(611개 표본점), 편백 3,345본(669개 표본점)에 대한 표고, 경사도, 방위, 토양형, 우세목의 수고와 흉고직경, 수령 등을 측정하여 수집하였다. 전라도 지역 소나무와 편백에 대한 흉고직경에 따른 우세목의 수고생장모델은 Petterson식, Michailow식, Log식을 이용하였으며, 연령에 따른 우세목의 수고생장모델은 Chapman-Richards식, Schumacher식, Gompertz식을 이용하여 개발하였다. 흉고직경에 따른 우세목의 수고생장모델은 소나무와 편백 모두 잔차평균제곱의 값이 가장 낮은 Pettersosn식을 선정하였다. 연령에 따른 우세목의 수고생장모델은 국가수준에서 사용하고 있는 Chapman-Richards식을 선정하였다. 지위지수의 추정을 위하여 기준임령(Base age)은 30년을 사용하였다. 그 결과 소나무는 지위지수 6~18, 편백은 지위지수 6~22로 국가수준에서 사용하고 있는 지위지수곡선에 비해 매우 다양하게 지위를 추정할 수 있어, 현실임분의 합리적인 경영을 위한 자료제공에 적합한 것으로 판단된다.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2001년도 춘계 학술대회논문집
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• pp.60-65
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• 2001

The projectile afterbodies for zero-lift drag reduction has been analyzed using the Navier-Stokes equations with the $\kappa-\epsilon$ turbulence model. The numerical method of a second order upwind scheme has been used on unstructured adaptive meshes. Base drag reduction methods that have been found effective on axisymmetric bodies include boattailing, base bleed, base comustion, locked vortex afterbodies and multistep afterbodies. In this paper, the charateristics of turbulence flow have been studied for geomeries of multistep afterbodies. The important geometrical and flow parameters relevant to the design of such afterbodies have been identified by number, length and height of step. The flow over multistep afterbodies has been analyzed including expansion waves, recompression waves, recirculating flow, shear flow and wake flow. The numerical results have been compared and analyzed with the experimental datum.

• Structural Engineering and Mechanics
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• 제52권5호
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• pp.875-887
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• 2014

The aim of the shaking table experiment is to verify the isolation effect of a storage liquid tank with multiple friction pendulum bearings. A 1:20 scale model of a real storage liquid tank that is widely used in the petroleum industry was examined by the shaking table test to compare its anchored base and isolated base. The seismic response of the tank was assessed by employing the time history input. The base acceleration, wave height and tank wall stress were used to evaluate the isolation effect. Finally, the influences of the bearing performance that characterizes the isolated tank, such as the friction force and residual displacement, were discussed.

• International Journal of Air-Conditioning and Refrigeration
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• 제13권3호
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• pp.145-151
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• 2005

A thermally asymmetric straight rectangular fin is analysed and optimized using the two-dimensional separation of variables method. The optimum heat loss is presented as a function of bottom to top Biot number ratio, fin base length and top Biot number. Decreasing rate of the optimum fin length with the increase of the fin base length is listed. The optimum fin tip length is shown as a function of bottom to top Biot number ratio, fin base length and tip to top Biot number ratio. One of the results shows that the optimum heat loss and the actual optimum fin length decrease while the optimum fin tip length increases as the fin base length increases.

• Journal of Periodontal and Implant Science
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• 제48권3호
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• pp.174-181
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• 2018

Purpose: The aims of the present study were to quantitatively assess graft height changes after sinus lift procedures and to analyze the factors that influenced graft height changes, including the residual bone height before surgery, surgical approach, and tooth type. Methods: A total of 39 maxillary posterior implants placed during a simultaneous sinus lift procedure were evaluated. Panoramic radiographs of all patients were taken immediately after implant installation and at 3 months, 6 months, 1 year, 2 years, and 3 years. To analyze graft height changes over time, we measured the distance between the implant platform and the base of the grafted sinus floor at 3 locations. The radiographs were analyzed by a single examiner. Results: Graft height tended to decrease over time, and a statistically significant difference was observed at 2 years compared to baseline (P<0.05). There was no statistically significant difference in graft height change according to the surgical approach or tooth type. For residual bone height, a statistically significant difference in graft height change was found between those with 4-7 mm of residual bone height and those with ${\geq}7mm$ (P<0.05). Conclusions: Graft height after sinus lift procedures significantly decreased at 2 years compared to baseline after sinus augmentation. Further studies should be done with controlled variables, and prospective studies with 3-dimensional images are needed to clarify the factors that influence graft height changes.