• Journal of the Korean Institute of Landscape Architecture
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• v.29 no.2
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• pp.61-67
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• 2001

The purpose of this thesis was to provide the basic data for landscape architecture of apartment constructions and to minimize the users´ and builder´ loss in terms of finance and landscape due to defects in planting. After a review of literature related to defects of planting work, the researcher investigated the defects in planting of landscape plants on the basis of data from the drawing and defect-repair construction of 50 civil apartment complexes in Daegu and Kyongbook are from 1994 to 1998. The defect-ratio was analysed in terms of the species, shapes, and sizes of trees. It provides matters for consideration in terms of the design of the landscape planting on the apartment unit. It also provided the future directions for landscape architecture in apartment constructions with regard to the selection of the planting trees, etc., given statistics on defect occurrence. The causes of defect of the landscape planting trees were not studied accurately in this study due to the board range of researched area, the differences of the planting ground environment, the management ability, and the parameters of judging planting defects. It is recommended that those areas should be researched in the future.

• Advances in nano research
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• v.16 no.1
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• pp.91-109
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• 2024

Carbon nanotubes are drawing wide attention of research communities and several industries due to their versatile capabilities covering mechanical and other multi-physical properties. However, owing to extreme operating conditions of the synthesis process of these nanostructures, they are often imposed with certain inevitable structural deformities such as single vacancy and nanopore defects. These random irregularities limit the intended functionalities of carbon nanotubes severely. In this article, we investigate the mechanical behaviour of double-wall carbon nanotubes (DWCNT) under the influence of arbitrarily distributed single vacancy and nanopore defects in the outer wall, inner wall, and both the walls. Large-scale molecular simulations reveal that the nanopore defects have more detrimental effects on the mechanical behaviour of DWCNTs, while the defects in the inner wall of DWCNTs make the nanostructures more vulnerable to withstand high longitudinal deformation. From a different perspective, to exploit the mechanics of damage for achieving defect-induced shape modulation and region-wise deformation control, we have further explored the localized longitudinal and transverse spatial effects of DWCNT by designing the defects for their regional distribution. The comprehensive numerical results of the present study would lead to the characterization of the critical mechanical properties of DWCNTs under the presence of inevitable intrinsic defects along with the aspect of defect-induced spatial modulation of shapes for prospective applications in a range of nanoelectromechanical systems and devices.

• Transactions of Materials Processing
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• v.11 no.5
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• pp.430-438
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• 2002

This paper suggests the new technology to control metal flow in orther to change of the cold forging from conventional deep drawing forming. This technology can be summarized the complex forming, which consists of bulk forming and sheet forming, and multi-action forging, which be performed double action press. The proposed technology is applied to hub clutch model which is part of auto-transmission for automobile. The purpose of this study is to investigate the material flow behavior of hub clutch through control the relative velocity ratio and the stroke of mandrel and punch using the flow forming technique. First of all, the finite element simulations are applied to analyse optimal process conditions to prevent flow defect(necking defect etc.) from non-uniform metal flow, then the results are compared with the plasticine model material experiments. The punch load for real material is predict from similarity law. Finally, the model material experiment results are in good agreement with the FE simulation ones.

• Journal of the Korean Ceramic Society
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• v.40 no.11
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• pp.1102-1105
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• 2003

The fiber drawing process induced defects in silica fiber have been investigated. This study has focused on the Oxygen Deficient Centers (ODCs) and E' centers induced by the fiberization process in low-OH silica fibers. To investigate those defects induced by the fiberization process, the optical absorption spectrum and Electron Spin Resonance (ESR) have both been employed. The concentration of Oxygen Deficient Centers (ODCs) and E' centers are increased by the fiber drawing process. The population of defects in the neck-down region has also been investigated. The most significant generation of defects during fiber drawing process has been shown to occur in this region of silica preform. The population of defects is higher on the edge region than in the center of neck-down region.

• Transactions of the Korean Society of Mechanical Engineers
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• v.9 no.5
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• pp.677-682
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• 1985

극치해석적인 상계정리를 기초로 하여, 평면변형 인발에서 발생하는 내부결함(central bursting)을 예측하기 위해 중심에서 공동(voids)을 가진 금속에 대해 비례흐름(proportional flow)과 내부결 함의 흐름을 비교하여 해석하였다. 이 결함을 촉진시키는 공정조건에 대한 판정식(criterion)을 변형경화 금속에 대해 유도하였다. 공동을 가진 금속은 공동들을 축소시키기 위해 정상적인 재 료(sound material)의 흐름과 동일 방법으로 흐를 수 있으며, 경우에 따라서는 내부결함을 확장 하기 위해 흐를 수도 있다. 본 연구에서는 다이의 경사각, 단면감소율 및 마찰 등의 어떤 공정 변수 영역에서 중심축 상에 많은 공동을 가진 변형경화 금속에서도 내부결함이 발생할 수 있다는 것이다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.637-638
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• 2006

V-belt pulleys play a key role in driving cooling pump, oil pump, air-conditioner and so on by using an engine power. Precision deep drawing is one of the main processes for manufacturing the pulleys. Operation variables of the deep drawing equipment, called the setup parameter, must be re-determined whenever the specifications of pulley to be produced are changed. The defect rates during a setup of equipment and the working hours needed for the setup are almost dependent on workers' know-how. This study designs the program for easily determining setup conditions in pulley manufacturing process.

• Transactions of Materials Processing
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• v.17 no.2
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• pp.91-96
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• 2008

The governing parameters affecting the fatigue properties have been investigated experimentally in the high carbon steel wires with 0.94 wt.%C. In order to find the crucial factors, the advanced analysis techniques such as optical 3-D profiler, focused ion beam(FIB) and transmission electron microscope(TEM) were used. The two-type steel wires with different drawing strain were fabricated. The fatigue properties were measured by hunter rotating beam tester, specially designed for thin-sized steel wires. It was found that the fatigue properties of the steel wires with high drawing strain was higher than that with other wires because of low residual stress and high adhesion condition of brass coating layer.

• Journal of the Korean Society of Industry Convergence
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• v.17 no.3
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• pp.122-135
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• 2014

This paper was studied on the horizontal continuous casting of Al-xSi(x=10~15%) aluminum alloy. The experiments of the horizontal continuous casting was carried out by the horizontal continuous casting machine for various casting conditions and investigated on fracture types and mechanisms. Surface defect types for the horizontal continuous casting is also investigated. And the study was carried out that the horizontal continuous casting conditions such as casting temperature, cooling rate, and drawing speed affect the hardness and primary silicon size of Al-xSi(x=10~15%) aluminum rod bar. Casting temperature within this experiment conditions don't affect on the hardness of rod bar but the higher casting temperature is the smaller primary silicon size. The higher cooling rate and drawing speed have the higher hardness and the smaller primary silicon size.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.05a
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• pp.148-151
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• 2009

This paper presents an experimental study of deep-drawing and rubber-pad forming process using titanium alloy sheet. The process and results of the work carried out to investigate the capability of the process and to optimize th process parameters to ensure a sound forming. Room and high temperature tensile tests were carried out at various process conditions and microstructural evaluation was investigated. The experimental investigation was done using 150 ton hydraulic press to produce a deep-drawn part. Both graphite lubricant and polyethylene sheet were essential for defect-free product. Regarding the rubber-pad forming, reasonable formability was obtained only for pure-Ti not for Ti-6Al-4V.

• Transactions of Materials Processing
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• v.9 no.6
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• pp.624-630
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• 2000

Typical automotive opening parts, i. e. hood trunk lid and door, are made through the press operations such as drawing, trimming, flanging, and hemming. The dimensional accuracy of stamped panels is mainly dependent on the drawing operation. However, the gap between outer panels and opening parts, which is important to the appearance quality of the assembled body, is directly influenced by the flanging and hemming operation. In this study, the relation between the design parameters of the hemming operation and the defect of roll-in is shown. The effects of some design parameters on the gap are examined using CAE. furthermore, the simulated results of the hemmed part of tailgate comer are shown and discussed.