• 한국정밀공학회지
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• 제22권6호
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• pp.175-182
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• 2005

Inner structured and bonded panel, or ISB Panel, as a kind of sandwich type panel, has metallic inner structures which have low relative density, because of their dimensional shape of metal between a pare of metal skin sheets or face sheets. In this work, ISB panels and inner structures formed as repeated pyramidal shapes are introduced. Pyramidal structures are formed easily with expanded metal sheet by the crimping process. Three kinds of pyramidal structures are made and used to fabricate test specimen. Through the multi-point electrical resistance welding, inner structures are bonded with skin sheet. 3-point bending tests are carried out to measure the bending stiffness of ISB panel and experimental results are discussed.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.381-382
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• 2006

The mechanical behaviors of multi-layered foam core sandwich composite were investigated through a 3-point bending test. The sandwich specimens were obtained from sandwich panel consisting of aluminum faces and urethane foam core. Three types of sandwich specimens such as a single structure, a double structure and a triple structure were considered. The span of sandwich specimens were varied from 170mm to 350mm. According to the results, the flexural and shear properties of multi-layered sandwich composite were found to be higher than those of single-layered sandwich composite.

• 한국해양공학회지
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• 제23권3호
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• pp.1-5
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• 2009

It is necessary to develop an efficient optimization technique to optimize engineering structures that have given design spaces, discrete design values, and several design goals. In this study, an optimum algorithm based on the genetic algorithm was applied to the multi-object problem to obtain an optimum solution that simultaneously minimizes the structural weight and construction cost of panel blocks in ship structures. The cost model was used in this study, which includes the cost of adjusting the weld-induced deformation and applying the deformation control methods, in addition to the cost of the material and the welding cost usually included in the normal cost model. By using the proposed cost model, more realistic optimum design results can be expected.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집 Vol.3 No.2
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• pp.849-852
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• 2002

Recently, amorphous selenium is used as x-ray conversion material for flat-panel x-ray detector. In this paper, we investigated the effect of breakdown under high voltage and leakage current in PN-type multi-layer structure based on p-type a-Se and n-type conductive thin film. Experimental results show that the multi-layer based detector reduced leakage current because n-type CeO2 conductive layer prevent from hole injection into a-Se layer from collection electrode, Also, the breakdown voltage was improved by dielectric layer between a-Se and top electrode.

• 유통과학연구
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• 제17권3호
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• pp.85-95
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• 2019

Purpose - The existing marketing studies using Social Network Analysis have assumed that network structure variables are time-invariant. However, a node's network position can fluctuate considerably over time and the node's network structure can be changed dynamically. Hence, if such a dynamic structural network characteristics are not specified for virtual goods purchase model, estimated parameters can be biased. In this paper, by comparing a time-invariant network structure specification model(base model) and time-varying network specification model(proposed model), the authors intend to prove whether the proposed model is superior to the base model. In addition, the authors also intend to investigate whether coefficients of network structure variables are random over time. Research design, data, and methodology - The data of this study are obtained from a Korean social network provider. The authors construct a monthly panel data by calculating the raw data. To fit the panel data, the authors derive random effects panel tobit model and multi-level mixed effects model. Results - First, the proposed model is better than that of the base model in terms of performance. Second, except for constraint, multi-level mixed effects models with random coefficient of every network structure variable(in-degree, out-degree, in-closeness centrality, out-closeness centrality, clustering coefficient) perform better than not random coefficient specification model. Conclusion - The size and importance of virtual goods market has been dramatically increasing. Notwithstanding such a strategic importance of virtual goods, there is little research on social influential factors which impact the intention of virtual good purchase. Even studies which investigated social influence factors have assumed that social network structure variables are time-invariant. However, the authors show that network structure variables are time-variant and coefficients of network structure variables are random over time. Thus, virtual goods purchase model with dynamic network structure variables performs better than that with static network structure model. Hence, if marketing practitioners intend to use social influences to sell virtual goods in social media, they had better consider time-varying social influences of network members. In addition, this study can be also differentiated from other related researches using survey data in that this study deals with actual field data.

• 한국산학기술학회논문지
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• 제12권11호
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• pp.5172-5177
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• 2011

본 논문은 박막 실리콘 태양전지에 적용되는 반사방지 또는 고반사 코팅 기술에 관한 연구이다. 태양광 흡수율을 개선하기 위하여 박막 실리콘 태양전지의 앞면에는 반사를 줄이는 반사방지막 기술이 필요하며, 뒷면에는 반대로 반사를 높이는 고반사 기술이 필요하다. 반사방지막 기술에서 단층의 구조에서는 코팅의 두께에 따라 반사율이 틀려지고, 적절한 범위에서 두께를 제어하면 낮은 반사율을 얻을 수 있다. 대칭형태의 다층의 구조에서는 단층구조에 비해서 넓은 파장대에 걸쳐서 낮은 반사율을 얻을 수 있다. 또한 뒷면에 적용되는 고반사막 기술에서는 높은 굴절율을 갖는 매질과 낮은 굴절율을 갖는 매질을 대칭 구조로 구성하여 계산한 결과 높은 반사율을 얻을 수 있다는 것을 확인하였다.

• Computers and Concrete
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• 제22권3호
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• pp.327-336
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• 2018

Increase in population and its daily increasing in our today society results in an increase in housing demand while traditional methods are not applicable. The project preparation and realization processes, based on theoretical and empirical studies, a creation of goods, services, and technologies, are the most important human activities. Selection of effective technological systems in construction is a complex multi-criteria decision-making task. Many decision-makers refuse innovations once faced with similar difficulties. Therefore, using modern materials and methods in this industry is necessary. Modern methods increase quality and construction speed in addition to decrease energy consumption and costs. One of the problems in the way of any project is selecting construction system compatible with the project needs and characteristics. In the present research, different concrete structures such as common reinforced concrete (RC) structure, prefabricated, Insulating Concrete Formwork (ICF), 3D Panel and Tunnel Concrete Formwork (TCF) for buildings with limited floors in Iran are studied and compared from the viewpoint of different criteria like cost, time, applicability and technical characteristics with industrialization approach. Therefore, some questionnaires filled out by construction industry experts in order to compare criteria and sub-criteria in addition to evaluation of optimized structural systems. Then, results of the questionnaires ranked by Analytic Hierarchy Process (AHP) and the most effective alternative selected. The AHP results show that 3D Panel system 36.5%, ICF 21.7%, TCF 19.03%, prefabricated system 13.3% and common RC system 9.3% are the most and the least efficient systems respectively.

• 한국항공우주학회지
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• 제40권2호
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• pp.157-164
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• 2012

다기능 구조체는 전자장비, 열제어 부품, 우주복사 차폐물 및 지지구조물이 하나의 시스템으로 통합된 구조적 결합체로써, 위성 및 행성탐사선 모듈의 소형화/경량화를 달성하여 경제성을 획기적으로 향상시킬 수 있는 매우 중요한 첨단 모듈이다. 본 연구에서는 구조적인 강도를 고려하여 설계된 다기능 구조체의 6가지 형상에 대하여 방열성능을 수치해석적인 방법으로 검토하였다. 다기능 구조체의 rib 형상이 방열판 내 전열효과에 미치는 영향은 열전도 측면만을 고려하는 것은 의미가 없으며, 구조적인 강성, 제작의 난점, 무게 등을 모두 고려하여야 하고, 전열 측면에서는 rib의 형상보다 면재 외부층의 두께와 무게에 대한 trade-off를 통하여 최적화하는 것이 일반적으로 유효하다고 판단된다.

• 대한기계학회논문집A
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• 제24권3호
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• pp.701-709
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• 2000

As the welding spot forms a singular geometry of an external crack type, fatigue failure of spot-welded specimens can be evaluated by means of a fracture parameter. Recasting the load vs. fatigue life relationships experimentally obtained, we predicted the fatigue life of spot-weld specimens with a single parameter denoted the equivalent stress intensity factor. This crack driving parameter is demonstrated to successfully describe the effects of specimen geometry and loading type in a comprehensive manner. The suggested fatigue life formula for a single spot weld can play a key role in the design and assessment of spot-welded panel structures, in that the fatigue strength of multi-spots is eventually determined by the fatigue strength of each single spot. We therefore attempt to evaluate the effectiveness and validity of $K_e$ in predicting the fatigue life of auto seat belt anchor panel. We first establish finite element models reflecting the actual mechanical behavior of 3 types of seat belt anchor specimens. Using finite element models elaborately established, we then obtain the effective crack driving parameter $K_e$ composed of its ductility -dependent modal components. It is confirmed that the $K_e$ concept successfully predicts the fatigue life of multi-spot welded panel structures represented by auto seat belt anchors here.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제10권1호
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• pp.47-60
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• 2006

평판 디스플레이 장치(FPD)의 패널 표면 결함 검출에서 일반적으로 사용되는 단순 문턱값에 의한 결함 검출은 FPD 패널 영상의 불균일한 휘도 변화로 인하여 정확한 결함 검출이 어렵다. 본 논문에서는 이러한 불균일한 휘도 변화를 보상하고, 정확한 결함 검출을 위해 다 해상도 분석방법인 웨이블릿 변환에 기반하여 높은 고주파 잡음제거와 함께 낮은 저주파를 제거함으로써 불균일한 휘도 변화를 보상할 수 있는 알고리즘을 제안하고 구현 하였다. 특히 제조 공정에서의 결함 검출을 실시간 인라인으로 적용하기 위해 리프팅 기반 고속 알고리즘으로 구현하였다.