• Composites Research
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• v.18 no.6
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• pp.9-18
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• 2005

With the wide applications of fiber-reinforced composite material in aero-structures and mechanical parts, the design of composite joints have become a very important research area because the joints are often the weakest areas in composite structures. This paper presents an analytical study of the stress distributions in mechanically single-fastened and multi-fastened composite laminates. The finite element models which treat the pin and hole contact problem using a contact stress analysis are described. A dimensionless stress concentration factor is used to compare the stress distributions in composite laminates quantitatively In the case of single-pin loaded composite laminate, the effects of stacking sequence, the ratio of a hole diameter and the width of a laminate (W/D ratio), the ratio of hole diameter and distance from edge to hole (E/D ratio), friction coefficient and clamping force are considered. In the case of multi-pin loaded composite laminate, the influence of the number of pins, pitch distance, number of rows, row spacing and hole pattern are considered. The results show that P/D ratio and E/D ratio affect more on stress distributions near the hole boundary than the other factors. In the case of multi-pin loaded composite laminate, the stress concentration in the double column case is better than the other cases of multi-pin loaded composite laminate.

• Computational Structural Engineering
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• v.6 no.1
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• pp.91-98
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• 1993

Minimum weight design of the boom of an excavator with stress and displacement constraints was performed. The procedure of analysis consists of the following steps. The finite element model of the boom was built up by using 227 triangular plate elements each of which has three nodes. And then the finite element program was implemented and its accuracy was verified by comparing its results with those of the commercial structural analysis package-ANSYS 4.4A. For the constraints of stresses and displacements, the design sensitivities of those were computed using direct differentiation method. To verify the reliability of them the results were compared with those of the finite difference method. The optimum design value was obtained by using PLBA(Pshenichny-Lim-Belegundu-Arora)non-linear optimization program which adopts the active set strategy. Using the above results, minimum weight design of an excavator boom showed an effect of 27% reduction in weight.

• Composites Research
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• v.30 no.2
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• pp.165-168
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• 2017

Coiled polymer actuators fabricated by twisting polymer fishing lines or sewing threads respond to heating and cooling with their contraction and relaxation. However, their actuation speed is highly dependent on the heating and cooling rates. In order to improve the actuation speed, the coiled polymer actuator was coated with polydimethylsiloxane composites. The introduction of multi-walled carbon nanotubes into the polydimethylsiloxane improved the actuation speed by about 13%.

• Proceedings of the Membrane Society of Korea Conference
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• 1995.10a
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• pp.36-37
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• 1995

투과증발법은 기존의 증류법에 의해 분리되기 어려운 혼합물(공비혼합물이나 끓는점이 비슷한 혼합물)이외에 열에 민감한 생성물의 분리, 과익쥬스의 농축, 불순물 찌꺼기의 제거, 정량 검출을 위한 유기 오염물질의 농축 등에 이용되었으며 특히 물과 에탄올의 공비혼합물의 분리와 물로부터 희박 유기물질을 회수하는데 행해져 왔다. 본 연구에서 사용된 키토산은 친수성기들을 가지고 있기 때문에 물과 알코올의 분리에서 물을 선택적으로 투과시켜 효과적인 투과증발막으로 사용될 수 있으며 투과속도를 높이기 위해서 활성층이 매우 얇은 복합막을 제조하였다. 또한 키토산 복합막을 다양한 가교제 (glutaraldehyde, glyoxal, terephthalaldehyde, 황산등)로 가교한 막들을 열처리를 하거나 키토산과 PVA를 블렌드하여 제조한 키토산/PVA 블렌드 복합막을 이용하여 에탄올/물, IPA/물 혼합용액에서의 탈수 실험을 실시하여 이에 따른 투과성능의 영향을 살펴보았다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.8
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• pp.44-49
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• 2003

In case of an extrinsic Fabry-Perot interferometric sensor, the phase compensating technique is particularly necessary in applying the interferometer to detecting acoustic emission signals because of signal-fading problems. The technique makes it possible to maintain the phase at the quadrature point. In this paper, we developed the stabilization control sensor system that is composed of a broadband light source, a tunable Fabry-Perot (F-P) filter and a control-circuit board. A tension test of a composite specimen was performed to verify if the developed system could compensate the phase change induced from the tension strain and keep the phase at the quadrature point.

• Clinical and Experimental Pediatrics
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• v.49 no.11
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• pp.1167-1173
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• 2006

Purpose : To evaluate various sepsis screening tests, individually and in combination, to formulate a guideline for the diagnosis of neonatal sepsis. Methods : The study was a retrospective cohort study. It took place at the neonatal intensive care unit of the Paediatric Department, Il Sin Christian Hospital, Busan, Korea, over a period of 68 months from 1st, April, 2001 to 31st, December, 2005. This study evaluated 100 neonates having clinical features of sepsis and 100 normal asymptomatic neonates and used screening tests including C-reactive protein (CRP), total leukocyte count (TLC), absolute neutrophil count (ANC), immature neutrophils to total neutrophil count ratio (I/T ratio), thrombocytopenia, degenerative changes in the neutrophils and gastric aspirate cytology (GAC) for the diagnosis of neontal sepsis. Results : The sensitivity of CRP and ANC was high. CRP had 86 percent sensitivity for group-A (proven sepsis) and 74 percent sensitivity for group-B (probable sepsis) and 94 percent specificity for group-A, B. ANC had sensitivity of 72 percent for group-A and 62 percent for group-B and 86 percent specificity for group-A, B. For group-A, sensitivity, specificity of GAC for polymorphs was 74 percent and 94 percent respectively. As for sensitivity, specificity of platelet count for group-A was 64 percent and 89 percent respecively. The sensitivity, specificity and predictive values (PV) of the individual tests and different test combinations were also calculated for group-A and B. Conclusion : For the detection of culture negative cases in neonatal sepsis, screening tests including CRP, TLC, ANC, thrombocytopenia, cytoplasmic vacuolization in the neutrophils and GAC for polymorphs have high sensitivity. A combination of three tests has higher sensitivity.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.10a
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• pp.63-67
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• 2001

근래 가공소재로 폭넓게 활용되고 있는 신소재의 대부분은 난삭재로 분류되고 있으며 난삭재 사공에 대한 연구도 활발하게 진행되고 있다. 난삭성에 영향을 미치는 민감한 요인은 재표특성과 가공요소의 복합성을 들 수 있고, 난삭재의 가공은 재료마다 그 최상요건이나 가공방법이 다르므로 일률적인 취급은 곤란하여 각각의 특성을 정확하게 파악하는 것이 중요하다고 하겠다.

• Journal of Digital Convergence
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• v.12 no.6
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• pp.171-180
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• 2014

Recently, in order to promote their marketing strategy, the entrepeneurs attach importance to many shopping Application services and execute it. The representative elements of shopping Application are interactivity, information offering, convenience of use. This study verified the effects of interactivity, information supplying, and usage convenience, the application characteristics, on the application preferences and repurchase intentions, and the moderating effects of price sensitivity and usage frequency. The result states that the shopping application characteristics affect the shopping application preference, In terms of price sensitivity, the group with higher price sensitivity showed more significant result on the interactivity and usage convenience, and when the information supplying affects on the application preference, the group with higher price sensitivity showed more significant result than the group with lower price sensitivity.

• Clean Technology
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• v.20 no.3
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• pp.298-305
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• 2014

Ash included in coal can cause environmental pollution and it can decrease efficiency of mass and heat transfer by getting scorched and stick in the facilities operated at high temperature. To solve this problem, a feasibility study on pulverized coal fired power plant and integrated gasification combined cycle (IGCC) using the AFC (Ash-Free Coal) as well as the development to remove the ash from the coal was conducted. In this research, optimization of operating condition was proposed by using sensitivity analysis of ASPEN $Plus^{(R)}$ to apply the coal containing under the 200 ppm ash for integrated gasification combined cycle. Particularly, the coal gasification process was classified as three parts : pyrolysis process, volatile matter combustion process and char gasification process. The dimension and operating condition of 1.5 ton/day class non-slagging gasifier are reflected in the coal gasification process model.

• Journal of Digital Convergence
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• v.14 no.6
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• pp.425-430
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• 2016

The goal of this study is to explore the factors that influence on intention to use UHDTV Service. Research problems has been designed to Structural equation model by Technology Acceptance Model. The Perceived quality, Price sensitivity, Innovativeness are adopted as independent variables. And Perceived usefulness, Perceived ease of use are adopted as intervening variables. A result of analysis, Perceived quality and Price sensitivity influenced the Intention to use via Perceived usefulness and Perceived ease of use. But in case of Innovativeness, it did not influence the Perceived usefulness while it influenced the Perceived ease of use. Meanwhile, the influence of Perceived quality to Perceived usefulness had more impact than the other path between the other factors.