• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.10a
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• pp.276-279
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• 2002

A problem formulation and solution for design optimization of laminated composite channel section beam is presented in this study. The objective of this study is the determination of optimum section dimensions of composite laminated channel section beam which has equivalent flexural rigidities to flexural rigidities of steel channel section beam. The analytical model is based on the laminate theory and accounts for the material coupling for arbitrary laminate stacking sequence configuration. The model is used to determine the optimal section dimensions of composite channel section beam. The web height, flange width and thickness of the beam are treated as design variables. The solutions described are found using a global search algorithm, Genetic Algorithms (GA).

• Fashion & Textile Research Journal
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• v.11 no.2
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• pp.350-358
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• 2009

This research has a purpose to examine the actual conditions of natural dyeing program as a personal learning experience, participants' characteristics and common people's interest on natural dyeing nowadays. To examine the actual conditions of natural dyeing center and programs, many web sites and newspapers dealing with natural dyeing were used as main resources. As common people's interest on natural dyeing increased, there were a lot of natural dyeing centers in around country. To examine the interest on natural dyeing and the participants' characteristics of natural dyeing program, the data was obtained from a convenient survey of 326 respondents over 15 years old during 15th, May~30th, July in 2006. Almost 40% of respondents were interested in natural dyeing, but only 19% of respondents had ever participated in natural dyeing experience program. The participants' characteristics such as motivation, participating time, dyeing sources and materials, etc. were examined. Almost 65% of respondents were satisfied with natural dyeing experience. As long as people have interest on natural dyeing, Industrialization of natural dyeing will be advanced.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1996.10a
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• pp.105-112
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• 1996

Aluminium alloy have been used extensively as forging materials for aircraft components due to their high specific strength and corrosion resistance. A large portions of these materials are used as airframe components consisted of various combination of such Rib-Web structure. But the problem of high forging pressure and defect which were caused by narrow Rib thickness prevented from the favorable developments and laboratory scaled trials. In this study, optimization of forging variables such as corner radius and temperature in Rib-Wed structure were established. The 2 mm of corner radius minimized the forging pressure to get the fixed Rib height, which well coincided with theoretical result according to Upper-Bound analysis. And optimum workpiece temperature was below 450$^{\circ}C$ in consideration of grain growth and forging defects by local melting.

• Textile Coloration and Finishing
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• v.24 no.1
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• pp.62-68
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• 2012

Cellulose was electrospun over water collector and the cellulose solution was prepared using N-methyl-morpholine N-oxide/water(nNMMO/$H_2O$). The morphology of electrospun cellulose was investigated by scanning electron microscopy (SEM). SEM images showed that the fiber formation depended on processing parameters such as solution concentration, applied electric field strength, solution feeding rate and temperature of water in coagulation bath. High concentration, low temperature of water bath, and low feeding rate were more favorable to obtain fiber morphology. All the variables affected on the fluidity of the cellulose solution and diffusion of NMMO. Low fluidity and fast diffuision of NMMO was critical for obtaining fiber morphology.

• Composites Research
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• v.28 no.4
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• pp.162-167
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• 2015

Composite sandwich structures are widely employed in various applications, due to their high specific stiffness and specific bending strength compared to solid panels. Lately, for that reason, the advanced composite sandwich structures are employed in satellite structures: materials should be as light as possible with the highest attainable performance. This study is majorly focused on inserts employed to the composite sandwich satellite structures. A new hybrid insert design was developed in precedent study to reduce the mass of the sandwich structure since the mass of the satellite structure is related to high launching cost [1]. In this study, the thermal characteristics and behavior of the precedently developed hybrid insert with carbon composite reinforcing web and the conventional partial insert were numerically investigated.

• 기계와재료
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• v.22 no.1
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• pp.84-93
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• 2010

본 고에서는 소재분야의 기술수준을 정확히 파악하고, 앞으로 나아갈 R&D 정책방향을 설정하는 데 도움이 되도록 하기 위해 NS(National Science Indicators) DB와 Web of Science DB의 재료과학(Materials Science) 분야를 토대로 논문분석을 수행하였다. 최근 10년간(1999-2008년) 소재 분야에 대한 분석결과 양적 지표인 논문수는 연평균 12%로 지속적으로 증가하였으며, 세계순위는 1999년 9위에서 2008년 4위까지 상승하였다. 질적지표인 논문1편당 피인용횟수는 세계 평균 대비 1999년 94.7%(한국 9.35건, 세계 9.87건)에서 2008년 88.4%(한국 0.23건, 세계 0.26건)로 낮아진 것으로 나타났다. 최근 10년간 연구주체간 협력 논문수를 살펴보면 대학-대학간 이 4,337편(39.8%)으로 가장 많으며, 대학-공공연구기관간은 3,135건(28.8%), 대학-기업은 2,295건(21.1%)으로 전체의 약 90%를 차지하고 있다. 또한 해외 협력논문수는 전체 논문에서 약 26%를 차지하고 있다. 결과적으로 기초연구성과의 실용화 연계 지원책 마련, 질중심 논문평가의 강화, 국내외 협력주체간 협력 연수의 강화, 주기적 논문분석을 통한 소재 R&D 정책 수립 및 연구사업기획에의 활용강화 필요하다.

• Proceedings of the KOSOMBE Conference
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• v.1996 no.05
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• pp.221-222
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• 1996

In order to prepare the porous hydroxyapatite (HA) ceramics with different porosity, interconnectivity, mechanical properties, surface chemistry and tissue response, several methods have been developed. Of the different forms of Porous HA ceramics which were prepared by various methods, only the coralline HA has undergone major clinical applications in orthopaedic, maxillofacial and ophthalmic surgery. In this study, totally synthetic macroporous HA ceramics with various pore size distribution were prepared. It is shown that the new reticulate HA ceramics, comprised of interconnected voids surmunded by a web of ceramic, have a morphology which mimics that of human trabecular bone.

• The Journal of Korean Association of Computer Education
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• v.9 no.1
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• pp.19-28
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• 2006

In this paper, we have developed electronic textbooks for social studies centering on contents of a public educational process so that primary schools can use them as a text book. Also, we conducted a survey to find out how teachers perceived electronic textbooks in respect to site accessibility and utility, instructional design, progress of lesson, validity and accuracy of learning content, interface design, and web-based multimedia. In this paper, we presented a new model for electronic textbooks development, which is expected to be useful in developing electronic textbooks as a main text book, unlike other existing models. We applied the navigation utilizing book metaphors to the user interface, on the basis of the results from the analysis of the existing electronic textbooks. In addition, we provided affluent multi-media materials as well as hyperlink, a strong point of on-lines. Experimental results show that the academic achievement was high in knowledge-understanding areas and functional areas in the perspective of academic achievements of the learners.

• Applied Microscopy
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• v.18 no.2
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• pp.77-90
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• 1988

The ultrastructure of the excretory duct of the large ampullate gland in the orb web spider, Nephila clavain L. Koch are studied with light and electron microscopes. The excretory ducts of the large ampullate glands connected with the large spinning tubes(spigots) on the anterior spinnerets are basically composed of three superposed types of the layers which are inner cuticles, monolayered epithelial cells and peripheral connective cells. According to the morphological characteristics of the cuticles and internal textures of the epithelial cells, the long excretory ducts are subdivided into three(distal, middle and proximal) portions. Especially, at the distal portion of the ducts near the spinning tubes, the electron lucent subcuticles which had the functions of water removal and orientation of silk fibers are well distributed, whereas at the middle and proximal portions these layers disappeared and instead of these, endocuticles are developed. The endocuticle contains two types of bands, which are electron dense and electron lucent. And along the length of the cuticular stem in the excretory duct, these two alternating bands are twisted spirally. In the cytoplasm of the columnar epithelial cells of the distal portion, rough endoplasmic reticula and Golgj complexes, related to the production of the cuticular materials are well developed. Between the adjacent epithelial cells, specialized septate junctions and desmosomes are formed along the plasma membranes. At the proximal portion of the duct, densely accumulated secretory materials appeared, and these are released to the inner canal by the apocrine secretion.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.21 no.3
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• pp.124-128
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• 2011

Electrospun webs have been widely investigated for applying to drug delivery system (DDS) because of their high specific surface area and high porosity. In this study, the composite webs of PLA (poly(lactic acid)) and $TiO_2$ were fabricated by melt-electro-spinning method for applying to drug delivery system. The morphologies of PLA/$TiO_2$, webs were observed using scanning electron microscope (SEM) and field emission transmission electron microscope (FE-TEM). The crystal structures of PLA/$TiO_2$ composite webs were confirmed by X-ray diffractometer (XRD).