• Journal of Power System Engineering
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• v.7 no.2
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• pp.44-50
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• 2003

The power steering hose is a kind of high-pressure hose with reinforced braids in rubber material. It is usually manufactured through the swaging process. In this paper, the deformation characteristics of a power steering hose during the swaging process were analyzed using the nonlinear finite element method. The material properties were obtained on experiments, and the contact conditions were used in consideration of real manufacturing process. Investigations were focused on the stress and strain values of the hose and meta] components at the maximum jaw stroke and at the completion of the process. Especially, the results of inner rubber component were interpreted in detail, because of its important role in the hose efficiency.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.931-934
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• 2001

GaN nanowires has much interest as one-dimensional materials for blue light LED. GaN-based materials have been the subject of intensive research for blue light emission and high temperature/high power electronic devices. In this letter, the synthesis of GaN nanowires by the reaction of mixture of GaN nanowires by the reaction of mixture of Ga meta and GaN powder with NH$_3$ using thermal chemical vapor deposition is reported. X-ray diffraction, energy dispersive x-ray spectrometer, scanning electron microscopy, and transmission electron microscopy indicate that those GaN nanowires with hexagonal wurtzite structure were about 60nm in diameter and up to several hundreds of micrometers in length.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.63-63
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• 2010

나노 구조를 제작은 나노 기술을 기반으로 하는 electronics, optoelectronics, sensing, ultra display등의 여러 분야에서 이용되고 있다. 특히 나노 구조를 갖는 금속 패터닝의 경우 전자빔 리소 그래피 (electron beam lithography)나 레이저 패터닝(laser patterning)과 같은 방법들이 많이 사용되고 있다. 하지만 공정이 복잡하고 그로 인해 공정 비용이 많이 든다는 단점이 있었다. 나노 임프린트 리소그래피 기술은 master mold 표면의 나노 패턴을 가열, 가압 공정을 통해 기판 위의 고분자 레지스트 층으로 전사하는 기술이다. 이 기술은 간단한 공정을 통해 나노 패턴을 형성할 수 있는 기술이기 때용에 차세대 나노 패터닝 기술로써 각광받고 있다. 특히 이 기술은 레지스트 층과의 직접적인 접촉을 통해 나노 패턴을 형성하기 때문에 다양한 방법을 통해 기능성 나노 패턴을 직접적으로 형성할 수 있는 가능성을 지니고 있다. 본 연구는 novel meta1의 하나인 Ag 입자가 첨가된 ink solution를 master mold로부터 복제한 PDMS mold를 이용하여 다양한 구조의 나노 패턴을 만드는 방법에 대한 연구이다.

• Structural Engineering and Mechanics
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• v.51 no.3
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• pp.361-375
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• 2014

The main aim of this paper is to investigate the relationship between thickness and height of the axially symmetric cylindrical reinforced concrete (RC) walls by the help of a meta-heuristic optimization procedure. The material cost of the wall which includes concrete, reinforcement and formwork, was chosen as objective function of the optimization problem. The wall thickness, compressive strength of concrete and diameter of reinforcement bars were defined as design variables and tank volume, radius and height of the wall, loading condition and unit cost of material were defined as design constants. Numerical analyses of the wall were conducted by using superposition method (SPM) considering ACI 318-Building code requirements for structural concrete. The optimum wall thickness-height relationship was investigated under three main cases related with compressive strength of concrete and density of the stored liquid. According to the results, the proposed method is effective on finding the optimum design with minimum cost.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.309-310
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• 2007

Spacecrafts such as most of commercial satellites that are operating in the geostationary orbit can be subjected to intense irradiation by charged particles. The surface made of dielectric materials can therefore become probable sites for damaging electrostatic discharges. Thanks to a specially equipped chamber, the spatial environment can be reproduced experimentally in the laboratory. In this paper, the behavior of high energy electrons injected in polymers such as PolyMethylMetaAcrylate (PMMA) and Kapton is studied. Results obtained by surface potential technique, pulse-electro acoustic device and a cell based on the split Faraday cup system are analyzed and discussed.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.621-624
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• 1999

Metalization technology of the fine patterns by electroless plating is required in place of electrodeposition as high-density printed boards(PCR) become indispensable with the miniaturization of electronic components. Electroless nickel plating is a suitable diffusion barrier between conductor meta1s, such as Al and Cu and solder is essetional in electronic packaging in order to sustain a long period of service. Moreover, Electroless nickel has particular characteristics including non-magnetic property, amorphous structure. wear resistance, corrosion protection and thermal stability In this study fundamental aspects of electroless nickel deposition were studied with effort of complexeing agents of different kinds. Then the property of electroless deposit are controlled by the composition of the deposition solution the deposition condition such as temperature and pH value and so on. the characteristics of the deposits has been carried out.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.4
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• pp.95-102
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• 2012

The serious issue of tall building is to ensure the fire resistance of high strength concrete. Therefore, Solving methods are required to control the explosive spalling. The fire resistant finishing method is installed by applying a fire resistant material as a light-weight material to structural steel and concrete surface. This method can reduce the temperature increase of the reinforcement embedded in structural steel and concrete at high temperature due to the installation thickness control. This study is interested in identifying the effectiveness of light-weight fire protection material compounds including the inorganic admixture such as fly ash, meta-kaolin and light-weight aggregate as the fire resistant finishing materials through the analysis of fire resistance and components properties at high temperature. Also, this paper is concerned with change in microstructure and dehydration of the light-weight fire protection materials at high temperatures. The testing methods of fire protection materials in high temperature properties are make use of SEM and XRD. The study results show that the light-weight fire resistant finishing material composed of fly ash, meta-kaolin and light-weight aggregate has the thermal stability of the slight decrease of compressive strength at high temperature. These thermal stability is caused by the ceramic binding capacity induced by alkali activation reaction by the reason of the thermal analysis result not showing the decomposition of calcium hydrate. Developed light-weight fire protection materials showed good stability in high Temperatures. Thus, the results indicate that it is possible to fireproof panels, fire protection of materials.

• Journal of the Korean School Mathematics Society
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• v.3 no.1
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• pp.131-148
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• 2000

Above all, the ability to solve problems must be emphasized as a basic skill of mathematics, but it is neglected when we teach. In this study, learning task means ［same meaning］ ［same form］ ［same technique］, so I tried to extend mathematical scholastic ability of the students as an extensional problem solving that is a basic element of mathematics. The purpose of this study is the investigation of level type learning, using the basic learning elements to extend thinking ability. From the constructed hypothesis as follows and then implement it. I selected basic learning elements from an analyzed textbook and then task learning material was created for each level type learning. The problem solving ability will be extended through the level type learning of the small group, using the level type learning task material. The conclusions this study are as follows. The level type learning in small group learning, using and making level type learning material, having basic learning elements in analysed text are. Basic learning content is understood clearly and deeply, so, fundamentally, it is effective in achieving the problem solving in mathematics. It is an effective method to achieve the meta-cognitive faculty because achieved the expected method of solving problems and resulted in the true learning of content.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.12
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• pp.466-472
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• 2017

This study was designed to examine the diversity census of fungi in rumen microbiome via meta-analysis of fungal 28S rDNA sequences. Both terms, "rumen" and "ruminal," were searched to retrieve the sequences of rumen fungi. As of September 2016, these sequences (n=165) of ruminal origin were retrieved from the Ribosomal Database Project (RDP; http://rdp.cme.msu.edu), an archive of all 28S rDNA sequences and were assigned to the phyla Ascomycota, Neocallimastigomycota, and Basidiomycota, which accounted for 109, 48, and 8 of the 165 sequences, respectively. Ascomycota sequences were assigned to the genera Pseudonectria, Magnaporthe, Alternaria, Cochliobolus, Cladosporium, and Davidiella, including fungal plant pathogens or mycotoxigenic species. Moreover, Basidiomycota sequences were assigned to the genera Thanatephorus and Cryptococcus, including fungal plant pathogens. Furthermore, Neocallimastigomycota sequences were assigned to the genera Cyllamyces, Neocallimastix, Anaeromyces, Caecomyces, Orpinomyces, and Piromyces, which may degrade the major structural carbohydrates of the ingested plant material. This study provided a collective view of the rumen fungal diversity using a meta-analysis of 28S rDNA sequences. The present results will provide a direction for further studies on ruminal fungi and be applicable to the development of new analytic tools.

• Journal of Oriental Neuropsychiatry
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• v.32 no.3
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• pp.185-206
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• 2021

Objectives: The objective of this study was to perform a systematic review and meta-analysis of pharmacopuncture treatment for insomnia disorder to derive clinical evidence and recommendation grades. Methods: Studies that verified effects of pharmacopuncture on primary insomnia were included. Characteristics and quality of included studies were assessed using Risk of Bias (RoB). Results: A total of 25 studies were selected. Pittsburgh Sleep Quality Index (PSQI) and effective rate were primarily used for outcome measurement. Vitamin B12 was the most used pharmacopuncture material. The most frequently used acupuncture point was Anmian (Ex-HN). The volume of the acupuncture solution ranged from 0.25 mL to 2 mL. Acupuncture treatment depth was 0.5 cm to 2 cm. In three studies, the procedure was performed at 16:00. Meta-analysis of studies revealed that the effective rate of the pharmacopuncture group was significantly higher than the group using sleeping pills group (RR: 1.21, 95% CI: 1.01 to 1.45, p=0.04, I²=69%). PSQI was decreased in the intervention group (MD=-2.19, 95% CI: -2.90 to -1.48, p<0.00001, I²=0%). Effective rates of pharmacopuncture and acupuncture groups were higher than that of the acupuncture group (RR: 1.11, 95% CI: 1.05 to 1.17, p=0.0002, I²=0%). PSQI was decreased in the intervention group (MD=-1.87, 95% CI: -2.36 to -1.38, p<0.00001, I²=0%). Although the effectiveness rate of the pharmacopuncture group was not significantly higher than that of the acupuncture group (RR: 1.12, 95% CI: 0.98 to 1.27, p=0.1, I²=9%), the PSQI was decreased in the pharmacopuncture group (MD=-2.10, 05% CI: -3.29 to -0.91, p=0.0005, I²=34%). The quality of clinical studies was poor. Conclusions: Based on results of this study, it is proper to use 0.5 to 2 mL of pharmacopuncture solution such as Danshen and Ciwujia with a depth of 0.5 to 2 cm at around 4 p.m. to treat insomnia disorder, focusing on Anmian (Ex-HN) and Sameumgyo (SP6).