• Proceedings of the Korean Information Science Society Conference
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• 2002.10d
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• pp.277-279
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• 2002

웹 로그 기반의 웹 사용 마이닝은 명시적 평가 의존, 확장성 결여, 그리고 다차원 및 희박한 데이터에 성능이 떨어지는 협력적 여과의 문제를 다소 해결할 수 있다. 그러나 k-Means 군집화 방법으로 생성된 군집속 유사 사용자 이동 패턴으로는 클러스터속 사용자 전체의 선호도를 표현할 수 없으므로 사용자 이동 패턴인 트랜잭션들로부터 사용 프로파일을 유도해야 한다. 본 논문에서는 유사 군집 사용자들의 관심과 기호를 표현할 수 있도록 클러스터 내부 데이타로부터 평균 가중치 및 빈발 지지도 임계값을 사용하여 개선된 사용 프로파일을 생성하고 실험 데이터를 통한 예측력과 추천에 대한 성능을 평가한다.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1412_1413
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• 2009

초고압 전력케이블용 기중 종단접속재에 사용되는 지지애자의 전기적 고절연 성능과 기계적 Compact화된 제품개발을 목적으로 Simulation Tool을 활용하여 전계해석을 수행하였고, 해석된 결과를 기초로 지지애자를 설계, 개발 하였다. 개발된 지지애자의 Sample을 채취하고 전기적, 기계적 시험을 통하여 신뢰성을 검증 하였다. 전계해석에 있어서는 Epoxy와 Porcelain 재료, Old type과 New type으로 구분하여 재료별, 구조별로 해석을 진행 하였다. 지지애자의 설계기준과 전기적, 기계적 시험 결과를 비교하여 개발된 제품의 특성에 있어서 얼마만큼의 안전율을 확보 할 수 있는지 알 수 있었고, Porcelain 지지애자와 비교하여 약 40%의 크기를 축소할 수 있는 전기적, 기계적 신뢰성이 확보된 지지애자를 개발 할 수 있었다.

• Membrane Journal
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• v.33 no.6
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• pp.383-389
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• 2023

A high-performance forward osmosis (FO) membrane was prepared using polyethylene glycol diacrylate (PEGDA) hydrogel as a support layer. Through the UV-induced polymerization and subsequent phase separation of PEGDA, the crosslinked, hydrophilic, and porous PEGDA suppor layer was obtained. To achieve high FO flux and salt selectivity using the fabricated PEGDA support, a selective layer was synthesized via the toluene-assisted interfacial polymerization (TIP), in which toluene is used as an organic solvent. The prepared PEGDA-based FO membrane showed higher FO water flux and lower salt selectivity compared with commercial HTI membranes using 1.0 M NaCl draw solution and DI water feed solution. We propose the strategy to fabricate high-performance FO membranes utilizing supports formed with new hydrophilic materials and fabrication processes.

• Journal of Korean Tunnelling and Underground Space Association
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• v.8 no.3
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• pp.273-287
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• 2006

This study investigates the failure mechanism and load-carrying capacity of a single-shell lining which has no disturbance in transfer of shear force, with respect to a conventional double-shell lining which has separation between layers of shotcrete lining and secondary concrete lining by water-proof membrane. In order to evaluate the capacity, a 2-D numerical investigation is preliminarily carried out and then real-scale loading tests with tunnel lining section specimens are performed on the condition given by the numerical investigation. In the test, a concentrated load is applied for considering a released ground load or rock wedge load. Through this study, it appears that the single-shell lining takes the load-bearing capacity 20% higher than in case of the double-shell lining. In addition, a possibility of a composite single-shell shotcrete layer composed by multiple bonded layers partly involving different contents of high-capacity additives is shown thereby leading to use of less amount of the high-capacity additives on the condition of taking a similar load-bearing capacity.

• Membrane Journal
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• v.4 no.1
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• pp.46-56
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• 1994

The performane of prepared Thin-Film Composite membrane depends on supporting membrane, concentration of monomers, dipping time of supporting membrane into monomer solution, reachon time between monomers, curing temperature and time and posttreatment. This study was conducted for searching the optimal condition for making the composite membrane. For this purpose, supporting membrane and composite membrane was made under various condition and at each step were tested.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1989.06b
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• pp.60-69
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• 1989

안정성과 진동억제 특성이 요구되는 터어빈이나 모터등의 고속 회전기계에서는 틸팅-패드 저어널 베어링이 많이 사용되고 있다. 이는 틸팅-패드 저어널 베어링에서는 패드가 피봇이나 로울러로 지지되어 있으므로 윤활유막에서 발생하는 압력의 합력중심이 항상 이 지지점을 지나게 되어 베어링의 안정특성이 향상되기 때문이다. 틸팅-패드 저어널 베어링은 추력 베어링과 같이 불연속적인 윤활면을 갖는다. 그러므로 베어링의 입구부 선단에서 공급되는 윤활유의 충돌로 인한 압력격변이 일어나는데 이때 패드 입구부에서 발생하는 압력을 선단압력이라 한다. 이러한 선단압력으로 인한 베어링의 성능변화에 관한 연구는 주로 추력 베어링에 대하여 이론 및 실험적으로 수행 되어져 왔으며 그 결과들은 선단압력이 베어링의 성능에 미치는 영향을 무시할 수 없음을 보여주고 있다. 그러나 아직도 선단압력의 영향이 제대로 파악되고 있지 못하며, 특히 틸팅-패드 저어널 베어링에서 선단압력의 영향을 조사한 연구는 많이 부족한 실정이다. 그러므로 본 연구에서는 유한폭 틸팅-패드 저어널 베어링을 모델화한 실험장치를 설계 제작하여 선단압력을 포함한 유막내의 압력분포 및 유막두께를 연속적으로 측정함으로써 틸팅-패드 저어널 베어링의 성능에 미치는 선단압력의 영향을 실험적으로 조사하기로 한다.

• Membrane Journal
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• v.23 no.6
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• pp.425-431
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• 2013

This paper has studied the hydrophilizing effect of support on the performance of pressure retarded osmosis (PRO). The hydrophilicity of polyester support has been controlled with cellulose solutions. In order to investigate the effect of hydrophilizing of support, the performance test has been conducted with membrane which compose of active layer and support in absence of support layer. The active layer has been made by casting of cellulose tri-acetate (CTA) 1,4-dioxane solution (13 wt%) and combined with the hydrophilized support. The results show that water fluxes of PRO membranes with hydrophobic or hydrophilized support were measured $0.8L/m^2hr$ and $1.2L/m^2hr$ under $5kgf/cm^2$ pressure, respectively. However, water flux increase did not accord with hydrophilicity of supports treated by cellulose solutions. It is because the porosity and pore size of supports decrease as the cellulose concentration increases. This result confirms that both the hydrophilization of support and the maintenance of membrane porosity are important to enhance the performance of PRO membrane.

• Membrane Journal
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• v.6 no.4
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• pp.250-257
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• 1996

Surface crosslinked chitosan composite membranes were prepared with glutaraldehyde and surfuric acid. Effects of neutralization for complex between chitosan and acetic acid and of water permeability for substrate membranes on pervaporation performance were investigated. For ionically crosskinked membranes, effect of active layer thickness on separation factor of water/ethanol mixture was studied. With increasing the water permeability of the substrate, the membrane showed an increased separation factor, while it maintained a constant permeate flux. Neutralized chitosan composite membranes revealed a decreased separation factor and a constant permeate flux. When the thickness of the active layer increased, an optimum crosslinking time to achieve higher separation factor shifted to a prolonged times.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.2
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• pp.66-73
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• 2021

In the existing study of steel beams with openings, openings are located at a location where the distance to the support point is equal to or greater than the section height. Considering the facilities using the openings in the steel beam, the distance from the opening to the support point may be closer than the height of the beam section. Therefore, research on this is needed. This study is an experimental study to understand the structural performance of beams with openings close to the ends subjected to Cyclic Loading. In addition, in this study, we want to understand the structural performance through experiments on beams with openings reinforced with vertical or horizontal steel plates.

• Membrane Journal
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• v.23 no.3
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• pp.251-256
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• 2013

In this study, acetylated methyl cellulose (AMC) was successfully used as a support layer of thin film composite (TFC) forward osmosis (FO) membrane. A selective polyamide active layer, interfacially polymerized, was coated on top of various substrate layers. The structure and performance of the TFC FO membrane based on the AMC substrate were compared with those of TFC FO membranes with different polymeric support layers. The experimental results showed that the AMC FO membrane performance was better than other FO membranes due to its characteristic morphology and lower back diffusion rate of salts.