• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2003년도 international symposium on advanced powder metallurgy
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• pp.39-40
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• 2003

1) Using a developed high-frequency induction heated sintering method, the rapid densification of WC-Co hard materials was accomplished using ultra fine powders with 260 nm size within 1 minute. 2) The relative density of the composite was 99.5% for the applide pressure of 60MPa and the induced current for 90% output of total capacity. 3) The grain size of WC-Co hard materials is about 260nm and the average thickness of the binder phase determined is about 11nm. The fracture toughness and the hardness of this work 12 $MPa{\cdot}nm^2$, respectively. 4) Using pressureless sintering, we produced dense WC-Co hard materials with a relative density of 97% without applying pressure.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1988년도 추계학술대회 논문집
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• pp.36-40
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• 1988

High TC Y-Ba-Cu-O Superconductors were fabricated by sintering, sinter+HIP encapsulation. Specimens were sintered at 920$^{\circ}C$∼960$^{\circ}C$. A part of sintered specimens were treated by HIP, and HIP conditions were 150 MPa, 880$^{\circ}C$, 30min under the Ar atmosphere. The relative density of HIP specimens was increased 5∼8% in comparison with sintered one(90∼93% relative density). X-ray analysis represented the orthorhobic-tetragonal phase transition with annealing condition. Tc measurements showed a sharp drp within 3$^{\circ}C$, 91K onset and 89K offset. Transport current density(Jc) of sintered specimens showed typically∼159A/㎤ but that of sinter+HIP encapsulation was decreased to∼89A/㎤ because of insufficient oxygen diffusion, Hardness(H) and Toughness(Kc) were increased to 38GPa; and 2.9 MPam$\^$$\frac{1}{2}$/, respectively.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2015년도 춘계 학술논문 발표대회
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• pp.82-83
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• 2015

Recently, the research on steel fiber reinforced concrete has been actively conducted to compensate the defect of brittle fracture of concrete and to enhance toughness. Therefore, the effect of the mixture rate of straight steel fiber on flexural behavior of high strength steel fiber reinforced concrete was evaluated in this research. As a result, when 2% of steel fiber was mixed with concrete volume ratio, it showed the best flexural capacity.

• Steel and Composite Structures
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• 제18권5호
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• pp.1161-1176
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• 2015

The connection between a column and a beam is of particular importance to ensure the safety of civil engineering structures, such as high-rise buildings and bridges. While the connector must bear sufficient force for load transmission, increase of its ductility, toughness and damping may greatly enhance the overall safety of the structures. In this work, a composite beam-column connector is proposed and analyzed with the finite element method, including effects of elasticity, linear viscoelasticity, plasticity, as well as geometric nonlinearity. The composite connector consists of three parts: (1) soft steel; (2) polymer; and (3) conventional steel to be connected to beam and column. It is found that even in the linear range, the energy dissipation capacity of the composite connector is largely enhanced by the polymer material. Since the soft steel exhibits low yield stress and high ductility, hence under large deformation the soft steel has the plastic deformation to give rise to unique energy dissipation. With suitable geometric design, the connector may be tuned to exhibit different strengths and energy dissipation capabilities for real-world applications.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1996년도 춘계학술대회 논문집
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• pp.108-113
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• 1996

Conventionally, grinding of stainless steel, aluminium alloy, copper alloy, and titanum alloy is difficult due to the mechanical properties such as low hardness, high toughness which result in the loading of wheel and the poor surface finish. In order to grind this sort of materials easily, discontinuous grinding wheel with multi-porous grooves was newly developed. The multi-porous grooves were formed during wheel production. This discontinuous grinding wheel drastically increases the grinding performance. It is desirable to use the discontinuous grinding wheel when grinding materials with high efficiency and accuracy which is impossible by conventional wheels. In this paper, the construction and manufacturing method of grinding wheel with multi-porous grooves are explained. The grinding charateristics of discontinuous grinding wheel was also illustrated.

• 대한기계학회논문집
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• 제12권6호
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• pp.1290-1295
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• 1988

본 연구에서는 공구마멸에 대한 정량적인 해석을 바탕으로 현대 산업사회의 주요소재인 강(steel)에 대한 최적 공구재를 선정하는 방법을 제시하므로서 앞으로의 공구재 개발에 대한 이론적인 접근을 시도하였다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 추계 학술발표회 제16권2호
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• pp.341-344
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• 2004

In the present research, slump, modulus of rupture (MOR) and flexural toughness $(I_{30})$ of high performance hybrid fiber reinforced concrete (HPHFRC) mixed with micro-fiber (carbon fiber) and macro-fiber (steel fiber) and replaced with silica fume were assessed with the analysis of variance (ANOVA). Steel fiber was a considerable significant factor in aspect of the response values of MOR and boo Based on the significance of factors related to response values from ANOVA, following assessments were available; Slump decrease: carbon fiber >> steel fiber > silica fume; MOR: steel fiber > silica fume > carbon fiber; $I_{30}$: steel fiber > carbon fiber > silica fume. Steel fiber $1.0\%$, carbon fiber $0.25\%$ and silica fume $5.0\%$, and Steel fiber $1.0\%$, carbon fiber $0.25\%$ and silica fume $2.5\%$ were obtained as the most optimum mixture.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 하계학술대회 논문집
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• pp.136-139
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• 2000

Epoxy materials are used as insulation material for electric power cables. In the case of a flow of excess current due to the temperature difference which occurs between the heat of the conductor and the atmosphere, heat degrades connection point of the cables. Also, the mechanical stress, which occurs due to the thermal expansion coefficient of cable connection electrode system and epoxy insulation materials along with the gap between thermal conduction based on the extra high voltage of transmitted voltage, increases possibility of cracks to occur. The relationship between mechanical stress and electrical breakdown mechanism is verified for the epoxy materials such as high toughness epoxy materials, which comes to be used contemporarily, and for the breakdown mechanism of epoxy materials on the multi-stresses (mechanical and electrical) due to the variation of the temperature.

• 한국해양공학회지
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• 제11권3호
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• pp.39-47
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• 1997

Recently developed TMCP steels, which were manufactured by controlled rolling followed by accelerated cooling process, were examined to study their characteristics and weldability. Accelerated cooling type TMCP steel's hardness test result exhibited high value on weld zone. On the contrary, base metal and HAZ exhibited comparatively the similar value. On this experiment result Softening of HAZ is not occurred. in the-heat affected zone, grain size repression be caused by chemical composition properties which a small quantity Al-Ti-B-N. Changing stress ratio near-threshold fatigue crack propagation experiments were carried out. According to this result, crack propagation velocity of the HAZ exhibited slower than the base metal and near-threshold value had increased at the HAZ. Finally accelerated cooling type TMCP steels were exhibited excellent mechanical properties in both strength and toughness.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2022년도 가을 학술논문 발표대회
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• pp.61-62
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• 2022

Carbon nanotubes were used to secure high strength, high durability, and fracture toughness of cementitous composites.In this study, carbon nanotube dispersion solutions were prepared using commercial superplasticizers, such as polycarboxylate-ester and sodium naphthalene sulfonate with tip sonication. The solutions were used to prepare cement paste with MWCNT and The mechanical properties of the cement paste composite with MWCNT solutions were evaluated.