• 자원리싸이클링
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• 제18권6호
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• pp.46-53
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• 2009

석재 가공 시 발생되는 석분은 산업폐기물로 되어있다. 현재 이 석분은 지하에 매립하거나 지상에 야적되어 방치되고 있어 폐기물로 처리하는 데 많은 비용이 요구되고 있고, 토질과 지하수 등의 환경오염의 원인이 되고 있다. 또한 콘크리트의 주재료인 골재의 공급이 부족한 현실을 고려하여 본 연구에서는 폐석분을 콘크리트 혼화재료로 재활용할 수 있는 가능성을 연구하고자 한다. 석분함유량에 대한 시멘트비를 조정한 결과, $20{\sim}30\;N/mm^2$의 콘크리트의 압축강도가 나타났고 이는 석분의 함유에 따라 압축강도가 감소되지 않음을 알 수 있었다. 석재 가공 시 발생되는 석분을 콘크리트 혼화재료로 재순환하여 사용하여도 콘크리트의 압축강도에는 전혀 문제가 없음을 알 수 있었다.

• 대한금속재료학회지
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• 제48권7호
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• pp.667-673
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• 2010

Copper filling into TSV (through-silicon-via) and reduction of the filling time for the three dimensional chip stacking were investigated in this study. A Si wafer with straight vias - $30\;{\mu}m$ in diameter and $60\;{\mu}m$ in depth with $200\;{\mu}m$ pitch - where the vias were drilled by DRIE (Deep Reactive Ion Etching) process, was prepared as a substrate. $SiO_2$, Ti and Au layers were coated as functional layers on the via wall. In order to reduce the time required complete the Cu filling into the TSV, the PPR (periodic pulse reverse) wave current was applied to the cathode of a Si chip during electroplating, and the PR (pulse-reverse) wave current was also applied for a comparison. The experimental results showed 100% filling rate into the TSV in one hour was achieved by the PPR electroplating process. At the interface between the Cu filling and Ti/ Au functional layers, no defect, such as a void, was found. Meanwhile, the electroplating by the PR current showed maximum 43% filling ratio into the TSV in an hour. The applied PPR wave form was confirmed to be effective to fill the TSV in a short time.

• 한국기계가공학회지
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• 제20권5호
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• pp.103-110
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• 2021

The mounting performance of the GFRP(Glass fiber Reinforced Plastic) beam and the mechanical mounting of the steel bracket was studied to be mounted as a GFRP impact beam on the side door of the passenger car. Moreover, an open-hole tensile test was performed to evaluate breakage tendency based on GFRP stacking conditions. Furthermore, the tightening strength of rivets and bolts was compared using the single lap-shear tension test for the GFRP stacking pattern. Additionally, the GFRP beam and bracket mounting features were designed; moreover, the prototype and bracket were assembled. Additionally, the bracket mounting bending test and the door assembly static bending test were performed to verify the stability of the bracket mounting. In the bracket fastening bending test, no breakage occurred in the connection part between the GFRP beam and the bracket, and it showed 67% (24.4 kN) improved performance compared to steel. In the static bending test of the door assembly, the initial average reaction force increased by 25% compared to the steel, and the performance of all FMVSS-214 regulations was satisfied. The replacement of GFRP impact beams resulted in a 30% weight reduction

• 대한금속재료학회지
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• 제49권5호
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• pp.388-394
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• 2011

High speed copper filling into TSV (through-silicon-via) for three dimensional stacking of Si chips was investigated. For this study, a tapered via was prepared on a Si wafer by the DRIE (deep reactive ion etching) process. The via had a diameter of 37${\mu}m$ at the via opening, and 32${\mu}m$ at the via bottom, respectively and a depth of 70${\mu}m$. $SiO_2$, Ti, and Au layers were coated as functional layers on the via wall. In order to increase the filling ratio of Cu into the via, a PPR (periodic pulse reverse) wave current was applied to the Si chip during electroplating, and a PR (pulse reverse) wave current was applied for comparison. After Cu filling, the cross sections of the vias was observed by FE-SEM (field emission scanning electron microscopy). The experimental results show that the tapered via was filled to 100% at -5.85 mA/$cm^2$ for 60 min of plating by PPR wave current. The filling ratio into the tapered via by the PPR current was 2.5 times higher than that of a straight via by PR current. The tapered via by the PPR electroplating process was confirmed to be effective to fill the TSV in a short time.

• 한국기계가공학회지
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• 제21권5호
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• pp.1-8
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• 2022

Fused deposition modeling (FDM), based on stacking a continuous filament of polymer or composite materials, is well matured and is thus widely used in additive manufacturing technology. To advance FDM-based 3D printing technology, the mechanical properties of additively manufactured composite materials must be improved. In this study, we proposed a novel FDM 3D printing process using metal wire-polymer composites, enabling enhanced mechanical properties. In addition, we developed a new type FDM filament of copper wire wrapped in nylon material for stable 3D printing without thermal damage during the printing process. After FDM printing of the copper wire-nylon composite filament, we conducted a tensile test to investigate the mechanical behavior of the printed composite materials. The experimental results confirmed that the tensile strength of the 3D-printed metal wire-polymer composites was higher than that of the conventional single polymer material. Thus, we expect that the FDM printing process developed in this study may be promising for high-load-bearing applications.

• 한국포장학회지
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• 제8권2호
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• pp.32-38
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• 2002

수송용 수산물 포장상자의 물류적성과 위생성을 향상시키기 위하여 폴리에틸렌-폴리프로필렌 공중합체를 소재로 한 표준규격의 플라스틱 어상자를 개발하였다. Two color type 과 bar type이 용도에 따라 개발되었으며 적재효율을 기존보다 27.6% 향상시키고 위생성과 편리성을 동시에 만족시킴으로써 수산물 물류의 현대화에 크게 기여할 것이다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.182-182
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• 2009

The effect of Re-oxidation on the PTCR properties of Sm-doped barium titanate ceramics was investigated by means of impedance spectroscopy. Electrical properties such as resistance vs. temperature, I-V curve were measured and microstructure was observed with SEM photography. Sample was fabricated with thick film process such as tape casting of green sheet, screen printing of electrode pattern, stacking, firing in reduced atmosphere and re-oxidation, etc. As the temperature of re-oxidation increases, resistance jump as a function of temperature enhances but resistance at room temperature increases. These behavior of resistance as a function of temperature, dependent on the re-oxidation condition, is analyzed with Cole-Cole impedance plot and is shown to be related with the degree of oxidation of grain boundary regardless of grain core during re-oxidation process of sample.

• 한국초전도ㆍ저온공학회논문지
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• 제6권1호
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• pp.1-5
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• 2004

Long length of Bi-2223/Ag superconducting wives were fabricated by stacking and drawing process with advanced heat-treatment schedules. Intermediate annealing was carried out to increase the homogeneity and uniformity of the superconducting filaments embedded in the silver matrix. Phase modification from tetragonal to orthorhombic Bi-2212 by pre heat treatment(PHT) was executed to improve the texture and phase transformation of Bi-2223. Drawing stress was measured to predict the sausaging and stress limit. Rolling Parameters such as thickness. width and winding tension were investigated to roll the tape with uniformity. 1 km length of Bi-2223/Ag superconducting wires were fabricated without any breakage. Critical current (Je) of 270 m length of superconducting tapes was measured over than $70 A/cm^2$ continuously after final sintering.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.54-57
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• 2003

Since passenger cars require five wheels including a spare, the weight reduction of wheels without sacrificing performance is important. Recently, the structured components of cars made of steel are replaced by composites. plastics and other nonmetallic materials such as aluminum and magnesium for weight reduction. From these new tried materials are most promising due to their high specific stiffness and specific strength. The composites manufactured by resin transfer molding (RTM) process has not only low cost for the manufacturing but also reduces the lead time and development because the molds for RTM is easy to manufacture. In this work, composite wheels for passenger cars were designed and manufactured by RTM process. Since surface quality of wheels is important for passenger cars, the optimal stacking sequence for composite wheels was selected considering surface quality and mechanical properties. Also, the manufacturing method for the composite mold was depicted.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2003년도 추계학술대회 논문집
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• pp.96-98
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• 2003

Many of research efforts have been focused on the improvement of critical current density Jc of silver-sheathed Bi-2223 tapes for practical applications of material. Bi-2223 superconducting wires with 55 filaments were fabricated by stacking, drawing process with different heat-treatment histories. After rolling process, Bi-2223 tapes were heat-treatment at 780~826$^{\circ}C$ with variable mass flow rate of mixed gas. In this study, the effect of changes in the variable mass flow rate of mixed gas during the heat treatment of Bi-2223/Ag tapes has been investigated. Distinct differences were observed in the Bi-2223 phase and critical current as flow rate of mixed gas. We could achieve proper conditions of mass flow rate of mixed gas for Ag-alloy clad Bi-2223 superconducting tapes.