• Tribology and Lubricants
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• 제21권5호
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• pp.216-220
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• 2005

The sliding wear behaviors of three different compositions of novel low temperature degradation-free zirconia/alumina (LTD-free Z/A) composites were examined in a ceramic-ceramic contact pair. The wear tests were performed by using a pin-on-disk type wear tester in a linear reciprocal sliding motion with a line contact in both dry and bovine serum lubricated conditions at room temperature. From the results of dry sliding wear tests, Z/A#1((5.3Y, 4.6Nb)-TZP/80 $vol\%Al_2O_3$) showed the best wear resistance among three kinds of LTD-free Z/A composites. For the bovine serum lubricated sliding wear tests, wear was too little to be measured for all kinds of Z/A composites. These novel LTD-free Z/A composites having excellent wear resistance demonstrated a potential as the alternative materials for the ceramic-ceramic contact pairs of femoral head and acetabular liner in total hip replacement.

• 한국해양공학회지
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• 제10권2호
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• pp.106-119
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• 1996

The ceramic has various high mechanical properties such as heat, abrasion, corrosion resistance and high temperature strength compared with metal. It also has low speciffic weight, low thermal expansibillity, low thermal conductivity. However, it could not be used as structural material since it is brittle and difficult for the machining. Therefore, there have been many researches to attempt to join ceramic with metal which is full of ductillity in order to compensate the weakness of ceramic.The problem is that residual stress develops around the joint area while the ceramic/metal joint material is cooled from high joining temperature to room temperature due to remarkable difference of thermal expansion coefficients between ceramic and metal. Especially, the residual stress at both edges of the specimen reduces the strngth of joint to a large amount by forming a singular stress field. In this study, two dimensional finite element method is attempted for the thermal elastic analysis. The joint residual stress of ceramic/metal developed in the cooling process is investigated and the change of joint residual stress resulted from the repetitive heat cycle is also examined. In addition, it is attempted to clarify the joint stress distribution of the case of tensile load and of the case of superposition of residual stress and actual loading stress.

• 한국전기전자재료학회논문지
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• 제24권3호
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• pp.188-193
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• 2011

The osseointegration of dental implant is influenced by many factors such as surface geometry, loading and the amount of bone. Thus, stability of the dental implant should be checked periodically. In order to test the stability of dental implant by using resonance frequency analysis, we designed a structure of transducers and fabricated a piezoelectric devices. Using finite element analysis, the thickness and length of piezoelectric device and transducers were tailorized and the optimized frequency of 10 kHz was obtained. The resonance frequency from simulation analysis and evaluation was estimated to be similar as 10 kHz. The osseointegration was further enhanced with increasing frequency from the evaluation result of the finite element analysis.

• 마이크로전자및패키징학회지
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• 제26권4호
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• pp.89-94
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• 2019

전력저장용 전기에너지 저장장치의 일종인 NaS 전지 단위 셀을 개발함에 있어서 알파-알루미나 절연세라믹 캡과 베타-알루미나 전해질 튜브 간의 세라믹-세라믹 상호 접합을 위하여 글라스 기반의 실링소재가 필요하다. 본고에서는 이 세라믹-세라믹 접합용 글라스 실링 페이스트를 제조함에 있어서, 열간 칭법에 의한 글라스 프릿 제조와 상분석, 분말입도 분석 및 글라스 조성에 따른 열팽창계수 변화 및 표면거칠기를 분석하였다. 또한 글라스 실란트의 접합력 평가를 위해 종래 솔더 볼 조인트의 접합력 평가용 분석장비인 Dage bond tester를 이용하여 세라믹-세라믹 컴포넌트의 작은 접합면에 대한 접합력 측정 방법을 제안하였다.

• 한국재료학회지
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• 제28권2호
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• pp.95-100
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• 2018

In this study, $ZrO_2$ ceramic ink was formulated for additive manufacturing three dimensional structure using dispenser printing technique. Ceramic ink with various $ZrO_2$ loading (30, 40, 50vol%) was prepared to evaluate their rheological properties and printability. High $ZrO_2$ loading $ZrO_2$ ceramic ink showed higher elastic modulus and improved shape retention, when the ceramic ink was printed and sintered at $1450^{\circ}C$ for 1h. Microstructural analysis of printed $ZrO_2$ objective indicated that high $ZrO_2$ loading objective showed lower porosity and smaller pore size.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.427-430
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• 2001

The degradation characteristics versus MgO Additive for the ZnO ceramic devices fabricated by the standard ceramic techniques is investigated in this study. It were made these devices be basic Matsuoka's composition. Especially, MgO were added to analyze the degradation characteristics and sintered in air at 1300$^{\circ}C$. The conditions of DC degradation test were 115${\pm}$2$^{\circ}C$ for 12h. Using XRD and SEM, the phase and microstructure of samples were analyzed respectively. The elemental analysis in the microstructures was used by EDS, E-J analysis was used to determine ${\alpha}$ . Frequency analysis was accomplished to understand the relationship between R$\sub$g/ and $R_{b}$ with the electric stress at the equivalent circuit.

• 한국전기전자재료학회논문지
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• 제15권5호
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• pp.398-405
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• 2002

The degradation characteristics of MgO additive for the ZnO ceramic devices fabricated by the standard ceramic techniques are investigated in this study. These devices were made from basic Matsuoka's composition. Especially, MgO was added to analyze the degradation characteristics and devices were sintered in air at $1200^{\circ}C$. The conditions of DC degradation test were $115\pm2^{\circ}C$ for 12h. Using XRD and SEM, the phase and microstructure of samples were analyzed, respectively. The elemental analysis in the microstructures was performed by EDS, E-J analysis was used to determine $\alpha$. Frequency analysis was accomplished to understand the relationship between $R_G$ and $R_B$ with the electric stress at the equivalent circuit.

• Structural Engineering and Mechanics
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• 제84권6호
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• pp.723-731
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• 2022

Functionally graded materials (FGMs) have been spotlighted as an advanced composite material, accordingly the intensive studies have focused on FGMs to examine their mechanical behaviors. Among them is thermal buckling which has been a challenging subject, because its behavior is connected directly to the safety of structural system. In this context, this paper presents the numerical analysis of thermal buckling of metal-ceramic functionally graded (FG) plates. For an accurate and effective buckling analysis, a new numerical method is developed by making use of (1,1,0) hierarchical model and 2-D natural element method (NEM). Based on 3-D elasticity theory, the displacement field is expressed by a product of 1-D assumed thickness monomials and 2-D in-plane functions which are approximated by NEM. The numerical method is compared with the reference solutions through the benchmark test, from which its numerical accuracy has been verified. Using the developed numerical method, the critical buckling temperatures of metal-ceramic FG plates are parametrically investigated with respect to the major design parameters.

• 한국세라믹학회지
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• 제13권2호
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• pp.31-38
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• 1976

Korean tremoitic talc, wollastonite and clay have been used to develop a wall tile body to appropriate to the fast firing process. Some of ceramic properties of the raw materials were investigated by X-ray diffraction, thermal analysis and chemical analysis. The body compositions were formulated from the range of 35~75% tremolitic talc, 0~30% wollastonite and 25~35% plastic clay. Thermal gravity analysis and thermal expansion were tested for each of unfired bodies to study the correlation between thermal dehydration and linear shrinkage during the firing procedure. Linear shrinkage and water absorption of the fired bodies at the various temperature were taken as a measures for determining the proper firing range of the bodies. Increasing the content of wollastonite and firing temperature, the thermal expansion of the fired body showed the gradual decrease, and the thermal expansion curves showed a tendency to straighten. These observations may be resulted from the fact that the amounts of diopside and anorthite formed were gradually increased and those of quartz relatively decreased. The optimum compositions of the wall tile bodies for fast firing are 30% clay, 10~20% wollastonite and 50~60% tremolitic talc.

• 한국결정성장학회지
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• 제16권3호
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• pp.127-131
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• 2006

세라믹소지에 발생하는 온도별 백화생성기구를 백화를 형성하는 양이온과 음이온을 분석하여 규명하였다. 백화가 발생된 세라믹 소지의 표면을 SEM과 EDS 분석을 하여 백화의 주 성분은 Ca와 S임을 확인하였다. 세라믹소지를 pH 7과 pH 10에서 각기 습식혼합 하였으며, 이때 여과된 액을 ICP와 IC 분석을 하여, 양이온 및 음이온 농도분석을 하였다. pH 7에서 제조된 세라믹 소지의 Ca 이온농도는 pH 10에서 제조된 세라믹소지의 Ca 이온농도의 8배 값을 보였으며, pH 10에서 제조된 세라믹소지는 $1100^{\circ}C$ 이상으로 소결된 소지에서도 백화가 발견되지 않았다.