• Journal of the Microelectronics and Packaging Society
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• v.2 no.1
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• pp.49-58
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• 1995

출발물질은 cordierite 유리와 borosilicate/Si3N4 복합분말을 사용하였다. Cordierite 유리조성은 무게비로 17.8MgO-23.1Al2O3-48.1ASiO2-5.0ZnO-1.0B2O3를 선택하였다. Borosilicate/Si3N4복합분말은 sol-gel법으로 a-si3N4 core 분말에 borosilicate 겔을 코팅하여 얻었다. 복합분말과 cordierite 유리 분말을 부피비로 0/100, 12.5/87.5 및 25/75의 조성으로 혼합하여 tape casting 에 의해 green sheet를 제작하였다. 이들 sheet들을 800~100$0^{\circ}C$에서 2시간 소성하여 얻은 시편을 SEM, XRD, 밀도, 유전상수 등을 측정하여 저 유전율의 저온 소성 기판재료를 제조하기 위한 조건들을 검토하였다.

• Journal of the Society of Naval Architects of Korea
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• v.49 no.3
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• pp.227-231
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• 2012

In this study, a plastic hardening constitutive equation for steels of polar class vessels at low temperature is proposed. The equation was derived using the experimental data obtained from tensile tests at room and low temperatures. Tensile tests at low temperature are both costly and time consuming because an expensive cold chamber is necessary and it takes too much time to cool down a specimen to set temperature. Using the proposed plastic hardening constitutive equation the plastic hardening characteristics of steels for polar class vessels at low temperature can be easily predicted from the tensile test results at room temperature.

• Applied Biological Chemistry
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• v.34 no.2
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• pp.162-167
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• 1991

In an attempt to explore the mechanistic aspects of chilling injury in plants and their defensive measures against the low temperature stress, the time sequential measurements of pyruvate, superoxide radicals$(O_{\overline{2}})$ and antioxygenic enzymes during whole period of injury-inducing treatment were performed using mostly rice seedlings. Pyruvate was substantialy accumulated in leaf tissues during the exposure period to $5^{\circ}C$ of the seedlings ; the relative extent of the accumulation was increased with increasing time of the cold treatment. When the cold-treated plants were translocated to ambient temperature$({\sim}25^{\circ}C)$, the accumulation started to dissipate, concomitantly accompaning a remarkable increase in the $O_{\overline{2}}$ level of tissues. Superoxide dismutase(SOD) and catalase were also activated during post-chilling period, although they showed a considerable lag time for activation. In contrast, glutathione peroxidase, another antioxygenic enzyme in cells, was not activated at all by preceding cold treatment of plants. The uptake of exogenous $O_{\overline{2}}$ by the roots of rice seedlings resulted in increase in the activities of SOD and catalase in root tissues. The supply of $H_2O_2$ to plan st brought about the activation of catalase in situ, while failing to exert any effect on the activation state of glutathione peroxidase. The results obtained in this work suggest that pyruvate accumulation in cells is the direct cause of the overproduction of $O_{\overline{2}}$ and thereby other toxic activated oxygen species, and that SOD and catalase may play a crucial role in the protection of plant cells against active oxygen-mediated chilling injury.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.271-271
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• 2007

LTCC 소재는 glass/ceramic composite로 구성된다. LTCC 소재에 embedding 되는 고유전율 소재 또한 이와 같은 소재설계를 통하여 무수축 접합이 가능할 것으로 판단된다. 그러나 이에 대한 연구결과가 보고된바 없고 몇몇 $Al_2O_3$의 infiltration에 대한 무수축 소성 관련 선행 연구를 바탕으로 고유전율 소재인 $BaTiO_3$의 무수축 소성이 연구되는 것이 필요한 시점이다. 따라서 본 연구는 저온에서의 glass infiltration에 의한 무수축 $BaTiO_3$ layer의 저온소성특성 및 유전특성을 평가하였다. 실험결과 $785^{\circ}C$에서 glass의 충분한 침투가 확인되며 결정구조에서는 glass/$BaTiO_3$ composite이 형성되었다. 무수축 접합 layer의 소성조건과 glass 두께 변화에 따른 유전특성 및 layer의 결정구조를 비교평가 하였다.

• Proceedings of the Materials Research Society of Korea Conference
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• 1999.11a
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• pp.170-170
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• 1999

• Information Display
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• v.2 no.6
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• pp.52-62
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• 2001

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2001.11a
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• pp.54-55
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• 2001

• 대한치과보철학회:학술대회논문집
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• 2004.11a
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• pp.84-84
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• 2004

• Economic and Environmental Geology
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• v.45 no.2
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• pp.157-167
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• 2012

This study aimed to interpret the provenance and firing temperature of pottery from Chipyeongdong site in Gwangju, Korea though mineralogical and geochemical methods and also investigated the post-depositional alteration of pottery in burial environments. It is also presumed that they were made of soils near the site because they have similar mineralogical composition and same geochemical evolution path. Based on the results of mineralogical analysis, the pottery samples are largely divided into 2 groups; $700^{\circ}C$ to $1,000^{\circ}C$ and 1,000 to $1,100^{\circ}C$. At some pottery fired at over $1,000^{\circ}C$, it is thought that the refinement of raw materials were processed to remove macrocrystalline fragments. However, it was found that phosphate in soil environments formed amorphous aggregates with Al and Fe within the pores and voids on pottery fired at the low temperature. It indicates the contamination of pottery after burial.

• Korean Journal of Environmental Agriculture
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• v.17 no.3
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• pp.200-204
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• 1998

Physical and chemical properties of artificial soil produced by firing process were analyzed and compared with normal dry field soil and soil quality standards. Material used for production was water and wastewater treatment sludge, chabizite, and lime. The mixed material was thermally treated in the firing kiln at about $300^{\circ}C$ and $1,000^{\circ}C$, respectively, as per designed process. General properties of the artificial soil were classified as sand by unified soil classification method and similar to the dry-field soil, and even soil conditioning effect were expected when it is mixed properly with normal soil. The artificial soil is high in pH and permeability compared to the dry-field soil. Heavy metal concentrations of the artificial soil met the soil quality standards for the farmland. Overall, the artificial soil was thought to be an appropriate soil which can be returned safely to the nature without significant adverse effect. The cost for the artificial soil production process needs to be lowered for practical application as a sludge treatment, therefore, commercializing of the artificial soil is under review.