• Proceedings of the Korean Institute of Building Construction Conference
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• 2007.11a
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• pp.75-78
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• 2007

The steel slag, a by-product which is produced by refining pig iron during the manufacture of steel, is mainly used as road materials after aging. It is necessary to age steel slag for long time in air because the reaction with water and free-CaO in steel slag could make the expansion of volume. This problem prevents steel slag from being used as aggregate for concrete. However, steel slag used in this study was controled by a air-jet method which rapidly cools substance melted at a high temperature. The rapidly-chilled method would prevent from generation of free-CaO in steel slag. Also, Molten steel slag rapidly-chilled by air in high speed becomes a fine aggregate of nearly spherical shape. This study dealt with the influence of the using rate of rapidly-chilled steel slag and polymer resin on fluidity of polymer concrete, as a results Since RCSS has spherical shape and high density, up to replacement ratio of 100%, increases concrete fluidity under same polymer content and decrease polymer content in order to secure the same fluidity

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.11
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• pp.1390-1397
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• 2004

This study is concerned with the thermal analysis during the cool-down period of 135,000㎥ class GT-96 membrane type LNG carrier under IMO and USCG design condition. During the cool-down period, the spraying rate for the NG cooling decreases as the temperature of NG falls down from -4$0^{\circ}C$ to -l3$0^{\circ}C$, and the spraying rate for the cooling of the insulation wall increases as the temperature gradient of the insulation wall is large. It was confirmed that there existed the largest temperature decrease at the first barrier and the first insulation, which are among the insulation wall, especially in the top side of the insulation wall under IMO and USCG design condition. Also, as the NG temperature distribution is fixed, the outer temperature condition under the design condition has influence on the temperature variation at the insulation. By the 3-D numerical calculation about the cargo tank and the cofferdam during the cool-down period, the temperature variation in hulls and insulations is precisely predicted under IMO and USCG design condition. From the comparison between two conditions; IMO design condition shows more severe temperature gradient than USCG design condition, therefore, it provides the conservative estimation of the BOG.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1346-1351
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• 2004

This study is concerned with the thermal analysis during the cool-down period of 135,000 $m^3$ class GT-96 membrane type LNG carrier under IMO design condition. The cool-down is performed to cool the insulation wall and the natural gas in cargo tank for six hours to avoid the thermal shock at the start of loading of $-163^{\circ}C$ LNG. During the cool-down period, the spraying rate for the NG cooling decreases as the temperature of NG falls clown from $-40^{\circ}C$ to $-130^{\circ}C$ and the spraying rate for the insulation wall cooling increases as the temperature gradient of the insulation wall is large. It was confirmed that there existed the largest temperature decrease at the 1 st barrier and 1st insulation, which are among the insulation wall, especially in the top side of the insulation wall. By the 3-D numerical calculation about the cargo tank and the cofferdam during the cool-down period, the temperature variation in hulls and insulations is precisely predicted.

• Journal of the Korean Magnetics Society
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• v.1 no.1
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• pp.17-24
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• 1991

Laves phases of $NdFe_2$, $Nd{(Fe_{0.5})}_2$, $SmCo_2$ and $Sm{(Fe_{0.5}Co_{0.5})}_2$ stoichiometry were prepared using a rapid solidification technology. Low temperature magnetic properties show ferromagnetic behaviors for the $Nd{(Fe_{0.5}Co_{0.5})}_2$, $SmCo_2$ and $Sm{(Fe_{0.5}Co_{0.5})}_2$Nd(Feo,Coo,) Laves compounds while a sort of spin reorientation has been suggested for the supposed composition of $NdFe_2$ alloy. This rapidly solidified $NdFe_2$ alloy is believed to consist of metastable rhombohedral $NdFe_7$ phase plus fine particles of Nd-rich phase. Some evidence of phase transition from the mixture of unstable $NdFe_7$ compound plus Nd-rich to $Nd_2Fe_{17}$ plus Fe-Nd-O phase was obtained after annealing the $NdFe_2$, alloy. The pseudo-binary Laves compound, $Sm{(Fe_{0.5}Co_{0.5})}_2$ exhibits a high coercivityof 4 kOe at room temperature with Curie temperature of $400^{\circ}C$ while the $Nd{(Fe_{0.5}Co_{0.5})}_2$ compound shows a magnetic moment of $2.8\;{\mu}_B/f.u.$.

• Journal of Sensor Science and Technology
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• v.6 no.6
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• pp.500-507
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• 1997

For fine control of operating temperature of shape memory alloy, we investigated the effect of thermal teratment of shape memory alloy with the impurity kind. The martensitic transformation temperature in a Cu-17.25Zn-15Al and Cu-17.25Zn-15Al-1Ag/Fe was measured using electrical resistivity as a function of quenching temperature. Order-disorder phase transition temperatures in parent phase were measured and kind of transition were distinguised by DSC(differential scanning calorimeter) with heating rate variation. And structual changes were studied with XRD. For the Cu-17.25Zn-15Al shape memory alloy, the order-disorder phase transition temperature, $T_{B2}$ and $T_{L21}$ was 809K and 610K and for the Cu-17.25Zn-15Al-1Ag and Cu-17.25Zn-15Al-1Fe specimen $T_{B2}$ and $T_{L21}$ was 794K and 610K, and 803K and 613K, respectively. In all the specimens, quenching from near $T_{B2}$ leads to an increase in martensitic temperature, whereas quenching from near $T_{L21}$ leads to an decrease in martensitic temperature.

• Proceedings of the Korean Fiber Society Conference
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• 2007.11a
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• pp.375-376
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• 2007

생쪽잎을 다양한 방법으로 건조, 분말화하여 염색하는 경우 전통적인 색소추출방법에서 얻을 수 있는 색상으로 염색됨을 확인하였다. 특히 급냉/동결건조한 분말은 생즙법의 염색효과에, 상온건조한 분말은 생즙법과 침전법의 염색효과에 더 효율적인 방법으로 나타났다.

• 제어로봇시스템학회:학술대회논문집
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• 1989.10a
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• pp.377-382
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• 1989

암모니아 합성을 위한 다단식급냉반응기를 대상으로 물질 및 에너지보존법칙을 적용하여 수식모델을 전개하였다. 실제 4단 반응기의 설계 및 운전자료를 기준으로 하여 정상상태의 다중성을 해석하고 각 촉매층의 체적비와 반응물의 공급유량비에 대한 최적화 연구를 수행한 결과 실제 조업조건하에서 3개의 서로 다른 정상상태가 존재하며 실제 설계 및 조업조건은 최적조건을 다소 완화한 조건에 상당한 것임을 확인하였다.

• The Science & Technology
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• v.32 no.11 s.366
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• pp.30-31
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• 1999

1991년 설립하여 충남대내에 자리잡고 있는 급속응고신소재연구센터는 30여명의 교수와 60여명의 석ㆍ박사과정연구원들이 급속냉각방식을 이용한 첨단신제품개발에 모든 정열을 쏟고 있다. 급속응고란 액상금속을 가스ㆍ액체 또는 원심력을 이용하여 급속도로 냉각시켜서 합금분말이나 비정질금속 등을 제조하는 공정을 말하는데 개발된 기술은 (주)정진화학에 전수하여 현재 생산라인에서 산업화를 위한 시험을 실시하고 있다.

• Proceedings of the Korean Nuclear Society Conference
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• 1995.05a
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• pp.765-770
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• 1995

지체균열전파(DHC)는 중수로 압력관의 수명에 근 영향을 미치는 중요한 현상 중의 하나이다. 본 연구에서는 열처리를 통하여 압력관 재료인 Zr-2,5Nb의 기계적 성질, 집합조직을 변화시켜 각 인자들이 DHC에 미치는 영향을 조사하였다. 그 결과 지체균열전파속도(DHCV)는 항복강도와 경도와 비례한다는 것과 유사한 미세구조와 집합조직을 갖는 Zr-2.5Nb의 경우 항복강도와 Puls의 모델을 이용하여 지체균열전파속도(DHCV)를 예측할 수 있었다. 그리고 secondary cracking이 annealing한 시편들에서는 관찰되었으나 $\beta$열처리 후 급냉한 시편에서는 관찰되지 않았다. 이것의 수소화물 형상의 차이에 의한 것으로 생각된다.

• Electronics and Telecommunications Trends
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• v.16 no.5 s.71
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• pp.167-178
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• 2001

코스닥 및 나스닥 시장의 붕괴로 인한 벤처투자 시장의 급냉이 벤처기업뿐만 아니라 벤처캐피탈업계에도 커다란 악영향을 주고 있다. 벤처투자 시장의 실패와 성공의 엇갈린 결과들이 속출되고 있는 가운데, 벤처기업에 대한 국내 벤처캐피탈의 투자동향, 투자특성 및 향후 IT 투자방향을 분석해 봄으로써 IT 벤처기업 육성을 위한 벤처캐피탈들의 나아가야 할 방향 및 시사점을 제시하고자 한다.