• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2002.05a
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• pp.189-192
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• 2002

Sn-Cu-Ni계 솔더 합금에 소량의 Bi와 In을 첨가하여 새로운 무연솔더 합금 개발을 진행하였다. Sn-0.7%(Cu+Ni)에 2~5% Bi, 2~10% In을 첨가하여 각각의 열적, 전기적, 기계적 특성을 평가하였다. 솔더합금의 융점은 200~222$^{\circ}C$, 응고온도범위는 20~37$^{\circ}C$로 중.고온계 솔더로서 적용이 가능하다. 실험 조성별 솔더 합금중 실용적, 경제적인 면을 고려하여 Sn-0.7%(Cu+Ni)-3.5%Bi-2%In이 최적의 합금조성으로 판단된다. 이 합금은 융점이 22$0^{\circ}C$정도이며 응고범위는 $25^{\circ}C$, 강도 면에서는 타 합금에 비해 상당히 우수한 값을 나타내었으며 연신율은 비교적 낮은 값을 나타내었다. 다른 기계적, 전기적 특성은 타 솔더 합금과 유사하거나 우수한 편이었으며 젖음특성도 양호하였다.

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.3
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• pp.603-608
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• 2004

Traditional Jeju tofu with a hard texture was manufactured by traditional method with a compounded coagulant. The processing condition for industrial production was optimized by determining soaking of soybean, extraction and heat treatment of soymilk as well as concentration and composition of coagulant. Maximum yield of soymilk was obtained by grinding one part of soaked soybean with eight parts of water, and the soluble solid of soymilk was about 8$^{\circ}$Brix. The free thiol group in soymilk was maximally exposed by heating at 10$0^{\circ}C$ for 2 min. A vacuum cooker for heating soymilk was effective for the improvement of yield and texture properties of tofu. The hardness of traditional Jeju tofu was obtained by increasing pressing time and drying by a fan instead of soaking in cold water. Optimization of a traditional tofu production resulted in the increase of total yield and improvement of quality control. Texture of traditional Jeju tofu prepared in industrial production scale was analyzed by instrumental analysis and sensory evaluation. Traditional Jeju tofu showed higher score in the hardness, roasting taste and overall preference compared with a commercial tofu, showing significant difference in 5% significant level..

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.7
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• pp.653-658
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• 2016

High pressure components of a gas turbine engine are generally made of nickel-base superalloys, using precision casting process due to complicated geometries with intricate channels and cooling holes. Turbine components manufactured from directionally solidified and single crystal materials have columnar grains; however, it is found that the crystals do not grow in its preferred direction, although the orientation can be controlled. This anisotropy can lead to the variations of elastic and Hill's parameters in constitutive equations, and they alter stress distributions and the low cycle fatigue life. We aims to evaluate the effects of perturbed crystal orientations on the structural integrity of a directionally solidified nozzle using low cycle fatigue life. We also attempt to show the necessity for the control of allowed manufacturing errors and stochastic analysis. Our approaches included conjugate heat transfer and structural analysis, along with low cycle fatigue life assessment.

• Journal of Korea Foundry Society
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• v.42 no.2
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• pp.77-82
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• 2022

Initial solidification condition during directional solidification of superalloy CM247LC was controlled with various cooling methods such as insertion of alumina disc or Ni foil or inoculant, and direct pouring of melt onto chill plate. Rapid cooling with direct pouring of melt onto chill plate resulted in generation of many fine grains and precipitation of fine γ' particles, as well as small dendrite arm spacing. Tensile properties of directionally solidified superalloy CM247LC were closely related to microstructure which was governed by initial solidification conditions. Directionally solidified CM247LC with small dendrite arm spacing and fine precipitates showed good tensile properties.

• Journal of Korea Foundry Society
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• v.28 no.5
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• pp.217-220
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• 2008

본 연구에서는 유한요소법을 적용한 수치해석을 이용하여 타이어 제조용 금형을 생산하기 위해 사용되는 주조재의 열적 특성에 관하여 조사해 보았다. 고 품질의 정밀도가 좋은 타이어를 제조하기 위해, 일반적으로 타이어 제조용 금형의 주조재로 많이 사용되고 있는 알루미늄 합금과 비교 대상으로 연강을 선정하여 각각의 주조재에 대한 응고과정에서의 온도분포와 응력분포 결과를 수치적으로 계산해 보고 결과를 예측해 보았다. 수치해석을 통한 결과에서, 알루미늄 합금을 사용한 금형의 냉각과정 동안의 온도분포는 연강에 비해 보다 더 안정적으로 나타나는 것을 확인하였으며, 응력분포 결과 또한 알루미늄 합금 금형이 연강에 비해 정밀도를 향상시키고 좋은 품질의 제품을 얻는 데 보다 나은 것으로 나타났다. 그리고 금형의 온도분포와 응력분포는 금형의 냉각과정 동안 주조재의 초기 냉각온도에 의해 크게 영향을 받는 것으로 사료된다. 마지막으로, 이러한 수치해석에 의한 금형의 열적 특성 예측은 향후 고품질, 고정밀도의 금형 생산을 위한 예비성능평가 방법과 경제적 측면에서 매우 유용하게 활용할 수 있을 것으로 보인다.

• Korean Journal of Food Science and Technology
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• v.10 no.2
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• pp.231-236
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• 1978

It has been investigated that preparation of cheese-like product from defatted soybean milk and changes during 6 weeks' ripening. Obtained results were as follows: 1. Defatted soybean milk was fermented at $37^{\circ}C$ for 4 hours with Streptococcus lactis YUFE L-4 without addition of any other carbon sources. 2. Optimum concentration of coagulant such as $MgCl_2{\cdot}6H_2O$ and $CaCl_2$ were 0.0125M and 0.0375M, respectively. 3. Coagulating time for 30 minutes was sufficient to make curd. 4. Optimal reaction temperature for coagulating were $50^{\circ}C$. 5. After 6 weeks' ripening, moisture content was approximately $62{\sim}63%$. Water and 10%-TCA soluble nitrogen contents of soybean cheese with Asp. saitoi protease were higher than those of Mucor rennet. Water soluble nitrogen content of Asp. saitoi protease cheese was 50.5% and 10%-TCA soluble nitrogen was 27.5%.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.12 no.3
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• pp.137-141
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• 1979

A study on the processing of soy curd powder with soybean milk and kril autolasate has been carried out to prolong tile self life and to improve the taste and colour of soy curd. The soy curd was manufactured by coagulation of the soybean milk prepared from soybean through a series of processes of soaking, grinding, heating at $500^{\circ}C$ for 5 minutes and filtration. Ten hours was reasonable as the soaking time of the soybean for the high yield of soybean milk. The use of $3\%$ $glucono-\delta-lactone$ to the weight of the raw soybean showed the best coagulation of the soybean milk at $90^{\circ}C$ in relation to the yield and content of crude protein of the soy curd. The soy curd powder prepared by spray drying of soyben milk could be coagulated at $90^{\circ}C$ by the addition of $glucono-\delta-lactone$ after suspending in water. The powder manufactured by spray drying of the mixture of soybean milk and drill autolasate could also be coagulated under the same conditions to produce the soft soy curd. Another powder prepared by spray drying of the mixture of soybean milk, krill autolysate and $glucono-\delta-lactone$ could be coagulated by standing at room temperature after 2 minutes boiling.

• Journal of the Korean Society of Safety
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• v.14 no.1
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• pp.208-215
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• 1999

The creep behavior of a rapidly solidified and consolidated Al-9.45wt%Fe-4.45wt%Cr alloy were investigated in the stress range 40 to 115 MPa and temperature range 300(0.53Tm) to 441$^{\circ}C$(0.66Tm). It is of use to available aerospace and automobile industries for the improved performance of materials used at high temperature. Because Al alloys with improved creep resistance offer the potential for lower weight and reduced costs in aerospace and automobile components (e.g., structural members and engine parts) through the replacement of heavier and more costly materials, the safety in use at high temperature is good. The alloy is characterized by high stress exponents and activation energies for creep, which are greatly dependent on the stress and temperature. Because the creep stress is seen to cause a strongly significant enhancement of coarsening, the coarsening rate of the dispersed particles in all crept specimens is faster than that in isothermally annealed specimens. Dislocations connecting dispersoids are observed more cofrequently in crept specimens with higher stress and lower temperature. The creep strain rates in the power law creep regime were found to be predicted much better by the Shorty and Rosler/Arzt equation with the inclusion of a threshold stress and dislocation detachment mechanism. The dispersoids in this alloy were acting a source of void nucleation that finally leaded to ductile fracture within the grain so called intergranular. Each void was initiated, grown and failed at the dispersoids in the aluminium matrix. Grain boundary accommodation of the slip produced, which result in initiation of the void and then final transgranular fracture. Therefore, it was confirmed that these dispersoids played an important role in the fracture mechanism by the formation of $Al_{13}Fe_4$, $Al_{13}Cr_2$ and $Al_2O_3$.

• Transactions of Materials Processing
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• v.14 no.7 s.79
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• pp.587-594
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• 2005

분무성형공정은 급냉응고 및 결정입자 제어에 따른 고품위 소재 개발의 장점과 함께 고밀도 near-net-shape 제품의 제조가 가능한 합금제조기술이다 분무성형체의 미세조직은 적층표면에 도달하는 액적들의 평균 열용량, 즉 고상분율에 의하여 결정되며, 이는 액적의 비행과정에서의 분사가스-액적간의 열전달과 적층표면에서의 열유입과 열유출 속도에 영향을 받는다. 실제 다양한 공정변수들이 복합적으로 미세조직 형성과정에 영향을 미치지만, 균일한 미세조직을 얻기 위하여서는 적층표면에서의 온도와 고상분율을 항상 일정하게 제어하여야만 한다 즉, 적층표면 온도를 분무 성형공정중에 지속적으로 측정하여 이를 공정 제어 시스템에 feedback하여 원하는 적층표면온도를 유지하도록 공정변수를 제어하는 것이 필수적이다. 분무성형에 제조된 성형체는 합금원소의 편석이 없고 미세한 등방성의 결정립으로 이루어진 특징적인 미세조직을 나타낸다 이와 같은 미세조직으로 인하여 분무성형체는 우수한 성형성과 기계가공성을 나타내며, 또한 분무성형-후속가공된 최종 제품은 잉곳주조에 의하여 제조된 것과 비교하여 크게 향상된 기계적 성질을 가진다.

• Journal of Korea Foundry Society
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• v.42 no.5
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• pp.273-281
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• 2022

In order to understand the solidification behavior and microstructural evolution of the Al-Cu-Si ternary eutectic alloy system, changes of the microstructure of the Al-Cu-Si ternary eutectic alloy with different cooling rates were investigated. When the mold preheating temperature is 500℃, primary Si and Al2Cu dendrites are observed, with (α-Al+Al2Cu) binary eutectic and needle-shaped Si subsequently observed. In addition, even when the mold preheating temperature is 300℃, primary Si and Al2Cu dendrites can be observed, and both (α-Al+Al2Cu+Si) areas observed and areas not observed earlier appear. When the mold preheating temperature is 150℃, bimodal structures of the binary eutectic (α-Al+Al2Cu) and ternary eutectic (α-Al+Al2Cu+Si) are observed. When the preheating temperature of the mold is changed to 500℃, 300℃, and 150℃, the greatest change is in the Si phase, and upon reaching the critical cooling rate, the ternary eutectic of (α-Al+Al2Cu+Si) forms. If the growth of the Si phase is suppressed upon the formation of (α-Al+Al2Cu+Si), the growth of both Al and Cu is also suppressed by a cooperative growth mechanism. As a result of analyzing the Al-27wt%Cu-5wt%Si ternary eutectic alloy with a different alloy design simulation programs, it was confirmed that different results arose depending on the program. A computer simulation of the alloy design is a useful tool to reduce the trial and error process in alloy design, but this effort must be accompanied by a task that increases reliability and allows a comparison to microstructural results derived through actual casting.