• Proceedings of the Materials Research Society of Korea Conference
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• 2009.05a
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• pp.41.1-41.1
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• 2009

최근 금형은 자동차뿐만 아니라 여러 산업에서 필수적이며 제품의 품질은 물론 제조원가에 막대한 영향을 미친다. 이러한 금형은 침탄, 질화, 고주파담금질등에 의해 표면처리 되어져 왔으나, 이와 같이 기존의 처리 방법은 모두 처리물 전체를 가열하거나 균일한 가열을 하지 못하기 때문에 변형의 문제와 처리후의 후가공의 경비 문제, 그리고 극히 일부분만 경화가 필요한 부품에는 적용하기 어려운 문제점이 있다. 이러한 문제를 해결할 수 있는 표면처리로서 레이저 표면처리 방법이 대두되고 있으며, 레이저 표면처리는 레이저 빔을 피처리물의 표면에 조사하고 적당한 속도로 이동을 하게 되면 레이저조사부위가 급속하게 가열되고 레이저빔이 통과한 후에는 표면의 열이 내부로 열전도 되어 급속히 자기냉각(Self-quenching)됨으로서 표면에 새로운 기계적 성질을 갖게 하는 표면처리법이다. 이와 같이 레이저를 이용한 표면처리로 기존의 CW Nd:YAG 레이저 열원보다 효율이 좋은 HPDL(High Power Diode Laser)를 이용한 고효율, 고기능 금형 표면처리 후 재료적 물성을 평가하고자 한다. 평가방법은 레이저빔의 조사속도 및 온도변화에 따른 표면처리부, 열영향부 그리고 모재 부분에 대한 경도특성 및 미세조직 변화를 관찰하였다. 또한 조사속도 및 온도변화에 대해 경화깊이를 관찰하였다.

• Nuclear Engineering and Technology
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• v.26 no.2
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• pp.237-246
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• 1994

A high flow critical heat flux (CHF) correlation, based on the single-pin CHF experimental data for finned and unfinned heated rods, was developed for the thermal-hydraulic design and safety analysis of the Korea Multi-purpose Research Reactor (KMRR) core. The correlation consists of dimensionless parameters such as Reynolds number, thermodynamic equilibrium quality, liquid-to-vapor density ratio, and hydraulic equivalent diameter ratio. The fin effect was taken into account in the correlation by a finned-to-unfinned heated perimeter ratio. The effects of a cold wall and non-uniform axial power distribution ore discussed to verify the applicability of the single-pin based correlation to the KMRR fuel bundle. The correlation limit departure from nucleate boiling ratio (DNBR) was determined as 1.44 from the statistical analysis of the CHF data.

• Korean Journal of Food Science and Technology
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• v.7 no.3
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• pp.154-158
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• 1975

Effects of combined treatments of radiation-heat and radiation-chemicals on the survival of mycotoxin-producing molds Aspergillus flavus and Penicillum islandicum conidia were investigated. Combined treatments of gamma-radiation and heat (10 minutes at $50^{\circ}C\;or\;55^{\circ}C$) showed a synergistic effect, causing remarkable decreases in $D_{10}$ values and induction doses in the two molds. Combined treatments of gamma-radiation and chemicals (sorbic acid) had no synergistic effect. Asp. flavus was more resistant to heat and sorbic acid than was Pen. islandicum.

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2003.05a
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• pp.29-33
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• 2003

최근 이동 정보통신 분야의 발전에 따라 단말기 및 관련 부품들을 소형 경량화 하는 것이 매우 중요한 기술요소로 부각되고 있다. 이를 위해서는 기판의 배선밀도를 높이는 것과 개별 부품 또는 모듈의 크기와 무게를 줄이는 것이 절실히 필요하며, 이러한 요구에 부응하기 위해 기존의 다층 PCB 기술이나 MCM 기술에 비해 우수한 배선밀도와 양호한 전기적 특성을 갖는 저온 동시소성 세라믹(Low Temperature Co-fired Ceramic) 기술이 개발, 적용되고 있다. 본 논문에서는 이러한 LTCC 기판의 소결에 있어 기존의 소결 공정인 전기로 소결 공정과 microwave를 이용한 소결 공정을 이용하여 소결 하였을 때, LTCC 기판의 수축율과 무게감소, 그에 따른 밀도변화, SEM 을 이용한 표면형상 분석을 통해 급속가열을 통한 공정시간의 단축, 낮은 에너지 소비로 인한 제조단가의 절감, 균일한 가열로 인한 소결온도의 저하 등의 장점을 갖는 microwave sintering 을 적용할 수 있는 가능성을 제시하였다.

• Korean journal of food and cookery science
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• v.32 no.4
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• pp.390-399
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• 2016

Purpose: The objective of this study was to examine the effect of plant scale and cooking conditions on the quality characteristics of sausages during refrigerated storage. Methods: Sausages used in this study were classified into two groups: those submitted to $1^{st}$ cooked treatments and those submitted to $2^{nd}$ cooked treatments. The pH, volatile basic nitrogen (VBN), gas production ratio, and microorganisms were measured in triplicate. Results: The change of quality in the products was assessed every 7 days by measuring pH, VBN levels, total microbes, coliform bacteria, Escherichia coli, and pathogenic bacteria in the products. Pathogenic bacteria such as Staphylococcus aureus, Listeria monocytogenes, Clostridium perfringens, and E. coli were not detected in the sausages with $1^{st}$ cooked treatments. The results showed that the pH of the sausages decline as storage time increased. The pH value of the sausages with $2^{nd}$ cooked treatments changed gradually. VBN levels were generally lower in products with $2^{nd}$ cooked treatments than in those with $1^{st}$ cooked treatments, but they varied with the type of products. On the $35^{th}$ day, the number of total microbes ranged between 6.13-7.12 log CFU/g in products with $1^{st}$ cooked treatments and 3.44-6.92 log CFU/g in products with $2^{nd}$ cooked treatments, showing fewer bacteria in the latter products. Conclusions: $1^{st}$ cooked treatments were effective in microbial control, but $2^{nd}$ cooked treatments could prolong the shelf life of the sausages, indicating a need for differential management of each product.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.8 no.4
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• pp.555-562
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• 1998

Under the influence of non-uniform magnetic field, melt flow in steady state and oxygen concentration in unsteady state are numerically investigated. The strength of the applied characteristic magnetic fields are B=0.1T, 0.2T, and 0.3T, respectively. The buoyancy effects due to the crucible wall heating and the thermocapillary effects due to the surface tention at the free surface are suppressed differentially by the non-uniform magnetic fields. As the intensity of characteristic magnetic fields is increasing, the recirculation region in the meridional plane is moving toward the growing crystal, and is diminishing. The oxygen concentration on the growing surface of crystals is decreasing and the uniformity of the oxygen concentration is increasing as the intensity of the magnetic fields is increasing.

• Korean Journal of Food Science and Technology
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• v.26 no.1
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• pp.31-36
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• 1994

In order to prepare SPI tofu without compression step, amounts of water added to SPI suspension was studied for textural properties of uncompressed SPI tofu prepared by first heating at $100^{\circ}C$ for 6 minutes and second heating at $75^{\circ}C$ for 25 minutes and use of $CaSO_{4}-GDL$(0.07g, 0.0075 g/g SPI) as coagulants. The hardness and uniformity were gradually increased as the water addition ratio $(gH_{2}O/g\;SPI)$ raised from 6.0 to 8.0 and cohesiveness was rather decreased. The increase in second heating time increased the hardness and gumminess and relativity higher values in hardness were measured for those tofu heated at $85^{\circ}C$ than those at $75^{\circ}C$ or $95^{\circ}C$. A multiple regression equation calculated and RSM figure showed that the effects of water addition ratio was become to be less as the heating time and temperature increased. Addition of 8 g of water per g SPI and second heating at $85^{\circ}C$ for $30{\sim}60$ minutes were found as optimal conditions to prepare uncompressed SPI tofu.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.4
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• pp.126-137
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• 2014

Characteristics of heating and drying of Canadian-imported Douglas-fir timber using microwave in order to secure convenience and quality of drying timber and to get basic data for secondary conservation treatment are as follows: As the results of analysis of change curves of internal temperature of the timber after irradiating it, round timber and board timber showed stable heat distribution, heat consumption and surface water-content in heating with 30kW for 30 minutes and 120 minutes and with 40kW for 3 minutes and 9 minutes, respectively. Especially, surface water-content distribution according to heating by microwave showed very even leveling and water-content decrease rate was also more 30% compared to its weight showing excellent dry efficiency. And in case of soaking timbers into liquid chemicals for secondary conservation according to the analysis results of heat consumption, it is expected that large amount of preservative will be permeated. Therefore, timber heated by microwave is remarkably available for using industrial materials and developing secondary utilized products with its fast water-content decrease and dryness and higher heat consumption.

• Korean Journal of Food Science and Technology
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• v.33 no.3
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• pp.327-332
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• 2001

Attempts were made to investigate the effect of gamma irradiation and heat treatment on quality changes of Bulgogi sauce during the storage at 4 and $20^{\circ}C$. Total acidity, Surface color, brix, microbial growth and sensory quality of test products were evaluated during storage. Total acidity of sauce did not change during storage at $4^{\circ}C$, whereas those of control and 4 kGy groups changed significantly during storage at $20^{\circ}C$. Gamma irradiation and heat treatment had little effect on brix of the suace during storage period. Surface color of control and 4 kGy group significantly changed during storage, especially at $20^{\circ}C$. Sucrose contents in sauce decreased during storage, while glucose and fructose contents increased. Sensory quality of sauces stored at $4^{\circ}C$ for 12 weeks was similar, except the control. Control and 4 kGy treated sauces stored at $20^{\circ}C$ for 6 week had detectable levels of off-flavor. Colifrom bacteria were not detected in sauces treated by either heat or gammma-ray. Total acrobic increases in colony counts were slower at $4^{\circ}C$. Yeasts or molds were not detected in sauces treated by heat or gamma-ray over 7-10 kGy. These results indicated that gamma irradiation over 7kGy or heat treatment of the sauce maintained acceptable quality.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.21 no.1
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• pp.27-34
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• 2015

Heating patterns depending on the packaging materials were examined in order to investigate the causes of thermal deformation of packages used for ready-to-eat foods for microwave heating due to the non-uniformity of microwaves. Physical properties including tensile strength, heat-resistance and elongation of four different CPP grades were compared. High retortable CPP had higher sealing strength and heat resistance compared to the conventional CPPs. All CPP samples tested were proved to have melting temperatures around $160^{\circ}C$. However, they were all thermally deformed by microwave heating due to a limited penetration of microwave and non-uniform heating within the spicy sauce of high viscosity contained high salt, especially on the above the filling line and sealing edge of pouches. When the laminated stand-up pouches composed of G-PET/PET/PET/CPP and G-PET/PET/NY/CPP were retorted and microwaved, significant deformations were noticed in both samples after retorting. Besides, pouches contained titanium dioxide showed more intense thermal deformation than the control. When the $10{\mu}m$ aluminium foil was affixed on the pouch, small thermal deformation was observed only in the bottom layer. More studies are required to prevent the thermal deformation of packaging materials used for RTE foods during microwave heating by developing the technologies to increase the thermal stability of CPP layer and the modification of packaging design to modify the microwave access into the package.