• 한국레이저가공학회지
• /
• 제9권1호
• /
• pp.9-16
• /
• 2006

Glass is one of brittle materials. Generally, brittle material is weak for tensile stress but strong for compression stress. Laser breaking of glass used this brittle characteristics. Laser breaking of glass was simulated to optimize breaking condition by using commercial FEM code MARC which is applicable to thermo-mechanical coupling analysis. Various shapes of heat sources were applied to the analysis and the distance between heating and cooling source were varied for each simulation. The shapes of heat sources were circle, single and double ellipse and the distance was varied from 0mm to 30mm. Moving heat sources were designed on the basis of experimental condition. As a result, double elliptic shape of heat source was the most suitable among them in laser breaking of glass. And it should be useful to determine optimal condition of laser breaking for glass.

• Preventive Nutrition and Food Science
• /
• 제12권4호
• /
• pp.251-258
• /
• 2007

Thermal resistance and heat activation characteristics of Clostridium botulinum ATCC 25763 spores were evaluated. The effects of nisin and pH on the activation and subsequent germination were also investigated. Spores of C. botulinum were not inactivated by heat treatments up to $92^{\circ}C$ for 2 hr. Heat treatment at $85^{\circ}C$ for 90 min was selected as the optimal activation condition based on monitoring subsequent germination. L-alanine alone or in combination with L-cysteine was not sufficient to germinate the spores of this strain. Tryptone-Peptone- Glucose-Yeast extract (TPGY) broth supplemented with L-alanine was used as a suitable germination medium. Decreasing pH of activation suspension increased the degree of phase darkening, i.e., germination. In addition, the presence of nisin during activation increased the degree of phase darkening. The majority of spore populations were dormant at a pH of less than 2.8, and these populations required heat activation to increase the culturability on TPGY agar medium. However, extended heating in the presence of nisin at pH 2.8 decreased the spore count; however, heat activation was less necessary at pH 3.4, compared at pH 2.8.

• 수산해양기술연구
• /
• 제59권2호
• /
• pp.155-163
• /
• 2023

This study deals with the maximum thermal load analysis and optimal capacity determination method of tank culture system for applying seawater source heat pump to save energy and realize zero energy. The location of the fish farm was divided into four sea areas, and the heat load in summer and winter was analyzed, respectively. In addition, two representative methods, the flow-through aquaculture system and the recirculation aquaculture system were reviewed as water treatment methods for fish farms. In addition, the concept of the exchange rate was introduced to obtain the maximum heat load of the fish farms. Finally, power consumption for heat pumps was analyzed in the view point of sea areas, tank capacity, and exchange rate based on the calculated maximum thermal load.

• 한국식품저장유통학회지
• /
• 제13권2호
• /
• pp.223-227
• /
• 2006

Anti-H pylori 항체를 함유한 면역우유를 $60^{\circ}C$에서 30분 열처리한 것과 열처리하지 않은 Anti-H. pylori 항체를 함유한 원유의 면역활성 비교시 99.99(100)%의 면역 활성을 나타내었으며, $75^{\circ}C$ 이상의 열처리에 의해서는 면역 활성이 급격하게 감소하여 약 50%이하로 감소하였다. 열처리 온도가 높을수록, 열처리 시간이 증가할수록 총균수의 감소율이 증가하였다. Coliform bacteria의 경우는 원유에서 $10^2\;CFU/mL$이 관찰되었으나 모든 열처리 구에서는 관찰되지 않았다. 면역우유를 $2^{\circ}C,\;4^{\circ}C$ 그리고 $10^{\circ}C$에서 21일 동안 저장한 결과 면역우유의 저장 중pH의 변화는 저장 21일 동안 $2^{\circ}C$와 $4^{\circ}C$에 저장한 경우 저장온도에 따른 뚜렷한 변화는 관찰할 수 없었으며, $10^{\circ}C$에 저장한 경우 저장 7일 이후 급격히 감소하였다. 총균수의 변화는 저장 초기 $10^3\;CFU/mL$에서 $2^{\circ}C$와 $4^{\circ}C$에 저장한 열처리 면역우유의 총균수는 저장 21일 동안 뚜렷한 증가현상을 관찰할 수 없었으며, $10^{\circ}C$에 저장하였을 경우 7일 이후 급격히 증가하여 저장 14일째 $10^8\;CFU/mL$로 부패현상을 나타내었다. 면역우유의 저장 중 면역 활성의 변화는 저장 온도에 관계없이 저장 14일까지는 저장초기의 활성에 비해 뚜렷한 차이는 나타나지 않았으나 14일 이후 급격히 감소하는 경향을 나타내었다.

• 열처리공학회지
• /
• 제37권1호
• /
• pp.16-22
• /
• 2024

The conventional degreasing process involves removing oil and contaminants at temperatures above 80℃, resulting in excessive energy consumption, increased process costs, and environmental issues. In this study, we aimed to find the optimal degreasing conditions for the pre-treatment process of electro-galvanizing cold-rolled steel sheets, conducted efficiently at room temperature without the need for a separate heating device. To achieve this, we developed a room temperature degreasing solution and a brush-type degreasing tool, aiming to reduce energy consumption and normalize the decrease in degreasing efficiency caused by temperature reduction. Alkaline degreasing solution were prepared using KOH, SiO₂, NaOH, Na₂CO₃, and Sodium Lauryl Sulfate, with KOH and NaOH as the main components. To enhance the degreasing performance at room temperature, we manufactured additives including sodium oleate, sodium stearate, sodium palmitate, sodium lauryl sulfate, ammonium lauryl sulfate, silicone emulsion, and EDTA-Na. Room temperature additives were added to the alkaline degreasing solution in quantities ranging from 0.1 to 20 wt.%, and the uniformity of degreasing and the adhesion of the galvanized layer were evaluated through Dyne Test, T-bending Test, OM, SEM, and EDS analyses. The results indicated that the optimal degreasing solution composition consisted of NaOH (30 g/L), Na₂CO₃ (30 g/L), SLS (6 g/L), and room temperature additives (≤1 wt%).

• 폴리머
• /
• 제34권5호
• /
• pp.391-397
• /
• 2010

폴리아믹산(PAA)은 가교가 가능한 2중 결합을 갖는 bicyclo(2,2,2)oct-7-ene-2,3,5,6-tetracarboxy-licdianhydride(BTDA)와 bis[4-(3-aminophenoxy)phenyl] sulfone(BAPS)을 N,N-dimethylacetamide(DMAc) 용매에서 반응하여 얻어졌으며, 폴리이미드(PI) 필름은 PAA를 캐스팅하여 각각 다른 반응 온도에서 열처리를 통해 얻었다. 가교 온도를 $250{\sim}350^{\circ}C$까지 증가하여 얻은 가교된 PI의 열적-기계적 성질, 가교도, 광학적 특성을 열처리 온도에 따라 조사하였다. 열적-기계적 성질은 $350^{\circ}C$에서 열처리되었을 때 최대 값을 나타냈으며, 광학적 특성은 $250^{\circ}C$에서 열처리된 필름이 가장 우수한 광학특성을 보였다. $250{\sim}350^{\circ}C$까지 열처리에 따른 가교도는 NMR 상에서 85~93%를 나타냈다.

• Journal of Ceramic Processing Research
• /
• 제21권4호
• /
• pp.479-487
• /
• 2020

Ceramic ZnS nanocomposites were prepared by mechanical processing and one-step heat sintering with powder mixtures of fly ash, waste glass, and ZnS (template-free hydrothermal method manufacturing). Chemical durability and morphological characteristics of heat-treated samples at 800 ℃ with/without acid treatment were evaluated. The photocatalytic activities were estimated with methyl orange (MO), methylene blue (MB), acetaldehyde (ATA), and 2,4-dichlorophenoxyacetic acid (2,4-D) as photodegradation targets. Crystallization behaviors of the prepared ceramic ZnS nanocomposites were investigated using X-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM), and energy dispersive X-ray spectrometry (EDS). In addition, compressive and bending strength as mechanical properties were evaluated. Ceramic ZnS nanocomposites were found to showed improvement in optimal photocatalytic reaction and physical properties regardless of acid treatment when the amount of ZnS nanoparticles was increased from 7.0 to 25.0 wt%. Degrees of photocatalytic decomposition of MO, ATA, 2,4-D, and MB by acid treated ceramic ZnS nanocomposites containing 25 wt% ZnS were about 0.185, 0.121, 0.216, 0.236, respectively, after UV irradiation for 180 min.

• 한국식생활문화학회지
• /
• 제34권3호
• /
• pp.361-368
• /
• 2019

The purpose of this study was to establish the best optimized extraction condition for the optimal development of fresh maca beverage using low temperature extraction and enzyme treatment. Low temperatures were applied to prevent heat-related nutritional loss during the extraction process. Best extraction conditions were investigated based on the ratio of maca to water, the ratio of enzymes, extraction temperature and time, and agitation. The optimal enzyme conditions were also examined after the treatment of cellulase:pectinase mixture to maintain the original color and flavor, as well as to increase the extraction yield. When cellulase:pectinase was 1:1, the extraction rate ranged from 77.84 to 79.29%. In addition, the best extraction rate was found when maca was mixed with twice volume of water and incubated at $45^{\circ}C$ ($84.05{\pm}0.32%$) with 90 rpm ($87.13{\pm}0.46%$) agitation for 3 hours ($84.73{\pm}0.29%$). Furthermore, sensory evaluation showed a high score in flavor, sweetness, and overall acceptability after adding 3% jujube concentrate into a fresh maca beverage.

• 열처리공학회지
• /
• 제36권1호
• /
• pp.22-32
• /
• 2023

In general, when scrap is dissolved in an electric arc furnace, the amount of electric furnace steel dust (EAFD) generated is about 1.5% of the scrap charge amount, and the electric furnace steel dust collected by the bag filter is charged into the Rotary Kiln or Rotary Hearth Furnace (RHF), and the zinc component is recovered as crude zinc oxide, at which time a clinker of Fe-Base is generated. In this research, first, for the efficient resource conversion of electric furnace steel dust, a reduction and roasting experiment was conducted and the reaction kinetics was examined. As a result of the experiment, it was observed that the reduction and roasting reaction was actively conducted in the range of 1100~1150℃, and melting occurred in the range of 1250℃. In the past, this clinker was widely used as a roadbed material for road construction and an Fe-Source for cement production, but in recent years, it has been mainly reclaimed due to strengthening environmental standards. However, landfill treatment is by no means a desirable treatment method due to environmental pollution caused by leachate, expensive landfill costs, and waste of Fe resources. Therefore, in order to more actively recycle the Fe component in the clinker, first of all the clinker was pulverized into an optimal particle size, and anthracite and binder (starch) were added to the magnetic material obtained by specific gravity and magnetic separation for briquet. As a experimental results, it was possible to efficiently separate clinker as Fe component and other slag component by specific gravity and magnetic force. As a results of loading and dissolving the manufactured briquet clinker in an electric arc furnace, it was observed that the unit of power and production yield were clearly improved and the carbon addition effect in molten metal was also somewhat.

• 농업과학연구
• /
• 제50권4호
• /
• pp.603-616
• /
• 2023

This study was conducted to investigate the productivity, meat quality, blood variables, stress responses, and litter quality of broilers offered feed with different levels of Glycine (Gly) supplementation under heat stress condition. A total of 760 one-day-old Ross 308 broiler males were randomly assigned to one of the four dietary treatment groups: (1) basal diet (control; CON); (2) basal diet + Gly 0.1% (Gly 0.1%); (3) basal diet + Gly 0.2% (Gly 0.2%); and (4) basal diet + Gly 0.3% (Gly 0.3%). The environments for all the treatments groups were maintained according to broiler rearing guidelines from day 1 to day 21, and heat stress condition (32 ± 1℃, 60 ±5%) was created from day 22 to the end. The addition of Gly increased weight gain and affected feed intake (p < 0.05). Gly 0.1% group had higher pH and ferric reducing antioxidant power (FRAP) in the chicken meat and lower heterophil (HE)/lymphocyte (LY) ratio in the blood (p < 0.05). In particular, Gly 0.2% treatment group had lower serum corticosterone level (p < 0.05) than other groups. For jejunum morphology, the addition of Gly 0.2% significantly reduced the depth of the crypts (p < 0.05). However, the addition of Gly did not significantly affect litter quality (p > 0.05). In conclusion, the addition of glycine improved productivity and meat quality, alleviated heat stress, and improved intestinal function. Further studies are needed to determine the optimal level and mechanism of action of the additive when ingested.