• Food Science and Biotechnology
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• 제16권2호
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• pp.255-259
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• 2007

The effects of temperature heating-up rate and pressure building-up phase on the inactivation of Listeria innocua ATCC 33090 were evaluated in buffered peptone water. The number of L. innocua was reduced by 5.57 and 6.52 log CFU/mL during the nonisothermal treatment (the come-up time followed by isothermal process) and the isothermal treatment, respectively, at $60^{\circ}C$. When compared to the isothermal treatment (0.76$33.2^{\circ}C/min$ of temperature heating-rate. The effect of the combined high pressure and thermal processing on the inactivation of L. innocua increased with increasing pressure and temperature. At all temperature levels from 40 to $60^{\circ}C$ under 700 MPa, L. innocua was not detected by enrichment culture (>7 log reduction).

• 소성∙가공
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• 제33권3호
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• pp.185-192
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• 2024

This study examined how varying tempering temperatures affect the susceptibility of Cr-Mo low alloy steels to hydrogen embrittlement. A slow strain-rate test (SSRT) was carried out on the steels electrochemically pre-charged with hydrogen in order to examine the hydrogen embrittlement behavior. The results showed that the hydrogen embrittlement resistance of the Cr-Mo low alloy steels improved with increasing tempering temperature. Thermal desorption analysis (TDA) revealed that diffusible hydrogen content decreased with increasing tempering temperature, accompanied by a slight increase in the peak temperature. This decrease in hydrogen content was likely due to a reduction in dislocation density which served as reversible hydrogen trap sites. These findings underline the significant role of tempering temperature in enhancing the hydrogen embrittlement resistance of Cr-Mo low alloy steels.

• 한국결정성장학회지
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• 제19권3호
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• pp.116-124
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• 2009

Our computational studies for the physical vapor transport crystal growth of $Hg_2Cl_2-Cl_2$ system evidence suggests that the PVT growth process exhibits the diffusion-dominated behaviors for aspect ratios more than and equal to 10, which would provide purely diffusive transport conditions adequate to microgravity environments less than $10^{-3}g_0$. Also, the regimes of high temperature difference based on the fixed source temperature of $380^{\circ}C$, where ${\Delta}T$ is relatively large enough for the crystal growth of mercurous chloride, the transport rates do not keep increasing with ${\Delta}T$ but tend to some constant value of $2.12\;mole\;cm^{-2}s^{-1}$. For the aspect ratios of 5, 10, and 20, the transport rate is directly proportional to the total pressure of the system under consideration. For Ar = 5, the rate is increased by a factor of 2.3 with increasing the total pressure from 403 Torr to 935 Torr, i.e., by a factor of 2.3. For both Ar = 10 and 20, the rate is increased by a factor of 1.25 with increasing the total pressure from 403 Torr to 935 Torr.

• 한국대기환경학회지
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• 제20권3호
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• pp.411-419
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• 2004

Titania particles are widely used as a photocatalyst to treat various contaminants in air and water. Titania particles were formed by vapor-phase oxidation of titanium tetraisopropoxide (TTIP) in a tube furnace between 773 and 1,273 K. The effect of process variables such as furnace temperature, flow rate of carrier air, and flow rate of sheath air on powder size and phase characteristics was investigated using a scanning mobility particle sizer (SMPS), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The size distribution of synthesized titania particles was characterized with mode diameter and peak concentration. The mode diameter ranging from 20 to 80 nm decreased with increasing flow rates of sheath air and carrier air, and increased with increasing furnace temperature. The peak concentration increased with increasing flow rates of sheath air and carrier air The best synthetic condition for high production rate can be derived from the experimental data set represented by mode diameter and peak concentration. The crystal structure of synthesized titania particles was found to be anatase phase, ensuring high photocatalytic potential.

• 열처리공학회지
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• 제4권3호
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• pp.39-46
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• 1991

The effects of austenitizing temperatures and times and cooling rate on the characteristics of continuous air cooling have been investigated for 0.3%C-Mn steels microalloyed with vanadium. Transformation start temperatures have been found to be measured from temperature-time curve directly obtained with continuous air cooling and to decrease with increasing austenitizing temperature, cooling rate and Mn contents. The coarsening behavior of austenite grain size has been measured to abnormally grow at $1050^{\circ}C$ and rapidly grow at $1200^{\circ}C$. It has been found that the volume fraction of pearlite was linealy proportional to the reciprocal square root of austenite grain size. The hardness has been measured to increase with increasing cooling rate up to $250^{\circ}C/min.$ and to remain relatively unchanged in the range of $250{\sim}400^{\circ}C/min.$ showing that hardness valves for steel with a higher Mn content increase more than those for steel with a lower Mn content. The impact property has been found to decrease with increasing of austenite grain size but does not linealy change with the reciprocal square root of austenite grain size.

• Carbon letters
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• 제15권2호
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• pp.146-150
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• 2014

In this work, activated carbon nanofiber (ACNF) electrodes with high double-layer capacitance and good rate capability were prepared from polyacrylonitrile nanofibers by optimizing the carbonization temperature prior to $H_2O$ activation. The morphology of the ACNFs was observed by scanning electron microscopy. The elemental composition was determined by analysis of X-ray photoelectron spectroscopy. $N_2$-adsorption-isotherm characteristics at 77 K were confirmed by Brunauer-Emmett-Teller and Dubinin-Radushkevich equations. ACNFs processed at different carbonization temperatures were applied as electrodes for electrical double-layer capacitors. The experimental results showed that the surface morphology of the CNFs was not significantly changed after the carbonization process, although their diameters gradually decreased with increasing carbonization temperature. It was found that the carbon content in the CNFs could easily be tailored by controlling the carbonization temperature. The specific capacitance of the prepared ACNFs was enhanced by increasing the carbonization temperature.

• International journal of advanced smart convergence
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• 제10권4호
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• pp.104-109
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• 2021

In the aftermath of the global pandemic that started in 2019, there have been many changes in the import/export and supply/demand process of agricultural products in each country. Amid these changes, the necessity and importance of each country's food self-sufficiency rate is increasing. There are several conditions that must accompany efficient agricultural activities, but among them, temperature is by far one of the most important conditions. For this reason, the need for high-accuracy climate data for stable agricultural activities is increasing, and various studies on climate prediction are being conducted in Korea, but data that can visually confirm climate prediction data for farmers are insufficient. Therefore, in this paper, we propose an artificial intelligence-based temperature prediction algorithm that can predict future temperature information by collecting and analyzing temperature data of farms in Gyeonggi-do in Korea for the last 10 years. If this algorithm is used, it is expected that it can be used as an auxiliary data for agricultural activities.

• 한국작물학회지
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• 제52권1호
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• pp.112-121
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• 2007

Grain filling is a crucial factor that determines grain yield in crops since it is the final process directly associated with crops' yield performance. Grain filling process can be characterized by the interaction of rate and duration of grain filling. This study was conducted, using 16 temperate japonica rice genotypes, with aims to (1) seek variations in grain filling duration and rate on area basis, (2) compare the contribution of grain filling duration and rate to grain yield, and (3) examine the influence of temperature and solar radiation for effective grain filling on grain yield in relation to grain filling duration and rate. Grain filling rate and duration exhibited highly significant variations in the ranges of $20.7{\sim}46.3\;g\;m^{-2}d^{-1}\;and\;11.2{\sim}35.5$ days, respectively, depending on rice genotypes. Grain yield on unit area basis was associated positively with grain filling duration but negatively with grain filling rate. Grain filling rate and duration were negatively correlated with each other. Final grain weight increased linearly with the rise in both cumulative mean temperature and cumulative solar radiation for effective grain filling. Higher cumulative mean temperature and cumulative solar radiation for effective grain filling were the results of longer grain filling duration, but not necessarily higher daily mean temperature and daily solar radiation for effective grain filling. Grain filling rate demonstrated an increasing tendency with the rise in daily mean temperature for effective grain filling but their relationship was not obviously clear. It was concluded that grain filling duration, which influenced cumulative mean temperature and cumulative solar radiation for effective grain filling, was the main factor that determined grain yield on unit area basis in temperate Japonica rice.

• 설비공학논문집
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• 제11권6호
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• pp.855-860
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• 1999

An experimental study of jet impingement on the surface with linear temperature gradient is conducted with the presentation of the turbulent characteristics and the heat transfer rates measured when this jet impinges normally to a flat plate. The jet Reynolds number ranges from 30,000 to 90,000, the temperature gradient of the plate is 2~$4.2^{\circ}C$/cm and the dimensionless nozzle to plate distance(H/D) is from 6 to 10. The results show that the peak of heat transfer rate occurs at the stagnation point, and the heat transfer rate decreases as the radial distance from the stagnation point increases. A remarkable feature of the heat transfer rate is the existence of the second peak. This is due to the turbulent development of the wall jet. Maximum heat transfer rate occurs when the axial distance from the nozzle to nozzle diameter(H/D) is 8. The heat transfer rate can be correlated as a power function of Prandtl number, Reynolds number and the dimensionless nozzle to plate distance(H/D). It has been found that the heat transfer rate increases with increasing turbulent intensity.

• 생물환경조절학회지
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• 제9권2호
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• pp.120-126
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• 2000

표고버섯(Lentinus edodes(Berk) Sing)의 품질은 환경조건에 매우 민감하고, 특히 생산기간중의 강우에 의한 수분의 영향이 큰 것으로 알려져 있다. 대부분의 경우, 표고버섯이 강우에 의하여 젖지 않도록 하기 위하여, 강우차단용 플라스틱 필름을 사용하여 측창 환기구 이외에는 모두 밀폐시킨 재배시설을 사용하고 있다. 그러나 이와 같이 천창이 없는 재배시설의 실내온도와 습도는 불량한 환기로 인하여 상승하게 되고, 결국 생산성 및 품질을 떨어뜨리게 된다. 본 연구에서는 모델을 이용하여 개선된 표고재배시설의 천창 면적과 차광율에 따른 환기율 및 실내온도 변화를 분석하였다. 차광율이 50%에서 90%로 증가할수록 온도는 약 2.5$^{\circ}C$ 이상의 차이를 나타냈으며 50%의 낮은 차광율에서 풍속의 영향이 크게 나타났다. 환기율은 풍속 1~2m.s-1 이상에서는 차광율에 관계없이 크게 증가하였다. 실외풍속이 0m.s-1에서 2m.s-1로 증가함에 따라 실내온도는 약 2$^{\circ}C$이상 하강하였다. 특히, 천창개도가 커질수록 온도가 하강하였지만 개도 50%이상에서는 큰 차이가 없었다. 차광율이 낮을수록 개도 증가가 온도하강에 미치는 영향이 뚜렸하였다. 풍속 및 차광율에 무관하게 천창면적과 측창면적이 거의 동일할 때, 높은 환기효율 및 온도하강 특성을 나타내었다.