• 에너지공학
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• 제23권3호
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• pp.21-26
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• 2014

유럽 원전 시장 개척을 위해 개발 중인 EU-APR1400은 중대사고 대처설비로 노외 노심용융물 보유 및 냉각을 위한 소위 Core catcher라 불리는 노외 노심용융물 냉각설비를 개발 중이며, Core catcher body를 노심용융물로부터 보호하기 위하여 노심용융물의 물성 및 상태를 변화시켜 냉각 및 보유에 유리하게 하는 희생물질을 설치한다. 중대사고 시 원자로 압력용기의 틈으로부터 노심용융물이 분출되어 희생물질에 충돌 시 열 전달량이 매우 증가하게 되므로, 이 때 노심용융물 제트의 충돌에 의한 희생물질의 침식율을 정확하게 예측하는 것은 매우 중요하다. 이 논문에서는 경계층 이론을 기반으로 한 희생물질 침식 모형을 제안하고 KAERI에서 수행한 실험결과와 비교하였다.

• 한국수정란이식학회지
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• 제29권2호
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• pp.189-194
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• 2014

The reproductive disorders are the major causes of reproductive infertility in cows that affect the total annual calf crop, resulting in great economic loss in Bangladesh. The aim of the study was to find out the reproductive disorders (RD) in dairy cows that markedly influences the reproductive performances in aspect of Bangladesh. A total number of 1658 dairy cows were selected according to their body condition score (BCS) in different farms at the southern part of Bangladesh during the period of 2011 to 2012. The preliminary data (basic information) were collected directly from the dairy farmer's record books and asking questions according to a prescribed questionnaires as well as the diagnosis of RD was presumptively confirmed on the basis of history, clinical signs and examination of animals by ultrasonography and others necessary tools. There are thirteen major reproductive disorders were identified. Overall prevalence of reproductive disorders at that area were 23%, among of these anoestrus 5.1%, repeat breeder 3.7%, metritis 4.4%, poor heat detection 1.6%, ovarian cyst 0.36%, retain placenta 4.6%, dystocia 0.97% and pyometra 0.24%. It is indicated that anoestrus and retention of placenta after calving was most hazardous cause of infertility whereas the metritis and repeat breeder were the second line of consequence. RD had shown significantly higher incidence in low BCS (${\leq}2$) than that of fair (2.5) and very good (${\geq}3{\sim}3.5$). In conclusion, the highest RD especially anoestrus and retention of placenta is very alarming for reproductive loss which might be needed further research to identify the specific cause of these disorders for establishment a profitable dairying and dairy population.

• Asian-Australasian Journal of Animal Sciences
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• 제29권2호
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• pp.204-210
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• 2016

This study examined the effect of supplementing exogenous cellulase on nutrient and energy utilization. Twelve desexed Boer crossbred goats were used in a replicated $3{\times}3$ Latin square design with 23-d periods. Dietary treatments were basal diet (control, no cellulase), basal diet plus 2 g unitary cellulase/kg of total mixed ration dry matter (DM), and basal diet plus 2 g compound cellulase/kg of total mixed ration DM. Three stages of feeding trials were used corresponding to the three treatments, each comprised 23 d, with the first 14 d as the preliminary period and the following 9 d as formal trial period for metabolism trial. Total collection of feces and urine were conducted from the 4th d of the formal trial, and gas exchange measures were determined in indirect respiratory chambers in the last 3 d of the formal trial. Results showed that cellulase addition had no effect (p>0.05) on nutrient digestibility. Dietary supplementation of cellulase did not affect (p>0.05) N intake and retention in goats. Gross energy (GE) intake, fecal energy and urinary energy excretion, heat production were not affected (p>0.05) by the cellulase supplementation. Total methane emission (g/d), $CH_4$ emission as a proportion of live weight or feed intake (DM, organic matter [OM], digestible DM or digestible OM), or $CH_4$ energy output ($CH_4$-E) as a proportion of energy intake (GE, digestible energy, or metabolizable energy), were similar (p>0.05) among treatments. There was a significant (p<0.001) relationship between $CH_4$ and live weight (y = 0.645x+0.2, $R^2$ = 0.54), $CH_4$ and DM intake (y = 16.7x+1.4, $R^2$ = 0.51), $CH_4$ and OM intake (y = 18.8x+1.3, $R^2$ = 0.51) and $CH_4$-E and GE intake. Results from this study revealed that dietary supplementation of cellulase may have no effect on nutrient digestibility, nitrogen retention, energy metabolism, and methane emission in goat.

• The Korean Journal of Ceramics
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• 제5권3호
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• pp.296-302
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• 1999

The state of the art of the 2-stage swirl calciner is to make 2-stage counter gas flow in a calciner with cooler hot air. Gas flow in the calciner increases retention time of raw mix particles. Simple structure of the 2-stage swirl calciner operated optimally the rotary cement kiln. In this study, in order to decide the entrance type of the cooler air of the optimal calciner model, an entrance cooler air velocity, the input points of raw mix were analyzed in many aspects with cold model experiment and computational fluidized dynamic simulation. It was found that the entrance type of cooler air fully splite 2-stage for the optimal condition of the cold model calciner. The operation conditions were that the input feeding, the cooler air velocity and the air velocity of throat were 0.33kg/$\textrm m$3$, 15m/s and 20m/s respectively. The performance of 150 t/d the pilot plant connected with the kiln rising duct was that volume capacity of the calciner is over 430 kg/$\textrm m$3$-h, decarbonation rate of raw mix apparently 90%, heat consumption 950 kcal/kg-cli and retention time of raw mix 2.4 sec. Its the best operating condition is cooler air velocity 18m/s, the gas velocity of throat 25m/s, feeding rate of raw mix 10t/h. The operating experience of the pilot plant confirmed the success of scale up for over 3000 t-cli/d.

• Journal of Dairy Science and Biotechnology
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• 제23권2호
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• pp.115-123
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• 2005

Microcapsules consisting of natural, biodegradable polymers for controlled and/or sustained core release applications are needed. Physicochemical properties of whey proteins suggest that they may be suitable wall materials in developing such microcapsules. The objectives of the research were to develop water-insoluble, whey protein-based microcapsules containing a model water-soluble drug using a chemical cross-linking agent, glutaraldehyde, and to investigate core release from these capsules at simulated physiological conditions. A model water soluble drug, theophylline, was suspended in whey protein isolate (WPI) solution. The suspension was dispersed in a mixture of dichloromethane and hexane containing 1% biomedical polyurethane. Protein matrices were cross-linked with 7.5-30 ml of glutaraldehyde-saturated toluene (GAST) for 1-3 hr. Microcapsules were harvested, washed, dried and analyzed for core retention, microstructure, and core release in enzyme-free simulated gastric fluid (SGF) and simulated intestinal fluid(SIF) at $37^{\circ}C$. A method consisting of double emulsification and heat gelation was also developed to prepare water-insoluble, whey protein-based microcapsules containing anhydrous milkfat (AMF) as a model apolar core. AMF was emulsified into WPI solution (15${\sim}$30%, pH 4.5-7.2) at a proportion of 25${\sim}$50%(w/w, on dry basis). The oil-in-water emulsion was then added and dispersed into corn oil ($50^{\circ}C$) to form an O/W/O double emulsion and then heated at $85^{\circ}C$ for 20 min for gelation of whey protein wall matrix. Effects of emulsion composition and pH on core retention, microstructure, and water-solubility of microcapsules were determined. Overall results suggest that whey proteins can be used in developing microcapsules for controlled and sustained core release applications.

• 한국식품위생안전성학회지
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• 제6권2호
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• pp.83-87
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• 1991

육류중의 Tetracycline계 항상물질의 잔류량을 조사하기 위하여 시판 중인 쇠고기, 돼지고기. 닭고기 3종을 각각 3개시료씩 구입하여 Tetracycline(TC), Oxyteracycline(OTC) , Chlortetracycline(CTC) 의 잔류량을 분석하였으며, 아울러 잔류 항생물질의 조리가열에 의한 분해감소량을 조사한 결과는 다음과 같다. 1. 시판 육류중의 OTC 및 CTC 잔류량: OTC 잔류량은 닭고기의 경우 A 시료에서 흔적정도, B시료에서 불검출 , C시료에서는 0.09mg/kg이 검출되었다. 쇠고기 3개 시료에서는 C 시료에서만 돼지고기 A 및 B에서는 흔적정도로 검출되었다. CTC은 닭고기 A,C시료에서 0.14, 0.02mg/kg으로 각각 검출되었으며, 쇠고기와 돼지고기의 경우에는 쇠고기 B에서만 0.01mg/kg의 잔류량이 확인되었다. 2. TC 잔류량 : 쇠고기와 돼지고기의 Tc 분석에는 육류 자체에서 유래된 성분의 peak와 TC의 peak가 중복되어 잔류량의 판단을 방해하였으나, 닭고기의 경우에는 이러한 방해 성분이 없었으며, 3개중 A 시료에서만 0.01mg/kg의 잔류량이 검출되었다. 3. 가열방법별 항생물질의 분해정도 : 가장 고온가열인 굽기에서, 특히 TC 및 OTC의 분해가 많았다.. 4. 가열시간에 따른 분해정도 : 자불에서는 상당시간이 경과하여도 미량의 분해가 있었으나, 굽기에서는 시간경과에 따라 분해량의 현저한 증가를 보였다. 굽기와 같은 조리 효과를 가진 전자오븐 가열에서는 덜 분해되었다. 가열에 대한 각 항생물질의 내열성은 CTC>OTC>TC 의 순으로 나타났다.

• 한국환경과학회지
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• 제16권10호
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• pp.1169-1177
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• 2007

The main objective of this research was to evaluate the effects of process variables which were forming ability, flow displacement, effective stress, effective strain, fluid vector and products defects on manufactured artificial lightweight aggregate made of both incinerated sewage sludge ash and clay by means of the numerical analysis of a rigid-plastic finite element method. CATIA (3D CAD program) was used for an extrusion metal mold design that was widely used in designing aircraft, automobile and metallic molds. A metal forming analysis program (ATES Co.) had a function of a rigid-plastic finite element method was used to analyze the program. The result of extrusion forming analysis indicated clearly that a shape retention of the manufactured artificial light-weight aggregate could be maintained by increasing the extrusion ratio (increasing compressive strength inside of extrusion die) and decreasing the die angle. The stress concentration of metal mold was increased by increasing an extrusion ratio, and it was higher in a junction of punch and materials, friction parts between a bottom of the punch and inside of a container, a place of die angle and a place of die of metal mold. Therefore, a heat treatment as well as a rounding treatment for stress distribution in the higher stress concentration regions were necessary to extend a lifetime of the metallic mold. A deformity of the products could have made from several factors which were a surface crack, a lack of the shape retention and a crack of inside of the products. Specially, the surface crack in the products was the most notably affected by the extrusion ratio.

• 한국축산시설환경학회지
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• 제5권3호
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• pp.189-196
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• 1999

Anaerobic digestion is a naturally occuring microbial process involving the decomposition of organic materials such as livestock manure. This study explores the effect of the operating conditions, HRT (Hydraulic Retention Time) and feeding frequency on treatment efficiency for digestion of pig slurry, which has been one of most difficult organic waste for proper treatment in livestock production industry in Korea at the present time. The pilot-scale CSTR of 5 m3 in volume was designed. manufactured, and operated at the temperature of 35$\pm$1$^{\circ}C$. The digester was designed to hydraulically stir for complete mixing and to supply heat from the water bath to maintain mesophilic temperature. The HRT of the digester for Test 1 and Test 2, and Test 3 was set for 17 days and 13 days respectively and pig slurry was fed once a day with 300$\ell$ each for Test 1 and Test 3, while twice with 150$\ell$each for Test 2. Test 2 showed better performance by increase of 4% in VS removal efficiency and 5% in biogas production rate. This is mainly attributed to smaller temperature drop by feeding frequently with half amount, which eventually led to lesser impact on anaerobic mocrobes in the digester. Test 2 maintained optimum pH 7.8 which uplifted the activaton of sulfur-reduction bacteria, alkalinity of around 4,000mg/$\ell$, VA of over 3,000mg/$\ell$ for whole period of experiment. Further research may require to provide the practical operation strategy of anaerobic treatment system for treatment of pig slurry.

• 산업식품공학
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• 제21권4호
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• pp.391-402
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• 2017

본 연구에서는 건조조건과 분쇄조건을 달리하거나 추출한 식물류의 영양성분 함량과 영양성분의 보존율을 비교분석하였다. 동결분쇄한 식물류는 일반분쇄 하거나 추출한 식물류에 비하여 영양성분의 보존율이 높은 것으로 나타났다. 인공생체막에서 영양성분의 투과도를 분석한 결과 동결분쇄한 식물류의 영양성분이 잘 투과하였다. 분쇄과정에서 열발생을 최소화하고 입도를 작게 하는 동결분쇄 기술이 식물류 원료를 우수한 식물소재로 가공할 수 있는 기술임을 확인하였다.

• 한국분말재료학회지
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• 제28권6호
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• pp.470-477
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• 2021

Energy storage systems should address issues such as power fluctuations and rapid charge-discharge; to meet this requirement, CoFe₂O₄ (CFO) spinel nanoparticles with a suitable electrical conductivity and various redox states are synthesized and used as electrode materials for supercapacitors. In particular, CFO electrodes combined with carbon nanofibers (CNFs) can provide long-term cycling stability by fabricating binder-free three-dimensional electrodes. In this study, CFO-decorated CNFs are prepared by electrospinning and a low-cost hydrothermal method. The effects of heat treatment, such as the activation of CNFs (ACNFs) and calcination of CFO-decorated CNFs (C-CFO/ACNFs), are investigated. The C-CFO/ACNF electrode exhibits a high specific capacitance of 142.9 F/g at a scan rate of 5 mV/s and superior rate capability of 77.6% capacitance retention at a high scan rate of 500 mV/s. This electrode also achieves the lowest charge transfer resistance of 0.0063 Ω and excellent cycling stability (93.5% retention after 5,000 cycles) because of the improved ion conductivity by pathway formation and structural stability. The results of our work are expected to open a new route for manufacturing hybrid capacitor electrodes containing the C-CFO/ACNF electrode that can be easily prepared with a low-cost and simple process with enhanced electrochemical performance.