• 한국자동차공학회논문집
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• 제13권2호
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• pp.135-141
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• 2005

Nitric oxide(NO) reduction by methanol was investigated over $La_2O_3$ catalysts in the presence and absence of oxygen. In the absence of $O_2$, $CH_3OH$ reduced NO to both $N_2$ and $N_2O$, with selectivity to $N_2$ formation decreasing from 81-88% at 623K to 47-71% at 723 K. With 1.2% $O_2$ in the feed, the rates were 4-8 times higher, but the selectivity to $N_2$ dropped from 50% at 623 K to 9% at 723 K. The specific activities with $La_2O_3$ for this reaction were higher than those for other reductants; for example, at 773 K with hydrogen a specific activity of $34\;{\mu}mol\;NO/sec{\cdot}m^2$ was obtained whereas that for methanol was $638\;{\mu}mol\;NO/sec{\cdot}m^2$. The Arrhenius plots were linear under differential reaction conditions, and the apparant activation energy was consistantly near 15 kcal/mol with $CH_3OH$. Linear partial pressure dependencies based on a power rate law were obtained and showed a near-zero order in $CH_3OH$ and a near-first order in $H_2$.

• 농업과학연구
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• 제19권2호
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• pp.238-268
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• 1992

Since rural people migrated to urban area as a result of rapid industrialization in Korea, a significant proportion on agricultural labor farces has consistently reduced and therefore incurred labor shortage in rural area which might aggravate the farm household's economy. This sutdy suggests a long run plan of supplying agricultural machines for forage cultivation based on the survery of 102 livestock farm housecholds conducted in 1987, aimed at curtailing the labor costs which would contribute to improving the livestock farming management. The results of this study are as follows: 1. Among the 102 livestock farm household surveyed, 50 farm housecholds were found to cultivate 398a of grassland on average while other 52 farm households produced the forage on the 169a of land under cultivation averagely. 2. Over 50 percent of farm houseolds were reported to have their own agricultural machine for harvesting and cutting, however rates of mechanization in other operations such as mowing and sowing were less than 20 percent. 3. There were more than 50 percent of livestock farm households who have shown their intention to buy and operate their own farming machines when proprer opportunities are given. 4. In order to estimate the long-run demand for agricultural machines for livestock farm household considering current mechanization procedure, data for the machine's optimal capacty, growth of arable acreage for feed stuffs was collected and analyzed. 5. Based on the estimated demand, long range supply plan of livestock farming machines for the period of 1990-2010 was suggested. 6. Finally, measures for technological developement and finanacial support were suggested to implement so as to encourage the farmers' adoption of agricultural machines, and to achieve the goal of mechanization planning for the livestock farm household.

• 생명과학회지
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• 제21권1호
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• pp.127-133
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• 2011

${\beta}$-galactosidase를 공유결합으로 키토산 담체에 고정화하여 고정화 효소의 특성을 조사하였다. 또한 충진층 반응기에서 연속 조업을 실시하여 공정 최적화를 실시하였다. 키토산 담체에 대한 효소 고정화 효율은 최대 75%을 나타내었다. 고정화 효소에 대한 최적의 pH는 7.0이었고 최적의 온도는 $50^{\circ}C$였다. pH와 온도의 실험 범위에서 고정화 효소가 자유 효소에 비해 넓은 분포를 보여 pH와 온도에 덜 민감하게 작용하였다. 충진층 반응기에서 고정화 효소의 운전에 대한 수학적 모델을 세우고 수치적으로 해를 구하였다. 투입되는 유당의 농도와 유량에 대해서 충진층 반응기의 출구에서 유당의 전환율을 측정하였다. 실험 결과를 경쟁적 저해 효소 반응식과 물질전달 저항을 고려한 수학적 모델의 결과와 비교하였다. 모델의 결과는 실험 결과를 5% 이내의 오차로 잘 예측하였다. 그리고 충진층 반응기의 길이에 따른 유당 전환율과 연속운전 시간에 따른 효소의 비활성화를 고려한 전환율을 모델로부터 예측하였다.

• 멤브레인
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• 제8권4호
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• pp.228-234
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• 1998

다양한 수질 오염원 중 페놀과 같은 유기화합물은 배출조건이 비정상적인 경우 기존의 처리방법으로 제거하거나 파괴하기 어렵다. 수용액으로부터 페놀을 분리하기 위한 최근의 연구들은 활성탄에 의한 흡착, 용매 추출 등에 의해 수행되어져 왔으며, 물-기름 유화에 기초를 둔 액막법이 기존의 기술들을 대체하기 위한 방법으로 시험되어져 왔다. 본 연구에서는 tri-n-butyl phosphate(TBP)와 액상 고분자를 지지액막의 액막용액으로 선정하여 수용액상의 페놀을 분리하였다. 공급측 페놀 농도를 변화시키고 다양한 액막용액을 사용하여 이들이 페놀분리에 미치는 효과를 연구하였다. TBP를 운반체로 사용한 경우의 실험결과들은 용매추출에서 주로 사용되고 있는 methyl isobutyl ketone(MIBK)보다 높은 물질전달속도를 보여주었으며, 선택한 액상고분자 중 polypropylene glycol 4000(PPG-4000), polybutylene glycol 500(PBG 500)의 경우 MIBK와 유사하거나 조금 높은 값을 나타내었다.

• Preventive Nutrition and Food Science
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• 제9권4호
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• pp.352-360
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• 2004

To investigate the antioxidative effects of an etbylacetate fraction extracted from the flowers of Chrysanthemum indicum L. (Chrysanthemi Flos) on the antioxidative system and lipid profiles of rats with ethanol induced hepatotoxicity. Sprague-Dawley rats weighing $100\~150$ g were divided into 5 groups: normal group (NOR), Chrysanthemi Flos EtOAC fraction (200 mg/kg) treated group (S1), $35\%$ etbanol (10 mL/kg) treated group (S2), Chrysanthemi Flos EtOAC fraction (200 mg/kg) and ethanol concomitantly treated group (S3) and Chrysanthemi Flos EtOAC fraction (400 mg/kg) and ethanol concomitantly treated group (S4), respectively. The antioxidative activity of each fraction was decreased in order of EtOAC, n-hexane, n-BuOH, water and chloroform. The growth rates and feed efficiency ratios were decreased by ethanol treatment, but were gradually restored to similar levels as in the NOR group by administering Chrysanthemi Flos EtOAC fraction. The whole blood concentrations of total cholesterol and LDL-cholesterol, and the activities of ALT and AST that were elevated by ethanol were significantly decreased in the Chrysanthemi Flos EtOAC fraction treated groups. It was also observed that the activities of SOD, catalase, xanthine oxidase and GSH-Px elevated by ethanol in rat liver were markedly decreased in the Chrysanthemi Flos EtOAC fraction treated group as compared to S2. These results suggest that Chrysanthemi Flos EtOAC fraction has possible protective effects against ethanol induced hepatotoxicity in rat liver.

• 한국의류학회지
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• 제35권11호
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• pp.1297-1308
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• 2011

This research investigates the application of ZnO (zinc oxide) nanoparticles and $TiO_2$ (titanium dioxide) nanoparticles to polypropylene nonwoven fabrics via an electrospinning technique for the development of textile materials that can decompose harmful gases. To fabricate uniform ZnO nanocomposite fibers, two types of ZnO nanoparticles were applied. Colloidal $TiO_2$ nanoparticles were chosen to fabricate $TiO_2$ nano- composite fibers. ZnO/poly(vinyl alcohol) (PVA) and $TiO_2$/PVA nanocomposite fibers were electrospun under a variety of conditions that include various feed rates, electric voltages, and capillary diameters. The morphology of electrospun nanocomposite fibers was examined with a field-emission scanning electron micro- scope and a transmission electron microscope. Decomposition efficiency of gaseous materials (formaldehyde, ammonia, toluene, benzene, nitrogen dioxide, sulfur dioxide) by nanocomposite fiber webs with 3wt% nano-particles (ZnO or $TiO_2$) and 7$g/m^2$ web area density was assessed. This study shows that ZnO nanoparticles in colloid were more suitable for fabricating nanocomposite fibers in which nanoparticles are evenly dispersed than in powder. A heat treatment was applied to water-soluble PVA nanofiber webs in order to stabilize the electrospun nanocomposite fibrous structure against dissolution in water. ZnO/PVA and $TiO_2$/PVA nanofiber webs exhibited a range of degradation efficiency for different types of gases. For nitrogen dioxide, the degradation efficiency was 92.2% for ZnO nanocomposite fiber web and 87% for $TiO_2$ nanocomposite fiber web after 20 hours of UV light irradiation. The results indicate that ZnO/PVA and $TiO_2$/PVA nano- composite fiber webs have possible uses in functional textiles that can decompose harmful gases.

• 한국동물위생학회지
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• 제28권2호
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• pp.99-106
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• 2005

This survey was carried out to investigate the seroprevalence of antibodies to Neospora caninum in Korean indigenous cattle that was representative livestock raised in Jeongeup province Jeonbuk Korea. A total of 1,162 sera were tested for N caninum antibodies using ELISA (Herdcheck anti-Neospora. IDEXX Laboratories Inc., Westbrook, Maine USA). $15(1.3\%)$ sera were positive by ELISA. A total of 290 farms were tested. $11(3.8\%)$ farms were positive. Among the seroprevalence of cattle according to the areas, 8 of 44 counties were infected N caninum. Sero-positive 11 farms of N caninum antibodies using ELISA test and 62 of 301 sera $(20.6\%)$ were infected to N caninum. We found that cattle be raised in Jeongeup province was slightly infected to N caninum. It seems to be infected of N caninum an early stage. but the positive rates was variable that it was $6\%\~62\%$. It was supposed to the highest positive rate of 3 farms had some factors to be infected. The factors were supposed to keep dogs yearly, located the base of hills, and almost feed with imported dried grass. Farmers suppose to the cause of abortion was not the neosporosis but also broke out an accident or was infected Brucella spp. The results of Brucella Rose Bengal Test (RBT) were all negative.

• 한국수산과학회지
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• 제32권4호
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• pp.391-394
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• 1999

참전복용 배합사료에 비타민 및 미네랄 혼합물의 첨가 효과를 조사하기 위해 실용적인 배합비에 비타민 혼합물 ($0\~2\%$)과 미네랄 혼합물 ($0\~6\%$)을 각각 달리 첨가한 사료로 평균체중 100mg의 참전복 치패를 3반복으로 4개월간 사육실험한 결과, 최종 평균 체중, 증체율, 가식부 중량, 체중에 대한 가식부 중량 비, 각장, 각폭 및 각장에 대한 체중 비의 값들은 사료의 비타민 및 미네랄에 영향을 받지 않았다 (P>0.05). 또한, 생존율과 가식부의 일반성분은 실험구간에 유의적은 차이를 보이는 실험구가 있기는 하였으나, 사료의 비타민이나 미네랄의 첨가수준에 따른 차이는 아니었다. 이상의 결과로부터 본 실험의 사료 배합비에는 비타민 혼합물과 미네랄 혼합물은 별도로 보충하지 않아도 될 것으로 판단되며, 그 만큼 사료단가를 절감시킬 수 있을 것으로 기대된다.

• 모자간호학회지
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• 제1권
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• pp.45-58
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• 1991

The purpose of this descriptive study was to investigate the determinants of mother's choice of infant feeding method on immediate postpartum period & the breast feeding practice after 1, 2, 3, 4, 5months. The subjects were 170 mothers who were delivered at 2 hospital, 2 OBGY clinics, 1 midwifery in Jinju, the data were collected from Jan. 1 to Feb. 20 of 1991, form each subject at two periods of time ; postpartum 2 or 3 days via interview, 5months via telephone interview. The results were as fellows : 1. The propotion of mother planned exclusive breast-feeding was 66.5%, milk feeding 17.6%, mixed feeding 15.9%, End 38.9% of mothers planned to breast-feed their infants for 4-6moths, 25.7% for more than 12 months. The major reasons for selection of milk feeding method were the presence of mother's job(26.7%), the conditions of breast & milk production(23.7%). 2. There were significant relations between the choice of feeding method & the presence of s job(p<.01), & parity(p<.01). 3. The percentages of subjects that were received education about the advantages & method of breast feeding were 63.5%, 38.2%, respectively, & the informants were mass media, 89.8%, 81.5%. 4. The most of mothers had the knowledge about the advantages of breast feeding. 5. The percentage of mothers that practiced breast feeding on postpartum were 75.9%. 6. The rates of breast feeding practice by duration were more than 5months, 60.5%, 1 month, 27.1%, 2-4 months. 12.3%. 7. The reasons for the stop of breast feeding were the decrease of milk volume(22.9%), the presence of mother's job(17.4%). 8. The duration of breast feeding practice were differed significantly by the presence of mother's job, type of delivery, rooming-in, planned duration of breast feeding, the first feeding time.

• Journal of Animal Science and Technology
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• 제63권4호
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• pp.759-765
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• 2021

Recently, summer temperatures have frequently been abnormal in Korea owing to global warming. In summer, a decrease in feed intake rate and biological activity were observed in Hanwoo (Korean Native Cattle), leading to lower production rates in the industry. However, the precise scale of damage was not reported as with other animals of economic value. This study was conducted to investigate the effects of birth season on birth weight in Hanwoo. Data were collected from 100 local breeding farms from 2016 to 2019. A total of 41,081 Hanwoo calves were classified and analyzed by sex, year, month, and season (March-May, spring; June-August, summer; September-November, fall; and December-February, winter) of birth. The birth weight of Hanwoo calves differed according to birth month. The average birth weight of male calves was 30.47 kg and that of female calves was 28.16 kg. Hanwoo birth weight was the highest in March-born calves and the lowest in July-born calves. The birth weights of calves born in February, March, April, November, and December were significantly larger than those of calves born in July. In addition, the birth weight of Hanwoo calves from the summer was significantly lower than that of calves born in other seasons. Furthermore, Hanwoo steer slaughter age showed a negative correlation, whereas carcass weight had a positive correlation with birth weight. In the beef cattle industry, birth weight is a very important economic characteristic that is related to growth rate. These data will contribute toward planning the reproduction of Hanwoo and analysis of changes in characteristics of economic value owing to high temperatures.