• Korean Journal of Materials Research
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• v.23 no.10
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• pp.568-573
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• 2013

The deformation properties of a TiC-Mo eutectic composite were investigated in a compression test at temperatures ranging from room temperature to 2053 K and at strain rates ranging from $3.9{\times}10^{-5}s^{-1}$ to $4.9{\times}10^{-3}s^{-1}$. It was found that this material shows excellent high-temperature strength as well as appreciable room-temperature toughness, suggesting that the material is a good candidate for high-temperature application as a structure material. At a low-temperature, high strength is observed. The deformation behavior is different among the three temperature ranges tested here, i.e., low, intermediate and high. At an intermediate temperature, no yield drop occurs, and from the beginning the work hardening level is high. At a high temperature, a yield drop occurs again, after which deformation proceeds with nearly constant stress. The temperature- and yield-stress-dependence of the strain is the strongest in this case among the three temperature ranges. The observed high-temperature deformation behavior suggests that the excellent high-temperature strength is due to the constraining of the deformation in the Mo phase by the thin TiC components, which is considerably stronger than bulk TiC. It is also concluded that the appreciable room-temperature toughness is ascribed to the frequent branching of crack paths as well as to the plastic deformation of the Mo phase.

• Korean Chemical Engineering Research
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• v.54 no.5
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• pp.587-592
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• 2016

Sodium borohydride, $NaBH_4$, shows a number of advantages as hydrogen source for portable proton exchange membrane fuel cells (PEMFCs). Properties of $NaBH_4$ hydrolysis reaction using unsupported Co-P-B Co-B, catalyst at high concentration $NaBH_4$ solution were studied. In order to enhance the hydrogen generation yield at high concentration of $NaBH_4$, the effect of catalyst type, $NaBH_4$ concentration and recovery of condensing water on the hydrogen yield were measured. The yield of hydrogen evolution increased as the boron ratio increased in preparation process of Co-P-B catalyst. The hydrogen yield decreased as the concentration increased from 20 wt% to 25 wt% in $NaBH_4$ solution during hydrolysis reaction using 1:5 Co-P-B catalyst. Maximum hydrogen yield of 96.4% obtained by recovery of condensing water and thinning of catalyst pack thickness in reactor using Co-P-B with Co-B catalyst and 25 wt% $NaBH_4$ solution.

• Proceedings of the Korean Society of Crop Science Conference
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• 2000.04a
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• pp.248-249
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• 2000

• Journal of Ginseng Research
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• v.15 no.3
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• pp.197-199
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• 1991

Growth of ginseng and physical properties of soil were compared with bed height in experimental plots of sand loam for four year and clay loam soil for three year old ginseng plants, respectively. Field survey was also carried out to compare yield and soil physical properties with bed height in the same fold of six years old ginseng fields. High yield of ginseng root was observed at high bed both in the experimental plots and field survey as well. The rate of rusty root was significantly reduced at high bed. Soil porosity increased but soil hardness decreased at high bed.

• Journal of Veterinary Clinics
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• v.30 no.3
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• pp.178-185
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• 2013

This study evaluated the effects of milk yield on the postpartum health and reproductive performance of dairy cows. In total, data were collected from 1,060 cows on six dairy farms, including their milk production, body condition score (BCS), postpartum disorders, and reproductive performance. The lactation data were grouped based on the 305-day milk yield into control (< 10,000 kg, n = 445) and high milk yield (${\geq}$ 10,000 kg, n = 615) groups. The milk fat and protein, and BCS were lower during the first 5 months postpartum in the high milk yield group compared with the control group (p < 0.01). Ovarian cysts were more frequent (p < 0.0001) in the high milk yield group (28.6%) than in the control group (15.3%), whereas endometritis tended to be less frequent in the high milk yield group (29.6%) than in the control group (35.1%, p = 0.06). A higher proportion of cows tended to receive reproductive hormones (p = 0.06) in the high milk yield group (62.4%) than in the control group (56.6%). The probability of a pregnancy after first insemination tended to be lower (odds ratio = 0.78, p = 0.07) in the high milk yield group (30.2%) than in the control group (35.2%). Furthermore, the hazard of pregnancy by 210 days in milk was lower in the high milk yield group (hazard ratio = 0.84, p = 0.04) than in the control group, which resulted in a 20-day increase in the median interval to pregnancy. In conclusion, high milk yield was related to lower milk fat and protein, lower BCS, an increased incidence of ovarian cysts, and increased use of reproductive hormones, which resulted in decreased reproductive performance of dairy cows.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.24 no.2
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• pp.35-41
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• 1979

To observe the effects of temperature and photoperiod on the growth and yield of winter wheat (Triticum aestivum, L) eight varieties including Chang Kwang were tested at various treatments like longday-high temperature (24hrs-20\circ), shortdayhigh temperature (12hrs-20\circ), longday-low temperature (24hrs-14\circ) and shortday-low temperature (12hrs-14\circ). Among the traits measured, days to heading, plant height, spike length, number of spikes per hill and grain yield per hill were generally decreased at high temperature and long day treatment and increased at low temperature and shortday condition. Number of grains per spike was decreased at low temperature and short day condition while increased at longday and high temperature conditions. Grain weight was decreased significantly at high temperature and shortday while increased at low temperature and longday treatment.

• Advances in nano research
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• v.14 no.3
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• pp.225-234
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• 2023

In this study, we aim to use big data resources and statistical analysis to obtain a reliable instruction to reach high-quality and high yield agricultural yields. In this regard, soil type data, raining and temperature data as well as wheat production in each year are collected for a specific region. Using statistical methodology, the acquired data was cleaned to remove incomplete and defective data. Afterwards, using several classification methods in machine learning we tried to distinguish between different factors and their influence on the final crop yields. Comparing the proposed models' prediction using statistical quantities correlation factor and mean squared error between predicted values of the crop yield and actual values the efficacy of machine learning methods is discussed. The results of the analysis show high accuracy of machine learning methods in the prediction of the crop yields. Moreover, it is indicated that the random forest (RF) classification approach provides best results among other classification methods utilized in this study.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.43-43
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• 2017

During grain filling period, rice is affected by many environmental factors; including temperature, water, radiation and soil nutrition condition. In future climate, greater shading and heat tolerance will be required in rice. In this study, the effect of shading and high temperature on spikelet sterility was conducted on fourteen Vietnamese cultivars. Field experiments were studied in 2015 and 2016 to evaluate the response of Vietnamese cultivars under high temperature during grain filling stage. The high temperature and shading were applied by closing two sides of growth chamber and covered by a black cloth (50% reduced solar radiation) under the field condition after the first cultivar heading. The sterility increased significantly under high temperature and shading. The highest percentage sterile spiketlets was observed in 'Jasmine 85' (71.7%) under shading and in 'OM4900' (53.4%) under high temperature in 2015 and 2016, respectively. Among the treatments, the percentage of sterile spekelets in Vietnamese cultivars under shading was highest which was 54.9% and 41.8% in 2015 and 2016, respectively. Yield components reduced significantly in both of shading and high temperature. Corresponding with significantly decrease in yield components, the yield in high temperature and shading decreased strongly in both 2015 and 2016.

• Journal of Information Technology Applications and Management
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• v.15 no.1
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• pp.243-260
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• 2008

To prevent low yields in the semiconductor industry is crucial to the success of that industry. However, to prevent low yields is difficult because of too many factors to affect yield variation and their complex relation in the semiconductor manufacturing process. This study presents a new efficient detection methodology for detecting abnormal yields including high and low yields, which can forecast the yield level of a production unit (namely a lot) based on yield-related feature variables' behaviors. In the methodology, we use C5.0 to identify the yield-related feature variables that are the combination of correlated process variables associated with yield, use SOM (Self-Organizing Map) neural networks to extract and classify significant patterns of past abnormal yield lots and finally use C5.0 to generate classification rules for detecting abnormal yield lot. We illustrate the effectiveness of our methodology using a semiconductor manufacturing company's field data.

• Journal of Environmental Science International
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• v.21 no.12
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• pp.1503-1510
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• 2012

The purpose of this article is analyzing the impacts of climate change on red pepper yield in Korea, with employing a panel data regression model. Our results show that there is a negative impacts of high temperature and precipitation amount on red pepper yields. Especially high temperature and rainfall in July cause serious damage to red pepper yield. According to the reduction schedule on greenhouse gas emission(RCP 8.5 scenario.), red pepper yield would be 25.4% lower than it is, for reasons of high temperature and rainfall damages by the end of 21st century.