• 한국농공학회논문집
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• 제62권2호
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• pp.31-38
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• 2020

Controlled Low Strength Material (CLSM) has high fluidity and self-compaction characteristics. CLSM is mainly used for backfilling the excavated road. Early-age properties of CLSM should be characterized for fast restoration of the road. In this study, shear wave monitoring and Vicat needle test are performed to investigate the early-age properties of CLSM depending on the setting time. CLSM consists of CSA cement, fly ash, silt and sand, accelerator, and water. Five fly ashes with different chemical properties are used for CLSM samples. The penetration of CLSM along setting time is obtained through the Vicat needle test. A pair of bender elements are placed in a mold for shear wave measurement, and the change in shear waves with the setting time is monitored. The experimental results show that, regardless of the type of fly ash, the penetration depth decreases and the shear wave velocity increases with the setting time. Depending on the type of fly ash, initial and final times and shear wave velocity change. After testing, the correlation between penetration and shear wave velocity is obtained with high coefficient of determination. The shear wave measurement technique using the bender element can be used to identify early-age properties.

• Asian-Australasian Journal of Animal Sciences
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• 제14권6호
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• pp.797-802
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• 2001

Two strains of rumen fungi (Piromyces rhizinflata B157, Orpinomyces joyonii SG4) and three strains of rumen cellulolytic bacteria (Ruminococcus albus B199, Ruminococcus flavefaciens FD1 and Fibrobacter succinogenes S85) were used as mono-cultures or combinationally arranged as co- and sequential-cultures to assess the relative contributions and interactions between rumen fungi and cellulolytic bacteria on rice straw degradation. The rates of dry matter degradation of co-cultures were similar to those of corresponding bacterial mono-cultures. Compared to corresponding sequential-cultures, the degradation of rice straw was reduced in all co-cultures (P<0.01). Regardless of the microbial species, the cellulolytic bacteria seemed to inhibit the degradation of rice straw by rumen fungi. The high efficiency of fungal cellulolysis seems to affect bacterial degradation rates.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 2000년도 THE THIRD INTERNATIONAL CONFERENCE ON AGRICULTURAL MACHINERY ENGINEERING. V.II
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• pp.132-138
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• 2000

Complex gear shifting and high speed-reduction ratio reduce the transmission efficiency in power driveline of agricultural tractors. According to a field test, the power transmission efficiency of a tractor in transporting operations was estimated about 70%. However, the actual efficiency was found by the experiment to fluctuate in a range of 56 to 87%. Therefore, the constant efficiency model commonly used for a simulation of power drivelines is not likely to simulate its performance more accurately. In order to predict power transmission efficiency more accurately, a new model was proposed and the new concepts of the maximum efficiency and sticking torque were introduced. The error mean between the measured and the predicted efficiencies was about 2.3% in mean. The new model reflecting the transmission characteristics in the power driveline of tractors could be used to analyze and predict the power transmission performance of tractors more accurately.

• 한국농공학회논문집
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• 제63권5호
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• pp.95-105
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• 2021

Drought is a disaster that causes prolonged and wide scale damage. Recently, the severity and frequency of drought occurrences, and drought damage have been increased significantly due to climate change. As a result, a quantitative study of drought factors is needed to better understand and prevent future droughts. In the case of agricultural drought, several existing studies examine the economic damage caused by droughts and their causes, but these studies are not well suited to estimating crop-oriented agricultural drought damage and the factors that absolutely affect agricultural drought. This study determines which factors most affect agricultural drought. It examines meteorological factors and those related to agricultural water supplied by irrigation facilities. Rice paddy production per unit area is lower than the average from the last two years where agricultural drought occurred. We compare the relative frequency of agricultural drought impacts with irrigation facilities, effective reservoir storage, the number of water supply facilities, and the meteorological drought index such as Standardized Precipitation Index (SPI). To identify factors that affect agricultural drought, we correlate rice paddy production anomalies with irrigation water supply for the past two years. There was a high positive correlation between rice paddy production and irrigation water usage, and there was a low or moderate negative correlation between rice paddy production anomalies compared to the average of the past two years and SPI. As a result, agricultural water supply by irrigation facilities was judged to be more influential than meteorological factors in rice paddy production. This study is expected to help local governments establish policies related to agricultural drought response.

• 한국잠사곤충학회지
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• 제53권1호
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• pp.29-37
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• 2015

2009년 개정된 고등학교 생물 교과서(I, II) 8개 출판사에 게재된 곤충 및 거미류 목록은 다음과 같다. 1. 조사된 분류군은 곤충 및 거미강 등 총 2강이었고, 게재된 빈도수는 총 143회이었다. 2. 조사된 곤충강은 나비목, 딱정벌레목 등 총 12개목이었고, 거미강은 거미목, 진드기목 등 총 2개목 이었다. 3. 출현빈도수가 가장 높은 곤충은 나비목으로 총 33회, 거미강 거미목은 11회 게재되었다. 4. 출판사별 분석에서는 주)교학사가 23회, 주)형설과 주)중앙교육진흥원으로 각각 21회 조사되었다. 5. 분석한 교과서에서 총 4종이 오동정 되었고, 5곳에서 사진 및 내용상 오류가 조사되었다.

• 농촌지도와개발
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• 제16권4호
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• pp.869-912
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• 2009

The objective of this study is to promote alternative plans on the prejudiced and distorted contents in school textbooks in the aspect of multi-functionality of agriculture and rural community. This was done through analysis of contents in 47 kinds of textbooks in science (8 of elementary school, 27 of middle school and 12 of high school). This will lead to promote understanding about the multi-functionality and form the proper value system related to agriculture and rural community for children and juveniles using textbooks. A content analysis was employed to examine to what extent the contents on agriculture and rural community were reflected in the textbooks for elementary school, middle school and high school. The content analysis was done in three categories, including presentation form, application method and function view. The followings are results of contents analysis in textbooks. The most frequently used presentation forms related to agriculture and rural community was figures and tables. In analysis of application methods, this research found that the contents related to agriculture and rural community were used to explain scientific facts and phenomena. In the function view, maintenance of local societies was most frequent among the various multi-functionalities in elementary and middle school, and food security in high school. Based on the results of content analysis, findings and recommendations in textbooks for elementary, middle and high school have been drawn, and several examples for contents development to be included in the textbooks were listed.

• Journal of Biosystems Engineering
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• 제43권4호
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• pp.386-393
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• 2018

Purpose: Chicken cutting is done manually, which is inefficient, unhygienic, and carries a high accident risk during processing. This study develops and evaluates an automatic chicken cutting machine that suits small-scale workplaces. Methods: This study developed an automatic chicken cutting machine equipped with four traverse blades and two longitudinal blades. An experiment was conducted with various blade rotating speeds and tray feed rates to evaluate the machine's performance. The chicken loss rate and chicken piece weights were measured to calculate the coefficient of variation (CV), thereby determining processing uniformity. Results: The optimal cutting conditions with the smallest chicken loss rate were 0.05 m/s tray feed speed and 18.8 m/s and 16.4 m/s for the traverse and longitudinal blades, respectively. The processing ran at 55.3 chickens per hour and the chicken pieces were more uniform when using the device than for hand-work processed pieces. Conclusions: The loss rate increased in proportion to the cutting-blade rotation speed due to the high cutting rate in meat. The loss rate also increased as the tray feed speed slowed because the cutting blade pushed the chicken meat. The tray feed speed should be increased to improve the amount processed per hour.

• Asian-Australasian Journal of Animal Sciences
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• 제22권2호
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• pp.162-167
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• 2009

Reproductive abilities in beef cattle herds are receiving increased attention due to recent rises in production costs. To achieve more efficient management, a measure of fertility, namely the number of calves produced at k yr of age ($NCP_k$), was developed and its genetic parameters were estimated from Japanese Black cows by restricted maximum likelihood procedures. The k examined were distributed from 2 to 10 yr of age and $NCP_2$ averaged 1.077 calves over 43,536 cows. The averages increased by approximately 0.9 calf with each additional 1 yr increment in k. Heritabilities of $NCP_k$ were estimated to be low ranging from 0.083 to 0.162, which seemingly suggested a difficulty of genetic improvement. However, large genetic variation and high accuracy were observed in predicted breeding values of $NCP_k$. For example, the breeding values of $NCP_7$ were predicted between -0.303 and +0.213 with average accuracy of 0.607 for cows with observations. Genetic correlations among different k were generally high and positive (0.474 to 0.995). The analyses showed that at least $NCP_4$ was required to maintain the genetic correlations of 0.8 or higher with subsequent $NCP_k$. Also $NCP_5$ maintained the genetic correlations of 0.9 or higher with subsequent $NCP_k$ The results suggested some possibilities for $NCP_k$ to be a selection criterion considering its genetic variation, high accuracy and consistency with subsequent performance.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2017년도 9th Asian Crop Science Association conference
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• pp.21-21
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• 2017

Severe lodging has recurrently occurred at strong typhoon's hitting in recent climate change. The identification of quantitative trait loci (QTLs) and their responsible genes associated with a strong culm and their pyramiding are important for developing high-yielding varieties with a superior lodging resistance. To identify QTLs for lodging resistance, the tropical japonica line, Chugoku 117 and the improved indica variety, Habataki were selected as the donor parent, as these had thick and strong culms compared with the temperate japonica varieties in Japan such as Koshihikari. By using chromosome segment substitution lines (CSSLs) in which chromosome segments from the japonica variety were replaced to them from Habataki, we identified the QTLs for strong culm on chrs. 1 and 6, which were designated as STRONG CULM1 (SCM1) and STRONG CULM2 (SCM2), respectively. By using recombinant inbred lines (BILs) derived from a cross between Chugoku 117 and Koshihikari and introgression lines, we also identified the other QTLs for strong culm on chrs. 3 and 2, which were designated as STRONG CULM3 (SCM3) and STRONG CULM4 (SCM4), respectively. Candidate region of SCM1 includes Gn1 related to grain number. SCM2 was identical to APO1, a gene related to the control of panicle branch number, and SCM3 was identical to FC1, a strigolactone signaling associated gene, by performing fine mapping and positional cloning of these genes. To evaluate the effects of SCM1~SCM4 on lodging resistance, the Koshihiakri near isogenic line (NIL) with the introgressed SCM1 or SCM2 locus of Habataki (NIL-SCM1, NIL-SCM2) and the another Koshihikari NIL with the introgeressed SCM3 or SCM4 locus of Chugoku 117 (NIL-SCM3, NIL-SCM4) were developed. Then, we developed the pyramiding lines with double or triple combinations derived from step-by-step crosses among NIL-SCM1 NIL-SCM4. Triple pyramiding lines (NIL-SCM1+2+3, ~ NIL-SCM1+3+4) showed the largest culm diameter and the highest culm strength among the combinations and increased spikelet number due to the pleiotropic effects of these genes. Pyramiding of strong culm genes resulted in much increased culm thickness, culm strength and spikelet number due to their additive effect. SCM1 mainly contributed to enhance their pyramiding effect. These results in this study suggest the importance of identifying the combinations of superior alleles of strong culm genes among natural variation and pyramiding these genes for improving high-yielding varieties with a superior lodging resistance.

• 농약과학회지
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• 제20권2호
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• pp.159-164
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• 2016

꽈리허리노린재(Acanthocoris sordidus)는 흡즙성 해충으로서 가지과 작물을 주로 가해하며, 국내에서는 일부 고추농가에 피해를 주고 있다. 이러한 꽈리허리노린재를 방제하기 위하여 유기합성 살충제 20 종류와 7 종류의 친환경유기농자재를 이용하여 살충력을 알아보았다. 그 결과, 꽈리허리노린재 성충의 경우에는 약제처리 72시간이 경과한 후에 유기인계 살충제인 펜티온이 100%의 살충율을 나타내었고, 페니트로티온과 펜토에이트는 95% 이상의 살충률을 나타내었다. 3령 약충의 경우에는 펜티온과 페니트로티온, 펜토에이트가 72시간이 경과한 후에 100%의 살충력을 나타내었다. 반면에 친환경유기농자재의 경우에는 고삼추출물이 80% 함유된 약제를 처리한 결과 성충이 약제처리 72시간 후 53.3%의 살충력을 나타내었을 뿐 다른 약제들은 대부분 살충력이 없거나 저조하였다.