• 한국지반공학회논문집
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• 제26권11호
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• pp.111-123
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• 2010

강관합성 현장타설말뚝은 굴착시 공벽보호를 위해 사용되는 강관케이싱을 구조재로 보고 내부에 콘크리트를 채운 합성말뚝으로서 외부 강관이 내부 콘크리트의 변형을 억제하여 말뚝의 강도를 증가시키고 연성파괴를 유도하는 보강 효과를 발휘한다. 본 연구에서는 강관합성 현장타설말뚝의 현장 적용성을 분석하기 위하여 현장재하시험을 수행하였다. 시험결과 강관 선단부 즉, 강관합성-콘크리트 경계면이 구조적으로 취약하며 휨에 대한 저항력이 작기 때문에 내부 철근망을 설치하여 이 부분을 보강할 필요가 있었다. 또한 강관합성-콘크리트 경계면이 휨모멘트의 영향을 받지 않는 충분히 갚은 깊이에 위치하고 주변지반의 구속효과가 발휘되는 경우에는 강관합성 현장타설말뚝의 하부 콘크리트 재료에 대한 허용강도가 증가하므로 강관합성 현장타설말뚝의 설계하중을 증가시켜 경제적인 설계가 기능해질 수 있을 것으로 판단된다.

• Computers and Concrete
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• 제18권3호
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• pp.297-317
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• 2016

Current codes recommend large amounts of shear reinforcement for reinforced concrete beam-column joints that causes significant bar congestion. Increase in congestion of shear reinforcement in joint core (connection zone), leads to increase accomplishment problems. The congestion may also lead to diameter limitations on the beam bars relative to the joint dimensions. Using double headed studs instead of conventional closed hoops in reinforced concrete beam-column joints reduces congestion and ensures easier assembly of the reinforcing cage. The purpose of this research is evaluating the efficiency of the proposed reinforcement. In this way, 10 groups of exterior beam-column joints are modeled. Each group includes 7 specimens by different reinforcing details in their joint core. All specimens are modeled by using of ABAQUS and analyzed subjected to cyclic loading. After verification of analytical modeling with an experimental specimen, 3D nonlinear specimens are modeled and analyzed. Then, the effect of amount and arrangement of headed studs on ductility, performance, ultimate strength and energy absorption has been studied. Based on the results, all joints reinforced with double headed studs represent better performance compared with the joints without shear transverse reinforcement in joints core. The behavior of the former is close to joints reinforced with closed hoops and cross ties according to the seismic design codes. By adjusting the arrangement of double-headed studs, the decrease in ductility, performance, ultimate moment resistant and energy absorption reduce to 2.61%, 0.90%, 0.90% and 1.66% respectively compared with the joints reinforced by closed hoops on the average. Since the use of headed studs reduces accomplishment problems, these amounts are negligible. Therefore, use of double-headed studs has proved to be a viable option for reinforcing exterior beam-column joints.

• Asian-Australasian Journal of Animal Sciences
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• 제12권3호
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• pp.417-421
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• 1999

This experiment examined the effects of feeding Aspergillus oryzae (AO) culture to laying hens, on fecal microbial populations, fecal pH and moisture content, egg quality, and metabolizabilities of several nutrients. Sixteen commercial 38-wk-old laying hens were randomly allotted to four diets: control; with 0.15% locally produced AO culture; with 0.3% locally produced AO culture, and; or with 0.3% imported AO. Each treatment consisted of four replicates (cages) containing one bird per cage according to a completely randomized design. After 4 wk, AO were recovered in the feces of birds fed the AO diets, indicating that AO might pass through the fore-gut alive and become active in the hind gut. The number of Lactobacillus spp. in feces was higher in all treated groups than that of the control, indicating that AO would provide a beneficial environment for the Lactobacillus spp. to proliferate in the intestine. The number of fecal E. coli was significantly reduced by the addition of AO. A similar trend was also found for aerobic bacteria. Although not significant, fecal moisture contents tended to be reduced by the addition of AO. Fecal pH was not significantly different among the treatments. The addition of AO did not affect the various economic traits of eggs. Metabolizabilities of gross energy and dry matter measured during the 5th wk were increased by the AO supplementation. It appears that AO culture alone could be used as a probiotic supplement for layers.

• 농업과학연구
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• 제46권4호
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• pp.991-997
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• 2019

This study was conducted to investigate the laying period performance of two crossbred Korean native chicken (KNC) grand parent stock (GPS) layer during 20 to 40 weeks. A total of 351 20-week-old KNC GPS were allocated in a completely randomized design to give 4 birds per each cage. The chickens were fed commercial diets [i.e., week 20 - 32, crude protein (CP) 18.0% and metabolizable energy (ME) 2,850 kcal/kg; week 32 - 40, CP 17.0% and ME 2,800 kcal/kg)] and fresh water during the whole experiment period ad libitum basis. Body weight, age of sexual maturity, egg weight, hen-day egg production (HDP) and feed conversion ratio (FCR) were measured during the experiment period (week 20 - 40). The results show no significant difference in the Body weight, age of sexual maturity, egg weight, and hen-day egg production (HDP) except for egg weight. 1B had a higher egg weight on week 36 only. We expect that the reason why most factors showed no significant difference is the lack of nutrients caused by limited feeding which follows the standard feeding system for the grand-parent stock. These results provide basic information for laying data in 2-way crossbred Korean native chickens.

• Asian-Australasian Journal of Animal Sciences
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• 제8권4호
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• pp.379-385
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• 1995

Ninety Wistar male rats were used to study the effects of vitamin E and Se supplementation to diets containing aflatoxin $B_1$ on the contents of liver lipids and various blood parameters. Two levels of dietary aflatoxin (0 and 1 ppm), 3 levels of vitamin E (30, 60 and 120 IU/kg), and 3 levels of Se (0.1, 1 and 2 ppm) were used to design a $2{\times}3{\times}3$ factorial experiment. Rats, weighing about 200 g, were randomly allotted to 18 cages, 5 rats per cage. The aflatoxin significantly (p < .05) decreased growth rate, feed intake and feed efficiency. Aflatoxin increased the glucose level and decreased the cholesterol level in blood significantly. Levels of blood triglyceride, total protein, and albumin were not affected by aflatoxin, vitamin E or Se. Activities of blood alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were significantly increased by aflatoxin; however, the glutathione peroxidase (GSH-Px) activity in the blood was decreased by aflatoxin even in the presence of Se. The vitamin E supplementation decreased the AST activity significantly, while GSH-Px activity increased significantly as the levels of dietary Se increased. The levels of total cholesterol and free cholesterol in the liver were significantly lower in rats receiving aflatoxin, while the extra vitamin E supplementation increased these hepatic cholesterol levels. It was concluded that the extra dietary vitamin E or Se supplementation might partially alleviate some of the harmful effects of aflatoxin in rats.

• 대한토목학회논문집
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• 제31권5D호
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• pp.705-717
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• 2011

타워크레인은 건설현장의 전체 자재인양 중 약 50%의 물량을 인양하는 양중 장비로 그 수는 빠른 속도로 증가하고 있으나, 건설현장에서의 소홀한 안전관리로 타워크레인 관련 안전사고는 매년 지속적으로 발생되고 있는 실정이다. 특히, 텔레스코핑 작업은 타워크레인 설치단계에서 텔레스코핑 케이지를 유압으로 상승시킨 후 생긴 빈 공간에 새로운 마스트를 삽입하여 요구 높이까지 상승시키는 작업으로 고소에서 다수의 작업자가 동시에 작업을 실시하여 추락 및 낙하의 위험성이 존재하는 등 타 작업에 비해 재해사례 비중이 가장 높은 것으로 분석되었다. 본 연구의 목적은 타워크레인 작업 중 특히 위험성이 높은 것으로 조사 및 분석된 텔레스코핑 작업의 안전성 및 생산성을 향상시킬 수 있는 타워크레인 텔레스코핑 자동화기술의 개념모델을 제안하고 이에 대한 안전성 측면에서의 잠재적 성능을 분석함으로써 향후 타워크레인 텔레스코핑 자동화기술 실물 제작을 위한 원천자료를 제공하는 것이다.

• 한국가금학회지
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• 제47권3호
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• pp.153-158
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• 2020

The effects of palm oil and soy oil supplementation in broiler chickens on growth performance and nutrient digestibility of dry matter, nitrogen, and energy was evaluated. In this experiment, 702 one-day-old Ross 308 cross bred chicks with an initial body weight of 42.23±0.05 g (mean±SD) were utilized in a completely randomized treatment design (13 replicates/treatment, 18 chickens/cage) and fed for 35 days with CON (basal diet), T1 (Basal diet + 1.3 % palm oil), and T2 (Basal diet + 1.3% soy oil). From days 1 to 7, the body weight gain (BWG), feed intake (FI), and feed conversion ratio (FCR) were not significantly affected by the supplementation with palm oil or soy oil. However, from days 7 to 21, BWG showed a tendency to increase compared to that with the control treatment. Moreover, BWG was significantly improved (P<0.05) with palm and soy oil supplementation during the overall experiment in comparison to that with the control diet. In addition, the palm oil-supplemented group had higher BWG than the soy oil treatment group (P<0.05). During the overall experiment, FI tended to increase in the T1 group compared to that in the other groups. There was no significant effect on FCR and nutrient digestibility of dry matter, nitrogen, and energy during the overall trial with the supplementation of palm or soy oil. In summary, the inclusion of dietary palm and soy oil has a beneficial effect on the growth performance of broiler chickens.

• 수산해양기술연구
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• 제55권1호
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• pp.62-73
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• 2019

Recently, copper alloy netting has been proposed as a material for aquaculture facilities that can be set in harsh offshore environments. To design a cage made of copper alloy netting, it is necessary to calculate the flow of water through the netting and force of external sources on the netting. Therefore, this study measured and analyzed the current velocity reduction after passing through the netting and the hydrodynamic forces acting on the netting using copper alloy netting with nine solidity ratios. As a result of the reduction rate of the flow velocity through the netting, the flow reduction rate was increased as the solidity ratio of netting was increased. The flow reduction rate was also increased as the attack angle on the netting was decreased. In analyzing the resistance on the netting, we also discovered that resistance was increased with increase in the flow velocity and solidity ratio. An analysis of the hydrodynamic coefficient acting on the netting is shown that the drag coefficient tends to increase as the attack angle increases. We also analyzed the hydrodynamic coefficient according to the variation of the Reynolds number. When the drag coefficients acting on the netting were analyzed with the different Reynolds numbers, the Reynolds number increased from over 0.3 m/s to a relative constant. Finally, the copper alloy nettings had a smaller velocity reduction rate when comparing the flow velocity reduction rate between copper alloy nettings and nylon nettings.

• Asian-Australasian Journal of Animal Sciences
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• 제32권4호
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• pp.548-555
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• 2019

Objective: The main objective of this study was to evaluate the effect of different feeding levels of a total mixed ration silage-based diet on feed intake, total tract digestion, enteric methane emissions, and energy partitioning in two beef cattle genotypes. Methods: Six mature bulls (three Thai natives, and three Thai natives - Charolais crossbreeds) were assigned in a replicated $3{\times}3$ Latin square design, with cattle breed genotype in separate squares, three periods of 21 days, and three energy feeding above maintenance levels (1.1, 1.5, and 2.0 MEm, where MEm is metabolizable energy requirement for maintenance). Bulls were placed in a metabolic cage equipped with a ventilated head box respiration system to evaluate digestibility, record respiration gases, and determine energy balance. Results: Increasing the feeding level had no significant effect on digestibility but drastically reduced the enteric methane emission rate (p<0.05). Increasing the feeding level also significantly increased the energy retention and utilization efficiency (p<0.01). The Thai native cattle had greater enteric methane emission rate, digestibility, and energy utilization efficiency than the Charolais crossbred cattle (p<0.05). The daily metabolizable energy requirement for maintenance in Thai native cattle ($388kJ/kg\;BW^{0.75}$, where $BW^{0.75}$ is metabolic body weight) was 15% less than that in Charolais crossbred cattle ($444kJ/kg\;BW^{0.75}$). Conclusion: Our results suggested that the greater feeding level in zebu beef cattle fed above maintenance levels resulted in improved energy retention and utilization efficiency because of the reduction in enteric methane energy loss. The results also indicated higher efficiency of metabolisable energy utilization for growth and a lower energy requirement for maintenance in Bos indicus than in Bos taurus.

• 농업과학연구
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• 제48권1호
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• pp.171-178
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• 2021

A comparative study was conducted to examine the effects of mixed and separate gender feeding on growth performance of Korean native chickens (KNC) against a white semi-broiler (WSB) and a commercial broiler (CB) over five weeks. 576 chicks were used with eight birds per cage in a randomized complete block design with 18 replicates per breed. For the KNC lines, three groups of male (M), female (F) and mixed-gender (FM) were used. Fresh water and feed were supplied on an ad-libitum basis. Birds were fed a standard starter (d 1 - 22) and grower diet (d 23 - 35). Body weight (BW), feed intake, and shank length (SL) were measured weekly. From the BW and feed consumed data, the average daily feed intake (ADFI), average daily gain (ADG), and feed conversion ratio (FCR) were calculated. The commercial broiler showed higher performance (p < 0.05) for all the indices measured for the entire period. The CB group consumed more feed and were more feed-efficient thus grew faster. This group was followed by the white semi-broiler and the KNC, in order. An intra-breed comparison for KNCs revealed that the males showed better growth performance with longer SL (p < 0.05) compared to the female and mixed-gender groups. The results showed that other than the breed type, mixed and separate gender feeding impacted on the growth performance of the two lines of Korean native chickens. Males for both lines of KNC generally performed better for the parameters measured, as determined by a greater BW and reduced FCR.