• Journal of the Korean Wood Science and Technology
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• 제34권5호
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• pp.29-41
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• 2006

This study was to investigate the effect of adding additive as tannin, rice husk and charcoal, for reducing the formaldehyde emission level, on the adhesion properties of urea-formaldehyde (UF) resin for particleboard. We controlled the hot-pressing time, temperature and pressure to determine the bonding strength and formaldehyde emission. Blends of various UF resin/additives (tannin, rice husk and charcoal) compositions were prepared. To determine and compare the effect of additives (tannin, rice husk and charcoal) content, 0, 5, 10 and 15%, by weight of UF resin, were used. $NH_4Cl$ as hardener added. To determine the level of formaldehyde emission, we used the desiccator, perforator and 20 L-small chamber method. The formaldehyde emission level decreased with increased additions of additive (except rice husk). Also, increased hot-pressing time decreased formaldehyde emission level. At a charcoal replacement ratio of only 15%, the formaldehyde emission level is under F ✩ ✩ ✩ ✩ grade (emit < $0.3mg/{\ell}$). Curing of the high tannin additive content in this adhesive system indicated that the bonding strength increased. But, in the case of rice husk and charcoal, the bonding strength was much lower due to the inorganic substance. Furthermore, rice husk was poor in bonding strength as well as formaldehyde emission than tannin and charcoal.

• 한국ITS학회 논문지
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• 제18권6호
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• pp.76-95
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• 2019

자중계는 화물차 운전자들이 자신의 화물무게를 인지하지 못해서 생기는 부득이한 과적을 방지하기 위해서 반드시 필요한 기술이다. 본 연구에서는 자중계의 일본의 의무장착 사례와 국내 활용현황에 대하여 조사하고 자중계와 GPS, 모뎀을 연동한 IoT 관제시스템을 시험차량에 설치한 후 원격 모니터링을 통해 과적운행패턴을 규명하고, 자중계 설치 시 과적 예방효과와 운송 효율성에 대하여 분석하고자 하였다. 장기 모니터링 데이터를 분석한 결과, 자중계 설치 후 운전자가 화물중량을 인지함으로써 과적율과 과적 중량이 감소되는 효과를 확인하였으며, 건설기계 차량의 경우 운송거리 단축에 의한 운송효율이 높아지는 결과를 확인하였다. 또한 단속지점의 GPS 좌표와 화물차량의 이동경로를 매칭하여 과적상태인 경우 회피 운행경로를 분석하였으며, 적재물의 종류에 따른 운행거리와 적재중량을 분석하였다.

• Journal of Ecology and Environment
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• 제31권4호
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• pp.341-344
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• 2008

We investigated the responses of red squirrels to pine nuts (Pinus koraiensis) treated with Lithium Chloride (LiCl) and the potential of the chemical for inducing conditioned taste aversion (CTA) in red squirrels. In red squirrels, nut feeding declined dramatically during the first 4 days after feeding with LiCl-treated nuts. The ratio of LiCl-treated nuts eaten to total nuts eaten declined from the $1^{st}$ day in LC-1 and the $2^{nd}$ day in LC-2, along with a general reduction in quantity eaten. Thus, feeding with LiCl-treated nuts induced CTA from the 2nd day after feeding, and CTA remained constant until the $4^{th}$ day, but disappeared on the $5^{th}$ day. The squirrels ate an average of $757.0{\pm}106.1mg$ (n = 2, range $682.0\sim832.0$) of LiCl before dying on the $16^{th}$ day of the study. The lethal dose of LiCl was 2.32 mg LiCl/g body weight, and the average amount of LiCl needed to induce CTA was $23.0{\pm}4.24mg$ (20 mg in LC-1 and 26 mg in LC-2).

• The Plant Pathology Journal
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• 제32권3호
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• pp.216-227
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• 2016

Biological control agents (BCAs) from different microbial taxa are increasingly used to control bacterial wilt caused by Ralstonia solanacearum. However, a quantitative research synthesis has not been conducted on the role of BCAs in disease suppression. Therefore, the present study aimed to meta-analyze the impacts of BCAs on both Ralstonia wilt disease suppression and plant (host) growth promotion. The analysis showed that the extent of disease suppression by BCAs varied widely among studies, with effect size (log response ratio) ranging from -2.84 to 2.13. The disease incidence and severity were significantly decreased on average by 53.7% and 49.3%, respectively. BCAs inoculation also significantly increased fresh and dry weight by 34.4% and 36.1%, respectively on average. Also, BCAs inoculation significantly increased plant yield by 66%. Mean effect sizes for genus Pseudomonas sp. as BCAs were higher than for genus Bacillus spp. Among antagonists tested, P. fluorescens, P. putida, B. cereus, B. subtilis and B. amyloliquefaciens were found to be more effective in general for disease reduction. Across studies, highest disease control was found for P. fluorescens, annual plants, co-inoculation with more than one BCA, soil drench and greenhouse condition were found to be essential in understanding plant responses to R. solanacearum. Our results suggest that more efforts should be devoted to harnessing the potential beneficial effects of these antagonists, not just for plant growth promoting traits but also in mode of applications, BCAs formulations and their field studies should be considered in the future for R. solanacearum wilt disease suppression.

• 대한기계학회논문집A
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• 제41권2호
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• pp.137-142
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• 2017

최근 자동차 산업에서 경량화이면서 외부 충격에 민감한 시트 프레임은 안전성을 고려하여 꾸준히 연구개발되고 있다. 특히 본 연구에서는 고장력 강판과 폴리머의 이종 소재를 이용한 시트 프레임의 충격 특성에 대해 살펴보았다. 또한, 충격시 변위는 소재에 대해 굽힘 현상을 고려한 등가 굽힘강성식을 도입하여 살펴보았다. 층간 wire-web 구조물의 다양한 형상의 공학 디자인을 통해 충격시 변화가 적은 디자인을 설계하였으며, 육각형의 층간 wire-web 구조물이 외부 충격대비 안전계수가 높음으로 인해 흡수능력이 향상될 것으로 기대하고 있다. 이러한 연구 결과를 토대로 층간 wire-web 구조물의 설계를 통해 레진과의 함침을 높이고 이종 소재로써의 충격민감도에 유리한 제품을 개발할 수 있을 것으로 사료된다.

• 한국강구조학회 논문집
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• 제23권1호
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• pp.125-135
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• 2011

최근 타워형 아파트구조에 많이 사용되고 있는 무량판 구조시스템을 대신해 층고절감 및 장스팬 구현 그리고 내화성능향상을 목적으로 GFRP를 이용한 경량합성바닥을 개발하였다. GFRP를 이용한 경량합성바닥은 웨브에 개구부를 가지는 비대칭 강재보 하부에 GFRP를 부착하고 슬래브에 경량체를 삽입한 중공합성바닥이다. 이에 개발된 합성바닥의 휨성능을 평가하기 위해 GFRP, 중공률, 웨브의 개구부 등을 변수로 실대 실험을 수행하였다. 그 결과 GFRP를 이용한 합성보 실험체는 기준 실험체에 비해 휨내력 및 강성 측면에서 10% 높은 성능을 나타냈으며, 구조물이 항복할 때까지 완전합성거동하였다. 항복 이후 웨브개구부 주변의 응력집중현상에 의해 연성이 감소하는 현상이 나타났으며, 최대내력점까지 미끄러짐의 발생은 미소하였다. 내력설계 측면에서는 안전율을 고려해 해석값의 85%를 설계내력으로 평가하는 것이 타당한 것으로 나타났다.

• 한국세라믹학회지
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• 제56권4호
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• pp.360-364
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• 2019

PZT suspensions for photo-curable 3D printing were fabricated and their characteristics were evaluated. After mixing the PZT, photopolymer, photo-initiator, and dispersant for 10 min by using a high-shear mixer, the viscosity characteristics were investigated based on the powder content. To determine an appropriate dispersant content, the dispersant was mixed at 1, 3, and 5 wt% of the powder and a precipitation test was conducted for two hours. Consequently, it was confirmed that the dispersibility was excellent at 3 wt%. Through thermogravimetric analysis, it was confirmed that weight reduction occurred in the photopolymer between 120? and 500?, thereby providing a debinding heat treatment profile. The fabricated suspensions were cured using UV light, and the polymer was removed through debinding. Subsequently, the density and surface characteristics were analyzed by using the Archimedes method and field-emission scanning electron microscopy. Consequently, compared with the theoretical density, an excellent characteristic of 97% was shown at a powder content of 87 wt%. Through X-ray diffraction analysis, it was confirmed that the crystallizability improved as the solid content increased. At the mixing ratio of 87 wt% powder and 13 wt% photo-curable resin, the viscosity was 3,100 cps, confirming an appropriate viscosity characteristic as a stereolithography suspension for 3D printing.

• Asian-Australasian Journal of Animal Sciences
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• 제17권1호
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• pp.102-108
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• 2004

The present experiment was conducted to assess the efficacy of methionine hydroxy analogue free fatty acid (MHAFA) in comparison to DL-methionine (DL-Met) utilizing day-old commercial broiler chicks (n=300). The chicks were randomly distributed into 30 groups of 10 chicks each. Three dietary treatments, viz. D1-maize-soybean meal based basal diet (Control), D2- control diet supplemented with DL- methionine to meet its requirements and D3-control supplemented with MHA-FA @ 1.54 times of DL-methionine used in D2, were formulated. Each dietary treatment was offered to 10 replicated groups of chicks following completely random design (CRD). The chicks fed on supplemental DL-Met had significantly higher (p<0.01) gain in body weight, followed by MHA-FA group and control during 0-3 weeks of age. During overall growth period (0-6 weeks), chicks in DL-Met and MHA-FA groups grew better (p<0.01) than those in control. Feed conversion ratio (FCR) improved (p<0.01) on supplementation of either DL- Met or MHA-FA in the basal (Control) diet during 0-3 weeks of age. The FCR for overall period, however, did not differ statistically (p>0.05) amongst the treatments. The eviscerated yields emanated from diets with DL-Met or MHA-FA were higher (p<0.01) than that in Control. Abdominal fat pad was also more (p<0.01) in broilers fed control diet than in DL-Met or MHA-FA supplemented group. Breast yield was higher (p<0.05) in MHA-FA fed broilers than those fed DL-methionine supplemented or un-supplemented diets. The efficacy of MHA-FA in comparison to DL-Met for growth was 62.11, 64.82 and 63.88% and for feed efficiency was 62.98, 67.73 and 64.01% at 0-3, 3-6 and 0-6 weeks of age, respectively, while it was 65.85, 71.40 and 67.49% for eviscerated yield, abdominal fat pad reduction and breast yield at 6 weeks of age, respectively.

• Asian-Australasian Journal of Animal Sciences
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• 제14권12호
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• pp.1741-1746
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• 2001

An experiment was conducted at the experimental duck farm of Cantho University to determine the effects of feeding duckweed (Lemna minor) that completely replaced commercial protein supplements in diets for crossbred meat ducks. The experiment included five treatments, with four replicates and ten crossbred ducks per replicate (pen). The five diets were based on broken rice offered ad libitum, supplemented with either 27 (control, SB100), 19 (SB70), 15 (SB55), 12 (SB40) or zero (SB0) g/day of ground, roasted soya beans, with fresh duckweed supplied ad libitum, except for the control (SB0) treatment. A vitamin / mineral premix and salt were included in the control (SB100) diet, but not in the diets with duckweed. These diets were fed to growing crossbred meat ducks (Czechoslovak Cherry Valley hybrids) from 28 to 63 days of age, when two birds (one male and one female) per pen were slaughtered for carcass evaluation. Total daily intakes were 95, 108, 108, 105 and 107 g of dry matter (DM) (p<0.001) and daily live weight gains 26.1, 29.1, 28.3, 27.1 and 27.6 g (p<0.001) for the SB100, SB70, SB55, SB40 and SB0 diets, respectively. Corresponding feed conversion ratios (FCR, dry matter basis) were 3.63, 3.71, 3.82, 3.89 and 3.88 kg feed/kg gain, respectively. There were no significant differences in carcass yields, chest and thigh muscle weights, and internal organ weights between the ducks fed the control diet and those fed duckweed diets. Fresh duckweed can completely replace roasted soya beans and a vitamin-mineral premix in broken rice based diets for growing crossbred ducks without reduction in growth performance or carcass traits. If the duckweed is grown on farm, and managed and harvested by household labour, the saving over purchased protein supplements is up to 48%.

• Asian-Australasian Journal of Animal Sciences
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• 제22권7호
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• pp.1026-1031
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• 2009

An experiment was conducted to study the effect of graded levels of butyric acid (butyrate) on performance, gastrointestinal tract health and carcass characteristics in young broiler chickens. Control starter (0-3 wk) and finisher (4-5 wk) diets were formulated to contain 2,900 kcal ME/kg and 22% CP, and 3,000 kcal ME/kg and 20% CP, respectively. Subsequently, four other experimental diets were formulated to contain 0.05% antibiotic (furazolidone) or 0.2, 0.4 and 0.6% butyric acid. Each diet was fed at random to 8 replicates of 6 chicks each throughout the experimental period (0-5 wk). The results showed that 0.4% butyrate in the diet was similar to antibiotic in maintaining body weight gain and reducing E. coli numbers but superior for feed conversion ratio. No added advantage on these parameters was obtained by enhancing the concentration of butyrate from 0.4 to 0.6% in the diet. Feed intake and mortality were not influenced by the dietary treatments. A reduction in pH of the upper GI tract (crop, proventiculus and gizzard) was observed by inclusion of butyrate in the diets of broilers compared to either control or antibiotic-fed group. Butyrate at 0.4% was more effective in reducing the pH than 0.2% butyrate. Within the lower GI tract, 0.4 and 0.6% butyrate was effective in lowering pH in the duodenum, but no effect was found in either the jejunum or ileum. The villus length and crypt depth in the duodenum increased significantly in all the butyrate treated diets irrespective of the level tested. Carcass yield was higher and abdominal fat content was lower significantly in all the butyrate treatment groups compared to the control or antibiotic group. From these findings, it is concluded that 0.4% butyric acid supplementation maintained performance, intestinal tract health, and villi development and carcass quality in broiler chickens.