• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2005년도 춘계학술발표대회 논문집
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• pp.146-149
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• 2005

The using of composite material is an aviation field but it changes into a general industry. Especially composites are expanding the use on transportation vehicles like automobiles, ships, and aircrafts. The main factor of this expansion is high specific strength. It can supply a high quality and efficiency of energy. But manufacturing of composite products requires many raw materials and tooling cost for special process, so we needs a reduction of these costs to achieve best efficiency. In the present study, we contrast the change of mechanical and physical properties between VaRTM(Vacuum Assisted Resin Transfer Molding) and hand lay-up process. VaRTM process can offer a high quality the same as autoclave products, and low cost like hand lay-up process. In the results of mechanical tests, VaRTM specimen is stronger than hand lay-up specimen and hand lay-up specimen became delamination. In the results of physical tests, the resin content of VaRTM specimen is lower than hand lay-up specimen. On micrograph, the strength of specimen by VaRTM between fiber and resin is stronger than that of one by hand lay-up. And the specimen by hand lay-up contains more defects than one by VaRTM. So, VaRTM process can practically apply for automobile engine hood. This paper shows that VaRTM process is one of the most suitable processes for composite parts of automobile.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2005년도 전기학술대회논문집
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• pp.377-381
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• 2005

The using of composite material is an aviation field but it changes into a general industry. Especially composites are expanding the use on transportation vehicles like automobiles, ships, and aircraft. The main factor of this expansion is high specific strength. It can supply a high quality and efficiency of energy. But manufacturing of composite products requires many raw materials and tooling cost for special process, so we needs a reduction of these costs to achieve best efficiency. In the present study, we contrast the change of mechanical and physical properties between VaRTM(Vacuum Assisted Resin Transfer Molding) and hand lay-up process. VaRTM process can offer a high quality the same as autoclave products, and low cost like hand lay-up process. In the results of mechanical tests, VaRTM specimen is stronger than hand lay-up specimen and hand lay-up specimen became delamination. In the results of physical tests, the resin content of VaRTM specimen is lower than hand lay-up specimen. On micrograph, the strength of specimen by VaRTM between fiber and resin is stronger than that of one by hand lay-up. And the specimen by hand lay-up contains more defects than one by VaRTM. So, VaRTM process can practically apply for automobile engine hood. This paper shows that VaRTM process is one of the most suitable processes for composite parts of automobile.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2017년도 9th Asian Crop Science Association conference
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• pp.33-33
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• 2017

Water stress obstructs rice growth mainly by oxidative damage in biological cells to cause a reduction of leaf photosynthesis and evapotranspiration processes. In this study, exogenous application of vanillic acid (VA) and p-hydroxybenzoic acid (PHBA) to improve drought tolerance of two Oryza sativa cultivars, Q2 and Q8 was tested. The drought evaluation based on leaf phenotypes to show that both Q2 and Q8 resulted in remarkable water-stress tolerance induced by leaf spraying pretreatment of mixed solution of $50{\mu}M\;VA+50{\mu}M\;PHBA$. The mixtures of $25{\mu}M\;VA+25{\mu}M\;PHBA$ and $50{\mu}M\;VA+50{\mu}M\;PHBA$ treated on Q2 and Q8 in water deficit condition also indicated that total phenols, total flavonoids, and DPPH radical scavenging activity were significantly greater their controls. In general, the accumulation of individual phenolic acids was increased in exogenous phenolic treatments, as compared with controls. Particularly, Q2 obtained a considerable amount of endogenous PHBA after application of $50{\mu}M\;VA$, $25{\mu}M\;VA+25{\mu}M\;PHBA$, and $50{\mu}M\;VA+50{\mu}M\;PHBA$ (0.18 mg/g DW, 0.71 mg/g DW, and 1.41 mg/g DW, respectively); and a negligible content of VA (0.003 mg/g DW) appeared uniquely in the treatment of $50{\mu}M\;VA$. Similarly, Q8 also absorbed a significant quantity of PHBA in $50{\mu}M\;PHBA$, $25{\mu}M\;VA+25{\mu}M\;PHBA$, and $50{\mu}M\;VA+50{\mu}M\;PHBA$ treatments (0.15 mg/g DW, 0.15 mg/g DW, and 0.22 mg/g DW, respectively). In addition, the spraying $50{\mu}M\;PHBA$ and $25{\mu}M\;VA+25{\mu}M\;PHBA$ on Q8 leaves induced similar amount of VA (0.04 mg/g DW). Meanwhile, there were no trace of VA and PHBA found in controls. The levels of drought tolerance of Q2 and Q8 were improved, paralleled with the increased amounts of endogenous phenolics revealed that VA and PHBA played an important role to enhance drought tolerance in rice.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2017년도 9th Asian Crop Science Association conference
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• pp.38-38
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• 2017

Water stress obstructs rice growth mainly by oxidative damage in biological cells to cause a reduction of leaf photosynthesis and evapotranspiration processes. In this study, exogenous application of vanillic acid (VA) and p-hydroxybenzoic acid (PHBA) to improve drought tolerance of two Oryza sativa cultivars, Q2 and Q8 was tested. The drought evaluation based on leaf phenotypes to show that both Q2 and Q8 resulted in remarkable water-stress tolerance induced by leaf spraying pretreatment of mixed solution of $50{\mu}M\;VA+50{\mu}M\;PHBA$. The mixtures of $25{\mu}M\;VA+25{\mu}M\;PHBA$ and $50{\mu}M\;VA+50{\mu}M\;PHBA$ treated on Q2 and Q8 in water deficit condition also indicated that total phenols, total flavonoids, and DPPH radical scavenging activity were significantly greater their controls. In general, the accumulation of individual phenolic acids was increased in exogenous phenolic treatments, as compared with controls. Particularly, Q2 obtained a considerable amount of endogenous PHBA after application of $50{\mu}M\;VA$, $25{\mu}M\;VA+25{\mu}M\;PHBA$, and $50{\mu}M\;VA+50{\mu}M\;PHBA$ (0.18 mg/g DW, 0.71 mg/g DW, and 1.41 mg/g DW, respectively); and a negligible content of VA (0.003 mg/g DW) appeared uniquely in the treatment of $50{\mu}M\;VA$. Similarly, Q8 also absorbed a significant quantity of PHBA in $50{\mu}M\;PHBA$, $25{\mu}M\;VA+25{\mu}M\;PHBA$, and $50{\mu}M\;VA+50{\mu}M\;PHBA$ treatments (0.15 mg/g DW, 0.15 mg/g DW, and 0.22 mg/g DW, respectively). In addition, the spraying $50{\mu}M\;PHBA$ and $25{\mu}M\;VA+25{\mu}M\;PHBA$ on Q8 leaves induced similar amount of drought tolerance of Q2 and Q8 were improved, paralleled with the increased amounts of endogenous phenolics revealed that VA and PHBA played an important role to enhance drought tolerance in rice.

• 한국건축시공학회지
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• 제12권3호
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• pp.275-283
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• 2012

본 연구는 철근 콘크리트 구조물의 장수명화를 위해 고성능 다기능 폴리머 시멘트 복합체의 개발을 목적으로, 우수한 성능을 갖는 VA/E/MMA (Vinyl Acetate/Ethylene/Methyl Methacrylate) 터폴리머 분말수지와 아질산형 하이드로칼루마이트를 병용한 폴리머 시멘트 모르타르의 염화물이온 침투 저항성, 중성화 저항성, 건조수축 및 철근부식 촉진시험을 통하여 그 내구성과 방청성을 검토하는 것이다. 그 결과, 폴리머 결합재비에 관계없이 칼루마이트의 치환에 의해 폴리머 시멘트 모르타르의 내구성이 일부 저하하는 경향을 보였으나, 이는 폴리머 결합재비의 증가에 따라 크게 개선되었다. 방청성의 경우 VA/E/MMA 분말수지 사용으로 시멘트 매트릭스 내 생성된 폴리머 필름에 의한 이온 및 가스투과 저항성 증대와 칼루마이트의 이온교환반응에 따른 염화물 이온 흡착 및 아질산 이온을 방출하는 자기방청기능에 의하여 우수한 방청효과를 보였다. 따라서, 철근콘크리트 구조물의 장수명화를 위해 VA/E/MMA 터폴리머 분말수지와 아질산형 하이드로칼루마이트의 병용에 의해 우수한 방청성과 내구성을 갖는 폴리머 시멘트 복합체의 개발이 가능할 것으로 판단된다.

• Asian-Australasian Journal of Animal Sciences
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• 제18권4호
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• pp.516-523
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• 2005

The experiment was conducted to study the effect of dietary combinations of vitamin A (VA), vitamin E (VE) and methionine (Met) on growth performance, meat quality and immunity in commercial broilers. Ross chicks (n=3,630) were allocated to five experimental treatments with three replicates per diet. The dietary treatments were: VA 8,000 IU, VE 10 IU (diet 1); VA 12,000 IU, VE 10 IU (diet 2); VA 8,000 IU, VE 100 IU (diet 3); VA 12,000 IU, VE 100 IU (diet 4) and; VA 12,000 IU, VE 100 IU/kg diet and 20% Met higher than other groups (diet 5). The Met content in diet 1 to diet 4 were as per the requirement suggested by NRC. Separate vitamin premixes were prepared for each treatment diet as per the requirement of study. The 35 d study revealed significantly (p<0.0001) higher weight gains in broilers fed diet 3 and diet 5, than in the rest of the groups during starter phase (0-3 weeks) only. The feed intake did not vary significantly at all phases of study, but feed efficiency was significantly (p<0.05) lower in diet 1 during starter and overall phase (4-5 weeks). The bone strength and bone composition, except bone calcium, remained unaffected due to experimental diets studied after 35 d of experimental feeding. The thio-barbituric acid reactive substances (TBARS) were significantly (p=0.0013) lower in the breast meat in group 5, followed by group 3, than in the rest of the groups. The immune studies conducted, antibody titers to sheep red blood cells, thickness index to phytohaemagglutinin-P, and heterophil: lymphocyte ratio, did not show any significant difference among treatments. It could be concluded that supplementation of VA, VE and Met at higher levels could be beneficial to broilers only during the starter phase.

• Asia pacific journal of information systems
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• 제31권4호
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• pp.491-526
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• 2021

Airlines can employ a variety of quality monitoring procedures. In this study, we employ a content analysis of 8 years of online reviews for Korean airlines in contrast to other international airlines. Online airline reviews are infrequent, relative to the total number of passengers - the number of reviews is multiple orders of magnitude lower than passenger volumes - and online airline reviews are, therefore, not representative of passenger attitudes overall. Nevertheless, online reviews may be indicative of specific service issues, and draw attention to aspects that require further study by airline operators. Furthermore, significant words and phrases used in these airline reviews may help airline operators to rapidly automate filtering, partitioning, and analysis of incoming passenger comments via other channels, including email, social media posts, and call center transcripts. The current study provides insights into the contents of online reviews of Korean vs Other-International airlines, and opportunities for service enhancement. Further, we provide a set of marker words and phrases that may be helpful for management dashboards that require automated partitioning of passenger comments.

• Elastomers and Composites
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• 제51권3호
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• pp.212-217
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• 2016

Influence of poly(ethylene-co-vinyl acetate) (EVA) types and cure systems on cure characteristics of foaming EVA compounds were investigated. Three kind EVAs with different VA contents were employed. Influence of triallyl cyanurate (TAC) and dicumylperoxide (DCP) content on the cure characteristics were examined. The minimum torque ($T_{min}$) and delta torque (${\Delta}T$) decreased as the VA content increased. The ${\Delta}T$ was increased by adding TAC and by increasing the DCP content. For the foaming EVA compounds without TAC, the cure times such as the minimum cure time ($t_{min}$), scorch time ($t_2$), and optimal cure time ($t_{90}$) did not show a specific trend according to the DCP contents. For the foaming EVA compounds containing TAC, the cure times decreased as the DCP content increased. From the experimental results, it was found that efficienct DCP/TAC ratio for improvement of the crosslink density was 1.1~2.0.

• Asian-Australasian Journal of Animal Sciences
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• 제21권9호
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• pp.1262-1270
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• 2008

The objective of this study was to investigate the effect of dietary supplementation with calcium salts of soybean oil fatty acids (CaSO) and linseed oil fatty acids (CaLO) on c9,t11-CLA production in ruminal fluid and milk fat from Holstein dairy cows. Rumen fermentation, lactational performances and fatty acid profiles in ruminal fluid and milk fat were also investigated. Twenty multiparous Holstein dairy cows were allotted randomly into two groups consisting of ten cows in each group according to calving date and average milk yield. The first group of cows was fed a control (without calcium salts) diet and a treatment as 1.0% of CaSO (on DM basis) for 30 days in each period. In the second group, cows were fed the same control diet and 1.0% of CaLO as a treatment in the same manner. The forage: concentrate ratio was 52:48, and diets were formulated to contain 17% crude protein (DM basis) for both groups. Ruminal pH, protozoal numbers and the concentration of total volatile fatty acids were unchanged, however, the ruminal ammonia-N decreased by feeding CaSO or CaLO treatment compared to the control diet. The vaccenic acid (trans-11 C18:1; VA) in rumen fluid increased (p<0.01) by 169% and 153%, and the c9,t11-CLA content of rumen fluid increased (p<0.01) by 214% and 210% in the CaSO and CaLO treatments, respectively, compared to the control diet. In milk fatty acids, the VA content increased by 130% and 132% in the evening and morning milking times, respectively, and the c9,t11-CLA content increased by 125% in both milking times for the CaSO supplementation than that of control diet. In the case of CaLO supplementation, the VA increased by 117% and 114%, and the c9,t11-CLA increased by 96% and 94% in the evening and morning milking times, respectively, compared to the control diet. The contents of VA and c9,t11-CLA of milk fatty acids were numerically higher in the evening milking time compared to the morning milking time for control and both treatments. Finally, these results indicated that the supplementation of CaSO or CaLO treatment increased the VA and the c9,t11-CLA in both ruminal fluid and milk fat of Holstein dairy cows.

• 한국토양비료학회지
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• 제33권6호
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• pp.482-492
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• 2000

VA균근균(菌根菌)은 식물(植物)의 성장(成長)을 증가(增加)시킬 뿐만 아니라 염류장해(鹽類障害) 경감(輕減)에도 과(果)가 있다고 알려져 있다. 균근균(菌根菌)의 염류경감(鹽類輕減) 효과(效果)를 규명하기 위해서 관주용(灌注用) 염류용액(鹽類溶液) 농도(濃度) 3 수준(水準)(0.5, 2.0, $6.0dS\;m^{-1}$) 인산비료(燐酸肥料) 4 수준(水準)(0, 200, 400, $600kg\;ha^{-1}$)과 VA균근균(菌根菌)을 접종(接種)과 무접종(無接種)으로 비닐하우스 내에서 Pot 시험(試驗)으로 수행(遂行)된 결과(結果)는 다음과 같다. 초장(草長)은 이식(移植) 후 4주 및 7주일 조사시(調査時) 인산비료(燐酸肥料) $400kg\;ha^{-1}$ 수준의 EC $6.0dS\;m^{-1}$ 처리(處理)까지는 대체로 VA균근균(菌根菌) 접종효과(接種效果)가 나타났으며, 인산(燐酸) $600kg\;ha^{-1}$ 수준에서는 감염효과가 미약하거나 그 반대(反對)의 결과(結果)를 보였다. 엽면적(葉面積)은 인산(燐酸) 무시용(無施用)처리의 3개 EC수준(水準)과 EC $0.5dS\;m^{-1}$ 수준(水準)의 인산(燐酸) $200kg\;ha^{-1}$ 수준까지 VA균근균(菌根菌) 접종효과(接種效果)가 인정(認定)되었다. 접종처리(接種處理) 4주와 7주 후의 건물중(乾物重)은 EC수준(水準)에서 고도(高度)의 유의성(有意性) 있는 영향(影響)을 미친 것으로 나타났고 인산수준(燐酸水準)과 EC수준(水準) 그리고 인산수준(燐酸水準)과 VA균근균(菌根菌)의 상호작용(相互作用)에서 특히, 지하부(地下部) 건물중(乾物重) 증가(增加)에 고도(高度)의 유의성(有意性)이 인정(認定)되었다. R/S비율(比率)은 대부분의 VA균근균(菌根菌) 접종처리(接種處理)에서 감소(減少)하는 경향(傾向)이였다. 특히 인산(燐酸) 0, 400, $600kg\;ha^{-1}$ 수준(水準)의 EC $6.0dS\;m^{-1}$ 처리(處理)에서 VA균근균(菌根菌) 효과(效果)가 뚜렷하였다. 이식처리(移植處理) 후 7주째의 염록소(葉綠素) 함량(含量)은 인산수준(燐酸水準)과 염류용액(鹽類溶液) 농도(濃度)가 낮을 수록 높았으며, VA균근균(菌根菌) 접종은 엽록소(葉綠素) 함량(含量)을 더욱 증가시켰다. 청과(靑果)의 수량(收量)은 일정(一定)한 경향(傾向)을 얻을 수 없었으나, 대체로 VA균근균(菌根菌)의 효과(效果)는 인산함량(燐酸含量)이 낮고 염류농도(鹽類濃度)가 높지 않은 조건(條件)에서만 인정(認定)되었다. 고추의 균근(菌根) 의존성(依存性)은 이식처리(移植處理) 4주, 7주 후 조사 모두에서 인산(燐醱) 무시용(無施用)과 인산(燐酸) $200kg\;ha^{-1}$ 수준의 EC 0.5, $2.0dS\;m^{-1}$ 처리(處理)의 경우만 의존성(依存性)을 보였고, 그 외의 처리(處理)에서는 균근균(菌根菌) 의존성(依存性)을 보이지 않았으며 높은 의존성(依存性)을 보인 처리(處理)는 인산무시용(燐酸無施用)의 EC $6.0dS\;m^{-1}$, 인산(燐酸) $200kg\;ha^{-1}$ 수준의 EC 0.5, $2.0dS\;m^{-1}$ 처리(處理)였다. 고추의 균근(菌根) 감염율(感染率)과 포자밀도(包子密度)에서 균근균(菌根菌) 감염율(感染率)은 3.3-43.3% 범위(範圍)를 보였고 인산수준(燐酸水準)이 낮고 염류농도(鹽類濃度)가 낮았을 경우에 높은 감염율(感染率)을 나타냈다. 포자밀도(胞子密度) 역시 VA균근균(菌根菌) 감염율(感染率)과 비슷한 경향(傾向)으로 건토 100 g당 47.7-198.3개(個)의 범위(範圍)로 감염율(感染率)과 포자밀도는 고도(高度)의 유의성(有意性) ($r=0.858^{**}$)을 보였다. 인산(燐酸)의 시용수준(施肥水準), 염류용액(鹽類溶液)의 농도(濃度) 및 VA균근균(菌根菌) 접종(接種)에 따른 고추의 무기(無機)이온의 흡수(吸收)에 있어서 인산수준(燐酸水準)이 낮고 염류수준(鹽類水準)이 높지 않은 처리(處理)에서 VA균근균(菌根菌) 접종효과(接種效果)가 인정되었다.