• Fire Science and Engineering
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• v.27 no.3
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• pp.30-37
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• 2013

The ultimate purpose of the present study is to secure a effective method for foam liquid discharge when the mixing ratio deviates from the permissible range due to a decrease in the bypass flow rate resulting from a decrease in the cross sectional area of the foam liquid piping ranging from the branching header of one foam proportioner to the branching headers of multiple branching foam fire-extinguishing systems in the region for fire extinguishing and then to the standpipe at the lower part of the storage tank when a fire occurred in a combustible tank. To this end, the cause of mixing ratio variations following changes in the flow rates of existing foam fire extinguishing systems was analyzed, methods for compensation for constant mixing ratios were investigated, and it was proved that metering orifice replacements that could expand the cross sectional area of the stock solution inhaling piping was the most effective way for the improvement of form fire extinguishing systems' mixing ratios through foam proportioner venturi, foam chamber orifice, and metering orifice replacement experiments.

• Journal of the korean Society of Automotive Engineers
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• v.18 no.5
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• pp.53-68
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• 1996

마그네슘이 자동차 경량화에 관심이 되는 이유는 근본적으로 CAFE 규제와 같이 경량화를 통한 화석연료의 소모를 크게 억제해야 한다는 사회적인 규제이나, 지난 10여년간의 기술발전으로 내식성이 나쁘다거나 취급이 위험한 금속이라는 인식이 크게 개선된 데에도 있다. 다른 경량금속에 대한 Mg 지금 가격의 비교조건이 호전되었고 향후 원소 재공급의 다변화가 추진되고 있는 것도 환경을 변화시킨 중요한 요인이다. 그간 중요한 경량화 대체 재료로 연구투자가 많았던 유기고분자 재료 및 FRP 등과 같은 복합재료는 폐기부품의 재활용이 어려움 때문에 호나경친화적인 단점이 부각되어, 이 소재의 증가가 주춤해 있다. 마그네슘의 경우에는 재활용이 가능하고, 진동흡수효과가 매우 커서 소음발생을 크게 줄일 뿐만 아니라, 주행 및 내구성시험에서 치수안정성이 좋고 많은 종류의 전자기기 사용에 의한 전자파 차폐효과도 큰 장점을 가지고 있다. 본 고에서는 Mg 다이캐스팅으로 자동차부품의 경량화 현황과 선진국에서 보는 전망을 미국을 중심으로 정리하고, 이와 관련한 Mg 다이캐스팅으로 자동차부품의 경량화 현황과 선진국에서 보는 전망을 미국을 중심으로 정리하고, 이와 관련한 Mg 기술적인 이슈와 시장전망도 서술하였다. 그리고 현재 우리나라의 연구계와 부품업계에서 추진하고 있는 연구개발 동향을 자동차 업계에 소개하는 의미도 있다. 이처럼 우리나라의 현황을 정리해 보는 것은 국내 자동차 산업이 국제적인 경쟁을 하고 있고 Mg기술과 원료확보에서 일본의 견제를 받고 있는 우리의 현실에서도 필요한 작업으로 생각된다.값들로 구성되는 형상을 내구 성능, 성형성등을 고려하여 최종 형상으로 결정한다. 내구성능의 예측은 금속부품의 내구수명 예측에 널리 이용되고 있는 방법이 방진 고무부품의 경우에도 적용 가능한지를 검토하고, 방진 고무부품에도 일반적으로 적용될수 있는 내구수명 예측방안의 개발 가능성을 타진해 보았다. 본 연구의 목표는 시제품을 제작하기 이전에 설계된 부품에 대한 스프링 상수 및 내구특성을 체계적으로 규명하여 제품 시험의 횟수를 줄이고, 보다 정밀한 제품을 제작할 수 있도록 하기 위한 것이다.세포수는 초기 배반포기배에서 팽윤 배반포기배로 진행됨에 따라 두배에서 세배 정도 증가되었음을 알 수 있었다. 또한, differential labelling과 bisbenzimide기법에서 얻어진 각각의 총세포수를 비교하였을 때 총세포수는 발달의 진행 정도에 따라 증가되며 그와 동시에 동일한 군 간의 세포수도 거의 유사함을 알 수 있었다. 따라서, ICM과 TE를 differential labelling하는 기법은 수정란의 quality를 평가하는데 매우 유용한 기법으로서 착상전 embryo 발달을 연구하는데 효과적으로 이용될 수 있다는 것을 시사한다. 고도의 유의차를 나타낸 반면 비수구, 초생수로구 및 Bromegrass 목초구 간에는 아무런 유의차가 인정되지 않았다. 7. 농지보전 처리구인 배수구와 초생수로구는 비처리구에 비해 낮은 침두 유출량과 낮은 토양유실량을 나타내었다.구보다 14% 절감되는 것으로 나타났다.작용하는 것으로 사료된다.된다.정량 분석한 결과이다. 시편의 조성은 33.6 at%

• Korean Journal of Animal Reproduction
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• v.27 no.2
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• pp.115-123
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• 2003

The present study was carried out to examine the effect of catalase (CAT) on in vitro maturation (IVM) of porcine follicular oocytes and oxygen concentration with CAT on in vitro development (IVD) of porcine IVM/IVF embryos. The results were summarized as follows - 1 . The rates of nuclear maturation, penetrated oocytes, pronucleus formation rates, polyspermic oocytes and mean numbers of the penetrated sperm were significantly lower in oocytes matured with 100, 500 and 1,000 units/ml CAT than those of central groups (P>0.05). 2. The rates of blastocyst formation and total cell numbers of blastocyst at day 7 after in vitro fertilization were significantly lower in CAT treatment groups than those of the central groups (P>0.05). 3. There were not significant difference in the blastocyst development and total cell numbers of blastocyst on in vitro culture of NCSU-23 media with 0, 100, 500 and 1000 units/ml CAT under the 5% and 20% $O_2$ concentrations. These results suggested that the addition of CAT was not helpful for porcine oocyte maturation and further development, also the rates of blastocyst formation and total cell numbers of blastocyst at day 7 of porcine IVM/IVF embryos were not significantly different in the NCSU-23 culture medium under the 5% and 20% $O_2$ concentrations.

• Korean Journal of Animal Reproduction
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• v.27 no.2
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• pp.169-177
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• 2003

This study was conducted to determine effects of polyvinyl alcohol (PVA), fetal bovine serum (FBS) bovine serum albumin (BSA) and epidermal growth factor (EGF) on blastocoel formation, total cell number, apoptosis and apoptosis-related gene expression of porcine diploid parthenotes developing in vitro. The addition of 0.4% BSA to the culture medium enhanced the development of 2-cell stage parthenotes to the blastocysts stage (P<0.01). FBS reduced cell numbers of blastocysts (P<0.01) and increased percentage of apoptosis in the blastocysts (P<0.001). However, while BSA increased cell numbers, it did so only when EGF was present. Either agent on its own had no effect. Similarly, apoptosis in the blastocysts was not influenced by either agent on its own but was reduced when both BSA and EGF were present. Furthermore, semi-quantitative reverse-transcriptase polymerase chain reaction revealed that EGF enhanced the mRNA expression of Bcl-xL in the presence of 0.4% BSA but BSA and EGF alone had no effect, and EGF and/or BSA did not influence Bak gene expression in the blastocyst stage parthenotes. However FBS reduced Bcl-xL mRNA expression (P <0.05) and enhanced Bak expression. This result suggests that apoptosis related genes expression is significantly affected by supplements, which may result in alteration of apoptosis and embryo viability of porcine embryos developing in vitro.

• Journal of the Mineralogical Society of Korea
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• v.23 no.3
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• pp.243-250
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• 2010

Froth flotation of complex copper ore from Indonesia Jambi mine has been carried out to produce high-grade Cu concentrate. Since the ore contained minor Cu sulfides in addition to major Cu carbonate (malachite), copper concentrate was recovered by two-stage process of flotation, which consisted of copper sulfide flotation using xanthate followed by copper oxide flotation using oleic acid. The copper sulfide concentrate of 57.5% Cu grade with 9.5% recovery was obtained by copper sulfide flotation under conditions of 300 g/t collector (1 : 1 mixture of xanthate series Aero Promoter 211 and Aero Promoter 242) and pH 6.0 pulp. In subsequent copper oxide flotation on sink products, the concentrate of 30.8% Cu grade with 92.1% recovery was obtained under the conditions of oleic acid 300 g/t, AF65 50 g/t, pH 8.0 and 2 times cleaning. The flotation techniques which can achieve a Cu grade of 36.1% and a recovery of 92.1% have been developed from the two-stage process of flotation.

• The Journal of the Korea Contents Association
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• v.18 no.1
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• pp.196-209
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• 2018

This study is founded on banks' profitability factors. Unlike the previous study in terms of diversification of the banks' funding structure, this research performs multiple regression analysis during the entire period and examines the comparative analysis of before and after the financial crisis. the study establishes hypotheses by using the wholesale funding ratio as a key focus variable with 8 explanatory variables and the operating profit on assets as a profitability index. The Loan-deposit rate gap, the Number of stores and the Non-performing loan ratio prove to be a significant profitability factor for all periods of time. Korean banks are also more profitable when their the Loan-deposit rate gap get bigger and the Number of stores grows. The wholesale funding ratio is analyzed to have no statistically significant effect on the profitability of banks. Rather than being influenced by macroeconomic indicators, it is indicated that the situation of individual banks and other financial environments have been affected. And banks increase profitability as banks increase their loan after the financial crisis. The empirical analysis shows that profitability factors have periodical distinctions, and in this aspect, this research has implications. The study needs to be expanded to cover the entire domestic banking sector, in consideration of the profitability of the banking industry in the future.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.9
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• pp.510-516
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• 2019

This study examined the effects of fetal bovine serum (FBS), goat blood serum (gBS), and poly-vinyl alcohol (PVA) on the in vitro development and embryo quality of goats for an improvement of embryo production. For the experiment, an in vitro fertilized embryo culture medium was supplemented with 10% FBS, 10% gBS, and 10% PVA to determine their effects on the embryo development efficiency and blastocyst quality. The results showed that the non-serum supplementation group showed significantly lower cleavage rate and blastocyst formation. On the other hand, the gBS and PVA supplementation groups showed a significant increase in the cleavage rate and better blastocyst formation than the control and FBS supplementation group. Furthermore, a TUNEL assay performed to confirm the blastocyst quality showed the same pattern as the embryo development experiment. These results showed that the supplemented gBS or PVA was more efficient in enhancing the in vitro development efficiency of goats than the supplementation of FBS or non-serum. On the other hand, considering the risk of an unidentified factor in gBS, PVA appears to be safer and more efficient in the in vitro development of goat embryos.

• Korean Journal of Plant Resources
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• v.36 no.5
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• pp.469-489
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• 2023

Six field surveys were conducted at 29 locations from April 2020 to April 2022 to identify the freshwater flora of the Taean Peninsula. Based on the collected specimens, the vascular plants of the Taean Peninsula were summarized as 391 taxa: 94 families, 248 genera, 362 species, 5 subspecies, and 24 varieties. Freshwater plants in the Taean Peninsula consisted of 104 taxa, 45 taxa for aquatic plants, and 59 taxa for wetland plants. When classified by life history, annuals accounted for 33 taxa, winter annuals 5 taxa, biennial 6 taxa, and perennials accounted for most of the 60 taxa. Among the 391 identified taxa, 2 taxa of Endangered plants, 3 taxa of Korean endemic plants, 5 taxa of IUCN red list plants, 49 taxa of Korean floristic target plants, 38 taxa of biological resources subject to the approval of outbound transfer, 55 taxa alien plants and 7 taxa of ecosystem disturbing plant. The results of this study are intended to be used as basic data on the freshwater environment and distribution of aquatic plants in the Taean Peninsula.

• Journal of the Korean Society of Food Science and Nutrition
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• v.37 no.1
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• pp.16-19
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• 2008

Bone mass in adults decreases with age because of the imbalance between the rate of bone formation and resorption. We performed this study to investigate whether Asparagus cochinchinensis (Lour.) Merr. (ACAE) plays a role in osteoblasts differentiation and osteoclasts formation. Ethanol extract of ACAE showed increase in the differentiation and alkaline phosphatase activity of osteoblasts. Also, it decreased the number of tartrate-resistant acid phosphatase (TRAP)-positive multinucleated cells (OCLs) and TRAP activity. Therefore, ACAE has the potential to prevent bone-related diseases such as osteoporosis by increasing the differentiation of osteoblasts and reducing both the number and activity of osteoclasts.

• Resources Recycling
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• v.21 no.6
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• pp.51-57
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• 2012

The objective of this study was to research the mineralogical characteristics and removal of heavy metals of tailings from Gum-poong mine. From the result of mineralogical analysis, there are several sulphide minerals such as chalcocite, aresenopyrite, pyrite, sphalerite and galena. Cd and Zn have a good positive correlation from the statistical relation between Cd and other heavy metals(Cu, Pb, Zn). Residual heavy metals(As, Cd, Cu, Pb, Zn) from the Gum-poong tailings were removed under the warning criteria from the result of froth flotation with K.A.X.(Potassium Amyl Xanthate) and Aerofloat 211.