• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2007년도 추계 학술논문 발표대회
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• pp.87-90
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• 2007

The purpose of this study is to investigate the properties of concrete with the kinds and addition of expansive additives. 2 kinds of expansive additives produced in our country and 0, 10, 20, 30, 40% of ratio of addition rate are selected for this experiment. According to experimental results, flow, slump and air rate of concrete with expansive additives is nearly same with its of plain concrete and compressive strength, tensile strength of concrete with expansive additives at 28 days is higher than that of plain concrete. Therefore, The expansion concrete is able to manufactured so it consumes by restricted effects.

• 한국식생활문화학회지
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• 제25권6호
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• pp.755-763
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• 2010

The purpose of this study was to select market variables that a foodservice company should consider when expanding overseas and to regional market analysis by variables. Twenty-three different variables were derived from 17 previous studies. These were: population, urbanization rate, women employed, enrollment in tertiary education, gross domestic product, value added by service, total number of mobile cellular telephone subscribers, number of internet users, total Asian highway, inward foreign direct investment, total service imports, inflation rate, international tourist arrivals, energy use by industry, growth rates of the food consumer price index, access to urban sanitation, per capita total expenditure on health, male life expectancy at birth, adult literacy rate, contributing women family workers, passenger car, and country risk assessment. The selected variables were collected as secondary data from the UN, Asian Development Bank, International Bank for Reconstruction and Development, and Michigan State University.

• 대한환경공학회지
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• 제35권12호
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• pp.967-972
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• 2013

질소산화물 저감에 큰 효과가 있는 MILD 연소는 고온의 배기가스가 연소로내에 유입되는 양에 따라 질소산화물 저감 특성이 많은 영향을 받는다. 본 연구에서는 동심원관 형태의 MILD 연소로에서 바깥 원통의 배기가스 통로에서부터 안쪽 원통의 연소통로 사이에 연결관을 설치하고 배기가스를 유입하기 위해 coanda 노즐을 사용하였다. 이러한 coanda 노즐의 기하학적 형상 변화에 따라 고압공기 유량, 배기가스 유입량 특성을 수치해석을 통해 살펴봄으로써 최적의 coanda 노즐 형상을 도출하는 것을 본 연구의 목적으로 하였다. 본 연구의 전산 해석의 결과는 conada 노즐의 노즐 통로 간격이 0.5 mm, 노즐 각도 $4^{\circ}$, 노즐 확관 길이 146 mm일 때 최적의 유입량비가 되었고 노즐 통로 수직 길이는 유입량비에 무관하였다.

• 대한의생명과학회지
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• 제29권4호
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• pp.302-313
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• 2023

Y chromosomal short tandem repeat (Y-STR) markers have been developed continuously to complement forensic DNA analyses and population genetic studies. Initially, we collected data from previously reported Korean population Y-STR haplotype studies on 1133 individuals. We then conducted a marker expansion analysis using a dataset from the Y-STR Haplotype Reference Database (YHRD), covering up to 29 Y-STRs, referred to as Ymax. Additionally, we examined the impact of rapidly mutating (RM) Y-STRs included in this expanded marker set on the discrimination capacity. We observed that marker expansions both with (0.9896), and without (0.9510), RM Y-STR improved the discrimination capacity. Subsequently, we focused on 16 individuals belonging to seven distinct groups sharing identical haplotypes. These particular haplotypes had been previously identified among 476 unrelated males using 23 Y-STR markers from the PowerPlex^® Y23 System. We expanded the marker panel up to Ymax to explore how discrimination improved with an expansion of Y-STR markers for these 16 individuals. Among the expanded markers, DYS627, which had high discriminatory power, had a high mutation rate (1.10 × 10^-2) and high gene diversity (0.83). In contrast, DYF387S1 displayed high gene diversity (0.95) but a relatively low mutation rate (2.80 × 10^-3). We propose that these findings will be valuable in the selection of suitable Y-STR markers, depending on the objectives of forensic analyses. Additionally, the presence of frequently observed Y-haplotypes in Korean population will facilitate statistical interpretation in Y-STR DNA profiling.

• KIEE International Transactions on Power Engineering
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• 제5A권1호
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• pp.46-55
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• 2005

This paper proposes a new method for choice of the best transmission system expansion plan on the side of highest satisfaction level of decision maker using fuzzy integer programming. The proposed method considers the permissibility and ambiguity of the investment budget (economics) for constructing the new transmission lines and the delivery marginal rate (reliability criteria) of the system by modeling the transmission expansion problem as a fuzzy integer programming one. It solves the optimal strategy (reasonable as well as flexible) using a fuzzy set theory-based on branch and bound method that utilizes a network flow approach and the maximum flow-minimum cut set theorem. Under no or only a very small database for the evaluation of reliability indices, the proposed technique provides the decision maker with a valuable and practical tool to solve the transmission expansion problem considering problem uncertainties. Test results on the 63-bus test system show that the proposed method is practical and efficiently applicable to transmission expansion planning.

• 한국추진공학회지
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• 제2권2호
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• pp.83-87
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• 1998

액체로켓엔진에서 발생하는 초음속 제트 소음을 감소시킬 수 있는 물 분사형 소음기를 설계, 제작하여 물의 질량 유동률, 1차관 길이, 그리고 2차 확장관의 지름과 같은 기하학적 변화에 따른 성능 시험을 수행하였으며, 다음과 같은 결과를 얻을 수 있었다. 1. 동일한 물의 질량 유동률에서, 1차관의 길이가 길수록 효과이었다. 2. 물이 질량 유동률이 증가하면, 소음은 감소한다. 3. 최적의 물 질량 유동률은 추진제 공급량의 10∼12배 정도이다. 4. 소음기에 2차 확장관을 부착할 경우, 약 30㏈ 정도 소음감소 효과를 얻을 수 있다.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 동계학술발표대회 논문집
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• pp.227-232
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• 2008

The present study was investigated the local heat transfer characteristics and temperature distribution on the louver fin by using the expansion model. Heat transfer rate, frost mass and temperature distribution of the louver fin under frosting condition were experimentally investigated. Local heat transfer rate and heat flux on the louver were analyzed by the conduction heat transfer between top and lower part of the louver. The experimental key parameter was brine inlet temperature(-5, -10, $-15^{\circ}C$). The heat transfer performance and frost mass at brine temperature of $-15^{\circ}C$ were increased by maximum 3 time than the brine temperature of $-5^{\circ}C$. At all experimental case, local heat transfer rate and heat flux of the louver were almost symmetry at the louver number of 6. Especially, local heat transfer rate and heat flux were maximum increased on the louver number of 4 and 8.

• Animal Bioscience
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• 제37권6호
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• pp.1007-1020
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• 2024

Objective: We increased the nuclear maturation rate of antral follicle derived oocytes by using a pre-in vitro maturation (IVM) culture system and improved the developmental potential of these porcine pathenotes by supplementing with melatonin. Furthermore, we investigated the expression patterns of genes involved in cumulus expansion (HAS2, PTGS2, TNFAIP6, and PTX3) derived from small and medium antral follicles before and after oocyte maturation. Methods: Only the cumulus oocyte-complexes (COCs) derived from small antral follicles were induced with [Pre-SF(+)hCG] or without [Pre-SF(-)hCG] the addition of human chorionic gonadotropin (hCG) during the last 7 h of the pre-IVM period before undergoing the regular culture system. The mature oocytes were investigated on embryonic development after parthenogenetic activation (PA). Melatonin (10^-7 M) was supplemented during in vitro culture (IVC) to improve the developmental potential of these porcine pathenotes. Results: A pre-IVM culture system with hCG added during the last 7 h of the pre-IVM period [Pre-SF(+)hCG] effectively supported small antral follicle-derived oocytes and increased their nuclear maturation rate. The oocytes derived from medium antral follicles exhibited the highest nuclear maturation rate in a regular culture system. Compared with oocytes cultured in a regular culture system, those cultured in the pre-IVM culture system exhibited considerable overexpression of HAS2, PTGS2, and TNFAIP6. Porcine embryos treated with melatonin during IVC exhibited markedly improved quality and developmental competence after PA. Notably, melatonin supplementation during the IVM period can reduce and increase the levels of intracellular reactive oxygen species (ROS) and glutathione (GSH), respectively. Conclusion: Our findings indicate that the Pre-SF(+)hCG culture system increases the nuclear maturation rate of small antral follicle-derived oocytes and the expression of genes involved in cumulus expansion. Melatonin supplementation during IVC may improve the quality and increase the blastocyst formation rate of porcine embryos. In addition, it can reduce and increase the levels of ROS and GSH, respectively, in mature oocytes, thus affecting subsequent embryos.

• 한국자동차공학회논문집
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• 제12권2호
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• pp.83-90
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• 2004

A flywheel-driven rapid compression and expansion machine is developed and utilized for experimental study of homogeneous charge compression ignition combustion. Compression ignition of homogeneous charge in IC engines offers possibilities of realizing ultra-lean engine operation with greatly reduced NOx and particulate formation. Fundamental investigations are carried out in order to better understand this ideal engine combustion mechanism. Perfectly premixed propane-air mixtures of various equivalence ratio are compression-ignited in the rapid compression and expansion machine, and the characteristics of the auto-ignition and the following combustion process are analyzed.

• KDI Journal of Economic Policy
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• 제39권2호
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• pp.1-23
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• 2017

Korea's rapid export expansion suddenly began in the early 1960s and boosted the economy. This paper's investigation finds that it began in 1961, as new export items appeared, export of which increased incomparably faster than that of the current export items at the time. How and why of this highly unusual phenomenon can best be explained by a major reform of foreign exchange system in February 1961. This goes against the widely held view that the switch in development policy from import substitution to export promotion in the mid-1960s was the reason for Korea's export success. Rather, the evidence indicates that the rapid export expansion led to the policy switch. The government's export promotion since the policy switch helped the rapid export expansion continue into the 1970s, despite the protectionist import policy.