• Magazine of the Korean Society of Agricultural Engineers
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• v.15 no.4
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• pp.3137-3146
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• 1973

This study was to investigate the effects of compaction, compressive strength and Atterberg limits in accordance with the temperatures changes. It was conducted on four soils-KJ, JJ, MH, SS-at temperatures of -1, 1, 3, 5, 7, 10, 15, 19, $22^{\circ}C$. These tests were obtained the maximum dry density and the optimum moisture content of four soils in accordance with temperature changes by using distilled water and $CaCl_2$ 10% solution, and were put to the compressive strength tests on remolded specimens of soils compacted at the optimum moisture content. The result of the study can be summarized as follows; The maximum dry density increased with an increase in temperature, and the use of $CaCl_2$ 10% solution had higher maximum dry density than distilled water. The optimum moisture content decreased with an increase in temperature, and the use of $CaCl_2$ 10% solution had lower optimum moisture content than distilled water. The maximum compressive strength was shown high peak from $7^{\circ}C\;to\;15^{\circ}C$, and the use of $CaCl_2$ 10% solution had higher maximum compressive strength than distilled water. The liquid limit and plasticity index decreased with an increased in temperature. It is estimated that the use of $CaCl_2$ 10% solution can lower the minimum compacted temperature from $2^{\circ}C\;to\;4^{\circ}C$ in low temperature.

• Journal of the Korea Institute of Military Science and Technology
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• v.14 no.6
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• pp.1192-1197
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• 2011

Recent developments of small-size unmanned or manned mobile systems such as autonomous robots, exoskeleton or armored suits, micro air vehicles, and unmanned armored vehicles require long-lasting independent power sources of high energy and power density to support the systems' operation for up to 72 hours in the fields. Chemical batteries such as Ni-MH, Li-Ion, the current primary power sources for mobile devices, however, are not capable of providing enough power and energy density for the next generation high power mobile machines. For this reason, KIMM along with KERI and KIMS has been carrying out a 500W MTG development project under the DAPA's "Next generation military power source R&D program" since 2009. In this paper, a design process for a 500W MTG system currently being developed at KIMM is briefly described and the technical issues related to its development are addressed.

• Korean Journal of Materials Research
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• v.25 no.3
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• pp.155-164
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• 2015

Porous metals are called as a new material of 21th century because they show not only extremely low density, but also novel physical, thermal, mechanical, electrical, and acoustic properties. Since the late in the 1990's, considerable progress has been made in the production technologies of many kinds of porous metals such as aluminum, titanium, nickel, copper, stainless steel, etc. The commercial applications of porous metals have been increased in the field of light weight structures, sound absorption, mechanical damping, bio-materials, thermal management for heat exchanger and heat sink. Especially, the porous metals are promising in automotive applications for light-weighting body sheets and various structural components due to the good relation between weight and stiffness. This paper reviews the recent progress of production techniques using molten metal bubbling, metal foaming, gas expansion, hollow sphere structure, unidirectional solidification, etc, which have been commercialized or under developing, and finally introduces several case studies on the potential applications of porous metals in the area of heat sink, automotive pannel, cathod for Ni-MH battery, golf putter and medical implant.

• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.339-339
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• 2017

손상함수란 건물, 차량, 농작물 등과 같은 피해대상물에 재난강도에 따른 취약도(vulnerability)를 정량화한 함수로, 재난리스크 모델에서 널리 사용되는 개념이다. 홍수재난에서 손상함수는 일반적으로 피해지역에서 조사된 경험적 피해자료(empirical data)를 활용하거나, 표준화된 피해대상물에 대한 손상성을 전문가의 의견(expert opinion)을 참고하여 개발된다. 이때, 취약도를 설명하는 설명변수는 일반적으로 침수심(inundation depth)이 사용되며, 그에 따른 취약도는 손상률(percent damage)로서 상대함수 형태가 일반적이다. 본 연구는 주거건물(residential building)에 대한 손상함수 개발을 위해 자연재난 손해사정 경력자(8인)를 대상으로 표준화된 주거건물(단독주택, 아파트, 연립/다세대주택)에 대해 침수에 따른 건물 손상성을 조사하였다. 주거건물 손상성을 설명하는 최대범위는 건물내부 바닥고를 기준으로 침수심 3m까지이며, 침수심 변화에 따른 손상성을 건물신축 공종에 따라 질의하고 이를 종합하였다. 조사과정은 (1) 표준건물에 대한 정의, (2) 공종별 침수에 따른 손상여부 질의, (3) 공종별 최대 손상률 평가 및 주요 피해내역 토의, (4) 공종별 침수심에 따른 손상률 평가, (5) 결과종합의 단계로 진행되었고, 이를 통해 주거건물 유형에 따른 손상함수를 개발할 수 있었다. 본 연구에서 개발된 손상함수는 다양한 침수높이에서 주거건물에 대한 취약도를 설명하는 데 장점이 있으나, 그 결과는 향후 홍수피해지역을 대상으로 수집된 다양한 피해조사 결과와 비교하여 보완될 필요가 있다.

• Bulletin of the Korean Mathematical Society
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• v.56 no.1
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• pp.57-71
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• 2019

Let R be an associative ring with identity, M a t.u.p. monoid with only one unit and ${\omega}:M{\rightarrow}End(R)$ a monoid homomorphism. Let R be a reversible, M-compatible ring and ${\alpha}=a_1g_1+{\cdots}+a_ng_n$ a non-zero element in skew monoid ring $R{\ast}M$. It is proved that if there exists a non-zero element ${\beta}=b_1h_1+{\cdots}+b_mh_m$ in $R{\ast}M$ with ${\alpha}{\beta}=c$ is a constant, then there exist $1{\leq}i_0{\leq}n$, $1{\leq}j_0{\leq}m$ such that $g_{i_0}=e=h_{j_0}$ and $a_{i_0}b_{j_0}=c$ and there exist elements a, $0{\neq}r$ in R with ${\alpha}r=ca$. As a consequence, it is proved that ${\alpha}{\in}R*M$ is unit if and only if there exists $1{\leq}i_0{\leq}n$ such that $g_{i_0}=e$, $a_{i_0}$ is unit and aj is nilpotent for each $j{\neq}i_0$, where R is a reversible or right duo ring. Furthermore, we determine the relation between clean and nil clean elements of R and those elements in skew monoid ring $R{\ast}M$, where R is a reversible or right duo ring.

• Asian Journal of Innovation and Policy
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• v.7 no.3
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• pp.461-488
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• 2018

This paper explores the relationship between network cooperation, innovation, internationalization and economic performance of manufacturing small and medium enterprises (SMEs) of engineering goods industry located in Bangalore city, India. At the outset, it is observed that SMEs receive the maximum assistance in the realm of product specifications. Moreover, they do not resort to manufacturing new products as much as they resort to product modifications or process improvements. Further, it is found (using Chi-square test of independence) that higher the network assistance received from an external network, greater is the innovation performance of SMEs. Subsequently, using analysis of variance (ANOVA), export intensity (proxy for internationalization performance) of SMEs is found to have a significant positive association with both the degree of their network cooperation and of their innovation performance. Lastly, it is observed that higher the degree of each of network cooperation, innovation performance and internationalization performance, better is the economic performance (measured by total sales turnover) of SMEs. These results have significant implications for the policy makers of the country to give due attention to network cooperation, innovation and internationalization as the means of enhancing the economic performance of SMEs.

• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.599-599
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• 2016

본 연구에서는 자연재해에 따른 재해 발생 시 신속하고 효율적인 대응을 위하여 시설물의 중요도 위험도 피해액 평가 인벤토리를 구축하였다. 인벤토리 구축을 수행하기 위해서 재해에 따른 시설물의 위험 발생 시 피해 시설물에 대한 구분 및 분류가 이루어져야한다. 하지만 재난관리가 수행되어야 하는 시설물 건축물의 정보가 정부 여러 기관에서 각기 다른 형태의 정보로 관리되어짐으로써 재난관리 업무의 효율적 운영에 대한 문제가 제기되어 왔다. 따라서 본 연구에서는 미국의 HAZUS-MH와 DIMSuS의 위험도와 중요도 개념을 기반으로 피해 시설물의 중요도, 위험도 등을 평가할 수 있는 항목들을 선정하고 국내 시설물 분류, 건축법규 및 자산 가치 산정 정보를 활용하여 시설물 재해 대응을 위한 인벤토리 구축을 수행하였다. 본 연구에서는 대구 성서산업단지를 TB지역으로 선정하고, TB지역내의 수변구조물, 산업시설, 주거시설 등 다양한 시설물의 속성 정보를 수집 구축하였다. 또한 신속한 재해 대응을 위해서는 시설물 정보와 공간정보를 융합한 복합적인 정보가 필요하기 때문에 TB지역의 공간정보를 구축하고 시설물의 위치 정보를 생성하고 속성 정보와 연계하여 통합 인벤토리를 구축하였다. 향후 본 연구에서 제안한 인벤토리 시스템을 활용하여 신속한 재해 대응을 위한 의사결정 도구로 활용될 것으로 판단된다.

• Asian Journal of Innovation and Policy
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• v.9 no.3
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• pp.308-338
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• 2020

The entrepreneurial journey is not short of challenges, and about 90% + tech start-ups experience failure (Startup Genome, 2019). The magnitude of the challenges varies across the tech start-up lifecycle stages, namely emergence, stability, and growth. This opens the research question, do the profiles of a start-up and its co-founder impact start-up success or failure across its lifecycle stages? This study aims to understand and identify the profiles of tech start-ups and their co-founders. We gathered primary data from 151 start-ups (Status: 101 failed and 50 successful ones), and they are across different lifecycle stages and represent six major start-up hubs in India. The chi-square test on status and start-up's lifecycle stage indicates a noticeable correlation, and they are not independent. The Kruskal Wallis test was used to distinguish statistically significant profile attributes. The parameters distinguishing success and failure are identified, and the need to deliver customer experience is emphasized by the start-up profile attributes: Product/service, high-tech nature of a start-up, investor fund availed, co-founder experience, and employee count. The importance of entrepreneurial experience is ascertained with entrepreneur profile attributes: Entrepreneurial expertise, the number of prior and current start-ups, their willingness to start again in the event of failure, and age of co-founder, which is a proxy to learning and experience. This study has implications for entrepreneurs, investors, and policymakers.

• Microbiology and Biotechnology Letters
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• v.48 no.4
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• pp.480-490
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• 2020

A novel lipase gene, Lip-1420, was isolated from a metagenomic library constructed from reed marsh from Mt. Jumbong in Korea, comprising 112,500 members of recombinant plasmids. The DNA sequence of Lip-1420-subclone (5,513 bp) was found to contain at least 11 ORFs according to the GenBank database. The ORF-3 gene was inserted into the pET21a plasmid containing the C-terminal 6-His tag and transformed into E. coli BL21(DE3) to express the recombinant lipase protein. Lip-1420 was purified using a fast protein liquid chromatography system. The gene was registered in GenBank (MH628529). The values of Km and Vmax were determined as 0.268 mM and 1.821 units, respectively, at 40℃ and pH 8.0, using p-nitrophenyl palmitate as the substrate. This lipase belongs to family IV taxonomically because it has conserved HGGG and GDSAG motifs in the constitutive amino acid sequence. According to the predicted structural model, the binding sites are represented by residues H78, G81, D150, S151, A152, V181, and D236. Finally, Lip-1420 showed triolein selectivity for methanolysis between triolein (18:1) and tristearin (18:0) substrates. Further study of the selective mechanism and structure-function relationship of this new lipase could be useful for more practical applications.

• Journal of Microbiology and Biotechnology
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• v.32 no.3
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• pp.333-340
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• 2022

Leuconostoc has been used as a principal starter in natural kimchi fermentation, but limited research has been conducted on its phages. In this study, prophage distribution and characterization in kimchi-derived Leuconostoc strains were investigated, and phage induction was performed. Except for one strain, 16 Leuconostoc strains had at least one prophage region with questionable and incomplete regions, which comprised 0.5-6.0% of the bacterial genome. Based on major capsid protein analysis, ten intact prophages and an induced incomplete prophage of Leu. lactis CBA3626 belonged to the Siphoviridae family and were similar to Lc-Nu-like, sha1-like, phiMH1-like, and TPA_asm groups. Bacterial immunology genes, such as superinfection exclusion proteins and methylase, were found on several prophages. One prophage of Leu. lactis CBA3626 was induced using mitomycin C and was confirmed as belonging to the Siphoviridae family. Homology of the induced prophage with 21 reported prophages was not high (< 4%), and 47% identity was confirmed only with TPA_asm from Siphoviridae sp. isolate ct3pk4. Therefore, it is suggested that Leuconostoc from kimchi had diverse prophages with less than 6% genome proportion and some immunological genes. Interestingly, the induced prophage was very different from the reported prophages of other Leuconostoc species.