• 한국인구학
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• 제32권2호
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• pp.141-159
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• 2009

우리나라는 2002년 초저출산 사회(합계출산율 1.3명 이하)로 진입한 후 합계출산율이 평균 1.2 이하인 상황이 지속되고 있다. 이러한 초저출산 상황이 향후 지속된다면 인구고령화의 사회 경제적 여파가 예상보다 클 것으로 전망된다. 과연 이런 초저출산 추세가 일시적인 것인지 아니면 앞으로 계속 지속될 것인지에 대한 검토가 필요하다. 이에 본 연구는 최근 저출산함정 가설(low fertility trap hypothesis)을 제기한 Lutz, Skirbekk and Testa(2006)의 논의를 소개한다. 그들은 크게 인구학적, 사회적, 그리고 경제적 요인과 같이 3가지 요인으로 구분하여 저출산함정의 존재 가능성을 논하고 있다. 그렇다면 과연 우리나라는 저출산함정에 빠져 있는가? 먼저 고령화 가설의 경우 출생아수와 고령화간 부(-)의 관계가 나타나고 있으며, 최근 이상자녀수가 2.2~2.3명이지만, 실제자녀수는 그 수준을 하회하고 있어 이상자녀수가설도 지지된다. 상대소득가설의 경우, 류덕현(2007)의 연구결과에 따르면 연령 계층 간 상대소득이 출산율에 정(+)의 효과를 보여 상대소득가설이 지지되는 것으로 나타났다. 물론 제한된 영역에서 완벽한 검증이 이루어진 것은 아니지만, 적어도 출산율이 대체수준까지 회복되기에는 어려운 상황이라는 점을 발견할 수 있었으며, 이는 우리나라의 저출산 문제가 얼마나 심각한 수준인지를 재확인시켜준다.

• 공학교육연구
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• 제13권5호
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• pp.49-54
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• 2010

We report about the international cooperative activities for the engineering education between a German University and a Japanese University. After the experiences for 15 years of cooperation, both in research and student exchange, we learned a lot about the differences between these two educational systems. This report summarizes the differences and the future perspective for the improvement of engineering education based on the understanding of the differences, including advantages and disadvantages, between two educational systems.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• 제3권1호
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• pp.110-115
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• 2000

저자들은 비근친 부모에게서 출생하여 신생아담즙 정체증, 선천성 다발성 관절 구축증 및 원위형 신세뇨관성 산증 소견을 보인 1례의 남아 및 1례의 여아에서 ARC증후군을 경험하였기에 문헌고찰과 함께 보고하는 바이다.

• 대한수학회지
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• 제44권3호
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• pp.683-695
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• 2007

A tournament is an orientation of a complete graph, and in general a multipartite or c-partite tournament is an orientation of a complete c-partite graph. In a recent article, the authors proved that a regular c-partite tournament with $r{\geq}2$ vertices in each partite set contains a cycle with exactly r-1 vertices from each partite set, with exception of the case that c=4 and r=2. Here we will examine the existence of cycles with r-2 vertices from each partite set in regular multipartite tournaments where the r-2 vertices are chosen arbitrarily. Let D be a regular c-partite tournament and let $X{\subseteq}V(D)$ be an arbitrary set with exactly 2 vertices of each partite set. For all $c{\geq}4$ we will determine the minimal value g(c) such that D-X is Hamiltonian for every regular multipartite tournament with $r{\geq}g(c)$.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 Proceedings ICPE 98 1998 International Conference on Power Electronics
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• pp.246-251
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• 1998

This paper describes the main features of an unconventional tester for high power semiconductor devices. Two application ranges are highlighted. The tester is used for the extraction of GTO parameters and their verification by measurements. The second field comprises the determination of the radial and azimuthal current density distribution of a GTO tablet. The results are compared with the carrier lifetime distribution.

• International Journal of Automotive Technology
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• 제3권2호
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• pp.53-56
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• 2002

A new generation of the BMW child seat and occupant detection system SBE2 far a smart airbag system is described. The SBE2 system consists of two subsystems: OC (Occupant Classification) and FDS (Field Detection System). The OC system is a force sensitive sensor array that measures a pressure profile. The FDS system detects child seat and occupant according to the change of electrical field generated by four capacitive plates. Combining the signals from both subsystems, the BMW SBE2 system can distinguish fully automatically between a child seat and a person.

• 한국통신학회논문지
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• 제29권12C호
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• pp.1633-1641
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• 2004

위성 디지털 방송이나 위성 인터넷에서는 위성에서 단말에 이르는 고속 리턴 채널 환경이 매우 나빠 연집오류가 심하게 생긴다. 이 논문에서는 리턴 채별이 레일리 확률 채널일 때, 앞 오류 고침 (forward error correction: FEC) 부호화 방식의 성능을 분석한다. 먼저, Loo, Lutz, Vucetic, Corazza의 채별 모형을 고찰하고, Rayleigh 페이딩 채널에서 길쌈 부호, 리드 솔로몬 부호, 길쌈-리드 솔로몬 연접 부호 터보 부호의 성능을 비교 분석한다.

• 대한기계학회논문집A
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• 제27권5호
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• pp.840-847
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• 2003

The bonding of adhesive joints of adhesive joints is influenced by the surface roughness of the joining Parts. However, the magnitude of the influence has not yet been clarified because of the complexity of the phenomena. In this study, it is shown that surface treatment affects adhesive strength and durability of alumina/polycarbonate single-lap .joints, and leading speed affects tensile-shea strength of adhesive Joints. To evaluate effect of surface treatments on the adhesive strength, several surface treatment methods are used, that is, cleaning, grinding, SiC polishing and sand blasting. It is shown that an optimum value of the surface roughness exists with respect to the tensile-shea strength of adhesive joints. The adhesive strength shows linear relationship with the surface roughness and loading speed. And the mechanical removal of disturbing films of lubricants, impurities and oxides make adhesive strength increase significantly.

• Journal of Microbiology and Biotechnology
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• 제23권8호
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• pp.1092-1098
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• 2013

Cassava constitutes an abundant substrate in tropical regions. The production of butanol in ABE fermentation by Clostridium beijerinckii BA101 using cassava flour (CF) was scaled-up to bioreactor level (5 L). Optimized fermentation conditions were applied; that is, $40^{\circ}C$, 60 g/l CF, and enzymatic pretreatment of the substrate. The batch fermentation profile presented an acidogenic phase for the first 24 h and a solventogenic phase afterwards. An average of 37.01 g/l ABE was produced after 83 h, with a productivity of 0.446 g/l/h. Butanol production was 25.71 g/l with a productivity of 0.310 g/l/h, high or similar to analogous batch processes described for other substrates. Solvent separation by different combinations of fractioned and azeotropic distillation and liquid-liquid separation were assessed to evaluate energetic and economic costs in downstream processing. Results suggest that the use of cassava as a substrate in ABE fermentation could be a cost-effective way of producing butanol in tropical regions.

• 대한수학회지
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• 제46권6호
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• pp.1309-1318
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• 2009

Let k be a positive integer, and let G be a simple graph with vertex set V (G). A Roman k-dominating function on G is a function f : V (G) $\rightarrow$ {0, 1, 2} such that every vertex u for which f(u) = 0 is adjacent to at least k vertices $\upsilon_1,\;\upsilon_2,\;{\ldots},\;\upsilon_k$ with $f(\upsilon_i)$ = 2 for i = 1, 2, $\ldot$, k. The weight of a Roman k-dominating function is the value f(V (G)) = $\sum_{u{\in}v(G)}$ f(u). The minimum weight of a Roman k-dominating function on a graph G is called the Roman k-domination number ${\gamma}_{kR}$(G) of G. Note that the Roman 1-domination number $\gamma_{1R}$(G) is the usual Roman domination number $\gamma_R$(G). In this paper, we investigate the properties of the Roman k-domination number. Some of our results extend these one given by Cockayne, Dreyer Jr., S. M. Hedetniemi, and S. T. Hedetniemi [2] in 2004 for the Roman domination number.