• 한국자동차공학회논문집
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• 제10권2호
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• pp.141-149
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• 2002

Most of mechanical failures are caused by repeated loadings and therefore they are strongly related to fatigue. To avoid the failures caused by fatigue, determination of an optimal shape of a structure is one of the very important factors in the initial design stage. Shape optimization for three types of specimens, which are very typical ones in opening mode in fracture mechanics, was accomplished by the linear elastic fracture mechanics and the growth-strain method in this study. The linear elastic fracture mechanics was used to estimate stress intensity factors and fatigue lives. And the growth-strain method was used to optimize the shape of the initial shape of the specimens. From the results of the shape optimization, it was concluded that shapes of three types of specimens optimized by the growth-strain method prolong their fatigue lives very much.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
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• pp.174-175
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• 2005

Initial growth stage was investigated for SiC homoepitaxial film growth using 'step controlled epitaxy' technique. When the off angel direction is located parallel along to the gas flow direction, the smoother surface can be obtained. On the on axis substrates, selective etching was detected both the etching and growth condition. It was deduced that the high ratio of C/Si in the source gas results in well developed steps and etched spiral around micropipes.

• 한국강구조학회 논문집
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• 제11권4호통권41호
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• pp.409-416
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• 1999

반복하중을 받는 용접구조물의 피로수명 추정에 있어서 파괴역학을 이용한 피로균열 진전해석방법은 매우 유용하다. 휨응력을 받는 바닥강판의 피로균열 진전해석 문제에서는 균일한 축하중 하에서의 피로균열 진전해석 절차를 동일하게 적용할 수 있다. 본 연구에서는 휨응력하에서 피로균열 진전수명을 계산하는 방법을 제시하고 2차원 균열 문제에서의 피로균열 진전을 다루었다. 수치적으로 계산된 균열진전은 균열길이가 증가함에 따라 피로균열의 진전속도가 점차 감소하고 실험결과와 잘 일치하였다. 피로 수명은 초기균열길이와 균열형상에 따라 달라짐을 알 수 있었다.

• Journal of Welding and Joining
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• 제7권1호
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• pp.28-35
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• 1989

The fatigue crack growth behavior in GTA butt welded joints of Al-Alloy 5052-H38 was examined using Single Edge Notched(SEN) specimens. It is well known that welding residual stress has marked influence on fatigue crack growth rate in welded structure. In the general area of fatigue crack growth in the presence of residual stress, it is noted that the correction of stress intensity factor (K) to account for residual stress is important for the determination of both stress intensity factor range(.DELTA.K) and stress ratio(R) during a loading cycle. The crack growth rate(da/dN) in welded joints were correlated with the effective stress intensity factor range(.DELTA.Keff) which was estimated by superposition of the respective stress intensity factors for the residual stress field and for the applied stress. However, redistribution of residual stress occurs during crack growth and its effect is not negligible. In this study, fatigue crack growth characteristics of the welded joints were examined by using superposition of redistributed residual stress and discussed in comparison with the results of the initial welding residual stress superposition.

• The Journal of Asian Finance, Economics and Business
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• 제6권1호
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• pp.107-119
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• 2019

This paper examines the impact of financial integration on economic growth in Southeast Asia over the period 1993-2013. This paper further investigates whether the relationship depends on the level of financial and economic development, government corruption, and macroeconomic policy. These questions raise important issues both from a theoretical and a policy perspective. We employ the generalized methods of moment (GMM) in the dynamic panel estimation framework to analyse several factors, including initial income, initial schooling, financial development, inflation, trade openness, corruption, and financial crisis. The study further analyzes the data using the EGLS model to examine the consistency of the GMM model. We found that financial integration has a significant positive effect on economic growth in Southeast Asia. Our findings suggest that increasing financial integration could improve the productive capacity of the economy, including more investments and efficient allocation of capital, and thus enhancing economic growth in this region. More specifically, the results suggest that the government should work towards eliminating corruption and stabilizing macroeconomics in order to enhance financial integration and economic growth. This paper sheds new insights on a better evaluation of the past and present theorizing on the subject of financial integration and economic growth; especially, in Southeast Asia.

• 한국산학기술학회논문지
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• 제11권7호
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• pp.2371-2385
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• 2010

IT 창업 기업이 창업 초기 단계를 지나 성공적으로 성장 단계에 진입 할 수 있는 성공 요인은 무엇일까? 고용 없는 성장의 지속과 경제 침체는 고용 상황을 악화시키고 있다. 일자리를 창출하고 경제적 격차를 줄이기 위한 방안의 하나로 창업이 제시되고 있다. 창업에 대한 연구와 정부 정책의 지원은 이미 오래 전부터 시행되어왔다. 창업 이후 초기 단계 기업의 성장과 존속에 대한 연구는 성장 단계를 지나 상장 단계에 이른 기업에 대한 것과 비교하여 양적, 질적으로 미미하다. 따라서 본 연구는 창업 초기 단계의 기업이 성장과 존속을 하기 위해 필요한 요인에 대해 사례를 통해 탐색한다. 창업 초기 단계에서 IT 창업 기업의 성장과 존속 성공 요인에 대한 연구와 모델을 제안하고, 모델을 실증하기 위해서 사례 연구를 실시했다. 사례 연구의 대상 기업은 제조업의 특성을 가진 하드웨어 관련 개발 기업 군과 소프트웨어 개발 기업군으로 분류하였다. 정부 출연 사업에 선정 되어 성공적으로 과제를 수행하여 최종 완료평가에서 성공 판정을 받는 것은 창업 초기 단계의 IT 창업 기업에게는 성장과 존속의 실체적인 증명이라 할 수 있을 것이다. IT 창업 기업의 초기 단계 성장과 존속에 영향을 미치는 요인은 내부적 요인, 외부적 요인, 성장 단계의 특성에 따른 요인, 종합적 요인으로 나눌 수 있다. 본 연구의 결과는 IT 창업 기업의 예비 창업 교육 프로그램 및 컨설팅 가이드라인 개발, 지원정책 수립 등에 활용될 수 있다.

• KSBB Journal
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• 제8권2호
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• pp.178-184
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• 1993

Extractive fermentations with the extract of Jerusalem artichoke in an aqueous-two-phase-system of polyethyleneglycol(PEG) and dextran(Dx) were investigated to obtain the effects of composition of PEG and Dx on both fermentation ,characteristics and partition ratio of alcohol. The specific growth rate of K. Fraglis CBS 1555 increased with a decrease of concentration of PEG and Dx. It augmented along with concentration of initial sugar up to 80g/l but decreased thereafter. The specific production rate of alcohol showed a rising tendency up to 100g/lof initial sugar, whereafter represented a decreasing trend. The partition ratio of alcohol between two phases augmented according to decrease of Dx comic. and increase of PEG cone. regardless of initial sugar concentrations. The ratio, however, decreased with Increment of initial sugar concentration at constant composition of PEG and Dx. The partition coefficient of alcohol had an ascending effect to the increase of PEG cone, but it had little effect on the changes of concentrations of Dx and initial sugar. The present study suggests that the optimum composition of PEG and Dx in the aqueous-two-phase-system by extractive fermentation were around 6.5%(w/v) of PEG and 3%(w/v) of Dx in considerations of emulsion state, sedimentation and separation of two phases, alcohol partition ratio, and specific growth rate.

• 한국자원식물학회지
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• 제26권6호
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• pp.709-717
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• 2013

The objective of this study was to examine the effect of root pruning intensity in combination with different initial seedling size on the growth of transplanting seedlings of Quercus acutissima. One-year-old seedlings were divided into three groups depending on their height, i.e. small (< 15 cm), medium (25-35 cm) and large size (35 cm <). Root of seedlings was pruned by three intensity such as, leaving 5 cm (severe), 10 cm (medium) and 15 cm (light) of taproot from the root-collar. After one year, we investigated survival rate, height and root-collar diameter (RCD) increment and final shoot dry weight. Also we measured characteristics of newly developed lateral roots such as number, total length, dry weight and diameter. Severe root pruning showed the lowest survival rate in all seedling size. Height increment, RCD increment and shoot dry weight were decreased with increasing intensity of root pruning. Seedlings of medium and light root pruning showed similar above-ground growth and dry weight of lateral roots. More large seedlings showed good survival rate, height increment and final shoot dry mass in all root pruning intensity. Therefore, one-year-old seedlings of Q. acutissima should be pruned taproot by 10 cm and transplanted to obtain excellent performance and increase the efficiency of transplanting work. Based on the findings of this study, it is important that applying to different root pruning intensity depending on initial seedling size for producing 2-year-old seedlings with excellent growth and high quality.

• Clinical and Experimental Pediatrics
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• 제61권7호
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• pp.221-225
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• 2018

Purpose: Congenital hypothyroidism (CH) is the most common endocrine disorder in children. Thyroid hormone deprivation results not only in mental retardation but also growth retardation. This study investigates the final height (FH) in Korean patients with CH detected by newborn screening and examines factors that may affect the FH. Methods: The medical records of Korean CH patients (n=45) were reviewed. The FH was examined and target height (TH) was calculated based on mid-parental height. The FH z score (FHZ) and TH z score (THZ) were computed using the 2007 Korean National Growth Chart. The FHZ and THZ were compared with a Student t test. The impact of the etiology of CH (athyreosis, dyshormonogenesis, ectopic thyoid, hypoplastic thyroid), initial serum thyroid stimulating hormone (TSH) level, initial free thyroxine (T4) level, and time of therapy initiation based on FH was assessed. Results: The mean FHZ was $0.10{\pm}1.01$ for male patients and $-0.11{\pm}1.09$ for female patients. There were no significant differences between FHZ and THZ for both female (P=0.356) and male patients (P=0.237). No significant relationship was found between FH and the etiology of CH, initial TSH level, initial free T4 level, and the time of therapy initiation. Conclusion: Early intervention and satisfactory management do not appear to impede growth in Korean patients with CH. Thus, early detection and proper management of patients with CH detected by newborn screening program are necessary.

• KSBB Journal
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• 제4권2호
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• pp.134-142
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• 1989

Aureobasidium pullulans에 의한 세포외 다속류 생성연구를 통한 결론은 다음과 같다. (1) sucrose 농도가 50 g/l 이상일 때는 기질에 의한 저해 작용이 나타나고 있음을 알았으며 실소원의 증가에 따라서 균체량은 증가하지만 세포외 다속류 생성은 최적농도 (1 g/l )까지 증가하고 그 이상에서는 감소했으며 멜라닌 색소 출현시간은 길어졌다. (2) 최대 균체 성장은 초기 pH 3.0에서 보인 반면에 세포외 다속류 생성은 초기 pH 7.5에서 최대 값은 나타내었고 최대 PH가 증가함에 따라서 효모형 비율이 증가했으며 멜라닌 색소 출현시간은 pH 4.5~8까지는 거의 일정하게 나타났지만 pH 3 이하에서는 전혀 멜라닌 색소가 나타나지 않았다. (3) 탄소원과 실소원을 증가시켰을 때 pH 5 이하에서는 멜라닌 색소는 나타나지 않았으나 pH 6에서 pH 8.5 로 pH가 높아짐에 따라 멜라닌 색소는 빨리 나타나는 경향을 보였다. (4) 용존산소 농도가 높을수록 균체량과 세포외 다속류 생성이 증가했고 멜라닌 색소 출현시간이 빨라졌으며 potassium phosphate가 전혀 들어있지 않는 배지에서는 멜라닌 색소 출현은 관찰할수가 없었다.