• 한국해양공학회지
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• 제10권1호
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• pp.53-64
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• 1996

In this paper, rotating bending fatigue tests have been carried out to investigate the growth behabiors of surface fatigue crack initiated from a small artificial surface defect, that might exist in real structures, on 2024-T3 and 6:4 brass. The test results are analysed in the viewpoints of both strength of materials and fracture mechanics, it can be concluded as follows. The effect of a small artificial surface defect upon the fatigue strength is very large. The sensitivity of 2024-T3 on the defect is higher than that of 6:4 brass. The growth behavior of the surface fatigue crack of 2024-T3 is different from that of 6:4 brass. The growth rate of the surface fatigue crack of 2024-T3 is considerably rapid in the early stage of the fatigue life and apt to decrease in the later stage. It was impossible to establish a unifying approach in the analysis of crack growth begabior of 2024-T3 and 6:4 brass using the maximum stress intensity factor because of their dependence on stress level. But if the elastic strain and cyclic total strain intensity factor range were applied to obtain the growth rate of surface fatigue cracks of the materials, the data were found to be nearly coincided.

• 한국재료학회지
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• 제14권12호
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• pp.829-834
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• 2004

Annealing of $Cu(B)/Ti/SiO_2$ in vacuum has been carried out to investigate the effects of Ti underlayer on microstructure in $Cu(B)/Ti/SiO_2$ structures. For comparison, $Cu(B)/Ti/SiO_2$ structures was also annealed in vacuum. Three different temperature dependence of Cu growth can be seen in $Cu(B)/Ti/SiO_2$; B precipitates- pinned grain growth, abnormal grain growth, normal grain growth. The Ti underlayer having a strong affinity for B atoms reacts with the out-diffused B to the Ti surface and forms titanium boride at the Cu-Ti interface. The formation of titanium boride acts as a sink for the out-diffusion of B atoms. The depletion of boron in grain boundaries of Cu films, as results of the rapid diffusion of B along the grain boundaries and the insufficient segregation of B to the grain boundaries, induces grain boundaries to migrate and causes the abnormal grain growth. The increased bulk diffusion coefficient of B within Cu grains can be responsible for the normal grain growth occurring in the annealed $Cu(B)/Ti/SiO_2\;at\;600^{\circ}C$. In contrast, the $Cu/SiO_2$ structures show only the abnormal growth of grains and their sizes increasing as the temperature increases above $400^{\circ}C$.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2001년도 춘계학술발표대회 개요집
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• pp.220-223
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• 2001

In this study, CT specimens were prepared hem ASTM SA516 which was used for pressure vessel plates for room and low temperature service. And we got the following characteristics from fatigue crack growth test carried out in the environment of room and low temperature at $25^{\circ}C$, -3$0^{\circ}C$, -6$0^{\circ}C$, -8$0^{\circ}C$, -l$0^{\circ}C$ and -l2$0^{\circ}C$ and in the range of stress ratio of 0.1, 0.3 by means of opening mode displacement. At the constant stress ratio, the threshold stress intensity factor range ΔK$_{th}$ in the early stage of fatigue crack growth ( Region I ) and stress intensity factor range ΔK in the stable of fatigue crack growth ( Region II) was increased in proportion to descend temperature. It assumed that the fatigue resistance characteristics and fracture strength at low temperature is considerable higher than that of room temperature in the early stage and stable of fatigue crack growth region. The straight line slope relation of logarithm da/dN - ΔK in Region II, that is, the fatigue crack growth exponent m increased with descending temperature at the constant stress ratio. It assumed that the fatigue crack growth rate da/dN is rapid in proportion to descend temperature in Region H and the cryogenic-brittleness greatly affect a material with decreasing temperature.e.greatly affect a material with decreasing temperature.

• 한국습지학회지
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• 제4권2호
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• pp.1-11
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• 2002

The morphology, seed germination, and life history of Salix nipponica were investigated in the wetland of the Nam-River, Jinju, Gyeongsangnam-do, Korea from 2000 to 2001 to provide the basic data necessary for riverine ecosystem restoration through understanding the growth characteristics of Salix nipponica. Salix nipponica had stomata on only lower side and stomata type was paracytic. Salix nipponica produced many small and light seeds. The seed number per mature ament was 1599.4, seed mass of 0.04 mg, and fertilization rate of 66.1%. Seed germination was little affected by light. Germination rate was high and mean germination time was short Under flooding condition, seeds were germinated normally and were viable after as much as 14 days of flooding. But there were no differences under various water depths on germination rates. Tree age was closely correlated with more stem diameter than tree height and there was no difference of growth rate between male and female tree. Growth rate was most rapid for 2 to 3 years after germination, and length growth was almost stopped for more than 11 years even though mass growth was done. Besides even a second-year indivisual was flowered.

• Ocean and Polar Research
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• 제40권4호
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• pp.271-280
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• 2018

The purpose of this study is to examine the causal relationship among oil consumption, oil-tanker accidents, and economic growth, and to derive policy implications from the results. Therefore, this paper attempts to analyze the short term, long term, and strong causality factors pertaining to the relationship between oil consumption, oil-tanker accidents, and economic growth in Korea using time-series techniques and annual data for the 1984-2016 period. Tests for unit roots, co-integration, and Granger-causality based on an error-correction model are presented. The results show that bidirectional causality exists between oil consumption and oil-tanker accidents, between economic growth and oil consumption, and between oil-tanker accidents and economic growth. The study shows that oil was used as a core energy source during the rapid economic growth of Korea in the past, and that this caused the number of oil-tanker accidents to rise as oil consumption increased.

• 대한수의학회지
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• 제29권3호
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• pp.275-281
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• 1989

This investigation was conducted on 249 Jindo dogs aging from 2 to 12 months to determine body type and external appearance of the dogs. The results of this investigation were as follows. 1. The withers height of male dogs growed rapidly during the period between 2 months and 7 months of age, and was 22.94cm and 49.77cm, respectively. Afterward the growth rate slowed down up to 12 months, 53.33cm. The growth rate of female was similar to male, and the withers height was 22.91cm, 46.81cm, 48.70cm at 2, 6 and 12 months of age. 2. For male and female the body length was 27.21, 27.23cm at 2 months, 51.40cm, 51.62cm at 6 months, 58.33, 52.15cm at 12 months, respectively. Growth rate of the body length was very rapid from 2 to 6 months of age, but afterwards the growth rate was slow and somewhat retarded. 3. For male and female, the withers height to body length ratio was 100 : 109.4 and 100 : 107.1 in 12 months old group. 4. Cross over between the sexes in growth rate occurred between 5.3 to 6.5 months of age for wither height, between 6.0 to 7.2 months for hody length, respectively. 5. The average chest girths of male and female were 31.46, 30.46cm at 2 months, 54.92, 52.20cm at 7months, 60.25, 57.90cm at 12months, respectively. The growth rate of chest girth was rapid between 2 to 7 months of age and gradual between 7 to 12 months. 6. The average skull lengths of male and female were 11.76, 11.32cm at 2 months, 21.83, 19.60cm at 12 months, respectively. The average head widths of male and female were 8.37, 7.94cm at 2 months, 15.47, 12.46cm at 12 months. 7. Erected type of ear was completed from oblique type at 6 months in male and 7 months in female. On our detailed examinations, we concluded that Jindo dogs completed their growth at 6 to 7 months of age.

• 한국수산과학회지
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• 제13권4호
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• pp.207-212
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• 1980

1979년 11월부터 1980년 5월까지 한산${\cdot}$거제만 내의 화도, 송도, 소랑 및 추봉양성장에시 양성하고 있는 굴에 대한 패각의 성장, 육중의 증가, 각중에 대한 육중의 비 그러고 부착기당 부착밀도에 따른 패각의 상대성장에 대해 조사하였다. 각고의 성장은 소량산 굴이 가장 좋아 5월에 10.10cm였고, 다른 세지역보다 늦게 수하한 추봉산은 4월과 5월 사이에 급성장하여 5월에는 8.65cm로 성장하여 화도(8.69cm) 및 송도산(8.57cm) 굴과 거의 같은 크기가 되었다. 소량산 굴의 육중은 2월까지 완만하게 증가하다가 2월 이후 5월까지 급성장 하였으며 화도 및 송도산은 12월과 2월, 4월과 5월 사이에 육중의 증가가 많았으며, 늦게 수하한 추봉산은 12월부터 육중의 중가가 서서히 빨라지기 시작하여 4월과 5월 사이에는 급격히 증가하였지만 육중량은 다를 지역의 것보다 적었다. 각중에 대한 육중비는 화도, 추봉 및 송도산의 증가 경향이 비슷하여 12월 이후 차차 증가하지만 소량산의 경우는 2월까지 그 비가 감소하다가 2월 이후 급격히 증가하였다. 굴 부착기당 부착 밀도별 각고에 대한 각장의 성장비 (각형)는 부착개체수가 13개 이하에서는 0.60이상으로 단형이지만 25개체까지는 0.56이었고, 28개체 이상에서는 0.51 이하로 그 비가 현저히 감소하여 장형으로 되었다.

• 벤처창업연구
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• 제15권1호
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• pp.225-235
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• 2020

한국 정부는 기술기반 창업 및 벤처기업의 육성에 노력하고 있으며, 다양한 지원 정책은 생존율 개선에 집중하고 있다. 이와 함께, 기업의 기본가정인 계속기업의 가정을 위한 지속가능경영을 가능하게 하는 전략적 수단의 발굴 또한 중요하다. 국내·외 연구에서 기업의 지속가능경영을 위하여 기업의 사회적 책임(Corporate social responsibility, 이하 CSR)을 주요 전략 수단으로 제시하고 있다. 본 연구는 이러한 CSR 활동이 벤처기업에 적용이 가능한지에 대한 실증분석을 시도한 탐색적 연구이다. 기존의 선행연구들은 대기업 중심, 설문조사 중심의 연구가 진행되었으며 기업의 특성을 반영하지 못한 한계점이 존재한다. 기존 선행연구의 한계점을 보완하고, 의미있는 시사점을 제안하기 위하여 본 연구는 정부승인통계 원시자료를 기반으로 벤처기업을 대상으로 하여 기업의 성장단계를 고려한 연구를 진행하였다. 2018 벤처기업정밀실태조사 원데이터를 기반으로 국내 벤처기업의 성장단계를 구분하여 성장단계 별 CSR 활동이 경영성과에 미치는 영향을 자료포락분석 (Data envelopment analysis, 이하 DEA)살펴보았다. 분석결과, 창업기 및 초기성장기에서는 CSR 활동이 경영성과에 영향을 미치지 못하고 있음이 발견되었다. 고도성장기 부터 적극적인 CSR 활동을 수행한 기업이 CSR 활동을 하지 않은 기업과 비교하여 경영성과가 우수한 것을 확인하였다. 마지막으로, 고도성장기 부터 벤처기업의 규모효율성은 CSR을 하지 않았을 때 가장 우수한 것으로 나타났다. 본 연구는 벤처기업의 CSR 활동이 고도성장기 이후 경영성과에 영향을 미칠 수 있음을 규명한 진취적인 연구이며, 관련 정책 및 현업 의사결정자들에게 CSR 활동이 경영성과 제고에 도움을 줄 수 있는 전략적 방안임을 제안한데에 그 의의가 존재한다.

• 한국작물학회지
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• 제56권1호
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• pp.72-79
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• 2011

본 연구는 간이 수경재배법을 이용하여 보리의 알루미늄 스트레스 내성과 민감성 품종을 간편하고 빠르게 screen하는 방법을 소개하고, 선별된 품종간의 뿌리의 생장, 뿌리 조직의 염색, 알루미늄 함량, 원형질막의 $H^+$-ATPase의 발현 변화를 조사하여 분석하였다. l. 보리 65가지 품종을 간이 수경재배법을 이용하여 $20{\mu}M$ 알루미늄을 24시간 처리 후 뿌리생장의 차이로 내성 세 품종(자예2, 자예6, 모치무기)과 민감성 세 품종(흰쌀, 올쌀, 품2)을 선별하였다. 2. 알루미늄에 내성 품종은 알루미늄 처리 농도(0, 5, 10, $20{\mu}M$)에 따라 뿌리 생장 감소폭이 적었으나, 민감성 세 품종은 상대적으로 낮은 $5{\mu}M$ 농도에서부터 80%의 생장이 억제되었다. 3. 내성인 자예2와 민감성인 품2의 알루미늄 처리 후, 농도별(0, 5, 10, $20{\mu}M$), 시간별(3, 6, 12, 24시간)로 0.2% hematoxylin으로 염색 시 주로 apex에 3시간 이후부터 염색되었으며, 민감성 품2가 내성인 자예2에 비해 농도와 시간에 따라 그 피해 정도가 매우 심각하였다. 4. $20{\mu}M$로 24 시간 처리된 뿌리 apex(10 mm)의 알루미늄 함량을 측정한 결과, 내성인 자예2는 주당 47.1 nmol의 함량을 보여 주었으나, 민감성인 품2는 주당 64.9 nmol의 높은 함량을 보여 주었다. 5. 24시간 동안 $20{\mu}M$ 알루미늄을 처리한 뿌리 원형질막 $H^+$-ATPase 발현을 western blotting을 통해 분석한 결과, 내성인 자예2는 차이가 없었으나, 민감성 품2는 현저히 억제되었다. 이로 보아 원형질막 $H^+$-ATPase가 알루미늄의 내성 기작에 관여하는 것으로 보인다. 6. 본 연구를 통해 간이 수경재배와 hematoxylin을 이용한 염색으로 간단하고 빠르게 보리의 알루미늄 내성과 민감성 품종의 screening을 할 수 있었고, 보리뿐 아니라 쌀, 밀 등의 다른 종자에도 적용할 수 있을 것이다.

• 한국항해항만학회지
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• 제27권3호
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• pp.315-320
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• 2003

Since the beginning of open-door policy, China has been making rapid annual growth with an average 10% economic development. And due to this rapid growth, cargo volumes via ports have been also rapidly increased, and accordingly, current China government has intensively invested in port development. Further, this development project is significantly big scale, compared with those project which Korea and Japan have. Thus, China is beginning to threaten Korean ports, especially Busan port which try to be a hub port in Northeast Asia. For this reason, it has been very important issue for Korea and Busan port to investigate or analyze Chinese ports based on empirical data. Especially, although various studies related to Shanghai and Hong Kong have been conducted, the competitiveness of overall Chinese major ports has been little studied. In this paper, we analyzed competitiveness level of eight Chinese ports with capabilities as container terminal, based on reliable sources. From data analysis, eight Chinese ports were classified into four groups according to competitiveness level. Rankings among four clusters based on competitiveness level are cluster(Hone Kong), cluster C(Shanghai), cluster A(Qingdao, Tianjin, and Yantian) and cluster D(Dalian, Shekou, and Xiamen).