• 한국결정학회지
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• 제3권1호
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• pp.23-30
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• 1992

단결정 a-SiC성장시 결정성장로의 감압속도가 결정 성장 속도, 결정성, 성장방향에 미치는 영향 을 고찰해 보기 위해서 승화법으로 (001)면 a-SiC 단결정 종자정위에 단결정 a-SiC를 성장시켰다. 결정성장 초기에는 성장로의 빠른 감압 속도에 따라 결정성장속도가 빨라지고 3C-SiC 다결정이 종자정위에 성장하였고, 감압속도를 느리게 한 경우에는 결정성장 속도가 느려지고 6H-SiC 단결정이 성장하였다. 초기에 단결정층이 성장하는 조건 하에서 2시간 성장후의 단면 성장 양상을 보면, 종자정 하단에서 발생하는 낙은 종자정의 연속적 인 승화 때문에 종자정과 초기의 단결정층이 소멸 되고, 종자정이 놓여있던 혹연 도가니의 바닥으로부터 연속적으로 다결정 층이 성장된 것이 관찰되었다. 그러나, 이러한 종자정의 승화 소멸은 초기 성장 후 냉각과정을 거치고 다시 승온시키는 두 단계 공정을 사용함으로써 효과적으로 억제시킬 수 있었다. 이와같은 방법으로 장시간 성장시킨 결정은 6H-HiC 단결정이었으며, (001) 방향으로 성장하였다.

• Journal of Mechanical Science and Technology
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• 제16권10호
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• pp.1246-1252
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• 2002

Ultrafine grained (UFG) low carbon (0.15 wt.% C) steel produced by equal channel angula. pressing (ECAP) was tested for investigating the effect of load ratio on the fatigue crack growth rate. Fatigue crack growth resistance and threshold of UFG steel were lower than that of asreceived coarse grained steel. It was attributed to the less tortuous crack path. The UFG steel exhibited slightly higher crack growth rates and a lower △Kth with an increase of R ratio. The R ratio effect on crack growth rates and △Kth was basically indistinguishable at lower load ratio (R >0.3), compared to other alloys, which indicates that contribution of the crack closure vanishes. The crack growth rate curve for UFG steel exhibited a longer linear extension to the lower growth rate regime than that for the coarse grained as-received steel.

• 한국신뢰성학회지:신뢰성응용연구
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• 제5권3호
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• pp.381-391
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• 2005

The level of reliability attained largely depends upon the investment in reliability growth programs during development phase. In order to find the relationship between reliability growth test time and BRTE(basic reliability tasks effectiveness) in a reliability improvement program that minimizes LCC in which contains the reliability growth cost, repair and replacement costs, and spare parts ordering costs in service with given service rate in management policy, the growth rate has been suggested proper LCC versus growth rate. This model employs the reliability growth projection with delayed fixes in avionic equipment based on AMSAA.

• 대한조선학회논문집
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• 제40권3호
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• pp.45-53
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• 2003

Ships and ocean structures are subjected to random loads caused by irregular waves. The irregularity of amplitude from random loading affects on fatigue crack growth and fatigue life. However the effects of irregularity of loading on fatigue including random loading have not been explained exactly. Therefore in this paper crack growth tests on DENT specimens under constant-amplitude loading including a single tensile overload are conducted to investigate the effect of overload on crack growth rate. The size of plastic zone and crack growth rate before and after a single tensile overloading are measured using ESPI system. Crack growth retardation model that is characterized by crack growth length and the size of plastic zone was proposed and compared with test result. From the research, the validity of proposed model is examined on crack growth retardation, and consequently fatigue life.

• Environmental Analysis Health and Toxicology
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• 제17권3호
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• pp.219-224
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• 2002

This study was carried out to examine the effects of bis (tribytyltin)oxide (TBT), endocrine disrupting compounds (EDCs). on the changes of survival, growth and oxygen consumption rate in the oliver flounder, Paralichthys olivaceus. Oliver Flounders were exposed to sublethal concentration of TBT (0, 1.67, 3.20, 6.30 and 12.50 $\mu\textrm{g}$/L) during 6 weeks. Survival rate was decreased in a concentration and exposure period-dependent way and suddenly the reduction of more than 20% occurred at TBT concentration greater than 3.20 $\mu\textrm{g}$/L. after exposure 6 weeks. Growth rate and feed efficiency significantly decreased at concentration greater than 3.20 $\mu\textrm{g}$/L. Oxygen consumption rate was also decreased in a concentration-dependent way and significantly decreased to 17,48 and 67％ than that of the control at the TBT concentration of 3.20, 6.32 and 12.50 $\mu\textrm{g}$/L, respectively. This study revealed that high TBT concentration ($\geq$3.20 $\mu\textrm{g}$/L) reduced growth and oxygen consumption rates of the juvenile oliver flounder suggesting potential influence on the natural mortality of Paralichthys olivaceus in the coastal areas.

• Journal of Nutrition and Health
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• 제26권6호
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• pp.783-792
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• 1993

This study examined the difference in growth rate between Korean breast-fed(BF) and formula-fed(FF) infants(n=31) at 1, 2 and 3 months postpartum. The results indicated that the growth rate was comparable between groups, but that of the BF infants tended to be slow during the first three months. The intakes of energy, protein and lipid except lactose of the FF infants were greater than those of the BF infants, however the difference in growth rate did not correlate to these variables. But these results suggest that the availability of nutrients might be different between the BF infants and the FF infants.

• 한국미생물·생명공학회지
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• 제43권3호
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• pp.187-194
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• 2015

인간의 위장관은 매우 복잡한 장내균총으로 이루어져 있으며, 장내균총은 인간의 생리 기능에 있어 매우 중요한 역할을 담당하고 있다. 특히 유아기의 장내균총의 불균형은 면역연관 질병을 일으키는 요인이며 치료 목적으로 probiotics가 유용하게 활용되고 있다. Probiotics의 대표 균종은 L. plantarum으로서 영유아기에 병원균보다 가장 먼저 정착해야 면역 질환을 예방할 수 있다. 그러나 아직 Lactobacillus가 장의 우점종으로 정착하기 위한 환경적 요인과 항생물질분비 조절에 대한 이해는 부족한 실정이다.

• 한국작물학회지
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• 제44권3호
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• pp.282-287
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• 1999

The object of this study was to determine the difference of the time course changes of transpiration, diffusion resistance and photosynthetic rate of rice at several different growth stages subjected to soil moisture stress (SMS) and recovery by irrigation. A japonica rice cultivar 'Dongjinbyeo', was grown under flooded condition in a plastic container filled with silty loam soil. At 5 main growth stages, the container was treated by SMS until initial wilting point (IWP) and then reirrigated. The duration of SMS until IWP were the longest, 13 days for tillering stage, and the shortest, 7 days for panicle initiation and meiosis stage. The transpiration rate rapidly decreased during SMS and the transpiration rate at IWP of the stressed plant showed 10∼20% compared with control, and the transpiration rate of stressed plant at most growth stages also recovered rapidly after irrigation and then reached 100% of control within a week. The shoot photosynthetic rate in all growth stages rapidly decreased by SMS, and the rates at IWP of stressed plants were de-creased nearly to 0%, beside the treatment at tillering stage. The recovery degree of photosynthetic rate by irrigation ranged from 20 to 90%, showed higher at early growth stages of SMS treatment than that of later stages. At all growth stages the leaf diffusion resistance of stressed plants was over 3 times that of the control resulting from a rapid increase at 3 to 5 days after draining for SMS, and showed quick recovery by irrigation within 3 days after drainage. The above physiological parameters changed in close relation with the decrease of the soil matric potential after SMS. These results indicate that at all main growth stages of rice plants the transpiration and photosynthesis reduction by stomatal closure reponded sensitively to the first stage of SMS closely related with decrease of soil water potential, while those recovery pattern and recovered degree by irrigation are little different by growth stage of rice.

• Journal of Welding and Joining
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• 제28권5호
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• pp.45-50
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• 2010

The fatigue crack growth characteristics of base metal and weld joint of 9% Ni steel for LNG storage tank was carried out using CT specimen at room temperature and $-162^{\circ}C$. Fatigue crack growth rate of base and weld metals at RT and $-162^{\circ}C$ was coincided with a single line independent of the change of stress ratio and temperature. In the region of lower stress intensity factor range, fatigue crack growth rate at $-162^{\circ}C$ was slower than that at RT, and the slop of fatigue crack growth rate at $-162^{\circ}C$ increased sharply with propagating of fatigue crack, fatigue crack growth rate at RT and $-162^{\circ}C$ was intersected near the region of $2{\times}10-4\;mm$/cycle, and after the intersection region, fatigue crack growth rate at $-162^{\circ}C$ was faster than that at RT. The micro-fracture mechanism using SEM shows the ductile striation in the stable crack growth region. Also the defects of weld specimen after fatigue testing were detected using the A scan of ultrasonic apparatus.

• 한국벤처창업학회:학술대회논문집
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• 한국벤처창업학회 2006년도 추계학술발표회
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• pp.197-217
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• 2006

본 연구는 수출을 기반으로 성장을 하는 우리나라 벤처 기업의 수출성장에 미치는 영향요인을 분석하는 것을 목적으로 한다. 기존 연구에 대한 문헌조사를 통하여 수출과 관계된 기업의 존속여부와 성장성(매출액 성장성)은 기업내부의 여러 가지 요인 및 기업을 둘러싸고 있는 외부적 환경과의 일정한 상관관계와 인과관계의 틀 속에서 기업의 존속여부와 성장성(수출액 성장성)이 결정된다고 생각할 수 있다. 또한 기업을 둘러싸고 있는 외부적환경은 기업 스스로의 힘과 의지에 의해서 통제될 수 없는 부분이라고 생각할 수 있는바 기업의 존속여부와 성장성(수출액 성장성)은 기업내부의 요인에 의하여 결정된다고 판단 할 수 있다. 기업의 성장성(수출액 성장성)을 결정하는 중요한 요인에는 어떤 것이 있으며 그러한 요인이 어느 정도의 영향력으로 기업의 성장성(수출액 성장성)에 영향력을 미치는가를 요인간의 모형으로 설정하고자 한다.