• Journal of Forest and Environmental Science
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• 제35권4호
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• pp.232-239
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• 2019

This study was carried out to establish an efficient selection condition for cold-tolerant individuals among evergreen Quercus spp. To select higher cold-tolerant individuals among four species of evergreen Quercus spp. (Q. acuta, Q. glauca, Q. myrsinaefoila, and Q. salicina), an-year-old seedlings of each species were exposed to low temperature in serial, and then examined for the death of cell tissue and the surface temperature was monitored. It was shown that the higher numbers of seedlings of Q. myrsinaefolia were survived than the others when those seedlings are exposed to cold stress. Thus, selection of the cold tolerant individuals was conducted on Q. myrsinaefolia seedlings. The limit low temperature condition for selecting cold-tolerant individuals was -6℃ for 24 hrs because no seedling of Q. myrsinaefolia was survived after exposed to -7℃ for 24 hours. It was shown that the leaf surface temperature of the selected individuals was higher than those of the non-selected individuals when they were exposed to cold-stress while monitoring them using thermal graphic camera. The results in this study can be used for expanding afforestation area of tree species of the warm temperate zone for preparation of climate change.

• 대한한의학방제학회지
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• 제21권2호
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• pp.144-157
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• 2013

Objectives : The aim of this study was to evaluate the efficacy of Hwangnyeonhaedok-tang (HH) and Geongangbuja-tang (GB) on the plasma hormone level in mice exposed to cold stress. HH and GB are the representative prescriptions of cold and hot property, respectively. Methods : We established cold condition by confining ICR mice to a $4^{\circ}C$ cage for 24 hours, ICR mice were given a HH (100, 300, 1000 mg/kg) or GB (100, 300, 1000 mg/kg) extract orally twice a day for three consecutive days. From the second day, they were given cold stress ($4^{\circ}C$) for twenty four hours. To measure the plasma corticosterone, insulin, thyroxine, epinephrine and norepinephrine levels of mice, their blood samples were collected from cardiac puncture, immediately centrifuged at $4^{\circ}C$. The protein level of HSP70 and JNK was examined using western blot analysis in cortex and hypothalamus. Results : Oral administration of GB more significantly reduced plasma corticosterone level raised by cold stress than HH. Gardeniae Fructus (CJ), the constituent of HH, significantly increased the thyroxine level. Western blot analysis showed that cold stress-induced Heat shock protein 70 (HSP70) expression was increased by HH and GB, HH decreased JNK expression and GB increased JNK expression dose-depently in hypothalamus. Scutellariae Radix (HG), Zingiberis Rhizoma (GG) and Aconiti Tuber (BJ) decreased HSP70 in hypothalamus and GG, BJ decreased HSP70 in cortex as well. Conclusions : These results suggest Geongangbuja-tang (GB) is more effective for ameliorating the stress response caused by cold stress.

• 감성과학
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• 제14권3호
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• pp.425-434
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• 2011

본 연구의 목표는 일반적으로 사람들이 일상에서의 추위 노출 시간을 고려하여 단기간 추위노출과 지속적인 장기간의 추위 노출이 인지기능과 뇌의 신경세포생성과 신경전달물질에 미치는 영향을 규명하고자 하였다. 실험 방법으로 인지행동검사(Behavior test)와 면역조직화학법(Immunohistochemistry Method)을 실시하였다. 본 연구에서는 7주령(평균체중 $250{\pm}10g$) Sprague-Dawley 계열의 수컷 흰쥐(n=40)를 사용하여, 무선배치 방식으로 상온 대조군(n=10), 저온 3일군(n=10), 저온 5주군(n=10)으로 분류 하였다. $22^{\circ}C$(상대습도 40%)의 온도는 상온으로 설정 하였고, $4^{\circ}C$(상대습도 40%)는 추위 스트레스 환경으로 설정 하였다. 수동회피실험의 결과에 의하면, 추위 스트레스는 기억력의 감소를 가져왔다. 그러나 추위 스트레스에 의한 기억력 감소의 보상작용으로 신경전달 물질인 5-HT와 TPH의 증가가 나타나는 것을 면역조직화학법을 통해 해부시경학적으로 확인할 수 있었다. 그러나 보상작용에 의한 새로운 신경세포생성 증가가 기억력을 정상상태로 회복시키지는 못하였다.

• 동의신경정신과학회지
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• 제9권2호
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• pp.1-18
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• 1998

This study aimed to evaluate the anti-stress effects of soyosan and chyengansoyosan on the contents cold swimming stress.The experimental animals were forced cold swimming stress for 3 minutes, and administered 4㎎/10g of soyosan and chyengansoyosan extract for 7 days before stress. The monoamines contents were measured by HPLC method in various part of mouse brain. The following results were obtained :1. In frontal cortex, the contenrs of norepinephrine ans dopamine increased significantly in the group administered chyrngansoyosan compared with in the group administered non chyengansoyosan and soyosan(control group) of mice stressed by cold swiming.2. In hypothalamus, the content of norepinephrine increased with statistical significance in the group administered soyosan compared with control group of mice stressed by cold swimming. 3. The content of dopamine increased with statistical significance on the group administered chyenfansoyosan and compared with control group of mice stressed by cold swimming in hypothlaamus and hippocampus.4. The content of serotonin increased with statistical significance in the group administered soyosan and compared with control group of mice stressed by cold swimming in hippocampus and corpus striatum.5. In corpus striatum and hippocampus, the content of norepineohrine decreased with statistical significance in the group administered soyosan and chyengandoyosan compared with control group of mice stressed by cold swimming.Judgding from the above results, this sthdy reaches a conclusion that soyosan or chyengansoyosas has significant effects in reducing stress.

• 한국항공우주학회지
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• 제31권3호
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• pp.79-84
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• 2003

홀 확장법은 홀 주위에 압축 잔류응력층을 생성시킴으로서 균열 발생을 지연시키는 방법으로 항공산업 분야에서 널리 사용되고 있다. 홀 확장 잔류응력의 분포는 홀 확장률, 맨드럴 삽입방향, 재료 물성치 등 여러 가지 홀 확장 피라미터에 따라 달라진다. 홀 확장 잔류응력층의 정확한 파악은 항공산업의 실제 설계에 있어서 매우 중요함에도 불구하고 이에 대한 연구는 상대적으로 부족하였다. 본 연구에서는 유한요소해석을 통하여 두 개의 인전한 홀에 홀 확장법을 적용하는 경우 대한 잔류응력 분포를 구하였다. 연구 결과 두개 홀에 동시에 홀 확장을 하는 경우가 순차적으로 홀 확장으로 하는 경우보다 더 유리한 잔류응력 분포를 얻을 수 있었다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.99-100
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• 2006

Cold gas dynamic spray or cold-spray is a deposition process, which causes deformation of a thin substrate. The deformation is usually convex to the deposited side. In this research, the main cause of the deformation was investigated using 6061-T6 aluminum alloy. The effects or anisotropic coefficient or thermal expansion (CTE) or the deposited layer by cold-spray and residual stress were studied by experiments and finite element analysis. The Hole Drilling method was applied to measure residual stress in the cold-spray layer and substrate. The data obtained by the experiments were used for the analysis of substrate deformation. From the result of the analysis, it was concluded that compressive residual stress was the main reason of substrate deformation while CTE had little effect.

• Structural Engineering and Mechanics
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• 제53권5호
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• pp.867-880
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• 2015

Mechanical fastening is still one of the main methods used for joining components. Different techniques have been applied to reduce the effect of stress concentration of notches like fastener holes. In this work we evaluate the feasibility of combining laser shock peening (LSP) and cold expansion to improve fatigue crack initiation and propagation of open hole specimens made of 6061-T6 aluminum alloy. LSP is a new and competitive technique for strengthening metals, and like cold expansion, induces a compressive residual stress field that improves fatigue, wear and corrosion resistance. For LSP treatment, a Q-switched Nd:YAG laser with infrared radiation was used. Residual stress distribution as a function of depth was determined by the contour method. Compact tension specimens with a hole at the notch tip were subjected to LSP process and cold expansion and then tested under cyclic loading with R=0.1 generating fatigue cracks on the hole surface. Fatigue crack initiation and growth is analyzed and associated with the residual stress distribution generated by both treatments. It is observed that both methods are complementary; cold expansion increases fatigue crack initiation life, while LSP reduces fatigue crack growth rate.

• 소성∙가공
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• 제16권8호
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• pp.575-581
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• 2007

The high dimensional accuracy of the cold forged part could be acquired by the accurate dimensional modification for the die, which is, the dimensional changes from the die through forged part to final part after heat treatment were considered. The experimental and FEM analysis are performed to investigate the dimensional changes from the die to final part on cold forged part, comparing with the machined gear. The dimension of forged part is compared with the die dimension at each stage, such as, machined die, cold forged part, and heat-treated-part. The elastic characteristics and thermal influences on forging stage are analyzed numerically by the $DEFORM-3D^{TM}$. The analyzed residual stress of forged part is considered into the FE-analysis for heat treatment using the $DEFORM-HT^{TM}$. The effects of residual stress affected into the dimensional changes could be investigated by the FEA. Each residual stress of gears was measured practically by laser beam type measurement.

• 소성∙가공
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• 제17권4호
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• pp.272-277
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• 2008

A constitutive equation of the electrical steel strip used for a raw material of transformer is proposed. The stress-strain behavior of electrical steel strip is quite different from that of common carbon steel and/or alloy steel. A series of tensile tests were performed with the specimens made from cold rolled strip. Several thicknesses of the strip were produced by a two-high (with upper and lower rolls) cold rolling pilot mill as reduction ratio increases from 10% to 90%. Its initial thickness of the strip was 2.5mm. Tensile specimens are cut out from the cold rolled strips. Mechanical properties of the steel are examined through rolling direction. Ramberg-Osgood model and the proposed equation are combined to describe the total behavior of stress-strain including instability region. The stress-strain curves calculated from the present constitutive equation are compared with those from experimentally obtained at each test condition of reduction ratios of specimen. Results show that the predicted stress-strain curves are in overall in a good agreement with measured ones.

• Annals of Clinical Neurophysiology
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• 제25권1호
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• pp.32-37
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• 2023

Background: Type 2 diabetic mellitus (T2DM) is an emerging global pandemic which is associated with lots of co-morbidities and reported vascular dysfunctions. T2DM associated vascular dysfunctions leads to vasculopathy in the form of altered peripheral vascular dynamics. Cold stress test (CST) is a reliable sympathetic reactivity test used for assessing vascular dysfunctions. In this study we are trying to quantify vascular dysfunctions in T2DM patients non invasively by various parameters of photoplethysmography (PPG) of cold stress test. Methods: Case control study had done in referral health center AIIMS, Raipur. Parameters are recorded by finger-PPG before, during and after CST (1 min) in 2 groups, control (n = 20 healthy volunteers) and case (n = 20 diagnosed T2DM patients). Results: Due to cold stress, PPG parameter peak amplitude was significantly decreased in both healthy and T2DM groups (p <0.001 and p <0.001, respectively). However, recovery trend of amplitude was significantly slow in T2DM compared to healthy subjects. Another PPG parameter peak to peak interval was significantly higher in healthy group compared to T2DM patients. Conclusions: This study showed that T2DM patients has significant deranged pulse volume parameters like amplitude and peak to peak interval can be used to objectively quantify the vasculopathy in T2DM patients by using sympathetic reactivity to cold stress.