• 기술경영경제학회:학술대회논문집
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• 기술경영경제학회 2004년도 제24회 동계학술대회 논문집
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• pp.83-107
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• 2004

This study investigates how and through which channels R&D activities influences the national economy, using a macro-econometric model. The macro-econometric model in this study includes 24 behavioral equations and 25 identities and was estimated using the annual data. From a simulation analysis, it is shown that the R&D investment has a permanent effect on real variables; lowering prices, wages and interest rates, and increasing potential and real GDP in the long run. It is noted that the national account was recalculated to avoid double-counting in estimation of R&D stocks.

• Biotechnology and Bioprocess Engineering:BBE
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• 제9권3호
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• pp.201-206
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• 2004

Vascular endothelial growth factor (VEGF), plays a key role in angiogenesis. Many endogenous factors can affect angiogenesis in endothelial cells. VEGF is known to be a strong migration, sprouting, survival, and proliferation factor for endothelial cells during angiogenesis in endothelial cells. Searching for novel genes involved in VEGF signaling during angiogenesis, we carried out differential display polymerase chain reaction on RNA from VEGF-stimulated human umbilical vein endothelial cells (HUVECs). In this study, follistatin (FS) differentially expressed in VEGF-treated HUVECs, compared with controls. Addition of VEGF (10ng/L) produced an approximately 11.8-fold increase of FS mRNA. F5 or VEGF produced approximately 1.8- or 2.9-fold increases, respectively, in matrix metalloproteinase-2 (MMP-2) secretion for 12h, compared to the addition of a control buffer. We suggest that VEGF may affect the angiogenic effect of HUVECs, through a combination of the direct effects of VEGF itself, and the indirect effects mediated via induction of FS in vitro.

• KDI Journal of Economic Policy
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• 제41권3호
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• pp.77-96
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• 2019

This paper examines the relation between the skill premium and international trade given differences in the relative supply of skills across countries while allowing the South (developing countries) to develop its appropriate technology. Typical assumptions put forward in the literature state that either technology is exogenously given, or technical change is allowed only in the North (developed countries). I present a model of international trade with endogenous growth by allowing the South to direct its technology. The results show that more R&D is directed towards skill-augmenting technology in the North than in the South, in sectors with the same skill-intensity. Technical change induced by lowering trade costs can increase the skill premium in both the North and the South. This result can explain the empirical observation that the skill premium has increased within many developing countries after they experienced trade liberalization. Finally, the model predicts larger gains from trade compared with the model where technical change is either not allowed, or allowed only in the North.

• Journal of Plant Biology
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• 제35권4호
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• pp.403-408
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• 1992

장일식물인 Lemna gibba G3의 개화유도과정에 있어서 polyamine의 관련성을 조사하였다. 이 식물의 개화는 연속광하에서 agmatine, putrescine, spermidine 및 spermine에 의해 촉진되었으며 이들의 체내 합성억제물질인 methylglyoxal-bis(guanylhydrazone)(MGBG)과 cyclohexylamine(CHA)에 의해서 억제되었다. Polyamine은 영양생장률을 거의 일정한 수준으로 유지하면서 개화를 촉진시켰으며, 억제물질에 의한 개화억제는 오히려 영양생장률의 증가를 수반하였다. 이러한 현상은 이 물질들의 개화촉진 또는 억제효과가 생장률의 일반적인 촉진 또는 억제효과에 의한 것이 아니라 선택적으로 개화과정에 작용한 결과일 것이라는 추측을 뒷받침해 준다. 배양액의 첨가된 spermidine 또는 spermine의 개화촉진 폭은 배양액에 이들의 억제물질의 함유여부와 관계없이 거의 일정한 수준으로 나타났다. 이렇듯, 외부에서 공급된 후 체내에 흡수된 spermidine과 spermine의 개화에 대한 기여도가 한정되어 있는 것으로 보아 L. gibba G3의 개화유도과정이 식물체내에서 합성되는 spermidine과 spermine에 크게 의존하고 있을 것으로 판단된다. 한편, 개화유도과정이 시작되어 점차적으로 증가한 체내의 spermidine 함량은 개화가 유도되지 않은 경우에 비하여 24시간만에 약 2배의 수준에 도달하였다. 이렇듯 체내의 spermidine량이 급격히 증가된 사실은 체내의 polyamine의 질적 및 양적 변화가 L. gibba G3의 개화유도초기과정에서 매우 중요한 역할을 하고 있을 것이라는 가정을 뒷받침하는 또 하나의 예비적 증거라 할 수 있다.

• 원예과학기술지
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• 제31권6호
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• pp.714-719
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• 2013

꽃목굽음 현상(bent peduncle phenomenon, BPP)은 절화장미의 생산성 저하를 유발하는 생리적 장해의 하나로 알려져 있으나, 관련 기작이 명확히 구명되어 있지 않아 아직까지 대책 마련이 곤란한 실정이다. 이를 해결하고자 국내육성 장미 품종인 'Beast'(Rosa hybrida L. 'Beast')를 대상으로 꽃목굽음지의 화기형태, 생장, 내생 호르몬 변화 특성을 분석하였다. 화기형태 관찰을 통해 꽃목굽음지는 5개의 꽃받침조각 중 하나가 조기에 형성되고 엽상화되면서 대화현상을 나타냈다. 연중 BPP 발생 빈도는 계절에 따라 5-20%로 여름철 고온기에 급증하였다. 꽃목굽음지는 정상지와 비교하여 꽃목굽음 증상 외 생장량과 속도면에서 차이를 보이지 않았으나, 꽃으로의 동화산물 분배는 현저하게 감소되었다. 정상지와는 달리 꽃목굽음지에서의 내생 호르몬 IAA 함량은 화아발육기간 내내 높게 유지되었으나, $GA_3$ 함량은 차이를 보이지 않았다. 본 연구에서 BPP는 고온과 관련된 특정 꽃받침조각의 엽상화, 대화현상을 나타내면서 꽃으로의 동화산물 불균형 분배, 높은 IAA에 의해 유발되는 것으로 보인다.

• Asian Pacific Journal of Cancer Prevention
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• 제13권8호
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• pp.3675-3680
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• 2012

Objective: To investigate the expression of endogenous hypoxia-related markers identified as being involved in vulvar squamous cell carcinoma (VSCC). Methods: We performed immunohistochemical staining of hypoxia-inducible factor-$1{\alpha}$ (HIF-$1{\alpha}$), glucose transporter-1 (GLUT-1), carbonic anhydrase 9 (CA-9) and vascular endothelial growth factor (VEGF), on tissue sections of 25 VSCC patients, 10 vulvar intraepithelial neoplasia (VIN) patients and 12 healthy controls. Results: HIF-$1{\alpha}$ expression was found in all sections, with no significant difference between controls, VIN and VSCC sections (all P<0.05). Glut-1 expression was found in 25% of control, 90% of VIN and 100% of VSCC sections. A significant difference between control and VIN or VSCC was observed (all P<0.05), while no difference was found between VIN and VSCC sections (P>0.05). CA-9 expression was negative in control sections, but it was found in 30% of VIN sections and 52% of VSCC sections with strong staining. Similarly, CA-9 expression also showed obvious differences between controls and VIN or VSCC sections (all P<0.05). However, there was no significant difference between VIN and VSCC (P>0.05). There were only 25% of control sections with weak VEGF expression, while strong staining was found in about 60% of VIN sections and 25% of VSCC sections (all P<0.05). In addition, a difference was also found between VIN and VSCC sections (P<0.05). Conclusion: Expression of endogenous hypoxia markers (HIF-$1{\alpha}$, GLUT-1, CA-9 and VEGF) might be involved in the malignant progression of VSCC.

• 대한간호학회지
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• 제50권1호
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• pp.26-38
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• 2020

Purpose: The purpose of this study was to explain a structural model of posttraumatic growth among psychiatric nurses based on existing models and a literature review and verify its effectiveness. Methods: Data were collected from psychiatric nurses in one special city, four metropolitan cities, and three regional cities from February to March 2016. Exogenous variables included hardiness and distress perception, while endogenous variables included self-disclosure, social support, deliberate rumination, and posttraumatic growth. Data from 489 psychiatric nurses were analyzed using IBM SPSS Statistics 19.0 and AMOS 20.0. Results: The modified model was a good fit for the data. Tests on significance of the pathways of the modified model showed that nine of the 14 paths were supported, and the explanatory power of posttraumatic growth by included variables in the model was 69.2%. For posttraumatic growth among psychiatric nurses, deliberate rumination had a direct effect as the variable that had the largest influence. Indirect effects were found in the order of hardiness, social support, and distress perception. Self-disclosure showed both direct and indirect effects. Conclusion: A strategy to improve deliberate rumination is necessary when seeking to improve posttraumatic growth among psychiatric nurses. Enhancing psychiatric nurses' hardiness before trauma would enable them to actively express negative emotions after trauma, allowing them to receive more social support. This would improve deliberate rumination and consequently help promote psychological growth among psychiatric nurses who have experienced trauma.

• BMB Reports
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• 제36권1호
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• pp.128-137
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• 2003

Matrix metalloproteinases (MMPs), zinc dependent proteolytic enzymes, cleave extracellular matrix (ECM: collagen, laminin, firbronectin, etc) as well as non-matrix substrates (growth factors, cell surface receptors, etc). The deregulation of MMPs is involved in many diseases, such as tumor metastasis, rheumatoid arthritis, and periodontal disease. Metastasis is the major cause of death among cancer patients. In this review, we will focus on the roles of MMPs in tumor metastasis. The process of metastasis involves a cascade of linked, sequential steps that involve multiple host-tumor interactions. Specifically, MMPs are involved in many steps of tumor metastasis. These include tumor invasion, migration, host immune escape, extravasation, angiogenesis, and tumor growth. Therefore, without MMPs, the tumor cell cannot perform successful metastasis. The activities of MMPs are tightly regulated at the gene transcription levels, zymogen activation by proteolysis, and inhibition of active forms by endogenous inhibitors, tissue inhibitor of metalloproteinase (TIMP), and RECK. The detailed regulations of MMPs are described in this review.

• The Korean Journal of Physiology and Pharmacology
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• 제3권6호
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• pp.597-603
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• 1999

Caldesmon (CaD), one of microfilament-associated proteins, plays a key role in microfilament assembly in mitosis. We have investigated the effects of overexpression of the high molecular weight isoform of CaD (h-CaD) on the physiology of vascular smooth muscle cells (VSMCs). Rat aortic VSMCs were stably transfected with plasmids carrying a full length human h-CaD cDNA under control of cytomegalovirus promoter. The majority of the overexpressed h-CaD appears to be localized predominantly on cytoskeleton structures as determined by detergent lysis. The overexpression of h-CaD, however, does not decrease the level of endogenous low molecular weight isoform of CaD. h-CaD overexpressing VSMCs (h-CaD/VSMCs) show a decreased growth rate than that of vector-only transfected cells when determined by $[^3H]thymidine$ uptake and cell counting after fetal bovine serum (FBS) stimulation. h-CaD/VSMCs were smaller than vector-transfected cells by 18% in cell diameter. These data suggest that overexpression of h-CaD can inhibit the poliferation and the cell volume of VSMCs stimulated by growth factors and that the gene therapy with h-CaD may be helpful to prevent the conditions associated with hypertrophy and/or hyperplasia of VSMCs after arterial injuries.

• 한국양식학회지
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• 제11권3호
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• pp.345-352
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• 1998

조피볼락 Sebastes schlegeli 자어와 점농어 Lateolabrax sp. 자어를 대상으로 기아시 성장과 간세포 핵 크기 변화를 조사하였다. 전장과 습중량 성장에 있어 조피볼락과 점농어의 간세포 핵 크기는 첫 먹이 섭취 자어의 영양상태와 연관성을 보였다. 본 연구의 조피볼락과 점농어 자어에서의 기아시 간세포 핵 크기 조사 결과는 조피볼락과 점농어에서 초기 영양상태 판명의 지표가 될 수 있으며 초기 먹이 공급 공정시 내생적 영양상태에서 외생적 영양상태로의 효율적 전환을 가능케 할 것으로 사료된다.