• ETRI Journal
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• 제27권3호
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• pp.319-325
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• 2005

In this paper the effect of temperature on the electrical properties of organic semiconductor disperse orange dye 25 (OD) have been examined. Thin films of OD have been deposited on $In_{2}O_{3}$ substrates using a centrifugal machine. DC current-voltage (I-V) characteristics of the fabricated devices $(Al/OD/In_{2}O_{3)$ have been evaluated at varying temperatures ranging from 40 to $60^{\circ}C$. A rectification behavior in these devices has been observed such that the rectifying ratio increases as a function of temperature. I-V characteristics observed in $Al/OD/In_{2}O_{3)$ devices have been classified as low temperature $({\leq} 50^{\circ}C)$ and high temperature characteristics (approximately $60^{\circ}C$). Low temperature characteristics have been explained on the basis of the charge transport mechanism associated with free carriers available in OD, whereas high temperature characteristics have been explained on the basis of the trapped space-charge-limited current. Different electrical parameters such as traps factor, free carrier density, trapped carrier density, trap density of states, and effective mobility have been determined from the observed temperature dependent I-V characteristics. It has been shown that the traps factor, effective mobility, and free carrier density increase with increasing values of temperature, whilst no significant change has been observed in the trap density of states.

• 한국환경과학회지
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• 제7권4호
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• pp.501-504
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• 1998

Vibrlo vulnificus가 병원성을 일으키는 한가지 요인으로서 iron의 역할을 본 연구에서 알아보고 V. vulnificus의 성장에 미치는 사람과 토끼 혈청에서의 iron과 $CCl_4$의 영향도 조사하였다. 쥐에 iron을 주사한 결과 50% 치사량이 감소하였고 감염 후 치사 시간도 감소하였으며 $CCl_4$,로 감염된 간에 의해서 혈청 중 iron준위는 증가하였다. 쥐를 치사시키는데 필요한 접종량은 혈청 중 iron준위와 직접적으로 상호 관련성이 있었다. Iron은 이 미생물이 포유류 혈청에서 살아남거나 성장하는 능력에 있어서 제한 요인으로 나타났다. 시험관 내에서와 생체 내에서 이들 결과는 iron이 V. vulnificus의 병원성에 있어서 중요한 역할을 한다는 강한 증거를 제공해주었다.

• Wind and Structures
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• 제28권6호
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• pp.381-388
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• 2019

This paper described the application of Geospatial Analysis in determining mean wind speed, $V_h$ for wind load calculation imposed to electrical transmission tower structural design. The basic wind speed data on available station obtained from Malaysian Meteorology Department is adjusted by considering terrain and ground roughness factor. The correlation between basic wind speed, terrain factor and ground roughness stated in EN-50341-1 is used to obtain the $V_h$ for overhead transmission line elements 50 m above ground. Terrain factor, $k_r$ and ground roughness, $z_0$ in this study are presented by land use types of study area. Wind load is then calculated by using equation stated in design code EN-50341-1 by using the adjusted mean wind speed. Scatter plots of $V_h$ for different $k_r$and $z_0$ are presented in this paper to see the effect of these parameters to the value of $V_h$. Geospatial analysis is used to represent the model of $V_h$. This model can be used to determine possible area that will subject to wind load which severe to the stability of transmission tower and transmission line.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2007년도 춘계학술대회 논문집
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• pp.533-534
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• 2007

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.253-257
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• 2003

This paper presents the Development of Switching Power Supply for testing communication equipment. The communication equipment need many kinds of voltage(-48V,27V,12V,5V,3.3V), and in case of low voltage needs large current($10{\sim}20A$). The previous Linear Power Supply was very heavy, has low efficiency and poor power-factor for testing communication equipment. This development has good efficiency and high power-factor using switch mode power supply technique. This Development of Switching Power Supply is composed of eight converters. The principles of operation, feature, and design considerations are illustrated and verified through the experiment with 600W prototype.

• 한국환경과학회지
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• 제5권2호
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• pp.179-185
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• 1996

본 연구는 생명을 위협하는 Vibrio vulnificus의 생존에 온도, 염분 pH 및 자외선과 같은 환경적 요인이 어떠한 영향을 미치는 가를 알아보기 위하여 수행하였다. 6일 동안 15에서 ${25\circ}C$의 온도범위에서 V.vulnificus의 수는 증가하였지만 이 범위외에서 V.vulnifivus의 생존수는 감소하였다. 1에서 ${10\circ}C$사이에서의 실험 결과, V.vulnificus 가 $10{\circ}C$이하에서는 생존수가 적었다. 한편 6일 동안 5에서 25ppt정도의 염분조건에서는 V.vulnificus수는 감소하였다. 최적의 pH 영역은 6.5에서 8.0이었고 이 영역밖에서는 V.vulnificus의 생존율은 낮았다. 15와 $25{\circ}C$에서 자외선은 V.vulificus에 대해 살균효과를 나타내어서 2시간 동안 자외선 처리후 V.vulnificus수가 약 10,00배 감소되었다. 이상과 같은 결과들은 환경적 요인이 V.vulnificus의 생존에 미치는 영향이 크다는 것을 보여주었다.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제30권1호
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• pp.41-51
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• 2008

Mucoepidermoid carcinoma (MEC) is the most common malignant salivary gland tumor which compromises about 6$\sim$8% of all tumors followed by the adenoid cystic carcinoma (ACC) and adenocarcinoma. Most deaths from salivary carcinomas are caused by recurrent or metastatic lesions that are resistant to conventional therapy. Therefore, knowledge of cellular properties and tumor-host interactions that influence the vascular metastasis is important for the design of more effective therapy of salivary carcinomas. Neoangiogenesis is essential for tumor growth, which is postulated to be fundamentally dependent on the induction of stromal neovascularization. However, how neovascularization takes place in live tissue has not been fully established, especially in recruitment and differentiation of endothelial cells in the salivary gland tumors. Vascular endothelial growth factor (VEGF) is a heparin-binding, dimeric polypeptide growth factor known to exert its mitogenic activity specifically on endothelial cells. VEGF has been shown th be directly involved in angiogenesis, which in essential for the pathogenesis of many solid tumors. von Willebrand factor (vWF) is a large multimeric protein synthesized by megakaryocytes and endothelial cells that enable platelets to adhere to exposed subendothelium and, as well, to respond to changes in the blood flow. Recent studies suggest that increased levels of vWF correlate with progression of disease, metastasis, or survival time and thus may have a prognostic significance. vWF is explained as an acute phase proteins which is increased in cancer or as a result of increased endothelial cell synthesis associated with tumor-induced angiogenesis. Due to adhesive properties of vWF, its increased concentrations may also contribute metastasis of tumor. In this study, we determined the mRNA expression of VEGF and vWF in salivary ACC, MEC and pleomorphic adenoma by in situ hybridization. As a result, stronger expression of VEGF and vWF was seen in salivary ACC and MEC which has more invasive nature than the salivary benign tumor.

• 한국가축번식학회지
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• 제21권2호
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• pp.177-183
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• 1997

The present study examined the effects of epidermal growth factor(EGF) and transforming growth factor-$\alpha$(TGF-$\alpha$) on in vitro maturation of porcine follicular oocytes. Basic medium used TCM-HEPES, and oocytes cultured for 42 hours in vitro. The results obtained are as follows; 1. The nuclear maturation rates of EGF-treated groups(10ng/ml, 75.9% ; 30ng/ml, 69.2% ; 50ng/ml, 67.2% ; 100ng/ml, 71.0%) on the porcine oocytes cultured in medium without pFF in vitro were significantly(P<0.01) higher than those of non-treated group(57.1%). When the oocytes were cultured in media with 10%(v/v) pFF, the nuclear maturation rates of 30ng EGF/ml(77.1%) treated group were significantly(P<0.01) higher than those of non-(59.2%) and EGF-treated groups(10ng/ml, 65.4% ; 50ng/ml, 65.5% ; 100ng/ml, 70.4%). 2. The nuclear maturation rates of 30ng TGF-$\alpha$/ml treated group(71.9%) in media without pFF in vitro were significatnly(P<0.01) higher than those of non-(57.1%) and TGF-$\alpha$ treated groups(10ng/ml, 60.4% ; 50ng/ml, 65.4% ; 100ng/ml, 60.0%). When the oocytes were cultured in media with 10%(v/v) pFF, the nuclear maturation rates of 30 and 50ng TGF-$\alpha$/ml(77.4% and 79.6%) treated groups(10ng/ml, 64.2% ; 100ng/ml, 61.6%). 3. On the effect of EGF(30ng/ml) and/or TGF-$\alpha$(30ng/ml) treated groups in medium without pFF in vitro, the nuclear maturation rates indicated 57.3, 60.4, 75.9 and 79.7% in media with no EGF & TFG-$\alpha$, TGF-$\alpha$ only, EGF only nad EGF＋TGF-$\alpha$ treated groups, respectively. The nuclear maturation rates in medium with EGF only or EGF＋TGF-$\alpha$ were significantly(P<0.01) higher than those non- and TGF-$\alpha$ treated groups. When the oocytes were cultured in media with 10%(v/v) pFF, the nuclear maturation ratesof EGF＋TGF-$\alpha$ treated group(75.9%) were significantly(P<0.01) higher than those of non-(59.2%), TGF-$\alpha$ only (64.2%) and EGF only(69.4%) treated groups.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2003년도 추계학술대회 논문집
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• pp.85-89
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• 2003

Many single-stage PFC(power-facto.-correction) ACHC converters suffer from the high link voltage at high input voltage and light load condition. In this paper, to suppress the link voltage, a novel high power factor high efficiency PFC AC/DC converter is proposed using the single controller which generates two gate signals so that one of them is used far gate signal of the flyback DC/DC converter switch and the other is applied to the Boost PFC stage. A 130w prototype for LCD monitor adapter with universal input $(90-265V_{rms})$ and 19.5V 6.7A output is implemented to verify the operational principles and performances. The experimental results show that the maximum link voltage stress is about 450V at 270Vac input voltage. Moreover, efficiency and power factor are over $84\%$ and 0.95, respectively, under the full load condition.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 춘계학술대회 논문집 초전도 자성체
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• pp.7-10
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• 2002

We designed the flyback planar transformer, which had 8W capacity, with 70V input voltage and 8.2V output voltage for the establishment of design method and the confirmation of application possibility. The numerical value of inductance measured under the switching frequency of 120 kHz was 1650 ${\mu}H$, which was the inductance efficiency of 85~87% against theoretical value. The A.C. resistance of primary and secondary coil was 4.2 ${\Omega}$ and 0.25 ${\Omega}$ respectively. On the other hand, the quality factor for each wound numbers showed quite a high value of 158 and 75 respectively. And the Coupling Factor was 0.96~0.97 under 120 kHz switching frequency. And the shape of the output wave of the planar transformer at 70V input voltage was a stable square wave.