• Bulletin of the Korean Chemical Society
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• 제28권6호
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• pp.995-998
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• 2007

Pentacene moiety has been widely studied in Organic Thin-Film Transistor (OTFT) device as a channel layer because of high carrier mobility. In this study, we have fabricated vertical type Organic Static Induction Transistors (SITs) using pentacene, 6,13-Dinaphthalen-1-ly-Pentacene (1-DNP, 3), and 6,13-Dinaphthalen-2- ly-Pentacene (2-DNP, 4). 1-DNP and 2-DNP have same naphtyl group with pentacene, but different linked position and spatial arrangement. We have checked the static characteristics of materials in vertical type SITs device. We found that pentacene has as on/off ratio of 14.56, 1-DNP and 2-DNP shows as on/off ratio of 36.58 and 6.61 at VDS = 2V in SIT, respectively.

• 한국분무공학회지
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• 제25권3호
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• pp.103-110
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• 2020

In this study, the behavior of water droplet impacting on a thin horizontal wire was visualized by time-delay photography. The impact behavior modes, critical capture speed and trapped mass were analyzed by changing the droplet size, velocity, wire diameter and eccentricity ratio. As the Weber number increased, the hanging, merging, and splitting modes appeared sequentially for the case of central impact, and the hanging and non-splitting modes appeared for the case of off-center impact. The boundary We number of each mode was affected by the diameter ratio. The critical capture speed was affected much by the degree of eccentricity. For all diameter ratios, it was higher for the case of central impact than for off-center impact. The trapped mass was larger for the case of central impact than for off-center impact and it increased with the smaller We number and the larger diameter ratio.

• EDISON SW 활용 경진대회 논문집
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• 제6회(2017년)
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• pp.499-505
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• 2017

Photoisomerizing molecules which can transform their structure by the light irradiation have great deal for the application of photo-switching devices. And azobenzene is the representive type of the photoisomerizing molecules. It can transform their trans- structures into cis- structure as the light for certain wave lengths they receive. This property shows the potential of ON/OFF switching functionalization which can be used into the nano scale photo switch. Furthermore, many studies are interested in the organic linkers that connect the azobenzene and metal electrodes. We used S, $CH_2S$, $(CH_2)_4S$ as the linker to watch the influence of linkers for electronic properties. So We suggest a photoswitching device based on the vertical junction using the first-principles calculations with density functional theory and non-equilibrium Greens function (NEGF). By analyzing the electronic structure and tunneling current caused by the structural difference of the system between cis- and trans- azobenzene, the difference in switching mechanism, ON/OFF ratio and transmission will be watched as the linker changes. And finally We will suggest which linker would be the better for the optimal device architecture which can achieve high control of the ON/OFF photocurrent ratio. This result will show the potential of azobenzene-based photoswitch and provide the critical insight in constructing the optimal device architecture.

• Journal of Mechanical Science and Technology
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• 제14권6호
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• pp.645-654
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• 2000

In this paper, low level control algorithms of a metal belt CVT are suggested. A feedforward PID control algorithm is adopted for line pressure based on a steady state relationship between the input duty and the line pressure. Experimental results show that feedforward PID control of the line pressure guarantees a fast response while reducing the pressure undershoot which may result in belt slip. For ratio control, a fuzzy logic is suggested by considering the CVT shift dynamics and on-off characteristics of the ratio control valve. It is found from experimental results that a desired speed ratio can be achieved at steady state in spite of the fluctuating primary pressure. It is expected that the low level control algorithms for the line pressure and speed ratio suggested in this study can be implemented in a prototype CVT.

• 한국잠사곤충학회지
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• 제13권2호
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• pp.151-154
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• 1971

In the silkworm egg production, cutting of the cocoon's edge formed by silkworms forced to aid the emergence, and emergence is related to the amount of alkaloid liquid in the sucking stomach in certain varieties. In this study, there was no difference between cutting of portion and sex, and no significant between cutting of both sides and one side cocoons when comparing their emergence ratio. Expenditures and emergence ratio between both sides and one side cutting off must be studied in coming future.

• 한국방사선학회논문지
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• 제12권5호
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• pp.677-682
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• 2018

본 연구는 유방 전단파 탄성 초음파에서 탄성도 점수와 변형비를 이용한 방법이 양성과 악성병변의 감별진단에 유용한지를 평가하였다. 탄성 초음파를 시행한 224명을 대상으로 하였으며, 유방조직검사 결과를 바탕으로 후향적인 분석을 하였다. 유방 종괴의 양성과 악성에 따른 5단계의 탄성도 점수와의 동질성 비교는 Fisher's Exact test, 변형비와의 차이검증은 Mann-Whitney U test를 실시하였다. ROC 곡선분석을 통해 악성병변의 예측을 위한 탄성도 점수와 변형비의 최적 cut off 값을 결정하였다. 양성과 악성 결절 군의 분류에 따른 탄성도 점수의 동질성 비교와 변형비의 차이검증 결과에서 각각 통계적으로 유의한 차이를 보였으며(p=.000), ROC 곡선분석에서 양성과 악성 결절의 예측을 위한 탄성도 점수와 변형비의 AUC 0.824, 0.806, cut off 값 3, 4.4로 결정되었다(p=.001). 따라서 탄성도 점수와 변형비는 유방 종괴의 감별진단에 도움을 줄 수 있을 것이다.

• Journal of Biosystems Engineering
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• 제19권4호
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• pp.318-328
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• 1994

This study was carried out to find out the possibility of continuity of the Farming Service Company (FSC), which has been founding since 1991 by the public administration to obtain the scale economy in the rice production, through the only financial analysis of the FSC. The results obtained were as follows. 1. The FSC's business is forward to the off-farm business rather than farm business. Based on the profit ratio, the profit ratio of off-farm business is more than that of farm business. It may cause the difficulty of policy to obtain the scale economy in the farming through the FSC. 2. Without subsidies the average net profit of the FSC was negative, which may provide the motives to the FSC to seek out the way to survive through the off-farm business, unless the FSC's could break up. 3. After all, the possibility of continuity of the FSC through the only financial analysis seems to be very little. Therefore the public administration should reconsider the present policy which is to found the more FSC continuously. If government wants to support the FSC continuously, government should focus on the conglomeration of farm land to increase the productivity of farming and on the subsidy of off-farm business to increase the profit ratio of the FSC.

• The Journal of Asian Finance, Economics and Business
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• 제8권1호
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• pp.45-52
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• 2021

The capital structure is one of the hot financial topics among researchers and scholars. Its importance comes from the fact that capital structure is closely related to companies' ability to meet different stakeholders' needs. A suitable capital structure will boost the business and create a competitive advantage in the context of fierce competition. Many companies choose an optimal debt level based on the trade-off between interest and debt costs. This study aimed to test the existence of trade-off theory in capital structure, the case of Vietnam's real estate companies, which are growing very fast recently. Instead of considering constant optimal leverage to test the trade-off model, we take advantage of the dynamic capital structure determined by growth opportunities, profitability, tax incentives, tangibility, liquidity, and firm size. The dynamic panel data regression was estimated by the system Generalized Method of Moment (Sys-GMM). The empirical evidence showed that real estate companies listed in the Vietnamese stock market might change their leverage toward a target capital structure determined by influential factors in a long-term perspective. In particular, the debt-to-asset ratio will change by approximately 14 percent, positively, in response to the difference between the current debt-to-asset ratio and the dynamic target debt-to-asset ratio.

• 한국전기전자재료학회논문지
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• 제22권2호
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• pp.107-113
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• 2009

In order to improve air stability, we proposed a new active layer of an organic TFT by synthesizing P3HT/POSS conjugated polymer. P3HT/POSS OTFTs with the various P3HT/POSS volume ratios were fabricated and characterized. With the P3HT/POSS volume ratio of 1:1, we achieved the field-effect mobilities of ${\sim}1.19{\times}10^{-3}\;cm^2/v{\cdot}sec$ in the saturation region and the current on/off ratio of ${\sim}2.51{\times}10^2$. The resulting current on-off ratio was much higher than that of the P3HT-based OTFTs and resulted from the dramatic decrease of the off-current. Since the off-current can be reduced by preventing oxygen in atmosphere from doping the P3HT/POSS active layers, this new active layer shows its ability to avoid oxygen doping in atmosphere. Therefore, the improvement of the air stability can be achieved by employing the P3HT/POSS active layers.

• 동력기계공학회지
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• 제17권1호
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• pp.58-63
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• 2013

The aerodynamic performance of double inlet sirocco fan is strongly dependent upon the design factors of impeller and scroll. In this paper, the change of scroll size was adopted to investigate the aerodynamic performances of double inlet sirocco fan and indoor PAC. Especially, a scroll expansion angle and a cut-off clearance ratio were considered to change the scroll size. In addition, the installation depth between double inlet sirocco fan and indoor PAC was considered. As a result, the total pressure efficiency of double inlet sirocco fan shows about 62%~73% according to the change of scroll expansion angles. Moreover, the flowrate performance of indoor PAC is the best at the condition of a scroll expansion angle of 8°, an installation depth of 15 mm and a cut-off clearance ratio of 8%.