• Composites Research
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• v.29 no.4
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• pp.145-150
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• 2016

Polyvinylidene fluoride (PVDF) as a representative polymer with the piezoelectric property has been studied since the 1960s. Crystalline structure of poly(vinylidene fluoride) polymer is composed of five different crystal structure of the polymer as a semi-crystalline. Among the various crystal structures, ${\beta}-type$ crystal exhibits a piezoelectricity because the permanent dipoles are aligned in one direction. Generally ${\beta}-form$ crystal structure can be obtained through the transformation of the ${\alpha}-form$ crystal structure by the stretching and it can increase the amount through the after treatment as poling process after stretching. ${\beta}-form$ crystal structure the PVDF fibers produced by wet spinning is formed through a diffusion mechanism of a polar solvent in the coagulation bath. However, it has a disadvantage that the diffusion path of the solvent remains as pores in the fiber because the fiber solidification occurs simultaneously with the diffusion of the polar solvent. These pores play a role in reducing effect of poling process owing to effect of disturbances acting on the polarization by the electric field. In this work, the drying method using the microwave was introduced to remove more effectively the residual solvent and the pore within PVDF fibers produced through wet-spinning process and piezoelectric PVDF fibers was produced by transformation of the remaining ${\alpha}$ form crystal structure into ${\beta}-crystal$ structure through the stretching process.

• Journal of Life Science
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• v.17 no.1 s.81
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• pp.18-23
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• 2007

Fe65, a neuron-specific adaptor protein, has two phosphotyrosine binding (PTB) domains. The second PTB (PTB2) domain interacts with intracellular domain fragment (AICD) of amyloid beta precursor protein (APP). Recent studies suggested that tile complex is composed of AICD and Fe65 transactivates genes that are responsible for neuronal cell death in Alzheimer's disease (AD). Therefore, a compound inhibiting the interaction between Fe65 and AICD can be a drug candidate to treat AD. However, it remains unclear how Fe65 recognizes AICD at a molecular level. Here, we report high-level production of the PTB2 domain of Fe65 in the baculovirus system. We found that the baculovirus system is an efficient method to obtain the Fe65 PTB2 domain, compared with the bacterial and mammalian expression systems. The purified recombinant protein was used for crystallization to determine its crystal structure helping to understand the molecular mechanism of Fe65-dependent signaling and to design its inhibitors.

• Geotechnical Engineering
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• v.4 no.4
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• pp.39-50
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• 1988

Until now, most probabilistic approaches to the slope stability analysis have been accomplished on the arc failure surface without load. In this study, the relationships between the probability of failure and the safety factor are investigated when the shape of failure is logarithmic spiral on the homogeneous slope with ground water level, the probability distributions of the load and the strength parameter of soil being assumed as normal distribution, log-normal distribution and beta distribution. The results obtained are as follows; 1. For the same safety factor, the design of slope is more reasonable by using the probability of failure than by the safety factor because the probability of failure is increased as the coefficient of variation is increased. 2, The safety factor is more reasonably determined by the coefficient of variation of the strength parameter than by the field condition when the safety factor is applied to design of slope.

• The Korean Journal of Financial Management
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• v.27 no.1
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• pp.209-237
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• 2010

This paper examines the relationship between information risk and equity premium in the Korean stock market. We use accruals quality as a proxy of information risk. Accruals quality (AQ) is estimated by Dechow and Dichev (2002) model, and then AQfactor is constructed based on the estimated AQ. Time-series and cross-sectional regression models are used to examine the relationship between information risk and equity premium, reflecting the critics of Core et al. (2008). The result of the paper shows that information risk proxied by accruals quality is not priced in equity premium in the Korean stock market. This result is consistent with Core et al. (2008) for US firms, but different with Francis et al. (2005) for US firms and Gray et al. (2008) for Australia firms. Also, the result shows that AQfactor is closely correlated with firm characteristic variables such as firm size. This implies that the effect of AQ on equity premium is more likely to arise from the pricing error due to firm characteristics rather than from an unknown risk factor.

• The Korean Journal of Financial Studies
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• v.6 no.1
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• pp.223-247
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• 2000

본 연구에서는 유로커런시와 외환시장의 초과수익률을 설명하는 여러 가지 모형을 검증하였다. 비록 Campbell-Clarida(1987)와 Lewis(1990,1991)는 이 시장에서 3개월물의 초과수익률에 대한 단일잠재변수모형을 기각할 수 없었지만 본 연구에서는 이 모형이 여러 포트폴리오에 대하여 기각되고 있음을 보여준다. 그러나 이 모형의 검증은 결합가정을 필요로 하기 때문에 모형의 기각원인을 찾는다는 것은 어려운 일이다. 기각의 가능성으로 세계 경제에 하나 이상의 위험요인이 존재할 수 있다는 것이 될 수도 있고 불안정한 상수가 원인일 수가 있다. 상수의 안정성검증에서 1979년 12월을 전후한 기간에 상수가 변하지 않는다는 귀무가설이 모든 포트폴리오에서 기각되었다. 따라서 양기간에 단일잠재변수모형과 두잠재변수모형을 검증하였다. 모든 포트폴리오에 대하여 1979년 12월 이전에는 단일변수모형이 기각되지 않았지만, 1979년 이후에는 체계적으로 기각되었다. 한편 두잠재변수모형은 양기간 모두에서 기각되지 않았다 따라서 위험요인에 변화를 주는 연방준비은행의 운영절차의 변화가 단일변수모형의 기각의 원인일 수 있다고 유추할 수 있다. 마지막으로 시간 가변적인 베타가 단일변수모형의 기각의 원인이 될 수 있는지를 검증하기 위하여 Harvey(1989,1991)에 의해서 개발된 모형을 적용해 보았지만 모형이 기각되었다. 따라서 유로커런시와 외화자산의 3개월물의 초과수익률에 두 잠재변수모형이 자료를 비교적 잘 설명한다고 볼 수 있다. 그러나 잠재변수모형의 검증은 자산가격결정의 일반균형이론의 검증도 아니고 검증력도 강하지 않기 때문에, 위험프리미엄을 설명해주는 단순한 실증분석으로 보아야 한다.

• Proceedings of the Korean Society of Postharvest Science and Technology of Agricultural Products Conference
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• 2003.04a
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• pp.107-107
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• 2003

고품질 쌀 생산을 위하여 우리나라의 농가 및 미곡종합처리장의 벼 수확후 품질관리 현황 실태를 조사하여 일본, 미국, 중국 둥의 현황과 비교하였다. 중국의 경우 벼 수확은 대부분 인력에 의존하고 있으며, 일본은 산물형 콤바인 그리고 미국은 대형산물 콤바인에 의한 적기수확을 하고 있다. 우리나라의 경우에는 콤바인이 부족하고 벼 수확시기는 콤바인 운영자의 일정에 따라 결정되고 있으며 습논, 소면적 재배 논은 수확이 늦어져 적기 수확이 못되고 있는 실정이다. 한편 일본은 라이스센터, 컨트리엘레베타, 드라이스토아 등의 지원으로 적기 수확이 가능하고 건조기 건조율도 90%이상 2단계 상온 통풍체계로 수분함량 14.5~15.5%를 유지하고 있다. 우리나라를 제외한 일본, 중국, 미국의 저장시설은 대부분 대형저장 사이로에서 품종별, 산지별, 등급별로 구분한 저온저장 시스템을 갖추어 품질을 유지하고 있었다. 또한 도정시설도 고품질 도정시설을 완비하고 있으며 제현이나 정미과정에 색채선별기, 금속검출기, 활성화 장치 및 입형분리기 등을 통하여 불완전미가 제거하는 등 수확후 관리에 철저를 기하고 있다. 쌀의 등급화 및 유통과정를 보면 일본, 중국, 미국 등은 대부분이 품종, 산지 및 등급별로 브랜드화 하여 차별화 된 가격으로 판매되고 있으며 포장지에 쌀에 대한 정보를 최대한 표시하여 소비자가 선택하는데 도움이 되게 하여 유통되고 있다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.24 no.4
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• pp.164-168
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• 2014

The sodium-sulfur batteries which operate at $350^{\circ}C$ have been mainly used in the field of energy storage system. This batteries consist of liquid sodium anode, sulfur cathode and ${\beta}^{{\prime}{\prime}}$-alumina solid electrolyte. The conditioning process for stabilization of the batteries is essential since the cells show considerable fluctuation of discharge voltage at the beginning of discharge/charge cycles. It is found that one of the reasons of the fluctuation is the gradual change of contact area between molten sodium and solid electrolyte.

• Journal of Industrial Convergence
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• v.20 no.2
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• pp.11-19
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• 2022

This study examines the role of economic uncertainty in stock price determination in the domestic stock market. To this end, we analyzed the relationship between economic uncertainty indices at home and abroad (USA, China) and stock returns for non-financial companies in Korea from January 2000 to 2017. For the analysis model, the 3-factor model of Fama and French (1992) and the 5-factor model including momentum and liquidity were used. As a result of the analysis, a portfolio with a high beta of economic uncertainty showed higher stock returns than a portfolio with a low beta. This was the same as the US analysis result. Also, the analysis results using the US uncertainty index were more significant than the regression analysis results using the Korean economic uncertainty index.

• Korean Journal of Food Science and Technology
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• v.48 no.3
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• pp.256-261
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• 2016

This study investigated the changes in functional components of barley powder produced from different grain varieties (Dahan, Hinchalssalbori, Heukgwang, Huknuri and Boseokchal) and varying milling degrees (27, 23, 19, and 15%). Total polyphenol contents increased with a decrease in the milling degree, with content ranges of 0.97-1.40, 1.19-1.66, 1.22-1.77, 1.30-1.93, and 1.46-2.12 mg/g, respectively. Total flavonoids content also increased with a decrease in the milling degree. The total polyphenol and flavonoids contents were the highest in barley powder from Huknuri and Boseokchal grains. Total dietary fiber, arabinoxylan, and GABA contents increased with a decrease in the milling degree. As the milling degrees decreased, ${\beta}$-glucan contents, which was the highest in Hinchalssalbori and Boseokchal, decreased with ranges of 4.98-7.29, 5.26-7.03, 4.84-7.17, 4.84-700, and 4.66-6.33 mg/100 g, respectively. These results provide useful data for selection of an appropriate variety and milling degree to achieve a high quality in barley processing.

• The Journal of the Korea Contents Association
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• v.12 no.11
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• pp.338-357
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• 2012

This study investigated any possible financial attributes of the CDS spreads of a firm belonging to financial industries headquartered in the Republic of Korea. There were few studies on this issue, especially for the firms located in emerging capital markets. Coupled with the models such as a multiple regression and a principal component analysis(PCA), this research has identified that only two explanatory variables such as SLOPE and INTER3 (i.e. interaction effect between the BETA and the SLOPE) consistently showed their statistically significant influence on the CDS spreads through the 'selected' model without and with applying a stepwise regression procedure for the robustness. Given the rapid developments of sophisticated financial derivatives, this study may suggest a valuable insight to foreign and domestic investors to identify the possible determinants of CDS spreads at the firm- and/or the industry-level.