• Bulletin of the Korean Chemical Society
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• 제30권7호
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• pp.1588-1592
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• 2009

Lithium cyanoaluminum hydride (LCAH) was prepared by the metal cation exchange reaction of sodium cyanoaluminum hydride with lithium chloride in tetrahydrofuran. The reducing characteristics of LCAH were explored systematically by the reaction with selected organic compounds containing representative functional groups under the standardized conditions (tetrahydrofuran, 0 ${^{\circ}C}$). The reducing ability of LCAH was also compared with of the sodium derivative, sodium cyanoaluminum hydride (SCAH). Generally, the reducing behavior of LCAH resembles that of SCAH closely, but the reactivity of LCAH toward representative organic functional groups appeared to be stronger than that of SCAH. Thus, the regent reduces carbonyl compounds, epoxides, amides, nitriles, disulfides, carboxylic acids and their acyl derivatives to the corresponding alcohols or amines, at a relatively faster rate than that of SCAH. The cyano substitution, a strong election-withdrawing group, diminishes the reducing power of the parent metal aluminum hydrides and hence effects the alteration of their reducing characteristics.

• Journal of international Conference on Electrical Machines and Systems
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• 제1권2호
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• pp.38-45
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• 2012

A novel kind of switched reluctance motor (SRM) with short flux path is proposed in this paper. Phase excitation in the SRM gives short flux paths, hence reducing the magnetomotive force required to drive the machine, resulting in significant reduction of copper wire and core losses compared to the typical SRM with diametric circulation of magnetic flux. To verify the performance, the characteristics analysis of a double-stator SRM, a 6/5 SRM with C-core structure, and a 4/5 two-phase SRM, which all have short flux paths, and a comparison with conventional SR motors are executed. The comparison demonstrates that the proposed motor offers some advantages in terms of torque and efficiency.

• Bulletin of the Korean Chemical Society
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• 제28권12호
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• pp.2162-2190
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• 2007

The newly-developed Meerwein-Ponndorf-Verley (MVP) type reagents using aluminum, boron and other metals for reduction of organic functional groups such as carbonyl and epoxy compounds have been surveyed. highlighted and reviewed in this account are the appearance of new MPV type reagents and their application to the selective reduction of organic functions. Finally, this account emphasizes the distinct contrast in the reducing characteristics existed between metal hydride reagents and MPV reagents, and compares their usefulness in organic synthesis.

• Bulletin of the Korean Chemical Society
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• 제19권2호
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• pp.243-249
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• 1998

The reaction of alcohol with a solution of thexylborane (ThxBH2) in tetrahydrofuran (THF) provides a new class of mild and selective reducing agents, thexylalkoxyboranes (ThxBHOR: R=Et, i-Pr, i-Bu, s-Bu, t-Bu, Ph). In order to elucidate the effect of the alkoxy group in reduction reactions, the reducing power of ThxBHOR toward selected organic compounds containing representative functional groups under practical conditions (THF, 25°, the quantitative amount of reagent to compound) has been investigated. Generally, the reactivity of ThxBHOR is largely dependent upon the alkoxy substituent. ThxBHOR can be synthesized from a variety of alcohols, thus allowing control of the steric and electronic environment of these reagents.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.2009_2010
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• 2009

Thin-gauged 3% Si-Fe sheets having a high magnetic induction of over 1.9 T have been developed for the purpose of applications where operation frequency is higher than power frequency. In order to clarify requirements of iron loss characteristics for the applications, iron loss characteristics of the newly developed strip were investigated by iron loss separation method and were compared with those of commercially produced 0.3 mm-thick electrical sheets. In case of relatively high excitation induction(1.7 T) and low frequency(60 Hz), reducing hysteresis loss is effective to decrease total iron loss. In case of relatively low excitation induction(1.0 T) and high frequency(1 kHz), reducing eddy-current loss is effective by decreasing thickness and grain size to improve total iron loss.

• Bulletin of the Korean Chemical Society
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• 제29권4호
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• pp.885-886
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• 2008

• KSBB Journal
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• 제15권2호
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• pp.201-207
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• 2000

전통적으로 사용되어 왔던 점토의 숙성과정을 과학적으로 규명하였고, 철환원세균의 농화배양액을 이용하는 생명공학기술을 이용한 개량된 점토 숙성방법을 연구하였다. 전통적으로 사용되어 왔던 수비법에 의한 점토의 숙성은 토착 미생물들이 점토에 함유된 유기물을 분해하는 과정에서 철불순물을 점토로부터 제거하여 색상을 향상시킬 뿐만 아니라 점토의 점성과 가소성 및 강도를 증진시키는 효과가 있음을 알 수 있었다. 점토숙성용 철환원세균 농화배양액을 얻는 방법을 제시하였고, 점토에 탄소원을 첨가한 후 혐기적 조건에서 농화배양액을 이용한 점토 숙성 방법을 제시하였다. 생물공학기술을 활용한 개량점토 숙성법은 전통적인 점토 숙성에서 소요되는 점토의 처리 시간을 약 1/6 수준이하로 단축시킬 수 있었고, 점토로부터 철불순물을 보다 효과적으로 제거할 수 있었을 뿐만 아니라 전통적인 방법보다도 물성이 우수한 점토로 고품위화가 가능하였다.

• Journal of Electrical Engineering and Technology
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• 제4권2호
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• pp.266-271
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• 2009

In this paper, improved direct torque control(DTC) of five-phase induction motor(IM) is proposed. Due to the additional degrees of freedom, five-phase IM drives present unique characteristics. One of them is the ability of enhancing the torque producing capability of the motor. Also five-phase motor drives possess many others advantage compared with the traditional three-phase motor drives. Such as, reducing the amplitude and increasing of frequency of torque pulsation, reducing amplitude of current per phase without increasing the voltage per phase and increasing the reliability. The direct torque control method is advantageous when it is applied to the five-phase IM. Because the five-phase inverter provides 32 space vectors in comparison to 8 space voltage vectors by the three-phase inverter. The 32 space voltage vectors are divided into three groups according to their magnitudes. The characteristics and dynamic performance of traditional five-phase DTC are analyzed and new DTC for five-phase IM is proposed. Therefore, a more precise flux and torque control algorithm for the five-phase IM drives can be suggested and explained. For presenting the superior performance of the pro-posed direct torque control, experimental results is presented using a 32 bit fixed point TMS320F2812 digital signal processor

• Architectural research
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• 제23권3호
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• pp.49-54
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• 2021

In contemporary modern architecture, it can be said that Western modern architecture, which has advanced in technology and ideology, is leading the world architecture today. However, because it is pointed out that modern architecture, mainly represented by Western architecture nowadays, is based on the crystal of Western civilization's consumption and capitalist culture, and because it seems not absolute for the eternal sustainable development of the Earth and happiness of Humankind, it is assumed that the new conceptions of Architecture should include the cultural, ecological and environmental characteristics of the region. So because it is thought that the latent characteristics of East Asian architecture including China, Japan and Korea has the advantage of reducing the deficiency of Western modern architecture and contributing to human civilization, this study was written to find a new direction of architecture by finding the differences of architectural characteristics(intrinsic and extrinsic) in the interior of the architectural result through comparison between the Eastern and Western architecture.

• 동아시아식생활학회지
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• 제10권1호
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• pp.71-76
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• 2000

This study was carried out in order to investigated the degree of expansion, textural and sensory characteristics of Yukwa made from various cultivars of waxy rice, With 5 varieties of waxy rice and a nonwaxy rice, Yukwa were prepared by the standardized method that had been established optimum preparation conditions. Yukwa made from Shinsunchalbyeo and Whasunchal showed lower degree of expansion than Hangangchalbyeo and IR 29, but showed higher crispness and softer texture among tested waxy rice cultivars. Sensory characteristics of these cultivars showed high score in flavor, crispness and preference. Whasunchalbyeo and Shinsunchalbyeo were appropriate varieties for Yukwa preparation and they were both short grain in length/width. Whasunchalbyeo has the highest score of water uptake and reducing sugar content in Key word.