• Bulletin of the Korean Chemical Society
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• 제28권7호
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• pp.1159-1166
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• 2007

New unsymmetrical trans-stilbenes have been prepared by the sequential coupling reactions of bromobenzenesulfonate with formylarylboronic acids, benzylphosphonates and arylmagnesium bromides and characterized. The nickel-catalyzed reactions of stilbenesulfonates with aryl Grignard reagents produced the corresponding stilbenes via the nucleophilic aromatic substitution of the neopentyloxysulfonyl group by aryl nucleophiles. The great chemoselectivity of the alkyloxysulfonyl group allows the stepwise construction of unsymmetrical trans-stilbenes possessing terphenyl moieties. This procedure appears to be a promising and conceptually straightforward route for the parallel synthesis of various unsymmetrical stilbenes as well as other highly conjugated hydrocarbons.

• 소성∙가공
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• 제24권6호
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• pp.400-404
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• 2015

For mass production of stamped parts, which require complicated in-press operations, it is always advisable to use a progressive die set. It is difficult to choose a progressive die set if the stamped parts need to be deep drawn and especially if they are unsymmetrical. Because unsymmetrical deep drawing parts are very sensitive to the effect of weight during moving to the next step, they are hard to exactly locate on the die face. An automotive seat side cushion panel is about 80mm high, unsymmetrical and its low edge needs hemming, so it is hard to produce even using a progressive die set. In the current paper a progressive stamping for seat side cushion panel was examined. Five strip bridges were considered to be strong enough to move to the next die as predicted by the CAE analysis.

• Structural Engineering and Mechanics
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• 제78권3호
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• pp.269-280
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• 2021

Reinforced concrete (RC) structural walls with L-shaped sections are commonly used in RC buildings. The walls are often expected to sustain biaxial load and Unsymmetrical bending in an earthquake event. However, there currently exists limited experimental evidence regarding their seismic behaviour in these lateral loading directions. This paper makes experimental and numerical investigations to these walls behaviours. Experimental evidences are presented for four L-shaped wall specimens which were tested under simulated seismic load from different lateral directions. The results highlighted some distinct behaviour of L-shaped walls sustaining Unsymmetrical bending relating to their seismic performance. First, due to the Unsymmetrical bending, out-of-plane reaction forces occur for these walls, which contribute to accumulation of the out-of-plane deformations of the wall, especially when out-of-plane stiffness of the section is reduced by horizontal cracks in the cyclic load. Secondly, cracking was found to affect shear centre of the specimens loaded in the Unsymmetrical bending direction. The shear centre of these specimens distinctly differs in the flange in the positive and negative loading direction. Cracking of the flange also causes significant warping in the bottom part of the wall, which eventually lead to out-of-plane buckling failure.

• Wind and Structures
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• 제25권6호
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• pp.551-567
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• 2017

Studies of unsymmetrical blade H-Darrieus rotors at low wind speeds in terms of starting time, static torque, and power performances for different blade parameters: thickness-to-chord (t/c), camber position, and solidity are scarce. However these are required for knowing insights of rotor performances to obtain some design guidelines for the selection of these rotors. Here, an attempt is made to quantify the effects of these blade parameters on the performances of three different H-Darrieus rotors at various low wind streams. Different blade profiles, namely S815, EN0005 (both unsymmetrical), and NACA 0018 (symmetrical blade for comparison) are considered. The rotors are investigated rigorously in a centrifugal blower apparatus. Firstly the dynamic and static performances of the rotors are evaluated to determine the best performing rotor and their optimum solidity. Generalised performance equations are developed based on selected blade parameters which are validated for the unsymmetrical rotors. Further, the starting time is quantified with respect to the rotor inertia to determine the suitable range of inertia that helps the unsymmetrical blade rotor to self-start earlier than the symmetrical one. This study can work as a benchmark for the selection of optimum blade parameters while designing an unsymmetrical blade rotor at low wind speeds.

• 제어로봇시스템학회논문지
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• 제7권10호
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• pp.806-811
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• 2001

The analysis and control algorithm of a new type unsymmetrical self-bearing step motor is presented. The motor actuator is used for both motor and bearing functionality without any redundant coil windings or redudant electromagnets for bearing functionality. Self bearing step motor layout and control current generation method for unsymmetrical position of electromagnets are described. This new current generation method without additional current for bearing functionality leads to minimize the power loss. As the result of the unbalance response approach, the constant torque is possible, even though the bearing functionality is added or not.

• Bulletin of the Korean Chemical Society
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• 제33권4호
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• pp.1225-1230
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• 2012

A new unsymmetrical zinc phthalocyanine has been designed and synthesized based on the 'push-pull' and extended ${\pi}$-conjugation concept for the dye-sensitized solar cells. Three tert-butoxy groups, which act as electron releasing ('push'), enhance the solubility of phthalocyanine in common organic solvents and reduce the aggregation. Hydroxy substituted 9,10-anthraquinones act as electron acceptors ('pull') for the study of photoinduced electron transfer processes as well as grafting onto nanocrystalline $TiO_2$. The new unsymmetrical zinc phthalocyanine was fully characterized by FTIR, UV-vis, $^1H$ NMR, cyclic voltammetry and differential pulse voltammetry. The new sensitizer was tested in dye-sensitized solar cells, and gave a better performance.

• Bulletin of the Korean Chemical Society
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• 제33권6호
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• pp.2037-2039
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• 2012

• 한국방재학회 논문집
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• 제5권3호
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• pp.57-65
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• 2005

아치 리브가 비대칭 하중을 받는 경우 아치 리브의 면내 좌굴 강도는 대칭 하중이 작용하는 경우 보다 저하된다. 하지만 비대칭 하중을 받는 아치 리브에 관한 연구는 대칭 하중이 작용하는 아치 리브에 관한 연구에 비하여 적은 실정이다. 비대칭 하중을 받는 아치 리브에 관한 연구는 Deutch(1940), Chang(1973)과 Harrison(1982)에 의하여 수행되었으며, 비대칭 하중이 대칭하중보다 좌굴하중을 감소시킨다는 것을 밝혔다. 그러나 이러한 연구는 포물선아치에 국한되었다. 본 논문은 원형아치 리브에 비대칭하중이 작용하는 경우 아치 리브의 면내 거동을 연구하였다. 본 연구에 의하면 기하비선형이 고려된 임계좌굴하중은 활하중과 고정하중의 길이의 비가 $0.6{\sim}0.7$일 때 가장 작고, 기하 재료비선형이 고려된 경우에는 $0.5{\sim}0.6$에서 가장 작은 결과를 보인다.

• Bulletin of the Korean Chemical Society
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• 제34권10호
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• pp.2859-2860
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• 2013

• Steel and Composite Structures
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• 제23권1호
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• pp.17-29
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• 2017

The seismic performance of steel beam to concrete-encased composite column with unsymmetrical steel section joints is investigated and reported within this paper. Experimental and analytical evaluation were conducted on a total of 8 specimens with T-shaped and L-shaped steel section under lateral cyclic loading and axial compression. The test parameters included concrete strength, stirrup ratio and axial compression ratio. The response of the specimens was presented in terms of their hysterisis loop behavior, stress distribution, joint shear strength, and performance degradation. The experiment indicated good structural behavior and good seismic performance. In addition, a three-dimensional nonlinear finite-element analysis simulating was conducted to simulate their seismic behaviors. The finite-element analysis incorporated both bond-slip relationship and crack interface interaction between steel and concrete. The results were also compared with the test data, and the analytical prediction of joint shear strength was satisfactory for both joints with T-shaped and L-shaped steel section columns. The steel beam to concrete-encased composite column with unsymmetrical steel section joints can develop stable hysteretic response and large energy absorption capacity by providing enough stirrups and decreased spacing of transverse ties in column.