• Bulletin of the Korean Chemical Society
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• v.32 no.4
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• pp.1231-1236
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• 2011

Chiral discrimination is the ability to distinguish one enantiomeric form over another. The differential binding interaction between two molecules with the same helicity and those with the opposite helicity was investigated by using dispersion-corrected density functional theory. [5]helicene, tetrahydro[5]helicene and the polar D-${\pi}$-A compounds, 3,12-dimethoxy-7,8-dicyano-[5]helicene and 3,12-dimethoxy-7,8-dicyano-tetrahydro[5]helicene were the monomers considered in this study. In gas phase, the dimeric interaction from two helical molecules with the opposite handedness is greater than from those with the same handedness. The stable configurations of such dimers were identified. The most stable configuration tends to be the one with maximum contact between monomers.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.12
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• pp.119-126
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• 2004

Permanent magnetic gears are magneto-mechanical devices that are widely used to replace the ordinary mechanical gear and to transmit torque without the mechanical contact. This study investigates the characteristics of touch free permanent magnetic gear according to the employing systems. The effect of the magnetic torque is analyzed by using 3 dimensional Finite Element Method (FEM). To estimate the transmission torque of FEM model, the numerical results are compared with the experimental results. The influences of geometry size, magnet number on transmission torque are obtained. As results of this paper, it is confirmed that the transmission torque behavior is associated with the configuration of the magnet numbers and the air gap between the two permanent magnetic gears.

• Solar Energy
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• v.17 no.2
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• pp.23-33
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• 1997

This paper reviews the advanced solar cell structures used in space. These are the structures which incorporate the back surface field and reflectors with very shallow and lightly doped emitters. Their use in space has shown that the thinner cells are more resistive to radiation damage than the thicker ones. It has been found that the charged particles affect both the surface and bulk of the cells used in space. This causes degradation in the output power, which in effect, can be explained by the degrading diffusion length of the cells. The PERL cells showed higher BOL(beginning of life) efficiency and almost the same EOL(end of life) efficiency as structures with wrap-around contact configuration fabricated on 10 ${\Omega}cm$ resistivity substrates. This observation lead to a conclusion that, the space cells do not necessarily need to have very high BOL efficiency except in specific missions which require such.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.10
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• pp.1946-1950
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• 2011

This paper deals with an input device without the touch. The existing touch screens have some problems such as the week durability by frequent contact and the high cost by complex hardware configuration. In this paper, a non-touch input device is proposed to overcome these problems. The proposed method uses a skin color generated by the HCbCr color model and a hand region obtained by the labeling technique. In Addition, the skeleton model is employed to improve the recognition performance of the hand motion. Finally, the experiment results show the applicability of the proposed method.

• Journal of Astronomy and Space Sciences
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• v.12 no.2
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• pp.196-203
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• 1995

The UBV light curves of a close eclipsing binary SW Lyn were obtained with the observations made at the Sobaeksan Astronomy Observatory during 7 nights from September 1983 to March 1987. These light curves show asymmetry to the secondary minimum light and the asymmetry is larger at the shorter wavelength light curve. Assuming that the star sport makes the asymmetry, we employed the WD code to make the B and V light curves solution. We confirmed that SW Lyu has near contact(semi-detached) Roche configuration and has the Case A evolution.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.9-10
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• 2006

The patterning for the active layer of organic semiconductors is important to attain completely organic-based OTFTs(Organic Thin Film Transistors). We studied on possibility of the application of the conventional photolithography technique to pattern the organic active layer poly(3-hexylthiophene)(P3HT). Patterned P3HT-based OTFTs with Bottom Contact(BC) configuration were fabricated using the conventional photolithography. We achieved field-effect mobilities in the saturation regime ${\sim}1.2{\times}10^{-3}cm^2/V{\cdot}s$, $I_{on/off}$ ratios ${\sim}10^5$ in the subtractive method, ${\sim}8{\times}10^{-4}cm^2/V{\cdot}s$, $I_{on/off}$ ratios ${\sim}10^3$ in the additive one.

• 한국태양에너지학회:학술대회논문집
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• 2009.04a
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• pp.155-161
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• 2009

Desiccant systems have been proposed as energy saving alternatives to vapor compression air conditioning for handling the latent load. Use of liquid desiccants offers several design and performance advantages over solid desiccants, especially when solar energy is used for regeneration. The liquid desiccants contact the gas inside the packed column and the heat transfer and mass transfer will occur. This proposal is try study the mass transfer and heat transfer inside the packed column of dehumidifier and regenerator systems. And later on, the rates of dehumidification and regeneration that were affected by desiccant flow rates, air temperature and humidity, and desiccant temperature and all that variation will influence the performance of the systems.

• Transactions of Materials Processing
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• v.6 no.5
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• pp.408-415
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• 1997

The backward tracing scheme of the finite element analysis, which is counted to be unique and useful for process design in metal forming, has been developed and applied successfully in industry to several metal forming processes. Here the backward tracing scheme is implemented for process design of three-dimensional plastic deformation in metal forming, and it is applied to a precision coining process. The contact problem between the die and workpiece has been treated carefully during backward tracing simulation in three-dimensional deformation. The results confirm that the application of the developed program implemented with backward tracing scheme of the rigid plastic finite element leads to a reasonable initial piercing hole configuration. It is concluded that three-dimensional extension of the scheme appears to be successful for industrial applications.

• 연구논문집
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• s.27
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• pp.175-181
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• 1997

Superconducting joints between Bi-2223/Ag tapes are fabricated by a press & reaction anneal and a multiple press & anneal. The silver sheath was mechanically or chemically removed from one side of each tape without altering the superconducting core. The exposed superconducting core of the two tapes were brought into contact and pressed so as to form a lap joint. The joined tapes were then subjected to a series of different thermomechanical treatments to achieve optimum heat treatment condition. The result from transport measurements shows that critical current ($I_c$) transmitting through joined area reaches 9A, approximately 60% of the current capacity of the tapes themselves. The critical current through joined area was improved by repeated press and reaction annealing. Measurements of the current-voltage relationship were made with several configuration of the voltage probes to characterize the critical current variation and I-V curve along the joint. Also discussed are microstructural aspects of the superconducting joint.

• Proceedings of the KIEE Conference
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• 1989.11a
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• pp.258-263
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• 1989

The configuration of Brushless DC moter is similar to the permanent magnet Synchronous moter. Power transistors are oftenly used to supply the switching by feedback signals of rotor positioning sensors. Brushless DC moter have been used in Aerospace and Robotics where the electromagnetic noise or the sparking of the commutator contact can not be tolerated and long - lived maintenance - free operation is required. This paper describes the design of the microprocessor - based controller for the Brushless DC moter. The controller is designed to operate for the constant torque generation and variable speed control using sinusoidal PWM inverters and resolvers as rotor positioning sensors.