• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.1331-1334
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• 2008

In this paper, we developed a novel hyperreality display called the Head Dome Projector (HDP). The HDP is a head-mounted display consisting of a dome-shaped screen with a very small radius of 40 cm, a mobile projector with ultra-wide projection lens and LED light sources. The main feature of the HDP is very wide viewing angle of 160 degrees horizontally by 120 degrees vertically comparable to the human visual field of view without head tracking and 360 degrees by 360 degrees with head tracking. According to our subjective evaluation comparing the HDP with a flat-panel display (FPD), the HDP realizes hyperreality 2.5 points higher than that realized by an FPD in the case of ${\pm}5$ level evaluation for HD motion images.

• Journal of electromagnetic engineering and science
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• v.2 no.1
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• pp.39-44
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• 2002

A high speed data link capability is one of the critical factors in determining the performance of the spaceborne SAR system with high resolution because of the strict requirement far the real-time data transmission of the massive SAR data in a limited time of mission. In this paper, based on the data lint model characterized by the spaceborne small SAR system, the high rate multi-channel data link module is designed including link storage, link processor, transmitter, and wide-angle antenna. The design results are presented with the performance analysis on the data link budget as well as the multi-mode data rate in association with the SAR imaging mode of operation from high resolution to the wide swath.

• Proceedings of the KIEE Conference
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• 1999.07f
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• pp.2487-2489
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• 1999

This paper proposes a wide speed range sensorless vector control strategy. At low speed region, the difference of high frequency impedances is used in order to estimate the rotor flux angle. At high speed region this algorithm is combined with the adaptive observer. It enables the stable operation even at zero speed under the rated load condition This is verified by experimental results.

• Smart Structures and Systems
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• v.14 no.4
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• pp.541-558
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• 2014

This paper proposes a new design of shape memory alloy (SMA) wire actuated gripper for open mode operation. SMA can generate smooth muscle movements during actuation which make them potentially good contenders in designing grippers. The principle of the shape memory alloy gripper is to convert the linear displacement of the SMA wire actuator into the angular displacement of the gripping jaw. Steady state analysis is performed to design the wire diameter of the bias spring for a known SMA wire. The gripper is designed to open about an angle of $22.5^{\circ}$ when actuated using pulsating electric current from a constant current source. The safe operating power range of the gripper is determined and verified theoretically. Experimental evaluation for the uncontrolled gripper showed a rotation of $19.97^{\circ}$. Forced cooling techniques were employed to speed up the cooling process. The gripper is simple and robust in design (single movable jaw), easy to fabricate, low cost, and exhibits wide handling capabilities like longer object handling time and handling wide sizes of objects with minimum utilization of power since power is required only to grasp and release operations.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.05a
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• pp.995-1000
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• 2000

In this paper. a mechanistic model is first constructed to predict three-dimensional cutting forces, and the uncut chip th thickness is calculated by following the movements of the position of the center of a cutter, which varies with the nominal feed, cutter deflection and runout. For general implementation to a real machining, this paper presents the method that determines constant cutting force coefficients, irrespective of the cutting conditions or cutter rotation angles. In addition, this study presents the approach which estimates runout-related parameters. the runout offset and its location angle, using only one measurement of cutting forces. For more accurate cutting force predictions, the size effect has to be considered in the cutting force model. In this paper, two approximate methods are suggested since the strict approach is practically impossible due to a measurement problem. The size effect is individually considered for narrow and wide cuts.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2003.11a
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• pp.248-258
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• 2003

Finite element computations were carried out to study the indentation by rigid cone with half-angle of $70.3^{\circ}$ for 72 different combinations of elasto-plastic properties that cover the wide range of mechanical parameters of common engineering solid materials. The dimensional analysis and representative strain concept were used in the analysis. It was shown that for the same representative strain value, the loading curvature C can be formulated under two different forms, which are based on two alternative dimensionless functions. The present study's one is simpler than the other previously found by other authors using the similar approach. For a wide range of material's parameters, the hardness-modulus ratio should be a parabolic function of ${\sigma}E$, rather than a power law function earlier proposed.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.294-298
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• 2000

As the LED or LCD technology has been developed, if we use LED or LCD pannel, more wide color range coluld be obtained as CRT monitor. Specially, full color LED display is developed by high brightness blue LED. It can be applicable to display pannel with a long-life, wide visible angle and high brightness. A display pannel shows the images of CRT monitor performed by the main computer. Graphic application in the main computer is therefore more important in the market. Conventional 3D STUDIO, one of graphic softwares, has difficulties in manipulating and understanding the specific terminology so that one may need more time to learn it. We, therefore, developed graphic application which can recycle the conventional 3D images by creating or editing the image easily.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.446-447
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• 2006

We investigated the electro-optic characteristics of a fringe-field driven twisted nematic (TN) display using a LC with negative dielectric anisotropy depending on electrode structures. The fringe-field driven TN mode known to exhibit wide viewing angle and excellent color characteristics over a wide viewing range and high transmittance. However, when the electrode width and distance between them is large enough, the transmittance is lower than the conventional vertical field-driven TN mode. By narrowing the electrode width and distance, the transmittance reaches the same value of the conventional TN mode.

• Journal of the Korea Institute of Military Science and Technology
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• v.27 no.2
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• pp.230-237
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• 2024

Dispersion munitions are often equipped with dispersive submunitions used to scatter bombs over a wide area, and one of the types of dispersive submunitions is the Magnus rotor, commonly referred to as a self-rotating flying body. The Magnus rotor is designed to be dispered over a wide area by utilizing the principle of the Magnus effect through self-rotation, and has various trajectories depending on the initial conditions from the mother dispersion munition. In this paper, an index to evaluate the dispersion uniformity of footprint of the dispersive submunition is presented and the dispersion uniformity according to various initial release conditions is evaluated, and it is getting larger with high incidence angle and get max value at certain initial angular velocity.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.14 no.2
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• pp.72-78
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• 1981

The purpose of this study is to find directivity characteristics and relative gain of directivity of the wedge horn in conjunction with a projector with varing horn length, horn angle and frequency. The horns are constructed with aluminum plate covered with styrofoam. By using hinges the horn angle could be varied with wide range. Measurements were made over the frequency range of 25 KHz-100 KHz by varing the horn lengths from 5cm to 21cm and the horn angles up to 90 degrees. The followings were the results obtained from the study, 1. As the horn angle increased, the beam width for tile major lobe initially decreased and then increased. At 80 KHz with horn length 21cm the minimum beam widths were obtained with 16 degrees in horizontal plane and 36 degrees in vertical plane. 2. The maximum relative gains of directivity were 4.4 dB in horizontal plane and 3.4 dB in vertical plane when the horn length was 21cm. 3. Beam width was decreased with increasing of frequency. 4. When the mouth apertures were small the major lobes obtained by the experiment agreed with the computed ones, and when the mouth apertures were wide the major lobes by the observed were wide than the computed ones.