• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.338-338
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• 2009

To date, rubbing has been widely used to align LC molecules uniformly. Although rubbing can be simple, it has fundamental problems such as the generation of defects by dust and static electricity, and difficulty in achieving a uniform LC alignment on a large substrate. Therefore, noncontact alignment has been investigated. Ion beam induced alignment method, which provides controllability, nonstop process, and high resolution display. We investigated the high pretilt angle effects on electro-optical properties of ion beam (IB)-irradiated liquid crystal cells. on a blended polymer surface. High pretilt angle of liquid crystals IB-irradiated on a blended polymer surface including such as 5% and 10% of homeotropic polymer contents can' be achieved. The threshold voltages of IB-irradiated twisted nematic (TN) cells on a blended polymer surface decrease with increasing the pretilt angle. Also, the rising time of IB-irradiated TN cells decreases with increasing the pretilt angle. However the decay time of IB-irradiated TN cells increases with increasing the pretilt angle. Consequently, the electro-optical properties of IB-irradiated TN cells depend strongly on the pretilt angle in a blended polymer surface.

• Journal of the Korea Institute of Military Science and Technology
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• v.21 no.4
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• pp.447-455
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• 2018

If a hidden enemy is shooting, there is a threat against soldiers in recent conflicts. This paper aims to improve the localization of a muzzle using microphone array. Gunshot noise can provide information about the location of muzzle with two signals, the muzzle blast from the gun barrel and the projectile sound from the bullet. Two signals arrive to the microphone array with different arrival time and angle. If the arrival angles of the two signals are estimated, distance between sniper location and the microphone array can be calculated by using geometric principles. This method was established in 2003 by Pare. But this method has a limitation that it cannot calculate the distance when the arrival angles of the two signals are same. Also it has an error when the angle difference of arrival is small. In order to overcome this limitation, a new method is proposed that uses the change of characteristic of the projectile sound with respect to vertical distance from the trajectory. The proposed method estimates the distance correctly when the arrival angle of two signals are same, and when the angle difference between two signals is increased, the estimation error increases with respect to the angle. Therefore these two methods can be selected according to the angle difference between two signals to estimate the distance of the muzzle. Below the threshold of the angle difference, the proposed method can be used to estimate distance with smaller error than the existing method. This was demonstrated by shooting tests using actual sniper rifles.

• Proceedings of the IEEK Conference
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• 2000.06b
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• pp.234-237
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• 2000

In this paper, a method to implement new Quasi-SOI LDMOSFET is introduced and the electrical characteristics of the device are studied. Key process steps of the device are explained briefly. By performing process and device simulations, electrical characteristics of the device are investigated, with emphasis on the optimization of the tilt angle of p$\^$0/ channel region. The electrical properties of the Quasi-SOI device are compared with those of bulk and SOI devices with the same process parameters. Simulated device characteristics are threshold voltage, off-state leakage current, subthreshold swing, DIBL, output resistance, lattice temperature, I$\_$D/-V$\_$Ds/, and cut-off frequency.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.1715-1718
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• 2006

Evaluating method of the device parameters of liquid crystal display (LCD) by means of the renormalized transmission spectroscopic ellipsometry is demonstrated. Dielectric and elastic constant, threshold voltage, pretilt angle, cell gap and Anchoring strength coefficients can be evaluated from the measurement of ellipsometric parameters measured by the symmetrically oblique incidence transmission ellipsometry (SOITE). Furthermore, rapid evaluating method for rubbed polyimide film is also demonstrated.

• Korean Journal of Remote Sensing
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• v.33 no.4
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• pp.359-375
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• 2017

We developed fog detection algorithm (KNU_FDA) based on the optical and textural properties of fog using satellite (COMS) and ground observation data. The optical properties are dual channel difference (DCD: BT3.7 - BT11) and albedo, and the textural properties are normalized local standard deviation of IR1 and visible channels. Temperature difference between air temperature and BT11 is applied to discriminate the fog from other clouds. Fog detection is performed according to the solar zenith angle of pixel because of the different availability of satellite data: day, night and dawn/dusk. Post-processing is also performed to increase the probability of detection (POD), in particular, at the edge of main fog area. The fog probability is calculated by the weighted sum of threshold tests. The initial threshold and weighting values are optimized using sensitivity tests for the varying threshold values using receiver operating characteristic analysis. The validation results with ground visibility data for the validation cases showed that the performance of KNU_FDA show relatively consistent detection skills but it clearly depends on the fog types and time of day. The average POD and FAR (False Alarm Ratio) for the training and validation cases are ranged from 0.76 to 0.90 and from 0.41 to 0.63, respectively. In general, the performance is relatively good for the fog without high cloud and strong fog but that is significantly decreased for the weak fog. In order to improve the detection skills and stability, optimization of threshold and weighting values are needed through the various training cases.

• Journal of Power Electronics
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• v.13 no.2
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• pp.264-274
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• 2013

A new sensorless position estimation method for switched reluctance motor (SRM) drives is presented in this paper. This method uses the change of the slope of the phase inductance to detect the aligned position. Since the aligned positions for successive electrical cycle of each phase are apart by a fixed mechanical angle $45^{\circ}$ in the case of 12/8 SRM, the speed of the machine can be calculated to estimate the rotor position. Since no prior knowledge of motor parameters is required, the method is easy for implementation without adding any additional hardware or memory. In order to verify the validity of this technique, effects such as changes in the advanced angle and phase lacking faults are examined. In addition, an inductance threshold based sensorless starting scheme is also proposed. Experimental results demonstrate the validity of the proposed method.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.198-201
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• 2004

We have developed a multi-domain vertically aligned liquid crystal display (MVA-LCD) that produces natural gray-scale images even at high viewing angles. We divided each pixel into two areas and set different threshold voltages for each sub-area. A transparent electrode in a sub-area is not connected directly to the source electrodes but via the capacitance of the SiN layer. In particular, light-orange skin color appears very natural, even at a high inclination angle. The contrast ratio is over 500 in the normal direction and over 10 from any viewing angle.

• Journal of Biosystems Engineering
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• v.23 no.3
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• pp.291-304
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• 1998

A control algorithm fir the unmanned vehicles was developed using image information received through a CCD camera that acquires more powerful information over the wide range of wave-length comparing with other sensors and was applied to a speed-sprayer. The algorithm consisted of straight mode for passing along with middle of two tree-rows and turning mode for changing from a row to another row. In case of turning mode, two marks of colored papers were employed to indicate turning point and to decide turning direction for various orchard situations. The method of analysis and image would be differed according to camera's tilt-angle and position that is set on the speed-sprayer. Hence, it analyzed the point of difference by making camera's up and downward tilt-angle.

• Proceedings of the Optical Society of Korea Conference
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• 2000.02a
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• pp.146-147
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• 2000

The electromagnetic wave scattering from active objects has only recently attracted attention.$^{(1).(3)}$ Theoretical studies have considered normal-incidence plane-wave interactions with active dielectric cylinders with the prediction of large enhancements in the scattered field for bound mode structures. According to the theory of the electromagnetic wave scattering from a dielectric cylinder, the eigenvector solutions are discrete and have both guided (non-radiative) and leaky (radiative) mode solutions. By using an anti-guiding (leaky) structure instead of a guided structure and scattering at oblique incident angles near critical angle, the scattering resonances predicted by theoretical studies were obtained for the first time. A fine-grained scan of the plane-wave incident angle a reveals the existence of discrete scattering resonances. The diameter and real part of the index of refraction determine the resonant conditions and the imaginary part of the refractive index has a threshold value to make mode up for its radiation loss. The cross coupling between transverse electric (TE) and transverse magnetic (TM) modes is clearly detected for both active and passive scattering as theoretically expected. (omitted)

• Journal of the Korean Society for Heat Treatment
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• v.13 no.5
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• pp.318-323
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• 2000

The planarization of rough polycrystalline diamond films synthesized by DC arc discharge plasma jet CVD (chemical vapor deposition) was attempted using KrF excimer laser pulses. The effects of laser incidence angle and reaction gases (ozone and oxygen) on etching rate of diamond were studied. The temperature change of diamond and graphite with different laser fluences was calculated by computer simulation to explain the etching behavior of diamond films. The threshold energy density from the experiment for etching of pure crystalline diamond was about $1.7J/cm^2$ and fairly matched the simulation value. Preferential etching of a particular crystallographic plane was observed through scanning electron microscopy. The etching rate of diamond with ozone was lower than that with oxygen. When the angle of incidence was $80^{\circ}$ to the diamond surface normal, the peak-to-valley surface roughness was Significantly reduced from $20{\mu}m$ to $0.5{\mu}m$.