• 한국정보디스플레이학회:학술대회논문집
• /
• 2005.07a
• /
• pp.453-456
• /
• 2005

Color characteristics of a dark state in the IPS-mode depending on viewing direction have been studied. IPS-mode is having a little variation of $d{\Delta}n$ with viewing angle since the LC rotates in plane. However, this mode shows asymmetric light leakage and color characteristics with viewing angle in a dark state. This drawback can be overcome by optimized retardation value of TAC film, pre-tilt angle & $d{\Delta}n$ of LC.

• Journal of the Korean Ceramic Society
• /
• v.34 no.6
• /
• pp.577-582
• /
• 1997

The mechanical properties of Al2O3-ZrO2 composites fabricated by RBAO(reaction bonded aluminium oxide) process were investigated. As the amount of ZrO2 increased the sinstered density of Al2O3-ZrO2 composites decreased slightly, but wear resistance was enhanced. Bending strength of Al2O3-ZrO2 composites increased in proportion to the amount of al in case of a fixed ZrO2 content. When the amount of Al was fixed bending strength reached its maximum value at 25 wt% ZrO2. The fracture toughness(K1c) increased with increasing content of ZrO2, but decreased with increasing Al amount. On the other hand, the fracture mode of Al2O3-ZrO2 composites was the mixed mode of inter-and transgranular fracture.

• Journal of Veterinary Clinics
• /
• v.18 no.3
• /
• pp.297-303
• /
• 2001

A female pug was presented with severe anemia, dyspnea and hemoglobinuria. By B- and M-mode echocardiography, the large number of heartworm were founded in the right ventricle, right atrium and pulmonary artery. The heartworm mass was moved from the right ventricle to the right atrium with the motion of the tricuspid value. Paradoxic septum motion were visible in M-mode of left ventrcular outflow tract and chordae tendineae level short-axis view. Flattened interventricular septum was find in B-mode of papillary muscle level short-axis view. In autopsy, 81 adult heartworms and 7 filarial debris were found. Most of adult heartworm were found in the right ventricle and pulmonary artery. 3 of them were found in the venaca and right atrium, respectively.

• Proceedings of the ESK Conference
• /
• 1997.10a
• /
• pp.333-338
• /
• 1997

We performed a study to investigate the characteristics of color perception according to some factors and to suggest the initial setting value of color temperature in each mode of a PC and TV monitor. Investigated factors were monitor coating (coating vs. noncoating)and screen brightness(30fL vs. 35fL). Twenty-three subjects (male 12, female 11) participated in this experiment. The experiment was performed in eachmode of a PC and TV monitor. Average color temperatures were obtained in both PC- mode and TV- mode. In addition, effects of monitor coating and screen brightness were investigated.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2002.04a
• /
• pp.415-429
• /
• 2002

Various modeling techniques for ultrasonic wave propagation and scattering problems in finite solid media are presented. Elastodynamic boundary value problems in inhomogeneous multi-layered plate-like structures are set up for modal analysis of guided wave propagation and numerically solved to obtain dispersion curves which show propagation characteristics of guided waves. As a powerful modeling tool to overcome such numerical difficulties in wave scattering problems as the geometrical complexity and mode conversion, the Boundary Element Method(BEM) is introduced and is combined with the normal mode expansion technique to develop the hybrid BEM, an efficient technique for modeling multi-mode conversion of guided wave scattering problems.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.25 no.1
• /
• pp.29-36
• /
• 2020

In this study, a variable step algorithm is proposed on the basis of the perturb and observe method. The proposed algorithm can follow the maximum power point (MPP) quickly when solar irradiance changes rapidly. The proposed technique uses the voltage change characteristic at the MPP when the environment changes because of insolation or temperature. The MPP is tracked through the voltage control using a variable step method. This method determines the sudden change of solar irradiance by setting the threshold value and operates in fast tracking mode to track the MPP rapidly. When the operation point reaches the MPP, the mode switches to the variable step mode to minimize the steady state error. In addition, the output disturbance is decreased through the optimization of the control method design. The performance of the proposed MPPT algorithm is verified through simulation and experiment.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.65 no.7
• /
• pp.1186-1192
• /
• 2016

This paper proposes techniques to diagnose short-circuit faults of both the diodes and power FET in switching mode power supply (SMPS) by using a simple analog tester. The diodes in full-bridge rectifier, power FET, switching transformer, and some sensors are modelled with resistor. The total resistance value measured at the input terminal of a SMPS is analyzed when the short-circuit faults of diodes in a full bridge rectifier or power FET are occurred. The short-circuit faults of one or two diodes in a full bridge rectifier, power FET, and both the diodes in a full bridge rectifier and power FET can be detected by a range of total resistance, which is measured by the analog tester. Through experiments, the theoretical analysis for total resistance under short-circuit faults can be verified.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.16 no.2
• /
• pp.131-137
• /
• 2003

We have performed computer simulation to obtain electro-optic chracteristics of reflective liquid crystal display (LCD) using wide viewing angle LC mode, fringe field switching(FFS). Unlike other reflective LCD modes, in the FFS mode, the LC director in plance so an application to reflective display consisted of polarizer, LC layer and reflector is possible. when an incident light is 550mm, the optimal cell retardation value is 0.1365${\mu}$m and the efficiency of reflectivity is high over 90% with very little wavelength dispersion. Further, we have studied a new reflective display with polarizer, optical compensation film with half plate, LC plus reflector. The display with optimized cell parameters shows high contrast ratio (CR) over 130 with high light efficiency over 90% at normal direction and the CR greater than 5 exists over 60$^{\circ}$ of polar angle in all directions.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2005.07a
• /
• pp.23-25
• /
• 2005

Infrared bolometer sensor's variation is detected by voltage drop between reference resistor and bolometer resistor in this architecture. One of the serious problems in this architecture is that these resistors value has a process variation. So common-mode level could be different from expectation in room temperature. Different common-mode level could lead to wrong output at the end of readout circuit. We suggest useful method to solve this problem. Difference correction using capacitor has reduced CM level difference to 86% for 1 $M\Omega$. bolometer and reference resistor's 10% variation.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2005.07a
• /
• pp.485-486
• /
• 2005

Fringe-field switching mode which has a horizontal and vertical electric field exhibits high transmittance and wide viewing angle characteristics. In the FFS mode, a passivation layer between common and pixel electrodes exists, which functions as preventing current leakage of fringe-field. In this paper, we have studied LC behavior, transmittance and operating voltage characteristics with applied voltage as a function of the passivation layer thickness and defined optimal value of the layer to be about $0.5{\mu}m$.