• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2007년도 7th International Meeting on Information Display 제7권1호
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• pp.101-104
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• 2007

We propose a novel optical configuration for transmissive and reflective mode in the IPS LC cell to improve the viewing angle characteristics in a diagonal direction. The optical design was performed on a Poincar$\dot{e}$ sphere. From the calculation, we confirmed that the proposed configuration provides excellent viewing angle characteristics.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2008년도 International Meeting on Information Display
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• pp.1580-1583
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• 2008

We propose an optical configuration for a vertical alignment (VA) liquid crystal (LC) cell to eliminate the off-axis light leakage in the dark state. The proposed compensation configuration consists of a positive A-film, a positive C-film and a negative C-film. The optical design is performed on a Poincar$\acute{e}$ sphere. This configuration has a better tolerance to the wavelength dispersion, as the polarization trace could self-compensate it. From calculations, we show that the proposed VA LC cell can improve the viewing angle characteristics by compensating for the light leakage in the diagonal direction.

• 한국통신학회논문지
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• 제34권5A호
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• pp.414-420
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• 2009

본 논문에서는 OFDMA 기반 relay 시스템에서 throughput 성능개선을 위한, Base Station (BS)과 Relay Station (RS)의 sub-cell 커버리지 설정기법을 제안한다. Relay 시스템에서는 BS-RS 링크에서 무선 자원을 추가로 소비하므로, RS간 자원의 재사용을 고려하면 자원의 효과적 사용이 가능하다. 그러나, 이때 신호의 간섭이 증가하므로 단말기의 수신 Signal to Interference and Noise Ratio (SINR)에 영향을 미치게 된다. 그리므로 본 연구에서는 자원 재사용 정도에 따른 사용가능 자원의 증가를 수신 SINR과 함께 sub-cell 커버리지 결정의 요인으로 함께 고려한다. 모의실험을 통한 결과분석을 통해 throughput 성능을 개선할 수 있는 sub-cell 커버리지를, 다양한 자원재사용 패턴에 따라 도출하였다.

• Journal of Mechanical Science and Technology
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• 제20권7호
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• pp.1089-1097
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• 2006

The market demand of display devices is drastically increasing in the information technology age. The research on OLED (Organic Light Emitting Diodes) display with the luminescence in itself is being more paid attention than LCD (Liquid Crystal display) with the light source from the back. The vapor deposition process is most essential in manufacturing OLED display. The temperature distribution of the linear cell in this process is closely related to securing the uniformity of organic materials on the substrate. This work analyzed the temperature distribution depending on the intervals between the crucible and the heating band as well as on the amount of the heat flux from the heating band. Moreover, the roles of the water jacket and the configuration of the cover within the linear cell were examined through the temperature analysis for six configurations of the linear cell. Under the above temperature analysis, the variations in the intervals and the amount of the heat flux were considered to have an effect on building the uniform temperature distribution within the crucible. It is predicted that the water jacket and the adequate configuration of the cover will prevent the blowout and clogging phenomena, respectively. The results can be used as the fundamental data for designing the optimal linear cell.

• 한국자동차공학회논문집
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• 제9권5호
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• pp.195-205
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• 2001

The mechanical properties of aluminum honeycomb on the direction of axial crushing under quasistatic loading test was investigated. The crushing process was simulated numerically by full-scale finite element models. Simulations reproduce the experimental results both qualitatively as well as quantitatively. From the investigation, we suggested the constitutive model of energy absorbing honeycomb structure for large scale impact analysis. Real impact test of the WB(Moving Deformable Barrier) was carried and compared with finite element simulation. Constitutive model used in the numerical simulation had a good correlation with experiment. By suggesting the optimizing method fur honeycomb cell configuration design, relationship between cell configuration and crush strength is studied.

• 설비공학논문집
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• 제19권4호
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• pp.339-345
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• 2007

In the present study, a 10-cell PEMFC stack with straight type cathode flow channels is employed to investigate the effect of inlet air flow header configuration on the overall fuel cell performance. Four different types of inlet flow headers are considered and the flow patterns according to the air inlet flow header configuration are numerically obtained. The computed result for a modified header predicts about 8.5% improvement in the air flow distribution at 10-cell cathode channel inlets. Experiments are also carried out to confirm the numerical findings by measuring actual air flow distributions and the polarization curves of the PEMFC stack.

• Nuclear Engineering and Technology
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• 제51권4호
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• pp.996-1007
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• 2019

We investigated the influence of the aspect ratio (H/R) of the oxide layer on the reactor vessel heating in three-layer configuration. Based on the analogy between heat and mass transfers, we performed mass transfer experiments to achieve high Rayleigh numbers ranging from $6.70{\times}10^{10}$ to $7.84{\times}10^{12}$. Two-dimensional (2-D) semi-circular apparatuses having the internal heat source were used whose surfaces of top, bottom and side simulate the interfaces of the oxide layer with the light metal layer, the heavy metal layer, and the reactor vessel, respectively. Multi-cell flow pattern was identified when the H/R was reduced to 0.47 or less, which promoted the downward heat transfer from the oxide layer and possibly mitigated the focusing effect at the upper metallic layer. The top boundary condition greatly affected the natural convection of the oxide layer due to the presence of secondary flows underneath the cold light metal layer.

• 제어로봇시스템학회논문지
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• 제5권5호
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• pp.614-621
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• 1999

In this paper, the analytical appproaches are presented for jointly determining the profit-miximizing configuration of the fault-tolerance real time modular cell manufacturing system. The transient(time-dependent) analysis of Markovian models is firstly applied to modular cell manufacturing system from a performability viewpoint whose modeling advantage lies in its ability to express the performance that truly matters - the user's perception of it - as well as various performance measures compositely in the context of application. The modular cells are modeled with hybrid decomposition method and then availability measures such as instantaneous availability, interval availability, expected cumulative operational time are evaluated as special cases of performability. In addition to this evaluation, sensitivity analysis of the entire manufacturing system as well as each machining cell is performed, from which the time of a major repair policy and the optimal configuration among the alternative configurations of the system can be determined. Secondly, the recovery policies from the machine failures by computing the minimal number of redundant machines and also from the task failures by computing the minimum number of tasks equipped with detection schemes of task failure and reworked upon failure detection, to meet the timing requirements are optimized. Some numerical examples are presented to demonstrate the effectiveness of the work.

• Journal of Information Display
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• 제9권2호
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• pp.22-27
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• 2008

We propose an optical configuration of a vertical alignment (VA) liquid crystal (LC) cell to eliminate the light leakage in the diagonal direction. VA LC cell has an excellent contrast ratio in the normal direction due to the no phase-retardation. However, change of the phase-retardation occurs in all directions, which causes the light leakage and deteriorates the characteristics of the dark state. We designed the LC cell structure composed of multiple combinations with two A-plates and two C-plates in order to achieve wide viewing property on the Poincare sphere. From calculations, we show that the proposed structure can improve the viewing angle characteristics by compensating for the light leakage in all directions.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2007년도 7th International Meeting on Information Display 제7권1호
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• pp.502-505
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• 2007

In this paper we propose a novel electrode structure for high transmittance in the Patterned Vertical Alignment (PVA) LC cell. Normally, the transmittance of PVA LC cell is depended on the shape of the electrode and cell gap. We studied the area decreasing the transmittance through the electrode structure for wide viewing angle and proposed new electrode design to change LC director configuration in the area. We use the 'TechWiz LCD' for calculation of the director configuration and optical characteristics. We show the comparison of the calculated optical transmittance between the conventional PVA mode and the proposed PVA mode. From the results, we confirm that the optical transmittance of the proposed structure of the PVA cell becomes higher.