• New & Renewable Energy
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• v.3 no.4
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• pp.54-62
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• 2007

In this paper, we report the research highlight on the preparation and characterization of Indium-free $Cu_2ZnSnSe_4$ and Indium-reduced $CulnZnSe_2$ thin films in order to seek the viability of these absorber materials to be applied in thin film solar cells. The films of $Cu_2ZnSnSe_4\;and\;CulnZnSe_2$ were prepared using mixed binary chalcogenides powders. It was observed that Cu concentration was a function of substrate temperature as well as CuSe mole ratio in the target. Under an optimized condition, $Cu_2ZnSnSe_4\;and\;CulnZnSe_2$ thin films grew with strong [112]. [220/204] and [312/116] reflections. Both $Cu_2ZnSnSe_4\;and\;CulnZnSe_2$ films were found to exhibit a high absorption coefficient of $104^4cm^{-1}\;Cu_2ZnSnSe_4$ film showed a band gap of 1.5eV which closes to the optimum band gap of an ideal solar absorber for a solar cell. On the other side, an increase of optical band gap from 1.0 to 1.25eV was found to be proportional with an increase of Zn concentration in the $CulnZnSe_2$ film. All films in this study revealed a p-type semiconductor characteristic.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.461-462
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• 2006

A single-gap and single-gamma transflective liquid-crystal (LC) display using patterned vertical alignment (PVA) mode was designed. In the device, a vertical electric field drives a vertically aligned LC to tilt down to optimize polarization efficiency. Electrodes of transmissive and reflective area were patterned $22.5^{\circ}$ and $45^{\circ}$ with respect to the polarizer so that a tilt-down direction of the LC director was $22.5^{\circ}$ and $45^{\circ}$ in the reflective and transmissive regions, respectively. In the device, the cell gap was the same for both regions, and the gamma curve matched each other in both regions because tilt angle of LC director was the same according to the applied voltage. Moreover, the dark state was irrespective of the cell retardation value at normal direction, which was highly important in massive fabrications. The switching principle and electro-optic characteristics of the device are reported herein.

• Journal of IKEEE
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• v.23 no.2
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• pp.524-528
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• 2019

Although different types of discharge cells exist, in common it is the primary goal for all discharge cells to have lower drive voltages and higher efficiency characteristics. To improve these factors, many studies are conducted that prolong the discharge path inside the discharge cell or change the composition of the working gas. In this paper, the two-dimensional fluid simulation was used to calculate the discharge voltage (firing voltage and sustain voltage) and the change in luminance and luminous efficacy according to the change in gap distance between discharge electrodes. In addition, we looked at changes in various charged particles, exciting particles and VUV particles, and studied the causes of the resulting values.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.479-482
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• 2004

We report a method for simultaneous measurements of cell gap, twist angle, birefringence dispersion of liquid crystal (LC) material and alignment directions in filled reflective LC cells. The method is based on spectral measurements of the LC cell reflectivity for three orientations ($0^{\circ},45^{\circ},90^{\circ}$) of the exit polarizer and may be applied for LC cells with low and high gaps.

• Development and Reproduction
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• v.5 no.2
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• pp.115-122
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• 2001

Production of a mature oocyte is a complex process that requires the close association between oocyte and follicular cells. The present study was conducted to investigate the difference between oocytes with and without close junctional communication with cumulus cells and the involvement of two connexins(CXs) in the interactions. Follicles at different sizes(small: 200～400 ㎛; large:>450 ㎛) were mechanically isolated from PMSG-primed mouse ovaries, and punctured to get cumulus-oocyte complex(COC). Oocytes were released themselves(denuded), with partially attached(partial), or with tightly attached(intact) cumulus cells. Maturation and fertilization capacity of the COCs were measured. Expression of CX 37 and CX 43 was examined by RT-PCR and in situ hybridization. The ratio between intact COC and denude/partial oocytes was 30％(SI) and 70％(SPD) in small follicles, while 55％(LI) and 45％(LPD) in large follicles, respectively. Maturation and fertilization rates of the released oocytes were similar among SI, LPD, LI groups, but those were significantly lower in SPD oocytes. In oocytes, CX 37 was the major CX and CX 43 was not expressed, whereas in the cumulus cells, CX 43 was the major, and CX 37 was the next. Results of the present study suggest that 1) immature oocytes from small follicles with intact cell-to-cell communication with cumulus have the similar quality to that of the oocytes from larger follicles, 2) gap junction between oocyte and cumulus cells may be the heterotypic channel, and 3) we could not explain the difference in the cell-to-cell communication between intact and partial/denuded COCs through the expression of the two CXs.

• Journal of Advanced Navigation Technology
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• v.16 no.1
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• pp.96-102
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• 2012

The goal of mobile internet system is to provide a high-data-rate, low-latency and optimized packet radio access technology supporting flexible bandwidth deployments. Therefore, network architecture is designed with the goal to support packet-switched traffic with seamless mobility, quality of service and minimal latency. An important requirement for the mobile internet system is improved cell-edge BER performance and data throughput. This is to provide some level of service consistency in terms of geographical coverage as well as in terms of available data throughput within the communication coverage area. In a cellular system, however, the signal to interference plus noise power ratio gap between cell-center and cell-edge users can be of the order of 20 [dB]. The disparity can be even higher in a communication coverage limited cellular system. This leads to vastly lower data throughputs for the cell-edge users relative to cell-center users creating a large QoS gap. This paper proposes a analytical approach that tries to reduce inter-cell interference, and shows the SIR and BER performance according to the OFDM system parameters in mobile Internet environment.

• Tuberculosis and Respiratory Diseases
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• v.44 no.1
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• pp.162-174
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• 1997

Background : Metabolic cooperation via gap junctional intercellular communication (GJIC) is an important mechanism of the bystander effect in gene therapy using the Herpes Simplex Virus thymidine kinase/ganciclovir (HSVtk) "prodrug" system. Since retinoids have been reported to increase GJIC by induction of connexin 43 expression, we hyporthesized that treatment of tumor cells with retinoic acid could augment the bystander effect of the HSVtk/GCV system and result in improved tumor cell killing by enhancing GJIC. Methods : We transferred HSVtk gene to SKHep-J cell line that does not express connexin43, and also transferred the gene to human and murine mesothelioma cell lines that express connexin43. We verified that retinoic acid enhanced GJIC utilizing a functional double-dye transfer study and evaluated the effects of retinoic acid on the growth rate of tumor cells. We then tested the effects of retinoic acid on bystander-mediated cell killing. Results : Addition of all-trans retinoic acid (RA) increased GJIC in cell lines expressing connexin 43 and was asspciated with more efficient in vitro bystander killing in cells transduced with HSVtk via adenoviral and retroviral vectors. In contrast, there was no increase in the efficiency of the bystander effect after exposure to RA in a cell line which had no delectable connexin 43. Conclusion : These results provide evidence that retinoids can augment the efficiency of cell killing with the HSVtk/GCV system by enhancing bystander effect and may thus be a promising new approach to improve responses in gene therapy utilizing the HSVtk system to treat tumors.

• Proceedings of the KIEE Conference
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• 1995.07c
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• pp.1413-1416
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• 1995

Plasma Display(PDP) was successfully demonstrated on 30-60inch display panel. Research for mass production is also been accelerating. The basic study of PDP are mainly focused on understanding of micro discharge in each cell In this paper, DC PDP with Ag electrode is made and the discharge charcateristics in micro gap is studied with the variation of the distance of electrode gap and the pressure in discharge cell.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.1179-1181
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• 2004

We have studied a single gap transflective liquid crystal display (LCD) associated with in-plane switching (IPS) mode. In the transmissive IPS cell, the transmittance of electrodes and above electrodes is different, that is, the degree of rotation of the LC director between electrodes and above electrodes is 45 $^{\circ}$ and 22.5 $^{\circ}$ , respectively. Utilizing the different rotating angle of the LC director and in-cell retarder with a quarter-wave plate used below the LC layer, the IPS transflective LCD is realized such that the area between electrodes is used as a transmissive part and the area above electrodes is used as a reflective part.

• Journal of Information Display
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• v.5 no.3
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• pp.8-13
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• 2004

We demonstrate a transflective liquid crystal display (LCD), doped with a chiral agent to produce a low helical twisting power, in a multimode configuration consisting of the homogeneous alignment and the hybrid alignment. The multimode transflective LCD with a single cell gap was fabricated using a single-step photoalignment technique with a self-masking process of an array of metal reflectors in the reflective region. In our configuration, the electro-optical disparity between the transmissive region and the reflective region was found to be significantly reduced by the low helical twisting power of the chiral dopant.