• 한국정밀공학회지
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• 제19권1호
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• pp.33-42
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• 2002

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2005년도 International Meeting on Information Displayvol.I
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• pp.91-96
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• 2005

In this paper, a general performance of the PSS-LCD or Polarization Shielded Smectic Liquid Crystal Display is discussed. This smectic base LCD does not use any spontaneous polarization, but uses induced polarization just same with current nematic base LCDs. Specific initial molecular alignment as well as specific cell design realizes extremely fast optical response speed with native wide viewing angle. Moreover, this performance is provided by full compatible electronics for current conventional LCDs. A general performance of the PSS-LCD is introduced here.

• 한국광학회지
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• 제1권1호
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• pp.87-97
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• 1990

With the recent advent of various ultrashort pulse lasers, time-resolved laser spectroscopic techniques have been widely recognized as versatile tools to study ultrafast phenomena in many research areas. These techniques are currently being employed not only to study atomic and molecular physics but to characterize the excited state or the carrier dynamics on surfaces of semiconductors, metals and thin layer materials. Also the sweetching speed measurement of ultrafast electro-optic devices using ultrashort laser pulses becomes important in high-speed electronics. Here, some principles of spectroscopic techniques with ps or fs lasers and their applications are summarized briefly.

• Molecules and Cells
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• 제24권3호
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• pp.307-315
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• 2007

Gene regulation is a fundamental process in biological systems, where transcription factors (TFs) play crucial roles. Inferring transcriptional interactions between TFs and their target genes has utmost importance for understanding the complex regulatory mechanisms in cellular systems. On one hand, with the rapid progress of various high-throughput experiment techniques, more and more biological data become available, which makes it possible to quantitatively study gene regulation in a systematic manner. On the other hand, transcription regulation is a complex biological process mediated by many events such as post-translational modifications, degradation, and competitive binding of multiple TFs. In this review, with a particular emphasis on computational methods, we report the recent advances of the research topics related to transcriptional regulatory networks, including how to infer transcriptional interactions, reveal combinatorial regulation mechanisms, and reconstruct TF activity profiles.

• Journal of Microbiology and Biotechnology
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• 제7권3호
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• pp.200-203
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• 1997

Bacteria isolated from ultrapure water made by a high-purity water manufacturing system in a semiconductor manufacturing plant were classified into two groups which either grew in diluted nutrient broth medium (oligotrophic bacteria) or could not grow (copiotrophic bacteria). The nutritional flexibility of oligotrophic and copiotrophic bacteria was investigated. The oligotrophic bacteria were shown to be able to utilize a significantly broader range of organic substrates than the copiotrophic bateria. This finding substantiates the hypothesis that nutritional flexibility is adaptive for oligotrophic bacteria.

• 전자공학회논문지D
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• 제35D권5호
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• pp.80-86
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• 1998

Material characterizations were performed for In$_{0.53}Ga_{0.47}As/In$_{0.52}Al_{0.48}$/As MQWs grown on InP substrates by low-temperature modlecular beam epitaxy. MQW samples were grwon at different temperatures of 200.deg.C, 300.deg. C and 500.deg. C, and doped with 10$^{18}$ cm$^{3}$ Be. High resolution x-ray diffraction measurement showed the change in crystal qualities according to growth temperature. Hall measurement showed the changes in carrier concentrations and mobilities for different growth temperatures. The optical properties of MQW samples were investigated with photoluminescence and fourier-transform infrared spectroscopy measurements.

• 전자공학회논문지A
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• 제31A권10호
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• pp.71-78
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• 1994

We have developed GaAs power metal semiconductor field effect transistors (MESFETs) for 4.7V operation under 900 MHz using a low-high deped structures grown by molecular beam epitaxy (MBE). The fabricted MESFETs with a gate widty of 7.5 mm and a gate length of 1.0.mu.m show a saturated drain current (Idss) of 1.7A and an uniform transconductance (Gm) of around 600mS, for gate bias ranged from -2.4 V to 0.5 V. The gate-drain breakdown voltage is measured to be higher than 25 V. The measured rf characteristics of the MESFETs at a frequency of 900 MHz are the output power of 31.4 dBm and the power added efficiency of 63% at a drain bias of 4.7 V.

• 전자공학회논문지A
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• 제31A권12호
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• pp.38-43
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• 1994

GaAs and AlGaAs layers were grown by Molecular Beam Epitaxy (MBE) to fabricate hith performance GaAs MESFETs. Optimum growth temperatures were found to be 600$^{\circ}C$ from their Hall measurement data. MESFETs with the gate legth of 1${\mu}$m and the gate width of 100.mu.m were fabricated on the MBE-grown GaAs layters which has i-GaAs buffer layer and characterized. Knee volgate and mazimum transconductance of the devices were 1V, 224mS/mm, respectively. Cut-off frequency at on-wafer measuring pattern was measured to be 18 GHz. The MESFET with the 1${\mu}$m -thick i-Al$_{0.3}Ga_{0.7}$As buffer layer between nactive and i-GaAs was fabricated on order to reduce the leakage current which flows through the i-GaAs buffer layer. Its output resistance was 2.26 k${\Omega}$.mm which increased by a factor of 15 compared with the MESFET without i-Al$_{0.3}Ga_{0.7}$As buffer layer.

• 전자공학회논문지A
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• 제31A권7호
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• pp.76-84
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• 1994

The characteristics of 3 inch wafer scale GaAs epitaxial wafer grown by molecular beam epitaxy for LSI process application were studied. The thickness and doping uniformity are characterized and discussed. The growth temperature and growth rate were $600^{\circ}C$ by pyrometer, and 1 $\mu$m/h, respectively. It was found that thickness and doping uniformity were 3.97% and 4.74% respectively across the full 3 inch diameter GaAs epitaxial layer. Also, ungated MESFETs have been fabricated and saturation current measurement showed 4.5% uniformity on 3 inch, epitaxial layer, but uniformity of threshold voltage increase up to 9.2% after recess process for MESFET device.

• 전자공학회논문지A
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• 제31A권9호
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• pp.114-120
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• 1994

We have been successfully fabricated the low nois HEMT device with AlGaAs and GaAs structure. The epitazial layer with n-type AlgaAs and undoped GaAs was grown by molecular beam epitaxy(MBE) system. Ohmic resistivity of the ource and drain contact is below 5${\times}10^{6}{\Omega}{\cdot}cm^{2}$ by the rapid thermal annealing (RTA) process. The ideality factor of the Schottky gate is below 1.6 and the gate material was Ti/Pt/Au. The HEMTs with 0.25$\mu$m-long and 200$\mu$m-wide gates have exhibited a noise figure of 0.65dB with associated gain of 9dB at 12GHz, and a transconductance of 208mS/mm.