• Journal of the Korean Chemical Society
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• v.38 no.3
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• pp.200-207
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• 1994

A biosensor for the measurement of L-glutamine has been constructed by immobilizing the slice of Wistar rat kidney and it's organelle on $NH_3$ gas-sensing electrode. The effects of pH, buffer solution, temperature and thickness of slice were investigated in order to optimize electrode response. The tissue sensor had the linearity in the range of L-glutamine concentration $8.0{\times}10^{-5}{\sim}1.0{\times}10^{-2} M$ with a slope of 53.8 mV/decade in 0.05 M phosphate buffer solution, pH 7.8 at $30^{\circ}C$, and optimum thickness of slice and response time were 30 ${\mu}m$ and 3∼5 min, respectively. The organelle sensor showed the linearity within L-glutamine concentration range of $1.2{\times}10^{-4}{\sim}5.0{\times}10^{-3} M$ with a slope of 54.0 mV/decade in 0.05 M phosphate buffer solution, pH 7.8 at $30^{\circ}C$, and response time was 6∼7 min, respectively. Thus, it is clear that the tissue and organelle sensor will be useful for L-glutamine measurements.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.22 no.1
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• pp.5-10
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• 2012

In general, the fabrications of the LEDs with mesa structure are performed grown by MOCVD method. In order to etch and separate each chips, the LEDs are passed the RIE and scribing processes. The RIE process using plasma dry etching occur some problems such as defects, dislocations and the formation of dangling bond in surface result in decline of device characteristic. The SAG method has attracted considerable interest for the growth of high quality GaN epi layer on the sapphire substrate. In this paper, the SAG method was introduced for simplification and fabrication of the high quality epi layer. And we report that the size of selective area do not affect the characteristics of original LED. The diameter of SAG circle patterns were choose as 2500, 1000, 350, and 200 ${\mu}m$. The SAG-LEDs were measured to obtain the device characteristics using by SEM, EL and I-V. The main emission peaks of 2500, 1000, 350, and 200 ${\mu}m$ were 485, 480, 450, and 445 nm respectively. The chips of 350, 200 ${\mu}m$ diameter were observed non-uniform surface and resistance was higher than original LED, however, the chips of 2500, 1000 ${\mu}m$ diameter had uniform surface and current-voltage characteristics were better than small sizes. Therefore, we suggest that the suitable diameter which do not affect the characteristic of original LED is more than 1000 ${\mu}m$.

• Korean Journal of Remote Sensing
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• v.14 no.3
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• pp.296-306
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• 1998

Airborne MSS data is regarded as a potentially effective data source for the measurement of water quality and for the environmental change of water bodies. In this study, we measured the radiance reflectance by using multi-spectral image of low resolution camera(LRC) which will be reached in the multi-purpose satellite(KOMPSAT) to use the data in analyzing water pollution. We also investigated the possibility of extraction of water quality factors in water bodies by using high resolution remote sensing data such as Airborne MSS. Especially, we tried to extract environmental factors related with eutrophication such as chlorophyll-a, suspended sediments and turbidity, and also tried to develop the process technique and the radiance feature of reflectance related with eutrophication. Although it was difficult to explicitly correlate Airborne MSS data with water quality factors due to the insufficient number of ground truth data. The results were summarized as follows: First, the spectrum of sun's rays which reaches the surface of the earth was consistent with visible bands of 0.4${\mu}{\textrm}{m}$~0.7${\mu}{\textrm}{m}$ and about 50% of total quantity of radiation could be found. The spectrum was reached highest at around 0.5${\mu}{\textrm}{m}$ of green spectral band in visible bands. Second, as a result of the radiance reflectance Chlorophyll-a represented high mainly around 0.52${\mu}{\textrm}{m}$ of green spectral band, and suspended sediments and turbidity represented high at 0.8${\mu}{\textrm}{m}$ and at 0.57${\mu}{\textrm}{m}$, respectively. Finally, as a result of the water quality analysis by using Airborne MSS, Chlorophyll-a could have a distribution image after carrying out ratio of B3 and B5 to B7. Band 7 was useful for making the distribution image of suspended sediments. When we carried out PCA, suspended sediments and turbidity had distributions at PC 1 and PC 4 which are similar to the ground data. Above results can be changed according to the change of season and time. Therefore, in order to analyze the environmental factors of water quality by using LRC data more exactly, we need to investigate the ground data and the radiance feature of reflectance of water bodies constantly. For further studies, we will constantly analyze the radiance feature of the surface of water in wafter bodies by measuring the on-the-spot radiance reflectance and using low resolution satellite image(SeaWiFS). We will also gather the data of water quality analysis in water bodies and analyze the pattern of water pollution.

• Korean Journal of Pharmacognosy
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• v.35 no.4 s.139
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• pp.271-275
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• 2004

Distylium racemosum Sieb. Et Zucc contains some compounds inhibit -amylase activity in experimental conditions. The inhibitory test showed that 50% acetone extracts from the bark and leaves of the plant strongly inhibited salivary -amylase activity. Proanthocyanidin(PA) which has strong inhibitory activity was extracted from the leaves by chromatography on Sephadex LH-20. The inhibitory activities and the inhibition kinetics of the PA were studied against three kinds of enzymes: human salivary ${\alpha}-Amylase$ (SAA), pork pancreatin ${\alpha}-Amylase$ (PAA) and yeast ${\alpha}-Glucosidase$ (AG). Then the activities of PA against SAA, PAA and AG were compared with those of acarbose, a commercial agent. The inhibitory activities of PA were stronger than those of acarbose. Inhibition kinetics of the PA showed competitive inhibition for SAA and PAA, and non competitive inhibition for GA.

• Journal of the Korean Wood Science and Technology
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• v.35 no.5
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• pp.109-117
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• 2007

Methyl trans-cinnamate is a significant flavor compound of Tricholoma matsutake. Attempts were made to produce this compound by culturing the mycelium using submerged culture. No methyl trans-cinnamate could be detected when the mycelium was cultured in the basal liquid medium. However, the addition of Pinus desiflora extracts to the medium, methyl trans-cinnamate was largely produced. To find out compounds or fractions inducing methyl trans-cinnamate, dichloromethane fraction obtained from the wood extracts of P. densiflora was subjected to column chromatography. Three sub-fractions were obtained from the $CH_2CI_2$ fraction. Submerged cultured mycelium treated with sub-fraction 1 has the highest content of methyl trans-cinnamate. Maximum methyl trans-cinnamate $(470.2{\mu}g/g)$ was obtained when the first sub-fraction of dichloromethane fraction of the P. densiflora wood extracts was added to the medium. This indicates that wood extracts of P. densiflora contains inducer of the methyl trans-cinnamate production in the T. matsutake submerged culture.

• Korean Journal of Materials Research
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• v.7 no.8
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• pp.635-639
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• 1997

ECR-PECVD법을 사용하여 450-49$0^{\circ}C$이하의 온도에서 Pt/SiO$_{2}$/Si기판 위에 PZT 박막을 증착하였다. 기판 온도가 46$0^{\circ}C$ 이하일 경우에는 페로브스이트 상과 제2상으로 이루어진 박막이 성장하였으며 기판온도가 47$0^{\circ}C$이상일 때에는 페로브스카이트 단일상의 PZT 박막이 성장하였다. 49$0^{\circ}C$에서 매우 얇은 페로브스카이트의 PZT 박막을 증착한 후 $650^{\circ}C$에서 1분간 raped thermal annealing(RTA) 처리한 결과 박막의 조성과 결정성에는 거의 변화가 없었으나 박막의 전하 저장 밀도는 크게 향상되었다. 이는 RTA 처리에 의한 저유전 계면층의 소멸이 주된 이유라고 판단된다. 열처리 후 두께 40-45nm의 PZT박막은 200kV/cm의 전장 하에서 $10^{-6}$$\textrm{cm}^2$이하의 누설전류값을 갖고 있었으며, 인가전압 1V에서 300fF/$\mu$$m^2$의 정전용량, 즉 SiO$_{2}$환산두께 0.12nm를 나타내었다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1993.05a
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• pp.3-5
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• 1993

It is very important that a spectrum of reflectance is in accord wi th a spectrum of absorbance for a effective heating. Therefore. the objective of this study was to achieve a technical composite for material plan which PTC thermistor increase a radiation property of far-infrared and keep a characteristic of R-T The Ceramic speciman studies had the composition $BaTiO_3$ with additive of 1.67 $Al_2O_3$, 3.75 $SiO_2$, 1.25 $TiO_2$, 0.15 $Sb_2O_3$ and 0.00-0.182 $MnO_2$. $MnO_2$ amounts of additives was both increase on the anomalous resistivity-temperature characteristics and high efficiency on the radiation properties bodies of far-infrared. This result shows that specimens produced high emissivity(average 0.8) of far-infrared at 4.5-15$[{\mu}m]$ by measuring a characteristic of IR and R-T.

• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.12
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• pp.142-146
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• 2012

Today, the demand for high-speed data communication and mobile communication has exploded. Thus, there is a growing need for optical communication systems that convert large volumes of data to optical signals and that accommodate and transmit the signals across long distances. Digital optical communication with these characteristics consists of a master unit (MU) and a slave unit (SU). However, the digital optical units that are currently commercialized or being developed transmit data without compression. Thus, digital optical communication using these units is restricted by the quantity of optical frames when adding diversity or operating with various combinations of CDMA, WCDMA, WiBro, GSM, LTE, and other mobile communication technologies. This paper suggests the application of a data compression algorithm to a digital signal processor (DSP) chip as a field programmable gate array (FPGA) and a complex programmable logic device (CPLD) of a digital optical unit to add separate optical waves or to transmit complex data without specific changes in design of the optical frame.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2006.11a
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• pp.141-144
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• 2006

In this study, the friction and wear characteristics of pure epoxy and silica-filled epoxy resin composites with average silica particle diameter of $6-33{\mu}m$ were investigated at ambient temperature by pin-on-disc friction test. The cumulative wear volume, friction coefficient and wear rate of these materials against SiC abrasive paper were determined experimentally. The cumulative wear volume tended to increase nonlinearly with increase of sliding distance and depended on diameter of the silica particle for all these composites. The sliding wear tests of the materials demonstrated that the friction coefficient and the wear rate of silica filled epoxy composites were lower than those of the pure epoxy. silica filled epoxy.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.189.1-189.1
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• 2014

Lead zirconium titanate (PZT) is usually used as bulk and thin films. Due to high flexibility and piezoelectric, ferroelectric and pyroelectric properties, PZT fiber has attracted in a variety of fields such as sensor devices, non-electromechanical systems and non-volatile ferroelectric memory devices. And PZT fiber can be numerously synthesized and almost with the diameter of PZT fiber thicker than $10{\mu}m$. However, the electrospinnig method is cost effective and convenient. PZT obtained by electrospinning methodhas the diameter from sub-micro to nanometer. In this paper, the PZT/PVP nanofibers were synthesized with three precursors, lead nitrate, zirconium ethoxide and titanium isopropoxide. And the PZT nanofibers were fabricated after removal of PVP by annealing process at various temperature. The obtained PZT nanofibers were characterized by means of X-ray photoelectron spectroscopy (XPS) for chemical properties, X-ray diffraction (XRD) for crystallinity and phase, scanning electron microscopy (SEM) for morphologies. The diameter of PZT nanofibers were measured with SEM. From the SEM images, we confirmed that diameter of PZT nanofibers was hundreds of nanometers and decreased with increasing the annealing temperature. When the annealing temperature increased, the crystallinity of PZT nanofibers changed from pyrochlore to perovskite structure.