• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.5
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• pp.1057-1061
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• 2007

In this study, we investigated the properties of ZnO thin films prepared by layer-by-layer method in RF magnetron sputtering system using AlAs and ZnO targets. Effects of $H_2O_2$ dip prior to thermal treatment were studied as well. Either n-type or p-type films were observed in our study depending on the annealing conditions. It thus indicates the feasibility of arbitrarily modifying the conductivity type. At the same time, it also implies the thermal instabilities of the film properties. Property measurements after stressing the films up to 144 hours showed that thermal variations of properties nay be suppressed by pre-treatment in 30% $H_2O_2$ for 1 min.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.32 no.3
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• pp.201-206
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• 2019

This report constitutes the first demonstration in Korea of single-crystal lateral gallium oxide ($Ga_2O_3$) as a metal-oxide-semiconductor field-effect-transistor (MOSFET), with a breakdown voltage in excess of 480 V. A Si-doped channel layer was grown on a Fe-doped semi-insulating ${\beta}-Ga_2O_3$ (010) substrate by molecular beam epitaxy. The single-crystal substrate was grown by the edge-defined film-fed growth method and wafered to a size of $10{\times}15mm^2$. Although we fabricated several types of power devices using the same process, we only report the characterization of a finger-type MOSFET with a gate length ($L_g$) of $2{\mu}m$ and a gate-drain spacing ($L_{gd}$) of $5{\mu}m$. The MOSFET showed a favorable drain current modulation according to the gate voltage swing. A complete drain current pinch-off feature was also obtained for $V_{gs}<-6V$, and the three-terminal off-state breakdown voltage was over 482 V in a $L_{gd}=5{\mu}m$ device measured in Fluorinert ambient at $V_{gs}=-10V$. A low drain leakage current of 4.7 nA at the off-state led to a high on/off drain current ratio of approximately $5.3{\times}10^5$. These device characteristics indicate the promising potential of $Ga_2O_3$-based electrical devices for next-generation high-power device applications, such as electrical autonomous vehicles, railroads, photovoltaics, renewable energy, and industry.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.3 no.2 s.5
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• pp.41-53
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• 2004

This study introduces the process of the field test of ETCS that has been performed by six enterprises for selecting the type of ETCS that will be applied to the internal tall roads. The main communication modes of six enterprises are active RF(radio wave)type and IR(optical wave)type. In this study, communication modes and systems, which are being used by each enterprises, have been compared and analyzed. Besides this, the configuration and the basic performances of the system have been checked. After those, the contents of the field performance test classified by the items of the test and the results of the test, finally, have been analyzed. Through analyzing the test, it is found that an enterprise using IR type and two enterprises using RF type satisfied the standards of the test and the others failed to meet the standards. However, the enterprises seem to be becoming stable by a large number of tests and the effort for improving from general point of view. Although the methods of performance evaluation in this field test considered enough patterns that are used in the present highway or Hi-Pass, there might possibly be some problems in the results because Korea Highway Corporation had decided the method and the number of times of the test according to their own standards about the various situations that can happen. Therefore, it will be needed to develop the method of standards for testing the performance which can be correspond with driver's behavior that can actually happen on the highway or the methods of transportation management.

• Journal of Korean Society of Forest Science
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• v.82 no.4
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• pp.431-440
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• 1993

This study was carried out to clarify a taxonomical relationships of the Korean Theaceae using characters from morphological, anatomical, electrophoretic and numerical methods. The results are summarized as follows ; Morphological data were cluster analysis by Euclidean distance, the complete and average linkage cluster were most distinctly classified into subfamily level. At the principal components analysis(PCA), the commutative contribution rate of three principal components showed to 91.1% total variance. By the leaf venation were classified semicraspedromous type of Theoideae and brochidodromous type of Ternstroemioideae. The stomatal types were classified Paracytic of Theoideae and Anomocytic type of Ternstroemioideae ; the former has founded subsideary cell the latter has not found. All taxa possessed common isozyme bands did not found out of Theaceae banding patterns. But, the activity of Theoideae were existed in below No.5(Rf. 4.0-4.4), in contrast to Ternstroemioideae were existed in more than No.7(Rf. 5.7-6.2). The cluster analysis of leaf characters and peroxidase isozymes were similarity between two methods.

• Journal of Microbiology and Biotechnology
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• v.21 no.10
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• pp.1057-1063
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• 2011

Herein, a novel ginsenosidase, named ginsenosidase type IV, hydrolyzing 6-O-multi-glycosides of protopanaxatriol-type ginsenosides (PPT), such as Re, R1, Rf, and Rg2, was isolated from the Aspergillus sp. 39g strain, purified, and characterized. Ginsenosidase type IV was able to hydrolyze the 6-O-${\alpha}$-L-($1{\rightarrow}2$)-rhamnoside of Re and the 6-O-${\beta}$-D-($1{\rightarrow}2$)-xyloside of R1 into ginsenoside Rg1. Subsequently, it could hydrolyze the 6-O-${\beta}$-D-glucoside of Rg1 into F1. Similarly, it was able to hydrolyze the 6-O-$_{\alpha}$-L-($1{\rightarrow}2$)-rhamnoside of Rg2 and the 6-O-${\beta}$-D-($1{\rightarrow}2$)-glucoside of Rf into Rh1, and then further hydrolyze Rh1 into its aglycone. However, ginsenosidase type IV could not hydrolyze the 3-O- or 20-O-glycosides of protopanaxadiol-type ginsenosides (PPD), such as Rb1, Rb2, Rb3, Rc, and Rd. These exhibited properties are significantly different from those of glycosidases described in Enzyme Nomenclature by the NC-IUBMB. The optimal temperature and pH for ginsenosidase type IV were $40^{\circ}C$ and 6.0, respectively. The activity of ginsenosidase type IV was slightly improved by the $Mg^{2+}$ ion, and inhibited by $Cu^{2+}$ and $Fe^{2+}$ ions. The molecular mass of the enzyme, based on SDS-PAGE, was noted as being approximately 56 kDa.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.282-282
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• 2012

본 연구에서 SiOC 박막을 제작하기 위해서 RF 마그네트론 스퍼터링법을 이용하여 유량별 RF 파워의 변화에 따라서 AZO 박막을 성장시켰으며 박막의 광학적 특성을 조사하였고 투명 전도성 박막으로써 AZO 박막을 SiOC 박막 위에 성장시켜서 광학적인 특성을 조사하였다. Si 웨이퍼의 종류에 따라서 광학적인 특성에 조금의 변화가 있는 것을 확인하였으며, n-type Si의 경우 electron transition에 의한 emission 특성이 달라지는 것에 비하여 상대적으로 p-type Si의 경우 변화가 거의 없는 것으로 나타났다. 일반적으로 사용되는 SiO2 산화막 위에 증착한 AZO 박막에 비하여 SiOC 박막 위에 증착할 경우 빛의 흡수가 많이 일어나는 것을 확인할 수 있었으며, AZO/SiOC 박막의 반사도 역시 많이 감소하였으며, 이러한 전기적인 특성은 태양전지에서 전면전극으로 사용할 경우 반사방지막으로서의 특징도 나타낸다는 것을 의미한다. 스퍼터 방법에 의한 증착법은 낮은 온도에서도 공정이 가능하다는 장점이 있으며, 절연특성이 우수한 SiOC 박막을 AZO 박막의 보호막으로 사용할 경우 용도에 따라서 우수한 특성을 나타낼 수 있음을 확인하였다.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.121-121
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• 2003

NiO thin films are very attractive for use as an antiferromagnetic layer, p-type transparent conducting films, in electrochromic devices and functional sensor layer for chemical sensors, due to their excellent chemical stability, as well as optical, electrical and magnetic properties. In addition, (100)- and (111)-oriented NiO films can be used as buffer layers on which to deposit other oriented oxide films, such as c-axis-oriented perovskite-type ferromagnetic films and superconducting films, because of the similarity in symmetry of oxygen ion lattice and lattice constants between the NiO films and the oriented oxide films. Thus, controlling the crystallographic orientation and surface roughness of the NiO films for a buffer layer are very important.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.28A no.11
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• pp.894-901
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• 1991

Contact-type linear image sensors have been fabricated by means of RF glow discharge decomposition method of silane and hydrogen mixtures. The dependences of the electrical and optical properties of these sensor on thickness, RF power, substrate temperature and ambient gas pressure have been investigated. the ITO/i-a-Si:H/Al structure film shows photosensitivity of 0.85 and photocurrent to dark current ratio ($I_{ph}/I_{d}$) of 150 at 5V bias voltage under 200${\mu}W/cm^[2}$ red light intensity. Under 200${\mu}W/cm^[2}$ green light intensity, the ratio is 100. In order to investigate photocarrier transport mechanism and to obtain ${\mu}{\gamma}$ product we have measured the I-V characteristics of these sensors favricated with several different deposition parameters under various light sources. The linear inage sensor for document reading has been operated under reverse bias condition with green light source, resulting in ${\mu}{\gamma}$ product of about 1.5$[\times}10^{-9}cm^{2}$/V.

• KIEE International Transactions on Electrophysics and Applications
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• v.5C no.3
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• pp.124-130
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• 2005

In this paper, we designed a cylindrical type light source having an electromagnetic principle of inductively coupled plasma, and measured its electrical-optical properties. Using the transformer principle, an electrically equivalent circuit cylindrical type light source was analyzed. According to the parameters of electromagnetic induction, which were diameter of coil with cpO.3$\~$ 1.2mm, number of turns with 4$\~$ 12 turns, distance with 40$\~$ l20mm and RF power with 10$\~$ 150W, the electrical .md optical properties were measured. When the diameter of the coil was cp0.3mm, number of turns was 8 and distance was 40mm, and the maximum brightness of 29,730 cd/m$^{2}$ was shown with RF power l50W. The relationship between electromagnetic induction and plasma discharges was demonstrated using the mode transition from E-mode to H-mode

• Journal of the Korea Institute of Information and Communication Engineering
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• v.3 no.1
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• pp.35-42
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• 1999

This paper describes the characteristics of the complex isotropic ferrite-rubber composite for a super wideband electromagnetic absorber in RP-A-PF type, which can be used for an anechoic chamber, wall material to prevent TV ghost, etc. The $Ni_x-A_{0.1}-ZN_{(1-x0.1)}$. $Fe{_2}O_4$ ferrite powder has been fabricated. Using this, then, [$Ni_x-A_{0.1}-ZN_{(1-x0.1)}$. $Fe{_2}O_4$]-Rubber composite for RF-layer in the RF-A-PF type absorber has been fabricated and it's characteristics has been analyzed. As a result, it has been shown that the [$Ni_x-A_{0.1}-ZN_{(1-x0.1)}$. $Fe{_2}O_4$].Rubber composite has excellent electromagnetic wave absorbing properties.