• KIPS Transactions on Computer and Communication Systems
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• v.2 no.2
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• pp.67-74
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• 2013

Approximate string matching problems have been studied in diverse fields. Recently, fast approximate string matching algorithms are being used to reduce the time and costs for the next generation sequencing. To measure the amounts of errors between two strings, we use a distance function such as the edit distance. Given two strings X(|X| = m) and Y(|Y| = n) over an alphabet ${\Sigma}$, the edit distance between X and Y is the minimum number of edit operations to convert X into Y. The edit distance between X and Y can be computed using the well-known dynamic programming technique in O(mn) time and space. The edit distance also can be computed using the Four-Russians' algorithm whose preprocessing step runs in $O((3{\mid}{\Sigma}{\mid})^{2t}t^2)$ time and $O((3{\mid}{\Sigma}{\mid})^{2t}t)$ space and the computation step runs in O(mn/t) time and O(mn) space where t represents the size of the block. In this paper, we present a parallelized version of the computation step of the Four-Russians' algorithm. Our algorithm computes the edit distance between X and Y in O(m+n) time using m/t threads. Then we implemented both the sequential version and our parallelized version of the Four-Russians' algorithm using CUDA to compare the execution times. When t = 1 and t = 2, our algorithm runs about 10 times and 3 times faster than the sequential algorithm, respectively.

• International Journal of Oral Biology
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• v.41 no.3
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• pp.141-147
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• 2016

Reactive oxygen species (ROS) and nitrogen species (RNS) are both important signaling molecules involved in pain transmission in the dorsal horn of the spinal cord. Xanthine oxidase (XO) is a well-known enzyme for the generation of superoxide anions ($O_2^{\bullet-}$), while S-nitroso-N-acetyl-DL-penicillamine (SNAP) is a representative nitric oxide (NO) donor. In this study, we used patch clamp recording in spinal slices of rats to investigate the effects of $O_2^{\bullet-}$ and NO on the excitability of substantia gelatinosa (SG) neurons. We also used confocal scanning laser microscopy to measure XO- and SNAP-induced ROS and RNS production in live slices. We observed that the ROS level increased during the perfusion of xanthine and xanthine oxidase (X/XO) compound and SNAP after the loading of 2',7'-dichlorofluorescin diacetate ($H_2DCF-DA$), which is an indicator of intracellular ROS and RNS. Application of ROS donors such as X/XO, ${\beta}-nicotinamide$ adenine dinucleotide phosphate (NADPH), and 3-morpholinosydnomimine (SIN-1) induced a membrane depolarization and inward currents. SNAP, an RNS donor, also induced membrane depolarization and inward currents. X/XO-induced inward currents were significantly decreased by pretreatment with phenyl N-tert-butylnitrone (PBN; nonspecific ROS and RNS scavenger) and manganese(III) tetrakis(4-benzoic acid) porphyrin (MnTBAP; superoxide dismutase mimetics). Nitro-L-arginine methyl ester (NAME; NO scavenger) also slightly decreased X/XO-induced inward currents, suggesting that X/XO-induced responses can be involved in the generation of peroxynitrite ($ONOO^-$). Our data suggest that elevated ROS, especially $O_2^{\bullet-}$, NO and $ONOO^-$, in the spinal cord can increase the excitability of the SG neurons related to pain transmission.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.120-121
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• 2006

To investigate the ZnO thin films which are interested in the next generation of short wavelength LEDs and Lasers, the ZnO thin films were deposited by RF magnetron sputtering system. Al sputtering process of ZnO thin films substrate temperature, work pressure respectively is $100^{\circ}C$ and 15 mTorr, and the purity of target is ZnO 5N. The ZnO thin films were in-situ annealed at $600^{\circ}C$, $800^{\circ}C$ in $O_2$ atmosphere. Phosphorus (P) and arsenic (As) were diffused into ZnO thin films sputtered by RF magnetron sputtering system in ampoule tube which was below $5{\times}10^{-7}$ Torr. The dopant sources of phosphorus and arsenic were $Zn_3P_2$ and $ZnAS_2$. Those diffusion was perform at $650^{\circ}C$ during 3hr. We confirmed that p-type properties of ZnO thin films were concerned with dopant sources rather than diffusion temperature.

• Proceedings of the Optical Society of Korea Conference
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• 2001.02a
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• pp.54-55
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• 2001

Recently, there has been much interests in InGaN/GaN multiple-quantum-well (MQW) structures due to their applicability as optoelectronic devices such as light-emitting diodes (LEDs) and laser diodes [1]. Their ultrafast and physical properties are also of significant interests. Anomalously large acoustic phonon oscillations have been observed using ultrafast lasers in InGaN MQWs [2]. In this study, we have peformed femtosecond pump-probe experiments in the reflection geometry on 5 periods InGaN/GaN MQW LED structure with well width of 20$\AA$ and barrier width of 100$\AA$ at room temperature. (omitted)

• Applied Chemistry for Engineering
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• v.23 no.1
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• pp.105-111
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• 2012

Manganese (Mn) catalysts were generated using $CeO_2$ and $ZrO_2$supports synthesized by the supercritical hydrothermal method and two different Mn precursors, aimed at an application for a low-temperature selective catalytic reduction process. Manganese acetate (MA) and manganese nitrate (MA) were used as Mn precursors. Effects of the kind and the concentration of the Mn precursor used for catalyst generation on the NOx removal efficiency were investigated. The characteristics of the generated catalysts were analyzed using $N_2$ adsorption-desorption, thermo-gravimetric analysis, X-ray diffraction, and X-ray photoelectron spectroscopy. De-NOx experiments were carried out to measure NOx removal efficiencies of the catalysts. NOx removal efficiencies of the catalysts generated using MA were superior to those of the catalysts generated using MN at every temperature tested. Analyses of the catalyst characteristics indicated that the higher NOx removal efficiencies of the MA-derived catalysts stemmed from the higher oxygen mobility and the stronger interaction with support material of $Mn_2O_3$ produced from MA than those of $MnO_2$ produced from MN.

• The KIPS Transactions:PartA
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• v.10A no.6
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• pp.665-670
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• 2003

In the applications like automatic masks generation for semiconductor production, a drawing consists of lots of polygons that are partitioned into trapezoids. The addition/deletion of a polygon to/from the drawing is performed through geometric operations such as insertion, deletion, and search of trapezoids. Depending on partitioning algorithm being used, a polygon can be partitioned differently in terms of shape, size, and so on. So, It's necessary to invent some comparison algorithm of sets of trapezoids in which each set represents interested parts of a drawing. This comparison algorithm, for example, may be used to verify a software program handling geometric objects consisted of trapezoids. In this paper, given k sets of trapezoids in which each set forms the regions of interest of each drawing, we present how to compare the k sets to see if all k sets represent the same geometric scene. When each input set has the same number n of trapezoids, the algorithm proposed has O(2$^{k-2}$ $n^2$(log n＋k)) time complexity. It is also shown that the algorithm suggested has the same time complexity O( $n^2$ log n) as the sweeping-based algorithm when the number k(<< n) of input sets is small. Furthermore, the proposed algorithm can be kn times faster than the sweeping-based algorithm when all the trapezoids in the k input sets are almost the same.

• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.1
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• pp.21-25
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• 2017

In this study, we have fabricated Schottky barrier diodes (SBD) on single-crystal ${\beta}-Ga_2O_3$ semiconductor that has received much attention for use in next-generation power devices. The SBD had a Pt/Ti/Au Schottky contact on a $2{\mu}m$ Sn-doped low concentration N-type epitaxial layer. The fabricated device exhibited a breakdown voltage of > 180 V, a specific on-resistance of $1.26m{\Omega}{\cdot}cm^2$, and forward current densities of $77A/cm^2$ at 1 V and $473A/cm^2$ at 1.5 V, which proved the potential for use in power device fabrication.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.6 s.348
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• pp.18-22
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• 2006

The inspection of surface properties under n-octadecyltrichlorosilane treated $SiO_2$ film was carried out by current-voltage characteristic and the scanning electron microscope. The voltage at zero current in low electric field is the lowest at 0.3 % OTS treated $SiO_2$ film with hybrid type. $SiO_2$ films changed from inorganic to hybrid or organic properties according to the increase of OTS content. OTS treated $SiO_2$ films with hybrid properties decreased the leakage currents, and the grain size of pentacene deposited sample was also the most small at the hybrid properties. The perpendicular generation of pentacene molecular was related with the surface of insulators. The surface with hybrid properties decreased the grain size, but that with inorganic or organic properties increased the grain size.

• Proceedings of the Korean Information Science Society Conference
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• 2003.04a
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• pp.893-895
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• 2003

단백질간 구조 비교는 기능적 또는 구조적으로 연관된 단백질을 분류하거나 모티프(motif)를 찾는데 유용하게 사용되고 있다. 여러 가지 단백질간 구조 비교 방법 중에서 단백질 2차구조를 이용하는 방법은 실행속도의 측면에서 장점이 있다. 본 논문에서는 단백질 2차 구조와 그들 사이의 관계를 기반으로 한 단백질 구조 비교에서 사용될 유사성 그래프를 생성하는 방법을 기술하였다. 유사성 그래프는 단백질의 2차구조 사이의 관계를 노드로 하여 생성되는데, 그 시간복잡도가 O(n$^4$)이다. 이에 본 논문에서는 유사성 그래프의 생성을 효율적으로 할 수 있는 알고리즘을 개발하였다.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.392-392
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• 2011

현재의 태양전지에 사용되는 wafer는 원가저감을 위해 점점 얇아지고 있는 추세이다. 하지만 wafer가 얇아질수록 장파장 영역의 광자는 충분히 활용할 수 없게 된다. 대부분의 광자는 50um 지점에 도달하였을 때 그 역할을 다하고 소멸하게 되며, 특히 800nm 이상의 장파장에 대한 generation rate는 wafer 두께에 따라 급격한 차이를 보이게 된다. 따라서 장파장 영역의 광자를 효율적으로 사용할 뿐만 아니라 원가 저감을 위해 더욱 얇아지고 있는 추세의 wafer의 장파장 이용을 보상하기 위해서 TCO를 이용한 back-reflector의 역할은 가장 좋은 해결책이 될 것이다. 본 연구에서는 Macleod를 이용하여 ZnO, Al-doped ZnO, TiN, TiO2와 같은 다양한 TCO 물질에 대한 다양한 simulation을 실시 하여 reflectance 특성을 알아보았다. 상기 simulation결과로써 Al-doped ZnO가 가장 reflectance 특성이 좋게 나타났었으며 이를 이종접합 태양전지에 적용하여 광학적 및 전기적 특성 변화에 대해서 분석하였다.