• Transactions on Electrical and Electronic Materials
• /
• v.16 no.3
• /
• pp.124-129
• /
• 2015

Organic electronics are the domain in which the components and circuits are made of organic materials. This new electronics help to realize electronic and optoelectronic devices on flexible substrates. In recent years, organic materials have replaced conventional semiconductors in many electronic components such as, organic light-emitting diodes (OLEDs), organic field-effect transistors (OFETs) and organic photovoltaic (OPVs). It is well known that organic light emitting diodes (OLEDs) have many advantages in comparison with inorganic light-emitting diodes LEDs. These advantages include the low price of manufacturing, large area of electroluminescent display, uniform emission and lower the requirement for power. The aim of this paper is to model polymer LEDs and OLEDs made with small molecules for studying the electrical and optical characteristics. The purpose of this modeling process is, to obtain information about the running of OLEDs, as well as, the injection and charge transport mechanisms. The first simulation structure used in this paper is a mono layer device; typically consisting of the poly (2-methoxy-5(2'-ethyl) hexoxy-phenylenevinylene) (MEH-PPV) polymer sandwiched between an anode with a high work function, usually an indium tin oxide (ITO) substrate, and a cathode with a relatively low work function, such as Al. Electrons will then be injected from the cathode and recombine with electron holes injected from the anode, emitting light. In the second structure, we replaced MEH-PPV by tris (8-hydroxyquinolinato) aluminum (Alq₃). This simulation uses, the Poole-Frenkel -like mobility model and the Langevin bimolecular recombination model as the transport and recombination mechanism. These models are enabled in ATLAS- SILVACO. To optimize OLED performance, we propose to change some parameters in this device, such as doping concentration, thickness and electrode materials.

• Journal of Ginseng Research
• /
• v.46 no.5
• /
• pp.636-645
• /
• 2022

Background: Ginsenoside Rg3 and gemcitabine have mutual enhancing antitumor effects. However, the underlying mechanisms are not clear. This study explored the influence of ginsenoside Rg3 on Zinc finger protein 91 homolog (ZFP91) expression in pancreatic adenocarcinoma (PAAD) and their regulatory mechanisms on gemcitabine sensitivity. Methods: RNA-seq and survival data from The Cancer Genome Atlas (TCGA)-PAAD and Genotype-Tissue Expression (GTEx) were used for in-silicon analysis. PANC-1, BxPC-3, and PANC-1 gemcitabine-resistant (PANC-1/GR) cells were used for in vitro analysis. PANC-1 derived tumor xenograft nude mice model was used to assess the influence of ginsenoside Rg3 and ZFP91 on tumor growth in vivo. Results: Ginsenoside Rg3 reduced ZFP91 expression in PAAD cells in a dose-dependent manner. ZFP91 upregulation was associated with significantly shorter survival of patients with PAAD. ZFP91 overexpression induced gemcitabine resistance, which was partly conquered by ginsenoside Rg3 treatment. ZFP91 depletion sensitized PANC-1/GR cells to gemcitabine treatment. ZFP91 interacted with Testis-Specific Y-Encoded-Like Protein 2 (TSPYL2), induced its poly-ubiquitination, and promoted proteasomal degradation. Ginsenoside Rg3 treatment weakened ZFP91-induced TSPYL2 poly-ubiquitination and degradation. Enforced TSPYL2 expression increased gemcitabine sensitivity of PAAD cells and partly reversed induced gemcitabine resistance in PANC-1/GR cells. Conclusion: Ginsenoside Rg3 can increase gemcitabine sensitivity of pancreatic adenocarcinoma at least via reducing ZFP91 mediated TSPYL2 destabilization.

• Journal of the Korean Geographical Society
• /
• v.43 no.1
• /
• pp.87-103
• /
• 2008

The geographical name is an expression of human knowledge about living conditions and a basic tool for understanding about regional cultures and history as a result of spatiotemporal changes. This study aims to understand the historical and regional characteristics by analyzing the frequency and distribution of geographical names of 1:50,000 topographic map in the early 20th century and materializing on electronic cultural atlas. The result of this analysis is as follows. First, the aspect of distributed geographical names on the Korean Peninsula reflects a general trait of the country's natural and human environment included geographical features, population, arable land, the number of counties and villages, and functions of administration and military, etc. Second, through the frequency and weight of their names, the analysis shows not only the change of native names, but also the country's phase of the time by Japanese colonial policies such as exploitation of resources, the construction of railroads, and a desire to control of the border area with Manchuria. In addition, the study identified regional characteristics and differences in environmental perception and preferences, and naming basis and forms by the comparative analysis of each type of geographical names associated with village and ridge such as 'Chi' 'Ryung' 'Duk' 'Hang' 'Pyeong' 'Gok'. In particular, those characteristics were largely affected from environmental difference of each area.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2008.06a
• /
• pp.133-133
• /
• 2008

Recently, as the down-scailing of field-effect transistor devices continues, Schottky-barrier field-effect transistors (SB-FETs) have attracted much attention as an alternative to conventional MOSFETs. SB-FETs have advantages over conventional devices, such as low parasitic source/drain resistance due to their metallic characteristics, low temperature processing for source/drain formation and physical scalability to the sub-10nm regime. The good scalability of SB-FETs is due to their metallic characteristics of source/drain, which leads to the low resistance and the atomically abrupt junctions at metal (silicide)-silicon interface. Nevertheless, some reports show that SB-FETs suffer from short channel effect (SCE) that would cause severe problems in the sub 20nm regime.[Ouyang et al. IEEE Trans. Electron Devices 53, 8, 1732 (2007)] Because source/drain barriers induce a depletion region, it is possible that the barriers are overlapped in short channel SB-FETs. In order to analyze the SCE of SB-FETs, we carried out systematic studies on the Schottky barrier overlapping in short channel SB-FETs using a SILVACO ATLAS numerical simulator. We have investigated the variation of surface channel band profiles depending on the doping, barrier height and the effective channel length using 2D simulation. Because the source/drain depletion regions start to be overlapped each other in the condition of the $L_{ch}$~80nm with $N_D{\sim}1\times10^{18}cm^{-3}$ and $\phi_{Bn}$ $\approx$ 0.6eV, the band profile varies as the decrease of effective channel length $L_{ch}$. With the $L_{ch}$~80nm as a starting point, the built-in potential of source/drain schottky contacts gradually decreases as the decrease of $L_{ch}$, then the conduction and valence band edges are consequently flattened at $L_{ch}$~5nm. These results may allow us to understand the performance related interdependent parameters in nanoscale SB-FETs such as channel length, the barrier height and channel doping.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2008.11a
• /
• pp.76-76
• /
• 2008

갈륨-질화물(GaN) 기반의 고속전자이동도 트랜지스터(high electron mobility transistor, HEMT)는 최근 마이크로파 또는 밀리미터파 등의 고주파 대역의 통신시스템에 널리 사용되는 전자소자이자, 차세대 고주파용 전력 소자로 각광받고 있다. AlGaN/GaN HEMT에서 AlGaN층과 GaN층의 이종접합 구조(heterostructure)는 두 물질 간의 큰 전도대의 불연속성으로 인해 발생하는 이차원 전자가스(two-dimensional electron gas, 2DEG) 채널을 이용하여 높은 전자이동도, 높은 항복전압 및 우수한 고출력 특성을 얻는 것이 가능하다. 그러나 이린 이론적인 우수한 특성에도 불구하고 실제 AlGaN/GaN HEMT 소자에서는 AlGaN 표면과 AlGaN과 GaN 층 사이 접합면, AlGaN과 GaN 벌크층에 존재하는 트랩의 영향으로 이론보다 낮은 DC 출력 특성을 갖는다. 본 논문에서는 표면, 접합면, 벌크 층에 존재하는 트랩들을 각각의 존재 유무에 따라 시뮬레이션 함으로써 각각의 트랩이 DC 특성에 미치는 영향에 대해서 알아본다. 또한 소스와 게이트, 드레인과 게이트간의 거리에 따라 표면 트랩에 따른 영향과 AlGaN층과 GaN 층의 두께를 변화시켜가면서 각 층의 두께에 따라 벌크 트랩이 DC 특성에 미치는 영향을 알아보았다. 본 논문에서 트랩에 따른 특성의 파악을 위해서 $ATLAS^{TM}$를 이용하여 전산모사 하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2008.06a
• /
• pp.151-151
• /
• 2008

갈륨-질화물(GaN) 기반의 고속전자이동도 트랜지스터(high electron mobility transistor, HEMT)는 마이크로파 또는 밀리미터파 등과 같은 고주파 대역의 통신시스템에 널리 사용되는 전자소자로 각광받고 있다. GaN HEMT는 AlGaN/GaN 또는 AlGaN/InGaN/GaN 등과 같은 이종접합구조(heterostructure)로부터 발생하는 이차원 전자가스(two-dimensional electron gas, 2DEG) 채널을 이용하여 캐리어 구속효과(carrier confinement) 및 이동도의 향상이 가능하다. 또한 높은 2DEG 채널의 면밀도(sheet concentration) 와 전자의 포화 속도(saturation velocity)를 바탕으로 고출력 동작이 가능하여 차세대 이동통신용 전력 증폭기로 주목받고 있다. 그러나 이론적으로 우수한 특성과 달리, 실제 소자에서는 epi 성장시의 결함이나 전위, 표면 상태에 따른 2DEG 감소 등의 영향으로 이론보다 높은 누설 전류와 낮은 항복 전압 특성을 가진다. 특히, 기존의 GaN HEMT 구조에서는 Drain-Side Gate Edge에서의 전계 집중이 항복 전압 특성에 미치는 영향이 크다. 본 논문에서는 이러한 문제를 해결하기 위해 Trapezoidal Gate구조를 이용하여 Drain 방향의 Gate Edge가 완만히 변하는 구조를 제안하였다. 이를 위해 $ATLAS^{TM}$ 전산모사 프로그램을 이용하여 Trapezoidal Gate 구조를 구현하여 형태에 따른 전류-전압 특성 및 소자의 스위칭 특성 및 Gate 아래 채널층에 형성되는 Electric Field의 분산을 조사하고, 이를 바탕으로 고속 동작 및 높은 항복 전압을 갖는 AlGaN/GaN HEMT의 최적화된 구조를 제안하였다. 새로운 구조의 Gate를 적용한 AlGaN/GaN HEMT는 Gate edge에서의 전계를 분산시켜 피크 값이 감소되는 것을 확인하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2008.06a
• /
• pp.131-131
• /
• 2008

Silicon carbide (SiC) has attracted significant attention for high frequency, high temperature and high power devices due to its superior properties such as the large band gap, high breakdown electric field, high saturation velocity and high thermal conductivity. We performed Al ion implantation processes on n-type 4H-SiC substrate using a SILVACO ATHENA numerical simulator. The ion implantation model used a Monte-Carlo method. We studied the effect of channeling by Al implantation simulation in both 0 off-axis and 8 off-axis n-type 4H-SiC substrate. We have investigated the Al distribution in 4H-SiC through the variation of the implantation energies and the corresponding ratio of the doses. The implantation energies controlled 40, 60, 80, 100 and 120 keV and the implantation doses varied from $2\times10^{14}$ to $1\times10^{15}cm^{-2}$. In the simulation results, the Al ion distribution was deeper as increasing implantation energy and the doping level increased as increasing implantation doses. After the post-implantation annealing, the electrical properties of Al-implanted p-n junction diode were investigated by SILV ACO ATLAS numerical simulator.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• v.9 no.1
• /
• pp.981-984
• /
• 2005

This study is to realize its threshold voltage shift after programming operation in charge trap type SONOS memory by simulation. SONOS devices are charge trap type nonvolatile memory devices in which charge storage takes place in traps in the nitride-blocking oxide interface and the nitride layer. For simulation of their threshold voltage as a function of the memory states, traps in the nitride layer have to be defined. However, trap models in the nitride layer are not developed in commercial simulator. So, we propose a new method that can simulate their threshold voltage shift by an amount of charges induced to the electrodes as a function of a programming voltages and times as define two electrodes in the tunnel oxide-nitride interface and the nitride-blocking oxide interface of SONOS structures.

• 한국HCI학회:학술대회논문집
• /
• 2009.02a
• /
• pp.1316-1320
• /
• 2009

Since most information is readily available these days, the shear volume of the information simply overwhelms people, rather than helping them as a form of useful knowledge. Thus, the quantity of information someone owns doesn't possess much significance. The possibility to well-utilize the quality information is much more important these days. Electronic culture map service is being provided these days to introduce various cultural information to people around the world. But its service is limited to 'visualization, collection, and integration of the data.' Which means, electronic culture maps are no more than a simple data collector. The main purpose of this thesis is to develop a new kind of knowledge/information service method which overcomes these shortcomings. To achieve this goal, at first, the thesis will take a close look at the characteristics and functions of Chosunjock culture maps, and then, it will clarify the definition of data, information, knowledge of cultural resources. And secondly, nd thirdly, the thesis will look up the Wayfinding contents, User Experience Design, User Context, and Organic design for knowledge/information service. And lastly, the thesis will develop the knowledge/information service, specifically based on Chosunjock cultural resources.

• BMB Reports
• /
• v.38 no.6
• /
• pp.739-747
• /
• 2005

Full-length cDNA sequences of four novel SPATA4 genes in chimpanzee, cow, chicken and ascidian were identified by bioinformatic analysis using mouse or human SPATA4 cDNA fragment as electronic probe. All these genes have 6 exons and have similar protein molecular weight and do not localize in sex chromosome. The mouse SPATA4 sequence is identified as significantly changed in cryptorchidism, which shares no significant homology with any known protein in swissprot databases except for the homologous genes in various vertebrates. Our searching results showed that all SPATA4 proteins have a putative conserved domain DUF1042. The percentages of putative SPATA4 protein sequence identity ranging from 30% to 99%. The high similarity was also found in 1 kb promoter regions of human, mouse and rat SPATA4 gene. The similarities of the sequences upstream of SPATA4 promoter also have a high proportion. The results of searching SymAtlas (http://symatlas.gnf.org/SymAtlas/) showed that human SPATA4 has a high expression in testis, especially in testis interstitial, leydig cell, seminiferous tubule and germ cell. Mouse SPATA4 was observed exclusively in adult mouse testis and almost no signal was detected in other tissues. The pI values of the protein are negative, ranging from 9.44 to 10.15. The subcellular location of the protein is usually in the nucleus. And the signal peptide possibilities for SPATA4 are always zero. Using the SNPs data in NCBI, we found 33 SNPs in human SPATA4 gene genomic DNA region, with the distribution of 29 SNPs in the introns. CpG island searching gives the data about CpG island, which shows that the regions of the CpG island have a high similarity with each other, though the length of the CpG island is different from each other.This research is a fundamental work in the fields of the bioinformational analysis, and also put forward a new way for the bioinformatic analysis of other genes.