Effects of channel thickness variation on bias stress instability of InGaZnO thin-film transistors

Cho, E.N.,Kang, J.H.,Yun, I. Pergamon Press 2011 Microelectronics reliability Vol.51 No.9

Here, we report on the effects of channel (or active) layer thickness on the bias stress instability of InGaZnO (IGZO) thin-film transistors (TFTs). The investigation on variations of TFT characteristics under the electrical bias stress is very crucial for commercial applications. In this work, the initial electrical characteristics of the tested TFTs with different channel layer thicknesses (40, 50, and 60nm) are performed. Various gate bias (V<SUB>GS</SUB>) stresses (10, 20, and 30V) are then applied to the tested TFTs. For all V<SUB>GS</SUB> stresses with different channel layer thickness, the experimentally measured threshold voltage shift (ΔV<SUB>th</SUB>) as a function of stress time is precisely modeled with stretched-exponential function. It is indicated that the ΔV<SUB>th</SUB> is generated by carrier trapping but not defect creation. It is also observed that the ΔV<SUB>th</SUB> shows incremental behavior as the channel layer thickness increases. Thus, it is verified that the increase of total trap states (N<SUB>T</SUB>) and free carriers resulted in the increase of ΔV<SUB>th</SUB> as the channel layer thickness increases.

The microRNA miR-124 inhibits vascular smooth muscle cell proliferation by targeting S100 calcium-binding protein A4 (S100A4)

Choe, N.,Kwon, D. H.,Shin, S.,Kim, Y. S.,Kim, Y. K.,Kim, J.,Ahn, Y.,Eom, G. H.,Kook, H. Elsevier Science B.V., Amsterdam. 2017 FEBS letters Vol.591 No.7

<P>S100 calcium-binding protein A4 (S100A4) induces proliferation and migration of vascular smooth muscle cells (VSMCs). We aimed to find the microRNA regulating S100A4 expression. S100A4 transcripts are abruptly increased in the acute phase of carotid arterial injury 1 day later (at day 1) but gradually decreases at days 7 and 14. Bioinformatics analysis reveals that miR-124 targets S100A4. VSMC survival is attenuated by miR-124 mimic but increased by miR-124 inhibitor. miR-124 decreases immediately after carotid arterial injury but dramatically increases at days 7 and 14. miR-124 inhibitor-induced cell proliferation is blocked by S100A4 siRNA, whereas miR-124-induced cell death is recovered by S100A4. Our findings suggest that miR-124 is a novel regulator of VSMC proliferation and may play a role in the development of neointimal proliferation.</P>

Contact resistance dependent scaling-down behavior of amorphous InGaZnO thin-film transistors

Cho, E.N.,Kang, J.H.,Yun, I. Elsevier 2011 Current Applied Physics Vol.11 No.4

Here, we report scaling effects on the electrical properties of amorphous InGaZnO (a-IGZO) thin-film transistors (TFTs). The a-IGZO TFTs had same channel width/length ratio (W/L = 20), but different channel lengths (L = 20, 10, 5, and 2.5 μm). To examine the scaling-down behaviors, short-channel effects and contact resistance of the TFTs were investigated. As the channel length decreased, apparent shift of threshold voltage (V<SUB>th</SUB>) and degradation of subthreshold swing (S<SUB>SUB</SUB>) were shown. In addition, it is also found that the field-effect mobility (μ<SUB>FE</SUB>) was degraded as the channel length was decreased which was originated from contact resistance. Due to this contact resistance effect, drain current (I<SUB>DS</SUB>) was decreased for short-channel devices.

Use of Crown Feature Analysis to Separate the Two Pine Species in QuickBird imagery

Choen Kim 大韓遠隔探査學會 2008 大韓遠隔探査學會誌 Vol.24 No.3

Tree species-specific estimates with spacebome high-resolution imagery improve estimation of forest biomass which is needed to predict the long term planning for the sustainable forest management(SFM). This paper is a contribution to develop crown distinguishing coniferous species, Pinus densiflora and Pinus koraiensis, from QuickBird imagery. The proposed feature analysis derived from shape parameters and first and second-order statistical texture features of the same test area were compared for the two species separation and delineation. As expected, initial studies have shown that both formfactor and compactness shape parameters provided the successful differentiating method between the pine species within the compartment for single crown identification from spacebome high resolution imagery. Another result revealed that the selected texture parameters-the mean, variance, angular second moment(ASM)-in the infrared band image could produce good subset combination of texture features for representing detailed tree crown outline.

An Approach to the Spectral Signature Analysis and Supervised Classification for Forest Damages -An Assessment of Low Altitude Airborne MSS Data

Choen Kim 大韓遠隔探査學會 1991 大韓遠隔探査學會誌 Vol.7 No.2

This paper discusses the capabilities of airborne remotely sensed data to detect and classify forest damages. In this work the AMS (Aircraft Multiband Scanner) was used to obtain digital imagery at 300m altitude for forest damage inventory in the Black Forest of Germany. MSS (Multispectral Scanner) digital numbers were converted to spectral emittance and radiance values in 8 spectral bands from the visible to the thermal infrared and submitted to a maximum-likelihood classification for: (1) tree species; and, (2) damage classes. As expected, the results of MSS data with high spatial resolution 0.75m×0.75m enabled the detection and identification of single trees with different damages and were nearly equivalent to the truth information of ground checked data.

AUFNAHMESYSTEME UND IHRE SENSOREIGENSCHAFTEN BEI FORSTINVENTUREN DURCH FERNERKUNDUNG

Kim, Choen 國民大學校 山林科學硏究所 1990 山林科學 Vol.2 No.-

A Study on Spectral Mixture Analysis of North East China Land-Cover Based on Landsat ETM+Images

Kim, Choen 國民大學校 山林科學硏究所 2005 山林科學 Vol.17 No.-

매년 봄 가을 마다 우리나라에 피해주는 황사는 중국 북동지역의 사막화와 관련이 있다. 본 연구는 Landsat 화상(MSS, TM, ETM+)의 분광혼합분석 기법을 이용하여 토지피복의 사막화 현상을 규명하고자 한다. 기존의 분류방법 대신 분광혼합분석은 나지 및 녹색식생 그리고 수체로 구성된 혼합정도에 따라 각 화소를 세분화한 후 세 계급별, 즉 나지 및 녹색식생 그리고 수체에 대한 분할화상을 생성한다. 분할화상을 통한 결과는 첫째, 나지가 유의하게 증가하는 반면 녹색식생과 수체는 감소하였다. 둘째, 1988년대와 1990년간의 비교보다 1990년대와 2000년대간의 비교에서 사막화가 빠르게 진행되었다. 무엇보다 관개농업이 중국 북동지역의 사막화를 진행시켰다고 볼 수 있다. At every spring, Korean penisular is polluted by the sandy dust blown from China and it reaches a serious level with the annual increase of the blown sand. This study is focused on the change detection of the desertification area in China from 1980s to 2000s, by using multitemporal satellite images(Landsat MSS, TM, and ETM+) based on Spectral Mixture Analysis(SMA) to identify and classify the study area. Endmembers were selected bare soil, green vegetation(GV), and water body by using Minimum Noise Fraction(MNF). Endmembers were also used to generate fraction images from 1980s to 1990s and 1990s to 2000s respectively. From the analysis of multitemporal change detection for three periods, it is apparent that the area of bare soil increased significantly, with simultaneous decrease of GV, and water body. Desertification process from 1990s to 2000s is faster than the period from 1980s to 1990s. The multitemporal fraction images can be effectively used for change detection. Though there is no field survey dataset, SMA gives a reliable result in the change detection of desertification in north-eastern China.

Kinetic Evaluation of the Hypoxia Radiotracers [18F]FMISO and [ 18 F]FAZA in Dogs with Spontaneous Tumors Using Dynamic PET/CT Imaging

Sangkyung Choen 대한핵의학회 2023 핵의학 분자영상 Vol.57 No.1

Purpose We evaluated the kinetics of the hypoxia PET radiotracers, [18F]fluoromisonidazole ([18F]FMISO) and [18F]fluoroazomycin-arabinoside ([18F]FAZA), for tumor hypoxia detection and to assess the correlation of hypoxic kineticparameters with static imaging measures in canine spontaneous tumors. Methods Sixteen dogs with spontaneous tumors underwent a 150-min dynamic PET scan using either [18F]FMISO or [18F]FAZA. The maximum tumor-to-muscle ratio (TMRmax) > 1.4 on the last image frame was used as the standard thresholdto determine tumor hypoxia. The tumor time-activity curves were analyzed using irreversible and reversible two-tissuecompartment models and graphical methods. TMRmaxwas compared with radiotracer trapping rate (k3), influx rate (Ki), anddistribution volume (VT). Results Tumor hypoxia was detected in 7/8 tumors in the [18F]FMISO group and 4/8 tumors in the [18F]FAZA group. Allhypoxic tumors were detected at > 120 min with [18F]FMISO and at > 60 min with [18F]FAZA. [18F]FAZA showed betterfit with the reversible model. TMRmaxwas strongly correlated with the irreversible parameters (k3 and Ki) for [18F]FMISOat > 90 min and with the reversible parameter (VT) for [18F]FAZA at > 120 min. Conclusions Our results showed that [18F]FAZA provided a promising alternative radiotracer to [18F]FMISO with detectingthe presence of tumor hypoxia at an earlier time (60 min), consistent with its favorable faster kinetics. The strong correlationbetween TMRmaxover the 90–150 min and 120–150 min timeframes with [18F]FMISO and [18F]FAZA, respectively, withkinetic parameters associated with tumor hypoxia for each radiotracer, suggests that a static scan measurement (TMRmax) isa good alternative to quantify tumor hypoxia.

고급 사냥감 밀도에 의한 수렵관리 : 김천

Kim, Choen 國民大學校 山林科學硏究所 1994 山林科學 Vol.6 No.-

Wildlife management plays as important roles in multipurpose forest management as sustained yield method emphasizes ecosystem, which is not closed but has both biotic and abiotic components interacting with surrounding systems. Recently hunting is very useful for maintaining biological control rather than as means of sport and recreation. This literature study shows the necessity of hunting stock of nobler beast of venery and higher game birds, hunting care and protection of game, and collecting population data which include the number of individuals.

An Approach to the Spectral Signature Analysis and Supervised Classification for Forest Damages - An Assessment of Low Altitued Airborne MSS Data -

Kim, Choen The Korean Society of Remote Sensing 1991 大韓遠隔探査學會誌 Vol.7 No.2

This paper discusses the capabilities of airborne remotely sensed data to detect and classify forest damades. In this work the AMS (Aircraft Multiband Scanner) was used to obtain digital imagery at 300m altitude for forest damage inventory in the Black Forest of Germany. MSS(Multispectral Scanner) digital numbers were converted to spectral emittance and radiance values in 8 spectral bands from the visible to the thermal infrared and submitted to a maximum-likelihood classification for : (1) tree species ; and. (2) damage classes. As expected, the resulted, the results of MSS data with high spatial resolution 0.75m$\times$0.75m enabled the detection and identification of single trees with different damages and were nearly equivalent to the truth information of ground checked data.