• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.49 no.2
• /
• pp.15-22
• /
• 2012

A low power consumption scan driver using depletion-mode n-type InGaZnO thin-film transistors is proposed. The proposed circuit uses 2 clock signals and generates the non-overlap output signals without the additional masking signals and circuits. The power consumption of the proposed circuit is decreased by reducing the number of the clock signals and short circuit current. The simulation results show that the proposed circuit operates successfully when the threshold voltage of TFT is varied from -3.0V to 1.0V. The proposed scan driver consumes 4.89mW when the positive and negative supply voltage is 15V and -5V, respectively, and the operating frequency is 46KHz on the XGA resolution panel.

• JSTS:Journal of Semiconductor Technology and Science
• /
• v.17 no.2
• /
• pp.239-244
• /
• 2017

We experimentally investigate the physical mechanism for asymmetrical degradation in amorphous indium-gallium-zinc oxide (a-IGZO) thin-film transistors (TFTs) under simultaneous gate and drain bias stresses. The transfer curves exhibit an asymmetrical negative shift after the application of gate-to-source ($V_{GS}$) and drain-to-source ($V_{DS}$) bias stresses of ($V_{GS}=24V$, $V_{DS}=15.9V$) and ($V_{GS}=22V$, $V_{DS}=20V$), but the asymmetrical degradation is more significant after the bias stress ($V_{GS}$, $V_{DS}$) of (22 V, 20 V) nevertheless the vertical electric field at the source is higher under the bias stress ($V_{GS}$, $V_{DS}$) of (24 V, 15.9 V) than (22 V, 20 V). By using the modified external load resistance method, we extract the source contact resistance ($R_S$) and the voltage drop at $R_S$ ($V_{S,\;drop}$) in the fabricated a-IGZO TFT under both bias stresses. A significantly higher RS and $V_{S,\;drop}$ are extracted under the bias stress ($V_{GS}$, $V_{DS}$) of (22 V, 20V) than (24 V, 15.9 V), which implies that the high horizontal electric field across the source contact due to the large voltage drop at the reverse biased Schottky junction is the dominant physical mechanism causing the asymmetrical degradation of a-IGZO TFTs under simultaneous gate and drain bias stresses.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2016.02a
• /
• pp.267.1-267.1
• /
• 2016

본 연구에서는 nematic 액정의 종류 중 하나인 5CB (4-Cyano-4'-pentylbiphenyl) 물질을 박막 트랜지스터 (TFT)의 passivation 층으로 사용했을 때 그 전기적 특성향상을 확인하였다. RF-magnetron sputtering법으로 증착된 비정질 InGaZnO 박막을 활성층으로 사용한 TFT를 제작하여 그 활성층 위에 drop형식으로 passivation 하였다. 그 결과, drain current (I_DS)가 약 10배 정도 증가하고, linear region(V_D=0.5V)에서 mobility와 subthreshold slope(SS)이 각각 6.7에서 12.2, 0.3에서 0.2로 향상되는 것이 보였다. 이것은 gate bias가 인가되었을 때 freedericksz 전이를 통한 액정의 배향과 이때 형성된 dipole 형성에 의한 것으로 보이며, 이러한 LC의 배향은 편광현미경을 통하여 표면과 수직으로 배향한다는 사실을 확인 할 수 있었고 이 LC-passivation된 a-IGZO TFT의 전기적 특성의 향상에 대한 mechanism을 제시하였다. 그리고 배향한 LC가 가지는 dipole에 의해 bias stress 상황에서 독특한 electron trapping과 recovery의 증폭효과가 나타났다. V_G=+20V의 positive gate bias stress를 1000s동안 가했을 때, passivation되지 않은 a-IGZO TFT의 경우 +4V의 threshold voltage shift(${\Delta}V$_TH)가 발생되었고, 바로 -20V의 negative gate bias를 30s간 가해주었을 때 -2.5V의 ${\Delta}V$_TH가 발생하였다. 반면 LC-passivation된 a-IGZO TFT의 경우 각각 +5V와 -4V의 ${\Delta}V$_TH로 더 큰 변화를 가져왔다. 이러한 LC에 의한 electron trapping/recovery 증폭효과에 대한 model을 제시하였다.

• The Journal of the Korea Contents Association
• /
• v.9 no.12
• /
• pp.270-278
• /
• 2009

Most of previous studies on civil servants' stress factors and job satisfaction have been focused on low job satisfaction caused by stress from role relations and human relations. In case of fire officers, however, their stress is expected to be influenced by their unique job characteristics such as risk, urgency, stand-by, and shift. Thus, this study divided fire officers'stress factors into job-related factors (risk, urgency, stand-by, alternation) and role-related factors (role conflict, role ambiguity, role overload), and empirically analyzed how these factors affect their job satisfaction. According to the results of this study, fire officers' job characteristics and their roles in the organization had a significant effect on their job satisfaction. Particularly, among the job-related factors, urgency and stand-by had a positive effect on job satisfaction, and among role-related factors, role conflict and role overload had a negative effect on job satisfaction. In addition, fire officers' stress and job satisfaction were significantly different according to their job (fire fighting, rescue and first aid, fire administration, others), and according to their workplace (fire fighting headquarters, fire station, 119 safety center).

• Journal of Environmental Impact Assessment
• /
• v.2 no.2
• /
• pp.1-11
• /
• 1993

Most developing countries are experiencing rapid urbanization and the associated growth of industry and services. Cities are currently absorbing two-thirds of the total population in the developing world. Korea has about 85 percent of urban dwellers. World population will shift from being predominantly rural to predominantly urban around the turn of the century. Although cities play a key role in development process and make more than a proportionate contribution to national economic growth, especially cities are also the main catalysts of economic growth in developing countries, they can also be unhealthy, inefficient, and inequitable places to live. Most developing countries are increasingly unable to provide basic environmental infrastructure and services, whether in the megacities or in secondary urban centers. Of particular concern is the strain on natural resources brought by the increasing number of people, cars, and factories. They are generating ever greater amounts of urban wastes and emissions. They also exceed the capacity of regulatory authorities to control them and of nature to assimilate them. The environmental consequences are translated into direct negative impacts on human health, the quality of life, the productivity of the city, and the surrounding ecosystems. Environmental degradation threatens the long tenn availability and quality of natural resources critical to economic growth. Cities, with their higher and growing per capita energy use for domestic, industrial, and transport purpose also contribute a disproportionate share of the emission leading to global warming and acid rain. An important priority is to develop strategic approaches for managing the urban environment. The design of appropriate and lasting strategic responses requires first an understanding of the underlying causes of urban environmental deterioration, it is necessary that longer tenn objectives should be set for urban area to avoid irreversible ecological damage and to ensure lasting economic development. As a means to the preventive policies against the adverse effect, environmental impact assessment (EIA) serve to identify a project's possible environmental consequences early enough to allow their being taken into consideration in the decision making process for urban planning. This paper describes some considerations of EIA for urban planning-scoping, assessment process, measurement and prediction of impacts, pollution controls and supervision, and system planning for environmental preservation.

• Research in Community and Public Health Nursing
• /
• v.7 no.2
• /
• pp.400-409
• /
• 1996

To investigate industrial fatigue and low back pain, the questionaire survey for subjective symptoms of fatigue and low back pain was carried out among 591 male workers aged 20-55 employed in an automobile industry in Korea. Workers participated to this study were divided into low back pain group(LBP) and control group, according to the self-reports by written questionaires. The subjective sysptoms of fatigue comprised three groups of 10 items each, representing dullness and sleepiness(level of cerebral activation), difficulty in concentration(level of motivation) and bodily projection of fatigue. The resultant data were processed for $\chi^2-test$, t-test and a pearson's correlation coefficient to confirm the relationships. The results were as follows: 1. 30 items of fatigue subjective symptoms exeptone item, 'lack in perseverance', were directly associated with low back pain. 2. The percentage of fatigue complaint were sig nificantly higher in LBP group. 3. Of the 30 items of fatigue subjective symptoms, the highest percentage was accounted for 'eye strain'(27.9%), followed by 'whole body feels tired' and 'legs feel heavy'(22.9%), 'feel like lying'(21.4%), 'feel a pain in the low back'(18.7%), 'feel drowsy'(16.4%) and 'feel stiffness in the neck or the shoulders'(16.2%) in the order of sequence. 4. The average weighted score for the first group of fatigue items(dullness and sleepiness) was the largest among three groups and was followed by the second group(difficulty in concentration) and the third group(bodily projection of fatigue) in the order of sequence, suggesting the heavier shift work stress of the workers. 5. In the groups of the aged 30-40, work duration of 5-7yrs, heavy work amount and irregular work speed, significant high fatigue complaints were revealed in terms of eye strain, whole body feels tired, legs feel heavy, feel like lying, feel a pain in the low back and feel stiffness in the neck or the shoulders. 6. A significant negative correlations were shown between age, work duration and eleven subjective symptoms while positive reciprocal correlations were shown between eleven items with one another.

• Journal of Korean Ophthalmic Optics Society
• /
• v.3 no.1
• /
• pp.75-86
• /
• 1998

The purpose of this study is to evaluate the effects of continuing work on VDT(video display terminal), therefore this study examined visual fatigue, unaided visual acuity, refractive error, accommodation and horizontal phoria of 152 subjects who did two hour long VDT work. For the ocular symptoms, the greatest number was tired eyes accounting for 45.71%. In the visual symptoms, blurred vision was the hightest rate of 80.39% and in case of systemic symptoms shoulder pain was 33.33% marked top ranking. The average of near visual acuity decresed almost 10% from 0.47 to 0.42, but refractive error increased about 0.10D to the direction of myopic shift. The amplitude of accommodation decreased approximately 0.72D from 7.46D to 6.74D. Accommodation facility was delayed from 2.27 second to 2.50 second, the amplitude of positive relative accommodation was decreased from 4.76D to 4.16D and the amplitude of negative relative accommodation was decreased from 2.46D to 2.33D. The horizontal phoria shifted to the direction of esophoria from $1.82{\Delta}$ to $3.24{\Delta}$.

• Journal of Microbiology and Biotechnology
• /
• v.24 no.5
• /
• pp.648-660
• /
• 2014

Doenjang, a traditional Korean fermented soybean paste, is made by mixing and ripening meju with high salt brine (approximately 18%). Meju is a naturally fermented soybean block prepared by soaking, steaming, and molding soybean. To understand living bacterial community migration and the roles of bacteria in the manufacturing process of doenjang, the diversity of culturable bacteria in meju and doenjang was examined using media supplemented with NaCl, and some physiological activities of predominant isolates were determined. Bacilli were the major bacteria involved throughout the entire manufacturing process from meju to doenjang; some of these bacteria might be present as spores during the doenjang ripening process. Bacillus siamensis was the most populous species of the genus, and Bacillus licheniformis exhibited sufficient salt tolerance to maintain its growth during doenjang ripening. Enterococcus faecalis and Enterococcus faecium, the major lactic acid bacteria (LAB) identified in this study, did not continue to grow under high NaCl conditions in doenjang. Enterococci and certain species of coagulase-negative staphylococci (CNS) were the predominant acid-producing bacteria in meju fermentation, whereas Tetragenococcus halophilus and CNS were the major acid-producing bacteria in doenjang fermentation. We conclude that bacilli, LAB, and CNS may be the major bacterial groups involved in meju fermentation and that these bacterial communities undergo a shift toward salt-tolerant bacilli, CNS, and T. halophilus during the doenjang fermentation process.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.19 no.6
• /
• pp.19-30
• /
• 2016

The projection of climate-related range shift is critical information for conservation planning of Korean fir (Abies koreana E. H. Wilson). We first modeled the distribution of Korean fir under current climate condition using five single-model species distribution models (SDMs) and the pre-evaluation weighted ensemble method and then predicted the distributions under future climate conditions projected with HadGEM2-AO under four $CO_2$ emission scenarios, the Representative Concentration Pathways (RCP) 2.6, 4.5, 6.0 and 8.5. We also investigated the predictive uncertainty stemming from five individual algorithms and four $CO_2$ emission scenarios for better interpretation of SDM projections. Five individual algorithms were Generalized linear model (GLM), Generalized additive model (GAM), Multivariate adaptive regression splines (MARS), Generalized boosted model (GBM) and Random forest (RF). The results showed high variations of model performances among individual SDMs and the wide range of diverging predictions of future distributions of Korean fir in response to RCPs. The ensemble model presented the highest predictive accuracy (TSS = 0.97, AUC = 0.99) and predicted that the climate habitat suitability of Korean fir would increase under climate changes. Accordingly, the fir distribution could expand under future climate conditions. Increasing precipitation may account for increases in the distribution of Korean fir. Increasing precipitation compensates the negative effects of increasing temperature. However, the future distribution of Korean fir is also affected by other ecological processes, such as interactions with co-existing species, adaptation and dispersal limitation, and other environmental factors, such as extreme weather events and land-use changes. Therefore, we need further ecological research and to develop mechanistic and process-based distribution models for improving the predictive accuracy.

• Asian-Australasian Journal of Animal Sciences
• /
• v.18 no.3
• /
• pp.427-432
• /
• 2005

The purpose of this study was performed as model study using four animals to investigate the correction between the changes in Differential Scanning Calorimetry thermogram of muscle proteins during storage and meat freshness. M. longissimus dorsi of pork was obtained immediately after slaughter and chilled/stored at either $-2^{\circ}C$ or $25^{\circ}C$ for up to 96 h for analyses. DSC thermograms were determined and compared with pH values, ATP-related compounds, K-values, volatile basic nitrogen (VBN) levels, bacterial counts and electrophoretic behavior. Changes in pH, bacterial counts, VBN and K-values were associated with increased storage temperature and time. The levels of pH values, bacterial counts, VBN and K-values of pork samples stored at $25^{\circ}C$ were higher than those of the pork samples stored at $-2^{\circ}C$. ATP concentration decreased faster in samples stored at $25^{\circ}C$. Only IMP increased in samples stored at $-2^{\circ}C$, whereas the concentration of hypoxanthine and inosine increased in samples stored at $25^{\circ}C$. One exothermic peak and two endothermic peaks appeared on the thermograms of pork stored at either temperature. Lower transition temperature of myosin, sarcoplasmic protein and actin peaks were observed. The freshness parameters of K-value, VBN and hypoxanthine showed highly negative correlations (-0.742- -0.9980) to the changes in transition temperature. Therefore, the shift temperature on DSC thermogram can be used as an indicator of the freshness parameters of meat.