• Journal of Information Display
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• v.12 no.1
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• pp.47-50
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• 2011

Highly stable amorphous indium.gallium.zinc-oxide (a-IGZO) thin-film transistors (TFTs) were fabricated with an etchstopper and via-hole structure. The TFTs exhibited 40 $cm^2$/V s field-effect mobility and a 0.21 V/dec gate voltage swing. Gate-bias stress induced a negligible threshold voltage shift (${\Delta}V_{th}$) at room temperature. The excellent stability is attribute to the via-hole and etch-stopper structure, in which, the source/drain metal contacts the active a-IGZO layer through two via holes (one on each side), resulting in minimized damage to the a-IGZO layer during the plasma etching of the source/drain metal. The comparison of the effects of the DC and AC stress on the performance of the TFTs at $60^{\circ}C$ showed that there was a smaller ${\Delta}V_{th}$ in the AC stress compared with the DC stress for the same effective stress time, indicating that the trappin of the carriers at the active layer-gate insulator interface was the dominant degradation mechanism.

• Journal of the Korean Vacuum Society
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• v.12 no.4
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• pp.239-250
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• 2003

The reliability degradation phenomena in the SiGe hetero-junction bipolar transistor (HBT) are investigated in this review. In the case of the SiGe HBT the decrease of the current gain, the degradation of the AC characteristics, and the offset voltage are frequently observed, which are attributed to the emitter-base reverse bias voltage stress, the transient enhanced diffusion, and the deterioration of the base-collector junction due to the fluctuation in fabrication process, respectively. The reverse-bias stress on the emitter-base junction causes the recombination current to rise, increasing the base current and degrading the current gain, because hot carriers formed by the high electric field at the junction periphery generate charged traps at the silicon-oxide interface and within the oxide region. Because of the enhanced diffusion of the dopants in the intrinsic base induced by the extrinsic base implantation, the shorter distance between the emitter-base junction and the extrinsic base than a critical measure leads to the reduction of the cut-off frequency ($f_t$) of the device. If the energy of the extrinsic base implantation is insufficient, the turn-on voltage of the collector-base junction becomes low, in the result, the offset voltage appears on the current-voltage curve.

• The Journal of Korean Physical Therapy
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• v.22 no.2
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• pp.69-75
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• 2010

Purpose: The purpose of this study was to investigate the relationship between subjective quality of life and job stress with regard to general characteristics and health characteristics of physical therapists (PTs) and occupational therapists (OTs). Methods: The study involved administering questionnaires to 93 PTs and OTs who worked in urban medical institutions between November 2009 and October 2009. A questionnaire (KvSBQOL) developed by Dunbar and colleagues and translated into Korean version by Yoon et al was used for measuring subjective quality of life. A questionnaire developed by Kim was used for measuring job stress. Results: Among PTs and OTs, the mean quality of life score was 3.10 points and the mean level of job stress was 3.42. Female PTs and OTs had significantly greater levels of job stress. Those PTs and OTs in the 'Lowest pay' group and in the 'Associated Degree' group reported the lowest quality of life. Those in the 'Very healthy' group of PTs and OTs had significantly lower job stress than the other groups. The group with the highest job stress had the lowest quality of life. A limitation of this study was that all data was self-reported and subject to associated bias. Conclusion: To prevent loss of business services by PTs and OTs, it is important to know how job stress affects quality of life. Our findings suggest that a reduction in job stress can improve quality of life among PTs and OTs.

• Journal of the Korean Vacuum Society
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• v.13 no.4
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• pp.157-163
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• 2004

Dependence of residual compressive stress of diamond-like carbon (DLC) films on relative humidity was investigated. Polymeric, graphitic and diamond-like carbon films were prepared by r.f.-PACVD using methane or benzene with the negative self bias voltage of the substrate ranging from -100 to -800 V. In-situ measurements of the residual stress were carried out in an environment chamber where the relative humidity was varied from 10％ to 90％. In dense DLC film of high residual compressive stress and hardness, we could not observe any change in the residual compressive stress with relative humidity. However, in the cases of graphitic and polymeric DLC films, abrupt change in the residual stress occurred by changing the relative humidity. The quantity of the stress change was inversely proportional to the film thickness, which means that the stress change with humidity is not due to the penetration of the water molecule into the film structure, but due to surface interaction between water molecules and film surface.

• Journal of Industrial Convergence
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• v.19 no.1
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• pp.87-97
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• 2021

This study aimed to systematically review the literature on the stress reduction of meaning-centered therapy (MCT) studies in Korea and to identify the characteristics of MCT for stress reduction. MCT studies aimed at reducing stress symptoms were searched among peer reviewed journal articles and unpublished dissertations until April, 2020. Two independent researchers assessed the risk of bias and the quality of the report using Scottish Intercollegiate Guidelines Network criteria. As a result of searching with 7 databases, 7 studies were finally selected. Seven MCTs were for all age groups, and 5 studies reported MCT was effective in reducing stress symptoms. Both single and combined type interventions were effective in reducing stress symptom, Researchers used the combined MCT more than single MCT program. The study with no significant effect was related to school test stress. There is a need to develop MCTs suitable for school-age youth with test stress in the future.

• Journal of Korean Society for Quality Management
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• v.9 no.1
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• pp.3-11
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• 1981

A stress-strength model is formulated for s of k systems consisting of identical components. We consider minimum variance unbiased (MVU) estimation of system reliability for data consisting of a random sample from the stress distribution and one from the strength distribution when the two distirubtions are Weibull with unknown scale parameters and same known shape parameter. The asymptotic distribution of MVU estimate of system reliability in the model is obtained by using the standard asymptotic properties of the maximum likelihood estimate of system reliability and establishing their equivalence. Uniformly most accurate unbiased confidence intervals are also obtained for system reliability. Empirical comparison of the two estimates for small samples is studies by Monte Carlo simulation.

• The Journal of Korean Obstetrics and Gynecology
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• v.33 no.4
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• pp.1-22
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• 2020

Objectives: The purpose of this review is to evaluate the efficacy of moxibustion for stress urinary incontinence (SUI) in women. Methods: For relevant randomized controlled trials (RCTs), we searched the following databases from their inception to September 1, 2020: The Cochrane Library, PubMed, EMBASE, Chinese National Knowledge Infrastructure Database (CNKI), Koreanstudies Information Service System (KISS), Research Information Sharing Service (RISS), and National Digital Science Library (NDSL). The key search terms were 'stress urinary incontinence' and 'moxibustion'. Data extraction and assessment of risk of bias were conducted by two authors independently. Results: A total of 11 RCTs were finally included in this systematic review. In all studies, moxibustion treatment was applied as an adjuvant therapy to the conventional treatment, and the most common conventional treatment was pelvic floor muscle training (PFMT). The treatment group (conventional treatment plus moxibustion) showed statistically more significant effect than the control group (conventional treatment only) in various evaluation indicators including urinary incontinence frequency, 1 hour urine pad test, quality of life, the clinical efficacy rate, and pelvic muscle strength. Conclusions: In this study, we investigated the efficacy of moxibustion as an adjuvant therapy for female SUI patients. Further studies are needed to supplement the safety of moxibustion and the evaluation of moxibustion dose.

• 한국정보디스플레이학회:학술대회논문집
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• 2002.08a
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• pp.515-518
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• 2002

In this paper, we demonstrate the impact of oxide interface-state on low temperature poly-Si TFTs. The TFTs with interface-state exhibit poor performance and serious degradation under hot carrier and gate bias stress. Our results indicate that the worse oxide integrity cause initial characteristic shift and device instability.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.135-135
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• 1999

It is well known that Raman spectroscopy is powerful tool in analysis of sp3/sp3 bonding fraction in diamond-like carbon(DLC) films. Raman spectra of DLC film is composed of D-peak centered at 1350cm-1 and G-peak centered at 1530cm-1. The sp3/sp3 fraction is qualitatively acquired by deconvolution method. However, in case of DLC film, it is generally observed that G-peak position shifts toward low wavenumber as th sp3 fraction increases. However, opposite results were frequently observed in ta-C films. ta-C film has much higher residual compressive stress due to its high sp3 fraction compared to the DLC films deposited by CVD method. Effect of residual stress on G-peak position is most recommendable parameter in Raman analysis of ta-C, due to its smallest fitting error among many parameters acquired by peak deconvolution of symmetric spectra. In current study, the effect of residual stress on Raman spectra was quantitatively evaluated by free-hang method. ta-C films of different residual stress were deposited on Si-wafer by modifying DC-bias voltage during deposition. The variation of the G-peak position along the etching depth were observed in the free-hangs of 20~30${\mu}{\textrm}{m}$ etching depth. Mathematical result based on Airy stress function, was compared with experimental results. The more reliable analysis excluding stress-induced shift was possible by elimination of the Raman shift due to residual compressiove stress.

• Healthcare Informatics Research
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• v.24 no.4
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• pp.381-386
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• 2018

Objectives: This study aimed to describe the process of utilizing a mobile application for ecological momentary assessment (EMA) to collect data on stress and mood in daily life setting. Methods: A mobile application for the Android operating system was developed and installed with a set of questions regarding momentary mood and stress into a smartphone of a participant. The application sets alarms at semi-random intervals in 60-minute blocks, four times a day for 7 days. After obtaining all momentary affect and stress, the questions to assess the usability of the mobile EMA application were also administered. Results: The data were collected from 97 police officers working in Gyeonggi Province of South Korea. The mean completion rate was 60.0% ranging from 3.5% to 100%. The means of positive and negative affect were 18.34 of 28 and 19.09 of 63. The mean stress was 17.92 of 40. Participants responded that the mobile application correctly measured their affect ($4.34{\pm}0.83$) and stress ($4.48{\pm}0.62$) of 5-point Likert scale. Conclusions: Our study investigated the process of utilizing a mobile application to assess momentary affect and stress at repeated times. We found challenges regarding adherence to the research protocol, such as completion and delay of answering after alarm notification. Despite this inherent issue of adherence to the research protocol, the EMA still has advantages of reducing recall bias and assessing the actual moment of interest at multiple time points that improves ecological validity.