• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.5
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• pp.1592-1596
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• 2010

According to the increase of the channel length with fixed width/length, characteristic curves of drain current as a function of gate bias voltage of indium gallium zinc oxide (IGZO) thin-film transistors moved to a positive direction of gate voltage, and field-effect mobility decreased. In case of fixed length and width of channel, field-effect mobility was lower and subthreshold slope was larger when drain bias voltage was higher. Due to large work function of IGZO, band bending at the junction region between IGZO channel and source/drain electrodes was expected to be in opposite direction to that between silicon and metal electrodes; this could explain the above results.

• Journal of the Semiconductor & Display Technology
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• v.13 no.3
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• pp.39-43
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• 2014

The effect of electrode charging on the ion energy distribution (IED) was investigated in the dual-frequency capacitively coupled plasma source which was powered of 100 MHz RF at the top electrode and 400 kHz bias on the bottom electrode. The charging property was analyzed with the distortion of the measured current and voltage waveforms. The capacitance and the resistance of electrode sheath can change the property of ion and electron charging on the electrode so it is sensitive to the plasma density which is controlled by the main power. The ion energy distribution was estimated by equivalent circuit model, being compared with the measured distribution obtained from the ion energy analyzer. Results show that the low frequency bias power changes effectively the low energy population of ion in the energy distribution.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2013.05a
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• pp.154-154
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• 2013

In this work, we investigated the characteristics and the effects of light on the negative gate bias stress stability (NBS) in high mobility polycrystalline IGO TFTs. IGO TFT showed a high drain current on/off ratio of ${\sim}10^9$, a field-effect mobility of $114cm^2/Vs$, a threshold voltage of -4V, and a subthresholdslpe(SS) of 0.28V/decade from log($I_{DS}$) vs $V_{GS}$. IGO TFTs showed large negative $V_{TH}$ shift(17V) at light power of $5mW/cm^2$ with negative gate bias stress of -10V for 10000seconds, at a fixed drain voltage ($V_{DS}$) of 0.5V.

• The Journal of Asian Finance, Economics and Business
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• v.9 no.2
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• pp.347-353
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• 2022

Using the Heckman two-step procedure, this study investigates the relationship between management accounting implementation and firm effectiveness. The research data for this study was acquired from 450 publicly traded companies in Vietnam; however, the final sample only includes 304 responses containing useful information. The reliability analysis was used to evaluate the acquired data to examine the qualities of constructs and the dimensions that make them up. Then, the Heckman two-step technique was performed to analyze the causal connection from the acceptance of management accounting to firm effectiveness allowing for the effect of environmental uncertainty and organizational characteristics on the likelihood of adopting management accounting. The empirical findings show that management accounting acceptance determines firm effectiveness; however, the research model on the relationship between management accounting adoption and firm effectiveness has a sample selection bias. The main conclusions of this study are that there is a difference in the effects of management accounting adoption on business effectiveness when sample selection bias is not taken into consideration. When potential sample selection bias is taken into account by integrating environmental uncertainty and organizational characteristics in the research model, the effect of adopting management accounting on company effectiveness becomes minor.

• Journal of Korean Society for Atmospheric Environment
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• v.33 no.1
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• pp.11-18
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• 2017

The performance of a modeling system consisting of WRF model v3.3 and CMAQ model v4.7.1 for forecasting $PM_{2.5}$ concentrations were evaluated during the period May 2012 through December 2014. Twenty-four hour averages of $PM_{2.5}$ and its major components obtained through filter sampling at the Bulgwang intensive measurement station were used for comparison. The mean predicted $PM_{2.5}$ concentration over the entire period was 68% of the mean measured value. Predicted concentrations for major components were underestimated except for $NO_3{^-}$. The model performance for $PM_{2.5}$ generally tended to degrade with increasing the concentration level. However, the mean fractional bias (MFB) for high concentration above the $80^{th}$ percentile fell within the criteria, the level of accuracy acceptable for standard model applications. Among three bias correction methods, the ratio adjustment was generally most effective in improving the performance. Albeit for limited test conditions, this analysis demonstrated that the effects of bias correction were larger when using the data with a larger bias of predicted values from measurement values.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.252-253
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• 2011

ZnO-based thin film transistors (TFTs) are of great interest for application in next generation flat panel displays. Most research has been based on amorphous indium-gallium-zinc-oxide (IGZO) TFTs, rather than single binary oxides, such as ZnO, due to the reproducibility, uniformity, and surface smoothness of the IGZO active channel layer. However, recently, intrinsic ZnO-TFTs have been investigated, and TFT- arrayss have been demonstrated as prototypes of flat-panel displays and electronic circuits. However, ZnO thin films have some significant problems for application as an active channel layer of TFTs; it was easy to change the electrical properties of the i-ZnO thin films under external conditions. The variable electrical properties lead to unstable TFTs device characteristics under bias stress and/or temperature. In order to obtain higher performance and more stable ZnO-based TFTs, HZO thin film was used as an active channel layer. It was expected that HZO-TFTs would have more stable electrical characteristics under gate bias stress conditions because the binding energy of Hf-O is greater than that of Zn-O. For deposition of HZO thin films, Hf would be substituted with Zn, and then Hf could be suppressed to generate oxygen vacancies. In this study, the fabrication of the oxide-based TFTs with HZO active channel layer was reported with excellent stability. Application of HZO thin films as an active channel layer improved the TFT device performance and bias stability, as compared to i-ZnO TFTs. The excellent negative bias temperature stress (NBTS) stability of the device was analyzed using the HZO and i-ZnO TFTs transfer curves acquired at a high temperature (473 K).

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.436-436
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• 2011

Recently, spintronic devices with submicron structures are widely investigated to take advantage of their unique micromagnetic properties. In this work, we study the temperature dependence of exchange bias in bilayer anti-dot arrays made by depositing Co (40 nm)/Ni (5 nm) ferromagnetic bilayer on Si substrate to form anti-dot arrays with a diameter $1{\mu}m$. The anti-dot patterning was done only for the upper Co layer, while the Ni underlayer was kept unperforated. The temperature dependences of magnetoresistance (MR) and exchange bias were studied along magnetic easy and hard axes. The in-plane MR measurements were performed using a physical-property measurement system (PPMS ; Quantum Design Inc.) at various temperatures. The standard in-line four-point probe configuration was used for the electrical contacts. As temperature was varied, the MR data were obtained in which in-plane field (H=3 kOe) was applied in the directions along the hard and the easy axes with respect to the lattice plane. The temperature dependences of magnetic anisotropy and exchange bias were also studied along the magnetic easy and hard axes. As temperature decreases, the single peak splits into two peaks. While no exchange bias was observed along the magnetic easy axis, the exchange bias field steadily increased with decreasing temperature along the magnetic hard axis. These results were interpreted in connection with the magnetic anisotropy and the effect of the anti-dots in pinning domain wall motion along the respective direction.

• Korean Journal of Materials Research
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• v.25 no.5
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• pp.253-257
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• 2015

The implanting of metal products is performed with numerous surface treatments because of toxicity and adhesion. Recently, the surface modification of metal products has been actively studied by coating the surface of the TiC or TiN film. We prepared a Ti(10%)Ag Target which may be used in dental oral material by, using the AIP(arc ion plating) system TiAgN coating layer that was deposited on Ti g.23. The purpose of this study was to establish the optimal bias voltage conditions of the coated TiAgN layer formed by the AIP process. The TiAgN coatings were prepared with different bias voltage parameters (0V to -500V) to investigate the effect of bias voltage on their mechanical and chemical properties. The SEM(scanning electron microscope), EDS(energy dispersive X-ray spectrometer), XRD(X-ray diffraction), micro-hardness, and potentiodynamic polarization were measured and the surface characteristics of the TiAgN coating layers were evaluated. The TiAgN coating layer had different mechanical characteristics based on the bias voltage, which also showed differences in thickness and composition.

• The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
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• v.30 no.3
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• pp.1-19
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• 2017

Objectives : This study aimed to validate the effect of herbal medicine intervention to relieve the symptoms of psoriasis using systematic review and meta-analysis and provide the newest reason of effectiveness of Korean medicine to psoriasis. Methods : Data were collected through electronic database including Pubmed, Cochrane CENTRAL, NDSL OASIS, Koreantk. Two experts assessed risk of bias of randomized controlled trials by Cochrane group's Risk of Bias tool after searching, reviewing and selecting papers. Data were analyzed using Review Manager(RevMan) 5.3 and Comprehensive Meta Analysis 2.0. Results : Total number of selected trials was 16 randomized controlled trials. This study evaluated the risk of bias and effectiveness of herbal medicine to psoriasis. There were high frequency uncertain in selection bias, performance bias and detection bias. In this meta-analysis, Korean medicine treatment was more effective than western medicine (ES:0.507, 95%CI:0.147-0.867) and placebo (ES:0.955, 95%CI:0.598-1.312). Conclusions : Herbal medicine intervention can be an effective for treatment in psoriasis. But enhancing levels of evidence, we must try to accumulate clinical researches of herbal medicine to psoriasis in Korea.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.12
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• pp.5639-5647
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• 2011

The purpose of this study was to analyze the influence of bias and the multicultural attitude of elementary schoolchildren on the multicultural efficacy and to seek for the right direction of multicultural education in elementary school. To attain this purpose, this study asked 416 elementary schoolchildren to questions in Jeonbuk Province. The results are as follows. First, there is a significant difference on bias, multicultural attitude, and efficacy to gender and grade. Second, there is a meaningful correlation among bias, multicultural attitude, and multicultural efficacy. Third, the elementary schoolchildren's bias has a significant influence on the multicultural attitude and efficacy. Fourth, the elementary schoolchildren's multicultural attitude exercises a meaningful effect on the multicultural efficacy. According to this survey, a variety of multicultural programs for the elementary schoolchildren are needed to develop and apply in substance at the level of their eyes. In addition to that, a diversity of studies are needed constantly for making the elementary schoolchildren get some positive understanding on various cultures.