• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.7
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• pp.513-516
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• 2010

In this work, a study is presented of the static characteristics of 4H-SiC DMOSFETs obtained by adjustment of the p-base region. The structure of this MOSFET was designed by the use of a device simulator (ATLAS, Silvaco.). The static characteristics of SiC DMOSFETs such as the blocking voltages, threshold voltages, on-resistances, and figures of merit were obtained as a function of variations in p-base doping concentration from $1\;{\times}\;10^{17}\;cm^{-3}$ to $5\;{\times}\;10^{17}\;cm^{-3}$ and doping depth from $0.5\;{\mu}m$ to $1.0\;{\mu}m$. It was found that the doping concentration and the depth of P-base region have a close relation with the blocking and threshold voltages. For that reason, silicon carbide DMOSFET structures with highly intensified blocking voltages with good figures of merit can be achieved by adjustment of the p-base depth and doping concentration.

• Korean Journal of Environmental Agriculture
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• v.7 no.2
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• pp.124-129
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• 1988

Prolonged aquatic toxicity tests (7-days) of six pesticides to the freshwater fish Oryzias latipes were performed to confirm the adequacy of the exposure times, 48-hr or 96-hr, which has been required by the protocols for the aquatic acute toxicity test. The toxicity curves were plotted for each chemical, and the significance of the difference between lethal threshold concentrations and 48-hr or 96-hr LC50's was analysed statistically. The lethal threshold concentrations of butachlor, fenobucarb, and chlorothalonil were clearly defined on the 5th day, 2nd day, and 2nd day at 0.53mg/1, 10.3mg/l, and 0.085mg/1, respectively. But the toxicity curves of alachlor, diazinon, and iprobenfos continued with no threshold for 7 days. Four out of six test pesticides failed to show the threshold concentration during the 96-hr exposure time. Therefore, the results of the acute toxicity test using 48-hr or 96-hr exposure time would not describe the ideal toxicity of pesticides. It is recommended that the prolonged exposure should be continued long enough to define the threshold adequately.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.8
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• pp.172-177
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• 2014

We present on a threshold switching device based on AsGeTeSi material which is significantly improved by two $N_2$ processes: reactive $N_2$ during deposition, and $N_2$ plasma hardening. The introduction of N2 in the two-step processing enables a stackable and thermally stable device structure, is allowing integration of switch and memory devices for application in nano scale array circuits. Despite of its good threshold switching characteristics, AsTeGeSi-based switches have had key issues with reliability at a high temperature to apply resistive memory. This is usually due to a change in a Te concentration. However, our chalconitride switches(AsTeGeSiN) show high temperature stability as well as high current density over $1.1{\times}10^7A/cm^2$ at $30{\times}30(nm^2)$ celll. A cycling performance of the switch was over $10^8$ times. In addition, we demonstrated a memory cell consisted of 1 switch-1 resistor (1S-1R) stack structure using a TaOx resistance memory with the AsTeGeSiN select device.

• Polymer(Korea)
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• v.27 no.1
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• pp.40-45
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• 2003

In this work, the effect of different contents of $Fe_3O_4$ and temperature variation on the electrical conductivity ($\sigma$) in the polar acrylonitrile butadiene rubber (NBR)/$Fe_3O_4$ (magnetite) mixture system was investigated. It was found that the percolation threshold concept holds true for the conductive particle-filled composites where $\sigma$ indicates a nearly sharp increase when the concentration of magnetite in the mixture exceeds 22%. The temperature dependence of $\sigma$ was thermally activated below and at the percolation threshold ($P_c$). Magnetite acted as reinforcing and conductive filler for NBR. At room temperature and higher voltages, the electrical current was proportional to the square of voltage ($I{\propto}V^2$) for the composites which contain 30 phr of magnetite. Moreover, it was shown that the composites with magnetite of 50 phr showed the highest tensile strength and elongation at break, which was due to the formation of optimal physical interlock and crosslinking. The results of 100%, 200%, and 300% Young moduli said that the moduli are largely correlated with reinforcement effect of magnetite and viscosity of the blends from torque curve.

• The Korean Journal of Food And Nutrition
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• v.30 no.4
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• pp.780-787
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• 2017

The consumption of high-salt foods is an independent risk factor for increased hypertension. Thus, evaluating the relationship of taste sensitivity and pleasantness of high-salt foods such as Korean jang products, would help contribute to an understanding of salty food eating behaviors of the Korean rural elderly. This study aimed to verify the association between taste sensitivity and salinity of Korean jang products, and the preferences of food groups and nutrient intake in the rural elderly. We studied 269 elderly persons (males 83, females 186) aged above 65 years, residing in the rural area, Sunchang gun Jeonbuk. For each subject, a recognition threshold of 4 basic tastes and pleasant concentrations of NaCl were estimated using the sip- and-spit method. Taste preferences, frequency of intake of food groups, nutrient intakes, and salinity and sweetness of Korean jang products (Doenjang, Ganjang, Gochujang) were assessed. No association was found between salt taste recognition threshold and optimally preferred concentration of salt and salinity of Korean jang products. However, the sweet taste recognition threshold was positively related to the sweetness of Korean jang products. Also, the salinity of Doenjang positively correlated with the frequencies of food groups and nutrient intakes. That is to say that the sweet taste sensitivity was related to the sweetness of Korean jang products, but was not sensitive to the salty taste. The salinity of Doenjang correlated with the consumption of food and nutrient intakes. Taken together, these findings suggest the need for appropriate intervention and education to reduce the salinity of Doenjang, which is an important modifiable factor contributing to reducing sodium intake in the rural elderly.

• The Korean Journal of Pharmacology
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• v.5 no.2
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• pp.87-92
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• 1969

The effects of dephenylhydantoin, strychnine, coramine, d-amphetamine and chlorpromazine on $QO_2$ and non-inulin space $Na^+$, $K^+$ concentration of rat cerebral cortical slices incubated in pH 7.4 glycylglycine glucose saline was investigated. In general, there are decreased non-inulin space $Na^+$ concentration or increased non-inulin space $K^+$ concentration or both when the ratio of respiration to non-inulin space is greater than control group except in case of chlorpromazine $10^{-4}\;M$. And it is suggested that the ratio of respiration to non-inulin space is responsible more closely for the non-inulin space Na, K concentration than $QO_2$ expressed per tissue wet weight. Effects of diphenylhydantoin and several other agents on electrolytes and the electroshock seizure threshold are discussed.

• Journal of the Society of Disaster Information
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• v.20 no.1
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• pp.93-105
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• 2024

Purpose: This study aims to quantitatively determine the impact on nearby risidents by selecting the amount of chemicals emitted from the workplace among the substances subject to the chemical emission plan and predicting the concentration with the atmospheric diffusion program. Method: The selection of research materials considered half-life, toxicity, and the presence or absence of available monitoring station data. The areas discharged from the materials to be studied were selected as the areas to be studied, and four areas with floating populations were selected to evaluate health risks. Result: AERMOD was executed after conducting terrain and meteorological processing to obtain predicted concentrations. The health hazard assessment results indicated that only dichloromethane exceeded the threshold for children, while tetrachloroethylene and chloroform appeared at levels that cannot be ignored for both children and adults. Conclusion: Currently, in the domestic context, health hazard assessments are conducted based on the regulations outlined in the "Environmental Health Act" where if the hazard index exceeds a certain threshold, it is considered to pose a health risk. The anticipated expansion of the list of substances subject to the chemical discharge plan to 415 types by 2030 suggests the need for efficient management within workplaces. In instances where the hazard index surpasses the threshold in health hazard assessments, it is judged that effective chemical management can be achieved by prioritizing based on considerations of background concentration and predicted concentration through atmospheric dispersion modeling.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.30 no.6
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• pp.345-348
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• 2017

In this work, static characteristics of 4H-SiC SJ-ACCUFETs were obtained by adjusting the p-pillar region. The structure of this SJ-ACCUFET was designed by using a two-dimensional simulator. The static characteristics of SJ-ACCUFET, such as the breakdown voltages, on-resistance, and figure of merits, were obtained by varying the p-pillar doping concentration from $1{\times}10^{15}cm^{-3}$ to $5{\times}10^{16}cm^{-3}$ and the thickness from $0{\mu}m$ to $9{\mu}m$. The doping concentration and the thickness of p-pillar region are closely related to the break down voltage and on-resistance and threshold voltages. Hence a silicon carbide SJ-ACCUFET structure with highly intensified breakdown voltages and low on-resistances with good figure of merits can be achieved by optimizing the p-pillar thickness and doping concentration.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.211.2-211.2
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• 2015

In order to investigate the effect of front channel in DAL (dual active layer) TFT (thin film transistor), we successfully fabricated DAL TFT composed of ITZO and IGZO as active layer using the solution process. In this structure, ITZO and IGZO active layer were used as front and back channel, respectively. The front channel was changed from 0.05 to 0.2 M at fixed 0.3 M IGZO of back channel. When the mol concentration of front channel was increased, the threshold voltage (VTH) was increased from 2.0 to -11.9 V and off current also was increased from 10-12 to 10-11. This phenomenon is due to increasing the carrier concentration by increasing the volume of the front channel. The saturation mobility of DAL TFT with 0.05, 0.1, and 0.2 M ITZO were 0.45, 4.3, and $0.65cm2/V{\cdot}s$. Even though 0.2 M ITZO has higher carrier concentration than 0.05 and 0.1 M ITZO, the 0.1 M ITZO/0.3 M IGZO DAL TFT has the highest saturation mobility. This is due to channel defect such as pores and pin-holes. These defect sites were created during deposition process by solvent evaporation. Due to these defect sites, the 0.1 M ITZO/0.3 M IGZO DAL TFT shows the higher saturation mobility than that of DAL TFT with front channel of 0.2 M ITZO.

• Korean journal of food and cookery science
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• v.12 no.3
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• pp.305-311
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• 1996

This study was to seek menu model in usual dishes to guarantee the optimum salt intake considering the optimum gustation of salt surveyed on Korean adults. First, a pilot test was practiced using rice gruel to determine the criteria and a meaningful interval of salt concentration. Based on the criteria and interval so determined, a test was performed to seek the optimum gustation of salt concentration in usual diets. Subjectgroup for the above tests was university students living in Kyung-Book area. The results were as follows: 1. Mode value of the optimum gustation of salt was 0.5% and the received threshold difference of salt was 0.2% in the pilot test. 2. Mode values of the optimum gustation of salt in a la carte, soups and stews were lower than those of other side dishes. 3. But the portion size of a la carte, soups and stews is much larger than that of other side dishes, so that a la carte, soups and stews are sources of relatively larger amount of salt than other side dishes. 4. Considering the recommended optimum salt intake, it is desirable to reduce the amount of stock in soups and stews and to select fried food or salad more frequently.