• Journal of Electrical Engineering and Technology
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• v.9 no.2
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• pp.686-694
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• 2014

A power semiconductor device, usually used as a switch or rectifier, is very significant in the modern power industry. The power semiconductor, in terms of its physical properties, requires a high breakdown voltage to turn off, a low on-state resistance to reduce static loss, and a fast switching speed to reduce dynamic loss. Among those parameters, the breakdown voltage and on-state resistance rely on the doping concentration of the drift region in the power semiconductor, this effect can be more important for a higher voltage device. Although the low doping concentration in the drift region increases the breakdown voltage, the on-state resistance that is increased along with it makes the static loss characteristic deteriorate. On the other hand, although the high doping concentration in the drift region reduces on-state resistance, the breakdown voltage is decreased, which limits the scope of its applications. This addresses the fact that breakdown voltage and on-state resistance are in a trade-off relationship with a parameter of the doping concentration in the drift region. Such a trade-off relationship is a hindrance to the development of power semiconductor devices that have idealistic characteristics. In this study, a novel structure is proposed for the Insulated Gate Bipolar Transistor (IGBT) device that uses conductivity modulation, which makes it possible to increase the breakdown voltage without changing the on-state resistance through use of a P-floating layer. More specifically in the proposed IGBT structure, a P-floating layer was inserted into the drift region, which results in an alleviation of the trade-off relationship between the on-state resistance and the breakdown voltage. The increase of breakdown voltage in the proposed IGBT structure has been analyzed both theoretically and through simulations, and it is verified through measurement of actual samples.

• Journal of Electrochemical Science and Technology
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• v.12 no.3
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• pp.330-338
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• 2021

An integral electrode-bipolar plate assembly, which is composed of electrode, conductive adhesive film (CAF) and bipolar plate, has been developed and evaluated for application with a vanadium redox flow battery (VRB) to decrease contact resistance between electrode and bipolar plate. The CAF, made of EVA (ethylene-vinyl-acetate) material with carbon black or CNT (Carbon Nano Tube), is applied between the electrode and the bipolar plate to enable an integral assembly by adhesion. In order to evaluate the integral assembly of VRB by adhesive film, the resistivity of integral assembly and the performance of single cell were investigated. Thus, it was verified that the integral assembly is applicable to redox flow battery. Through resistance and contact resistance of bare EVA and CAF films on bipolar plate were changed. Among the adhesive films, CAF film coated with carbon black showed the lowest value in through resistance, and CAF film coated with CNT showed the lowest value in contact resistance, respectively. The efficiency of VRB single cell was improved by applying CAF films coated with carbon black and CNT, resulting in the reduced overvoltage in charging process. Therefore, the energy efficiency of both CAF films, about 84%, were improved than that of blank cell, about 79.5 % under current density at 40 mA cm^-2. The energy efficiency of the two cells were similar, but carbon black coated CAF improved the coulomb efficiency and CNT coated CAF improved the voltage efficiency, respectively.

• Proceedings of the Korean Society of Crop Science Conference
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• 2022.10a
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• pp.290-290
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• 2022

Powdery mildew is known to be one of the serious diseases in C. moschata cultivation. Plants infected with powdery mildew cause damage to cultivation areas such as occurrence of deformity fruit and decrease in quantity. also, it has been reported that many farms have difficulties in controlling powdery mildew due to the outbreak under various conditions throughout the year. Therefore, this study intends to perform a phenotype test and a genotype test for C. moschata 60 lines grown in Jenong S&T. Podospareaxanthii, known as a pathogen that causes powder mildew disease in pumpkins in Korea, was collected and used as an inoculation source, phenotype test was performed by examining the infection area rate(%) of powdery mildew disease that occurred in leaves 25 days after inoculation. It was determined that 0% of the infection area rate was in the first stage, 1 to 5% in the second stage, 6 to 15% in the third stage, 16 to 30% in the fourth stage, and 31% or more in the fifth stage, The first and second stages were judged as resistance, the third as moderate resistance, and the fourth and fifth stages as sensitivity. As a result of the phenotype test, it was confirmed that the resistance was 21 points, moderate resistance was 14 points, and sensitivity was 25 points. After searching for the genes related to powdery mildew resistance resistance, pm-0, CmbHLH87, and LOC111453072, 21 points of resistance and 9 points of moderate resistance identified through phenotype tests were identified through gel electrophoresis after polymerase chain reaction(PCR) using 5 primers related to 3 genes. As a result of genotype testing of a total 30 points, the CmbHLH87 and LOC111453072 gene were found to be resistant bands in all points, PMR1 was identified as 20 points for resistance, 4 points for moderate resistance, and 6 points for sensitivity, PMR2 was not identified in the entire band, and PMR5 was identified as 18 point for resistance, 3 points for moderate resistance, and 9 points for sensitivity. As a result, when comparing the phenotype test results and genotype test results, CmbHLH87 and LOC111453072 genes was 100% consistent in resistance and moderate resistance, PMR1 was 95.2% in resistance, 44.4% in moderate resistance, and PMR5 was 90% in resistance and 33.3% in moderate resistance, PMR2 was not consistent in resistance and moderate resistance. Therefore, it is expected that more accurate PMR test will be possible by using molecular markers(PMR1, PMR5) and by developing CmbHLH87 and LOC111453072 gene-related molecular markers.

• Korean Journal of Agricultural Science
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• v.44 no.1
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• pp.1-15
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• 2017

In major field crops, synthetic herbicides have been used to control weeds worldwide. Globally, herbicide resistance in weeds should be minimized because it is a major limiting factor for food security. Cross resistance can occur with herbicides within the same or in different herbicide families and with the same or different sites of action. Multiple resistance refers to evolved mechanisms of resistance to more than one herbicide (e.g., resistance to both ALS-inhibitors and ACCase-inhibitors) and this resistance was brought about by separate selection processes. Target site resistance could occur from changes at the biochemical site of action of one herbicide. Non target site resistance occurs through mechanisms which reduce the number of herbicide molecules that reach the herbicide target site. There are currently 480 unique cases (species ${\times}$ site of action) of herbicide resistance globally in 252 plant species (145 dicots and 105 monocots). To date, resistance in weeds has been reported to 161 different herbicides, involving 23 of the 26 known herbicide sites of action. Finally, it can be concluded that we can protect crops associated to herbicide resistant weeds by applications of biochemical, genetic and crop control strategies.

• Journal of Electrical Engineering and Technology
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• v.10 no.1
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• pp.325-330
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• 2015

With approval from the Asia Pacific Metrology Program Working Group on Materials Metrology (APMP WGMM), an international comparison for sheet resistance standards for silicon wafers was firstly conducted among Korea Research Institute of Standards and Science (KRISS) in Korea, CMS/ITRI in Taiwan, and NIM in China, which are national metrology institutes (NMIs), from August 2011 to January 2012. The sheet resistance values of the standards are $10{\Omega}$, $100{\Omega}$, and $1000{\Omega}$; the measurement was conducted in sequence at KRISS, CMS/ITRI, NIM, and KRISS again using the four-point probe method with single and dual configuration techniques. The reference value for the measurement results of the three NMIs was obtained through averaging the values of the three results for each sheet resistance range. The differences between the reference value and the measured values is within 0.22% for $10{\Omega}$, 0.17% for $100{\Omega}$, and 0.12% for $1000{\Omega}$. Therefore, the international consistency for conducting sheet resistance measurements is confirmed within 0.22% through the APMP WGMM approved comparison.

• Journal of Plant Biotechnology
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• v.47 no.2
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• pp.164-171
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• 2020

Transgenic Alstroemeria plants resistant to Alstroemeria mosaic virus (AlMV) were generated through RNA-mediated resistance. To this end, the friable embryogenic callus (FEC) of Alstroemeria was induced from the leaf axil tissue and transformed with a DNA fragment containing the coat protein gene and 3'-nontranslated region of AlMV through an improved particle bombardment system. The bar gene was used as a selection marker. More than 300 independent transgenic FEC lines were obtained. Among these, 155 lines resistant to phosphinothricin (PPT) were selected under low stringent conditions. After increasing the stringency of PPT selection, 44 transgenic lines remained, and 710 somatic embryos from these lines germinated and developed into shoots. These transgenic shoots were then transferred to the greenhouse and challenged with AlMV. In total, 25 of the 44 lines showed some degree of resistance. PCR analysis confirmed the presence of the viral sequence. Virus resistance was observed at various levels. Establishment of an efficient transformation system for Alstroemeria will allow inserting transgenes into this plant to confer resistance to viral and fungal pathogens. Accordingly, this is the first report on the production of a transgenic virus-resistant Alstroemeria and lays the foundation for alternative management of viral diseases in this plant.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1993.10a
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• pp.1176-1185
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• 1993

The purpose of this study is to propose a new dynamic model of wheels and agricultural tractors through verification of the existence of " lift resistance " and "perpendicular adhesion" which also can be called " contra-retractive adhesion". The existence of these forces was proved through experiments including the development of a sensor which can measure the forces acting on a wheel accurately. Consequently " perpendicular adhesion ratio" which is defined as the ratio of the perpendicular adhesion to the distributed load was observed to be in the range of 0.05 to 0.3. This means the influence of the " lift resistance " is comparable to that of motion resistance in wheel dynamics. The perpendicular adhesion ratio was observed to decrease logarithmically with the increase of ground contact pressure, and to increase linearly with increase of the travel speed of the wheel . Some examples to express the new dynamic model compared to the conventional dynamics are explained.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.10 s.181
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• pp.2581-2588
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• 2000

In previous studies, the dynamic resistance, which was calculated by the process variables measured at the electrode of the welding machine, and the electrode displacement were used for quality exa mination. However, in-process usage of such systems is not effective in systems that include a welding gun attached to a robot. In order to overcome such problems, we obtained and used the process variables from the welding machine timer. This would allow us to estimate real time in -process weld quality. For quality estimation, the features were extracted as factors from the primary dynamic resistance patterns, which were measured in t he welding machine timer. The relationship between the indexes and nugget size of the welds was observed through the regression analysis. Using the analyzed factors, a regression model that could estimate nugget diameter was developed. Two regression equations of the model were suggested depending on the factors, and it was showed that the model developed by stepwise method was effective one for weld quality estimation. The developed estimation model was in good linearity with the nugget diameter obtained through the experimentation.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.10
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• pp.4879-4881
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• 2012

Epidermal growth factor receptor (EGFR) overexpression is associated with resistance to chemotherapy and radiotherapy. The EGFR modulates DNA repair after radiation-induced damage through an association with the catalytic subunit of DNA protein kinase. DNA double-strand breaks (DSBs) are the most lethal type of DNA damage induced by ionizing radiation, and non-homologous end joining is the predominant pathway for repair of radiation-induced DSBs. Some cell signaling pathways that respond to normal growth factors are abnormally activated in human cancer. These pathways also invoke the cell survival mechanisms that lead to resistance to radiation. The molecular connection between the EGFR and its control over DNA repair capacity appears to be mediated by one or more signaling pathways downstream of this receptor. The purpose of this mini-review was not only to highlight the relation of the EGFR signal as a regulatory mechanism to DNA repair and radiation resistance, but also to provide clues to improving existing radiation resistance through novel therapies based on the above-mentioned mechanism.

• Geomechanics and Engineering
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• v.38 no.2
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• pp.165-177
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• 2024

Liquefaction phenomenon refers to a phenomenon in which excess pore water pressure occurs when a dynamic load such as an earthquake is rapidly applied to a loose sandy soil ground where the ground is saturated, and the ground loses effective stress and becomes liquid. The laboratory repetition test for liquefaction evaluation can be performed through a repeated triaxial compression test and a repeated shear test. In this regard, this study attempted to evaluate the effects of the relative density of sand on the liquefaction resistance strength according to particle size distribution using repeated triaxial compression tests, and additional experimental verification using numerical analysis was conducted to overcome the limitations of experimental equipment. As a result of the experiment, it was confirmed that the liquefaction resistance strength increased as the relative density increased regardless of the classification of soil, and the liquefaction resistance strength of the SP sample close to SW was quite high. As a result of numerical analysis, it was confirmed that the liquefaction resistance strength increased as the confining pressure increased under the same relative density, and the liquefaction resistance strength did not decrease below a certain limit even though the confining pressure was significantly reduced at a relatively low relative density. This is judged to be due to a change in confining pressure according to the depth of the ground. As a result of analyzing the liquefaction resistance strength according to the frequency range, it was confirmed that there was no significant difference from the laboratory experiment results in the basic range of 0.1 to 1.0 Hz.