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수도 도열병에 저항성인 통일품종에 대한 침입생리에 관한 연구
김광석,정봉구 한국균학회 1977 韓國菌學會誌 Vol.5 No.1
In order to investigate histopathologically the nature of varietal resistance and infection process of the rice bast fungus, Pyricularia oryzae. this experiment was undertaken by using the resistant cultivar Tongil and susceptible cultivars Norin No.6 and Jinheung in 1973 to 1974. 1) It was found that appressorium of the fungus forms not only at 4 hours after incubation under the favor able conditions butalso peak of appressorial formation is at 48 hours treatment. Physical stimulus known to be a definite factor for appressorial formation. The optimum temperature range for appressorial infection was at 24℃ to 28℃, and pH was between 4.8 to 8.0 with 6.8 as the optimum. 2) Although percent of appressorial formation on the leaves of resistant Tongil and susceptiible Norin No.6 were only slightly different, there was a remarkable difference between resistant and susceptible cultivars with regard to percent of hyphal infection and index for hyphal extension. Index of hyphal extension was 1.6-2.7 in Tonyil. while in susceptible cultivar was 3.4-6.6. The rate of discoloration of infected cells, a indication of hypersensitivity, was greater in the resistant than in susceptible cultivar. 3) Therefore, it could be concluded that resistance of Tongil cultivar may be attributable to a higher degree of mechanical barriers as well as a higher level of antifungal substance accumulation.
김광석,최돈현,정승부 한국마이크로전자및패키징학회 2014 마이크로전자 및 패키징학회지 Vol.20 No.2
Technology for high power devices has made impressive progress in increasing the current density of powersemiconductor, system module, and design optimization, which realize high power systems with heterogeneous functionalintegration. Depending on the performance development of high power semiconductor, packaging technology of highpower device is urgently required for efficiency improvement of the device. Power device packaging must provide superiorthermal management due to high operating temperature of power modules. Here we, therefore, review critical challengesof typical power electronics packaging today including core assembly processes, component materials, and reliabilityevaluation regulations.
Effect of the number of poles on the acoustic noise from BLDC motors
김광석,이창민,황건용,황상문 대한기계학회 2011 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.25 No.2
The goal of this study is to examine the effect of the number of poles on the noise from BLDC motors. To this end, the number of slots was fixed to six and the number of the poles was set to four or eight before noise was measured. Motors having different numbers of poles showed clear differences in noise; cogging torque, torque ripple and normal local force were interpreted, analyzed and compared to determine the reason for the differences. To conduct precise comparisons of noise, efforts were made to prevent changes in other variables when constructing the four-pole and eight-pole motors. Noise measurements were conducted after going through the above preparation. The results show that the eight-pole motor produced a lower noise level than the four-pole motor. To determine the cause of the noise, the cogging torque, torque ripple and radial local force were calculated, which are representative noise sources in BLDC motors,and FFT was performed to analyze their frequency components (harmonics). The calculations were made using a finite element method with the Maxwell stress tensor.
김광석 한국기계기술학회 2009 한국기계기술학회지 Vol.11 No.1
This paper is research of design and manufacture of a hybrid vehicle. Through seminar about vehicle design principle, an undergraduate students studied concept about vehicle design. Vehicle frame designed by CATIA V5. Also, composed finite element model of designed frame and executes static and dynamic analysis. A DMU model for a full vehicle was built using CATIA V5 and used to check interference between parts and to simulate assembly process. Also, in this study, applied split parallel type's hybrid system on manufacturing vehicles. Controller for system drive designed using Atmel company's AVR MCU. Through this project, the undergraduate students could acquire knowledge about vehicle development process.
Optically-induced Nonlinearities and Polarization Modulation of Spin Dichroism in CdSe Quantum Dots
김광석 한국물리학회 2012 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.61 No.5
Polarization modulation in CdSe quantum dots is presented in the framework of the opticallyinduced nonlinearities of spin dichroism. The real and the imaginary parts of the phase retardation,which are induced from the nonlinear refractive index of the spin-degenerate fine states, are shown spectrally. The polarization modulation is also described in terms of the Jones vector, where the spectral dependences of the amplitude and phase are shown. The optically-induced elliptical polarization of a Gaussian pulse in a feasible condition of multi-quantum dot-layers is predicted precisely in terms of the rotational and the elliptical angles for increasing pulse area up to , which is also mapped on a the normalized Poincar´e sphere.