• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.5
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• pp.7-12
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• 2008

This paper described results for desiging the best effective bushing geometry by comparing the distribution of the electric field according to bushing geometry. Twelve cases of the geometrical change are tried to analysis. Improvement of the insulation strength related with the vector and the electric field distribution are reached to about 0.7[%] and $21{\sim}26[%]$ by changing the electrode length, respectively. Moreover, in cases of the change of insulator thickness at high-voltage parts, the insulation strength relevant to the same parameters as mentioned above are 2[%] and $23{\sim}43[%]$, respectively Consequently, the quenching voltage for interrupting the partial discharge might be improved due to increasing the insulation strength by the geometrical change.

• Proceedings of the Korean Society of Crop Science Conference
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• 2022.10a
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• pp.120-120
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• 2022

Agrivoltaic System (AVS) was introduced with the concept that it could generate electricity by using the extra light remain after crops use for photosynthesis in farm, which can earn additional income. However, crop yield was declined under the AVS condition due to the decrease in light energy. In the past, many researchers have been studied about crop states under shading conditions. However, the phenomenon of partial shading such as under the AVS is not well studied. In this study, to figure out the response of crop under the different light conditions, the electron transport rate (ETR) and non-photochemical quenching (NPQ) of rice was investigated using the chlorophyll fluorescence measurement. Also, physiological changes of crops under the shading conditions were investigated. The growth experiment under partial shading under AVS and overall shading which made of 35% shade cloth was conducted to understand the eco-physiological responses of rice to light in terms of the photosynthesis. Under the shading conditions, SPAD value and chlorophyll contents were higher, but the leaf thickness was lower than control. The overall shading condition show lower ETR than others during the growing season. In contrast, NPQ was higher than other treatments. This means the available light energy cannot contribute to photosynthesis under the shading condition.

• Journal of the Korean Vacuum Society
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• v.7 no.s1
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• pp.1-6
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• 1998

The influence of the order-disorder structural transition on the magnetic and mageto-optical, and transport properties of Fe-Al and Co-Al alloy films has been investigated. The disordered states in the alloy films were prepared by vapor quenching deposition on glass substrates cooled by liquid nitrogen. The experimental study of the magento-optical properties of the ordered and disordered Fe-Al and Co-Al alloy films has been carried out in 1.05-5.0 eV energy range at room temperature. The transport properties have been measured in 2-300K temperature range with and without magnetic field of 0.5T. The influence of the order-disorder structural transition on the magnetic and magneto-optical properties was discussed by using the effective medium approximation and the structural defect approach. That on the temperature dependence of the resistivity was analyzed in a framework of the partial localization of the electronic states and the variable range hopping conductivity.

• Journal of Welding and Joining
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• v.33 no.5
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• pp.53-60
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• 2015

Laser surface Melting Process is getting hardening layer that has enough depth of hardening layer as well as no defects by melting surface of substrate. This study used CW(Continuous Wave) Yb:YAG and STD11. Laser beam speed, power and beam interval are fixed at 70mm/sec, 2.8kW and 800um respectively. Hardness in the weld zone are equal to 400Hv regardless of melting zone, remelting zone overlapped by next beam and HAZ. Similarly, microstructures in all weld zone consist of dendrite structure that arm spacing is $3{\sim}4{\mu}m$, matrix is ${\gamma}$(Austenite) and dendrite boundary consists of ${\gamma}$ and $M_7C_3$ of eutectic phase. This microstructure crystallizes from liquid to ${\gamma}$ of primary crystal and residual liquid forms ${\gamma}$ and $M_7C_3$ of eutectic phase by eutectic reaction at $1266^{\circ}C$. After solidification is complete, primary crystal and eutectic phase remain at room temperature without phase transformation by quenching. On the other hand, microstructures of substrate consist of ferrite, fine $M_{23}C_6$ and coarse $M_7C_3$ that have 210Hv. Microstructures in the HAZ consist of fine $M_{23}C_6$ and coarse $M_7C_3$ like substrate. But, $M_{23}C_6$ increases and matrix was changed from ferrite to bainite that has hardness above 400Hv. Partial Melted Zone is formed between melting zone and HAZ. Partial Melted Zone near the melting zone consists of ${\gamma}$, $M_7C_3$ and martensite and Partial Melted Zone near the HAZ consists of eutectic phase around ${\gamma}$ and $M_7C_3$. Hardness is maximum 557Hv in the partial melted zone.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.739-741
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• 2001

Magnetic field distribution of rotating flux type Low-Tc superconducting (LTS) power supply with respect to the applied current on exciters is investigated in detail by using Finite Element Method (FEM). LTS power supply consists of two exciters, a rotor, a stator and superconductor foil attached to the inner surface of the stator and LTS load. The current pumping of LTS power supply is induced by partial-quenching and recovery of superconductor foil. For this reason, magnetic flux density on superconductor foil must be sufficiently greater than the its critical magnetic density. In this analysis, the normal spot on superconductor foil appears more than 10A of excitation current. The results of this analysis are calculated and compared with the experimental results.

• Transactions of the Korean hydrogen and new energy society
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• v.9 no.1
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• pp.16-24
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• 1998

Recently Zr-based $AB_2$ type hydrogen absorbing alloy has received much attention as a negative electrode material for the Ni-MH batteries because of its high capacity. In this study $ZrV_{0.1}Mn_{0.7}Ni_{1.2}$ alloy was chosen and the effects of heat treatment and a partial substitution of the Mo in Mn site on the various electrode properties were investigated. The alloys was prepared by arc melting (as-cast sample). Some of them were heat treated at $1,100^{\circ}C$ for 4 hours. After this they were differentiated by the different cooling rates of slow cooling and quenching. Various electrode characteristics such as activation process, high rate dischargeability and self discharge characteristic were investigated with the three types of electrodes. It was found that heat treated alloys resulted in an increase in plateau flatness of P-C isotherms however both discharge capacity and high rate capability were decreased. And the partial substitution of Mo for Mn in $ZrV_{0.1}Mn_{0.7}Ni_{1.2}$ alloy improved the self-discharge characteristic without the loss of discharge capacity (300mAh/g).

• Journal of Technologic Dentistry
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• v.23 no.1
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• pp.65-73
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• 2001

The purpose of this study was to investigate the microstucture and hardness, corrosion of pure Ti alloy, which is widely used as partial denture frame work these days, depending on the cooling method, followed by casting. The first group was bench cooling at room temperature($18^{\circ}C$), the second group was slowly cooled in the furnace from $700^{\circ}C$ to room temperature, and third. rapidly cooled in $0^{\circ}C$ water. The microstructure of each specimen observed by means of photomicrograph taken by electron microscope, in add to the physical characteristics of each specimen were obtained using the rockwell Hardnest Number. the characteristics of corrosion. The results were obtained as follows: 1. From Potentiodynamic plot. we conclude furnace-cooled specimen had the best stabiltity of passive film and that air-cooled specimen showed similar characteristics. The density of electric current of quenched specimen was the highest, which formed kind of unstable passive film. 2. Specimen cooled at room temperature (air cooling) had the highest value of hardness of 81.26HRB, specimen cooled at ice-water, $0^{\circ}C$, had the value of 78.42HRB, and specimen furnace-cooled at $700^{\circ}C$ had lowest value of 77.1HRB. 3. Quenching treated micro-structure formed martensite structure by and large. In case of air cooling, we could see $\alpha$-structure widmanstatten formed overall. In furnace cooling, widmanstatten structure and various shape $\alpha$-structures forming colony with direction were detected.

• Journal of the Korean Electrochemical Society
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• v.15 no.3
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• pp.181-189
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• 2012

We developed a new high-yield synthesis method of free-standing germanium nanocrystals (Ge NCs) by means of the gas-phase photolysis of tetramethyl germanium in a closed reactor using an Nd-YAG pulsed laser. Size control (5-100 nm) can be simply achieved using a quenching gas. The $Ge_{1-x}Si_x$ NCs were synthesized by the photolysis of a tetramethyl silicon gas mixture and their composition was controlled by the partial pressure of precursors. The as-grown NCs are sheathed with thin (1-2 nm) carbon layers, and well dispersed to form a stable colloidal solution. Both Ge NC and Ge-RGO hybrids exhibit excellent cycling performance and high capacity of the lithium ion battery (800 and 1100 mAh/g after 50 cycles, respectively) as promising anode materials for the development of high-performance lithium batteries. This novel synthesis method of Ge NCs is expected to contribute to expand their applications in high-performance energy conversion systems.