• Journal of the Institute of Electronics Engineers of Korea TC
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• v.37 no.3
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• pp.35-42
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• 2000

A cross-shaped microstripline-fed printed slot antenna having wide bandwidth Is presented in this paper. The proposed antenna is analyzed by using the Finite-Difference Time-Domain (FDTD) method. It was found that the bandwidth of the antenna depends highly on the length of the horizontal and vertical feedline as well as the offset position of the feedline. The maximum bandwidth of this antenna is from 1.975 GHz to 4.725 GHz, which is approximately 1.3 octave, for the VSWR $\leq$ 2. Experimental data for the return loss and the radiation pattern of the antenna are also presented. and they are in good agreement with the FDTD results.e FDTD results.

• Nuclear Engineering and Technology
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• v.48 no.1
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• pp.16-25
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• 2016

In severe loss of coolant accidents (LOCA), similar to those experienced at Fukushima Daiichi and Three Mile Island Unit 1, the zirconiumalloy fuel claddingmaterials are rapidlyheateddue to nuclear decay heating and rapid exothermic oxidation of zirconium with steam. This heating causes the cladding to rapidly react with steam, lose strength, burst or collapse, and generate large quantities of hydrogen gas. Although maintaining core cooling remains the highest priority in accident management, an accident tolerant fuel (ATF) design may extend coping and recovery time for operators to restore emergency power, and cooling, and achieve safe shutdown. An ATF is required to possess high resistance to steam oxidation to reduce hydrogen generation and sufficient mechanical strength to maintain fuel rod integrity and core coolability. The initiative undertaken by Electric Power Research Institute (EPRI) is to demonstrate the feasibility of developing an ATF cladding with capability to maintain its integrity in $1,200-1,500^{\circ}C$ steam for at least 24 hours. This ATF cladding utilizes thin-walled Mo-alloys coated with oxidation-resistant surface layers. The basic design consists of a thin-walled Mo alloy structural tube with a metallurgically bonded, oxidation-resistant outer layer. Two options are being investigated: a commercially available iron, chromium, and aluminum alloy with excellent high temperature oxidation resistance, and a Zr alloy with demonstratedcorrosionresistance.Asthese composite claddings will incorporate either no Zr, or thin Zr outer layers, hydrogen generation under severe LOCA conditions will be greatly reduced. Key technical challenges and uncertainties specific to Moalloy fuel cladding include: economic core design, industrial scale fabricability, radiation embrittlement, and corrosion and oxidation resistance during normal operation, transients, and severe accidents. Progress in each aspect has been made and key results are discussed in this document. In addition to assisting plants in meeting Light Water Reactor (LWR) challenges, accident-tolerant Mo-based cladding technologies are expected to be applicable for use in high-temperature helium and molten salt reactor designs, as well as nonnuclear high temperature applications.

• Journal of the Korean Solar Energy Society
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• v.29 no.1
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• pp.18-23
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• 2009

We intend to describe a 12kW building-integrated photovoltaic system which was applied into the south wall of a new building. This study showed the results that were appeared from describing the PV module manufacture and installation process, and performing generation performance analysis of BIPV system. From the result we confirmed that the generation performance of the BIPV system was changed by season. The performance ratio(PR) was about 83.6% in winter and it means that performance of this BIPV system was so good in that season. On the other hand, the PR in summer was about 75.0% dropped about 8%. It was believed that the change was influenced by the reduction of solar radiation irradiated into the PV modules by installation position and rainy spell in summer. And we also confirmed that low irradiation condition is cause of the additional loss in the total PV system. In this case, the efficiency ratio of PCS drops significantly at low input loads and the average conversion efficiency of PCS in summer was 76.4% decreased about 10% from 86% in winter.

• Journal of the Korean Vacuum Society
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• v.17 no.4
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• pp.302-310
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• 2008

Heat transfer between substrate and substrate-heater in low vacuum was investigated. The convection related with gas flow and pressure, the heat conduction considering surface roughness and contact pressure, and the heat loss by radiation depending on the surface emissivity were considered. The coefficient of heat conduction $h_c$ in the Fourier's law were determined experimentally from the temperature difference between the substrate and the substrate-heater in the range of substrate-heater temperature $100\;-\;500^{\circ}C$, in the pressures of 300 mTorr - 1 Torr. The temperature difference was then calculated in the reverse way for the purpose of verification, using the heat flow and the experimentally determined coefficients. The verified temperature differences were thus obtained within 0.33 % error.

• Journal of the Korea Institute of Building Construction
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• v.17 no.1
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• pp.9-14
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• 2017

Mechanical properties and neutron shielding performance of concrete with amorphous boron steel fiber have been investigated in this study. The measurement of this investigation includes air contents, slump loss, compressive strength, flexural strength, flexural toughness and neutron shielding rate. Four different fiber volume fractions were selected ranging from 0.25% to 1.0% by volume for the amorphous boron steel fibers. The testing results showed that the flexural toughness and the neutron shielding rate were increase with the increase of volume fraction for amorphous boron steel fiber. Based on the result, it is concluded that the concrete with the amorphous boron steel fiber can be effectively applied to shield the neutron and to improve mechanical properties.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.11 s.114
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• pp.1105-1111
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• 2006

In this paper, using low-temperature co-fired ceramic(LTCC) based system-in-package(SiP) technology, a very compact power amplifier LTCC module was designed, fabricated, and then characterized for 60 GHz wireless transmitter applications. In order to reduce the interconnection loss between a LTCC board and power amplifier monolithic microwave integrated circuits(MMIC), bond-wire transitions were optimized and high-isolated module structure was proposed to integrate the power amplifier MMIC into LTCC board. In the case of wire-bonding transition, a matching circuit was designed on the LTCC substrate and interconnection space between wires was optimized in terms of their angle. In addition, the wire-bonding structure of coplanar waveguide type was used to reduce radiation of EM-fields due to interconnection discontinuity. For high-isolated module structure, DC bias lines were fully embedded into the LTCC substrate and shielded with vias. Using 5-layer LTCC dielectrics, the power amplifier LTCC module was fabricated and its size is $4.6{\times}4.9{\times}0.5mm^3$. The fabricated module shows the gain of 10 dB and the output power of 11 dBm at P1dB compression point from 60 to 65 GHz.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.4
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• pp.342-349
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• 2016

We design a displaced-axis Gregorian dual antenna in the form of a metal reflectarray antenna for millimeter wave region, W-band. Unlike a reflectarray composed of printed patch antennas on a dielectric substrate, metallic rectangular waveguide unit-cells are proposed to avoid the loss of substrate and take an advantage of ease of typical metal machining fabrication. In this paper, the radiation characteristics of constructed metal reflectarray antennas show ultra high-gain antenna over 50 dBi at a target frequency in W-band. The experimental measurements are conducted in millimeter-wave compact range antenna measurement system.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.3
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• pp.230-239
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• 2009

In this paper, we propose a novel on-glass antenna for FM radio reception in a recreation vehicle(RV). We use a multi-loop structure that takes advantage of a broad matching bandwidth and a high vertical radiation gain by efficiently utilizing a given space of a quarter glass in spite of the simple planar structure. Transparency of the antenna is also improved by adjusting the stripline widths based on the induced current distributions. The proposed antenna is printed on a quarter glass of a commercial vehicle and antenna performances such as the return loss and the gain are measured in a semi-anechoic chamber. The result shows the average gain of -9.67 dBi along the bore-sight direction($\theta=90^{\circ}$, $\phi=270^{\circ}$) in the FM radio band(80$\sim$l10 MHz), which is higher than a commercial monopole typed on-glass antenna($G_{ave}$=-12.49 dBi) and micro-antenna($G_{ave}$=-19.24 dBi) mounted on the roof of the RV.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.9B
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• pp.1676-1682
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• 1999

In this paper, the double circular array microstrip patch antenna was designed to minimize the side lobe in which a cooperate feeding network was used to supply the same amplitude and equi-phase to each antenna element. Eight microstirip patch antenna(MPA) elements were arrayed with $45^{\circ}$ interval in the inner circle and the outer circle respectively. The simulation results showed that when the radii of the inner circle and the outer circle were 0.7 $\lambda$0 and 1.45 $\lambda$0, the side lobes of beam pattern were minimized. As the results of the measurements, the return loss of the designed antenna was -14.5[dB] at 11.75[GHz] in the input terminal. When the level of the main lobe was normalized at 0[dB], those of the first and the second side lobe were -18[dB] and -26[dB] respectively. The radiation patterns agree well with the simulated patterns.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.6
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• pp.75-80
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• 2006

The disastrous accident happens and the economic loss comes into being at the power facilities that used a industry site, if the fault comes into being. This paper experiments the partial discharge in the GIS used a $SF_6$ insulation gas by the pressure change. We studied the influence of particles at the partial discharge in a $SF_6$ gas. We use UHF method and measure the partial discharge signal radiation electromagnetic waves and to be happened at the $SF_6$. And we analyzed the influence on the $SF_6$ gas to have the particles which the partial discharge analyzes a spectrum of the radiated electromagnetic waves and comes out. The paper results aided the prevention of breakdown accident that happened by particles when an inside pressure changes at the GIS & the power facilities used $SF_6$ gas.