• Journal of Hydrogen and New Energy
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• v.34 no.6
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• pp.631-640
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• 2023

This study selected Eco-AZ91 MgH₂, which shows high enthalpy as a material for this purpose, as the basic material, and analyzed the change in characteristics by synthesizing TiNi as a catalyst to control the thermodynamic behavior of MgH₂. In addition, the catalyst dispersion technology using graphene oxide (GO) was studied to improve the high-temperature aggregation phenomenon of Ni catalyst and to secure a source technology that can properly disperse the catalyst. XRD, SEM, and BET analysis were conducted to analyze the metallurgical properties of the material, and TGA and DSC analysis were conducted to analyze the dehydrogenation temperature and calorific value, and the correlation between MgH₂, TiNi catalyst, and GO reforming catalyst was analyzed. As a result, the MgH₂-5 wt% TiNi at GO composite could lower the dehydrogenation temperature to 478-492 K due to the reduction of the catalyst aggregation phenomenon and the increase in the reaction specific surface area, and an experimental result for the catalyst dispersion technology by GO could be ensured.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.7
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• pp.1777-1783
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• 2014

In this paper, we designed and fabricated a high-speed semiconductor sensor for use in power control devices and analyzed the characteristics with pulsed radiation tests. At first, radiation sensitive circular Si PIN diodes with various diameters(0.1 mm ~5.0 mm) were designed and fabricated using Si epitaxial wafer, which has a $42{\mu}m$ thick intrinsic layer. The reverse leakage current of the diode with a radius of 2 mm at a reverse bias of 30 V was about 20.4 nA. To investigate the characteristic responses of the developed diodes, the pulsed gamma-radiation tests were performed with the intensity of 4.88E8 rad(Si)/sec. From the test results showing that the output currents and the rising speeds have a linear relationship with the area of the sensors, we decided that the optimal condition took place at a 2 mm diameter. Next, for the selected 2 mm diodes, dose rate tests with a range of 2.47E8 rad(Si)/sec to 6.21E8 rad(Si)/sec were performed. From the results, which showed linear characteristics with the radiation intensity, a large amount of photocurrent over 60mA, and a high speed response under 350ns without saturation, we can conclude that the our developed PIN diode can be a good candidate for the sensor of power control devices.

• Composites Research
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• v.34 no.5
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• pp.290-295
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• 2021

The application of lightweight structural composites to automobiles as a solution in line with global fuel economy regulations to curb global warming is recognized as a megatrend. This study was conducted to provide a technical approach that can respond to the issue of replacing parts that require conductive properties to maximize the application of thermoplastic carbon fiber reinforced plastics (CFRPs), which are advantageous in terms of repair, disposal and recycling. By utilizing the properties of the low-viscosity polymerizable oligomer matrix, it was possible to prepare a thermoplastic CFRP exhibiting excellent impregnation properties while uniformly mixing the conductive filler. Various carbon-based conductive fillers such as carbon black, carbon nanotubes, graphene nanoplatelets, graphite, and pitch-based carbon fibers were filled up to the maximum content, and electrical and thermal conductive properties of the fabricated composites were compared and studied. It was confirmed that the maximum incorporation of filler was the most important factor to control the conductive properties of the composites rather than the type or shape of the conductive carbon filler. Experimental results were observed in which it might be advantageous to apply a one-dimensional conductive carbon filler to improve electrical conductivity, whereas it might be advantageous to apply a two-dimensional conductive carbon filler to improve thermal conductivity. The results of this study can provide potential insight into the optimization of structural design for controlling the conductive properties of thermoplastic CFRPs.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.36C no.2
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• pp.14-25
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• 1999

The IEEE standard 1149.1, which was proposed to increase the observability and the controllability in I/O pins, makes it possible the board level testing. In the boundary-scan environments, many shift operations are required due to their serial nature. This increases the test application time and the test application costs. To reduce the test application time, the method based on the parallel opereational multiple scan paths was proposed, but this requires the additional I/O pins and the internal wires. Moreover, it is difficult to make the designs in conformity to the IEEE standard 1149.1 since the standard does not support the parallel operation of data shifts on the scan paths. In this paper, the multiple scan path access algorithm which controls two scan paths simultaneously with one test bus is proposed. Based on the new algorithm, the new algorithm, the new board level BIST architecture which has a relatively small area overhead is developed. The new BIST architecture can reduce the test application time since it can shift the test patterns and the test responses of two scan paths at a time. In addition, it can reduce the costs for the test pattern generation and the test response analysis.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.7
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• pp.635-645
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• 2016

In this paper, we showed the phase noise of voltage controlled oscillator(VCO) can be radically improved using FLL(Frequency Locked Loop). At first, a 5 GHz VCO is fabricated using a hair-pin resonator. The fabricated VCO shows a phase noise of -53.1 dBc/Hz at 1 kHz frequency offset. In order to improve the phase noise of the fabricated VCO, a FLL is constructed using the feedback loop that consists of the VCO, a frequency detector composed of 5 GHz resonator, loop-filter, and level shifter. The fabricated FLL is designed to oscillate at a frequency of 5 GHz, and its measured phase noise is about -120.6 dBc/Hz at 1 kHz offset frequency. As a result, the phase noise of VCO can be radically improved by about 67.5 dB applying FLL. In addition, the measured phase noise performance is close to that of crystal oscillator.

• Journal of Bio-Environment Control
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• v.28 no.4
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• pp.420-428
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• 2019

This study is the heating energy saving test of the high-bed strawberry crown heating system. The system consists of electric hot water boiler, thermal storage tank, circulation pump, crown heating pipe(white low density polyethylene, diameter 16mm) and a temperature control panel. For crown heating, the hot water pipe was installed as close as possible to the crown part after planting the seedlings and the pipe position was fixed with a horticultural fixing pin. In the local heating type, hot water at $20{\sim}23^{\circ}C$ is stored in the themal tank by using an electric hot water boiler, and crown spot is partially heated at the setting temperature of $13{\sim}15^{\circ}C$ by turning on/off the circulation pump using a temperature sensor for controlling the hot water circulation pump which was installed at the very close to crown of strawberry. The treatment of test zone consisted of space heating $4^{\circ}C$ + crown heating(treatment 1), space heating $8^{\circ}C$(control), space heating $6^{\circ}C$ + crown heating(treatment 2). And strawberries were planted in the number of 980 for each treatment. The heating energy consumption was compared between November 8, 2017 and March 30, 2018. Accumulated power consumption is converted to integrated kerosene consumption. The converted kerosene consumption is 1,320L(100%) for space $8^{\circ}C$ heating, 928L(70.3%) for space $4^{\circ}C$ + crown heating, 1,161L($88^{\circ}C$) for space $6^{\circ}C$ + crown heating). It was analyzed that space $4^{\circ}C$ + pipe heating and space $6^{\circ}C$ + crown heating save heating energy of 29.7% and 12% respectively compared to $8^{\circ}C$ space heating(control).