• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.32 no.3
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• pp.201-206
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• 2019

This report constitutes the first demonstration in Korea of single-crystal lateral gallium oxide ($Ga_2O_3$) as a metal-oxide-semiconductor field-effect-transistor (MOSFET), with a breakdown voltage in excess of 480 V. A Si-doped channel layer was grown on a Fe-doped semi-insulating ${\beta}-Ga_2O_3$ (010) substrate by molecular beam epitaxy. The single-crystal substrate was grown by the edge-defined film-fed growth method and wafered to a size of $10{\times}15mm^2$. Although we fabricated several types of power devices using the same process, we only report the characterization of a finger-type MOSFET with a gate length ($L_g$) of $2{\mu}m$ and a gate-drain spacing ($L_{gd}$) of $5{\mu}m$. The MOSFET showed a favorable drain current modulation according to the gate voltage swing. A complete drain current pinch-off feature was also obtained for $V_{gs}<-6V$, and the three-terminal off-state breakdown voltage was over 482 V in a $L_{gd}=5{\mu}m$ device measured in Fluorinert ambient at $V_{gs}=-10V$. A low drain leakage current of 4.7 nA at the off-state led to a high on/off drain current ratio of approximately $5.3{\times}10^5$. These device characteristics indicate the promising potential of $Ga_2O_3$-based electrical devices for next-generation high-power device applications, such as electrical autonomous vehicles, railroads, photovoltaics, renewable energy, and industry.

• Journal of the Korean Society for Nondestructive Testing
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• v.35 no.1
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• pp.52-60
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• 2015

Nuclear power plant contain many dissimilar metal welds that connect carbon steel components with stainless steel pipes using alloy600 welding materials. Primary water stress corrosion cracks at dissimilar metal welds have been continuously reported around the world. In periodic integrity evaluations, dissimilar metal welds are examined using a generic ultrasonic testing procedure, KPD-UT-10. In this procedure, the gap between the probe and examination surface is limited to 1/32 inch (0.8mm). It is not easy to test some dissimilar metal welds in Korean plants applying ordinary technology because of their tapered shapes and irregular surface conditions. This paper introduces a method for applying a flexible phased array technology to improve the reliability of ultrasonic testing results for various shapes and surface conditions. The artificial flaws in specimens with irregular surfaces were completely detected using the flexible phased array ultrasonic technology. Therefore, it can be said that the technology is applicable to field examination.

• Korean Institute of Interior Design Journal
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• v.16 no.2 s.61
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• pp.295-302
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• 2007

The use of colors plays an important role in the field of space design. The selection of proper colors influences on people who use space by making the most of the psychological and physical functions of colors. Especially, the medical space is relatively more important than other indoor spaces in the selection of colors. The medical space has to be something to do with diversity and functions, and at the same time with stability and quietude, as well as the space with general convenient facilities. Color is not only related to the expression but also to the distinction of things and the existence. It also functions as a visual language. Human beings depend heavily on the function of color as a visual language. According to previous studies, human beings depend on color by 80% of the whole range of eyesight. Thus, color is an important factor in recognizing things and space. For example, in hospital, it Is very important to apply proper colors to various medical treatment spaces for the sake of patients' rest and healing. Various colors which do not consider the function of patients' rest and healing may make the space confusing against the change of space and structure. It is also important to apply colors to the change of space and structure. Another key point that I would like to make is that color has visual, direct and physical influence on the human body. For example, the color red with long wavelength serves to regulate body temperature. Research on the color scheme for hospitals should consider both physical and psychological factors. That is why the research should be carried out in depth through continuous clinical demonstration. The present research aims to outline color planning.

• Journal of the Korean Society for Nondestructive Testing
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• v.31 no.5
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• pp.536-542
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• 2011

Dissimilar metal welds in nuclear power plant are known as very susceptible to PWSCC flaws, and periodically inspected by the qualified inspector and qualified procedure during in-service inspection period. According to field survey data, the majority of their DMWs are located on tapered nozzle or adjacent to a tapered component. These types of configurations restrict examination access and also limit examination volume coverage. Additionally, circumferential scan for axially oriented flaw is very difficult to detect located on tapered surface because the transducer can't receive flaw response from reflector for miss-orientation. To overcome this miss-orientation, it is necessary adapt skewed ultrasonic transducer accomodate tapered surface. The skewed refracted longitudinal ultrasonic transducer designed by modeling and manufactured from the modelling result for axial flaw detection. Experimental results showed that the skewed refracted longitudinal ultrasonic transducer get higher flaw response than non-skewed refracted longitudinal ultrasonic transducer.

• Korean Institute of Interior Design Journal
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• v.25 no.5
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• pp.16-30
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• 2016

There is an increasing interest in and efforts for safe residential environment from crimes nationwide. Many cities are making efforts to create safe residential environment by enacting ordinances and guidances on safe design for preventing crimes and implementing demonstration projects. In line with the trends of the times toward 'improvement of living conditions' through urban regeneration, the importance of the Crime Prevention Through Environmental Design(CPTED) has recently emerged in the field of residential housing regeneration. Indeed, the CPTED is included as essential factor in the recent deteriorated residential area regeneration related projects. In this respect, the purpose of this study is to provide the basic data on the methodology of CPTED to be applied to the regeneration of deteriorated residential area in the future. To this end, this study selected three representative CPTED projects in Busan - 'Deokpo-dong Hope and Stepping Stone Village,' 'Chilsan-dong CPTED Happiness Village' and 'Sujeong-dong Crime Prevention and Safe Village' as objects of this study and then investigated and analyzed project contents, application of CPTED strategy, subjects who are implementing projects, and the time when they implement projects as the framework of my analysis. The findings from this study are as follows: First, the projects that were largely based on hardware should be improved by including software in the future. Second, the current Step 2 should expand into Step 3 Maintenance in applying CPTED strategy. Third, it is necessary to encourage exchange and cooperation between unit projects and subjects who are operating related projects.

• KIEAE Journal
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• v.17 no.1
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• pp.5-13
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• 2017

Purpose: This study, by comprehensively the characteristics of new Hanok application techniques with the proposed site application technology in the course of the design changes that have been accumulated through Hanok technology development the second stage business, by analyzing the range of reflection, new Considering the direction reflects the efficiency of the new Hanok application techniques. Method: new Hanok application technology, it was been established through research and development of large 1 new Hanok technology it has been proposed through the "site-specific application techniques" and 2 builders and designers "space-time proposed technique" Analysis of the case, at the center of the design changes, the land the body of laws and regulations, the requirements of the public buildings, compared to the construction method and the like for the reduction of construction costs, new Hanok applied technology in the process of change by it There was analyzed whether acceleration on the range and step which is reflected in the design Result: The result of new Hanok applied technology was built through the demonstration build business case, process another major technology, foundation, woodwork, walls, roof, has been reflected in the ceiling construction, the inclusion of items in the proposed technique of construction , it was applied to the main steps in general, except for other construction work landscaping. Application techniques and construction proposal technology research team has presented, show the difference between the scope and method. With significance effort to improve the unreasonable traditional methods of these core processes that can be reflected in the field repeated the construction proposed technique as a result of the utility that can be applied for substantial construction.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.2
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• pp.66.2-66.2
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• 2017

The Korea Astronomy and Space Science Institute plans to develop a coronagraph in collaboration with National Aeronautics and Space Administrative (NASA) and install it on the International Space Station (ISS). The coronagraph is an externally occulted one stage coronagraph with a field of view from 2.5 to 15 solar radii. The observation wavelength is approximately 400 nm where strong Fraunhofer absorption lines from the photosphere are scattered by coronal electrons. Photometric filter observation around this band enables the estimation of 2D electron temperature and electron velocity distribution in the corona. Together with the high time cadence (< 12 min) of corona images to determine the geometric and kinematic parameters of coronal mass ejections, the coronagraph will yield the spatial distribution of electron density by measuring the polarized brightness. For the purpose of technical demonstration, we intend to observe the total solar eclipse in 2017 August for the filter system and to perform a stratospheric balloon experiment in 2019 for the engineering model of the coronagraph. The coronagraph is planned to be installed on the ISS in 2021 for addressing a number of questions (e.g. coronal heating and solar wind acceleration) that are both fundamental and practically important in the physics of the solar corona and of the heliosphere.

• 한국태양에너지학회:학술대회논문집
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• 2012.03a
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• pp.457-462
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• 2012

Daylighting software is an important component to predict the performance of daylighting system in advance of a field demonstration study with installing them in buildings. PHOTOPIA is a powerful software to generate a candela distribution curve(CDC) of an active daylighting system like a tracking dish concentrator. With PHOTOPIA, a set of candela distribution curves was generated under clear sky conditions and different solar altitude angles. The candela distribution curves were then imported to RADIANCE for rendering and analysis on the daylighting performance of a tracking dish concentrator when it installed in a actual class room without windows. As a result, the daylight collection efficiency of the dish concentrator was 68.4% when we assumed that there was no tracking error. It was found that candela(cd) and total lumens(lm) increased with solar altitude rising, whereas the distribution angle was fixed. The illuminance uniformity on the work plane in the class room was relatively low, 0.12, while the illuminance uniformity on the area of $2.7m^2$ to which the light was illuminated was considerably high, 0.60. The maximum illuminance was 1,340lux with a solar altitude angle of 80 degrees.

• International Journal of Highway Engineering
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• v.16 no.6
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• pp.9-17
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• 2014

PURPOSES : The purpose of this study is to assess removal efficiency of non-point pollutants and applicability for non-point pollutant reduction facilities by conducting the demonstration project operation. METHODS : In order to analyze removal efficiency of non-point pollutants for facilities such as a grassed swale, a small constructed wetland, a free water surface wetland, a horizontal sub-surface flow wetland, and a sand filtration, the field data including specifications of facilities, rainfall, inflow and runoff rainfall effluent etc. was acquired after occurring rainfall events, and the acquired data was analyzed for removal efficiency rate to assess road non-point pollutants facilities using event mean concentration (EMC) and summation of load (SOL) methods. RESULTS : The results of analyzing rainfall effluent, non-point pollutant sources showed that total suspended solid (TSS), chemical oxygen demand (COD), biochemical oxygen demand (BOD), total nitrogen (TN), total phosphorus (TP), chrome (Cr), zinc (Zn), and lead (Pb) can be removed through non-point pollutant reduction facilities by 60.3% ~ 100%. Especially removal efficiency of TSS, COD and BOD is relatively higher than removal efficiency of other non-point pollutant sources in all kind of non-point pollutant facilities. CONCLUSIONS : Based on the result of this study, even though natural type of non-point pollutant reduction facilities for roads occupy small areas comparing with drainage basin areas, most of non-point pollutant sources would be removed through the facilities.

• Transactions of the Society of Information Storage Systems
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• v.1 no.2
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• pp.155-160
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• 2005

In this paper, the channel decoder promising reliable data retrieving in noisy holographic channel has been developed for holographic WORM(write once read many) system. It covers various DSP(digital signal processing) blocks, such as align mark detector, adaptive channel equalizer, modulation decoder and ECC(error correction code) decoder. The specific schemes of DSP are designed to reduce the effect of noises in holographic WORM(H-WORM) system, particularly in prototype of DAEWOO electronics(DEPROTO). For real time data retrieving, the channel decoder is redesigned for FPGA(field programmable gate array) based hardware, where DSP blocks calculate in parallel sense with memory buffers between blocks and controllers for driving peripherals of FPGA. As an input source of the experiments, MPEG2 TS(transport stream) data was used and recorded to DEPROTO system. During retrieving, the CCD(charge coupled device), capturing device of DEPROTO, detects retrieved images and transmits signals of them to the FPGA of hardware channel decoder. Finally, the output data stream of the channel decoder was transferred to the MPEG decoding board for monitoring video signals. The experimental results showed the error corrected BER(bit error rate) of less than $10^{-9}$, from the raw BER of DEPROTO, about $10^{-3}$. With the developed hardware channel decoder, the real-time video demonstration was possible during the experiments. The operating clock of the FPGA was 60 MHz, of which speed was capable of decoding up to 120 mega channel bits per sec.