• Proceedings of the Korean Vacuum Society Conference
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.416-416
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• 2016

Organic-inorganic metal halide perovskite solar cells have received attention because it has a number of advantages with excellent light harvesting, high carrier mobility, and facile solution processability and also recorded recently power conversion efficiency (PCEs) of over 20%. The major issue on perovskite solar cells have been reached the limit of small area laboratory scale devices produced using fabrication techniques such as spin coating and physical vapor deposition which are incompatible with low-cost and large area fabrication of perovskite solar cells using printing and coating techniques. To solution these problems, we have investigated the feasibility of achieving fully printable perovskite solar cells by the blade-coating technique. The blade-coating fabrication has been widely used to fabricate organic solar cells (OSCs) and is proven to be a simple, environment-friendly, and low-cost method for the solution-processed photovoltaic. Moreover, the film morphology control in the blade-coating method is much easier than the spray coating and roll-to-roll printing; high-quality photoactive layers with controllable thickness can be performed by using a precisely polished blade with low surface roughness and coating gap control between blade and coating substrate[1]. In order to fabricate perovskite devices with good efficiency, one of the main factors in printed electronic processing is the fabrication of thin films with controlled morphology, high surface coverage and minimum pinholes for high performance, printed thin film perovskite solar cells. Charge dissociation efficiency, charge transport and diffusion length of charge species are dependent on the crystallinity of the film [2]. We fabricated the printed perovskite solar cells with large area and flexible by the bar-coating. The morphology of printed film could be closely related with the condition of the bar-coating technique such as coating speed, concentration and amount of solution, drying condition, and suitable film thickness was also studied by using the optical analysis with SEM. Electrical performance of printed devices is gives hysteresis and efficiency distribution.

• Publications of The Korean Astronomical Society
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• 제32권1호
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• pp.83-85
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• 2017

We conducted an unbiased near- to mid-infrared imaging and spectroscopic survey of the Large Magellanic Cloud (LMC) as a part of the AKARI Mission Program "Large-area Survey of the LMC" (LSLMC, PI: T. Onaka). An area of about 10 square degrees of the LMC was observed by five photometric bands (3.2, 7, 11, 15, and $24{\mu}m$) and a low-resolution slitless prism ($2-5{\mu}m$, R ~20) equipped with AKARI /IRC. We constructed and publicly released photometric and spectroscopic catalogues of point sources in the LMC based on the survey data. The catalogues provide a large number of near-infrared spectral data, coupled with complementary broadband photometric data. Combined use of the present AKARI LSLMC catalogues with other infrared point source catalogues of the LMC possesses scientific potential that can be applied to various astronomical studies.

• Journal of Environmental Impact Assessment
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• 제10권1호
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• pp.49-57
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• 2001

With reducing coal mining industry the number of coal mine sites between 1988 and 1998 was dropped from 347 to 12. Since the abandoned coal mine sites have been kept without any cares, they have raised various environmental and safety problems. Then, Korean government initiated a special law in 1995 for enhancing economic conditions and solving environmental problems with promoting developmental projects in the abandoned mining sites. As a result, casino business in Chungsun area has been opened to publics, and other large-scale developments such as ski slopes and resorts are planned. In addition, Boryung area in Chungchung province also will launch a large-scale project building golf courses. Based on this developmental trend, it is expected that lots of large-scale developments in other places will be taken place. In general, the large-scale developments have caused various environmental problems, and, thus, environmental aspects should be considered in a decision-making process. This paper examine the status of the abandoned mine sites in Korea and U.S. and suggests the alternatives of its utilization.

• Transactions of the Korean Society of Mechanical Engineers
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• 제14권3호
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• pp.636-645
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• 1990

Analytically induced wear mechanism of elastic body under Hertzian contact is applied in acutual wear test of ceramics. There are two types of wear in ceramics, a large scale wear and a small scale wear. The large scale wear is commensurable with Hertzian contact area and the small scale wear with real contact area. Nondimensional parameter, S$_{c}$, is introduced and fully examined to estimate or predict wear rate of ceramics. Ceramic wear for S$_{c}$.leq.0.8 is in small scale wear and for S$_{c}$;geq.1.6 in large scale wear. wear.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• 제14권1호
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• pp.39-47
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• 1996

This paper is to provide land cover classification techniques for large area ranged in different pathos by classifying Landsat TM data of Jeonnam province. The analyses proceeded by individual scene because acquired dates are not same in different pathes. In this processing, troubles had happened something like variation of classes can be classified in two scenes and choice problem about overlapped area. Since spatial effects in large area affect data values, it was difficult to make a selection of classes and training fields. we could present a solution about these problems by trial and error method, and found that Bayesian maximum likelihood classification and majority filtering were effective to improve classification accuracy.

• Spatial Information Research
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• 제18권1호
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• pp.11-17
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• 2010

The present study attempts to provide the practical methodology to determine the spatial boundary of trade area, not depending on conventional circle-based regional analysis, but adopting dimension-diverging conception based on GIS and road connectivity by exemplifying a large-scale discount store with an outlook to enhance accuracy and reliability in trade area analyzing. Unlike the preliminary researches frequently relying on circular form of interpretation which were not likely to exclude obstacles blocking the accessibility to trade areas, the method suggested by the study is to suggest an alternative way for demarcating the trade areas more practically with better access by excluding in-between obstacles. Finally, we show verification of proposed cost models and performance by join strategy.

• Journal of the Korean housing association
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• 제27권3호
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• pp.23-30
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• 2016

Among the unearthed House ruins in Gyeongju of the capital of Silla period, the ruins to see the overall appearance of building arrangement is the ruins of Silla capital S1E1 area, Inwangdong 412, and the Jaemaejeong. In this study, the characteristics of urban house arrangement of the Unified Silla period was analyzed that, through a review of the arrangement relationship between the gate and the individual buildings found in these ruins. The urban house of the Unified Silla period was surrounded with wall, and the way to distinguish between functional areas within it are shown differently, depending on the size of the house. In other words, the small house was divided each area by installation of inner fence, and the large house was by arranging attached buildings. Thai is, the central area is not divided by inner fence is the Characteristics that is different from the small house. And in all houses, a large courtyard is located in the front of main building. Conatruction of the courtyard determines the location and direction of the main building. And the each area has external space of courtyard in the center.

• Journal of Electrical Engineering and Technology
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• 제13권1호
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• pp.1-10
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• 2018

Wide-area monitoring of tree-related high impedance fault (THIF) efficiently contributes to increase reliability of large-scaled network, since the failure to early location of them may results in critical lines tripping and consequently large blackouts. In the first place, this wide-area monitoring of THIF requires managing the placement of sensors across large power grid network according to THIF detection objective. For this purpose, current paper presents a framework in which sensors are distributed according to a predetermined risk map. The proposed risk map determines the possibility of THIF occurrence on every branch in a power network, based on electrical conductivity of trees and their positions to power lines which extracted from spectral data. The obtained possibility value can be considered as a weight coefficient assigned to each branch in sensor placement problem. The next step after sensors deployment is to on-line monitor based on moving data window. In this on-line process, the received data window is evaluated for obtaining a correlation between low frequency and high frequency components of signal. If obtained correlation follows a specified pattern, received signal is considered as a THIF. Thereafter, if several faulted section candidates are found by deployed sensors, the most likely location is chosen from the list of candidates based on predetermined THIF risk map.

• Nuclear Engineering and Technology
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• 제53권8호
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• pp.2640-2645
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• 2021

We report the development of a gamma-ray imaging device, named Large-Area Hybrid Gamma Imager (LAHGI), featuring high imaging sensitivity and good imaging resolution over a broad energy range. A hybrid collimation method, which combines mechanical and electronic collimation, is employed for a stable imaging performance based on large-area scintillation detectors for high imaging sensitivity. The system comprises two monolithic position-sensitive NaI(Tl) scintillation detectors with a crystal area of 27 × 27 cm² and a tungsten coded aperture mask with a modified uniformly redundant array (MURA) pattern. The performance of the system was evaluated under several source conditions. The system showed good imaging resolution (i.e., 6.0-8.9° FWHM) for the entire energy range of 59.5-1330 keV considered in the present study. It also showed very high imaging sensitivity, successfully imaging a 253 µCi ¹³⁷Cs source located 15 m away in 1 min; this performance is notable considering that the dose rate at the front surface of the system, due to the existence of the ¹³⁷Cs source, was only 0.003 µSv/h, which corresponds to ~3% of the background level.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2008년도 춘계학술대회 논문집
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• pp.444-444
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• 2008