• 한국광학회:학술대회논문집
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• 한국광학회 2009년도 창립 20주년기념 특별학술발표회
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• pp.298-299
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• 2009

Use of a DLP-beam projector is proposed to measure solar cell quantum efficiency distribution. The measurement requires a good spatial uniformity of the beam from the projector. We measured the spectral power distribution of the beam projector and the spatial uniformity of the white beam. By changing the gray level of the white beam at the measured spatial points, we improved the spatial illuminance uniformity to be about 2 % which was otherwise as much as 400 %.

• International Journal of Internet, Broadcasting and Communication
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• 제11권3호
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• pp.27-33
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• 2019

Quadrature spatial modulation (QSM) utilizes the in-phase and quadrature spatial dimensions to transmit the real and imaginary parts, respectively, of a single signal symbol. Improved QSM (IQSM) builds upon QSM to increase the spectral efficiency by transmitting the real and imaginary parts of two signal symbols using antenna combinations of size of two. In this paper, we propose a double QSM (DQSM) scheme that transmits the real and imaginary parts of two signal symbols independently through any of the transmit antennas. The two signal symbols are drawn from two different constellations of the same size with the first symbol drawn from any of the conventional modulation sets while the second is drawn from an optimally rotated version of the first constellation. The optimum rotation angle is obtained through extensive Monte Carlo simulations to minimize the bit error rate (BER) of the system. Simulation results show that for a given spectral efficiency, DQSM performsrelatively close to IQSM while requiring a smaller number of transmit antennas, and outperformsIQSM by up to 2 dB when the same number of antennas are used.

• ETRI Journal
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• 제45권4호
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• pp.615-626
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• 2023

Under limited transmission conditions, many factors affect the efficiency of video transmission. During the flight of an unmanned aerial vehicle (UAV), frequent network switching often occurs, and the channel transmission condition changes rapidly, resulting in low-video transmission efficiency. This paper presents an efficient video coding flow for UAVs working in the 5G nonstandalone network and proposes two bit controllers, including time and spatial bit controllers, in the flow. When the environment fluctuates significantly, the time bit controller adjusts the depth of the recursive codec to reduce the error propagation caused by excessive network inference. The spatial bit controller combines the spatial bit mask with the channel quality multiplier to adjust the bit allocation in space to allocate resources better and improve the efficiency of information carrying. In the spatial bit controller, a flexible mini graph is proposed to compute the channel quality multiplier. In this study, two bit controllers with end-to-end codec were combined, thereby constructing an efficient video coding flow. Many experiments have been performed in various environments. Concerning the multi-scale structural similarity index and peak signal-to-noise ratio, the performance of the coding flow is close to that of H.265 in the low bits per pixel area. With an increase in bits per pixel, the saturation bottleneck of the coding flow is at the same level as that of H.264.

• International journal of advanced smart convergence
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• 제8권3호
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• pp.61-68
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• 2019

Spatial modulation (SM) is the first proposed space modulation technique. By further utilizing the quadrature spatial dimension, quadrature spatial modulation (QSM) has been developed as an amendment to SM system to enhance the overall spectral efficiency. Both techniques are capable of entirely eliminating interchannel interference (ICI) at the receiver. In this paper, we propose a simple adaptive hybrid switching transmission scheme to obtain better system performance than SM and QSM systems under a fixed transmission date rate. The presented modulator selection criterion for switching between spatial modulator and quadrature spatial modulator is based on the larger received minimum distance of spatial modulator and quadrature spatial modulator to exploit the spatial channel freedom. It is shown through Monte Carlo simulations that the proposed hybrid SM and QSM switching system yields lower error performance than the conventional SM and QSM systems under the same fixed data rate and thus can provide signal to noise ratio (SNR) gain.

• 한국대기환경학회지
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• 제9권3호
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• pp.236-241
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• 1993

Recently, with the ourdoor air pollution, the indoor air pollution devided into living environment and working environment are raised as the problem of indoor space. Also, the more time lived in indoor space, the larger the influence of indoor air pollution. Therefore in this study, the spatial variation of ventilation efficiency was estimated through the experiment using a physical model. The experiment using a physical model. The experiment was conducted in two category; the central zone of ventilated air flow and the corner zone. As the result of experiment, high ventilation efficiency (90$\sim$108%) was shown in the central zone of ventilated air flow. Whereas low ventilation efficiency (46$\sim$77%) was shown in the corner zone. In conclusion, when the designing of ventilation was planned, the zone showed low ventilation efficiency should be considered.

• 한국환경복원기술학회지
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• 제20권6호
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• pp.133-149
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• 2017

As cities face increasing problems such as aging, environmental pollution and growth limits, we have been trying to incorporate sustainability into urban planning and related policies. However, it is very difficult to generate a 'sustainable spatial plans' because there are trade-offs among environmental, society, and economic values. This is a kind of non-linear problem, and has limitations to be solved by existing qualitative expert knowledge. Many researches from abroad have used the meta heuristic optimization algorithms such as Genetic Algorithms(GAs), Simulated Annealing(SA), Ant Colony Optimization(ACO) and so on to synthesize competing values in spaces. GAs is the most frequently applied theory and have been known to produce 'good-enough plans' in a reasonable time. Therefore we collected the research on 'spatial optimization model based GAs' and analyzed in terms of 'study area', 'optimization objective', 'fitness function', and 'effectiveness/efficiency'. We expect the results of this study can suggest that 'what problems the spatial optimization model can be applied to' and 'linkage possibility with existing planning methodology'.

• 대한원격탐사학회지
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• 제34권1호
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• pp.89-99
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• 2018

Spatial downscaling is often applied to coarse scale satellite products with high temporal resolution for environmental monitoring at a finer scale. An area-to-point regression kriging (ATPRK) algorithm is regarded as effective in that it combines regression modeling and residual correction with area-to-point kriging. However, an open source tool or package for ATPRK has not yet been developed. This paper describes the development and code organization of an R-based spatial downscaling tool, named R4ATPRK, for the implementation of ATPRK. R4ATPRK was developed using the R language and several R packages. A look-up table search and batch processing for computation of ATP kriging weights are employed to improve computational efficiency. An experiment on spatial downscaling of coarse scale land surface temperature products demonstrated that this tool could generate downscaling results in which overall variations in input coarse scale data were preserved and local details were also well captured. If computational efficiency can be further improved, and the tool is extended to include certain advanced procedures, R4ATPRK would be an effective tool for spatial downscaling of coarse scale satellite products.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2002년도 International Meeting on Information Display
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• pp.939-942
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• 2002

The optically addressed and electrically addressed spatial phase only light modulators without pixelized structures have been developed. A sufficient phase modulation capability and a high diffraction efficiency of these devices are useful for practical applications.

• 한국공간구조학회지
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• 제5권3호
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• pp.26-32
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• 2005

• 건축역사연구
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• 제22권2호
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• pp.43-54
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• 2013

Compared to Early Chosun Dynasty, the spatial structure of most local Eupseongs of Korea had a standardized change with the expansion and spread of the Rye-hak(禮學:a study of confucius Rite). Meanwhile in the process of rebuilding Eupseongs there was a tendency of relocation of the local government offices(官衙) and its attached facilities in terms of functions and use. Although it was PyeongSanseong Miryang Eupseong had an unreasonable spatial structure locating Gaeksa(客舍; accommodation house for visitors) in the middle of the local government office complex, and Dongheon(東軒;main office building) in the east of it before the Japanese Invasion of Korea in 1592. However with the reorganization of spatial Structure of local Eupseongs after the Japanese invasion Gaeksa was moved to the foot of Adongsan where commanded a fine view of river. Dongheon was moved to the center of Eupseong for the effective management of its auxiliary organizations. It was because road system and administrative efficiency had a serious effect on deciding the location of the local government office and its attached facilities. After the Japanese invasion Hyangchoeng(鄕廳), having been out of Eupseong, also was moved to the independent location within Eupseong separate from Dongheon and Gaeksa. It seemed to take into account the autonomy of Hyangchoeng. Dongheon, Gaeksa, and Hyangchoeng which are the crucial facilities of Milyang Eupseong were arranged at each angular point of big triangle. In order to enhance the administative efficiency, the attached administrative facilities were arranged surrounding Dongheon and Hyangchoeng. The spatial structure of Milyang Eupseong in the late Choseon dynasty was of great difference from that of uniformly organized system of early Choseon Period. It was because the development of administrative function, the pursuit of efficiency, and commercial progress had a great impact on the change of urban space.