• Atmosphere
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• v.15 no.3
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• pp.167-178
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• 2005

Using the FSSP-100(FSSP) and Microwave Radiometer (MWR), the fog and clear day characteristics (the size and number concentration of fog particles and the liquid water content) have been measured and analyzed at Daegwallyoung observation site ($37^{\circ}41^{\prime}N$, $128^{\circ}45^{\prime}E$) during 27 - 30 November 2003 (fog day) and 19 January 2004 (clear day). During the fog days, the measured fog-particle size by using FSSP is 0.8~8.4 ${\mu}m$, which is similar to the WMO typical value, the fog number concentration varies from 121 to 200 count ($No./cm^2$) and the fog liquid water content from $0.018g/m^3-0.1g/m^3$ in the site. The precipitable water vapor obtained by the MWR, showing the correlation coefficient $R^2$=0.83 between the total precipitable water vapor obtained from the radio sonde and MWR, shows the larger amount (0.75-8.3 cm) during the fog days than the clear-sky data (0.2 cm).

• KIEAE Journal
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• v.15 no.1
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• pp.83-88
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• 2015

This study aims to develope the light-weight PV blinds with windows and to investigate the shading analysis by the control conditions. For the study, the polycarbonate characteristics and coating methods are analyzed and the PV blind design for a small office is suggested. Also, the mock-up model of a suggesting system was made. The field tests were controled based on a solar altitude under clear sky conditions. As results, it is necessary to use a polycarbonate instead of a tempered glass for a light-weight PV. The shading effects of blind systems are high in slat angle $30^{\circ}$ and low in $0^{\circ}$. Also, the shading ratio is more affected by solar latitude than solar altitude. The shading change rate is relevantly constant on the solar altitude.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2003.05b
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• pp.197-198
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• 2003

최근 미국 및 유럽의 선진국에서는 시민에게 맑은 하늘을 체감적으로 느낄 수 있는 Clear Sky(푸른하늘)를 실현하기 위하여 시정(visibility)분야에 대한 연구가 급진적으로 확산되어 가고 있다. 미국의 IMPROVE, 북미대륙(미국, 캐나다. 멕시코) 공동연구인 NARSTO, 유럽대륙의 EURO-TRAC II 등, 선진국의 연구기관들은 인체에 유해할 뿐만 아니라 시정장애에 영향이 지배적인 미세입자(Dp 〈 2.5$\mu\textrm{m}$)에 대한 화학적이며, 광학적인 특성을 실시간으로 관측 및 분석하도록 권고하고 있다. 현재까지의 우리나라의 시정변화에 대한 분석은 광학적인 관측에 있어서는 실시간으로 시행되어 왔으나, 에어로졸의 화학적인 분석에 있어서는 일일 관측이 일반적인 관측간격이었다. (중략)

• Journal of The Korean Astronomical Society
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• v.35 no.2
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• pp.87-95
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• 2002

We have conducted VI CCD photometry of the open cluster NGC 6819 in order to understand the effects of dynamical evolution in old open clusters. Our photometry covers 18' $\times$ 18' on the sky, centered on the cluster, which seems to cover the whole cluster field. Our photometry reaches down to V $\approx$ 20.5, which allows us to analyze the luminosity function and spatial distribution of stars brighter than Mv $\approx$ 8.5. There is a clear evidence for mass segregation in NGC 6819, i.e., the giants and upper main-sequence stars are concentrated in the inner regions, whereas the lower main-sequence stars distribute almost uniformly throughout the cluster. The luminosity function of the main-sequence stars of NGC 6819 is almost flat. The flat luminosity function indicates that a large number of low mass stars has escaped from the cluster unless its initial mass function is much different from the Salpeter type (${\phi}(m){\propto} m^{-(1+x)},x = 1.35$).

• Proceedings of the KSRS Conference
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• 2005.10a
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• pp.34-37
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• 2005

An efficient and robust neural network-based scheme is introduced in this paper to perform automatic cloud detection. Unlike many existing cloud detection schemes which use thresholding and statistical methods, we used the artificial neural network methods, the multi-layer perceptrons (MLP) with back-propagation algorithm and radial basis function (RBF) networks for cloud detection from Geostationary satellite images. We have used a simple scene (a mixed scene containing only cloud and clear sky). The main results show that the neural networks are able to handle complex atmospheric and meteorological phenomena. The experimental results show that two methods performed well, obtaining a classification accuracy reaching over 90 percent. Moreover, the RBF model is the most effective method for the cloud classification.

• Journal of the Korean Operations Research and Management Science Society
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• v.29 no.4
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• pp.141-157
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• 2004

In this paper, we consider broadband satellite systems using MF-TDMA(Multi-Frequency Time Division Multiple Access) scheme. First, we analyze return link, superframe structure, and QoS( Quality of Service) parameters in broadband satellite systems, and mathematically formulate the QoS-based optimal timeslot allocation problem as a nonlinear integer programming problem for broadband satellite systems with clear-sky and rain-fade satellite terminals, and multiple data classes. Next, we modify the proposed problem to solve it within in a fast time, and suggest the QoS-based optimal timeslot allocation scheme. Extensive simulation results show that the proposed scheme finds an optimal solution or a near optimal solution within 5ms at Pentium IV PC.

• The Journal of the Korean dental association
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• v.22 no.11 s.186
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• pp.973-978
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• 1984

The authors observed a case of Burkitt's lymphoma, occurred in the mandible, of 6-year-old female patient who admitted to the Department of Oral Radiology, Kyung Hee University Medical Center. The serial radiograms, clinical findings, and microscopid findings had been taken and obtained following results: 1. In serial radiograms, invasive and infiltrative bone destruction in the both mandibular body region was observed. Perforation and erosion of cortical plate of the mandibular angle area and loss of alveolar lamina dura in involved teeth were also noticed. 2. In microscopic findings, a monotous overgrowth of undifferentiated monomorphic lymphoreticular cells found. Macrophages with and abundant clear cytoplasm are usually found scattered uniformly throughout the tumor, producing the very characteristic 'starry-sky' appearance.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• v.4 no.4
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• pp.263-271
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• 2000

To investigate the distribution of air pollutants dispersion in the horizontal wind fields, a chaff release experiment was carried out by an airplane. The temporal and spatial variations of a chaff plume from an elevated point source using the WSR-88D(NEXRAD) radar. The observed profiles of radar reflectivity were compared with the Gaussian diffusion model at slightly unstable atmospheric condition. The present study shows that the distributions of radar reflectivity from chaffs and their concentration by the model are in general agreement with time variation. The dispersion coefficients in downwind($\sigma$(sub)x) and crosswind($\sigma$(sub)y) spread data exceeded what has generally been found at Pasquill and Brigg\`s estimates. As a result, it was clearly shown that horizontal and vertical diffusion coefficients are more accurately determined as compared with theoretical coefficients. At longer diffusion distances(than 10km), a radar observation provided the determination of maximum range and diffusion height more qualitatively, too.

• Architectural research
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• v.4 no.1
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• pp.17-23
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• 2002

Daylight simulation methods play an important role for the prediction of daylight illuminances in underground spaces. This daylighting project is designed to compare daylight prediction methods for the application of large underground spaces. In this study, actual measurements were conducted under overcast and clear sky conditions. Also, computer simulations by Radiance, Superlite IEA 2.0 program and scale model testings were conducted to be compared with measured data. Simulation results show the data by Radiance, Superlite IEA 2.0 and the scale model are similar to the measured data in two underground spaces in Seoul. Overall results show that Radiance and superlite IEA 2.0 proved to be useful to predict daylight illuminances even in big underground spaces.

• Proceedings of the KSRS Conference
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• 2007.10a
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• pp.302-305
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• 2007

During the CareBeijing campaign in September 2006, Imaging Differential Optical Absorption Spectroscopy (IDOAS) measurements were made over the city of Beijing, China using a spatial resolution of 146 pixels horizontally and 61 pixels vertically, each with a field of view of $0.133^{\circ}$ and $0.072^{\circ}$ in the horizontal and vertical directions, respectively. Using Fraunhofer reference spectra (FRS) for the evaluation of data for two consecutive days, the diurnal variation of $NO_2$ distributions was determined from data measured every single hour from 08:00 until 16:00 on September 9 and 10. Both days presented a fairly clear sky with high visibility. The setup allowed detailed images of the low surface $NO_2$ distribution over Beijing. Images with less than a 30-min temporal resolution showed variation of plume dispersal in both horizontal and vertical directions. An in-situ measurement was also conducted. Results from both instruments are interpreted by considering local emission sources and wind conditions.