Key Engineering Materials Vols. 277-279

Abstract: In this paper we show that the circularity and the planar functions of an intuitionistic fuzzy sphere converge to one of a crisp sphere as a fuzzy sphere shapes itself more and more like a crisp sphere.

Abstract: The main objective of this study is to observe and extract relevant geographical information of areas afflicted with floods using KOMPSAT-1 EOC image data. The satellite images taken on September 2, 2002 of the downstream of the river of Nakdong in the province of South Gyeongsang afflicted with floods at that time are used for the purpose of demonstration. To extract information which is the boundary lines and area in flood disaster area should be made to the ortho-image with characteristic of map. The generation of ortho-images involve sensor modeling using control points and DEM to restore a geometric relation of a satellite, its images and ground of which images are provided by the satellite. Candidate areas for edge extraction are selected based on ortho-corrected images through edge preserving smoothing method, high-pass filter and Prewitt operator. Based on the generated candidate areas, edges are extracted by use of edge extracting algorithm. The resultant extracted edges enable the overall status of flooded areas to be promptly grasped. This paper demonstrates such scope of utilization of satellite data for investigation and recovery of areas damaged by natural disasters.

Abstract: The great fires were detected through the Moderate Resolution Imaging Spectroradiometer (MODIS) observations over Northeast Asia. The large amount of smoke produced near Lake Baikal was transported to East Asia using high Aerosol Optical Thickness (AOT) as seen through the satellite images. The smoke pollution from the Russian forest fires would sometimes reach Korea through Mongolia and eastern China. In May 2003, a number of large fires blazed through eastern Russian, producing a thick, widespread pall of smoke over much of East Asia. This study focuses on the identification of the carbon monoxide (CO) for MOPITT released from MOPITT primarily into East Asia during the Russian Fires. In the wake of the fires, the 700hPa MOPITT retrieved CO concentrations which reached up to 250ppbv. Smoke aerosol retrieval using a separation technique was also applied to the MODIS data observed in 14-22 May 2003. Large AOT, 2.0 ~ 5.0, was observed over Korea on 20 May 2003 due to the influence of the long range transport of smoke aerosol plume from the Russian Fires.

Abstract: The Chiljeongsan Naepion (七政算內篇) and the Chiljeongsan Oepion (七政算外篇), landmark achievements in the field of astronomical calendars in Korea, were published in the 26th year (1444 A.D.) of the reign of King Sejong (世宗, 1418-1450 A.D.) of the Choseon(朝鮮) dynasty, firmly establishing the calendar making system of Choseon. The Chiljeongsan Naepion adopts the conventions of the Shoushi calendar (授時曆) of the Yuan (元) dynasty (1280-1367 A.D.) of China, but also consults the Datong calendar (大統曆) and the modified Datong-li Tongkue (大統曆通軌), published during the Ming(明) dynasty (1368-1643 A.D.) of China. Furthermore, the Chiljeongsan Naepion corrects errors in the referred Chinese calendars and adds calculations of sunrise and sunset at the latitude of Seoul. On the other hand, the Chiljeongsan Oepion adopts the conventions of the Huihui calendar (回回曆) of Arabia translated and edited by the Arabian astronomer Mashayihei (馬沙亦黑) [1] in China. The Huihui calendar uses an Islamic theory of epicycles for its treatment of lunar and planetary motions. This means that aspects of the Ptolemaic system had been introduced into the Korean astronomy in the 15th century The calendar of the Choseon dynasty was made by the method of Chiljeongsan Naepion, but the calculations of solar and lunar eclipses and five planet’s positions are compared to those of the Chiljeongsan Oepion. In this paper, we discussed mainly the differences of the calculation methods of the solar positions in both calendars.

Abstract: Outgassing, the evolution of gas from the material in a vacuum, is not only a source of micro contamination in a semiconductor or the flat display panel production process, but it also a limitation factor in the ultra clean process of nano-technology. The outgassing from the materials of satellites and spacecrafts must be controlled for increased safety and function because space is also a vacuum environment. Several methods are used in outgassing measurement in general, but there is no one method suitable for obtaining all outgassing data. The most suitable method for a particular application must be chosen by the experimenter or user. Three types of outgassing measurement systems were fabricated and characterized, ‘Throughput method,’ ‘Rate of Rise method’ and ‘Mass Loss Measurement method’. The outgassing rates of many kinds of materials were measured and characterized using these systems.

Abstract: This study aims to analyze the synergic effect of integrating two distinctive satellite remote sensor data (optical and microwave imagery) for land cover classification. The study area covers diverse land cover types in the Western coastal region of the Korean peninsula. Eleven land cover types were classified using several datasets of combined Landsat ETM+ and Radarsat synthetic aperture radar (SAR) data as well as only a single dataset of either ETM+ or SAR data alone. Furthermore, we introduced a texture image that was derived from the SAR data. The synergic effect of these combined datasets was evident by both image interpretation and computerassisted classification. The overall classification accuracy of the combined datasets was improved to 74.60% as compared to the 69.35% accuracy of using ETM+ data alone.

Abstract: The satellite RF system is an essential part of the control and management of a satellite from the ground station and provides a communication link during the entire satellite mission life. The RF system should be fully evaluated for reliability and stability on the ground, as defined by the requirements of the satellite mission. The evaluation of an RF system can be verified by measuring the RF link parameter and then comparing and analyzing the result with the RF system requirements. Since the system test for satellites requires advanced technology and has a high cost with limited time, however, it is difficult to access technically for many parts. This paper describes the design and verification of the RFTS (Radio Frequency Test Set) and the RTS (RFTS Test Software), which AITC developed in KARI to evaluate a satellite RF system. The developed test system was used to perform an RF functional test on an ETB (Engineering Test Bed), and the RFTS’s full functions were debugged to provide a reliable function for the KOMPSAT-2 Satellite Test. The RFTS showed a high degree of reliability, conformity and repeatability for each test case at any time. It is now being applied to the RF system evaluation test of KOMPSAT-2 FM during KOMPSAT-2’s integration and environment test phases. Hereinafter, this system can be applied to the next generation of satellites as well as to the RF payload system as a unique KOMPSAT series RF test system.

Abstract: We present high-resolution chemical abundance results of 15 metal-poor dwarf stars in the solar neighborhood. Our metallicity measurements are in a good agreement with previous estimates. The stars under investigation have metallicities ranging from -1.6 to -2.8 with the mean value of [Fe/H] = -2.28. The mean values of elemental abundances are [O/Fe] = 0.73, [Na/Fe] = -0.16, [Ca/Fe] = 0.28, and [Ti/Fe] = 0.60. Our results are found to be consistent with those of giant metal-poor stars.

Abstract: The objective of this study is to enhance neural-network guidance to consider the impact condition. Missile impact angle error, a measure of the degree to which the missile is not steering for a head-on attack, can have a significant influence on the final miss distance. Midcourse guidance using neural networks is employed to reduce the deviation angle from head-on effectively in the three-dimensional space. In addition, a coordinate transformation is introduced to simplify the three-dimensional guidance law and reduce training data for the neural network. Computational results show that the current neural-network guidance law with the coordinate transformation can be used to reduce the impact angle errors.

Abstract: We present intermediate-band spectral energy distributions (SED) of QSO candidates in 1 square degree field around Leo Triplet. Leo Triplet consists of three galaxies, NGC3623, 3627, and 3628, which appear to interact with each other. BATC survey data of 15 intermediate-band filters offer excellent opportunity to study low spectral resolution SED for thousands of point sources in the field simultaneously. In order to derive SED of high signal to noise ratio, we have combined hundreds of images for each passband and made photometric measurements for every point sources in the combined images. Two dozens of new QSO candidates are identified based on the shape of derived SED curves. We also investigated SEDs of known QSO candidates in the field, but their SED differs greatly from model predictions made for cataloged redshift. While we plan to carry out spectroscopic observations for further confirmation, this indicates that QSO identification based on objective prism and X-ray methods should be taken more cautiously.