• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.59-62
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• 2012

지진해일은 한 번 발생하면 매우 큰 피해를 주는 자연재해 중 하나이다. 특히 최근에 일어나고 있는 지진해일에서 주목할 점은 해저지진의 규모가 커짐에 따라 그로인해 생긴 지진해일이 발생 인접지역에만 피해를 주는 것이 아니라 2010년 칠레지진과 2011년 동일본 대지진으로 생긴 지진해일과 같이 태평양을 가로질러 먼 거리에까지도 영향을 준다는 것이다. 하지만 이러한 지진해일에 대하여 피해 경감 및 재해대책을 수립할 때는 지진해일의 발생시간에 대한 정확한 예측이 불가능하기 때문에 연구하는데 여러 가지 어려움이 있으므로 역사 및 가상지진해일의 수치모의실험 결과를 이용한다. 그래서 이렇게 활용성이 높은 지진해일 수치모의실험 결과의 정확도 검증을 위하여 본 연구를 시작하게 되었다. 본 연구에서 사용한 수치기법으로는 분산항을 제외한 선형 천수방정식을 이용하였고, 이를 차분하는 과정에 나타나는 수치분산을 조정하여 선형 Boussinesq 방정식의 분산항을 대체할 수 있도록 하였다. 그리고 실제 동일본 대지진으로 발생한 지진해일을 전파모의하여 분산항을 고려한 수치모의실험 결과와 이 당시 태평양에서 수면변화양상을 기록한 DART buoy 관측값과의 비교를 통해 정확도를 확인해보았다.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.858-861
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• 2012

2010년 태풍 '뎬무'가 제주지역에 내습했을 때, 한천 상 하류에 위치한 하천유출량 관측소의 자료와 저류지 유입량 자료를 이용하여 한천저류지 운영이 하류지역 홍수저감에 미치는 영향을 분석하였다. 분석결과, 하류지역에서의 실제 하천수위는 3.44m를 기록하였으나, 수위-유출량 관계식, 유출전파속도, 저류지 유입량를 활용하여 저류지가 운영되지 않았을 경우 하류지역 하천수위는 4.16m로 예측되어, 저류지 운영으로 하천유출수의 일부가 저류지로 유입됨으로써 하류지역의 하천수위를 0.72m 하강시킨 것으로 분석되었다.

• Journal of the Institute of Convergence Signal Processing
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• v.15 no.4
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• pp.183-191
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• 2014

This paper describes the development of the observational data transmission algorithm for high-speed network in radio astronomy. For the preprocessing of VLBI data observed by radio telescope, data transmission algorithm uses the VDIF specification, VDIFCP, and UDP protocol by transferring VLBI data stored in a massive storage server with one-to-one correspondence between the server and the RVDB of Daejeon correlator. A transmission method is proposed, which reads the recorded data in Mark5B VSI format and trnasmits 2048 Mbps VLBI data by software through UDP packet transmission, while RVDB system is waiting for the transmitting data from the server. In order to check the effectiveness of the proposed method, the data transmission between the massive storage server and RVDB is conducted and the transmitted data is correlated by Daejeon correlator for the accurate comparison concerning the data before and after. The transmitted data is shown to be completely the same as the original data without any data transmission loss. Henceforth, the developed data transmission algorithm in this research is expected to be applied effectively as e-VLBI for KaVA network.

• Journal of the Institute of Convergence Signal Processing
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• v.18 no.1
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• pp.13-20
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• 2017

In this paper, we evaluate the basic test results of the 32 Gbps observational equipment introduced as the back-end system for the wideband VLBI (Very Long Baseline Interferometry) observation of KVN (Korean VLBI Network). Radio astronomers want to make a large radio telescope that has excellent performance in order to observe the superfine structure of a celestial body, but a lot of money is needed. Therefore, in order to increase the sensitivity, the performance improvement of the receiving system and the method of observing the wide frequency bandwidth are introduced. To do this, we adopted a wideband sampling method for converting analog signals to digital with ultra-fast speeds and a wideband sampler for performing digital filtering in order to observe a wide observational frequency bandwidth. The wideband sampler (OCTAD-K) supports up to 16 Gsps-2bits sampling and supports a variety of observational bandwidth using digital filtering techniques. In particular, it is designed to support KVN's 4-frequency simultaneous observation system and VERA(VLBI Exploration of Radio Astrometry)'s 2-beam observation system. It can also support polKVN(Korean VLBI Network), KaVA(KVN and VERA Array), 32Gbps Direct Sampler, Digital Filter, Widebandarization observations and supports the standard VDIF(VLBI Data Interchange Format) format of observed data. In this paper, the performance of the system and the problem solving are described in detail after performing the factory inspection and field test before the system is introduced.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.8
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• pp.7-18
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• 1999

We have designed and tuilt the quasioptical system for the dual channel receiver which is used for the simultaneous observation of the cosmic radio with 100GHz band and 150GHz band. The quasioptical system has been widely used to guide the beam for the millimeter and submillimeter waves. A Gaussian distribution of field and power transverse to their axis of propagation allow the simple and elegant theory of Gaussian quasioptics. Using the theory of Gaussian beam, we introduced the analysis of image beam which is applied for a wide range of frequency. In order to guide two beams from the Cassegrain antenna simultaneously, the quasioptical system and its components for the dual channel receiver were designed by using the image beam method. We have checked the characteristics of the quasioptical components and the system by using the heam measurement system, which is made by us. The quasioptical system has been installed in the dual channel receiver on the Cassegrain antenna. The performance of this system has been finally confimed through the successful simultaneous observation with two bands of the cosmic radio.

• Journal of the Earthquake Engineering Society of Korea
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• v.10 no.1 s.47
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• pp.33-39
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• 2006

Parameters including the seismic sources and the elastic wave propagation characteristics were analysed using the observed ground motions from 3 Kyoungju region earthquakes. The Levenberg-Marquardt algorithm was applied to invert all the variables non-linearly and simultaneously with S wave energy In frequency domain. Average stress drop of 3 events and local attenuation parameter ${\kappa}$ were estimated to about 48-bar and 0.0312 respectively. Regional attenuation parameter, Qo and ${\eta}$, were also estimated to be about 417 and 0.83. ${\kappa}$ values are much higher than that of EUS, even though smaller than that of WUS. All these values resultant from this study show that there are differences in some parameters of other studios due to differences in the governing equation. of acceleration motions

• Journal of Advanced Navigation Technology
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• v.26 no.5
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• pp.350-357
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• 2022

With the recent prediction of 'Cycle 25', the importance of space weather research increases. Accordingly, the World Radiocommunication Conference (WRC)-23 has adopted Agenda Item 9.1a) and carried out sharing researches between active/passive space weather observation systems and existing services. Therefore, in this paper, in order to increase the precision of space weather environment data and secure the frequency spectrum for observation systems, the direct interference effect from the weather radar in Gosan, Jeju on the space weather observation receiver in Hallim, Jeju, and the indirect interference on the observation receiver by diffraction and scattering from the radar target have been analyzed. As a result, it can be known that the radar direction, the propagation direction diffracted and scattered from the target, and the Rradar Cross Section (RCS) of the radar target, the reception area of the space weather observation antenna, and the antenna off-boresight are important parameters for the interference effect analysis.

• The Bulletin of The Korean Astronomical Society
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• v.40 no.2
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• pp.53.4-54
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• 2015

분자운의 광대역 분포는 작은 영역에서는 볼 수 없는 독특한 모습을 보여준다. 본 연구는 2010년도 TRAO 관측으로 얻는 외은하면의 $4.3^{\circ}{\times}2^{\circ}$의 광대역 데이터를 사용해서 광대역 분자운 분포의 특성을 분석했다. 광대역 분자운들은 형태학적 특징에 의거해서 네 종류로 분류되었다: chain, twisted filament, speckle, cluster suspect 이들의 특징을 간략히 소개하고 광대역 분자운들을 보는 새 관점으로 분자운 충돌 이론을 소개한다. 그와 함께 광대역 연구의 대표적인 예로 두 전파원을 소개한다. 첫째는 CTB109 (3C 434.1) 근처 분자운이며, 길다란 CO filament가 포함된다. 둘째는 "집게벌레(S157 ab 포함)"로서 강한 별 탄생을 보여주는 특이한 영역으로서 강한 CO emission이 두 개 twisted filament 구조를 보여준다. 연구에는 DRAO HI, IRAS 적외선 자료, DRAO Radio continuum data를 사용했고, CO 자료를 통해서 분자운의 질량과 밀도, 온도 등의 기본 물리량을 계산했다.

• Bulletin of the Korean Space Science Society
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• 2004.04a
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• pp.34-34
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• 2004

국가지정연구실 사업인 "인공위성 및 지구접근천체 감시연구"에서는 2003월 한국천문연구원 전파연구동에 60cm 광시야 망원경을 설치하여 시험가동중이다. 이 광시야 망원경의 광학계는 초점비 F/2.92로 직초점 방식이며 3개의 보정렌즈를 이용하여 보정된 초점면의 시야는 2.7도가 되도록 설계되었다. 독일에서 제작하였으며 광학계를 구동할 마운트는 국내 제작하였다. Apogee사 AP10, FingerLake 사 2K CCD 카메라, Pentax 67사진 카메라와 같은 다양한 관측기기를 이용하여 광학계의 성능을 검사하고 광축조정을 하고 있으며 발생한 문제점을 파악하여 해결하고 있다. (중략)

• Journal of Astronomy and Space Sciences
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• v.12 no.1
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• pp.143-156
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• 1995

Using a directional antenna, the Doppler effect of satellites can be detected and the orbital elements can be obtained by the Extended Kalman Filter with the observed frequency shift data. We obtained the orbital elements of NOAA-11 by the application of the Extended Kalman Filter type algorithm to the Doppler shift data of NOAA-11d and discussed the accuracy and the credibility of this algorithm.