DE405를 이용한 태양계 천체력 계산

김효령,노덕규,정현수,정재훈,조세형,안영숙,KIM HYO RYOUNG,ROH DUK GYOO,CHUNG HYUN SOO,JUNG JAE HOON,CHO SE HYUNG,AHN YOUNG SOOK 한국천문학회 2001 天文學論叢 Vol.16 No.1

The DE405 ephemeride is introduced as TRAO solar ephemeris system to support the apparent coordinates of planets after 2000. The time delay between planets and observer has to be regarded to get the apparent position of planet. Some fast algorithms about time delay are suggested to reduce the computing time. The CSI method is applied to run these algorithms on any O/S including both real-time and run-time machine.

하드디스크 데이타 I/O 속도 측정용 유틸리티 blockwrite 개발과 응용

김효령(Hyo-Ryoung Kim),송민규(Min-Gyu Song) 한국전자통신학회 2020 한국전자통신학회 논문지 Vol.15 No.6

하드디스크의 속도 성능을 탐색해 볼 수 있는 유틸리티를 개발하였다. 하드디스크에 적용하여 속도 곡선을 자세히 볼 수 있음을 보이고, 이동평균 방법을 적용하면 하드디스크의 실린더 구조와 속도 곡선의 변화를 선명하게 볼 수 있도록 하였다. 확장성을 위해 일반 대용량 스토리지에 적용하였으며, 최근에 새로운 저장 매체로 각광 받고 있는 SSD의 I/O 성능을 측정하였다. 10Gbps급 이상의 속도를 보이는 M.2 NVME를 이용하여, 리눅스 O/S에서 제공하느 cp와 속도 비교 실험을 수행함으로서, 유틸리티의 신뢰성을 검증하였다. In order to investigate the speed profile of data I/O of HDD, we have delveloped an utility program. The application to HDD reveals the detail properties of the speed profile of HDD and the relation between the cylinder structrure of HDD and the velocity profile, also. For the extent application, the experiment of the large volume storage was performed, and the profile of SSD media, which is known as the new rapid media, was measured. The new M.2 NVME SSD, which has the ability of over 10Gbps, we can compare the velocities between cp under linux O/S and the utility, and shows that the preformance of the utility can be reliable.

blockwrite를 이용한 대형 스토리지 성능 측정 및 최적화 연구

김효령(Hyo-Ryoung Kim),송민규(Min-Gyu Song),강용우(Yong-Woo Kang) 한국전자통신학회 2021 한국전자통신학회 논문지 Vol.16 No.6

1.4P 대형 스토리지의 성능을 최적화하기 위하여 청크모드별 특성을 조사하고, I/O 속도면에서 청크 512K 모드를 선택하였다. NVME 스토리지 시스템을 구성하여 대형 스토리지의 데이터 서버 성능 측정에 활용하였다. 1.4P 대형 스토리지의 쓰레드 수에 따른 스루풋의 변화를 측정하여 대형 스토리지 시스템의 특성을 파악하였으며, 스루풋의 최대값은 블록크기 32KB에서 133Gbps 성능을 보임을 확인하였다. GridFTP 방식의 globus-url-copy를 이용하여 데이터 송수신 실험을 수행한 결과, 이 대형 스토리지는 33Gbps의 스루풋을 가지고 있음을 알 수 있었다. In order to optimize the performance of 1.4P large storage, the characteristics of each chunk mode were investigated, and the chunk 512K mode was selected in terms of I/O speed. NVME storage system was configured and used to measure data server performance of large storage. By measuring the change in throughput according to the number of threads of the 1.4P large storage, the characteristics of the large storage system were identified, and it was confirmed that the performance was up to 133Gbps with a block size of 32KB. As a result of data transmission/reception experiment using globus-url-copy of GridFTP, it was found that this large storage has a throughput of 33Gbps.

불요발사 (우주업무의 발사)로부터 수동업무의 보호

정현수,노덕규,제도흥,박종민,김효령,안도섭,오대섭,Chung, Hyun-Soo,Je, Do-Heung,Park, Jong-Min,Kim, Hyo-Ryoung,Ahn, Do-Seob,Oh, Dae-Sub 한국천문학회 2003 天文學論叢 Vol.18 No.1

WRC-03 was held between 9 June and 4 July 2003 in Geneva, Switzerland. Over 2,200 delegates from 138 ITU Member States attended the Conference. The delegates considered some 2,500 proposals, and over 900 numbered documents related to 50 agenda items. The final output of the Conference consists of 527 pages of new and revised text of the Radio Regulations. This paper provides some details about the outcome of the radio astronomy related issues at the WRC-03 Conference. It is divided into two part: a) Agenda item1.8.2 and b) Agenda item 1.32, related to radio astronomy. Relevant extracts from the Final Acts of WRC-03 are given in the Appendix. Agenda item 1.8.2 was one of the most controversial Agenda Items at WRC-03. Studies were carried out within ITU-R TG 1/7 for the last three years; the results of these studies are summarized in Recommendation ITU-R SM.1633. The Conference adopted a new footnote (5.347A), that calls for the application of Resolution 739 (WRC-03) in the 1452-1492 MHz, 1525-1559 MHz, 1613.8-1626.5 MHz, 2655-2670 MHz, 2670-2690 MHz and 21.4-22.0 GHz bands. Agenda item 1.32 is to consider technical and reglatory provisions concerning the band 37.5-43.5 GHz, in accordance with Resolutions 128 (Rev.WRC-2000) and 84 (WRC-2000). WRC-03 reviewed and adjusted the New footnotes 5.551H and 5.551I cover the protection of radio astronomy observations in the 42.5-43.5 GHz band from unwanted emissions by non-geostationary (5.551H) and geostationary (5.551I) FSS and BSS systems, respectively.

불안정한 네트워크 환경에서 대용량 데이터의 전송 효율화를 위한 링 버퍼에 관한 연구

송민규(Min-Gyu Song),김효령(Hyo-Ryoung Kim) 한국전자통신학회 2020 한국전자통신학회 논문지 Vol.15 No.6

본 논문에서는 불안정한 네트워크 환경에서 안정적으로 대용량 데이터 스트림을 전송할 수 있는 TCP/IP 기반 링 버퍼 시스템을 설계하였다. 우리가 제안한 방식에서 각 전파천문대의 백엔드 시스템에서 UDP 프레임으로 생성 및 출력되는 관측 데이터 스트림은 클라이언트 시스템 내의 소켓 버퍼를 경유해 대용량 링 버퍼에 UDP 패킷으로 저장된다. 이후 목적지에 해당하는 상관센터로의 안정적인 전송을 위해 이는 다시 TCP 패킷으로 송신되고 상관센터 내의 서버 시스템은 해당 패킷을 소켓 버퍼에 수신받아 이상이 없을 경우 대용량 링 버퍼에 저장한다. 패킷 손실, 중복 및 순서 역전 등의 이상이 발생할 경우 TCP의 흐름 제어를 통해 패킷은 재전송되며 상관센터에 도착한 데이터는 신뢰성을 보장받게 된다. 또한 네트워크 성능 불안정으로 인한 혼잡 회피 발생 시 병렬 스트림 적용을 통해 성능 저하가 소화될 수 있도록 하였다. In this paper, we designed a TCP/IP based ring buffer system that can stably transfer bulk data streams in the unstable network environments. In the scheme we proposed, The observation data stream generated and output by each radio observatory s backend system as a UDP frame is stored as a UDP packet in a large capacity ring buffer via a socket buffer in the client system. Thereafter, for stable transmission to the remote destination, the packets are processed in TCP and transmitted to the socket buffer of server system in the correlation center, which packets are stored in a large capacity ring buffer if there is no problem with the packets. In case of errors such as loss, duplication, and out of order delivery, the packets are retransmitted through TCP flow control, and we guaranteed that the reliability of data arriving at the correlation center. When congestion avoidance occurs due to network performance instability, we also suggest that performance degradation can be minimized by applying parallel streams.

대용량 데이터의 전송 효율 및 기록 성능 향상을 위한 Zero Copy 기술 적용에 관한 연구

송민규(Min-Gyu Song),김효령(Hyo-Ryoung Kim),강용우(Yong-Woo Kang),제도흥(Do-Heung Je),위석오(Seog-Oh Wi),이성모(Sung-Mo Lee),김승래(Seung-Rae Kim) 한국전자통신학회 2021 한국전자통신학회 논문지 Vol.16 No.6

Zero-copy는 메모리 무복사로도 불리는 기술로서 이에 대한 사용을 통해 사용자 영역과 커널 영역 간 컨텍스트 스위칭을 줄여 CPU의 부하를 최소화할 수 있다. 하지만 이 기술은 소규모의 랜덤한 파일을 전송하는 용도에 그치고, 대용량 파일 전송에는 아직 널리 활용되지 못하고 있다. 본 논문은 네트워크를 경유한 대용량 파일 처리에 있어서 Zero-copy의 실질적인 적용 방안에 대해 논의하고자 한다. 이를 위해 먼저 Zero-copy 기반으로 데이터를 전송, 저장할 수 있는 소규모 테스트베드 구축 및 프로그램을 개발하였다. 이후 세부 성능 평가를 통해 적용된 기술의 유용성을 세부 검증하고자 한다. Zero-copy is a technology that is also called no-memory copy, and through its use, context switching between the user space and the kernel space can be reduced to minimize the load on the CPU. However, this technology is only used to transmit small random files, and has not yet been widely used for large file transfers. This paper intends to discuss the practical application of zero-copy in processing large files via a network. To this end, we first developed a small test bed and program that can transmit and store data based on zero-copy. Afterwards, we intend to verify the usefulness of the applied technology in detail through detailed performance evaluation.

전파천문 및 위성통신업무간의 주파수 공유방안

정현수,노덕규,제도흥,김효령,박종민,안도섭,오대섭,CHUNG HYUNSOO,ROH CUK-GYOO,JE DO-HEUNG,KIM HYO-RYOUNG,PARK JONG-MIN,AHN DO-SEOB,OH DAE-SUB 한국천문학회 2004 天文學論叢 Vol.19 No.1

In the past, radio astronomers have sought isolation from man-made signals by placing their telescopes in remote locations. These measures may no longer safeguard scientific observations, since NGSO satellite systems, particularly low-Earth orbit (LEO) systems, are usually designed to provide global or wide regional coverage. Further, radio astronomers have historically made their observations in the frequency bands allocated for their use by the member countries of the International Telecommunication Union (ITU). The science of radio astronomy could be adversely impacted by the deployment of large constellations of new non-geostationary orbiting (NGSO) satellites for telecommunications, navigation and Earth observation, and the proliferation of new, high-power broadcasting and telecommunication satellites in geostationary (GSO) orbits. Radio telescopes are extremely sensitive, and, in certain situations, signals from satellites can overwhelm the signals from astronomical sources. This paper describes the problem in detail and identifies ways to mitigate it without adversely affecting the continued vigorous growth of commercial space-based telecommunications.

전파천문 관측데이터 분석을 위해 소프트웨어를 이용한 디지털필터 설계에 관한 연구

염재환,오세진,노덕규,오충식,정동규,신재식,김효령,황주연,Yeom, Jae-Hwan,Oh, Se-Jin,Roh, Duk-Gyoo,Oh, Chung-Sik,Jung, Dong-Kyu,Shin, Jae-Sik,Kim, Hyo-Ryoung,Hwang, Ju-Yeon 한국융합신호처리학회 2015 융합신호처리학회 논문지 (JISPS) Vol.16 No.4

본 논문은 전파천문 관측데이터 분석을 위해 소프트웨어를 이용한 디지털필터 설계방법에 대해 제안한다. 전파천문 관측시스템은 컴퓨팅 시스템의 발전과 함께 하드웨어에서 소프트웨어를 이용한 분석방법으로 넘어가는 단계이다. 기존 하드웨어로는 특정규격에 맞도록 설계 제작되었기 때문에 규격을 변경하는 것이 어렵고 제작에 많은 비용이 소요되지만, 소프트웨어는 규격 변경이 유연하고 공개 소프트웨어를 이용할 경우 저렴하게 설계할 수 있는 장점이 있다. 그러나 소프트웨어로 전파천문과 같이 많은 자료를 분석하기 위해서는 컴퓨터 시스템의 성능이 우수해야 하는 점도 있다. 본 연구에서는 한국우주전파관측망에서 운영하고 있는 관측시스템 중에서 하드웨어로 구성된 디지털필터와 같은 성능을 갖는 소프트웨어 디지털 필터 설계에 대해 제안한다. 제안 방법은 표준 C언어를 이용하여 디지털 필터를 설계하였으며, 설계한 디지털필터에 대해 GNU Octave로 시뮬레이션을 수행하여 유효성을 검토하였다. 또한 설계한 디지털필터의 고속연산을 위해 병렬연산이 가능한 SSE 라이브러리를 도입하였다. KVN 관측모드 중에 광대역 관측데이터를 대상으로 제안한 방법의 디지털 필터를 통하여 협대역 관측모드로 데이터 필터링을 수행하였다. 그 결과, 대역 내의 필터링이 설계대로 수행되었고 리플이 발생하지 않아, 제안방법이 유효함을 확인하였다. In this paper, we propose a design method for a digital filter using software in order to analyze the radio astronomy observation data. Recently the analysis method for radio astronomy observing system is transferring from hardware to software by developing of state-of-the-art of computer system. The existing hardware system is not able to easily change the specification because it is implemented to meet special requirements and it takes a high cost and time. In case of software, however, it has an advantage to implement with small cost if open software is used, and flexibly changes to satisfy the desired specification. But, in order to analyze the massive data like radio astronomy with software, the good performance system is needed for computer. Therefore, this paper proposes a digital filter design method using software with the same performance as that of digital filter implemented with hardware in observation system which is operated by the KVN(Korean VLBI Network). To design a digital filter, the proposed method is performed with standard C language and the simulation is conducted with GNU(GNU's Not Unix) Octave and investigated to show its effectiveness. In addition, for the high speed operation of the designed digital filter, the SSE(Streaming SIMD Extensions) library is adopted for available parallel operation. By the proposed digital filter, the digital filtering is performed for the wide band observation data in the KVN observation mode, the filtering result of narrow band observation has no ripple inside of stop band, and confirmed the effectiveness of the proposed method.

RVDB와 대용량 서버 간의 직접 데이터 전송 알고리즘 개발과 시험에 관한 연구

노덕규,오세진,염재환,정동규,오충식,윤영주,김효령,Roh, Duk-Gyoo,Oh, Se-Jin,Yeom, Jae-Hwan,Jung, Dong-Kyu,Oh, Chung-Sik,Yun, Young-Joo,Kim, Hyo-Ryoung,Ozeki, Kensuke 한국천문학회 2014 天文學論叢 Vol.29 No.3

This paper describes the development of algorithm for direct data transmission between Raw VLBI Data Buffer (RVDB) and Huge Capacity Data Server (HCDS) operated in Korea-Japan Correlation Center (KJCC). The transmitted data is the VLBI observation data, which is recorded at each radio telescope site, and the data transmitting rate is varying from 1 Gbps, in usual case, upto 8 Gbps. The developed algorithm for data transmission enables the direct data transmission between RVDB and HCDS through 10 Gbps optical network using VLBI Data Interchange Format (VDIF). Proposed method adopts the conventional UDP/IP protocol, but in order to prevent the loss of data during data transmission, the packet error monitoring and data re-transmission functions are newly designed. The VDIF specification and VDIFCP (VDIF Control Protocol) are used for the direct data transmission between RVDB and HCDS. To validate the developed algorithm for data transmission, we conducted the data transmission from RVDB to HCDS, and compared to the transmitted data with the original data bit by bit. We confirmed that the transmitted data is identical to the original data without any loss and it has been recovered well even if there were some packet losses.

VLBI상관서브시스템의 검증을 위한 소프트웨어 시뮬레이터의 개발 및 성능시험

오세진,노덕규,염재환,정현수,이창훈,김효령,김광동,강용우,박선엽,Oh, Se-Jin,Roh, Duk-Gyoo,Yeom, Jae-Hwan,Chung, Hyun-Soo,Lee, Chang-Hoon,Kim, Hyo-Ryoung,Kim, Kwang-Dong,Kang, Yong-Woo,Park, Sun-Yeop 한국천문학회 2008 天文學論叢 Vol.23 No.2

A software simulator is developed for verifying the VLBI Correlation Subsystem (VCS) trial product hardware. This software simulator includes the delay tracking, fringe rotation, bit-jump, FFT analysis, re-quantization, and auto/cross-correlation functions so as to confirm the function of the VCS trial product hardware. To verify the effectiveness of the developed software simulator, we carried out experiments using the simulation data which is a mixed signal with white noise and tone signal generated by software. We confirmed that the performance of this software simulator is similar as that of the hardware system. In case of spectral analysis and re-quantization experiment, a serious problem of the VCS hardware, which is not enough for expressing the data stream of FFT results specified in VCS hardware specification, was found by this software simulator. Through the experiments, the performance of software simulator was verified to be efficient. In future, we will improve and modify the function of software simulator to be used as a software correlator of Korea-Japan Joint VLBI Correlator (KJJVC).