• Journal of The Korean Astronomical Society
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• v.52 no.6
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• pp.227-233
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• 2019

We report the performance of the 13.7-meter Taeduk Radio Astronomy Observatory (TRAO) radio telescope. The telescope has been equipped with a new receiver, SEQUOIA-TRAO, a new backend system, FFT2G, and a new VxWorks operating system. The receiver system features a 16-pixel focal plane array using high-performance MMIC preamplifiers; it shows very low system noise levels, with system noise temperatures from 150 K to 450 K at frequencies from 86 to 115 GHz. With the new backend system, we can simultaneously obtain 32 spectra, each with a velocity coverage of 163 km s^-1 and a resolution of 0.04 km s^-1 at 115 GHz. The new operating system, VxWorks, has successfully handled the LMTMC-TRAO observing software. The main observing method is the on-the-fly (OTF) mapping mode; a position-switching mode is available for small-area observations. Remote observing is provided. The antenna surface has been newly adjusted using digital photogrammetry, achieving a rms surface accuracy better than 130 ㎛. The pointing uncertainty is found to be less than 5" over the entire sky. We tested the new receiver system with multi-frequency observations in OTF mode. The aperture efficiencies are 43±1%, 42±1%, 37±1%, and 33±1%, the beam efficiencies are 45±2%, 48±2%, 46±2%, and 41±2% at 86, 98, 110, and 115 GHz, respectively.

• The Transactions of the Korea Information Processing Society
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• v.4 no.10
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• pp.2596-2604
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• 1997

There are two kinds of backends in ACK:code generator(full-fledged backend) and code expander(fast backend). Code generators generate target code using string pattern matching and code expanders generate target code using macro expansion. ACK translates EM to SPARC code using code expander. The corresponding SPARC code sequences for a EM code are generated and then push-pop optimization is performed. But, there is the problem of maintaining hybrid stack. And code expander is not considered to passes parameters of a procedure call through register windows. The purpose of this paper is to improve SPARC code quality. We suggest a method of SPARC cod generation using EM tree. Our method is divided into two phases:EM tree building phase and code expansion phase. The EM tree building phase creates the EM tree and code expansion phase translates it into SPARC code. EM tree is designed to pass parameters of a procedure call through register windows. To remove hybrid stack, we extract an additional information from EM code. We improved many disadvantages that arise from code expander in ACK.

• The Journal of Korean Institute of Next Generation Computing
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• v.15 no.4
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• pp.18-29
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• 2019

A dynamic adaptive streaming server consumes high processor power because it handles a large amount of transcoding operations at a time. For this purpose, multi-processor architecture is mandatory for which effective transcoding task distribution strategies are essential. In this paper, we present the design and implementation details of the transcoding workload distribution schemes at a 2-tier (frontend node and backend node) transcoding server. For this, we implemented four schemes: 1) allocation of transcoding tasks to appropriate back-end nodes, 2) task scheduling in the back-end node and 3) the communication between front-end and back-end nodes. Experiments were conducted to compare the estimated and the actual power consumption in a real testbed to verify the efficacy of the system. It also proved that the system can reduce the load on each node to optimize the power and time used for transcoding.

• Journal of the Korea Society of Computer and Information
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• v.27 no.4
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• pp.231-239
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• 2022

In this paper, I analyze the difficulties of web service development education for non-IT majors through the Q&A of students posted in the k-mooc lecture, and propose methods to improve them. Through Q&A analysis, it was confirmed that non-majors mainly had difficulties in using unfamiliar tools, cost of cloud service, setting up server environment, and writing code while taking web service development courses. To solve this problem, I propose a method to reduce the server cost problem and the complexity of the server environment by using BaaS(Backend as a Service), which is one of the cloud service models. It also shows that it is possible to reduce the length of code that needs to be written at once by using the React library to modularize long code into smaller units. Finally, I propose an improvement plan that even non-IT majors can easily learn by implementing a web application that works by using the design output obtained by using Figma.

• 한국초전도학회:학술대회논문집
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• v.16
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• pp.68-68
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• 2006

• 한국초전도학회:학술대회논문집
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• v.16
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• pp.99-99
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• 2006

• 한국초전도학회:학술대회논문집
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• v.16
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• pp.97-97
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• 2006

• Proceedings of the Korea Information Processing Society Conference
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• 2017.11a
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• pp.6-7
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• 2017

디지털 데이터의 폭발적 증가와 형태의 다양화는 최근 비정형 대규모 저장 플랫폼의 급격한 확산을 이끌고 있다. 이러한 비정형 데이터 저장 시스템은 전통적인 파일시스템과 데이터를 저장 및 처리하는 방식이 상이하여 높은 성능을 위해서는 기존 하위 시스템의 최적화가 필요하다. 이에 본 논문에서는 최근 급부상하고 있는 분산 오브젝트 스토어인 Ceph을 중심으로 오브젝트 스토어의 스토리지 접근 패턴을 분석하는 연구를 수행한다. 본 연구는 상위 계층의 접근패턴을 구체적으로 이해함으로써 차세대 데이터 플랫폼을 효율적으로 지원할 수 있는 스토리지 시스템을 개발하는 데에 기여한다고 하겠다.

• Publications of The Korean Astronomical Society
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• v.22 no.3
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• pp.83-87
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• 2007

We designed the Intermediate Frequency(IF) distributor for multi beam backend system and manufactured Voltage to Frequency Converter(VFC) to measure the multi-beam receiver performance. Multi beam receiver has 15 channel receivers and can get 15 spectrums at once. The multi beam receiver has more observation efficiency than single beam receiver. We manufactured the 15 IF distributors to distribute IF signal for Autocorrelation spectrometer that is radio signal processor. Also, we manufactured the VF Converter to test the performance measurement of receiver for Korea VLBI Network(KVN) system which is under-construct in Seoul, Ulsan and Jeju. As a result of performance measurement, we could obtain linearity of 99.4% on the input power vs output frequency and measured the operating range of input frequency.

• Proceedings of the Korean Information Science Society Conference
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• 2010.06b
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• pp.523-526
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• 2010

고에너지 물리나 바이오 인포매틱스 연구 분야는 대량의 컴퓨팅 자원을 필요로 한다. 이를 위해서 클러스터 컴퓨팅, 그리드 컴퓨팅, 슈퍼 컴퓨팅, 클라우드 컴퓨팅 자원 등의 여러 컴퓨팅 자원이 사용된다. 사용자는 각 컴퓨팅 자원을 이용하기 위해서 각각의 사용 방법을 배우고, 저마다의 방법으로 각 컴퓨팅 자원을 사용한다. 사용자가 각 컴퓨터 자원의 사용 방법을 습득하기 위해서는 많은 비용과 시간이 필요하다. 사용자가 보다 쉽고 빠르게 컴퓨팅 자원을 활용하기 위하여 여러 컴퓨팅 자원을 사용하기 위한 동일 인터페이스 개발이 필요하다. 본 논문에서는 한국과학기술정보연구원의 타키온 슈퍼컴퓨터를 이용하는 사용자에게 동일한 사용자 인터페이스를 제공하기 위한 Ganga의 원격 SGE 백엔드(Backend) 플러그인을 설계하고 구현하였다.