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DQPSK 방식 광송수신기를 이용한 2Tb/s WDM 신호의 장거리 전송실험
정환석,장순혁,김광준 에스케이텔레콤 (주) 2010 Telecommunications Review Vol.20 No.5
대용량 멀티미디어 서비스의 증가에 따른 코아 라우터간 인터페이스 속도의 지속적인 증가는 단거리 망에서 100기가비트 이더넷 (100GbE) 표준 제정을 촉발하였고, 장거리 광 전송망에서 단일 파장당 100기가 속도의 전송을 요구하고 있다. 따라서 본 논문에서는 100GbE 신호의 광전송망 수용을 위해 100기가급 광 변복조 기술을 비교하고 분석한다. 다음으로 DQPSK (Differential quadrature phase shift keying) 방식에 기초한 단일 파장당 107Gb/s 속도의광 송수신기 구현에 대해 논의하며 2 Tb/s(107Gb/s x 20채널) 신호를 320 km 전송하여 100GbE 신호의 장거리 전송 가능성을 확인한다. 그리고 100G 시스템으로 업그레이드 시 10G/40G/100G 신호가 혼용되어 전송되는 멀티 레이트 시스템의 성능을 분석하고 성능 보장 방법에 대해 논의한다.
정환석,나용욱,박찬성,이준기,Chung, HwanSeok,Ra, YongWook,Park, Chansung,Lee, Joon Ki 한국전자통신연구원 2020 전자통신동향분석 Vol.35 No.5
This paper reviews the recent trends in optical access technologies and their future directions. As the number of hyper-connected, ultra-low-latency, and hyper-realistic services increases, the wireless path has become shorter and the optical access network has become deeply penetrated into the end user. The optical access network continues to evolve through endless innovation via high-speed, ultra-low-latency, and abstraction/virtualization technologies.
사례 연구 : EN ISO 13849-1의 안전회로 설계를 위한 구체적 평가 기준의 적용
정환석,이동주 한국산업경영시스템학회 2018 한국산업경영시스템학회지 Vol.41 No.1
With the development of industrial technology and science, production and manufacturing facilities have been enhanced and improved, and the importance of the safety of workers has also been regulated and limited by various safety management methods. As a way to secure the safety of the workers from the production facility, the fail-safe and fool-proof methods are now being applied. Any possible insecure behavior and unsafe conditions can be removed by adopting the standards and specifications that are now secure the safety of workers and equipment. This research analyzes EN ISO 13849-1 international and European standards during CE certification. In order to secure acceptable reduced risks, the risk assessment process of ISO 12100 and the processes for reducing its risk are applied. In the current ISO 13849-1 standard, the criteria for the required performance level PLr (Required Performance Level) for the applicable risk and safety functions through the risk assessment are subjective and not subdivided. Therefore, the evaluation criteria are likely to cause judge’s judgement error due to qualitative judgement. This research focuses on evaluation and acceptable performance level setting for the safety circuit of the equipment. We propose an objective and specific evaluation criteria to secure safety, and the proposed evaluation criteria are applied to the case study of the safety circuit for the equipment. In order to secure the safety of the entire safety circuit, the improvement of the MTTFd and DC level related to the SRP/CS (Safety-Related Parts of Control Systems)’ lifetime is required for the future research.
Diagnostic Polymorphisms in the Mitochondrial DNA Allow Discrimination among Cervus elaphus Species
정환석,이효정,김영은,강문규,황승용,김지훈,정진욱,정인혁,김양석,배현수,홍무창,신민규 한국바이오칩학회 2009 BioChip Journal Vol.3 No.3
Velvet antlers from Cervus elaphus species are one of most famous and commonly used medicinal materials in traditional oriental medicine. In this study, the variation in DNA sequences of the mitochondrial ATPase8 and cytochrome-c oxidase I (COI) genes of Cervus elaphus from China, the Republic of Altai, and Canada were evaluated. In addition, the sequence variation among Sika deer, Rein deer and Cervus elaphus species was also evaluated. Although the sequences of deer from the Republic of Altai and Canada were very similar, polymorphisms that were conserved in each species were observed in the ATPase8 and COI genes. Therefore, these polymorphic markers could be used to distinguish Cervus elaphus antlers from different locations.
정환석 글로컬창의산업연구센터 2015 글로컬창의문화연구 Vol.4 No.2
The number helps us understand all kinds of relations exiting in the world. Particularly, number 3 is formed as a distinct digital concept in Koreans deep consciousness. Given that Koreans are sharing the cultural gene called natural harmony with community , the number 3 has been one of our favorite numbers since long ago. However, the liking ranking changed due to the impact of the American culture. Koreans happened to prefer number 7 to number 3. It was confirmed through the analysis result of the newspapers in 1920~1990s that the American culture was the reason. The content is as follows. No.7 was no more than a sports term called lucky seven in 1920~1930s. Also, Japanese informed Koreans that US believed the unscientific number superstition to derogate US. One of them was number 7 which had a positive(good luck) meaning. Koreans accepted the American culture systematically and extensively by the US military government which ruled over South Korea in 1940~1950. At that time, we thought we should accept American things quickly to live well. However, the negative meaning of number 7 that Koreans had traditionally collided with the number 7, a positive meaning of the US culture. The situation in 1960s was not largely different from one in 1950s. However, as the awareness on the number 7 containing a positive meaning of the US culture was largely expanded in 1970s, it appeared in the politics, society, life/culture, and entertainment. No.7 became the Koreans favorite number beating No.3 in 1980s. The articles of that time have contents saying the propensity to No3 turned into 7 due to the impact of the western culture. The Korean language-based web service, particularly the information on the number that Koreans like provided by portal such as Naver generally stays in the fragmental stage. If the result of this study into the reaction web considering the mobile users, the lack of information will be resolved. Actually, the number of monthly inquiry of the keywords: Koreans favorite number , No.7 , and No.3 on Naver is 593 on PC and 1,495 on mobile. To assume one person per one case, almost 2,000 people receive the insufficient information. The responsive web is realized in consideration of the optimization of the search engine to resolve this problem.
정환석,김봉규,김광준 한국전자통신연구원 2008 ETRI Journal Vol.30 No.2
We compare the performance of a wavelength remodulated wavelength-division-multiplexed passive optical network implemented using Manchester-coded or inverse-return-to-zero (IRZ)-coded signal downstream and non-return-to-zero remodulated signal upstream. We investigate the effects of varying differences between downstream and upstream bit rates on the two coding schemes. When the bit rate ratio of upstream to downstream is less than or equal to 50%, the performance of Manchester coding is better than that of IRZ coding. However, when the bit rate ratio of upstream to downstream is higher than 50%, Manchester code requires appropriate time delay between upstream and downstream signals, whereas IRZ code needs reduced extinction ratio in the downstream signal.