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사물인터넷 환경에서 CoAP 기반의 저전력, 신뢰성 향상을 위한 경량 프로토콜
서두옥,이동호 (사)디지털산업정보학회 2019 디지털산업정보학회논문지 Vol.15 No.1
Internet of Things(IoT) is a technology or environment that collects data by attaching sensors to objects and transmits the collected information to each other through wired / wireless communication in real time. It is expected that when the Internet of objects is activated, many objects can identify and recognize each other by themselves and provide various services to facilitate our lives through mutual information exchange. In addition, the internet market for things is growing rapidly each year, and various IT technologies are expected to converge. In the Internet environment of objects, data exchange technology between object devices, that is, message protocol, is classified as one of important technologies. In this paper, we examine various lightweight message protocols suitable for the Internet environment of objects, and compare the reliability of the CoAP protocol structure with the MQTT protocol for a limited environment. Finally, we confirm the reliability of TCP / TLS and WebSockets-based CoAP transmission protocol of IETF's CoRE WG that can use various transport layers other than UDP in Internet environment including cloud infrastructure.
DTMNs를 위한 방향성 정보와 최대 공동 이웃 노드에 기반한 효율적인 라우팅 프로토콜
서두옥,이동호 (사)디지털산업정보학회 2010 디지털산업정보학회논문지 Vol.6 No.1
DTNs (Delay Tolerant Networks) refer to the networks that can support data transmission in the extreme networking situations such as continuous delay and no connectivity between ends. DTMNs (Delay Tolerant Networks) are a specific range of DTNs, and its chief considerations in the process of message delivery in the routing protocol are the transmission delay,improvement of reliability, and reduction of network loading. This article proposes a new LCN (Largest Common Neighbor) routing algorism to improve Spray and Wait routing protocol that prevents the generation of unnecessary packets in a network by letting mobile nodes limit the number of copies of their messages to all nodes to L. Since higher L is distributed to nodes with directivity to the destination node and the maximum number of common neighbor nodes among the mobile nodes based on the directivity information of each node and the maximum number of common neighbor nodes, more efficient node transmission can be realized. In order to verify this proposed algorism, DTN simulator was designed by using ONE simulator. According to the result of this simulation, the suggested algorism can reduce average delay and unnecessary message generation.
제주도 연안 갈치 채낚기 어구의 생력화 : 1. 연속식 채낚기어구의 모형 실험
서두옥,정용진,김석종,이창헌,김고환,박용석 제주대학교 해양연구소 2000 해양자원연구소연구보고 Vol.24 No.-
The authors carried out a model experiment of continuous hairtail hand line on the rooftop in order to obtain the fundamental data on elimination of labor with hairtail hand line in the coast of Jeju The results are as follow : 1. The continuous main line was rotated smoothly by driving roller. 2. The branch lines and hooks on a main line which was rotated by rotary machine were entangled slightly. 3. The branch lines attached to rubbered model of hairtails to hooks were rotated continuously by the rotary machine.
서두옥,정용진 제주대학교 해양연구소 1981 해양자원연구소연구보고 Vol.5 No.-
The tidal current, wind drift current and wind waves in the coast of Jeju Island were computed in the basis of tide tables, Thoma's formular and Hidaka's formular by use of wind data which observed at Jeju and Seogwipo Meterological Observatory. Chart and tide tables of the Hydrographic Office utilized to the stability of the artifical fishreefs in the coast of Jeju Island. The fluid resistance per unit area and the wave force per unit volume of the artificial fishreefs were summarized as follows; ◁표 삽입▷(원문을 참조하세요)
濟州島沿岸의 갈치 채낚기 漁業에 있어서 集漁 의 水中照度
徐斗玉 濟州大學校 海洋硏究所 1988 해양과환경연구소 연구논문집 Vol.12 No.-
濟州島 沿岸의 갈치 채낚기 漁業에 있어서 集魚燈의 電力에 對한 總屯數, 機關馬力. 發電機의 出力, 그리고 電球의 種類別 集魚燈의 水中照度分布等에서 얻은 結果는 다음과 같다. 1. 갈치 채낚기 漁船의 集魚燈 電力(y)에 對한 總屯數(χ₁), 機關馬力(χ₂), 發電機의 出力(χ₃)에 關한 關係式은 y=0.72χ₁+ 22.35(r =0.73) y=0.19χ₂+ 22.60(r =0.76) y=0.85χ₃- 6.87(r =0.95) 2. 水深 10m에서 水中照度는 메탈電球가 텅스텐電球보다 높았다. 3. 메탈電球의 水上集魚燈(2kw×20, 220V)과 텅스텐電球의 水中集魚燈(5kw, 220V) 10Lux의 等水中照度는 각각 水深 6.4m, 4.4m였다. 4. 갈치가 잘 釣獲되는 水深은 30~50m로서 그 水中照度는 ???????????????? Lux이다. Ribbon fish(Trichiurus lepturus, FORSKAL) are mainly caught by line fishing gear around the cost of Cheju Island that were investigated power of fishing lamp, gross tonnage of fishing boat, horse power of main engine, output of generator and underwater illumination of fishing lamp. The results obtained from the study were as follows: 1. The relationships between the power(y) of the fishing lamp to the equipped in fishing boat and gross tonnage(χ₁) of that, horse power of main engine(χ₂), output of generator(χ₃) are indicted as follows: y=0.72χ₁+22.35(r=0.73) y=0.19χ₂+22.60(r=0.76) y=0.85χ₃+6.87(r=0.95) 2. The underwater illumination of metal bulb is higher than that of tungsten bulb at 10m in the depth of water. 3. The equal underwater illumination to 10 Lux of metal bulb on the air(2㎾×20,220V) and tungsten bulb in the water were at 604m, at 4.4m in the depth of water, respectively. 4. The underwater illumination that ribbon fish were catched well was 1.5×10 ̄¹∼1.1×10 ̄³Lux at 30∼50m in the depth of water.
서두옥,정용진 제주대학교 1986 논문집 Vol.23 No.-
Underwater ambient noises were investigated at 12 points in the eastern coast of Cheju Island The underwater ambient noise was present as a sound pressure level for each frequences. The results were as follows: 1 The sound pressure level of the underwater ambient noise was the highest of that in 12 points at 100 m in the depth of water at station D. 2 The vertical average sound pressure level at 200Hz was measured at 10m. 50m and 100m in the depth of water The values were 88dB. 87dB and 90dB, respectlvely. 3 The average sound pressure level on 12 points was measured 88 dB at 200Hz in the frequency.
서두옥 제주대학교 해양연구소 1979 해양자원연구소연구보고 Vol.3 No.-
The wind waves in the coast of Jeju Island were computed applying Hidaka formula, by use of wind data which observed at Jeju and Seogwipo. Meteorological observatorg from Januauy l973 to December 1977 to calculate the stability of the artifical fish reef that will put off the coast of Jeju Island. The result obtained were summarized as follows ; 1. Maximum wind direction and velocity of Jeju coast were NW 17.4% and 8.8m/sec. That of Seogwipo coast were NE 34.0% and 6.7 m/sec. 2. The average wind waves in the coast of Jeju Island were as follows; <표본문참조>