• Title/Summary/Keyword: Above sea level

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Accuracies of the Position Fixes by the Differential GPS measured in Pusan (부산에서의 Diferential GPS의 측위정도)

  • 이희상;신형일;김기윤;이대재
    • Journal of the Korean Institute of Navigation
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    • v.17 no.3
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    • pp.49-55
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    • 1993
  • This study describes the accuracies of position fixes observed by the DGPS systems for the purpose of obtaining the utility basic data in the fishery and oceanography observation field. The circling sail experiments around a reterence point using the DGPS were made in water level point of National Fisheries University of Pusan and on the sea in Yongho day located on the southeast of that university. The main results are as follows ; 1) The number of the usable satellites in position fixing were all eighteen, SV 2, 3, 11-21, 23-26 and SV 28 etc. Each satellites could be observed for average seven hours a day, and position fixing was found to be always possible except about thirty minutes a day. 2) In the standard fixed position, the radius of 95% probability circle and the shifted distance between the position fixes by the DGPS and true position were respectively 5.7m, 0.9m. In the above case those of ordinary GPS was respectively 48.8, 54.2m. Therefore, the accuracy of the position fixes by DGPS was shown much higher the ordinary GPS. 3) At land, the shifted distance between the center of traces in the circling sail experiment of 15m ra-dius by DGPS and the reference position amounted to 5.5m and observed radius of circling traces was 17.5m. other than 15m. At sea, that distance the center of traces in circling experiment of 20m radius by the DGPS and the reference position amounted to 3.6m and observed radius of circling traces was 19.7m, other than 20m. Therefore, the utility of the circling experiment to obtain the accurate position fixes by the DGPS was found to be very high.

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Numerical Simulation of Longshore Current due to Random Sea Waves (불규칙파에 의한 연안류의 수치계산)

  • 권정곤;양윤모
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.4 no.2
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    • pp.72-82
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    • 1992
  • To accurately estimate nearshore current in shallow water regions. it is necessary to investigate the irregular wave transformation characteristics and radiation stress produced by random sea waves. This research is to investigate the application or the individual wave Analysis Method. the Component Wave Analysis Method and Representative Wave Analysis Method in the shallow water region. These methods were estimated by wave shallowing transformation when the waves propagate from deep water to shallow water region b)r generating regular waves, two component waves and irregular waves (Bretschneider-Mitsuyasu type). That is, the Indivisual Wave Analysis Method is to investigate from the viewpoint of shallow water transformation of wave statistical characteristics and their zero-down-crossing waves (wave height period and wave celerity). And the component Wave Analysis Method is to investigate from the view point of shallow water transformation of basic frequency component wave and their interference frequency component wave. In addition, this research is to compare the measured mean water level elevation with the calculated one from radiation stress of irreguar waves that is assumed in the three methods above.

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Investigation of Dice Artificial Reef Stability Installed (1981-2004 years) on Pohang Coast of the East Sea (경상북도 포항시 해역에 시설된(1981-2004년) 사각형 어초의 상태조사)

  • Cho, Yong-Chul;Kim, Wan-Ki;Lee, Chae-Sung;Kim, Nam-Il
    • Journal of Advanced Marine Engineering and Technology
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    • v.34 no.1
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    • pp.177-182
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    • 2010
  • Sediment transport around artificial habitat which is induced by the change of flow due to installation of the structure plays a role not only as a defect function of subsidence and burial but also bottom-environment control function. Using Side Scan Sonar (SSS), Differential Global Positioning System (DGPS) and Scuba diving equipment, we investigated a facility condition of a dice reef installed on Pohang coast of the East Sea. Investigation result, at total 139 place, 10,526 dice reef was discovered. As the level which affects function of the above 0.5m, the case 4 place of burial (0.5~1.2m, 2.9%), scour appeared with 3 place (0.5m, 2.2%) and broken was appeared with 183 artificial reefs (1.74%). As a result, dice reef installed Pohang coast appeared to mostly stable.

The Analysis of Attributive Level of District Image for City Image - Focus on Busan City - (도시 이미지에 대한 지구 이미지의 기여수준 분석 - 부산시를 중심으로 -)

  • Byeon, Jae-Sang;Choi, Hyung-Seok;Shin, Ji-Hoon;Cho, Ye-Jee;Kim, Song-Yi;Im, Seung-Bin
    • Journal of the Korean Institute of Landscape Architecture
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    • v.35 no.1 s.120
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    • pp.59-68
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    • 2007
  • This article statistically analyzed contributive levels of district image based on an effect and a similarity index through the evaluation of citizens and suggested the efficient management system of a city image according to the results. For this study, Busan City was selected as a case city by the preceding literature and was investigated concerning district image and city image through a questionnaire. The new evaluation method for analysis of a city image was presented in this process. The results of this research are as follows: 1. Busan City has a substantial positive and culturally unique image, and each of its districts have other image characteristics. for example, the CBD district has a positive image, and the sea shore district has a busy and prosperous image, but the backward sea shore district has an image of stagnancy. 2. The image of Yeonje-gu has the largest effect on the image of Busan. Next in influence are Jung-gu, Saha-gu, Suyoung-gu, respectively. The effect index is closely connected with the variance of evaluative adjectives. 3. Busanjin-gu and Haeundae-gu have similar images to Busan City. Next in similarity are Nam-gu, Jung-gu, Youngdo-gu, Suyoung-gu, respectively. The similarity index is closely connected with the correlation of evaluative adjectives. Busan City and its districts can establish their image strategies with the above analyzed results. This study is meaningful in that a statistical evaluative method was proposed. With continued follow-up research, this study may serve as a systematic and logical model to improve the urban landscape and image.

A Study on the Linear Array Beamforming by Cross Correlation Matrix (상호상관 행렬을 이용한 선배열 빔형성 기법 연구)

  • 황수복;이성은
    • The Journal of the Acoustical Society of Korea
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    • v.20 no.7
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    • pp.31-36
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    • 2001
  • Passive sonar system forms the various beams in any desired directions to obtain the improvement in Signal-to-Noise (S/N) ratio, bearing detection and localization of targets, and the attenuation of interferences from other directions. The improvement of beamforming is very important to detect modern underwater targets as noise reduction technology leads to considerably low-level acoustic emissions in the long range in complex environmental sea. In this paper, we proposed the spatial cross correlation beamforming (SCCBF) algorithm using cross correlation matrix of individual hydrophone pairs of linear array sensors. By the theoretical analysis and simulation, the proposed SCCBF is demonstrated that its performances compared to conventional beamforming (CBF) output can be obtain above 3dB of array gain and about half of beam width represented the bearing accuracy in target detection. Also, this paper presents sea test result of linear passive sonar system that the proposed algorithm implemented.

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On the Origin of the Tsushima Current (I) : Barotropic Case (대마해류의 기원에 대하여 (I) : 순압인 경우)

  • PANG Ig-Chan;KIM Tae-Hee;MATSUNO Takeshi;RHO Hong-Kil
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.26 no.6
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    • pp.580-593
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    • 1993
  • The Tsushima Current has been known to branch out from the Kuroshio west of Kyushu and to flow north to the Korea Strait. Then, it has to flow across the isobaths and so needs some driving forces. As the forces, sea level difference between the Korea and Tsugaru Straits, Reynolds stress west of Kyushu and density differences have been suggested, In this paper, their roles have been numerically studied in the barotropic case. Model results show that the Tsushima Current is possible without any above force. The flows just follow isobaths over the East China Sea. They seem to be driven by their own dynamics without any external force. The mechanism is just like outflows from a gap. Model results also show that the flows in this area could be significantly affected by the external forces such as Reynolds Stress. Then the dynamics and flows in real ocean might be complicated. However, the barotropic study tells us that the Tsuahima Currents is basically driven by geostrophic adjustment.

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Test of Communication Distance Measurement of Fishing Gear Automatic System Based on Private LoRa (Private LoRa 기반 어구 자동식별 시스템의 거리 측정 시험)

  • Lee, Seong-Real;Kim, Se-Hoon
    • Journal of Advanced Navigation Technology
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    • v.24 no.2
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    • pp.61-66
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    • 2020
  • Since the ocean accounts for 70.8 percent of the earth's surface, the success of IoT technology in the marine industry is to collect information from devices placed in a wider range. LPWA is a feature with a wide range of communication and is very suitable for deployment in the ocean. In this paper, the real-sea performance distance experiment was carried out based on Private LoRa, a key technology for executing the electronic phrase real-name system. A private LoRa module based on sx1276 was developed, and Gateway was developed to transfer data received by private LoRa to the server using SKT Cat. M1. After installing gateways at 599 meters above sea level and experimenting with data transmission and reception at 25 km, 40 km and 60 km, we were able to see that the communication success rate was obtained to be 96.1%. 97.1% and 96.2% respectively.

Effectiveness of Wave Resonator for Secondary Undulation under Real Sea Conditions (실해역에서 공진장치를 이용한 부진동의 제어)

  • Jeong, Jin-Woo;Kim, Do-Sam;Park, Jong-Bae;An, Sung-Wook
    • Journal of Ocean Engineering and Technology
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    • v.24 no.6
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    • pp.51-60
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    • 2010
  • In this study, the performance evaluation of a conventional wave resonator at the entrance of a port or a pier against secondary undulation has been performed using 2D hydrodynamic modeling within port. A wave resonator has been designed for the attenuation of the secondary undulation induced by the long-periodic waves. The controlled performance of the wave resonator has been numerically investigated for CGWAVE MODULE of finite-element model of SMS (Surface water Modeling System) based on the elliptic mild-slope wave equation. SMS was verified though the comparisons with analytical solution performed by Ippen and Goda (1963). Also, It was confirmed that a wave resonator of a rectangular model harbor is effective enough to control the secondary undulation when it compares variation of water level with the case of no resonance system. From the above results, amplification phenomenon induced by long-period waves transferred from 1900 sec to 2100 sec when it applied a wave resonator in Busan Gamcheon Port which is a deep-sea. And it was confirmed that a wave resonator of Pohang New Port attenuates largely long-period waves which are within the range of 300 sec induced by long-period motion of the moored ship.

Seasonal and Diurnal Variations of Surface Ozone at Ieodo in the East China Sea (이어도 해양과학기지의 오존농도의 계절변화와 일변화 특징)

  • Shin, Beom-Cheol;Lee, Mee-Hye;Lee, Jae-Hak;Shim, Jae-Seol
    • Journal of Korean Society for Atmospheric Environment
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    • v.23 no.6
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    • pp.631-639
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    • 2007
  • We examined diurnal and seasonal variations of ozone ($O_3$) concentrations and its relation to meteorological parameters observed at the Ieodo Ocean Research Station ($32.07^{\circ}N$, $125.10^{\circ}E$, 36 m above sea level) during June 2003 and May 2005. Over the 2-year period, the mean ozone concentration was $49.5{\pm}15.5\;ppbv$. Ozone concentrations show great variability with a monthly mean up to 68.2 ppbv in May 2005 and seasonal variations with being highest in spring and fall, and lowest in summer. However, the amplitude of diurnal variation was less than ${\sim}4\;ppbv$ with a maximum at $3{\sim}4\;p.m.$ and minimum at $7{\sim}8\;a.m.$ HYSPLIT backward air trajectory indicated that the air masses with higher ozone came from the north or northwest and those with lower ozone arrived mainly via southerly or southeasterly. Ozone distributions at Ieodo Ocean Research Station were observed to be significantly impacted by long-range transport and regional scale air circulation.

Residue of benomyl in the coastal environment on the Cheju island (제주도(濟州道) 연안(沿岸) 해양(海洋) 중(中) benomyl의 잔류(殘留))

  • Kim, Jung-Ho;Suh, Seung-Kyo;Oh, Youn-Keun
    • The Korean Journal of Pesticide Science
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    • v.3 no.1
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    • pp.51-56
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    • 1999
  • For the determination of coastal environmental contamination level of benomyl, benzimidazole pesticide, the residue of benomyl in various environmental samples on the Cheju island was monitored in May, August and October 1996, respectively. The residue of benomyl was determined as carbendazim because benomyl was converted to carbendazim (methyl 2- benzimidazolecarbamate) in the environment. The qualified limit detection of benomyl was $0.2{\mu}g/L$ in ocean water and $0.4{\mu}g/kg$ in the solid such as sediment and sea organism by HPLC with UV detector. Benomyl was not detected in any water and sediment. Moreover benomyl was neither detected in seaweed cava(Ecklonia Cava), agar(Gelidium amansii), turban sell(Batillus cornutus) and sea urchin(Anthocidaris Crassispina). Above date suggest that the benomyl used in the Cheju island is not the major source of coastal contamination.

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