• Title/Summary/Keyword: 延安

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Reproduction of Shallow Tides and Tidal Asymmetry by Using Finely Resolved Grid on the West Coast of Korea (서해연안 상세해상을 통한 천해조석 및 조석비대칭 재현)

  • Suh, Seung-Won
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.23 no.4
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    • pp.313-325
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    • 2011
  • Finite element grid system using h-refinement on the Yellow Sea was constructed based on previous study (Suh, 1999b) from 14 K to 210 K and special attention was concentrated on refining the coastal zone. In grid generation, depth change between adjacent points and non-dimensional tidal wave length ratio were considered. As a result approximately a quarter of the total nodes are located nearby 5 m of shallow area. Accurate bathymetry data using 30's and ETOPO1 with open boundary conditions of 8 major tidal constituents extracted automatically from FES2004 have been applied. In tidal simulation a 3-dimensional nonlinear harmonic model was setup and tidal amplification due to changes in vertical turbulent and bottom friction were simulated. In this study not only 8 major tidal constituents but also nonlinear shallow tides $M_4,$, $MS_4$ and long period $M_f,$, $M_{sf}$ were reproduced. It is found that implication of spatial variation of friction coefficient plays a very important role in reproduction of astronomical and shallow tides which are computed by iterative computation of nonlinear terms. Also it should be considered differently with respect to tidal periods. To understand the distribution of tidal asymmetry, amplitude ratio of $M_4/M_2$ and phase differences $2g(M_2)-g(M_4)$ were calculated. Tidal distortion ratio marks up to 0.2 on the west coast showing shallow coastal characteristics and somewhat wide range of ebb-dominances in front of Mokpo area are reproduced.

Using the Gyeong-in Ara Waterway to Revitalize Coastal Shipping (연안해운 활성화 측면에서의 경인아라뱃길 활용 방안)

  • Lee, Choong-Hyo;Sun, Il-Suck
    • Journal of Korea Port Economic Association
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    • v.32 no.2
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    • pp.39-57
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    • 2016
  • Many countries are developing transportation technologies aimed at reducing environmental pollution and the environmental burden. For example, environmentally friendly transportation routes and methods are being used to improve inland waterways in Europe. Against this backdrop, a case study was conducted on special cargo (weight cargo, earth and sand, etc.) on Korea's Gyeong-In Ara Waterway, an inland waterway connecting the Han River and the West Sea, serving a distribution function. The results of the analysis showed that coastal shipping could be promoted using the waterway, including a positive synergy among environmental, economic, and social aspects. That is, by shifting from overland transportation to marine transportation, it is possible to reduce environmental pollution, ease traffic congestion, decrease traffic accidents, and shorten the licensing period for the weight cargo demand of the northern area of the Han River. In this respect, the Gyeong-in Ara Waterway could become an environmentally friendly transportation route, promoting coastal shipping in Korea. However, for this to occur, support systems such as subsidies for marine transportation and using the inland waterway are required, as happens in the EU. Furthermore, existing policies to promote coastal shipping should be improved and applied more broadly.

Reliability Analysis of the GCM Data Downscaling Methods for the Climate-Induced Future Air Temperature Changes in the Coastal Zone (연안 해역의 미래 기온변화 예측을 위한 GCM 자료 Downscaling 기법의 신뢰수준 분석)

  • Lee, Khil-Ha;Cho, Hong-Yeon;Cho, Beom-Jun
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.20 no.1
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    • pp.34-41
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    • 2008
  • Future impact of anthropogenic climate-induced change on ecological regime has been an issue and information on water temperature is required for estimating coastal aquatic environment. One way to induce water temperature is to relate water temperature to air temperature and GCM is able to provide future air temperature data to do this. However, GCM data of low spatial resolution doesn't incorporate local or sitespecific air temperature in need of application, and downscaling processes are essential. In this study, a linear regression is used to relate nationally averaged air temperature to local area for the time period of 2000-2005. The RMSE for calibration (2000-2005) is 1.584, while the RMSE for validation is 1.675 for the year 2006 and 1.448 for the year 2007. The NSC for calibration (2000-2005) is 0.962, while the NSC for validation is 0.955 for the year 2006 and 0.963 for the year 2007. The results show that the linear regression is a good tool to relate local air temperature to nationally averaged air temperature with $1.0{\sim}2.0^{\circ}C$ of RMSE. The study will contribute to estimate future impact of climate-induced change on aquatic environment in Korean coastal zone.

Basic Research on Revetments Development of Erosion Protection for Coastline Creation of Hydrophilic Environment by Field Observation (현장관측에 의한 친환경 해안조성을 위한 침식방지 호안공 개발에 관한 기초적 연구)

  • Lee, Jong-Seok;Han, Jae-Myung
    • Journal of Korea Water Resources Association
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    • v.41 no.10
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    • pp.983-993
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    • 2008
  • In recent times, sea level increasing caused by abnormal weather and global warming, sea-sand dredging and complex development causes various kind of erosion damages onto the coastal area in the world. The various types of erosion control and protection methods are applied but there are no signs of fruitful effectiveness. The PC concrete protection block for shore protection structure is practically installed in globally but most of structures in the present day became villainous because of bad accessability. In this study, hydrophilic revetments for control and protection of coastline erosion will be developed in order to make up for a faculty of the shore erosion protection block with better accessibility and excellent protection ability. Experimental measurements were researched to insure for the capacity and facility on reflection coefficient, overtopping volume, and overtopping height characteristics of newly developed shore erosion protection block in model tests. As the result, hydraulic model tests show much excellent than the general step block. Field tests were carried out also to verify through vegetative test on an affinity and construction work test of control-protection on coastline erosion with actual utilization. In the latter case, deposition of sand accumulation occurred in fairly short time at the established reaches and then we can be confirmed to utilize for newly developed block as the revetments for control and protection of coastline erosion.

The influence of the tidal front on primary productivity and distribution of phytoplankton in the mid-eastern coast of Yellow Sea (황해 중.동부 연안 수역의 조석전선이 식물 플랑크톤 생산력과 분포에 미치 는 영향)

  • 최중기
    • 한국해양학회지
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    • v.26 no.3
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    • pp.223-241
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    • 1991
  • In order to study the formation and structure of tidal fronts and their influence on the distribution and productivity of phytoplankton in the outer of Kyonggi Bay, analyses on the water temperature data from 1977 to 1986 and 3 surveys from 1981 to 1986 were carried out in the mid0eastern coast of the Yellow Sea. Temperature gradients and dissolved oxygen gradients were implied that the tidal fronts are formed at the outer of the Kyonggi Bay along the western side of Tae-An peninsula from spring to summer. the formations of tidal fronts in this study area influence the distribution of phytoplankton and primary productivity. The standing stocks, chlorophyll concentrations and primary productivity of phytoplankton in the frontal area are higher than those of the outer stratified waters and the inner coastal mixed waters. These high production in the frontal area are resulted from good light condition and rich nutrient within the water columns. With a boundary of frontal area, there are relatively high chlorophyll concentrations and primary productivity in the coastal mixed waters while there are low chlorophyll concentrations and relatively high primary productivity in the stratified waters. These relatively high primary productivity in the outer area are resulted from the high potential production by nanoplankton in the surface layer and the high production of tychopelagic diatoms under the thermocline with the deep transparency.

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The study on bioaccumulation of heavy metals in the cultured Pacific oyster, Crassostrea gigas, along the coast of Tongyeong, Korea (통영연안 해역의 양식 참굴 (Crassostrea gigas) 의 중금속 농축에 관한 연구)

  • Cho, Sang-Man;Kim, Yeong-Hwan;Jeong, Woo-Geon
    • The Korean Journal of Malacology
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    • v.25 no.3
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    • pp.213-222
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    • 2009
  • In order to investigate contamination of heavy metal in seawater and cultured oyster, samples were collected November 2003 to July 2004 from 12 sites (13 sites for seawater) along the coast of Tongyeong, Korea. The mean concentrations of metal in oyster tissues were as follows: 0.09 (0.01-0.3) ${\mu}g/l$ for Cd, 0.47 (0.01-1.4) ${\mu}g/l$ for Cr, 0.59 (0.2-2.3) ${\mu}g/l$ for Ni, 1.02 (0.1-4.2) ${\mu}g/l$ for Pb and 0.48 (0.01-3.9) ${\mu}g/l$ for Hg in the seawater, whereas 2.45 (0-5.47) mg/kgDW for Cd, 3.63 (0.10-12.91) mg/kgDW for Cr, 3.2 (0.01-15.73) mg/kgDW for Ni, 3.51 (0.01-6.47) mg/kgDW for Pb and 0.39 (0.004-0.74) mg/kgDW for Hg, respectively. Most metal concentration values were below the permissible range for the related regulations. Mean bioconcentration factors (BCF) for each metal were as follows: 38,964 (1,771-207, 171) for Cd, 9,583 (1,231-80, 162) for Cr, 191 (3-20, 980) for Ni, 1,416 (245-5, 207) for Pb and 180 (5-716) for Hg, respectively. The BCF values from this study corresponded to the transitional phase from the pristine to the contaminated waters. Notably, Cd showed the highest BCF, which suggest that the Pacific oyster could be utilized as a useful biomarker for Cd contamination in sea water. The multidimensional scaling analysis suggested that the metal contaminants are mainly originated from combustion of fossil fuel and accumulated to oyster through food web.

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Analysis on inundation characteristics by compound external forces in coastal areas (연안 지역의 복합 외력에 의한 침수 특성 분석)

  • Kang, Taeuk;Sun, Dongkyun;Lee, Sangho
    • Journal of Korea Water Resources Association
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    • v.54 no.7
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    • pp.463-474
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    • 2021
  • The various external forces can cause inundation in coastal areas. This study is to analyze regional characteristics caused by single or compound external forces that can occur in coastal areas. Storm surge (tide level and wave overtopping) and rainfall were considered as the external forces in this study. The inundation analysis were applied to four coastal areas, located on the west and south coast in Republic of Korea. XP-SWMM was used to simulate rainfall-runoff phenomena and 2D ground surface inundation for watershed. A coupled model of ADCIRC and SWAN (ADCSWAN) was used to analyze tide level by storm surge and the FLOW-3D model was used to estimate wave overtopping. As a result of using a single external force, the inundation influence due to storm surge in most of the coastal areas was greater than rainfall. The results of using compound external forces were quite similar to those combined using one external force independently. However, a case of considering compound external forces sometimes created new inundation areas that didn't appear when considering only a single external force. The analysis considering compound external forces was required to reduce inundation damage in these areas.

Empirical Analysis for Improvement of Safety Management of Coastal Passenger Ship - Focusing on Safety Practitioners - (연안여객선 안전관리 개선을 위한 실증 분석 - 안전관리 실무 종사자 중심으로 -)

  • Kang, Min-gu;Kim, Hwayoung
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.25 no.5
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    • pp.511-518
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    • 2019
  • This study aimed to extract the priority safety improvement factors for coastal passenger ships and analyze the perception gap between groups. To extract the improvement factors, we formed an expert group with maritime safety supervisors, passenger-ship safety inspectors (PSIs), and captains of passenger ships, and then conducted a Delphi survey. We found, using a hierarchy process, that the improvement factors were divided into three factors in Level 1 and ten factors in Level 2. For the relative importance analysis using the AHP (Analytic Hierarchy Process) model, we also formed two groups: an inspector group with maritime safety supervisors and PSIs, and an examinee group with safety managers, captains, and crews. Consequently, the factors of designation of public transportation for passenger ships and supporting the welfare of the crew were evaluated as the most important among the extracted factors. We conducted a t-test for the analysis of the perception gap between the two groups. Three perception gaps were found: increasing the inspection personnel, strengthening the qualification of the inspection personnel, and expanding the safety operation center. The result of this study will be useful for improving the safety policy of coastal passenger ships.

Changes in Sediment Properties Caused by a Covering of Oyster Shells Pyrolyzed at a Low Temperature (저온 소성 굴 패각의 피복에 의한 연안 오염 퇴적물의 성상 변화에 관한 연구)

  • Kim, Hyung-Chul;Woo, Hee-Eun;Jeong, Ilwon;Oh, Seok-Jin;Lee, Seong-Ho;Kim, Kyunghoi
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.25 no.1
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    • pp.74-80
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    • 2019
  • In this study, pyrolyzed oyster shells at a low temperature ($350^{\circ}C$) were applied for a mesocosm experiment to confirm resulting changes in the properties of sediment. After creating a covering of oyster shells, an increase in ORP and decrease in ammonia in the overlying water was observed in an experimental case. The decrease of TOC in this experiment was due to the dilution of organic matter due to the addition of inorganic matter (pyrolyzed oyster shells). The decrease in the concentration of AVS was observed due to the adsorption of AVS by the surface of the oyster shells. From the results obtained in this experiment, it has been concluded that pyrolyzed oyster shells at a low temperature can be used for remediation of polluted sediment.

A Study on Characteristics Analysis of Swell Wave Accidents and the Establishment of Countermeasures in the East Coast (동해안 너울 사고 특성 분석 및 대응방안 수립)

  • Hwang, Soon-Mi;Oh, Hyeong-Min;Kang, Tae-Soon;Nam, Soo-Yong
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.30 no.6
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    • pp.235-241
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    • 2018
  • In this study, we collected cases of accidents caused by swell in the east coast of Korea from 2013 to 2017. The location of the accident, the season, the type of coast and the type of damage were classified and the correlation between the accident and the wave data was analyzed by collecting the observation data of the nearby area at the time of the accident. Also, based on the results of the coastal disaster vulnerability assessment of Korea Hydrographic and Oceanographic Agency, the vulnerability grades of swell accidents area were evaluated. In swell accident area, the average grade of the wave exposure index was 4.91, the wave sensitivity index was 3.87, and the wave impact index was 4.90. As a result, most of the swell accidents occurred in the 5 grade (very vulnerable level) of the wave impact index, and the area of the east coast (78.7%) of the same 5 grade was classified into five types according to the wave sensitivity index result. Finally, a countermeasures was taken for characteristics of each type.