• Ocean and Polar Research
• /
• 제33권spc3호
• /
• pp.359-369
• /
• 2011

This study documents KORDI's experience of successfully deploying a deep ocean buoy for monitoring oceanic and atmospheric variabilities in the tropical western Pacific Ocea nsince May 2010. The primary focus of this study was to compare TRITON (big and old type) with m-TRITON (smaller and new type) buoys within the JAMSTEC's buoy management system. The objective of operating a KORDI buoy is to ascertain oceanic variability in the tropical western Pacific. We adopted a slack-line mooring type to observe water temperatures at six layers from surface to 400 m depth. However, we could not acquire satisfactory results due to lack of expertise in buoy management system. A new KORDI buoy has been developing, which has been modified from both buoys, and ARGOS-3 satellite system and a slack-type mooring line.

• 한국해양학회지
• /
• 제7권1호
• /
• pp.15-18
• /
• 1972

1968년 8월부터 1969년 7월까지 1년간 대한해협에서 수온 염분의 시간적 변동에 대해 조사한 결과를 요약하면 다음과 같다. 1. 수온 염분의 시간적 변동범위는 년중 8월이 가장 크고 4월이 가장 작았다. 2. 8월의 수온은 125m 층에서 5.67-15.75$^{\circ}C$로 10.08$^{\circ}C$의 최고 변동범위를 보였으며, 염분은 20m 층에서 32.09-34.32 로 2.23 의 최고 변동범위를 보였다. 3. 이렇게 수온, 염분의 시간적 변동범위가 계절에 따라 수층에 따라 큰 차이를 보이는 것은 대한해협에는 수평, 수직적으로 이질적인 다양한 수괴들이 있어 이들이 게절에 따라 분포구조가 변화할 뿐 아니라, 이곳을 통과하는 대마난류가 조석의 영향으로 시시각각 그 유향과 유속이 변동됨에 따라 이들 수괴들이 상호 수직, 수평으로 유동하기 때문인 것으로 보인다.

• 한국수산과학회지
• /
• 제56권3호
• /
• pp.341-346
• /
• 2023

This study aimed to suggest an alternative income generation (AIG) for local artisanal fisheries communities in the southern coastal area of Bangladesh, which is vulnerable to climate change. To analyze the problems of local artisanal fisheries caused by climate change, field surveys and in-depth interviews with fishermen and government officials were conducted. Livelihood risk factor (LRF) in the marine fishing sector included reduction of fishing days and fish production and damage to fishing vessels and fishing gear due to cyclone and sea-level rise. LRF in the aquaculture sector included cultured fish escape, reduction of aquaculture production, and water pollution due to Monsoon flood. A common challenge for two sectors was high interest rate on commercial loans. Small-scale tank aquaculture is recommended as AIG for securing income of artisanal fisheries communities. In the early stages of dissemination of small-scale tank aquaculture technology, it is necessary to prevent fishermen from struggling to repay high-interest rate loans through technology transfer and facility support by official development assistance. The aquaculture training center, along with the technical education, will also contribute toward expansion of local distribution network and marketing support to establish a value chain for local artisanal fisheries communities.

• 한국수자원학회논문집
• /
• 제52권spc2호
• /
• pp.823-833
• /
• 2019

This study presents the impact of natural flow patterns on downstream fish habitat and economic outcomes in the Dal Stream, Korea. The study reach is 3.35 km long, located downstream form the Goesan Dam. To assess such impact, this study performed physical habitat simulations. The River2D model was used for the computation of the flow and the HSI model for the habitat simulation. Two physical habitat variables, flow depth and velocity, were used. The Zacco platypus, Zacco temminckii, Coreoleuciscus splendidus, and Opsariichthys bidens were selected as the target species in the study area. Using the building block approach (BBA), the scenarios for the hydropeaking mitigation were presented. Scenario 1 and scenario 2 were proposed by using the magnitude - duration concept and averaged the hydrologic data over the each month, respectively. Simulation results indicated that the scenarios effects significantly increased by about 18.6% for the weighted usable area (WUA). In addition, hydroelectric power benefits with both scenarios were investigated. It was revealed that the change of storing and releasing water decreased by about 27% for hydroelectric power benefits. In order to increase economic benefits, the scenario was modified with the discharges corresponding to the hydropeaking condition except the flood season. As a result, the hydroelectric power benefits were almost the same, however the aquatic habitat for the target species increased by about 5%. The change of dam re-operations through natural flow patterns provides an opportunity to minimize environmental and economic benefits in order to balance water management.

• 한국수산과학회지
• /
• 제46권2호
• /
• pp.186-194
• /
• 2013

We compiled and analyzed long-term time-series data collected in Korea to evaluate changes in oceanographic conditions and marine ecosystems near Jeju Island ($33^{\circ}00^{\prime}-34^{\circ}00^{\prime}\;N$, $125^{\circ}30^{\prime}-127^{\circ}30^{\prime}\;E$) from 1981 to 2010. Environmental data included depth-specific time series of temperature and salinity that have been measured bimonthly since 1961 in water columns at 175 fixed stations along 22 oceanographic lines in Korean waters by the National Fisheries Research & Development Institute, and time series of estimated volume transport of the Tsushima Warm Current (TWC) and Korea Strait Bottom Cold Water (KSBCW) for the period from 1961 to 2008. We analyzed the species composition in terms of biomass of fish species caught by Korean fishing vessels in the waters near Jeju Island (1981-2010). Data were summarized and related to environmental changes using canonical correspondence analysis (CCA). The CCA detected major shifts in fish community structure between 1982 and 1983 and between 1990 and 1992; the dominant species were a filefish during 1981-1992 and chub mackerel from 1992 to 2007. CCA suggested that water temperature and salinity in the mixed layer and the volume transport of the TWC and the KSBCW were significantly related to the long-term changes in the fish community in the waters off Jeju Island. Fish community shifts seemed to be related to the well-established 1989 regime shift in the North Pacific. Further studies are required to elucidate the mechanisms driving climate change effects on the thermal windows and habitat ranges of commercial species to develop fisheries management plans based on reliable projections of long-term changes in the oceanographic conditions in waters off Jeju Island.

• 한국해안·해양공학회논문집
• /
• 제30권3호
• /
• pp.123-133
• /
• 2018

본 연구는 우리나라 방파제의 변천 과정에 대한 자료를 조사 정리 분석하였다. 그 결과를 요약하면 1) 심해설계파 재산정에 따라 설계파고가 상향되었다. 2) 수심(h)에 따른 상대설계파고($H_{1/3}/h$)의 연도별 변화는 1970년경 0.5에서 최근에는 0.6~0.7까지 증가하였다. 3) 1999년 이전에는 모든 설계에서 설계조위를 삭망평균만조위(H.W.L)를 적용하였으나, 1999년 이후부터 설계 시공일괄입찰에서 입찰자가 설계조위를 재산정하는 것이 가능해져 상향 적용하는 경향이 발생하였다. 4) 1999년 이전까지는 상대마루높이 ${\alpha}$값이 0.6~0.7 정도로 적용되었으나, 1999년도 이후 설계 시공된 방파제에서는 0.8~1.26 정도로 상향되었다.

• Ocean Science Journal
• /
• 제40권4호
• /
• pp.191-200
• /
• 2005

In this study an analytical tide model of uniform width with three sub-regions is presented. The three-subregions model takes into account step-like variations in depths in the direction of the channel as a way to examine the $M_2$ tide of the East China Sea (ECS) as well as the Yellow Sea (YS). A modified Proudman radiation condition has been applied at the northern open head, while the sea surface elevation is specified at the southern open boundary. It is seen that, due to the presence of an abrupt change in depth, co-amplitude lines of the $M_2$ tide are splitted to the east and west near the end of the ECS shelf region. Variations in depths, bottom friction and the open head boundary conditions all contribute to the determination of formation of amphidromes as well as overall patterns of $M_2$ tidal distribution. It is seen that increasing water depth and bottom friction in the ECS shelf results in the westward shift of the southern amphidrome. There is however no hint at all of the well-known degenerated tidal pattern being formed. It is inferred that a lateral variation of water depth has to be somehow incorporated to represent the tidal patterns in ECS in a realistic manner. Regarding the radiation factor introduced by Fang et al. (1991), use of a value larger than one, possibly with a phase shift, appears to be a proper way of incorporating the reflected waves from the northern Yellow Sea (NYS).

• 한국해양학회지
• /
• 제22권2호
• /
• pp.71-79
• /
• 1987

동해안 외해역 51개 정점의 표층 200m내 10개 표준 수심의 누년평균 수온자 료에 대한 조화분석을 통하여 수온의 연변동을 구명하였다. 연안에 인접한 해역에 서 연평균 수온의 등온선은 해안선에 거의 평행한 반면에, 외해에서는 등온선이 위 도선에 거의 평행한다. 수심이 증가함에 따라 수온의 연진폭은 지수함수적으로 감 소하고, 연위상은 거의 선형적으로 증가한다. 동해 남동해역에서의 평균적인 지수적 진폭 감소 수심 (e-folding depth)은 65 이고, 수심증가 200m에 따른 연위상의 변동 은 180 이며, 연직방향의 난류적 전도계수는 $4\textrm{cm}^2/sec$해안으로부터 수십해리 이내인 연안역의 수온 연변동은 외해의 수온 연변동과 상당히 다르다. 연안역 진폭의 지수 적 감소 수심은 외해에서 보다 얕으며, 수심에 따른 수온 연변동 상의 증가는 연안 쪽이 외해쪽보다 완만하다.

• 대한환경공학회지
• /
• 제32권3호
• /
• pp.271-277
• /
• 2010

본 연구에서는 다목적댐인 주암호에서 물리화학적 인자의 변화에 따른 미세조류의 계절적 변동특성을 파악하는 것을 목적으로 하여, 4회에 걸쳐 주암호 3개 지점에서 기초환경 변화와 Micro-, Nano-, Picoplankton의 계절적 군집변화 양상을 조사하였다. 강수량이 많고 수온이 가장 높았던 7월에 평균 Chl-a의 농도가 18.03 mg/$m^3$으로 가장 높은 결과를 나타내었으며, 그 다음이 10월, 4월 그리고 1월이 가장 낮은 1.86 mg/$m^3$으로 조사되었다. 모든 계절에서 표층 보다는 수심 2 m와 5 m의 수층에서 가장 높은 Chl-a의 농도를 나타내었으며, 그 이상의 수심에서는 Chl-a의 농도가 점차 감소하는 경향을 보였다. 전체적으로 20~200 ${\mu}m$의 Microplankton이 33.9~54.2%로 가장 높은 비율을 차지하고 있었으며, 2~20 ${\mu}m$의 Nanoplankton이 24.3~30.5%를 점유하고 있었으며, 나머지 2 ${\mu}m$ 미만의 Picoplankton이 21.6~41.2%의 비율을 차지하고 있는 것으로 조사되었다. 따라서 주암호에서 취수된 원수의 경우는 picoplankton과 같은 미세플랑크톤이 상당비율로 포함되어 있기 때문에 응집?침전 및 사여과 공정 등의 같은 정수처리 공정에서 제거되지 못한다면 후속공정인 염소소독에 의해 미세플랑크톤의 세포내의 물질이 생물학적으로 분해 가능한 유기물(AOC; Assimilable organic carbon)로 전환되어 후속 공정인 급수 배수관망에서 세균 및 병원미생물의 재증식(Regrowth)을 유발시킬 가능성이 있을 것을 판단해 볼 수 있다.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2010년도 추계 학술발표회
• /
• pp.1343-1349
• /
• 2010

This paper presents the behavior of the soil based on the Gap Parameter during the Shield TBM tunnel excavation in sandy soil. This study reproduced the tunnel before and after the excavation according to the diameter of the tunnel, water ratio and depth to execute a Scaled Model Test and analyzed the behavior change of the upper soil. As a result, tunneling after for soil stress decreased was similar in all the Case. In addition, the soil stress decreased was in water ratio increases.