• 수산해양기술연구
• /
• 제22권3호
• /
• pp.36-41
• /
• 1986

Uederwater ambient noise was measured at the set net in the Neung-Po Eay. The environment characteristics depend upon oceanographic conditions of sound propagation and its implication on the source of ambient noise. The results of measurement and analysis were as follows: 1. The frequency of the maximum noise level of two passenger. vessels was around 300 Hz. The spectrum level of the fast vessel (the Air-Ferry) was lower than the little slow vessel (the Olympic) between 50-150 Hz in frequences. 2. The spectrum level of the surface in the playground of the set net was lower than the deeper water till 500 Hz, but over that frequency the level was getting lower as the depth was deep. 3. The spectrum level outside the bag of the set net was greater than the inside between 50 and 700 Hz, but over 1,500 Hz the level inside the bag was higher than the outside. 4. The spectrum level of the outside of the breeding tank was higher than the inside in the daytime. However at night opposite phenomenon occurs.

• 환경영향평가
• /
• 제16권6호
• /
• pp.421-432
• /
• 2007

To investigate temporal and spatial variations of hydrodynamics and environmental conditions in Gyeonggi Bay, including Han River estuary, numerical experiments were performed using 3-dimensional fine grid numerical ocean model. The model successfully reproduced the physical phenomena already known in Gyeonggi Bay where tide and fresh water discharge are dominant forcings. The calculated harmonic constants of tide and tidal current agreed well with those of observations at nine tide stations and two tidal current stations. Tidal asymmetries along the Yeomha Waterway, mainly caused by non-linear effect, were well reproduced and agreed well with observations. Time series of salinity at four stations(A, B, C and D) and horizontal distributions of monthly averaged salinity show that Gyodong and Seokmo Waterways play an important role in fresh water discharge into the Gyeonggi Bay rather than Yeomha Waterway.

• 해양환경안전학회:학술대회논문집
• /
• 해양환경안전학회 2009년도 춘계학술발표회
• /
• pp.41-48
• /
• 2009

부사연안해역의 멸치와 미역의 생산량($1990{\sim}2007$)의 연변동을 규명하기 위하여 대한해협의 해양 관측 자료($1990{\sim}2007$)로 수온과의 관련성을 살펴보았다. 멸치와 미역 생산량 모두 허마다 변동은 있으나 전반적으로 점차 증가하는 추세를 보였으며 수온약층 이천에서 평년 보다 높은 수온이 나타날 때 멸치의 생산량은 증가하고 미역의 생산량은 감소하다. 한편 수온약층 이심에서 평년보다 낮은 수온이 나타날 때 멸치의 생산량은 감소하고 미역의 생산량은 증가하는 경향으로 분석되었다.

• 해양환경안전학회:학술대회논문집
• /
• 해양환경안전학회 2003년도 추계학술발표회
• /
• pp.175-180
• /
• 2003

수온과 멸치와 김 생산량의 관계를 규명하기 위해, $1980\~2002$년 한국 남해 동부해역에서 생산량과 해양관측자료를 분석하였다. 한국 남해 동부해역에서 년간 멸치와 김 생산량은 들 다 해마다 변동은 있으나 전반적으로 점차 증가하는 추세를 보였다. 멸치와 김 생산량은 해양환경 특히, 수온과 밀접한 관계가 있는 것으로 나타났다. 즉, 표층은 평년보다 높고, $0\~20m$에서의 수온은 평년보다 낮았을 때 특히 저층에 약 $15^{\circ}C$ 이하의 저온수가 존재했을 때, 들 다 생산량이 저조하였다.

• Fisheries and Aquatic Sciences
• /
• 제11권1호
• /
• pp.50-60
• /
• 2008

Harmful algal blooms (HABs) of Cochlodinium polykrikoides frequently occur around the South Sea of Korea, causing. economic losses in coastal breeding grounds. HAB outbreak scale usually changes each year depending on physical, biological and environmental conditions. Relatively large-scale HABs occurred in 1995, 1997, 1999, 2001, 2002 and 2003 with respect to spatial scale, duration and maximum density. Considering HAB scale and temperature distributions around the South Sea, we found that low coastal temperatures in August correspond to enormous HAB outbreaks. Cold waters created by coastal upwellings around the southeastern coast of Korea also corresponded to these outbreaks. Serial oceanographic investigations in August in the South Sea revealed that sea surface temperature anomalies had distinctively negative values when large-scale HAB outbreaks appeared. With regard to temperature differences between the surface and the 30-m layer, there was a tendency for large-scale outbreaks when temperature gradients around the seasonal thermocline weakened.

• 대한조선학회논문집
• /
• 제51권4호
• /
• pp.300-310
• /
• 2014

This paper presents a mooring design procedure of a floating offshore wind turbine. The environment data of south offshore area of Jeju collected from Korea Hydrographic and Oceanographic Administration(KHOA) are used for hydrodynamic analyses as environmental conditions. We considered a semi-submersible type floating wind turbine based on Offshore Code Comparison Collaborative Continuation(OC4) DeepCWind platform and National Renewable Energy Laboratory(NREL) 5 MW class wind turbine. Catenary mooring with studless chain is chosen as the mooring system. Important design decisions such as how large the nomial sizes are, how long the mooring lines are, how far the anchor points are located, are demonstrated in detail. Considering ultimate limit state and fatigue limit state based on 100-year return period and 50-year design life, respectively, longterm predictions of breaking strength and fatigue are proposed.

• International Journal of Ocean System Engineering
• /
• 제3권4호
• /
• pp.209-217
• /
• 2013

This paper presents a mooring design procedure for a floating offshore wind turbine. Offshore environmental data for Jeju are taken from KHOA (Korea Hydrographic and Oceanographic Administration) and used for the environmental conditions in numerical analyses. A semi-submersible-type floating wind system with a 5-MW-class wind turbine studied by the DeepCwind Consortium is applied. Catenary mooring with a studless chain is chosen as the mooring system. Design deliverables such as the nominal sizes of chain and length of the mooring line are decided by considering the long-term prediction of the breaking strength of the mooring lines where a 100-year return period is used. The designed mooring system is verified using a fatigue calculation based on rain-flow cycle counting, an S-N curve, and a Miner's damage summation of rule. The mooring tension process is obtained from time-domain motion analyses using ANSYS/AQWA.

• 환경생물
• /
• 제25권3호
• /
• pp.205-214
• /
• 2007

Marine environmental characteristics on the dinoflagellate cysts distribution in surface sediment of the southwest sea of Korea were investigated from 21 stations in September 2003, and 36 stations in June, 2004. The water mass characteristics indicated that the southwest sea of Korea is characterized by various oceanographic conditions due to coastal waters of Korea and China. The Tsushima warm currents and the cold bottom water of the Yellow Sea. Mud contents and chlorophyll a concentrations were higher in central region such as, Namhaedo, Yeosu and Goheung coast than in western region such as, Wando, Haenam and Jindo coast in the South Sea of Korea. A total of 35 taxa of dinoflagellate cysts were identified representing 21 genera, 33 species, 2 unidentified species. Cyst abundance ranged from 13 to 527 cysts $g-dry^{-1}$, showing higher abundance in the coastal areas than in western region of the South Sea of Korea. From the result of the PCA analysis, the distribution of dinoflagellate cysts was not only related to the different water masses which appeared in the southwestern sea but also to physical and biological parameters such as water temperature, light, surface sediment faces and phytoplankton biomass.

• 한국해양학회지:바다
• /
• 제11권1호
• /
• pp.11-20
• /
• 2006

낙동강 하구는 담수와 해수가 만나 복잡한 순환 양상을 보이는 지역으로, 1987년에 준공된 하구둑의 건설로 지형적인 변화와 함께 여러 가지 해양 환경적인 변화를 가져왔다. 하구둑 건설 전과 후의 특징을 보면, 건설 전에 비해 흐름이 약해졌고 조류가 흐름을 주도하던 혼합 기작이 담수의 방류가 주도하는 체계로 변하였다. 이러한 담수의 방류는 그 정도에 따라 낙동강 하구둑 하류부 담수의 거동과 혼합 특성을 변화시켰으며 해수 순환에도 큰 영향을 주었다 본 연구에서는 낙동강 하구둑 하류부의 유동 특성을 하구둑의 수문 개폐에 초점을 맞춰 분석하였다.

• 수산해양기술연구
• /
• 제38권2호
• /
• pp.140-148
• /
• 2002

황해 주요어족생물의 분포 특성을 파악하기 위한 연구의 일환으로 황해의 위도 33$^{\circ}$00'N~37$^{\circ}$00'N, 경도 24$^{\circ}$00'E~126$^{\circ}$00'E를 대상 해역으로 설정하여, 1999년 5월, 1999년 8월, 2000년 4월의 3회에 걸쳐 여수대학교 실습선 청경호와 동백호를 사용하여 실시한 해양학적 및 음향학적조사에 대한 결과를 요약하면 다음과 같다. 1. 조사당시 황해 저층수온의 지리적인 분포는 제주도 서부해역, 목포 서부해역, 군산 서부해역의 3권역으로 크게 구분되었고, 수온차는 제주도 서부해역이 군산 서부해역보다 2~5$^{\circ}C$ 정도 높았다. 또한 어족생물자원의 분포와 관련이 깊은 수온 약층(thermocline)은 5월보다는 8월에 뚜렷하게 형성되었다. 2. 황해의 조사대상해역에 대한 면적산란계수는 값은 38kHz의 경우, 제주도 서부해역에서 가장 나타났고, 위도가 높을수록 낮은 경향을 나타내었다. 그러나 120kHz의 경우에 있어서는 38kHz와 다른 양상을 보여 제주도 서부해역에서 보다는 목포 및 군산 서부해역에서 상대적으로 높은 값을 나타내었다. 3. 면적산란계수의 연직분포는 수온약층(thermocline)을 경계로 그 값이 뚜렷하게 구분되었는데, 수온약층이 발달된 해역일수록 표출부 저층부에서의 면적 산란계수가 높았고, 동서방향에 대해서는 연안이나 근해쪽보다는 그 중심부근에서 면적산란계수가 높은 경향을 나타내었다. 4. 트롤망고에 해당되는 저층 5m에 대한 면적 산란계수의 값은 대체적으로 어획량에 비례하는 경향을 나타내었고, 서식 어종의 차이에 따라 저층성 어종은 38kHz에서, 중층성 어종은 120kHz에서 면적산란계수가 높게 나타나는 경향을 보였다.