• Title/Summary/Keyword: 수조(修造)

Search Result 1,674, Processing Time 0.03 seconds

A Study on Wave Responses of Vertical Tension-Leg Circular Floating Bodies (연직인장계류된 원형부유체의 파랑응답에 관한 연구)

  • Lee, Kwang-Ho;Kim, Chang-Hoon;Kim, Do-Sam
    • Journal of Korean Society of Coastal and Ocean Engineers
    • /
    • v.23 no.3
    • /
    • pp.248-257
    • /
    • 2011
  • In the present study, we proposed a new numerical wave tank model to analyze the vertical tension-leg circular floating bodies, using a 2-D Navier-Stokes solver. An IBM(Immersed Boundary Method) capable of handling interactions between waves and moving structures with complex geometry on a standard regular Cartesian grid system is coupled to the VOF(Volume of Fluid) method for tracking the free surface. Present numerical results for the motions of the floating body were compared with existing experimental data as well as numerical results based on FAVOR(Fractional Area Volume Obstacle Representation) algorithm. For detailed examinations of the present model, the additional hydraulic experiments for floating motions and free surface transformations were conducted. Further, the versatility of the proposed numerical model was verified via the numerical and physical experiments for the general rectangular floating bodies. Numerical results were compared with experiments and good agreement was archived.

Effects of Wave Focusing Device on Performance of OWC Chamber (OWC형 파력발전 공기실의 파랑집중장치의 효과에 대한 수치적인 연구)

  • Liu, Zhen;Hyun, Beom-Soo;Hong, Key-Yong;Jin, Ji-Yuan
    • Journal of the Korean Society for Marine Environment & Energy
    • /
    • v.13 no.1
    • /
    • pp.12-17
    • /
    • 2010
  • Oscillating Water Column (OWC) device has been widely employed in the wave energy conversion. Wave Focusing Device (WFD) is proposed to be helpful for improving the operating performance of OWC chamber. In the present paper, a Numerical Wave Tank (NWT) using two-phase VOF model is utilized to simulate the generation and propagation of incident regular waves, water column oscillation inside the chamber. The NWT consists of the continuity equation, Reynolds-averaged Navier-Stokes equations and two-phase VOF functions. The standard k- turbulence model, the finite volume method, NITA-PISO algorithm and dynamic mesh technique are employed. Effects of WFD on the operating performance of OWC chamber are investigated numerically.

Water Vapor Transmission for T800/AD6005 Based Composite Motor Case (T800/AD6005계 복합재 연소관의 습기 투과에 관한 연구)

  • 박명규;류백능;최영보;도영대
    • Journal of the Korean Society of Propulsion Engineers
    • /
    • v.2 no.1
    • /
    • pp.50-58
    • /
    • 1998
  • Water vapor transmission was tested in water bath controlled by $20^{\cire}C$, 90%RH for T800/AD6005 based composite motor case which made by filament winding method. We detected internal relative humidity of composite motor case by inserting the humidity detector through the head of motor case for the study of humidity transmission through the wall of composite motor case. We found out that this composite material appears the water vapor flux of 2.88${\times}$$10^{-9}$g/$\textrm{m}^2$sec and diffusivity of 7.98${\times}$$10^{-7}$$\textrm{mm}^2$/sec at $20^{\cire}C$, 90%RH water vapor condition.

  • PDF

Development of Numerical Tank Using Open Source Libraries and Its Application (오픈 소스 라이브러리를 이용한 수치수조 구현 및 적용)

  • Park, Sunho;Rhee, Shin Hyung
    • Journal of the Korean Society of Marine Environment & Safety
    • /
    • v.20 no.6
    • /
    • pp.746-751
    • /
    • 2014
  • In this paper, ship performance prediction solver was developed using open source computational fluid dynamics (CFD) libraries. The mass- and momentum-conservation equations and turbulent model with a wall function for the turbulent closer were considered. The volume fraction transport equation with a high-resolution interface capturing scheme were selected for free-surface simulation. The predicted wave pattern around KRISO container ship (KCS) using developed program showed good agreement against existing experimental data. For the revolution of a propeller in the propulsive test, general grid interface (GGI) library was used. The predicted propulsive performance showed 7 % difference against experimental data. Two-phase mixture model was developed to simulate a cavitation and applied to a propeller. The sheet cavitation on the propeller was predicted well. From results, the potential of the numerical tank developed by open source libraries was verified by applying it to KCS.

An Experimental Study on Flow Characteristics in the Open Annular Flume (환형수조에서 흐름특성에 관한 실험적 연구)

  • Choi, In Ho;Kim, Jong Woo
    • Journal of Wetlands Research
    • /
    • v.21 no.3
    • /
    • pp.207-214
    • /
    • 2019
  • This study investigated the flow characteristics in an annular flume with a free water surface using the Acoustic Doppler Velocimeter(ADV) in the laboratory. The flow was driven by the rotation of the inner cylinder in a way designed not to interfere with flocculation of cohesive sediments. The effect of the inner cylinder for the longitudinal velocities showed highest near the moving boundary and decreased towards the outer wall. At the lower longitudinal velocity, there was a peak in turbulent kinetic energy near the bed, whereas it moved upward to with increasing of the velocity. The longitudinal velocities estimated using the power law were in good agreement with the measured values than the values predicted by the log-law with roughness lengths. The average friction velocities evaluated by Reynolds shear stress were smaller than the values calculated using the log-law and power law when increasing the longitudinal velocity.

A Study on the Habitat Use of Waterbirds and Grading Assessment of the Tidal Flat at Muan Bay in Jeollanamdo, Korea (전라남도 무안만에 도래하는 수조류의 서식지 이용 및 갯벌등급 평가)

  • Kang, Tae-Han;Yoo, Seung-Hwa;Lee, Si-Wan;Choi, Ok-In;Lee, Chong-Bin
    • Korean Journal of Environment and Ecology
    • /
    • v.22 no.5
    • /
    • pp.521-529
    • /
    • 2008
  • This research conducted a survey on waterbirds visiting this area four times by season from February to October in 2007 to look into the habitat use of waterbirds, to do a value and grade testing of the tidal flat by dividing the foreshore on Muan Bay located in Jeollanam-do into four areas (Dongam, Guro, Bokryong and Wangsan tidal flats). The survey results revealed that there existed a total of 15,755 individuals of 54 species including 2 species of grebes, 7 species of herons, 7 species of dabbling ducks, 6 species of diving ducks, 20 species of waders, 3 species of gulls and 9 other species and this survey also observed 9,291 individuals of the wading birds as a dominant group on Muan Bay. In these classified groups, the gulls and waders were observed to mostly use Dongam tidal flat as their habitat, while the group using Guro tidal flat as their habitat was mostly grebes, dabbling and diving ducks. As a result of UPGMA clustering analysis in consideration of the species and number of individuals, there appear the close similarities between Dongam and Bokryong tidal flats and so do Guro and Wangsan tidal flats. Taking a look at the grading of tidal flats by setting up ecological indexes, such as diversity index, abundance index, and dominance index, etc. legally reserved species and maximum number of individuals as a standard, the rank for the value and importance degree of Bokryong tidal flat appeared higher than that of the other three tidal flats. Like this, the gradation of tidal flats according to waterbirds are judged to able to suggest objective data on the issue of proper judgment and designation of valuable tidal flat areas and its subsequent effective preservation and management.

AN EXPERIMENT ON THE HEARING OF RAINBOW TROUT IN THE INDOOR AQUARIUM IN BUSAN (부산지방에서 실내수조를 이용한 무지개송어의 사육실험)

  • KIM In-Bae;JO Jae Yoon
    • Korean Journal of Fisheries and Aquatic Sciences
    • /
    • v.10 no.4
    • /
    • pp.267-273
    • /
    • 1977
  • Rainbow trout were reared in a small indoor aquarium which was equipped with a simple recirculating biofilter combined with a small amount of inflowing water for 199 days from April 25 to November 10, 1977 in Busan where very hot summer air temperature is encountered, and results obtained were promissing as following; 1. The aquarium has dimensions of $1m\;\times\;1m\;\times\;67cm(depth)$, and a bottom center sedimentation chamber of conical type through which out-flowing water is pushing fecal matter and other detritus outward. The conical sedimentation chamber measures 20 cm depth and 20 cm diameter at its upper mouth and tapers to the bottom end which is connected to 4 cm diameter draining pipe. The draining pipe goes through under the tank and then is elevated on the side. The water depth was maintained at about 40 cm depth by adjusting the heigh of draining pipe. The filter bed contained 16 l of $3\~5\;mm$ zeolite gravels, and water circulation rate was about 1030 l/hr. 2. Continuous inflowing water resulted in a good elimination of waste materials through its outflowing water thus reducing waste loading in the filter. 3. Mean temperature of water in the rearing aquarium containing about 400 l water volume was maintained at around 20 to $22^{\circ}C$ by 0.59 l/min of the inflowing well water which usually maintained the temperature of $17^{\circ}C$ during the hot summer season from the first of July to the first of October when the 10-days-mean air temperature ranged from $20^{\circ}\;to\;27.3^{\circ}C$ $(total\;mean\;24.6^{\circ}C) $ and under this condition the fish continued normal growth. 4. The production per 1 l/min of inflowing water with this simple biofilteration reached 30 hg. 5. The total cost including all feed and power during this experimental rearing period fell well within the economic establishment and if the feed and filteration system are improved the benefit-cost ratio will be much increased.

  • PDF

The survival rate of fish discarded from trawler (트롤 어선에서 어획후 투기된 어류의 생존율)

  • 안희춘;양용수;박창두;조삼광;박해훈;정의철
    • Journal of the Korean Society of Fisheries and Ocean Technology
    • /
    • v.39 no.2
    • /
    • pp.87-91
    • /
    • 2003
  • Experimental fishing was carried out to investigate the survival rate of fishes discarded after hauling from the trawl and to develop the fishing gear and method for fisheries management which can improve the survival rate of young fishes escaped from the trawl codend in offshore korean southern sea and off Cheju Island of Korea. The young fishes were bred in fish cage on the board to measure the sustainable survival time for fishes escaped from grid panel and codend. The obtained results are summarized as follows' 1. Japanese flying squid(Todarodes pacjficus), mitra squid(Loligo chinesis), hair-tail( Trichiurus lepturus), john dory(Zeus japonicus), spanish mackerel(Scomberomorus niphonius), redlip croaker (Pseudosciaena polyactis) and blackthroat seaperch(Doederliinia berycoides) were dead instantly after hauling. 2. Survival rate of tiger shark(Galeocerdo cuvier), conger eel (Conger myriaster), red skate (Dasyatis akajei), black scraper(Navodon modestus) and japanese fan lobster(Ibacus ciliatus) might be high after discarding because they survived for long hours in fish cage. 3. Blotched eelpout(Zoarces gili) escaped from the escapement device(grid) was dead within 6 hours in the water tank installed on the board but 97% of tiger shark and 72% of conger eel survived over 72 hours. 4. Red skate escaped from trawl codend was dead within 60 hours in the water tank installed on the board but sustainable survival time of 25% of octopus(Paroctopus dofleini) and 100% of black scraper was over 72 hours. 5. Compared with the survival rate of rosefish(Helicolenus higendorfi) escaped from the escapement device(grid) and trawl codend, all of the rosefish escaped from the grid was dead within 7.2 hours but 8.3% of the rosefish escaped from the codend survived over 72 hours. 6. In comparison with the survival rate of japanese fan lobster survived over 72 hours, survival rate of japanese fan lobster escaped the codend was much higher as 75% than 33% of japanese fan lobster escaped from the grid.

Study on the Influence of Waterbirds Distribution According to the Restoration of Intertidal Zone (조간대 복원이 수조류의 분포에 미치는 영향)

  • Park, Chi-Young;Shin, Man-Seok;Kim, Ho-Joon;Paek, Woon-Kee;Lee, Joon-Woo
    • Korean Journal of Environment and Ecology
    • /
    • v.30 no.5
    • /
    • pp.837-847
    • /
    • 2016
  • In this study, the bird fauna of Sihwa Lake in Gyeonggi Province were investigated from 2009 to 2014 to identify the effect of the restored intertidal zone on bird community. Based upon the analysis of the habitat status and distribution change of water birds in the intertidal zone, the following conclusions were obtained. The number of water bird individuals increased by approx. 40 thousand after the restoration. Most of water bird species increased, but diving ducks decreased. Analysis of the number of individuals of water birds before and after the intertidal zone restoration showed that there was a significant increase in the number of shorebird individuals. There is a habitat use pattern change in the southern tideland intertidal zone that includes the largest area of widened intertidal zone and the inland waters of the intertidal zone. This is related to the change of benthic ecosystem which is the food source of birds. The benthic ecosystem in restoring Sihwa Lake has been stabilized with a decrease in opportunistic species and consistent increase in equilibrium species that are sensitive to pollution. As a result, the environmental conditions for shorebirds have been improved. The restoration of intertidal zone affected the habitat use and distribution patterns of water birds in a short period of time. Compared to before restoration, all the water birds now use the wide area of the intertidal zone with no partiality and it is confirmed that the restoration greatly affected the distribution of shorebirds and swan & geese. This study was conduced to identify the effects of an artificial restoration of intertidal zone due to tidal power generation of bird species. In terms of maintaining and improving biodiversity, the intertidal zone restoration was recognized to be important and still shows positive results. This study is expected to provide a direction when an alternative is required to maintain and improve biodiversity in a similar situation in the future.

참돔 노지종묘생산과 요각류 번식을 위한 적정 시비제

  • 방인철;박상용;권성민;신현웅
    • Proceedings of the Korean Aquaculture Society Conference
    • /
    • 2003.10a
    • /
    • pp.3-63
    • /
    • 2003
  • 우리나라 서해안의 폐염전 또는 대하양식장을 이용한 해산어 종묘생산이 조피볼락, 감성돔, 숭어 등을 대상으로 이루어지고 있다. 이렇게 생산된 종묘는 기형개체가 전혀 없는 건강 종묘이며, 생산 원가 또한 육상수조식에 비해 최고 5배정도 낮다. 한편 참돔은 육상수조에서 종묘생산시 기형률이 비교적 높게 나타나므로 노지를 이용한 종묘생산이 요구되고 있다. 현재 노지 종묘생산시 요각류 번식을 위한 시비제로는 암모니아, 인산염, 칼륨 등이 함유되어 있는 화학비료(요소, 복합비료)나 계분, 돈분, 우분 등의 유기질 비료가 주로 사용되고 있다. 그러나 화학비료를 사용시 급격한 수질변화로 요각류의 폐사가 발생하고, 매년 지속적인 생산량을 기대하기가 어려운 문제점이 있다. 따라서 적절한 시비제를 구명하기 위하여 유기질 비료(알팔파, 숙성계분)와 화학비료(요소, 복합)를 단독 또는 병행 사용하여 2개월간의 동ㆍ식물플랑크톤의 변동량과 치어의 생존율을 조사한 결과, 유기질 비료는 부화자어가 입식된 이후에도 연속하여 시비하여도 생존율에 영향을 미치지 않았으나, 화학비료의 경우 일정 농도 이상에서는 동ㆍ식물플랑크톤의 번식에 장애를 초래하였고 이에 따라 자어가 전량 폐사하였다. 실험군의 생존율은 육상수조에서 40%, 알팔파와 숙성계분을 시비한 실험군이 15%, 요소, 복합, 알팔파를 시비한 실험군이 10%, 요소, 복합, 숙성 계분을 시비한 실험군이 8%, 요소와 복합을 시비한 실험군은 0%를 나타내었다. 또한 기형률에 있어 노지 실험군은 0.7%로 매우 낮게 나타났으나, 육상수조 실험군은 61%에 해당하는 치어가 기형이었으며, 그 형태도 다양하게 나타났다.fer, Artemia sp., copepods, 부화 25일째부터는 copepods였다. 초기성장은 부화직후 전장 1.95 mm였던 것이 10일째는 2.96 mm, 20일째는 3.89 mm, 30일째는 12.9 mm, 50일째는 35.1 mm를 나타내었다. 그러나 말쥐치 자ㆍ치어가 성장함에 따라 발생하는 지속적인 폐사와 종묘의 수송시 발생하는 폐사를 줄일 수 있는 방법이 추후에 해결되어야 할 것으로 사료된다.8,000~215,000 마리의 자어를 낳아서 개체에 따라 큰 차이를 나타내었다. 1999년에는(어미 : 전장 20.7~25.5cm, 체중 205.5~396.4g) 1 회 출산때마다 7,000~50,000 마리의 자어를 출산하였다. 3. 출산간격. 다회 출산한 쏨뱅이 어미가 첫 번째 출산에서 다음 출산까지 소요되는 기간을 조사한 결과 13일에서 25일이 걸리는 것으로 나타났다. 특히 4회 출산 한 1998년 쏨뱅이 어미는 첫 번째 출산 후 19일만에 두 번째 출산이 이루어 졌고 각각 13 일과 14 일만에 세 번째, 네 번째 출산이 이루어져 총 46일 동안 4회에 거쳐 자어를 출산하였다. 4. 출산자어의 크기. 1997년 3회 출산한 쏨뱅이의 출산시기별 자어 크기를 조사한 결과 첫 번째 출산에서는 평균전장 4.1$\pm$0.07mm의 자어를 낳았으나 두 번째 출산에서 자어의 크기는 평균전장이 3.9$\pm$0.11mm, 세 번째 3.8$\pm$0.12mm로 점차 작은 경향을 나타내었다..27mm(평균 1.76mm, n=20) 그리고 Snout length 0.74~l.67mm(평

  • PDF