• 제목/요약/키워드: Knots

검색결과 428건 처리시간 0.02초

온산공단 부근의 해양오염물질 이동 (TRANSPORT AND DIFFUSION OF POLLUTANTS IN THE COASTAL WATERS OF ONSAN INDUSTRIAL COMPLEX)

  • 장선덕;이종섭;한경화
    • 한국수산과학회지
    • /
    • 제13권4호
    • /
    • pp.151-162
    • /
    • 1980
  • 온산만내에서는 대조시 조류가 우세한 편이지만 (0.1 kt), 소조시의 표층류는 매우 불규칙하며(0.07 kt), 취송류와 지형성 소용돌이의 영향을 크게 받는다. 대조시 만북부에서는 썰물 때 동류하고 밀물 때 서류한다. 만남부에서는 밀물은 서북서류하고 철물은 동북동류이다. 만외에서는 조류가 우세하여 밀물 때 남-남남서류하고 썰물 때 북-북북동류한다. 최대유속은 $1\~1.1kt$로 관측되었다. 소조시의 항류는 북북동 14.3cm/sec였다. 우봉갑 남쪽 만입부에는 밀물갈때나 썰물갈 때 지름 약 1km미만의 시계방향 소용돌이가 존재하여 해수의 정체성이 비교적 강한편이다. 겨울의 취송류는 대체로 남류하며 최대유속은 약 0.1kt에 달한다. 온산만내에서 점원방출한 염료는 바람에 의해 변형되면서 주로 조류에 따라 만구쪽으로 이동, 분산하였고, 방출 3시간후의 평균확산계수는 $4.4\times10^4cm^2/sec$ 였다. 만외 만입부 시계방향의 환류내에서는 이보다 다소 낮은 값을 보였다.

  • PDF

차인 형상에 따른 레저선박의 저항특성에 관한 연구 (A Study on the Resistance Characteristics of Leisure Boat According to Chine Shape)

  • 김주열;최준호;오정근
    • 해양환경안전학회지
    • /
    • 제23권5호
    • /
    • pp.566-573
    • /
    • 2017
  • 고속 활주선에서 차인은 활주자세 변화 뿐 아니라 선체의 균형을 잡아주는 역할을 하며, 저항성능에 큰 영향을 미친다. 그러나 이러한 차인의 설계는 배수량, 선저경사각, 흘수, 선폭 등 다양한 설계 인자들에 영향을 받는 변수로 많은 경험을 필요로 한다. 본 연구에서는 경험식이 아닌 계산을 통해 차인에 대한 설계 시 형상에 대한 기본적인 지침 마련을 목적으로 고속 활주선의 차인의 형상에 따른 저항성능에 대해 계산하였다. 설계는 상용 설계 프로그램인 Yacht-one을 이용하였으며, 유동해석은 상용 해석프로그램인 STAR-CCM+으로 DFBI(Dynamic Fluid Body Interaction)방법을 적용하여 수행하였다. 초기 설계 차인 각도인 17도를 기준으로 차인 15도, 차인 16도, 차인 19도로 변경하여 설계 속도인 30노트에서 해석을 수행하였다. 그 결과, trim은 4개의 차인 중 16도가 가장 컸으며, heave는 차인 15도에서 가장 우수하였다. 해석 결과를 봤을 때 저항 측면에서 초기 설계 각도인 차인 17도 보다 차인 16도가 우수함을 보이고 있어 실제 설계 시 초기 설계 각도에서 +2도, -2도의 범위로 계산을 통해 저항 성능과 자세에서 우수한 차인을 선택해야 함을 알 수 있다.

Dynamic analysis of slack moored spar platform with 5 MW wind turbine

  • Seebai, T.;Sundaravadivelu, R.
    • Ocean Systems Engineering
    • /
    • 제1권4호
    • /
    • pp.285-296
    • /
    • 2011
  • Spar platforms have several advantages for deploying wind turbines in offshore for depth beyond 120 m. The merit of spar platform is large range of topside payloads, favourable motions compared to other floating structures and minimum hull/deck interface. The main objective of this paper is to present the response analysis of the slack moored spar platform supporting 5MW wind turbine with bottom keel plates in regular and random waves, studied experimentally and numerically. A 1:100 scale model of the spar with sparD, sparCD and sparSD configuration was studied in the wave basin ($30{\times}30{\times}3m$) in Ocean engineering department in IIT Madras. In present study the effect of wind loading, blade dynamics and control, and tower elasticity are not considered. This paper presents the details of the studies carried out on a 16 m diameter and 100 m long spar buoy supporting a 90 m tall 5 MW wind turbine with 3600 kN weight of Nacelle and Rotor and 3500 kN weight of tower. The weight of the ballast and the draft of the spar are adjusted in such a way to keep the centre of gravity below the centre of buoyancy. The mooring lines are divided into four groups, each of which has four lines. The studies were carried out in regular and random waves. The operational significant wave height of 2.5 m and 10 s wave period and survival significant wave height of 6 m and 18 s wave period in 300 m water depth are considered. The wind speed corresponding to the operational wave height is about 22 knots and this wind speed is considered to be operating wind speed for turbines. The heave and surge accelerations at the top of spar platform were measured and are used for calculating the response. The geometric modeling of spar was carried out using Multisurf and this was directly exported to WAMIT for subsequent hydrodynamic and mooring system analysis. The numerical results were compared with experimental results and the comparison was found to be good. Parametric study was carried out to find out the effect of shape, size and spacing of keel plate and from the results obtained from present work ,it is recommended to use circular keel plate instead of square plate.

연안어장의 부유성 폐기물 분포와 조성에 관한 연구 II. 남해 중부해역의 폐기물 수송 (A Study on the Distribution and Composition of Floating Debris in the Coast of Korea II. Transport of Debris in Middle Part of Southern Sea)

  • 김종화
    • 한국수산과학회지
    • /
    • 제32권3호
    • /
    • pp.338-344
    • /
    • 1999
  • Floating debris was recorded from a training ship, $\sharp$1 Kwanaksan, of Pukyong National University with about 10 knots speed at July 15th and 20th of 1997. The sampled area is the middle of southern sea of Korea, divided into 44 unit segments on survey routes. Debris fabrication materials were categorized with 6 items using the following; man-made or natural wood items, paper and cardboard, nylon netting and rope, styrofoam, plastics, floating metal and glass containers. All identified items within a 100 $\pm$ 2 m wide band were recorded but ignored if beyond this boundary. The results of distribution and transport of floating debris in the area are as follows: 1. The quantities of debris during the survey were distributed from $1.6\~369.7\;items/km^2$. The most obvious trend is the widespread distribution of all debris. The highest densities of all debris were discovered in the coastal waters of Namhae and Yokji island, and of about 50 km off from the southward of Yokji and about 74 km off from the eastward of Komun island. Especially many of small styrofoams within $\phi$20 cm were observed in these segments. 2. Styrofoams and plastics were composed of $83.5\%$ among all debris, next woods items, $9.8\%$. 3. The quantities, distribution shapes and composition of debris were varied as the observed duration and the natures of each items. 4. These phenomena are concluded that firstly they depend on the river discharges included debris due to precipitation falls, secondly inflow or dumping debris are drifting to the off-shore by Kuroshio currents present at their adjacent sea, But on the basis of the observed data it is difficult that source position, quantities and inflow items of debris are identified, and also the transport processes is pursue. further more surveys are continuously being investigated, and from this it is hoped that a much wider coverage can be achieved, perhaps on all sites of the Coast of Korea and contributed to the stationary area, finding of sources, removal method of debris and resistants of marine productivity.

  • PDF

대한해협의 자치어 분포상 (The Distribution of Fish Larvae in the Korea Strait)

  • 김용억
    • 한국수산과학회지
    • /
    • 제17권3호
    • /
    • pp.230-243
    • /
    • 1984
  • 1983년 7월과 11월, 2차례에 걸친 대한해협에서의 자치어의 분포를 조사한 결과는 다음과 같다. 1. 대한해협에서 채집된 자치어표본중에서 과, 속 또는 종의 계급까지 동정되어진 것은 27과 37속 38종이었다. 2. 어종별로 가장 많이 출현한 종은 E. japonica ($88.6\%$)였으며, 이어서 Diaphus sp.($1.7\%$), Gobiidae sp.($1.3\%$), Bothus sp.($0.7\%$)의 순이었다. 3. 계절별 수층별 출현경향을 보면, 여름철에는 표층에서 10종 2,397미, 중증에서 17종 895미였으며, 가을철에는 표층에서 7종 23미, 중층에서 26종 214미가 채집되어 표층보다. 중층에서 종이 다양한 경향이 있으며 특히 가을철의 중층은 가장 다양한 종조성을 나타내었다. 4. 계절별 우점종으로서는, 여름철에는 E. japonica, Gobiidae sp., T. lepturus 순으로 많이 출현하였으며, 가을철에는 Diaphus sp., E. japonica, Bothus sp., Ophichthidae sp. 순으로 나타났다. 5. 우점종의 계절별, 수층별 체장조성을 보면 E. japonica, Diaphus sp.는 여름철과 가을철에 걸쳐 계속 출현하였으며 계절별로는 뚜렷한 체장범위의 차이는 없으나 대개 표층에서보다 중층에서 조금 큰 체장범위의 개체들이 출현하는 경향을 나타내었다. 6. E. japonica는 비교적 넓은 수온, 염분범위에서 출현하였으며, 여름철 표층에서 수온 $20{\sim}24^{\circ}C$, 염분농도 $31{\sim}33\%0$ 범위에서 가장 많이 출현하였고, 가을철 중층에서는 큰 japonica, Diaphus sp., Bothus sp., Ophichthidae sp.가 모두 $18{\sim}23^{\circ}C$의 수온범위와 $32.5{\sim}34.3\%0$의 염분농도범위에서 출현하고 있었으나 그중 Ophichthidae sp.가 가장 고온, 고염 해역에서 분포하고 있었다.

  • PDF

항만과 수로의 제한속력 개선방안에 관한 기초 연구 (A Fundamental Study on the Improvements of Speed Limit at the Ports and Fairways in Korea)

  • 김득봉;윤병원;정재용;박진수;박영수
    • 해양환경안전학회지
    • /
    • 제18권5호
    • /
    • pp.423-430
    • /
    • 2012
  • 해상에서 제한속력은 항만 정온도(Calmness) 유지와 원활한 교통흐름 유도, 해양사고 방지에 목적이 있다. 우리나라는 현재 19개 항만에서 제한속력을 지정하여 사용 중에 있으나, 제한속력 적절성과 설정 기준에 대하여 문제가 제기되고 있다. 본 연구는 현재 시행중인 제한속력에 대한 검토와 제한속력 설정 기준과 표준 모델 개발의 필요성을 확인하기 위한 기초 연구로서, 우리나라 항만과 접근수로에 대한 제한속력과 선박 통항 실태를 조사 분석하였다. 조사 분석 결과 전체 평균 48 %의 위반율을 보이고 있었으며 여객선과 5.000톤 이상의 중 대형 선박에서 위반율이 높았다. 또한 평균속력이 제한속력 보다 높은 지역이 있었으며 선박간의 속력 편차도 4.2-5.2노트로 조사되었다. 평균속력과 속력 편차가 높은 항만일수록 해양사고율도 높았다. 따라서 선박 통항속력 관리에 대한 제도적 검토와 개선이 필요한 실정이다.

Study on the procedure to obtain an attainable speed in pack ice

  • Kim, Hyun Soo;Jeong, Seong-Yeob;Woo, Sun-Hong;Han, Donghwa
    • International Journal of Naval Architecture and Ocean Engineering
    • /
    • 제10권4호
    • /
    • pp.491-498
    • /
    • 2018
  • The cost evaluation for voyage route planning in an ice-covered sea is one of the major topics among ship owners. Information of the ice properties, such as ice type, concentration of ice, ice thickness, strength of ice, and speed-power relation under ice conditions are important for determining the optimal route in ice and low operational cost perspective. To determine achievable speed at any designated pack ice condition, a model test of resistance, self-propulsion, and overload test in ice and ice-free water were carried out in a KRISO ice tank and towing tank. The available net thrust for ice and an estimation of the ice resistance under any pack ice condition were also performed by I-RES. The in-house code called 'I-RES', which is an ice resistance estimation tool that applies an empirical formula, was modified for the pack ice module in this study. Careful observations of underwater videos of the ice model test made it possible to understand the physical phenomena of underneath of the hull bottom surface and determine the coverage of buoyancy. The clearing resistance of ice can be calculated by subtracting the buoyance and open water resistance form the pre-sawn ice resistance. The model test results in pack ice were compared with the calculation results to obtain a correlation factor among the pack ice resistance, ice concentration, and ship speed. The resulting correlation factors were applied to the calculation results to determine the pack ice resistance under any pack ice condition. The pack ice resistance under the arbitrary pack ice condition could be estimated because software I-RES could control all the ice properties. The available net thrust in ice, which is the over thrust that overcomes the pack ice resistance, will change the speed of a ship according to the bollard pull test results and thruster characteristics (engine & propulsion combination). The attainable speed at a certain ice concentration of pack ice was determined using the interpolation method. This paper reports a procedure to determine the attainable speed in pack ice and the sample calculation using the Araon vessel was performed to confirm the entire process. A more detailed description of the determination of the attainable speed is described. The attainable speed in 1.0 m, 90% pack ice and 540 kPa strength was 13.3 knots.

어군탐지기에 의한 어군의 분포와 생태계측에 관한 연구 (Hydroacoustic Investigation on the Distribution and Migration Behavior of Fish)

  • 이대재
    • 수산해양기술연구
    • /
    • 제28권4호
    • /
    • pp.337-346
    • /
    • 1992
  • 어군탐지기를 이용하여 어군의 분포와 그 행동생태를 계측하기 위한 연구의 일환으로 어군의 연직적인 일주회유이동 및 초음파산란강도의 변동특성을 검토하고, 또한 수온의 연직구조와 어군의 연직분포특성과의 관계, 선박의 항주상태에 따른 어군의 행동반응 등을 현장실험을 통하여 검토, 고찰한 결과를 요약하면 다음과 같다. (1) 어군의 공간분포특성은 수온의 연직구조와 밀접한 관계가 있음을 알 수 있었다. (2) 동중국해 중앙부에서 일출 직전까지 수온약층 바로 아래쪽에 군집하고 있던 칼오징어와 전갱이 어군이 일출과 더불어 해저를 향해 급속히 하강하는 일주회유이동이 관찰되었고, 그 하강속도는 0.24m/min이었다. (3) 수온약층이 탁월했던 제주도 서방해역과 대만 북부해역을 대상으로 어군의 연직분포특성과 수온의 연직구조와를 상호 비교 분석한 결과, 표층과 저층의 수온차가 크고, 또 중층에 뚜렷한 수온약층이 형성되어 있는 경우, 전갱이와 칼오징어군은 야간에 수온약층의 바로 아래쪽에 농밀하게 군집하는 특성을 나타내고, 또 표층과 저층의 수온차가 적은 경우에 있어서는 표층까지 완전히 부상하여 군집하는 경향을 나타내었다. (4) 선박을 정선시킬 때, 선저 직하에 분포하는 어족생물이 급히 연직적으로 하향 이동하는 도피행동을 나타내었다. 그러나, 그 후 시간이 경과함에 따라서 다시 원래의 유영층으로 상향이동하는 행동패턴을 나타내었다. 한편, 수온약층을 경계로 하여 상층과 하층에 분포하는 어족생물의 행동패턴에도 차이가 있었는데, 수온약층 아래쪽에 있어서는 어군이 현저한 도피행동을 나타내었지만, 그 위쪽에 있어서는 그러한 징후가 관찰되지 않았다. 이와 같은 현상은 수온약층 아래쪽에는 유영성이 강한 어족생물이, 그 위쪽에는 유영성이 약한 어족생물이 군집하고 있었기 때문이라고 판단된다. 당시 이 해역에서 행한 저층 트롤의 주요 어획물은 물메기, 살오징어, 삼치 등이었다.

  • PDF

IRAS 15099-5856: Remarkable Mid-Infrared Source with Prominent Crystalline Silicate Emission

  • 구본철;;서경원;문대식;;;;;김현정;정웅섭;;임명신;이호규;이재준
    • 천문학회보
    • /
    • 제35권1호
    • /
    • pp.57-57
    • /
    • 2010
  • We report the discovery of a bright mid-infrared (MIR) source with prominent crystalline silicate emission using the space telescope AKARI and Spitzer. This source, IRAS 15099-5856, has a spectacular morphology with a bright central compact source (CCS) surrounded by knots, spurs, and several extended (~4') arc-like filaments. The source is seen only in infrared at ${\geq}10{\mu}m$. The Spitzer MIR spectrum of the CCS shows prominent emission features from Mg-rich crystalline silicates and strong [Ne II] 12.88 ${\mu}m$ and several other faint ionic lines. We model the MIR spectrum as thermal emission from several independent dust components and compare their properties to those of the Herbig Be star HD 100546 which shows very similar MIR spectrum. Our molecular line observations reveal two molecular clouds around the source, but no associated dense molecular cores. We discuss two possible origins for IRAS 15099-5856; a deeply embedded massive young stellar object on the other side of the Galaxy and a disrupted, protoplanetary disk being photoevaporated by the UV radiation from the nearby O star Muzzio 10.

  • PDF

Shoes from Pinet to the Present

  • June, Swann
    • 한국복식학회:학술대회논문집
    • /
    • 한국복식학회 2001년도 19th International Costume Association Congress
    • /
    • pp.11-13
    • /
    • 2001
  • For those unfamiliar with the shoe world, Pinet (1817-1897) was a contemporary of Worth, the great Parisian couturier. So I look at the glamour shoes and the world of haute couture, and indeed the development of the named designer. That is a concept we are all familiar with now. So it is not easy to comprehend the lack of names for the exquisite work before 1850. Straightway I have to say that the number of noted shoe designers is far fewer than famous dress designers, but I will introduce you to some of them, against the background of contemporary shoe fashions. Franc;ois Pinet was born in the provinces (probably Touraine) in 1817, two years after the end of the Napoleonic Wars. His father, an ex-soldier, settled to shoemaking, a comparatively clean and quiet trade. It had a tradition of literacy, interest in politics, and was known as the gentle craft, which attracted intelligent people. We should presume father would be helped by the family. It was usual for a child to begin by the age of 5-6, tying knots, sweeping up, running errands and gradually learning the job. His mother died 1827, and father 1830 when he was 13, and at the time when exports of French shoes were flooding world markets. He went to live with a master shoemaker, was not well treated, and three years later set out on the tour-de- France. He worked with masters in Tours and Nantes, where he was received as Compagnon Cordonnier Bottier du Devoir as Tourangeau-Ia rose dAmour (a name to prove most appropriate). He went on to Bordeaux, where at 19 he became president of the local branch. In 1841 he went to Paris, and in 1848, revolution year, as delegate for his corporation, he managed to persuade them not to go on strike. By now the shoemakers either ran or worked for huge warehouses, and boots had replaced shoes as the main fashion. In 1855 Pinet at the age of 38 set up his own factory, as the first machines (for sewing just the uppers) were appearing. In 1863 he moved to new ateliers and shop at Rue ParadisPoissoniere 44, employing 120 people on the premises and 700 outworkers. The English Womans Domestic Magazine in 1867 records changes in the boots: the soles are now wider, so that it is no longer necessary to walk on the uppers. There is interest in eastern Europe, the Polonaise boots with rosette of cord and tassels and Bottines Hongroises withtwo rows of buttons, much ornamented. It comments on short dresses, and recommends that the chaussure should correspond to the rest of the toilet. This could already be seen in Pinets boots: tassels and superb flower embroidery on the higher bootleg, which he showed in the Paris Exposition that year. I think his more slender and elegant Pinet heel was also patented then or 1868. I found little evidence for colour-matching: an English fashion plate of 1860 shows emerald green boots with a violetcoloured dress.

  • PDF