• Title/Summary/Keyword: Knots

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

  • Kim, Juyeol;Choi, Junho;Oh, Jungkeun
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.23 no.5
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    • pp.566-573
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    • 2017
  • The chine of high speed vessels does not only play a role in changing position when planing but also helps balancing the hull. It also has a great influence on resistance performance. However, designing a chine requires a lot of experience because it is influenced by various factors such as displacement, transom shape, draft and width. Such a design is not based on an empirical formula, but the purpose of this study is to provide basic guidelines regarding the shape of chine through calculation. This design was developed using Yacht-one, a commercial design program, and analysis was performed using Star-CCM+, also a commercial analysis program. Analysis of the hull selected in this study was carried out by Dynamic Fluid Body Interaction (DFBI) method. Analysis of the chine was carried out at chine angles of 15, 16, 17, and 19degrees, at a speed of 30knots. The result indicated that the highest trim occurred at 16 degrees among the four chine angles considered, and the highest heave occurred at 15degree. In terms of resistance performance, minimum resistance was observed at 16 degrees. Consequently, for minimum ship resistance, it is necessary to complete calculations in accordance with the chine angles, ${\pm}2$ degrees from the initial chine angle, which should be carried out a the design stage.

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

  • Seebai, T.;Sundaravadivelu, R.
    • Ocean Systems Engineering
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    • v.1 no.4
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    • pp.285-296
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    • 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.

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 (연안어장의 부유성 폐기물 분포와 조성에 관한 연구 II. 남해 중부해역의 폐기물 수송)

  • KIM Jong-Hwa
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.32 no.3
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    • pp.338-344
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    • 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.

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

  • KIM Yong Uk
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.17 no.3
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    • pp.230-243
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    • 1984
  • Larvae of fishes were collected at 26 stations in the Korea Strait, by horizontal towings using the fish larval net (Norpac) in the surface layer and by oblique towings using Isaac-Kid mid-water trawl in the mid-water layer in summer (July) and in autumn (November), in 1983. The towing speed was 1.5 knots. Of the larval fish examined, 3,529 individuals were identified to generic and specific levels. They belong to 27 families, consisting of 38 species in 37 genera. Unidentified were 114 specimens. The most abundant species was Engraulis japonica which occupied $88.5\%$ of the whole 3,645 individuals. Diaphus sp. took the second place with 50 individuals ($l.3\%$). Seasonally abundant species were in the order of Engraulis japonica, a Gobid, Trichiurus lepturus, and Diaphus sp. in summer, and in the order of Diaphus sp., Engraxlis japonica, Bothus sp., and a Ophichthid in autumn. Of these larvae, Engraulis japonica and Diaphus sp. continuously appeared from summer to Autumn. Champsodon sp., Diaphus sp. and Synagrops philippinensis were unrecorded species in Korea.

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

  • Kim, Deug-Bong;Yun, Byeong-Won;Jeong, Jae-Yong;Park, Jin-Soo;Park, Young-Soo
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.18 no.5
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    • pp.423-430
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    • 2012
  • The purpose of Speed limit at sea is to keep harbor calmness, to maintain efficient traffic flow and to prevent maritime accidents. The Korean Regional Maritime Affairs and Port Office(KRMAPO) specified and enforced the ship's speed limits at the 19 harbors around the Korean coasts. However, problems have been raised to the adequacy of speed limits. This paper made a research on the speed limit set standards, analyzed vessel traffic survey and the dilemma on the specified speed limits imposed by KRMAPO. The result of this study has shown an overall average of 48 % violation rate on speed limit with passenger ships and large vessels of more than 5,000 tons having higher violation rate. Average speed was higher than the limit speed in some harbors and deviation of 4.2 to 5.2 knots was investigated. Further, harbors having higher average speed also have higher deviation accident incidence. Therefore, this paper had confirmed that there is a need for institutional review and improvement of Korea's port and fairways speed traffic management.

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
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    • v.10 no.4
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    • pp.491-498
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    • 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.

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

  • 이대재
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.28 no.4
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    • pp.337-346
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    • 1992
  • Hydroacoustic surveys were conducted in the East China Sea, in the summers of 1990-1991 to investigate the distribution and migration behavior of fish, such as the diel changes in the distributions of fish, the thermoselection behavior of fish, and the fish reactions to a surveying vessel. The hydroacoustic observations were taken with a scientific echo sounder operating at 50kHz and a microcomputer-based echo processor. Fish samples were collected by bottom trawling and temperature was measured with a DBT system. The patterns of fish distributions were compared with the vertical profiles of water temperature. The results obtained can be summarized as follows: 1. The time series of hydroacoustic observations on the downward migration at dawn in the central region of East China Sea showed that the migration rate was 0.24 m/min. In this region, most of the fish collected by bottom trawling during the surveys were squid (Photologio edulis f. budo) and horse mackeral (Trachurus japonicus). 2. The hydroacoustic observations, which together associated with temperature data, indicated that squid and horse mackeral concentrated nocturally in a narrow vertical band of thermocline, particularly in summer when the survey region was strongly stratified. This result suggest that the nocturnal vertical distribution of these species evidently is controlled by temperature. 3. When the survey vessel, that is running at a speed of 11 knots, has suddenly stopped, the fish which concentrated beneath the transducer showed a strong avoidance reaction in the form of rapid downward migration. After a few minutes, the descending reaction disappeared and the fish slowly began the upward migration toward their original swimming positions. Trawl data suggest that the fish, which showed the avoidance reaction, was Liparis tessellatus.

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

  • Koo, Bon-Chul;McKee, Christopher F.;Suh, Kyung-Won;Moon, Dae-Sik;Burton, Michael, G.;Hiramatsu, Masaaki;Bessel, Michael S.;Onaka, Takashi;Kim, Hyun-Jeong;Jeong, Woong-Seob;Gaensler, Bryan;Im, Myung-Shin;Lee, Ho-Gyu;Lee, Jae-Joon;Tatematsu, Ken'ichi;Kohno, Kotaro;Ezawa, Ryohei;Ezawa, Hajime;Yun, Min-S.;Hughes, David H.
    • The Bulletin of The Korean Astronomical Society
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    • v.35 no.1
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    • pp.57-57
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    • 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.

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Shoes from Pinet to the Present

  • June, Swann
    • Proceedings of the Korea Society of Costume Conference
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    • 2001.08a
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    • pp.11-13
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    • 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.

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A Development of Necktie Design in Western Art (서양 예술작품에 나타난 넥타이의 역사적 고찰)

  • Lee Eui-Jung;Chung Se-Hui
    • Journal of the Korea Fashion and Costume Design Association
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    • v.8 no.1
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    • pp.81-96
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    • 2006
  • This study aimed to investigate the sociocultural phenomena which affected to clothing change in 1650-1900 and to examine the features of men's necktie in the western art. For this study, information about historic neckwear is obtained from the visual evidence of painted or engraved portraits, contemporary written sources. The covered area of this study was Europe mainly England and France. For this process, research steps were as follows : 1. Investigating the sociocultural phenomena which affect to clothing change through 1650-1900 and analysis of men's clothing and appearance. 2. Finding the changing characteristics of neckties including it's different types, shapes, knots, colors and materials and analyzing similarities and differences of neckties by the times. 3. Examining necktie as one of important and representative icons of male gender identity. The results of the study was as follows: 1. In 1660-1900, men's fashion was simplified in color and detail due to the influence of practical Puritanism and matured civil culture. And British men's fashion spreaded throughout whole European countries and get popularity. 2. In 1650-1720, there were band, cravat and steinkirk. And expecially cravatier, a expert custodian of cravats, was appeared in that period. In 1720-1800, there were stock, solitaire and cravat. In 1800-1850, neckwear were popularized and got various sizes and types up to shape and size of chemise collars. Black stock, scarf cravat and shawl cravat were popular and terms of 'necktie' were used for an certain neckcloth shape. And abundant literature for necktie were published thanks to the development of printing technology in that period. In 1851-1900, the leady-made neckties were spreaded and there were changes in shape, length, knot of necktie up to V-zone formed with shirt's collars and vest types. Neckwear was gradually evolving through four distinct styles, bow tie, scarf or neckerchief, Ascot and four-in-hand. 3. After the mid-l7th Century, as civil culture matured and splendid and extravagant colorful men's wear disappeared, British men's fashion spreaded throughout whole European countries and got popularity. The necktie become an essential ornamental accessory of men's fashion and one of important and representative icons of male gender identity.

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