• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.30 no.1
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• pp.13-24
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• 1994

Purse seiner detects a fish school navigating in full speed with the aid of fish finder, sonar, helicopter, etc., and casts a net quickly to enclose the fish school in purse seine net according to the movement of the fish school, wind, and current. At this moment, if the time of casting a net, direction, speed, and turning circle are net suitable, it is unavoidable to lose fish school founded with hard efforts and we only consume our efforts of casting and hauling the net. Therefore, in order to enclose the fish school to enhance the amount of fish for each casting, the author investigated the type of ships equipped with purse seiners and examined maneuvering tests so that we provide some basic information to figure out the ability of steerage correctly. The results obtained are summarized as follows: 1. Block coefficients of pelagic tuna purse seiners with gross tonnage between 500 and 1500 tons are recorded between 0.50 and 0.55 which are greater than those of off shore purse seiners recorded as between 0.44 and 0.54 and less than those of various cargo ships recorded as between 0.56 and 0.84. 2. L/B, L/D, B/D, B/T, and T/D of the class of gross tonnage between 75 and 130 tons are respectively 4.49, 11.00, 2.45, 2.85 and 0.86 as their average and those of the class of between 500 and 1500 tons are 4.89, 10.53, 2.15, 2.73 and 0.75 respectively, which are quite different from those of various cargo ships recorded as 6.0~7.5, 11.0~12.0, 1.6~2.0, 2.2~2.8 and 0.65~0.75 respectively. 3. Rudder area ratio of purse seiners of the class of between 75 and 130 tons is 1/24~1/31 and that of the clase of between 500 and 1500 tons is 1/36~1/42 which is greater than that of various cargo ships recorded as 1.45~1.75. 4. On speed-length ratio of purse seiners. 111 Dong-a has the biggest value 2.94 the class of 130 tons has 2.52 the class of between 75 and 100 tons has 2.30~2.35 and the class of between 500 and 1500 tons has 1.99~2.05. 5. Turning circle of stern trawlers Pusan 404 and Haelim 3 are measured as below according to rudder angles 5$^{\circ}$, 15$^{\circ}$, 25$^{\circ}$ and 35$^{\circ}$ respectively. Advances are 11.3~13.6, 6.0~7.1, 3.6~4.8 and 2.5~3.5 times of LPP respectively. Tactial diameters are 15.2~18.6, 6.9~8.0, 4.2~4.9 and 2.9~3.5 times of LPP. Purse seiner 111 Dong-a with rudder angle 35$^{\circ}$ has a good yaw with quick responsibility since its advance is 2.2~2.3 times of LPP and since its tactial diameter is 2.0~2.1 times of LPP. 6. In full ahead going of purse seiner 111 Dong-a, it takes about 2 minutes and 10.6 times of LPP from the reverse turning its engine into full astern to the ship speed 0. In its full astern going, it takes about 1 minute and 5.1 times of LPP from the reverse turning its engine into full ahead to the ship speed 0. In its full ahead going, it takes about 2 minutes and 50 seconds and 12.3 times of LPP from stopping its engine to the dead slow ahead speed 3.2 knots.

• Journal of the Geological Society of Korea
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• v.54 no.5
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• pp.489-499
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• 2018

A series of geological events such as the formation of the Antarctic continental ice sheets, the changes in ocean circulation and a mass extinction after the onset of Oligocene has been studied as major concerns by various researches. However, paleoclimatic and paleoceanographic changes during the most period of Oligocene since the Eocene-Oligocene transition (EOT) still remains unclear. Especially, although the late Oligocene warming (LOW) has been assessed as the largest period in the paleoceanographic changes, the detailed understanding on the changed components is very low. The purpose of this study is the reconstruction of the paleoceanographic history during the late Oligocene using core sediments from IODP Expedition 342 Site U1406 performed in J-Anomaly Ridge in North Atlantic. Because North Atlantic deep water (NADW) has flowed southward through the study area since the early Oligocene, this area has been considered to an important location for studies on the changes of NADW. The core sediment analyzed in this study were deposited from about 26.0 to 26.5 Ma as evidenced by both of onboard and shore-based paleomagnetic data, and this is corresponded to the earliest period of LOW. The sediment profile can be divided into three Units (Unit 1, 2 & 3) based on the changes in both of total number and test size of Oridorsalis umbonatus as well as grain size data of clastic sediments. Unit 2 represents largest values in these three data. Because the total number, test size of O. umbonatus and grain size can be proxy records on the oxygen concentration and circulation intensity of deep water, we interpreted that Unit 2 had been deposited during the period of relatively strengthened NADW. Previous Cibicidoides spp. stable isotope results from the low latitude region of the North Atlantic also support our interpretation that is the intensified formation of NADW during the identical period. In conclusion, our results present a new evidence for the previous ideas that the causes on LOW are directly related to the changes in NADW.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.29 no.3
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• pp.116-123
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• 2011

This study investigates the characteristics(form, material, structure, method of construction, vegetation) and model of lotus pond in Joseon Royal Tombs for conservation and restoration. The objects of study are the lotus pond of Namyangju Gwangreung, Hyoreung, Gimpo Jangreung and Sungreung that are well-preserved and the record is remaining. The form is two plane types, square shaped include an island and square shaped. The pond is 7.5~81m in width and 6.5~45m in length and the island is 8~16m in diameter. The depth of water is 0.5~1.2m and the cross section form is narrow bottom and wide top. The material of shore protection is soil in Hyoreung, Gimpo Jangreung and Sungreung. The bottom is mud in all sites. I think that the main material of the lotus pond in Joseon Royal Tombs is soil. The lotus pond is built by soil bank in the structure and method of construction. The water supply and drainage are worked through the culvert. There are many kinds of plants in the lotus pond today, however I think that the model of vegetation of lotus pond in Joseon Royal Tombs is lotus the inside, pine tree, fir tree and flowers the around and pine tree the inside of island in compared the present and the old literature. In comparison with the lotus pond in Joseon Royal Tombs and the lotus pond in the Joseon palace, the material is the biggest difference. The main material is soil in Royal Tombs but isodomic in Royal Palace. I think that the difference of material in between two causes the difference of structure and method of construction. The Royal Tombs is valuable in architecture, landscape and esthetics, this study investigated the characteristics and model of lotus pond in Joseon Royal Tombs. I think that this study serves as a momentum to find a traditional technique in Royal water space and offer the foundation to plan in the contemporary water space.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.26 no.1
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• pp.37-48
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• 2021

A new high speed rotation type-passive sampling device (HSR-PSD), which can rotate seawater at high speed and absorb easily and quickly the freely dissolved hydrophobic organic contaminants from seawater, was developed and then applied around the Korean Peninsula. Freely dissolved concentrations (Cfree) of polycyclic aromatic hydrocarbons (PAHs) were determined using the HSR-PSD with low density polyethylene (LDPE) sheets as a passive sampler. Furthermore, dissolved concentrations (Cdissolved) of PAHs in seawater were also obtained from high volume water sampling as a conventional method to account for actual bioavailability. When the LDPE sheets were rotated in the HSR-PSD at 900 rpm, PAHs with log KOW 3.4 ~ 5.2 were equilibrated between the LDPE and water in 5 hours. Although the high molecular weight PAHs with log KOW 5.6 ~ 6.8 was expected to be 2 to 30 days to reach the equilibrium, the Cfree of the PAHs at equilibrium could be corrected using performance reference compounds in 5 hours. Meanwhile, the total Cfree of PAHs were from 0.32 to 1.2 ng/L, which were higher than reported values in other oceans, but lower than in coastal water such as estuary, harbor, or shore. A bioavailability from the detected PAHs was highest at the sampling line near the dumping site of the Yellow Sea. Predicted residual concentrations in biota were relatively higher in offshore including the dumping site than in coastal regions.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.40 no.4
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• pp.32-48
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• 2022

This study analyzed the construction pattern and historical reality of Gwallamji Pond(觀纜池) in the rear garden of Changdeokgung Palace(昌德宮), which has been received as distorted information and has not received sufficient attention. The main topics consisted of the construction period and reorganization in the pond garden, changes in the installed wooden bridge, the existence of the berthing facility, and whether the plan shape was deformed. The main results of this study can be summarized as follows. First, the Gwallamji Pond was already completed before the Gapsin Coup, which occurred in the year of King Gojong. Since then, the Gwallamji Pond area, including the surrounding facilities, has been neglected for a while and was extensively renovated in the early 1900s. It is difficult to find a clear basis for the suspension and resumption of the Gwallamji Pond construction proposed in the previous discussion. Second, three types of wooden bridges with different shapes and structures were installed sequentially in the Gwallamji Pond. In particular, the second wooden bridge, which installed after the maintenance of the Gwallamji Pond, is judged to be the pontoon bridge depicted in Donggweoldohyeong(東闕圖形), and the railing of the bridge was decorated to symbolize the imperial family of the Korean Empire. The third wooden bridge, which appeared intensively in Japanese colonial era, was a Japanese-style bridge. Third, a berth facility for boarding and disembarking existed on the eastern shore of the Gwallamji Pond. The berth facility is also described in Donggweoldohyeong and it remained until the Japanese colonial period. However, as the maintenance work of the Gwallamji Pond was carried out several times after liberation, the berth facility was gradually damaged, and there are no traces left now. Fourth, The Gwallamji Pond was originally constructed in a planar shape of the Korean Peninsula similar to the present. It is necessary to reconsider the conventional theory that the Gwallamji Pond, made in the shape of a gored-shaped bottle, was renovated in the shape of the Korean Peninsula in Japanese colonial era. Even when the term Pandoji Pond(半島池) first appeared, there was no view that the Japanese intentionally modified the Gwallamji Pond.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.5
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• pp.479-487
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• 2023

Recently, the destructive power of typhoons is continuously increasing owing to global warming. In a situation where the installation of floating wind turbines is increasing worldwide, concerns about the huge loss and collapse of floating offshore wind turbines owing to strong typhoons are deepening. A new type of disconnectable mooring system must be developed for the safe operation of floating offshore wind turbines. A new submersible mooring pulley considered in this study is devised to more easily attach or detach the floating of shore wind turbine with mooring lines compared with other disconnectable mooring apparatuses. To investigate the structural safety of the initial design of submersible mooring pulley that can be applied to an 8MW-class floating type offshore wind turbine, scale-down structural models were developed using a 3-D printer and structural tests were performed on the models. For the structural tests of the scale-down models, tensile specimens of acrylonitrile butadiene styrene material that was used in the 3-D printing were prepared, and the material properties were evaluated by conducting the tensile tests. The finite element analysis (FEA) of submersible mooring pulley was performed by applying the material properties obtained from the tensile tests and the same load and boundary conditions as in the scale-down model structural tests. Through the FEA, the structural weak parts on the submersible mooring pulley were reviewed. The structural model tests were conducted considering the main load conditions of submersible mooring pulley, and the FEA and test results were compared for the locations that exceeded the maximum tensile stress of the material. The results of the FEA and structural model tests indicated that the connection structure of the body and the wheel was weak in operating conditions and that of the body and the chain stopper was weak in mooring conditions. The results of this study enabled to experimentally verify the structural safety of the initial design of submersible mooring pulley. The study results can be usefully used to improve the structural strength of submersible mooring pulley in a detailed design stage.

• Journal of Navigation and Port Research
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• v.46 no.1
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• pp.1-10
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• 2022

This study aims to investigate changes in the demand for ship officers in response to changes in the shipping industry environment in which Maritime Autonomous Surface Ships (MASS) emerge according to the application of the fourth industrial revolution technology to ships, and it looks into changes in the skill of ship officer. It also analyzes and proposes a plan for nurturing ship officers accordingly. As a result of the degree of recognition and AHP analysis, this study suggests that a new training system is required because the current training and education system may cover the job competencies of emergency response, caution and danger navigation, general sailing, cargo handling, seaworthiness maintenance, emergency response, and ship maintenance and management, but tasks such as remote control, monitoring diagnosis, device management capability, and big data analysis require competency for unmanned and shore-based control. By evaluating the importance of change factors in the duties of ship officers in Maritime Autonomous Surface Ships, this study provides information on ship officer educational institutions' response strategies for nurturing ship officers and prioritization of resource allocation, etc. The importance of these factors was compared and evaluated to suggest changes in the duties of ship officers and methods of nurturing ship officers according to the introduction of Maritime Autonomous Surface Ships. It is expected that the findings of this study will be meaningful as it systematically derives the duties and competency factors of ship officers of Maritime Autonomous Surface Ships from a practical point of view and analyzed the perception level of each relevant expert to diagnose expert-level responses to the introduction of Maritime Autonomous Surface Ships.

• The Journal of the Acoustical Society of Korea
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• v.28 no.4
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• pp.343-355
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• 2009

In order to restore the identity of sound environment and expand the sound culture of a region, the purpose of this study are to excavate the resources of soundscape and find out the plans for the preservation and promotion of soundscape resources peculiar to the region. For this purpose, this research is conducted through an interview survey of residents and an observation survey using listening walk in Hongdo, one of the southwesten island of Korea. The results of survey confirm that there are so many sounds to hear around Hongdo island, those are, natural sounds such as the song of the birds, the roar of the waves, the whistling sounds, the shriek of the seagulls, and the pebbles sounds washed away by the waves, and artificial sounds such as the steam-whistle signals, the ship's broadcasts, the voice of tourists, the sounds of church bells, lighthouse sirens etc. The results suggest that it is necessary to consider several ways for restoration of an unique soundscape in Hongdo island, those are, improvement for efficient management of a ship's broadcasts in public areas, removal of a ferry in Hongdo swimming beach, management of Dangsanje (a religious service), preservation of a lighthouse siren and a foghorn, restoration and improvement of underground stream, management and control of public fish market, restoration of brooklet, management of cooperative system for a fish market, restoration of PoongO-Gut (a ritual for a large harvest) and a skate festival, management of a Hongdo sports meeting, sound quality modification of a boat whistle, restoration of orientalia such as a funeral bier, ecosystem preservation activity of the shore and ocean, and promotion of amenity for fascination and vitality in a rural community. Also, a sound map is drawn up for many tourists so as to realize the importance of sound environment and identity of soundscape and to gain their experience at first hand in Hongdo island.

• Journal of the Korean Society of Marine Environment & Safety
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• v.30 no.1
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• pp.127-134
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• 2024

With the growth of offshore wind power generation market, the corresponding installation vessel market is also growing. It is anticipated that approximately 100 installation vessels will be required in the of shore wind power generation market by 2030. With a price range of 300 to 400 billion Korean won per vessel, this represents a high-value market compared to merchant vessels. Particularly, the demand for large installation vessels with a capacity of 11 MW or more is increasing. The rapid growth of the offshore wind power generation market in the Asia-Pacific region, centered around China, has led to several discussions on orders for operational installation vessels in this region. The seabed geology in the Asia-Pacific region is dominated by clay layers with low bearing capacity. Owing to these characteristics, during vessel operations, significant spudcan and leg penetration depths occur as the installation vessel rises and descends above the water surface. In this study, using penetration variables ranging from 3 to 21 m, the unique vibration period, structural safety of the legs, and conductivity safety index were assessed based on penetration depths. As the penetration depth increases, the natural vibration period and the moment length of the leg become shorter, increasing the margin of structural strength. It is safe against overturning moment at all angles of incidence, and the maximum value occurs at 270 degrees. The conditions reviewed through this study can be used as crucial data to determine the operation of the legs according to the penetration depth when developing operating procedures for WTIV in soft soil. In conclusion, accurately determining the safety of the leg structure according to the penetration depth is directly related to the safety of the WTIV.

• Korean Journal of Heritage: History & Science
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• v.37
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• pp.65-89
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• 2004

Up to now, the studies for a pond of ancient palace of Korea are mainly achieved in a landscape architectural field. In fact, we can't grasp the general aspects but we are only heard about the fragmentary ruins and remains by the people who are in charge of an archaeological excavation. In this thesis, therefore, I attempt to grasp the relational categories of the ponds of an ancient palace of Korea, and find out the ideological backgrounds of the ponds of a palace construction through classify them excavated so far. The ancient ponds of Korea are divided to the class of square ponds(I) and curved ponds(II) according a shapes of planes. The class of square ponds(I) are subdivided to the form IA of the class of square ponds and form IB of the class of square ponds by whether it has an island, artificial hill and ornamental stone or not. And the class of the curved ponds(II) are divided to the form IIC that is only composed of curves in shore and the form IID that is composed of curves and straight lines. According the size, it is divided to a small size that is below the maximal diameter, 20m, and a large size that is more than 45m, after all, the ponds of the ancient palaces are devided to IAa, IAb, IBa, II Ca, IICb, IIDa. The square ponds and the curved ponds are co-exist from the initial stage when a pond of a place was found in our country and are succeeded or changed after Silla unified the three Kingdoms. In other words, we can infer a continuity from the earlier stage from the fact that there is a flat figure ground mainly constituted by the ponds of a palace mixed up of a straight line and a curved line in United Silla Kingdom while it succeeds the ponds of a palace that has a square form of Goguryo in Balhai. Different from the successional relation of the flat figure grounds, in an aspect of the elements of the construction, the site of the arbor at the top of the island and the bridge facilities in a field of a palace those are not exist in three Kingdoms period are appeared in United Silla Kingdom. The point that this aspect is simultaneously appeared in a neighboring country, or Japan, allows us to infer that there may be some motivations cause the changes in a construction of the ponds of a palace of Korea, China and Japan from the latter half of the 7th century to the first half of the 8th century. The ideological backgrounds of the ponds of a palace construction are divided roughly into Taoism and Buddhism. We can recognize that the ponds of a palace made up of the islands, the artificial hills and the garden rocks reflect Taiosm, considering the records of the ponds a palace of Korea and China are all use the term, Taoism, or the concrete statement represents that the islands, the artificial hills and the garden rocks are used in the description of the ponds of a palace of Korea. Both two are, therefore, obviously differentiated from the ponds of a palace that doesn't include them. We can conclude that the ponds of a palace that doesn't include them are colored by Buddhism since they are overtly distinguished from the class of curved ponds that reflect Taoism at the same period and they are identical with the site of an ancient temples in an aspect of their type and construction.