• Journal of Conservation Science
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• v.25 no.1
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• pp.1-16
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• 2009

Jeollabuk-do is bounded by the sea, and Mahan Baekje culture have been established around a wide plain. Also, in southeastern, it was closed by Gaya kingdom where iron culture was prosperous at that time, a variety of the handles of swords with round pommel is excavated at present. The handles of swords with round pommel is the best amount of excavated objects among the swords with round pommel and producted object for the time. It supposes them to become the foundation of making the decorated swords with round pommel. But, the handles of swords with round pommel that don't have a pattern in handle is indifferent to study because the production method is simple in spite of that the value of archaeological data is sufficient. Therefore, in this study, it examined changed production techniques with the change of times concerning the handles of swords with round pommel of Mahan Baekje Gaya period(before 6C) excavated from Jeollabukdo through using X-rays in order to clarify a variety of production techniques of the handles of swords with round pommel correctly in accordance with a period of production and excavated place. As a result, identified production techniques using X-rays of the handles of swords with round pommel excavated around remains of Mahan Baekje Gaya period shows that production progress improved in order of all-in-one shape, hammer welding shape of the handle of round pommel, and two in body formation in accordance with age. Especially, in two in body shape, it products the handle of round pommel separately, after that it welds the handle of swords and then links the sword blade like a riveting or bottleneck and so on. Despite of improved hammer welding technique, the reason why it didn't utilize is it regards as inlay or gilt will be damaged. And it is judged by using riveting or bottleneck. Also, it appears to techniques of metal craft such as decoration of the handle, decoration of point of sword, inlay, and silver-plating in the period of appearing two in body shape. As clarifying correctly, it provides fundamental database of scientific research about a study of production techniques of handle of swords with round pommel.

• Journal of Ocean Engineering and Technology
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• v.27 no.3
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• pp.67-72
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• 2013

In this study, numerical analyses that considered the dynamic interaction effects between the flow and a turbine were carried out to investigate the power output performance of an H-type Darrieus turbine rotor, which is one of the representative lifting-type vertical-axis tidal-current turbines. For this purpose, a commercial CFD code, Star-CCM+, was utilized for an example three-bladed turbine with a rotor diameter of 3.5 m, a solidity of 0.13, and the blade shape of an NACA0020 airfoil, and the optimal tip speed ratio (TSR) and corresponding maximum power coefficient were evaluated through exhaustive simulations with different sets of flow speed and external torque conditions. The optimal TSR and maximum power coefficient were found to be approximately 1.84 and 48%, respectively. The torque and angular velocity pulsations were also investigated, and it was found that the pulsation ratios for the torque and angular velocity were gradually increased and decreased with an increase in TSR, respectively.

• International Journal of Highway Engineering
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• v.18 no.6
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• pp.41-50
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• 2016

OBJECTIVES : In this study, microstructural components of crumb rubber modified asphalt (CRMA) binder were investigated using environmental scanning electron microscope (ESEM). To clearly understand the elemental composition of the CRMA binder, energy dispersive X-ray spectroscopy (EDX) was employed on the ESEM samples. METHODS : CRMA binders were produced using open blade mixers at $177^{\circ}C$ for 30 min. The binders were artificially aged through a series of accelerated aging processes. Sample preparation was done by making a mold shape on the glass slide. Thereafter, the morphology of the CRMA binder was observed using the ESEM coupled with the EDX. RESULTS : The images captured from the ESEM indicate that the unaged CRMA binder appears to have a single-phase continuous nonuniform structure after the addition of crumb rubber particles, whereas the artificially aged CRMA binder was observed to have two different phases. ESEM coupled with EDX shows detailed internal structure of the modified binders compared to other technologies (i.e., optical microscopy, atomic force microscopy, and conventional scanning electron microscope). CONCLUSIONS : The captured images resemble the internal structures such as the viscous properties of the unaged CRMA binder and the interaction between the rubber particles and the base binder at aged condition. ESEM is a powerful instrument and with the introduction of EDX, it provided more details of the network microstructure of the asphalt binder. ESEM coupled with EDX is recommended for use in future investigation of microstructure of asphalt binders.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.56 no.3
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• pp.223-229
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• 2020

We analyzed the cutting mechanism of laver harvesting machine in the sea area near Gooam Port in Goheung, Jeollanam-do, and investigated the change and efficiency of laver collecting operation in the working ship. The laver working ship slides uniformly from the bow to the upper part of the laver collecting machine on the deck and cuts the wet laver attached to the bottom of the net at the blade of the havesting machine. The laver farming net, which was loaded with laver turrets on the deck by gravity and collected primitives, consisted of a ship structure that led to the stern side and into the sea. The working ship operation is in harvesting process while driving in a S-shape that is separated by one space to efficiently collect the laver net. During laver working ship operation, the speed was 0.51 m/s in the access stage, 0.56 m/s in the havesting stage, and 0.52 m/s in the exit stage. Considering the cutting edge life and production efficiency of the laver harvesting machine, it is appropriate to harvest 1.15 to 1.26 kg/rpm by operating at a rotational speed of about 700 to 800 rpm rather than forcibly harvesting the product at high speed. On the deck of the working ship, 959.7 kg of starboard and 1048.7 kg of center were 964.7 kg of port side. Based on the starboard, 9.3% of the central part and 0.5% of the port side appeared. The reason for this was due to the difference in harvest time according to the turning direction of the working ship.

• IE interfaces
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• v.21 no.4
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• pp.411-417
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• 2008

An impeller is a type of high-speed rotor that is used to compress or transfer fluid under high-speed and pressure at high temperatures. The impeller is composed of an axial hub and several blades attached along the hub. The weight and shape of an impeller must be balanced, because their imbalances can cause noise and vibration, which can lead to the breakage of the impeller blades during operation. Thus, the hub and blades of an impeller are commonly machined in a 5-axis NC machine to obtain qualified surfaces. The impeller machining strategy or process plan can not be easily obtained due to the complex, overlapped and twisted shapes of impeller blades. Skillful machining process planners may generate appropriate machining strategies based on their experiences and floor data. However, in practice most shop floor data for the impeller machining is not well-structured such that it does not effectively provide a process planner with information for machining strategies and/or process plans. This paper reports the development of a case-based machining strategy support system (CBMS) that employs case-based reasoning to obtain the machining strategy of an impeller by using the existing machining strategies of the shop floor. The CBMS generates impeller machining strategies through a stepwise reasoning process considering the similarity features between the blade shapes and machining regions. A case study is provided to demonstrate that CBMS can generate useful machining strategies facilitating process planners. The developed system can simulate the tool paths of impeller machining and runs on the web.

• Journal of Biosystems Engineering
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• v.36 no.6
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• pp.453-460
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• 2011

This study was carried out to test a red pepper tedding factors which is needed for design and development of an auto-tedding machine and a performance. According to this test, the results can be summarized as follows: The results of the tedding factors test according to shape of rotary blade, which is the 0.4 to 0.5 mm brush type, was found to be the most appropriate. As a result of tedding ratio which includes brush diameters, driving velocities and rotation velocities, there was generally no significance difference, but the red pepper tedding efficiency was found to be 39.7%. The moisture drying rate of red pepper was found to be 0.9 %w.b./h in prototype auto-tedding machine and 0.4 %w.b./h in traditional practice. The drying time was found to be 3 days in prototype auto-tedding machine and the traditional practice was 6 days. The average variable coefficient of the red pepper moisture content was found to be 16.8% in prototype auto-tedding machine in comparing with the traditional practice of 35.0%. This test showed a difference around two times, and this difference was evaluated to be the reason for irregular drying and different drying times.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.8
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• pp.110-115
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• 2009

Recently, there has been a growing global interest in environmental conservation, and the field of electric power equipment has been working to become more environment-friendly. Accordingly, the low noise cooling fan of power transformers was developed through the improvement of blade shape. These are expected to apply to existing power transformers and low noise transformers. It is essential for low noise fan to possess good cooling performance as well as low audible noises. But, there was not analysis on the audible noise level and the cooling performance for low noise cooling fans until present. In this paper, we measure the audible noise level and the flow rate of low noise cooling fans to inspect the performance, Also, we confirmed that the low noise cooling fan is available to apply to power transformers through temperature rise tests of power transformers.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.9
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• pp.843-850
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• 2010

This In this paper, we describe the performance characteristics of a turbo blower as a function of the shape of the volute casing: expansion diameter and width of the volute casing. The turbo blower considered in the present study is mainly used in a refuse collection system. The flow characteristics inside the turbo blower were analyzed by a three-dimensional Navier-Stokes solver and compared with experimental results. The distributions of pressure and efficiency obtained by numerical simulation were in good agreement with those determined experimentally. Throughout the numerical simulation of the turbo blower, the blower performance was enhanced by decreasing the local losses in the blade passage and the outlet flow. The efficiency and pressure for the design flow condition were enhanced by about 3% and 2%, respectively, compared to the efficiency and pressure of the reference blower. Detailed flow analysis was performed using the results of the numerical simulation

• Korean Journal of Plant Taxonomy
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• v.44 no.4
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• pp.233-237
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• 2014

A new taxon, Hymenophyllum wrightii f. serratum C.S. Lee & K. Lee (Hymenophyllaceae), forma nov. was collected and described from forests in Mt. Halla, Jeju-do, Korea. This taxon, H. wrightii f. serratum C.S. Lee & K. Lee (vernacular name: 'Gu-reum-cheo-nyeo-i-kki') was distinguished from H. wrightii f. wrightii by having smaller leaves, broader basal part of leaf blade, broad-ovate laminae, larger sori and serrate margins of lips of involucres. The new taxon's name is based on serrate margin shape of the lips. A Korean name, 'Gu-reum-cheo-nyeo-i-kki', was newly given based on its habitat. Descriptions and its photograph in the habitat are provided along with a key to the species of Hymenophyllum from Korea.

• Korean Journal of Plant Taxonomy
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• v.43 no.4
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• pp.263-266
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• 2013

Jasminum attenuatum Roxb. ex G. Don, a species of Oleaceae, was recently found in Kon Ka Kinh National Park of Vietnam that represents a new record to the flora of the country. The plant can be differentiated from its allied species J. latipetalum C.B. Clarke and J. simplicifolium subsp. funale (Decne) Kiew by the shape of its leaf blade, in having 5-20 flowered inflorescence, linear bracts, and obconic and glabrous calyx with shorter lobes. The present study provides the species description, illustrations, micrographs by scanning electron microscope of the pollen grains, and important taxonomic notes. Furthermore, a comparison of the diagnostic characters between this species and the above mentioned related species is made.