• Journal of The Geomorphological Association of Korea
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• v.20 no.3
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• pp.27-39
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• 2013

This study grasped long-term changing tendency of shoreline during lately about 30 years in five region of South East coast, and analyzed long-term changing tendency of East coast shoreline and the factors that synthesized studies of Central and South East coast. As a result of calculating of shoreline variations using DSAS, each shoreline of Mangyangjeong and Josa region regressed mean 28.9m and 6.4m, but each shoreline of Goraebul, Daejin and Bonggil region progressed mean 25.0m, 10.6m and 18.8m. Synthesizing changing tendency of East coast shoreline, 1) progressive and regressive zones of shoreline in all regions seem to repeat. 2) looking at shoreline of south zone adjacent to lately constructed or extended breakwater progressed, because it is thought due to effect of a longshore current flowing north. 3) zones using beach relatively tends to regress shorelines. 4) progress and regress of shoreline in zones including estuary of stream are various features as change of deposit supply from a upstream region.

• Journal of Electrical Engineering and Technology
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• v.12 no.1
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• pp.478-485
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• 2017

Urban DC railways have played an important role in urban transportation, and railway operation and energy management have been emphasized to be important to achieve maximum efficiency from existing infrastructure. Fast, accurate DC railway power flow analysis is required to operate a DC railway efficiently, and this paper proposes a novel methodology to analyze the DC railway power network by implementing the participation factor (PF). The PF concept consists of a correlation between the vehicle and the substation, as explained using zones based on the position of the vehicles running on the route. Then, the DC railway powerflow is calculated using the PF concept. Finally, the usability of the proposed method was validated via case studies with actual railway operation data, and we discuss some of the advantages of the suggested methodology.

• Geomechanics and Engineering
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• v.18 no.2
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• pp.111-119
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• 2019

Due to certain geological characteristics (high thickness, rocky properties), some underground coal mines require the use of explosives. This paper explores the effects of fragmentation of different decks detonated simultaneously in a single borehole with the use of numerical analysis. ANSYS/LS-DYNA code was used for the implementation of the models. The models include an erosion criterion to simulate the cracks generated by the explosion. As expected, the near-borehole area was damaged by compression stresses, while far zones and the free surface of the boundary were subjected to tensile damage. With the increase of the number of decks in the borehole, different changes in the fracture pattern were observed, and the superposition effects of the stress wave became evident, affecting the fragmentation results. The superposition effect is more evident in close distances to the borehole, and its effect attenuates when the distance to the borehole increase.

• IE interfaces
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• v.15 no.1
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• pp.1-9
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• 2002

Tandem AGV system is obtained by partitioning all workstations into multiple zones assigning a single vehicle to each zone. In this paper, we propose an analytical model to design a tandem AGV system with multi-load AGVs. Using simulation, the performance of the proposed model is shown by comparing a conventional multi-load AGV system.

• Journal of Mechanical Science and Technology
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• v.19 no.12
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• pp.2270-2280
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• 2005

An experimental study is performed for turbulent swirling flow behind a circular cylinder using 2-D PIV technique. The Reynolds number investigated are 10,000, 15,000, 20,000 and 25,000. The mean velocity vector, time mean axial velocity, turbulence intensity, kinetic energy and Reynolds shear stress behind the cylinder are measured before and behind the round cylinder along the test tube. A comparison is included with non swirl flow behind a circular and square cylinder. The recirculation zones are showed asymmetric profiles.

• Honam Mathematical Journal
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• v.46 no.2
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• pp.209-223
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• 2024

In this paper, we investigate the spatial quaternionic expressions of the ruled surfaces whose base curves are formed by the Smarandache curve. Moreover, we formulate the striction curves and dralls of these surfaces. If the quaternionic Smarandache ruled surfaces are closed, the pitches and angle of pitches are interpreted. Finally, we calculate the integral invariants of these surfaces using quaternionic formulas.

• Korean Journal of Ecology and Environment
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• v.41 no.4
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• pp.554-562
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• 2008

To evaluate the limitation for epiphytic and planktonic algal growth, acid extractable inorganic phosphorus (AP), implying the luxury uptake phosphorus, was measured in five reed zones of Lake Biwa. The AP in epiphytic substances was 0.7 to 1.4 mg P surface stem $m^{-2}$ in summer and 1.2 to 2.8 mg P $m^{-2}$ in winter. On the other hand, the amount in planktonic substances was 1.4 to 5.7 mg P m -3 and 0.8 to 5.4 mg P $m^{-3}$ in both seasons. Contribution of AP in the epiphytic and planktonic phosphorus was 23 to 31% and 8 to 27% in summer, and 17 to 22% and 9 to 17% in winter. It suggests that in summer both epiphytic and planktonic algae had been luxuriously taken up phosphate into cells. The weight ratios of C : N : P were averaged 79 : 20 : 1 for the epiphytic substances and 81 : 12 : 1 for the particulate substances. On the other hand, the ratios without the luxurious phosphorus were 93 : 24 : 1 and 103 : 15 : 1, showing much higher values than the Redfield ratio. High ratio in the epiphytic substances indicates that the phosphorus is the limiting parameter, rather than nitrogen, regulating the growth of epiphytic algal populations.

• Geomechanics and Engineering
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• v.11 no.2
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• pp.197-209
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• 2016

Clayey rock has large clay mineral content. When in contact with water, this expands considerably and may present a significant hazard to the stability of the rock in geotechnical engineering applications. This is particularly important in the present work, which focused on mitigating some unwelcomed properties of clayey rock. Changes in its physical properties were simulated by subjecting the rock to a low voltage direct current (DC) using copper, steel and aluminum electrodes. The modified mechanism of the coupled electrical and chemical fields acting on the clayey rock was analyzed. It was concluded that the essence of clayey rock electrochemical modification is the electrokinetic effect of the DC field, together with the coupled hydraulic and electrical potential gradients in fine-grained clayey rock, including ion migration, electrophoresis and electro-osmosis. The aluminum cathodes were corroded and generated gibbsite at the anode; the steel and copper cathodes showed no obvious change. The electrical resistivity and uniaxial compressive strength (UCS) of the modified specimens from the anode, intermediate and cathode zones tended to decrease. Samples taken from these zones showed a positive correlation between electric resistivity and UCS.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2018.05a
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• pp.36-37
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• 2018

This study is about the development of emergency response guidance according to the fire safety index in the fire safety module, which is one of the on-board remote monitoring system. In this paper divided the zones based on the location of the fire sensor for passenger ship which is one of the service passenger ships and developed on the emergency response guidance by the identified zones.

• School Mathematics
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• v.5 no.3
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• pp.297-314
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• 2003

Mathematics students must appropriate their mathematical knowledge which has the definition and theorem of mathematics, algorithm, reasonable thought, heuristic, and mathematics language, and so on. That is, students should construct, use, and apply their own knowledge during learning. Appropriation of mathematical knowledge is practicable when mathematics language is in charge of many functions that Vygotsky cited. To reach the potential development level with mathematics language, students need the zones that they interact themselves and peers, as well as teacher. On that ground, this study presented the interactional zones of IZPD, ZPP, and ZAD, and modeled mathematics learning. By the case of 2 students, we found that ZPP and ZAD were necessary and important.