• Transactions of Materials Processing
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• v.18 no.7
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• pp.531-537
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• 2009

The effect of blank holding force on thickness variation in simultaneous sheet forming with rectangular shape and circular has been demonstrated. Because has investigated an effect on formability of magnesium sheet, in this paper, the effect of punch radius on formability have been thinning, various crack phenomena and forming velocity. By simultaneously forming process with circular and rectangular shape, the data of simultaneously forming process with circular and rectangular shape will used to a part development such as notebook computer case, cell phone and bipolar plate of fuel cell.

• The KIPS Transactions:PartB
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• v.18B no.2
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• pp.73-82
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• 2011

There are a lot of people trying to solve the Traveling Salesman Problem (TSP) by using the Meta Heuristic Algorithms. TSP is an NP-Hard problem, and is used in testing search algorithms and optimization algorithms. Also TSP is one of the models of social problems. Many methods are proposed like Hybrid methods and Custom-built methods in Meta Heuristic. In this paper, we propose the S-MINE Algorithm to use the MINE Algorithm introduced in 2009 on the TSP.

• Structural Engineering and Mechanics
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• v.18 no.1
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• pp.79-90
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• 2004

A high precision shear deformable triangular element has been proposed for bending analysis of triangular plate. The element has twelve nodes at the three sides and four nodes inside the element. Initially the element has thirty-five degrees of freedom, which has been reduced to thirty by eliminating the degrees of freedom of the internal nodes through static condensation. Plates having different boundary conditions, side ratios (b/a) and thickness ratios (h/a = 0.001, 0.1 and 0.2) have been analyzed using the proposed shear locking free element. Concentrated and uniformly distributed transverse loads have been used for the analysis. The formulation is made based on first order shear deformation theory. For validation of the present element and formulation few results of thin triangular plate have been compared with the analytical solutions. Results for thick plate have been presented as new results.

• The KIPS Transactions:PartB
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• v.18B no.5
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• pp.291-294
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• 2011

Red tide is a temporary natural phenomenon to change sea color by harmful algal blooms, which finfish and shellfish die en masse. There have been many studies on red tide due to increasing of harmful algae damage of fisheries in Korea. Particularly, red tide damage can be minimized by means of prediction of red tide blooms. However, the most of red tide research in Korea has been focused only classification of red tide which it is not enough for predicting red tide blooms. In this paper, we proposed the red tide blooms prediction method using fuzzy reasoning.

• Journal of the Optical Society of Korea
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• v.18 no.6
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• pp.739-745
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• 2014

We have demonstrated a $Ti:LiNbO_3$ electro-optic electric-field sensor utilizing a $1{\times}2$ Y-fed balanced-bridge Mach-Zehnder interferometric (YBB-MZI) modulator, which uses a 3-dB directional coupler at the output and has two complementary output waveguides. A dc switching voltage of ~25 V and an extinction ratio of ~12.5 dB are observed at a wavelength of $1.3{\mu}m$. For a 20 dBm rf input power, the minimum detectable electric fields are ~8.21, 7.24, and ~13.3 V/m, corresponding to dynamic ranges of ~10, ~12, and ~7 dB at frequencies of 10, 30, and 50 MHz respectively. The sensors exhibit almost linear response for an applied electric-field intensity from 0.29 V/m to 29.8 V/m.

• JSTS:Journal of Semiconductor Technology and Science
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• v.13 no.3
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• pp.193-197
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• 2013

This paper presents a 5-bit true time delay circuit using a standard 0.18 ${\mu}m$ CMOS process for the broadband phased array antenna without the beam squint. The maximum time delay of ~106 ps with the delay step of ~3.3 ps is achieved at 5-20 GHz. The RMS group delay and amplitude errors are < 1 ps and <2 dB, respectively. The measured insertion loss is <27 dB and the input and output return losses are <12 dB at 5-15 GHz. The current consumption is nearly zero with 1.8 V supply. The chip size is $1.04{\times}0.85\;mm^2$ including pads.

• Transactions on Electrical and Electronic Materials
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• v.18 no.1
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• pp.16-20
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• 2017

A RF-MEMS (radio-frequency microelectromechanical-system) based DPDT (double pole double throw) switch for the Ku band has been designed and analyzed for this article. The switch topology is based on the FG-CPW (finite ground-coplanar waveguide) configuration of a microstrip-transmission line. An FEM-based multiphysics solver is used for the evaluation of the spring constant, stress distribution, and pull-in voltage regarding the requirements of the switch-beam unit. The electromagnetic performance of the switch is investigated for a $675{\mu}m$ thick silicon substrate. For the operational frequency of 14.5 GHz, an insertion loss better than -0.3 dB, a return loss better than -40 dB, and input/output- and output-port isolations better than -35 dB are achieved for the switching unit.

• Transactions on Electrical and Electronic Materials
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• v.18 no.6
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• pp.359-363
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• 2017

A slotted implantable patch antenna with microstrip feeding is proposed for industrial, scientific, and medical band applications. The result is verified by implanting the antenna in animal tissue. Further, by varying the ground width and introducing a defect into the ground structure, the antenna becomes applicable for worldwide interoperability for microwave access operations. A simulation is performed using Empire XCcel software. An Agilent vector network analyzer is used for analyzing the return loss performance. Simulated and measured results are compared. Antennas with and without defected ground structure both have key advantages including low profile, desirable return loss, good impedance matching and required bandwidth.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.12
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• pp.22-27
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• 2019

In this study, the flow rate and air resistance pressure were analyzed on models a, b, and c due to the front wing angle of the airplanes. Models a, b, and c have front wing angles of 120°, 100°, and 160°, respectively. The results of the flow analyses showed that the flow rate and air resistance pressure of model c were observed to be higher than models a and b. The airplane model with a larger angle to the front wing is thought to be the best model for flight. This result can be applied to development of the best in-flight airplane.

• Journal of Sensor Science and Technology
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• v.18 no.4
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• pp.269-273
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• 2009

In this paper, a study on a portable hydrogen alarm system based on the palladium coated single mode fiber sensor has been reported. The fabricated hydrogen sensor exhibited 0.14 dB, 0.41 dB and 0.54 dB optical intensity variation when it was exposed by the nitrogen and hydrogen mixed gas containing 0.5 %, 1 % and 4 % of the hydrogen concentration, respectively. The fabricated sensor exhibited 20 second of response time and 120 second of recovery time for 4 % hydrogen containing gas. The fiber optics layout and software algorithm for detection of hydrogen leakage have been presented. The implanted portable hydrogen alarm system successfully generated an alarm signal when a 4 % hydrogen containing gas was leaked out.