• Proceeding of EDISON Challenge
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• 2014.03a
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• pp.495-497
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• 2014

Combining the quantum transport theory with new field of Spin Caloritronics, we investigate on the influence of thermal gradient on the magneto tunnel junction structure under various circumstances. The results indicate enhancement in performance of spintronic device is possible using thermal energy.

• Journal of Korea Water Resources Association
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• v.45 no.8
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• pp.767-782
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• 2012

Accumulation of sediment within pipelines, manholes, and other components of urban sewer systems can have a bad influence on sewerage arrangements, such as the resistance of the passage of flows, the cause of urban flooding and the premature operation of combined sewer overflows, and the inevitable pollution of watercourses. Therefore, it is necessary to understand the movements and sedimentation of sediment loads in combining junction manholes by experiments. In this study, hydraulic experimental apparatus which can change the manhole shapes (square, circle) were installed to measure deposited sedimentation quantity. The quantity of deposited sediment loads was measured by different conditions, for instance, the inflow conditions of sediment (continuous and certain period), the amount of inflow sediment, and the variation of inflow pipe of sediment. The combining junction manhole that was set up a inclined benching have the considerable effect of reduction of sedimentation in manholes without apropos of the change of manhole shapes. Therefore, the improved manhole could be increased the drainage capacity of sewerage arrangements in urban sewer systems.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.9
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• pp.870-878
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• 2000

An experimental study and a modeling are peformed to investigate the pressure drop of combining junctions in two-phase flows. Experiments on tripod geometry used in a condenser or an evaporator, are conducted with inlet mass fluxes from 200 to$ 400 kg/m^2$s, and pipe diameters of 7 m and 9.52 m. The working fluid is R22. The result shows that the pressure drop increases as the quality does, but the effect of the increase of the pressure decreases when the diameter of a pipe increases. When the mass flux increases, the pressure drop linearly does. Furthermore, when the pipe diameter decreases, the pressure drop has a quadratic increase.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.2
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• pp.41-46
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• 2013

In this paper, low pass filters(LPF) using corrugated waveguide for satellite communication is proposed. To design the proposed LPF, the corrugated waveguide and impedance transformers are combined. The corrugated waveguide is formed by arrangement of T-junction. To obtain low insertion loss and high isolation propriety, T-junction is designed by using Chebyshev function. Impedance transformers is designed by combining T-junction with different heights at both ends of the corrugated waveguide to get high return loss. The measured results of the proposed LPF have a return loss of over 35.4 dB, a insertion loss of less than 0.1 dB from 12.25 GHz to 12.75 GHz and a isolation propriety of over 54.5 dB from 14 GHz to 14.5 GHz. From these results, it is confirmed that the proposed waveguide LPF can be used for satellite communication.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.22 no.2
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• pp.35-42
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• 2022

In this paper, a method to increase the combining efficiency and isolation of the combiner, the core module of SSPA (solid state amplifier), was studied. Specifically, the isolation was secured by matching the common port and the isolation port in the waveguide combiner. The matching structure for matching is in the form of a circular disk and is engraved inside the waveguide combiner. The structure is very simple, so it is possible to secure stable performance. And this structure showed more than 60 times higher critical power performance compared to previous studies, confirming that it is suitable for high output. And by combining 1-stage T-junction and 2, 3 stage MagicT combiner, miniaturization was achieved and the combining efficiency was optimized by reducing the insertion loss. The fabricated waveguide coupler obtained an isolation of 16dB or more and a coupling efficiency of 86.2%.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.389.1-389.1
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• 2016

The flexible solid state device has been widely studied as portable and wearable device applications such as display, sensor and curved circuits. A zero-bias operation without any external power consumption is a highly-demanding feature of semiconductor devices, including optical communication, environment monitoring and digital imaging applications. Moreover, the flexibility of device would give the degree of freedom of transparent electronics. Functional and transparent abrupt p/n junction device has been realized by combining of p-type NiO and n-type ZnO metal oxide semiconductors. The use of a plastic polyethylene terephthalate (PET) film substrate spontaneously allows the flexible feature of the devices. The functional design of p-NiO/n-ZnO metal oxide device provides a high rectifying ratio of 189 to ensure the quality junction quality. This all transparent metal oxide device can be operated without external power supply. The flexible p-NiO/n-ZnO device exhibit substantial photodetection performances of quick response time of $68{\mu}s$. We may suggest an efficient design scheme of flexible and functional metal oxide-based transparent electronics.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.7
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• pp.1363-1374
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• 2009

This paper reviews the characteristics and technical trends in Power MOSFET technology that are leading to improvements in power loss for power electronic system. The silicon bipolar power transistor has been displaced by silicon power MOSFET's in low and high voltage system. The power electronic technology requires the marriage of power device technology with MOS-gated device and bipolar analog circuits. The technology challenges involved in combining power handling capability with finger gate, trench array, super junction structure, and SiC transistor are described, together with examples of solutions for telecommunications, motor control, and switch mode power supplies.

• JSTS:Journal of Semiconductor Technology and Science
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• v.14 no.3
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• pp.339-344
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• 2014

This paper presents a novel bipolar junction transistor (BJT) based electrostatic discharge (ESD) protection device. This protection device was designed for 20V power clamps and fabricated by a process with Bipolar-CMOS-DMOS (BCD) $0.18{\mu}m$. The current-voltage characteristics of this protection device was verified by the transmission line pulse (TLP) system and the DC BV characteristic was verified by using a semiconductor parameter analyzer. From the experimental results, the proposed device has a trigger voltage of 29.1V, holding voltage of 22.4V and low on-resistance of approximately $1.6{\Omega}$. In addition, the test of ESD robustness showed that the ESD successfully passed through human body model (HBM) 8kV. In this paper, the operational mechanism of this protection device was investigated by structural analysis of the proposed device. In addition, the proposed device were obtained as stack structures and verified.

• JSTS:Journal of Semiconductor Technology and Science
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• v.13 no.6
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• pp.546-550
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• 2013

We propose a novel negative differential resistance (NDR) device with ultra-high peak-to-valley current ratio (PVCR) by combining pn junction diode with depletion mode nanowire (NW) transistor, which suppress the valley current with transistor off-leakage level. Band-to-band tunneling (BTBT) Esaki diode with degenerately doped pn junction can provide multiple switching behavior having multi-peak and valley currents. These multiple NDR characteristics can be controlled by doping concentration of tunnel diode and threshold voltage of NW transistor. By designing our NDR device, PVCR can be over $10^4$ at low operation voltage of 0.5 V in a single peak and valley current.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.5C
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• pp.506-511
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• 2002

In this paper, waveguide-based power combiner using conventional slotline-to-microstrip transition was proposed at Ka-band. The proposed 2-way and 4-way power combiner consist of waveguide-to-slotline transition, two or four slotline-to-microstrip transitions, and impedance matching networks. Their structures were simulated and optimized by 3-D FEM simulation. The 2-way power combiner showed a very low back-to-back insertion loss of 1.0 dB and return loss better than 15 dB from 25.7 GHz to 29.8 GHz except the resonant frequency. The 2-way power combining approach was extended to 4-way power combining using slotline tee junction. The 4-way power combiner showed the similar performance to that of 2-way power combiner with 2 GHz smaller bandwidth.