• JSTS:Journal of Semiconductor Technology and Science
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• v.16 no.5
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• pp.635-640
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• 2016

Tunnel field-effect transistor (TFET) is a promising candidate for the next-generation electron device. However, technical issues remain for their practical application: poor current drivability, shor-tchannel effect and ambipolar behavior. We propose herein a novel recessed-channel TFET (RTFET) with the asymmetric source and drain. The specific design parameters are determined by technology computer-aided design (TCAD) simulation for high on-current and low S. The designed RTFET provides ${\sim}446{\times}$ higher on-current than a conventional planar TFET. And, its average value of the S is 63 mV/dec.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.31 no.4
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• pp.93-99
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• 2008

In science and engineering programs in the U.S. in 2000 China, South Korea and India were top countries of origin sending students. More than half of the students intend to stay in the U.S. Immigration, education and occupational choices all have human capital aspects that require investments. A framework is proposed where expected incomes in both countries of origin and destination are calculated and used to reflect the substitution effect and the wealth effects of the expected incomes of two countries. It appears that nonpecuniary effects of education encourages immigration as much as pecuniary effects in the immigration decision equation. After the pecuniary effects are accounted for there is some negative nonpecuniary tendency of the professional scientists to immigrate to the U.S.

• Geomechanics and Engineering
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• v.13 no.6
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• pp.963-975
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• 2017

Improvement of soft clay deposit by preloading with vertical drains is one of the most popular techniques followed worldwide. These drains accelerate the rate of consolidation by shortening the drainage path. Although the analytical and numerical solutions available are mostly based on equal strain hypothesis, the adoption of free strain analysis is more realistic because of the flexible nature of the imposed surcharge loading, especially for the embankment loading used for transport infrastructure. In this paper, a numerical model has been developed based on free strain hypothesis for understanding the behaviour of soft ground improvement by vertical drain with preloading. The unit cell analogy is used and the effect of smear has been incorporated. The model has been validated by comparing with available field test results and thereafter, a hypothetical case study is done using the available field data for soft clay deposit existing in the eastern part of Australia and important conclusions are drawn therefrom.

• Journal of Electrical Engineering and Technology
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• v.12 no.6
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• pp.2324-2332
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• 2017

This paper presents the electrical performances of novel AlGaSb/InGaAs heterojunction-based vertical-tunneling field-effect transistor (VTFET). The device performance was investigated in views of the on-state current ($I_{on}$), drain-induced barrier thinning (DIBT), and subthreshold swing (SS) as the gate length ($L_G$) was scaled down. The proposed TFET with a $L_G$ of 5 nm operated with an $I_{on}$ of $1.3mA/{\mu}m$, a DIBT of 40 mV/V, and an SS of 23 mV/dec at a drain voltage ($V_{DS}$) of 0.23 V. The proposed TFET provided approximately 25 times lower DIBT and 12 times smaller SS compared with the conventional $L_G$ of 5 nm TFET. The AlGaSb/InGaAs VTFET showed extremely high scalability and strong immunity against short-channel effects.

• Journal of Korea Water Resources Association
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• v.55 no.spc1
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• pp.1251-1260
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• 2022

Recently, due to the deterioration of watermains and the detachment of scale which is accumulated on the watermain surface, water quality accidents in a water supply network occur frequently. As scale accumulated on watermains is stabilized, it may not cause water quality accidents under the normal operating condition. However, due to water hammer or transient flow caused by the abrupt velocity and/or direction of flow change, it can be detached from the watermain surface resulting in water quality accidents. To prevent these kinds of water quality accidents, it is required to remove scale by watermain cleaning regularly. Many researches about flushing which is the most popular water cleaning method are focused on the desirable velocity criteria and the cleaning condition to accomplish the effect of flushing whereas less amount of research effort is given to develop a method to consider whether the desirable velocity for flushing can be obtained before flushing is performed. During flushing, the major and minor headloss is occurred when flushing water flows through a hydrant or drain valve. These headloss may slow down the velocity of flushing water so that it can reduce the flushing effect. Thus, in this study, we suggest a method to simulate the flow velocity of flushing water using "MinorLoss Coefficient" and "Emitter Coefficient" in EPANET. The suggested method is applied to a sample network and the water supply network of "A" city in Korea to compare the flushing effect between "flushing through a hydrant" and "flushing through a drain valve". In case of "flushing through a hydrant", if the hydraulic condition ocurring from a watermain pipe connecting to the inlet pipe of a hydrant to the outlet of a hydrant is not considered, the actual flowrate and velocity of a flow is less than the simulated flowrate and velocity of a flow. In case of "flushing through a drain valve", the flushing velocity and flowrate can be easily simulated and the difference between the simulated and the actual velocity and flowrate is not significant. Also, "flushing through a drain valve" is very effective to flushing a long-length pipe section because of its efficiency to obtain the flushing velocity. However, the number and location of a drain valve is limited compared to a hydrant so that "flushing through a drain valve" has a limited application in the field. For this reason, the engineer should consider various field conditions to come up with a proper flushing plan.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1277-1280
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• 2005

A high-aspect-ratio and high-resolution stainless steel shadow mask for organic thin-film transistors (OTFTs) circuit has been fabricated by a new method which combines photochemical machining, micro-electrical discharge machining (micro-EDM), and electrochemical etching (ECE). First, connection lines and source-drain holes are roughly machined by photochemical etching, and then the part of source and drain holes is finished by the combination of micro-EDM and ECE processes. Using this method a $100\;\mu{m}$ thick stainless steel (AISI 304) shadow mask for inverter can be fabricated with the channel length of $30\;\mu{m}\;and\;10\;\mu{m}\;respectively.\;The\;width\;of\;connection line\;is\;150\;\mu{m}$. The aspect ratio of the wall is about 5 and 15, respectively. Metal lines and source-drain electrodes of OTFTs were successfully deposited through the fabricated shadow mask.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.04a
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• pp.194-202
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• 2009

The paper deals with the countermeasure against structure-borne noise source and noise reduction of drainage pipes. Recently, the problem the problem of the toilet drain noise of an apartment house has been become the center of public interest and a target of public grievance. Generally, the drain noise of a toilet in the apartment house has a pink noise characteristics below 2 kHz level, and therefore, the structure-borne noise has a great effect on the entire drain noise. In order to measure the transmission loss for various kinds of pipes such as PVC pipes, cast-iron pipes and newly developed AS pipes, experimental setup containing speakers as a sound source was designed and manufactured. The second-stories measurement room with a small size anechoic chamber was constructed and the noise level for different kinds of drainage pipes was measured by the sound level meter. Through the experimental research in the study, noise reduction capacity for various kinds of drainage pipes and countermeasures against structure-borne noise source are demonstrated.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.5
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• pp.452-458
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• 2005

In Korea, pumping pipe using gravity way by water is most popular method in drainage system. But, it is difficult to repair a drainpipe in this method because the drain pipe diameter is increased as using this method. In this research, we propose a new drainage system. The system aim for an adaptedness with buildings, freedom of plan, construction and renewal in water pipe equipments, etc. The new system is not need of incline of piping, and it uses drainage power that is changed potential energy by high velocity flow as making Siphonage at vertical pipe. Therefore, the diameter of piping can decreased than existing piping system established in the ceiling. Also because connecting position will be located at the lower part, it is changed the potential energy of drainage to the high velocity flow. In addition, drainage will be smooth because the fixture drain is linked by each drain pipes.

• Transactions on Electrical and Electronic Materials
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• v.12 no.3
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• pp.93-97
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• 2011

In this paper, we discuss design considerations for an n-channel metal-oxide-semiconductor field-effect transistor (MOSFET) with a lateral asymmetric channel (LAC) doping profile. We employed a 0.35 ${\mu}M$ standard complementary MOSFET process for fabrication of the devices. The gates to the LAC doping overlap lengths were 0.5, 1.0, and 1.5 ${\mu}M$. The drain current ($I_{ON}$), transconductance ($g_m$), substrate current ($I_{SUB}$), drain to source leakage current ($I_{OFF}$), and channel-hot-electron (CHE) reliability characteristics were taken into account for optimum device design. The LAC devices with shorter overlap lengths demonstrated improved $I_{ON}$ and $g_m$ characteristics. On the other hand, the LAC devices with longer overlap lengths demonstrated improved CHE degradation and $I_{OFF}$ characteristics.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.6
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• pp.497-504
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• 2014

The digital signage display is actively researched as the next generation of large FPD. To commercialize those digital signage display, the manufacturing cost must be downed with printing method instead of conventional photolithography. Here, we demonstrate a reverse offset printed TFT electrodes for the digital signage display. For the fabricated source/drain and gate electrode, we used Ag ink, silicone blanket, Clich$\acute{e}$ and reverse offset printer. We printed uniform TFT electrode patterns with narrow line width(10 ${\mu}m$ range) and thin thickness(nm range). In the end the printing source/drain and gate electrode are successfully achieved by optimization of experimental conditions such as Clich$\acute{e}$ surface treatment, ink coating process, delay time, off/set process and curing temperature. Also, we checked that the printing align accuracy was within 5 ${\mu}m$.