• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.3
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• pp.117-122
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• 2008

Generally, water is taken through channels and rivers, in which there are many weirs and structures, which cross rivers and temporally hold up water. But this way has its own shortcomings. It is main reason that the water flows through structures, and backwater come into being. So it causes many water quality problems and some flood side-effects and so on. In this study, among the various movable weirs, we installed bottom-discharged and air pressure movable weir in the experimental channel. And we analyzed flowing influence, which is followed by the angle variation of movable weir. We also make further study the flow characteristic variation followed by installing entrance at the bottom to discharge the bottom water. The analysis result was that installed weir angle was increased, and the discharge also gradually increased. The installed weir angle depended on the water quantity, which can be excluded in the bottom. In case of velocity, there was increased as maximum 21.9 times, according to there is entrance or not at the bottom. And in case of water level, it showed the water level of locally above the average decrease in the upper river of weir.

• The Korean Journal of Physiology and Pharmacology
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• v.7 no.2
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• pp.97-101
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• 2003

The salivary glands produce 1.5L of fluid per day. As in other exocrine organs, the general mechanism in the salivary glands is that water movement occurs secondary to osmotic driving forces created by active salt transport. Therefore, high water permeability in the salivary glands is expected to have a variety of aquaporin (AQP), a water channel. Although some AQPs have been known to be present in the salivary glands, roles of parasympathetic nerve in AQP expression have not yet been examined. This study was designed to examine the changes of AQPs and extracellular signal-regulated kinase (ERK) in the submandibular glands after parasympathetic denervation. Right chorda-lingual nerve was cut, and each right (experiment) and left (control) submandibular gland was excised at 1, 3, 7, 14, 30 days after denervation. The denervated right submandibular glands were resulted in weight loss and morphologic changes, including cell loss and atrophy, as the time elapsed after parasympathetic denervation increased, whereas there were no histologic alteration in control side. AQP5 which is known to reside in apical membrane and secretory caraliculi of the submandibular acini were gradually underexpressed according, as the time after denervation increased. Expression of AQP4 in submandibular ductal epithelium was down-regulated after denervation. Besides, AQP3 and 8, which is known to be present in basolateral membrane of the glandular acini, were gradually underexpressed after denervation, similar to the pattern of other types. Expression of ERK, a mitogen-activated protein kinase, was downregulated after parasympathetic denervation in the submandibular gland. These results suggest that parasympathetic nervous system regulates the expression of AQPs in salivary glands, and is in part mediated by ERK pathway.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.23 no.6
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• pp.1017-1023
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• 2013

With the growing use of smartphones, many secure applications are performed on smartphones such as banking, payment, authentication. To provide security services, cryptographic algorithms are performed on smartphones' CPU. However, smartphone's CPU has no considerations against side-channel attacks including Electromagnetic Analysis (EMA). In DesignCon 2012, G. Kenworthy introduced the risk of cryptographic algorithms operated on smartphone against EMA. In this paper, using improved experimental setups, we performed EMA experiments on androin smartphones' commercial secure applications. As a result, we show that the weakness of real application. According to the experimental setups, we picked up the operation of w-NAF scalar multiplication from the operation of Google's Play Store application using radiated EM signal. Also, we distinguished scalar values (0 or not) of w-NAF scalar multiplication.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.7A
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• pp.535-541
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• 2005

This paper proposes a hybrid optical lines composed of single-mode fiber(SMF) and multi-mode fiber(MMF) for gigabit-capable Passive Optical Network(GPON) using a WDM method with a single light source per each channel, and reports the results of transmission performance the proposed lines. The transmission link uses a direct modulated DFB-LD for high speed downstreams at the optical line terminal(OLT) of central office(CO) and a low cost SFP type transceiver for low-speed upstream in optical network unit(ONU). To split or combine the transmission channels, wavelength MUX/DEMUX are used in the optical line section, and MMFs not longer than 1 km are attached to the SMF lines at the ONU side of the WDM-PON links. We have performed the transmission experiment on the downstream of 2.5 Gbit/s, and 1.25 Gbit/s, and the upstream of 1.25 Gbit/s, and 622 Mbit/s which are recommended by ITU-T G.984.2. The transmission margin and feasibility of the proposed links have been tested to be suitable up to 2.5 Gbit/s transmission.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.8
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• pp.746-755
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• 2014

In this paper, we propose the structure of a dual polarized system for a wireless communication. The proposed dual polarized antenna is formed by one vertical antenna and two horizontal antennas that are orthogonal to each other. Vertical and horizontal polarized antennas transmit different signals, but two orthogonal horizontal polarized antennas transmit the same data signals. So, the signals of the proposed dual polarized system construct two dual-polarization planes. And, only one dual-polarization plane with a large signal power is selected at the side of a receiver. The simulation results show that the proposed dual polarized system could obtain a higher capacity compared to an ordinary $2{\times}2$ MIMO (Multi-input Multi-output) system.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.4
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• pp.10-14
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• 2009

We propose a trapezoidal gate AlGaN/GaN high electron mobility transistor(HEMT) to improve the breakdown voltage characteristics and its feasibility is investigated by two-dimensional device simulations. The use of a trapezoidal gate structure appears to be quite effective in dispersing the electric fields concentrated near the gate edge on the drain side from the simulation result. We find that a peak value of the electric field along the 2-DEG channel is reduced by 30%, from 4.8 to 3.5 MV/cm and thereby, the breakdown voltage(Vbr) of the proposed AlGaN/GaN HEMT is increased by about 40%, from 49 to 69 V, compared to those of the standard AlGaN/GaN HEMT.

• The KSFM Journal of Fluid Machinery
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• v.17 no.6
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• pp.77-83
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• 2014

The vessel of integral reactor contains its major primary components such as the fuel and core, pumps, steam generators, and a pressurizer, so its size is proportional to the required space for the installation of each component. The steam generators take up the largest volume of internal space of reactor vessel and their volumes is substantial for the overall size of reactor vessel. Reduction of installation space for steam generators can lead to much smaller reactor vessel with resultant decrease of overall cost for the components and related facilities. A printed circuit heat exchanger is one of the compact types of heat exchangers available as an alternative to conventional shell and tube heat exchangers. Its name is derived from the procedure used to manufacture the flat metal plates that form the core of the heat exchanger, which is done by chemical milling. These plates are then stacked and diffusion bonded, converting the plates into a solid metal block containing precisely engineered fluid flow passages. The overall heat transfer area and pressure drops are evaluated for the steam generator based on the concept of the printed circuit heat exchanger in this study. As the printed circuit heat exchanger is known to have much larger heat transfer area density per unit volume, we can expect significantly reduced steam generator compared to former shell and tube type of steam generator. For the introduction of new steam generator, two design requirements are considered: flow area ratio between primary and secondary flow paths, and secondary side parallel channel flow oscillation. The results show that the overall volume of the steam generator can be significantly reduced with printed circuit type of steam generator.

• Journal of Broadcast Engineering
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• v.16 no.1
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• pp.123-132
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• 2011

Recently, DVC (Distributed Video Coding) is receiving a lot of attention as one of the low complexity video encoding techniques suitable for various applications with computation-limited and/or power-limited environment, and is being actively studied for improving the coding efficiency. This paper proposes a rate-distortion based selective block encoding scheme. First, the motion information is obtained in the process of generating side information at decoder and received through the feedback channel, and then, based on this information, the proposed method performs a selective block encoding based on rate-distortion optimization. Experimental results show that the performance of the proposed scheme reaches up to 2.2 dB PSNR gain over the existing scheme. Moreover, it is shown that the complexity can be reduced by encoding parts of region considering rate-distortion cost.

• Journal of Broadcast Engineering
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• v.16 no.1
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• pp.133-143
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• 2011

In this paper, a complexity-balancing algorithm is proposed for distributed video coding based on entropy coding. In order to reduce complexity of DVC-based decoders, the proposed method employs an entropy coder instead of channel coders and the complexity-balancing method is designed to improve RD performance with minimal computational complexity. The proposed method performs motion estimation in the decoder side and transmits the estimated motion vectors to the encoder. The proposed encoder can perform more accurate refinement using the transmitted motion vectors from the decoder. During the motion refinement, the optimal predicted motion vectors are decided by the received motion vector and the predicted motion vectors and complexity load of block is allocated by adjusting the search range based on the difference between the received motion vector and the predicted motion vectors. The computational complexity of the proposed encoder is decreased 11.9% compared to the H.264/AVC encoder and that of the proposed decoder are reduced 99% compared to the conventional DVC decoder.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.6 no.1
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• pp.87-94
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• 1986

Under natural condition, many rivers had shallow and gently curved shape in plane. A two dimensional mathematical model of the flow was a very attractive one. The flow characteristics in bended open channels were analyzed. The mathematical model based on the mass and the momentum equation of the two-dimensional unsteady flow was developed by introducing finite difference method and the double sweep algorithm. For the purpose of the verification of this model, the modeling results were applied to the L.F.M flume and the I.I.H.R flume. The results had a good agreement with the experimental data of the flumes. The results could be more close to the experimental data by controlling Chezy Coefficients in order to reduce the effect of friction around side wall, and be studied the importance of the convective term. The water surface profile, the direction and scale of depth average mean velocity and the path of the thread of maximum velocity in bended open channels could be computed.