• Title/Summary/Keyword: channel properties

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Modeling and Experimental Verification of Echo Characteristics of 3 Dimensional Underwater Target (3차원 수중 표적의 반향특성 모델링과 실험적 검증)

  • You, Seung-Ki;Kim, Sunhyo;Choi, Jee Woong;Kang, Donhyug;Jeong, Dongmin
    • The Journal of the Acoustical Society of Korea
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    • v.33 no.3
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    • pp.174-183
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    • 2014
  • When a active sonar signal is transmitted and returned back from a target, it has been distorted by various properties of acoustic channel such as multipath arrivals. And signals have been appeared to be different form by target position and attitude. Therefore, we simulated the target echo signal using 3 dimensional target model include reflects target features. In this paper, we develop components form of a simulated target model is made up equally spaced highlight points, and each part of the target consists of shape function. We can simulate a target echo signal and Target strength (TS) according to wave incident angle. To verify, we made small scale target in kit form and we had got underwater target signal for comparing simulation result in water tank.

Amination of Ethanol over Large Pore Zeolites (큰 기공 제올라이트에서 에탄올의 아민화반응)

  • Jeon, Hee-Young;Jeon, Seong-Hee;Lee, Cheon-Jae;Shin, Chae-Ho
    • Clean Technology
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    • v.14 no.2
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    • pp.87-94
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    • 2008
  • The catalytic properties of large pore zeolite (mordenite, beta, and Y) with 12-membered rings were comparatively evaluated in the synthesis of diethylamines from ethanol amination. The number of strong acid sites, which obviously promoted the formation of mono- and diethylamines, was decreased with the increase of Si/Al ratio of the zeolites that were used. H-beta and H-Y zeolites with multidimensional pore channels favorably formed diethylether by the dimerization of ethanol, due to their large cage volumes and low acid strength. On the other hand, H-mordenite which has one dimensional straight channel was shown to be suitable for the formation of mono- and diethylamine which are well known as the useful intermediates of fine chemicals.

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Structural Analysis of the Streptomyces avermitilis CYP107W1-Oligomycin A Complex and Role of the Tryptophan 178 Residue

  • Han, Songhee;Pham, Tan-Viet;Kim, Joo-Hwan;Lim, Young-Ran;Park, Hyoung-Goo;Cha, Gun-Su;Yun, Chul-Ho;Chun, Young-Jin;Kang, Lin-Woo;Kim, Donghak
    • Molecules and Cells
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    • v.39 no.3
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    • pp.211-216
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    • 2016
  • CYP107W1 from Streptomyces avermitilis is a cytochrome P450 enzyme involved in the biosynthesis of macrolide oligomycin A. A previous study reported that CYP107W1 regioselectively hydroxylated C12 of oligomycin C to produce oligomycin A, and the crystal structure of ligand free CYP107W1 was determined. Here, we analyzed the structural properties of the CYP107W1-oligomycin A complex and characterized the functional role of the Trp178 residue in CYP107W1. The crystal structure of the CYP107W1 complex with oligomycin A was determined at a resolution of $2.6{\AA}$. Oligomycin A is bound in the substrate access channel on the upper side of the prosthetic heme mainly by hydrophobic interactions. In particular, the Trp178 residue in the active site intercalates into the large macrolide ring, thereby guiding the substrate into the correct binding orientation for a productive P450 reaction. A Trp178 to Gly mutation resulted in the distortion of binding titration spectra with oligomycin A, whereas binding spectra with azoles were not affected. The Gly178 mutant's catalytic turnover number for the 12-hydroxylation reaction of oligomycin C was highly reduced. These results indicate that Trp178, located in the open pocket of the active site, may be a critical residue for the productive binding conformation of large macrolide substrates.

Impairment of a parabolic bursting rhythm by the ectopic expression of a small conductance $Ca^{2+}$-activated $K^+$ channel in Aplysia neuron R15

  • Lee, Yong;Han, Jin-Hee;Lim, Chae-Seok;Chang, Deok-Jin;Lee, Yong-Seok;Heun Soh;Park, Chul-Seung;Kaang, Bong-Kiun
    • Proceedings of the Korean Biophysical Society Conference
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    • 2003.06a
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    • pp.38-38
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    • 2003
  • The electrical properties of neurons are produced by the coordinated activity of ion channels (Hille, 1992). $K^{+}$ channels play a key role in shaping action potentials and in determining neural firing patterns. Small conductance $Ca^{2+}$-activated $K^{+}$ (S $K_{Ca}$ ) channels are involved in modulating the slow component of afterhyperpolarization (AHP) (Kohler et al., 1996). Here we examine whether rat type 2 S $K_{Ca}$ (rSK2) channels can affect the shape of the action potential and the neural firing pattern, by overexpressing rat SK2 channels in Aplysia neuron R15. Our results show that rSK2 overexpression decreased the intraburst frequency and changed the regular bursting activity of neurons to an irregular bursting or beating pattern in R15, Furthermore, the overexpression of rSK2 channels increased AHP and reduced the duration of the action potential. Thus, our results suggest that ectopic S $K_{Ca}$ channels play an important role in regulating the filing pattern and the shape of the action potential.ntial.

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A Wavelet-Based EMG Pattern Recognition with Nonlinear Feature Projection (비선형 특징투영 기법을 이용한 웨이블렛 기반 근전도 패턴인식)

  • Chu Jun-Uk;Moon Inhyuk
    • Journal of the Institute of Electronics Engineers of Korea SC
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    • v.42 no.2 s.302
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    • pp.39-48
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    • 2005
  • This paper proposes a novel approach to recognize nine kinds of motion for a multifunction myoelectric hand, acquiring four channel EMG signals from electrodes placed on the forearm. To analyze EMG with properties of nonstationary signal, time-frequency features are extracted by wavelet packet transform. For dimensionality reduction and nonlinear mapping of the features, we also propose a feature projection composed of PCA and SOFM. The dimensionality reduction by PCA simplifies the structure of the classifier, and reduces processing time for the pattern recognition. The nonlinear mapping by SOFM transforms the PCA-reduced features to a new feature space with high class separability. Finally a multilayer neural network is employed as the pattern classifier. From experimental results, we show that the proposed method enhances the recognition accuracy, and makes it possible to implement a real-time pattern recognition.

Realization of Plasmonic Adaptive Coupler using Curved Multimode Interference Waveguide (곡면형 다중모드 간섭 도파로를 사용한 플라즈마 적응 결합기의 구현)

  • Ho, Kwang-Chun
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.16 no.2
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    • pp.165-170
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    • 2016
  • Nano-scale power splitter based on curved plasmonic waveguides are designed by utilizing the multimode interference (MMI) coupler. To analyze easily the adaptive properties of plasmonic curverd multimode interference coupler(PC-MMIC), the curved form transforms equivalently into a planar form by using conformal transformation method. Also, effective dielectric method and longitudinal modal transmission-line theory are used for simulating the light propagation and optimizing the structural parameters at 3-D guiding geometry. The designed $2{\times}2$ PC-MMIC does not work well for quasi-TM mode case due to the bending structure, and it does not exist 3dB coupling property, in which the power splitting ratio is 50%:50%, for quasi-TE mode case. Further, the coupling efficiency is better when the signal is incident at channel with large curvature radius than small curvature radius.

Distributed Transmit Power Control Algorithm Based on Flocking Model for Energy-Efficient Cellular Networks (에너지 효율적인 셀룰러 네트워크를 위한 플로킹 모델 기반 분산 송신전력제어 알고리즘)

  • Choi, Hyun-Ho
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.20 no.10
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    • pp.1873-1880
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    • 2016
  • Most of the energy used to operate a cellular network is consumed by a base station (BS), and reducing the transmission power of a BS is required for energy-efficient cellular networks. In this paper, a distributed transmit power control (TPC) algorithm is proposed based on the flocking model to improve the energy efficiency of a cellular network. Just as each bird in a flock attempts to match its velocity with the average velocity of adjacent birds, in the proposed algorithm each mobile station (MS) in a cell matches its rate with the average rate of the co-channel MSs in adjacent cells by controlling the transmit power of its serving BS. Simulation results show that the proposed TPC algorithm follows the same convergence properties as the flocking model and also effectively reduces the power consumption at the BSs while maintaining a low outage probability as the inter-cell interference increases. Consequently, it significantly improves the energy efficiency of a cellular network.

An Error-Resilient Image Compression Base on the Zerotree Wavelet Algorithm (오류에 강인한 제로트리 웨이블릿 영상 압축)

  • 장우영;송환종;손광훈
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.25 no.7A
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    • pp.1028-1036
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    • 2000
  • In this paper, an error-resilient image compression technique using wavelet transform is proposed. The zerotree technique that uses properties of statistics, energy and directions of wavelet coefficients in the space-frequency domain shows effective compression results. Since it is highly sensitive to the propagation of channel errors, evena single bit error degrades the whole image quality severely. In the proposed algorithm, the image is encoded by the SPIHT(Set Partitioning in Hierarchical Trees) algorithm using the zerotree coding technique. Encoded bitstreams are partitioned into some blocks using the subband correlations and then fixed-length blocks are made by using the effective bit reorganization algorithm. finally, an effective bit allocation technique is used to limit error propagation in each block. Therefore, in low BER the proposed algorithm shows similar compression performance to the zerotree compression technique and in high BER it shows better performance in terms of PSNR than the conventional methods.

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Regression Testing of Software Evolution by AOP (AOP를 이용하여 진화된 프로그램의 회귀테스트 기법)

  • Lee, Mi-Jin;Choi, Eun-Man
    • The KIPS Transactions:PartD
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    • v.15D no.4
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    • pp.495-504
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    • 2008
  • Aspect Oriented Programming(AOP) is a relatively new programming paradigm and has properties that other programming paradigms don't have. This new programming paradigm provides new modularization of software systems by cross-cutting concerns. In this paper, we propose a regression test method for program evolution by AOP. By using JoinPoint, we can catch a pointcut-name which makes it possible to test the incorrect pointcut strength fault and the incorrect aspect precedence fault. Through extending proof rules to aspect, we can recognize failures to establish expected postconditions faults. We can also trace variables using set() and get() pointcut and test failures to preserve state invariant fault. Using control flow graph, we can test incorrect changes in control dependencies faults. In order to show the correctness of our proposed method, channel management system is implemented and tested by using proposed methods.

Single Crystal Silicon Thin Film Transistor using 501 Wafer for the Switching Device of Top Emission Type AMOLEDs (SOI 웨이퍼를 이용한 Top emission 방식 AMOLEDs의 스위칭 소자용 단결정 실리콘 트랜지스터)

  • Chang, Jae-Won;Kim, Hoon;Shin, Kyeong-Sik;Kim, Jai-Kyeong;Ju, Byeong-Kwon
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.16 no.4
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    • pp.292-297
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    • 2003
  • We fabricated a single crystal silicon thin film transistor for active matrix organic light emitting displays(AMOLEDs) using silicon on insulator wafer (SOI wafer). Poly crystal silicon thin film transistor(poly-Si TFT) Is actively researched and developed nowsdays for a pixel switching devices of AMOLEDs. However, poly-Si TFT has some disadvantages such as high off-state leakage currents and low field-effect mobility due to a trap of grain boundary in active channel. While single crystal silicon TFT has many advantages such as high field effect mobility, low off-state leakage currents, low power consumption because of the low threshold voltage and simultaneous integration of driving ICs on a substrate. In our experiment, we compared the property of poly-Si TFT with that of SOI TFT. Poly-Si TFT exhibited a field effect mobility of 34 $\textrm{cm}^2$/Vs, an off-state leakage current of about l${\times}$10$\^$-9/ A at the gate voltage of 10 V, a subthreshold slope of 0.5 V/dec and on/off ratio of 10$\^$-4/, a threshold voltage of 7.8 V. Otherwise, single crystal silicon TFT on SOI wafer exhibited a field effect mobility of 750 $\textrm{cm}^2$/Vs, an off-state leakage current of about 1${\times}$10$\^$-10/ A at the gate voltage of 10 V, a subthreshold slope of 0.59 V/dec and on/off ratio of 10$\^$7/, a threshold voltage of 6.75 V. So, we observed that the properties of single crystal silicon TFT using SOI wafer are better than those of Poly Si TFT. For the pixel driver in AMOLEDs, the best suitable pixel driver is single crystal silicon TFT using SOI wafer.