• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.3 no.3
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• pp.73-80
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• 2010

Complex-valued blind algorithms which are based on constant modulus error and Euclidian distance (ED) between two probability density functions show relatively poor performance in spite of the advantages of information theoretic learning since the inherent characteristics of the constant modulus error prevent the algorithm from coping with the symbol phase rotation caused by the complex channels. In this paper, we show that the symbol phase rotation problem can be avoided and the advantages of information theoretic learning can be preserved by introducing decision-directed mode to the blind algorithm whenever the equalizer output power lies in the neighborhood of multi-modulus levels. Simulation results through MSE convergence and constellation comparison for severely distorted complex channels show significantly enhanced performance of symbol-point concentration and no phase rotation problems caused by the complex channel models.

• BMB Reports
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• v.39 no.1
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• pp.91-96
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• 2006

Previously, we have shown that nitric oxide (NO) directly activates the Maxi-K channels. In the present study, we have investigated whether NO has prolonged effects on the Maxi-K channels reconstituted in lipid bilayer. Application of S-nitroso-N-acetyl-D, L-penicillamine (SNAP), a NO donor, induced an immediate increase of open probability (Po) of Maxi-K channel in a dose-dependent manner. When SNAP was removed from the cytosolic solution, the Po did not simply returned to, but irreversibly decreased to a level lower than that of the control Po. At 0.2 mM, (Z)-[N-(3-Ammoniopropyl)-N-(n-propyl)amino] diazen-1-ium-1,2-diolate (PAPA-NO), another NO donor, produced a similar increase of Po and decrease of Po upon washout. The increasing effects of SNAP on Po were not blocked by either 50 U/ml superoxide dismutase (SOD) or 2 mM N-ethylmaleimide (NEM) pre-treatments. However, NEM appears to be ineffective when applied after SNAP. These results suggest that NO can modulate Maxi-K channel via direct interaction and chemical modification, such as S-nitrosylation in the brain.

• International Journal of Control, Automation, and Systems
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• v.5 no.1
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• pp.104-109
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• 2007

This paper is about a redundancy management system design for the Smart UAV(unmanned aerial vehicle) which utilizes the tilt..rotor mechanism. In order to meet the safety requirement on the PLOC(probability of loss of control) of $1.7{\times}10^{-5}$ per flight hour for FCS (flight control system) failures, a digital FCS is mechanized with a dual redundant structure. A fault detection system which is composed of a CCM(cross channel monitor) and analytic redundancy using the Kalman filtering is designed, and its effectiveness is evaluated through experiments. A threshold level and persistence count for managing redundant sensors are designed based on the statistical analysis of the FCS sensors. To increase the survivability of the UAV after the loss of critical sensors in the SAS(stability augmentation system) and to provide reference information for a tie-breaking condition at which an ILM(in-line monitor) cannot distinguish the faulty channel between two operating ones, the Kalman filter approach is investigated.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.11
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• pp.2708-2716
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• 2013

This paper presents implementation of embedded remote monitoring diagnosis system which has effective wireless channel structure and communication protocols with user-friendly UI for intelligent digital vessel. Developed system contains integrated vessel monitoring system, server, exclusive mobile terminal and smart phone. We designed an effective dual structure communication channel and simple but effective communication protocol on the monitoring system. Failures of the wireless communication are minimized and the wrong wireless communication channel is immediately replaced. In addition, we developed an effective embedded Linux UI for LCD. The implemented wireless monitoring system was tested and verified on digital vessel.

• Journal of Korea Society of Digital Industry and Information Management
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• v.6 no.4
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• pp.131-142
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• 2010

Due to the development of the Internet, Internet banking that we are liberated from time and space has evolved into banking system. So modern life became comfortable. However, Dysfunction (malicious Information leakage and hacking etc.) of the Internet development has become a serious social problem. According to this, The need for security is rapidly growing. In this paper, we proposed the Internet Banking Authentication System using a dual-channel in OTP(One Time Password) authentication. This technology is that A user transfer transaction information to Bank through one Internet channel then bank transfer transaction information to user using the registered mobile phone or smart phone. If user confirm transaction information then bank request user's OTP value. User create OTP value and transfer to bank and bank authenticate them throgth the ARS. If authentication is pass then transaction permitted. Security assessment that the proposed system, the security requirement that the confidentiality and integrity, authentication, repudiation of all of the features provide a key length is longer than the current Internet banking systems, such as using encryption, the security provided by the Financial Supervisory Service Level 1 rating can be applied to more than confirmed.

• Transactions of Materials Processing
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• v.15 no.2 s.83
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• pp.105-111
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• 2006

A study was made to investigate the microstructure and the mechanical properties of low-carbon steel, Al-Mg alloy and Ti-6Al-4V alloy each representing bcc, fcc and hcp crystal structures, respectively fabricated by equal-channel angular(ECA) pressing. After a series of ECA pressings was performed, most grains were significantly refined below ${\mu}m$ in diameter with high mis-orientation of grain boundaries irrespective of different crystal structure used. Regarding the strain hardening capability, tensile tests of ultrafine grain (UFG) dual-phase (ferrite/martensite) steel which was different from UFG ferrite-pearlite steel were carried out at ambient temperature, and corresponding mechanical properties were discussed in relation to modified C-J analysis. Low-temperature and/or high strain-rate superplasticity of the UFG Al-Mg alloy and UFG Ti-6Al-4V alloy were also studied. Based on the analysis used in this study, it was concluded that UFG alloys exhibited the enhanced mechanical properties as compared to coarse-grained (CG) counterparts.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.9
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• pp.2120-2133
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• 2013

In this paper, we address the problem of linear minimum mean-squared error (MMSE) transmitter design for the cognitive radio (CR) multi-user multiple-input single-output (MU-MISO) broadcasting channel (BC), where the cognitive users are subject to not only a sum power constraint, but also a interference power constraint. Evidently, this multi-constraint problem renders it difficult to solve. To overcome this difficulty, we firstly transform it into its equivalent formulation with a single constraint. Then by utilizing BC-MAC duality, the problem of BC transmitter design can be solved by focusing on a dual MAC problem, which is easier to deal with due to its convexity property. Finally we propose an efficient two-level iterative algorithm to search the optimal solution. Our simulation results are provided to corroborate the effectiveness of the proposed algorithm and show that this proposed CR MMSE-based scheme achieves a suboptimal sum-rate performance compared to the optimal DPC-based algorithm with less computational complexity.

• ETRI Journal
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• v.42 no.5
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• pp.773-780
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• 2020

A 40 nm complementary metal oxide semiconductor carrier-aggregated drive amplifier with high linearity is presented for sub-GHz Internet of Things applications. The proposed drive amplifier consists of two high linear amplifiers, which are composed of five differential cascode cells. Carrier aggregation can be achieved by switching on both the driver amplifiers simultaneously and combining the two independent signals in the current mode. The common gate bias of the cascode cells is selected to maximize the output 1 dB compression point (P1dB) to support high-linear wideband applications, and is used for the local supply voltage of digital circuitry for gain control. The proposed circuit achieved an output P1dB of 10.7 dBm with over 22.8 dBm of output 3rd-order intercept point up to 0.9 GHz and demonstrated a 55 dBc adjacent channel leakage ratio (ACLR) for the 802.11af with -5 dBm channel power. To the best of our knowledge, this is the first demonstration of the wideband carrier-aggregated drive amplifier that achieves the highest ACLR performance.

• Proceedings of the Korea Society for Simulation Conference
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• 2001.05a
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• pp.133-133
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• 2001

무선 근거리 지역망(Wireless LAN;WLAN) 환경에서 다중 채널을 이용하여 실시간 서비스를 제공하기 위한 매체 접근제어 계층에서의 채널의 사용 구간 할당 방법을 제안하고, 컴퓨터 모의 실험을 통하여 제한된 방식의 실시간 서비스 지원 성능과 채널의 사용 효율을 분석한다. 제안한 채널 사용 구간 할당 방안은 개선된 매체 접근 제어 프로토콜 RICH-DP (Receiver-Initiated Channel-Hopping with Dual Polling)를 바탕으로 한다. 무선 환경에서 RTS-CTS를 사용하는 프로토콜은 SRMA, MACA, MACAW, IEEE 802.11, FAMA 등이 있다. 최근에 단일 채널을 환경에서 RICH(Receiver Initiated Channel-Mopping) 프로토콜이 제안되었다. RICH는 충돌 회피를 위해서 경쟁 구간에서 충돌 감지(carrier sensing)을 사용한다. RICH는 제한된 어플케이션에 국한되는 단절이 있다. 반면에 RICH-DP는 다중 채널 환경에서 충돌 감지와 특별한 코드(spreading code) 할당 없이 일반화된 충돌 회피를 제공한다. 실시간 서비스를 이용하자 차는 단말들로 하여금 RICH-DP를 사용하여 서비스를 제공할 때, 대역폭에 대한 정보를 AP(Access Point)로 전송토록 함으로써 비경쟁 구간에서 뿐 아니라, 경쟁구간에서도 높은 채널 효율이 얻어질 수 있도록 하고 있다. 제한된 방안의 성능 평가를 위한 모의 실험은 OPNET를 이용하여 실시간 서비스 데이터를 7개의 상태 천이를 갖는 VBR 소스로 모델링하고 비동기 트래픽들은 Poisson 소스로 모델링하여 실시간 서비스 단발들의 이용 대역폭과 채널 처리율과 시스템 지연시간을 성능 평가 인자로 하여 수행하였다. 논문에서 제한된 방법을 적용한 개선된 RICH-DP을 모의 실험을 통하여 분석한 결과 기존의 제한된 RICH-DP는 실시간 서비스에 대한 처리율이 낮아지며 서비스 시간이 보장되지 못했다. 따라서 실시간 서비스에 대한 새로운 제안된 기법을 제안하고 성능 평가한 결과 기존의 RICH-DP보다 성능이 향상됨을 확인 할 수 있었다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.8
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• pp.3789-3808
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• 2017

This paper studies a multi-antenna wireless relay network in the presence of a jammer. In this network, the source node transmits signals to the destination node through a multi-antenna relay node which adopts the amplify-and-forward scheme, and the jammer attempts to inject additive signals on all antennas of the relay node. With the linear beamforming scheme at the relay node, this network can be modeled as an equivalent Gaussian arbitrarily varying channel (GAVC). Based on this observation, we deduce the mathematical closed-forms of the capacities for two special cases and the suboptimal achievable rate for the general case, respectively. To reduce complexity, we further propose an optimal structure of the beamforming matrix. In addition, we present a second order cone programming (SOCP)-based algorithm to efficiently compute the optimal beamforming matrix so as to maximize the transmission rate between the source and the destination when the perfect channel state information (CSI) is available. Our numerical simulations show significant improvements of our propose scheme over other baseline ones.