• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.16 no.11
• /
• pp.2569-2574
• /
• 2012

HMS(Hull Mount Sonar) equipment mounted on PCC(Patrol Combat Corvette) is suitably designed for active mode, and the specific character of sensor or system is not appropriate for the frequency range to detect a torpedo. In this article, in order to implement the function of detecting torpedoes with HMS of existing PCC, I will analyze the feature of input signals each PCCs and design a circuit to compensate reversely for the input signal in certain frequency. And also, I will suggest the most adequate torpedo defense system suitable for the special operating environment and the characteristic of naval vessels, implementing functions such as AGC of input signal and fixing the frequency range of different input signals per different warships.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.19 no.2
• /
• pp.354-363
• /
• 1994

This paper describes the method that voice traffic is served efficiently in BISDN. Voice is divided into talkspurt and silent period, and it is possible to transmit olny talksurt by the speech activity detection. This paper described the voice traffic control algorithm in the ATM network where cell discarding method is applied to the embedded ADPCM voice data. For traffic control, the cell discarding was used over low priority cells when it overflows the queue threshold. To estimate the efficiency of traffic control algorithm, the computer simuation was performed with cell loss probability, queue length and mean delay as performance parameters. The embedded ADPCM voice coding and cell disscarding resulted in improving the voice cell traffic efficiency and the dynamic control over network congestion.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.31 no.12A
• /
• pp.1214-1222
• /
• 2006

In this paper, an efficient direction-r)f-arrival based adaptive beamforming algorithm for orthogonal frequency-division multiple-access smart antenna systems is proposed. The proposed algorithm provides a high performance by steering main beams to the directions of a desired signal, whereas steering nulls to the directions of the interference, using the estimated directions. The beamforming outputs obtained by steering the main beams to the distinct directions of resolvable multipath signals are combined in a maximal ratio manner to exploit angular diversity gain. The performance elf the proposed algorithm is finally evaluated in cellular mobile environments to verify its efficiency and is compared with that of least-squares beamforming algorithm, by taking the WiBro system as a target system.

• Journal of IKEEE
• /
• v.2 no.2 s.3
• /
• pp.299-308
• /
• 1998

In this paper, reliable switched reluctance motor(SRM) drive system and 4-rule based fuzzy logic modifier(FLM) of the conventional PI controller are presented. The i80C196KC, low-cost one-chip microcontroller is used for designing SRM drive controller which include the speed controller and the starting sequence. The fuzzy logic modifier which exhibits a stabilizing effects on the closed-loop system, has good robustness regarding the improperly tuned PI controller. The simulation and experimental results are performed to verify the capability of proposed control method on 6/4 salient type SRM.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.16 no.4
• /
• pp.506-511
• /
• 2006

This paper considers a method to design sliding mode observers for a class of uncertain systems using Linear Matrix Inequalities(LMI). In an LMI-based sliding mode observer design method for a class of uncertain systems the switching surface is set to be the difference between the observer and system output. In terms of LMIs, a necessary and sufficient condition is derived for the existence of a sliding-mode observer guaranteeing a stable sliding motion on the switching surface. The gain matrices of the sliding-mode observer are characterized using the solution of the LMI existence condition. The results are illustrated by an example.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.8 no.3
• /
• pp.508-512
• /
• 2007

In this paper, a novel wideband crossed planar monopole antenna with the double resonance characteristics is proposed. The proposed monopole antenna consists of a wideband crossed planar monopole antenna and L-shaped slits. In order to generate double resonance characteristics on the proposed monopole antenna, the length of L-shaped slit on the antenna surface is obtained from the quarter-wavelength of the second resonance frequency The double resonance characteristics of the proposed antenna can be easily designed by the control of length of L shaped slit at an interesting frequency. The proposed antenna having an omnidirectional radiation pattern and a high gain over the double resonance frequency bands, respectively, is suitable for mobile multiband antenna.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.36 no.3C
• /
• pp.127-132
• /
• 2011

In this paper, we propose a cooperative communication scheme for high transmission efficiency and coverage extension under multipath fading environment of moving networks. The proposed scheme uses a Space-Time Block Code (STBC) for improvement of receiving performance by using virtual Multiple-Input Multiple-Output(MIMO) transmit diversity. It can also achieve faster transmission time than a conventional scheme by using virtual MIMO configurations. Simulation results have shown that the proposed scheme provides SNR improvement and has faster transmission time compared to the conventional scheme, since it can utilize the good properties of spatial diversity and coding gain by using virtual MIMO configuration. In this paper, we propose simulations of UWB communication system to show validity by using the MATLAB.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2002.05a
• /
• pp.802-807
• /
• 2002

The updating of FE model to match it with the experimental results needs the modal information. There are two cases where this methodology is ill-equip to deal with； under-determined and ill-conditioning problem. The feedback exciter that uses the summation of the white noise and the signals from the measurement sensors multiplied with feedback gains can deal with these problems as the new modal data from the closed loop system generate more constraints the updating parameters should obey. The new modal data from the closed loop system should be different to enhance the condition of the modal sensitivity matrix. In this research, a guide for the selection of the sensor locations and the decision of the corresponding output feedback gains is proposed. This method is based on the sensitivity of the modal data with respect to the feedback gains. Through the proper selection of the exciter and sensor locations and the feedback gain, the eigenvalue sensitivity of the updating parameters which cause the ill-conditioning of the modal sensitivity matrix can be modified and consequently the error contamination in updating parameters are reduced.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.9 no.2
• /
• pp.226-237
• /
• 1998

In recent SATCOM systems, transparent transponders are widely used. The transponder is, however, the most vulnerable part in SATCOM systems against jamming interference. All signals within the transponder bandwidth are frequency-converted and retransmitted with IM(intermodulation) products. In this paper, the method is proposed that makes the SJR(Signal-to-Jammer ratio) better. The bandwidth spreading of the user signal can reduce the jammers effects. The geostationary satellite system is modeled to simulate and to certificate the capability of suppression of jammers by DSSS. If signal is partially-overlapped by jammer and PG(processing gain) is 16.9 [dB] for 2ASK jammer and about 16.8 [dB] for QPSK jammer, when BER is $10^{-3}$.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.13 no.1
• /
• pp.101-106
• /
• 2018

This study proposes a method of controller design for precise position control in the use of solenoid which is widely used in industrial field. First, we design a Luenberger's observer that can accurately estimate the disturbance and set the appropriate gain. Based on the observed state, a fractional PD controller is designed and applied to the position control. As a result, the fractional order controller can obtain almost the same control performance even if the target position is different. In addition, it was confirmed that the position error of the steady state is within 0.1 [%] and the rising time is within about 0.05 second.