• Journal of Korea Society of Digital Industry and Information Management
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• v.14 no.4
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• pp.93-99
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• 2018

This paper presents an implementation method using NDK (Network Developer's Kit) of GNU (GNU is Not Unix) Radio and Multicore DSP (Digital Signal Processor) to implement LTE (Long Term Evolution) SDR (Software Defined Radio) Platform. In order to satisfy 1.4MHz, 3MHz, 5MHz and 10MHz of the bandwidth supported by LTE, USRP (Universal Software Radio Peripheral) X series which is an RF (Radio Frequency) transceiver of Ettus Research was used. To control this, GNU Radio which is an open source software radio toolkit was used. We also used NDK from TI (Texas Instruments) DSP to transfer data between USRP and DSP. Experimental results show throughput results according to each bandwidth, thus confirming the feasibility of implementing LTE SDR Platform using GNU Radio and NDK of TI DSP.

• Journal of Electrochemical Science and Technology
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• v.10 no.2
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• pp.177-184
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• 2019

An electrochemical detection method for capsaicin has been developed using ionic liquid (IL) doped graphene-titania-Nafion composite-modified electrode. The combination of IL (1-hexyl-3-methylimidazolium with hexafluorophosphate counter ion) in the composite-modified electrode resulted in a significantly increased electrochemical response for capsaicin compared to that obtained at the corresponding electrode without IL. The increased electrochemical signal could be ascribed to the decreased electron transfer resistance through the composite film and also to the effective accumulation of capsaicin on the electrode surface due to ${\pi}-{\pi}$ interaction of the imidazole groups of IL with the aromatic rings of capsaicin. The present IL composite-modified electrode can detect capsaicin with a concentration range from $3.0{\times}10^{-8}M$ to $1.0{\times}10^{-5}M$ with a detection limit of $3.17{\times}10^{-9}M$ (S/N = 3). The present sensor showed good reproducibility (RSD = 3.2%).

• ETRI Journal
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• v.43 no.5
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• pp.923-931
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• 2021

We studied the influence of GaAs top-layer thickness on the small-signal modulation response and 56 Gb/s four-level pulse-amplitude modulation eye quality of 850 nm vertical-cavity surface-emitting lasers (VCSELs). We considered the proportionality of the gain-saturation coefficient to the photon lifetime. The simulation results that employed the transfer-matrix method and laser rate equations led to the conclusion that the proportionality should be considered for proper explanation of the experimental results. From the obtained optical eyes, we could determine an optimum thickness of the GaAs top layer that rendered the best eye quality of VCSEL. We also compared two results: one result with a fixed gain-saturation coefficient and the other that considered the proportionality. The former result with the constant gain-saturation coefficient demonstrated a better eye quality and a wider optimum range of the GaAs top-layer thickness because the resultant higher damping reduced the relaxation oscillation.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.319.1-319
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• 2002

A frequency-domain PES estimation and its prediction method are proposed for the tightly-coupled servo/mechanical design of high-TPI HDD system above 100kTPI. The major two disturbance energies which are related with mechanical vibrations inside of HDD are used to predict the drive-level PES, while considering closed-loop servo dynamics. One is the torque disturbance which mainly comes from aerodynamic excitation of HSA system and the other is the displacement disturbance from disk-spindle dynamics. (omitted)

• Journal of the Korean Institute of Telematics and Electronics
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• v.24 no.3
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• pp.376-380
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• 1987

The closed-loop transfer function of 2-nd order PLL (phase-looked loop)of which loop filter has active-lag 1-st order is found. Considering the three criteria of system performance: the transient response time of the circuit, noise bandwidth by the linear analysis and stability which uses root-locus method, the optimum value of damping factor is 1.0 and the natural frequency which depends upon the signal frequency can be determined after consideration of the trade-off relationship between the transient response time and the noise bandwidth.

• ETRI Journal
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• v.45 no.6
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• pp.974-981
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• 2023

This paper presents a transition-limited pulse-amplitude modulation (TLPAM) signaling method to enable a high data rate and robust wireline communications. TLPAM signaling addresses the impact of high intersymbol interference (ISI) ratios in conventional M-ary PAM signaling methods by limiting the maximum voltage transition level between adjacent symbols. The implementation of a TLPAM signaling encoder is realized by setting back the most significant bits (MSBs) in the queue. The correlation between TLPAM's maximum transition level, effective data rate, and eye width/height is analyzed with various channel loss parameters, followed by characterization and measurement results with a realistic channel setup. The analysis and experimental results reveal the effectiveness of the proposed TLPAM signaling scheme for achieving a high data rate with minimal interference.

• Investigative Magnetic Resonance Imaging
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• v.10 no.2
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• pp.98-107
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• 2006

Magnetization Transfer (MT) imaging generates contrast dependent on the phenomenon of magnetization exchange between free water proton and restricted proton in macromolecules. In biological materials in knee, MT or cross-relaxation is commonly modeled using two spin pools identified by their different T2 relaxation times. Two models for cross-relaxation emphasize the role of proton chemical exchange between protons of water and exchangeable protons on macromolecules, as well as through dipole-dipole interaction between the water and macromolecule protons. The most essential tool in medical image manipulation is the ability to adjust the contrast and intensity. Thus, it is desirable to adjust the contrast and intensity of an image interactively in the real time. The proton density (PD) and T2-weighted SE MR images allow the depiction of knee structures and can demonstrate defects and gross morphologic changes. The PD- and T2-weighted images also show the cartilage internal pathology due to the more intermediate signal of the knee joint in these sequences. Suppression of fat extends the dynamic range of tissue contrast, removes chemical shift artifacts, and decreases motion-related ghost artifacts. Like fat saturation, phase sensitive methods are also based on the difference in precession frequencies of water and fat. In this study, phase sensitive methods look at the phase difference that is accumulated in time as a result of Larmor frequency differences rather than using this difference directly. Although how MT work was given with clinical evidence that leads to quantitative model for MT in tissues, the mathematical formalism used to describe the MT effect applies to explaining to evaluate knee disorder, such as anterior cruciate ligament (ACL) tear and meniscal tear. Calculation of the effect of the effect of the MT saturation is given in the magnetization transfer ratio (MTR) which is a quantitative measure of the relative decrease in signal intensity due to the MT pulse.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.11
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• pp.2147-2159
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• 1994

In this parper, the performance of trellis coded DS/SSMA system using feedforward trellis encoder with sasymmetric signal constellation are evaluated over AW(In channel. The numerical results of trellis coded 4 PSK(code rate 1/2)and 8-PSK(code rate2/3) are calculated for 2-state and 4-state cases and compared with those of the Boudreau's system using feedback trellis encoder without optimizing the signal constellation. The method of moments is employed to evaluate the multiple access interference, in conjunction with the generalized transfer function techniques for trellis code. The numerical results show that the proposed system in this paper is always better than the Boudreau's system over AWGN channel; particularly at $P_b:10$, $0.2dB\sim2.4dB$ improvement over AWGN channel are obtained.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.4
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• pp.739-746
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• 2016

The real-time railway safety monitoring and control system is for prevention of safety accidents, and this system adopts DDS (Data Distribution Service) standard based data transmission method to support integrated management of data from existing on-site safety detection devices. In this paper, we introduce the design of DDS-based data specification from on-site signal equipment on the conventional railway. For this, we (1) design UML data model of KRS SG 0062 standard which defines existing data specification, (2) define DDS Topics for DDS transmission and map KRS model to DDS Topic model, (3) suggest data transformation rules and (4) design network control QoS polices. In addition, we analysis actual on-site log data and validate our data specification design. DDS-based data transmission enables data compatibility among on-site devices and the real-time railway safety monitoring and control system, and allows efficient network management for a large amount of data transfer.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.1
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• pp.220-226
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• 2011

Device of the ECG and pulse signal was made to measure PTT signal using non-invasive method and possible to wearable. PTT alterations were observed according to position change using implemented system.It was needed to ECG and pulse to detect the PTT, used the photoplethymorgraphy appeared to change the blood volume. And also wireless sensor node which was able to Zigbee compatibility was used to transfer the detected ECG and pulse signal to PC. Noise was removed from transit data and algorithm was applied to calculate the PTT. After the evaluation of both the conventional measuring systems and the proposed photoplethymography measuring system, a highly effective and efficient formation and distribution sequences were found within the proposed photoplethymography measuring system.