• Journal of the Optical Society of Korea
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• v.13 no.3
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• pp.361-366
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• 2009

We propose the performance enhancing method optimization of an asynchronous 2.5 Gbps/1.25 Gbps optical subscriber network with inverse RZ (Return to Zero) coded downstream and NRZ (Non Return to Zero) upstream re-modulation by adjusting threshold level control of a receiver. We theoretically analyze the BER (Bit Error Rate) performance by modeling the occurrence of BER by simulation with MATLAB according to the types of downstream data. The results have shown that the normalized threshold level in an optical receiver could be saturated at 1/3 as the SNR (Signal to Noise Ratio) increases. The needed SNR for obtaining the BER $10^{-9}$ can be reduced by $\sim$5 dB by optimizing the normalized threshold level at 1/3 instead of by using the conventional receiver with threshold level of 0.5. The proposed system can be a useful technology for asynchronous optical access networks with asymmetric upstream and downstream data rates, because the improved minimum receiving power could replace a light source with a source with lower power and lower cost in an OLT (Optical Line Termination).

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.2
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• pp.347-354
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• 2011

This paper presents a time-domain based asynchronous IR-UWB ranging system. This system accomplishes the ranging by detecting peaks from the outputs of a correlator implemented by a FIR filter. To discriminate the peaks due to a signal component, we use windowing for the correlated data within which the data are sorted in amplitude-ascending order and the noise level is calculated. Comparing with the recently presented frequency-domain based ranging system, we show the system structure and explain how it operates for ranging. Moreover, through the simulations, the proposed system is compared with the frequency-domain based system in terms of performance.

• Journal of Information Technology Services
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• v.21 no.3
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• pp.73-87
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• 2022

As the COVID-19 pandemic continues to prolong, non face-to-face, online classes has become the new normal in education. To examine the effect of course types and course delivery modes on student course satisfaction, the study analyzed survey data collected from 2,743 students enrolled in a 4-year university located in a metropolitan area. Basic Frequency analysis as well as keyword network analysis were used to analyze student survey data. The main results and implications of the study are as follows. First, the survey results indicated that students preferred asynchronous classes over synchronous online classes. This tendency was consistent regardless of student grades and majors as well as the course type. However, students majoring in more practice-oriented disciplines tend to prefer synchronous online classes and blended classes, and this tendency gets stronger with courses in major. Second, the keyword network analysis results further indicated that interactivity may play an important role in both synchronous and asynchronous online course satisfaction.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.79.6-79
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• 2002

We propose here sequential 2 methods for obtain information of current or potential data for power transmission line. One is a digital data transmission unit, this is, an output of a current sensor of power transmission line is digitalized by use of an easy asynchronous protocol. The unit has high speed transform rate, easy making header caused of consisting of only logic circuit. The other is, the output of the unit is transformed via LAN interface and displayed on a personal computer. We have confirmed remote measuring using the method for 100A and 240 A of the current information of power transmission line. Therefore we will be able to see a current waveform by use of internet at a cheep c...

• Bulletin of the Korean Chemical Society
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• v.24 no.9
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• pp.1345-1350
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• 2003

Principal component analysis based two-dimensional (PCA-2D) correlation analysis is applied to FTIR spectra of polystyrene/methyl ethyl ketone/toluene solution mixture during the solvent evaporation. Substantial amount of artificial noise were added to the experimental data to demonstrate the practical noise-suppressing benefit of PCA-2D technique. 2D correlation analysis of the reconstructed data matrix from PCA loading vectors and scores successfully extracted only the most important features of synchronicity and asynchronicity without interference from noise or insignificant minor components. 2D correlation spectra constructed with only one principal component yield strictly synchronous response with no discernible a asynchronous features, while those involving at least two or more principal components generated meaningful asynchronous 2D correlation spectra. Deliberate manipulation of the rank of the reconstructed data matrix, by choosing the appropriate number and type of PCs, yields potentially more refined 2D correlation spectra.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.2
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• pp.45-50
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• 2017

Micro-service Architecture is a service architecture optimized for large-scale distributed systems such as real-time realistic broadcasting systems, so that are fiercely adopted by Global leading service platform vendors such as Netflix and Twitter due to the merit of horizontal performance scalability enabling the scale-out technique. In addition, micro-service architecture makes it possible to execute image processing and real-time data analysis using an asynchronous-based processing that are difficult to handle in Web API such as REST. In this paper, an event stream processing framework applicable to asynchronous based micro services is proposed in the sense that the accountability of event processing order is not guaranteed in the events such as IoT sensor data analysis or cloud-based image editing because these are the situations where the real-time media editing generates multiple event streams and asynchronous processes in the platform.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.5
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• pp.950-956
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• 2015

In this paper, a WiMedia Distributed-MAC (D-MAC) protocol is adopted for development of a seamless N-screen wireless service in Indoor and Ship Area Networks. Furthermore, to provide the OSMU (One Source Multi Use) N-screen service through P2P streaming in the seamless D-MAC protocol, a ATMT (Asynchronous Traffic Multi-hop Transmission) technology is proposed and analyzed. In this system, a WiMedia ATMT D-MAC bridge transmits control and managing information to various sensors and instruments, from a central integrated ship area network station. For this technology, a time slot allocation scheme for WiMedia asynchronous traffic and a multi-hop resource reservation scheme are combined to evaluate the performance of each scheme. From simulation results, the proposed ATMT scheme enhances performances in viewpoints of N-screen asynchronous data latency and throughput, compared to the conventional WiMedia D-MAC system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.9
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• pp.3563-3570
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• 2010

MAC protocol has been studied for reducing energy consumption in wireless sensor networks. The overhearing and idle In the existing asynchronous MAC Protocol will occur due to unnecessary energy consumption. In this paper, to solve these problems, the Preamble to change the structure of the destination address, the Preamble of the end times, the data including the length of the Preamble and Data Overhearing reduce the length of the Check Interval Data generated according to the presence of the Dynamic Value dynamically adjustable by changing the DPL (Dynamic Preamble Length)-MAC protocol was proposed. Moreover, the existing asynchronous MAC protocol of wireless sensor networks and DPL-MAC protocol proposed in this paper to simulate the energy consumption and latency were assessed in terms of comparative analysis.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.5
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• pp.71-81
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• 2008

In this paper, we propose a novel Globally Asynchronous, Locally Dynamic System(GALDS) bus and demonstrate its performance. The proposed GALDS bus is the bidirectional multitasking bus with the segmented bus architecture supporting the concurrent operation of multi-masters and multi-slaves. By analyzing system tasks, the bus architecture chooses the optimal frequency for each If among multiples of bus frequency and thus we can reduce the overall power consumption. For efficient data communications between IPs operating in different frequencies, we designed an asynchronous and bidirectional FIFO based on an asynchronous wrapper with hand-shaking interface. In addition, since systems can be easily expandable by inserting bus segments, the proposed architecture has advantages in IP reusability and structural flexibility As a test example, a four-segment bus haying four masters and four slaves were designed by using Verilog HDL. We demonstrate multitasking operations with read/write data transfers by simulation when the ratios of operation frequency are 1:1, 1:2, 1:4 and 1:8. The data transfer mode is a 16 burst increment mode compatible with Advanced Microcontroller Bus Architecture(AMBA). The maximum operation latency of the proposed GALDS bus is 22 clock cycles for the bus write operation, and 44 clock cycles for read.

• IE interfaces
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• v.20 no.3
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• pp.288-297
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• 2007

Success of semiconductor/LCD industry depends on its yield and quality of product. For the purpose, FDC (Fault Detection and Classification) system is used to diagnose fault state in main manufacturing processes by monitoring time series data collected by equipment sensors which represent various conditions of the equipment. The data set is segmented at the start and end of each product lot processing by a trigger event module. However, in practice, segmented sensor data usually have the features of data asynchronization such as different start points, end points, and data lengths. Due to the asynchronization problem, false alarm (type I error) and missed alarm (type II error) occur frequently. In this paper, we propose a robust process fault detection system by integrating a process event detection method and a similarity measuring method based on dynamic time warping algorithm. An experiment shows that the proposed system is able to recognize abnormal condition correctly under the asynchronous data situation.