• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.12
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• pp.2518-2524
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• 2009

This paper presents the backplane effects due to a rectangular aperture size for two-wire transmission line with equal line length crossing the changeable rectangular aperture in an infinite ground backplane. It is used to determine the characteristics of the backplane insertion loss of the transmission line from the load section in accordance with the backplane aperture size. The results show that the insertion gain and insertion loss are obtained for the specific frequency range when the transmission line is closed to the backplane aperture size. The insertion loss is decreased that the aperture horizontal length and vertical length is more than a=50 mm and b=20 mm. The measurements of insertion loss are performed to verify the theoretical analysis.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.12 no.5
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• pp.499-506
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• 2019

This paper is concerned with the operating stability of 7kW inverter using SIC hybrid module and verifies the validity of the simulation results by comparing the result of the loss equation and the simulation result, Simulation results using Si module and SiC hybrid module are compared to compare switch loss and diode loss. Through the loss equation calculation, the conduction loss of SiC Hybrid module is 168W, switching loss is 9.3W, diode loss is 10.5nW, When compared with the simulation results, similar values were shown. As a result of comparing the simulation results of the Si module and the SiC Hybrid module, The total device loss of the Si module was 246.2W, and the total device loss of the SiC Hybrid module was 189.9W. The loss difference was 56.3W, which was about 0.8W. thereby verifying the reverse recovery characteristics of the SiC SBD. In addition, temperature saturation test was conducted to confirm the stability of SiC Hybrid module and Si module under high temperature saturation, In the case of the Si module, the output power was stopped at 4kW, and the SiC Hybrid module was confirmed to operate at 7kW. Based on this, an efficiency graph and a temperature graph are presented, and the Si module is graphed up to 4kW and the SiC Hybrid module is graphed up to 7kW.

• The Journal of Korean Institute of Next Generation Computing
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• v.13 no.2
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• pp.18-25
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• 2017

In computer science, an encoding is a standardization of converting information to one format for audio, video or text. Therefore, the encoding information of the data should be known to open and read it and there are algorithms detecting encoder of the data. However, some informations of data could be disappeared by packet loss when transmitted on network, especially, if the data is snatched by packet sniffing or eavesdropping from wireless communications. In this paper, we improve the performance of encoding detection algorithm of 'uchardet' program for multi-byte encoded data with errors based on bit-shift algorithm. To simulate the performance, we generated Korean and Japanese text data with errors that is removed some random bits at random positions. Then the detection algorithm are tested using the data and 'uchardet-bitshift' showed better performance than 'uchardet'. When Korean texts are used, 'uchardet' could detect perfectly with ≤0.005% errors but it showed 0% detection rate with ≥1% errors while 'uchardet-bitshift' detected perfectly with ≤0.05% errors and it showed correct detection cases with ≥1% errors. Japanese texts with errors tend to report falsely as Chinese encoding because Japanese texts include lots of Chinese characters. As a results, we improved encoding detection algorithms by applying bit shift operation.

• Journal of the Korean Data and Information Science Society
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• v.20 no.4
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• pp.705-712
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• 2009

Histogram is the oldest and most widely used density estimator for presentation and exploration of observed univariate data. The structure of a histogram really depends on the number of bins and the width of the bins, so that slight changes on bins can produce totally different shape of a histogram. In order to solve this problem the fuzzy histogram was introduced and the result was good enough (Loquin and Strauss, 2008). In particular, when estimating loss distribution related with operational risk a histogram has been widely used. In this article, instead of an ordinary histogram we try to use a fuzzy histogram for estimating loss distribution and show that a fuzzy histogram provide more stable results.

• The KIPS Transactions:PartC
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• v.13C no.5 s.108
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• pp.635-640
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• 2006

The Snoop in the BS (Base Station) performs a local retransmission over wired-wireless networks to recover packet loss quickly. However, when the MH (Mobile Host) leaves the reception range of the signal, the local retransmission causes performance to degrade. In this paper, we minimize the packet loss and local retransmission caused by the unreachability from BS to MH to improve network performance. To do this, we suggest to add RSS(Received Signal Strengths) flag bit in ACK packet of MH. By using this flag bit, the BS decides whether it retransmits or not to minimize packet loss. The result of the simulation by ns-2 shows a big improvement of performance in the networks.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.4 no.3
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• pp.565-573
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• 2000

In this paper, a interdigital microstrip bandpass filter is designed. A interdigital microstrip bandpass filter has many advantages such as insertion return loss, lower return loss, higher frequency selectivity and smaller in size in comparison with the conventional coupled line filter. A interdigital microstrip bandpass filter consists of quasi TEM-mode strip line resonators between parallel ground plant. Each resonator element is a quarter wavelength long of the center frequency and is short circuited at one end and open circuited at the other end. In the filter design, Ensemble software is used. Experimental results show that the bandwidth of interdigital microstrip bandpass filter is 2.52GHz, insertion loss is -1.8dB and return loss is -17.0dB at 11.20Hz.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.2 no.4
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• pp.583-592
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• 1998

In this paper, the cell loss rate is analyzed in terms of the input traffic stream of different speed in ATM network. The cell loss rate is calculated by birth-death process of Leaky-Bucket mechanism as the representative algorithm of usage parameter control. The cell loss rate assumed 2-state MMPP input process to be birth-death process by considering the character of token pool about finite capacity queue. The results from numerical analysis show that the cell loss rate decreases abruptly according to the buffer size increase. The computer simulation by SIMSCRIPT II.5 has been done and compared with on/off input source case to verify the analysis results.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.6
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• pp.1327-1332
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• 2015

In this paper, we studied several aspects that affect the quality of VoIP using WiFi network. It's clear that the background data traffic within an AP, the end-to-end delay and the traffic loss of TCP/IP network gives serious effects on the voice quality. A kind of access control for the VoIP connection within an AP should be done for the acceptable voice quality.

• 한국정보통신설비학회:학술대회논문집
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• 2006.08a
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• pp.105-110
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• 2006

The most sensitive part of the installed optical cable is the optical loss variation of the splicing point according to the environmental changes. This paper presents the details of the experimental results of the external environmental changes on optical loss, such as bending, temperature variation, temperature variation after water osmosis and variation. Through the bending test of optical fiber, rapid increase of optical loss was measured within the diameter of 30mm. The result of optical loss variation within the temperature range of $-30^{\circ}C{\sim}60^{\circ}C$ is less than 0.02dB. It was confirmed that the maximum optical loss increased up to 0.2dB in case of water osmosis within the temperature range of $-40^{\circ}C{\sim}80^{\circ}C$. There is small optical loss variation of 0.01dB under the 1mm vibration test. The experimental results of this paper can be used as the reference data for the design of the optical fiber cable splicing enclosure to protect the optical loss variation due to environmental changes.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.10a
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• pp.632-635
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• 2008

In this paper, a diplexer circuit to separate GSM/CDMA band is designed using a LTCC (Low Temperature Cofired Ceramic) multi-layer technology. In order to increase a integration capability of the diplexer, it is designed in 6-layer LTCC sunstrate with a elative dielectric constant of 7.2 using 3-dimensional (3-D) multi-layer inductors and capacitors. The size of the designed diplexer including CB-CPW pads is $3,450{\times}4,000{\times}600{\mu}m^3$. An insertion loss (IL) and return loss of GSM band are less than -0.23dB and -10dB, respectively. In the case of CDMA band, the IL of -0.53dB and RL of below -10dB are archieved.