• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.10
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• pp.883-888
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• 2007

Investigation of improving the properties of UV detector which uses the wide bandgap of ZnO are under active progress. The present study focused on the design and fabrication of i-ZnO/p-inversion $layer/n^--Si$ Epi. which is characterized with very thin p-type inversion layer for UV detectors. The i-ZnO thin film for achieving p-inversion layer which was grown by RF sputtering at $450^{\circ}C$ and then annealed at $400^{\circ}C$ in $O_2$ gas for 20 min shows good intrinsic properties. High (0002) peak intensity of the i-ZnO film is shown on XRD spectrum and it is confirmed by XPS analysis that the ratio of Zn : O of the i-ZnO film is nearly 1 : 1. Measurement shows high transmission of 79.5 % in UV range (< 400 nm) for the i-ZnO film. Measurement of $V_r-I_{ph}$ shows high UV photo-current of 1.2 mA under the reverse bias of 30 V.

• IEMEK Journal of Embedded Systems and Applications
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• v.4 no.4
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• pp.195-200
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• 2009

As 4G mobile communication systems require high transmission rates with reliability, the need for efficient error correcting code is increasing. In this paper, a novel LDPC (Low Density Parity Check) decoder is introduced. The LDPC code is one of the most popular error correcting codes. In order to improve performance of the LDPC decoder, we use SNR (Signal-to-Noise Ratio) estimation results to adjust coefficients of modified UMP-BP (Uniformly Most Probable Belief Propagation) algorithm which is one of widely-used LDPC decoding algorithms. An advantage of Modified UMP-BP is that it is amenable to implement in hardware. We generate the optimal values by simulation for various SNRs and coefficients, and the values are stored in a look-up table. The proposed decoder decides coefficients of the modified UMP-BP based on SNR information. The simulation results show that the BER (Bit Error Rate) performance of the proposed LDPC decoder is better than an LDPC decoder using a conventional modified UMP-BP.

• The Journal of the Korea institute of electronic communication sciences
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• v.6 no.1
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• pp.49-54
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• 2011

In this paper, End-to-End VoIP(Voice over Internet Protocol) performance over large scale MANET(Mobile Ad-hoc Networks) is evaluated. VoIP implementation model, which can be used for large scale MANET, is suggested through this evaluation. VoIP simulator based on NS-2 network simulator is used for performance measurement. Call connection ratio as a connection performance, MOS and network delay as a transmission performance, packet loss rate as other performance is measured with this simulation. Finally, maximum $10{\sim}15km^2$ as a single MANET, 500 nodes and 100 call connections is suggested for VoIP implementation and operation conditions over large scale MANETs.

• Proceedings of the KSME Conference
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• 2001.11a
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• pp.834-840
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• 2001

Gear is general mechanical elements that used for power transmission between two shafts that interval is comparatively short. and it delivers big power as accurate ratio of speed. The profile of Spur gear which is the most basic factor is divided into Trochoidal fillet curve and Involute curve. Involute curve is used a lot of a shaped curve of machine parts such as a gear, a scroll compressor and a collar of centrifugal pump. However, It is poor to study the modeling of Trochoidal fillet curve and the three dimensions model shaped mathematical curve. This paper describes a mathematical model of profile shifted involute gear. and this model is based on Camus's theory. We draw three dimensions gear have accurate mathematical function using ADS, VisualLISP. and To check accuracy and perfection, we make a program of checking Interference. and use for this study.

• Journal of Mechanical Science and Technology
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• v.14 no.4
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• pp.408-417
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• 2000

The design and simulation of meshing of a single enveloping worm-gear drive with modified surfaces is presented. Generally worm-gear is generated by the hob which is identical to the worm. This process guarantees the conjugation between the worm and the gear but results in a line contact at every instant which is very sensitive to misalignment. The localization of bearing contact is necessary to reduce the sensitivity of the worm-gear drive to misalignment. Practically this localization is achieved by application of an oversized worm type hob to cut the worm-gear. The oversized hob approach is very practical and effective to localize bearing contact but can not provide the conjugation between the worm and the modified worm-gear. This work proposes an analytical procedure to make the worm surface conjugate to the worm-gear which is cut by the oversized hob. The developed computer program allows the investigation of the influence of misalignment on the shift of the bearing contact and the determination of the transmission errors, the contact ratio and the principle curvatures. The developed approach has been applied for ZK type of single-enveloping worm-gear drives and the developed theory is illustrated with a numerical example.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.24 no.2
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• pp.203-210
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• 2015

This paper investigates the failure of a car with a 2.5-liter CRDi engine of the Hyundai Company. The failure is caused by intermittent poor acceleration while driving. To analyze the cause, we investigated the air intake volume, the fuel injection, and the air-fuel ratio, which were determined to be normal. The brake switch signal error was discovered while analyzing the function that limits the output of the engine. While investigating the cause, we discovered the corrosion of the pins on the connector of the brake switch. We determined that it was generated by soapy water flowing in the solar film. Therefore, the cause of the failure was the brake switch signal errors. Additionally, we determined that ECM was the normal fail-safe mode that implemented the override device for safety during normal acceleration. Based on these results, further solar film experiments must be conducted to fully elucidate the causes.

• Smart Structures and Systems
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• v.22 no.2
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• pp.167-174
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• 2018

Digital input and output modules are widely used to connect digital sensors and actuators to automation systems. Digital I/O modules provide flexible connectivity extension to numerous sensors and actuators and protect systems from high voltages and currents by isolation. Components in digital I/O modules are inevitably affected by operating and environmental conditions, such as high voltage, high current, high temperature, and temperature cycling. Because digital I/O modules transfer signals or isolate the systems from unexpected voltage and current transients, their failures may result in signal transmission failures and damages to sensitive circuitry leading to system malfunction and system shutdown. In this study, the lifetime of optocouplers, one of the critical components in digital I/O modules, was predicted using Bayesian tracking approaches. Accelerated degradation tests were conducted for collecting the critical performance parameter of optocouplers, current transfer ratio (CTR), during their lifetime. Bayesian tracking approaches, including extended Kalman filter and particle filter, were applied to predict the failure. The performance of each prognostic algorithm was then compared using accuracy and robustness-based performance metrics.

• IEMEK Journal of Embedded Systems and Applications
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• v.15 no.5
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• pp.205-214
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• 2020

With the recent development of hardware and software technology, interest in the development of wearable devices is increasing. In particular, wearable devices require algorithms suitable for low-power and low-capacity embedded devices. Among them, there is an increasing demand for a signal compression algorithm that reduces communication overhead, in order to increase the efficiency of storage and transmission of electrocardiogram (ECG) signals requiring long-time measurement. Because normal beats occupy most of the signal with similar shapes, a high rate of signal compression is possible if normal beats are represented by a template. In this paper, we propose an algorithm for determining the normal beat template using the template cluster and Pearson similarity. Also, the template is expressed effectively as a few vertices through linear approximation algorithm. In experiment of Datum 234 of MIT-BIH arrhythmia database (MIT-BIH ADB) provided by Physionet, a compression ratio was 33.44:1, and an average distribution of root mean square error (RMSE) was 1.55%.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.4
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• pp.75-82
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• 2004

The channel transmission ratio is speeded up by the combination of the Huffman algorithm, the model scheme of the lossy transform having minimum average code lengths for the image information and good instantaneous decoding capability, with the Lempel-Ziv algorithm showing the fast processing performance during the compression process. In order to increase the processing speed during the compression process, ICMEP algorithm is proposed and the entropy encoder of HDTV is designed and inspected. The ICMEP entropy encoder have been designed by choosing the top-down method and consisted of the source codes and the test benches by the behavior expression with VHDL. As a simulation results, implemented ICMEP entropy encoder confirmed that whole system efficiency by memory saturation prevention and compressibility increase improves.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2006.04a
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• pp.615-622
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• 2006

As construction technique and design are developing, the bridge tend to be longer, and also the type of bridge is verity. Steel and concrete combination improve the mechanics characteristic and economical efficient which Hybrid Structure divide Mixed Structure with Composite Structure. The connected section of the Mixed Structure should integrate steel and concrete that should show the same behavior as well, And also this connection needs big interna1 force and stiffness because it used to be a most dangerous section. This study carry out a nonlinear analysis technique with slip, check out each different type of section force's transfer mechanism on the connection. And this analysis was carried out using parameter that are front plate thickness, connection length, filled concrete strength and so on. We confirmed the profitable type of connection is front backward type. The biggest stiffness and certain stress transmission are showed at the ratio 0.075 between total length and connection length, and also most economical front plate thickness is judged when it set three times thicker than flange.