• Geophysics and Geophysical Exploration
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• v.11 no.4
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• pp.361-367
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• 2008

When constructing a synthetic seismogram in the earthquake study or in seismic data interpretation by using a ray-tracing technique, the most troublesome and error-prone task is to define a suite of ray codes for the corresponding rays to trace in advance. An infinite number of rays exist for any arbitrarily located source and receiver in a medium. Missing certain important rays or an inappropriate selection of ray codes in tracing rays may result in wrong interpretation of the earthquake record or seismogram. Automatic ray code generation could be able to eliminate those problems. In this study we have developed an efficient algorithm with which one can generate systematically all the ray codes for the source(s) and receiver(s) arbitrarily located in a model. The result of this work could be used not only in analysing multiples in seismic data processing and interpretation, but also in coda wave study, study on the amplification effects in a basin and phase identification of the waves multiply reflected/refracted in earthquake study.

• Journal of the Earthquake Engineering Society of Korea
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• v.12 no.2
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• pp.69-80
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• 2008

In this study, improved capacity spectrum method (CSM) is proposed. The method can account for higher mode contribution to the seismic response of MDOF systems. The CSM has been conveniently used for determining maximum roof displacement using both demand spectrum and capacity curve of equivalent SDOF system. Unlike the conventional CSM, the maximum roof displacement is determined without iteration using inelastic displacement ratio and R factor calculated from demand spectrum and capacity curve. Three moment resisting steel frames of 3-, 9- and 20-stories are considered to test the accuracy of the proposed method. Nonlinear response history analysis (NL-RHA) for three frames is also conducted, which is considered as an exact solution. SAC LA 10/50 and 2/50 sets of ground motions are used. Moreover, this study estimates maximum story drift ratios (IDR) using ATC-40 CSM and N2-method and compared with those from the proposed method and NL-RHA. It shows that the proposed CSM estimates the maximum IDR accurately better than the previous methods.

• Journal of Advanced Marine Engineering and Technology
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• v.33 no.8
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• pp.1254-1260
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• 2009

CDMA tele-Controller system is designed with a low power consumption 8 bit microcontroller, ATmega 2560. ATmega 2560 microcontroller consists of 4 UART (Universal asynchronous receiver/transmitter) ports, 4 kbytes EEPROM, 256 kbytes flash memory, 4 kbytes SRAM. 4 URAT is used for CDMA modem, communication for GPS module, EEPROM is used for saving a configuration for program running, a flash memory of 256 kbytes is used for storing a F/W(Firm Ware), and SRAM is used for stack, storing memory of global variables while program running. We have tested the communication distance between the coast station and sea by the fabricated control board using 800 MHz CDMA modem and GPS module, which is building for the navigational aid management system by remote control. As a results, the receiving signal strength is above -80 dBm, and then the characteristics of the control board implemented more than 10 km in the distance of the communication.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.9
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• pp.831-837
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• 2015

Many persons and electronic devices are exposed to electromagnetic (EM) waves generated from magnetic resonance imaging (MRI) equipment, EM pulses (EMPs), and many other kinds of EM wave devices. Finger strips are used to provide shielding from these EM waves. Because of the high thermal conductivity of finger strips, they are used in the design of specialized doors that are installed in shielded rooms. In this study, we perform an accelerated life test using the load acceleration stress, which affects the main failure mode of finger strips. We predict the life of the finger strip under normal usage conditions based on the results of the accelerated life test. We compare the results with those predicted from the life test under normal usage conditions to evaluate the validity of accelerated life testing.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.777-780
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• 2005

모바일 오디오 적용을 위한 저전력 ${\Sigma}{\Delta}$ Modulator 에 대한 설계와 layout 을 보였다. 전체 구조는 3 차 단일 피드백 루프이며, 해상도는 16bit 을 갖는다. 샘플링 주파수에 따른 Over-sampling Ratio 는 128(46kHz) 또는 64(96kHz) 가 되도록 하였다. 차동 구조를 사용한 3 차 ${\Sigma}{\Delta}$ modulator 내의 적분기에 사용된 Op-Amp 는 DC-Gain 을 높이기 위해서 Gain-boosting 기법이 적용되었다. ${\Sigma}{\Delta}$ modulator 의 기준 전압은 전류 모드 Band-Gap Reference 회로에서 공급이 되며, PVT(Process, Voltage, Temperature) 변화에 따른 기준 전압의 편차를 보정하기 위하여, binary 3bit 으로 선택하도록 하였다. DAC 에서 사용되는 단위 커패시터의 mismatch 에 의한 성능 감소를 막기 위해, DAC 신호의 경로를 임의적으로 바꿔주는 scrambler 회로를 이용하였다. 4bit Quantizer 내부의 비교기 회로는 고해상도를 갖도록 설계하였고, 16bit thermometer code 에서 4bit binary code 변환시 발생하는 에러를 줄이기 위해 thermometer-to-gray, gray-to-binary 인코딩 방법을 적용하였다. 0.18um CMOS standard logic 공정 내 thick oxide transistor(3.3V supply) 공정을 이용하였다. 입력 전압 범위는 2.2Vp-p,diff. 이며, Typical process, 3.3V supply, 50' C 시뮬레이션 조건에서 2Vpp,diff. 20kHz sine wave 를 입력으로 할 때 SNR 110dB, THD 는 -95dB 이상의 성능을 보였고, 전류 소모는 6.67mA 이다. 또한 전체 layout 크기는 가로 1100um, 세로 840um 이다.

• Journal of IKEEE
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• v.8 no.2 s.15
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• pp.172-180
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• 2004

In this paper, a parallel Input/Output modulo multiplier, which is applied to AOTP(All One or Two Polynomials) multiplicative algorithm over $GF(3^m)$, has been proposed using neuron-MOS Down-literal circuit on voltage mode. The three-valued input of the proposed multiplier is modulated by using neuron-MOS Down-literal circuit and the multiplication and Addition gates are implemented by the selecting of the three-valued input signals transformed by the module. The proposed circuits are simulated with the electrical parameter of a standard $0.35{\mu}m$CMOS N-well doubly-poly four-metal technology and a single +3V supply voltage. In the simulation result, the multiplier shows 4 uW power consumption and 3 MHzsampling rate and maintains output voltage level in ${\pm}0.1V$.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.39 no.6
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• pp.652-663
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• 2002

Recently, many advanced video application services over the mobile wireless networks have required a transcoder which can efficiently reduce the size of compressed video bitstreams. The transcoder can be worked in either the spatial domain or the DCT domain. In this paper, we propose a new fast hybrid-type transcoder which can efficiently reduce the frame size with keeping the visual quality. The proposed scheme consists of two major processes: a transform domain process and a spatial domain process. We also propose a scheme for coding mode selection and motion vector refinement. Experimental results show that our approach can reduce the computational complexity more than any other conventional spatial-domain transcoder with keeping the visual quality.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.1
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• pp.11-18
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• 2010

Tool condition monitoring (TCM) is crucial for improvement of productivity in manufacturing process. However, TCM techniques have not been applied to monitor tool failure in an industrial gear shaving application. Therefore, this work studied a statistical TCM method for monitoring gear shaving tool condition. The method modeled the vibration signal of the shaving process using beta probability distribution in order to extract the effective features for TCM. Modeling includes rectifying for converting a bi-modal distribution into a unimodal distribution, estimating the parameters of beta probability distribution based on method of moments. The performance of features obtained from the proposed method was evaluated and discussed.

• Journal of Advanced Navigation Technology
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• v.17 no.1
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• pp.98-106
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• 2013

In this paper, we propose a moving object detection and tracking method for multi-view camera environment. Based on the similarity and characteristics of motion vectors and coding block modes extracted from compressed bitstreams, validation of moving blocks, labeling of the validated blocks, and merging of neighboring blobs are performed. To continuously track objects for temporary stop, crossing, and overlapping events, a window based object updating algorithm is proposed for single- and multi-view environments. Object detection and tracking could be performed with an acceptable level of performance without decoding of video bitstreams for normal, temporary stop, crossing, and overlapping cases. The rates of detection and tracking are over 89% and 84% in multi-view environment, respectively. The rates for multi-view environment are improved by 6% and 7% compared to those of single-view environment.

• KIISE Transactions on Computing Practices
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• v.22 no.10
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• pp.497-503
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• 2016

Emerging next-generation storage technologies such as non-volatile memory will help eliminate almost all of the storage latency that has plagued previous storage devices. In conventional storage systems, the latency of slow storage devices dominates access latency; hence, software efficiency is not critical. With low-latency storage, software costs can quickly dominate memory latency. Hence, researchers have proposed the memory mapped file I/O to avoid the software overhead. Mapping a file into the user memory space enables users to access the file directly. Therefore, it is possible to avoid the complicated I/O stack. This minimizes the number of user/kernel mode switchings. In addition, there is no data copy between kernel and user areas. Despite of the benefits in the memory mapped file I/O, its overhead still needs to be addressed, as the existing mechanism for the memory mapped file I/O is designed for slow block devices. In this paper, we identify the overheads of the memory mapped file I/O via experiments.