• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.23 no.3
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• pp.17-28
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• 2024

In this study, the capacity of the tunnel and the general section was calculated and compared using the VDS detector data, and the decrease rate in capacity of the tunnel section was analyzed by tunnel type. To compare the capacity of the tunnel and the general section, the Product Limit Method (PLM) was applied to the VDS detector data. As a result of comparing the capacity of the tunnel and general section, the capacity of the tunnel section decreased by about 6.5% compared to the general section. To classify the tunnel type, the tunnel extension and the number of lanes were used as variables, and there was a difference in the decrease rate of capacity by tunnel group classified by each criterion.

• The Journal of the Acoustical Society of Korea
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• v.37 no.5
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• pp.300-308
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• 2018

The contribution analysis of various external aeroacoustic noise sources to interior noise is important, enabling to design an automobile with a low interior noise level. With a new technique, the CD (Cholesky Decomposition), it is proposed to decompose an overall interior noise spectrum into multiple spectra, each representing the contribution of a specific noise source to the interior noise. In order to validate this method, three kinds of experiments were conducted. Furthermore, it is proposed to improve the CD-based contribution analysis method to be integrated with existing exterior microphone arrays in the wind tunnel. This method was validated with an experiment with two speakers.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.2
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• pp.151.1-151.1
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• 2011

We present the Exposure Time Calculator of IGRINS. The noises of IGRINS can be calculated from the combination of Telluric background emission and absorptions, the emission and transmission of the telescope and instrument optics, and the dark noise and the read noise of the infrared arrays. For the atmospheric transmissions, we apply the simulated spectra depending on the Precipitable Water Vapor (PWV) values. The user needs to input the expected target magnitude, the weather conditions, and the desired exposure time. The output would be the expected signal-to-noise for each spectral resolution element.

• Ocean Systems Engineering
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• v.2 no.2
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• pp.147-158
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• 2012

A time-domain simulation of a land-based Oscillating Water Column (OWC) with various irregular waves as a form of PM spectrum is performed by using a two-dimensional fully nonlinear numerical wave tank (NWT) based on the potential theory, mixed Eulerian-Lagrangian (MEL) approach, and boundary element method. The nonlinear free-surface condition inside the OWC chamber was specially devised to describe both the pneumatic effect of the time-varying pressure and the viscous energy loss due to water column motions. The quadratic models for pneumatic pressure and viscous loss are applied to the air and free surface inside the chamber, and their numerical results are compared with those with equivalent linear ones. Various wave spectra are applied to the OWC system to predict the efficiency of wave-energy take-off for various wave conditions. The cases of regular and irregular waves are also compared.

• Journal of Families and Better Life
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• v.26 no.6
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• pp.143-158
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• 2008

The purpose of the study was to investigate the wife and husband role division in household financial management between dual-income household and single-income household. Household financial management included the following five categories: financial planning, consumption/expenditure management, savings/investment management, risk management and credit management. Data for this research was collected through 610 married women living in Seoul, Korea. Using SAS-PC program, Chi-square and t-test Analyses were executed. The results showed that dual- and single-income households tend to have different perspectives on marital role division in household management. Wives of dual-income households had more significant roles in financial management rather than wives of single income households. Especially, wives of dual-income managed more active credit management and saving/investment management. On the other hand, wives of single-income households played a major role in making decision over cheap items than that of wives of dual-income household.

• Proceedings of the KIEE Conference
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• 2000.11d
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• pp.794-796
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• 2000

This paper analyzes the method of cascading 74LS163 4-Bit Binary Counters. The 74LS163 4-Bit Binary Counter has synchronous LD. CLR functions and especially ENT, ENP, RCO to cascade some chips in order to count more 4bit binary number. The maximum operating frequency may vary according to the method of cascading. The Data sheet from Texas Instruments introduces two methods, The Ripple Carry Mode Circuit and The Carry Look Ahead Circuit, and shows that The Carry Look Ahead Circuit is more efficient than the other. However, there are only little information for user to understand and apply this to other circuits. Thus, we not only analyzed the two methods but also compared with each other in the point of performance.

• Proceedings of the KIEE Conference
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• 2005.04a
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• pp.210-212
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• 2005

최근 급속도로 발전하고 있는 산업분야에서 요구되는 서보 시스템에서 빠른 응답특성, 고도의 정밀성 그리고 안전성에 대한 요구가 커지고 있는 실정이다. 본 논문에서는 이러한 요구에 따라 5상 IPM(Five-phase IPM)의 DTC(Direct torque control)에 대해 고찰하였으며, Texas Instruments사에서 전동기 제어 전용으로 개발된 DSP칩인 TMS320F2812를 이용하여 디지털적으로 제어 알고리즘을 구성하였다. 5상 전동기는 현재 산업현장에서 일반적으로 널리 사용되고 있는 삼상 전동기에 비해 안정성이 높고, 상당 전압의 변화 없이 고정자 전류를 줄일 수 있고, 토크 맥동의 주파수를 높이고 결과적으로 토크의 크기를 감소시킬 수 있다는 여러 가지 장점을 가지고 있으며, 특히 안정성을 요구하는 항공기(Aerospace applications), 전기자동차 및 하이브리드 자동차(Electric or hybrid vehicles)등의 특수한 영역에서 요구가 계속 증가되고 있다. 따라서 본 논문에서는 5상 IPM의 DTC에 대한 특성을 실험을 통하여 확인하였다.

• Journal of the Korean Geotechnical Society
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• v.17 no.3
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• pp.5-13
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• 2001

세립토에서의 세굴깊이의 발달은 일반적으로 조립토에서보다는 아주 천천히 진행된다. 조립토를 위해 개발된 방법을 시간효과와 무관하게 세립토에 적용한다면 세굴깊이가 과대하게 평가된다. SRICOS 방법은 점성토 또는 연암에 설치된 교각의 국부세굴깊이의 변화를 예측하기 위해 개발되었으며, 교량현장에서 채취한 흙에 대한 실험과 SRICOS 프로그램의 수행을 병행함으로써 적용된다. 본 논문에서는 SRICOS 방법을 간단히 설명한 후 프로그램의 세부적인 내용을 기술한다. 또한 이 프로그램을 이용하여 세굴에 미치는 각 매개변수의 영향을 평가하기 위해 실시한 매개변수 해석의 결과가 포함된다.

• Journal of Electrical Engineering and Technology
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• v.13 no.6
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• pp.2301-2309
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• 2018

In a field-oriented vector-controlled permanent magnet synchronous motor (PMSM) control system, the d-axis current control loop can offer a free degree of freedom which can be used to improve control performances. However, in the industry the desired d-axis current command is usually set as zero without using the free degree of freedom. This paper proposes a method to use the degree of freedom for control performance improvement. It is assumed that both the inner loop proportional-integral (PI) current controller and the q-axis outer loop PI speed controller are tuned by the well-known tuning rules. This paper gives an optimal d-axis reference current command generator such that some useful performance indexes are minimized and/or a tradeoff between conflicting performance criteria is made. This paper uses a differential evolution algorithm to autotune the parameter values of the optimal d-axis reference current command generator. This paper implements the proposed control system in real time on a Texas Instruments TMS320F28335 floating-point DSP. This paper also gives experimental results showing the practicality and feasibility of the proposed control system, along with simulation results.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.10
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• pp.1128-1136
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• 2012

In this paper, the states and parameters in a dynamic system are estimated by applying an Unscented Kalman Filter (UKF). The UKF is widely used in various fields such as sensor fusion, trajectory estimation, and learning of Neural Network weights. These estimations are necessary and important in determining the stability of a mobile system, monitoring, and predictions. However, conventional approaches are difficult to estimate based on the experimental data, due to properties of non-linearity and measurement noises. Therefore, in this paper, UKF is applied in estimating the states and parameters needed. An experimental dynamic system has been set up for obtaining data and the experimental data is collected for parameter estimation. The measurement noises are primarily reduced by applying the Low Pass Filter (LPF). Given the simulation results, the estimated error rate is 39 percent more efficient than the results obtained using the Least Square Method (LSM). Secondly, the estimated parameters have an average convergence period of four seconds.