• Structural Engineering and Mechanics
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• v.31 no.2
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• pp.211-223
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• 2009

Transient response analysis can be conducted either in the time domain, or via the frequency domain. Sometimes a frequency domain method (FDM) has advantages over a time domain method. A practical issue in the FDM is to find out an appropriate extended period, which may be affected by several factors, such as the excitation duration, the system damping, the artificial damping, the period of interest, etc. In this report, the extended period of the FDM based on the Duhamel's integral is investigated. This Duhamel's integral based FDM does not involve the unit impulse response function (UIRF) beyond the period of interest. Due to this fact, the ever-lasting UIRF can be simply set as zero beyond the period of interest to shorten the extended period. As a result, the preferred extended period is the summation of the period of interest and the excitation duration. This conclusion is validated by numerical examples. If the extended period is too short, then the front portion of the period of interest is more prone to errors than the rear portion, but the free vibration segment is free of the wraparound error.

• The Journal of Asian Finance, Economics and Business
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• v.8 no.4
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• pp.113-124
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• 2021

The study investigates how financial markets respond to a shock to tone and semantic similarity of the Bank of Thailand press releases. The techniques in natural language processing are employed to quantify the tone and the semantic similarity of 69 press releases from 2010 to 2018. The corpus of the press releases is accessible to the general public. Stock market returns and bond yields are measured by logged return on SET50 and short-term and long-term government bonds, respectively. Data are daily from January 4, 2010, to August 8, 2019. The study uses the Structural Vector Auto Regressive model (SVAR) to analyze the effects of unanticipated and temporary shocks to the tone and the semantic similarity on bond yields and stock market returns. Impulse response functions are also constructed for the analysis. The results show that 1-month, 3-month, 6-month and 1-year bond yields significantly increase in response to a positive shock to the tone of press releases and 1-month, 3-month, 6-month, 1-year and 25-year bond yields significantly increase in response to a positive shock to the semantic similarity. Interestingly, stock market returns obtained from the SET50 index insignificantly respond to the shocks from the tone and the semantic similarity of the press releases.

• Asia-Pacific Journal of Business
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• v.15 no.2
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• pp.223-236
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• 2024

Purpose - The purpose of the paper is to empirically investigate the asymmetric adjustment of loan and deposit interest rates among banks and non-bank depository institutions. Design/methodology/approach - We construct a VAR model using time series data comprising loan and deposit interest rates of banks and non-bank depository institutions, along with the call rate. Based on this model, we conduct impulse-response analysis and variance decomposition to investigate the dynamic relationship between the interest rates. Findings - In the case of banks and credit unions, the responses of deposit rates to the call rate are larger than the responses of loan rates, and we cannot find evidence of non-linear responses. In the case of savings banks, the responses of loan rates to the call rate are larger than the responses of deposit rates. The responses of loan rates to a positive call rate shock are statistically significant, while the responses of loan rates to a negative call rate shock are not statistically significant. Research implications or Originality - This study differs from previous research in that it examines the asymmetric response of loan and deposit rates of both banks and non-bank financial institutions to changes in the call rate. The implications for the impact of these findings on the financial system and income inequality are presented.

• Journal of Labour Economics
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• v.21 no.2
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• pp.17-46
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• 1998

In this paper, I pursue an empirical analysis of different patterns of employment and wage adjustments to demand changes for the US and Japan. Analyzed are the data in the 70's and 80's, the period that the two countries are believed to show most conspicuous diverging patterns. Using the framework of cointegration and error correction, I establish that in the US it is employment level, while in Japan it is wages, that is more responsive to output fluctuations both in the long run and the short run. All the comparisons on the long run relationships are estimated and tested based on the system cointegrating regressions, and the transition from the short run to the long run responses are investigated using impulse response analysis of the error correction models. I also study differences across genders and establishment sizes within each country. For males and females in Japan, the adjustments are significantly different both in the long run and the short run, but for the firms of different sizes they diverge only in the short run. In contrast to some of the earlier work, the gender effect turns out to be insignificant in the US.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.32B no.1
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• pp.96-102
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• 1995

This paper presents the VHSIC Hardware Description Language(VHDL) implementation of the Fixed Point Covariance Lattice(FLAT) algorithm for an Linear Predictive Coding(LPC) analysis and its related algorithms, such as the forth order high pass Infinite Impulse Response(IIR) filter, covariance matrix calculation, and Spectral Smoothing Technique(SST) in the Vector Sum Exited Linear Predictive(VSELP) speech coder that has been Selected as the standard speech coder for the North America and Japanese digital cellular. Existing Digital Signal Processor(DSP) chips used in digital cellular phones are derived from general purpose DSP chips, and thus, these DSP chips may not be optimal and effective architectures are to be designed for the above mentioned algorithms. Then we implemented the VHDL code based on the C code, Finally, we verified that VHDL results are the same as C code results for real speech data. The implemented VHDL code can be used for performing logic synthesis and for designing an LPC Application Specific Integrated Circuit(ASOC) chip and DsP chips. We first developed the C language code to investigate the correctness of algorithms and to compare C code results with VHDL code results block by block.

• The Journal of the Acoustical Society of Korea
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• v.17 no.2
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• pp.25-31
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• 1998

본 연구에서는 자동차 유리판에 초음파 대역 진동을 효율적으로 발생시킬 수 있는 압전 액츄에이터를 개발하고자 하였다. 자동차 유리판을 단순지지 평판으로 가정하였으며, 액츄에이터로는 PZT 진동자를 사용하였다. 유한 요소법(Finite Element Method)을 통하여 유리판의 최적 공진 주파수와 유리판에 부착할 압전 진동자의 구조 조건인 최적 위치와 개 수를 결정하였다. 설계 결과에 따라 자동차 유리판에 압전 진동자를 부착하여 임펄스 응답 해석(impulse response analysis)과 임피던스 해석(impedance analysis)을 수행하여 구동 주 파수를 확인하였다. 그 결과, 이 주파수로 가진하여 유리판 전면에 걸쳐 고른 초음파 진동이 분포함을 확인하였으며, 나아가 전기적 임피던스 매칭(impedance matching)을 통해 더 큰 효율의 진동을 발생시킬 수 있었다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.688-693
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• 2002

Identification method is formulated to evaluate the dynamic characteristics of air bearings under NFR(Near Field Recording) sliders. Impulse responses and frequency response functions of NFR sliders are obtained on numerical non-linear models including rigid motion of slider and fluid motion of air bearing under the slider. Modal parameters and system parameters are identified by modal analysis method and instrumental variable method. The parameters of sliders are utilized to evaluate the dynamic characteristics of air bearings. Also, this study shows the difference between the dynamic characteristics of NFR and HDD slides, and squeeze effect of air bearings.

• KDI Journal of Economic Policy
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• v.24 no.1
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• pp.3-44
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• 2002

This study attempts to explain why traditionally pro-cyclical trade balance became counter-cyclical since early 1990's in Korea. Structural VAR analysis for two sub-periods reveals two interesting changes in the role of the supply shock. First, impulse response analysis shows that the conditional correlation between the supply shock and trade balance turned from positive to negative over the two sub-periods. Second, the relative importance of the supply shock increased over the sub-periods. These two factors together explain the change in the cyclical properties of trade balance over time. Underlying cause behind these changes is likely to be the trade and financial market liberalization since late 1980's.

• East Asian Economic Review
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• v.22 no.2
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• pp.141-176
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• 2018

The paper analyzes and compares the effects of domestic monetary policy using DSGE, DSGE-VAR, and VAR based on a two-country open economy model of Korea and the U.S. According to impulse response analysis, a domestic interest rate hike raises won value in the case of DSGE and DSGE-VAR models, while in the case of the unrestricted VAR model, it lowers won value. In the marginal data density standard, DSGE-VAR (${\mu}=1$) is superior to DSGE or Bayesian VAR over the sample period. Conversely, in the in-sample RMSE criterion, especially for the won/dollar exchange rate, VARs are superior to DSGE or DSGE-VAR. It is necessary to study further if these differences are caused by model misspecification or omitted variable bias.

• Journal of the Korean Institute of Telematics and Electronics
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• v.24 no.2
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• pp.196-200
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• 1987

The following methods are proposed for implementing digital dual tone multi-frequency (DTMF) receiver: using infinite impulse response(IIR) digital filters, period-counting algorithm, discrete Fourier transform(DFT), and fast Fourier transform(FFT)[2]. The PARCOR(Partical Correlation) analysis method which has been widly used in the speech signal processing area is applied to the dual tone multi-frequency(DTMF) signal detection. This method is easy to implement digitally and stronger to digit simulation of speech than any other methods proposed up to date. Since sampling rate of 4KHz is used in the DTMF receiver for the detection of input DTMF signal originally sampled at 8KHz, it effects two times higher multiplexing efficiency.