• Title/Summary/Keyword: Impulse-response test

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Marine Freight Transportation and Cargo Handling Capacity of Ports (해상물동량과 항만의 처리능력)

  • 모수원
    • Journal of Korea Port Economic Association
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    • v.19 no.2
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    • pp.55-67
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    • 2003
  • The purpose of this study is to estimate and forecast the marine trading volumes based on the structural model. We employ GPH cointegration test since the structural model must be stationary to get the accurate predicted values. The empirical results show that our model is stationary. This paper also applies variance decompositions and impulse-response functions to the structural model composed of exchange rate, domestic industrial activity, and world business. The results indicate that while both loading and unloading volumes respond positively to the shocks in income and then decay very slowly, their responses are different to the shocks in exchange tate.

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An Enhancement of Multi-Dof Frequency Response Spectrum From Impact Hammer Testing (충격햄머 실험에서 다자유도 주파수 응답스팩트럼의 개선)

  • Ahn, Se-Jin;Jeong, Weui-Bong
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2002.11b
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    • pp.623-629
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    • 2002
  • The spectrum of impulse response signal from an impulse hammer testing is widely used to obtain frequency response function(FRF) of the structure. However the FRFs obtained from impact hammer testing have not only leakage errors but also finite record length errors when the record length for the signal processing is not sufficiently long. The errors cannot be removed with the conventional signal analyzer which treats the signals as if they are always steady and periodic. Since the response signals generated by the impact hammer are transient and have damping, they are undoubtedly non-periodic. It is inevitable that the signals be acquired for limited recording time, which causes the finite record length error and the leakage error. In this paper, the errors in the frequency response function of multi degree of freedom system are formulated theoretically. And the method to remove these errors is also suggested. This method is based on the optimization technique. A numerical example of 3-dof model shows the validity of the proposed method.

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The influence of load pulse shape on pressure-impulse diagrams of one-way RC slabs

  • Wang, Wei;Zhang, Duo;Lu, Fangyun
    • Structural Engineering and Mechanics
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    • v.42 no.3
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    • pp.363-381
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    • 2012
  • This study is aimed at providing an efficient analytical model to obtain pressure- impulse diagram of one-way reinforced concrete slabs subjected to different shapes of air blast loading using single degree of freedom method (SDOF). A tri-linear elastic perfectly plastic SDOF model has been used to obtain the pressure-impulse diagram to correlate the blast pressure and the corresponding concrete flexural damage. In order to capture the response history for the slab, a new approximately SDOF method based on the conventional SDOF method is proposed and validated using published test data. The influences of pulse loading shape on the pressure-impulse diagram are studied. Based on the results, a pressure-impulse diagram generation method using SDOF and an analytical equation for the pressure-impulse diagram is proposed to different damage levels and different blast loading shapes.

The Errors and Reducing Method in 1-dof Frequency Response Function from Impact Hammer Testing (충격햄머 실험에 의한 1자유도 주파수응답함수의 오차와 해결방법)

  • 안세진;정의봉
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.12 no.9
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    • pp.702-708
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    • 2002
  • The spectrum of impulse response signal from an impulse hammer testing is widely used to obtain frequency response function(FRF). However the FRFs obtained from impact hammer testing have not only leakage errors but also finite record length errors when the record length for the signal processing is not sufficiently long. The errors cannot be removed with the conventional signal analyzer which treats the signals as if they are always steady and periodic. Since the response signals generated by the impact hammer are transient and have damping, they are undoubtedly non-periodic. It is inevitable that the signals be acquired for limited recording time, which causes the errors. This paper makes clear the relation between the errors of FRF and the length of recording time. A new method is suggested to reduce the errors of FRF in this paper. Several numerical examples for 1-dof model are carried out to show the property of the errors and the validity of the proposed method.

A study on a Integrated analysis for survey of the cavity behind the Concrete (콘크리트 배면 공동탐사를 위한 복합적 해석 연구)

  • Noh, Myung-Gun;Oh, Seok-Hoon;Suh, Baek-Soo
    • 한국지구물리탐사학회:학술대회논문집
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    • 2009.10a
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    • pp.185-189
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    • 2009
  • Integrated analysis of GPR, impact echo and impulse response for detection of the rear cavity of concrete was performed on the test-bed which was made in the same scale and component ratio to the real concrete structure. GPR survey may roughly delineate the location of the cavity, but applying the IE and IR technique to the test-bed, the location was clearly identified.

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Characteristics of Impulse Buying According to Price Attitude towards Internet Apparel Purchases -Focusing on the Differences by Gender and Age- (인터넷 쇼핑에서 의류제품 가격태도에 따른 충동구매 특성 -성별, 연령별 비교를 중심으로-)

  • Ji, Hye-Kyung
    • Journal of the Korean Society of Clothing and Textiles
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    • v.37 no.6
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    • pp.737-749
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    • 2013
  • As more famous and luxurious fashion brands enter the online market, the changes in the online market include those in the composition of merchandise, price image, and consumer behavior. Focusing on these changes, this study examines the relation of consumer price attitude and impulse buying behavior towards internet apparel purchases. Data were obtained from 377 males and females in their 20s-40s who purchased apparel from an internet mall. Convenience sampling through the internet was performed. Collected data were analyzed by descriptive statistics, factor analysis, t-test, ANOVA, Duncan test, and regression analysis using SPSS for Windows 12.0. The results of this study are as follows. First, four dimensions of consumer price attitudes towards internet apparel purchases were found that included price-quality/prestige, sale, value for money, and low price orientation. Second, the influence of consumer price attitude on impulse buying is significant. As the price attitude of price-quality/prestige orientation and sale orientation increases, impulse buying orientation is stronger. Third, there are partially significant differences on the sub-dimensions of consumer price attitude and the influence of price attitude on impulse buying by gender and age. This study will be of help to internet companies by providing information in regards to a price attitude-based marketing strategy and an adequate response to customer impulse buying.

Analysis of Transient Response of an Engine to Throttle Tip-in/Tip-out (차량 감/가속시의 엔진의 동적 응답 해석)

  • 고강호
    • Transactions of the Korean Society of Automotive Engineers
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    • v.10 no.4
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    • pp.122-128
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    • 2002
  • In this paper dynamic responses of an engine, which is supported by hydraulic mount, to throttle tip-in/Tip out are analyzed. Because the hydraulic mounts have non-linearity that the characteristics of stiffness and damping vary with frequencies, it is difficult to analyze the dynamic behavior of an engine using general integral algorithms. Convolution integral and relationship between unit impulse response functions and frequency response functions are therefore used to simulate the transient behaviors of an engine indirectly. In time domain, impulse response functions are calculated by two-side discrete inverse courier transform of frequency response function achieved by laplace transform of equations of motion. Considering the fact that the shapes of behavior of an engine simulated by the proposed method are in good agreement with test results, it is confirmed that the proposed method is very effective for the analysis of transient response to throttle tip-in/out of an engine with hydraulic mounts.

Dynamic Analysis of Engine Response to Throttle Tip-in/Tip-out (Tip-in/Tip-out 시의 엔진의 동적 거동 해석)

  • Ko, Kang-Ho;Kook, Hyung-Seok
    • Proceedings of the KSME Conference
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    • 2001.06b
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    • pp.540-545
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    • 2001
  • In this paper dynamic responses of an engine, which is supported by hydraulic mount, to throttle tip-in/tip out are analyzed. Because the hydraulic mounts have non-linearity which the characteristics of stiffness and damping vary with frequencies, it is difficult to analyze the dynamic behavior of an engine using general integral algorithms. Convolution integrals and relationships between unit impulse response functions and frequency response functions are therefore used to simulate the transient behavior of an engine indirectly. In time domain, impulse response functions are calculated by two-side discrete inverse Fourier transform of frequency response function achieved by Laplace transform of equations of motion. Considering the fact that the shapes of behavior of an engine simulated by the proposed method are in good agreement with test results, it is confirmed that the proposed method is very effective for the analysis of transient response to throttle tip-in/out of an engine with hydraulic mounts.

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A Causality Analysis of the Hairtail Price by Distribution Channel Using a Vector Autoregressive Model (VAR 모형을 이용한 유통단계별 갈치가격의 인과성 분석)

  • Kim, Cheol-Hyun;Nam, Jong-Oh
    • The Journal of Fisheries Business Administration
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    • v.46 no.1
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    • pp.93-107
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    • 2015
  • This study aims to analyze causalities among Hairtail prices by distribution channel using a vector autoregressive model. This study applies unit-root test for stability of data, uses Granger causality test to know interaction among Hairtail Prices by distribution channel, and employes the vector autoregressive model to estimate statistical impacts among t-2 period variables used in model. Analyzing results of this study are as follows. First, ADF, PP, and KPSS tests show that the change rate of Hairtail price by distribution channel differentiated by logarithm is stable. Second, a Granger causality test presents that the producer price of Hairtail leads the wholesale price and then the wholesale price leads the consumer price. Third, the vector autoregressive model suggests that the change rate of Hairtail producer price of t-2 period variables statistically, significantly impacts change rates of own, wholesale, and consumer prices at current period. Fourth, the impulse response analysis indicates that impulse responses of the structural shocks with a respectively distribution channel of the Hairtail prices are relatively more powerful in own distribution channel than in other distribution channels. Fifth, a forecast error variance decomposition of the Hairtail prices points out that the own price has relatively more powerful influence than other prices.

Life Firing Test of 1 N-class Monopropellant Thruster Development Model -Part II: Pulse Mode Performance (1 N급 단일추진제 추력기 개발모델의 장기수명 연소시험 -Part II: 펄스모드 성능 특성)

  • Won, Su-Hee;Kim, Su-Kyum;Jun, Hyoung-Yoll;Lee, Jun-Hui;Park, Su-Hyang;Lee, Jae-Won
    • Journal of the Korean Society of Propulsion Engineers
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    • v.18 no.6
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    • pp.68-74
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    • 2014
  • During the life firing test of 1 N-class thruster development model, pulse mode performance and performance changes were examined. The deviation of pulse mode response time according to thruster feed pressure was relatively small and the resultant ignition delay, response time, tail-off time were 32-35 ms, 86-91 ms, 89-98 ms, respectively. For the stabilized pulse region the impulse bit revealed the outstanding reproducibility of 1.41, 1.32, 2.10% at $3{\sigma}$. During the life firing test, the impulse bit was decreased with limited amounts, therefore the pulse mode performance could be considered to be maintained. The thrust centroid was also maintained during the life firing test.