• Geophysics and Geophysical Exploration
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• v.16 no.1
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• pp.45-52
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• 2013

We developed a Impulse Response Measurement System, including hardware system and data analysis software, for non-destructive test of slab structure. And, we carried out impulse response measurements on the pavement to test performance of the system. In the field test, the developed system measured impulse response stably and showed parameters immediately. Test results showed that dynamic stiffness and average mobility varies significantly depending on the characteristics of the pavement materials. Some data showed anomalous values those reflect variations in pavement itself or subsurface ground. Developed system gives informations of conditions of slab structure easily and quickly. So, 2-D monitoring with the system will be helpful in maintaining various slab structures.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.45 no.2
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• pp.283-288
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• 1996

This paper presents the development technology of standard shielded resistor divider for full lightning impulse voltage. The ability of large-capacity power apparatus to withstand lighting stroke is usually evaluated by means of full lightning impulse voltage. Lightning impulse voltage test has been essential to evaluate the insulation performance of electrical power apparatus. Recently international standard (IEC 60) on high voltage measurement techniques is being revised and requests a formal traceability of high voltage measurements. Therefore, general interest for this area has grown considerably during last years, and several international intercomparisons have already completed worldwide, i.e. Europe, Japan, America etc., In this viewpoint, we have also investigated the step response of the standard shielded resistor divider, which satisfies the IEC recommendation.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1445_1446
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• 2009

This paper represents the step response characteristics of shunts for impulse current. This work is aimed at the development of the reference measuring system(RMS) for impulse current rated 10 kA at 1/$20{\mu}s$, 100 kA at 4/$10{\mu}s$, 20 kA at 8/$20{\mu}s$, 40 kA at 30/$80{\mu}s$. According to the IEC 60060-2, the step response characteristics was assessed. As results of the test, the step response characteristics of newly developed shunts for impulse current satisfied requirements of RMS.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.10
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• pp.792-798
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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.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.363.2-363
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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. (omitted)

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.71-77
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• 2002

The spectrum of impulse response signal which is obtained from an impulse hammer testing is used for frequency response function, nevertheless it has serious faults when the record length for the signal processing is not very long. The faults cannot be avoided with the conventional signal analyzer that is processing all the signals as if they are always periodic. The signals generated by the impact hammer are undoubtedly non-periodic because of the damping, and are acquired for limited recording time due to the memory as well as the computation performance of the signal analyzer. This paper will make clear the relation between the faults and the length of recording time, and propose the way for solving the faults.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.714-720
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• 2008

This research presents a laboratory study about an subjective response of impulsive sound caused by leisure shooting. The sources are sampled from outdoor noise and their levels range from 40 to 75 dB at the interval of 5dB. The noise unit is based on A-weighted sound exposure level (ASEL; $L_{AE}$). To make equal ASEL of outdoor noise, finite impulse response (FIR) filter is applied to the originally sampled source to include the effect of distance attenuation. The evaluation method of the jury test adopted a Semantic Difference(SD) Method. In the result of the jury test for impulsive noise, the mean response rating expressed a linear relation and %HA(percent highly annoyed) displayed a exponential growth relation.

• Korean Management Science Review
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• v.25 no.3
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• pp.13-26
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• 2008

We investigate the effect of government and public sector R&D Investment at IT Industry on the amount of Production, export and nongovernment R&D Investment at IT Industry. We, firstly, examine the stationarity of each variable by the unit root t-test and perform the co-integration test for the pairs of variables. We use YECM(Vector Error Correction Model) according to the results of co-integration test for the examination of Granger-causality between variables. It is found that there exist an Granger-causality between public sector R&D Investment and nongovernment R&D investment and also between public sector R&D Investment and export. Secondly, we analyze the impulse response of government and public sector R&D Investment at IT Industry on the amount of production, export and nongovernment R&D investment at IT Industry based on VECM model. It is found that the response of the amount of production is highest at 3th period and is lowest at 8th period and that of export shows similar pattern.

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1858-1860
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• 2003

Ground rods as the discharge path are commonly installed to ensure the safety of human beings and facilities from the surge. Accordingly, proper grounding resistance are specified by the grounding types, and the specified resistance are also required to install the lightning protective facilities. it is needed to analyze the difference between these two resistance through the field test. Therefore, in this paper, the impulse response behavior of the ground rods is analyzed by constructing the test facilities and by testing the ground rods in multi-ground power distribution systems. The impulse responses were analyzed, in transient state, by testing the concrete poles as well since the grounding wires are installed in the concrete poles.

• Ocean and Polar Research
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• v.40 no.1
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• pp.49-58
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• 2018

This study aimed to analyze the causality of hairtail prices among import and domestic distribution channels using a Vector Error Correction Model(VECM). The results are as follows. First, since the ADF unit-root test suggests that each of the price variables, apart from retail price, has a unit root, the price variables should be 1st-differenced to secure the stability of the prices. Next, through the Johansen co-integration test, it was discovered that there are long-term relationships among the price variables. On the basis of the co-integration test, VECM analysis shows that the producer price has a long-run balance with the import and wholesale prices. In particular, when the prices deviate from the balance, the producer price dynamically adjusts to return to the long-term relationship among prices. It also indicates that the producer price has an impact on the import, wholesale, and retail prices in the short-term, and the import price has an influence on the producer and wholesale prices. In addition, the impulse response analysis demonstrates that the impulse of import and producer prices has a lasting impact on each of the prices.