• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.5
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• pp.156-162
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• 2003

The shock absorber is a part having a direct influence on the ride comfort, stability and dynamic load prediction of a vehicle. Thus, a rationally modeled shock absorber should be required in the dynamic analysis of vehicles. This thesis presents a modified model, based on Worden's hyperbolic tangent function, in order to fit experimental data on the velocity-damping force of a shock absorber. The hyperbolic tangent function correctly indicates the characteristics of a shock absorber, and has the advantage of containing physical causality. To evaluate the method, comparative evaluations of the linear model, the 5th polynomial model and Worden's model were carried out. The function presented in this paper is not only simple but also makes it possible to estimate the function coefficients easily and visually. In addition, it has the advantage of containing physical causality. Lastly, it effectively models the damping force of a shock absorber.

• Journal of Korea Technology Innovation Society
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• v.4 no.1
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• pp.79-95
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• 2001

This paper examines the effects of information telecommunication (IT) capital and R&D stock variation on the growth of Korean industry, using a time series approach. Most specifically, we apply the Granger causality and impulse response analysis to our examination of Koreas industrial growth, IT capital, and R&D stocks. The Johansen co-integration test is performed in order to analyze long-term relations among these variables. This research explores the way in which IT capital and R&D stocks variation from economic shocks affects the growth of Koreas industrial sector. The effects are ambiguous, however, across industrial sectors. An impulse response function analysis shows that the effects of IT capital and R&D stock fluctuations in each industrial sector are presented for different time periods.

• Proceedings of the Korea Technology Innovation Society Conference
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• 2004.05a
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• pp.77-97
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• 2004

In this paper we: (1) analyze the relationship among public R&D investment, private R&D investment, and GDP by employing the Granger causality test; (2) examine if there is any country-specific pattern in the relationship by testing the cases of Korea, the U.S. and Japan. We found some common results for the above countries as follows: (i) GDP causes Public R&D, not vice versa; (ii) Private R&D causes GDP; and (iii) Public R&D does not cause Private R&D. For the bivariate model of GDP and total R&D, the results show the existence of one-way causality running from total R&D to GDP for both U.S, and Japan. We also found bidirectional causal relationship between GDP and total R&D for Korea, which could be interpreted as a typical pattern for newly industrialized countries.

• Journal of the Korea Society for Simulation
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• v.4 no.2
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• pp.31-40
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• 1995

A hybrid simulation model consists of real physical entities as well as simulated ones. It also contains logical processes for decision making for each operation units, a group of the entities. During the execution of such simulations, the physical and the logical processes consume real clock time while the activity durations of the simulated ones are generated. Due to the inherent chracteristics of the subjects of the communication channels. Since one can not undo an real event already taken place, the traditional central clock approach is used for the synchronization of the events(Kim[6]). However, there are still chances of causality errors due to the randomness in the communication delays. This error is not found in the distributed pure simulations. This paper explains the error in details and proposes a prevention scheme that is simple to implement.

• Asia pacific journal of information systems
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• v.16 no.2
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• pp.111-122
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• 2006

This paper investigated the causal relationship between IT investment and economic performance with the office, computing and accounting machinery (OCAM) and gross domestic product (GDP) statistics from the United States for the period 1961 to 2001. Due to non-stationary aspects of the series, found by unit root tests, it was deemed applicable to apply growth models using the first difference of the series. The results indicate that IT investment growth at the country level do not only cause economic performance growth, but are also caused by economic performance growth. While IT investment growth affect economic performance growth over shorter time periods, economic performance growth affect IT investment growth over longer time periods. As a result, this study reveals IT investment growth have the preceding effect on economic performance growth, and then economic performance growth impact subsequently on IT investment growth.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1479-1482
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• 2003

The shock absorber is a part having a direct influence on the ride comfort, stability and dynamic load prediction of a vehicle. Thus, a rationally modeled shock absorber should be required in the dynamic analysis of vehicles. This thesis presents a modified model, based on Worden's hyperbolic tangent function, in order to fit experimental data on the velocity-damping force of a shock absorber. The hyperbolic tangent function correctly indicates the characteristics of a shock absorber. and has the advantage of containing physical causality. To evaluate the method, comparative evaluations of the linear model. the 5th polynomial model and Worden's model were carried out. The function presented in this paper is not only simple but also makes it possible to estimate the function coefficients easily and visually. In addition, it has the advantage of containing physical causality. Lastly, it effectively models the damping force of a shock absorber.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.10 s.103
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• pp.1131-1136
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• 2005

For the accurate measurement of acoustic properties of a surface, efforts have been made to reduce errors caused by external disturbance. If the reflection coefficient is considered as a transfer function between reflected wane and incident wave, the causality is required between them and the reflection coefficient should be of minimum phase. In this thesis, the minimum phase condition is applied to measure correct reflection coefficient. The reflection coefficient is approximated as a rational function In the Z domain by minimizing the sum square error. Then the minimum phase reflection coefficient is reconstructed using the distribution of poles and zeros of the reflection coefficient model.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.695-700
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• 2008

Artificial neural network (ANN) has been extensively used in areas of nonlinear system modeling, analysis and design applications. Basically, ANN has its distinct capabilities of implementing system identification and/or function approximation using a number of input/output patterns that can be obtained via numerical and/or experimental manners. The paper describes a role of ANN, especially a back-propagation neural network (BPN) in the context of engineering analysis, design and optimization. Fundamental mechanism of BPN is briefly summarized in terms of training procedure and function approximation. The BPN based causality analysis (CA) is further discussed to realize the problem decomposition in the context of multidisciplinary design optimization. Such CA is also applied to quantitatively evaluate the uncoupled or decoupled design matrix in the context of axiomatic design with the independence axiom.

• International Commerce and Information Review
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• v.10 no.1
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• pp.329-347
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• 2008

The purpose of this study is to examine the causal relationship between the exchange rate and economic growth, and to induce policy implications. In order to test whether time series data is stationary and the model is fitness or not, we put in operation unit root test, cointegration test. And we apply Granger causality based on an error correction model. The results indicate that uni-dierctional causality between exchange rate and economic growth is detected. Exchange rate impacts on economic growth, but economic growth don't impact on exchange rate. The analysis of impulse reaction function shows that the impulse of exchange rate impacts on Korean economic growth in negative direction. We can infer policy suggestion as follows: The fluctuation of exchange rate much affects economic growth, thus we must make a stable policy of exchange rate to continue economic growth.

• 대한상한금궤의학회지
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• v.9 no.1
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• pp.47-58
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• 2017

Objective : The purpose of this paper is to report the adverse drug reactions of patient with cervical spondylotic myelopathy(CSM) treated by herb medicine, Soshiho-tang. Methods : The patient was prescribed Soshiho-tang herbal medicine for 9days. The patient complained of dizziness, difficulty of concentration and elevation of blood pressure on the 6th day. The doctor made the patient stop to take the herbal medicine and every symptoms and abnormal blood pressure are normalized after 6 days. The abnormal responses were assessed by WHO-UMC Causality Categories and LDS scale. Results : The WHO-UMC Causality is 'probable/likely' and LDS scale is 5, it means 'moderate' severity. Conclusions : The herbal medicine, Soshiho-tang is relevant to abnormal responses of the patient with CSM. This is a first case report of hypertension induced by herbal medicine, Soshiho-tang in Korea.