• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1996.10a
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• pp.345-350
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• 1996

The suspension system plays an important role in vehicle performance. To improve suspension characteristics related to riding comfort and handling stability simultaneously, active suspension system is developed. In this study, a hybrid control scheme is proposed, the idea of which is that the sliding mode control is applied to nonlinear hydraulic system and the skyhook control is applied for controlling the motion of the suspension system. The performance of the proposed control method is evaluated by simulation and experiment of a half car active suspension system.

• The Journal of shipping and logistics
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• v.27 no.4
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• pp.719-746
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• 2011

This study attempted to analyse the results of investments from each individual ship investment company(SIC) in Korea which is operating under its ship investment company system. We analyzed investment result of ship investment company by means of Market Adjusted Return Method for measurement of abnormal return(AR) and cumulative abnormal return(CAR). Some implications from the results of this study are suggested. First, we find that the initial abnormal return of IPO, 30-day CAR and long-term CAR are not significantly different between A and B shipping fund management company. And then, the initial abnormal return of IPO and long-term CAR are not significantly different between newbuilding and secondhand ship SIC. But the 30-day CAR is significantly different between newbuilding and secondhand vessel SIC. Third, the 30-day CAR and long-term CAR are not significantly different between newbuilding and secondhand vessel SIC. But the 30-day AR is not significantly different between container and non-container ship SIC. Finally, newbuilding ship SCI is more stable than secondhand vessel SIC, and container ship SIC is more stable than non-container ship SIC in 3-month cumulative return over the past two and half years, from February 2008 to July 2011.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2573-2578
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• 2007

In order to investigate the vortex body frame interaction around the side mirror of a passenger car, velocity vector fields in the wake, pressure distributions and boundary layer flows over both the mirror surface and the mirror housing, have been measured by several experimental tools. It was resulted that only within an half downstream distance of the mirror span there appears the recirculation zone, and also found that vortex trail towards to the driver side window between A and B pillars, making the acoustic noise and vibration. Wake vortex rolls up after this recirculating zone and makes the trail of the vortex center towards the driver side window, which was also confirmed by measurements of wake velocity vectors in the vertical sections of the trail and visualization over the side mirror surfaces as well. It was also observed that total pressure distribution over the mirror surface has the minimum peak near the lower tip region which can be considered as the origin of the vortex center. It can be concluded that the geometrical modification of the lower tip and the upper root area of the mirror housing is the key to control the wake vortex.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.162-167
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• 2004

The ascent and descent market screen door (PSD-Platform Screen Door) between the electromotive car which is in the process of operating from the subway ascent and descent market and the passenger it is an immediacy and crisis as the system which it intercepts currently the inside and outside of the country of course signal system automatic operation signal system (ATO) establishment is operated from the segment. Manual operation signal system (the ATS and the ATC) almost it is a condition which is wholly lacking from the segment. This year from second half of the year 2 line manual operation signal system (ATS). It established the shutting tightly elder brother and the railing elder brother in PSD system in segment 12 reverses and the death accident due to the passenger hurt accident which occurs from the subway. It prevented an energy curtailment in the same time when it raises air cooling efficiency, It gathered it restricted the underground space which is comfortable in the use citizen and and and service it did interface the electromotive car and PSD entrance and exit literature course from the manual operation segment to sleep technically optimizationt. It researched a minute dust diffusion.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.1
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• pp.179-184
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• 2006

Rapid and high-precision positioning with a Global Navigation Satellite System (GNSS) is feasible only when very precise carrier-phase observations can be used. There are two kinds of mathematical models for ambiguity resolution. The first one is based on both pseudorange and carrier phase measurements, and the observation equations are of full rank. The second one is only based on carrier phase measurement, which is a rank-defect model. Though the former is more commonly used, the latter has its own advantage, that is, ambiguity resolution will be freed from the effects of pseudorange multipath. Galileo will be operational. One of the important differences between Galileo and current GPS is that Galileo will provide signals in four frequency bands. With more carrier-phase data available, frequency combinations with long equivalent wavelength can be formed, so Galileo will provide more opportunities for fast and reliable ambiguity resolution than current GPS. This paper tries to investigate phase only fast ambiguity resolution performance with four Galileo frequencies for short baseline. Cascading Ambiguity Resolution (CAR) method with selected optimal frequency combinations and LAMBDA method are used and compared. To validate the resolution, two tests are used and compared. The first one is a ratio test. The second one is lower bound success-rate test. The simulation test results show that, with LAMBDA method, whether with ratio test or lower bound success rate validation criteria, ambiguity can be fixed in several seconds, 8 seconds at most even when 1 sigma of carrier phase noise is 12 mm. While with CAR method, at least about half minute is required even when 1 sigma of carrier phase noise is 3 mm. It shows that LAMBDA method performs obviously better than CAR method.

• The Korean Journal of Financial Management
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• v.23 no.2
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• pp.27-56
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• 2006

This paper analyzes whether corporations which have done capital reduction fulfill the objectives of their capital reduction as planned and also asks how did the capital reduced corporations fare in terms of stock returns, by investigating the capital reduced corporations on the Exchange and the Kosdaq between 2000 and 2004. Most capital reduced companies aim to improve their capital structure. Debt to Equity ratio among financial ratios has improved significantly after capital reduction, yet the profitability of corporations wasn't up to expectations. The analysis of cumulative abnormal returns (CARs) indicates that the CARs were below '0' during whole investigation period. Besides, the CARs of companies listed on the Kosdaq have plummeted to -53.5%. Half of the companies on the Kosdaq in this sample which have reduced their capital to avoid delisting have been eventually delisted after capital reduction. This Study concludes that simple capital reduction without having value-added projects is not beneficial to shareholders.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.3
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• pp.34-44
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• 1998

It is clear that when an automobile negotiates a curve the lateral acceleration causes an increase in tire normal load for the wheels on the outside of the curve and a decrease in load for the inside wheels. However, just how the details of the suspension linkages and the parameters of the springs and shock absorbers affect the dynamics of the load transfer os not easily understood. One even encounters the false idea that since it is the compression and extension of the main suspension springs spring body role which largely determines the changes in normal load, of roll could be reduced, the load transfer would also be reduced. Using free body diagrams, one can explain quite clearly how the load is transferred for steady state cornering, and, using complex multibody models of particular vehicles one can simulate in good fidelity how load transfer occurs dynamically. Here we adopt a middle ground by using the concept of roll center and using a series of half-car bond graph models to point out main effects. Since bond graph junction structures automatically and consistently constrain geometric and force variables simultaneously, they can be used to point out hidden assumptions of other simplified vehicle models.

• Journal of Mechanical Science and Technology
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• v.14 no.8
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• pp.807-815
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• 2000

In this paper, modified discrete time preview control algorithms for active and semi-active suspension systems are derived based on a simple mathematical 4 DOF half-car model. The discrete time preview control laws for ride comfort are employed in the simulation. The algorithms for MIMO system contain control strategies reacting against body forces that occur at cornering, accelerating, braking, or under payload, in addition to road disturbances. Matlab simulation results for the discrete time case are compared with those for the continuous time case and the appropriateness of the discrete time algorithms are verified by the of simulation results. Passive, active, and semi-active system responses to a sinusoidal input and an asphalt road input are analysed and evaluated. The simulation results show the extent of performance degradation due to numerical errors related to the length of the sampling time and time delay.

• Journal of the Korean Professional Engineers Association
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• v.43 no.6
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• pp.39-45
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• 2010

Soil plays a huge role in climate change, because even a tiny loss of 0.1% of carbon emitted into the atmosphere from European soils is the equivalent to the carbon emission of 100million extra cars on Europe's roads - an increase of about half of the existing car fleet. Soils contain around twice the amount of carbon in the atmosphere and three times the amount to be found in vegetation. Europe's soils are an enormous carbon reservoir, containing around 75billion tonnes, and poor management can have serious consequences. Soil degradation is accelerating across the EU, with negative effects on human health, ecosystems and climate change - and on economic prosperity and quality of life. Climate change is identified as a common element in many soil threats. Europe's soils urgently need better protection. The current trend of soil degradation needs to be reversed, and soil management practices must be improved if a high rate of soil carbon sequestration is to be achieved.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.9 no.2
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• pp.33-39
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• 2010

The thickness of original hinge model is changed for structural stability in this study. The front end with the largest deformation of 9.8813 mm or the rear middle part with the largest equivalent stress of 6082.6 MPa is respectively shown at door hinge. The lower part of joint pin head with the largest deformation of 0.17499 mm and the largest equivalent stress of 1540.2 MPa are shown. The advanced model with more thickness and stability is shown to have smaller displacement in half and smaller equivalent stress by 3 times by comparing with the original model.