• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1996년도 추계학술대회논문집; 한국과학기술회관, 8 Nov. 1996
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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.

• 해운물류연구
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• 제27권4호
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• pp.719-746
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• 2011

본 논문은 일반투자자들의 선박투자회사에 대한 투자성과를 초과수익률과 누적초과수익률로 측정하였으며, 선박금융 운용회사간, 투자대상선박의 신조 여부간, 그리고 투자대상선박의 컨테이너선 여부간 초과수익률과 누적초과수익률의 차이를 분석하였다. 그 결과, 선박금융 운용회사간에는 최초공모주의 초과수익률, 초기 30일 누적 초과수익률, 장기 누적초과수익률에서 유의적인 차이가 나타나지 않았고, 투자대상선박이 신조인 선박투자회사와 중고인 선박투자회사간에는 최초공모주의 초과수익률, 장기 누적초과수익률에서 유의적인 차이가 존재하지 않았지만, 초기 30일 누적초과수익률에서는 유의적인 차이가 존재하는 것으로 나타났다. 반면, 컨테이너선박에 투자한 선박투자회사와 컨테이너선외의 선박에 투자한 선박투자회사간에는 초기 30일 누적초과수익률, 장기 누적초과수익률에서 유의적인 차이가 존재하는 것으로 나타났다. 한편, 3개월별 누적수익률 추세에서 신조 선박에 투자한 선박투자회사가 중고선박에 투자한 선박투자회사 보다, 그리고 컨테이너선박에 투자한 선박투자회사가 컨테이너 선외의 선박에 투자한 선박투자회사 보다 더 안정적인 추세를 보였다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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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.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 추계학술대회 논문집
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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.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 International Symposium on GPS/GNSS Vol.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.

• 재무관리연구
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• 제23권2호
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• pp.27-56
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• 2006

본 연구에서는 거래소와 코스닥에서 2000년부터 2004년까지 감자를 실시한 기업들을 조사하여 해당기업들이 표방하는 대로 감자의 목표를 잘 수행하고, 또한 그러한 과정에서 정보에 있어서 열악한 일반 투자자들이 감자를 실시한 기업에 투자하여 투자수익률을 제대로 보전하는 지를 감자 공시일 전후의 주가행태를 실증 분석하여 살펴보고자 하였다. 감자를 실시하는 기업들은 대부분 재무구조의 개선을 주목적으로 하는데, 재무비율 중 부채비율에 있어서는 감자 실시 후 현저한 향상이 이루어 졌으나, 부채비율의 향상이 ROA나 ROE같은 기업의 수익성 향상으로 연결되는 징후는 발견하지 못하였다. 감자를 실시하고도 기업의 수익성이 향상되지 못하는 것은 감자 전 후의 누적초과수익률(CAR)을 살펴봤을 때 확연히 드러나는데, CAR이 감자 전 후 조사기간 내내 음의 수익률 일변도를 기록하였다. 이러한 음(-)의 CAR은 높은 부채비율과 감자비율과의 연관성이 높은 것으로 나타났다. 특히, 코스닥의 경우는 CAR이 최대 -53.5%까지 하락하였다. 코스닥 감자실시 기업들은 상장폐지를 피하고자 감자를 실시하였지만, 감자 후 결국 상장 폐지되는 모순적인 기업들이 조사표본의 절반이나 되었다. 본 연구에서는 자본잠식 문제를 해결하기 위해서 부실기업들이 새로운 부가가치를 창출하는 투자기회를 확보함이 없이, 단순히 감자를 하고, 다시 자본금을 확충하고, 급기야는 상장 폐지되는 구태의연한 재무의사결정만으로는 일반 투자자들의 부뿐만아니라 궁극적으로 기업의 가치를 극대화할 수 없다는 점을 지적한다.

• 한국자동차공학회논문집
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• 제6권3호
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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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• 제14권8호
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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.

• 기술사
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• 제43권6호
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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.

• 한국기계가공학회지
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• 제9권2호
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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.