• 한국자동차공학회논문집
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• 제8권2호
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• pp.92-101
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• 2000

The objective of this paper is to design the controller for longitudinal vehicle following which makes the vehicle follow the lead vehicle and keeps a safety distance without human driver operation. This paper presents a sliding mode control algorithm for the ACC system. The controller is based on three sliding surfaces. Each surface plays an individual control-deviation control, throttle control and brake control. In addition to sliding mode control, we propose some additional schemes to enhance controller performance. The first one is a gear shift-down controller which makes tractive force increase with a change of gear ratio. The other is a predictive correction method which reduces slinky effect.

• 대한치과기공학회지
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• 제28권1호
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• pp.53-59
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• 2006

The movement range on the semi adjustable articulator and the movement range in an oral were measured. And then I studied to analyze the gap. I got wax records by the movement on the semi adjustable articulator, the movement in an oral. I measured the distance of the cusp tips that are close to the mesial direction and the distal direction, the buccal direction and the lingual direction then I compared gaps. As I saw results on data, I knew that the semi adjustable articulator represented the range of mandibular movement restrictively. I could find the decisive contradiction that the sliding movement finished on the semi adjustable articulator although it did not finish in an oral. When the sliding movement does not reappear exactly, it brings a fatal failure to the dental prosthesis. In addition it is impossible that the semi adjustable articulator restores the movement in an oral because the lateral condyle inclination and the horizontal condyle inclination are appeared to be straight. Therefore dental prosthesisses were made by the semi adjustable articulator, they will interfere with a mastication. I have obtained the following results; 1. The distance of sliding movement on the semi adjustable articulator showed shorter than the distance of sliding movement in oral. This means the increase of cusp inclination of the dental prosthesis that was made on the semi adjustable articulator. Therefore, when the lateral movement occurs in oral, there is a possibility to become the premature as the increase of cusp inclination. 2. The difference in the range of movement is considered as the gap that is made because the movement only can be occurred as straight in the semi adjustable articulator. 3. When the dental technician understand mandibular movement and articulator deficiencies, they can attain proficiency in use of the articulator and reduce the gap.

• 대한치과기공학회지
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• 제25권1호
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• pp.111-118
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• 2003

I measured the movement range on the hinge articulator and the movement range in an oral. And then I studied to analyze the gap. I got wax records by the movement on the hinge articulator, the movement in an oral and the movement on the hand articulating. I measured the distance of the cusp tips that are close to the mesial direction and the distal direction, the buccal direction and the lingual direction then I compared gaps. As I saw results on data, I knew that the hinge articulator represented the range of mandibular movement restrictively. I could find the decisive contradiction that the sliding movement finished on the hinge articulator although it did not finish in an oral. If the sliding movement does not reappear exactly, it brings a fatal failure to the dental prosthesis. In addition it is impossible that the hinge articulator restores the movement in an oral because the lateral condyle inclination and the horizontal condyle inclination are fixed previously. Therefore dental prosthesisses were made by the hinge articulator, they will interfere with a mastication. I have obtained the following results; 1. The distance of sliding movement on the hinge articulator showed shorter than the distance of sliding movement in oral. This means the increase of cusp inclination of the dental prosthesis that was made on the hinge articulator. Therefore, when the lateral movement occurs in oral, there is a possibility to become the premature as the increase of cusp inclination. 2. The results that were impressed records in oral and impressed records on the hand articulating have many congruities. I think that the simple crown etc. that were made by the hand articulating method except the long span bridge and the free end case that can not measure the vertical dimension exactly can represent similarly the mandibular movement. 3. If we want to represent the mandibular movement similarly, we have to use the articulator that can adjust the horizontal condyle inclination and the lateral condyle inclination at least.

• 한국해안해양공학회지
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• 제19권2호
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• pp.113-127
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• 2007

본 연구에서는 직립 방파제 케이슨의 활동에 따른 복구비용, 과도한 케이슨 활동 발생시 항만 폐쇄에 따른 경제적 피해 비용 그리고 월파에 의한 일시적 작업 중단에 따른 경제적 피해 비용을 동시에 고려하는 기대 총 건설비 산정 모델을 수립하였다. 발생시점이 서로 다른 피해 비용을 일정한 기준으로 산정하기 위해 할인율을 적용하였다. 케이슨의 최적 단면은 방파제 수명 동안의 기대 활동량의 허용범위 내에서 기대 총 건설비용이 최소가 되는 단면으로 정의되며, 그 기대 활동량의 허용치는 0.3 m와 0.1 m 두 가지 경우에 대해 살펴보았다. 과도한 케이슨 활동에 의한 항만 폐쇄에 따른 경제적 피해 비용과 그 산정 기준이 케이슨 복구비용이나 월파에 의한 작업 중단에 따른 경제적 피해 비용보다 최적 단면 결정에 더 중요한 요인임을 확인하였고, 항만 폐쇄에 대한 케이슨 활동량의 임계 칼이 커질수록 케이슨의 최적 단면은 기대 총 건설비의 최소점보다 기대 활동량의 허용치에 의해 결정되는 것으로 나타났다.

• Tribology and Lubricants
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• 제30권6호
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• pp.364-369
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• 2014

To assess the wear behavior of rails against subway rail car wheels, we investigate the sliding wear behavior of pins derived from two types of rails (normal rails and heat-treated rails) against a disc derived from a subway rail car wheel, using a pin-on-disc-type tribometer. We base the sliding wear test conditions on the sliding conditions for wheel flange-rail gauge corner contact. We demonstrate the remarkable transition in the wear behavior of the pins derived from the rails, from severe wear to mild wear, as a function of the sliding distance. The wear rate of the heat-treated rail material in the running-in wear region is much lower than that of the normal rail material. Furthermore, the wear rates of the pins in the running-in wear region decrease with increasing hardness and with decreasing sliding speed. However, there is little difference between the heat-treated rail pin and the normal rail pin in the wear rate in the steady-state wear region. Stricter controls on the decarburized layer beneath the surface of rails are required to reduce the wear rate in the running-in wear region.

• Tribology and Lubricants
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• 제36권3호
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• pp.117-123
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• 2020

In this study, the effect of the pre-mild wear mode test condition on the subsequent severe wear behavior of carbon steel has been investigated when the wear mode is varied according to the sliding speed change during sliding contact. Two sliding speeds of 0.3 m/s and 3 m/s for the mild wear mode test have been chosen and a sliding speed of 1 m/s for the severe wear mode test. A mild wear mode test at two different sliding speeds has been carried out during the severe wear mode test and total sliding distance of the mild wear mode test has been changed at this time. As a result, it could be found that the wear rate of carbon steel under the severe wear mode test after performing a pre-mild wear mode test is significantly reduced, compared with that before performing. However, its wear rate was slightly higher than that under the mild wear mode test. Oxides produced during the pre-mild wear mode test have been found to play a significant role in reducing the wear rate under the subsequent severe wear mode test. In particular, it was found that the effect of a pre-mild wear mode test performed at the sliding speed of 3 m/s has more rapid and the reduction in the wear rate was greater than thst at the sliding speed of 0.3 m/s.

• 한국해안·해양공학회논문집
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• 제26권5호
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• pp.267-277
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• 2014

본 연구에서는 기존의 무공케이슨 방파제에 대하여 개발된 성능설계법을 유공케이슨 방파제로 확장하여 적용하였다. 확장된 계산 모형은 한국해양연구소에서 수행한 수리 실험결과와 비교하여 검증하였다. 케이슨의 안정성을 평가하기 위하여 방파제 수명 동안의 누적활동량의 평균으로 정의되는 기대활동량과 누적활동량이 일정한 허용치를 초과할 확률을 산정하여 케이슨의 안정성 평가에 사용하였다. 기대활동량과 초과확률 모두 수심이 감소함에 따라 쇄파대 안쪽에서는 증가하며, 바깥쪽에서는 감소하는 경향을 보였다. 또한, 안전율에 기초한 결정론적 설계법의 결과와 비교해 보았을 때, 성능설계법의 설계기준에 따라 경제성이 달라지는 것으로 나타났다. 허용기대활동량과 초과확률이 극한 한계상태를 만족할 경우 쇄파대 바깥쪽에서는 성능설계법이 결정론적 설계법보다 비경제적인 것으로 나타났으며, 쇄파대 안쪽에서는 비슷한 경제성을 가지는 것으로 나타났다. 그러나, 복구가능한계상태를 만족할 경우 성능설계법이 결정론적 설계법보다 더 경제적인 것으로 평가되었다.

• 한국해안·해양공학회논문집
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• 제25권5호
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• pp.317-326
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• 2013

확률론적 설계법은 설계변수의 불확실성을 고려할 수 있기 때문에 직립방파제의 설계에 폭넓게 사용되고 있다. 대표적인 확률론적 설계법은 부분안전계수 설계법, 신뢰성 설계법, 성능설계법 등이 있다. 특히 성능설계법은 구조물의 수명 또는 설계폭풍 지속시간 동안의 누적활동량을 계산한다. 최근 설계폭풍 동안에 개별활동량의 최초통과확률을 산정할 수 있는 시간의존 성능설계법이 개발되었다. 하지만 개발된 방법의 허용기준이 없어 구조물의 안정성을 정량적으로 평가할 수 없었다. 본 연구에서는 다양한 수심과 극치파고분포의 특성을 반영한 구조물의 단면에 대하여 최초통과확률을 산정함으로써 두 가지 한계상태에 따른 허용최초통과확률을 제안하였다. 수리가능한계상태(개별 허용활동량 0.03 m)와 극한한계상태(개별 허용활동량 0.1 m)에서 허용최초통과확률은 각각 5%와 1%로 산정되었다. 제안된 허용기준을 적용하여 기후변화에 따른 파고 증가가 방파제 안정성에 미치는 영향을 평가하였다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.1810-1815
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• 2003

Sliding mode control with nonlinear interpolation in the boundary layer is proposed. A modified sigmoid function is used for nonlinear interpolation in the boundary layer and its parameter is tuned by a fuzzy logic controller. The fuzzy logic controller that takes the distance between the system state and the sliding surface as its input guides the choice of parameter of the modified sigmoid function and the parameter is on-line tuned. Owing to the decreased thickness, the proposed method has better tracking performance than the conventional linear interpolation method. To demonstrate its performance, the proposed control algorithm is applied to a simple nonlinear system model.

• 수산해양기술연구
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• 제44권3호
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• pp.250-256
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• 2008

Generally the side plate materials of FRP ship are composed of glass fiber and unsaturated polyester resin composites(GFRP composites). In this study, the effect of applied load and sliding speed on friction and wear characteristics of these materials were investigated at ambient temperature by pin-on-disc friction test. The cumulative wear volume, friction coefficient and wear rate of these materials for SiC abrasive paper were determined experimentally. The cumulative wear volume showed a tendency to increase nonlinearly with increase of sliding distance and was dependent on applied load and sliding speed for these composites. The friction coefficient of GFRP composites was increased as applied load increased at same sliding speed in wear test. It was verified by SEM photograph of worn surface that major failure mechanisms were microfracture, deformation of resin, cutting and cracking.