• International Journal of Precision Engineering and Manufacturing
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• 제3권2호
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• pp.87-94
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• 2002

This paper presents the synchronous vibration control of a rotor system using an Active Air Bearing(AAB). In order to suppress the synchronous vibration, it is necessary to actively control the air film pressure or the air film thickness. In this study, active pads are used to control the air film thickness. Active pads are supported by the pivots containing piezoelectric actuators and their radial positions can be actively controlled by applying voltage to the actuators. Disturbances and various kinds of external forces can cause the shaft vibration as well as the change of the air film thickness. The dynamic behaviors of a rotary system supported by two tilting-pad gas bearings and its active stabilization using the tilting-pads as actuators are investigated numerically. The PID controller is applied to the tilting-pad gas bearing system with three pads, two of which contain piezoelectric actuators. To test the validity of the theoretical method, the performance of this control method is evaluated through experiments. The experimental results show the effectiveness of the control system for suppressing the unbalanced response of the rigid modes.

• 한국정밀공학회지
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• 제18권8호
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• pp.32-39
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• 2001

This paper presents the synchronous vibration control of a rotor system using an Active Air Bearing(AAB). In order to suppress the synchronous vibration, it is necessary to actively control the air film pressure or the air film thickness. In this study, active pads are used to control the air film thickness. Active pads are supported by the pivots containing piezoelectric actuators and their radial positions can be actively controlled by applying voltage to the actuators. Disturbances and various kinds of external force can cause the shaft vibration as well as the change of the air film thickness. The dynamic behaviors of a rotary system supported by two tilting-pad gas bearings and its active stabilization using the tilting-pads as actuators are investigated numerically. The PID controller is applied to the tilting-pad gas bearing system with three pads, two of which contain piezoelectric actuators. To test the vapidity of the theoretical method, the performance of this control method is evaluated through experiments. The experimental results show the effectiveness of the control system for suppressing the unbalanced response of the rigid modes.

• 한국식품영양학회지
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• 제15권4호
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• pp.289-294
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• 2002

본 연구에서 선발된 17종의 천연물을 Sprague-Dawleyra rat에 급여한 결과, 체중증가, 에너지 소비, fat pads 중량, 간의 triglyceride함량, atherogenic index 그리고 혈중 글루코오스의 함량 등이 감소하는 경향을 나타내었다. 특히 동아를 구강으로 섭취시킨 결과, 체중증가, 에너지 소비, fat pads 중량, 그리고 혈중 글루코오스의 함량 등이 감소하였으나, 간의 triglyceride 함량은 오디와 송엽의 열수 추출물보다 적게 감소하였다. 동아, 오디, 그리고 송엽을 혼합하여 사용한 결과, 각각의 원효를 사용할 경우보다 비만이 개선되는 것으로 나타났다.

• 한국정보처리학회논문지
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• 제7권7호
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• pp.2179-2187
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• 2000

This paper provides a heuristic analysis technique which determines an optimal number of V\ulcorner/V\ulcorner pads meeting allowable Simultaneous Switching Noise(SN) budget, early in the design phase. Until now, in determining the number of V\ulcorner/V\ulcorner pads, designers had to simulate packaging models case by case in the design phase or roughly allocate the power/ground pins in an inaccurate way according to typical design rules. However, due to the high density and frequency trends of IC technologies, the V\ulcorner/V\ulcorner pads allocation method can affect an adverse effect on IC operations, which requires more accurate and efficient methods be devised. Thus, this paper proposes an analytic V\ulcorner/V\ulcorner pads calculation method that gives a practical help for packaging designs early in the design phase. The proposed method is applied to a design example of a 1/8x208 pin plastic quad flat package (PQFP) and the results are verified through simulation using HSPICE.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.1730-1733
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• 2007

As semiconductor and MEMS devices become smaller, testing process during their production should follow such a high density trend. A circuit inspection tool "probe card" makes contact with electrode pads of the device under test (DUT). Nowadays, electrode pads are irregularly arranged and have height difference. In order to absorb variations in the heights of electrode pads and to generate contact loads, contact probes must have some levels of mechanical spring properties. Contact probes must also yield a force to break the surface native oxide layer or contamination layer on the electrodes to make electric contact. In this research, new vertical micro contact probe with bellows shape is developed to overcome shortage of prior work. Especially, novel bellows shape is used to reduce stress concentration in this design and stopper is used to change the stiffness of micro contact probe. Variable stiffness can be one solution to overcome the height difference of electrode pads.

• 한국염색가공학회지
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• 제26권3호
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• pp.151-158
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• 2014

The oil sorption capacities and biodegradability of nonwoven fabrics(pads) of PP and PP/kapok(10/90wt%) blend prepared in this study and commercial pad(T2COM: 100% PP) were compared. The biodegradability(58.5%) of PP/kapok(10/90wt%) blend pad was about 5times higher than those(11%) of PP and T2COM pads after 45days. The oil sorption rates of oil sorbent pads for various oils(diesel, lubricant and Bunker C oils) were markedly increased with increasing dipping time up to about 5min and then levelled off. The oil sorption rate and oil sorption capacity were found to increase in the order of PP/kapok(10/90wt%) blend>PP>commercial(T2COM) and Bunker C>lubricant>diesel.

• Animal cells and systems
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• 제16권6호
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• pp.479-487
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• 2012

Biological attachment device is optimized in insect legs for attachment onto the variety of natural substrate. We have studied the microstructural characteristics of the tarsal appendages in the ladybug Harmonia axyridis using scanning electron microscopy to reveal the attachment system of their legs. The attachment devices are composed of claws and adhesive pads. The claws are connected with pretarsal segment, and their apical diverged hooks are developed to hold rough substrates. In contrast, the adhesive pads have an adhesive function onto smooth surface. The pads are interspersed at the ventral part of each tarsomere, and are composed of two kinds of hairy setae. The discoid tip seta (DtS) has a spoon-shaped endplate usually with a rounded concave structure, whereas the pointed tip seta (PtS) has a pointed tip, usually with a hooked endplate. While the PtS is broadly localized concentrically on the marginal area of both the proximal and distal pads, the DtS can be seen at the central areas of each adhesive pad except for the hind legs. Our findings demonstrate the presence of the direction-dependence pattern of the fibrillar system as well as a functional modification of the tenent setae to achieve proper contact with almost any kind of substrates.

• 대한기계학회논문집A
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• 제26권4호
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• pp.711-719
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• 2002

This paper presents the synchronous vibration control of a rotor system using an active air bearing(AAB). In order to suppress the synchronous vibration, it is necessary to actively control the air film pressure or the air film thickness. In this study, active pads are used to control the air film thickness. Active pads are supported by pivots containing piezoelectric actuators and their radial position can be actively controlled by applying voltage to the actuators. Thus, disturbances, i. e. various kinds of external force can cause shaft vibration as well as change of the air film thickness. The dynamic behavior of a rotary system supported by two tilting-pad gas bearings and its active stabilization using the tilting-pads as actuators are investigated numerically. The $\mu$ synthesis are applied to the AAB system with three pads, two of which contain piezoelectric actuators. To test the validity of the theoretical method, the performance of this control method is evaluated through experiments. The experimental results also show the effectiveness of the control system for suppressing the unbalanced response of the rigid modes.

• 한국기계가공학회지
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• 제18권10호
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• pp.54-59
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• 2019

The final reduction drive in tactical vehicles has a wear-pad that helps to maintain adequate end floating when the hub assay operates. The input axis and sun gear move repeatedly with the axis when tactical vehicle is operating. The hub assay is designed so that the wear pads won't seize during operation. Seizure of the wear pads during operation results in oil leakage. In our study, the fault mechanism was analyzed to prevent the seizure of the wear pads and an optimal design for the shape and material of the wear-pad was explored. We then observed the changes in temperature, shape, and material of several important parts.

• 풍력에너지저널
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• 제14권4호
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• pp.13-20
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• 2023

A self-climbing crane (SCC) system is under development for the installation and maintenance of wind turbines. It can move vertically along the wind turbine tower by itself. One of the key components of the SCC system is the clamping pad to maintain a safe position on the wind turbine tower. The SCC system can maintain its position on the tower from the frictional force generated between the surfaces of the clamping pads and the tower. If the frictional force provided by the clamping pads are insufficient, the SCC system cannot stay in the vertical position on the tower. Therefore, the development of clamping pads with sufficient frictional force is very important for the SCC system. At the same time, the operation of the SCC system should not damage the paint coating of the wind turbine tower. In order to verify that the frictional force is sufficient and that frictional and compressive forces do not cause damage to the paint, a number of combined compression and shear loading tests were conducted using a test device prepared for this study. The details regarding the test specimens, test procedure, and test results are summarized in this paper.