• The Journal of Korean Physical Therapy
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• v.21 no.3
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• pp.75-80
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• 2009

Purpose: The purpose of this study was to examine the effect of an obstacle height on the balance control of older adults while stepping over an obstacle from a position of quiet stance. Methods: Fifteen community-dwelling healthy older adults (mean age, $74.4\pm4.27$ yrs; age range, 67-82 yrs) volunteered to participate in this study. The subjects performed gait initiation (GI) and they stepped over obstacles of two different heights (10 cm and 18 cm) at a self-paced speed from a position of quiet stance. Their performance was assessed by recording the changes in the displacement of the COP in the anteroposterior (A-P) and mediolateral (M-L) directions using a force platform. Results: The M-L displacement of the COP significantly increased for an 18 cm obstacle height condition as compared to the GI and a 10 cm obstacle height condition (p<0.01). Furthermore, the M-L displacement of the COP for a 10 cm high obstacle was significantly greater for that for the GI (p<0.01). However, the mean of the A-P displacement of the COP was similar between the stepping conditions for the A-P displacement of the COP (p>0.05). Conclusion: This study suggests that the M-L COP displacement could be a better parameter to identify the dynamic balance control in older adults when negotiating obstacles.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.04a
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• pp.453-458
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• 2011

Air preheater uses the waste heat of the gas which burnt from the boiler from the thermal power plant. Air preheater it is established in the exit of the boiler follows in change of temperature combustion gas and the vibration which it follows in thermal expansion and contraction occurs. Air preheater with ruse the gas the seal the place where it includes a gap in the structure which it does, the vibration which it follows in change of temperature fluctuates the displacement of gap, fluctuation of the leakage quantity which occurs from gap there is a possibility of decreasing an effect to system. Part system it will be able to control the interval of gap in order, control mechanism about under establishing the place where it does the gap control actively, measures a gap the displacement sensor for is necessary. Like this displacement sensor the condition must do continuous running from atmosphere of high temperature was demanded all. This paper investigates the implementation instance of hazard existing which implement the high temperature displacement sensor, it analyzes, produces the result which it examines a model, it was a presentation. These results with the fact that it will contribute in the research for the implementation and a localization of the high temperature displacement sensor and advanced air preheater.

• The Journal of Korean Academy of Prosthodontics
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• v.14 no.1
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• pp.55-65
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• 1976

The influences of the mandibular displacement and valium administration on the muscular activity were observed by spectrophotometric analysis of glycogen, glucose, G-6-P, lactate, pyruvate, ATP, phosphocreatine ana protein. Experimental animals were divided into three groups; the first was the mandibular displacement group, the second was valium administered group and the third was the mandibular displacement and valium admministered group. In mandibular displacement group, the high inclined plane with a gap of 2.5mm to 3.0mm between the upper and lower incisors was created by setting the silver crowns on the lower incisors. By creating such a high inclined plane, the bite was opened and the mandible was dispalced posteriorly. In valium administered group, 5mg/kg body weight of valium was administered intraperitoneally every day until the animal was sacrificed. Results were as follows: I) The body weight of all experimental rats was decreased in the beginning of experimental periods. The body weight of the mandibular displacement group showed the similar increasing rate as the control group from 15 days of experimental period. 2) The superficial masseter muscles of the mandibular displacement group appeared to be decreased it's functional activity at 36hrs, 60hrs and 96hrs of experimental periods as revealed by the decrease of various metabolites studied in this experiment. From 96hrs of experimental periods, the contents of those metabolites tended to increase up to the control level. 3) The superficial masseter muscle of 2nd group showed the decreased value of all metabolites at until 60hrs and the values were recovered to almost the same as the control at 168hrs. 4) Glycogen and G-6-P contents induced by mandibular displacement plus valium administration, showed longer duration of the decreased value than 1st group. And the decrease of glucose and pyruvate contents induced by mandibular displacement at 36hrs and 60hrs of experimental periods was enhanced by valium administration. However, the contents of lactate in 3rd group were decreased continuously until the end of experiment.

• The Journal of Engineering Geology
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• v.17 no.2 s.52
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• pp.197-204
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• 2007

Tunnel deformation happens by excavation. After installation of support, tunnel is gradually stabilized over time. Effect of excavation on tunnel behavior decreases as increase of distance from face. If the time that the displacement converges by tunnel stabilization is estimated, processes after stabilization can be advanced and economic loss can be reduced. In this study, the distance of displacement convergent point from face in the tunnel constructed on sedimentary rock is estimated using control chart method. As the results of analysis using a control of chart, displacements in a sedimentary rock tunnel are converged within 100 m from each tunnel face.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.272-276
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• 1996

This study deals with the speed control of an overcentered variable-displacement hydraulic motor on a constant pressure network, which is noted for its high system efficiency fast dynamic response and energy recovery capability. The speed control characteristics of the conventional cascade PI controller are largely affected by load-torque disturbances. To obtain robust speed control despite torque disturbances, the load torque is estimated by an observer based on a mathematical model and compensated for by a feedforward loop. It is shown by experiment that robust speed control may be obtained with the proposed controller. The experimental data agree fairly well with the theoretical analysis.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.4 s.97
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• pp.46-56
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• 1999

A semi-actively controlled impact system which adjusts an impulse exerted by the external impact is studies. The main control variables are internal pressure difference inside the cylinder and the shock absorber displacement while it travels. Compared to a conventional one so called a passive system with a variable orifice inside the cylinder, a semi-actively controlled system utilizes an external orifice controlled by a highly fast responding electrical proportional valve. This device overcomes the temperature and viscosity change due to continuous operating and keeps the desired pressure difference and displacement in every operation. In this article a new prototype impact system is designed and manufactured based on a semi-actively control system. Through computer simulations and experiments, we verify the possibility of controlling the shock absorber pressure and displacement. After investigating the control performance a modified semi-actively controlled system with better control performance is also proposed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.756-759
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• 2004

We present a piezoelectric actuator using stiffness control and stroke amplification mechanism in order to make large lateral displacement. In this work, we suggest stiffness control approach that generates lateral displacement by increasing the vertical stiffness and reducing the lateral stiffness using additional structure. In addition, an additional structure of a serpentine spring amplifies the lateral displacement like leverage structure. The suggested lateral PZT actuator (bellows actuator) consists of serpentine spring and PZT/electrode layer which is located at the edge of the serpentine spring. The edge of the serpentine spring prevents the vertical motion of PZT layer, while the other edge of the serpentine spring makes stroke amplification like leverage structure. We have determined dimensions of the bellows actuator using ANSYS simulation. Length, width and thickness of PZT layer are 135$\mu$m, 20$\mu$m and 0.4$\mu$m, respectively. Dimensions of the silicon serpentine spring are thickness of 25$\mu$m, length of 300$\mu$m, and width of 5$\mu$m. The bellows actuator has been fabricated by SOI wafer with 25$\mu$m-top silicon and 1$\mu$m-buried oxide layer. The bellows actuator shows the maximum 3.93$\pm$0.2$\mu$m lateral displacement at 16V with 1Hz sinusoidal voltage input. In the frequency response test, the fabricated bellows actuator showed consistent displacement from 1Hz to 1kHz at 10V. From experimental study, we found the bellows actuator using thin film PZT and silicon serpentine spring generated mainly laterally displacement not vertical displacement at 16V, and serpentine spring played role of stroke amplification.

• Journal of Korean Association for Spatial Structures
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• v.20 no.4
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• pp.83-91
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• 2020

In this study, a tuned mass damper(TMD) was installed to control the displacement response to earthquakes by generalizing to six analysis models according to the shape of the upper structure based on the case of various large spatial structures around the world. The six analysis models are ribbed type, latticed type, elliptical type, gable type, barrel type, and stadium type composed of 3D arch trusses. In this paper, ribbed type, latticed type and elliptical type were analyzed. The mass of each TMD was set to 1% of the total structural mass. Result of analyzing the optimal number and position of the analysis model, the displacement response control was the most excellent in the model with 6 and 8 TMDs, and the displacement response decreased in most cases. The displacement response control was better with installing the TMD at the edge point than focusing the TMD at the center of the analysis model. However, when 10 or more TMDs are installed or concentrated in the center, large loads intensively act on the structure, resulting in increased displacement. Therefore, although it is slightly different depending on the shape, it is judged that the displacement response control is the best to install 6 and 8 TMDs at the close to the edge point.

• Journal of Korean Association for Spatial Structures
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• v.20 no.4
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• pp.73-81
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• 2020

In this study, a tuned mass damper(TMD) was installed to control the displacement response to earthquakes by generalizing to six analysis models according to the shape of the upper structure based on the case of various large spatial structures around the world. The six analysis models are ribbed type, latticed type, elliptical type, gable type, barrel type, and stadium type composed of 3D arch trusses. In this paper, ribbed type, latticed type and elliptical type were analyzed. The mass of each TMD was set to 1% of the total structural mass. Result of analyzing the optimal number and position of the analysis model, the displacement response control was the most excellent in the model with 6 and 8 TMDs, and the displacement response decreased in most cases. The displacement response control was better with installing the TMD at the edge point than focusing the TMD at the center of the analysis model. However, when 10 or more TMDs are installed or concentrated in the center, large loads intensively act on the structure, resulting in increased displacement. Therefore, although it is slightly different depending on the shape, it is judged that the displacement response control is the best to install 6 and 8 TMDs at the close to the edge point.

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.165-168
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• 2006

Due to the distinct advantages of comfort, drive ability and fuel economy standard, the variable displacement swash plate type compressor which can control the compressor displacement by increasing of reducing the swash plate angle has developed for automotive air-conditioning system. That can be obtained constant temperature of car room on the variation cooling capacities of engine speeds. In this paper we investigated the improvement of internally controlled variable displacement swash plate compressor on noise.