• 대기
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• 제24권4호
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• pp.555-563
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• 2014

The impacts of dynamic and thermodynamic schemes used in the Community Ice CodE (CICE), the Los Alamos sea ice model, on sea ice concentration, extent and thickness over the Arctic and Antarctic regions are evaluated. Using the six dynamic and thermodynamic schemes such as sea ice strength scheme, conductivity scheme, albedo type, advection scheme, shortwave radiation method, and sea ice thickness distribution approximation, the sensitivity experiments are conducted. It is compared with a control experiment, which is based on the fixed atmospheric and oceanic forcing. For sea ice concentration and extent, it is found that there are remarkable differences between each sensitivity experiment and the control run over the Arctic and Antarctic especially in summer. In contrast, there are little seasonal variations between the experiments for sea ice thickness. In summer, the change of the albedo type has the biggest influence on the Arctic sea ice concentration, and the Antarctic sea ice concentration has a greater sensitivity to not only the albedo type but also advection scheme. The Arctic sea ice thickness is significantly affected by the albedo type and shortwave radiation method, while the Antarctic sea ice thickness is more sensitive to sea ice strength scheme and advection scheme.

• Steel and Composite Structures
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• 제32권6호
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• pp.753-767
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• 2019

Vibration control in mechanical equipments is an important problem where unwanted vibrations are vanish or at least diminished. In this paper, free vibration active control of the porous sandwich piezoelectric polymeric nanocomposite microbeam with microsensor and microactuater layers are investigated. The aim of this research is to reduce amplitude of vibration in micro beam based on linear quadratic regulator (LQR). Modified couple stress theory (MCST) according to sinusoidal shear deformation theory is presented. The porous sandwich microbeam is rested on elastic foundation. The core and face sheet are made of porous and three-phase carbon nanotubes/resin/fiber nanocomposite materials. The equations of motion are extracted by Hamilton's principle and then Navier's type solution are employed for solving them. The governing equations of motion are written in space state form and linear quadratic regulator (LQR) is used for active control approach. The various parameters are conducted to investigate on the frequency response function (FRF) of the sandwich microbeam for vibration active control. The results indicate that the higher length scale to the thickness, the face sheet thickness to total thickness and the considering microsensor and microactutor significantly affect LQR and uncontrolled FRF. Also, the porosity coefficient increasing, Skempton coefficient and Winkler spring constant shift the frequency response to higher frequencies. The obtained results can be useful for micro-electro-mechanical (MEMS) and nano-electro-mechanical (NEMS) systems.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.325-328
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• 1997

In this paper the modeling and control of a twin roll strip caster is investigated. Mathematical models for the strip casting process are obtained by analyzing five critical areas such that the molten steel level in the pool, solidification process, roll separating force and torque, roll dynamics including hydraulic actuators, and roll drive system. A two-level control strategy is proposed. At lower level, three local subsystems are independently feedback-controlled by suitable local controllers which perform well to the behaviors of each subsystem. They are a variable structure control of the molten steel level in the pool, an adaptive predictive control of the roll gap which is directly related to the strip thickness, and an $H^{\infty}$ control of the roll drive system. At higher level, all reference signals to the lower level subsystems are generated by an optimal controller in the perspective of regulating the strip thickness and roll separating force. Simulations are provided..

• 한국안전학회지
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• 제9권1호
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• pp.68-75
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• 1994

The cetylpyridium ion-selective electrode were developed by dibenzo-18-crown-6 for auto control of the chemical plants. The effect of content of active material and the membrane thickness on the response characteristics of electrode such as the linear reponse range, the detection limit, and Nemstian slope of the electrod, were studied. The electrode characteristics was better with decreasing the content of active material above the optimum content, but became worse below these. DBP was best as a plasticizer, The effect of the membrane thickness on the electrode characteristics was improved with decreasing the membrane thickness, but below the optimum membrane thickness the electrode exhibited an inverse trend.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 춘계학술대회 논문집
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• pp.528-532
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• 1997

The structure of satellite was of six parts of control system, power system, thermal control system, remote measurement command system, propellant system and thrust system. In these parts, propellant system consists of propellant tank and thrust device. What we want to perform is optimum design to minimaize the weight of propellant tank. In order to design optimal propellant tank, several parameters should be adopted form the tank geometry like the relative location of the lug and variation of the wall thickness. So the analysis was executed by finite element analysis for finding optimal design parameters. The structure was devided into 3 parts, the initial thickness zone, the transitional zone, and the weak zone,whose effects on the pressure vessel strength was investigated. Finally the optimal lug location and the three zone thickness were obtained and the weight was compared with the uniform thickness vessel.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.40-40
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• 2000

Generally a RF AGC controls the roll gap using the variation of rolling force caused by the roll eccentricity and the entry thickness of material, but these can not be classified. The Feed- forward AGC method, which controls the next stand roll 9ap by estimation the skid mark of the previous stand output thickness is needed to supplement the shortage of RF AGC. In this paper, an improved filtering method of skid mark which take account of the kinds of materials, the final objective thickness and the roll speed is proposed, In addition, an improved estimation method of control point using the speedometer and looper angle is suggested, Via simulation, the performance improvement of the suggested FF AGC method is verified.

• Design & Manufacturing
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• 제13권1호
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• pp.31-35
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• 2019

For manufacturing upper housing product of mechanical control valve, the progressive drawing process was conducted experimental. Then, the center of the product was cut to measure the thickness of the product. As a result, the following conclusions were obtained. By means of a stand-alone pad provided with sufficient pressure, it is possible to prevent the occurrence of wrinkles in the die pad product of the drawing process. As a result of the experiment, it was considered that the flange bottom of the product and the lower edge of the product are made thick in thickness, the top edge and the top surface are thin. It is considered that this is due to the size and roughness of the entrance edge radius of the die in the drawing process, and the inflow of the material by the die pad.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.323-323
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• 2000

In the tandem cold wiling mill, the quality is very in portant, and requirements for thickness accuracy become more strict. However, the mathematical model for prediction of rolling force was not considered an elastic deformation at the entry and delivery side of the contacted area between the worked roll and rolling strip so that there was so difficult to control of the thickness. To overcome this problem, the mathematical model included an elastic deformation of strip has been developed and applied to the field in order to predict the rolling force. The simulated results showed that the end of elastic recovery should be included the model, even if the effect of elastic compression was not important.

• 대한치과보철학회지
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• 제32권2호
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• pp.212-224
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• 1994

The purpose of this study was to evaluate and compare film thickness of five kinds of resin luting cements [Comspan, Panavia Ex, Maryland bridge adhesive, All-bond C & B cementation kit, and Super-bond C & B]. Zinc-phosphate cement and glass-ionomer cement were used as the control group. In order to measure the film thickness the methods used were in broad compliance with ADA Specification No. 8, a tapered-die system that simulates clinical conditions more closely, and the connected tapered-die system that simulates bridge conditions. The inorganic filler size of resin cements was also examined with scanning electron micrographs. The results were obtained as follows ; 1. The film thickness of resin cements was increased in the order of Comspan, Panavia Ex, Super-bond C & B, Maryland bridge adhesive, and All-bond C & B cementation kit. Maryland bridge adhesive and All-bond C & B cementation kit showed significantly higher film thickness than the control group(p<0.01). 2. For all resin cements, there was a significant difference of film thickness between the ADA method and the tapered-die system. Generally, the tapered-die system demonstrated lower film thickness than the ADA method(p<0.01). 3. There was no significant difference in film thickness between the tapered-die system and the tapered-die bridge system in all resin cements(p<0.01). 4. The scanning electron microscope showed that the cement with larger filler had a tendency to be higher in film thickness.

• 대한물리의학회지
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• 제14권4호
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• pp.195-201
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• 2019

PURPOSE: This study aimed to quantify the effects of whole body vibration (WBV) stimulation training on the muscle thickness and gross motor function in children with spastic cerebral palsy. METHODS: Twenty children diagnosed with spastic cerebral palsy were assigned randomly to the Whole Body Vibration (WBV) group (n=10) and control group (n=10). The WBV group received vibration therapy including five different therapy, and the control group received only five general physiotherapy sessions. After 10 weeks of intervention, the muscle thickness was measured using ultrasound, and the Gross Motor Function D and E items were evaluated. RESULTS: After the intervention, both groups showed a significant increase in muscle thickness and gross motor function (p<.05). The WBV group showed a significant increase in the quadriceps femoris and tibialis anterior muscles compared to the control group, whereas no significant increase in the gastrocnemius muscle was observed (p<.05). The WBV group showed significant improvement in the Gross Motor Function D and E scores compared to the control group (p<.05). CONCLUSION: WBV training may be a useful way of improving the lower extremity muscle strength in children with spastic cerebral palsy, which may help improve the gross motor function.