• 항공우주시스템공학회지
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• 제2권3호
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• pp.1-6
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• 2008

The tilt rotor aircraft has the flight characteristics which takes off vertically like a helicopter and flies forward like an airplane. Especially, the transition process from a helicopter to an airplane mode requires not only the mixing of control inputs but also the stability and controllability augmentation system(SCAS) in order to keep the safe flight because there are compound flight dynamic characteristics of a helicopter and an airplane including non-linearity, uncertainty. This paper describes the design of SCAS in a lateral motion for the tilt rotor aircraft based on the $H_{\infty}$ control method, which was performed from mathematical model with weighting matrix based on the relationship between the $H_{\infty}$ norm and the sensitivity function. Through simulation analysis for the controller designed on the $H_{\infty}$ control theory, it was shown that this method may be applied to the control design of the tilt rotor aircraft.

• 한국정보처리학회논문지
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• 제7권3호
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• pp.756-765
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• 2000

In this paper, a korean text to sign language translation system is designed and implemented for the hearing impaired people to learn letters and to have a conversation with normal people. We adopt the direct method for machine translation which uses morphological analysis and the dictionary search. And we define the necessary sign language dictionaries. Based on this processes, the system translate korean sentences to sign language moving picture. The proposed dictionaries are composed of the basic sign language dictionary, the compound sing language dictionary, and the resemble sign language dictionary. The basic sign language dictionary includes basic symbols and moving pictures of korean sign language. The compound sing language dictionary is composed of key-words of basic sign language. In addition, we offered the similar letters at the resemble sign language dictionary. The moving pictures of searched sign symbols are displayed on a screen in GIF formats by continuous motion of sign symbols or represented by the finger spelling based on the korean code analysis. The proposed system can provide quick sign language search and complement the lack of sign languages in the translation process by using the various sign language dictionaries which are characterized as korean sign language. In addition, to represent the sign language using GIF makes it possible to save the storage space of the sign language. In addition, to represent the sign language using GIF makes it possible to save storage space of the sign language dictionary.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1995년도 춘계학술대회
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• pp.235-238
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• 1995

In this paper, we propose an effective coding method of the angiography by using the scalable structure in the frequency domain for MPACS(Medical Picture Archiving and Communication System). We employed the subband decomposition method and MPEG-2 system which is the international standard coding method of the general moving picture. After the subband decomposition is applied to split an input image into 4 bands in the spatial frequency domain, the motion compensated DPCM coding method of MPEG-2 is carried out for each subband. As a result, an easily controllable coding Structure is accomplished by composing the compound hit stream for each subband group. Follows are the simulation results of the proposed sheme for the angiography. A scalable structure which can be easily controlled for a loss of transmission or the band limit can be accomplisbed in the MPEG-2 stucture by the subband decomposition minimizing the side information. And by reducing the search area of the motion vector between -4 and 3, the processing speed of a codec is enhanced by more than two times without a loss of the picture quality compare with the conventional DCT coefficients decompositon method. And the processing speed is considerably improved in the case of the parallel construction of each subband in the hardware.

• 대한기계학회논문집A
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• 제29권2호
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• pp.188-200
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• 2005

Control of a multi-fingered robotic hand is usually based on the theoretical analysis for kinematics and dynamics of fingers and of object. However, the implementation of such analyses to robotic hands is difficult because of errors and uncertainties in the real situations. This article presents the control method for estimating the kinematic constraint of an unknown object by active sensing. The experimental system has a two-fingered robotic hand suspended vertically for manipulation in the vertical plane. The fingers with three degrees-of-freedom are driven by wires directly connected to voice-coil motors without reduction gears. The fingers are equipped with three-axis force sensors and with dynamic tactile sensors that detect slippage between the fingertip surfaces and the object. In order to make an accurate estimation for the kinematic constraint of the unknown object, i.e. the constraint direction and the constraint center, four kinds of the active sensing and feedback control algorithm were developed: two position-based algorithms and two force-based algorithms. Furthermore, the compound and effective algorithm was also developed by combining two algorithms. Force sensors are mainly used to adapt errors and uncertainties encountered during the constraint estimation. Several experimental results involving the motion of lifting a finger off an unknown object are presented.

• 한국수소및신에너지학회논문집
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• 제4권1호
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• pp.11-19
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• 1993

The kinetic studies of the hydrogen induced amorphization in $ErCo_2$ Laves phase is observed by the internal standard method using X-ray diffraction intensities. The activation energy and rate constant exponent for the amorphization in $ErCo_2$ are found to be 26 kcal/mole and 0.78, respectively. From these results, it is believed that the mechanism of the hydrogen induced amorphization in $ErCo_2$ is related to the motion of Co atoms. Though there are many similar physical properties between $ErCo_2$ and $ErNi_2$, the activation energy for the amorphizatin in $ErCo_2$ is larger than that in $ErNi_2$ and the amorphization rate in $ErCo_2$ is slower. It is suggested that these differences of activation energy for the hydrogen induced amorphization and the amorphization rate between $ErCo_2$ and $ErNi_2$ is due to the occurence of structural change on forming crystalline hydride.

• 한국생산제조학회지
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• 제23권1호
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• pp.7-14
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• 2014

The core of the automotive industry's strategy to handle the climate change can be explained as the development and distribution of the vehicles with high fuel efficiencies and low emission. Clean Diesel, hydrogen fuel cell, electric, and especially hybrid power-train vehicles have been actively studied. This paper dynamically analyzes the performance of a hybrid system's five driving modes. The research subject consists of one engine, two electric motors, two simple planetary gears, and one compound planetary gears with five clutches. To define the steady state equation of the system, interaction formulas of five driving modes are introduced with motion variables and torque variables. These formulas are then used to analyze the speeds, torques, and power flows of each mode.

• 한국생산제조학회지
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• 제24권1호
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• pp.1-6
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• 2015

To improve the efficiency of a reverse engineering process, many researches have recently tried to develop efficient, automatic 3D scanning devices. A new automatic 3D scanning device using a spherical coordinate system mechanism is introduced in this study. This device incorporates a guide motion along the spherical coordinate to compound each 3D data point automatically. The experiments correlating the system assembling tolerance with the form accuracy were conducted to verify the efficiency of the system for the scanning of an object, including complex shapes and manifold sections. In addition, the required time and system accuracy, taken during the scanning process of complicated artifact models, were investigated. Further, based on these empirical results, it was ascertained that the superior productivity of this new device offers a more precise and efficient scan when compared to conventional methodologies.

• 한국자동차공학회논문집
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• 제3권1호
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• pp.33-44
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• 1995

As the occupant safety receives more attention from automobile industries. protection systems have been developed quite well. Developed protection systems must be evaluated through real tests in crash environment Since the real tests are extremely expensive. computer simulations are replaced for some prediction of the real test In the computer simulation. it is very crucial to express the real environment precisely in the modeling precess. The energy absorbing(EA) steering system has a very important rote in vehicle crashes because the occupant can hit the system directly. In this study. the EA steering system is modeled precisely. analyzed for the safely and designed by an optimization technology. First. the EA steering system is disassembled by parts and modeled by segments and joints. The segments are modeled by rigid bodies in motion and they have resistances in contact. Spring-damper elements and force-deflection curves are utilized to represent the joints. The body block test is cal lied out to validate. the modeling. When the test results are not enough for the detailed modeling. the differences between tests and simulations are minimized to calculate unknown parameters using optimization. The established model is applied to a crash simulation of a full-car model and tuned again. After the modeling is finished. components of the steering system are designed by an optimization algorithm. In the optimization process. the compound injury of a driver is defined and minimized to determine the chracteristics of the components. The second. order approximation algorithm has been adopted for the optimization.

• 한국안전학회지
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• 제9권1호
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• pp.100-109
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• 1994

In this study, it is investigated that the possibility of the numerical simulation for the incineration of the hazardous material, crbon tetrachloride($CCl_4$). A 3-dimensional numerical technology is applied for turbulent reacting flows of the full-scale Dow Chemical incinerator. The calculations are made by a CRAY-2S, super computer. The major parameters considered in this study are kiln revolution rate (rpm), filling ratio of the solid waste(f), burner Injection velocity and angle, and turbulent air jets for swirl. And the employed turbulent reaction model is the eddy break-up model which is a kind of fast chemistry model assuming general equilibrium and used for a premixed flame. The calculated flow fields are presented and discussed. 1) The presence of turbulent air nozzles for swirl gives rise to visible increase of the convective motion over the region of the solid waste. This implies the possibility to enhance the mixing of the waste with the surrounding all and thereby to reduce thermal and species stratification, which were reported in a large rotary kiln operation. 2) Considering that the location of the recirculation region has a strong relation with the heating rate of the solid waste, the control of the recirculation region by the burner injection angle Is quite desirable in the sense of the flexible design of the rotary kiln incinerator for a carbon tetrachloride. 3) Finally, it is found that the eddy break-up model Is not suitable for carbon tetrachloride($CCl_4$) because this model is not incorporated the flame inhibition trend due to the presence $CCl_4$compound.

• Journal of Electrical Engineering and Technology
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• 제13권2호
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• pp.1008-1020
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• 2018

In this paper, the dynamic compliance and its compensation control of the force control system on the highly integrated valve-controlled cylinder (HIVC), the joint driver of the hydraulic drive legged robot, is researched. During the robot motion process, the outer loop dynamic compliance control is applied on the base of hydraulic control inner loop and most inner loop control are the force or torque closed loop control. While the dynamic compliance control effectiveness of outer loop can be affected by the inner loop self-dynamic-compliance. Based on this problem, the dynamic compliance series composition theory of HIVC force control system as well as the analysis of its self-dynamic-compliance is proposed. And then the paper comes up with the compliance-enhanced control, which is a compound compensation control method of dynamic compliance with multiple series branches. Finally, the experiment results indicate that the control method mentioned above can enhance the dynamic compliance of HIVC force control system observably. This provides the compensation control method of inner loop dynamic compliance for the outer loop compliance control requiring the high accuracy and high robustness for the robot.