• Title/Summary/Keyword: second order roll

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Control of a Biped Walking Robot using ZMP Formulation (균형점 정형화를 이용한 이족보행로봇 제어)

  • Lim, Sun-Ho;Kim, Jin-Geol
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.48 no.8
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    • pp.1022-1030
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    • 1999
  • This paper is concerned with the balancing motion formulation and the control of ZMP (zero moment point) for a biped walking robot with balancing joints. The balancing equation of a biped robot can be modeled as the second order non-homogeneous differential equation, which makes it possible to plan the desired trajectories for various gaits or motions. Also, the balancing motion can be defined easily by solving the differential equation without pre-processing or heuristic procedures. The actual experiments are performed on biped walking robot system IWR-III, developed in our Automatic Control Lab. The system has the structure of three pitches in each leg, and one roll and one prismatic type in balancing joints. The walking simulations and the experimental results on IWR-III are shown using the proposed formula and control algorithm.

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Experimental and Improved Numerical Studies on Aerodynamic Characteristics of Low Aspect Ratio Wings for a Wing-In Ground Effect Ship

  • Ahn, Byoung-Kwon;Kim, Hyung-Tae;Lee, Chang-Sup;Lew, Jae-Moon
    • Journal of Ship and Ocean Technology
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    • v.12 no.3
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    • pp.14-25
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    • 2008
  • Recently, there has been a serious effort to design a wing in ground effect (WIG) craft. Vehicles of this type might use low aspect ratio wings defined as those with smaller than 3. Design and prediction techniques for fixed wings of relatively large aspect ratio are reasonably well developed. However, Aerodynamic problems related to vortex lift on wings of low aspect ratio have made it difficult to use existing techniques. In this work, we firstly focus on understanding aerodynamic characteristics of low aspect ratio wings and comparing the results from experimental measurements and currently available numerical predictions for both inviscid and viscous flows. Second, we apply an improved numerical method, "B-spline based high panel method with wake roll-up modeling", to the same problem.

A Study on Activity in Reading of Men in terms of Brain Science

  • Jeong, Dae Keun
    • International Journal of Knowledge Content Development & Technology
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    • v.9 no.1
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    • pp.57-79
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    • 2019
  • This study attempts to seek a solution, in terms of brain science, to stimulate reading activities of men to whom no attention has been given from the field of reading. In order to do so, brain pattern, reading tendency, reading preference, reading effectiveness and influence of reading were analyzed. As a result of the analysis, first, it showed that respondents' characteristics did not affect brain patterns, but school and social influences on reading were found to affect brain patterns. Second, reading propensity according to gender was observed to be different in terms of personal health, personal self - esteem, and cultural artistry. On the other hand, reading effectiveness was found to be different in terms of reading engagement and the willingness to continue reading whereas reading propensity according to the brain pattern was different in books related to humor and family matters. Third, reading satisfaction, reading engagement and willingness to continue reading all were observed to affect the reading activities of men. Suggesting measures to stimulate reading activities of men based on such findings, first, implementing dynamic reading education programs and finding reading models for men are needed. Second, when selecting books for reading program operations, books should be recommended according to gender rather than being selected en bloc by libraries. Third, since reading education at home shows high influences on both male and male-type brain pattern, the starting point of reading education should be made at homes. In particular, fathers, who can become a role model for men, need a reading role model, and reading education programs for fathers are also required.

The Effects of Torsional Characteristics according to Mounting Method of the Frame of a Large-sized Truck on Dynamic Performance (대형트럭 프레임의 결합방법에 따른 비틀림 특성이 동적 성능에 미치는 영향)

  • Moon, Il-Dong;Kim, Byoung-Sam
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.15 no.6 s.99
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    • pp.731-737
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    • 2005
  • This paper evaluates dynamic performance of a cab over type large-sized truck for estimating the effects of frame's torsional characteristics using a computer model. The computer model considers two mounting methods of frame, flange mounting and web mounting. Frame is modeled by finite elements using MSC/NASTRAN In order to consider the flexibility of frame. The torsional test of the frame is conducted In order to validate the modeled finite element model. A load cell is used to measure the load applied to the frame. An angle sensor is used to measure the torsional angle. An actuator is used to apply a load to the frame. To estimate the effects of frame's torsional characteristics on dynamic performance, simulations are performed with the flange mounting and web mounting frame. Simulation results show that the web mounting frame's variations of roll angle, lateral acceleration, and yaw rate are larger than the flange mounting frame's variations, especially in the high velocity and the second part of the double lane course.

A New Type of Active Engine Mount System Featuring MR Fluid and Piezostack (MR 유체와 압전스택을 특징으로하는 새로운 형태의 능동 엔진마운트 시스템)

  • Lee, Dong-Young;Sohn, Jung-Woo;Choi, Seung-Bok
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2009.04a
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    • pp.444-449
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    • 2009
  • An engine is one of the most dominant noise and vibration sources in vehicle systems. Therefore, in order to resolve noise and vibration problems due to engine, various types of engine mounts have been proposed. This work presents a new type of active engine mount system featuring a magneto-rheological (MR) fluid and a piezostack actuator. As a first step, six degrees-of freedom dynamic model of an in-line four-cylinder engine which has three points mounting system is derived by considering the dynamic behaviors of MR mount and piezostack mount. In the configuration of engine mount system, two MR mounts are installed for vibration control of roll mode motion whose energy is very high in low frequency range, while one piezostack mount is installed for vibration control of bounce and pitch mode motion whose energy is relatively high in high frequency range. As a second step, linear quadratic regulator (LQR) controller is synthesized to actively control the imposed vibration. In order to demonstrate the effectiveness of the proposed active engine mount, vibration control performances are evaluated under various engine operating speeds (wide frequency range) and presented in time domain.

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A New Type of Active Engine Mount System Featuring MR Fluid and Piezostack (MR 유체와 압전스택을 특징으로 하는 새로운 형태의 능동 엔진마운트 시스템)

  • Lee, Dong-Young;Sohn, Jung-Woo;Choi, Seung-Bok
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.19 no.6
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    • pp.583-590
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    • 2009
  • An engine is one of the most dominant noise and vibration sources in vehicle systems. Therefore, in order to resolve noise and vibration problems due to engine, various types of engine mounts have been proposed. This work presents a new type of active engine mount system featuring a magneto-rheological (MR) fluid and a piezostack actuator. As a first step, six degrees-of freedom dynamic model of an in-line four-cylinder engine which has three points mounting system is derived by considering the dynamic behaviors of MR mount and piezostack mount. In the configuration of engine mount system, two MR mounts are installed for vibration control of roll mode motion whose energy is very high in low frequency range, while one piezostack mount is installed for vibration control of bounce and pitch mode motion whose energy is relatively high in high frequency range. As a second step, linear quadratic regulator (LQR) controller is synthesized to actively control the imposed vibration. In order to demonstrate the effectiveness of the proposed active engine mount, vibration control performances are evaluated under various engine operating speeds(wide frequency range) and presented in time domain.

A Multistage In-flight Alignment with No Initial Attitude References for Strapdown Inertial Navigation Systems

  • Hong, WoonSeon;Park, Chan Gook
    • International Journal of Aeronautical and Space Sciences
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    • v.18 no.3
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    • pp.565-573
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    • 2017
  • This paper presents a multistage in-flight alignment (MIFA) method for a strapdown inertial navigation system (SDINS) suitable for moving vehicles with no initial attitude references. A SDINS mounted on a moving vehicle frequently loses attitude information for many reasons, and it makes solving navigation equations impossible because the true motion is coupled with an undefined vehicle attitude. To determine the attitude in such a situation, MIFA consists of three stages: a coarse horizontal attitude, coarse heading, and fine attitude with adaptive Kalman navigation filter (AKNF) in order. In the coarse horizontal alignment, the pitch and roll are coarsely estimated from the second order damping loop with an input of acceleration differences between the SDINS and GPS. To enhance estimation accuracy, the acceleration is smoothed by a scalar filter to reflect the true dynamics of a vehicle, and the effects of the scalar filter gains are analyzed. Then the coarse heading is determined from the GPS tracking angle and yaw increment of the SDINS. The attitude from these two stages is fed back to the initial values of the AKNF. To reduce the estimated bias errors of inertial sensors, special emphasis is given to the timing synchronization effects for the measurement of AKNF. With various real flight tests using an UH60 helicopter, it is proved that MIFA provides a dramatic position error improvement compared to the conventional gyro compass alignment.

Flight Dynamic Identification of a Model Helicopter Using CIFER® (III) - Transfer Function Analysis - (CIFER ® 를 이용한 무인 헬리콥터의 동특성 분석 (III) - 전달함수 해석 -)

  • Bae, Yeong-Hwan;Koo, Young-Mo
    • Journal of Biosystems Engineering
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    • v.37 no.3
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    • pp.192-200
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    • 2012
  • Purpose: Aerial application of chemicals with an agricultural helicopter allows for precise and timely spraying and reduces working labor and pollution. An attitude controller for an agricultural helicopter would be helpful to aerial application operator. The objectives of this paper are to determine the transfer function models and to estimate the handling qualities of a bare-airframe model helicopter. Methods: Transfer functions of a model unmanned helicopter were estimated by using NAVFIT and DERIVID modules of the $CIFER^{(R)}$ program to the time history data of frequency sweep flight tests. Control inputs of the transfer functions were elevator, aileron, rudder and collective pitch stick positions and the outputs were resulting on-axis movements of the fuselage. Results: Minimum realization of the transfer functions for pitch rate output to elevator control input and roll rate output to aileron control input produced second order transfer functions with undamped natural frequencies around 3.0 Hz and damping ratios of 0.139 and 0.530, respectively. The equivalent time delays of the transfer functions ranged from 0.16 to 0.44 second. Sensitivity analysis of the proposed parameters allowed derivation of minimal realization of the transfer functions. Conclusions: Handling quality of the model helicopter was addressed based on the eigenvalues of the transfer functions, corresponding undamped natural frequencies with damping ratios. The equivalent time delays of the lateral-directional motion ranged from 0.16 to 0.44 second, longer than the 0.1 to 0.15 second requirement for well-controlled typical manned aerial vehicles.

A Study on the Costume of the Gods in the Ancient Roman Myths (고대 로마 신화에 등장한 신들의 복식 연구)

  • 임상임;추미경
    • Journal of the Korean Society of Clothing and Textiles
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    • v.25 no.5
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    • pp.945-956
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    • 2001
  • The costume for gods in the Ancient Roman myth was studied by examining in the embossed-carving, sculptures, mural-painting and various documents of the period. The clothes item, hairstyle, symbol & ornaments and shoes of the gods in the Roman myths were analyzed to understand the formative process in the religious costumes, and results are as follows. First, the costumes for male gods are the same as those for ordinary men lived in ages, including toga, paludamentum, tebenna, tunica. The costumes for female gods are also the same as those for ordinary women lived in ages, including stola, palla, tunica. Second, the hairstyle of male gods is short curled-hair, twisty roll-up hair and braid long-hair due to the influence of Etrurian in the early days. Another hairstyle is appeared in form of the laurelled-crown. The hairstyle of female gods is curled long-hair, chignon style and braid roll-up hair decorated with hairband. Third, the symbol & ornaments which represent the responsible possession of male gods, are appeared in beard, a stick of the message, arrow-case, offering-dish, antlered-glass, shield, spear-handle, as the superhuman forms, such as the lightning shape. For female gods they are is appeared plastron, a stick of the message, flower. some female gods wear necklace, foot-ring, bracelet. Fourth, male gods wear shoes in forms of sandal, buskin, boots, but all female gods are in barefoot. It could be explained by the fact that a man-centered society in the ancient roman is reflected in the world of gods. As mentioned, Gods costume in Roman myths was very similar to or nothing different from the ordinary peoples in Rome. However, they used corps, sacrifices or sepcific symbols depending on the fields that they were responsible for in order to be distinguished from the ordinary people. This is the result from the peoples expression that they should keep a close relationship with Gods hoping to be protected, and rely on them under whatever circumstances.

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A study on the problems in appling CIF, Incoterms 1990 into the contract of sale. (1990년(年) 인코텀즈에 따른 CIF조건(條件)의 활용상(活用上)의 문제점(問題點))

  • Choi, Myung-Kook
    • THE INTERNATIONAL COMMERCE & LAW REVIEW
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    • v.6
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    • pp.11-51
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    • 1993
  • This study is focused on the problems and the suggestions of proper ideas for solving them which are arisen from appling CIF, Incoterms 1990 into the contract of sale after reviewing of the contents of traditional CIF contract and the main changes of CIF, Incoterms 1990. This study summerized as follows: First, when the seller provide the buyer with non-negotiable sea waybill or inland waterway document instead of negotiable bill of lading, it is my feeling that the essence of symbolic delivery in traditional CIF contract is fading. And if the buyer has paid for the goods in advance, or a bank wishes to use the goods as security for a loan extended to the buyer, it is not sufficient that the buyer or the bank be named as consignee in a non-negotiable document. This is true because the seller by new instractions to the carrier could replace the named consignee with someone else. To protect the buyer or the bank it is therefore necessary that the original instructions from the seller to the carrier to deliver the goods to the named consignee be irrevocable. Second, CIF term can only be used for sea and inland waterway transport. When the ship's rail serves no practical purposes such as in the case of roll-on/roll-off or container traffic, CIP term instead of CIF term is more appropriate to use. Third, the EDI method still contains many legal and technical problems to be solved in order to be used thoroughly' in the international sale of goods. Therefore, the parties wishing to replace the traditional paper-based trade documents by electronic messages must exchange the agreement on EDI each other in order to prevent and sol ye unexpected problems. Forth, it may be that the goods are to be carried in bulk without such marking or naming of consignee as would amount to appropriation. Then the risk will not pass until effective appropriation has been made. Therefore, the seller needs to appropriate by issuing of separate bills of lading or delivery orders for parts of the bulk cargo. And in case the goods are bought while they are carried at sea, some problems on the passing of risk would arise. One possibility is that the buyer might have to assume risks which have already occured at the time when the contract of sale is entered into force. The other possibility would be to let the pissing of the risk concide with the time when the contract of sale is concluded. The parties are advised to ascertain the applicable law and any solution which might follow there form. Finally, Incoterms are restricted to deal with the main principles for the division of functions, costs and risks between the parties and the rest is left to their individual contract as supplemented by the custom of the trade, the individual terms of the contract of sale and the applicable law. Thus, the parties are advised to ascertain the applicable law on their individual contract of sale in order to solve the problems on the transfer of property, the remedy and so on.

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