• Journal of Institute of Control, Robotics and Systems
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• v.9 no.10
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• pp.798-807
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• 2003

We propose a blind mobile robot force control algorithm that uses force information as a guidance toward to the goal position. Based on the mobile robot dynamics, the control law is formed from explicit force errors. Simulation studies are conducted based on the kinematics and the dynamics of the mobile robot. Simulation results show that good force tracking can be achieved. In order to confirm simulation results, experiments are performed. The robot is commanded to follow unknown environment with maintaining a certain desired force. Experimental results show that the blind mobile robot successfully maintains contact with a regulated desired force and arrives at the goal position.

• Korean System Dynamics Review
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• v.5 no.1
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• pp.99-110
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• 2004

Building trust assurance particularly in case of commercial practices in cyber space without physical contact is a very complex task to tackle. Several factors are interrelated in not necessarily technical but also societal dimensions over the entire process of e-commerce firm ex-ante through ex-post transactions. This paper attempts first to brief the substance of e-trust and examine the natuure of its complexity by using system dynamics simulation technique, followed by its current address and the future directions to move. A framework of 3 x 3 matrixes is deviaed and the key issues of e-trust are mapped into cross-cells of the table. The paper also includes some possible suggestions on the matter of trust assurance especially for B2C and B2B in policy wise and organizational perspective from the context of international collaboration.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.175-180
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• 2002

Loading/Unloading(L/UL) mechanism has been considered to be an alternative to contact start-stop(CSS) mechanism which eliminates stiction and wear associated with frequent start and stop process. It has other advantages including increased areal density due to lower flying height, reduced power consumption, and improved shock resistance. In order for L/UL to be Implemented in Near-field recording system properly, dynamics of optical flying head must be understood and optimized. In this paper the dynamic characteristics during loading process is analyzed numerically to investigate the effect of design parameters such as loading speed. slider shape, and initia conditions on the dynamic reponses of flying head..

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.887-892
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• 2004

In this paper, the activity of Japanese researchers relating multibody dynamics is introduced. The author stayed at the CCR(Center for Collaborative Research) in the university of Tokyo as a visiting scholar during December 10, 2003 to March 9, 2004. The information obtained from several universities (University of Tokyo, Sophia university, Nihon university, Tsukuba university), several industries and research institutes (JR Central in Nagoya, Toyota Research Center in Nagoya., Subway department in Tokyo, and JARI at Tsukuba), several research groups (JSCM, JSME, JSAE) was summarized with several photos. Professor Yoshihiro Suda's laboratory at the university of Tokyo, professor Yoshiaki Terumichi's laboratory at the Sophia university, and professor Ichiro Kageyama's laboratory at the Nihon university are introduced.

• Journal of the Korean Society for Precision Engineering
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• v.11 no.2
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• pp.85-94
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• 1994

The cutting mechanism of ultrasonic vibration machining is characterized as two phases, that is, an impact at the cutting edge and a reduction of cutting force due to non-contact interval between tool and workpiece. In this paper, in order to identify cutting dynamics of a system with ultrasonically vibrated cutting tool, an ARMA modeling is performed on experimental cutting force signals which have a dominant effect on cutting dynamics. The aim of this study is, through Dynamic Date System methodology, to find the inherent characteristics of an ultrasonic vibration cutting process by considering natural frequency and damping coefficient. Surface roughness and stability of cutting process under ultrasonic vibration are also considered

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.5
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• pp.111-116
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• 2018

Thermal fusion bonding is a method to enclose open microchannels fabricated on polymer chips for use in lab-on-a-chip (LOC) devices. Polymethyl methacrylate (PMMA) is utilized in various biomedical-microelectromechanical systems (bio-MEMS) applications, such as medical diagnostic kits, biosensors, and drug delivery systems. These applications utilize PMMAs biochemical compatibility, optical transparency, and mold characteristics. In this paper, we elucidate both the conformational entanglement of PMMA molecules at the contact interfacial regime, and the qualitative nature of the thermal fusion bonding phenomena through systematic molecular dynamics simulations.

• Bulletin of the Korean Chemical Society
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• v.19 no.2
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• pp.178-183
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• 1998

Carbon-13 CP-MAS NMR techniques were used to investigate dynamics of new combined type liquid crystalline polymers, poly[oxy-1,4-phenyleneoxy-2-{6-(4-(4-butylphenylazo)phenoxy)hexyloxy}terephthaloyl] and poly[oxy-1,4-phenyleneoxy-2-{10-(4-(4-butylphenylazo)phenoxy)decyloxy}terephthaloyl]. Noticeable mobility change of either aromatic groups or methylene groups is not detected between 25 ℃ and 82 ℃ from 13C spinlattice relaxation time in the rotating frame (T1ρ(C)) and contact time array experiments. However, line shape analysis shows the increase of mobility of methylene carbons in poly[oxy-1,4-phenyleneoxy-2-{6-(4-(4-butylphenylazo)phenoxy)hexyloxy}terephthaloyl] at higher temperature. The dynamics of side chanis does not seem to be affected in our experimental temperature range by the length of aliphatic chain which is connecting the side chain group to the main chain.

• Proceedings of the KSR Conference
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• 2009.05b
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• pp.225-230
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• 2009

From the view point of railway vehicle dynamics, the interaction between wheel and rail have an huge effect on the behavior of the vehicle. This phenomenon is an unique motion, only for railway vehicles. Furthermore, close investigation of the backgrounds of the interaction is the key to estimate the dynamic behavior of the vehicle, successfully. To evaluate the model including flexible bodies such as car body and catenary system of the next generation express train, it is necessary to develop proper dynamic solver including a wheel rail contact module. In this study, wheel-rail contact module is developed using the general purpose dynamic solver. First of all, the procedure for calculation of the wheel-rail contact force has been established. Generally, yaw angle of the wheelset is ignored. Sets of information are summarized as tables and splined for further uses. With this information, normal force and creep coefficient can be extracted and used for FASTSIM algorithm, which has been shown good reliability over years. Normal force and longitudinal, lateral force at the contact surface are also calculated. Those data are verified by commercial railway simulation program 'VAMPIRE'. This procedure and program can offer a basic process for estimation of the dynamic behavior and wear of the wheel-rail system, even while running on the curved rail. Finally, multi-dimensional inspection tool will be developed including the prediction of the derailment.

• Proceedings of the KSME Conference
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• 2005.11a
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• pp.56.1-56.1
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• 2005

• KSTLE International Journal
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• v.3 no.2
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• pp.79-83
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• 2002

Sealing an oil-air mixture plays important roles to have an enhanced lubrication for high speed spindle. High speed spindle requires non-contact type of sealing mechanism. Current work emphases on the investigation of the air jet effect on the protective collar type labyrinth seal. To improve the sealing capability of conventional labyrinth seal, air jet was injected against through the leakage flow, It has a combined geometry of a protective collar type and an air jet type. Both of a numerical analysis by CFD (Computational Fluid Dynamics) and experimental measurements are carried out to verify sealing improvement The sealing effects of the leakage clearance and the air jet magnitude are studied in various parameters. The results of pressure drop in the experiment match reasonably to those of the simulation by introducing a flow coefficient Effect of sealing improvement is explained as decreasing of leakage clearance by air jetting. Thus, sealing effect is improved by amount of air jetting even though clearance becomes larger.