• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.8
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• pp.1376-1382
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• 2016

The discharge characteristics of inductively coupled $Ar/CH_4$ plasma were investigated by fluid simulation. The inductively coupled plasma source driven by 13.56 Mhz was prepared. Properties of $Ar/CH_4$ plasma source are investigated by fluid simulation including Navier-Stokes equations. The schematics diagram of inductively coupled plasma was designed as the two dimensional axial symmetry structure. Sixty six kinds of chemical reactions were used in plasma simulation. And the Lennard Jones parameter and the ion mobility for each ion were used in the calculations. Velocity magnitude, dynamic viscosity and kinetic viscosity were investigated by using the fluid equations. $Ar/CH_4$ plasma simulation results showed that the number of hydrocarbon radical is lowest at the vicinity of gas feeding line due to high flow velocity. When the input power density was supplied as $0.07W/cm^3$, CH radical density qualitatively follows the electron density distribution. On the other hand, central region of the chamber become deficient in CH3 radical due to high dissociation rate accompanied with high electron density.

• Journal of Korea Multimedia Society
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• v.19 no.11
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• pp.1871-1877
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• 2016

In this paper, a Wireless USB (WUSB) protocol is adopted for development of ASMD (Adaptive Source Multi Device) N-screen wireless services. WUSB is the USB technology merged with WiMedia PHY and Distributed-MAC (D-MAC). However, the current WUSB protocol can't provide seamless N-screen streaming services to moving WUSB devices in home network environment. Therefore, to provide the ASMD N-screen services through WUSB based on D-MAC protocol, a channel management scheme is proposed to support seamless mobility between adjacent ASMD groups for wireless IPTV N-screen services. In simulation results, proposed ASMD channel management (ACM) scheme is compared with conventional WUSB channel management scheme in view points of throughput, average path interference and energy consumption according to various numbers of nodes and elapsed simulation times. Through simulation results, it is explained that proposed ASMD channel management (ACM) scheme should be adopted in the WUSB protocol to realize ASMD N-screen wireless services.

• ETRI Journal
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• v.31 no.3
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• pp.342-344
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• 2009

From a hydrodynamic device simulation for the pseudomorphic high electron mobility transistors (pHEMTs), we observe an increase of maximum extrinsic transconductance and a decrease of source-drain capacitances. This gives rise to an enhancement of the switching speed and isolation characteristics as the upper-to-lower planar-doping ratios (UTLPDR) increase. On the basis of simulation results, we fabricate single-pole-double-throw transmitter/receiver monolithic microwave integrated circuit (MMIC) switches with the pHEMTs of two different UTLPDRs (4:1 and 1:2). The MMIC switch with a 4:1 UTLPDR shows about 2.9 dB higher isolation and approximately 2.5 times faster switching speed than those with a 1:2 UTLPDR.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.5
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• pp.834-840
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• 2001

A real time multibody vehicle dynamics model has been developed and implemented using a subsystem synthesis method based on recursive formulation. To verify real time simulation capability the developed model has been applied to HMMWV(High Mobility Multipurpose Wheeled Vehicle) with steering system. For the kinematically driven steering system, the coupled front suspension-steering subsystem can be decoupled into two SLA suspension subsystems, which improves the efficiency of simulation. To investigate theoretical efficiency, operational counting method has been also employed to compare the proposed model with the conventional recursive dynamics model. Various simulations such as unsymmetric bump run, step steering(J-turn) and sine steering input test have been carried out to verify the real time feasibility of the proposed model.

• Bulletin of the Korean Chemical Society
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• v.21 no.9
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• pp.875-881
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• 2000

We study the rheological properties of concentrated polymer solution and the melt under simple shear and elon-gational flow using Brownian dynamicssimulation. In order to describe the anisotropic molecular motion, we modifiedthe Giesekus' mobility tensor by incorporating the finitely extensible non-linear elastic (FENE) spring force into dumbbell model. To elucidate the nature of this model, our simulation results are compared with the data of FENE-P ("P"standsfor the Perterin) dumbbell model and experiments. While in steady state both original FENE and FENE-P models exhibit a similar viscosity response,the growthof viscosity becomes dissimilar as the anisotropy decreases and the flowrate increases. The steady state viscosity obtained from the simulation well describes the experiments including the shear-thinning behavior in shear flow and viscosity-thinning behavior in elongational flow. But the growth of viscosity oforiginal FENE dumbbell model cannot describe the experimental results in both flow fields.

• Journal of KIISE:Computing Practices and Letters
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• v.6 no.4
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• pp.411-420
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• 2000

The performance of soft handoffs of CDMA mobile communication systems is potentially determined by several factors such as handoff-related system parameters (T_ADD, T_DROP, T_COMP, T_TDROP), mobile stations' mobility, service areas, capacity of base stations. Due to the importance of handoffs in mobile communications, several methods have been proposed and tested through computer simulations to prove the efficiency of proposed methods. Different assumptions on the above mentioned factors often produce different simulation results. Therefore, the credibility of a simulation result is directly determined by the objectivity of the assumptions made by the simulation. This paper proposes a new soft handoff method that controls handoff delay time based on a mobile station's speed, and compares it with the current method of CDMA systems. The simulation results showed that the new method is much more efficient for mobile stations that are free in their moving direction and space than for those restricted in their moving direction and space. In addition, the results showed that even the same handoff method may produces different simulation results depending on whether a service area is modeled as two-dimensional space or three-dimensional space. These results indicate the importance of suitable models of user mobility, especially the movement types and space allowed for mobile stations, which have been neglected in simulation studies of mobile communications.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.04a
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• pp.76-81
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• 2002

The characteristics of the track are important concerning the mobility of tracked vehicles. It can be represented in terms of the track tension and maintaining the track tension adequately guarantees the stable and improved driving of the tracked vehicles. The track tension must be known in order to be controlled and it needs to be estimated in real-time because it is difficult to be measured. The tension around idler and sprocket can be controlled by the frizzy logic control system base on the estimated values. Dynamic Track Tensioning System(DTTS) which is estimating and controlling the track tension. In this paper, simulation tool is developed in order to apply the DTTS to real battle tanks. To construct the simulation tool, the Modeling the tracked vehicle, constructing estimation system, and designing controller should be achieved first and then all subsystem should be organized in one. The simulation tool make the RecurDyn model of tracked vehicle, which is plant model, and the control system exchange their data simultaneously. Simulation with many kinds of driving conditions and road conditions is carried out and the results are interpreted. The interpretation provides necessary information to apply the DTTS to real battle tanks.

• The Journal of Korean Institute for Practical Engineering Education
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• v.3 no.1
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• pp.15-24
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• 2011

Modeling and simulation for Green Energy depends largely on the type of system under investigation. The topics are very wide ranging from semiconductor physics (solar), electrical motor/generator (wind turbines), power electronics (grid connections) to typical control strategies. To correctly model these technologies requires a broad set of models and various simulation techniques. To further refine or detail the simulation the modeling has to be performed on a specific level, being system, circuit or component level. Combinations of several levels allows gradually improving the validity of the overall model against available parameters and model equations.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.10
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• pp.119-126
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• 2007

Recently, the mobility of users and mobile communication technologies have developed rapidly. The users in this state also want to connect their devices and to receive services anywhere, anytime. Hierarchical Mobile IPv6 (HMIPv6) has been proposed by the Internet Engineering Task Force (IETF) to compensate for such problems as handover latency and signaling overhead when employing Mobile IPv6 (MIPv6). HMIPv6 supports micro-mobility within a domain and introduces a new entity, namely Mobility Anchor Point (MAP) as a local home agent. However, HMIPv6 has been found to cause longer handover latency when the inter-domain handover occurs. This is because a Mobile Node (MN) has to generate two addresses and register them to Home Agent (HA) a MAP, respectively. In order to solve such problems, we propose a scheme that an MN generates one address and registers it to HA for supporting fast handover during the inter-domain handover process. In the proposed scheme, the load of MAP and MAP domain is reduced because the number of MNs which are managed by MAP is decreased and the MAP does not perform proxy Neighbor Discovery Protocol (NDP) to intercept packets destined to MNs. We evaluate the performance of proposed scheme in comparison to HMIPv6 through the simulation and numerical analysis.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.22 no.1
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• pp.311-326
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• 2023

This paper proposes a plan to improve the installation and operation of traffic safety facilities using a microscopic simulation by confirming the difference in the perception method and range of autonomous vehicles and human vehicles. In this study, the existing 『Traffic Safety Sign Installation·Management Guidelines』 was reviewed, and safety signs among traffic safety facilities were classified according to changes in vehicle behavior. Subsequently, for the classified facilities, the installation location of the traffic sign was changed through simulation experiments, and the optimal location was inferred to suggest an improvement plan. This study confirmed how traffic safety facilities installed based on the visibility of human drivers affect road efficiency and safety in mixed traffic flow with autonomous vehicles and human-controlled vehicles. The optimal location derived through this study is meaningful because it can be used as the basis for revising the guidelines on the installation and management of traffic safety facilities.