• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 1998.10a
• /
• pp.99-105
• /
• 1998

Simulation modeling has become an extremely important approach to analyzing complex system. In recent years the number of people using simulation as problem-solving aid has increased. In this Paper, we developed a simulation model for analyzing the physical distribution system in ports. we used Arena 2.2 which is a kind of simulation software based common simulation language, SIMAN V. And then, we applied this model to kwangyang port(partially) and analyzed the effect of it upon port system in according to change of the quantity of goods transported.

• 한국전산유체공학회:학술대회논문집
• /
• 2003.10a
• /
• pp.207-208
• /
• 2003

Increasing interest in indoor air quality (IAQ) control has been found because of its serious effect on human health. To evaluate IAQ, thermal comfort in terms of temperature and velocity distributions of indoor air has to be analyzed in detail. Choice of location for installation of air-conditioner in a building will affect the performance of cooling effect and thermal comfort on the occupants, which in turn will affect the indoor air quality (IAQ) of the building. In this paper, we present a discussion on the proper location of the air-conditioner in order to obtain good thermal comfort for occupant of a typical bedroom in Macao. A set of carefully designed numerical experiments is run with the Computational Fluid Dynamics (CFD) software FLOVENT 3.2 [1]. Reynolds averaged Navier-Stokes equations are solved with finite volume technique and turbulence effects upon the mean flow characteristics is modeled with the k - & model. Assumption of steady state environment is made and only convective and conductive heat transfer from the occupant and air-conditioner are being concerned.

• 한국전산유체공학회:학술대회논문집
• /
• 2007.10a
• /
• pp.49-55
• /
• 2007

The quality of chaotic mixing in three-dimensional micro channel flow has been numerically studied using Fractional-step method (FSM) and particle tracking techniques such as $Poincar{\acute{e}}$ section and Lyapunov exponents. The flow was driven by pressure distribution and the chaotic mixing was generated by applying alternating current to electrodes embedded on the bottom wall at a first half period and on the top wall at a second half period. The equations governing the velocity and concentration distributions were solved using FSM based on Finite Volume approach. Results showed that the mixing quality depended significantly on the modulation period. The modulation period for the best mixing performance was determined based on the mixing index for various initial conditions of concentration distribution. The optimal values of modulation period obtained by the particle tracking techniques were compared with those from the solution of concentration distribution equation using FSM and CFX software and the comparison showed their good match.

• Proceedings of the KSME Conference
• /
• 2002.08a
• /
• pp.419-422
• /
• 2002

A three-dimensional inlet flow structure inside a microfluidic element has been investigated using a micro-PIV(particle image velocimetry) measurement as well as a numerical analysis. The present study employs a state-of-art micro-PIV system which consists of epi-fluorescence microscope, 620nm diameter fluorescent seed particles and an 8-bit megapixel CCD camera. For the numerical analysis, a commercial software CFD-ACE+(V6.6) was employed for comparison with experimental data. Fixed pressure boundary condition and a 39900 structured grid system was used for numerical analysis. Velocity vector fields with a resolution of $6.7{\times}6.7{\mu}m$ has been obtained, and the attention has been paid on the effect of varying measurement conditions of particle diameter and particle concentration on the resulting PIV results. In this study, the microfluidic elements were fabricated on plastic chips by means of MEMS processes and a subsequent melding process.

• Interaction and multiscale mechanics
• /
• v.3 no.3
• /
• pp.257-266
• /
• 2010

A novel resonance based proximity DC current sensor is proposed. The sensor consists of a piezo sensed and actuated cantilever beam with a permanent magnet mounted at its free end. When the sensor is placed in proximity to a wire carrying DC current, resonant frequency of the beam changes with change in current. This change in resonant frequency is used to determine the current through the wire. The structure is simulated in micro and meso scale using COMSOL Multi physics software and the sensor is found to be linear with good sensitivity.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.12 no.3
• /
• pp.1152-1167
• /
• 2018

In this paper, I propose an application layer cooperative congestion control scheme for safety message broadcast in vehicular networks, called CMS, that adaptively controls a vehicle's safety message rate and transmit timing based on the channel congestion state. Motivated by the fact that all vehicles should transmit and receive an application layer safety message in a periodic manner, I directly exploit the message itself as a means of estimating the channel congestion state. In particular, vehicles can determine wider network conditions by appending their local channel estimation result onto safety message transmissions and sharing them with each other. In result CMS realizes cooperative congestion control without any modification of the existing MAC protocol. I present extensive NS-3 simulation results which show that CMS outperforms conventional congestion control schemes in terms of the packet collision rate and throughput, especially in a high-density traffic environment.

• Journal of Sensor Science and Technology
• /
• v.23 no.1
• /
• pp.24-28
• /
• 2014

A lock-in amplifier was proposed for capacitive sensor applications. This amplifier was based on a general-purpose microcontroller and had only a charge amplifier as analog circuits. All the other functions of lock-in amplifier except for the charge amplifier were implemented with firmware and the internal resources of the microcontroller. A rectangular signal, generated by the microcontroller, was used in a sensor-driving signal instead of a conventional sinusoidal signal. This makes it possible that the phase comparison circuit in the lockin amplifier is made with analog-to-digital converter, a timer and an interrupt controller. Using the oversampling method and the rectangular driving signal, we can make it easy to implement the peak detection function with software and sample the peak-to-peak signal at charge amplifier output. A charge amplifier was proposed to cancel out the base capacitance existing in capacitive sensors structurally. The experimental results show that the lock-in amplifier operating in the supply voltage of 3.0 V cancels out the base capacitance and has good linearity.

• Journal of Sensor Science and Technology
• /
• v.23 no.1
• /
• pp.29-34
• /
• 2014

A dosimeter using tissue-equivalent scintillator by photon-counting method was developed and evaluated in its performance. The dosimeter is portable and can be operated by low power from lap-top computer. A data-acquisition software of the dosimeter system was developed by Labwindows/CVI based on Windows. The energy to channel ratio for energy calibration was 0.839 keV/ch. obtained from pulse height spectrum of $^{137}Cs$ and $^{60}Co$ gamma-ray. Using the dosimeter system, the absorbed dose of environmental radiation in Gyungju was 0.18 ${\mu}Sv/h$.

• Transactions of Materials Processing
• /
• v.24 no.6
• /
• pp.418-425
• /
• 2015

Based on eco-friendly advantages and the enhanced development in the chemical and physical characteristics, liquid silicone rubber (LSR) is widely used in producing precision parts in the automotive, medical, electronics, aeronautical and many other industries. In the current work, a thermoplastic-thermoset multi component injection molding (MCM) was developed for a waterproof automotive connector housing using PBT and LSR resins. Measurements of the rheological characteristics of PBT and LSR were made to improve the reliability of the numerical analysis for the multi component injection process. With the measured viscosity, pvT and curing data, numerical analysis of the multi cycle injection molding was conducted using simulation software (Sigma V5.0).

• Proceedings of the KIEE Conference
• /
• 2004.04a
• /
• pp.62-64
• /
• 2004

This paper presents results of the finite-element(FE) analysis of air-gap flux variation in induction motor when rotor vibration conditions occur. Accurate modelling and analysis of rotor vibration in the machine are developed using FE software packages, and search coils are used for measuring the flux. In the FE analysis, the induction motor with 380 [V], 5 [HP], 4P, 1742 [rpm] ratings is used. The results of FE analysis can be useful for on-line vibration monitoring of the motor.