• Proceedings of the IEEK Conference
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• 2002.06a
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• pp.77-80
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• 2002

In this paper, we analyze a physical layer of W-CDMA .system and design a transmitter and receiver by using ADS (Advanced Design System). Also, we simulated a link level performance with different channel estimation algorithm in Jakes fading channel environment. For the channel estimator, we used the WMSA(Weighted Multi-Slot Averaging) algorithm, EGE(Equal Gain Estimation) algorithm and SSE(Symbol-to-Symbol Estimation) algorithm. This study will be useful in the analysis and design of W-CDMA system.

• Proceedings of the Korea Information Processing Society Conference
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• 2013.05a
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• pp.418-420
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• 2013

Issues on design of routing scheme and routing metric for multicast in multi-channel multi-radio (MCMR) wireless mesh networks (WMNs) are discussed. Emphasis is placed on channel-diversity oriented routing metrics. From case study the conclusion to be drawn is that the key for design of channel-diversity oriented routing metrics is how to construct an optimization function to quantify interdependence between channel assignment and multicast routing throughput.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.14 no.1
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• pp.8-14
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• 2018

Printed circuit heat exchangers (PCHEs) are widely used with an increasing demand for industrial applications. PCHEs are capable of operating at high temperatures and pressure. We consider a PCHE as a candidate intermediate heat exchanger type for a high temperature gas-cooled reactor (HTGR). For conventional application using stainless steels, design and manufacturing of PCHEs are well established. For applications to HTGR, knowledge of longitudinal conduction and deformation of channel is required to estimate design margin. This paper analyzes the effects of longitudinal conduction and deformation of channel on thermal performance using a code internally developed for design and analysis of PCHEs. The code has a capability of two dimensional simulations. Longitudinal conduction is estimated using the code. In HTGR operating condition, about ten percent of design margin is required to compensate thermal performance. The cross-sectional images of PCHE channels are obtained using an optical microscope. The images are processed with computer image process technique. We quantify the deformation of channel with dimensional parameters. It is found that the deformation has negative effect on structural integrity. The deformation enhances thermal performance when the shape of channel is straight in laminar flow regime. It reduces thermal performance in cases of a zigzag channel and turbulent flow regime.

• Structural Engineering and Mechanics
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• v.90 no.2
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• pp.117-125
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• 2024

This article presents the behaviour and design of cold-formed steel (CFS) web-stiffened lipped channel beams that primarily fail owing to the buckling interaction of distortional and global buckling modes. The incorporation of an intermediate stiffener in the web of the lipped channel improved the buckling performance leads to distortional buckling at intermediate length beams. The prediction of the strength of members that fail in individual buckling modes can be easily determined using the current DSM equations. However, it is difficult to estimate the strength of members undergoing buckling interactions. Special attention is required to predict the strength of the members undergoing strong buckling interactions. In the present study, the geometric dimensions of the web stiffened lipped channel beam sections were chosen such that they have almost equal distortional and global buckling stresses to have strong interactions. A validated numerical model was used to perform a parametric study and obtain design strength data for CFS web-stiffened lipped channel beams. Based on the obtained numerical data, an assessment of the current DSM equations and the equations proposed in the literature (for lipped channel CFS sections) is performed. Suitable modifications were also proposed in this work, which resulted in a higher level of design accuracy to predict the flexural strength of CFS web stiffened lipped channel beams undergoing distortional and global mode interaction. Furthermore, reliability analysis was performed to confirm the reliability of the proposed modification.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.3
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• pp.444-451
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• 2007

The design parameters of transmitter and receiver channel systems for COMS, which provides meteorological and ocean data services, were analyzed and the channel design parameters for a proper design of a small user-terminal were proposed in this paper. The COMS transmits the oceanic observation data by using the S/L-band link to the earth station. The meteorological data also are transmitted to the earth station, the meteorological data services, which are processed in the earth station, are provided to user. The sensor data are transmitted as digital signal type and are received by bilateral small-sized user terminals. So the optimal channel system for transmission and reception of sensor data should be designed on the basis of the channel modeling and analyzed results for primary technologies.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.580-584
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• 2004

In the present study, an evaluation technology for heating channel layout was investigated in SMC molding system design. Conventional design rules of cooling channel in injection molding process were applied to the present work. Finite element thermal analysis with ANSYSTM was performed to evaluate the temperature distribution of mold surface. SMC mold was manufactured to test the effect of a proposed heating channel layout system on the temperature distribution of mold surface and infrared camera was applied to a measurement of temperature. It was shown that infrared camera application was possible in a measurement of temperature distribution on mold surface.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.11
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• pp.1267-1273
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• 2009

Hot press forming can produce high-strength components by rapidly cooling between closed punch and die after hot forming using quenchable boron steel austenized in a furnace. In the hot press forming process, the cooling rate is influenced by the size, position and arrangement of the cooling channel and the file condition of cooling water in the die. Also, mechanical properties of the final components and operation time are related to cooling rate. Therefore, the design of optimized cooling channel is one of the most important works. In this paper, the effect of position and size of the cooling channel on the cooling rate was investigated by using design of experiment and FE analysis in hot press bending process. Therefore the optimum cooling channel ratio was presented in the HPB.

• New & Renewable Energy
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• v.5 no.1
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• pp.18-25
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• 2009

PEMFC (Proton Exchange Membrane Fuel Cell) is a low temperature fuel cells which are high efficient and clean energy. But it has many problems like economical efficiency or durability. Because of this reason, many researchers challenge various view points. One of challenge is the flow channel design and many researchers develop new flow channel design. In addition to most of them have the anode and cathode's flow channel overlapped almost perfectly. In this case, the electrochemical reaction is almost done by the inertial force of flow. So we study on the effect of the anode and cathode's flow channel which aren't overlapped perfectly, have more diffusion effect, to PEMFC performance using CFD.

• Structural Engineering and Mechanics
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• v.77 no.4
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• pp.523-533
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• 2021

The present study investigates the lateral torsional buckling behaviour of pultruded glass fiber reinforced polymer (GFRP) simply supported channel beams subjected to uniform bending about their major axis. A parametric study by varying the sectional geometry and span of channel beams is carried out by using ABAQUS software. The accuracy of the FE models was ensured by verifying them against the available results provided in the literature. The effect of geometric nonlinearity, geometric imperfections, and the dependency of finite element mesh on the lateral torsional buckling were carefully considered in the FE model. Lateral torsional buckling (LTB) strengths obtained from the numerical study were compared with the theoretical LTB strengths obtained based on the Eurocode 3 approach for steel sections. The comparison between the numerical strengths and the design procedure proposed in the literature based on Eurocode 3 approach revealed disagreements. Therefore, a simplified improved design procedure is proposed for the safe design strength prediction of pultruded GFRP channel beams. The proposed equation has been provided that might aid the structural engineers in economically designing the pultruded GFRP channel beams in the future.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.4
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• pp.2860-2867
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• 2015

Stable channel design is to determine the width, depth and slope for satisfying the condition that the upstream incoming sediment rate is equal to the sediment transport rate at the design channel. Therefore, the most sensitive variable when designing a stable channel is the selection of a sediment transport equation applied for the channel design. Especially if in the case of gravel beds the designer uses the equation developed by using the data of sand rivers, the calculation result of the stable channel section has large errors. In this study, the stable channel design has been applied to the gravel bed river using the previous stable channel design program with newly added the sediment transport equation for gravel beds; and the stable channel section considering design constraints has been produced by using the analytical method. As results, in the case of the application with the fixed width, the depth predicted by Ackers and White's equation was the shallowest and Meyer-Peter and $M\ddot{u}ller's$ equation was 0.8 m deeper than the current section of 2.4 m. In the case of the application with the fixed depth, the width predicted by Engelund and Hansen's equation was twice wider than the current section and by Meyer-Peter and $M\ddot{u}ller's$ equation was 20 m wider than the current section of 44 m.