• Journal of Energy Engineering
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• v.20 no.1
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• pp.1-7
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• 2011

The performance and life-cycle costs of electric vehicle(EV) and hybrid electric vehicle(HEV) depend inherently on battery packs. Temperature uniformity in a pack is an important factor for obtaining optimum performance for an EV or HEV battery pack, because uneven temperature distribution in a pack leads to electrically unbalanced battery cells and reduced pack performance. In this work, a three-dimensional modeling was carried out to investigate the effects of operating conditions on the thermal behavior of a lithium-ion battery pack for an EV or HEV application. Thermal conductivities of various compartments of the battery were estimated based on the equivalent network of parallel/series thermal resistances of battery components. Heat generation rate in a cell was calculated using the modeling results of the potential and current density distributions of a battery cell.

• The Journal of Korean Association of Computer Education
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• v.17 no.2
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• pp.65-76
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• 2014

This paper aims at implementing experimental devices with which middle school students can explore scientific ideas using GoGo Board and NetLogo that connect real and simulated worlds. Related research literature was reviewed to design a simulation-based learning model using computer simulation and robot-related activities. In order to construct devices for exploratory experiments, GoGo Board was adopted for developing the interface of Micro-Based Laboratory(MBL) devices with several sensors while NetLogo was used for connecting MBL devices (real world) and simulated experiments (virtual world). The simulation contents were developed in the area of heat equilibrium for changing temperature and the conduct-current relationship appeared in the textbook of middle school science class. With the developed device and contents students can visualize the change of temperature cold and hot waters in terms of heat equilibrium. They also can measure the change of conductor representing the relationship between conductor and current. The formative evaluation of the contents carried out with several middle school students indicated the future direction for upgrading simulation contents and interface. The results might be beneficial for science educators who want to apply simulation contents with the use of computers.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.3
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• pp.301-307
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• 2011

Turbo blowers are mainly used in refuse collection systems. We discuss blower performance in relation to the angle of the inlet vane installed at the upstream of the blower. The flow characteristics of the components are analyzed by three-dimensional Navier-Stokes analysis and compared to experimental results. A two-stage serially connected turbo blower is introduced to analyze the performance experimentally. Throughout the experimental measurements and the numerical simulation, the distorted inlet velocity generated in the small vane angle reduces the performance of the blower, because of the local leading-edge separation and the resulting non-uniform blade loading. We also perform a detailed flow analysis using the results obtained in the numerical simulation.

• Analytical Science and Technology
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• v.24 no.6
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• pp.429-434
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• 2011

In this study, a wet-sampler was developed for collection in water and simultaneous fractionation of micron-sized particles (e.g., pigment, airborne, etc.). In this new device, three cylinders (partially filled with water) through which air was forced to pass for sample collection are connected in a series. Particles of different sizes are collected in different cylinders, allowing simultaneous fractionation. An uniqueness of this new device is that it does not use any membrane filter. Microparticles are collected directly in cylinders filled partially with water. Also the particles are simultaneously fractionated within this device while they are being collected. The new device was employed for collection of airborne particles. The collected airborne particles were fractionated by using sedimentation field-flow fractionation, SdFFF), and observed with an optical microscopy (OM) for size and shape analysis. Also AAS and ICP-AES were used for composition analysis of the airborne particles. It is expected that the new device is applicable to collection and analysis of size distribution of various types of microparticles.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.1
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• pp.78-84
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• 2010

The efficiency of system with a built-in coil is improved as (1) the total coil flux increases, (2) the space distribution of coil flux is closer to the sinusoidal wave and (3) the direction of coil flux flow becomes more inherent with the original direction at the same condition. Every turn RC(Reinforced Coil) is composed of OC having original region and two IC's strengthening bidirectionally the inner part flux in order to maintain the symmetry with origin. This way we will realize the inherent flux direction and the sinusoidal closeness as well. Accordingly RC type is obtained by connecting the pure OC's and RC's in just turns to be closer to sinusoidal flux wave. We proved experimentally the usefulness of reinforced coil to improve the efficiency of SPIM.

• Journal of Bio-Environment Control
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• v.9 no.4
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• pp.212-222
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• 2000

This study was performed to investigate the performance of heat recovery device attached to exhaust gas flue connected to combustion chamber of greenhouse heating system. The experimental heat recovery system is mainly consisted of LPG combustion chamber and two heat recovery units; unit-A is attached directly to the exhaust gas flue, and unit-B is connected with unit-A. Heat recovery performance was evaluated by estimating total energy amounts by using enthalpy difference between two measurement points together with mass flow rate of gas and/or air passing through each heat recovery unit depending on 5 different flow rates controlled by voltage meter. The results of this experimental study, such as heat exchange behavior of supply air tubes and exhaust air passages crossing the tubes, pressure drop between inlet and outlet, heat recovery performance of exchange unit, etc., will be used as fundamental data for designing optimum heat recovery device to be used for fuel saving purpose by reducing heat loss amounts mostly wasted outside of greenhouse through flue.

• Journal of the Korea Society for Simulation
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• v.21 no.2
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• pp.91-101
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• 2012

Automobile manufacturing consists of body-line, painting-line, and assembly-line. These production lines are disposed in series and go through a flow process, so according to the status of pre & post processing, a suspension happens in a line by a starvation(impossibility of production by insufficient supply) or blocking(impossibility of production by exceed capacity). Therefore, to prevent a loss of production coming from a starvation or blocking, a storage such as WBS or PBS is independently owned and operated. The paper suggests the simulation model of integrated storage which can operate it by integrating each storage performing a role as a buffer of line. Specifically, the paper found the answers about reasonable number of Stacker Crane and AGV(Automatic Guided Vehicle) and suggested a methodology of operation which is available to operate them. Also, it compared an efficiency between a model of current storage and integrated storage through simulation. As a result, it turned out that the model suggested in the paper was more efficient on suspension of painting-line stop than a current storage.

• Journal of Broadcast Engineering
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• v.4 no.2
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• pp.134-143
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• 1999

In this paper, in order to implement the IDWT(inverse discrete wavelet transform) with relatively low complexity, we propose a VLSI architecture for odd-tap linear-phase IDWT filters. By considering the symmetric property of the linear phase filter, the input is added to the one located at symmetrical position of the filter before filtering. Then. we rearrange the delay line of the filter in a U-shaped fashion. requiring no global interconnection between the components. The proposed architecture for the IDWT filter consists of delay units. operator units, adder units. and postprocessor unit. Since each units are configured regularly and interconnected locally. the proposed architecture can accommodate arbitrary linear phase IDWTs by simply adding/removing the corresponding units. The M -level IDWT can be implemented by interconnecting the proposed architecture in a cascaded or semi-recursive form. It is expected that the proposed architecture for the IDWT can be effectively employed in the related area including MPEG-4, since the proposed architecture is less complex than the conventional architectures.

• Journal of Korean Society of Water and Wastewater
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• v.30 no.3
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• pp.271-278
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• 2016

Recently, reverse osmosis (RO) is the most common process for seawater desalination. A common problem in both RO and thermal processes is the high energy requirements for seawater desalination. The one energy saving method when utilizing the osmotic power is utilizing pressure retarded osmosis (PRO) process. The PRO process can be used to operate hydro turbines for electrical power production or can be used directly to supplement the energy required for RO desalination system. This study was carried out to evaluate the performance of both single-stage PRO process and two-stage PRO process using RO concentrate for a draw solution and RO permeate for a feed solution. The major results, were found that increase of the draw and feed solution flowrate lead to increase of the production of power density and water permeate. Also, comparison between CDCF and CDDF configuration showed that the CDDF was better than CDCF for stable operation of PRO process. In addition, power density of two-stage PRO was lower than the one of single-stage. However, net power of two-stage PRO was higher than the one of single-stage PRO.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.10
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• pp.126-134
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• 2006

This paper describes the development of an embedded wireless LAN controller which can be in parallel operated with an existing utility controller. The embedded controller mainly consists of Prism(R) 2.5 chip set and Atmega 128 microcontroller. In order to communicate over the network, the controller including TCP/IP stack (IP, TCP, UDP, and ICMP), telnet, and X/Z modem has been developed. For a specific application, we have proposed an special method to convert data structure between TCP/IP and X/Z modem and a data buffer algorithm to minimize the RAM memory usage. Finally, the correctness and performance of the protocols are tested and verified using $CommView^{(R)}\;and\;DU^{(R)}$. The development is satisfactorily operated only for 3,381 bytes of RAM usage without sacrificing interoperability between hosts.