• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.2
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• pp.16-21
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• 2005

The performance of reciprocating internal combustion engine is a strong function of the air intake system configuration. In order to improve engine power, it is essential to optimize the air induction system. In this study, a numerical investigation has been carried out for the three-dimensional flow and pressure characteristics in air intake system of a large-sized commercial bus. CFD simulations using STAR-CD were also perform ed to evaluate effects of intake duct geometry and structure variation inside air cleaner on the negative pressure distribution of overall intake system. Studies for improving the back pressure distribution have been proposed and quantitatively examined based on intensive case studies.

• Journal of Information Processing Systems
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• v.7 no.1
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• pp.85-92
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• 2011

This paper shows an effective partitioning of static global row/column buses for tightly coupled 2D mesh-connected small processor arrays ("mesh", for short). With additional O(n/m (n/m + log m)) time slowdown, it enables the mesh of size $m{\times}m$ with static row/column buses to simulate the mesh of the larger size $n{\times}n$ with reconfigurable row/column buses ($m{\leq}n$). This means that if a problem can be solved in O(T) time by the mesh of size $n{\times}n$ with reconfigurable buses, then the same problem can be solved in O(Tn/m (n/m + log m)) time on the mesh of a smaller size $m{\times}m$ without a reconfigurable function. This time-cost is optimal when the relation $n{\geq}m$ log m holds (e.g., m = $n^{1-\varepsilon}$ for $\varepsilon$ > 0).

• Proceedings of the KIEE Conference
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• 2001.07d
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• pp.2582-2584
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• 2001

In this paper, this system which constantly control rotation speed of compressor is designed to use in idling state as traffic jam. Also this system is designed to improve reduction of cooling efficiency when sloping and starting a bus. The estimation of designed system in this paper is performed in the laboratory where KS-R-1053 is satisfied. We come to the conclusion that this system is more excellent than the present system in point of cooing ability and response characteristic of controller.

• Journal of Electrical Engineering and Technology
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• v.13 no.1
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• pp.133-142
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• 2018

Paper presents a comparative study of space vector pulse width modulation (SVPWM) switching sequences for Voltage Source Inverters (VSIs). Various SVPWM switching sequences are studied for two and three level VSIs in linear modulation index region. The computations of dwell times are presented for two and three level VSIs based on space vector geometry in a synchronized and optimized manner. The existing SVPWM switching sequences are implemented using Matlab / Simulink and in an experimental setup for three phase two and three level VSIs. The simulation and experimental waveforms of conventional SVPWM (CSVPWM) and bus clamped SVPWM (BCSVPWM) are demonstrated for two and three level inverter respectively. The performance of different SVPWM switching sequences are evaluated and presented based on weighted voltage total harmonic distortion (THD).

• Proceedings of the KIEE Conference
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• 1996.11a
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• pp.80-83
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• 1996

This paper develops a method for reliably estimating an UEP(Unstable Equilibrium Point) which is located in the direction of SEP(Stable Equilibrium Point)'s moving as system load is getting heavy. As power systems are getting loaded heavily, the SEP which is an operable solution, and the UEP which is occurring voltage collapse, are moving toward each other linearly. The estimated UEP is used as a good initial guess for the real UEP. The proposed method is tested by 3 bus system and Stagg 5 bus system. It is demonstrated that the proposed method is very useful for assessing system voltage stability in the case of heavy loaded power system. The result solutions are often used in conjunction with energy methods and the stability margin.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.58-58
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• 2000

Recently low resistance of bus line is required for large screen size RFT-CLD panels. As a result, lower resistance Al-alloy is currently reviewed extensively. The resistivity is required smaller than 10$\mu$$\Omega$cm and high resistance of chemical attack is required. In this paper, Al-W thin film were deposited on glass substrates by D.C magnetron sputtering system under various condition for high chemical resistance. Its properties were characterized by SEM, AFM, XRD, 4-point-probe, and cyclic voltammertry. The optimal condition of Al-W was 10$0^{\circ}C$, 100W, 0.4Pa, 23sccm(Ar) and 35$0^{\circ}C$, 20min. annealing. At that condition the resistivity of Al-W(3 wt.%) was about 11$\mu$$\Omega$cm. And when wt.% of W in Al-W alloy was higher than about 4%, Al-W alloy thin film has high chemical resistance.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.12 no.2
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• pp.27-33
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• 2013

In this study we analyzed the on-road driving performance of two parallel-type diesel-hybrid buses which have been driven in Daegu metropolitan area. A real-time on-board data logger was facilitated to measure the vehicle information such as vehicle speed, idle stop, state of charge of battery, and engine operating conditions. These diesel-hybrid buses ran as a commuter at Daegu Exco area and Dalsung industrial complex. The driving pattern in Exco area comprised more frequent idle stop and relatively lower speed than at Dalsung area, where comprised no idle stop. Due to those different driving patterns, the fuel economy at Dalsung showed $3.7\;km/{\ell}$, which is about 8% higher than that of Exco. The main causes of this come from the higher portion of regenerative braking and higher speed which moves to the operating points of diesel engine with a lower fuel consumption.

• Proceedings of the KSME Conference
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• 2001.06d
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• pp.17-24
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• 2001

To solve the problems of energy and environment conservation issued recently, mainly in mechanical engineering point of view, R&D's on the thermal, fluid and environmental engineering technology have been carried out by two R&D departments in the Korea Institute of Machinery & Materials (KIMM). Now there are 65 researchers in the two. The representative projects in the field of thermal and fluid engineering are development of an inactive gas generator and development of a cryogenic cooler for electronic sensors. Pyrolysis and melting of wastes, gas treatment using nonthermal plasma, and desalination are important technology to be developed in environmental R&D areas. To reduce the emission from the existing diesel engines for buses, an LPG direct injection type of bus engine is being developed supported by LPG supply companies. These several R&D projects which have been carried out in KIMM are introduced briefly.

• Journal of Korea Multimedia Society
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• v.15 no.10
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• pp.1212-1220
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• 2012

In this paper, a collision-free resource reservation scheme for WUSB (Wireless Universal Serial Bus) networks with WiMedia D-MAC (Distributed Medium Access Control). Since distributed characteristic of the WiMedia D-MAC supporting DRP (Distributed Reservation Protocol) scheme may cause lots of conflicts, overall performances of the WUSB with WiMedia D-MAC can be deteriorated. In addition, when we consider multi-hop environment, "mobile" hidden node problem due to mobility of WUSB devices can be happened, and it is a critical problem to mobile WUSB devices transceiving real-time QoS (Quality of Service) traffic. To tackle the problem, we propose a new DRP reservation mechanism to prevent DRP conflicts for multi-hop mobility support in WUSB networks with WiMedia D-MAC and show its improved performance via simulation results.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.12 s.354
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• pp.23-32
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• 2006

Fast and accurate power bus design (FAPUD) method for multi-layers high-speed digital boards is devised for the power supply network design tool for accurate and precise high speed board. FAPUD is constructed, based on two main algorithms of the PBEC (Path Based Equivalent Circuit) model and the network synthesis method. The PBEC model exploits simple arithmetic expressions of the lumped 1-D circuit model from the electrical parameters of a 2-D power distribution network. The circuit level design based on PBEC is carried with the proposed regional approach. The circuit level design directly calculates and determines the size of on-chip decoupling capacitors, the size and the location of off-chip decoupling capacitors, and the effective inductances of the package power bus. As a design output, a lumped circuit model and a pre-layout of the power bus including a whole decoupling capacitors are obtained after processing FAPUD. In the tuning procedure, the board re-optimization considering simultaneous switching noise (SSN) added by I/O switching can be carried out because the I/O switching effect on a power supply noise can be estimated over the operation frequency range with the lumped circuit model. Furthermore, if a design changes or needs to be tuned, FAPUD can modify design by replacing decoupling capacitors without consuming other design resources. Finally, FAPUD is accurate compared with conventional PEEC-based design tools, and its design time is 10 times faster than that of conventional PEEC-based design tools.