• The Transactions of the Korean Institute of Power Electronics
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• v.18 no.4
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• pp.349-358
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• 2013

In this paper, the sensorless MPPT algorithm is proposed where the performance of varied duty ratio change has been improved using multi-layer neuro-fuzzy that aligns with neuro-fuzzy based optimized membership function. Since the change of duty ratio of sensorless MPPT is varied by using the neuro-fuzzy, the MPPT response speed is faster than the convectional method and is able to reduce the steady-state ripple. The neuro fuzzy controller has the response characteristics which is superior to the existing fuzzy controller, because of the usage of the optimal width of the fuzzy membership function. The effectiveness of the proposed method has been verified by simulations and experimental results.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.1867-1870
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• 2003

The analysis and simulation are the method to study the behavior, response, and specification of the driver device. This paper proposes brushless DC drive which using the vector control technique. The encoder is used detect the rotor position and decode to Three-phase step signal. The step signal is modulated with triangle signal and change to the pulse width modulation (PWM) signal. The PWM signal is used for control the input power of the motor based on the vector control technique. The experimental results of the driver circuit and motor response performed under the following condition: as the motor was started, change the load torque, and vary the supply voltage. The experimental performs with a dynamometer and the test results are compared to the simulation method is the same result.

• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.5
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• pp.140-147
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• 2001

The solenoid valve in ABS hydraulics, modulator is a two directional on-off valve and is controlled by around 100Hz high speed pulse width modulation. When the inlet valve is switched from open state to closed state, there are braking force degration, noise and vibration due to pressure surge phenomena in the hydraulic line and wheel cylinder. In this study, identifies pressure surge phenomenon in the braking process of a ABS, and investigates the way to reduce the phenomenon. For the purpose theoretical analysis on the pressure surge in the closed state hydraulic line, characteristic curve method based on wave equation was utilized. During this analysis, we could find pressure surge characteristics change due to hydraulic line change and PWM control conditions. In conclusion, by using the results of this study for the pressure surge prediction and reduction method, we could expect braking performance enhancement in Anti-Lock Braking System.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.6 no.1
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• pp.29-38
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• 1994

Particle contamination into and out of a cavity-cylindrical cavities with aspect ratios(width/depth) less than, equal to 1 and langer than 1, and also three dianensional T's attached to a cylindrical flow tube was studied numerically, using a finite difference method. In the process of unsteady particle diffusion, the particles contained in a concentration boundary layer near the tube wall plays an important role in the initial stage, after which a quasi-steady concentration profile is developed inside the cavity, resulting in an exponential change of concentration with time. Average concentration and its rate of change are observed to be closely correlated by a power law function in terms of Reynolds number and the logarithm of Schmidt number. Effects of the three parameters-Re, Sc, and aspect ratio-are analysed and well explained.

• Journal of the Semiconductor & Display Technology
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• v.2 no.2
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• pp.1-4
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• 2003

We have developed a rotating compensator spectroscopic ellipsometer (RCSE). As the ellipsometry measures a change in the polarization state of a light wave upon non-normal reflection from surface, the degree of sensitivity is enhanced greatly through the detection of relative phase change. RCSE acquires additional information from the non-ideal surface of sample and operates over the photon energy range from 1.5 to 4.5 eV. We applied RCSE to measure the optical properties of films and the line-width of patterned PR films on crystalline silicon.

• Journal of Industrial Technology
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• v.35
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• pp.55-58
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• 2015

Natural shifting of rivers has been disturbed by anthropological activities. Urbanization in Kathmandu has been encroached the natural floodplain of Bagmati and currently channeled by training walls. The study compares the change in shape of Dhobikhola, a small tributary using 1966 and 2014 satellite images. It has been found that the original shape is heavily changed over time at the beginning and end section of river under study. The river width is now fixed by training walls and roads along the banks. Using multiple data sets like satellite images and GIS analysis, these shifts can be easily detected to plan for management and restoration of physical and ecological behaviors of rivers.

• Proceeding of Spring/Autumn Annual Conference of KHA
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• 2004.11a
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• pp.75-80
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• 2004

This study was designed to examine characteristics of apartment floor plans that have been recently available. Content analysis was conducted, and 232 apartment floor plans were examined. This study indicated that the front width and the number of front bays also notably increased. Also, two bathrooms in a unit have been increasing, and three bedrooms were very popular. The conspicuous change of floor plan component is the appearance of entrance lobby. It was noted that dress room and powder room that appeared in a larger unit were adopted in small one. Housing suppliers have continuously attempted to have partial change in unit floor plan to accommodate consumers' diverse needs and lifestyle, Further analysis on our residential culture and continuous study on various development of floor plan types need to be made.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.518-521
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• 2008

When constructing a high-speed railroad, the reduction of the distance between track centers and the width of track bed will save the construction cost. However the shortening the distance between track centers may cause the stability problems due to higher wind pressure. Therefore the extensive technical review and aerodynamical study should be performed to determine the adequate distance between track centers. In this study, the impact that the increase in wind pressure due to the change of aerodynamic phenomena with the change of the distance between track centers may have on two trains passing by each other was predicted, and the stability of train operation was analyzed in order to review the distance between track centers suitable to Honam HSR trains. And we estimated the aerodynamical effects by the results of the real train experiments by using KTX.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.6
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• pp.852-859
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• 2000

The emission in the exhaust gas from diesel engine is effected by the fuel spray characteristics. The spray of D.I. diesel engine impinges on a piston cavity and a cylinder wall. It is very important to know exactly the distribution and behavior of the spray inside cylinder. The objective of this study is to develop more accurate evaporation model. The EPISO code was used to analyze the flow characteristics in the engine. The Wakil model and the Faeth model are applied to the EPISO code to analyze the behavior of impinging spray. And also experimental and numerical analysis were carried out. The spray behavior characteristics were investigated by changing injection pressure, ambient pressure and temperature. The behavior of impinging spray was strongly effected by the change of ambient pressure and temperature. The effects of evaporation and rebounding droplet should be considered.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1736-1740
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• 2003

There have been various studies to find out the correlation between subjective and objective evaluation ride comfort in vehicle. To be proper, subjective evaluation considers the signal pattern of vibration generated by vehicle. In this study, driving test is carried out to extract the correlation between subjective evaluation by subjects and vibration signals measured on the seat when a test vehicle is passing over test bumpers, which have two sorts of width change and height change respectively. A unique reference bumper is used to be compared with the relative comfort of test bumpers.