• International Journal of Automotive Technology
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• v.7 no.5
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• pp.609-618
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• 2006

This paper presents the lateral control of an autonomous vehicle by using a look-ahead sensing system. In look-ahead sensing by an absolute positioning system, a reference lane, constructed by straight lanes or circular lanes, was switched by a segment switching algorithm. To cope with sensor noise and modeling uncertainty, a robust LMI-based $H_{\infty}$ lateral controller was designed by the feedback of lateral offset and yaw angle error at the vehicle look-ahead. In order to verify the safety and the performance of lateral control, a scaled-down vehicle was developed and the location of the vehicle was detected by using an ultrasonic local positioning system. In the mechatronic scaled-down vehicle, the lateral model and parameters are verified and estimated by a J-turn test. For the lane change and reference lane tracking, the lateral controllers are used experimentally. The experimental results show that the $H_{\infty}$ controller is robust and has better performance compared with look-down sensing.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.3
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• pp.206-211
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• 2005

The device makers want to make higher density chips on the wafer through scale-down. The change of WSix/poly-Si gate film thickness is one of the key issues under 100 nm device structure. As a new device etching process is applied, end point detection(EPD) time delay was occurred in DPS+ poly chamber of Applied Materials. This is a barrier of device shrink because EPD time delay made physical damage on the surface of gate oxide. To investigate the EPD time delay, the experimental test combined with OES(Optical Emission Spectroscopy) and SEM(Scanning Electron Microscopy) was performed using patterned wafers. As a result, a EPD delay time is reduced by a new chamber seasoning and a new wavelength line through plasma scan. Applying a new wavelength of 252 nm makes it successful to call corrected EPD in WSix/poly-Si stack-down gate etching in the DPS+ poly chamber for the current and next generation devices.

• Proceedings of the KSRS Conference
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• v.1
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• pp.459-462
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• 2006

The diffuse attenuation coefficient for down-welling irradiance ($K_d$) is an important parameter for ocean studies including remote sensing applications. For the vast ocean, ocean color remote sensing is the only possible means to get the fine-scale measurements of $K_d$. To develop a technique of estimating $K_d$ from remotely sensed data, the following underwater optical parameters (absorption coefficient (a), attenuation coefficient (c), scattering coefficient (b), diffuse attenuation coefficient ($K_d$), etc.) have been studied. For this research we conducted the field campaign around the Yellow Sea at $8{\sim}9$ June, 2006. We obtained a set of underwater optical parameter data: down-welling irradiance ($E_d$), up-welling irradiance ($E_u$) and up-welling radiance ($L_u$) using TriOS optical sensors and a, c coefficient using Spectral Absorption and Attenuation Meter (AC-S). We then derived $K_d$ values from $E_d$ for each depth.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.33.2-33.2
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• 2011

The 'NREL Phase VI' model with a 10.06m diameter was tested in the NASA Ames tunnel to make a reference data of the computational models. The test was conducted at the one rotational speed, blade tip speed 38m/s and the Reynolds number of the sectional airfoils in that test was around 1E6. The 1/5 scale down model of the 'NREL Phase VI' model was used in this paper to study the power characteristics in low Reynolds number region, 0.1E6 ~ 0.4E6 which is achievable range for the conventional wind tunnel facilities. The torque generated by the blade was directly measured by using the torque sensor installed in the rotating axis for a given wind speed and rotational speed. The power characteristics below the stall condition, lambda > 4, was presented in this paper. The power coefficient is very low in the condition below the Re. 0.2E6 and rapidly increases as the Re. increases. And it still increases but the variation is not so big in the condition above the Re. 0.3E6. This results shows that to study the performance of the wind turbine blade by using the scaled down model, the Re. should be larger than the 0.3E6.

• Steel and Composite Structures
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• v.1 no.2
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• pp.187-200
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• 2001

Most of the portal frames are designed these days by the application of plastic analysis, with the normal assumption being made that the column bases are pinned. However, the couple produced by the compression action of the inner column flange and the tension in the holding down bolts will inevitably generate some moment resistance and rotational stiffness. Full-scale portal frame tests conducted during a previous research program had suggested that this moment can be as much as 20% of the moment of resistance of the column. The size of this moment of resistance is particularly important for the design of the tensile capacity of the holding down bolts and also the bearing resistance of the foundation. The present research program is aiming at defining this moment of resistance in simple design terms so that it could be included in the design of the frame. The investigation also included the study of the semi-rigid behaviour of the column base/foundation, which, to a certain extent, affects the overall loading capacity and stiffness of the portal frames. A series of column bases with various details were tested and were used to calibrate a finite element model which is able to simulate the action of the holding down bolts, the effect of the concrete foundation and the deformation of the base plate.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.1
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• pp.24-30
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• 2004

Analysis model for the two-phase catalytic reactor is presented. With the progress in development of micro thermofluidic devices, needs fur understanding of the phenomena in two phase reaction in cm scale has been arisen. To investigate thermal and reactive performance of down scaled two phase reactor simple analysis model that is a kind of lumped flow model is proposed. Analysis model presented is based on the experiment on mm scale model reactor. Target experiment is catalytic decomposition of 70wt％ hydrogen peroxide with existence of perovskite L $a_{0.8}$S $r_{0.2}$Co $O_3$ catalyst. It is composed of balance equations of mass and energy. Each phase is considered to be a species fur the simplicity. Axial diffusion and transversal distribution of properties are neglected. Two phase catalytic reaction is modeled as successive gasification of liquid lump around catalyst and reaction in gas phase. Heat transfer is modeled by model function ofNu number. Modeled Nu is expressed as Nu=N $u_{0}$ (1＋ $a_1$( $a_2$ $T^{-}$ $a_3$)exp( $a_4$ $T^{-1}$)exp( $a_{5}$ z). Transfer coefficients are determined by the comparison of experimental results. With the model, heat transfer characteristics are investigated. Also by the mass transfer coefficient, characteristics in mass transfer is investigated. With the result basic understanding on design and analysis of mm scale two-phase reactive device is obtained. Also it can be further applied to micro scale reactive device fabricated by micromachining.ing..

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2003.04a
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• pp.125-134
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• 2003

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.6
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• pp.616-624
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• 2003

The exhaustion of our water resource due to the leakage of waterworks renders it urgent to detect water leakage effectively. In the paper, the detection of water leakage makes use of a pound-penetrating radar(GPR). The region of water leakage is implemented by an acryl box filled with methanol, and then the scale-down experiments are performed by using the GPR system developed in our laboratory. The validity of GPR experiments is assured by showing that the measured data agree well with those finite-difference time-domain(FDTD) simulated results in the same situation. The feasibility of GPR system for the detection of water leakage is investigated by displaying B-scan images according to the distribution of water leakage.

• Computers and Concrete
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• v.21 no.4
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• pp.385-397
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• 2018

This study is focused on the investigation for similitude the requirements between prototype and scaled models to determine the structural behavior of concrete load bearing systems. The scaling concept has been utilized in many engineering branches, has been assisted to engineers and scientists for obtain the behavior of the prototype by using scaled model. The scaling can be done for two purposes, either scaling up or scaling down depending upon the application. Because, scaled down models are the experimentation on scaled models is cheaper than huge structures. These models also provide facilities for experimental work. Similarity relationships between systems are created either by field equations of the system or by dimensional analysis. Within this study, similarity relationships were obtained by both methods. The similarity relations obtained are applied to different load bearing systems and it is determined that the similarity relation is a general expression. In this study, as an example, column, frame, cantilever beam and simple beam are chosen and 1/2, 1/5 and 1/10 scales are applied. The results are compared with the analytical results which are obtained by creating of the finite element models with SAP2000 software of different scaled load bearing systems. The analysis results of all systems are examined and it is determined that the scale factors are constant depending on the scale types for different load bearing systems.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.3
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• pp.451-456
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• 2021

In order to improve the cell capacitance and scale down in capacitors of semiconductor memory devices, a stacked ONO structure has been introduced as a dielectric layer and thinning of these layers has been attempted continuously. However, many problems have emerged in the manufacturing process. In this study, L/L LPCVD system was used to suppress the growth of natural oxide film of about 10 Å, which was able to secure the capacitance of 3fF / cell. In addition, we investigated the effect of thinning of the dielectric film on the abnormal oxidation of the nitride film, and proposed a stable process control method for forming the dielectric film to ensure oxidation resistance.