• Water for future
• /
• v.21 no.2
• /
• pp.193-201
• /
• 1988

A simplified model for higher order scanning curves in the soil water characteristic function is suggested. The conceptual hysteresis models developed by $Mualem_{8,9}$ are simplied for higher order scanning curves. Higher order drying curves are regarded as primary drying curves and the last wetting reversal point is assumed to be on the main wetting curve by moving that point vertically downward. For the higher order wetting curves, it is assumed that these curves can be regarded as primary curves and the last wetting reversal point sits on the imaginary main drying curve which passes through the last wetting reversal point. The water content computed from the simplified model are compared with those obtained from Mualem's original model for second order scanning curves. It is found that absolute differences between the two methods aree relatively small and the simplified model always underestimates for higher order drying curves while it overestimates for higher order wetting curves. Hence, those two tend to compensate each other for repeated drying-wetting processes. The simplified model approximates higher order scanning curves well and reduces computation considerably.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.35 no.2A
• /
• pp.142-152
• /
• 2010

When a mobile station(MS) performs a handover, in the IEEE 802.11 WLAN, MS's channel scanning for discovering new available APs is the dominating factor in handover latency, accounting 90% of overall latency. In order to reduce such a scanning latency, we focus on the method for reducing the number of channels for the MS in handover process to scan. With the help of IEEE 802.21 information server(IS), a proper order of groups of channels to be scanned is offered by the current AP depending on the information of neighbor APs in terms of the distance from serving AP, traffic load and network topology. By using this scanning order, the passive scanning of a MS in normal operation enables the MS to filter out the unavailable channels, and thus to classify the candidate channels of neighbor APs into three groups. Then, a handover-imminent MS can perform the active scanning from the most reliable group of channels. Simulation results show that the proposed scanning scheme reduce the scanning latency in comparison with the conventional scheme.

• ETRI Journal
• /
• v.31 no.5
• /
• pp.607-609
• /
• 2009

In this letter, an effective scanning method based on a morphological representation of quantized coefficients is proposed for intra coding in H.264. In the proposed scanning method, the scan order for each block is adaptively reconfigured by exploiting a residual correlation beyond the border of the block. An initial scan order for the current block is determined first by using the pattern of nonzero coefficients in the adjacent block. Then, a complete scan order is obtained by performing the dilation operation at each position within the initial scan order. Experimental results show that the proposed method improves the coding efficiency up to 3.7% compared to the conventional zigzag scanning method.

• Journal of the Korean Society for Precision Engineering
• /
• v.15 no.11
• /
• pp.58-66
• /
• 1998

A low power consuming laser scanning vibrometer is studied for its development. For its optical system, a laser interferometer is constructed to use the Doppler effect. In order to reduce the driving power of the scanning system, a small displacement of the scanning system is produced, which is achieved by using a magnetostrictive actuator. A sufficient rotating angle of the scanning system is obtained by using an amplified displacement from the resonant phenomena of a second order mechanical system composed of a mass and spring. The control of the magnetostrictive actuator using a Terfenol-D is performed without using a feedback system to help reduce the power consumption. The vibration analysis is made for the sinusoidal scanning input to have the space domain information from the time domain of the velocity of a vibration object. As a partial work of development of a tow power consuming laser scanning vibrometer, in this work, a scanning system which has the above features is developed and experimentally investigated. For the purpose of the optical system calibration, the vibration measurement for one axis is presented and the future works are discussed.

• Current Optics and Photonics
• /
• v.2 no.2
• /
• pp.172-178
• /
• 2018

We propose a precise 3D endoscopic technique for medical and industrial applications. As the 3D measuring principle, the continuously scanning structured illumination microscopy (CSSIM), which enables to obtain 3D sectional images by the synchronous axial scanning of the target with the lateral scanning of the sinusoidal pattern, is adopted. In order to reduce the size of the probe end, the illumination and detection paths of light are designed as coaxial and a coherent imaging fiber bundle is used for transferring the illumination pattern to the target and vice versa. We constructed and experimentally verified the proposed system with a gauge block specimen. As the result, it was confirmed that the 3D surface profile was successfully measured with $16.1{\mu}m$ repeatability for a gauge block specimen. In order to improve the contrast of the sinusoidal illumination pattern reflected off on the target, we used polarizing optical components and confirmed that the visibility of the pattern was suitable in CSSIM.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1995.10a
• /
• pp.442-445
• /
• 1995

This paper presents the position tracking control of a laser scanning mirror system in which piezoelectic actuator is incorporated. Using the shear mode of the piezoelectric actuator,angular oscillation of a laser scanning mirror is derived. Torsion bar is rhen designed and attached to the piezoelctric actuator in order to magnify the amplitude generated by the actuator. Finite element modeling and analysis are essntial for designing the piezoelectic actuator. The torsional resonance mode of the piezoelectric actuator is found from the model analysis of the actuator and the mechanical shear is matched with the driving frequency. Transfer function between the electrical excitation and the mechanical shear deformation at resonance frequency is found form the response of the actuator calculated by the finite element analysis and the governing equation of the system is derived from d'Alembert's principle. Tracking control performance for desired trajectory which is, in fact, sinusoidal curve is presented in order to demonstrate the validity of the proposed system.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.14 no.2
• /
• pp.281-288
• /
• 2011

In this paper, a variable quantization coefficient scanning for macroblock considering the histogram value of previous macroblock's quantization coefficient is proposed. In order to scan a quantization coefficient, the proposed method makes $4{\times}4$ histograms for various prediction modes($16{\times}16$, $16{\times}8$, $8{\times}16$, $8{\times}8$) by adding 1 if the value of quantization coefficient is not 0. After a final mode decision procedure, the $4{\times}4$ histogram of the final mode will be sorted. Then, quantization coefficients in corresponding macroblock of the next frame are scanned using the sorted order. The experimental results show that the proposed scheme reduces the total bits by approximately 0.01~2.25% with similar PSNR performance compared with the previous method.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1994.05a
• /
• pp.30-33
• /
• 1994

This paper studies on the effect of DSC(Differential Scanning Calorimeter) analysis condition on the glass transition temperature of silica filled epoxy network polymer used for ultra-high voltage apparatus. The effects of temperature scanning rate specimen size and gas flow rate on measured glass transition temperature have been studied in order to select optimum thermal analysis condition.

• Korean Journal of Computational Design and Engineering
• /
• v.4 no.1
• /
• pp.60-68
• /
• 1999

In reverse engineering (RE) sustems, the quality of the data aquisition process is crucial to the accuracy of the reverse engineered three dimensional computer-aided design (CAD) model. However, these tasks are predominantly done manually, and little work has been done to improve the efficiency of scanning by determining the minimum number of scans and the optimal scanning directions. In this paper, new scanning and registration methods using tooling balls are developed to assist in determining the optimal parameter for these processes. When the object to scanned has no concavity, attaching path of the object and its bounding rectangle are used for optimal scanning and registration. Then minimum number of tooling balls and their positions are calculated automatically. In the case of concave parts, the scanning plan should include a complete scan of the concave area. With the surface normal vector and the scanning direction, the minimum degree of rotating the part can be calculated. But the maximum rotation should be restricted in order to prevent occlusion of the part. Finally tow sample part ar scanned based on the proposed methods and the results are discussed.

• Journal of Broadcast Engineering
• /
• v.16 no.6
• /
• pp.1036-1046
• /
• 2011

MPEG and VCEG have constituted a collaboration team called JCT-VC(Joint Collaborative Team on Video Coding) and have been developing HEVC(High Efficiency Video Coding) standard. All transform coefficients in a TU(Transform Unit) have been equally quantized according to the quantization and inverse quantization method which is used in HEVC standard. Such an equal quantization is not efficient because the transformed coefficients in the TU are not eqully distributed. Furthermore, the quantized coefficients which is positioned in later scanning order cannot be efficient due to the entropy scanning method. We suggest an algorithm that transform coefficients are quantized at different values according to the position in TU considering a scanning order of entropy encoding to improve the coding efficiency. The principle of this algorithm is that quantization and inverse quantization are carried out according to the scanning order which is in accordance with the statistical characteristic of distribution of quantized transform coefficients. The proposed algorithm shows on the average of 0.34% Y BD-rate compression rate improvement.