• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2003.11a
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• pp.83-86
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• 2003

With the opening of digital broadcast services and development of wire/wireless Internet, the current multimedia broadcasting is provided for has various services. The user will be provided lots of various content through the various channel and media. Content provider and consumer want the various service using content with the better quality which is fit to user preference. For transmitting this content in the limited transmission channel capacity, it needs to transmit the highly compressed content which user wants. The content of 3D mesh model-based on MPEG-4 enables the various content service that provides the lower capacity and the better quality, and Targeting service enables just provide the contents that user more wants and likes. The adaption of Java application program and 3D program can provide the content service utilizing 3D mesh model, so content provider and consumer can share the more information about the content. This paper has presented the study on the targeting service using compression of 3D mesh model-based on MPEG-4 and the adaptation of Java application program using it

• Journal of the Korean Society for Nondestructive Testing
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• v.28 no.3
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• pp.279-284
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• 2008

The firmness of fruit is one of the most important quality factors and is highly correlated to the elastic modulus. In this study, the ultrasonic transmission method was applied to evaluate the elastic modulus of the apple. In order to transmit and receive the ultrasonic wave through the whole apple, the ultrasonic measurement setup consisted of ultrasonic pulser, two specially fabricated ultrasonic transducers for fruit and digital storage oscilloscope. Ultrasonic parameters such as ultrasonic wave velocity, apparent attenuation, and peak frequencies were analyzed. The elastic modulus of apple was measured by using compression test apparatus. The correlations between ultrasonic parameters and elastic modulus were analyzed. A multiple linear regression model describing the relationship between elastic modulus and ultrasonic parameters was proposed.

• Journal of KSNVE
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• v.9 no.2
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• pp.317-323
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• 1999

Dynamic characteristics of catenary that supplies electrical power to high-speed trains are investigated. A simple catenary is composed of the contact and messenger wires connected by droppers possessing bi-directional stiffness properties. For slender, repeating structures such as catenary, both the wave propagation and vibration properties need to be understood. The influence of parameters that determine catenary dynamics are investiaged through numerical simulations involving finite element models. The effects of the tension and flexural rigidity of the contact wire is first investigated. The effects of dropper characteristics are then investigated. For linear droppers wave propagation as well as modal properties are determined. For large catenary motion, droppers can be modeled as bi-directional elements possessing low stiffness in compression and high stiffness in tension. For this case, impulse response is computed and compared with the cases of linear droppers. It is found that the catenary dynamics are primarily determined by contact wire tension and dropper properties, with large responses observed in 5∼40 Hz frequency range. In particular, the dropper stiffness and spacing are found to have dominant influence on the response frequency and the wave transmission characteristics.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.5
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• pp.920-927
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• 1994

A development of an efficient 14.0~14.5GHz 3 Watt SSPA is described in this paper, which is applicable to the very small aperture terminal(VSAT) for bidirectional data and voice signal transmission in low cost and with small size. The SSPA consists of two stages of low noise amplifiers using the low noise GaAs FETs. two stages of medium power amplifiers using the medium power GaAs FETs, and three stages of power amplifiers including a balanced amplifier using an internally matched power GaAs FET. The achieved with this seven stage amplifiers are 42dB signal power gain, 7dB noise figure, 35dBm output power at 1dB gain compression point and 2.0 and 1.5 input and output VSWR respectively.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.6
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• pp.848-859
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• 2004

Mechanical testing methods to determine the material constants for large deformation nonlinear finite element analysis were demonstrated for natural rubber. Uniaxial tension, uniaxial compression, equi-biaxial tension and pure shear tests of rubber specimens are performed to achieve the stress-strain curves. The stress-strain curves are obtained after between 5 and 10 cycles to consider the Mullins effect. Mooney and Ogden strain-energy density functions, which are typical form of the hyperelastic material, are determined and compared with each other. The material constants using only uniaxial tension data are about 20% higher than those obtained by any other test data set. The experimental equations of shear elastic modulus on the hardness and maximum strain are presented using multiple regression method. Large deformation finite element analysis of automotive transmission mount using different material constants is performed and the load-displacement curves are compared with experiments. The selection of material constant in large deformation finite element analysis depend on the strain level of component in service.

• Proceedings of the Korean Information Science Society Conference
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• 2007.10d
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• pp.435-439
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• 2007

최근 저가형 이미지 센서 기술의 발전과 무선 센서 네트워크기술의 발전으로 인해 WMSN(Wireless Multimedia Sensor Networks) 기술이 활발히 연구되고 있다. WMSN은 기존의 무선 센서 네트워크 기술에 멀티미디어 컨텐츠를 센싱하고 전송 및 처리하는 기반기술을 포함한다. 멀티미디어 컨텐츠는 많은 데이터 가지므로 이를 처리하기 위해서는 많은 계산량과 데이터 전송량을 필요로 하게 된다. 저사양의 센서 노드에서 멀티미디어 컨텐츠를 수용하기 위해서는 에너지 소모를 고려한 압축 기법 및 효율적인 전송에 대한 연구가 필요하다. 본 논문에서는 무선 센서 네트워크에서 이미지를 효율적으로 압축하고 전송하기 위하여 웨이블릿의 Resolution Scalability 특성을 이용한 4가지 움직임 보상/예측 기법을 제안한다. 이를 지원하기 위해 시스템에서 사용하는 각 압축 기법들의 조합에 따른 압축 성능이 적절함을 알아보았다.

• ETRI Journal
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• v.31 no.1
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• pp.21-30
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• 2009

In low bit-rate video transmission, the payload of a single packet can often contain a whole coded frame due to the high compression ratio in both spatial and temporal domains of most modern video coders. Thus, the loss of a single packet not only causes the loss of a whole frame, but also produces error propagation into subsequent frames. In this paper, we propose a novel whole frame error concealment algorithm which reconstructs the first of the subsequent frames instead of the current lost frame to suppress the effects of error propagation. In the proposed algorithm, we impose a constraint which uses side match distortion (SMD) and overlapped region difference (ORD) to estimate motion vectors between the target reconstructed frame and its reference frame. SMD measures the spatial smoothness connection between a block and its neighboring blocks. ORD is defined as the difference between the correlated pixels which are predicted from one reference pixel. Experimental results show that the proposed algorithm effectively suppresses error propagation and significantly outperforms other conventional techniques in terms of both peak signal-to-noise ratio performance and subjective visual quality.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.193-197
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• 2002

In this study, the casting/forging process was applied to the Shift-Fork, a manual transmission part of automobiles. In the casting experiments, the effects of additives, Sr, Ti＋B and Mg, on the mechanical properties and the microstructure of a cast preform were investigated. When 0.03% Sr were added into the molten aluminum alloy, the finest silicon-structure was observed in the cast preform and the highest tensile strength and elongation accomplished. And when 0.2% Ti＋B were added into the molten Al-Si alloy, the highest values of tensile strength were obtained. The maximum hardness was in case of 0.2% Mg. In the forging experiment, it was confirmed that the optimal configuration of the cast preform could be predicted by FE analysis. To minimize the cost as the press size, the compact shape of preform was proposed to reduce the volume of flash. The modification of shape in designing preform was performed to attain a satisfactory performance in the areas where the mechanical strength were more required. By using FVM(Finite Volume Method) software, it was verified that a proposed casting design was available. To identify the relationship between effective strain and mechanical properties of the final forged product, the compression test was performed. As the result, the tensile strength and elongation of a cast preform were much higher than before forging. The minimum forging temperature was found 40$0^{\circ}C$ to save heating time.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.1081-1085
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• 2009

We have already developed EMI reducing techniques using lossless compression by vertically differential EMI suppression method (VDE[1]). It applies lossless modulo reduction and data bit mapping optimization for low voltage differential signaling (LVDS) transmission lines, that reduces the probability of transient bit and EMI by 12 dB [6][7]. We also improved and optimized the VDE for low power LCD interface. With this modified VDE algorithm[8], the developed FPGA was measured the reduction of the power consumption of LCD circuit by more than 15 % compared to the conventional methods in the case of 14-in LCD with SXGA resolution. The VDE algorithm is based on the total image systematic approach. In the VDE method, the present image signals are subtracted for the 1H delayed image signals and transferred to a column driver through a PCB. As the vertical correlations for image signals are very high, we expected that most of the vertically subtracted image signals remain 0 level and transient cycles become very long. As a result, the power consumption and EMI are extremely reduced for the transferred image signals on a PCB. In this paper, we discussed our proposed method by emphasizing the fact that systematic approach are important based on not only display point of view but also total system point of view.

• Advances in nano research
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• v.3 no.2
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• pp.81-96
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• 2015

Octahedral shaped single crystalline undoped and Ga-doped indium oxide nano-and microcrystals were fabricated using vapor-solid growth process. Effects of Ga doping on the crystallinity, defect structure, and optical properties of the nano-/microstructures have been studied using scanning electron microscopy, microRaman spectroscopy, transmission electron microscopy and cathodoluminescence spectroscopy. It has been observed that incorporation of Ga does not affect the morphology of $In_2O_3$ structures due to its smaller ionic radius, and similar oxidation state as that of In. However, incorporation of Ga in high concentration (~3.31 atom %) causes lattice compression, reduces optical band gap and defect induced CL emissions of $In_2O_3$ nano-/microcrystals. The single crystalline Ga-doped, $In_2O_3$ nano-/microcrystals with low defect contents are promising for optoelectronic applications.