• 방송공학회논문지
• /
• 제21권4호
• /
• pp.592-608
• /
• 2016

최근 거의 완벽한 3차원 영상정보를 갖고 있는 디지털 홀로그램에 대한 연구가 활발히 이루어지고 있어 조만간 디지털 홀로그램의 서비스가 시작될 것으로 보인다. 따라서 본 논문에서는 이 서비스에 사용될 수 있는 디지털 홀로그램 동영상을 압축하는 기술을 제안한다. 이 방법은 가장 최근에 국제표준으로 제정된 2차원 동영상 압축 기술인 H.265/HEVC를 사용하는데, 디지털 홀로그램의 화소 간 상관성을 높이기 위하여 도메인 변환 방법을 사용한다. 또한 압축효율을 높이기 위해 H.265/HEVC의 다양한 압축 파라미터들을 고려한다. 본 논문의 목적은 다양한 도메인 변환 방법, 도메인 변환 단위, 압축 파라미터들 중 가장 압축효율이 좋은 최적의 압축조건을 실험을 통하여 구하는 것이다. 이렇게 구해진 조건을 만족하는 압축방법을 기존의 방법들과 비교하여 본 논문에서 제시하는 방법의 우수성을 보인다.

• 한국정보통신학회논문지
• /
• 제16권1호
• /
• pp.119-126
• /
• 2012

H.264/AVC는 부호화되는 잉여 데이터의 유형에 따라 3개의 변환을 사용할 수 있다. $4{\times}4$ DCT 변환은 항상 수행되며, $16{\times}16$ 인트라 모드인 경우에는 추가적으로 휘도 DC 계수에는 $4{\times}4$ 하다마드 변환을 수행하고, 색체 DC 계수에는 $2{\times}2$ 하다마드 변환을 수행한다. 변환 코딩을 완료한 이후에 한층 더한 데이터 압축을 위해 양자화가 수행된다. 본 논문에서는 H.264/AVC에 중요한 역할을 하는 DCT 변환, 하다마드 변환 및 양자화에 대한 하드웨어적인 구현에 대해 연구하였다. 특히 파이프라인 기법을 적용하여 33클럭의 대기지연시간 이후에는 매 클럭 당 1개의 양자화된 결과를 출력할 수 있는 아키텍쳐를 제안하였다. 제안한 아키텍쳐는 Verilog HDL로 코딩되고, Xilinx 7.1i ISE툴을 사용하여 합성하고 검증하였다. 합성 결과 SPARTAN3S-1000 디바이스에서 동작 주파수는 106MHz이다. $1920{\times}1080$ HD 영상 프레임의 경우 최대 33프레임을 처리할 수 있다.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 2008년도 추계학술대회 논문집
• /
• pp.333-336
• /
• 2008

The groove rolling is a process that transforms the bloom or billet into a shape with circular section through a series of rolling. Inhibition of surface defect generation in groove rolling is a matter of great importance and therefore many research groups proposed a lot of models to find the location of surface defect initiation. In this study, we propose a model for maximum shear stress ratio over equivalent strain to catch the location of surface defect onset. This model is coupled with element removing method and applied to box groove rolling of POSCO No. 3 Rod Mill. Results show that proposed model in this study can find the location of surface defect initiation during groove rolling when finite element analysis results is compared with experiments. The proposed criterion has been applied successfully to design roll grooves which inhibits the generation of surface defect.

• Coupled systems mechanics
• /
• 제9권4호
• /
• pp.325-342
• /
• 2020

A mathematical model of electro-thermoelasticity subjected to memory-dependent derivative (MDD) heat conduction law is applied to a one-dimensional problem of a thermoelectric spherical cavity exposed to a warm stun that is an element of time in the presence of a uniform magnetic field. Utilizing Laplace transform as an instrument, the issue has been fathomed logically within the changed space. Numerical inversion of the Laplace transform is carried for the considered distributions and represented graphically. Some comparisons are shown in the figures to estimate the effects of MDD parameters and thermoelectric properties on the behavior of all considered fields.

• 대한기계학회논문집A
• /
• 제26권2호
• /
• pp.283-290
• /
• 2002

In this paper, we consider the dynamic electromechanical behavior of an eccentric Yoffe permeable crack in a piezoelectric ceramic strip sandwiched between two elastic orthotropic materials under the combined anti-plane mechanical shear and in-plane electrical loadings. Fourier transforms are used to reduce the problem to the solution of two pairs of dual integral equations, which are then expressed to a Fredholm integral equation of the second kind. The initial crack propagation orientation for PZT-5H piezoceramics is predicted by maximum energy release rate criterion.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 1991년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 22-24 Oct. 1991
• /
• pp.844-849
• /
• 1991

A high speed control system for a telerobot using DSP is developed. The system is designed to resolve computational burden in advanced algorithms. The design is assumed to h ave no specific algorithm and robot configuration. The system is composed of a teaching box, a DSP board, a set of servo drivers and 16 bit microcomputer system. The teaching box is designed as a man-machine interface, which has two joysticks with three degrees of freedom for velocity generation in Cartesian space. The DSP board, i.e. DSP56000ADS based on a 10.25MIPS digital signal processor, DSP56001, computes the inverse Jacobian matrix which transforms Cartesian velocity into joint velocity. A resolved motion rate control algorithm for a 5 degrees of freedom manipulator was implemented. About 100 Hz sampling rate was achieved in this system.

• ETRI Journal
• /
• 제24권5호
• /
• pp.391-397
• /
• 2002

This paper presents digital signal processor (DSP) instructions and their data processing unit (DPU) architecture for high-speed fast Fourier transforms (FFTs) in orthogonal frequency division multiplexing (OFDM) systems. The proposed instructions jointly perform new operation flows that are more efficient than the operation flow of the multiply and accumulate (MAC) instruction on which existing DSP chips heavily depend. We further propose a DPU architecture that fully supports the instructions and show that the architecture is two times faster than existing DSP chips for FFTs. We simulated the proposed model with a Verilog HDL, performed a logic synthesis using the 0.35 ${\mu}m$ standard cell library, and then verified the functions thoroughly.

• 한국정밀공학회지
• /
• 제14권7호
• /
• pp.126-136
• /
• 1997

This paper describes a task level cell programming environment that deals with difficulties in programming Flexible Manufacturing Cells (FMCs), and consists of the cell programming editor and the automatic generation module. In the cell programming editor, cell programs can be developed with task- oriented cell specifications that reduces the amount of details to be considered by cell programmers. The automatic generation module transforms task specifications into executable programs used by cell constituents. The development tool in designing the environment is an object-oriented approach which provides a simple to use and intuitive user interface, and allows for an easy development of object models associated with the environment. Test results are illustrated in order to demonstrate the applicability of the developed envifonment.

• International Journal of Reliability and Applications
• /
• 제10권2호
• /
• pp.109-118
• /
• 2009

Crankshaft, the core element of the engine of a vehicle, transforms the translational motion generated by combustion to rotational motion. Its failure will cause serious damage to the engine so its reliability verification must be performed. In this study, the S-N data of the bending and torsion fatigue limits of a crankshaft are derived. To evaluate the reliability of the crankshaft, reliability verification and analysis are performed. For the purpose of further evaluation, the bending and torsion tests of the original crankshaft are carried out, and failure mode analysis is made. The appropriate number of samples, the applied load, and the test time are computed. On the basis of the test results, Weibull analysis for the shape and scale parameters of the crankshaft is estimated. Likewise, the $B_{10}$ life under 50% of the confidence level and the MTTF are exactly calculated, and the groundwork for improving the reliability of the crankshaft is laid.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2001년도 춘계학술대회논문집A
• /
• pp.304-309
• /
• 2001

In this paper, we consider the dynamic electromechanical behavior of an eccentric Yoffe permeable crack in a piezoelectric ceramic strip sandwiched between two elastic materials under the combined anti-plane mechanical shear and in-plane electrical loadings. Fourier transforms are used to reduce the problem to the solution of two pairs of dual integral equations, which are then expressed to a Fredholm integral equation of the second kind. The initial crack propagation orientation for PZT-5H piezoceramics is predicted by maximum energy release rate criterion.