• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권3호
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• pp.1684-1699
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• 2017

The deblocking filter (DF) reduces blocking artifacts in encoded video sequences, and thereby significantly improves the subjective and objective quality of videos. Statistics show that the DF accounts for 5-18% of the total decoding time in high-efficiency video coding. Therefore, speeding up the DF will improve codec performance, especially for the decoder. In view of the rapid development of multicore technology, we propose a parallel DF scheme based on a modified order of accessing the coding tree units (CTUs) by analyzing the data dependencies between adjacent CTUs. This enables the DF to run in parallel, providing accelerated performance and more flexibility in the degree of parallelism, as well as finer parallel granularity. We additionally solve the problems of variable privatization and thread synchronization in the parallelization of the DF. Finally, the DF module is parallelized based on the HM16.1 reference software using OpenMP technology. The acceleration performance is experimentally tested under various numbers of cores, and the results show that the proposed scheme is very effective at speeding up the DF.

• 한국정보통신학회논문지
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• 제16권3호
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• pp.511-521
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• 2012

JXTA는 개방형 프로토콜로서 인터넷이나 MANET(Mobile Adhoc NETwork)에서 연결된 기기들 사이의 P2P 방식 통신을 가능하게 한다. 본 논문에서는 JXTA를 기반으로 하는 스마트폰 협업 어플리케이션의 개발에 대하여 기술한다. 체계적인 개발을 위하여 P2P 네트워크에서 필요한 핵심 서비스와 협업 서비스가 정의되고, 정의된 서비스를 지원하기 위한 프로토콜이 설계된다. 개발된 어플리케이션은 다양한 가상의 작업공간을 지원하여 스마트폰을 활용한 효과적인 협업 환경을 제공하며, 모바일 네트워크에 의존하지 않고 근거리에 있는 스마트폰 사용자 간에 협업을 지원하기 때문에 재난 지역 등의 다양한 상황에서도 유용하게 사용될 수 있다.

• Structural Engineering and Mechanics
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• 제45권6호
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• pp.759-777
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• 2013

In this paper, a topology optimization method based on the element independent nodal density (EIND) is developed for continuum solids with multiple load cases and multiple constraints. The optimization problem is formulated ad minimizing the volume subject to displacement constraints. Nodal densities of the finite element mesh are used a the design variable. The nodal densities are interpolated into any point in the design domain by the Shepard interpolation scheme and the Heaviside function. Without using additional constraints (such ad the filtering technique), mesh-independent, checkerboard-free, distinct optimal topology can be obtained. Adopting the rational approximation for material properties (RAMP), the topology optimization procedure is implemented using a solid isotropic material with penalization (SIMP) method and a dual programming optimization algorithm. The computational efficiency is greatly improved by multithread parallel computing with OpenMP to run parallel programs for the shared-memory model of parallel computation. Finally, several examples are presented to demonstrate the effectiveness of the developed techniques.

• 전기학회논문지
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• 제66권12호
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• pp.1792-1798
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• 2017

Event Data Recorder(Car Black-Box) with WiFi dongle have been released, and the platform of the majority is the Linux platform. This is because the platform development is possible in little investment cost by reducing the source licensing costs by taking advantage of the open source. But utilizing Linux platform has the limitations of boot-up time and consuming processing power due to the limitation of battery capacity, to be cost-competitive to minimize the use of memory. In this paper, the real-time operating system(RTOS) is utilized to optimize these portions. MP4 encoder and Muxer are developed to be about ten seconds boot up and minimized memory. It has the advantages of operating at lower power consumption than the Linux utilizing WiFi dongle. Utilizing a WiFi dongle is to provide a progressive download feature on smart phones to lower product prices. But RTOS has the weakness in WiFi. Porting TCP /IP, Web and DHCP server and combination with the USB OTG Host interface by implementing the protocol stack are developed for WiFi. And also SPI NOR flash memory is utilized for faster boot time and cost reductions, low processing power to be consume. As the results, the developed proved the 10 seconds booting time, 24 frame rate/sec. and 10% lower power consumption.

• Nuclear Engineering and Technology
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• 제50권3호
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• pp.327-339
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• 2018

This article presents a new global-local hybrid coarse-mesh finite difference (HCMFD) method for efficient parallel calculation of pin-by-pin heterogeneous core analysis. In the HCMFD method, the one-node coarse-mesh finite difference (CMFD) scheme is combined with a nodal expansion method (NEM)-based two-node CMFD method in a nonlinear way. In the global-local HCMFD algorithm, the global problem is a coarse-mesh eigenvalue problem, whereas the local problems are fixed source problems with boundary conditions of incoming partial current, and they can be solved in parallel. The global problem is formulated by one-node CMFD, in which two correction factors on an interface are introduced to preserve both the surface-average flux and the net current. Meanwhile, for accurate and efficient pin-wise core analysis, the local problem is solved by the conventional NEM-based two-node CMFD method. We investigated the numerical characteristics of the HCMFD method for a few benchmark problems and compared them with the conventional two-node NEM-based CMFD algorithm. In this study, the HCMFD algorithm was also parallelized with the OpenMP parallel interface, and its numerical performances were evaluated for several benchmarks.

• 생약학회지
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• 제5권3호
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• pp.159-166
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• 1974

The Yellow needle crystal was isolated from Atractylis Rhizoma, having mp $124{\sim}126^{\circ}C$(decomp.), the chemical composition $C_{16}H_{21}N_{3}O_{6}$, and its m.w. 251. The pharmacological actions of this alkaloid were studied by various psycopharmacological experiments. 1) In order to see the effect of this Atractylis(=At.) alkaloid on gross general behaviors in mice, a behavioral analysis experiment was adapted. The occurrence number of sleep and lying in At. alkaloidal animals with the doses 10mg/kg or 20mg/kg was increased but the number of jumping, exploration, rearing and defecation was significantly decreased than those of placebo. 2) The effect of the At. alkaloid on unlearned emotional behaviors of mice was studied with an open-field method. The At. alkaloidal groups with the doses 20mg/kg or 30mg/kg showed less often the frequency of locomotion than that of placebo. 3) To know the effect of the At. alkaloid on the learning, a standard water maze experiment and conditioned avoidance response were conducted. As compared to placebo control, the aquisition rate of the maze learning in the alkaloidal mice with the dose of 10mg/kg or 20mg/kg was significantly impaired and the speed of swimming was also signficantly delayed. In the conditioned avoidance response, the extinction performances of the alkaloidal rats with doses of 20mg/kg or 30mg/kg did not differ significantly than that of placebo.

• 한국정보통신학회논문지
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• 제12권1호
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• pp.53-58
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• 2008

내포 병렬성을 가지는 병렬 프로그램은 동기화 없이 병행적으로 수행되는 양상으로 인하여 비결정적인 결과를 초래하는 경향이 있다. 이러한 오류를 탐지하기 위하여 다양한 시각화 기법이 이용되고 있지만, 공간의 제한성과 과다한 추상화로 인하여 직관성이 매우 저하되는 실정이다. 본 논문에서는 내포 병렬성을 가지는 복잡한 병렬 프로그램의 전역적 구조를 사용자에게 제공하는3차원 시각화 엔진을 제안한다. 제안된 시각화 엔진은 전역적 구조를 사용자에게 제공함으로서 프로그램의 이해를 용이하게 하고 효과적인 디버깅 환경을 제공한다.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2019년도 학술발표회
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• pp.62-62
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• 2019

본 연구에서는 기상청에서 제공하는 인공위성 관측자료와 레이더 자료를 합성하여 예측된 선행시간 2시간의 강수량 예측자료를 이용하여 도시유역의 침수 발생 여부를 확인할 수 있는 시스템을 개발하였다. 대상유역은 부산광역시에 위치하고 있는 유역면적 $54km^2$의 온천천유역으로, $10m{\times}10m$의 해상도로 지표면의 침수예측을 수행한다. 침수예측에 이용되는 모델은 지표면과 하수관망 사이의 상호작용을 효과적으로 고려할 수 있도록 지표면 2차원, 하수관망 1차원 모델을 연계하였으며, 침수예측에 소요되는 시간을 최소화하기 위하여 OpenMP기반의 병렬해석 기법을 적용하였다. 또한 초기조건에 의한 오차를 줄이기 위하여 하천수위 관측소에 관측된 수위자료를 예측모델의 초기조건으로 입력할 수 있도록 시스템을 구성하였으며 유역 하류단에서 경계조건으로 활용되는 예측수위자료는 시계열자료의 예측에 뛰어난 성능을 보여주는 것으로 알려진 LongShort-term Memory(LSTM) 기법을 적용하여 이용하였다. 본 연구에서 개발된 실시간 도시침수 예측 시스템은 집중호우 발생시 침수 발생 위치를 사전에 빠르게 예측하여 도시유역의 인적 물적 자원의 피해를 저감하는데 적극적으로 활용될 수 있을 것으로 기대된다.

• Nuclear Engineering and Technology
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• 제53권11호
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• pp.3543-3562
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• 2021

The methods and performance of a 3D pin-by-pin neutronics code based on the 2D/1D decoupling method are presented. The code was newly developed as an effort to achieve enhanced accuracy and high calculation performance that are sufficient for the use in practical nuclear design analyses. From the 3D diffusion-based finite difference method (FDM) formulation, decoupled planar formulations are established by treating pre-determined axial leakage as a source term. The decoupled axial problems are formulated with the radial leakage source term. To accelerate the pin-by-pin calculation, the two-level coarse mesh finite difference (CMFD) formulation, which consists of the multigroup node-wise CMFD and the two-group assembly-wise CMFD is implemented. To enhance the accuracy, both the discontinuity factor method and the super-homogenization (SPH) factor method are examined for pin-wise cross-section homogenization. The parallelization is achieved with the OpenMP package. The accuracy and performance of the pin-by-pin calculations are assessed with the VERA and APR1400 benchmark problems. It is demonstrated that pin-by-pin 2D/1D alternating calculations within the two-level 3D CMFD framework yield accurate solutions in about 30 s for the typical commercial core problems, on a parallel platform employing 32 threads.

• Nuclear Engineering and Technology
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• 제51권5호
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• pp.1218-1230
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• 2019

A sub-channel solver, named ${\underline{S}}teady$ and ${\underline{T}}ransient$ ${\underline{A}}nalyzer$ for ${\underline{R}}eactor$ ${\underline{T}}hermal$ hydraulics (START), has been developed using the homogenous model for two-phase conditions of light water reactors. The code is developed as a fast and accurate TH-solver for coupled and multi-physics calculations. START has been validated against the NUPEC PWR Sub-channel and Bundle Test (PSBT) database. Tests like single-channel quality and void-fraction for steady state, outlet fluid temperature for steady state, rod-bundle quality and void-fraction for both steady state and transient conditions have been analyzed and compared with experimental values. Results reveal a good accuracy of solution for both steady state and transient scenarios. Axially different values for turbulent mixing coefficient are used based on different grid-spacer types. This provides better results as compared to using a single value of turbulent mixing coefficient. Code-to-code evaluation of PSBT results by the START code compares well with other industrial codes. The START code has been parallelized with the OpenMP algorithm and its numerical performance is evaluated with a large whole PWR core. Scaling study of START shows a good parallel performance.