• 한국레이저가공학회:학술대회논문집
• /
• 한국레이저가공학회 2006년도 춘계학술발표대회 논문집
• /
• pp.41-46
• /
• 2006

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2005년도 학술대회 논문집 정보 및 제어부문
• /
• pp.532-535
• /
• 2005

These days, many image processing techniques have been studied for effective image compression. Among those, 2D image filtering is widely used for 2D image processing. The 2D image filtering can be implemented by performing ID linear filtering separately in the direction of horizontal and vertical. Efficiency of image compression depends on what filtering method is used. Generally, circular convolution is widely used in the 2D image filtering for image processing. However it doesn't consider correlations at the region of image boundary, therefore filtering can not be performed effectively. To solve this problem. I proposed new convolution technique using Symmetric-Mirroring convolution, satisfying the 'alias-free' and 'error-free' requirement in the reconstructed image. This method could provide more effective performance than former compression methods. Because it used very high correlative data when performed at the boundary region. In this paper, pre-processing filtering in H.264 codec was adopted to analyze efficiency of proposed filtering technique, and the simulator developed by Matlab language was used to examine the performance of the proposed method.

• 한국측량학회지
• /
• 제37권6호
• /
• pp.445-452
• /
• 2019

본 연구에서는 대용량 위성영상의 무감독분류를 위해 k-means clustering 알고리즘의 병렬처리 코드를 개발하여 PC-cluster에서 구현하였다. 이를 위해 OpenMP (Open Multi-Processing)를 기반으로 CPU (Central Processing Unit)의 다중코어를 이용하는 intra-node 코드와 message passing interface를 기반으로 PC-cluster를 이용하는 inter-nodes 코드, 그리고 이 둘을 병용하는 hybrid 코드를 구현하였다. 본 연구에 사용한 PC-cluster는 한 대의 마스터 노드와 여덟 대의 슬래이브 노드로 구성되어 있고 각 노드에는 여덟 개의 다중코어가 장착되어 있다. PC-cluster에는 Microsoft Windows와 Canonical Ubuntu의 두 가지 운영체제를 설치하여 병렬처리 성능을 비교하였다. 실험에 사용한 자료는 두 가지 다중분광 위성영상으로서 중용량인 LANDSAT 8 OLI (Operational Land Imager) 영상과 대용량인 Sentinel 2A 영상이다. 병렬처리의 성능을 평가하기 위하여 speedup과 efficiency를 측정한 결과 전반적으로 speedup은 N/2 이상, efficiency는 0.5 이상으로 나타났다. Microsoft Windows와 Canonical Ubuntu를 비교한 결과 Ubuntu가 2-3배의 빠른 결과를 나타내었다. 순차처리와 병렬처리 결과가 일치하는지 확인하기 위해 각 클래스의 밴드별 중심값과 분류된 화소의 수를 비교하고 결과 영상간 화소대 화소 비교도 수행하였다. Intra-node 코드를 구현할 때에는 OpenMP에 의한 false sharing이 발생하지 않도록 주의해야 하고, PC-cluster에서 대용량 위성영상을 처리하기 위해서는 파일 I/O에 의한 성능저하를 줄일 수 있도록 코드 및 하드웨어를 설계해야 함을 알 수 있었다. 또한 PC-cluster에 설치된 운영체제에 따라서도 성능 차이가 발생함을 알 수 있었다.

• 한국정보과학회논문지:데이타베이스
• /
• 제35권1호
• /
• pp.67-83
• /
• 2008

유비쿼터스 컴퓨팅의 실현을 위해서는 이동 단말기의 자원 및 컴퓨팅 파워의 효율적 사용이 필수적이다. 특히, 이동 단말기에 내장된 소프트웨어의 수행에 있어 메모리 효율성 에너지 효율성, 그리고 처리 효율성이 요구된다. 본 논문은 자원이 제약되어 있는 이동 단말기에서의 XML 데이타에 대한 질의 처리에 관한 것이다. 메모리 용량이 크지 않은 단말기의 경우 대량의 XML 데이타에 대한 질의 처리를 수행하기 위해서는 XML 스트림 질의 처리 기술이 활용되어야 한다. 최근에 제시된 XFrag는 홀-필러 모델을 이용하여 XML 데이타를 XML 조각으로 분할하여 스트림으로 전송하고 처리할 수 있는 기법이다. 이는 메모리가 부족한 이동 단말기에서 조각 스트림으로부터 XML 데이타를 재구성하지 않고 질의 처리를 가능하게 한다. 그러나 홀-필러 모델을 사용할 경우 홀과 필러에 대한 부가적인 정보를 저장해야 하므로 메모리 효율성이 높지 못하다. 본 논문에서는 XML 데이타의 구조 정보를 표현하는 XML 레이블링 기법을 이용하여 XML 데이타를 조각으로 분할하여 처리하는 새로운 기법 XFLab을 제시한다. 구현 및 성능 실험 결과 XFLab이 XFrag보다 메모리 사용량과 처리 시간 양면 모두에서 우수한 것으로 나타났다.

• 한국환경과학회지
• /
• 제8권2호
• /
• pp.221-225
• /
• 1999

This study was conducted to evaluate the treatment efficiency including reaction kinetics and hydraulic characteristics of food processing wastewater by using an ejector-type aeration system (ETAS) in activated sludge process. The oxygen transfer efficiency in ETAS can be changed in accordance with the depth of reactor. However, the optimum air velocity was found less than 1.82 m/hr at a superficial liquid velocity of 634 m/hr. The ETAS process showed higher organic material removal efficiency than that of the existing activated sludge process under hydraulic detention time 6 to 12 hours. This process, which can maintain MLVSS highly, is able to have high organic material removal efficiency at short HRT and deal with variable organic material loading.

• 대한임베디드공학회논문지
• /
• 제7권5호
• /
• pp.277-284
• /
• 2012

To meet the usage of discrete wavelet transform (DWT) on potable devices, this paper implements 2-level DWT using a reference many-core processor architecture and determine the optimal many-core processor. To explore the optimal many-core processor, we evaluate the impacts of a data-per-processing element ratio that is defined as the amount of data mapped directly to each processing element (PE) on system performance, energy efficiency, and area efficiency, respectively. This paper utilized five PE configurations (PEs=16, 64, 256, 1,024, and 4,096) that were implemented in 130nm CMOS technology with a 720MHz clock frequency. Experimental results indicated that maximum energy and area efficiencies were achieved at PEs=1,024. However, the system area must be limited 140mm2 and the power should not exceed 3 watts in order to implement 2-level DWT on portable devices. When we consider these restrictions, the most reasonable energy and area efficiencies were achieved at PEs=256.

• Journal of Information Processing Systems
• /
• 제16권1호
• /
• pp.1-5
• /
• 2020

Sustainable computing is a rapidly expanding field of research covering the fields of multidisciplinary engineering. With the rapid adoption of Internet of Things (IoT) devices, issues such as security, privacy, efficiency, and green computing infrastructure are increasing day by day. To achieve a sustainable computing ecosystem for future smart cities, it is important to take into account their entire life cycle from design and manufacturing to recycling and disposal as well as their wider impact on humans and the places around them. The energy efficiency aspects of the computing system range from electronic circuits to applications for systems covering small IoT devices up to large data centers. This editorial focuses on the security, privacy, and efficiency of sustainable computing for future smart cities. This issue accepted 17 articles after a rigorous review process.

• 한국수소및신에너지학회논문집
• /
• 제30권5호
• /
• pp.411-417
• /
• 2019

An adsorption chiller is connected to the fuel processing/fuel cell system to increase the energy efficiency of the system. Since, the minimum temperature of $70^{\circ}C$ is needed to operate the adsorption chiller, HT-PEMFC is used as a heating source and $80^{\circ}C$ hot water in the water tank at the system is supplied to the chiller. Experimentally measured COP of the adsorption chiller was between 0.4-0.5 and the total calcuated efficiency of the connected system was between 60% and 70% comparing to 47% without adsorption chilling system.

• 전자공학회논문지B
• /
• 제30B권10호
• /
• pp.13-26
• /
• 1993

Motion picture algorithms are realized on the multiprocessor system presented in the Study I. For the most efficient processing of the algorithms, pipelining and geometrical parallel processing methods are employed, and processing time, communication load and efficiency of each algorithm are compared. The performance of the implemented system is compared and analysed with reference to MPEG coding algorithm. Theoretical calculations and experimental results both shows that geometrical partitioning is a more suitable parallel processing algorithm for moving picture coding having the advantage of easy algorithm modification and expansion, and the overall efficiency is higher than pipelining.

• Journal of Information Processing Systems
• /
• 제13권2호
• /
• pp.285-304
• /
• 2017

Big data information and pattern analysis have applications in many industrial sectors. To reduce energy consumption effectively, the eco-driving method that reduces the fuel consumption of vehicles has recently come under scrutiny. Using big data on commercial vehicles obtained from digital tachographs (DTGs), it is possible not only to aid traffic safety but also improve eco-driving. In this study, we estimate fuel consumption efficiency by processing and analyzing DTG big data for commercial vehicles using parallel processing with the MapReduce mechanism. Compared to the conventional measurement of fuel consumption using the On-Board Diagnostics II (OBD-II) device, in this paper, we use actual DTG data and OBD-II fuel consumption data to identify meaningful relationships to calculate fuel efficiency rates. Based on the driving pattern extracted from DTG data, estimating fuel consumption is possible by analyzing driving patterns obtained only from DTG big data.