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Technology and Applications of Character Recognition for Distance Information of Sewerage Surface Recording Videos
Jong-Rul Park, Min-Gyu Kong, Jungho Kim, Joung Woo Ryu
http://doi.org/10.5626/JOK.2024.51.10.862
Our research proposes a character recognition method for distance information overlaid with sewerage surface recorded clips. To implement the character recognition function on specified locations for each district in Seoul, Republic of Korea, our proposed training procedure of the character recognition model consists of captured image frames and types of fonts from sewerage surface recorded clips of each district in Seoul. This study investigated image processing application that minimizes interferences among character output areas, including overlaid areas between rows of character output areas and background images. The accuracy of character recognition regarding sewerage recorded clips from a total of 25 districts in Seoul was 99.2%, which was 38.9% higher than the accuracy evaluated by character recognition from an open-sourced library, and 31.5% higher than previous research held by city hall in Seoul.
Techniques to Guarantee Real-Time Fault Recovery in Spark Streaming Based Cloud System
Jungho Kim, Daedong Park, Sangwook Kim, Yongshik Moon, Seongsoo Hong
In a real-time cloud environment, the data analysis framework plays a pivotal role. Spark Streaming meets most real-time requirements among existing frameworks. However, the framework does not meet the second scale real-time fault recovery requirement. Spark Streaming fault recovery time increases in proportion to the transformation history length called lineage. This is because it recovers the last state data based on the cumulative lineage recorded during normal operation. Therefore, fault recovery time is not bounded within a limited time. In addition, it is impossible to achieve a second-scale fault recovery time because it costs tens of seconds to read initial state data from fault-tolerant storage. In this paper, we propose two techniques to solve the problems mentioned above. We apply the proposed techniques to Spark Streaming 1.6.2. Experimental results show that the fault recovery time is bounded and the average fault recovery time is reduced by up to 41.57%.
Framework-assisted Selective Page Protection for Improving Interactivity of Linux Based Mobile Devices
Seungjune Kim, Jungho Kim, Seongsoo Hong
While Linux-based mobile devices such as smartphones are increasingly used, they often exhibit poor response time. One of the factors that influence the user-perceived interactivity is the high page fault rate of interactive tasks. Pages owned by interactive tasks can be removed from the main memory due to the memory contention between interactive and background tasks. Since this increases the page fault rate of the interactive tasks, their executions tend to suffer from increased delays. This paper proposes a framework-assisted selective page protection mechanism for improving interactivity of Linux-based mobile devices. The framework-assisted selective page protection enables the run-time system to identify interactive tasks at the framework level and to deliver their IDs to the kernel. As a result, the kernel can maintain the pages owned by the identified interactive tasks and avoid the occurrences of page faults. The experimental results demonstrate the selective page protection technique reduces response time up to 11% by reducing the page fault rate by 37%.
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