• KIISE Transactions on Computing Practices
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• v.24 no.1
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• pp.40-45
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• 2018

With the advent of big data and social networks, large-scale graph processing becomes popular research topic. Recently, an optimization technique called Gorder has been proposed to improve the performance of in-memory graph processing. This technique improves performance by optimizing the graph layout on memory to have better cache locality. However, since it is designed for in-memory graph processing systems, the technique is not suitable for disk-based graph engines; also the cost for applying the technique is significantly high. To solve the problem, we propose a new graph ordering called I/O Order. I/O Order considers the characteristics of I/O accesses for SSDs and HDDs to improve the performance of disk-based graph engine. In addition, the algorithmic complexity of I/O Order is simple compared to Gorder, hence it is cheaper to apply I/O Ordering. I/O order reduces the cost of pre-processing up to 9.6 times compared to that of Gorder's, still its performance is 2 times higher compared to the Random in low-locality graph algorithms.

• Journal of KIISE
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• v.42 no.8
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• pp.998-1009
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• 2015

In recent years, there has been a growing interest in RDFS Inference to build a rich knowledge base. However, it is difficult to improve the inference performance with large data by using a single machine. Therefore, researchers are investigating the development of a RDFS inference engine for a distributed computing environment. However, the existing inference engines cannot process data in real-time, are difficult to implement, and are vulnerable to repetitive tasks. In order to overcome these problems, we propose a method to construct an in-memory distributed inference engine that uses a parallel graph structure. In general, the ontology based on a triple structure possesses a graph structure. Thus, it is intuitive to design a graph structure-based inference engine. Moreover, the RDFS inference rule can be implemented by utilizing the operator of the graph structure, and we can thus design the inference engine according to the graph structure, and not the structure of the data table. In this study, we evaluate the proposed inference engine by using the LUBM1000 and LUBM3000 data to test the speed of the inference. The results of our experiment indicate that the proposed in-memory distributed inference engine achieved a performance of about 10 times faster than an in-storage inference engine.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.2
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• pp.36.3-37
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• 2018

By utilizing large-scale graph analytic tools in the modern Big Data platform, Apache Spark, we investigate the topological structures of five different multiverses produced by cosmological n-body simulations with various cosmological initial conditions: (1) one standard universe, (2) two different dark energy states, and (3) two different dark matter densities. For the Big Data calculations, we use a custom build of stand-alone Spark cluster at KIAS and Dataproc Compute Engine in Google Cloud Platform with the sample sizes ranging from 7 millions to 200 millions. Among many graph statistics, we find that three simple graph measurements, denoted by (1) $n_\k$, (2) $\tau_\Delta$, and (3) $n_{S\ge5}$, can efficiently discern different topology in discrete point distributions. We denote this set of three graph diagnostics by kT5+. These kT5+ statistics provide a quick look of various orders of n-points correlation functions in a computationally cheap way: (1) $n = 2$ by $n_k$, (2) $n = 3$ by $\tau_\Delta$, and (3) $n \ge 5$ by $n_{S\ge5}$.

• Journal of the Korea Society of Computer and Information
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• v.24 no.5
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• pp.11-17
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• 2019

In this study, we propose an ensemble engine, which is a framework for game engine optimized for visual novels genre, focusing on storytelling among various game genres. The game of Visual Nobel genre is based on multi-ending story and features branching of various scenarios according to user's choice. The proposed engine supports various multi-scenarios and multi-endings based on nodes according to the characteristics of these genres. In addition, it provides a convenient and intuitive user interface that not only enhances user immersion but also provides VR function to maximize the sense of presence. We will demonstrate the usefulness of the proposed game engine by designing the framework of a game engine suitable for this feature and actually creating variety stories automatically.

• Proceedings of the Korea Information Processing Society Conference
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• 2023.05a
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• pp.383-385
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• 2023

Single-machine-based 그래프 엔진의 state-of-the-art 모델인 RealGraph 는 쓰레드를 이용한 병렬화로 성능을 향상하였으나 쓰레드 내부에서의 병렬성은 고려되지 않았다. 본 논문은 SIMD 명령어를 이용해 RealGraph 의 병렬성을 향상시켰다. 쓰레드 내부의 효율성을 높이기 위해 RealGraph 의 구조와 그래프 알고리즘의 분석을 통한 SIMD 명령어의 적용 가능한 영역을 탐색하였다. 실험으로 SIMD 명령어의 적용을 통해 쓰레드 내부에서 벡터 연산을 수행하여 평균 7.6%, 11.7%, 9.2%의 수행 시간 단축을 이끌어냈으며 SIMD 명령어의 적용이 그래프 엔진의 분석 성능에 얼마나 도움이 될 수 있는지 확인하였다.

• Proceedings of the IEEK Conference
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• 2003.07d
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• pp.1319-1322
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• 2003

We present a web document summarizer, simpler more condense than the existing ones, of a search engine. This summarizer generates summaries with a statistic-based summarization method using Clustering or MMR technique to reduce redundancy in the results, and that generates summaries using Perfect Link Graph. We compare the results with the summaries generated by human subjects. For the comparison, we use FScore. Our experimental results verify the accuracy of the summarization methods.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2003.09a
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• pp.702-705
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• 2003

Directed graph and Lindenmayer system (L-system) are two major encoding methods of representation to develop creatures in an application field of artificial life. It is difficult to structurally define real morphology using the L-systems which are a grammatical rewriting system because they represent genotype as loops, procedure calls, variables, and parameters. This paper defines a class of representations called structured directed graph and interactive genetic algorithm for automatically creating 3D flower morphology. The experimental results show that natural flower morphology can be created by the proposed method.

• 연구논문집
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• s.29
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• pp.29-38
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• 1999

In comparison with gasoline engine, LPG direct injection engine has some advantages not only in emission and fuel efficiency but also in prevention of power decrease and back fire etc. which are disadvantages of conventional LPG engine. In this study, comparision tests of the incylinder spray and combustion characteristics between of LPG and gasoline fuels were performed in the RCEM as a basic research for the development of future LPG engine with low emission and high fuel efficiency During the direct injection of LPG fuel and gasoline into the inside of RCEM, spray development characteristics according to the injection condition have been photographed by the high speed shadow graph methods. The conditions for the optimum mixture distribution of LPG and gasoline fuels are achievable at the selected ignition timing, respectively.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.2
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• pp.500-510
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• 1996

This paper presents a new prototype of an engine mount for a passenger vehicle featuring ER(elector-rheological) fluids and piezoactuators. Conventional rubber mounts and various types of passive or semi-active hydraulic engine mounts have their own functional aims on the limited frequency band in the board engine operating frequency range. However, the proposed engine mount covers all frequency range of the engine operation. A mathematical model of the proposed engine mount is derived using the bond graph method which is inherently domain, the ER fluid is activated upon imposing electric field for vibration isolation while the piezoactuator. Computer control electric fluid for the ER fluid H.inf. cotrol technique is adopted for the piezoactuator. Computer simulation is undertaken in order to demonstrate isolation efficiency of the engine mount over wide operating frequency range.

• Proceedings of the Korea Information Processing Society Conference
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• 2023.05a
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• pp.386-388
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• 2023

본 논문은 고성능 스토리지를 사용하는 환경에서 대규모 그래프를 분석을 위한 GPU 기반 그래프 분석 엔진의 I/O 최적화 전략을 제안한다. 사전 실험을 통해 최신 GPU 기반 그래프 엔진인 RealGraph^GPU 가 고성능 스토리지의 대역폭을 충분히 활용하지 못하고 있음을 발견하였다. 이를 개선하기 위해 (1) User-space I/O, (2) Asynchronous I/O 두 가지 최적화 전략을 적용하였으며, 실험을 통해 두 전략이 RealGraphGPU 의 그래프 분석 성능 향상시키는 데 효과적임을 확인하였다.