• Journal of KIISE:Computing Practices and Letters
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• v.11 no.6
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• pp.465-476
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• 2005

In this paper, we propose a new dynamic reconfiguration method using application-level checkpointing in a grid computing environment with Cactus and Globus. The existing dynamic reconfiguration methods have been dependent on a specific hardware and operating system. But the proposed method performs a dynamic reconfiguration without supporting specific hardwares and operating systems and, an application is programmed without considering a dynamic reconfiguration. In the proposed method, the job starts with an initial configuration of Computing resources and the job restarts including new resources dynamically found at run-time. The proposed method determines whether to include the newly found idle sites by considering processor performance and available memory of the sites. Our method writes the intermediate results of the job on the disks using system-independent application-level checkpointing for real-time visualization during the job runs. After reconfiguring idle sites and idle processors newly found, the job resumes using checkpointing files. The proposed dynamic reconfiguration method is proved to be valid by decreasing total execution time In K*Grid.

• Korean Journal of Remote Sensing
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• v.22 no.6
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• pp.595-600
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• 2006

GOCI is the core paryload of the geostationary satellite COMS(Communication, Ocean and Meteological Satellite) for ocean monitoring. It is scheduled to be launched at the end of 2008. GOCI observes ocean color around the Korean Peninsula over $2500km\times2500km$ area. It used tilted two-axis scan mechanism to observe entire field of view. In this work, the pointing stability of the tilted two-axis method is analyzed and compared with that of gimbal method. The analysis results show that tilted two-axis method gives great stability and it is adequate for geostationary payload. The results can also be used to determine and analyze the mechanism specifications.

• Proceedings of the Korean Information Science Society Conference
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• 2005.11a
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• pp.775-777
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• 2005

무선 센서 네트워크는 다양한 환경에서 자연의 정보를 수집하여 인간이 필요로 하는 형태로 정보를 제공하는 네트워크이다. 이러한 센서 네트워크는 수많은 우선 센서 노드들로 이루어지고, 각 센서 노드는 자율적으로 자연의 정보를 계측하고, 이웃 노드와 통신하며, 결함 발생시에 이를 허용하고 대처할 수 있어야 한다. 본 논문에서는 무선 센서 네트워크를 위한 모바일 체크포인팅 기법을 소개한다. 모바일 체크포인팅 기법을 통하여, 보다 안정적인 결함 허용 무선 센서 네트워크를 구현해 낼 수 있고, 실험 결과를 통하여 이 기법을 사용하였을 때에 전체 센서 네트워크가 보다 더 안정적으로 동작할 수 있음을 보인다.

• Proceedings of the Korean Information Science Society Conference
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• 2006.06a
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• pp.160-162
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• 2006

최근 모바일 환경에서 모바일 기기가 결항에 쉽게 노출될 수 있다는 특성 때문에 모바일 컴퓨팅 시스템에서의 결함 허용에 대한 관심이 높아지고 있다. 결함 허용을 제공하기 위한 기법 중 하나로 체크포인팅을 들 수 있는데, 이를 모바일 환경에 적용하기 위해서는 체크포인트의 실행으로 인해 모바일 기기에 가해지는 과부하를 줄이는 것이 중요하다. 따라서 본 논문에서는 각각의 프로세스가 독립적으로 실행하는 BASIC 체크포인트를 없앰으로써 과부하를 줄이기 위한 체크포인팅 기법을 제안한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2002.11a
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• pp.463-466
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• 2002

본 논문에서는 주어진 이미지를 균일하게 블록화 시킨 후 각각의 Range 블록에서 Domain 블록을 찾아나간다. 각 Range 블록마다 Domain 블록이 찾아지게 되면 픽셀별로 포인팅을 하게 한다. 이러한 포인팅을 이용하여 링크드 리스트를 만들어 나가게 되면 사이클을 포함하게 되는 링크드 리스트가 조인된 형태의 모습을 갖게 된다. 그러면 사이클을 포함하는 이러한 형태의 픽셀의 평균값을 계산하여 뿌려주게 되는 것이다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.1
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• pp.121-127
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• 2013

A vision based hand-gesture interface method for substituting a pointing device is proposed in this paper, which is used the ratio and size variation of Gesture Region. Proposed method uses the skin hue&saturation of the hand region from the HSI color model to extract the hand region effectively. This method can remove the non-hand region, and reduces the noise effect by the light source. Also, as the computation quantity is reduced by detecting not the static hand-shape recognition, but the ratio and size variation of hand-moving from the clipped hand region in real time, more response speed is guaranteed. In order to evaluate the performance of the our proposed method, after applying to the computerized self visual acuity testing system as a pointing device. As a result, the proposed method showed the average 86% gesture recognition ratio and 87% coordinate moving recognition ratio.

• Journal of KIISE
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• v.44 no.2
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• pp.132-138
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• 2017

We design and implement a process-based fault recovery system to increase the reliability of new memory based computer systems. A rollback point is made at every context switch to which a process can rollback to upon a fault. In this study, a clone process of the original process, which we refer to as a P-process (Persistent-process), is created as a rollback point. Such a design minimizes losses when a fault does occur. Specifically, first, execution loss can be minimized as rollback points are created only at context switches, which bounds the lost execution. Second, as we make use of the COW (Copy-On-Write）mechanism, only those parts of the process memory state that are modified (in page units) are copied decreasing the overhead for creating the P-process. Our experimental results show that the overhead is approximately 5% in 8 out of 11 PARSEC benchmark workloads when P-process is created at every context switch time. Even for workloads that result in considerable overhead, we show that this overhead can be reduced by increasing the P-process generation interval.

• Journal of Astronomy and Space Sciences
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• v.24 no.2
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• pp.145-154
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• 2007

Antenna pointing analysis for a geostationary satellite has been performed for using the NORAD Two-Line-Elements (TLE) converted from osculating Keplerian orbital elements. In order to check the possibility of the reception of the satellite signal, the antenna offset angles have been derived for the Communications, Ocean, and Meteorological Satellite (COMS) which carries out weekly East-West and North-South station-keeping maneuvers and twice a day thruster assisted momentum dumping. Throughout the analysis, it is shown that the use of converted NORAD TLE simplifies the antenna pointing related interfaces in satellite mission control system. For a highly eccentric transfer orbit cases, further analysis presents that the converted NORAD TLE from near apogee gives more favorable results.

• The KIPS Transactions:PartA
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• v.15A no.2
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• pp.111-118
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• 2008

With the advance in mobile communication systems, the need for distributed applications running on multiple mobile devices also grows gradually. As such applications are subject to H/W failures of the mobile device or communication disruptions, compared to the traditional applications in fixed networks, it is crucial to develop any recovery mechanism suitable for them. For this, checkpointing is widely used to restart interrupted applications. In this paper, we devise an efficient checkpointing method that adopts the software agent executed at the mobile support station. The agent, called the checkpointing agent, is aimed at supporting the concept of rollback-distance (R-distance) that bounds the maximum number of roll-backed local checkpoints. By means of the R-distance, our method can prevent undesirable domino effects and heavy checkpoint overhead, while providing high flexibility in checkpoint creation.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.45 no.6
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• pp.133-141
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• 2008

As interactive multimedia have come into wide use, user interfaces such as remote controllers or classical computer mice have several limitations that cause inconvenience. We propose a vision-based pointing device to resolve this problem. We analyzed the moving image from the camera which is embedded in the pointing device and estimate the movement of the device. The pose of the cursor can be determined from this result. To process in the real time, we used the low resolution of $288{\times}208$ pixel camera and comer points of the screen were tracked using local optical flow method. The distance from screen and device was calculated from the size of screen in the image. The proposed device has simple configurations, low cost, easy use, and intuitive handhold operation like traditional mice. Moreover it shows reliable performance even in the dark condition.