• 한국HCI학회:학술대회논문집
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• 2006.02a
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• pp.203-209
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• 2006

햅틱 렌더링이 발전함에 따라서 촉감을 통하여 사용자에게 전달하려고 하는 가상 물체의 성질도 다양해 지고 있다. 이 논문은 균일하지 않은 강도(Stiffness)를 가지는 가상 물체를 기존의 페널티 기반 알고리즘(Penalty-based algorithms)을 사용하여 렌더링하는 경우 물체 표면의 모양(Topography)이 사용된 모델과 달리 왜곡되어 인지되는 현상을 해결하기 위한 햅틱 렌더링 알고리즘에 관한 연구를 보고한다. 첫 번째로 저자의 선행 연구인 힘 유지 가설(Force Constancy Hypothesis) - 사용자가 물체 표면의 모양을 획득하기 위해 물체를 만질 때 일정한 크기의 접촉 힘을 유지한다 - 을 소개한다. 다음으로 힘 유지 가설에 기반한 물체의 모양 및 강도를 왜곡 없이 정확하게 렌더링하는 알고리즘을 제안하고 폴리곤 모델에 적용하는 방법을 설명한다. 마지막으로 실험을 통하여 개발된 알고리즘의 성능을 입증한다.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.11 no.2
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• pp.1-8
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• 2002

Cutting force is obtained as a sum of chip removing force and ploughing force. Chip removing force is estimated by multiplying specific cutting pressure by cutting area. Since ploughing force is caused from dullness of a tool, its magnitude is constant if depth of cut is bigger than a certain value. Using the linearity of chip removing force to cutting area and the constancy of ploughing force regardless of depth of cut which is over a certain limit each force is separated from measured cutting force and used to establish cutting force model. New rotation matrix to convert the measured cutting force in reference axes into the forces in cutter axes is obtained by considering that tool angles are projected angles from cutter axes to reference axes.. Spindle tilt is also considered far the model. The predicted cutting force estimated from the model is in good agreement with the measured force.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.9
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• pp.4287-4306
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• 2016

Network resilience provides an effective way to overcome the problem of network failure and is crucial to Internet protocol (IP) network management. As one of the main challenges in network resilience, recovering from link failure is important to maintain the constancy of packets being transmitted. However, existing failure recovery approaches do not handle the traffic engineering problem (e.g., tuning the routing-protocol parameters to optimize the rerouting traffic flow), which may cause serious congestions. Moreover, as the lack of QoS (quality of service) restrictions may lead to invalid rerouting traffic, the QoS requirements (e.g., bandwidth and delay) should also be taken into account when recovering the failed links. In this paper, we first develop a probabilistically correlated failure model that can accurately reflect the correlation between link failures, with which we can choose reliable backup paths (BPs). Then we construct a mathematical model for the failure recovery problem, which takes maximum rerouting traffic as the optimizing objective and the QoS requirements as the constraints. Moreover, we propose a heuristic algorithm for link failure recovery, which adopts the improved k shortest path algorithm to splice the single BP and supplies more protection resources for the links with higher priority. We also prove the correctness of the proposed algorithm. Moreover, the time and space complexity are also analyzed. Simulation results under NS2 show that the proposed algorithm improves the link failure recovery rate and increases the QoS satisfaction rate significantly.

• Journal of the Korean Institute of Landscape Architecture
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• v.36 no.3
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• pp.52-62
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• 2008

By analyzing specific plant distributions and physicochemical characteristics of topsoil in a reclaimed dredging area, baseline data was found of natural landscape planting sites, and developing dredged fill ground. The reclaimed dredging area is five different stands (1, 2, 3, 4 and 5) which were examined in this research. They are located from sea level to 15 meters in altitude and exhibited typical characteristics of the salt marsh in Gwangyang Bay. Species with high constancy in the vegetation on the reclaimed soil were classified into four stages. A total of 12, 15, 22, 27 and 35 different plant species were found and also increased in stands 1, 2, 3, 4 and 5, respectively. Moving from stand 1 to 5, halophytes decreased and non-halophytes increased. Desalination at each stage of the reclaimed dredging area was a driving force affecting the performance and distribution of halophytes and non-halophytes. Overall, 35 quadrats of soil were selected and analyzed for specific physicochemical characteristics of topsoil between O${\sim}$20cm. Results of the physicochemical analysis such as altitude, slope, vegetation and kind of reclaimed dredging soil, exhibited irregular increases or decreases. As survey areas moved from stand 1 to 4, desalination areas, soil acidity, electric conductions, content of salinity, available phosphorus, potassium, chlorine, calcium, and magnesium indicated decreasing patterns; however, total nitrogen, silt, and clay content increased. Cluster analysis and PCA by environmental data within the stands clearly showed five distinct vegetation patterns on the tested reclaimed area. These results indicate that the differences of performance and distribution of vegetation are due to the SAR in the reclaimed soil and related to the natural survival strategy at the given hostile habitat.