• Nuclear Engineering and Technology
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• v.51 no.2
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• pp.501-509
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• 2019

In this paper a body-centered cubic(BCC) crystal plasticity model based on microscopic dislocation mechanism is introduced and numerically implemented. The model is coupled with irradiation effect via tracking dislocation loop evolution on each slip system. On the basis of the model, uniaxial tensile tests of unirradiated and irradiated RPV steel(take Chinese A508-3 as an example) at different temperatures are simulated, and the simulation results agree well with the experimental results. Furthermore, crystal plasticity damage is introduced into the model. Then the damage behavior before and after irradiation is studied using the model. The results indicate that the model is an effective tool to study the effect of irradiation and temperature on the mechanical properties and damage behavior.

• Proceedings of the Korea Contents Association Conference
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• 2008.05a
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• pp.732-737
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• 2008

As e-learning is recognized in new education form, Learning Management System that manage general activity of learning to maximize effect of education is being developed actively. Usually, Learning Management System includes course registration and learning as well as learner's learning recording and tracking, evaluation in online. But, most systems is lacking a tool that learners can collaborate with companion learners, and planning learning and set valuation basis as leading. In this paper, we can expect effective collaborative learning activities because can make debate and team project smooth by suggesting collaborative learning module that can drive voluntary participation such as group formation, learning plan, mutually estimation as leading to learner in Learning Management System of blended learning base that support online and offline environment both.

• Journal of Power Electronics
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• v.18 no.5
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• pp.1398-1408
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• 2018

In order to further improve the steady-state control performance of model predictive torque control (MPTC), a double-vector-based model predictive torque control without a weighting factor is proposed in this paper. The extended voltage vectors synthesized by two basic voltage vectors are used to increase the number of feasible voltage vectors. Therefore, the control precision of the torque and the stator flux along with the steady-state performance can be improved. To avoid testing all of the feasible voltage vectors, the solution of deadbeat torque control is calculated to predict the reference voltage vector. Thus, the candidate voltage vectors, which need to be evaluated by a cost function, can be reduced based on the sector position of the predicted reference voltage vector. Furthermore, a cost function, which only includes a reference voltage tracking error, is designed to eliminate the weighting factor. Moreover, two voltage vectors are applied during one control period, and their durations are calculated based on the principle of reference voltage tracking error minimization. Finally, the proposed method is tested by simulations and experiments.

• Journal of Astronomy and Space Sciences
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• v.31 no.3
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• pp.247-264
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• 2014

In this paper, a brief but essential development strategy for the lunar orbit determination system is discussed to prepare for the future Korea's lunar missions. Prior to the discussion of this preliminary development strategy, technical models of foreign agencies for the lunar orbit determination system, tracking networks to measure the orbit, and collaborative efforts to verify system performance are reviewed in detail with a short summary of their lunar mission history. Covered foreign agencies are European Space Agency, Japan Aerospace Exploration Agency, Indian Space Research Organization and China National Space Administration. Based on the lessons from their experiences, the preliminary development strategy for Korea's future lunar orbit determination system is discussed with regard to the core technical issues of dynamic modeling, numerical integration, measurement modeling, estimation method, measurement system as well as appropriate data formatting for the interoperability among foreign agencies. Although only the preliminary development strategy has been discussed through this work, the proposed strategy will aid the Korean astronautical society while on the development phase of the future Korea's own lunar orbit determination system. Also, it is expected that further detailed system requirements or technical development strategies could be designed or established based on the current discussions.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1888-1889
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• 2011

본 논문에서는 다수의 네트워크 카메라를 이용한 협동 추적 알고리즘을 제안하고자 한다. 이를 위해 먼저 모션 템플릿 기법을 통하여 영상내의 움직임 영역을 추출한다. 이후 움직임 영역이 추출되면 이웃한 카메라에 협동요청을 하고 칼만 필터를 이용하여 움직임 영역의 위치를 보정하여 정확한 PTZ변수를 설정한다. 또한 협동요청을 받은 이웃 카메라는 요청받은 PTZ변수를 이용하여 움직임 물체를 협동 추적한다. 마지막으로, 본 논문에서 제안하는 협동 추적 알고리즘에 대한 실험을 통하여 제안된 협동 추적 알고리즘의 성능분석 및 그 응용 가능성을 증명한다.

• 한국HCI학회:학술대회논문집
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• 2007.02a
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• pp.316-320
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• 2007

다수의 사용자가 동일한 디스플레이 화면을 보면서 의사를 교환하거나 공동 작업을 수행하는 협업환경에서의 인터랙션 기술은 네트워크 기술, 디스플레이 기술만큼이나 효율적인 협업을 위해 중요한 요소 기술이다. 이러한 인터랙션의 성공적인 수행을 위해서 중요한 기능 중의 하나는 사용자의 상황인식을 들 수 있는데 이는 사용자의 돌발 행동, 사용자들간의 의사교환 정도 등을 측정하고 예측하는데 유용하게 사용될 수 있다. 협업환경 내에서의 사용자의 위치 파악은 사용자의 상황인식뿐 아니라 다수의 사용자가 동시에 레이저 포인터를 이용하여 디스플레이 장치를 가리키고 있는 경우, 어느 사용자가 디스플레이 화면 중 어느 위치를 포인팅 하고 있는지를 계산하는데 도움을 줄 수 있다. 본 연구에서는 제한된 환경 내에서 사용자의 3차원 위치를 추적할 수 있는 시스템을 제안한다. 개발된 시스템은 사용자의 위치 계산뿐 아니라 사용자의 제스처도 함께 인식하여 사용자가 협업환경 시스템을 제어할 수 있고 공중에서 글씨 쓰는 등의 인터랙션도 수행할 수는 기능을 지원한다.

• Journal of Korean Institute of Industrial Engineers
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• v.40 no.1
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• pp.100-107
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• 2014

This paper presents a co-located and mobile interaction technique using smartphones in a global space. To effectively detect the locations and orientations of smartphones, the proposed approach utilizes Kinect that captures RGB image as well as 3D depth information. Based on the locations and orientations of smartphones, the proposed approach can support direct, collaborative and private interactions with the global space. Thus, it can provide more effective mobile interactions for local space exploration and collaboration.

• Proceedings of the Korea Information Processing Society Conference
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• 2023.11a
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• pp.595-596
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• 2023

스마트팩토리의 핵심 설비 기기인 협동로봇의 유지보수를 위해 다양한 센서 데이터를 활용한 딥러닝 기반 결함 진단 연구가 확대되고 있다. 하지만 협동로봇은 기계적 특성과 수행하는 작업의 다양성으로 인해 내부 센서 데이터의 복잡도가 매우 높아 고정적인 결함 진단 기법을 적용하기 어렵다. 따라서 본 논문은 협동로봇의 동작 패턴을 직관적이고 신속하게 인지할 수 있는 비전 기술을 활용하여, 동작 오류 진단을 기반으로 원인이 되는 조인트 결함 위치를 추적하는 딥러닝 기법을 제안한다.

• Journal of the HCI Society of Korea
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• v.2 no.1
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• pp.57-63
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• 2007

Our research was performed in order to implement a new pointing device for human-computer interactions in a collaborative environments based on Tiled Display system. We mainly focused on tracking the position of an infrared light source and applying our system to various areas. More than simple functionality of mouse clicking and pointing, we developed a device that could be used to help people communicate better with the computer. The strong point of our system is that it could be implemented in any place where a camera can be installed. Due to the fact that this system processes only infrared light, computational overhead for LED recognition was very low. Furthermore, by analyzing user's movement, various actions are expected to be performed with more convenience. This system was tested for presentation and game control.

• Proceedings of the Korea Information Processing Society Conference
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• 2023.11a
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• pp.140-142
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• 2023

Federated learning (FL) is a new paradigm in machine learning (ML) that enables multiple devices to collaboratively train a shared ML model without sharing their local data. FL is well-suited for applications where data is sensitive or difficult to transmit in large volumes, or where collaborative learning is required. The Internet of Underwater Things (IoUT) is a network of underwater devices that collect and exchange data. This data can be used for a variety of applications, such as monitoring water quality, detecting marine life, and tracking underwater vehicles. However, the harsh underwater environment makes it difficult to collect and transmit data in large volumes. FL can address these challenges by enabling devices to train a shared ML model without having to transmit their data to a central server. This can help to protect the privacy of the data and improve the efficiency of training. In this view, this paper provides a brief overview of Fed-IoUT, highlighting its various applications, challenges, and opportunities.