• International Journal of Fuzzy Logic and Intelligent Systems
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• 제4권3호
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• pp.327-336
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• 2004

In distributed autonomous mobile robot system, each robot (predator or prey) must behave by itself according to its states and environments, and if necessary, must cooperate with other robots in order to carry out a given task. Therefore it is essential that each robot have both learning and evolution ability to adapt to dynamic environment. This paper proposes a pursuing system utilizing the artificial life concept where virtual robots emulate social behaviors of animals and insects and realize their group behaviors. Each robot contains sensors to perceive other robots in several directions and decides its behavior based on the information obtained by the sensors. In this paper, a neural network is used for behavior decision controller. The input of the neural network is decided by the existence of other robots and the distance to the other robots. The output determines the directions in which the robot moves. The connection weight values of this neural network are encoded as genes, and the fitness individuals are determined using a genetic algorithm. Here, the fitness values imply how much group behaviors fit adequately to the goal and can express group behaviors. The validity of the system is verified through simulation. Besides, in this paper, we could have observed the robots' emergent behaviors during simulation.

• 한국태양에너지학회 논문집
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• 제38권6호
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• pp.65-72
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• 2018

Since data-driven building technologies have been widely applied to building energy systems, the accuracy of building sensors has more impacts on the building performance and system performance analysis. Various building sensors, however, can have typical errors including a random error (noise) and a systematic error (bias). The systematic error is indicated by the difference between the mean of measurements and their true value. It may occur due to the sensor's physical condition, measured phenomena, working environments inside the systems. Unfortunately, a conventional calibration method has limitations in calibrating the systematic errors because of the difference between working environments and calibration conditions. In such situations, a novel sensor calibration method is needed to handle various sensor errors, especially for systematic errors, in building energy systems having various thermodynamic environments. This study proposes a building sensor calibration method named Virtual In-situ Calibration (VIC) and shows how it is applied into a real building system and how it solves the sensor errors.

• 센서학회지
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• 제25권5호
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• pp.365-370
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• 2016

The study about VR (Virtual Reality) has been done from the 1960s, but technical limits and high cost made VR hard to commercialize. However, in recent, high resolution display, computing power and 3D sensing have developed and hardware has become affordable. Therefore, normal users can get high quality of immersion and interaction. However, HMD devices which offer VR environment have high latency, so it disrupts the VR environment. People are usually sensitive to relative latency over 20ms. In this paper, as adding the Electromyogram (EMG) sensors to typical IMU sensor only system, the latency reduction method is proposed. By changing software and hardware components, some cases the latency was reduced significantly. Hence, this study covers the possibility and the experimental verification about EMG sensors for reducing the latency.

• 대한임베디드공학회논문지
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• 제9권4호
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• pp.237-243
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• 2014

In this paper we present an real-time obstacle avoidance technique of autonomous mobile robot with steering system and implementation of user interface for mobile devices with Android platform. The direction of autonomous robot is determined by virtual force field concept, which is based on the distance information acquired from 5 ultrasonic sensors. It is converted to virtual repulsive force around the autonomous robot which is inversely proportional to the distance. The steering system with PD(proportional and derivative) controller moves the mobile robot to the determined target direction. We also use PSD(position sensitive detector) sensors to supplement ultrasonic sensors around dead angle area. The mobile robot communicates with Android mobile device and PC via Ethernet. The video information from CMOS camera mounted on the mobile robot is transmitted to Android mobile device and PC. And the user can control the mobile robot manually by transmitting commands on the user interface to it via Ethernet.

• 대한임베디드공학회논문지
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• 제9권6호
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• pp.307-314
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• 2014

Recently, software reliability and safety issues are seriously considered since failures of embedded systems may cause the damages of human lifes. For verifying and testing embedded software, execution environment including sensors and actuators should be prepared in the actual plants or virtual forms on PC. In this paper, we provide the virtual prototype based code simulation techniques and testing framework on PC. Virtual prototypes are generated by combining the Adobe's Flash SWF images corresponding to the state machine of HW or environment components. Code simulation on PC is possible by replacing the device drivers into virtual drivers which connect to virtual prototypes. Also, testing is performed by controlling the states of virtual prototype and simulators. By using these tools, embedded software can be executed in the earlier development phase and the efficiency and SW quality can be enhanced.

• 한국지진공학회논문집
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• 제21권6호
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• pp.287-293
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• 2017

Sometimes, it is impossible to install a sensor on a certain location of a structure due to the size of a structure or poor surrounding environments. Even if possible, sensors can be frequently malfunctioned or improperly operated due to lack of adequate maintenance. These kind of problems are solved by the virtual sensing methods in various engineering fields. Virtual sensing technology is a technology that can measure data even though there is no physical sensor. It is expected that this technology can be also applied to the construction field effectively. In this study, a virtual sensing technology based on ARX model is proposed. An ARX model is defined by using the simulated data through a structural analysis rather than by actually measured data. The ARX-based virtual sensing model can be applied to estimate unmeasured response using a transfer function that defines the relationship between two point data. In this study, a simulation and experimental study were carried out to examine the proposed virtual sensing method with a laboratory test on a cable-stayed model bridge. Acceleration measured at a girder is transformed to estimate a cable tension through the ARX model-based virtual sensing.

• 한국컴퓨터그래픽스학회논문지
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• 제24권5호
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• pp.41-48
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• 2018

가상 환경에서 몰입감을 높이고 자유로운 상호작용을 제공하기 위한 가장 자연스러운 방법은 사용자의 손을 이용한 제스처 인터페이스를 제공하는 것이다. 그러나 손 제스처 인식에 관한 기존의 연구들은 특화된 센서나 장비를 요구하거나 낮은 인식률을 보이는 단점이 있다. 본 논문은 손 제스처 입력을 위한 RGB 카메라 이외 별도 센서나 장비 없이 손 제스처 인식이 가능한 3차원 DenseNet 합성곱 신경망 모델을 제안하고 이를 기반으로 한 가상현실 게임을 소개한다. 4개의 정적 손 제스처와 6개의 동적 손 제스처 인터페이스에 대해 실험한 결과 평균 50ms의 속도로 94.2%의 인식률을 보여 가상현실 게임의 실시간 사용자 인터페이스로 사용 가능함을 알 수 있었다. 본 연구의 결과는 게임 뿐 아니라 교육, 의료, 쇼핑 등 다양한 분야에서 손 제스처 인터페이스로 활용될 수 있다.

• 정보처리학회논문지B
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• 제14B권2호
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• pp.119-126
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• 2007

가상환경에서 학습 방식에 따른 학습 효과를 학습자의 주의와 기억량 분석을 중심으로 연구하였다. 교안유도 방식(Guided learning)과 고안 비유도 방식(Unguided learning)의 학습이 주어진 상태에서 뇌파, 심전도, 피부저항과 시선추적 생체신호장비를 사용하여 학습자 주의측정을 하였고, 학습자의 학습태도, 느낌, 기억량 등을 실험시 비디오와 실험 후 설문분석을 이용하여 분석하였다. 실험 결과는 교안유도 방식이 학습자의 주의를 교안으로 끄는 데는 효율적이어서 많은 교안내용을 기억하게 했으나, 교안비유도 방식에 비해 상대적으로 학습자가 느끼는 체감 흥미는 떨어진 것으로 나타났다. 그와는 대조적으로 교안비유도 방식에서 학습자들은 교안과 교안외 내용을 모두 비교적 광범위하게 기억하고 있었고, 능동적이며 자율적인 학습을 하였다. 또한 교안비유도 후 교안유도 방식의 학슬을 했을 경우 그 반대의 경우보다 훨씬 더 학습호과가 좋았다. 이는 교안비유도 방식이 사전 예비학습 효과를 주었기 때문으로 해석된다. 실험결과를 통해 본 논문에서는 교안비유도 방식을 먼저 학습한 후에 교안유도방식으로 학습을 진행하는 것이 학습자의 학습 효과와 체감흥미에서 더욱 효율적임을 제시하였다.

• 한국멀티미디어학회논문지
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• 제24권3호
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• pp.355-372
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• 2021

Recently, high-performance HMDs (Head-Mounted Display) are becoming wireless due to the growth of virtual reality technology. Accordingly, environmental constraints on the hardware usage are reduced, enabling multiple users to experience virtual reality within a single space simultaneously. Existing multi-user virtual reality platforms use the user's location tracking and motion sensing technology based on vision sensors and active markers. However, there is a decrease in immersion due to the problem of overlapping markers or frequent matching errors due to the reflected light. Goal of this study is to develop a multi-user virtual reality moving platform in a single space that can resolve sensing errors and user immersion decrease. In order to achieve this goal hybrid sensing technology was developed, which is the convergence of vision sensor technology for position tracking, IMU (Inertial Measurement Unit) sensor motion capture technology and gesture recognition technology based on smart gloves. In addition, integrated safety operation system was developed which does not decrease the immersion but ensures the safety of the users and supports multimodal feedback. A 6 m×6 m×2.4 m test bed was configured to verify the effectiveness of the multi-user virtual reality moving platform for four users.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 춘계학술대회 논문집
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• pp.722-725
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• 2014

The spatial focusing of time reversal Lamb waves on a plate has attracted considerable attention for identifying the location of an input source. This study investigates the spatial focusing performance on a plate with respect to the number of piezoelectric (PZT) sensors for varying locations of input sources. In particular, a small number of PZT sensors produce spatial focusing through the virtual sensor effect due to reflection of Lamb waves at plate edges. The spatial focusing performance with respect to the number of PZT sensors is quantified in terms of signal to noise ratio through numerical simulation and its implication is discussed.