본 논문은 온라인 모바일 게임이용이 자기 효능감(self-efficacy) 및 사회성(sociality), 사회적 신뢰(social trust)에 대해 갖는 효과를 검증하고자 하는 목적에서 쓰여졌다. 본 논문은 모바일 플랫폼의 등장에 따라 게임에 광범위하게 도입되고 있는 SNS적 요소(커뮤니티 운영과 소통기 능)에 주목하였고, 이러한 논리에 근거하여 게임플레이는 게임유저의 자기 효능감과 사회성, 사 회적 신뢰를 높인다는 가설을 설정하였다. 연구를 위해 전문여론조사기관에 의뢰해 전국 대표 성을 가진 샘플 1500명을 대상으로 온라인 서베이를 시행하였다. 연구 결과 온라인 게임 플레 이는 유저들의 자기 효능감을 높일 뿐만 아니라, 사회성 및 사회적 신뢰의 향상에 직·간접적인 영향을 미치는 것으로 나타났다.

For the underwater localization, acoustic sensor systems are widely used due to greater penetration properties of acoustic signals in underwater environments. On the other hand, the good penetration property causes multipath and interference effects in structured environment too. To overcome this demerit, a localization method using the attenuation of electro-magnetic(EM) waves was proposed in several literatures, in which distance estimation and 2D-localization experiments show remarkable results. However, in 3D-localization application, the estimation difficulties increase due to the nonuniform (doughnut like) radiation pattern of an omni-directional antenna related to the depth direction. For solving this problem, we added a depth sensor for improving underwater 3D-localization with the EM wave method. A micro scale pressure sensor is located in the mobile node antenna, and the depth data from the pressure sensor is calibrated by the curve fitting algorithm. We adapted the depth(z) data to 3D EM wave pattern model for the error reduction of the localization. Finally, some experiments were executed for 3D localization with the fast calculation and less errors.

본 연구에서는 2005년부터 2013년까지 운용되었던 국내 연안여객선의 항로를 사회네트워크 분석 방법을 통해 파악하였다. 우선 국 내 연안여객 항로의 네트워크 특성을 살펴본 결과 네트워크 복잡계 특성인 멱함수의 법칙을 따르는 Scale-Free 형태를 보이고 있음을 확인하 였다. 본 연구에서는 사회 네트워크 분석의 중요 척도라고 할 수 있는 중심성을 바탕으로 살펴보았으며, 연도별 연결정도 중심성의 변화추세, 기존의 정량적인 방법과의 비교를 통한 양의 상관관계 확인, 마지막으로 연결정도 중심성과 매개 중심성간의 관계를 분석하여 두 가지의 척도를 기준으로 우선시되는 항구를 순위별로 확인할 수 있었다. 본 연구는 연안여객 항로를 하나의 네트워크로 간주하고 분석하여 유용한 결과를 제시하였다. 앞선 결과들을 바탕으로 국내 연안여객 항로의 개발 등 발전방향을 설정할 시 보다 효과적으로 진행이 가능할 것으로 보인다. 또 한 공항의 중심성 분석, 주변국의 외교 관계 분석 등 다양한 분야에서 사회네트워크 분석 방법을 활용한다면 유용한 결과를 산출하는데 효과적 일 것으로 판단된다.

In this paper, an exact reshaping method for the motor dynamics of a flexible-joint robot is proposed using an integral manifold approach. Obtaining the exact model for both motor-side and linkside dynamics of a flexible-joint robot is difficult due to its under-actuated nature and complex dynamics. Despite the simple structure of the motor-side dynamics, they are difficult to model accurately for a flexible-joint robot due to motor disturbances, especially when speed reducers such as harmonic drives are installed. An integral manifold feedback control (IMFC) is proposed to reshape the motor dynamics. Based on the integral manifold approach, it is theoretically proved that the IMFC reshapes motor dynamics exactly even with bounded disturbances such as motor friction. The performance of the proposed IMFC is verified experimentally using a single degree-of-freedom flexible-joint robot under gravity conditions.

In this paper, an external torque estimation problem in one-degree-of-freedom (1-DOF) flexible-joint robot equipped with a joint-torque sensor is revisited. Since a sensor torque from the jointtorque sensor is distorted by two dynamics having a spring connection, i.e., motor dynamics and link dynamics of a flexible-joint robot, a model-based estimation, rather than a simple linear spring model, should be required to extract external torques accurately. In this paper, an external torque estimation algorithm for a 1-DOF flexible-joint robot is proposed. This algorithm estimates both an actuating motor torque from the motor dynamics and an external link torque from the link dynamics simultaneously by utilizing the flexible-joint robot model and the Kalman filter estimation based on random-walk model. The basic structure of the proposed algorithm is explained, and the performance is investigated through a custom-designed experimental testbed for a vertical situation under gravity.

A local map-based exploration algorithm for mobile robots is presented. Segmented frontiers and their relative transformations constitute a tree structure. By the proposed efficient frontier segmentation and a local map management method, a robot can reduce the unknown area and update the local grid map which is assigned to each frontier node. Although this local map-based exploration method uses only local maps and their adjacent node information, mapping completion and efficiency can be greatly improved by merging and updating the frontier nodes. Also, we suggest appropriate graph search exploration methods for corridor and hall environments. The simulation demonstrates that the entire environment can be represented by well-distributed frontier nodes.

이 연구에서는 GPS 기준국 주변에 존재하는 장애물의 방향과 고도각이 좌표 정확도 변화에 미치는 영향을 시뮬레이션을 통해 분석하고자 한다. 최적의 관측환경에 있는 기준국의 정밀좌표를 산출한 뒤 고도각 10˚부터 70˚까지의 장애물이 동, 서, 남 방향에 각각 존재한다고 가정하고 관측자료를 재구성하였다. 10일간의 관측자료를 이용하여 일단위와 시간단위로 각각 처리하였다. 일단위 처리결과에서는 RMSE가 10mm 내외였으나 시간단위 결과에서는 100mm 수준까지 증가하였다. 장애물의 고도각이 높아질수록 수평 및 수직방향 RMSE는 증가하였고 높이 추정값은 감소하였다. 방향에 따른 분석에서는 동쪽이나 서쪽에 장애물이 존재할 때 남북방향에 비해 동서방향으로 위치오차가 더 크게 증가하였고 남쪽 장애물인 경우에는 동서방향의 오차폭이 상대적으로 작게 나타났다.

In this paper, a localization algorithm and an autonomous controller for PETASUS system II which is an underwater vehicle-manipulator system, are proposed. To estimate its position and to identify manipulation targets in a structured environment, a multi-rate extended Kalman filter is developed, where map information and data from inertial sensors, sonar sensors, and vision sensors are used. In addition, a three layered control structure is proposed as a controller for autonomy. By this controller, PETASUS system II is able to generate waypoints and make decisions on its own behaviors. Experiment results are provided for verifying proposed algorithms.

2006~2007년까지 2개년에 걸쳐 전국 8개도 27개 지역 28개 시험구에서 재배한 시료를 바탕으로 등숙기 온도가 벼의 등숙형질에 미치는 영향을 분석하고 식미치 향상에 적합한 등숙온도를 추적한 결과는 다음과 같다. 1. 출수기~출수 후 30일까지의 평균기온이 출수 후 40일까지의 평균기온 보다 벼의 등숙정도를 나타내는 현미 천립중과 식미치 변이를 더 잘 설명할 수 있었다. 2. 시험에 사용된 중만생종 벼 품종들은 출수기~출수 후 30일까지의 평균기온이 21℃ 이하일 경우에는 저온으로 등숙이 불량하였고 22℃ 전후에서 현미천립중이 최고를 나타내었으며 그 이상의 온도에서는 온도가 올라갈수록 현미천립중이 감소하였다. 3. 현미천립중이 최대가 되는 출수기~출수 후 30일까지 평균기온은 22.2℃ , 식미치가 가장 높았던 평균기온도 22.2℃ 로 같은 경향을 나타내었다. 4. 출수기~출수 후 30일까지 평균기온이 증가할수록 현미단백질 함량은 증가하였고 현미천립중이 증가할수록 현미단백질 함량은 감소하였으며, 현미천립중이 증가하면 식미치가 증가하였고 현미단백질이 증가하면 식미치가 감소하였다. 5. 식미치가 최고를 나타내는 출수기~출수 후 30일까지의 평균기온은 남평벼에서 22.1℃ , 일품벼와 주남벼에서는 22.5℃ 였지만 동진1호는 23.1℃ 로 다소 높았다. 6. 출수기~출수 후 30일까지 평균기온이 21℃ 이상인 경우 온도가 높아질수록 현미단백질 함량은 유의하게 증가하였고, 현미천립중과 현미단백질 함량과의 관계는 부의 유의성을 나타내었다. 7. 식미치는 현미천립중과 정의 유의성을 보였고 현미단백질 함량과는 부의 유의성을 나타내었다.

This paper presents a method of sonar grid map matching for topological place recognition. The proposed method provides an effective rotation invariant grid map matching method. A template grid map is firstly extracted for reliable grid map matching by filtering noisy data in local grid map. Using the template grid map, the rotation invariant grid map matching is performed by Ring Projection Transformation. The rotation invariant grid map matching selects candidate locations which are regarded as representative point for each node. Then, the topological place recognition is achieved by calculating matching probability based on the candidate location. The matching probability is acquired by using both rotation invariant grid map matching and the matching of distance and angle vectors. The proposed method can provide a successful matching even under rotation changes between grid maps. Moreover, the matching probability gives a reliable result for topological place recognition. The performance of the proposed method is verified by experimental results in a real home environment

This paper presents a method of topological modeling using only low-cost sonar sensors. The proposed method constructs a topological model by extracting sub-regions from the local grid map. The extracted sub-regions are considered as nodes in the topological model, and the corresponding edges are generated according to the connectivity between two sub-regions. A grid confidence for each occupied grid is evaluated to obtain reliable regions in the local grid map by filtering out noisy data. Moreover, a convexity measure is used to extract sub-regions automatically. Through these processes, the topological model is constructed without predefining the number of sub-regions in advance and the proposed method guarantees the convexity of extracted sub-regions. Unlike previous topological modeling methods which are appropriate to the corridor-like environment, the proposed method can give a reliable topological modeling in a home environment even under the noisy sonar data. The performance of the proposed method is verified by experimental results in a real home environment.

In order to achieve a force controller with high performance, an accurate torque servo is required. However, the precise torque servo for a double vane rotary actuator system has not been developed till now, due to many nonlinear characteristics and system parameter variations. In this paper, the torque servo structure for the double vane rotary actuator system is proposed based on the torque model. Nonlinear equations are set up using dynamics of the double vane rotary hydraulic actuator system. Then, to derive the torque model, the nonlinear equations are linearized using a taylor series expansion. Both effectiveness and performance of the design of torque servo are verified by torque servo experiments and applying the suggested torque model to an impedance controller.

자운영의 개화 후 일수, 협(꼬투리)의 탈협 유무, 파종 깊이 및 담수기간 차이에 따른 포장발아율을 조사하여 재입모율 향상을 위한 방안을 모색하고, 매년 농약 소독된 종자 수입억제와 파종 노력 경감 등 실용화 자료로 활용코자 본 연구를 수행하였다. 연구결과를 요약하면 논에서 자운영을 재배하여 개화 후 일수별로 매몰한 다음 적습상태를 유지하고 100일 후 누적 발아율을 조사한 결과, 개화 후 20일 종자는 총 9.6%, 30일 종자는 26.7%, 40일 종자는 37.3% 발아되었다. 또한 같은 종자를 90일간 담수하였다가 낙수를 하여 15일간 발아기간 을 경과 한 발아율은 개화 후 20일 종자는 발아되지 않았고, 30일 종자는 2.0%, 40일 종자는 11.2%이었다. 자운영 개화 후 40일 종자의 협(꼬투리)의 탈협 유무에 따른 발아율은 탈협 종자가 11.9%인데 비하여 비탈협 종자는 15.5%로 다소 높았다. 종자 매몰깊이에 따른 발아율은 1㎝미만 5.87%, 1～3㎝는 3.37%, 3∼5㎝는 1.66%, 5∼7㎝는 0.23%로 얕게 파종할수록 발아율이 높았다.. 담수기간에 따른 발아율은 무 담수는 30.8%, 30일 담수는 21.0%, 60일 담수는 17.6%, 90일 담수는 14.7%이었다. 따라서 자운영 지속재배를 위한 자연발아 율을 높이기 위해서는 종자가 충분히 익었을 때 물을 댄 다음 얕게 로터리를 하고 벼 생육기간 중 연속 4일 이상 논바닥을 말리지 않아야 자연발아율을 높일 수 있다

Recently, robotic automation in clinical laboratory becomes of keen interest as a fusion of bio and robotic technology. In this paper, we present a new robotic platform for clinical tests suitable for small or medium sized laboratories using mobile robots. The mobile robot called Mobile Agent is designed as transfer system of blood samples, reagents, microplates, and any instruments. Also, the developed mobile agent can perform diverse tests simultaneously based on its cooperative and distributed ability. The driving circuits for the mobile agent are embedded in the robot, and each mobile agent communicates with other agents by using Bluetooth communication. The RFID system is used to recognize patient information. Also, the magnetic hall sensor is embedded to remove and compensate the cumulated error of locomotion at the bottom of mobile agent. The proposed mobile agent can be easily used for various applications because it is designed to be compatible with general software development tools. The Mobile agents are manufactured, and feasibility of the robot and localization of the agents using magnetic hall sensor are validated by preliminary experiments.

Representing an environment as the probabilistic grids is effective to sense outlines of the environment in the mobile robot area. Outlines of an environment can be expressed factually by using the probabilistic grids especially if sonar sensors would be supposed to build an environment map. However, the difficult problem of a sonar such as a specular reflection phenomenon should be overcome to build a grid map through sonar observations. In this paper, the NRF(Neighborhood Recognition Factor) was developed for building a grid map in which the specular reflection effect is minimized. Also the reproduction rate of the gird map built by using NRF was analyzed with respect to a true map. The experiment was conducted in a home environment to verify the proposed technique.

Dynamic simulator can be a helpful tool for understanding underwater robotic system's dynamics. However, due to difficulties in modeling dynamics of vehicle/manipulator and interaction between them, dynamic simulation is not easy. This is true even when fluid dynamics are not considered during the simulation. In this paper, two schemes are introduced for dynamic simulation of underwater robotic systems. One is principle of dynamical balance, which is an easy and powerful tool for formulating dynamic equations of composite systems such as underwater vehicle- manipulator system. In the dynamic modeling, this principle gives us the closed-form of dynamic equations on matrix Lie group. The other is geometric integration algorithm, called 4-th order explicit Munthe-Kaas method. By this method, the derived differential equations can be integrated preserving geometric structure. Adopting these two schemes, dynamic simulation of underwater vehicle- manipulator system can be conducted more easily and more reliably.

The thruster is the crucial factor of an underwater vehicle system, because it is the lowest layer in the control loop of the system. In this paper, we propose an accurate and practical thrust modeling for underwater vehicles which considers the effects of ambient flow velocity and angle. In this model, the axial flow velocity of the thruster, which is non-measurable, is represented by ambient flow velocity and propeller shaft velocity. Hence, contrary to previous models, the proposed model is practical since it uses only measurable states. Next, the whole thrust map is divided into three states according to the state of ambient flow and propeller shaft velocity, and one of the borders of the states is defined as Critical Advance Ratio (CAR). This classification explains the physical phenomenon of conventional experimental thrust maps. In addition, the effect of the incoming angle of ambient flow is analyzed, and Critical Incoming Angle (CIA) is also defined to describe the thrust force states. The proposed model is evaluated by comparing experimental data with numerical model simulation data, and it accurately covers overall flow conditions within 2N force error. The comparison results show that the new model's matching performance is significantly better than conventional models'.

We present an implementation of particle filter algorithm for global localization and kidnap recovery of mobile robot. Firstly, we propose an algorithm for efficient particle initialization using sonar line features. And then, the average likelihood and entropy of normalized weights are used as a quality measure of pose estimation. Finally, we propose an active kidnap recovery by adding new particle set. New and independent particle set can be initialized by monitoring two quality measures. Added particle set can re-estimate the pose of kidnapped robot. Experimental results demonstrate the capability of our global localization and kidnap recovery algorithm.