• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.5 s.122
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• pp.415-426
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• 2007

In a link motion punch press, numerous links are interconnected and each link executes a constrained motion at high speed. As a consequence, dynamic unbalance force and moment are transmitted to the main frame of the press, which results in unwanted vibration. This degrades productivity and precise stamping work of the press. This paper presents an effective method for reducing dynamic unbalance in a link motion punch press based upon kinematic and dynamic analyses. Firstly, the kinematic analysis is carried out in order to understand the fundamental characteristics of the link motion mechanism. Then design variable approach is presented in order to automate the model setup for the mechanism whenever design changes are necessary. To obtain the inertia properties of the links such as mass, mass moment of inertia, and the center of mass, 3-dimensional CAD software was utilized. Dynamic simulations were carried out for various combinations of design changes on some links having significant influences on kinematic and dynamic behavior of the mechanism.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.498-502
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• 2004

In a link-motion mechanism, numerous links are interconnected and each link executes a constrained motion at a high speed. Due to the complicated constrained motions of the constituent links, dynamic unbalance forces and moments are generated and transmitted to the main frame. Therefore unwanted vibration is produced. This degrades productivity and precise work. Based on constrained multi-body dynamics, the kinematic analysis is carried out to enable design changes to be made. This will provide the fundamental information for significantly reducing dynamic unbalance forces and moments which are transmitted to the main frame. In this work, a link-motion punch press is selected as an example of a link-motion mechanism. To calculate the mass and inertia properties of every link comprising a link-motion punch press, 3-dimensional CAD software is utilized. The main issue in this work is to eliminate the first-order unbalance force and moment in a link-motion punch press. The mass, moment of inertia link length, location of the mass center in each link have a great impact on the degree of dynamic balancing which can be achieved maximally. Achieving good dynamic balancing in a link motion punch press is quite essential fur reliable operation at high speed.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.8
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• pp.1756-1763
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• 2011

This paper was researched the straight cruise of fish robot according to biological mimic, and it was compared the proposed method which was considered up to 7th order components in fourier series of Liu's tail motion function with the approximate method which was used general sine function by simulation. If fish robot has a large number of links and if the length of tail link is long. The end rotary joint trajectory of tail motion function generally is different from sine function. Therefore The approximate method which expresses tail motion trajectories as fundamental component in fourier series has a problem. Through the computer simulation, the proposed method showed 10% excellent propulsion and velocity than the conventional method.

• Journal of the Korea Computer Graphics Society
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• v.14 no.2
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• pp.9-17
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• 2008

We propose a method to determine camera parameters for character motion, which confiders the motion by itself. The basic idea is to approximately compute the area swept by the motion of the character's links that are orthogonally projected onto the image plane, which we call "Motion Area". Using the motion area, we can determine good fixed camera parameters and camera paths for a given character motion in the off-line or real-time camera control. In our experimental results, we demonstrate that our camera path generation algorithms can compute a smooth moving camera path while the camera effectively displays the dynamic features of character motion. Our methods can be easily used in combination with the method for generating occlusion-free camera paths. We expect that our methods can also be utilized by the general camera planning method as one of heuristics for measuring the visual quality of the scenes that include dynamically moving characters.

• Proceedings of the Korean Information Science Society Conference
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• 2000.04b
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• pp.619-621
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• 2000

최근 인터넷 기술의 발달로 인한 실시간 인터넷 동영상 서비스 등 인터넷을 이용한 방송사업이 활성화되어지고 이에 부가적으로 애니메이션이 감각적 서비스를 지원하고 있는 실정이나 고가의 모션캡쳐 시스템을 통한 캡쳐된 좌표를 적절한 보정을 한 후에 캐릭터를 움직이는 방법으로 이루어지고 있다. 이러한 모션캡쳐 시스템을 통한다면 시스템 및 장비 자체가 고가이고 또한 실시간으로 처리하기 위하여는 좌표값 보정 등이 필요하지만 본 논문에서 제안하는 좌표 추출 및 추적 기법을 이용하여 저가의 가정용 멀티미디어 오버레이 캡쳐보드와 CCD 카메라를 통하여 영상을 캡쳐하고 캡쳐된 영상좌표와 실험용 GDI object를 링크시켜 실시간으로 사람의 입술의 움직임 모양대로 애니메이션이 립싱크되어서 움직여지는 것을 볼 수 있으며, 더 나아가서 외화의 우리말 더빙시 영상처리를 통한 정교한 화면 더빙 및 가상 캐릭터를 이용한 사이버 미팅가지 가능할 것이다.

• Proceedings of the Korea Information Processing Society Conference
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• 2011.04a
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• pp.505-508
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• 2011

유비쿼터스 환경에서 객체들과의 데이터 통신은 매우 중요하다. 특히 서버와의 교신 없이 객체들로부터 직접 충분한 정보를 확보해야 할 때에 이는 더욱 중요하다. 온라인 기반 네트워크를 이용하는 경우, 대량의 데이터를 고속으로 전송할 수 있다는 장점이 있으나, 해당 통신을 지원할 수 있는 모듈이 각각의 객체에 설치되어 있어야 하고 온라인 상태를 유지하고 있어야 한다는 부담이 있다. 태그 인터페이스와 카메라 비전 기술을 주로 사용하는 오프라인 기반 네트워크를 이용하는 경우, 특별한 통신모듈 없이도 물리적 객체와 디지털 객체 사이에서 효과적인 데이터 전송이 가능하다는 장점이 있으나, 온라인 기반 네트워크를 이용하는 경우에 비해 극히 소량의 데이터만을 전송한다는 단점이 있다. 이 경우 전송하는 데이터 량을 늘리기 위해 우회적으로, 온라인 기반 네트워크로의 링크 정보를 전달하는 방법을 사용하고 있으나, 결국 온라인 기반 네트워크를 이용하는 경우에 발생하는 한계를 지니게 된다. 본 논문에서는 온라인 기반 네트워크를 이용할 수 없는 제한된 오프라인 환경에서, 디스플레이와 카메라만을 이용하여 기존의 오프라인 태그 인터페이스 특히 이미지 코드에서보다 자체적으로 서버와의 교신 없이 좀 더 많은 데이터를 전송하기 위한 방법으로 모션 코드를 제시한다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.3
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• pp.580-585
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• 2009

Real Time Locating Systems (RTLS) are used to track and identify the location of objects in real time using simple, inexpensive tags attached to or embedded in objects and readers that receive the wireless signals from these tags to determine their locations. A tag is powered an internal source such as a battery. The blink frequency of a tag affects the energy efficiency and the locating accuracy of RTLS. The mobility of a tag also affects the locating accuracy. In this paper, we introduce a RTLS tag design which improves the locating accuracy and the power efficiency. We propose an adaptive transmission-rate control algorithm using a motion sensor. By analyzing the signal pattern of the motion sensor, we can build a model to estimate the speed of the motion. Using this model, our algorithm can achieve better locating accuracy and lower power consumption than those of the conventional method. In our experiments, the number of transmission reduced as 40%, keeping similar locating accuracy.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1813-1814
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• 2008

본 논문에서는 생물학적 운동 메카니즘을 유사하게 구현하기 위해 신경 진동자를 이용한 로봇 팔 제어 시스템을 제안한다. 인간 및 동물의 주기적인 자율 운동을 관장하는 Central Pattern Generator (CPG)를 수학적으로 모델링한 신경 진동자는 그 중요 특성의 하나인 entrainment 효과를 보여준다. 일반적으로 우리는 이 기능을 이용하여 미지의 외부 환경 변화와 같은 외란에 적절히 상호 작용할 수 있는 운동을 생성해 낼 수 있다. 이러한 결과를 보이기 위해, 각 관절에 가상의 신경 진동자 모델을 결합하였고 외부 환경의 변화나 외란의 감지를 위한 F/T센서를 팔의 말단에 부착하여 시스템을 구현하였다. 신경 진동자 모델을 결합한 2축 링크 로봇 팔 시스템(real time)은 주어진 목적운동을 (원 운동) 수행함과 동시에 미지의 외부 환경의 변화(임의의 벽)를 인지하여 적절한 모션을 생성하는 지를 살펴본다.

• Spatial Information Research
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• v.18 no.4
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• pp.89-98
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• 2010

Recently, the target of navigation system is moving from the cars to pedestrians. Many researches are in progress regarding pedestrian navigation, However, in most cases, the path-finding is based on the existing node/link network model. which is widely used for the car navigation, and thus showing its limitation. The reasons arc that a) unlike with a car, the paths that pedestrians take arc not limited to the roads, b) pedestrians an~ not restricted in rotation or direction, and c) they can freely move within the walkable space. No alternatives have been offered yet, especially for openspaces such as a park or square. Therefore, in this research, we suggested appropriate methods to create paths that can be used in pedestrian navigation service, by using motion-planning technology, which is used in the field of robotics for planning the motion of an object, and conducted tests for their applicability.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.114-117
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• 2000

We developed a motion capture system to get angle data of human joints in walking mode. The data are used to coordinate the biped-walking robot developed in our laboratory. A pair of motion capture system is composed of three links with the ankle, knee, and pelvis joints. The system has six axes attached with potentiometers. We used an A/D converter was used to get digital data from joint angles. We filterd the data using the Butterworth 4th order digital filter, and simulated walking motion based on the data using the Matlab.