• Investigative Magnetic Resonance Imaging
• /
• 제25권1호
• /
• pp.10-22
• /
• 2021

Purpose: To overcome the difficulty in building a large data set with a high-quality in medical imaging, a concept of 'blended-transfer learning' (BTL) using a combination of both source data and target data is proposed for the target task. Materials and Methods: Source and target tasks were defined as training of the source and target networks to reconstruct cardiac CINE images from undersampled data, respectively. In transfer learning (TL), the entire neural network (NN) or some parts of the NN after conducting a source task using an open data set was adopted in the target network as the initial network to improve the learning speed and the performance of the target task. Using BTL, an NN effectively learned the target data while preserving knowledge from the source data to the maximum extent possible. The ratio of the source data to the target data was reduced stepwise from 1 in the initial stage to 0 in the final stage. Results: NN that performed BTL showed an improved performance compared to those that performed TL or standalone learning (SL). Generalization of NN was also better achieved. The learning curve was evaluated using normalized mean square error (NMSE) of reconstructed images for both target data and source data. BTL reduced the learning time by 1.25 to 100 times and provided better image quality. Its NMSE was 3% to 8% lower than with SL. Conclusion: The NN that performed the proposed BTL showed the best performance in terms of learning speed and learning curve. It also showed the highest reconstructed-image quality with the lowest NMSE for the test data set. Thus, BTL is an effective way of learning for NNs in the medical-imaging domain where both quality and quantity of data are always limited.

• 제어로봇시스템학회논문지
• /
• 제20권6호
• /
• pp.593-598
• /
• 2014

Hand gesture recognition based on vision is a challenging task in human-robot interaction. The sign language of finger spelling alphabets has been tested as a kind of hand gesture. In this paper, we test hand gesture recognition by detecting the contour shape and orientation of hand with visual image. The method has three stages, the first stage of finding hand component separated from the background image, the second stage of extracting the contour feature over the hand component and the last stage of comparing the feature with the reference features in the database. Here, finger spelling alphabets are used to verify the performance of our system and our method shows good performance to discriminate finger alphabets.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제18권5호
• /
• pp.1238-1259
• /
• 2024

Previous studies on joint optimization of computation offloading and service caching policies in Mobile Edge Computing (MEC) have often neglected the impact of dependency-aware subtasks, edge server resource constraints, and multiple users on policy formulation. To remedy this deficiency, this paper proposes a many-objective joint optimization dependency-aware task offloading and service caching model (MaJDTOSC). MaJDTOSC considers the impact of dependencies between subtasks on the joint optimization problem of task offloading and service caching in multi-user, resource-constrained MEC scenarios, and takes the task completion time, energy consumption, subtask hit rate, load variability, and storage resource utilization as optimization objectives. Meanwhile, in order to better solve MaJDTOSC, a many-objective evolutionary algorithm TSMSNSGAIII based on a three-stage mating selection strategy is proposed. Simulation results show that TSMSNSGAIII exhibits an excellent and stable performance in solving MaJDTOSC with different number of users setting and can converge faster. Therefore, it is believed that TSMSNSGAIII can provide appropriate sub-task offloading and service caching strategies in multi-user and resource-constrained MEC scenarios, which can greatly improve the system offloading efficiency and enhance the user experience.

• International Journal of Control, Automation, and Systems
• /
• 제1권1호
• /
• pp.1-10
• /
• 2003

This paper presents a high-precision magnetically levitated (maglev) stage to meet demanding motion specifications in the next-generation precision manufacturing and nanotechnology. Characterization of dynamic behaviors of such a motion stage is a crucial task. In this paper, we address the issues related to the stochastic modeling of the stage including transfer function identification, and noise/disturbance analysis and prediction. Provided are test results on precision dynamics, such as fine settling, effect of optical table oscillation, and position ripple. To deal with the dynamic coupling in the platen, we designed and implemented a multivariable linear quadratic regulator, and performed time-optimal control. We demonstrated how the performance of the current maglev stage can be improved with these analyses and experimental results. The maglev stage operates with positioning noise of 5 nm rms in $\chi$ and y, acceleration capabilities in excess of 2g(20 $m/s^2$), and closed-loop crossover frequency of 100 Hz.

• 인지과학
• /
• 제23권3호
• /
• pp.389-408
• /
• 2012

감각적 경험을 언어로 기술하면 그 경험에 관한 감각적 기억이 저하되는데, 이러한 현상을 일컬어 언어 장막(verbal overshadowing) 효과라고 한다. Schooler(2002)[1]는 언어화로 인해 정보처리 방식이 전역적 처리에서 국지적 처리로 전환되기 때문에 언어 장막이 발생한다고 제안하였다. 본 연구에서는 이러한 정보처리의 전환이 실제로 일어나는가를 검증하고자 얼굴 자극에 대한 기억을 요구하고 이를 토대로 언어적 묘사를 한 직후에 전역 처리와 국지 처리를 비교할 수 있는 Navon 과제를 실시하였다. 얼굴 재인 과제에서는 참가자들에게 외워야 하는 얼굴을 제시한 후 그 얼굴에 대한 언어화를 요구하였으며, 얼굴 재인 과제를 수행한 직후에 Navon 과제를 수행하도록 하였다. 그 결과, 얼굴 재인 과제에서는 언어화를 한 묘사 집단에서 언어화를 하지 않은 통제 집단보다 낮은 재인률을 보이는 언어 장막 효과가 나타났다. Navon 과제에서는 통제 집단이 전역수준의 정보가 국지 수준의 정보보다 우세하게 처리되는 전역 선행성(global precedence)을 보인 반면에, 묘사 집단은 전역 수준의 정보보다 국지 수준의 정보를 더 우세하게 처리하는 국지 선행성을 보였다. 이는 얼굴을 언어화함으로써 정보처리의 방식이 전역적인 방향에서 국지적인 방향으로 전환되고, 그 결과로서 얼굴에 대한 재인이 손상된 것임을 시사한다.

• 감성과학
• /
• 제12권3호
• /
• pp.279-288
• /
• 2009

이 연구의 목적은 과제수행에 대하여 주관적 인지부하 요인과 GSR의 각성수준이 어떤 관계를 형성하고 있는지를 검증하는 것이다. 이를 위하여 인지부하 설문지(신체적 노력, 정신적 노력, 지각된 과제난이도, 자기평가, 자료설계의 용이성), 사전-사후검사, GSR에 의한 각성수준을 측정하였다. 사전검사는 학습자의 사전지식 수준을 의미하며, 사후검사는 과제수행의 결과를 의미한다. 이 연구의 분석방법은 사후검사의 결과를 종속변수로 하는 회귀분석이었다. 첫째, 자기보고의 인지부하 요인이 사후검사에 미치는 영향을 분석한 결과에 따르면, 사전검사, 신체적 노력, 지각된 과제난이도가 사후검사에 유의미한 영향을 미치고 있었다. 신체적 노력은 정적관련성을 보이고 있었으나 지각된 과제난이도는 부적관련성을 보이고 있었다. 이 결과는 사전검사의 점수가 높은 사람은 상대적으로 과제난이도를 낮게 지각하는 경향이 있으며 과제해결을 위하여 신중히 노력함으로써 사후검사의 결과가 올라간다는 것을 보여주는 것이다. 둘째, 각성수준에 대한 연구결과에서는 평가단계에서 측정된 각성수준이 사후검사의 점수를 유의미하게 예측하고 있는 것으로 나타났다. 평가단계의 GSR은 과제수행(사후검사)과 부적 관계를 형성하고 있었다. 즉, 평가단계에서 적절한 이완수준을 유지하고 있을 때 사후검사의 결과가 증진된다는 것을 보여주는 것이다.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2004년도 추계학술대회 논문집
• /
• pp.894-897
• /
• 2004

In this paper, we address a position control scheme for a stage system, which is levitated and driven by electric magnetic actuators. This consists of a levitating object (called platen) with 4 permanent magnetic linear synchronous motors in parallel. Each motor generates vertical force for suspension against gravity and propulsion force horizontally as well. This stage can generate six degrees of freedom motion by the vertical and horizontal forces. Dynamic equations of the stage system are derived based on Newton-Euler method and its special Jacobian matrix describing a relation between the Joint velocity and platen velocity is done. There are proposed two control schemes for positioning, which are Cartesian space controller and Joint space controller. The control performance of the Cartesian space controller is better than the Joint space controller in task space trajectory while the Joint space controller is simpler than the Cartesian space controller in controller realization.

• 한국정밀공학회지
• /
• 제22권7호
• /
• pp.102-111
• /
• 2005

In this paper, we address a position control for a parallel stage, which is levitated and driven by electric magnetic force. This consists of a levitating object (called platen) with 4 permanent magnetic linear synchronous motors in parallel. Each motor generates vertical force for suspension against gravity and propulsion force horizontally as well. This stage can generate six degrees of freedom motion by the vertical and horizontal force. A dynamic equation of the stage system is derived based on Newton-Euler method and it's special Jacobian matrix describing a relation between the limited velocity and Cartesian velocity is done. There are proposed two control methods for positioning which are Cartesian space controller and Actuator space controller. The control performance of the Cartesian space controller is better than the Actuator space controller in task space trajectory while the Actuator space controller is simpler than the Cartesian space controller in controller realization.

• 대한인간공학회지
• /
• 제27권2호
• /
• pp.49-57
• /
• 2008

This study aims to investigate the effect of handle angles of pliers on performance, wrist motion and subjective rating of satisfaction. An experiment was conducted, in which handle angle of pliers was used as independent variable and 14 subjects participated. Based on the literature survey, plier handles angled at 0$^{\circ}$, 10$^{\circ}$, 20$^{\circ}$, 30$^{\circ}$ and 40$^{\circ}$ were adopted in the experiment. The subjects were instructed to bend iron plates by 90$^{\circ}$ and to cut wires as soon as possible. The results revealed that 1) handle angles of pliers have significant effect on wrist motion and satisfaction(p<0.0001); 2) handle angles of pliers did not affect performance of completing tasks irrespective of types of tasks done in the study; 3) in the initial stage of windup, plier with handle angled at 20$^{\circ}$ produced the least wrist motion of deviation in task of bending iron plates, while plier with handle angled at 40$^{\circ}$ did in task of cutting wires; 4) degree of satisfaction was maximized when handle of pliers was bent by 20$^{\circ}$ in both tasks. On the basis of the results, it is recommended that handle of pliers be bent by 20-30$^{\circ}$ for reducing musculoskeletal disorders related to pliers.

• 한국군사과학기술학회지
• /
• 제11권4호
• /
• pp.59-67
• /
• 2008

In the next near future, the human would like to use the small unmanned ground vehicle(SUGV) on the diverse fields. Specially the world of today is tried to apply with operating the task on very difficult working environments such as some dangerous or unreachable area. To work this task, this vehicle should be guaranteed with the high level of reliability, safety, and performance. In this paper, we propose to focus on not only the functional requirements, but also the non-functional requirements based on software architecture at the design stage for developing the embedded system. Through focusing on the non-functional requirements on this software architecture, we can obtain the design goal of the target system and also show the enhancement of reliability, safety and performance with 'Vtune' performance analysis tool.