• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.1109-1114
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• 2003

In this paper, task control architecture is proposed for a mobile robot with behaviors based on cognition theory to endow the robot intelligence. In the task control architecture, task manager is introduced especially for the management of computational resource. The management is based on classical RMS (Rate Monotonic Strategy), but with online rate modulation strategy. The rate modulation is performed using the value variances of behavior execution for the task. Because the values are based on natively uncertain sensor information, they are modeled using PDF (probability Density Function). As a rate modulation process, the range of the rate modulation is defined firstly by real-time constraints of RMS and discrete control stability of behaviors. With the allowable range, rate modulations are performed considering harmonic bases to maintain utilization bound without decrease. To evaluate the efficiency of the proposed rate modulation strategy, a simulation test is performed to compare the efficiency between the control architecture with the proposed strategy and previous one. A performance index with the formalization of propensity of resource allocation is proposed and utilized for the simulation test. To evaluate the appropriateness of the performance index, the performance index is compared with practical one through a practical simulation test.

• Proceedings of the Korea Information Processing Society Conference
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• 2000.04a
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• pp.414-418
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• 2000

CDMA 단말기의 DBMS는 단말기를 운영하는데 필요한 시스템 및 가입자의 정보를 관리하기 위한 소프트웨어로서 서비스 제공에 있어서의 실시간성과 높은 신뢰성, 그리고 효과적인 Fault Tolerance 및 고장으로부터의 신속한 회복 기능을 제공하여야 한다. 이를 위해 이동통신용 단말기에서는 실시간 운영체제를 기반으로 하는 Non-Volatile 메모리인 EEPROM에 저장하여 관리하는 방법을 채택하고 있다. CDMA 단말기에서 사용하는 MSM(Mobile Station Modem)과 단말기 소프트웨어는 운영체제 환경하에서 동작하는데 기능 중심으로 여러 개의 Task들을 설계하고 이들이 필요한 기능들을 수행하도록 하고 있다. 본 논문에서는 CDMA 단말기 소프트웨어의 여러 Task 중에서 EEPROM과 관련하여 데이터베이스 시스템 역할을 수행하는 NVDB Task(Non-Volatile Database Task)의 기능과 구조를 다룬다.

• Proceedings of the Korea Information Processing Society Conference
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• 2000.04a
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• pp.465-469
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• 2000

CDMA 단말기의 DBMS는 단말기를 운영하는데 필요한 시스템 및 가입자의 정보를 관리하기 위한 소프트웨어로서 서비스 제공에 있어서의 실시간성과 높은 신뢰성, 그리고 효과적인 Fault Tolerance 및 고장으로부터의 신속한 회복 기능을 제공하여야 한다. 이를 위해 이동통신용 단말기에서는 실시간 운영체제를 기반으로 하는 Non-Volatile 메모리인 EEPROM에 저장하여 관리하는 방법을 채택하고 있다. CDMA 단말기에서 사용하는 MSM(Mobile Station Modem)과 단말기 소프트웨어는 운영체제 환경하에서 동작하는데 기능 중심으로 여러 개의 Task들을 설계하고 이들이 필요한 기능들을 수행하도록 하고 있다. 본 논문에서는 CDMA 단말기 소프트웨어의 여러 Task 중에서 EEPROM과 관련하여 데이터베이스 시스템 역할을 수행하는 NVDB Task(Non-Volatile Database Task)의 기능과 구조를 다룬다.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.720-723
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• 1997

This paper presents a cooperative control method for multiple robots. This method is based on local sensors. The proposed method integrates all information obtained by local perception through a set of sensors and generates commands without logical conflicts in designing control logic. To control multiple robots effectively, a global control strategy is proposed. These methods are constructed by using AND/OR logic and transition firing sequences in Petri nets. To evaluate these methods, the object-searching task is introduced. This task is to search an object like a box by two robots and consists of two sub-tasks, i.e., a wall tracking task and a robot tracking task. Simulation results for the object-searching task and the wall tracking task are presented to show the effectiveness of the method.

• Journal of the Ergonomics Society of Korea
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• v.24 no.1
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• pp.19-26
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• 2005

Mobile internet access using such devices as PDAs and cellular phones becomes popular as mobile technologies grow. However, the characteristics of small screen devices such as small screen size and pen-based input cause many usability problems. In this study, a human factors experiment was conducted to identify the factors affecting the usability of information search on a PDA. Factors manipulated in the experiment included use of wheel equipment, scroll dimension, and screen orientation. Task completion time, error frequency, and subjective satisfaction level were measured. In addition, various users' behavioral patterns such as scanning routes and mainly used scrolling methods were analyzed. Scroll dimension has a significant effect on task completion time. Scroll equipment and screen orientation affect subjective satisfaction level. The results could be applied to designing information structure of web sites for mobile use by providing vertical scroll and using external scroll equipments.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.1841-1846
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• 2003

The mobile platform-manipulator discussed in this paper is a three link manipulator mounted on a mobile platform. This mobile manipulator is used for welding operation and it is able to operate in a narrow space. The task of the torch, which is mounted at the end effector of the manipulator, is to track along the seam line and the task of the mobile platform is to move the origin point of the manipulator in order to go away from the singularity of the manipulator’s configuration. In this paper, the path planning for the motion of two subsystems (i.e., the manipulator and the mobile platform) was presented by the decentralized control method. Two controllers for the mobile platform and the manipulator were designed, and the relationship between the independent controllers is its state information. The simulation results are also presented to demonstrate the effectiveness of the control method.

• Proceedings of the KIEE Conference
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• 2003.07d
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• pp.2362-2364
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• 2003

In this paper, behaviors performing controls of a mobile robots are designed based on the concept of closed-loop controls. A control architecture, in which the behaviors coordinate concurrently with one others to achieve a task is also proposed. In the control architecture, task manager allocates valid resources and configures the weight of the behavior outputs to achieve the task. For practical implementation, a rate modulation strategy based on RMS(Rate Modulation Strategy) is proposed for efficient resource allocations. The rate modulation strategy is performed with considering control stability. The efficiency of the proposed rate modulation strategy is validated through simulation tests.

• Proceedings of the KIEE Conference
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• 2000.07d
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• pp.2846-2848
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• 2000

In this paper we propose a path planning method for an autonomous mobile robot based on genetic algorithms(GAs). There have been a number of methods proposed for the path planning of a mobile robot. However, few algorithms have been developed for an on-line path planning of a mobile robot with the uncertain information of a task environment. Therefore, we propose a path planning algorithms based on GAs that has ability of creating path planning without the perfect information of a task environment and an ability of planning the efficient path by on-line process. Then we show a possibility of the practical use with the results of simulations and experiments.

• Journal of KIISE
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• v.42 no.6
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• pp.707-712
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• 2015

Mobile cloud computing is a technology that uses cloud services to overcome resource constrains of a mobile device, and it applies the computation offloading scheme to transfer a portion of a task which should be executed from a mobile device to the cloud. If the communication cost of the computation offloading is less than the computation cost of a mobile device, the mobile device commits a certain task to the cloud. The previous cost analysis models, which were used for separating functions running on a mobile device and functions transferring to the cloud, only considered the amount of data transfer and response time as the offloading cost. In this paper, we proposed a new task partitioning scheme that considers the frequency of function calls and data synchronization, during the cost estimation of the computation offloading. We also verified the energy efficiency of the proposed scheme by using experimental results.

• Proceedings of the Korea Information Processing Society Conference
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• 2009.04a
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• pp.1218-1221
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• 2009

최근 Internet Engineering Task Force에서 표준화가 된 Proxy Mobile IPv6는 기존의 이동성 보장 프로토콜인 Mobile IPv6가 가지는 많은 문제점을 보완했다. 하지만, Proxy Mobile IPv6에서 같은 Local Mobility Anchor 내에 있고, 다른 Mobile Access Gateway에 있는 Mobile Node 사이의 패킷 전송에 있어서 발생하는 삼각 라우팅 문제는 여전히 존재한다. 이 문제점을 해결하기 위해 최근 Liebsch의 드래프트와 A.Dutta의 드래프트에서 제안된 두 가지의 Route Optimization 기법의 동작 과정을 알아보고, 상호 데이터 전송 상황에서 더 나은 성능을 제공하는 새로운 Route Optimization 기법을 제안한다. 제안한 Route Optimization 기법은 Corresponding Information을 이용하여 Mobile Access Gateway 간 Corresponding Binding을 완료하여, Route Optimization을 설정한다. 제안한 Correspondent Information을 이용한 Route Optimization 기법은 기존의 기법보다 상호 데이터 전송 상황에서 Route Optimization에 필요한 메시지 수가 적기 때문에 시그널링 비용이 감소하였다.