• The KIPS Transactions:PartC
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• v.11C no.4
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• pp.429-438
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• 2004

This Paper Presents the control structure for incoming traffic from arbitrary node to Provide admission control in policy-based W network management structure using fuzzy logic control approach. The proposed control structure uses scheme for deciding network resource allocation depending on requirements predefined-policies and network states. The proposed scheme enhances policy adapting methods of existing binary methods, and can use resource of network more effectively to provide adaptive admission control, according to the unpredictable network states for predefined QoS policies. Simulation results show that the proposed controller improves the ratio of packet rejection up to 26%, because it Performs the soft adaption based on the network states instead of accept/reject action in conventional CAC(Connection Admission Controller).

• Journal of Broadcast Engineering
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• v.20 no.2
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• pp.283-299
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• 2015

In this paper, we propose new broadcasting services that combine MMT (MPEG Media Transport) standard with MPEG-DASH (Dynamic Adaptive Streaming over HTTP) standard. MMT is a next-generation multimedia transport standard that is IP-friendly and provides functionalities appropriate for hybrid broadcasting that uses broadcast physical channels and the Internet simultaneously. MPEG-DASH enables media streaming services that can be dynamically adaptive both to the network traffic conditions of wired and/or wireless Internet and the receiving entity environment. We explain the scenarios of the proposed broadcasting services and demonstrate that various hybrid broadcasting services can be easily realized through the combined usage of MMT and MPEG-DASH. By making the test bitstreams containing contents for the new services and developing the receiver back-end software that performs the function of the receiving entity for the new services on personal computers, we verified that the proposed scenarios can be realized.

• Journal of the Korean Institute of Intelligent Systems
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• v.23 no.3
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• pp.196-201
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• 2013

In this paper, we propose an asynchronous and adaptive message passing scheme based on S-MAC for handling with the problem on energy efficiency in wireless sensor networks. The proposed scheme consists of a policy that differentiate transmission errors caused by packet collision or radio interference from congestion errors caused by buffer overflow and a method that adaptively controls the size of a fragment according to the variance of traffic loads. Especially, it presents a method that highly reduce the energy consumption by keeping the size of fragment not being excessively smaller than the one that may result in rapid increment of the total transfer time. Finally, with the simulation results we show that network throughput and delay are improved by using the proposed message passing scheme.

• Journal of KIISE:Computer Systems and Theory
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• v.26 no.12
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• pp.1447-1457
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• 1999

본 논문에서는 일반적인 네트워크에서 적응력 있는(adaptive) 분산형 시스템 레벨 결함 진단을 위한 분할 기법을 제안한다. 적응력 있는 분산형 시스템 레벨 결함 진단 기법에서는 시스템의 형상이 변경될 때마다 시험 할당 알고리즘이 수행되므로 적응력 없는 결함 진단 기법에 비하여 결함 감지를 위한 시험의 갯수를 줄일 수 있다. 기존의 시험 할당 알고리즘들은 전체 시스템을 대상으로 하는 비분할(non-partitioning) 방식을 이용하였는데, 이 기법은 불필요한 과다한 메시지를 생성한다. 본 논문에서는 전체 시스템을 이중 연결 요소(biconnected component) 단위로 분할한 후, 시험 할당은 각 이중 연결 요소 내에서 수행한다. 이중 연결 요소의 관절점(articulation point)의 특성을 이용하여 각 시험 할당에 필요한 노드의 수를 줄임으로서, 비분할 기법들에 비해 초기 시험 할당에 필요한 메시지의 수를 감소시켰다. 또한 결함이 발생한 경우나 복구가 완료된 경우의 시험 재 할당은 직접 영향을 받는 이중 연결 요소내로 국지화(localize) 시켰다. 본 논문의 시스템 레벨 결함 진단 기법의 정확성을 증명하였으며, 기존 비분할 방식의 시스템 레벨 결함 진단 기법과의 성능 분석을 수행하였다.Abstract We propose an adaptive distributed system-level diagnosis using partitioning method in arbitrary network topologies. In an adaptive distributed system-level diagnosis, testing assignment algorithm is performed whenever the system configuration is changed to reduce the number of tests in the system. Existing testing assignment algorithms adopt a non-partitioning approach covering the whole system, so they incur unnecessary extra message traffic and time. In our method, the whole system is partitioned into biconnected components, and testing assignment is performed within each biconnected component. By exploiting the property of an articulation point of a biconnected component, initial testing assignment of our method performs better than non-partitioning approach by reducing the number of nodes involved in testing assignment. It also localizes the testing reassignment caused by system reconfiguration within the related biconnected components. We show that our system-level diagnosis method is correct and analyze the performance of our method compared with the previous non-partitioning ones.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.2
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• pp.495-502
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• 2013

In the mobile Ad hoc Network(MANET), improving technique for management and control of topology is recognized as an important part of the next generation network. In this paper, we proposed an efficient node life time management of ATICC(Adaptive Time Interval Clustering Control) in Ad-hoc Networks. Ad-hoc Network is a self-configuration network or wireless multi-hop network based on inference topology. This is a method of path routing management node for increasing the network life time through the periodical route alternation. The proposed ATICC algorithm is time interval control technique depended on the use of the battery energy while node management considering the attribute of node and network routing. This can reduce the network traffic of nodes consume energy cost effectively. As a result, it could be improving the network life time by using timing control method in ad-hoc networks.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.12 no.1
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• pp.28-42
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• 2013

Personal Rapid Transit(PRT) is a new unmanned transportation system using electricity. The purpose of the PRT is relieving the congestion of city traffic and connecting between inner city and airport, high-speed railroad. PRT requires to develop devices for the guarantee of safety and reliability. PRT as the mean of rail transportation must be equipped with control system for front rail sensing. Ultra Wide Band(UWB) radar system is suitable for PRT's detection because it has the advantage of low power consumption, low interference and high resolution. In this paper, an improved adaptive Constant False Alarm Rate(CFAR) algorithm is proposed and studied in various noise environments. The proposed algorithm improves performance in various noise environments compared to the Mean Level CFAR algorithms and other adaptive CFAR algorithms.

• Journal of Internet Computing and Services
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• v.21 no.2
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• pp.99-108
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• 2020

In this paper, we analyze the most suitable RA method among PAMA, DAMA, and RA classified by the multiple access method of satellite communication in the rapidly changing traffic environment according to the emergency and tactical situation. It suggests an alternative to improve the limit of output degradation. Based on the CRDSA protocol selected as the standard of DVB-RCS2 among the current satellite communication methods, CRDSA2R (Contention) maintains an optimal RA channel environment by checking the limitations in an environment where packet volume is rapidly increasing and observing channel load and channel conditions. We propose a Resolution Diversity Slotted ALOHA with Adaptive Random Access.

• Current Optics and Photonics
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• v.1 no.3
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• pp.207-213
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• 2017

The Adaptive Front-lighting System (AFS) is a part of the active safety system, providing optimized vision to the driver during night time and other poor-sight conditions of the road by automatic adaptation of lighting to environmental and traffic conditions. Basically, an AFS provides four different modes of the passing beam as designated in an United Nations Economic Commission for Europe regulation (ECE324-R123): neutral state or country light (Class C), urban light (Class V), highway light (Class E), and adverse weather light (Class W). In this paper, we first present an optics design for an AFS system capable of producing the Class C/V/E/W patterns requiring only on/off modulation of multi-array LEDs with no need for any additional mechanical components. The AFS optics consists of two separated modules, cutoff and spread; the cutoff module lights a narrow central area with high luminous intensity, satisfying the cutoff regulation, and the spread module forms a wide spread beam of low luminous intensity. Each module consists of two major parts; the first converts a discretely positioned LED array into a full-filled area emitting light source plane, and the second projects the light source plane to a 25 m away target plane. With the combination of these two optics modules, the four beam patterns are formed by simple on/off modulation of multi-array LEDs. Then we report the development of a prototype that was demonstrated to provide the four beam patterns.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.8
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• pp.1901-1907
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• 2015

Today's smartphones and user devices are equipped with multiple radio interfaces increasingly. Aggregating theses multiple radio interfaces and using them concurrently will increase a user's communication speed immediately, but at the expense of increased power consumption. In this paper, we develop a mathematical performance model of an adaptive radio activation scheme by which a radio interface is activated only when needed for performance increase and deactivated otherwise. The developed model shows that the adaptive scheme reduces delay significantly and almost halves power consumption below a certain level of traffic input.

• Journal of KIISE:Computer Systems and Theory
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• v.26 no.9
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• pp.1073-1082
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• 1999

본 논문에서는 시스템 내의 프로세서들을 효과적으로 사용하기 위한 적응적 프로세서 할당 정책을 제안한다. 프로그램의 병렬성을 향상시키기 위하여 일반적으로 병렬 처리에 사용될 프로세서 개수를 증가시킨다. 그러나 증가된 프로세서들은 그레인 크기에 변화를 일으키며 이는 캐쉬 성능에 영향을 미친다. 특히 대역이 제한된 공유 버스를 사용하는 시스템에서는 프로세서 개수의 증가는 공유 버스에 대한 접근 경쟁을 크게 증가하므로 버스에서 대기하는 시간이 프로세서 증가에 의한 계산 능력 이득을 상쇄시키는 주요한 원인이 되고 있다. 본 논문에서 제안한 적응적 프로세서 할당 정책은 프로그램이 수행되는 도중에 임의의 기간동안 공유버스에 대기중인 프로세서 분포에 관한 정보를 얻는다. 그리고 이 정보를 바탕으로 프로세서 개수를 변경하는 방법이다. 모의 시험에서 적응적 프로세서 할당 정책은 프로그램들의 버스 트래픽 특성에 따른 최적의 적합한 프로세서 개수를 발견함을 보인다. 그리고 적응적 프로세서 할당 정책은 고정된 프로세서 개수를 사용한 가장 좋은 성능보다는 다소 떨어진 성능을 나타내었으나 시스템의 프로세서 활용성을 높여 효과적 시스템 사용에 기여함을 보인다. Abstract In this paper, the adaptive processor allocation policy is suggested to make effective use of processors in system. To enhance the parallelism, the number of processors used in the parallel computing may be increased. However, increasing the number of processors affects the grain size of the parallel program. Therefore, it affects the cache performance. In particular, when the shared bus is employed, since increasing the number of processors can result in a significant amount of contention to achieve the shared-bus, the increased computing power is offset by the bus waiting time due to these contentions. The adaptive processor allocation policy acquires the information about the distribution of waiting processors on shared bus for any execution period of programs. And it changes the number of processors working in parallel processing during the program's run. Our simulation results show that the adaptive processor allocation policy finds the optimum feasible number of processors based on the bus traffic characteristic of programs. Thus, it contributes to effective system utilization, even though it performs slightly less efficiently than using a fixed number of processors with the best performance.