• Journal of the Institute of Electronics Engineers of Korea SC
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• v.37 no.3
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• pp.55-62
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• 2000

This paper presents an analysis of the chaotic behavior in the discrete-time voltage mode chaotic generator fabricated using 0.8${\mu}{\textrm}{m}$ single poly CMOS technology. An approximated empirical equation is extracted from the measurement data of a nonlinear function block. Then the bifurcation diagram is simulated according to input variables and Lyapunov exponent λ which represent a dependence on an initial value is calculated. We show the interrelations among time waveforms, state transition, and power spectra for the state condition of chaotic circuit, such as equilibrium, periodic, and chaotic state. And results of experiments in the chaotic circuit with the $\pm$2.5V power supply and sampling clock frequency of 10KHz are shown and compared with the simulated results.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.05a
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• pp.221-224
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• 2008

Anghelescu et al. proposed a block cryptosystem based on 8-cell hybrid additive cellular automata with cycle length 8 using state transition rules 51, 60 (or 102). All states must divided into the same cycles in the diagram of the cellular automata. But there exist cellular automata which don't satisfy this condition in Anghelescu et al.'s cryptosystem. In this paper we analyze hybrid additive cellular automata and propose an improved method.

• The KIPS Transactions:PartC
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• v.13C no.2 s.105
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• pp.177-184
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• 2006

A handover is a technology that enables data transmission and receipt seamlessly while a mobile station moves from the current base station to another base station. The handover is basically classified into two types; a horizontal handover which changes a radio link only without changing a network link, and a vertical handover which changes both in heterogeneous networks. In this paper, we propose a vertical handover protocol in a dual base station which supports both of W-CDMA and WiBro networks based on SDR (Software Defined Radio), verify the rightness using a state transition diagram and a Petri-net, and evaluate the performance of the proposed protocol using NS-2 simulator.

• Journal of the Korea Society for Simulation
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• v.3 no.1
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• pp.151-165
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• 1994

Broadband network based on the Asynchronous Transfer Mode(ATM) concept are becoming the target technology for the emerging Broadband Integrated Services Digital Network(B-ISDN). Since B-ISDN is very complex and requites a great amount of investment, optimum design and performance analysis of such systems are very important. Simulation can be widely used to analyze and examine the broadband network behavior. However, for the complicated system like broadband networks it is extremely difficult and time-consuming to develop a complete model for simulation. In this paper, an object-oriented modeling approach for the broadband network simulation is presented for the effective and efficient modeling. Object-oriented approaches can provide a good structuring capability for complicated simulation models and facilitate the development of reusable and extensible simulation models. We have developed an object-oriented model which consists of object model and behavior model. In the object mode., the components of the broadband network and both constant bit rate(CBR) and variable bit rate(VBR) traffic types of call level, burst level, and cell level are modeled as object classes. In the behavior model, the dynamic features for each object class are represented using the state transition diagram. It has been shown by illustration that objectoriented modeling is an effective tool for modeling the complicated B-ISDN.

• Journal of KIISE:Computer Systems and Theory
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• v.28 no.3
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• pp.173-180
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• 2001

고가용도 클러스터 시스템에서 가동되는 인터넷 기반 소프트웨어의 복잡도가 증가됨에 따라 소프트웨어의 설계, 구현, 또는 그 밖의 여러 가지 원인과 관련된 결함으로 인하여 시스템 서비스의 오동작 또는 수행 중단으로 이어지는 사례가 늘어나고 있다. 특히 대량 트랜잭션을 처리하는 인터넷 기반 컴퓨팅 소프트웨어는 빈번한 통신 두절과 데이터 유실로 인하여, 이들이 탑재된 클러스터 시스템의 결함 발생이 더욱 심각할 가능성이 높다. 본 연구는 소프트웨어 재활 결함 허용 기법을 활용하여, 별도의 추가되는 하드웨어 없이도 가용도를 개선할 수 있다는 '소프트웨서 재활 기법을 적용한 다중계 시스템 가용도 분석'에 관한 논문에서 언급된 문제점들에 대한 해결 방안을 제시하였으며, 구체적으로는 1) 주서버의 고장 발생시 여분서버로의 작업전이(switchover) 상태를 클러스터 시스템 모델링에 포함시켰으며, 2) 작업전이 상태와 재활(rejuvenation) 상태에서 머무는 시간을 지수분포 대신에 k-stage Erlangian 분포를 사용하여 확정시간(deterministic time)을 표현할 수 있도록 하였다. 즉 본 논문에서는 고가용도 cold standby 클러스터 시스템의 운영 상태에 대한 상태전이도(state transition diagram)에서, 임의의 상태에서 머무는 시간분포가 memoryless 성질을 만족하지 않아도 되는 semi-Markov 프로세스 문제를 해결하였다.

• The Transactions of the Korea Information Processing Society
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• v.4 no.10
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• pp.2453-2460
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• 1997

Among the method of developing software there are many object-oriented analysis(OOA) techniques, and the new ones are being introduced continuously. The present OOA techniques, however, have difficulty in the identification and the verification of the objects and tend to ignore high-level control aspects of the problem due to the initial partitioning of them on the basis of the data. As a result, it brings inaccurate understanding and faults in the software which is required by users. Therefore the purpose of this paper is to design the TOVERC to verify completeness and consistency through cross-reference between the state transition diagram and the methods of object model in order to reflect the requirements of users in the analysis of software considering this problem.

• Journal of Internet Computing and Services
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• v.7 no.2
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• pp.121-136
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• 2006

Software architecture and protocols to be maintained between components for the reconfigurable SDR system is analyzed and suggest system design idea for the implementation of software. To do this, related surveys are reviews and set up the system model with the structure of embedded system. SDR system architecture is suggested with five layered structure, consisted with hardware, operating system, middle-ware, service objects and application layer. SDR system is designed to be work on the basis of Linux operating system, and aimed to be scalable and reconfigurable. It is introduced the design result of software protocol and state transition diagram for the implementations of software download function which is the most important feature in SDR.

• Proceedings of the Korea Information Processing Society Conference
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• 2001.04a
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• pp.523-526
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• 2001

3GPP2 방식에서는 Macro Mobility 지원을 위하여 MIP를 이용하며 PDSN은 FA의 기능을 수행한다. 이때 하나의 PDSN에서 다른 PDSN으로 MS가 이동할 경우 지원되는 이동성을 Macro Mobility라 하며, POSN 관리 영역 내의 하나의 RN에서 다른 RN으로 이동시에 지원되는 이동성을 Micro Mobility라 한다. 본 논문은 Micro Mobility를 지원하기 위한 멀티캐스트 그룹 메커니즘 기반의 Seamless 핸드오프 알고리즘을 제안하고 있다. 제안된 알고리즘은 MS의 이동방향과 속도를 계산하여, 예상 이동경로에 인접한 RN들을 멀티캐스트 그룹으로 구성하고, 그룹 조인 시점을 최대한 늦춤으로서 망의 효율성을 높인다. 또한, 기존의 멀티캐스트 연결 방법이 가지고 있는 버퍼 오버헤드에 대한 문제점을 해결하기 위해, PDSN은 예상 핸드오프 시간 이후의 데이터만을 전송하며, RN 또한 예상 핸드오프 시간 이후의 데이터만을 버퍼링 한다. 제안된 알고리즘의 Dead Lock Free, Liveness 및 Reliability를 검증하기 위해 State Transition Diagram을 작성하고, 페트리 네트를 이용하였다.

• Journal of Magnetics
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• v.16 no.1
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• pp.15-18
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• 2011

We have studied the $TiO_2$ doping effects on the flux pinning behavior of an $MgB_2$ superconductor synthesized by the in-situ solid-state reaction. From the field-cooled and zero-field-cooled temperature dependences of magnetization, the reversible-irreversible transition of $TiO_2$-doped $MgB_2$ was determined in the H-T diagram (the temperature dependence of upper critical magnetic field and irreversibility line). For comparison, the similar measurements are also obtained from SiC-doped $MgB_2$. The critical current density was estimated from the width of hysteresis loops in the framework of Bean's model at different temperatures. The obtained results manifest that nano-scale $TiO_2$ inclusions served as effective pinning centers and lead to the enhanced upper critical field and critical current density. It was concluded that the grain boundary pinning mechanism was realized in a $TiO_2$-doped $MgB_2$ superconductor.

• The KIPS Transactions:PartD
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• v.18D no.1
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• pp.35-44
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• 2011

Memory errors can cause not only program malfunctions but also even unexpected system halt. Though a programmer checks memory errors, some memory errors with low occurrence frequency are missed to detect. In this paper, we propose a method for effectively detecting such memory errors using instruction transition diagrams through analyzing assembly codes obtained by disassembling an executable file. Out of various memory errors, local memory return errors, null pointer access errors and uninitialized pointer access errors are targeted for detection. When applying the proposed method to various programs including well-known open source programs such as Apache web server and PHP script interpreter, some potential memory errors are detected.