• Journal of the Korean Society for Library and Information Science
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• v.44 no.3
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• pp.5-24
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• 2010

The public library is the local centre and gateway of knowledge and information. Therefore, the library should be funded and operated by local government and the governing body will be responsible for matters of policy of the library. However, recently public libraries in Korea have faced enormous policy challenges such as the damage of its identity, outsourcing or contracting-out of management, and the general chaos of its administrative system. This paper aims to analyze the current level of infrastructure and policies of public libraries and to review the wrong path and the right path of library policies focused on establishing a library foundation and outsourcing library management in Seoul and Incheon.

• Journal of Electrical Engineering and Technology
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• v.9 no.4
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• pp.1283-1289
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• 2014

The state transition matrix are obtained by solving state equations in terms of Laplace inverse transformation and Cayley-Hamilton theorem, and an establishment of a precise discrete-iterative mapping of the voltage-fed buck-boost converter operating in discontinuous conduction mode is made. On the basis of the mapping, the converter bifurcation diagrams and Lyapunov exponent diagrams with the input voltage, the resistance, the inductance and the capacitance as the bifurcation parameters are obtained, and the effect of the parameters on the system stability is deeply studied. The results obtained show that they have a great influence on the stability of the system, and the general trend is that the increase of either the voltage-fed coefficient, input voltage or the load resistance, or the decrease of the filtering inductance, capacitance will make the system stability become poorer, and that all the parameters have a critical value, and when they are greater or less than the values, the system will go through stable 1T orbits, stable 2T orbits, 4T orbits, 8T orbits and eventually approaches chaos.

• 한국정보통신설비학회:학술대회논문집
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• 2005.08a
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• pp.406-414
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• 2005

In this paper, we propose 128bits chaotic block encryption scheme using a PLCM(Piece-wise Linear Chaotic Map) having a good dynamical property. The proposed scheme has a block size of 128 bits and a key size of 128 bits. In proposed scheme we use four 32bi1s sub-keys of session key and four 32bit sub-blocks of block to decide the initial value and the number of iteration of PLCM. The encrypted code is generated from the output of PLCM. With results of test and analyses of security we show the proposed scheme is very secure against statistical attacks and have very good Avalanche Effect and Randomness properties.

• Journal of Power Electronics
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• v.15 no.1
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• pp.160-176
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• 2015

This paper presents a method of designing optimal integer- and fractional-order proportional-integral-derivative (FOPID) controllers for a boost converter to gain a set of favorable characteristics at various operating points. A Pareto-based multi-objective optimization approach called strength Pareto evolutionary algorithm (SPEA) is used to obtain fast and low overshoot start-up and dynamic responses and switching stability. The optimization approach generates a set of optimal gains called Pareto set, which corresponds to a Pareto front. The Pareto front is a set of optimal results for objective functions. These results provide designers with a trade-off look-up table, in which they can easily choose any of the optimal gains based on design requirements. The SPEA also overcomes the difficulties of tuning the FOPID controller, which is an extension to the classic integer-order PID controllers and potentially promises better results. The proposed optimized FOPID controller provides an excellent start-up response and the desired dynamic response. This paper presents a detailed comparison of the optimum integer- and the fractional-order PID controllers. Extensive simulation and experimental results prove the superiority of the proposed design methodology to achieve a wide set of desired technical goals.

• Proceedings of the KOSOMBE Conference
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• v.1996 no.11
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• pp.363-367
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• 1996

In general, the physiological systems have shown nonlinear complex phenomena. This study analyzes nonlinear characteristics of the flow of peripheral blood vessel dynamics in physiological systems using chaos theory. We performed this study by means of several quantity methods and power spectrum. The quantity methods are a phase space reconstruction and a poincare's map. And the power spectrum method is a conventional linear analysis. Experimental data have been acquired from examining 10 diabetic patients, and 10 control subjects in initial stable state. In acquisition experminetal data, we anlysized the differences of nonlinear characteristics between diabetic group and control group. The results of quality analysis methods showed the flow of peripheral blood vessel had the nonlinear and chaotic characteristics, screening a strange attractor on reconstructed phase space. In conclusion, the flow dynamics of peripheral blood vessel had a chaotic behavior of nonlinear dynamic systems, dynamic system, and differences of characteristic of nonlinear dynamic system.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1797-1798
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• 2007

In field of voice pathology, diverse statistics extracted form pitch estimation were commonly used to assess voice quality. In this study, we proposed robust pitch detection algorithm which can estimate pitch of pathological voices in benign vocal fold lesions. we also compared our proposed algorithm with three established pitch detection algorithms; autocorrelation, simplified inverse filtering technique, and nonlinear state-space embedding methods. In the database of total pathological voices of 99 and normal voices of 30, an analysis of errors related with pitch detection was evaluated between pathological and normal voices, or among the types of pathological voices. According to the results of pitch errors, gross pitch error showed some increases in cases of pathological voices; especially excessive increase in PDA based on nonlinear time-series. In an analysis of types of pathological voices classified by aperiodicity and the degree of chaos, the more voice has aperiodic and chaotic, the more growth of pitch errors increased. Consequently, it is required to survey the severity of tested voice in order to obtain accurate pitch estimates.

• Korean Institute of Interior Design Journal
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• no.18
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• pp.110-116
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• 1999

인류의 역사가 시작된 이후, 인간의 창조는 자연의 모방이라는 큰 울타리 안에서 이루어져 왔다. 신의 작품이 위대한 자연이라면, 인간의 작품은 극히 단순한 그것의 모방에 불과한 것인데, 인간은 인간의 제한된 두뇌 활동으로 이해하기가 불가능한 복잡한 자연을 인식하기 위하여 단순화(simplification)라는 방법을 사용하여 왔다. 이 과정에서 기하학(geometry)은 극도로 발전하게 되며, 인간의 자연 인식을 위한 보편적인 수단으로 자리잡게 된다. 중요한 사실은 기하학이 수단으로서 뿐만 아니라 인간에 의한 창조의 목표로서 위치하게 되었다는 사실이다. 즉 기하학은 자연의 모방이전에 이미 인간의 상상력을 지배해왔고, 그것은 가장 보편적인 창조원리가 되어왔다는 점이다. 그러나 최근의 과학과 기술의 발전, 특히 컴퓨터 기술의 발전으로 그 복잡한 자연은 단순화의 과정을 거치지 않은 복잡한(complex) 상태로 인간에게 이해되어지기 시작했다. 그중 하나가 19세기에 시작된 복잡성(chaos)이론인데 실내공간의 디자인에 있어서도 이러한 자연의 복잡성(complexity)이 새로운 창조 원리로서 자리잡게 되었다. 대표적인 실내 공간 다지이너로서 Nigel Coats를 꼽을 수 가 있는데 그의 무정부적인 (anarchism) 디자인 성향은 자연에서 발견될 수 있는 특징중의 하나라고 할 수 있다. 그가 추구한 복잡성(complexity)은 일본의 동경과 같은 고 밀도(high density)의 적극적 소비 도시(active consuming city)에서 발견되는 지극히 인간적인 도시생활을 만들기 위한 software의 제작이며, 이는 자연이라는 신의 창조물에 근접한 모방이 된다. 본 연구는 Nigel Coats의 작품에서 발견될 수 있는 이러한 무정부주의적 성향이 어떻게 자연의 본질적인 복잡한 (complex) 모습과 관련이 되는가를 통하여 현대 실내디자인의 새로운 방향이 이 시대의 과학적 발견에 따른 복잡성(complexity)과 유관함을 보여준다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1993.10a
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• pp.77-83
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• 1993

In this paper, the dynamics of a 2-DOF not 1:1 resonant Hamiltonian system are studied. In the first part of the work, the behaviors of special periodic orbits called normal modes are examined by means of the harmonic balance method and their approximate stability ar analyzed by using the Synge's concept named stability in the kinematico-statical sense. Secondly, the global dynamics of the system for low and high energy are studied in terms of a perturbation analysis and Poincare' maps. In this part, one can see that the unstable normal mode generates chaotic motions resulting from the transverse intersections of the stable and unstable manifolds. Although there exist analytic methods for proving the existence of infinitely many periodic orbits, chaos, they cannot be applied in our case and thus, the Poincare' maps constructed by direct numerical integrations are utilized fot detecting chaotic motions. In the last part of the work, the existence of arbitrarily many periodic orbits of the system are proved by using a subharmonic Melnikov's method. We also study the possibility of the breakdown of invariant KAM tori only when h>h$_{0}$ (h$_{0}$:bifurcating energy) and investigate the generality of the destruction phenomena of the rational tori in the systems perturbed by stiffness and inertial coupling.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.05a
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• pp.171-174
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• 2009

Generally the neural network and the fuzzy compensative algorithm are applied to forecast the time series for power demand with a characteristic of non-linear dynamic system, but it has a few prediction errors relatively. It also makes long term forecast difficult for sensitivity on the initial condition. On this paper, we evaluate the chaotic characteristic of electrical power demand with analysis methods of qualitative and quantitative and perform a forecast simulation of electrical power demand in regular sequence, attractor reconstruction, time series forecast for multi dimension using Lyapunov exponent quantitatively. We compare simulated results with the previous method and verify that the purpose one being more practice and effective than it.

• Journal of the Korean Society of Industry Convergence
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• v.24 no.5
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• pp.635-639
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• 2021

As times goes by, a ton of electric devices have been developing. Nowadays, there are many personal electric goods that are connected each other and have important private information such as identification, account number, passwords, and so on. As many people own at least one electric device, security of the electric devices became significant. To prevent leakage of the information, study of Chaotic TRNG, "Chaotic True Random Number Generator", protecting the information by generating random numbers that are not able to be expected, is essential. In this paper, A chaotic TRNG is introduced is simulated. The proposed Chaotic TRNG is simulated with Virtuoso &, a circuit design program of Cadence that is a software company. For simulating the mentioned Chaotic TRNG, setting values, 0V low and 3V high on Vpulse, 1.2V on V-ref, 3.3V on VDD, and 0V on VSS, are used.