• 한국운동역학회지
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• 제17권2호
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• pp.83-91
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• 2007

This experiment studied the change in a human's control of his or her static posture by analyzing the stabilogram diffusion and, by using the said study, evaluated the control ability of different groups with different experiences. The postures had a rising requirement of heel-rise according to three conditions: heel-toe, ball, toe; the groups were divided into dance major student and non-dance majors. The results of the critical points according to posture did not show a direct relation with the change in postures that had a rising requirement of heel-rise. The diffusion coefficient(D) had greater stochastic activity for short-term regions that utilize open-loop controls without feedback than for long-term regions that used closed-loop controls with feedback to maintain balance. The directional results of the body undergoing disturbance showed that A/P direction's diffusion coefficient (D) was larger than that of M/L direction. Both feet's planar diffusion coefficients were a linear combination of the diffusion coefficients calculated for the x and y axis. In studying the different abilities to control posture between a dance major student and a non-dance majors, a comparison of open-loop control's diffusion coefficient(D) was effective, and dance major student had superior control ability to that of non-dance majors.

• 한국정보과학회논문지:데이타베이스
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• 제37권2호
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• pp.82-91
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• 2010

네트워크 분야에서 데이터 압축은 네트워크 트래픽을 줄이기 위한 전통적이고 효과적인 방법 중 하나이다. 센서 네트워크의 데이터는 시/공간적인 연관성을 가지고 있으며, 이러한 특성을 이용한 데이터 압축 기법들이 많이 연구되고 있다. 센서 노드는 제한된 범위내의 통신이 가능하며, 자신의 통신 반경내의 데이터만을 활용한다. 만약 네트워크의 전체 데이터 분포 특성을 활용할 수 있다면, 데이터 압축의 효율을 증가시킬 수 있다. 본 논문에서는 네트워크 전체 데이터 분포 특성을 활용하기 위한 새로운 접근의 피드백 배포 기법을 통한 데이터 압축 기법을 제안한다. 제안하는 기법은 기지국 혹은 슈퍼 노드에 의해 수집된 데이터의 빈도를 이용하여 허프만 코드를 생성하고, 배포함으로써 네트워크 전체의 데이터 압축을 용이하게 한다. 본 논문의 우수성을 보이기 위해서 시뮬레이션을 통해 성능 평가를 수행하였으며 그 결과 네트워크의 수명이 약 30% 증가하였다.

• Nuclear Engineering and Technology
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• 제53권9호
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• pp.2788-2802
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• 2021

Multigroup cross section (MG XS) generation by the UNIST in-house Monte Carlo (MC) code MCS for fast reactor analysis using nodal diffusion codes is reported. The feasibility of the approach is quantified for two sodium fast reactors (SFRs) specified in the OECD/NEA SFR benchmark: a 1000 MW_th metal-fueled SFR (MET-1000) and a 3600 MW_th oxide-fueled SFR (MOX-3600). The accuracy of a few-group XSs generated by MCS is verified using another MC code, Serpent 2. The neutronic steady-state whole-core problem is analyzed using MCS/RAST-K with a 24-group XS set. Various core parameters of interest (core k_eff, power profiles, and reactivity feedback coefficients) are obtained using both MCS/RAST-K and MCS. A code-to-code comparison indicates excellent agreement between the nodal diffusion solution and stochastic solution; the error in the core k_eff is less than 110 pcm, the root-mean-square error of the power profiles is within 1.0%, and the error of the reactivity feedback coefficients is within three standard deviations. Furthermore, using the super-homogenization-corrected XSs improves the prediction accuracy of the control rod worth and power profiles with all rods in. Therefore, the results demonstrate that employing the MCS MG XSs for the nodal diffusion code is feasible for high-fidelity analyses of fast reactors.

• 대한전기학회논문지:전력기술부문A
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• 제48권10호
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• pp.1183-1189
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• 1999

This paper presents the method of parameter estimation of diffusion model for monitoring Demand-Side Management program. Bass diffusion model was applied in this paper, which has different values according to the following parameters; coefficients of innovation, imitation and potential adopters. Though it is very important to estimate three parameters precisely, there has been no empirical way in practice. Thus, this paper presents the method of parameter estimation in case of few data with constraints to reduce the possibility of bad estimation. The constraints can be empirical results or expert's decision. Case studies show the diffusion curves and forecasted values of the peak for the high-efficient lighting. The feedback and nonlinear least-square parameter estimation methods used in this paper enable us to evaluate the status and to predict the effect of DSM program.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 C
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• pp.1073-1075
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• 1998

This paper presents the method of parameter estimation of diffusion model for monitoring Demand-Side Management Program. Bass diffusion model was applied in this paper, which has different values according to parameters ; coefficients of innovation, imitation and potential adopters. Though it is very important to estimate three parameter, there are no empirical results in practice. Thus, this paper presents the method of parameter estimation in case of few data with constraints to reduce the possibility of bad estimation. The constraints are empirical results or expert's decision. Case studies show the diffusion curves of high-efficient lighting and also forecasting of the peak value for power demand considering diffusion of high-efficient lighting, the feedback and least-square parameter estimation method used in this paper enable us to evaluate the status and forecasting of the effect of DSM program.

• 천문학회보
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• 제45권1호
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• pp.70.3-70.3
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• 2020

Previous numerical simulations on planet-disk interactions revealed a lot of interesting phenomena including the planetary migration and the formation of many sub-structures inside the disks. However, these simulations were limited to an isothermal or adiabatic equation of state which does not account for various heating and cooling processes in the disks. Recent studies showed that the behavior of the planet-disk interaction can be significantly influenced by the disk thermodynamics. We develop a radiative diffusion module based on the two-temperature flux-limited diffusion approximation accounting for viscous heating and the accretion feedback. In this presentation, we describe our radiative diffusion solver, present some test results, and discuss potential applications of the module to planet-disk interactions,

• Journal of the Optical Society of Korea
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• 제10권2호
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• pp.86-90
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• 2006

The external feedback effect on the relative intensity noise (RIN) characteristics of blue InAlGaN laser diode has been analyzed taking into account the spontaneous emission noise and the injection current for the high frequency modulation. A Langevin diffusion model was exploited to characterize its relative intensity noise. The simulation parameters were quantitatively evaluated from the optical gain properties of the InAlGaN multiple quantum well active regions by using the multiband Hamiltonian for the strained wurtzite crystals. The extracted parameters were then applied to the rate equations taking into account the external feedback and the high frequency modulation current. The RIN characteristics were investigated to optimize the low frequency laser diode noise characteristics.

• Journal of applied mathematics & informatics
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• 제26권1_2호
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• pp.29-44
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• 2008

By employing the continuation theorem of coincidence degree theory, we derive a sufficient condition for the existence and attractricity of a positive periodic solution for a generalized predator-prey model with diffussion feedback controls.

• Nuclear Engineering and Technology
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• 제51권7호
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• pp.1721-1728
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• 2019

The advanced node core code CORCA-3D is one of the independent developed codes of NPIC for the nuclear reactor core design. CORCA-3D code can calculate the few-group cross section, solve the 3D diffusion equations, consider the thermal-hydraulic feedback, reconstruct the pin-by-pin power. It has lots of functions such as changing core status calculation, critical searching, control rod value calculation, coefficient calculation and so on. The main theory and functions of CORCA-3D code are introduced and validated with a lot of reactor measured data and the SCIENCE system. Now, CORCA-3D code has been applied in ACP type reactor nuclear cores design.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권3호
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• pp.1785-1801
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• 2017

In recent years, image encryption algorithms have been developed rapidly in order to ensure the security of image transmission. With the assistance of our previous work, this paper proposes a novel chaotic image encryption algorithm based on self-adaptive model and feedback mechanism to enhance the security and improve the efficiency. Different from other existing methods where the permutation is performed by the self-adaptive model, the initial values of iteration are generated in a novel way to make the distribution of initial values more uniform. Unlike the other schemes which is on the strength of the feedback mechanism in the stage of diffusion, the piecewise linear chaotic map is first introduced to produce the intermediate values for the sake of resisting the differential attack. The security and efficiency analysis has been performed. We measure our scheme through comprehensive simulations, considering key sensitivity, key space, encryption speed, and resistance to common attacks, especially differential attack.