• Geomechanics and Engineering
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• 제7권5호
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• pp.525-537
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• 2014

The typical design of ground improvement with prefabricated vertical drains (PVD) and surcharge preloading involves a series of deterministic analyses using averaged or mean soil properties for the various combination of the PVD spacing and surcharge preloading height that would meet the criteria for minimum consolidation time and required degree of consolidation. The optimum design combination is then selected in which the total cost of ground improvement is a minimum. Considering the variability and uncertainties of the soil consolidation parameters, as well as considering the effects of soil disturbance (smear zone) and drain resistance in the analysis, this study presents a stochastic cost optimization of ground improvement with PVD and surcharge preloading. Direct Monte Carlo (MC) simulation and importance sampling (IS) technique is used in the stochastic analysis by limiting the sampled random soil parameters within the range from a minimum to maximum value while considering their statistical distribution. The method has been verified in a case study of PVD improved ground with preloading, in which average results of the stochastic analysis showed a good agreement with field monitoring data.

• 대한산업공학회지
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• 제32권3호
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• pp.210-218
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• 2006

Traditional statistical process control (SPC) applied to discrete part industry in the form of control charts can look for and eliminate assignable causes by process monitoring. On the other hand, engineering process control (EPC) applied to the process industry in the form of feedback control can maintain the process output on the target by continual adjustment of input variable. This study presents controlling and monitoring rules adopted by variable sampling interval (VSI) to change sampling intervals in a predetermined fashion on the predicted process levels under integrated EPC and SPC systems. Twelve rules classified by EPC schemes(MMSE, constrained PI, bounded or deadband adjustment policy) and type of sampling interval combined with EWMA chart of SPC are proposed under IMA (1,1) disturbance model and zero-order (responsive) dynamic system. Properties of twelve control rules under three patterns of process change (sudden shift, drift and random shift) are evaluated and discussed through simulation and control rules for integrated VSI EPC and SPC systems are recommended.

• Journal of Electrical Engineering and Technology
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• 제11권2호
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• pp.300-308
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• 2016

Application of demand-side resources to automatic generation control (AGC) has a great significance for improving the dynamic control performance of power system frequency regulation. This paper investigates the possibility of providing regulation services by demand-side energy storage in electric vehicle battery swapping stations (BSS). An interaction framework, namely station-to-grid (S2G), is presented to integrate BSS energy storage into power grid for giving benefits to frequency regulation. The BSS can be regarded as a lumped battery energy storage station through S2G framework. A supplementary AGC method using demand-side BSS energy storage is developed considering the vehicle user demand of battery swapping. The effects to the AGC performance are evaluated through simulations by using a two-area interconnected power grid model with step and random load disturbance. The results show that the demand-side BSS can significantly suppress the frequency deviation and tie-line power fluctuations.

• 대한기계학회논문집A
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• 제32권3호
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• pp.280-289
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• 2008

This paper presents design of the quantitative feedback control system of the three axes hydraulic road simulator with respect to the dummy wheel for uncertain multiple input-output(MIMO) feedback systems. This simulator has the uncertain parameters such as fluid compressibility, fluid leakage, electrical servo components and nonlinear mechanical connections. This works have reproduced the random input signal to implement the real road vibration's data in the lab. The replaced $m^2$ MISO equivalent control systems satisfied the design specifications of the original $m^*m$ MIMO control system and developed the mathematical method using quantitative feedback theory based on schauder's fixed point theorem. This control system illustrates a tracking performance of the closed-loop controller with low order transfer function G(s) and pre-filter F(s) having the minimum bandwidth for parameters of uncertain plant. The efficacy of the designed controller is verified through the dynamic simulation with combined hydraulic model and Adams simulator model. The Matlab simulation results to connect with Adams simulator model show that the proposed control technique works well under uncertain hydraulic plant system. The designed control system has satisfied robust performance with stability bounds, tracking bounds and disturbance. The Hydraulic road simulator consists of the specimen, hydraulic pump, servo valve, hydraulic actuator and its control equipments

• Journal of Ecology and Environment
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• 제32권4호
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• pp.229-236
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• 2009

A habitat model was developed to delineate potential habitat of the leopard cat (Prionailurus bengalensis) in a mountainous region of Kangwon Province, Korea. Between 1997 and 2005, 224 leopard cat presence sites were recorded in the province in the Nationwide Survey on Natural Environments. Fifty percent of the sites were used to develop a habitat model, and the remaining sites were used to test the model. Fourteen environmental variables related to topographic features, water resources, vegetation and human disturbance were quantified for 112 of the leopard cat presence sites and an equal number of randomly selected sites. Statistical analyses (e.g., t-tests, and Pearson correlation analysis) showed that elevation, ridges, plains, % water cover, distance to water source, vegetated area, deciduous forest, coniferous forest, and distance to paved road differed significantly (P < 0.01) between presence and random sites. Stepwise logistic regression was used to develop a habitat model. Landform type (e.g., ridges vs. plains) is the major topographic factor affecting leopard cat presence. The species also appears to prefer deciduous forests and areas far from paved roads. The habitat map derived from the model correctly classified 93.75% of data from an independent sample of leopard cat presence sites, and the map at a regional scale showed that the cat's habitats are highly fragmented. Protection and restoration of connectivity of critical habitats should be implemented to preserve the leopard cat in mountainous regions of Korea.

• Journal of Advanced Marine Engineering and Technology
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• 제23권6호
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• pp.770-777
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• 1999

In this study a phase diagram has been used to investigate the unsteadiness of two-dimensional lid-driven closed flows within a square cavity for twelve Reynolds numbers; $7.5{\times}10^3,\; 8{\times}10^3,\; 8.5{\times}10^3,\; 9{\times}10^3,\; 9.5{\times}10^3,\; 10^4,\;1.5{\times}10^4,\;2{\times}10^4,\; 3{\times}10^4,\; 7.5{\times}10^4$ and $10^5$. The results indicate that the first critical Reynolds number at which the flow unsteadiness of sinusoidal fluctuation appears from the temporal variation of total kinetic energy curves is assumed of sinusoidal fluctuation appears form the temporal variation of total kinetic energy curves is assumed to be in the neigh-bourhood of $Re=8.5{\times}10^3$ The second critical Reynolds number where the periodic amplitude and frequency collapse to random disturbance being existed around $Re=1.5{\times}10^4$ The exponentially decreasing vortices formed at the lower two corners are found commonly at the time-mean flow pattern of $Re=3{\times}10^4$.

• 생명과학회지
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• 제15권3호
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• pp.359-364
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• 2005

조릿대(Sasa borealis)집단에서 미세지리적 변이에 대한 공간적 상관관계를 조사하였다. 각 거리등급당 대립유전자좌위에서 연결계수(하나의 대립유전자좌위에서 유전자형의 조합)를 산출하였으며 그 계수가 임의 예상 값에 유의성을 가지는지 검증하였다. 150 경우 중 25 경우$(16.7\%)$가 예상 값과 유의하게 차이를 나타내었다. 이들 값 중에서 8경우$(4.7\%)$는 음의 값으로 거리등급에서 개체쌍이 유전적 비친화성이 있음을 나타낸다. 조릿대는 죽세공에 쓰이므로 인위적 별채에 의해 한국내 자연집단은 유효 집단이 유지되지 못하는 등 집단 파괴가 이루어지고 있다. 특히 조릿대가 잘 발달되어온 지리산 집단의 경우 공간적 유전 구조가 결여되어 있었다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제16권3호
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• pp.1028-1046
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• 2022

Genome-wide association studies (GWAS) aim to find the significant genetic variants for common complex disease. However, genotype data has privacy information such as disease status and identity, which make data sharing and research difficult. Differential privacy is widely used in the privacy protection of data sharing. The current differential privacy approach in GWAS pays no attention to raw data but to statistical data, and doesn't achieve equilibrium between utility and privacy, so that data sharing is hindered and it hampers the development of genomics. To share data more securely, we propose a differential privacy preserving approach of data sharing for GWAS, and achieve the equilibrium between privacy and data utility. Firstly, a reasonable disturbance interval for the genotype is calculated based on the expected utility. Secondly, based on the interval, we get the Nash equilibrium point between utility and privacy. Finally, based on the equilibrium point, the original genotype matrix is perturbed with differential privacy, and the corresponding random genotype matrix is obtained. We theoretically and experimentally show that the method satisfies expected privacy protection and utility. This method provides engineering guidance for protecting GWAS data privacy.

• Nuclear Engineering and Technology
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• 제54권2호
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• pp.617-626
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• 2022

To effectively monitor the variety of distributions of neutron flux, fuel power or temperatures in the reactor core, usually the ex-core and in-core neutron detectors are employed. The thermocouples for temperature measurement are installed in the coolant inlet or outlet of the respective fuel assemblies. It is necessary to reconstruct the measurement information of the whole reactor position. However, the reading of different types of detector in the core reflects different aspects of the 3D power distribution. The feasibility of reconstruction the core three-dimension power distribution by using different combinations of in-core, ex-core and thermocouples detectors is analyzed in this paper to synthesize the useful information of various detectors. A comparison of multilayer perceptron (MLP) network and radial basis function (RBF) network is performed. RBF results are more extreme precision but also more sensitivity to detector failure and uncertainty, compare to MLP networks. This is because that localized neural network could offer conservative regression in RBF. Adding random disturbance in training dataset is helpful to reduce the influence of detector failure and uncertainty. Some convolution neural networks seem to be helpful to get more accurate results by use more spatial layout information, though relative researches are still under way.

• 한국항해항만학회지
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• 제29권10호
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• pp.853-858
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• 2005

최근의 해안, 해양공학 분야에서는 구조물이 있는 영역의 파동을 계산하기 위해 Navier-Stokes 방정식을 기초로 한 많은 기법들이 개발되고 발전되어 왔다. 이들 중 파랑의 쇄파현상 등의 복잡한 파동현상을 재현하기 위한 수치해석 기법으로 Volume Of Fluid method (보프법)에 근거를 둔 수치해석 기법이 자주 사용되어지고 있다. 그러나 보프법은 일반적으로 방대한 계산시간과 기억용량이 요구되는 단점을 가지고 있어, 적어도 100주기 이상의 계산시간을 통한 해석이어야만 만족할 만한 결과가 나타나는 불규칙파랑의 경우, 보프법의 단독 적용으로는 현실적으로 어려워진다. 한편, 경계요소법(BEM)의 경우는 파랑을 신속하고, 정확하게 계산할 수 있으나, 비선형 현상을 재현할 수 없는 단점이 있다. 본 연구는 불규칙 파랑을 대상으로 하고, 구조물이 있는 경우의 파동현상도 계산이 가능한 수치 해석 기법의 개발을 목표로 하고 있다. 이를 위해, 두 기법의 장점을 살려 쇄파현상 등으로 인해 비선형 현상의 재현이 요구되는 영역에서는 보프법을 사용하여 계산하고, 비선형성을 무시할 수 있어 포텐셜이론이 적용 가능한 구간에서는 BEM을 사용하여 계산을 하도록 두 기법을 연결한 BEM-VOF model을 개발하였다. 개발된 수치모델의 검증은 5차 스톡스파의 파랑전파 및 불규칙파랑의 전파를 통해 수행하였다.