• 한국대기환경학회지
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• 제23권6호
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• pp.708-717
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• 2007

In the present study, one of the widely applied equations for gas-solid cyclones, Leith and Licht model, was evaluated based on the 3-D CFD technique. The initial and boundary values of radial position and tangential velocity obtain-ed from the CFD simulation enabled complete calculation of the nonlinear second differential equation. This approach showed about 30% errors between calculations with and without the second order differential term. The calculation by using the simple first order equation presented shorter times to migrate up to the inner wall of the cyclone than by the second order, which theoretically implies higher separation efficiency. Further comparison is now under evaluation in terms of the detailed grade efficiency.

• 대한화학회지
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• 제35권2호
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• pp.111-118
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• 1991

기체 상태의 오존(0.5 torr)과 이산화황간의 반응속도를 연구하였다. 이산화황은 7∼22 torr 의 압력범위에서 90∼155$^{\circ}$C의 온도영역에서 반응시켰다. 오존과 이산화황의 반응속도는 이산화탄소와의 반응보다 빨리 진행되었다. 오존과 이산화황의 반응속도식은 -d(O$_3 )/dt = k _0 (SO _2 )(M)(O _3)+2k _1(SO_2 )(O _3$)였다. 이 속도식의 첫 항은 3분자 반응으로 낮은 온도에서 우세하게 진행되었으며, 속도상수 k$_0 =(9.35{\pm}8.6){\times}10^9e^{-(11.05{\pm}2.04)kcal/RT}(M^{-2}s^{-1}$)이다. 속도식의 두번째 항은 2분자 열분해 반응으로부터 유도된 주된 반응으로 속도상수 k$_1=(1.53{\pm}1.5){\times}10^{11}e^{-22.7 kcal/RT}$이다. 전 반응차수는 주로 2차 반응이며 3차 반응과 복합반응으로 진행되었다.

• 응용통계연구
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• 제14권1호
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• pp.71-80
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• 2001

로지스틱 회귀모형은 이항 반응자료에 대한 가장 보편적인 일반화 선형모형으로 독립변수에 대한 확률함수를 추정하는데 이용된다. 많은 실제적 상황에서 확률함수가 종형의 곡선형태로 표현되는데 이 경우에는 2차항을 포함한 로지스틱 회귀모형을 이용한 분석은 대칭성을 갖는 확률함수에 대한 가정으로 인해 비대칭 형태의 종형곡선에서는 확률함수의 신뢰성이 저하되고, 2차항을 포함하기 때문에 독립변수의 효과를 설명하기가 쉽지 않다는 제한점을 가지고 있다. 본 논문에서는 이러한 문제점을 해소하기 위해서 로지스틱 회귀분석과 반복적 이분법을 이용하여 종형의 형태에 관계없이 확률곡선을 추정하는 방법론을 제안하고 모의 실험을 통해 2차항을 포함한 로지스틱 회귀모형과 비교하고자 한다.

• 대한음성학회:학술대회논문집
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• 대한음성학회 2003년도 10월 학술대회지
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• pp.97-100
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• 2003

This paper addresses a method of convolutive source separation that based on SEONS (Second Order Nonstationary Source Separation) [1] that was originally developed for blind separation of instantaneous mixtures using nonstationarity. In order to tackle this problem, we transform the convolutive BSS problem into multiple short-term instantaneous problems in the frequency domain and separated the instantaneous mixtures in every frequency bin. Moreover, we also employ a H infinity filtering technique in order to reduce the sensor noise effect. Numerical experiments are provided to demonstrate the effectiveness of the proposed approach and compare its performances with existing methods.

• 제어로봇시스템학회논문지
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• 제22권6호
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• pp.477-482
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• 2016

This paper presents a simple approximation-based design approach for consensus tracking of heterogeneous second-order nonlinear systems under a directed network. All nonlinearities of followers are assumed to be unknown and non-identical. In the controller design procedure, graph-independent error surfaces are used and an unimplementable intermediate controller for each follower is designed at the first design step. Then, by adding and subtracting a graph-based term at the second step, the actual controller for each follower is designed by using one neural network employed to estimate a lumped and distributed nonlinearity. Therefore, the proposed local controller for each follower has a simpler structure than existing approximation-based consensus tracking controllers for multi-agent systems with unmatched nonlinearities.

• 국제학술발표논문집
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• The 6th International Conference on Construction Engineering and Project Management
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• pp.472-476
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• 2015

The purpose of this study is to fully understand the present state of the domestic construction companies, and to analyze phased business types and construction management techniques in order to initiate overseas expansion. Because of the recession in the domestic construction market, a thorough and strategic perspective to constantly develop inroads into overseas market is required. So we carried out a questionnaire survey targeting the experts of the overseas construction and researcher, and consulted them in depth. The questionnaire survey was divided into three sections. The first section is the necessity of overseas construction and the reason. The second is the overseas business types classified into the way of advance in short-term and long-term phase possibility of expansion. Lastly, the importance of the phased construction management techniques and the current capacity of the domestic and the foreign business trends were scrutinized. On the basis of the consultation and surveys, we analyzed the overseas business types and the construction management types in the short-term and long-term phase.

• 한국측량학회:학술대회논문집
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• 한국측량학회 2010년 춘계학술발표회 논문집
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• pp.429-431
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• 2010

The hybrid geoid model should be determined by fitting the gravimetric geoid to the geometric geoid which were presented the local vertical level. Therefore, it is necessary to find firstly the optimal scheme for improving the accuracy of gravimetric geoid in order to development the high-precision hybrid geoid model. Through finding the optimal scheme for determining the each part of gravimetric geoid, the most accurate gravimetric geoid model in Korea will be developed when the EIGEN-CG03C model to degree 360, 4-band spherical FFT and RTM reduction methods were used for determining the long, middle and short-frequency part of gravimetric geoid respectively. Finally, we developed the hybrid geoid model around Korea by correcting to gravimetric geoid with the correction term. The correction term is modelled using the difference between GPS/Levelling derived geoidal heights and gravimetric geoidal heights. The stochastic model used in the calculation of correction term is the LSC technique based on second-order Markov covariance function. 503 GPS/Levelling data were used to model the correction term. The degree of LSC fitting to the final hybrid geoid model in Korea was evaluated as 0.001m ${\pm}0.054m$.

• 전기의세계
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• 제22권3호
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• pp.49-62
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• 1973

An algorithm for the state estimation and identification of multivariable nonlinear systems with noisy nonlinear observation has been investigated on the basis of the multidimensional Hermitian expansion for the a posteriori probability densities of the predicted observation, the predicted state and the observation conditioned by the state. A new approach for construction of this sequential nonlinear estimator, retaining up to the second order term of the observation error, has been developed, along with the approximation of nonlinear system functions, truncating at the second term. The estimation of the unknown parameters has been established by extending the state estimation technique, regarding the parameters as another state variables. The results of investigation indicate the feasibility of the schemes presented in this paper.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2001년도 봄 학술발표회 논문집
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• pp.301-308
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• 2001

The problem of predicting crack propagation in anisotropic solids which is a subject of considerable practical importance is examined. The effect of the second term in the asymptotic expansion of the crack tip stress field on the direction of initial crack extension is made explicitly. We employ the normal stress ratio theory to determine values for the direction of initial crack extension. The theoretical analysis is performed for the wide range of the anisotropic material properties. It is shown that the use of second order term in the series expansion is essential for the accurate determination of crack growth direction in anisotropic solids.

• Journal of applied mathematics & informatics
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• 제28권5_6호
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• pp.1035-1054
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• 2010

We consider a mixed type singularly perturbed one dimensional elliptic problem with discontinuous source term. The domain under consideration is partitioned into two subdomains. A convection-diffusion and a reaction-diffusion type equations are posed on the first and second subdomains respectively. Two hybrid difference schemes on Shishkin mesh are constructed and we prove that the schemes are almost second order convergence in the maximum norm independent of the diffusion parameter. Error bounds for the numerical solution and its numerical derivative are established. Numerical results are presented which support the theoretical results.