• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 춘계학술대회 논문집
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• pp.311-316
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• 2007

The improvement of speed and ride comfort requires a very horizontally and vertically rigid and non-flexible alignment. It is inevitable to construct many bridges depending on the topography of landscapes and obliged to lay turnouts on the bridges. In that case, special considerations have to be taken into account, i.e. permissible stresses of turnout components and limitations of displacements of bridge and turnouts. In this studies, numerical analyses for turnout/bridge interaction are carried out using commercial program LUSAS. The target of analytical model is the turnout layed near Pyeongrae-Hopyeng station on Kyeongchun line. The lead rail, stock rails, and the bridge are modelled using beam elements. Fasteners and ballast resistances are modelled using bi-linear spring elements. The turnout behaviors are investigated by varying the parameters such as span length of bridge, spring coefficients, and thermal loads.

• Biotechnology and Bioprocess Engineering:BBE
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• 제6권1호
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• pp.31-36
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• 2001

Optimal operation in chromatography is needed to save operation time and the solvent used in multiple chromatographic runs. To this end, many simulation studies of chromatography process have been performed. The relationship between the distribution coefficient and the ionic strength is important in gradient elution ion chromatography. Experimental runs and computer simulations were carried out under linear gradient elution condition in order to compare the experiments and the simulation. Experiments were performed with formic acid under isocratic conditions to determine the simulation equation parameters. Computer simulation was based on three equations which related distribution with ionic strength as follows; K=${\alpha}$I(sup)-${\beta}$, K=A+BI+Cl$^2$and K=y(sub)0+A$_1$$.$e(sup)(-I/m$_1$). The effects of gradient slope on the chromatograms are discussed, and good agreement between the experimental and the simulated results is shown.

• Journal of applied mathematics & informatics
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• 제19권1_2호
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• pp.241-251
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• 2005

In this paper, we introduce a new algebraic method to characterize rational PH plane curves. And using this method, we study the algebraic characterization of generic strongly regular rational plane PH curves expressed in the complex formalism which is introduced by R.T. Farouki. We prove that generic strongly semi-regular rational PH plane curves are completely characterized by solving a simple functional equation H(f, g) = $h^2$ where h is a complex polynomial and H is a bi-linear operator defined by H(f, g) = f'g - fg' for complex polynomials f,g.

• 한국음향학회:학술대회논문집
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• 한국음향학회 2001년도 추계학술발표대회 논문집 제20권 2호
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• pp.193-196
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• 2001

본 연구에서는 원활한 정재파 생성과 양방향 구동이 가능한 새로운 형태의 초음파 리니어 모터를 제작하고, 그 특성을 평가하였다 본 연구에서 제안한 모터는 $\lambda/4$ 간격으로 이빨 구조를 가지는 스테이터의 상, 하부에 압전소자를 $90^\circ$ 의 위치 위상차를 갖도록 부착한 형태의, 상, 하부 압전소자에 각각 동위상, 180도의 시간 위상차를 가지는 교류 전압을 인가함으로써 양방향 구동이 가능하도록 하였다. 또한 원활한 정재파를 생성할 수 있는 최적의 구조를 결정하기 위해, 여러 가지 형태의 경계조건들에 대해 유한요소해석법을 이용하여 모델링하여 각 이빨들의 변위를 관찰함으로써 각각의 구조에 대해 타당성을 검증하였다. 위 결과를 바탕으로 세 종류의 초음파 리니어 모터를 제작하여 구동실험을 하였고, 실험 결과에 따라 속도와 추력 및 양방항성이 가장 우수한 최적의 구조를 결정하였다. 본 연구에서 제작한 모터는 최대 82.4cm/s의 속도와 0.46N의 추력을 가졌다.

• Journal of Communications and Networks
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• 제9권1호
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• pp.28-33
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• 2007

Estimated channel information, especially multipath length and multipath channel of the desired user, is necessary for most previously reported linear blind multiuser detectors in code division multiple access (CDMA) systems. This paper presents a new blind intersymbol decorrelating detector in asynchronous CDMA systems, which uses the cross correlation matrix of the consecutive symbols. The proposed detector is attractive for its simplicity because no channel estimation is required except the synchronization of the desired user. Compared with other reported multiuser detectors, simulation results show that the proposed detector provides a good performance when the active users have significant intersymbol interference and the multipath length is short.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
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• pp.114-114
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• 2011

Graphene is the hottest topic in condensed-matter physics due to its unusual electronic structures such as Dirac cones and massless linear dispersions. Graphene can be epitaxially grown on various metal surfaces with chemical vapor deposition (CVD) processes. Such epitaxial graphene shows modified electronic structures caused by substrates. In the method for removal of the effect of substrate, there are bi, tri-layer graphene, gold intercalation, and oxygen intercalation. Here, We will present the changes of geometric and electronic structure of graphene grown on Ru(0001) by oxygen intercalation between graphene and Ru(0001). Using Scanning tunneling microscopy (STM) and spectroscopy (STS), we observed the aspect that the band gap features near the fermi level of graphene on Ru(0001) system is shifted and narrow. Based on the observed results, two effects by intercalated oxygen were considered.

• 한국항만경제학회지
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• 제22권1호
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• pp.175-198
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• 2006

This paper presents a network capacity model that can be used as an analytical tool for strategic planning and resource allocation for multimodal transportation systems. In the context of freight transportation, the multimodal network capacity problem (MNCP) is formulated as a mathematical model of nonlinear bi-level optimization problem. Given network configuration and freight demand for multiple origin-destination pairs, the MNCP model is designed to determine the maximum flow that the network can accommodate. To solve the MNCP, a heuristic solution algorithm is developed on the basis of a linear approximation method. A hypothetical exercise shows that the MNCP model and solution algorithm can be successfully implemented and applied to not only estimate the capacity of multimodal network, but also to identify the capacity gaps over all individual facilities in the network, including intermodal facilities. Transportation agencies and planners would benefit from the MNCP model in identifying investment priorities and thus developing sustainable transportation systems in a manner that considers all feasible modes as well as low-cost capacity improvements.

• Computers and Concrete
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• 제1권2호
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• pp.189-209
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• 2004

Several extensions to the Thelandersson phenomenological model for concrete under transient high temperatures are explored. These include novel expressions for the temperature degradation of the elastic modulus and the temperature dependency of the coefficient of the free thermal strain. Furthermore, a coefficient of thermo mechanical strain is proposed as a bi-linear function of temperature. Good qualitative agreement with various test results taken from the literature is demonstrated. Further extensions include the effects of plastic straining and temperature dependent Poisson's ratio. The models performance is illustrated on several simple benchmark problems under uniaxial and biaxial stress states.

• 한국철도학회:학술대회논문집
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• 한국철도학회 1999년도 춘계학술대회 논문집
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• pp.176-184
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• 1999

Dynamic characteristics of pantograph-catenary system that supplies electrical power to high-speed trains are investigated. A simple catenary is composed of the contact and messenger wires connected by hamgers possessing bi-directional stiffness properties. The influences of parameters that determine the contact properties of pantograph-catenary system are investigated through numerical simulations. For the catenary, a finite difference model composed of 10 spans is constructed. The contact and messenger wires are modeled as strings with respective tension and damping ratio values. The pantograph is modeled as a linear 3-degree-of-freedom system. It is found that the tension, number of hangers and damping ratios as well as the speed of the train significantly influence the contact forces and contact separation rate

• 한국지진공학회논문집
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• 제20권7_spc호
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• pp.495-502
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• 2016

In this paper, time and frequency domain characteristics of Gyeong-ju earthquakes were investigated, and nonlinear time history analyses were conducted for bi-linear hysteretic structures excited by short-duration ground accelerations. Previous studies showed that larger inelastic displacements than the peak displacement of the corresponding elastic system were observed especially for the structures with structural period shorter than 0.3s, and the similar results could be obtained when long-duration ground accelerations were used as excitation loads. For the short-duration earthquakes, however, the inelastic displacements were not so large and almost identical to the peak elastic displacements.