• Journal of the Society of Naval Architects of Korea
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• v.61 no.1
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• pp.19-28
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• 2024

Environmental regulations are becoming more stringent in response to climate change, especially concerning marine pollution caused by ship emissions. Large ships are adjusting by integrating technologies to reduce pollutant emissions and transitioning to eco-friendly fuels such as low-sulfur oil and LNG. However, small ships face space constraints for installing LNG propulsion systems and the risk of power depletion with pure electric propulsion. Consequently, there's growing interest in researching hybrid propulsion methods that combine electricity and diesel for smaller vessels. Hybrid propulsion systems utilize diverse energy sources, requiring an effective method for evaluating their efficiency. This study proposes employing Bond graph modeling to comprehensively analyze energy dynamics within hybrid propulsion systems, facilitating better understanding and optimization of their efficiency. Modeling of the ship's energy system using Bond graphs will be able to provide a framework for integrating various energy sources and evaluating their effects.

• The Journal of Economics, Marketing and Management
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• v.12 no.3
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• pp.23-33
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• 2024

This study aims to enhance the accuracy of effective demand analysis for publicly supported private rental housing by integrating the RIR into the traditional Mankiw-Weil (MW) model. Traditional models like the M-W model, which account for household income, housing costs, and household size, often fall short in estimating demand driven by large-scale development projects. By integrating the RIR factor, this study introduces a more accurate and practical approach to analyzing effective housing demand. Findings show that the modified M-W model incorporating RIR predicts effective demand with greater precision than traditional methods. This advancement allows developers to plan projects more efficiently and aids governments and local authorities in implementing more effective housing policies. Furthermore, the study assesses the real housing cost burden on households, elucidating their capacity to pay housing costs based on household size and income quintile. This information enables policymakers to design targeted housing support policies for specific demographic groups. Additionally, the research provides comprehensive policy recommendations tailored to various regions and housing types. Overall, this study lays a vital groundwork for the long-term analysis of the effects of economic changes and housing market trends on effective demand.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.5 no.1
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• pp.55-78
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• 2001

Given the anisotropic Poisson equation $-{\nabla}{\cdot}{\mathcal{K}}{\nabla}p=f$, one can convert it into a system of two first order PDEs: the Darcy law for the flux $u=-{\mathcal{K}{\nabla}p$ and conservation of mass ${\nabla}{\cdot}u=f$. A very natural mixed finite volume method for this system is to seek the pressure in the nonconforming P1 space and the Darcy velocity in the lowest order Raviart-Thomas space. The equations for these variables are obtained by integrating the two first order systems over the triangular volumes. In this paper we show that such a method is really a standard finite element method with local recovery of the flux in disguise. As a consequence, we compare two approaches in analyzing finite volume methods (FVM) and shed light on the proper way of analyzing non co-volume type of FVM. Numerical results for Dirichlet and Neumann problems are included.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2000.04a
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• pp.140-145
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• 2000

The spectral method which is composed of an eigenfunction expansion of free modes in the wave number domain is used to produce two dimensional unsteady inviscid wave simulation such as progressive waves in a numerical pneumatic wave tank. A spatial and time dependent free surface elevation and the potential are calculated by integrating ODE derived from fully nonlinear kinematic and dynamic free surface boundary condition at each time step. The nonlinear characteristics in the waves by this method were notable as increasing wave steepness. This method is very useful and powerful in terms of saving computational time caused by rapid convergence exponentially with increasing number of nodes, even preserving accurate numerical results. Moreover, it will given us many possibilities to apply to naval and ocean engineering fields.

• Nuclear Engineering and Technology
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• v.49 no.6
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• pp.1135-1142
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• 2017

The applicability of the algebraic collapsing acceleration (ACA) technique to the method of characteristics (MOC) in cases with scattering anisotropy and/or linear sources was investigated. Previously, the ACA was proven successful in cases with isotropic scattering and uniform (step) sources. A presentation is first made of the MOC implementation, available in the DRAGON5 code. Two categories of schemes are available for integrating the propagation equations: (1) the first category is based on exact integration and leads to the classical step characteristics (SC) and linear discontinuous characteristics (LDC) schemes and (2) the second category leads to diamond differencing schemes of various orders in space. The acceleration of these MOC schemes using a combination of the generalized minimal residual [GMRES(m)] method preconditioned with the ACA technique was focused on. Numerical results are provided for a two-dimensional (2D) eight-symmetry pressurized water reactor (PWR) assembly mockup in the context of the DRAGON5 code.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.254-255
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• 2011

This paper presents a method to analysis the effect for integrating Sihwa tidal power into power systems. Especially, power flow, fault current, voltage and contingency of sihwa tidal power plant area are calculated and the generation characteristics of tidal machine are analyzed.

• 제어로봇시스템학회:학술대회논문집
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• 1992.10a
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• pp.407-411
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• 1992

A method for optimal route planning is presented with the assumption that the overall defended area is known in terms of threat potential function. This approach employes tangent plane to reduce the dimension of the state space for optimal programming problems with a state equality constraint. One-dimensional search algorithm is used to select the optimal route among the extermal fields which are obtained by integrating three differential equations from the initial values. In addition to being useful for the route planning through threat potential area, the trajectory planning will be suitable for general two-dimensional searching problems.

• 제어로봇시스템학회:학술대회논문집
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• 1990.10a
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• pp.749-754
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• 1990

NC machine is xi expensive and valuable asset to a manufacturing enterprise. Consequently, a great deal of work has been done to maximize the productivity of this equipment. A major goal of all of these efforts is to achieve connection of this machine lo computers, integrating them into factory information system so that they can not only be driven, but cm be managed as well. This paper describes an approach to implement NC companion standard(NC-CS) to MMS.

• Proceedings of the KSRS Conference
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• 1998.09a
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• pp.207-212
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• 1998

It is not easy to identify a ground control point (GCP) or even locate its vicinity from a SAR image. Although simulated SAR images may be useful to interpret mountain areas, they are not useful in flat areas because they do not show ground coverage or key features such as rivers, lakes and roads. In this study, we developed a method to simulate SAR images integrating geographical features to DEM to facilitate to locate ground control features from SAR images.

• Proceedings of the Korean Information Science Society Conference
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• 2003.10c
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• pp.268-270
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• 2003

전송 기존의 유선 네트？과 새로이 신설되고 있는 무선 네트？을 통합하려는 노력은 보다 폭넓은 사용 가치를 이끌어내는 주요 역할을 하고 있다. 이러한 목적을 위해서 유선의 안정되고 빠른 속도의 데이터 통신에 간섭과 데이터 손실로 인한 비교적 불안정하고 느린 무선 데이터 통신의 효율적 통합이 선결적으로 요구되어진다. 본 논문에서는 데이터 버퍼에 유지되는 데이터 패킷을 보다 빨리 전송하여 유무선 통신의 속도 차이에서 오는 손실을 최대한으로 방지함으로써 그렇지 않았을 경우 발생하는 트래픽 성능의 저하를 막고자 하는 방법을 제안하고자 한다.