• JSTS:Journal of Semiconductor Technology and Science
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• 제7권2호
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• pp.88-93
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• 2007

In this paper, a simple and improved noise parameter model of RF MOSFETs is developed and verified. Based on the analytical model of channel thermal noise, closed form expressions for four noise parameters are developed from proposed equivalent small signal circuit. The modeling results show a excellent agreement with the measured data of $0.13{\mu}m$ CMOS devices.

• 한국환경과학회지
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• 제9권1호
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• pp.57-64
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• 2000

The sensitivity analysis of two short-term models (ISCST3, INPUFF2.5) is performed to improve the model accuracy. It appears that the sensitivities on the changes of wind speed, stack height and stack inner diameter in the near distance from source, stability and mixing height in the remote distance form source, are significant. Also the gas exit velocity, stack inner diameter, gas temperature and air temperature which affect the plume rise have some effects on the concentration values of each model within the downwind distance where final plume rise is determined. And in modeling for the atmospheric dispersion of point pollutant source INPUFF2.5 can calculate amount, trajectory of puff and concentration versus time at each receptors. So, it is compatible to analyze distribution of point pollutants concentration at modeling area.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.518-522
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• 2014

This paper is concerned with the dynamic modeling of transmission line undergoing galloping vibrations. To this end, the kinetic and potential energies of a uniform wire vibrating in space are derived. The equations of motion suitable for numerical simulations are derived using the assumed mode method and Lagrange equation. The resulting equations of motion are expressed in matrix form. To cope with bundled transmission line, the spacer was modelled by a spring element. As a numerical example, a two-wire transmission line combined by spacers was considered. Natural vibration characteristics show that the in-plane vibrations of the transmission line appeared in low frequency range, which may lead to galloping.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1999년도 가을 학술발표회 논문집
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• pp.378-386
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• 1999

The integrated system for the structural analysis of space frame is made up 4 modules ; pre-process module, structural analysis module, optimum member design module and post-process module. Re-process module of these 4 modules involves data input module and structure modeling module. This study is to develope an efficient modeling program as a basic for development of pre-process module. This modeling program generates geometric information of space frame and performs the input fie form for structure analysis only by input general data. User can mode1 space frame efficiently within shut time by using this program.

• International Journal of Naval Architecture and Ocean Engineering
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• 제2권2호
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• pp.96-103
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• 2010

A concept of preliminary design for mid-size superyachts is explored. First, the profile of a superyacht is interactively designed with the help of freeform curve functionality and graphical user interface (GUI) based interaction. The hull form is then constructed using major characteristic curves such as design waterline, deck sideline, and sections in addition to the predefined profile curve. After exterior hull modeling is done, the arrangement of significant interior spaces of all decks is carried out. A genetic algorithm is exploited to find a space arrangement by considering space fitness values, space proximity, and stairs connectivity of relevant spaces. A goal of the paper is to offer a step-by-step procedure for superyacht design from scratch or when initial information is not sufficient for complete design. For this purpose, a GUI based superyacht design system is developed. This design approach is expected to help users interactively design mid-size superyachts.

• Environmental Engineering Research
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• 제11권3호
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• pp.164-171
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• 2006

Numerical modeling of the flow velocity fields for the near corona wire electrohydrodynamic (EHD) flow was conducted. The steady, two-dimensional momentum equations have been computed for a wire-plate type electrostatic precipitator (ESP). The equations were solved in the conservative finite-difference form on a fine uniform rectilinear grid of sufficient resolution to accurately capture the momentum boundary layers. The numerical procedure for the differential equations was used by SIMPLEST algorithm. The Phoenics (Version 3.5.1) CFD code, coupled with Poisson's electric field, ion transport equations and the momentum equation with electric body force were used for the numerical simulation and the Chen-Kim ${\kappa}-{\varepsilon}$ turbulent model numerical results that an EHD secondary flow was clearly visible in the downstream regions of the corona wire despite the low Reynolds number for the electrode ($Re_{cw}=12.4$). Secondary flow vortices caused by the EHD increases with increasing discharge current or EHD number, hence pressure drop of ESP increases.

• 산업기술연구
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• 제25권A호
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• pp.123-131
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• 2005

Semantic object model has widely been recognized as an alternative data modeling approach to entity-relationship model for database system design. In this study, we have presented a semantic object model for intermediary type shopping mall consisting of multiple buyers and sellers. Essential processes and information with regard to the customer management, product management, price estimation, product order etc. have been considered for this study. Upon careful examination and analysis of them, a detailed semantic objects and attributes have been drawn and structured into semantic object diagrams. The final objects were converted into an entity-relationship diagram so that intuitive comparison could be made for relational database design. The results in this study may form a conceptual framework for both academic concerns and more complicated system applications.

• Journal of Power Electronics
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• 제14권3호
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• pp.572-579
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• 2014

As a non-linear time variant system, the four-quadrant line converter of an electric multiple unit (EMU) was expressed by linear time periodic functions near an operating point and modeled by a steady-state harmonic domain matrix. The components were then combined according to the circuit connection and relations of the feedback control loops to form a complete converter model. The proposed modeling method allows the study of the amplitude of harmonic impedances to explore harmonic coupling. Moreover, the proposed method helps provide a better design for the converter controllers, as well as solves the problem in coordination operation between the EMUs and the AC supply. On-site data from an actual $CRH_2$ high-speed train were used to validate the modeling principles presented in the paper.

• 대한산업공학회지
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• 제37권3호
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• pp.264-270
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• 2011

A new method for creating a logical data model is proposed. The logical data model developed by the method defines table, primary key, foreign key, and fields. The framework of the logical data model is constructed by modeling the relationships between events and their related entity types. The proposed method consists of a series of objective and quantitative decisions such as maximum cardinality of relationships and functional dependency between the primary key and attributes. Even beginners to database design can use the methology as long as they understand such basic concepts about relational databases as primary key, foreign key, relationship cardinality, parent-child relationship, and functional dependency. The simple and systematic approach minimizes decision errors made by a database designer. In practial database design the method creates a logical data model in Boyce-Codd normal form unless the user of the method makes a critical decision error, which is very unlikely.

• Structural Engineering and Mechanics
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• 제82권4호
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• pp.503-515
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• 2022

The multi-rigid-body matrix method (MRBMM) is a generalized modeling method for obtaining the displacements, forces, and dynamic characteristics of a compliant mechanism without performing inner-force analysis. The method discretizes a compliant mechanism of any type into flexure hinges and rigid bodies by implementing a multi-body mass-spring model using coordinate transformations in a matrix form. However, in this method, the deformations of bodies that are assumed to be rigid are inherently omitted. Consequently, it may yield erroneous results in certain mechanisms. In this paper, we present a multi-compliant-body matrix-method (MCBMM) that considers a rigid body as a compliant element, while retaining the generalized framework of the MRBMM. In the MCBMM, a rigid body in the MRBMM is segmented into a certain number of body nodes and flexure hinges. The proposed method was verified using two examples: the first (an XY positioning stage) demonstrated that the MCBMM outperforms the MRBMM in estimating the static deformation and dynamic mode. In the second example (a bridge-type displacement amplification mechanism), the MCBMM estimated the displacement amplification ratio more accurately than several previously proposed modeling methods.