• Journal of Information Technology Application
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• v.3 no.4
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• pp.63-92
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• 2001

This paper makes an attempt to look at the process of automatically generating an application software system based on the Entity-Relationship (E-R) model. Basically, the process consists of five steps as follows: First, the designer develops an E-R model of an real-world system. Second, the software generator automatically generates a stereo-type application system. Third, the generator produces database schema and link information between application programs. Fourth, the designer designs the user interface including menu, screen design and so on. Finally, the generator completes the process integrating all the elements of an application system. Five basic program generation rules, three extended rules and a database generation rule have been suggested. By following each rule with the generator, the designer can build an application with an extremely efficient manner compared with traditional approaches. A case study has been included in order to show the applicability of the automated software generation process suggested in this paper. It has been demonstrated from the case study that the idea of applying an automated generator in systems development based upon the E-R model worked well.

• The Bulletin of The Korean Astronomical Society
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• v.35 no.1
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• pp.53.1-53.1
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• 2010

$Y^2$(Yonsei-Yale) Isochrones은 Yale의 항성 진화 계산을 이용한 정밀한 등연령곡선으로 구상성단의 연구에 널리 사용되고 있다. 이번 연구에서는 $Y^2$-Isochrones를 Kurucz 모형을 이용한 색변환을 통해서 SDSS로 널리 알려진 ugriz 필터 체계에 대해 적용하고 실제 관측 결과와 비교함으로써 타당성을 검증하고자 한다. 우선 ugriz 필터의 등연령곡선을 제공하는 BaSTI와 DSEP, Padova 모델간의 비교를 통해 $Y^2$-Isochorones이 MSTO에서 g-r값이 다른 모델에 비해 0.05정도 큼을 확인하였다. 또한 CFHT 3.6m 망원경의 가시광 카메라 MegaCam으로부터 얻은 중원소 함량이 낮은 다섯 개의 구상성단 M15, M30, M53, NGC 5053, NGC 5466에 대한 g, r, i 필터의 색등급도에 각각의 등연령곡선을 적용하여 모델에 따른 구상성단의 특성을 분석하였다. $Y^2$-isochrones를 이용한 (g-r, r) CMD의 분석 결과, BaSTI와 DSEP 모델에 비해 0.1~0.3만큼 거리지수가 크고, 성단의 나이는 1~3Gyr 정도 어리게 측정됨을 확인할 수 있었다. 더불어 SDSS 관측으로부터 얻어진 구상성단에 대한 색등급도와 비교 분석과정을 수행하여, 다른 망원경에서의 사용가능 여부를 확인하였다. 이 연구를 통하여 각 모델에 따른 등연령곡선의 차이를 확인하고, 현재 여러 망원경에서 사용되고, 앞으로 여러 대형망원경에서 사용될 ugriz 필터 체계에 $Y^2$-Isochrones를 적용할 수 있는 타당성을 제시하고자 한다.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.3
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• pp.65-73
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• 2004

The bolier systems of coal fired power plants are large, non-linear systems with numerous interactions between its component parts. In the analysis of such complex systems, dynamic simulation is recognized as a powerful method of keeping track of the myriad of interactions. The boiler system consists of air/gas system and water/steam system. Due to recent reinforcement of environmental regulation on pollutant discharge and requirements of design validation on properites of boiler, the commercial programs are used for the analysis of boiler system. This paper addressed to the development of model using MMS(Modular Modeling System) developed by EPRI(Electric Power Research Institute) as the simulation tool. The developed model using MMS is tested for the design and local data on boiler combustion system of korea standard coal fired power plant boiler. The simulation results show that the developed model well reproduces responses of the combustion system with less than ${\pm}$5% error under steady state and transient state conditions. The developed model for analysis of the combustion system in this paper is general and applicable to any type of coal fired power plant.

• Journal of KIISE:Software and Applications
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• v.35 no.1
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• pp.12-21
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• 2008

As the usage of computer systems is increasing in our lives, the reliability and safely of these systems need to be thoroughly checked through the verification techniques. As a basic formalism for several modeling methods, the finite state machine (FSM) is widely used in specification and verification of system models. And there is a technique for ing internal events of FSM in order to effectively analyze the system. However, this technique does not handle the state explosion problem since it can be applied after completely generating all the state space of the system. In this research, we provide a new approach for efficiently representing concurrent properties of FSM, the slice model and provide an efficient transition reduction method based on the slice model. Our approach is effective in time and space perspective since it is peformed by partially generating the needed system states while the existing abstraction technique can be applied to all the system states.

• Journal of KIISE:Software and Applications
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• v.34 no.3
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• pp.179-195
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• 2007

Traditional software development method is not suitable for Web application development because of characteristics of Web application such as frequent requirements change, different architectures and models and quick-to-market delivery. In this paper we propose a Web application development method adaptable to requirements change while we systematically model Web application using extended UML model. The metamodel is independent to specific languages and technologies because we define the metamodel using extended UML model. Proposed process is described by SPEM(Software Process Engineering Metamodel) profile. A process supporting tool execute and customize process. To model Web applications systematically and effectively, a navigation modeling and a component communication modeling tools are provided. In a case study, we show the usefulness of our process and model.

• Journal of Digital Convergence
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• v.10 no.11
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• pp.403-418
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• 2012

In this paper, we attempted to theorize the synergy effect between the value creating attributes for digital convergence model in the service industry. Our investigation is based upon contingency fit theory to understand the strategic fit for the two inherent value attributes of fixed and mobile value, as well as resolving fundamental limitations of service processes. Empirical validation of the derived research model is analyzed using hierarchical regression method. The results indicate that the relative advantage of each value creating attributes are strongly associated with the characteristics of domain service industries, and compatibility is critical to user adoption of convergent service model. Moreover, the less significant statistical impact of the synergy between mobile and fixed value attributes and others implies that each value attribute uniquely contributes to particular IT convergence model, which thereby offers critical insight that focusing the convergent value in conjunction with specific application domain is the most appealing managerial focus. The findings provide useful insight for the further research in IT based industry convergent business model areas.

• Journal of the Korea Concrete Institute
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• v.23 no.3
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• pp.365-376
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• 2011

The current Concrete Structural Design Code (2007) prescribe the equivalent rectangular stress block of the ACI 318 Building Code as concrete compressive stress distribution for design of concrete structures. The rectangular stress block may be enough for flexural strength calculation, but realistic stress-strain relationship is required for performance verification at selected limit state in performance-based design. Moreover, the ACI rectangular stress block provides non-conservative flexural strength for high strength concrete columns. Therefore a new stress distribution model is required for development of performance-based design code. This paper proposes a concrete compressive stress-strain distribution model for design and performance verification. The proposed model has a parabolic-rectangular shape, which is adopted by Eurocode 2 and Japanese Code (JSCE). It was developed by investigation of experimental test results conducted by the authors and other researchers. The test results cover high strength concrete as well as normal strength concrete. The stress distribution parameters of the proposed models are compared to those of the ACI 318 Building Code, Eurocode 2, Japanese Code (JSCE) and Canadian Code (CSA) as well as the test results.

• Korean Chemical Engineering Research
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• v.46 no.5
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• pp.915-921
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• 2008

In most PEM fuel cell research, effects of cell geometry, physical properties of component such as membrane, carbon cloth, catalyst, etc. and water transport phenomena are key issues. The scope of these research was limited to single cell and stack except BOP(Balance of plant) of fuel cell. The research fouced on the fuel cell system usually neglect to consider detailed transport phenomena in the cell. The research of the fuel cell system was interested in a system performance and system dynamics. In this paper, the effect of the anode recirculation is calculated using the 2D steady-state model. For this work, 2D steady-state modeling and experiments are performed. For convenience of modifying of model equation, not commercial pakage but the in-house algorithm was used in simulation. For an vehicle industry, the analysis of the anode recirculation system helps the optimization of operating condition of the fuel cell.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.16 no.4
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• pp.353-367
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• 2003

This paper describes the extension of the numerical model, which was developed to simulate the nonlinear behavior of reinforced concrete (RC) structures subjected to monotonic in plane shear and introduced in the companion paper, to simulate effectively the behavior of RE structures under cyclic loadings. While maintaining all the basic assumptions adopted in defining the constitutive relations of concrete under monotonic loadings, a hysteretic stress strain relation of concrete, which across the tension compression region, is defined. In addition, unlike previous simplified stress strain relations, curved unloading and reloading branches inferred from the stress strain relation of steel considering the Bauschinger effect we used. The modifications of the stress strain relation of steel are also introduced to reflect pinching effect depending on the shear span ratio and an average stress distribution in a cracked RC element. Finally, correlation studies between analytical results and experimental studies are conducted to establish the validity of the proposed model.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.3B
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• pp.408-422
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• 2000

In this paper, we propose a generalized vector channel model for wireless communication systems using antenna arrays. The proposed channel model reflects path loss. spatial-temporal variation of shadowing, multipath fading , Doppler effect, spatial distribution of local scatterers and delay spread due to remote dominant scatterers. In addition, we use a discrete ray model in which respective ray signal experiences independent shadowing, fading and Doppler shift, and impinges on antenna arrays at a distinct angle. Based on the proposed mode. we derive the relations on the spatial and temporal correlations of the received signals and implement a spatial channel simulator. By comparing the theoretical values with the simulated ones, we verify the effectiveness of the implemented simulator. The simulator is then used to generate an arbitrary channel impulse response and to analyze the channel characteristics under various environments.