• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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• pp.1-12
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• 2006

For advanced civil engineering structures a service life of hundred up to hundred fifty and even two hundred years is sometimes required. The prediction of the performance of concrete structures over such a long period requires accurate and reliable predictive models. Most of the presently used, mostly experience based models don't have the quality and reliability that is required for reliable long-term predictions. The models designers are searching for should be based on an accurate description of the relevant degradation mechanisms. The starting point of such models is a realistic description of the microstructure of the concrete. In this presentation the need and the role of fundamental microstructural models for predicting the performance of concrete structures will be presented. An example will be given of a microstructural model with a proven potential for long-term predictions. Besides this also the role of models in general, i.e. in the whole design and execution process of concrete structures, will be dealt with. Finally recent trends in concrete research will be presented, like the research on self-healing cement-bases systems.

• Journal of Information Technology Applications and Management
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• 제13권4호
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• pp.121-140
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• 2006

UDDI (Universal Discovery Description and Integration) Registry is used for Web Services registration and search. UDDI offers the search result to the keyword-based query. UDDI supports WSDL registration but it does not supports WSDL search. So it is required that contents based search and ranking using name and description in UDDI registration information and WSDL. This paper proposes a retrieval engine considering contents of services registered in the UDDI and WSDL. It uses Vector Space Model for similarity comparison between contents of those. UDDI registry information hierarchy and WSDL hierarchy are considered during searching process. This engine suppports two discovery methods. One is Keyword-based search and the other is template-based search supporting ranking for user's query. Template-based search offers how service interfaces correspond to the query for WSDL documents. Proposed retrieval engine can offer search result more accurately than one which UDDI offers and it can retrieve WSDL which is registered in UDDI in detail.

• Industrial Engineering and Management Systems
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• 제3권1호
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• pp.1-11
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• 2004

This paper proposes a new algorithm for determining an optimal control input for production systems. In many production systems, completion time should be planned within the due dates by taking into account precedence constraints and processing times. To solve this problem, the max-plus algebra is an effective approach. The max-plus algebra is an algebraic system in which the max operation is addition and the plus operation is multiplication, and similar operation rules to conventional algebra are followed. Utilizing the max-plus algebra, constraints of the system are expressed in an analogous way to the state-space description in modern control theory. Nevertheless, the formulation of a system is currently performed manually, which is very inefficient when applied to practical systems. Hence, in this paper, we propose a new algorithm for deriving a state-space description and determining an optimal control input with several constraint matrices and parameter vectors. Furthermore, the effectiveness of this proposed algorithm is verified through execution examples.

• 대한원격탐사학회지
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• 제17권2호
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• pp.155-164
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• 2001

In this study, we describe the technique for deriving a digital elevation model (DEM) from a synthetic aperture radar (SAR) stereo image pair and apply it to an image pair over "Kwanak-san" in Seoul, Korea. This paper contains brief discussion of the use of stereo SAR to derive topographic data, description of the overall structure of the stereo SAR processing system, description of the site and SAR data used for the evaluation and the source of validation data, results of the stereo SAR processing, analysis and evaluation of their accuracy against map data, and finally summarizes the main highlights of the method used, comments and recommendations on its future implementation.

• 한국자기학회지
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• 제5권5호
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• pp.645-649
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• 1995

The depletion of thin liquid films due to the combined effect of centrifugation, surface roughness, and air-shear has recently been studied. While surface roughness of a rotating solid disk can be represented by deterministic cures, it has been argued that spatial random processes provide a more realistic description. Chiefly because of surface roughness, there is an asymptotic limit of retention of a thin film flowing on the rotating disk. The aim of this article is to model the depletion of thin-film flow and analyze the interplay of centrifugation, surface tension, viscosity, air-shear, disjoining pressure, and surface roughness that affect the depletion of the film. Also, the robustness of stochastic description of surface roughness is examined.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2010년도 추계학술발표대회
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• pp.132-135
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• 2010

FTA(Free Trade Agreement)는 체결국들의 자유로운 물자 이동을 기반으로 무역의 활성화와 외국자본의 직접투자를 통해 경제성장을 가져오는 중요한 협정이다. 그러나 FTA 협정의 체결조건에 따라 품목별 세율 등의 정보가 달라진다. 국제통일상품분류체계(Harmonized Commodity Description and Coding System)코드도 마찬가지로 국제 공동코드 영역인 6 자리까지 동일 하나, 7 ~ 10 자리까지는 각 국가에 의해 운영관리 되어, 국가별로 품목분류 방식이 달라진다. 또한, 품목분류코드가 갱신 될 때마다 연관 정보를 사용자에게 제공하고 있다. 그러나 우리나라와 FTA 체결국간 세부품목분류 방식이 달라 품목분류방식의 의미에 따라 담당자가 한 건씩 비교하고 맵핑하여, 많은 시간과 인력이 소모된다. 따라서, 의미를 갖는 품목분류코드를 맵핑하면서 발생하는 문제들이 있다. 이를 해결하기 위해, 이 논문에서는 품목분류코드 기반의 온톨로지 모델을 제안한다.

• International Journal of Aeronautical and Space Sciences
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• 제16권2호
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• pp.254-263
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• 2015

In this study, numerical simulations are carried out to investigate the dynamic SGS model effects in a Kerosene-LOx coaxial swirl injector under high pressure conditions. The turbulent model is based on large-eddy simulation (LES) with real-fluid transport and thermodynamics. To assess the effect of the dynamic subgrid-scale (SGS) model, the dynamic SGS model is compared with that of the algebraic SGS model. In a swirl injector under supercritical pressure, the characteristics of temporal pressure fluctuation and power spectral density (PSD) present comparable discrepancies dependant on the SGS models, which affect the mixing characteristics. Mixing efficiency and the probability density (PDF) function are conducted for a statistical description of the turbulent flow fields according to the SGS models. The back-scattering of turbulent kinetic energy is estimated in terms of the film thickness of the swirl injector.

• Archives of Pharmacal Research
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• 제3권1호
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• pp.13-16
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• 1980

The model of an isolated organ system has been constructed to simulated the behavior of drug in the circulatory system of an acting organ or site. The model is developed on the following assumptions : The drug in the microcirculatory system cannot permeate the capilary walls. The capilary bed is modeled as a simple ideal plug flow system with and without radial concentration gradient. The mathematical model is developed from basic considerations of drug distribution with hemodynamical and pharmacokinetical meanings. It is considered that a nonmetabolic drug substance is injected into the arterial inflow site of an isolated organ at a constant rate. The concentration of the drug in the outflow site is mathematically expressed as a function of time.

• 한국전자거래학회지
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• 제5권2호
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• pp.81-99
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• 2000

Nowadays, many commercial ERP products, such as Oracle, SAP, and Baan, etc, are designed based on large-scaled companies. It is difficult for small and medium-size companies with weakness in budgets and resources(e.g., human, organization, technique, and so on) to use them as it was. So, new ERP system need to be provided for small and medium-size companies. In this paper, we model and provide a conceptual ERP model for small and medium-size companies by using "4＋1 View" architecture model of Unified Modeling Language(UML). The conceptual ERP model consists of five subsystems： Manufacturing, Sales, HumanResource and Payroll, Accounting, and Trading. Especially, we describe the conceptual ERP model focusing on "Manufacturing" subsystem by using several diagrams of UML. By using the conceptual ERP model, the ERP system′s developers of small and medium-size companies can obtain many benefits： improving the efficiency of software developing process and helping user requirements gathering and description of ERP system′s nonfunctional aspect as well as functional aspect.

• Wind and Structures
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• 제16권5호
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• pp.457-476
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• 2013

This paper presents theoretical background for a semi-empirical, mathematical model of critical vortex excitation of slender structures of compact cross-sections. The model can be applied to slender tower-like structures (chimneys, towers), and to slender elements of structures (masts, pylons, cables). Many empirical formulas describing across-wind load at vortex excitation depending on several flow parameters, Reynolds number range, structure geometry and lock-in phenomenon can be found in literature. The aim of this paper is to demonstrate mathematical background of the vortex excitation model for a theoretical case of the structure section. Extrapolation of the mathematical model for the application to real structures is also presented. Considerations are devoted to various cases of wind flow (steady and unsteady), ranges of Reynolds number and lateral vibrations of structures or their absence. Numerical implementation of the model with application to real structures is also proposed.