• International Journal of Fluid Machinery and Systems
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• 제10권3호
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• pp.240-253
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• 2017

Latin hypercube sampling is widely used design-of-experiment technique to select design points for simulation which are then used to construct a surrogate model. The exploration/exploitation properties of surrogate models depend on the size and distribution of design points in the chosen design space. The present study aimed at evaluating the performance characteristics of various surrogate models depending on the Latin hypercube sampling (LHS) procedure (sample size and spatial distribution) for a diverse set of optimization problems. The analysis was carried out for two types of problems: (1) thermal-fluid design problems (optimizations of convergent-divergent micromixer coupled with pulsatile flow and boot-shaped ribs), and (2) analytical test functions (six-hump camel back, Branin-Hoo, Hartman 3, and Hartman 6 functions). The three surrogate models, namely, response surface approximation, Kriging, and radial basis neural networks were tested. The important findings are illustrated using Box-plots. The surrogate models were analyzed in terms of global exploration (accuracy over the domain space) and local exploitation (ease of finding the global optimum point). Radial basis neural networks showed the best overall performance in global exploration characteristics as well as tendency to find the approximate optimal solution for the majority of tested problems. To build a surrogate model, it is recommended to use an initial sample size equal to 15 times the number of design variables. The study will provide useful guidelines on the effect of initial sample size and distribution on surrogate construction and subsequent optimization using LHS sampling plan.

• 한국의류산업학회지
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• 제23권5호
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• pp.576-585
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• 2021

This study sought to identify the types of fashion brands preferred by tourists based on the shopping values that they pursue through purchases at tourist destinations and to verify the effects of these values on their satisfaction. To obtain a representative sample of South Korea's tourist shoppers, a survey was conducted among 300 subjects involving adult men and women in their twenties to sixties. Structural equation modeling analyses were performed on the collected data using SPSS and AMOS. The effects of tourist shopping values on brand attitudes were verified by dividing tourist shopping values into social, epistemic, and functional values and dividing brand attitudes into attitudes toward fashion global and local brands. Additionally, this work intended to ascertain the moderating effect of cosmopolitanism on tourist shopping behaviors. The analysis results reveal that a high level of epistemic value as perceived by tourists during shopping resulted in a corresponding high level of preference for local fashion brands. Furthermore, a high level of social value as perceived by tourists led to a high level of preference toward global fashion brands. Contrastingly, functional value influenced both local and global brands. As a result of the moderating effect, in the group with high cosmopolitanism tendency, the effect of epistemic value was not significant, but the low group significantly affected brand attitude based on the social and epistemic value. Given its academic and practical implications, the present study is likely to broaden the understanding of tourist shopping and facilitate future research on that phenomenon.

• 산업경영시스템학회지
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• 제46권4호
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• pp.15-31
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• 2023

In this study, we propose a novel approach to analyze big data related to patents in the field of smart factories, utilizing the Latent Dirichlet Allocation (LDA) topic modeling method and the generative artificial intelligence technology, ChatGPT. Our method includes extracting valuable insights from a large data-set of associated patents using LDA to identify latent topics and their corresponding patent documents. Additionally, we validate the suitability of the topics generated using generative AI technology and review the results with domain experts. We also employ the powerful big data analysis tool, KNIME, to preprocess and visualize the patent data, facilitating a better understanding of the global patent landscape and enabling a comparative analysis with the domestic patent environment. In order to explore quantitative and qualitative comparative advantages at this juncture, we have selected six indicators for conducting a quantitative analysis. Consequently, our approach allows us to explore the distinctive characteristics and investment directions of individual countries in the context of research and development and commercialization, based on a global-scale patent analysis in the field of smart factories. We anticipate that our findings, based on the analysis of global patent data in the field of smart factories, will serve as vital guidance for determining individual countries' directions in research and development investment. Furthermore, we propose a novel utilization of GhatGPT as a tool for validating the suitability of selected topics for policy makers who must choose topics across various scientific and technological domains.

• Earthquakes and Structures
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• 제26권4호
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• pp.261-267
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• 2024

With the increase in the exploitation depth of offshore oil and gas, it is possible to control the global buckling of deep-sea pipelines by the snake lay method. Previous studies mainly focused on the analysis of critical buckling force and critical temperature of pipelines under the snake-like laying method, and pipelines often suffer structural failure due to seismic disasters during operation. Therefore, seismic action is a necessary factor in the design and analysis of submarine pipelines. In this paper, the seismic action of steel pipes in the operation stage after global buckling has occurred under the active control method is analyzed. Firstly, we have established a simplified finite element model for the entire process cycle and found that this modeling method is accurate and efficient, solving the problem of difficult convergence of seismic wave and soil coupling in previous solid analysis, and improving the efficiency of calculations. Secondly, through parameter analysis, it was found that under seismic action, the pipe diameter mainly affects the stress amplitude of the pipeline. When the pipe wall thickness increases from 0.05 m to 0.09 m, the critical buckling force increases by 150%, and the maximum axial stress decreases by 56%. In the pipe soil interaction, the greater the soil viscosity, the greater the pipe soil interaction force, the greater the soil constraint on the pipeline, and the safer the pipeline. Finally, the pipeline failure determination formula was obtained through dimensionless analysis and verified, and it was found that the formula was accurate.

• Steel and Composite Structures
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• 제21권1호
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• pp.217-247
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• 2016

Five extended cylindrical reticulated shells are proposed by changing distribution rule of diagonal rods based on three fundamental types. Modeling programs for fundamental types and extended types of cylindrical reticulated shell are compiled by using the ANSYS Parametric Design Language (APDL). On this basis, conditional formulas are derived when the grid shape of cylindrical reticulated shells is equilateral triangle. Internal force analysis of cylindrical reticulated shells is carried out. The variation and distribution regularities of maximum displacement and stress are studied. A shape optimization program is proposed by adopting the sequence two-stage algorithm (RDQA) in FORTRAN environment based on the characteristics of cylindrical reticulated shells and the ideas of discrete variable optimization design. Shape optimization is achieved by considering the objective function of the minimum total steel consumption, global and locality constraints. The shape optimization for three fundamental types and five extended types is calculated with the span of 30 m~80 m and rise-span ratio of 1/7~1/3. The variations of the total steel consumption along with the span and rise-span ratio are analyzed with contrast to the results of shape optimization. The optimal combination of main design parameters for five extended cylindrical reticulated shells is investigated. The total steel consumption affected by distribution rule of diagonal rods is discussed. The results show that: (1) Parametric modeling method is simple, efficient and practical, which can quickly generate different types of cylindrical reticulated shells. (2) The mechanical properties of five extended cylindrical reticulated shells are better than their fundamental types. (3) The total steel consumption of cylindrical reticulated shells is optimized to be the least when rise-span ratio is 1/6. (4) The extended type of three-way grid cylindrical reticulated shell should be preferentially adopted in practical engineering. (5) The grid shape of reticulated shells should be designed to equilateral triangle as much as possible because of its reasonable stress and the lowest total steel consumption.

• 제어로봇시스템학회논문지
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• 제19권5호
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• pp.481-487
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• 2013

This paper presents an FIR (Finite Impulse Response) fixed-interval smoothing filter for fast and exact estimating state variables of a discrete nonlinear system with modeling uncertainty. Conventional IIR (Infinite Impulse Response) filter and smoothing filter can estimate state variables of a system with an exact model when the system is observable. When there is an uncertainty in the system model, however, conventional IIR filter and smoothing filter may cause large errors because the filters cannot estimate the state variables corresponding to the uncertain model exactly. To solve this problem, FIR filters that have fast estimation properties and have robustness to the modeling uncertainty have been developed. However, there is time-delay estimation phenomenon in the FIR filter. The FIR smoothing filter proposed in this paper makes up for the drawbacks of the IIR filter, IIR smoothing filter, and FIR filter. Therefore, the FIR smoothing filter has good estimation performance irrespective of modeling uncertainty. The proposed FIR smoothing filter is applied to the integrated navigation system composed of a magnetic compass based DR (Dead Reckoning) and a GPS (Global Positioning System) receiver. Even when the magnetic compass error that changes largely as the surrounding magnetic field is modeled as a random constant, it is shown that the FIR smoothing filter can estimate the varying magnetic compass error fast and exactly with simulation results.

• Spatial Information Research
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• 제11권3호
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• pp.227-240
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• 2003

본 연구는 2D 기반의 동적 공간모형(dynamic spatial landscape models)을 통해 지표 변화 과정을 이해하고 예측할 수 있는 방법론을 제시하는데 그 초점을 두고 있다. 동적 공간모형 에 기반한 연구는 크게 지표의 공간 패턴에 대한 모형화와 변화 과정에 관한 모형화 및 모의로 구성되어 있는데 지표 변화와 관련된 규칙은 변화 원인과 그 과정에 따라 다르게 정의될 수 있다. 이때 지표 패턴의 이질성은 변화와 밀접한 관계를 가지고 있기 때문에 연구 지역의 GIS 맵으로부터 공간 패턴의 특성을 모형화 하여 이를 기반으로 변화에 관한 동적 공간 모형이 적용되어야 한다. 본 논문에서는 이를 위한 모형기반 접근법이 설명되어 있고 자연 화재로 인한 지표 변화 과정에 적용되어 동적 공간 모형이 개발되었다.

• 한국컴퓨터산업학회논문지
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• 제5권8호
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• pp.791-800
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• 2004

e-Commerce와 가상 조직의 확산으로 e-비즈니스 활성화에 따른 기업 환경의 변화로 인해 기업간의 협업이 증가하면서 수많은 비즈니스 프로세스들의 범위는 기업 내부가 아닌 기업과 기업간으로 확대되었다. 기업간 거래는 서로 다른 시스템과 서로 다른 비즈니스 프로세스 모델을 가지고 있으므로 상호운용성에 대한 문제점이 존재하기 때문에 기업간 협업을 위한 비즈니스 프로세스 모델을 위해 표준화된 스키마가 제공되어야 한다. ebXML은 그 규모나 위치와 관계없이 각 기업들로 전 세계 전자상거래 시장을 형성하며 XML 기반 메시지 교환을 통하여 각 비즈니스들을 실행한다. 따라서 ebXML을 기반으로 거래 기업간의 비즈니스 프로세스 자동화를 목적으로 e-비즈니스를 위한 거래 기업간 협업 모델링 시스템을 설계 및 구현한다.

• 정보처리학회논문지D
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• 제8D권4호
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• pp.401-408
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• 2001

객체지향 모델은 구조적 모델에 비해 모듈성, 재사용성, 유지보수성, 확장성 등의 장점을 제공한다. 이러한 이유로 객체지향 소프트웨어 개발 방법들을 정보 시스템 개발에 광범위하게 적용되고 있다. 그러나 현재의 객체지향 소프트웨어 개발 방법들은 목적 소프트웨어 시스템의 객체지향 모델링을 지원할 뿐, 방법론 그 자체는 구조적 및 절차적 체계를 기반으로 하고 있다. 본 논문에서는 객체지향 소프트웨어 개발 방법론을 객체지향적으로 모델링한 OMOS(Object-oriented software development Method for Object-oriented software System)를 제시한다. OMOS에서는 개발 산출물과 관련된 활동이 객체로써 모델링 되며, 개발 생명주기 프로세스가 객체간의 상호작용으로 모델링 된다. 소프트웨어 개발 방법론의 객체지향적 모델링은 방법론 자체의 재사용성, 유연성, 확장성, 유지보수성의 용이성 등의 장점을 제공한다.

• 한국전자거래학회지
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• 제14권4호
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• pp.299-313
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• 2009

국내 물류 환경이 점차 글로벌 물류로 변화됨에 따라 업무 처리에 다양한 물류 주체들이 참여하고, 화물은 컨테이너에 포장되어 여러 단계를 거쳐 수화인에게 전달된다. 또한 화물 배송 과정 중간에 화물이 손상되거나 유실될 가능성이 크다. 이 때문에 송화인과 수화인을 비롯한 여러 물류 주체들에게 있어서 수출입 화물에 대한 흐름의 파악은 매우 중요한 문제가 되고 있다. 하지만 현실적으로는 여러 가지 문제로 인해 화물이 전달되는 과정을 일관되게 추적하는 것은 매우 어려운 실정이다. 그 원인은 화물과 정보 흐름이 일치하지 않는다는 것과 업무자동화 측면에서 표준 정보 및 프로세스가 아니어서 물류 주체 간 데이터 연동이 어렵다는 것이다. 이에 본 논문에서는 화물 추적 업무에 있어서 단일화되고 통합된 비즈니스 협업을 위한 비즈니스 프로세스를 정의하고, 그 결과를 이용해 표준 데이터를 정의하고자 한다. 개발된 프로세스 모델과 표준 데이터는 국제적으로 상호운용성을 지원할 수 있도록 하였다.