• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 2002년도 춘계공동학술대회
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• pp.306-311
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• 2002

This paper propose a personalized defection detection and prevention procedure based on the observation that potential defectors have tendency to take a couple of months or weeks. For this purpose, possible states of customer behavior are determined from past behavior data using SOM (Self-Organizing Map). For the evaluation of the proposed procedure, a case study has been conducted for a Korean online game site. The result demonstestes that the proposed procedure can assist defection prevention effectively and detect potential defectors without deterioration of prediction accuracy comparison to prediction by MLP. Our procedure can be applied to various service industries that can capture fluent customer behavior data such as telecommunications, internet access services, and content services, too.

• Coupled systems mechanics
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• 제8권2호
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• pp.111-127
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• 2019

In this paper, we present a 2D multi-scale coupling computation procedure for localized failure. When modeling the behavior of a structure by a multi-scale method, the macro-scale is used to describe the homogenized response of the structure, and the micro-scale to describe the details of the behavior on the smaller scale of the material where some inelastic mechanisms, like damage or plasticity, can be defined. The micro-scale mesh is defined for each multi-scale element in a way to fit entirely inside it. The two scales are coupled by imposing the constraint on the displacement field over their interface. An embedded discontinuity is implemented in the macro-scale element to capture the softening behavior happening on the micro-scale. The computation is performed using the operator split solution procedure on both scales.

• Coupled systems mechanics
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• 제7권5호
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• pp.555-581
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• 2018

The moment-resistant steel frames are frequently used as a load-bearing structure of buildings. Global response of a moment-resistant frame structure strongly depends on connections behavior, which can significantly influence the response and load-bearing capacity of a steel frame structure. The analysis of a steel frame with included joints behavior is the main focus of this work. In particular, we analyze the behavior of two connection types through experimental tests, and we propose numerical beam model capable of representing connection behavior. The six experimental tests, under monotonic and cyclic loading, are performed for two different types of structural connections: end plate connection with an extended plate and end plate connection. The proposed damage-plasticity model of Reissner beam is able to capture both hardening and softening response under monotonic and cyclic loading. This model has 18 constitutive parameters, whose identification requires an elaborate procedure, which we illustrate in this work. We also present appropriate loading program and arrangement of measuring equipment, which is crucial for successful identification of constitutive parameters. Finally, throughout several practical examples, we illustrate that the steel structure connections are very important for correct prediction of the global steel frame structure response.

• The Journal of Asian Finance, Economics and Business
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• 제8권3호
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• pp.331-339
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• 2021

The youths are characterized by their reckless and ambitious behavior. They exhibit a strong tendency to make risky decisions that may jeopardize their future. These qualities are also in line with their experience-seeking behavior. As young entrepreneurs aim high in profit-seeking activities, their ethical stance may be compromised. Moreover, their money profile increases at an accelerated pace, leading them to love money even more. Quantitatively, this study was the first to investigate the behavior of young entrepreneurs in terms of their love of money, religiosity, and ethical perceptions by adopting the hadith perspective in Islamic tradition by developing the scales of all constructs. The respondents were 261 members of the Indonesian Young Entrepreneur Association in Sulawesi Selatan, Indonesia. This study also examined gender as the moderating variable. This study found that the love of money affects ethical perception negatively; on the other hand, religiosity positively affected ethics. Gender is found to moderate religiosity, but not love of money. These results signify the harmful impact of loving money too much on young entrepreneurs' ethics; furthermore, the scales developed from hadith revelation were able to capture the empirical findings significantly.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2009년 춘계학술대회논문집
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• pp.155-158
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• 2009

We developed a numerical method to analyze the contact-line problems, incorporating a dynamic contact angle model. We used level set method to capture free surface. The method is applied to the analysis of dynamic behavior of a droplet in DC electrowetting. The result is compared with an experimental data and result of perturbation method.

• 한국CDE학회논문집
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• 제13권3호
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• pp.209-216
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• 2008

This paper presents a novel approach to design evaluation of portable consumer electronic (PCE) products using augmented reality (AR) based tangible interaction and functional behavior simulation. In the approach, the realistic visualization is acquired by overlaying the rendered image of a PCE product on the real world environment in real-time using computer vision based augmented reality. For tangible user interaction in an AR environment, the user creates input events by touching specified regions of the product-type tangible object with the pointer-type tangible object. For functional behavior simulation, we adopt state transition methodology to capture the functional behavior of the product into a markup language-based information model, and build a finite state machine (FSM) to controls the transition between states of the product based on the information model. The FSM is combined with AR-based tangible objects whose operation in the AR environment facilitates the realistic visualization and functional simulation of the product, and thus realizes faster product design and development. Based on the proposed approach, a product design evaluation system has been developed and applied for the design evaluation of various PCE products with highly encouraging feedbacks from users.

• 한국소음진동공학회논문집
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• 제15권1호
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• pp.29-38
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• 2005

The track pull-in behavior analysis in an optical disk drive (ODD) using plane phase and the evaluations for effecting parameters of it are discussed. Track pull-in, track capture procedure to do track following control, is a key factor to increase data transfer rate. First, the relative velocity between the beam spot of an optical pick-up and the target track of an optical disk is analyzed during the track pull-in procedure. In this process, it is showed that the track error signal has nonlinear characteristics which are depending on the time. Second, Runge-Kutta method to solve the nonlinear equation is applied to find the track pull-in behavior, and some optimal parameters to get stable and fast pull-in condition are obtained. Then, the phase plane analysis for track pull-in procedure is presented. Finally, some comments for the simulated results are discussed briefly.

• Structural Engineering and Mechanics
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• 제31권5호
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• pp.545-566
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• 2009

Bridge columns are subjected to combined actions of axial force, shear force and bending moment during earthquakes, caused by spatially-complex earthquake motions, features of structural configurations and the interaction between input and response characteristics. Combined actions can have significant effects on the force and deformation capacity of RC columns, resulting in unexpected large deformations and extensive damage that in turn influences the performance of bridges as vital components of transportation systems. This paper evaluates the seismic response of three prototype reinforced concrete bridges using comprehensive numerical models that are capable of simulating the complex soil-structural interaction effects and nonlinear behavior of columns. An analytical approach that can capture the shear-flexural interacting behavior is developed to model the realistic nonlinear behavior of RC columns, including the pinching behavior, strength deterioration and stiffness softening due to combined actions of shear force, axial force and bending moment. Seismic response analyses were conducted on the prototype bridges under suites of ground motions. Response quantities of bridges (e.g., drift, acceleration, section force and section moment etc.) are compared and evaluated to identify the effects of vertical motion, structural characteristics and the shear-flexural interaction on seismic demand of bridges.

• Structural Engineering and Mechanics
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• 제42권1호
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• pp.73-93
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• 2012

With an active structural involvement in spiral case structure (SCS) that is always the design and research focus of hydroelectric power plant (HPP), the compressible membrane sandwiched between steel spiral case and surrounding reinforced concrete was often assumed to be linear elastic material in conventional design analysis of SCS. Unfortunately considerable previous studies have proved that the foam material serving as membrane exhibits essentially nonlinear mechanical behavior. In order to clarify the effect of membrane (foam) material's nonlinear stress-strain behavior on SCS, this work performed a case study on SCS with a compressible membrane using the ABAQUS code after a sound calibration of the employed constitutive model describing foam material. In view of the successful capture of fitted stress-strain curve of test by the FEM program, we recommend an application and dissemination of the simulation technique employed in this work for membrane material description to structural designers of SCS. Even more important, the case study argues that taking into account the nonlinear stress-strain response of membrane material in loading process is definitely essential. However, we hold it unnecessary to consider the membrane material's hysteresis and additionally, employment of nonlinear elastic model for membrane material description is adequate to the structural design of SCS. Understanding and accepting these concepts will help to analyze and predict the structural performance of SCS more accurately in design effort.

• 한국지반공학회논문집
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• 제19권3호
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• pp.15-22
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• 2003

지반의 실제 거동을 보다 정확하게 표현하기 위한, 응력의 비등방성 및 시간의존적(time-dependent) 거동의 적절한 묘사는 특히 점성토의 응력-변형률 관계를 나타내는 구성관계식에 있어서 중요한 관심사이다. 본 연구에서는 적은 모델정수로 응력의 비등방성을 묘사할 수 있는 소성 구성관계식과, 대표적 시간의존적 거동인 변형률 속도 효과를 간편하게 표현할 수 있는 변형률속도 의존적 구성관계식을 일반 점성이론에 입각하여 조합하였다. 결론적으로 제안된 하나의 비등방성 변형률속도 의존적 구성관계식은 비교적 모델정수가 적고, 변형률속도가 바뀔 때마다 모델정수 값을 다시 결정할 필요가 없다는 장점이 있다. 제안된 구성모델은 인위적으로 제작된 균질한 시료를 이용한 실내시험을 통하여 검증되었으며, 상세 거동 및 문제점을 고찰하였다.