• 산업경영시스템학회지
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• 제41권4호
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• pp.213-219
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• 2018

Mechanical components are to be produced with accurate dimensions in order to function properly in assemblies of a machine. Once designs of mechanical components are created, designers examine the designs by adopting many known experimental methods. A primary test method includes stress and strain evaluation of structural parts. In addition, fatigue test and vibration analysis are an important test method for mechanical components. Real experiments at a laboratory are established when products are manufactured. Since design changes should be done before producing the designs in factories, rapid modifications for new designs are required in production industries. FEM simulation is a proper choice for a design evaluation with speed at a detail stage in design process. This research focuses modeling and mechanical simulation of a mechanical component in order to ensure structural safety. In this paper, a universal joint, being used in driving axels of vehicles, is studied as a target component. A design model is created and tested in some ways by using commercial software of FEM. The designed component is being twisted to transmit heavy power and thus, torsional stress should be under strengths of the component's material. The next is fatigue analysis to convince fatigue cycles to be within the endurance limit of the material. Another test is a vibration analysis for rotational components. This research draws final conclusions from these test analyses and recommends whether the designed model is under safety condition in terms of mechanical structure.

• 패션비즈니스
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• 제25권5호
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• pp.73-87
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• 2021

This study aimed to develop fashion designs by applying the PO (Provocative Operation) method as a 3D virtual clothing program and to derive the PO application method in fashion design. The first T-shirt design was presented as an existing thinking method, and the second design was developed by applying escape, reversal, exaggeration, distortion, and hopeful thinking techniques, which are techniques for 'provocation' of the PO method, to the first design. Thus, 18 T-shirt designs were developed as 3D virtual clothing, with 3 sets of 6 designs, including the 1st and 2nd designs. The method of using the 'provocation' techniques of the PO method in the development of fashion design derived from this was as follows. First, the 'escape' technique was designed in such a way that a part of the detail or structure was deleted, or a part of the structure or expression element of another item was applied. Second, the 'inversion' technique was expressed by inverting the position or shape of a detail or structure up, down, left, and right; fitting the structural detail or reversing the shape; or converting the structure and form. Third, the 'exaggeration' technique exaggerated the size, length, and volume of a structure's form or detail. Fourth, the 'distortion' technique was expressed as a distortion of lines or shapes or a visual distortion using the Trompe l'oeil technique. Fifth, the 'hopeful thinking' technique was developed and expressed from the idea of an hypothetical 'if' it was absurd, irrational, and unrealistic.

• 한국전산구조공학회논문집
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• 제35권1호
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• pp.45-55
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• 2022

현 설계기준에서 제시한 단부횡보강 상세는 시공성과 생산품질이 현저히 떨어지므로 내진성능과 시공성을 확보할 수 있는 RC 구조벽체의 단부횡보강 상세 개발이 필요하다. 최근 선재 제작기술의 발전으로 다양한 선조립철근의 제작이 가능해지고 있으며 특히 다양한 연속횡보강 철근 상세의 제작이 가능하게 되었다. 본 연구에서는 사각 연속횡보강 선조립철근 단부횡보강 상세를 적용한 RC 구조벽체의 모멘트-곡률 관계에 대한 분석을 진행하였다. 비선형 단면해석에 의하면 사각 연속횡보강의 상세를 적용한 RC 구조벽체는 사각 연속횡보강 영역의 면적이 증가할수록 내진성능을 확보할 수 있다. 이러한 연구결과에 근거하여 사각 연속횡보강 선조립 철근의 상세 적용시, 단부횡보강 영역의 면적만큼 사각 연속횡보강 영역의 면적을 확보해야 한다.

• 한국산학기술학회논문지
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• 제18권6호
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• pp.728-735
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• 2017

디지털 디바이스가 범용적으로 보급되면서, 영상을 획득하는 과정에서 다량의 부가적 백색 잡음 노이즈(additive white Gaussian noise, AWGN)가 발생하고 있다. 대부분 알려져 있는 대표적인 디노이징 기법들은 노이즈를 제거하는 것에 초점을 맞추고 있어, 영상정보를 포함하는 디테일 성분들이 노이즈를 제거가 되는 과정에서 비례적으로 없어지게 된다. 그러므로, 제안하는 알고리즘은 영상 디테일을 보존하면서 효과적으로 노이즈를 제거하는 방법을 제시하고자 한다. 제안하는 방법에서는, 노이즈의 랜덤성을 이용하여 엣지 강도 및 엣지 연결성을 이용하여 의미 있는 디테일 성분을 분리하는 것을 목적으로 한다. 결과적으로, 노이즈 수준이 높아져도, 제안하는 방법은 연결된 디테일성분을 효과적으로 추출하기 때문에 타 벤치마크 방법에 비해 나은 디노이징 결과를 보여준다. 또한, 실험결과에서 보듯이, 제안하는 방법은 다양한 노이즈 수준에서도 타 벤치마크 방법들에 비교하여 제안하는 방법은 SSIM(structural similarity index), PSNR(peak signal-to-noise ratio)측면에서 각각 우수한 수치를 보여주었다. 높은 수치의 SSIM의 결과로 알 수 있듯이, 결과 영상들이 인간의 시각인지체계(human visual system, HVS)를 반영하고 있는 것을 확증해 주고 있다.

• 한국전산구조공학회논문집
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• 제36권4호
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• pp.265-272
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• 2023

본 논문에서는 철근콘크리트 골조를 주 대상으로 하여 설계 및 시공 전 과정에 대한 디지털전환 전략과 기술개발에 대하여 기술하였다. 건설 현장의 BIM 도입과 디지털 전환이 기대만큼 활성화되지 않는 중요원인을, 모델링 솔루션을 이용한 설계모델 구축의 생산성과 후속 프로세스에서 요구하는 필요충분한 정보를 제공하는 완성도에서 찾을 수 있다. 특히 방대한 양의 상세설계 모델 구축에 소요되는 과도한 노력과 단순반복 작업 과정에서 발생할 수 있는 인적 오류에 의한 정확성 결여는 건축 프로젝트의 디지털 전환 실현을 위하여 해결되어야 할 기술적 장벽이다. 이러한 배경에서 본 연구에서는 철근콘크리트 골조 공사를 대상으로 디지털전환과 현장적용을 목표로 이를 실현하기 위한 개념적 전략 수립과 기술개발 사례에 대하여 기술하였다. 이를 위하여 시공 단계에서 필요한 상세설계 정보를 포함하는 건물골조 상세설계 BIM 모델링 기술개발 결과를 제시하고, 특히 배근상세설계 등 반복성이 높은 상세설계 업무를 자동화하여 기본설계 2D CAD 도면에서 출발하여 3D BIM 모델을 구축하고 상세설계 BIM 모델을 생성한 후 이를 활용하기 위한 플랫폼 구축까지의 프로세스를 완성하였다. 제시된 자동화기술과 현장관리 플랫폼에 의한 프로세스는 CAD 도면 기반의 전통적 건설프로세스를 대체하기 위해 요구되는 업무 생산성과 기술적 정보 완성도를 확보한 것으로 평가되었다.

• Computers and Concrete
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• 제16권4호
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• pp.503-529
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• 2015

Traditionally, multi-story buildings are designed to provide stiffer structural support to withstand lateral earthquake loading. Introducing flexible elements at the base of a structure and providing sufficient damping is an alternative way to mitigate seismic hazards. These features can be achieved with a device known as an isolator. This paper covers the design of base isolators for multi-story buildings in medium-risk seismicity regions and evaluates the structural responses of such isolators. The well-known tower building for police personnel built in Dhaka, Bangladesh by the Public Works Department (PWD) has been used as a case study to justify the viability of incorporating base isolators. The objective of this research was to establish a simplified model of the building that can be effectively used for dynamic analysis, to evaluate the structural status, and to suggest an alternative option to handle the lateral seismic load. A finite element model was incorporated to understand the structural responses. Rubber-steel bearing (RSB) isolators such as Lead rubber bearing (LRB) and high damping rubber bearing (HDRB) were used in the model to insert an isolator link element in the structural base. The nonlinearities of rubber-steel bearings were considered in detail. Linear static, linear dynamic, and nonlinear dynamic analyses were performed for both fixed-based (FB) and base isolated (BI) buildings considering the earthquake accelerograms, histories, and response spectra of the geological sites. Both the time-domain and frequency-domain approaches were used for dynamic solutions. The results indicated that for existing multi-story buildings, RSB diminishes the muscular amount of structural response compared to conventional non-isolated structures. The device also allows for higher horizontal displacement and greater structural flexibility. The suggested isolation technique is able to mitigate the structural hazard under even strong earthquake vulnerability.

• Smart Structures and Systems
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• 제31권4호
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• pp.311-323
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• 2023

Ever since ancient times, earthquakes have been a major threat to the civil infrastructures and the safety of human beings. The majority of casualties in earthquake disasters are caused by the damaged civil infrastructures but not by the earthquake itself. Therefore, the efficient and accurate post-earthquake assessment of the conditions of structural damage has been an urgent need for human society. Traditional ways for post-earthquake structural assessment rely heavily on field investigation by experienced experts, yet, it is inevitably subjective and inefficient. Structural response data are also applied to assess the damage; however, it requires mounted sensor networks in advance and it is not intuitional. As many types of damaged states of structures are visible, computer vision-based post-earthquake structural assessment has attracted great attention among the engineers and scholars. With the development of image acquisition sensors, computing resources and deep learning algorithms, deep learning-based post-earthquake structural assessment has gradually shown potential in dealing with image acquisition and processing tasks. This paper comprehensively reviews the state-of-the-art studies of deep learning-based post-earthquake structural assessment in recent years. The conventional way of image processing and machine learning-based structural assessment are presented briefly. The workflow of the methodology for computer vision and deep learning-based post-earthquake structural assessment was introduced. Then, applications of assessment for multiple civil infrastructures are presented in detail. Finally, the challenges of current studies are summarized for reference in future works to improve the efficiency, robustness and accuracy in this field.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2005년도 춘계 학술발표회 논문집
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• pp.351-358
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• 2005

Many methods have been developed and are in use for structural size optimization problems, In which the cross-sectional areas or sizing variables are usually assumed to be continuous. In most practical structural engineering design problems, however, the design variables are discrete. This paper proposes an efficient optimization method for structures with discrete-sized variables based on the harmony search (HS) meta-heuristic algorithm. The recently developed HS algorithm was conceptualized using the musical process of searching for a perfect state of harmony. It uses a stochastic random search instead of a gradient search so that derivative information is unnecessary In this paper, a discrete search strategy using the HS algorithm is presented in detail and its effectiveness and robustness, as compared to current discrete optimization methods, are demonstrated through a standard truss example. The numerical results reveal that the proposed method is a powerful search and design optimization tool for structures with discrete-sized members, and may yield better solutions than those obtained using current method.

• 한국소음진동공학회논문집
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• 제23권4호
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• pp.308-314
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• 2013

The vibration and stress analysis program of comprehensive vibration assessment program(CVAP) is to theoretically verify the structural integrity of reactor vessel internals(RVI) and to provide the basis for selecting the locations monitored in measurement and inspection programs. This paper covers the applicability of the vibration and stress analysis method of APR1400 RVI CVAP. The analysis method was developed to use 3-dimensional detail hydraulic and structural models with ANSYS and CFX. To assess the method, the hydraulic loads and structural reponses of OPR1000 were predicted and compared with the measured data in the OPR1000 RVI CVAP. The results predicted with this method were close to the measured values considerably. Therefore, the analysis method was developed properly.

• Structural Engineering and Mechanics
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• 제56권4호
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• pp.625-648
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• 2015

Modern super-tall buildings are more sensitive to strong winds. The evaluation of wind loads for the design of these buildings is of primary importance. A direct monitoring of wind forces acting on super-tall structures is quite difficult to be realized. Indirect measurements interpreted by inverse techniques are therefore favourable since dynamic response measurements are easier to be carried out. To this end, a Kalman filtering based inverse approach is developed in this study so as to estimate the wind loads on super-tall buildings based on limited structural responses. The optimum solution of Kalman filter gain by solving the Riccati equation is used to update the identification accuracy of external loads. The feasibility of the developed estimation method is investigated through the wind tunnel test of a typical super-tall building by using a Synchronous Multi-Pressure Scanning System. The effects of crucial factors such as the type of wind-induced response, the covariance matrix of noise, errors of structural modal parameters and levels of noise involved in the measurements on the wind load estimations are examined through detailed parametric study. The effects of the number of vibration modes on the identification quality are studied and discussed in detail. The made observations indicate that the proposed inverse approach is an effective tool for predicting the wind loads on super-tall buildings.