• Advances in aircraft and spacecraft science
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• 제4권3호
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• pp.219-235
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• 2017

The large container ships and fast patrol boats are complex marine structures. Therefore, their global mechanical behaviour has long been modeled mostly by refined beam theories. Important issues of cross section warping and bending-torsion coupling have been addressed by introducing special functions in these theories with inherent assumptions and thus compromising their robustness. The 3D solid Finite Element (FE) models, on the other hand, are accurate enough but pose high computational cost. In this work, different marine vessel structures have been analysed using the well-known Carrera Unified Formulation (CUF). According to CUF, the governing equations (and consequently the finite element arrays) are written in terms of fundamental nuclei that do not depend on the problem characteristics and the approximation order. Thus, refined models can be developed in an automatic manner. In the present work, a particular class of 1D CUF models that was initially devised for the analysis of aircraft structures has been employed for the analysis of marine structures. This class, which was called Component-Wise (CW), allows one to model complex 3D features, such as inclined hull walls, floors and girders in the form of components. Realistic ship geometries were used to demonstrate the efficacy of the CUF approach. With the same level of accuracy achieved, 1D CUF beam elements require far less number of Degrees of Freedom (DoFs) compared to a 3D solid FE solution.

• 영재교육연구
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• 제17권2호
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• pp.223-250
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• 2007

1992년 제6차 교육과정에서부터 도입된 초등학교 학교교육과정개발 정책은 단위 학교에서 영재들을 위한 교육과정을 개발하여 교육할 것을 주문하고 있다. 연구자는 그 활동을 돕기 위해 초등학교 영재들을 위한 학교교육과정 개발 모형을 구안하여 제시하였다. 본 모형은 VanTassel-Baska의 통합적 교육과정 모델(ICM: Integrated Curriculum Model)을 초등교육의 정체성에 비추어 재구성한 것으로서, ICM의 하위모델인 내용 모델, 과정 산출 모델, 인식론적 모델을 초등학교 $1{\sim}6$학년 아동들의 발달단계에 적절하게 그 적용 비중을 조절하는 것을 특징으로 하고 있다. 본 모형은 초등학교 영재 탤런트 풀을 대상으로 한 교육과정 개발의 일반 모형인 동시에, 영재 개개인의 특성과 요구에 따라서도 그 적용 비중이 달라질 수 있는 개인 모델로서도 기능할 수 있을 것이다.

• 시스템엔지니어링학술지
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• 제12권1호
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• pp.25-40
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• 2016

The Systems Engineering (SE) approach is characterized by the application of a structured engineering methodology for the design of a complex system or component. In this study, the SE methodology is used to design a nondestructive inspection system for Bottom Mounted Instrumentation (BMI) nozzles. We developed a system that enables nondestructive inspection of BMI nozzles during regular refueling outage without removing the reactor internals. A special ultrasonic (UT) probe is introduced to scan and detect cracks within the weld region of the nozzle. A 3D model of the inspection structure system was developed along with the reactor pressure vessel (RPV) and internals which permits a virtual 3D simulation of the operation to check the design concept and effectiveness of the system and to provide a good visualization of the system. This approach allows for a virtual walk through to verify the proposed BMI nozzle inspection system.

• Steel and Composite Structures
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• 제13권1호
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• pp.1-13
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• 2012

In this study, a new structural bracing system named 'Hat Knee Bracing' (HKB) is presented. In this structural system, a special form of diagonal braces, which is connected to the knee elements instead of beam-column joints, is investigated. The diagonal elements provide lateral stiffness during moderate earthquakes. However the knee elements, which is a fuse-like component, is designed to have one plastic joint in the knee elements for dissipation of the energy caused by strong earthquake. First, a suitable shape for brace and knee elements is proposed through elastic studying of the system and several practical parameters are established. Afterward, by developing applicable and highly accurate models in Drain-2DX, the inelastic behavior of the system is carefully considered. In addition, with inelastic study of the new bracing system and comparison with the prevalent Knee Bracing Frame system (KBF model) in nonlinear static and dynamic analysis, the seismic behavior of the new bracing system is reasonably evaluated.

• Steel and Composite Structures
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• 제37권2호
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• pp.151-173
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• 2020

This paper aims to probabilistically evaluate performance of two types of I beam to box column (IBBC) connection. With the objective of considering the variability of seismic loading demand, statistical features of the inter-story drift ratio corresponding to the second, fifth and eleventh story of a 12-story steel special moment resisting frames are extracted through incremental dynamic analysis at global collapse state. Variability of geometrical variables and material strength are also taken into account. All of these random variables are exported as inputs to a probabilistic finite element model which simulates the connection. At the end, cumulative distribution functions of local seismic demand for each component of each connection are provided using histogram sampling. Through a parametric study on probabilistic local seismic demand, the influence of some geometrical random variables on the performance of IBBC connections is demonstrated. Furthermore, the probabilistic study revealed that IBBC connection with widened flange has a better performance than the un-widened flange. Also, a design procedure is proposed for WF connections to achieve a same connection performance in different stories.

• 산업공학
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• 제5권1호
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• pp.35-46
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• 1992

This paper deals with analysis of material handling system efficiency of a heat-exchanger manufacturing line. This line is a typical flow shop type assembly line which consists of 10 steps of assembly stations. Each station have one or two workers who assemble and move components for the job, and no special transporters for component's movement. Therfore, all the workers are involoved in unnecessary moving activities which decrease overall production efficiencies of the line. To improve productivities, production outputs and worker's job performances for this assembly line, the several alternatives are considered such as installing new conveyor lines and automatic guided vehicle(AGV) system. Analyzing economic feasibilities and responses of the system alternatives, an experimental simulation model is built suing SIMAN Ver. 3. 5 simulation language with CINEMA package for animation of the process flow. Through this animation process a vivid picturial analysis could performed on the process flow.

• Industrial Engineering and Management Systems
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• 제14권2호
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• pp.196-209
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• 2015

Retail sales forecast is a special area of forecasting. Its unique characteristics call for unique data models and treatment, and unique forecasting processes. In this paper, we will address lessons learned and challenges encountered in retail sales forecast from a practical and technical perspective. In particular, starting with the data models of retail sales data, we proceed to address issues existing in estimating and processing each component in the data model. We will discuss how to estimate the multi-seasonal cycles in retail sales data, and the limitations of the existing methodologies. In addition, we will talk about the distinction between business events and forecast events, the methodologies used in event detection and event effect estimation, and the difficulties in compound event detection and effect estimation. For each of the issues and challenges, we will present our solution strategy. Some of the solution strategies can be generalized and could be helpful in solving similar forecast problems in different areas.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2013년도 추계학술대회 논문집
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• pp.585-588
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• 2013

Electric motor with reduction gear systems are being adopted recently as main propulsion on the special-purposed ships. These specialized ships or offshore vessels require higher power rating generators for propulsion and accommodation power supply. This study investigated the cause of exciter components failure in the view of excessive vibration, force or abnormal ship motion in service. Countermeasures are proposed to address the exciter component failure. A 1.4 MW class dual-fuel engine generator using rigid foundation for a LNG carrier was used as research model.

• 인지과학
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• 제11권2호
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• pp.69-78
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• 2000

상호활성화모형은 원래 영어의 단어우월효과를 설명하기 위해서 개발되었다. 한글에서도 영어에서의 단어우월효과와 비슷한 현상이 존재함이 알려져 있다. 즉, 한글의 자소가 글자의 한 구성요소로 나타났을때가 자소 단독으로 나타났을 때보다 더 잘 인식된다는 것이다. 우리의 한글에서의 글자우월효과를 설명하기 위해서 기존의 상호활성화모형을 수정하였다. 그러나 한글에서의 글자우월효과는 글자의 유형에 따라 그 정도가 다양하게 나타난다는 사실이 보고된 바 있다. 특히 글자내에서 한 자소가 다른 자소들 사이에 둘러 쌓여 있을 때는 해당 자소가 글자의 맥락에 있다고 하더라도 인지하기 어렵다는 사실이 알려져 있다. 한글의 경우, 글자가 각 구성요소(자소)의 이차원적 구성이기 때문에 이런 특이한 현상이 발생한다고 추측해 볼 수 있다. 우리는 글자의 이차원적 형태에 중점을 두어 계산되어진 입력 자극의 가중치를 기존의 상호활성화모형에 도입하여 이러한 현상을 설명할 수 있었다.

• Steel and Composite Structures
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• 제16권4호
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• pp.417-436
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• 2014

During an earthquake, steel frame columns can be subjected to high axial forces combined with inelastic rotation demand resulting from story drift. Generally, the whole beam or component can be represented with one element. In elasto-plastic analysis, subdivision is necessary if the plastic deformation occurs within two ends of beams. If effects of the joint panel are necessarily considered in the analysis, the joint panel should be represented with an independent element. It is a special element to represent the shear deformation of the joint panel in the beam-column connection zone. Several analytical models for panel zone (PZ) behavior exist, in terms of shear force-shear distortion relationships. Among these models, the Krawinkler PZ model is the most popular one which is used in the AISC code. Some studies have pointed out that Krawinkler's model gives good results for the range of thin to medium column flanges thickness. This paper, introduces a new model to estimate the response of shear force-shear distortion for the PZ including column axial force. The model is applicable to both thin and thick column flange. To achieve an appropriate PZ mathematical model first, the effects of PZ strength and stiffness on connection response are parametrically studied using finite element models. More than one thousand and four-hundred beam-column connections are included in the parametric study, with varied parameters; then based on analytical results a simple mathematical model is presented. A comparison between the results of proposed method herein with FE analyses shows the average error especially in thick column flange is significantly reduced which demonstrates the accuracy, efficiency, and simplicity of the proposed model.