• International Journal of Naval Architecture and Ocean Engineering
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• 제11권1호
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• pp.553-571
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• 2019

Geometric variation including welding distortion accumulates as many parts are joined together, ultimately affecting the final product. This variation is then subjected to correction, which requires considerable effort, time, and cost. This variation can be categorized as in-plane/out-of-plane variation. To date, studies on variation simulation have largely focused on the out-of-plane variation, however the variation generated in the in-plane direction requires more time and efforts to correct afterwards. This research aims to construct a variation simulation model considering both the in-plane and out-of-plane variations. A geometric analysis was performed to derive an equation that reflects the coupling effect of the out-of-plane variation on the in-plane variation. The proposed model is validated with case study analysis and the results shows that good fidelity in predicting and diagnosing the in-plane variation during the block assembly process considering welding distortion.

• 대한지리학회지
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• 제48권3호
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• pp.387-401
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• 2013

우리나라 선거구 획정은 인구의 증감이나 행정구역의 변경뿐만 아니라 지극히 정치적인 의도와 목적을 가지고 이루어져 선거결과에 중대한 영향을 미친다. 이 논문은 선거구 구획의 실행 측면에 초점을 맞추어 선거구 구획을 위한 대안적 방법을 제시하는 데 초점을 맞추고 있다. 즉 과정에서 자의성이 개입될 수 있는 부분에 절차적이고 객관적인 선거구 획정 방법론을 제시하고자 한다. 이를 위하여 선거구 획정기준(인구등가성, 연속성, 공간적 조밀성)을 준수하는 공간 최적화 모델을 고안하고 제19대 선거구 획정결과에서 논란이 되었던 용인시에 적용하여 그 가능성을 평가한다. 모델의 분석 결과는 정치적 고려나 임의적 개입 없이 기저의 데이터만으로 기준을 만족하는 선거구를 확정할 수 있음을 보여주었다. 특히, 모델에 의해서 도출된 선거구는 기존 선거구에 비하여 인구등가성을 향상시켰다.

• BMB Reports
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• 제42권9호
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• pp.541-551
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• 2009

Amyloidogenesis defines a condition in which a soluble and innocuous protein turns to insoluble protein aggregates known as amyloid fibrils. This protein suprastructure derived via chemically specific molecular self-assembly process has been commonly observed in various neurodegenerative disorders such as Alzheimer's, Parkinson's, and Prion diseases. Although the major culprit for the cellular degeneration in the diseases remains unsettled, amyloidogenesis is considered to be etiologically involved. Recent recognition of fibrillar polymorphism observed mostly from in vitro amyloidogeneses may indicate that multiple mechanisms for the amyloid fibril formation would be operated. Nucleation-dependent fibrillation is the prevalent model for assessing the self-assembly process. Following thermodynamically unfavorable seed formation, monomeric polypeptides bind to the seeds by exerting structural adjustments to the template, which leads to accelerated amyloid fibril formation. In this review, we propose another in vitro model of amyloidogenesis named double-concerted fibrillation. Here, two consecutive assembly processes of monomers and subsequent oligomeric species are responsible for the amyloid fibril formation of $\alpha$-synuclein, a pathological component of Parkinson's disease, following structural rearrangement within the oligomers which then act as a growing unit for the fibrillation.

• 산업공학
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• 제24권3호
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• pp.267-273
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• 2011

In the shipbuilding industry, since production processes are so complicated that the data collection for decision making cannot be fully automated, most of production planning and controls are based on the information provided only by field workers. Therefore, without sufficient information it is very difficult to manage the whole production process efficiently. Job status is one of the most important information used for evaluating the remaining processing time in production control, specifically, in block assembly shop. Currently, it is checked by a production manager manually and production planning is modified based on that information, which might cause a delay in production control, resulting in performance degradation. Motivated by these remarks, in this paper we propose an efficient algorithm for identifying job status in block assembly shop for shipbuilding. The algorithm is based on the multi-layer perceptron neural network model using two key factors for input parameters. We showed the superiority of the algorithm by using a numerical experiment, based on real data collected from block assembly shop.

• 제어로봇시스템학회논문지
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• 제16권11호
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• pp.1089-1095
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• 2010

We propose an image segmentation method for auto-teaching system of PCB (Printed Circuit Board) assembly inspection machines. The inspection machine acquires images of all components in PCB, and then compares each image with its standard image to find the assembly errors such as misalignment, inverse polarity, and tombstone. The component window that is the area of component to be acquired by camera, is one of the teaching data for operating the inspection machines. To reduce the teaching time of the machine, we newly develop the image processing method to extract the component window automatically from the image of PCB. The proposed method segments the component window by excluding the soldering parts as well as board background. We binarize the input image by use of HSI color model because it is difficult to discriminate the RGB colors between components and backgrounds. The linear combination of the binarized images then enhances the component window from the background. By use of the horizontal and vertical projection of histogram, we finally obtain the component widow. The experimental results are presented to verify the usefulness of the proposed method.

• 산업경영시스템학회지
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• 제41권2호
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• pp.105-116
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• 2018

In this study, we consider the assembly line balancing (ALB) problem which is known as an very important decision dealing with the optimal design of assembly lines. We consider ALB problems with soft constraints which are expected to be fulfilled, however they are not necessarily to be satisfied always and they are difficult to be presented in exact quantitative forms. In previous studies, most researches have dealt with hard constraints which should be satisfied at all time in ALB problems. In this study, we modify the mixed integer programming model of the problem introduced in the existing study where the problem was first considered. Based on the modified model, we propose a new algorithm using the genetic algorithm (GA). In the algorithm, new features like, a mixed initial population selection method composed of the random selection method and the elite solutions of the simple ALB problem, a fitness evaluation method based on achievement ratio are applied. In addition, we select the genetic operators and parameters which are appropriate for the soft assignment constraints through the preliminary tests. From the results of the computational experiments, it is shown that the proposed algorithm generated the solutions with the high achievement ratio of the soft constraints.

• 한국추진공학회지
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• 제23권3호
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• pp.96-103
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• 2019

본 연구에서는 지상 시험과 수치해석을 비교하여 시험용 달 궤도선의 추진제 공급부 설계 검증을 하고자 한다. 비행 모델의 유동 흐름을 모사할 수 있는 지상 시험용 검증 모델을 제작하고 있으며, 지상 시험용 검증 모델과 비교하기 위한 항목을 배관 내 전체 압력 강하량, 추력기 밸브 구동에 의한 수격현상 그리고 유량 제어 및 수격현상 완화를 위한 오리피스 장착의 세 가지로 선정하였다. 해석 결과를 향후 지상 시험 결과와 비교하여 최종적으로 설계 확정을 위한 근거 자료를 확보하고자 한다.

• Nuclear Engineering and Technology
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• 제54권10호
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• pp.3943-3948
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• 2022

Single-photon emission computed tomography is one of the reliable pin-by-pin verification techniques for spent-fuel assemblies. One of the challenges with this technique is to increase the total fuel assembly verification speed while maintaining high verification accuracy. The aim of the present study, therefore, was to develop an artificial intelligence (AI) algorithm-based tomographic image analysis technique for partial-defect verification of fuel assemblies. With the Monte Carlo (MC) simulation technique, a tomographic image dataset consisting of 511 fuel-rod patterns of a 3 × 3 fuel assembly was generated, and with these images, the VGG16, GoogLeNet, and ResNet models were trained. According to an evaluation of these models for different training dataset sizes, the ResNet model showed 100% pattern estimation accuracy. And, based on the different tomographic image qualities, all of the models showed almost 100% pattern estimation accuracy, even for low-quality images with unrecognizable fuel patterns. This study verified that an AI model can be effectively employed for accurate and fast partial-defect verification of fuel assemblies.

• 한국도로학회논문집
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• 제16권2호
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• pp.61-71
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• 2014

PURPOSES : The first generation of wide base tires introduced in the early 1980s was found to cause a significant increase in pavement damage compared to dual-tire assemblies. However, wide base tires have evolved considerably, and a new generation of wide base tire is thought to be comparable to conventional dual tires for pavement damage. A challenge associated with using wide base tires is the accurate quantification of pavement damage induced by these tires. The objective of this study was to investigate the responses of flexible pavement to continuously moving vehicular loading under various tire configurations. METHODS : The comparison of the strain/stress responses of full-depth pavement caused by conventional dual tire assembly and new generation of wide-base tires was performed. The FE model incorporates linear viscoelasticity of asphalt material and continuous moving load using implicit dynamic analysis. RESULTS AND CONCLUSIONS : The result demonstrates that the new wide-base tires caused slightly more fatigue damage and less primary rutting damage in HMA layer than a dual-tire assembly, but caused more secondary rutting damage in subgrade than a dual tire assembly.

• 한국압력기기공학회 논문집
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• 제12권1호
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• pp.11-16
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• 2016

Fuel assembly's mechanical characterization test facility (FAMeCT) in KAERI was constructed with upgraded functional features such as increased loading capacity, underwater vibration testing and severe earthquake simulation for extended fuel design guideline. This facility is designed and developed to provide out-pile fuel data for accident analysis model and fuel licensing. Functional tests of FAMeCT were performed to confirm functionality, structural integrity, and validity of newly-built fuel assembly mechanical test facility. Test program includes signal check of data acquisition system, load delivering capacity using real-sized fuel assemblies and a standard loading cylindrical rigid specimen. Fuel assembly's lateral bending test was carried out up to 30 mm of pull-out displacement. Limit case axial compression loading test up to 33 kN was performed to check structural integrity of UCPS (Upper Core Plate Simulator) support frame. Test results show that all test equipment and measurement system have acceptable range of alignment, signal to noise ratio, load carrying capacity limit without loss of integrity. This paper introduces newly constructed fuel assembly's mechanical test facility and summarizes results of functional test for the mechanical test equipment and data acquisition system.