• 대한기계학회논문집A
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• 제24권4호
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• pp.811-823
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• 2000

In design and manufacturing airframe structures which are composed of a lot of sub-assemblies and large complex profile shapes it is difficult to reduce so called hardware variations. Accordingly cost increasing factors for manufacturing airframe parts are much more than other machine parts because of the variability of fabricated details and assemlies. To improve cost and quality, accurate assembly methods and DPD techniques are proposed in this paper which are based upon using CAD/CAM techniques, the concept of KC's and the coordinated datum and index throughout the design, tooling, manufacturing and inspection. The proposed methods are applied to produce fuselage frame assemblies and related engineering aspects are described regarding the design of parts and tools in the context of concurrent digital definition. First articles and consequent mass production of frame assemblies shows a great improvement of the process capability ratio from 0.7 by the past processes to 1.0 by the proposed methods in addition to the cost reduction due to the less number of tools, reduced total assembly times and the space compaction needed by massive inventory. The need to achieve better Cpk, however, and future studies to be investigated will be addressed briefly.

• Genomics & Informatics
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• 제6권2호
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• pp.87-90
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• 2008

During the last four years, the pyrosequencing-based 454 platform has rapidly displaced the traditional Sanger sequencing method due to its high throughput and cost effectiveness. Meanwhile, the Sanger sequencing methodology still provides the longest reads, and paired-end sequencing that is based on that chemistry offers an opportunity to ensure accurate assembly results. In this report, we describe an optimized approach for hybrid de novo genome assembly using pyrosequencing data and varying amounts of Sanger-type reads. 454 platform-derived contigs can be used as single non-breakable virtual reads or converted to simpler contigs that consist of editable, overlapping pseudoreads. These modified contigs maintain their integrity at the first jumpstarting assembly stage and are edited by fragmenting and rejoining. Pre-existing assembly software then can be applied for mixed assembly with 454-derived data and Sanger reads. An effective method for identifying genomic differences between reference and sample sequences in whole-genome resequencing procedures also is suggested.

• Smart Structures and Systems
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• 제32권2호
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• pp.111-121
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• 2023

This study proposes an automated assembly performance evaluation method for prefabricated steel structures (PSSs) using machine learning methods. Assembly component images were segmented using a modified version of the receptive field pyramid. By factorizing channel modulation and the receptive field exploration layers of the convolution pyramid, highly accurate segmentation results were obtained. After completing segmentation, the positions of the bolt holes were calculated using various image processing techniques, such as fuzzy-based edge detection, Hough's line detection, and image perspective transformation. By calculating the distance ratio between bolt holes, the assembly performance of the PSS was estimated using the k-nearest neighbors (kNN) algorithm. The effectiveness of the proposed framework was validated using a 3D PSS printing model and a field test. The results indicated that this approach could recognize assembly components with an intersection over union (IoU) of 95% and evaluate assembly performance with an error of less than 5%.

• 품질경영학회지
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• 제10권2호
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• pp.10-17
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• 1982

Three different manual assembly techniques are evaluated by relating the effects of component quality to the total cost of the product. The results show that the choice of the scrapping or repairing the defective products or alternatively, salvaging the acceptable parts, may effect the total product cost by as much as 400 per cent. This paper emphasizes the need for accurate control quality of parts in assembly if low-cost manufacture is to be achieved.

• 대한조선학회논문집
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• 제49권1호
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• pp.87-92
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• 2012

Alignment of the main plates during the tack welding is essential to block assembly since most of the curved blocks and outfitting parts are assembled on the jigs and fixtures. Tact welding of main plates is the initial process of the curved hull block assembly. Due to the heavy weight of the main plates it is difficult to locate the plate on the accurate position of the jig and fixtures before welding. The conventional masonry process requires much time and manual work in order to achieve the accurate alignment. This labour-intensive process results in relatively high errors and correction works. Due to their larger dimensions and heavier weights, these hull blocks are not ergonomically desirable and, therefore, various mechanical devices such as hydraulic balancers or hydraulic jigs are used for the plate alignment. In this study, the position-sensing scheme implemented by sensors is presented in order to align the main plates on the accurate position during the hull block assembly. Integrating the Infrared photo sensors and micro processor unit, a small scaled prototype of the position-sensing module is developed to determine the alignment of main plates.

• 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.

• 대한기계학회논문집 C: 기술과 교육
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• 제3권2호
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• pp.97-106
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• 2015

Flexible structures are often important components of mechanical assemblies in motion. A flexible structure sometimes must go through assembly steps that cause it to be in a pre-stressed condition when in the starting position for operation. A virtual prototype of the assembly must also bring the model of the flexible structure into the same pre-stressed condition in order to obtain accurate simulation results. This case study is presented regarding the simulation of a constant velocity joint, with a focus on the flexible boot. The case study demonstrates that careful definition of the initial conditions of the boot and flexible body contacts yields high-fidelity simulation results.

• 정보처리학회논문지B
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• 제13B권2호
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• pp.139-148
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• 2006

협업적 제품 설계 환경에서는 여러 설계자가 작업에 참여하기 때문에 설계자간의 원활한 의사 소통이 필수적인 요소이다. 즉, 제품 설계에 내재되어 있는 다른 설계자의 설계의도를 파악할 수 있어야 하고, 각 설계자마다 사용하고 있는 상이한 모델링 용어에 대한 의미적 처리가 필요하다. 시맨틱 웹에서 온톨로지는 의미 정보를 명시적으로 표현할 수 있기 때문에 데이터와 서비스에 대한 통합되고 일관된 접근을 가능하게 한다. 따라서 제품을 여러 설계자가 설계하는 협업적 환경에서 온톨로지를 사용한다면 조립체내의 내포된 공학적 관계들, 공간적 관계들, 그리고 접합 관계들이 명확하게 표현되고, 추론을 통해 설계자의 의도가 파악되어 설계자간의 의사소통이 원활하게 이루어질 수 있다. 본 논문에서 는 조립체를 온톨로지를 이용하여 표현함으로써 협업적 환경에서 조립체 설계정보를 공유할 수 있는 시맨틱 조립체 모델링 프레임워크를 제안한다. 시맨틱 조립체 모델링 프레임워크에서는 조립체 관계 모델(Assembly Relationship Model, ARM)을 OWL(Web Ontology Language)와 SWRL(Semantic Web Rule Language)로 표현한다. 이를 통해 조립체 내에 내포된 공학적 관계들, 공간적 관계들, 그리고 접합 관계들이 명확하게 표현되고, 추론되어 설계 의도가 파악된다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.1854-1858
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• 2007

The reliability assurance with respect to the test procedure and results of the out-pile mechanical performance test for the nuclear fuel assembly is an essential task to assure the test quality and to get a permission for fuel loading into the commercial reactor core. For the case of vibration test, which is carried out to obtain basic dynamic characteristics of the fuel assembly, proper management and appropriate calibration of instruments and devices used in the test, various efforts to minimize the possible error during the test and signal acquisition process are needed. Additionally, the deep understanding both of the theoretical assumption and simplification cation for the signal processing/modal analysis and of the functions of the devices used in the test were highly required. Finally, to verify the test result to represent the accurate natural characteristics of the structure, the proper correlation analysis between the theoretical and experimental method has to be carried out. In this study, the overall procedure and result of lateral vibration test for the fuel assembly's mechanical characterization were briefly introduced. A series of measures to assure and improve the reliability of the vibration test were discussed.

• 전자공학회논문지B
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• 제31B권1호
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• pp.41-48
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• 1994

The conventional resolved motion control is not applicable for the control of robots on the spacecraft on account of the floating base of the robots. When the robots perform the assembly or repair operations, the position and attitude of the base satellite are disturbed by the reaction force/moment caused by the robot motion. This reaction will cause error on the robot. motion. Therefore, we define a new type of Jacobian(Extended Jacobian) to minimize the effects of reaction on the accuracy of the robot performing assembly or repair operations. In this paper, we utilize the redundancy of the closed chain system to minimize the effects of the robot motion on the position and attitude of spacecraft. This will results in the accurate assembly and repair operations by the robot.