• Journal of Welding and Joining
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• 제32권2호
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• pp.43-47
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• 2014

Famous artificial neural network (ANN) is applied to predict proper process window of arc welding. Target weldment is variously combined lap joint fillet welding of automotive steel plates. ANN's system variable such as number of hidden layers, perceptrons and transfer function are carefully selected through case by case test. Input variables are welding condition and steel plate combination, for example, welding machine type, shield gas composition, current, speed and strength, thickness of base material. The number of each input variable referred in welding experiment is counted and provided to make it possible to presume the qualitative precision and limit of prediction. One of experimental process windows is excluded for predictability estimation and the rest are applied for neural network training. As expected from basic ANN theory, experimental condition composed of frequently referred input variables showed relatively more precise prediction while rarely referred set showed poorer result. As conclusion, application of ANN to arc welding process window derivation showed comparatively practical feasibility while it still needs more training for higher precision.

• 한국통신학회논문지
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• 제12권2호
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• pp.176-188
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• 1987

본 논문은 역필터링을 이용하여 이동에 의해 흐려진 영상을 복원하는 기법에 관한 논문이다. 적절한 역필터를 설계하기 위하여 저하과정(Degradation Process)을 정확히 모델링하여 그의 역특성을 갖는 필터를 구해내야 한다. 고속으로 이동하는 물체의 영상은 Blurring되는데, 이것은 수학적으로 시간에 대한 영상의 적분으로 모델링될 수 있으며, 공간좌표상 방향성 방형 윈도우(Rectangular Window)를 상승(Convolution)하는 것으로 분석된다. 본 논문에서는 주파수 영역에서 이를 분석하여, 이동방향을 고려한 역 Sinc 함수 특성을 갖는 필터를 이용하여 흐려진 영상을 복원하는 기법을 연구한다.

• 산업경영시스템학회지
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• 제29권4호
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• pp.75-82
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• 2006

The main objective of this study is to find out the shortest path of the vehicle routing problem with time window constraints by using both genetic algorithm and heuristic. Hard time constraints were considered to the vehicle routing problem in this suggested algorithm. Four different heuristic rules, modification process for initial and infeasible solution, 2-opt process, and lag exchange process, were applied to the genetic algorithm in order to both minimize the total distance and improve the loading rate at the same time. This genetic algorithm is compared with the results of existing problems suggested by Solomon. We found better solutions concerning vehicle loading rate and number of vehicles in R-type Solomon's examples R103 and R106.

• 한국추진공학회지
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• 제22권6호
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• pp.94-103
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• 2018

발사체 및 유도무기 기체에 사용되는 복합재 격자구조물은 구조물에 작용하는 하중을 고려하여 최소한의 두께와 무게로 설계되는 구조물이다. 이를 위하여 실리콘 몰드에 탄소섬유를 와인딩하는 공정으로 격자구조물을 만들며, 이때 발사체 및 유도무기 기체 내부의 장비 등을 점검하기 위하여 점검창을 설치하는 것이 일반적으로 요구된다. 본 논문에서는 필라멘트 와인딩 공정으로 제작된 실린더형 격자구조물에 대하여 압축시험을 수행하고, 이 구조물에 대한 유한요소해석을 수행하여 얻은 해석 결과를 설치된 격자구조물에 대하여 유한요소해석을 수행하였다. 또한 구조물의 리브(Rib)와 노트(Knot)의 파손강도를 통해 육각형 점검창의 두께 및 위치를 변수로 선정하여 수행한 유한요소해석 결과는 다음과 같다; (1) 육각형 점검창의 안전계수가 사각형 점검창 보다 높게 계산되었으며, (2) 수직 점검창이 상단 헬리컬 리브의 중간에 위치할 때 안전계수가 높게 계산되었고, (3) 구조안전성 확보를 위하여 점검창의 두께를 증가시킬 경우 구조물의 불연속 부분에 응력집중이 발생하므로 유한요소 해석을 통해 안전계수가 가장 높은 점검창 형상을 선정해야 한다.

• KIEAE Journal
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• 제16권3호
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• pp.77-82
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• 2016

Purpose: The aim of this study is to calculate U-factor of the window using international standard methods and compare quantitative and tendency difference focused on ISO standard 15099 and ISO standard 10077. And the result of ISO standard calculation methods is verified using thermal performance experiment to evaluate applicability of domestic certification system. This study is utilized a basis for activation of domestic window certification system. Method: First, 16 cases are selected that is combined a variety of frame, Glazing, spacer, etc. The selected cases were simulated using WINDOW&THERM based on ISO 15099 and 10077 calculation method. Second, experiment was conducted based on Korean standard condition. Then, it was compared the error of experiment and simulation results. Through this process, ISO 15099 and 10077 calculation methods were evaluated accuracy and utilization. Result: The results show that the difference of ISO 15099 and ISO 10077-2 is maximum 5.4%. The results of comparing U-factor errors based on the Korea standard experiment test found 2.4%. Consequently, it will be possible to combination calculation methods of ISO 15099 and ISO 10077 for a single window.

• 제어로봇시스템학회논문지
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• 제18권11호
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• pp.997-1004
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• 2012

In enterprise software projects, performance issues have become more critical during recent decades. While developing software products, many performance tests are executed in the earlier development phase against the newly added code pieces to detect possible performance regressions. In our previous research, we introduced the framework to enable automated performance anomaly detection and reduce the analysis overhead for identifying the root causes, and showed Statistical Process Control (SPC) can be successfully applied to anomaly detection. In this paper, we explain the special performance trend in which the existing anomaly detection system can hardly detect the noticeable performance change especially when a performance regression is introduced and recovered again a while later. Within the fixed number of sampling period, the fluctuation gets aggravated and the lower and upper control limit get relaxed so that sometimes the existing system hardly detect the noticeable performance change. To resolve the issue, we apply dynamically tuned sampling window size based on the performance trend, and Fuzzy theory to find an appropriate size of the moving window.

• 한국기계가공학회지
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• 제13권3호
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• pp.63-69
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• 2014

This paper studies the strength, fatigue sensitivity, safety factor and lifetimes by means of structural and fatigue analyses of different models of rear doors upon the opening of doors and windows leading to severe fatigue fractures of the window motor components of rear doors. The simulation models were a standard model and other models. The other models, which are denoted here as models I and II, were modified versions of the standard model, with a rib of 3mm and a thickness of 2mm as compared to the standard model. The door was modelled with CATIA V5 and analyzed with the ANSYS program. The material of the rear door was cold rolled steel (DDQ). From the study results, the standard model and model I were confirmed to be less safe upon the opening of the door as compared to the opening of a window in terms of fatigue, but model II was found to be safe for both door and window openings.

• 한국소음진동공학회논문집
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• 제17권11호
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• pp.1093-1101
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• 2007

This study presents the design improvement process for door module. Its objective evades the resonance generated at module plate due to the operation of window regulator motor. For this study, the design improvement process is composed of experimental methods having three steps. First step is modal analysis at door assembly status for acquisition of dynamic characteristics which are modal frequency and damping. Second step is a vibration experiment to get the test mode considered an efficiency of window regulator motor. Last step is a vibration measurement by the form of $6{\times}6$ array on module plate. A vibration measurement of $6{\times}6$ array form can be got to three analysis results which are a transfer path of vibration using cross correlation function, a vibration map using OA level and a contribution by frequency band using coherent output power spectrum on module plate. These results are applied to SDM(structural dynamic modification) for design improvement to get around the resonance on module plate by the excitation of window regulator motor.

• 한국정보전자통신기술학회논문지
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• 제4권2호
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• pp.103-110
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• 2011

u-Health 시스템의 센서들로부터 측정된 데이터에 대한 정확하고 에너지 효율적인 관리가 필요하다. 센서네트워크에서 대용량의 입력 스트림 데이터 전체를 데이터베이스에 모두 저장하여 한꺼번에 처리하는 것은 효율적이지 못하다. 본 논문에서는 u-Health 시스템 내 센서 네트워크의 에너지 효율성과 정확성을 고려하여 여러 센서에서 지속적으로 들어오는 다차원 스트림 데이터의 처리 성능을 높이고자 한다. 효율적인 입력 스트림 처리를 위해서 슬라이딩 윈도우 기반으로 질의를 처리하고 Mjoin 방법으로 다중 질의 계획을 수립한 후 역전파 알고리즘을 통해 저장 데이터를 축소하는 효율적인 처리 기법을 제안한다. 14,324개의 데이터 집합을 사용하여 실험한 결과 실제 입력되는 데이터보다 저장 공간의 18.3%를 축소함으로써 효과적임을 보였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권4호
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• pp.1193-1215
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• 2021

The measurement of the key product quality index plays an important role in improving the production efficiency and ensuring the safety of the enterprise. Since the actual working conditions and parameters will inevitably change to some extent with time, such as drift of working point, wear of equipment and temperature change, etc., these will lead to the degradation of the quality variable prediction model. To deal with this problem, the selective integrated moving windows based principal component regression (SIMV-PCR) is proposed in this study. In the algorithm of traditional moving window, only the latest local process information is used, and the global process information will not be enough. In order to make full use of the process information contained in the past windows, a set of local models with differences are selected through hypothesis testing theory. The significance levels of both T - test and χ² - test are used to judge whether there is identity between two local models. Then the models are integrated by Bayesian quality estimation to improve the accuracy of quality variable prediction. The effectiveness of the proposed adaptive soft measurement method is verified by a numerical example and a practical industrial process.