• Smart Structures and Systems
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• 제21권5호
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• pp.623-635
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• 2018

In order to study the mechanical behavior of shield tunnel segments during assembly stage, the in-situ tests and FDM numerical simulation were conducted based on the Foguan Shiziyang Tunnel with large cross-section. Analysis for the load state of the assembling segments in different assembly steps as well as the investigation for the changing of inner forces and longitudinal stress of segments with assembling steps were carried out in this paper. By comparing the tested results with the simulated results, the conclusions and suggestions could be drawn as follows: (1) It is the most significant for the effects on axial force and bending moment caused by the assembly of adjacent segment, followed by the insertion of key segment while the effects in the other assembly steps are relative smaller. With the increasing value of axial force, the negative bending moment turns into positive and remains increasing in most monitored sections, while the bending moment of segment B1and B6 are negative and keeping increasing; (2) The closer the monitored section to the adjacent segments or the key segment, the more significant the internal forces response, and the monitored effects of key segment insertion are more obvious than that of calculation; (3) The axial forces are all in compression during assembling and the monitored values are about 1.5~1.75 times larger than the calculated values, and the monitored values of bending moment are about 2 times the numerical calculation. The bending moment is more sensitive to the segments assembly process compared with axial force, and it will result in the large bending moment of segments during assembling when the construction parameters are not suitable or the assembly error is too large. However, the internal forces in assembly stage are less than those in normal service stage; (4) The distribution of longitudinal stress has strong influence on the changing of the internal forces. The segment side surface and intrados in the middle of two adjacent jacks are the crack-sensitive positions in the early assembly stage, and subsequently segment corners far away from the jacks become the crack-sensitive parts either.

• 한국시뮬레이션학회논문지
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• 제27권3호
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• pp.117-129
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• 2018

이 논문에서는 철도차량 의장공장에서 적용되는 두 종류의 배치안 개념에 대한 논의하고자 한다. 현재 시스템은 전통적인 흐름라인 방식에 따라 조립라인이 설계되어 있지만 새로운 시스템은 고정위치형 배치방식을 따르고자 한다. 시스템에 영향을 주는 요소로는 공정시간의 변동성, 결품률 및 결품시간의 분포를 고려하였다. 시뮬레이션 실험결과 해당시스템의 경우 생산량, 차량당 평균 체류시간, 편성당 평균 체류시간 모두 고정위치형 배치방식을 사용하는 것이 좋다는 결론을 얻었다. 또한 시스템의 고정위치형 방식이 흐름라인 방식에 비해 변화에 둔감하게 반응함으로써 강건성 측면에서도 우수하다는 결론을 얻었다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2011년도 춘계학술대회 논문집
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• pp.1493-1494
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• 2011

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2011년도 춘계학술대회 논문집
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• pp.113-114
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• 2011

• International Journal of Aerospace System Engineering
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• 제5권1호
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• pp.1-8
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• 2018

Military rotorcrafts are constantly exposed to risk from bullet impacts because they operate in a battle environment. Because bullet impact damage can be deadly to crews, the fuel tanks of military rotorcraft must be designed taking extreme situations into account. Fuel tank design factors to be considered include the internal fluid pressure, the structural stress on the part impacted, and the kinetic energy of bullet strikes. Verification testing using real objects is the best way to obtain these design data effectively, but this imposes substantial burdens due to the huge cost and necessity for long-term preparation. The use of various numerical simulation tests at an early design stage can reduce the risk of trial-and-error and improve the prediction of performance. The present study was an investigation of the effects of bullet impacts on a fuel tank assembly using numerical simulation based on SPH (smoothed particle hydrodynamics), and conducted using the commercial package, LS-DYNA. The resulting equivalent stress, internal pressure, and kinetic energy of the bullet were examined in detail to evaluate the possible use of this numerical method to obtain configuration design data for the fuel tank assembly.

• 한국생산제조학회지
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• 제24권2호
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• pp.251-255
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• 2015

Thermal deformation, such as bending and twisting, occurs among the polymer parts of air-conditioner indoor units because of repetitive temperature change during heating operation. In this study, a numerical method employing finite-element analysis to efficiently simulate the thermal deformation of an assembly is proposed. Firstly, the displacement of an actual assembly produced by thermal deformation was measured using a 3D optical measurement system. The measurement results indicated a general downward sag of the assembly, and the maximum displacement value was approximately 1 mm. The temperature distribution was measured using a thermographic camera, and the results were used as initial-temperature boundary conditions to perform temperature-displacement analysis. The simulation results agreed well with the measured data. To reduce the thermal deformation, the stiffness increased 100%. As the results, the maximum displacement decreased by approximately 5.4% and the twisting deformation of the holder improved significantly.

• 산업융합연구
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• 제18권1호
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• pp.17-23
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• 2020

본 연구는 블렌디드 러닝을 위한 자동차 엔진 부품 조립에 대한 증강현실 콘텐츠 개발을 하고 설문을 통해 교육 효과의 유용성을 확인하였다. 자동차 엔진 조립에 대한 커리큘럼을 설계하고, 각 커리큘럼에 따라 조립해야 할 부품의 모양, 위치, 조립 순서 등을 증강현실 콘텐츠로 개발하였다. 개발된 증강현실 시뮬레이션 콘텐츠는 학습자 중심의 협력 활동과 결합하여 학생들이 능동적으로 학습할 수 있도록 하였고, 교사는 촉진자 역할을 수행하도록 설계하였다. 본 콘텐츠와 전통적인 학습을 한 학생들과 비교 실험하여 약 2배의 학습 시간이 절감되는 것으로 나타났다. 본 연구를 통해 학생들의 문제해결, 프로세스 기술, 시스템 기술 및 인지 능력 등이 강화되는 것을 확인할 수 있었다.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2022년도 추계학술대회
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• pp.15-17
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• 2022

볼 베어링 선택조립 시스템에서 잉여부품을 최소화하기 위해서는 각 부품의 치수 분포를 파악하여 선택 확률을 최적화하여야 하지만, 복잡한 시스템은 생산 공정에 지연이 일으킨다. 본 논문에서는 볼 베어링 선택조립 시스템에서 빠르고 간단하게 선택 우선순위를 결정할 수 있는 군집 우선 선택 알고리즘을 제안한다. 그리고 실제 볼 베어링 선택조립 공정에서 수집한 데이터로 모의 상황을 가정하고, 군집 우선 선택 알고리즘과 기존 알고리즘을 시뮬레이션하여 잉여부품 발생률과 연산소요시간을 평가한다. 시뮬레이션 결과, 군집 우선 선택 알고리즘이 기존 알고리즘에 비하여 83.8% 적은 잉여부품을 발생하였고, 연산소요시간도 39.7% 단축되었다.

• 산업공학
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• 제9권2호
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• pp.39-45
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• 1996

This paper investigates the problems of grouping N products on an assembly line with an objective of maximizing the option grouping rate. Before developing a mixed model grouping algorithm, simulation studies are committed for developing operating rules and evaluating the layout production systems. A mixed model grouping algorithm is suggested and it is applied to the color selection lane in automobile production system, which reveals a high mixed model grouping rate.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.297-297
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• 2000

This paper proposed character recognition method by using DB Matching and Artificial Neural Network at the Gerber files. Gerber files are file for make PCB. But we also use the file to a program of extraction PCB position data. If the Gerber file recognized a character, the extraction PCB position data will be faster and also when the recognition rate is high, it can be possible to automatic extraction. We apply to the construction PCB Gerber file program and Simulation results are presented to verify the usefulness of the method.