• Journal of Welding and Joining
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• 제21권5호
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• pp.555-560
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• 2003

In automobile industry, it is necessary to reduce the weight from the view point of energy and environmental problems in these days. One of the ways for weight reduction is using adhesive aluminum structures. In this study, ultrasonic signals reflected from the adhesively bonded joint layer are used to evaluate the adhesively bonded joints. FFT is performed to determine bond-layer parameters such as effective thickness and frequency for adhesively bonded joint Al 6061 plates in comparison with the measured and theoretical ratios. And the parameters of ultrasonic wave and the J-integral are investigated to evaluate the adhesively bonded joint strength by DCB specimens.

• Management Science and Financial Engineering
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• 제17권1호
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• pp.45-63
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• 2011

The aim of this paper is to consider the process of supplying trained workers with knowledge and skills for upcoming business opportunities and the process of training apprentices to be prepared to meet future demands in an IT service firm. As the demand for new workers fluctuates, a firm should employ a buffer workforce such as apprentices or interns. However, as a result of rapid business development, the capacity of the buffer may be exceeded, thus requiring the company to recruit skilled workers from outside the firm. Therefore, it is important for a firm to map out a strategy for manpower planning so as to fulfill the demands of new business and minimize the operation costs related to training apprentices and recruiting experienced workers. First, this paper analyzes the supply and demand of workers for the IT service in a knowledge-intensive field. It then presents optimal human resource planning strategies via the familiar method of stochastic process. Also, we illustrate that our model is applied to the human resource planning of an information security service firm in South Korea.

• 한국레이저가공학회지
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• 제11권4호
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• pp.21-28
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• 2008

Remote Laser welding technology for manufacturing automotive body is studied. Laser welding and industrial robot systems are used for the robot based laser welding system. The laser system is used 1.6kW Fiber laser(YLR-1600) of IPG. The robot system is used HX130-02 of Hyundai Heavy Industry(payload : 130kg). The robot based laser welding system is equipped with laser scanner system for remote laser welding. The welding joints of steel plate and steel plate coated with zinc are butt and lapped joints. The quality test of the laser welding are through the observation the shape of bead on plate and cross-section of welding part. During past three years the laser system, 4kW Nd:YAG laser (HL4006D) of Trumpf was used and the robot system, IRB6400R of ABB (payload:120kg) was used. The new laser source, robot and laser scanner system are used to increase the processing speed and to improve the process efficiency. This paper introduces the robot based remote laser welding system to resolve the limited welding speed and accuracy of the conventional laser welding system.

• 한국태양에너지학회 논문집
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• 제28권3호
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• pp.15-20
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• 2008

Building-integrated photovoltaics(BIPV) are increasingly incorporated into new domestic and industrial buildings as a principal or ancillary source of electrical power, and are one of the fastest growing segments of the photovoltaic industry. This paper presents design, operational features analysis, and PCS(Power Conditioning System) of grid-connected 30kW BIPV set up on the library of Dongshin University. For a sustainable photovoltaics system in this area, the data of the BIPV system are collected and analyzed by monitoring system using LabView. PCS of the grid-connected BIPV system, also, is designed for optimal operation with characteristics suggested in this paper.

• 한국전자통신학회논문지
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• 제12권2호
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• pp.361-366
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• 2017

산업체 전반의 주요 설비에서 이상 상태는 온도의 이상 상승, 진동과 소음의 변화를 수반하여 나타나게 된다. 본 연구에서는 BLE 를 탑재한 스마트 센싱 모듈를 개발하고, MEMS 기반의 가속도 센서를 인터페이스하여, 설비의 자체결함으로 인한 이상진동을 감지할 수 있는 스마트 센싱 디바이스를 개발하였다. 본 연구에서 개발한 스마트 센싱장치는 좁은 공간에 쉽게 설치하여, 설비의 진동상태를 실시간으로 모니터링 할 수 있으며, 어레이 LED 디스플레이로 정상상태와 문제 발생상태를 간편하게 사용자에게 알려줄 수 있다.

• International Journal of Automotive Technology
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• 제6권5호
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• pp.519-527
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• 2005

Recently, weight reduction of vehicles has been of great interest and consequently the use of low-density materials in the automotive industry is increasing every year. However, the substitution of one material for another is not simple because it accompanies several problems, for example, weakness in the strength and stiffness and difficulty in the joining. To overcome these problems, the structure of the automobile redesigned totoally. Aluminum spaceframe is rapidly being adopted as a body structure for accommodating lightness, stiffness and strength requirement. In aluminum spaceframe manufacturing, it is often required to join aluminum tube. However, there are few suitable methods for joining aluminum tube, so that much interest has been focused on testing suitable joining methods. Joining by electromagnetic forming (EMF) can be useful method in joining aluminum tube, which offers some advantages compared with the conventional joining methods. In this paper, joining by EMF was investigated as a pre-study for applying an automotive spaceframe. Finite element simulations and strength tests were performed to analyze the influence of geometric parameters on joint strength. Based on these results, configurations of axial joint and torque joint were suggested and guidelines for designing EMF joint were established.

• Journal of Electrical Engineering and Technology
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• 제9권2호
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• pp.478-488
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• 2014

Torque pulsation mechanism and highly nonlinear magnetic characterization of switched reluctance motors(SRM) lead to unfavorable torque ripple and limit the variety of applications in industry. In this paper, a modification method proposed for torque ripple minimization of SRM based on conventional torque sharing functions(TSF) to improve maximum speed of torque ripple-free operation considering converter limitations. Due to increasing phase inductance in outgoing phase during the commutation region, reference current tracking can be deteriorated especially when the speed increased. Moreover, phase torque production in incoming phase may not be reached to the reference value near the turn-on angle in which the incremental inductance would be dramatically decreased. Torque error for outgoing phase can cause increasing the resultant motor torque while it would be negative for incoming phase and yields reducing the motor torque. In this paper, a modification method is proposed in which phase torque tracking error for each phase under the commutation added to the other phase so that the resultant torque remained in constant level. This yields to extend constant torque region and reduce peak phase current when the speed increased. Simulation and experimental results for four phase 4 KW, 8/6 SRM validate the effectiveness of the proposed scheme.

• 대한공업교육학회지
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• 제31권2호
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• pp.350-363
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• 2006

최근 마이크로 엔드밀을 이용한 가공은 소형구조물이나 소형기계의 부품과 금형산업에서 양호한 표면 거칠기와 가공시간의 단축을 위해 고정도의 기술을 요구하고 있다. 마이크로 엔드밀을 이용한 가공에 있어서 가공조건은 절삭면의 표면거칠기에 커다란 영향을 미치게 된다. 따라서 본 연구에서는 마이크로 엔드밀을 이용하여 스테인리스 강(STS 304)의 표면을 가공하였고, 실험계획법에 의해 최적의 표면거칠기를 얻기 위한 가공조건에 대해 분산분석하였다. 본 연구를 통하여 마이크로 엔드밀에 의한 가공에서 가공조건은 절삭깊이, 스핀들의 회전수, 이송속도의 순서로 표면거칠기에 영향을 미치는 것을 알았다.

• 한국산학기술학회논문지
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• 제12권4호
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• pp.1947-1953
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• 2011

OSEK/VDX는 자동차 ECU를 위한 산업계 표준을 제시하고자 구성된 공동 프로젝트이며 OSEK OS는 OSEK/VDX에서 제안한 사양을 준수하는 실시간 운영체제이다. 본 논문에서는 ARM 프로세서를 기반으로 한 OSEK OS의 태스크 전환 및 인터럽트 핸들링 메커니즘 구현을 제시한다. OSEK OS의 요구사항과 ARM 프로세서의 특성을 고려하여 태스크 전환 및 인터럽트 핸들링 메커니즘을 설계하였다. 제시한 메커니즘의 타당성을 검토하기 위하여 ARM 프로세서가 탑재된 실험용 임베디드 보드에서 기능적 정확성을 확인하고 태스크 전환과 인터럽트 핸들링에 소요되는 시간을 측정하였다.

• 한국기계가공학회지
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• 제21권1호
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• pp.49-55
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• 2022

Recently, the automobile industry has continued to demand lighter materials owing to international environmental regulations and increased convenience. To address this demand, aluminum parts have increased in popularity and are mainly developed and produced through hot forging and cold pressing. However, because this method has low yield and low production efficiency, a new manufacturing method is desirable. In this study, the water capacity efficiency of an aluminum inner tie rod socket was investigated using cold forging that provided a high yield and excellent production efficiency. Mechanical properties were derived through tensile testing of 6110A aluminum materials, and critical fracture factor and process analysis based on experimental data were carried out. The optimized process was applied as a prototype using cold multi-stage forging, and based on the derived results, the formability, productivity, and material efficiency of aluminum inner tie rod socket parts using this cold forging process was verified.