• Journal of Biosystems Engineering
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• 제39권2호
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• pp.134-141
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• 2014

Purposes: This study was to validate the Robotic Smart Work System that can provides better working conditions and high productivity in unstructured environments like bio-industry, based on a tele-operation system for fruit harvesting with low cost 3-D positioning system on the laboratory level. Methods: For the Robotic Smart Work System for fruit harvesting and cultivation management in agriculture, a vision based tele-operating system and 3-D position information are key elements. This study proposed Robotic Smart Farming, an agricultural version of Robotic Smart Work System, and validated a 3-D position information system with a low cost omni camera and a laser marker system in the lab environment in order to get a vision based tele-operating system and 3-D position information. Results: The tasks like harvesting of the fixed target and cultivation management were accomplished even if there was a short time delay (30 ms ~ 100 ms). Although automatic conveyor works requiring accurate timing and positioning yield high productivity, the tele-operation with user's intuition will be more efficient in unstructured environments which require target selection and judgment. Conclusions: This system increased work efficiency and stability by considering ancillary intelligence as well as user's experience and knowhow. In addition, senior and female workers will operate the system easily because it can reduce labor and minimized user fatigue.

• 한국자동차공학회논문집
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• 제16권3호
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• pp.38-43
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• 2008

The hydroforming technology has been spreaded dramatically in automotive industry last 10 years. Itmay cause many advantages to automotive applications in terms of better structural integrity of the parts, lower cost from fewer part count, material saving, weight reduction, lower springback, improved strength and durability and design flexibility. In this study, the whole process of rear sub-frame parts development by tube hydroforming using steel material having tensile strength of 440MPa grade is presented. At the part design stage, it requires feasibility study and process design aided by CAE (Computer Aided Design) to confirm hydroformability in details. Effects of parameters such as internal pressure, axial feeding and geometry shape in automotive rear sub-frame by hydroforming process were carefully investigated. Overall possibility of hydroformable sub-frame parts could be examined by cross sectional analyses. Moreover, it is essential to ensure the formability of tube material on every forming step such as pre-bending, preforming and hydroforming. In addition, all the components of prototyping tool are designed and interference with press is examined from the point of geometry and thinning.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제22회 춘계학술대회논문집
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• pp.593-596
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• 2004

We are developing a micro-solid propellant rocket array thruster for simple attitude control of a 10 kg class micro-spacecraft. The prototype has ø 0.8 mm solid propellant micro-rockets arrayed at a pitch of 1.2 mm on a 22 x 22 mm substrate. In previous studies, an impulse thrust of 4.6 x 10$^{-4}$ Ns was obtained in vacuum, but we found the problems of unacceptably low ignition success rate and incomplete combustion. This paper describes experiments to improve the ignition rate. In order to achieve this goal, we tried to solidify paste-like ignition aid (RK) on the ignition heaters with strong adhesion. To make the paste-like RK, isoamyl acetate was added to RK powder. We tested 9 rockets, but only 2 rockets were ignited with huge ignition energy. This is because the heat con-duction between the ignition heater and the RK was too low to ignite the RK, since dried RK had a lot of pores. Also, a large cavity was sometimes found just above the ignition heater.

• 실천공학교육논문지
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• 제8권1호
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• pp.63-68
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• 2016

본 연구에서는 일 학습병행제도의 연착륙과 성공적인 확산기반의 마련을 위해 효과적인 계약학과 운영모델을 제안하고자한다. 계약학과 운영과 관련한 당면과제 측면에서 보면 계약학과 입학생들은 특성화고나 마이스터고 출신들이고 성인이며 재직자이기 때문에 학업에 불리한 조건을 많이 가지고 있다. 따라서 학업부담을 완화시켜 주어야 하고, 탄력적인 학사운영이 필요하며, 낮은 학업능력 및 의욕을 보완해주어야 한다. 한편 직원들을 계약학과에 보내는 기업 입장에서는 현장 맞춤형 교육이 절실하게 요구된다. 이러한 당면과제들을 효과적으로 해소하기 위해 한기대는 S-OJT 교과목 도입, NCS 기반의 표준이수체계구축, 선행학습인정제도 활용, 역진행 학습(Flipped Classroom)의 도입, Tutor제 도입, 기초학습능력 지원을 위한 신규 교과목 개발 등 도전적인 방안들을 마련하였다. 이러한 시도가 성공적으로 정착된다면 우리나라 계약학과 제도를 한 단계 업그레이드 시키고 평생직업능력개발을 선도할 것으로 기대된다.

• 실천공학교육논문지
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• 제10권1호
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• pp.25-33
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• 2018

IT산업이 발달하면서 기존의 이론 교과목에서 머물러져 있던 이러닝 학습이 실습이 요구되는 교과목까지 영역이 확장되고 있다. 이러닝 학습에서 실습이 요구되는 교과목이 온라인 실습을 통해 학습성과가 있는지 평가돼야 한다. 본 연구에서는 사이버대학 메카트로닉스공학 학생들이 전공기초실습 교과목인 'PLC제어'교과목과 '전동기 서보제어'교과목을 이러닝에서 학습을 위해 '프라임칼리지(Prime College)의 사이버랩'을 통해 학습 성과가 있는지 조사하였다. 이를 위해 사이버랩 학습 운영을 진행하였고, 2년 동안 교과목을 수강한 학생에 대하여 5점 척도 설문과 취득성적을 통해 실습교과목의 대한 이러닝 교육의 효과가 상단부분 있음을 확인하였다.

• Journal of Welding and Joining
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• 제32권4호
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• pp.10-14
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• 2014

Laser aided Direct Metal Tooling(DMT) process is a kind of Additive Manufacturing processes (or 3D-Printing processes), which is developed for using various commercial steel powders such as P20, P21, SUS420, H13, D2 and other non-ferrous metal powders, aluminum alloys, titanium alloys, copper alloys and so on. The DMT process is a versatile process which can be applied to various fields like the mold industry, the medical industry, and the defense industry. Among of them, the application of DMT process to the mold industry is one of the most attractive and practical applications since the conformal cooling channel core of injection molds can be fabricated at the slightly expensive cost by using the hybrid fabrication method of DMT technology compared to the part fabricated with the machining technology. The main objectives of this study are to provide various characteristics of the parts made by DMT process compared to the same parts machined from bulk materials and prove the performance of the injection mold equipped with the conformal cooling channel core which is fabricated by the hybrid method of DMT process.

• 한국산학기술학회논문지
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• 제10권8호
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• pp.2126-2133
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• 2009

세계적으로 로봇산업이 거대시장으로 급성장할 것으로 예상되면서, 많은 국가에서 정책적으로 로봇산업 발전을 추진하고 있다. 이러한 추세에 발맞춰 대한민국에서도 정부의 전략적 주도하에 다양한 분야에서의 로봇개발이 수행되고 있다. 이러한 연구개발 프로그램들은 산학협력을 통해 이루어지고 있으며, 더 나아가 기업의 애로기술을 해소하기 위한 기술적인 지원 및 교육을 추구하는 인력양성 및 산학협력 확산 연계 프로그램을 포함하고 있다. 본 논문에서는 이러한 산학협동 프로그램의 잠정적인 성과에 대해 논하였다. 우선 차세대 특성화 계획에 포함된 각각의 프로그램을 설명하고, 로봇 개발과 관련한 인력양성의 성과를 평가하였다. 마지막으로 이러한 프로그램들의 지속적이고 바람직한 발전을 위한 방안을 고찰하였다.

• Journal of Welding and Joining
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• 제35권1호
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• pp.16-25
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• 2017

Gas Metal Arc Welding is a widely used process in Industry due to its high productivity and potential to automation. The present study investigates the effects of the welding speed, arc voltage, welding current and shielding gas on the bead geometry for a low-carbon steel. The Response Surface Methodology (RSM) is used to choose an experimental design and perform test runs accordingly in order to produce mathematical models predicting the geometry, the hardness and the heat input of the bead as functions of the welding parameters. The direct and interaction effects of the four welding parameters are represented graphically and allow to determine an optimum set of welding parameters.

• 반도체디스플레이기술학회지
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• 제14권1호
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• pp.67-71
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• 2015

Pulse electroplating was studied to form nanocrystal structure effectively by changing plating current density and duty cycle. When both of plating current density and duty cycle were decreased from $100mA/cm^2$ and 70% to $50mA/cm^2$ and 30%, the P content in the Ni matrix was increased almost up to the composition of $Ni_3P$ compound and the grain growth after annealing was retarded as well. The as-plated hardness values ranging from 660 to 753 HV are mainly based on the formation of nanocrystal structure. On the other hand, the post-anneal hardness values ranging from 898 to 1045 HV, which are comparable to the hardness of hard Cr, are coming from how competition worked between the precipitation of $Ni_3P$ and the grain coarsening. According to the ANOVA and regression analysis, the plating current density showed more strong effect on nanocrystal size and film hardness than the duty cycle.

• Journal of Advanced Marine Engineering and Technology
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• 제27권4호
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• pp.503-510
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• 2003

A new method of induction motor drive, which requires neither shaft encoder nor speed estimator, is presented. The proposed scheme is based on decreasing current gap between a numerical model and an actual motor. By supplying the identical instantaneous voltage to both model and motor in the direction of reducing the current difference. the rotor approaches to the model speed. that is. reference value. The indirect field orientation algorithm is employed for tracking the model currents. The performance of induction motor drives without speed sensor is generally characteristic of poorness at very low speed. However, in this system, it is possible to obtain good speed response in the extreme low speed range.