• Transactions of Materials Processing
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• v.31 no.3
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• pp.124-128
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• 2022

NdFeB magnets have been positioned as the core materials in advanced technologies such as MRI (magnetic resonance imaging), FA (factory automation system), robot, motors, and so on based on the highest magnetic properties. To effectively improve the refined microstructure, the plastic deformation has been known as the good alternatives by the recrystallization. However, it has been regarded as being impossible because of the few slip systems in the RE-Fe-B magnets at room temperature. The purpose of this study was to investigate the possibility of control of grain refinement and magnetic anisotropy of NdFeB alloy powder by the severe plastic deformation. The NdFeB magnet powder was fabricated by gas atomization process, and the powder was pre-compacted at high temperature. The pre-compacted billets were deformed by HPT (high pressure torsion), and then the deformed billets were observed microstructure and magnetic properties. After the HPT process at room temperature, the grain size decreased with increasing because of the melted Nd-rich phase, and the anisotropy of Nd₂Fe₁₄B phase was formed after the HPT process.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2017.04a
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• pp.149-149
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• 2017

본 논문은 생산라인 자동화를 위한 로봇으로 제조업 시장 확대에 가장 큰 걸림돌이 되는 가격 경쟁력 및 인력난 해소를 위해 설계하였으며 다양한 소재에 대응하기 위해 그리퍼를 교체하여 적용이 되도록 하였다. 자동화를 위한 로봇은 소재의 내외경 가공 및 검사까지 모든 공정이 일괄적으로 이루어 져야하며 LCD 모니터에 생산수량 및 불량률 등의 정보를 실시간으로 나타내어 효율적인 생산계획을 수립할 수 있도록 하였다. 생산라인 자동화를 위해 로봇의 설계는 Auto CAD를 이용하였다. 부품의 가공은 CNC에 적용하기 위해 자동공급장치를 설계하였다. 가공이 완료된 후 측정한 값을 LCD모니터를 통하여 작업자가 알아볼 수 있게 나타냈다. 외경 1은 40.405, 외경2는 32.201, 내경 1은 23.346, 내경 2는 34.302로 나타났다. 측정결과 불량 측정을 위해 측정부의 결과 값이 나타나며 불량이 발생하면 그래프를 이용하여 어떤 부위에서 발생했는지를 알 수 있도록 하였다. 또한 결과 값은 자동으로 저장되도록 하였다. 생산라인 자동화를 위해 100EA를 측정한 결과 외경 1은 40.40438, 외경2는 32.20164, 내경 1은 23.34830 내경 2는 34.30033의 평균값을 나타냈다. 측정값의 검증은 하이트게이지로 측정한 결과 0.003 이내의 결과를 나타냈다. 따라서 본 로봇 자동화 시스템을 적용한다면 생산성 향상 및 불량률 감소가 가능하여 인력대체 및 가격경쟁력이 가능하다고 판단된다.

• Journal of the Korea Society of Computer and Information
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• v.22 no.1
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• pp.63-69
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• 2017

In this paper, we propose a method to optimize the geometry and installation position of the mixer in the selective catalytic reduction (SCR) system by computational fluid dynamic(CFD). Using the commercial CFD software of CFD-ACE+, the flow dynamics of the flue gas was numerically analyzed for improving the injection uniformity of the reduction agent. Numerical analysis of the mixed gas heat flow into the upstream side of the primary SCR catalyst layer was performed when the denitrification facility was operated. The characteristics such as the flow rate, temperature, pressure loss and ammonia concentration of the mixed gas consisting of the flue gas and the ammonia reducing gas were examined at the upstream of the catalyst layer of SCR. The temperature difference on the surface of the catalyst layer is very small compared to the flow rate of the exhaust gas, and the temperature difference caused by the reducing gas hardly occurs because the flow rate of the reducing gas is very small. When the mixed gas is introduced into the SCR reactor, there is a slight tendency toward one wall. When the gas passes through the catalyst layer having a large pressure loss, the flow angle of the exhaust gas changes because the direction of the exhaust gas changes toward a smaller flow. Based on the uniformity of the flow rate of the mixed gas calculated at the SCR, it is judged that the position of the test port reflected in the design is proper.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.1
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• pp.67-76
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• 2011

An exact curved path has to be fixed and velocity profile for travelling on the curved path is required by a moving stage. In this study, we decide the curved path on the basis of the information on three point locations. The path of the moving stage is traced by simulating the designed curve path and the velocity profile, and the results are compared with the given three points to determine how closely the moving stage follows the given path. Further, we propose a method to calibrate a curved path and velocity profile. The proposed moving paths were evaluated by performing experiments. Finally, the designed curved path and the actual path were compared.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.12
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• pp.8753-8759
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• 2015

Establishment of analysis procedures and validated performance measurements for generator output is required to maintain stable management of generator output in turbine power generation cycle. We developed turbine expansion model and measurement validation model for the performance calculation of generator using turbine output based on ASME (American Society of Mechanical Engineers) PTC (Performance Test Code). We also developed verification model for uncertain measurement data related to the turbine and generator output. Although the model in previous researches was developed using artificial neural network and kernel regression, the verification model in this paper was based on algorithms through Support Vector Machine (SVM) model to overcome the problems of unmeasured data. The selection procedures of related variables and data window for verification learning was also developed. The model reveals suitability in the estimation procss as the learning error was in the range of about 1%. The learning model can provide validated estimations for corrective performance analysis of turbine cycle output using the predictions of measurement data loss.

• Journal of the Microelectronics and Packaging Society
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• v.20 no.2
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• pp.23-28
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• 2013

Microlens array as basic element of the optical system have been fabricated with various focal length (mainly with long focal length) depending on the purpose of application. In this paper, the microlens arrays were fabricated for observing fluorescent images within sol-gel. Though the fluorescent signal is very low, the microlens array can help obtaining clear images through extracting the fluorescent light from sol-gel. We fabricated microlens arrays with short focal length, which can extract the light using photoresist thermal reflow method. In the experiment, the diameter of microlens decreased after thermal reflow because the solvent within the photoresist was vaporized. Therefore, to compensate the shape error by this reduction, microlens diameter in photomask was altered and spin-coat recipe of photoresist were modified.

• The Journal of Korean Institute for Practical Engineering Education
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• v.3 no.1
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• pp.143-148
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• 2011

In this study, the damage to the bridge structure such as the crack and water leakage was assessed due to the increase of the vehicle load and traffic on the roads. In order to make this into the database, as a part of the automation system development for the bridge maintenance, the students themselves designed and developed their own inspection robotic system based on the idea of robots currently being developed overseas. Its field testing was conducted and its applicability assessed. During the design and fabrication, its connection to the details of the unit course taken in the undergraduate level was focused. In terms of new product development, the field application was possible due to the support of the academic-industrial cooperation firms. Furthermore, through the survey of the students, the improvements in the practical skills of the students who participated in this development process was affirmed.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.6
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• pp.815-820
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• 2013

With the development of technology, there has been a considerable increase in the number of skyscrapers in the world. Accordingly, there are increasing requirements with regard to maintenance, such as cleaning, painting, and inspection. However, it is extremely dangerous to work on the walls of buildings, and falls from buildings have accounted for a large proportion of construction accidents. In particular, as the number of buildings with irregular shapes increases, the accident rate during maintenance work has increased each year, with most accidents leading to deaths. An alternative solution must be developed with the commercialization of automatic systems. In this study, fundamental research has been conducted for drafting and commercializing an automation tool with a built-in guide system that can perform cleaning.

• Journal of Bio-Environment Control
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• v.18 no.2
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• pp.95-100
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• 2009

This study was conducted to develop an imaging processing system of inoculation processing of a lily callus. The image processing system was composed of a camera, a image processing board, and etc. And the illuminance always decided by setting up 55W/3 wavelength lamp respectively on all aspects and the side was maintained by the lighting part. The image characteristic was examined according to each frame of RGB,therefore the culture vessel was able to be separated with B frame. The required time was 2.2 seconds in one cycle from the image acquisition to obtaining the result. The recognition rate of the container was 100%, and the result of image processing showed that the recognition success rate of lily callus was 93%.

• Journal of Energy Engineering
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• v.23 no.4
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• pp.263-271
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• 2014

Corrective thermal performance analysis is required for thermal power plants to determine performance status of turbine cycle. We developed classification method for main feed water flow to make precise correction for performance analysis based on ASME (American Society of Mechanical Engineers) PTC (Performance Test Code). The classification is based on feature identification of status of main water flow. Also we developed predictive algorithms for corrected main feed-water through Support Vector Machine (SVM) Model for each classified feature area. The results was compared to estimations using Neural Network(NN) and Kernel Regression(KR). The feature classification and predictive model of main feed-water flow provides more practical methods for corrective thermal performance analysis of turbine cycle.