• Journal of Korea Society of Digital Industry and Information Management
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• v.17 no.3
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• pp.9-15
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• 2021

In this paper, the Embedded MEMS system to the power apparatus used Edge Impulse machine learning tools and therefore an improved predictive system design is implemented. The proposed MEMS embedded system is developed based on nRF52840 system and the sensor with 3-Axis Digital Magnetometer, I2C interface and magnetic measurable range ±120 uT, BM1422AGMV which incorporates magneto impedance elements to detect magnetic field and the ARM M4 32-bit processor controller circuit in a small package. The MEMS embedded platform is consisted with Edge Impulse Machine Learning and system driver implementation between hardware and software drivers using SensorQ which is special queue including user application temporary sensor data. In this paper by experimenting, TensorFlow machine learning training output is applied to the power apparatus for analyzing the status such as "Normal, Warning, Hazard" and predicting the performance at level of 99.6% accuracy and 0.01 loss.

• Journal of Korean Tunnelling and Underground Space Association
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• v.17 no.2
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• pp.175-187
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• 2015

In this paper, the development of trench shield machine for near-surface railway construction were presented. The Near-surface railway can be constructed by cut and cover construction method, because it is installed at the depth of 5~7 m below roads. The cut and cover construction method mostly use temporary supports. The limitation of the cut and cover method is high installation cost and long construction period. To overcome these disadvantages, development of the trench shield machine is proposed and expected to shorten the construction time and cost of near-surface railway system. The sliding retaining wall of trench shield equipment replaces the role of temporary support (solider piles and lagging) and excavator equiped to the bottom front of the machine shorten the excavation time. This paper deals with design of the bit attached to the excavator and required capacity of the motor.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.10
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• pp.121-127
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• 2018

A system for diagnosing surface defects of long and large pipe inner overlay welds, 1m in diameter and 6m in length, was developed using a Liquid Penetrant Test (PT). First, CATIA was used to model all major units and PT machines in 3-dimensions. They were used for structural strength analysis and strain analysis, and to check the motion interference phenomenon of each unit to produce two-dimensional production drawings. Structural strength analysis and deformation analysis using the ANSYS results in a maximum equivalent stress of 44.901 MPa, which is less than the yield tensile strength of SS400 (200 MPa), a material of the PT Machine. An examination of the performance of the developed equipment revealed a maximum travel speed of 7.2 m/min., maximum rotational speed of 9 rpm, repeatable position accuracy of 1.2 mm, and inspection speed of $1.65m^2/min$. The results of the automatic PT-inspection system developed to check for surface defects, such as cracks, porosity, and undercut, were in accordance with the method of ASME SEC. V&VIII. In addition, the results of corrosion testing of the overlay weld layer in accordance with the ferric chloride fitting test by the method of ASME G48-11 indicated that the weight loss was $0.3g/m^2$, and met the specifications. Furthermore, the chemical composition of the overlay welds was analyzed according to the method described in ASTM A375-14, and all components met the specifications.

• Food Engineering Progress
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• v.21 no.2
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• pp.110-115
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• 2017

This study aimed to identify milling characteristics depending on the number of a cutting roller's air vent and blowing velocity to remove rice bran by the cutting type milling machine which can minimize the conventional milling process. The level of whiteness was found to be $38{\pm}0.5$ in all the conditions, showing consistent whiteness levels during milling. The rice temperatures turned out to be 15.4 and $14.6^{\circ}C$ which were rather low-level under the conditions of the cutting roller with 3 vents and blowing velocities of 35 and 40 m/s respectively. Cracked rice ratio was 2.13% under the conditions of the cutting roller with 3 vents and a blowing velocity of 35 m/s. Broken rice ratio showed the range of 0.762-0.869%, reflecting a low level. Turbidity after milling was decreased, as blowing velocity became faster. Energy consumption for milled rice production was decreased, as blowing velocity became faster. The optimum milling condition for cutting type milling machine depending on air vent number of cutting roller and blowing velocity was found to be 3 vents and 35 m/s.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.769-772
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• 2005

Five DOF motion errors of a hydrostatic bearing table driven by the coreless type linear motor were compensated utilizing the active controlled capillaries in this study. Horizontal linear motion and yaw error were simultaneously compensated using two active controlled capillaries and vertical linear motion, pitch and yaw error were also simultaneously compensated using three active controlled capillaries. By the compensation, horizontal linear motion accuracy and yaw were improved from 0.16 ${\mu}m$ and 1.96 arcsec to 0.02 ${\mu}m$ and 0.03 arcsec. Vertical linear motion accuracy, pitch and roll were also largely improved from 0.18 ${\mu}m$, 2.26 arcsec and 0.14 arcsec upto 0.03 ${\mu}m$, 0.07 arcsec and 0.02 arcsec. The compensated motion errors were within the range of measuring repeatability which was ${\pm}0.02\;{\mu}m$ in the linear motion and ${\pm}0.05$ arcsec in the angular motion. From these results, it is found that the motion error compensation method utilizing the active controlled capillaries are very effective to improve the five motion accuracies of the hydrostatic bearing tables.

• Information and Communications Magazine
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• v.30 no.7
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• pp.58-62
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• 2013

최근에 ICT 기반의 융합 서비스 분야로 인구 밀집지역인 메가 시티에서의 교통, 전력, 상/하수도, u-헬스, 안전/보안등의 문제들을 근본적으로 해결하기 위하여 ICT기반 개방형 플랫폼을 이용한 서비스 인프라 구축 및 개선을 위한 연구들이 많이 진행되고 있다. 이러한 ICT 기반의 융합 인프라 구축 서비스들은 M2M(Machine to Machine)과 D2D(Device to Device)를 기본 연결 수단으로 사용하고 있으며, 이들을 기반으로 서비스 정보 전달 및 제어 정보를 실시간으로 처리하기 위한 IP 기반의 플랫폼이 지원되어야만 융합 서비스가 지속적으로 제공 가능할 것이다. 이들 융합서비스 중에서 전력과 관련하여 한국의 스마트그리드 사업은 기후 변화 대응을 위하여CO2 배출을 줄이고, 에너지 효율을 향상하여 새로운 비즈니스 모델을 만들어 일자리와 신산업을 창출하기 위한 국가 프로젝트로 진행되었다. 그러나, 현재의 전력관련 국내 상황을 살펴보면 여름철과 겨울철에 반복적인 전력 수급 불안으로 인해 피크 전력에 대한 예비력이 부족하여 국가적인 재난인 블랙 아웃의 위기를 걱정하고 있는 실정이다. 본고에서는 한국의 스마트그리드 제주실증단지 사업과 관련하여 현황 및 개선 사항들을 알아보고, 향후 거점지구와 국가 단위의 서비스 확장을 위하여ICT 기반의 개방형 인프라 플랫폼 기술의 중요성을 강조하고자 한다. 이러한 M2M과 D2D를 기반으로 하는 융합 서비스의 성공적인 수행은ICT 기반의 개방형 플랫폼의 우선적인 개발이 필요하며, 플랫폼 기반의 디바이스 보급과 네트워크의 구축이 진행되어야 지속 가능한 융합 서비스를 제공할 수 있을 것이다.

• Journal of Service Research and Studies
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• v.2 no.1
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• pp.61-68
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• 2012

Much technologies building cloud computing environment and supporting sevices on the cloud computing have been developing. Through the environment, accessing new services and sharing knowledge become easy. So far, they have just focused on companies which can support services and people who can use those services. In other words, the environment and models for cloud computing are the most important issue. However, the environment changes rapidly, mobile devices that are connected with each other not only will replace the computing environment based on desktop, but also can create Big data. Therefore, technologies and models are need to follow the trend including mobile based cloud computing environment. In this paper, we explain the cloud computing technologies and trend. Also we address Machine to Machine(M2M) technology and Web of things(WoT) in order to apply those into the cloud computing environment because these two concepts will enhance effectiveness and service reusability in the coming days.

• Safety and Health at Work
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• v.8 no.1
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• pp.105-115
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• 2017

Background: The goal of this study is to develop a general population job-exposure matrix (GPJEM) on asbestos to estimate occupational asbestos exposure levels in the Republic of Korea. Methods: Three Korean domestic quantitative exposure datasets collected from 1984 to 2008 were used to build the GPJEM. Exposure groups in collected data were reclassified based on the current Korean Standard Industrial Classification ($9^{th}$ edition) and the Korean Standard Classification of Occupations code ($6^{th}$ edition) that is in accordance to international standards. All of the exposure levels were expressed by weighted arithmetic mean (WAM) and minimum and maximum concentrations. Results: Based on the established GPJEM, the 112 exposure groups could be reclassified into 86 industries and 74 occupations. In the 1980s, the highest exposure levels were estimated in "knitting and weaving machine operators" with a WAM concentration of 7.48 fibers/mL (f/mL); in the 1990s, "plastic products production machine operators" with 5.12 f/mL, and in the 2000s "detergents production machine operators" handling talc containing asbestos with 2.45 f/mL. Of the 112 exposure groups, 44 groups had higher WAM concentrations than the Korean occupational exposure limit of 0.1 f/mL. Conclusion: The newly constructed GPJEM which is generated from actual domestic quantitative exposure data could be useful in evaluating historical exposure levels to asbestos and could contribute to improved prediction of asbestos-related diseases among Koreans.

• International Journal of Precision Engineering and Manufacturing
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• v.1 no.1
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• pp.111-117
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• 2000

One of the major limitations of productivity and quality in metal cutting is the machining accuracy of machine tools. The machining accuracy is affected by geometric errors, thermally-induced errors, and the deterioration of the machine tools. Geometric and thermal errors of machine tools should be measured and compensated to manufacture high quality products. In metal cutting, the machining accuracy is more affected by thermal errors than by geometric errors. This paper models the thermal errors for error analysis and develops an on-the-machine measurement system by which the volumetric errors are measured and compensated. The thermal error is modeled by means of angularity errors of a column and thermal drift error of the spindle unit which are measured by the touch probe unit with a star type styluses and a designed spherical ball artifact (SBA). Experiments show that the developed system provides a high measuring accuracy, with repeatability of $\pm$2$\mu\textrm{m}$ in X, Y and Z directions. It is believed that the developed measurement system can be also applied to the machine tools with CNC controller. In addition, machining accuracy and product quality can be also improved by using the developed measurement system when the spherical ball artifact is mounted on a modular fixture.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1228-1231
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• 2005

This paper reports about the development of scanning probe microscopy (SPM) tip with multi-walled carbon nanotube (MWNT). For making a carbon nanotube (CNT) modified tips, AC electric field which causes the dielectrophoresis was used for alignment and deposition of CNTs to the metal coated SPM tip. By dropping the MWNT solution and applying an electric field between an SPM tip and an electrode, MWNTs which were dispersed into a diluted solution were directly assembled onto the apex of the SPM tips due to the attraction by the dielectrophoretic force. In this paper, we investigate experimental conditions about the alignment of the CNT to tip axis according to the change of the angle between a tip and an electrode. Experimental results are presented, and then fabricated CNT tips are showed and measurement results for 15nm gold particles are compared with that of the conventional silicon tip.