• Journal of the Korean Society for Precision Engineering
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• v.12 no.7
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• pp.19-25
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• 1995

Presently, along with the advance of high-technology, the precise measurement of linear displacement has become a staple requirement, and consequently the high resolution with submicron order has also been required in precise positioning and carriaging. In this paper, we advance a propose on a new type of laser encoder based on the principle of phase analysis of the moire fringes from superimposed two gratings. The phase angle as an information of displacement can be accurately calculated by detecting the change in brighness at four points of the fringes. The actual application of four point method to the moire fringes is performed thru microcomputer for general purpose, and the measuring procedure is also studied in this research. As an experimental result, in the case of using 20 .mu. m-pitch gratings, it is validated that this method has the resolution of 0.01 .mu. m and the accuracy of .+-. 0.15 .mu. m over the setting range of 100mm.

• Convergence Security Journal
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• v.15 no.4
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• pp.27-33
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• 2015

In this paper, the development level of information security technology for internet of things(Iot), big data and clo ud services is analyzed, and the detail policy is proposed to be leader in area of patents and ICT standard. The conc ept of ICT convergence is defined frist, market and current state of technology for three convergence services is the n analyzed, and finally main function and security target for each technology are presented. The evaluation criteria a nd IPR are analyzed to diagnose the level of patent and standard for the technology. From the results, even though the domestic competence is inferior compared to other advanced country, the efficient policy should be presented by using our capability for the big data and cloud. Furthermore, the technology development for the IoT and cloud is ne eded in advance considering the market-technology influence effects. In addition to, M2M security framework in IoT, data security in big data and reliable networking in cloud should be developed in advance.

• Journal of Magnetics
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• v.18 no.4
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• pp.400-404
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• 2013

Grain boundary diffusion technique with $DyH_3$ nanoparticles was applied to fabricate Dy-less sintered Nd-Fe-B permanent magnets with high coercivity. The magnetic properties and microstructure of magnets were systematically studied. The coercivity and remanence of grain boundary diffusion magnet were improved by 60% and reduced by 7% compared with those of the original magnet, respectively. Meanwhile, both the remanence temperature coefficient (${\alpha}$) and the coercivity temperature coefficient (${\beta}$) of the magnets were improved after diffusion treatment. Investigation shows that Dy is preferentially enriched as (Nd, Dy)$_2Fe_{14}B$ phase in the surface region of the $Nd_2Fe_{14}B$ matrix grains indicated by the remarkable enhancement of the magneto-crystalline anisotropy field of the magnet. As a result, the magnet diffused with a small amount of Dy nanoparticles possesses enhanced coercivity without remarkably sacrificing its magnetization.

• Tunnel and Underground Space
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• v.30 no.6
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• pp.540-550
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• 2020

Machine learning has been actively used in the field of automation due to the development and establishment of AI technology. The important thing in utilizing machine learning is that appropriate algorithms exist depending on data characteristics, and it is needed to analysis the datasets for applying machine learning techniques. In this study, advance rate is predicted using geotechnical and machine data of TBM tunnel section passing through the soil ground below the stream. Although there were no problems of application of statistical technology in the linear regression model, the coefficient of determination was 0.76. While, the ensemble model and support vector machine showed the predicted performance of 0.88 or higher. it is indicating that the model suitable for predicting advance rate of the EPB Shield TBM was the support vector machine in the analyzed dataset. As a result, it is judged that the suitability of the prediction model using data including mechanical data and ground information is high. In addition, research is needed to increase the diversity of ground conditions and the amount of data.

• Journal of the Korean housing association
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• v.23 no.6
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• pp.11-20
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• 2012

This Study developed library of parts, applied with 3-dimension character which has width, length and height and a reference plane, for the system development of BIM design on housing unit modular. The current BIM software has not the concept of a reference plane or work tolerance in modular, so the development of parts library applied to unit modular has not moved forward. So, we developed, in this study, parts library applied to windows, built-in-furniture, kitchen systems and knock down bathrooms, with a reference plane and work tolerance based on single roon prototype on urban-life-housings. BIM library can utilize changed size and work tolerance of parts, and fabricating reference plane will be created automatically when an engineer puts work tolerance in the BIM library with supplement of some category related to work reference. Through this BIM library development, we consider the part module can be used for housing complex planning, and architectural designers will be able to utilize the BIM library for housing complex design.

• Journal of the Korean Society for Nondestructive Testing
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• v.33 no.3
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• pp.283-288
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• 2013

This paper describes development of a high speed Doppler OFDI system for non-invasive vascular imaging. Doppler OFDI (optical frequency domain imaging) is one of the phase-resolved second generation OCT (optical coherence tomography) techniques for high resolution imaging of moving elements in biological tissues. To achieve a phase-resolved imaging, two temporally separated measurements are required. In a conventional Doppler OCT, a pair of massively oversampled successive A-lines is used to minimize de-correlation noise at the expense of significant imaging speed reduction. To minimize a de-correlation noise between targeted two measurements without suffering from significant imaging speed reduction, several methods have been developed such as an optimized scanning pattern and polarization multiplexed dual beam scanning. This research represent novel imaging technique using frequency multiplexed dual beam illumination to measure exactly same position with aimed time interval. Developed system has been verified using a tissue phantom and mouse vessel imaging.

• Journal of Korea Society of Digital Industry and Information Management
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• v.6 no.4
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• pp.57-65
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• 2010

Application of WBAN technology in medical field facilitates the prevention of diseases by collecting the vital signs remotely. It also enables to prevent the accidental emergency situation in advance plus long-tem monitoring of patients with chronic diseases such as heart diseases, hypertension, or the elderly and infirm. For emergency patients, major vital signal information collected by the 'Sensing' should have the top priority and such information should be transferred as promptly as possible without competition. In addition, when an emergency occurs to a patient, a priority mechanism is necessitated for a urgent message to get through to the final destination. However, LR-WPAN IEEE 802.15.4 technology does not consider such emergency message handling features. To deal with aforementioned issues, the IEEE 802.15.4 super frame protocol structure has been designed for stable transfer of emergency information in WBAN environment in this study, and alternation to super frame structures have been made, allowing GTS(Guaranteed Time Slot) can be used first at CFP (Contention Free Period) by reserving the resources in advance and prioritize the emergency signals. NS-2 has been utilized for the performance test and analysis.

• International Journal of Naval Architecture and Ocean Engineering
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• v.5 no.2
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• pp.287-301
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• 2013

The present paper deals with the problems of yaw angle effects on podded propulsor performance. The study aims at providing insights on characteristics of podded propulsors in azimuthing condition. In this regard, a wide numerical simulation that concerned yaw angle effect measurement on podded propeller performance was performed. The Reynolds-Averaged Navier Stokes (RANS) based solver is used in order to study the variations of hydrodynamic characteristics of podded propulsor at various angles. At first, the propeller is analyzed in open water condition in absence of pod and strut. Next flow around pod and strut are simulated without effect of propellers. Finally, the whole unit is studied in zero yaw angle and azimuthing condition. Structured and unstructured mesh techniques are used for single propeller and podded propulsor. The performance curves of the propeller obtained by numerical method are compared and verified by the experimental results. The characteristic parameters including the torque and thrust of the propeller, the axial force and side force of unit are presented as function of velocity advance ratio and yaw angle. The results shows that the propeller thrust, torque and podded unit forces in azimuthing condition depend on velocity advance ratio and yaw angle.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.3
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• pp.22-27
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• 2006

As the regulation and assessment program for safety of passengers become stringent, automakers are required to develop lighter and safer vehicles. In order to fulfill both requirements which conflict with each other, automobile and steel companies have proposed the application of AHSS(Advance High Strength Steel) such as DP, TRIP and martensite steel. ULSAB-AVC model is one of the most remarkable reactions to offer solutions with the use of steel for the challenge to improve simultaneously the fuel efficiency, passenger safety, vehicle performance and affordability. This paper is concerned with the crash analysis of ULSAB-AVC model according to the US-SINCAP in order to compare the effectiveness between the model with AHSS and that with conventional steels. The crashworthiness is investigated by comparing the deformed shape of the cabin room, the energy absorption characteristics and the intrusion velocity of a car.

• Journal of the Korea Society of Computer and Information
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• v.12 no.1 s.45
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• pp.99-106
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• 2007

In order to make new productions; first of all, a creative idea is necessary and significance. For developing new production, a creative thinking must be a first step. In other words, a creative thinking can be a solving a problem. Better education for the formal and unformal education, various information and using space are able to develop ability of problems. Group study can students can find their talents, capacity, gifts, and ability. Also, students help to develop ideas of an individual. Therefore, through an effort to advance computer technology, developing food models in creative ideas for formal and informal education. As a result. good efforts and aspects can be produced.