• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.08a
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• pp.78-87
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• 1999

A mathematical model for the stress free surface profile in Over-Round and Round-Oval grove rolling, which can be used effectively in the calculation of pass area, is presented. The new model has generality, simplicity and accuracy for practical usage. The stress free surface profile of an outgoing stock can be modeled when the maximum spread of it known a priori. The equation for the stress free surface profile is formulated from the linear interpolation of the radius of curvature of an incoming stock and that of roll groove to the axis direction. In developing the analytical model, the effect of rolling temperature and friction between roll and work piece(stock) were not considered since the geometry of roll groove and the incoming work piece were assumed a dominant factor which decides the stress free surface profile of the outgoing stock. A simulation with the analytical model developed also has been carried out to demonstrate the stress free surface profile of the outgoing stock.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.9
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• pp.1516-1521
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• 2008

Recently, distribution load analysis using AMR (Automatic Meter Reading) data is researched in electric utilities. Load analysis method based on AMR system generates the typical load profile using load data of AMR customers, estimates the load profile of non-AMR customers, and analyzes the peak load and load profile of the distribution circuits and sectors per every 15 minutes/hour/day/week/month. Typical load profile is generated by the algorithm calculating the average amount of power consumption of each groups having similar load patterns. Traditional customer clustering mechanism uses only contract type code as a key. This mechanism has low accuracy because many customers having same contract code have different load patterns. In this research, We propose a customer clustring mechanism using k-means algorithm with contract type code and AMR data.

• Journal of Korea Multimedia Society
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• v.9 no.12
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• pp.1709-1718
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• 2006

Users are able to use the information and service more free than previous wire network due to development of wireless network and device. For this reason, various studies on ubiquitous networks have been conducted. Various contexts brought in this ubiquitous environment, have recognized user's action through sensors. This results in the provision of better services. Because services exist in various places in ubiquitous networks, the application has the time of services searching. In addition, user's context is very dynamic, so a method needs to be found to recommend services to user by context. Therefore, techniques for reducing the time of service and increasing accuracy of recommendation are being studied. But it is difficult to quickly and appropriately provide large numbers of services, because only basic context information is stored. For this reason, we suggest DUPS(Dimension User Profile System), which stores location, time, and frequency information of often used services. Because previous technique used to simple information for recommending service without predicting services which is going to use on future, we can provide better service, and improve accuracy over previous techniques.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.12
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• pp.1765-1773
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• 2012

The accuracy of load forecast is very important from the viewpoint of economical power system operation. In general, the weekdays' load demand pattern has the continuous time series characteristics. Therefore, the conventional methods expose stable performance for weekdays. In case of special days or weekends, the load demand pattern has the discontinuous time series characteristics, so forecasting error is relatively high. Especially, weekdays near the thanksgiving day and lunar new year's day have the mixed load profile characteristics of both weekdays and weekends. Therefore, it is difficult to forecast these days by using the existing algorithms. In this study, a new load forecasting method is proposed in order to enhance the accuracy of the forecast result considering the characteristics of weekdays and weekends. The proposed method was tested with these days during last decades, which shows that the suggested method considerably improves the accuracy of the load forecast results.

• Journal of Positioning, Navigation, and Timing
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• v.8 no.2
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• pp.59-68
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• 2019

This paper proposed a method to estimate the vertical delay from the slant delay, which can improve accuracy of the ionospheric correction of SBAS. Proposed method used Chapman profile which is a model for the vertical electron density distribution of the ionosphere. In the proposed method, we assumed that parameters of Chapman profile are given and the vertical ionospheric can be modeled with linear function. We also divided ionosphere into multi-layer. For the verification, we converted slant ionospheric delays to vertical ionospheric delays by using the proposed method and generated the ionospheric correction of SBAS with vertical delays. We used International Reference Ionosphere (IRI) model for the simulation to verification. As a result, the accuracy of ionospheric correction from proposed method has been improved for 17.3% in daytime, 10.2% in evening, 2.1% in nighttime, compared with correction from thin shell model. Finally, we verified the method in the SBAS user domain, by comparing slant ionospheric delays of users. Using the proposed method, root mean square value of slant delay error decreased for 23.6% and max error value decreased for 27.2%.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.26 no.6
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• pp.583-590
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• 2008

In construction work's design process, we must carry out a topographical survey for construction reserved land and to the basis of this, production of profile is indispensable factor for the purpose of every construction work such as road, rail way, canal and etc. From this research, the production of profile about construction reserved land, using topographical information of digital topographical map produced by NGIS project, construct precision 3D terrain model and from this, propose plans for utilizing by producing automatic profile. With the aim of this, extract every layers of main facilities and altitude from digital topographical map and while producing 3D terrain model by using this, we product automatic profile from precision 3D terrain model. And we was carried out to check whether the automatic produced profile's accuracy could be accepted at actual estimation by mutual analysis. It is considered that the result of the research could be suggested as a new techniques concept which can reduce the designing period and expenses and increase the efficiency of affair in the design process for the construction.

• The Journal of the Korean dental association
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• v.41 no.3 s.406
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• pp.180-189
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• 2003

The purpose of this study was to evaluate the accuracy of the soft tissue profile predicted by Quick Ceph Image Pro in mandibular setback surgery. Preoperative and postoperative lateral cephalograms of 24 patients(9 males and 15 females) who had completed treatment that involved orthodontics and mandibular setback by BSSRO were used. Computerized cephalometric lines and video image predictions were generated and compared with the actual postoperative results. In horizontal measurement, predicted values were smaller than actual measurements. And lips were thicker than actual values. Most of the different between values and actual measurement were than 2mm, and it was clinically acceptable.

• Proceedings of the KIEE Conference
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• 1988.07a
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• pp.683-686
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• 1988

In the recognition of similar patterns like profile contours of human faces, feature measure plays important role. We extracted effective and general feature by B-spline approximation. The nodes and vertices of the approximated curve are normalized and used as features. Since the features have both local property of curvature extrema and global property by B-spline approximation, they are superior to those of curvature extrema of the profile contour. For the image data of six sets of 56 persons, some of which are ill-made, averaged accuracy rate of 97.6 % is obtained in recognizing combinational 333 test samples.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.5 no.4
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• pp.108-120
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• 1996

A new technique and theory are proposed which correct orientation of a cylinder to perform a reliable measurement of the surface profile. We analyze characteristics of machined surfaces, e.g., ground, lapped and turned surfaces. Based upon the results. the optimum correction technique is derived by the statistical method. To verify the techinques, measurements are carried out by using the contact stylus profilometer on a controllable table. The measurement shows that surface information of cylinders can be acquired with high accuracy.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.05a
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• pp.213-216
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• 2008

Sled test id widely used to evaluate the performance of occupant's safety system in frontal crash environment without having to conduct a full-scale crash test. Steel bar breaking system is used to generate deceleration profile which is experienced by passengers in frontal crash. In this study, deformation analyses of steel bars were conducted using a commercial FE code. Several guidelines were proposed to improve the accuracy of simulation.