• Journal of the Korea Safety Management & Science
• /
• v.14 no.1
• /
• pp.217-224
• /
• 2012

Location-Based Services(LBS) is a service that provide location information by using communication network or satellite signal. In order to provide LBS precisely and efficiently, we studied how we can reduce the error on location determination of objects such people and things. We focus on using the least square method and triangulation positioning method to improves the accuracy of the existing location determination method. Above two methods is useful if the distance between the AP and the tags can be find. Though there are a variety of ways to find the distance between the AP and tags, least squares and triangulation positioning method are wildely used. In this thesis, positioning method is composed of preprocessing and calculation of location coordinate and detail of methodology in each stage is explained. The distance between tag and AP is adjusted in the preprocessing stage then we utilize least square method and triangulation positioning method to calculate tag coordinate. In order to confirm the performance of suggested method, we developed the test program for location determination with Labview2010. According to test result, triangulation positioning method showed up loss error than least square method by 38% and also error reduction was obtained through adjustment process and filtering process. It is necessary to study how to reduce error by using additional filtering method and sensor addition in the future and also how to improve the accuracy of location determination at the boundary location between indoor and outdoor and mobile tag.

• Journal of Biomedical Engineering Research
• /
• v.22 no.5
• /
• pp.459-468
• /
• 2001

The Average Coordinate Referenee System (ACRS) method is developed to reduce experimental errors in human locomotion analysis. Experimentally measured kinematic data is used to conduct analysis in human modeling, and the model accuracy is directly related to the accuracy of the data. However. the accuracy is questionable due to skin movement. deformation of skeletal structure while in motion and limitations of commercial motion analysis system . In this study. the ACRS method is applied to an optically-tracked segment marker system. although it can be applied to many of the others as well. In the ACRS method, each marker can be treated independently. as the origin of a local coordinate system for its body segment. Errors, inherent in the experimental process. result in different values for the recovered Euler angles at each origin. By employing knowledge of an initial, calibrated segment reference frame, the Euler angles at each marker location can be averaged. minimizing the effect of the skin extension and rotation. Using the developed ACRS methodology the error is reduced when compared to the general Euler angle method commonly applied in motion analysis. If there is no error exist in the experimental gait data. the separation and Penetration distance of the femoraltibial joint using absolute coordinate system is supposed to be zero during one gait cycle. The separation and Penetration distance was ranged up to 18 mm using general Euler angle method and 12 mm using the developed ACRS.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.26 no.4
• /
• pp.548-555
• /
• 2022

This paper describes the hardware implementation of elliptic curve cryptography (ECC) used as a core operation in elliptic curve digital signature algorithm (ECDSA). The ECC processor supports eight operation modes (four point operations, four modular operations) on the NIST P-521 curve. In order to minimize computation complexity required for point scalar multiplication (PSM), the radix-4 Booth encoding scheme and modified Jacobian coordinate system were adopted, which was based on the complexity analysis for five PSM algorithms and four different coordinate systems. Modular multiplication was implemented using a modified 3-Way Toom-Cook multiplication and a modified fast reduction algorithm. The ECC processor was implemented on xczu7ev FPGA device to verify hardware operation. Hardware resources of 101,921 LUTs, 18,357 flip-flops and 101 DSP blocks were used, and it was evaluated that about 370 PSM operations per second were achieved at a maximum operation clock frequency of 45 MHz.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.9 no.3
• /
• pp.5-11
• /
• 2006

This paper is launched to get an exact bore-sighting value in the process of assembling for a dual-barrel weapon. Image processing method with a CCD(Charged Coupled Device) camera is chosen for the error reduction of bore-sighting. The results of this method by using a CCD camera and the testing target method are described in this paper. After the performance of the dual-barrel weapon and that of the fire-control system in the dual barrel weapon system is confirmed, the bore-sighting which is a part of the process in the system assembly is accomplished. In this process, the position of the barrel is identified by using the testing target method that is an existing bore-sighting method. Then, the fixing line of the fire-control system is checked by a day-optical part. The precision of the bore-sighting is required within several mils, however the manual method using the naked eyes makes it worse. Therefore, a CCD camera is installed in the eyepieces. Next, we can get an image of the sighting and the center coordinate values of the laser-pointer from each barrel by image processing method. A required bore-sighting value is calculated from the eccentricity of the center coordinate. Finally, It can be applied to adopt this result in the assembling process of the dual-barrel weapon.

• 제어로봇시스템학회:학술대회논문집
• /
• 2000.10a
• /
• pp.83-83
• /
• 2000

Recently, Vision system has being used all around industry. Sensor systems are used for Mark Reader, for example, optical scanning is proximity sensor system, have many disadvantages, such as, lacking user interface and difficulty to store original specimens. In contrast with this, Vision systems for Mark Reader has many advantages, including function conversion to achieve other work, high accuracy, high speed, etc. In this thesis, we have researched the development of Mark Reader by using a Vision system. The processing course of this s)'stem is consist to Image Pre-Processing such as noise reduction, edge detection, threshold processing. And then, we have carried out camera calibration to calibrate images which are acquired from camera. After searching for reference point within scanning area(60pixe1${\times}$30pixe1), we have calculated points crossing by using line equations. And then, we decide to each ROI(region of interest) which are expressed by four points. Next we have converted absolute coordinate into relative coordinate for analysis a translation component. Finally we carry out Mark Reading with images classified by six patterns. As a result of experiment which follows the algorithm has proposed, we have get error within 0.5% from total image.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.46 no.2
• /
• pp.66-72
• /
• 2009

In this paper, an efficient frequency offset synchronization structure for OFDM(Orthogonal Frequency Division Multiplexing) is proposed. Conventional CORDIC(Coordinate Rotation Digital Computer) algorithm for frequency offset synchronization utilizes two CORDIC hardware i.e., one is vector mode for phase estimation, the other is rotation mode for compensation. But proposed structure utilizes one CORDIC hardware and divider. Through simulation, it is shown that hardware implementation complexity is reduced compared with conventional structures. The Verilog-HDL coding and front-end chip implementation results for the proposed structure show 22.1% gate count reduction comparison with those of the conventional structure.

• Journal of the Institute of Electronics Engineers of Korea SP
• /
• v.45 no.5
• /
• pp.118-125
• /
• 2008

In this paper, an efficient frequency offset synchronization structure for OFDM(Orthogonal Frequency Division Multiplexing) is proposed. Conventional CORDIC(Coordinate Rotation Digital Computer) algorithm for frequency offset synchronization utilizes two CORDIC hardware i.e., one is vector mode for phase estimation, the other is rotation mode for compensation. But proposed structure utilizes one CORDIC hardware and divider. Through simulation, it is shown that hardware implementation complexity is reduced compared with conventional structures. The Verilog-HDL coding and front-end chip implementation results for the proposed structure show 22.1% gate count reduction comparison with those of the conventional structure.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2023.05a
• /
• pp.345-346
• /
• 2023

As the shape and size of detectable objects diversifying recognition and segmentation algorithms have been developed to acquire accurate shape information. Although a high density of data captured by the repetition of scanning improves the accuracy of algorithms the high dense data decreases the efficiency due to its large size. This paper proposes standardization algorithms using the feature of structural members on indoor point cloud data to improve the process. First of all we determine the reduction rate of the density based on the features of the target objects then the data reduction algorithm compresses the data based on the reduction rate. Second the data arrangement algorithm rotates the data until the normal vector of data is aligned along the coordinate axis to allow the following algorithms to operate properly. Final the data arrangement algorithm separates the rotated data into their leaning axis. This allows reverse engineering of indoor point clouds to obtain the efficiency and accuracy of refinement processes.

• Journal of Yeungnam Medical Science
• /
• v.15 no.2
• /
• pp.263-274
• /
• 1998

One of the main purposes in the treatment of developmental dislocation of the hip is to achieve and maintain concentric, congruent, and stable reduction. The arthrogram performs an important role in the diagnosis and treatment of developmental dislocation of the hip. The arthrogram provides much information about the soft tissue status of the hip joint. Limbus and ligamentum teres is exactly evaluated so that we can plan the reduction and treatment before operation. Eighteen preoperative hip arthrograms of 17 children treated for developmental dislocation of the hip from 1992 to 1998 were reviewed. The limbus, ligamentum teres and transverse acetabular ligament were compared with the pathoanatomy seen at the time of open reduction. Arthrography proved to be reliable in identifying the limbus and ligamentum teres. So we recommend that arthrography must be performed before closed or open reduction. Also, we recorded the radiographic parameters: acetabular index, acetabular floor thickness, center edge(CE) angle of Wiberg, and Y-coordinate. The center edge(CE) angle of Wiberg obtained from arthrography was measured more accurately than from simple roentgenograms because the ossification of the femoral head was frequently located eccentrically in the developmental dislocation of the hip.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.57 no.3
• /
• pp.375-383
• /
• 2008

This paper deals with reduction and analysis of cogging torque for permanent magnet synchronous generators with multi-pole rotor for wind power applications. Open-circuit field solutions are derived using a magnetic vector potential and a two-dimensional (2-d) polar coordinate systems. On the basis of derived open-circuit field solutions and 2-d permeance functions, we also derive open-circuit field solutions considering stator slotting effects. By using open-circuit field solutions considering stator slotting effects and energy variation methods, this paper analytically predicts the cogging torque considering skew effects. All analytical results are shown in good agreement with those obtained from finite element (FE) analyses. In order to reduce the cogging torque, by predicting the variation of the cogging torque according to pole arc/pitch ratio using analytical and FE methods, pole arc/pitch ratio which makes the cogging torque minimum are determined. However, we confirm that measured value for cogging torque of the PMG with determined pole arc/pitch ratio is twice higher than predicted value. Therefore, the reason for an error between measured and predicted cogging torque is discussed in terms of a shape of PMs and is proved experimentally.