• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2014년도 추계학술대회
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• pp.837-839
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• 2014

레이다 시스템에서 3차원 궤적 정보는 목표물 추적을 위해 필수적이다. 이때 3차원 레이다는 수신 신호를 통해 방위각, 고각 및 거리를 추정하여 3차원 궤적 정보를 얻게 된다. 수신 신호에 따라 추정된 각도들과 거리는 오차를 가지게 되며 이 오차의 정도에 따라 3차원 레이다 시스템의 성능에 미치는 영향에 대한 분석이 요구되어진다. 본 논문에서는 3차원 레이다 시스템의 각도 및 거리 오차에 따라 추정된 3차원 궤적 정보와 실제 궤적 정보에 대해 RMSE (Root Mean Square Error)를 통해 성능을 분석한다.

• Journal of the Korean Data and Information Science Society
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• 제25권2호
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• pp.439-446
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• 2014

Quantile regression models with errors in variables have received a great deal of attention in the social and natural sciences. Some eorts have been devoted to develop eective estimation methods for such quantile regression models. In this paper we propose an orthogonal distance quantile regression model that eectively considers the errors on both input and response variables. The performance of the proposed method is evaluated through simulation studies.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권6호
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• pp.2132-2143
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• 2015

This paper presents two distance geometry-based algorithms for wireless location in cellular network systems-distance geometry filtering (DGF) and distance geometry constraint (DGC). With time-of-arrival range measurements, the DGF algorithm estimates the mobile station position by selecting a set of measurements with relatively small NLOS (non-line-of-sight) errors, and the DGC algorithm optimizes the measurements first and then estimates the position using those optimized measurements. Simulation results show that the proposed algorithms can mitigate the impact of NLOS errors and effectively improve the accuracy of wireless location.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 학술대회 논문집 정보 및 제어부문
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• pp.59-61
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• 2004

For automatic landing of small VTOL UAV, it is necessary to calculate the distance from the UAV and the ground. The distance can be generally measured by a ultra-sonic sensor, but the ultra-sonic sensor has errors according to velocity of a sensor board. To compensate these errors, we proposed a sensor fusion method using a Kalman filter.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제38권
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• pp.15.1-15.6
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• 2016

Background: The utilization of a cone-beam computed tomography (CT)-assisted surgical template allows for predictable results because implant placement plans can be performed in the actual surgery. In order to assess the accuracy of the CT-guided surgery, angular errors and shoulder/apex distance errors were evaluated by data fusion from before and after the placement. Methods: Computer-guided implant surgery was performed in five patients with 19 implants. In order to analyze differences of the implant fixture body between preoperative planned implant and postoperative placed implant, angular error and distance errors were evaluated. Results: The mean angular errors between the preoperative planned and postoperative placed implant was $3.84^{\circ}{\pm}1.49^{\circ}$; the mean distance errors between the planned and placed implants were $0.45{\pm}0.48mm$ horizontally and $0.63{\pm}0.51mm$ vertically at the implant neck and $0.70{\pm}0.63mm$ horizontally and $0.64{\pm}0.57mm$ vertically at the implant apex for all 19 implants. Conclusions: It is important to be able to utilize these methods in actual clinical settings by improving the various problems, including the considerations of patient mouth opening limitations, surgical guide preparation, and fixation.

• 제어로봇시스템학회논문지
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• 제20권4호
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• pp.443-448
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• 2014

Soft errors in memory devices that caused by radiation are the main threat from a reliability point of view. This threat can be commonly overcome with the combination of SEC (Single-Error Correction) codes and scrubbing technique. The interleaving architecture can give memory devices the ability of tolerating these soft errors, especially against multiple-bit soft errors. And the interleaving distance plays a key role in building the tolerance against multiple-bit soft errors. This paper proposes a reliability model of an interleaved memory device which suffers from multiple-bit soft errors and are protected by a combination of SEC code and scrubbing. The proposed model shows how the interleaving distance works to improve the reliability and can be used to make a decision in determining optimal scrubbing technique to meet the demands in reliability.

• 대한임베디드공학회논문지
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• 제7권2호
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• pp.71-78
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• 2012

Based on the Zigbee-based wireless sensor network, I suggest the way to reduce errors between the short distance, improving the accuracy of the presumed distance by revising the deviation of RSSI(Received Signal Strength Indication) values is to estimate the distance using only the RF signal power without the additional hardware. In general, the graph measured by RSSI values shows the proximity values which are ideally reduced in proportion to the distance under the free outdoor space in which LOS(Line-Of-Sight) is guaranteed. However, if the result of the received RSSI values are each substituted to the formula, it can produce a larger margin of error and less accurate measurement since it is based upon the premise that this free space is not affected by reflected waves or obstacles caused by the ground and electronic jamming engendered by the environment. Therefore, the purpose of this study is to reduce the margin of errors between the distances and to measure the proximity values with the ideal type of graph by suggesting the way to revise the received RSSI values in the light of these reflected waves or obstacles and the electronic jamming. In conclusion, this study proves that errors are reduced by comparing the proposed deviation correction method to the revised RSSI value.

• Imaging Science in Dentistry
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• 제52권4호
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• pp.343-350
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• 2022

Purpose: This study evaluated the prevalence of dental implant positioning errors and the most frequently affected oral regions. Materials and Methods: A sample was obtained of CBCT images of 590 dental implants from 230 individuals who underwent diagnosis at a radiology center using cone-beam computed tomography from 2017 to 2020. The following variables were considered: thread exposure, violation of the minimum distance between 2 adjacent implants and between the implant and tooth, and implant contact with anatomical structures. Descriptive data analysis and the Pearson chi-square test(P<0.05) were performed to compare findings according to mouth regions. Results: Most (74.4%) of the 590 implants were poorly positioned, with the posterior region of the maxilla being the region most frequently affected by errors. Among the variables analyzed, the most prevalent was thread exposure (54.7%), followed by implant contact with anatomical structures, violation of the recommended distance between 2 implants and violation of the recommended distance between the implant and teeth. Thread exposure was significantly associated with the anterior region of the mandible (P<0.05). The anterior region of the maxilla was associated with violation of the recommended tooth-implant distance (P<0.05) and the recommended distance between 2 adjacent implants(P<0.05). Implant contact with anatomical structures was significantly more likely to occur in the posterior region of the maxilla (P<0.05). Conclusion: Many implants were poorly positioned in the posterior region of the maxilla. Thread exposure was particularly frequent and was significantly associated with the anterior region of the mandible.

• Journal of Biosystems Engineering
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• 제32권1호
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• pp.44-49
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• 2007

A stereo vision system was developed for robot milking system (RMS) using two monochromatic cameras. An algorithm for inverse perspective transformation was developed for the 3-D information acquisition of all teats. To verify performance of the algorithm in the stereo vision system, indoor tests were carried out using a test-board and model teats. A real cow and a model cow were used to measure distance errors. The maximum distance errors of test-board, model teats and real teats were 0.5 mm, 4.9 mm and 6 mm, respectively. The average distance errors of model teats and real teats were 2.9 mm and 4.43 mm, respectively. Therefore, it was concluded that this algorithm was sufficient for the RMS to be applied.

• 한국측량학회:학술대회논문집
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• 한국측량학회 2010년 춘계학술발표회 논문집
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• pp.245-247
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• 2010

This research presents both system structure analysis to improve performance of 3D laser scanner, which has time of flight method, and scheme to minimize distance measurement errors during signal process. With the help of reference source, we minimized the instability of electronic signal processing time and possibility of distance measurement errors. Furthermore, it helps easy alignment and accuracy of system by using fiber delay line and coupler.