• The Journal of the Korea Contents Association
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• v.13 no.11
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• pp.541-550
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• 2013

Generally in case of tablet PC's, the Windows 8 is used to support various functions or development convenience, however it cannot support real-time processing. In addition, existing commercial solutions and RTiK has a problem to support real-time processing due to impossibility of getting APIC timer count value which is used to generate timer interrupt separated from that of Windows. Thus, in this paper, we set the initial APIC count value using MSR_FSB_FREQ to support real-time processing on the Windows 8-based tablet PC's. Additionally, we deal with designing and implementing RTiK+ providing real-time processing to guarantee interrupt periods by controlling C-State which is used for low power techniques. To evaluate the performance of the proposed RTiK+, we measured the periods of generated real-time threads using RDTSC instructions which return the number of CPU clock ticks, and verified that RTiK+ operates correctly within the error ranges of 1ms.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.24 no.5
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• pp.443-451
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• 2006

DEM has been used for various purposes overall fields of engineering, the fields of civil engineering, military, communication, environment, and so forth and its applications are being extending increasingly. It is well hewn that LiDAR DEM is definitely superior to the other surveying methods. But LiDAR DEM run short of a full study about vertical accuracy. In order to assess LiDAR DEM, total 35 stations were selected and surveyed by GPS for utilizing as reference data. And then accuracy of LiDAR DEM was analyzed by comparison between both LiDAR DEM and CPS surveying. The RMSE of ${\pm}0.109m$ was shown in vertical direction. It is within the permissible accuracy required for mapping on a scale of 1 to 500 and 1 to 1000 on the mapping rule notified by the National Geographic Information Institute. It is expected that the results of this study will be fully used in the field of large scale DEM generation and be utilized as basic information in applied field of LiDAR DEM.

• Journal of Korean Society for Geospatial Information Science
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• v.18 no.4
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• pp.31-39
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• 2010

In this study, the performance of the online GPS processing services provided by diverse institutions was compared so that domestic GPS users in geodesy and surveying can easily get precise coordinates using those services. In order to evaluate the accuracy of each online GPS processing service, we calculated coordinates of seven GPS permanent stations located in Korea and foreign countries using APPS, CSRS-PPP, AUSPOS and OPUS. And the results were compared with published coordinates by IERS and National Geographic Information Institute. In the cases of foreign stations, the mean value of the horizontal errors was 9.3 mm and the descending order of accuracies was APPS, AUSPOS, OPUS and CSRS-PPP. In the cases of Korean stations, the mean value of the horizontal errors was 37.6 mm, although the order of accuracy was similar to the foreign cases; AUSPOS, APPS, OPUS and CSRS-PPP. Also, the average value of 3-D errors in Korean cases was about 3 cm larger than that of foreign cases and a bias of 3 cm was observed in the north direction.

• Journal of Korean Society for Geospatial Information Science
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• v.14 no.3 s.37
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• pp.47-53
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• 2006

In this contribution, an integration of seamless navigation system for the pedestrian is introduced. To overcome the GPS outages in various situations, multi-sensor of GPS, INS, electronic barometer and compass are considered in one Extented Kalman filter. Especially, the integrated system is designed for low-cost for the practical applications. Therefore, a MEMS IMU is considered, and the low quality of the heading is compensated by the electronic compass. In addition, only the pseudoranges from GPS measurements are considered for possible real-time application so that the degraded height is also controlled by a barometer. The mathematical models for each sensor with systematic errors such as biases, scale factors are described in detail and the results are presented in terms of a covariance analysis as well as the position and attitude errors compared to the high-grade GPS/INS combined solutions. The real application scenario of GPS outage is also investigated to assess the feasible accuracy with respect to the outage period. The description on the current status of the development and future research directions are also stated.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.05a
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• pp.181-184
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• 2016

This study is to compensate for inaccuracies in accordance with the change in the deviation correction value due to the movement and location of the ship cargo, equipment of the vessel, and eliminating the inconvenience of hand. By modifying the deviation through the simplification and automation was planned for accuracy and ease of modification of the modified value. The main method used is charted by measuring 24 direction and inputting the value of magnetic compass direction in automatic deviation-correcting apparatus manually or automaticallyThe measured values are exhibited in Table data and made it possible to calculate accurate correction value deviation. From this it can make deviation table having the margin of error within ${\pm}3^{\circ}$in all regions of the world And this table will help to navigational safety and economy under the unavailable or limited gyro contion.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.11
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• pp.33-39
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• 2014

We propose an optimal number of transmit antennas which maximizes energy-efficiency (EE) in multi-user massive multiple-input multiple-output (MIMO) downlink system with the maximal ratio transmission (MRT) precoding. With full channel state information at the transmitter (CSIT), we find a closed form solution by partial differential function with proper approximations using average channel gain, independence of individual channels, and average path loss. With limited feedback, we get a solution numerically by the bisection with approximations in the same manner, and analyze an effect of feedback bits on the optimal number of transmit antennas. Simulation results show that the optimal numbers of transmit antenna getting from proposed closed form solution and exhaustive search are nearly same.

• Aerospace Engineering and Technology
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• v.1 no.2
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• pp.105-112
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• 2002

In this paper, a servo filter design for the gimbal engine actuator system of KSR-III(Korea Sounding Rocket-III) is considered. A reasonable filter structure is determined based on the actuator analytic models. The servo filter consists of a 2-nd order lowpass filter and a 1-st order compensator. The lowpass filter is required to protect the actuator from high frequency vibration, and the compensator to enhance the resulting stability. A Butterworth type servo filter is considered as the simplest one. The final servo filter type is determined by evaluating simultaneously both high frequency gain reduction performance and the corresponding KSR-III stability margin. Consequently it is revealed that a notch type servo filter located on the error between command signal and feedback signal in the control loop is very effective. Later, based on the proposed servo filter type, an onboard servo filter hardware of KSR-III will be designed and tested.

• Smart Media Journal
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• v.7 no.2
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• pp.15-22
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• 2018

Pupil tracking technologies can be used as an efficient information provider means that provides convenience to the user by connecting with a smart device. In this paper, we measure the distance of user gaze point using the pupil tracking device which produced by Pupil-labs, also shows the experimental result with analyzing accuracy and precision. Based on that the pupil gaze point location which tracked by pupil tracking device is compared with object target in terms of error. Since the mobile pupil tracking device is also one kind of camera, we have to perform the calibration before using the device. Not only generally used 2-dimensional calibration, but also 3-dimensional calibration method is explained. To get the improved accuracy of 2-dimensional calibration result, the 3-dimensional calibration set an imaginary plane and executes the calibration in various 3-dimensional spaces. To show the efficiency of 3-dimensional calibration, we analyze the experimental result. It also introduces various using methods and information that can be obtained through the device.

• Journal of the Institute of Convergence Signal Processing
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• v.11 no.4
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• pp.303-309
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• 2010

We proposes a new approach for testing the self visual-acuity by using the KS standard optotype. The proposed system provides their hand-gesture recognition method for the convenient response of subjects in the visual acuity measurement. Also, this system can measure a visual-acuity that excludes the examiner's subjective judgement or the subject's memorized guess, because of presenting a random optotype automatically by computer without a examiner. Especially, Our system guarantees the reliability by using the KS standard optotype and its presentation(KS P ISO 8596), which is defined by the Korea Standards Association in 2006. And the database management function of our system can provide the visual-acuity data to the EMR client easily. As a result, Our system shows the 98% consistency in the limit of the ${\pm}1$ visual-acuity level error by comparing the visual-acuity chart test.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.453-453
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• 2018

2017년 12월 기준 우리나라에 등록된 자동차는 약 2,200만 이상으로, 그 증가율은 매년 증가하는 추세이다. 이러한 최근 차량대수 및 고자산인 외산차 보유율 증가는 자연재난에서 노출과 관련한 위험도를 증가시키는 주요인이 되며, 홍수발생 시 상당한 규모의 경제적 피해를 야기한다. 현재 국가연구개발사업으로 진행 중인 행정안전부(2017) 연구는 위험지역 내 차량의 공간적 분포와 차량유형별 침수심에 따른 취약성을 고려하여 어떠한 홍수사상으로부터 예상되는 차량 피해액을 추정하는 방법을 제시한 바 있다. 여기서는 어떠한 집계구 내에서 동일한 침수심 구간을 가지는 면(polygon)을 분석단위로 하고 있는 데, 이를 편의성 차원에서 벡터자료에 기반 한 연산과정을 수행할 경우 정의된 침수구역도(재해정보)의 고유 정보가 훼손되거나, 세분화된 침수심 구간에 따른 손상률 관계를 사용할 수 없는 문제점이 있다. 이에 본 연구에서는 격자 기반의 침수구역도와 인벤토리 지도로부터 Raster GIS 공간연산을 활용한 차량피해 산정절차를 제시하였고, 이를 신천수계 하천기본계획(경기도, 2011)에서 계획된 치수사업에 적용하여 홍수빈도별 사업시행 전후 상황에 적용하였다. 이 과정에서 침수구역도는 인벤토리 상의 집계구 면적을 고려하여 $5m{\times}5m$ 크기로 제작하였고, 동일한 격자크기로 변환된 인벤토리는 변환 전후 면적을 기준으로 할 때 거의 오차가 없는 것으로 확인되었다. 그리고 Raster 공간연산으로부터 침수편입률을 결정하는 과정에서 집계구 넘버 및 침수심 정보를 확인하기 위한 자료별 전처리 과정을 제시하였고, 여기서 집계구 넘버는 인벤토리 정보와 침수심 정보는 손상함수와 연계된다. 본 연구에서 제시한 결과는 향후 실무에서 직접 적용하는 데 활용하기 위하여 방법론과 함께 가이드라인 문서로 정리할 계획이다.