• KSII Transactions on Internet and Information Systems (TIIS)
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• 제3권1호
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• pp.119-133
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• 2009

The purpose of this research is to accurately estimate the location of a device using the received signal strength indicator (RSSI) of IEEE 802.11 WLAN for location tracking in indoor environments. For the location estimation method, we adopted the calibration model. By applying the Adaptive Zone Based K-NNSS (AZ-NNSS) algorithm, which considers the velocity of devices, this paper presents a 9% improvement of accuracy compared to the existing K-NNSS-based research, with 37% of the K-NNSS computation load. The accuracy is further enhanced by using a Kalman filter; the improvement was about 24%. This research also shows the level of accuracy that can be achieved by replacing a subset of the calibration data with values computed by a numerical equation, and suggests a reasonable number of calibration points. In addition, we use both the mean error distance (MED) and hit ratio to evaluate the accuracy of location estimation, while avoiding a biased comparison.

• 대한기계학회논문집A
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• 제26권11호
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• pp.2237-2244
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• 2002

This research develops a low-cost and high accuracy kinematic calibration method based on the following principles: 1) the platform locations are accurately measured by a constrained movement to inspect a calibration target; 2) the constrained movement is chosen to guarantee the parameter observability; 3) the mechanical fixture to constrain the movement and the sensor to check the constrained movement are implemented by low-cost and high-accuracy devices; 4) the calibration is easily done at an industrial environment. The kinematic parameters calibrated with respect to a single plane aren't influenced due to the misalignment of the plane. A parameter observability is successfully obtained even through one planar constraint, which guarantees that all kinematic parameters are estimated by minimizing the cost function.

• 한국대기환경학회지
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• 제21권2호
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• pp.269-274
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• 2005

In this work, analytical bias arising from the gas chromatographic determination of sulfur compounds was evaluated by the application of direct loop injection method to the GC/PFPD detection of four sulfur compounds including H$_{2}$S, CH$_{3}$SH, DMS, and DMDS. For the proper evaluation of analytical uncertainties involved in GC calibration, we employed two comparative techniques of calibration at fxed concentration injection (CFCI) vs calibration at fixed volume injection (CFVI) method. The results of our study indicate that CFCI method exhibits very poor sensitivity due to the matrix effect with varying injection volumes. On the other hand, as CFVI method overcomes such limitation, it can be used to obtain very accurate quantification of S compounds at their high concentration levels above a few to a few tens ppb.

• Journal of Korean Society for Atmospheric Environment
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• 제21권E2호
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• pp.49-56
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• 2005

A long-path transmissometer is one of the optical instruments widely used to measure atmospheric light extinction coefficient without enclosing a light beam and perturbing aerosols. Over the past two decades, a number of measurements have been carried out using the long-path transmissometer manufactured by OPTEC, Inc. Calibration of the transmissometer should be performed when any component of the transmissometer system is interchanged or installation condition is changed. For a better calibration of the transmissometer, application of a modified calibration method for the existing neutral density (ND)-filter method was recommended for the computation of the atmospheric transmittance using model MODTRAN 4 in this study. It was revealed that the measured light extinction coefficient from the transmissometer which was calibrated using the existing ND-filter method could be overestimated due to the assumption of the atmospheric transmittance suggested by OPTEC, Inc. The uncertainty of the measured light extinction coefficient from the transmissometer calibrated based on the modified ND-filter method was calculated to be approximately $13Mm^{-1}$.

• 제어로봇시스템학회논문지
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• 제22권11호
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• pp.944-951
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• 2016

Resistance temperature detectors (RTDs) and thermocouple sensors are broadly used to measure temperatures in the engineering and research fields. The contents of this standard calibration procedure (SCP) describe procedures related to the calculation of an electrical temperature calibrator and show different ways to indicate the calibration results, such as measurement uncertainty. As an SCP for the electrical temperature calibrator has not been developed yet, we studied the SCP and found a solution to this problem. In this paper, we present a mathematical model of the data and measurement variations with the calibration data results.

• 정보처리학회논문지:소프트웨어 및 데이터공학
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• 제8권2호
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• pp.89-96
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• 2019

전방향 3차원 라이다 센서와 비전 카메라는 자동차나 드론 등의 자율주행기술 개발에 활용되고 있다. 한편 라이다 센서와 카메라 좌표계 사이의 변환 관계를 보정하기 위한 기존의 기술들은 특수한 보정물체를 제작하거나 보정물체의 크기가 큰 단점이 있다. 본 논문에서는 한 개의 구형물체를 사용하여 두 센서 사이의 기하보정을 간편하게 구현하는 방법을 소개한다. 구형 물체의 3차원 거리정보에서 RANSAC으로 네 개의 3차원 점을 선택하여 구의 중심좌표를 계산하고, 카메라 영상에서 물체의 2차원 중심점을 구하여 두 센서를 보정하였다. 구는 다양한 각도에서 영상을 획득하여도 항상 원형의 형상을 유지하기 때문에 데이터 획득 시 유리한 장점이 있다. 본 논문에서 제안하는 방법으로 약 2픽셀의 투영오차의 결과를 얻었고, 기존의 방법과의 비교실험을 통하여 제안 기술의 성능을 분석하였다.

• 전기전자학회논문지
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• 제20권4호
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• pp.439-448
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• 2016

온도 측정을 위해 RTD와 열전대 센서가 산업이나 연구 분야에 널리 사용되고 있다. RTD 및 열전대의 온도 교정기에 대한 표준교정절차는 측정에서 포함되는 불확도의 교정 결과를 나타내는 방법을 보여준다. 지금까지 이들에 대한 표준교정절차가 확립되지 않아 다소의 불편함과 표준교정 업무에 어려움이 있었다. 이러한 문제를 해결하기 위해 온도 교정기의 RTD 및 열전대에 대한 교정기법을 연구하게 되었다. 본 논문에서는 이들에 대한 수학적 모델과 교정결과 자료를 제시하였다.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2016년도 추계학술대회
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• pp.411-414
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• 2016

장마 및 태풍, 집중호우 등 다량의 강우발생시 댐 및 하천의 수위 관측은 국민의 생명 및 재산과 직접 연관되는 상황으로 안전재난 대비를 위해서는 안정적인 실시간 수위 데이터 확보와 신뢰성 있는 데이터는 과학적이고 신뢰성 있는 수자원 관리를 위한 필요충분 요소이다. 그러나 현재 운영되고 있는 댐이나 하천 상하류의 수위계는 신뢰성 확보를 위하여 현장에서 검정 및 교정이나 보정 등이 쉽지 않은 실정이다. K-water연구원에서는 길이분야인 수위계에 대한 국제공인 교정기관으로 운영중에 있으며, 현장에서 부자식 수위계를 교정할 수 있는 시스템 및 절차서의 부재로 표준교정실에서만 교정을 실시하였다. 따라서 본 연구에서는 기준자와 카메라를 이용하여 부자식 수위계를 현장에서 교정할 수 있도록 이동형 교정시스템 및 표준교정 절차서를 개발하였으며, 수위 데이터의 신뢰성 있는 자료 확보와 일관성 있는 자료관리가 가능하도록 하였다.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2019년도 학술발표회
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• pp.155-155
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• 2019

The Agricultural Policy/Environmental eXtender (APEX) models have been developed for assessing agricultural management efforts and their effects on soil and water at the field scale as well as more complex multi-subarea landscapes, whole farms, and watersheds. National Academy of Agricultural Sciences, Wanju, Korea, has modified a key component of APEX application, named APEX-Paddy for simulating water quality with considering appropriate paddy management practices, such as puddling and flood irrigation management. Calibration and validation are an anticipated step before any model application. Simple techniques are essential to assess whether or not a parameter should be adjusted for calibration. However, very few study has been done to evaluate the ability of APEX-Paddy to simulate the impact of multiple management scenarios on nutrients loss. In this study, the observation data from experimental fields at Iksan in South Kora was used in calibration and evaluation process during 2013-2015. The APEX auto- calibration tool (APEX-CUTE) was used for model calibration and sensitivity analysis. Four quantitative statistics, the coefficient of determination ($R^2$),Nash-Sutcliffe(NSE),percentbias(PBIAS)androotmeansquareerror(RMSE)were used in model evaluation. In this study, the hydrological process of the modified model, APEX-Paddy, is being calibrated and tested in predicting runoff discharge rate and nutrient yield. Field-scale calibration and validation processes are described with an emphasis on essential calibration parameters and direction regarding logical sequences of calibration steps. This study helps to understand the calibration and validation way is further provided for applications of APEX-Paddy at the field scales.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집A
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• pp.521-526
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• 2001

This research develops a low-cost and high accurate kinematic calibration method for a parallel typed machining center tool. A planar table is used for a mechanical fixture restricting the platform to place at the constrained pose and a low-cost and high accurate digital indicator is employed for a device checking if the constrained movement is satisfied within the established range. The kinematic parameters calibrated with respect to a single plane aren't influenced from the misalignment of the plane. A parameter observability is successfully obtained even through one planar constraint, which guarantees that the kinematic parameters is estimated by minimizing the cost function.