• Proceedings of the KSRS Conference
• /
• 2009.03a
• /
• pp.167-171
• /
• 2009

정지궤도에서는 세계 최초의 해양관측위성으로 개발된 정지궤도 해양위성(GOCI, Geostationary Ocean Color Imager)은 통신해양기상위성(COMS, Communication, Ocean and Meterological Satellite)의 탑재체로서 2009년말 발사 예정이다. 정지궤도 해양위성의 복사보정은 센서의 전기적 특성에 의한 잡음을 제거하기 위한 암흑전류 교정(Dark Current Correction)을 먼저 수행한 다음, 주운영지상국인 해양위성센터(KOSC, Korea Ocean Satellite Center)에서 수신된 위성의 원시자료의 Digital Number(DN)를 실제 해양원격탐사에서 이용하는 물리량인 복사휘도(Radiance, $W/m^2/{\mu}m/sr$)로 변환하는 복사보정을 수행한다. 정확도 높은 복사보정을 수행하기 위해서는 기준광원의 복사휘도와 센서의 물리적 특성을 정확하게 알아야 한다. 정지궤도 해양위성 궤도상 복사보정(on-orbit radiometric calibration)에서는 태양이 기준광원이기 때문에, 기준 태양복사모델(Thuillier 2004 Solar Irradiance Model)에서 지구-태양간 거리 변화(1년 주기)를 보정한 태양의 방사도 (Irradiance)를 이용하고, 태양입사각에 대한 태양광 확산기의 감쇄 특성 변화를 고려하여 센서에 입력되는 복사휘도를 계산한다. 센서의 물리적 특성으로 인한 복사보정의 오차를 줄이기 위해 우주방사선 및 우주먼지(space debris)로 인해 위성 운용기간 중 그 특성이 저하되는 태양광 확산기(solar Diffuser)의 특성변화를 모니터링하기 위한 DAMD(Diffuser Aging Monitoring Device)를 이용한다. 정지궤도 해양위성 주관운영기관인 한국해양연구원의 해양위성센터에서는 정지궤도 해양위성 복사보정을 수행하기 위한 S/W를 통신해양기상위성 자료처리시스템 개발사업의 일환으로 개발하였으며, 관련 성능 시험을 수행하고 있다.

• Journal of Sensor Science and Technology
• /
• v.7 no.4
• /
• pp.293-299
• /
• 1998

An objective of this study is to develop a voltage measuring device that uses a gas-filled switch (GS) on 22.9 kV-y extra-high voltage distribution lines. The voltage measuring device proposed in this paper is a kind of capacitive divider which consists of a detecting electrode attached outside of the bushing of GS, an impedance matching circuit, and a voltage buffer. It can be easily installed in an established GS without changing the structure. For the calibration and application investigations, the voltage measuring device was set up in the 25.8 kV 400 A GS, and a step pulse generator having 5 ns rise time is used. As a result, it was found that the frequency bandwidth of the voltage measuring device ranges from 1.35 Hz to about 13 MHz. The error of voltage dividing ratio which is evaluated by the commercial frequency voltage of 60 Hz was less than 0.2%. In addition, voltage dividing ratio in the commercial frequency voltage and in a non-oscillating impulse voltage were compared, and their deviation were less than 0.7%.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.24 no.1
• /
• pp.33-38
• /
• 2016

The turbocharger is an essential component to realize the engine down-sizing. The moment of inertia of turbocharger rotor is an important parameter with respect to acceleration performance of the vehicle. It can be calculated from the CAD software based the geometry data and the material properties. But the accurate value of the inertia of turbocharger rotor must be measured through the experimental method. In this study, the measurement of moment of inertia of turbocharger rotor for 2.0 L spark-ignition engine was carried out. First, an experimental equipment using a trifilar method was designed and fabricated. Some optical devices, that is, photo sensor, counter, convex lens, etc, were used to increase the accuracy of the measurement. Second, error sensitivity for the equipment was analyzed. The error of period time and the radius can give big affects to the accuracy of the moment of inertia. When the amount of error of these two were each 1.0 %, maximum error of the moment of inertia was under 3.0 %. Third, the calibration for the equipment was performed using a calibration rotor which has similar shape to turbine rotor but simple. Calculated value from CAD software and measured one for the calibration rotor were compared. The total error of the equipment and the measurement is about 1.3 %. This result shows that the equipment can give the good result with resonable accuracy. Finally the moment of inertia of the turbine rotor and compressor wheel were measured. The coefficient of variations, the ratio of standard deviation to mean value, were reasonably small at 0.57 % and 0.73 % respectively. Therefore this equipment is suitable for the measurement of the moment of inertia of the turbine rotor and compressor wheel.

• Journal of the Korea Convergence Society
• /
• v.13 no.4
• /
• pp.137-145
• /
• 2022

The usability evaluation of the remote fluid monitoring device, which was introduced to reduce the work of nurses and increase the efficiency, was performed due to the expansion of the non-face-to-face medical system. Remote fluid monitoring is a fusion of various technologies such as fluid measurement and analysis, error correction technology, and transmission technology. The range of use by users, the information they want to obtain, and the control device, etc. are wide, and the factors that evaluate the product are also diverse. Therefore, it is difficult to improve the product through evaluation. In this study, a quantitative index was developed to help improve the product for commercialization by conducting 20 usability evaluations in three areas of product stability, operability, and satisfaction with the remote sap monitoring system device. It was performed through infrared and load cell-type sap monitoring devices. In terms of stability, there was a difference in installation work such as fixing the pole of the device, and high satisfaction was shown for operability and accuracy. In terms of product satisfaction, the satisfaction of load cell devices was generally high.

• Plant Journal
• /
• v.17 no.4
• /
• pp.53-60
• /
• 2021

The purpose of this study was to develop a portable vibration analyzer that is effective for acquiring and analyzing vibration data of rotating equipment of a power plant and a domestic vibration monitoring system manufacturer Nada Co., Ltd. The hardware of the developed portable vibration analyzer minimizes measurement errors by calibrating the measured values obtained through measurement uncertainty for calibration of the measuring devices in the system, and is composed of a signal processing device with high resolution through high speed data processing. The software structure implements a variety of vibration plots to execute a detailed analysis program, and applies algorithms to measure and remove noise caused by disturbances while operating a rotating machine. The developed product contributed greatly to increase the user's mobility and performance, as well as to reduce the purchase cost due to localization.

• Korean Journal of Food Science and Technology
• /
• v.40 no.2
• /
• pp.152-159
• /
• 2008

The purpose of this study was to determine the accurate quantification of vitamin A in infant formula by comparing two different standard stock solutions as well as various sample weights using high performance liquid chromatography. The sources of uncertainty in measurement, such as sample weight, final smaple vloume, and the instrumental results, were identified and used as parameters to determine the combined standard uncertainty based on GUM(guide to the expression of uncertainty in measurement) and the Draft EURACHEM/CITAC Guide. The uncertainty components in measuring were identified as standard weight, purity, molecular weight, dilution of the standard solution, calibration curve, recovery, reproducibility, sample weight, and final sample volume. Each uncertainty component was evaluated for type A and type B and included to calculate the combined uncertainty. The analytical results and combined standard uncertainties of vitamin A according to the two different methods of stock solution preparation were 627 ${\pm}$ 33 ${\mu}$g R.E./100 g for 1,000 mg/L of stock solution, and 627 ${\pm}$ 49 ${\mu}$g R.E./100 g for 100 mg/L of stock solution. The analytical results and combined standard uncertainties of vitamin A according to the various sample weighs were 622 ${\pm}$ 48 ${\mu}$g R.E./100 g, 627 ${\pm}$ 33 ${\mu}$g R.E./100 g, and 491 ${\pm}$ 23 ${\mu}$g R.E./100 g for 1 g, 2 g, and 5 g of sampling, respectively. These data indicate that the preparation method of standard stock solution and the smaple amount were main sources of uncertainty in the analysis results for vitamin A. Preparing 1,000 mg/L of stock solution for standard material sampling rather than 100 mg, and sampling not more than 2 g of infant formula, would be effective for reducing differences in the results as well as uncertainty.

• The Journal of Korean Society for Radiation Therapy
• /
• v.33
• /
• pp.109-116
• /
• 2021

Purpose: The purpose of this study is to evaluate the usefulness of Surface-Guided Patient Setup by comparing the patient positioning accuracy when image-guided radiation therapy was used for Markerless patients(unmarked on the skin) using Surface-Guided Patient Setup and Marker patients(marked on the skin) using Laser-Based Patient Setup. Materials And Methods: The position error during IGRT was compared between a Markerless patient initially set up with SGPS using an optical surface scanning system using three cameras and a Marker patient initially set up with LBPS that aligns the laser with the marker drawn on the patient's skin. Both SGPS and LBPS were performed on 20 prostate cancer patients and 10 Stereotactic Radiation Surgery patients, respectively, and SGPS was performed on an additional 60 breast cancer patients. All were performed IGRT using CBCT or OBI. Position error of 6 degrees of freedom was obtained using Auto-Matching System, and comparison and analysis were performed using Offline-Review in the treatment planning system. Result: The difference between the root mean square (RMS) of SGPS and LBPS in prostate cancer patients was Vrt -0.02cm, Log -0.02cm, Lat 0.01cm, Pit -0.01°, Rol -0.01°, Rtn -0.01°, SRS patients was Vrt 0.02cm, Log -0.05cm, Lat 0.00cm, Pit -0.30°, Rol -0.15°, Rtn -0.33°. there was no significant difference between the two regions. According to the IGRT standard of breast cancer patients, RMS was Vrt 0.26, Log 0.21, Lat 0.15, Pit 0.81, Rol 0.49, Rtn 0.59. Conclusion:. As a result of this study, the position error value of SGPS compared to LBPS did not show a significant difference between prostate cancer patients and SRS patients. In the case of additionally performed SGPS breast cancer patients, the position error value was not large based on IGRT. Therefore, it is considered that it will be useful to replace LBPS with SGPS, which has the great advantage of not requiring patient skin marking..

• The korean journal of orthodontics
• /
• v.30 no.1 s.78
• /
• pp.115-126
• /
• 2000

Dental arch expansion is one of the method used to solve the dental crowding problem by non-extraction. Many formulae using tooth size have been suggested to predict ideal inter-premolar and inter-molar width. The purpose of this study was to evaluate the adequacy of some upper dental arch width prediction methods, namely Pont's method, Schmuth's method and Cha's method. The sample consisted of the casts of 119 Korean young adults who had no muscular abnormality, no skeletal discrepancy, and Angle's Class I molar relationships. Measurements were obtained directly from plaster casts; they Included mesiodistal crown diameters of the four maxillary incisors, as well as maxillary inter-first-premolar and inter-first-molar arch widths as specified by Pont. The correlation coefficients between the sum of incisors(SI) and upper dental arch width were calculated. The differences between predicted width and actual width were classified as overestimated, properestimated, and underestimated. The data obtained from each group were analyzed for statistical differences. The results were as follows : 1. Upper dental arch width indices were calculated from SI in normal occlusion (81.96 : premolar index, 62.55 : molar index). 2. Low correlations between SI and arch width were noted in normal occlusion (0.50 in the inter-premolar width, 0.39 in the inter-molar width). 3. Pont's formula and Schmuth's formula tended to overestimate the inter-premolar width. A more even distribution of estimates was noted in Cha's fomula. 4. Cases within $\pm$1 mm range of observed inter-premolar width were $45\%$ in the Cha's formula, $40\%$ in the Pont's formula, and $39\%$ in the Schmuth's formula. 5. All formulae had a tendency to underestimate the inter-molar width, but Cha's formula had better predictability than others. 6. Cases within $\pm$1 mm range of observed inter-molar width were $40\%$ in the Cha's formula, $29\%$ in the Pont's formula, and $13\%$ of Schmuth's formula. The data presented in this study does not support the clinical usefulness of ideal arch width prediction methods using the mesiodistal width of maxillary incisors.

• The korean journal of orthodontics
• /
• v.35 no.6 s.113
• /
• pp.475-484
• /
• 2005

This study was performed to investigate the reproducibility of the horizontal and midsagittal planes, and to suggest a stable coordinate system for three-dimensional (3D) cephalometric analysis. Eighteen CT scans were taken and the coordinate system was established using 7 reference points marked by a volume model, with no more than 4 points on the same plane. The 3D landmarks were selected on V works (Cybermed Inc., Seoul, Korea), then exported to V surgery (Cybermed Inc., Seoul, Korea) to calculate the coordinate values. All the landmarks were taken twice with a lapse of 2 weeks. The horizontal and midsagittal planes were constructed and its reproducibility was evaluated. There was no significant difference in the reproducibility of the horizontal reference planes, But, FH planes were more reproducible than other horizontal planes. FH planes showed no difference between the planes constructed with 3 out of 4 points. The angle of intersection made by 2 FH planes, composed of both Po and one Or showed less than $1^{\circ}$ difference. This was identical when 2 FH planes were composed of both Or and one Po. But, the latter cases showed a significantly smaller error. The reproducibility of the midsagittal plane was reliable with an error range of 0.61 to $1.93^{\circ}$ except for 5 establishments (FMS-Nc, Na-Rh, Na-ANS, Rh-ANS, and FR-PNS). The 3D coordinate system may be constructed with 3 planes; the horizontal plane constructed by both Po and right Or; the midsagittal plane perpendicular to the horizontal plane, including the midpoint of the Foramen Spinosum and Nc; and the coronal plane perpendicular to the horizontal and midsagittal planes, including point clinoidale, or sella, or PNS.

• The Korean Journal of Nuclear Medicine Technology
• /
• v.21 no.2
• /
• pp.55-64
• /
• 2017

Purpose Recently, with the spread of SPECT/CT, various image correction methods can be applied quickly and accurately, which enabled us to expect quantitative accuracy as well as image quality improvement. Among them, the Collimator Detector Response(CDR) recovery is a correction method aiming at resolution recovery by compensating the blurring effect generated from the distance between the detector and the object. The purpose of this study is to find out quantitative change depending on the change in detection distance in SPECT/CT images with CDR recovery applied. Materials and Methods In order to find out the error of acquisition count depending on the change of detection distance, we set the detection distance according to the obit type as X, Y axis radius 30cm for circular, X, Y axis radius 21cm, 10cm for non-circular and non-circular auto(=auto body contouring, ABC_spacing limit 1cm) and applied reconstruction methods by dividing them into Astonish(3D-OSEM with CDR recovery) and OSEM(w/o CDR recovery) to find out the difference in activity recovery depending on the use of CDR recovery. At this time, attenuation correction, scatter correction, and decay correction were applied to all images. For the quantitative evaluation, calibration scan(cylindrical phantom, $^{99m}TcO_4$ 123.3 MBq, water 9293 ml) was obtained for the purpose of calculating the calibration factor(CF). For the phantom scan, a 50 cc syringe was filled with 31 ml of water and a phantom image was obtained by setting $^{99m}TcO_4$ 123.3 MBq. We set the VOI(volume of interest) in the entire volume of the syringe in the phantom image to measure total counts for each condition and obtained the error of the measured value against true value set by setting CF to check the quantitative accuracy according to the correction. Results The calculated CF was 154.28 (Bq/ml/cps/ml) and the measured values against true values in each conditional image were analyzed to be circular 87.5%, non-circular 90.1%, ABC 91.3% and circular 93.6%, non-circular 93.6%, ABC 93.9% in OSEM and Astonish, respectively. The closer the detection distance, the higher the accuracy of OSEM, and Astonish showed almost similar values regardless of distance. The error was the largest in the OSEM circular(-13.5%) and the smallest in the Astonish ABC(-6.1%). Conclusion SPECT/CT images showed that when the distance compensation is made through the application of CDR recovery, the detection distance shows almost the same quantitative accuracy as the proximity detection even under the distant condition, and accurate correction is possible without being affected by the change in detection distance.