• Journal of Korea Water Resources Association
• /
• v.43 no.11
• /
• pp.933-944
• /
• 2010

This study compares the CEM and SGS methods which are geostatistical stochastic simulation methods for assessing the uncertainty by spatial variability in the estimation of the spatial distribution of probability rainfall. In the stochastic simulations using CEM and SGS, two methods show almost similar results for the reproduction of spatial correlation structure, the statistics (standard deviation, coefficient of variation, interquartile range, and range) of realizations as uncertainty measures, and the uncertainty distribution of basin mean rainfall. However, the CEM is superior to SGS in aspect of simulation efficiency.

• The Korean Journal of Nuclear Medicine Technology
• /
• v.26 no.2
• /
• pp.43-47
• /
• 2022

Purpose Radioimmunoassay implement quality control by systematizing the internal quality control system for quality assurance of test results. This study aims to contribute to the quality assurance of radioimmunoassay results and to implement systematic quality control by measuring the average CV of internal quality control and external quality control by plenty of institutions for reference when setting the laboratory's own acceptable range. Materials and Methods We measured the average CV of internal quality control and the bounce rate of more than 10.0% for a total of 42 items from October 2020 to December 2021. According to the CV result, we classified and compared the upper group (5.0% or less), the middle group (5.0~10.0%) and the lower group (10.0% or more). The bounce rate of 10.0% or more was compared by classifying the item of five or more institutions into tumor markers, thyroid hormones and other hormones. The average CV was measured by the overall average and standard deviation of the external quality control results for 28 items from the first quarter to the fourth quarter of 2021. In addition, the average CV was measured by the overall average and standard deviation of the proficiency results between institutions for 13 items in the first half and the second half of 2021. The average CV of internal quality control and external quality control was compared by item so we compared and analyzed the items that implement well to quality control and the items that require attention to quality control. Results As a result of measuring the precision average of internal quality control for 42 items of six institutions, the top group (5.0% or less) are Ferritin, HGH, SHBG, and 25-OH-VitD, while the bottom group (≤10.0%) are cortisol, ATA, AMA, renin, and estradiol. When comparing more than 10.0% bounce rate of CV for tumor markers, CA-125 (6.7%), CA-19-9 (9.8%) implemented well, while SCC-Ag (24.3%), CA-15-3 (26.7%) were among the items that require attention to control. As a result of comparing the bounce rate of more than 10.0% of CV for thyroid hormones examination, free T4 (2.1%), T3 (9.3%) showed excellent performance and AMA (39.6%), ATA (51.6%) required attention to control. When comparing the bounce rate of 10.0% or more of CV for other hormones, IGF-1 (8.8%), FSH (9.1%), prolactin (9.2%) showed excellent performance, however estradiol (37.3%), testosterone (37.7%), cortisol (44.4%) required attention to control. As a result of measuring the average CV of the whole institutions participating at external quality control for 28 items, HGH and SCC-Ag were included in the top group (≤10.0%), however ATA, estradiol, TSI, and thyroglobulin included in bottom group (≥30.0%). Conclusion As a result of evaluating 42 items of six institutions, the average CV was 3.7~12.2% showing a 3.3 times difference between the upper group and the lower group. Cortisol, ATA, AMA, Renin and estradiol tests with high CV will require continuous improvement activities to improve precision. In addition, we measured and compared the overall average CV of the internal quality control, the external quality control and the proficiency between institutions participating of six institutions for 41 items excluding HBs-Ab. As a result, ATA, AMA, Renin and estradiol belong to the same subgroup so we require attention to control and consider setting a higher acceptable range. It is recommended to set and control the acceptable range standard of internal quality control CV in consideration of many things in the laboratory due to the different reagents and instruments, and the results vary depending on the test's proficiency and quality control materials. It is thought that the accuracy and reliability of radioimmunoassay results can be improved if systematic quality control is implemented based on the set acceptable range.

• Journal of the Korean Geosynthetics Society
• /
• v.16 no.4
• /
• pp.93-101
• /
• 2017

In this study, a subjective weighting factors were awarded based on some indication of the difficulty of assessing the preconsolidation stress using traditional methods (Casagrande, Onitsuka et al., Silva, Becker et al., Janbu and Karlsrud methods) such as those proposed by Casagrande and Janbu using undisturbed sample obtained from Gwangyang dredged clay with high plasticity located in the southern area of Korean peninsular. These numbers only assess the relative ease of finding preconsolidation stress and say nothing regarding the accuracy of the value. The data were compared with measurements of undrained shear strength using strength incremental ratio, checking where or not the values are in the range of 0.25 to 0.35 (typical values of Korean marine clay) and analyzing standard deviation(degree of variability). The measurements of undrained shear strength were obtained from unconfined compression tests (UCT). When determining preconsolidation stress of Korean marine clay, at first, the work method proposed by Becker et al. and the bilogarithmic method proposed by Onitsuka et al. should be used. In addition, preconsolidation pressure should be estimated using the traditional Casagrande method as a basic of comparison.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.16 no.1
• /
• pp.147-156
• /
• 2017

This paper analyzes the performance limit of WAVE system for the platooning service requirements which is referred from the de facto standards. The performance of the packet error rate and mean delay as key parameters in the wireless communication systems should be satisfied to provide safety to the platooning vehicles. The test scenarios are conducted by considering the following vehicle groups: platooning vehicles, vehicles within a hop distance and vehicles within two hop distance( called hidden node vehicles). The models of packet error rate and delay deals with the topology of aforementioned vehicle groups, vehicle speed and communication range. The numerical results are obtained in terms of packet size, packet arrival rate and data transmission rate. Finally, this paper suggests the robust range of packet error rate and delay for the WAVE system to provide the platooning vehicle service.

• Progress in Medical Physics
• /
• v.12 no.2
• /
• pp.141-146
• /
• 2001

It is well known that assurance of the radiation therapy needs for an accuracy of $\pm$ 5 % in the delivery of an absorbed dose to target volume. Therefore, the dose evaluation of brachytherapy source and/or linear accelerate beam must be a stability with accuracy. In an advanced country, they recommended to use the radioactive check source for reference air ionization chamber for a stable response of radiation field chamber. In this experiments, the radioactive source Sr-90 and PR-05 air ionization chamber were used for standard source and reference ion chamber. The response of reference ion chamber showed as an 1.000$\pm$ 0.010 uncertainty for 10 years long and the evaliuation f dose discrepancy of clinical field ion chamber showed as 0.997 $\pm$0.011 in a $^{60}$ Co brachytherapy soruce. In our experiments, we can assuarance the long halflife standard source is reliable to preserve the calibration factor of reference chamber in stability.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.12 no.9
• /
• pp.4095-4100
• /
• 2011

In this paper, a log periodic bow-tie dipole array (LPBDA) antenna for UWB communications is investigated. Bow-tie shaped dipole elements are used instead of general dipole elements for LPDA antennas and the input reflection coefficient and realized gain characteristics of the LPBDA as a function of a flare angle are analyzed. It turns out that as the flare angle of the bow-tie dipole elements is increased, the lowest operating frequency is shifted toward lower frequency and the operating frequency band is increased, but the average gain is decreased. However, the gain variation of the LPBDA is much decreased and the front-back ratio is improved compared to the LPDA. Standard LPDA and LPBDA with a flare angle of 13 degrees are fabricated on an FR4 substrate with a dielectric constant of 4.4 and a thickness of 1.6 mm. Measured gain for the LPDA ranges from 4 to 6.5 dBi at 3.1 to 10.6 GHz band, while that for the LPBDA is in the range of 4.2 to 5 dBi.

• Journal of the Korean Magnetics Society
• /
• v.11 no.1
• /
• pp.38-44
• /
• 2001

The magnetic field standard below 1 mT with the resolution of 0.26 nT has been established. Earth magnetic field (EMF) is compensated automatically down to 0.1 nT/10 min. by a closed feedback system with Cs optical pumping magnetometer and 3-axis Helmholtz coils in nonmagnetic facilities. A multi-layer precision solenoid with the optimized single-current method generates the uniform magnetic field better than 1.0$\times$10$\^$-7/ within $\pm$ 1 cm region at its center. The coil constant of solenoid determined from Helium optical pumping magnetometer is 1.231 058 9 mT/A, and temperature coefficient is 0.38 nT/$\^{C}$. This standard system is used for calibration of low field magnetometers and testing relates to low field.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2020.06a
• /
• pp.13-13
• /
• 2020

'20년 3월 현재 전국 3,502개 읍면동 중 73개 읍면동이 지하수를 상수원으로 급수 중이며, 48개 산업단지에서 지하수를 주 수원으로 사용 중이다. 또한 급수 소외지역의 물 공급을 위해 주로 사용되는 소규모수도시설 14,811개 중 12,073개(81.5%)는 지하수를 이용하고 있으며, 그 위치는 전국에 산재해 있다. 이처럼 지하수는 댐, 저수지 및 하천과 더불어 생·공용수의 중요한 수원이라 할 수 있다. 본 연구에서는 급수 소외지역의 주요 수원인 지하수위 현황을 이용한 가뭄 모니터링 및 전망 기법을 개발하고자 하였다. 국가 지하수관측망 중 10년 이상 장기 관측 자료를 보유한 253개 관측소의 일단위 관측자료를 기반으로, 과거 관측수위 분포를 핵밀도함수로 추정하고 Quantile Function을 이용해 현재 수위의 높고 낮은 정도를 Percentile 값으로 산정하였다. 관측소별 지하수위 Percentile은 티센망을 이용해 167개 시군별로 공간평균하고 Percentile의 범위에 따른 가뭄등급을 설정하여 지하수 가뭄 정도를 모니터링 할 수 있는 기법을 제시하였다. 또한 지하수 가뭄을 전망하기 위해 강수와 지하수위의 거시적인 응답특성을 이용하였다. 관측소별로 추정된 핵밀도함수의 누적확률을 표준정규분포의 Quantile로 변환하여 표준지하수지수I(Standardized Groundwater level Index, SGI)를 산정하고, 시군별로 공간을 일치시킨 1~12개월 지속기간별 표준강수지수(Standardized Precipitation Index, SPI)와의 상관관계를 이용해 NARX(nonlinear autoregressive exogenous) 인공신경망 예측모형을 구축하였다. 이를 통해 기상청 정량전망 강수량을 이용해 전국의 1~3개월 후 지하수 가뭄을 빠르게 전망할 수 있는 체계를 구축하고, 생·공용수 분야 국가 가뭄 예·경보의 미급수지역 가뭄현황 및 전망에 활용중이다.

• Journal of the Korean GEO-environmental Society
• /
• v.9 no.5
• /
• pp.83-89
• /
• 2008

This study is to figure out the speed of soil diffusion and shapes as well when landslide occurred. It was measured the speed and shapes of soil diffusion using installed indoor-simulation of a land slide. Standard sand was used to measure it and this measurement is following the moisture content of standard sand. The result of this experiment follows the moisture content; as the moisture content goes up, the area and speed of soil diffusion goes faster as well. As the average of records by the moisture content was analyzed, the area and speed of land slide are increased proportionally. The shape of diffusion is formed as fanwise. It depends on the moisture content as above; the speed was fast when the moisture content is high, and it was getting narrower and longer as the speed of diffusion was faster.

• Tunnel and Underground Space
• /
• v.25 no.2
• /
• pp.210-219
• /
• 2015

This paper describes a new quantitative process for evaluating the roughness of discontinuity, which is suggested as a qualitative criteria in RMR or Q-system. For this purpose, the Delphi method which is one of the surveying methods was introduced. The selected panels were asked to evaluate the roughness of discontinuities on the Web which was hosted by authors in advance. A total of 3 surveys were performed using JRCs suggested by Barton and Choubey as well as Ai generated by the Monte Carlo simulations. After each survey, the results were provided to all panels for comparing their decisions to others. As surveys proceeded, better consensus and convergence were achieved. With a good agreement of panels on roughness classification, the quantitative criteria for roughness of discontinuity in RMR and Q-system was established in this study.