• Journal of Environmental Science International
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• v.7 no.6
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• pp.793-801
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• 1998

In this study, the Dilution Method is used to measure river discharge through the hydraulic model test. the dilution method is divided into Constant-Rate-Infection Method and Slug-Injection Method in the river discharge measurement techniques. When the dilution method is applied in the hydraulic model flume, it is analyzed that the estimated error of constant-rate-injection method is less than that of the slug-in-jection method, and the result shows that floodflow analysis is more efficient than lowflow analysis as compared observed discharge with calculated discharge. The result of statistical error analysis shows that the constant-rate-injection method is appropriate technique for the measurement of the river discharge. Therefore, the dilution method among the river discharge measurement techniques can be applied for the river basin which can't be measured with current meter or unsteady-flow regime in the urban-small drainage or hydraulic structure equipment area and can be obtained more exact results than any other discharge measurement techniques.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.1013-1022
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• 2005

Because depth of deposit is deeper as well as compressibility is very larger than the other regions in Korea, behaviour of settlement at Nak-Dong river estuarine causes hot issue at ground improvement. Defined properties for design differ from measurement. Therefore it affects cost of construction. This study presents design standard to engineers as it defined properties of compressibility at Jangyu Area of Nak-Dong river estuarine. To search value of representation for region, back analysis was performed using the measurement. To verify that, the measurement of recently designed site was confirmed, and the cost of construction with properties of consolidation was calculated.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.12
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• pp.1898-1904
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• 2001

Measurement uncertainty should be evaluated according to ISO/IEC 17025. In Flow measurement area, uncertainty evaluation scheme was applied to the reference flow meter, sonic nozzle. Uncertainty was calculated by evaluating various uncertainty factors affected in flow measurement. The expanded uncertainty(U) of the sonic nozzle was 2.1$\times$ 10$^{-3}$ (confidence level of 95 %). This evaluation example will be useful in flow measurement uncertainty determination of other flow meters.

• Transactions of Materials Processing
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• v.5 no.4
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• pp.343-352
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• 1996

One of the preferred methods that can be used to verify the results of finite element analysis is to measure surface strains of the deformed part for purpose of direct comparison with simulation results. Instead of using the usual manual method the vision-based measurement method is capable of determining surface geometry and strain from the deformed grid pattern automatically with the help of a computer. To obtain strain distribution over an area, the coordinates of such a surface grid are determined from the multiple video images by applying the photogrammetry principle. Methods to improve the overall accuracy of the vision-based strain measurement system are explored and the possible accuracies that can be attained by such a measurement method are discussed. A major emphasis is placed on the initial grid application method its accuracy and ease of subsequent image processing. Finite element analyses of limiting dome height(LDH) test are carried out and the results of them are compared with exsperimen-tal data.

• IEMEK Journal of Embedded Systems and Applications
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• v.6 no.2
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• pp.76-85
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• 2011

In conventional methods for measuring snow height, a graduated pole is installed on ground in an area of interest and the snow height is manually read from the pole. Recently, automated snow height measurement systems have been introduced to improve the conventional methods. The automated measurement systems, however, are quite expensive since they use the reflection of ultrasonic waves or laser beams. In addition, it is not easy to move the location of the automated measure systems. This paper proposes a snow height measurement system equipped with image sensors and wireless communication capability via a USN and the Internet. The proposed system has a resolution of 5 cm and easy to deploy without difficulties, which can be usefully used to monitor unforseen local snowfalls.

• Particle and aerosol research
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• v.15 no.2
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• pp.67-78
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• 2019

Since existing measurement sites are required to construct a high-cost PM measuring device and a measuring site of a large area, there is a limit to the construction of a high-resolution measurement network. Therefore, it is necessary to develop a low-cost, high-performance PM measuring device (as an alternative technology) that can increase the resolution of PM measurement, and it is necessary to establish a base to provide real-time PM information for whole people. Therefore, in this study, the alternative technique (light scattering method) for achieving the above object was examined, performance evaluation was carried out, and it was verified that the light scattering method was usable. Various PM measurement results were compared and analyzed to find PM monitoring points and resolutions we would like to propose.

• Journal of Sensor Science and Technology
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• v.33 no.5
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• pp.378-383
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• 2024

This study developed a buoyancy-based level sensor composed of a buoyant object, a sensing unit, and a signal generation unit to meet the demand of low-cost, high-efficiency inundation-detection sensors. The volume of the submerged buoyant object remained nearly constant even in the presence of water-level fluctuations, allowing stable water-level data acquisition. The measurement resolution and measurement repeatability were confirmed to be within 0.4 mm and 0.3%, respectively. LoRa-based communication was used to implement the IoT-based inundation-detection sensor. The measurement deviation between the sensors is approximately 0.15%. The unresponsive level at which measurement was not possible was confirmed to be approximately 2 mm. Excluding this unresponsive range, the water level measurements exhibited very high linearity, allowing precise measurements. Furthermore, a test bed was established in an inundation-vulnerable area using buoyancy-based level sensors.

• Journal of Korean Society for Atmospheric Environment
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• v.25 no.4
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• pp.289-303
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• 2009

The chemical and meteorological effects on the concentration variations of ozone ($O_3$) were evaluated based on the intensive air quality measurement (5 pollutants and aromatic volatile organic compounds (AVOCs)) in and out-side an urban valley during spring and summer of 2006. The 5 pollutants measured in the study area include $O_3$, $NO_2$, NO, $PM_{10}$, and CO; the AVOCs include benzene (BEN), toluene (TOL), ethylbenzene (EB), m,p-xylene (MPX), and o-xylene (OX). For the purpose of this study, study areas were classified into two categories: valley area (VA) with a semi-closed topography covering a number of industrial complex, public building, and mountains and non-valley area (NVA) surrounding the suburban and residential areas. In general, the mean concentration levels of most pollutants (except for $PM_{10}$) in the VA were higher than those in the NVA. It was found that the average $O_3$ increase in the VA during spring might result from the combined effects such as the photochemical production from diverse anthropogenic sources and the $O_3$ accumulation due to geographical features (e.g., the semi-closed topography) and wind conditions (e.g., a low wind speed). In addition, the nocturnal $O_3$ increase in the VA during spring was primarily caused by local wind conditions (e.g., mountain and valley winds) with the low wind speed (approximately $1{\sim}2\;m\;s^{-1}$). On the other hand, the $O_3$ difference between the two areas during summer might be because of the photo-chemical production with the $O_3$ precursors (especially the AVOCs) rather than the contribution of wind conditions.

• Korean Journal of Animal Reproduction
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• v.23 no.1
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• pp.37-43
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• 1999

The image analyser was used for the measurement of the morphological changes of the spermatogenic cells and seminiferous tubules in the pheasant during the breeding and non breeding season. 1. The seminiferous tubules were enlarged 2.57 times during the breeding season than during the non breeding season. Only Sertoli cells and spermatogonia in the seminiferous tubules can be found during the non breeding season. 2. There is no significantly difference in the ratio of nucleus area against that of cell size in the spermatogonium between breeding and non breeding season. The ratio of area was 28.71% and 29.11%, respectively. However, the enlargement of spermatogonium was noticed during the non breeding season. 3. The highest value of the ratio of the nucleus area against that of cell size among the germ cells was measured 37.40% in the pachytene phase of the spermatocyte during the breeding season. 4. The ratio of nucleus area against that of cell size in the spermatid was 22.53%.

• The Korean Journal of Pain
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• v.33 no.1
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• pp.54-59
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• 2020

Background: The median nerve cross-sectional area (MNCSA) is a useful morphological parameter for the evaluation of carpal tunnel syndrome (CTS). However, there have been limited studies investigating the anatomical basis of median nerve flattening. Thus, to evaluate the connection between median nerve flattening and CTS, we carried out a measurement of the median nerve thickness (MNT). Methods: Both MNCSA and MNT measurement tools were collected from 20 patients with CTS, and from 20 control individuals who underwent carpal tunnel magnetic resonance imaging (CTMRI). We measured the MNCSA and MNT at the level of the hook of hamate on CTMRI. The MNCSA was measured on the transverse angled sections through the whole area. The MNT was measured based on the most compressed MNT. Results: The mean MNCSA was 9.01 ± 1.94 ㎟ in the control group and 6.58 ± 1.75 ㎟ in the CTS group. The mean MNT was 2.18 ± 0.39 mm in the control group and 1.43 ± 0.28 mm in the CTS group. Receiver operating characteristics curve analysis demonstrated that the optimal cut-off value for the MNCSA was 7.72 ㎟, with 75.0% sensitivity, 75.0% specificity, and an area under the curve (AUC) of 0.82 (95% confidence interval [CI], 0.69-0.95). The best cut off-threshold of the MNT was 1.76 mm, with 85% sensitivity, 85% specificity, and an AUC of 0.94 (95% CI, 0.87-1.00). Conclusions: Even though both MNCSA and MNT were significantly associated with CTS, MNT was identified as a more suitable measurement parameter.