• Analytical Science and Technology
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• v.25 no.1
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• pp.83-90
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• 2012

The objective of the study was to estimate the measurement uncertainty associated with determination of creatinine (Cr) in urine samples by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Centrifuged urine samples (10 ${\mu}L$) were diluted with 390 ${\mu}L$ of distilled water. To 20 ${\mu}L$ aliquots of diluted urine samples, 30 ${\mu}L$ of internal standard solution (Cr-$d_3$, 5 ${\mu}g/mL$) and 10 ${\mu}L$ of acetonitrile were added and filtered. The samples (1 ${\mu}L$) were introduced into LC-MS/MS with no further pretreatment. Cr was separated on a multi-mode ODS column (Scherzo SM-C18, 75 ${\times}$ 2.0 mm I.D., 3 ${\mu}m$) and quantified by LC-MS/MS operating in MRM mode (Cr, m/z 114.0${\rightarrow}$ 86.0; Cr-$d_3$, m/z 117.0${\rightarrow}$ 89.1). The four factors that contribute uncertainty to the final result were extracted and evaluated. The principal factors of contribution to combined standard uncertainty were sample dilution, calibration curve and repeatability, while the preparation of standard solution was only a minor factor. Relative extended uncertainty of the measured concentration was 14.2% in a real urine sample.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.2
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• pp.153-160
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• 2009

A PM10 (aerodynamic diameter${\leq}$10 ${\mu}m$) sampler is used to quantify the potential human exposure to suspended particulate matter (PM) and to comply with the governmental regulation. This study was conducted to compare and evaluate the same PM10 cutpoint and different slopes between United States Environmental Protection Agency (USEPA) PM10 sampling criterion and American Conference of Governmental Industrial Hygienists/$Comit\acute{e}$ $Europ\acute{e}en$ de Normalization/International Organization for Standardization thoracic PM10 sampling criterion through theory and experiment. Four PM10 samplers according to the USEPA criterion and one RespiCon sampler in accordance with the thoracic PM10 criterion were used in the present study. In addition, one DustTrak monitor was used to measure real time PM10 mass concentrations. All six aerosol samplers were tested in a PM generation chamber using polydisperse fly ash. Theoretical mass concentrations were calculated by applying the measured particle size distribution characteristics (geometric mean = 6.6 ${\mu}m$, geometric standard deviation = 1.9) of fly ash to each sampling criterion. The measured mass concentrations through a chamber experiment were consistent with theoretical mass concentrations in that a RespiCon sampler with the thoracic PM10 criterion collected less PM than a PM10 sampler with the USEPA criterion. The overall chamber experiment results indicated, when a PM10 sampler was used as a reference sampler, that (1) a RespiCon sampler had a normalizing factor of 1.6, meaning that this sampler underestimated an average 60% of PM10 mass sampled from a PM10 sampler, and (2) a DustTrak real-time monitor using a PM10 inlet had a calibration factor of 2.1.

• Journal of the Korean Society for Marine Environment & Energy
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• v.17 no.4
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• pp.283-296
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• 2014

The distribution of heavy metals in the stormwater runoffs from industrial sites around Shihwa Lake that implements the total pollutant load management system (TPLMS) was studied to characterize the temporal changes of metal concentrations and to assess the ecological risk in dissolved and particulate phases of the selected metals. The dissolved Co and Ni concentration demonstrated first flush and tended to decrease with increasing of the duration of rainfall. The intensity of precipitation was found to be the main controlling factor of particulate metals in the stromwater runoffs. The particulate concentration of Pb accounted for 97.2% so the particulate phase was its main form. Other metals followed the sequence: Pb>Cu>Cd>Co>Zn>Ni. The particulate-dissolved partitioning coefficient ($K_d$) indicated that the $K_d$ of Pb were bigger than that of other metals because the metal Pb in the stormwater runoffs is quickly removed into the particulate phase. In a single day rainfall event, total runoff fluxes for total metals as the sum of dissolved and particulate forms through only two sewer outlets were 2.21 kg for Co, 30.5 kg for Ni, 278.3 kg for Cu, 398.3 kg for Zn, 0.39 kg for Cd and 40.0 kg for Pb, respectively. Given the annual rainfall, the number of rain days and the basin area for total pollutant load management system (TPLMS) of Shihwa area, enormous amount of non-point metal pollutants were entered into Lake with any treatment. The dissolved metals (e.g., Ni, Cu and Zn) in the stormwater runoffs exceeded the acute water quality criteria. Additionally, all metals were significantly enriched in the particulate phase and exceeded the PEL criteria of sediment quality guidelines (SQGs). These results indicated that the heavy metals in the stormwater runoffs may pose a very high ecological risk to the coastal environments and ecosystem.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.4
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• pp.27-35
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• 2008

This work proposes a 14b 150MS/s 0.13um CMOS ADC for SDR systems requiring simultaneously high resolution, low power, and small size at high speed. The proposed ADC employs a calibration-free four-step pipeline architecture optimizing the scaling factor for the input trans-conductance of amplifiers and the sampling capacitance in each stage to minimize thermal noise effects and power consumption at the target resolution and sampling rate. A signal- insensitive 3-D fully symmetric layout achieves a 14b level resolution by reducing a capacitor mismatch of three MDACs. The proposed supply- and temperature- insensitive current and voltage references with on-chip RC filters minimizing the effect of switching noise are implemented with off-chip C filters. The prototype ADC in a 0.13um 1P8M CMOS technology demonstrates a measured DNL and INL within 0.81LSB and 2.83LSB, at 14b, respectively. The ADC shows a maximum SNDR of 64dB and 61dB and a maximum SFDR of 71dB and 70dB at 120MS/s and 150MS/s, respectively. The ADC with an active die area of $2.0mm^2$ consumes 140mW at 150MS/s and 1.2V.

• International Journal of Highway Engineering
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• v.18 no.3
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• pp.47-57
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• 2016

PURPOSES : This study aims to examine the differences between the existing traffic demand forecasting method and the traffic demand forecasting method considering future regional development plans and new road construction and expansion plans using a four-step traffic demand forecast for a more objective and sophisticated national highway maintenance. This study ultimately aims to present future pavement deterioration and budget forecasting planning based on the examination. METHODS : This study used the latest data offered by the Korea Transport Data Base (KTDB) as the basic data for demand forecast. The analysis scope was set using the Daejeon Metropolitan City's O/D and network data. This study used a traffic demand program called TransCad, and performed a traffic assignment by vehicle type through the application of a user equilibrium-based multi-class assignment technique. This study forecasted future traffic demand by verifying whether or not a realistic traffic pattern was expressed similarly by undertaking a calibration process. This study performed a life cycle cost analysis based on traffic using the forecasted future demand or existing past pattern, or by assuming the constant traffic demand. The maintenance criteria were decided according to equivalent single axle loads (ESAL). The maintenance period in the concerned section was calculated in this study. This study also computed the maintenance costs using a construction method by applying the maintenance criteria considering the ESAL. The road user costs were calculated by using the user cost calculation logic applied to the Korean Pavement Management System, which is the existing study outcome. RESULTS : This study ascertained that the increase and decrease of traffic occurred in the concerned section according to the future development plans. Furthermore, there were differences from demand forecasting that did not consider the development plans. Realistic and accurate demand forecasting supported an optimized decision making that efficiently assigns maintenance costs, and can be used as very important basic information for maintenance decision making. CONCLUSIONS : Therefore, decision making for a more efficient and sophisticated road management than the method assuming future traffic can be expected to be the same as the existing pattern or steady traffic demand. The reflection of a reliable forecasting of the future traffic demand to life cycle cost analysis (LCCA) can be a very vital factor because many studies are generally performed without considering the future traffic demand or with an analysis through setting a scenario upon LCCA within a pavement management system.

• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.1
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• pp.47-56
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• 2008

Risperidone is a widely prescribed atypical antipsychotic agent. Approved by the FDA as the first drug to treat irritability associated with autism in children, it is also used to treat tic disorder and Tourette's syndrome. Its adverse reactions related to dentistry include dry mouth, the mechanism of which is yet to be identified. The aim of this study is to identify, at the cellular level, how and to what extent risperidone affects intracellular free calcium concentration ($[Ca^{2+}]_i$), an primary intracellular factor in the regulation of fluid secretion in salivary gland cells. The human salivary gland cell line (HSG) was grown in MEM supplemented with 10% BCS. In order to measure $[Ca^{2+}]_i$, Fura-2/AM was loaded in the HSG, and fluorescence at 340 nm/380 nm excitation was measured in the 500 nm emission ratio. After every experiment, a calibration experiment was conducted in order to readjust the ratio to the actual $[Ca^{2+}]_i$. Changes in $[Ca^{2+}]_i$ were measured in the presence of carbachol, ATP and histamine. The researcher then explored how the pretreatment of risperidone affected such changes. Findings of this study include: 1. In HSG, $[Ca^{2+}]_i$ increased due to the addition of carbachol, ATP and histamine. The presence of risperidone inhibited the action of histamine on this process, while making little effect on that of carbachol and ATP. 2. A quantification of $[Ca^{2+}]_i$ in relation to histamine of different concentrations indicates that the effect of histamine was concentration dependent with an $EC_{50}$ of $3.3{\pm}0.5\;{\mu}M$. 3. The inhibitory effect of risperidone on histamine-induced $[Ca^{2+}]_i$ was concentration-dependent with an $IC_{50}$ of $104.4{\pm}14\;nM$. 4. Risperidone inhibits histamine-induced Ca2+ release from endoplasmic reticulum and influx of extracellular $Ca^{2+}$ in HSG cells(p<0.05).

• Journal of the Korean Society for Marine Environment & Energy
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• v.16 no.2
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• pp.71-81
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• 2013

Trace metal concentration in sediment cores from the outer sea of Lake Shihwa were determined to study the vertical profiles of metal concentrations and to evaluate the levels of metal contamination. Sediment pollution assessment was carried out using enrichment factor (EF) and geo-accumulation index (Igeo). The mean concentration of metals were 58.8 mg/kg for Cr, 10.3 mg/kg for Co, 22.8 mg/kg for Ni, 18.1 mg/kg for Cu, 74.0 mg/kg for Zn, 6.75 mg/kg for As, 0.14 mg/kg for Cd, 27.4 mg/kg for Pb and 0.026 mg/kg for Hg, respectively. The mean EF values for Cu, Zn, As, Cd and Hg were greater than 1.5 in sediment cores, indicating that these metals in sediments are slightly enriched by anthropogenic activities. The geo-accumulation index (Igeo) suggested unpolluted status for metals of sediments collected from outer see of Lake Shihwa. Igeo values for Cu and Hg nearby LNG station (site C, D, E) ranged from 1 to 2, indicating moderately to unpolluted pollution status for those metals. Even if the higher concentrations of trace metals nearby LNG station were observed, there is significantly positive relationship between Al and trace metals. Thus, the sediment grain size plays an important roles in influencing the distribution of trace metals in sediment cores from the outer sea of Lake Shihwa. Based on the comparison with sediment quality guidelines such as threshold effect level and probable effect level in Korea, the concentration of metals in sediments from outer sea of Lake Shihwa are likely to result in no harmful effects on sediment-dwelling organisms.

• Journal of Korean Society of Steel Construction
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• v.29 no.6
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• pp.467-477
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• 2017

The live load effect of KL-510 of the current Korean bridge design code is examined by comparing with that of the multiple trucks of which the weights are statistically estimated from measured traffic data as well as with those of the related live load models. The truck weight data measured on the expressway before and after overweight enforcement are used to obtain the truck weights following the same procedures in deciding the live load model of the design codes and the results are compared with the load effect of KL-510. KL-510 yields a very uniform loading effect compared with the multiple truck effects when the weights are estimated from the data which contains some of the heavy trucks over the operational weight limit. KL-510 yields consistent results with the live load of AASHTO LRFD and shows less variation than the past load model DB-24 over the span lengths considered in this study. As a result of this research, the actual truck combinations equivalent to the notional KL-510 load model are constructed and it can be applied to the evaluation of the existing bridge and the calibration of the load factor of the permit vehicle.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.26 no.4
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• pp.217-224
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• 2014

Cochlodinium polykrikoides is a typical harmful algal species which generates the red-tide in the coastal zone, southern Korea. Accurate algal growth model can be established and then the prediction of the red-tide occurrence using this model is possible if the information on the optimal growth model parameters are available because it is directly related between the red-tide occurrence and the rapid algal bloom. However, the limitation factors on the algal growth, such as light intensity, water temperature, salinity, and nutrient concentrations, are so diverse and also the limitation function types are diverse. Thus, the study on the algal growth model development using the available laboratory data set on the growth rate change due to the limitation factors are relatively very poor in the perspective of the model. In this study, the growth model on the C. polykrikoides are developed and suggested as the optimal model which can be used as the element model in the red-tide or ecological models. The optimal parameter estimation and an error analysis are carried out using the available previous research results and data sets. This model can be used for the difference analysis between the lab. condition and in-situ state because it is an optimal model for the lab. condition. The parameter values and ranges also can be used for the model calibration and validation using the in-situ monitoring environmental and algal bloom data sets.

• Journal of Wetlands Research
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• v.14 no.4
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• pp.519-535
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• 2012

In order to establish a rainfall-runoff model, calibration of hydrological parameters for the model is very important. Especially, Curve Number(CN), estimated by NRCS method, is a main factor to apply unit hydrograph theory to calculation of peak discharge. For using NRCS method, it is needed selecting AMC because CN is strongly connected with that. In this study, we focus our concern on finding a applicable standard for selecting AMC for CN. For this, three dams which are Boryeong, Habchon, Namgang are selected as target basins to use observed data including rainfall and dam inflow. As a result of this research, it is found that CN must be included as a calibrated parameter to calculate effective rainfall for the rainfall-runoff model. Also, it is preferred to use PWRMSE of HEC-HMS program as a objective function for optimizing hydrological parameters. From the analyzing result of variation of AMC for peak discharge, it is recommended to apply AMC-III to estimation of CN for calculating effective rainfall of design hydrograph.