• Journal of the Korea Concrete Institute
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• v.22 no.4
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• pp.595-603
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• 2010

Monte-Carlo simulation technique is often used in order to predict service life of concrete structure subjected to chloride penetration in marine environment based on probability theory. Monte-Carlo simulation method, however, the method gives different results every time that the simulation is run. On the other hand, moment method, which is frequently used in reliability analysis, needs negligible computational cost compared with simulation technique and gives a constant result for the same problem. Thus, in this study, moment method was applied to the calculation of corrosion-initiation probability. For this purpose, computer programs to calculate failure probabilities are developed using first-order second moment (FOSM) and second-order second moment (SOSM) methods, respectively. From the analysis examples with the developed programs, SOSM was found to give a more accurate result than FOSM does. The sensitivity analysis has shown that the factor affecting the corrosion-initiation probability the most was the cover depth, and the corrosion-initiation probability was influenced more by its coefficient of variation than its mean value.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.40 no.6
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• pp.48-57
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• 2003

In this paper, An 8${\times}$l ID-IDCT processor with adder-based distributed arithmetic(DA) and bit-serial method Is presented. To reduce hardware cost and to improve operating speed, the proposed 8${\times}$1 ID-IDCT used the bit-serial method and DA method. The transform of coefficient equation results in reduction in hardware cost and has a regularity in implementation. The sign extension computation method reduces operation clock. As a result of logic synthesis, The gate count of designed 8${\times}$1 1D-IDCT is 17,504. The sign extension processing block has gate count of 3,620. That is 20% of total 8${\times}$1 ID-IDCT architecture. But the sign extension processing block improves more than twice in throughput. The designed IDCT processes 50Mpixels per second and at a clock frequency of 100MHz.

• The Journal of Korean Physical Therapy
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• v.22 no.6
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• pp.77-83
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• 2010

Purpose: The aim of this study was to do numerical analysis of the wavelength dependence in low level laser therapy (LLLT) using a finite element method (FEM). Methods: Numerical analysis of heat transfer based on a Pennes' bioheat equation was performed to assess the wavelength dependence of effects of LLLT in a single layer and in multilayered tissue that consists of skin, fat and muscle. The three different wavelengths selected, 660 nm, 830 nm and 980 nm, were ones that are frequently used in clinic settings for the therapy of musculoskeletal disorders. Laser parameters were set to the power density of 35.7 W/$cm^2$, a spot diameter of 0.06 cm, and a laser exposure time of 50 seconds for all wavelengths. Results: Temperature changes in tissue based on a heat transfer equation using a finite element method were simulated and were dominantly dependent upon the absorption coefficient of each tissue layer. In the analysis of a single tissue layer, heat generation by fixed laser exposure at each wavelength had a similar pattern for increasing temperature in both skin and fat (980 nm > 660 nm > 830 nm), but in the muscle layer 660nm generated the most heat (660 nm ${\gg}$ 980 nm > 830 nm). The heat generation in multilayered tissue versus penetration depth was shown that the temperature of 660 nm wavelength was higher than those of 830 nm and 980 nm Conclusion: Numerical analysis of heat transfer versus penetration depth using a finite element method showed that the greatest amount of heat generation is seen in multilayered tissue at = 660 nm. Numerical analysis of heat transfer may help lend insight into thermal events occurring inside tissue layers during low level laser therapy.

• Journal of Broadcast Engineering
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• v.22 no.3
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• pp.375-380
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• 2017

This paper has proposed a single image based fog degree quantification method by measuring both transmission and local contrast. The proposed method estimates the foggy expected regions from transmission, and then assesses the size of regions of which transmission values are foggy expected ones and the range of local contrast value on such regions. Compared with fog degree gauged by the scattering coefficient measurement sensor, the proposed method quantifies the fog degree with more than 95% accuracy for images containing various objects and environments. We also developed a technique that measures the local contrast values in process of measuring transmission values. So, the proposed method does not increase complexity compared to the existing transmission method.

• Korean Journal of Veterinary Service
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• v.34 no.4
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• pp.429-439
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• 2011

This article described the comparison of a quick, easy, cheap, effective, rugged and safe (QuEChERS) sample preparation and the classical method established by National Veterinary Research and Quarantine Service (NVRQS) for the determination of pesticide residues in livestock products using GC-tandem mass spectrometry. The classical method by NVRQS used liquid-liquid partioning followed by evaporizing. The modified QuEChERS entailed extraction of 2 g sample with 15 ml acetonitrile containing 1% acetic acid followed by addition of 6 g anhydrous magnesium sulfate and 1.5 g sodium acetate. After centrifugation, 6 ml of the extract underwent a cleanup step (in a technique known as column-based solid phase extraction) using 400 mg each of $C_{18}$ and primary secondary amine sorbents plus 1,200 mg magnesium sulfate. The quantitation of individual pesticides by both methods was based on tissue standard calibration curves with a correlation coefficient in excess of 0.98 for the 24 pesticides. The detection limits by the classical method were ranged 1.3~5.0 ${\mu}g$/kg, with mean recoveries between 76.2% and 114.3% except aldrin (59.3%) and deltamethrin (63.6%). The detection limits by modified QuEChERS were ranged 0.3~6.2 ${\mu}g$/kg, with mean recoveries between 68.0% and 114.3% except dimethipin (152.6%), chlorfenvinphos (138.1%), 4,4-DDT (61.5%), aldrin (60.4%) and chinomethionate (30.3%).

• Journal of the Korean Society of Hazard Mitigation
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• v.11 no.1
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• pp.77-84
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• 2011

The methods of the rational formula and Kajiyama formula have been widely used for estimating the peak flood for design to all kind of hydraulic structure. However, there are many limitations and we have to apply these methods to ungauged basin. These methods require to calculate the Probable Maximum Precipitation (PMP) before determining the Probable Maximum Flood (PMF). Creager's method (Creager et al., 1945) is a kind of estimation of specipic flood and this method provided nonlinear equations based on relationship between the drainage area and PMF in order to calculate the PMF of multipurpose dams over medium-sized. But this method has not much applied in Korea. Creager's coefficient is not clear about its application because this method has never been applied to dams in Korea. Based on the PMP for rainfull-runoff models with the PMF of small and larger dams in this research, the range and standard of Creager's coefficients with parameters are proposed to apply basin areas in Korea.

• Analytical Science and Technology
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• v.32 no.2
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• pp.48-55
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• 2019

The simple and effective analytical method for the quality control of a novel scalp tonic formulation has been developed and optimized in terms of HPLC conditions and sample preparation method, meanwhile, the optimization of preparation condition was using response surface methodology (RSM) based on central composite design (CCD). Oleanolic acid was selected as marker compound because of its bioactivities for alopecia therapy. The developed analytical method and extraction condition were successfully qualified. Coefficient of determination ($r^2$) for the calibration was 0.9997 with a line passing through the origin point in the range of 0.1-100 mg/mL. The limit of detection (LOD) and the limit of quantitation (LOQ) were 17.5 ng/mL and 55.0 ng/mL, respectively. The intra-day and inter-day precision of the method were 0.5-1.4 % and 0.7-1.8 % in relative standard deviation, respectively, while those accuracy were 99.5-100.9 % and 100.0-102.2 %, respectively. The repeatability of oleanolic acid in samples ranged of 0.3-1.9 % based on peak area and 0.3-0.7 % for retention time. Recoveries from samples were 95.0-99.4 % with lower than 1.8 % in relative standard deviation. Overall, the developed analytical method will be used for quality control of this commercial scalp tonic products successfully.

• Food Science of Animal Resources
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• v.44 no.4
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• pp.873-884
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• 2024

Flunixin is a veterinary nonsteroidal anti-inflammatory agent whose residues have been investigated in their original form within tissues such as muscle and liver. However, flunixin remains in milk as a metabolite, and 5-hydroxy flunixin has been used as the primary marker for its surveillance. This study aimed to develop a quantitative method for detecting flunixin and 5-hydroxy flunixin in milk and to strengthen the monitoring system by applying to other livestock and fishery products. Two different methods were compared, and the target compounds were extracted from milk using an organic solvent, purified with C₁₈, concentrated, and reconstituted using a methanol-based solvent. Following filtering, the final sample was analyzed using liquid chromatography-tandem mass spectrometry. Method 1 is environmentally friendly due to the low use of reagents and is based on a multi-residue, multi-class analysis method approved by the Ministry of Food and Drug Safety. The accuracy and precision of both methods were 84.6%-115% and 0.7%-9.3%, respectively. Owing to the low matrix effect in milk and its convenience, Method 1 was evaluated for other matrices (beef, chicken, egg, flatfish, and shrimp) and its recovery and coefficient of variation are sufficient according to the Codex criteria (CAC/GL 71-2009). The limits of detection and quantification were 2-8 and 5-27 ㎍/kg for flunixin and 2-10 and 6-33 ㎍/kg for 5-hydroxy flunixin, respectively. This study can be used as a monitoring method for a positive list system that regulates veterinary drug residues for all livestock and fisheries products.

• The Journal of Engineering Geology
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• v.26 no.2
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• pp.197-205
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• 2016

Rainfall-induced landslide disaster case histories are typically required to establish critical lines based on the decrease coefficient for judging the likelihood of slope collapse or failure; however, reliably setting critical lines is difficult because the number of nationwide disaster case histories is insufficient and not well distributed across the region. In this study, we propose a method for setting the critical area to judge the risk of slope collapse without disaster case history information. Past 10 years rainfall data based on decrease coefficient are plotted as points, and a reference line is established by connecting the outermost points. When realtime working rainfall cross the reference line, warning system is operating and this system can be utilized nationwide through setting of reference line for each AWS (Automatic Weather Station). Warnings were effectively predicted at 10 of the sites, and warnings could have been issued 30 min prior to the landslide movement at eight of the sites. These results indicate a reliability of about 67%. To more fully utilize this model, it is necessary to establish nationwide rainfall databases and conduct further studies to develop regional critical areas for landslide disaster prevention.

• Transactions of the KSME C: Technology and Education
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• v.4 no.1
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• pp.3-10
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• 2016

Heat pump unit performance is represented by the COP(Coefficient of Performance) and expressed by the one point design condition according to KS C 9306. However, when heat pump operated to the real buildings, the simulations are changed continuously according to the actual weather conditions, the building load and heat pump source conditions. The purpose of this paper is to evaluate the APF(Annual performance factor) for a climate dependent building integrated air-to-air heat pump system in major cities in Korea. TRNSYS simulation tool with an international MV standard based IPMVP 4.4.2 was utilized to perform the annual performance analysis. The APF with the multi-performance data based method was calculated as 2.29 for Daejeon residential building case while Busan residential building case appeared as the highest with 2.36.