• Title/Summary/Keyword: storage ratio

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Evaluating Applicability of Hunt's Analytical Solution for Groundwater Pumping from a Leaky Aquifer (누수대수층 지하수 양수에 관한 Hunt 해석해의 적용성 평가)

  • Lee, Jeongwoo;Chung, Il-Moon
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.40 no.6
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    • pp.555-561
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    • 2020
  • In this study, the applicability of Hunt's analytical solution for a two-layered leaky aquifer system, which was developed to estimate stream depletion due to the groundwater pumping of the upper shallow aquifer, was evaluated. The 5-year averaged stream depletions were estimated using Hunt's analytical solution for various combinations of hydraulic characteristic values such as transmissivity, storage coefficient of the two aquifers, interlayer leakage coefficient, stream-well distance, hydraulic conductivity of the streambed, and stream width. Through comparison with the numerical solution accurately simulated with a MODFLOW groundwater flow model, the analytical solution derived by regarding the stream width as a point was evaluated. It was found that the error in the stream depletion calculated by the analytical solution can be reduced to less than 0.05 when the stream-well distance is greater than the stream width or when the stream depletion factor (SDF) is more than about 3,000 days. In addition, when the streambed hydraulic conductivity is less than 1 m/d, the hydraulic diffusion coefficient of the lower aquifer layer is less than 100 ㎡/d, the hydraulic diffusion coefficient ratio of the upper and lower aquifer layers is 5 or more, and the leakage coefficient between the layers is less than 0.0004 m/d, the overall analytical solutions were overestimated compared with the numerical solutions.

Risk assessment for norovirus foodborne illness by raw oyster (Ostreidae) consumption and economic burden in Korea

  • Yoo, Yoonjeong;Oh, Hyemin;Lee, Yewon;Sung, Miseon;Hwang, Jeongeun;Zhao, Ziwei;Park, Sunho;Choi, Changsun;Yoon, Yohan
    • Fisheries and Aquatic Sciences
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    • v.25 no.5
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    • pp.287-297
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    • 2022
  • The objective of this study was to evaluate the probability of norovirus foodborne illness by raw oyster consumption. One hundred fifty-six oyster samples were collected to examine the norovirus prevalence. The oyster samples were inoculated with murine norovirus and stored at 4℃-25℃. A plaque assay determined norovirus titers. The norovirus titers were fitted with the Baranyi model to calculate shoulder period (h) and death rate (Log PFU/g/h). These kinetic parameters were fitted to a polynomial model as a function of temperature. Distribution temperature and time were surveyed, and consumption data were surveyed. A dose-response model was also searched through literature. The simulation model was prepared with these data in @RISK to estimate the probability of norovirus foodborne. One sample of 156 samples was norovirus positive. Thus, the initial contamination level was estimated by the Beta distribution (2, 156), and the level was -5.3 Log PFU/g. The developed predictive models showed that the norovirus titers decreased in oysters under the storage conditions simulated with the Uniform distribution (0.325, 1.643) for time and the Pert distribution (10, 18, 25) for temperature. Consumption ratio of raw oyster was 0.98%, and average consumption amount was 1.82 g, calculated by the Pert distribution [Pert {1.8200, 1.8200, 335.30, Truncate (0, 236.8)}]. 1F1 hypergeometric dose-response model [1 - (1 + 2.55 × 10-3 × dose)-0.086] was appropriate to evaluate dose-response. The simulation showed that the probability of norovirus foodborne illness by raw oyster consumption was 5.90 × 10-10 per person per day. The annual socioeconomic cost of consuming raw oysters contaminated with norovirus was not very high.

Shear-wave elasticity imaging with axial sub-Nyquist sampling (축방향 서브 나이퀴스트 샘플링 기반의 횡탄성 영상 기법)

  • Woojin Oh;Heechul Yoon
    • The Journal of the Acoustical Society of Korea
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    • v.42 no.5
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    • pp.403-411
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    • 2023
  • Functional ultrasound imaging, such as elasticity imaging and micro-blood flow Doppler imaging, enhances diagnostic capability by providing useful mechanical and functional information about tissues. However, the implementation of functional ultrasound imaging poses limitations such as the storage of vast amounts of data in Radio Frequency (RF) data acquisition and processing. In this paper, we propose a sub-Nyquist approach that reduces the amount of acquired axial samples for efficient shear-wave elasticity imaging. The proposed method acquires data at a sampling rate one-third lower than the conventional Nyquist sampling rate and tracks shear-wave signals through RF signals reconstructed using band-pass filtering-based interpolation. In this approach, the RF signal is assumed to have a fractional bandwidth of 67 %. To validate the approach, we reconstruct the shear-wave velocity images using shear-wave tracking data obtained by conventional and proposed approaches, and compare the group velocity, contrast-to-noise ratio, and structural similarity index measurement. We qualitatively and quantitatively demonstrate the potential of sub-Nyquist sampling-based shear-wave elasticity imaging, indicating that our approach could be practically useful in three-dimensional shear-wave elasticity imaging, where a massive amount of ultrasound data is required.

Shielding Performance of PLA and Tungsten Mixture using Research Extruder (연구용 압출기를 활용한 PLA와 텅스텐 혼합물의 차폐 성능)

  • Do-Seong Kim;Tae-Hyung Kim;Myeong-Seong Yoon;Sang-Hyun Kim
    • Journal of the Korean Society of Radiology
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    • v.17 no.4
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    • pp.557-564
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    • 2023
  • In this study, 3D printing technology was used to compensate for the shortcomings of the use of lead, which has proven to have excellent shielding performance, and to control unnecessary human exposure. 3D printers can implement three-dimensional shapes and can immediately apply individual ideas, which has great advantages in maintaining technology supplementation while reducing the cost and duration of prototyping. Among the various special 3D printers, the FDM method was adopted, and the filament used for output was manufactured using a research extruder by mixing two materials, PLA (Poly-Lactic-Acid) and tungsten. The purpose was to verify the validity through dose evaluation and to provide basic information on the production of chapezones of various materials. The mixed filament was implemented as a morphological shield. Filaments made of a research extruder by mixing PLA and tungsten were divided into 10 %, 20 %, 30 %, 40 %, and 50 % according to the tungsten content ratio. Through the process of 3D Modeling, STL File storage, G-code generation, and output, 10 cm × 10 cm × 0.5 cm was manufactured, respectively, and dose and shielding ability were evaluated under the conditions of tube voltages of 60 kVp, 80 kVp, 100 kVp, 120 kVp, and tube currents of 20 mAs and 40 mAs.

Analysis of electrical resistivity characteristics according to the mixing ratio of coarse fillings in artificial rock joint (인공 암반절리의 조립토 충진물 혼합비에 따른 전기비저항 특성 분석)

  • Haeju Do;Tae-Min Oh;Hangbok Lee
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.25 no.2
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    • pp.141-155
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    • 2023
  • Monitoring technology based on electrical resistivity is widely used for non-destructive data collection and health analysis of underground structures and tunnels. Vulnerable sections such as fault zone generates many problems during construction of the tunnel. These problems cause displacement and stress changes of the ground. Therefore, it is necessary to predict the state of the fault zone section to ensure the mechanical stability of the underground structure. Monitoring the size of joints and the porosity of the fillings is essential for rocks. Previous studies have not considered the variety of fillings in rock joints. In this study, electrical resistivity tests were conducted according to the particle mixing state of the sandy fillings. When the size of fillings is decreased at the constant porosity, the electrical resistivity tends to increase. The results of this study are expected to be useful as basic electrical resistivity data for predicting the ground conditions and evaluation of the ground behavior that is containing sandy fillings in the rock joint for tunnels.

Flash memory system with spatial smart buffer for the substitution of a hard-disk (하드디스크 대용을 위한 공간적 스마트 버퍼 플래시 메모리 시스템)

  • Jung, Bo-Sung;Jung, Jung-Hoon
    • Journal of the Korea Society of Computer and Information
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    • v.14 no.3
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    • pp.41-49
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    • 2009
  • Flash memory has become increasingly requestion for the importance and the demand as a storage due to its low power consumption, cheap prices and large capacity medium. This research is to design a high performance flash memory structure for the substitution of a hard-disk by dynamic prefetching of aggressive spatial locality from the spatial smart buffer system. The proposed buffer system in a NAND flash memory consists of three parts, i.e., a fully associative victim buffer for temporal locality, a fully associative spatial buffer for spatial locality, and a dynamic fetching unit. We proposed new dynamic prefetching algorithm for aggressive spatial locality. That is to use the flash memory instead of the hard disk, the proposed flash system can achieve better performance gain by overcoming many drawbacks of the flash memory by the new structure and the new algorithm. According to the simulation results, compared with the smart buffer system, the average miss ratio is reduced about 26% for Mediabench applications. The average memory access times are improved about 35% for Mediabench applications, over 30% for Spec2000 applications.

Machine Learning-based Phase Picking Algorithm of P and S Waves for Distributed Acoustic Sensing Data (분포형 광섬유 센서 자료 적용을 위한 기계학습 기반 P, S파 위상 발췌 알고리즘 개발)

  • Yonggyu, Choi;Youngseok, Song;Soon Jee, Seol;Joongmoo, Byun
    • Geophysics and Geophysical Exploration
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    • v.25 no.4
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    • pp.177-188
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    • 2022
  • Recently, the application of distributed acoustic sensors (DAS), which can replace geophones and seismometers, has significantly increased along with interest in micro-seismic monitoring technique, which is one of the CO2 storage monitoring techniques. A significant amount of temporally and spatially continuous data is recorded in a DAS monitoring system, thereby necessitating fast and accurate data processing techniques. Because event detection and seismic phase picking are the most basic data processing techniques, they should be performed on all data. In this study, a machine learning-based P, S wave phase picking algorithm was developed to compensate for the limitations of conventional phase picking algorithms, and it was modified using a transfer learning technique for the application of DAS data consisting of a single component with a low signal-to-noise ratio. Our model was constructed by modifying the convolution-based EQTransformer, which performs well in phase picking, to the ResUNet structure. Not only the global earthquake dataset, STEAD but also the augmented dataset was used as training datasets to enhance the prediction performance on the unseen characteristics of the target dataset. The performance of the developed algorithm was verified using K-net and KiK-net data with characteristics different from the training data. Additionally, after modifying the trained model to suit DAS data using the transfer learning technique, the performance was verified by applying it to the DAS field data measured in the Pohang Janggi basin.

Characteristic and Stability of Lipids in Yackwa at Various Shortening Ratios (쇼트닝 혼합유로 만든 약과의 유지 특성과 유지 안정성)

  • Kim, So-Won;Kim, Myong-Ae
    • Journal of the Korean Society of Food Culture
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    • v.24 no.3
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    • pp.344-349
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    • 2009
  • The principal objective of this study was to assess the effects of various ratios of sesame oil to shortening on the characteristics and stability of lipids in Yackwa. The sesame oil to shortening ratios assessed herein were 100:0, 75:25, 50:50, and 1:100. The lipid contents of Yackwa prepared with various shortening ratios ranged from 25.20 to 29.12%. The lipids in these Yackwa consisted primarily of the frying oil (soybean oil), and the oil contents were measured between 84-90%. The fatty acid compositions of the lipids in the Yackwa were unrelated to the ratio of shortening. The fatty acid compositions were as follows: linoleic acid 49.1-51.27%, oleic acid 26.05-26.77%, palmitic acid 10.07-11.71%, linolenic acid 5.51-5.72% and stearic acid 4.51-4.68%. These compositions were similar to that of soybean oil, which was the frying oil used to prepare the Yackwa. The acid value, peroxide value, and carbonyl value of the lipids in Yackwa did not differ with the various shortening ratios used during the storage time. Stability of lipids in Yackwa were mainly effected by frying oil. Our results suggest that shortening should prove useful as a substitute for sesame oil in the preparation of Yackwa.

Analysis of grout injection distance in single rock joint (단일절리 암반에서 그라우팅 주입거리 분석)

  • Ji-Yeong Kim;Jo-Hyun Weon;Jong-Won Lee;Tae-Min Oh
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.25 no.6
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    • pp.541-554
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    • 2023
  • The utilization of underground spaces in relation to tunnels and energy/waste storage is on the rise. To ensure the stability of underground spaces, it is crucial to reinforce rock fractures and discontinuities. Discontinuities, such as joints, can weaken the strength of the rock and lead to groundwater inflow into underground spaces. In order to enhance the strength and stability of the area around these discontinuities, rock grouting techniques are employed. However, during rock grouting, it is impossible to visually confirm whether the grouting material is being smoothly injected as intended. Without proper injection, the expected increases in strength, durability, and degree of consolidation may not be achieved. Therefore, it is necessary to predict in advance whether the grouting material is being injected as designed. In this study, we aimed to assess the injection performance based on injection variables such as the water/cement mixture ratio, injection pressure, and injection flow using UDEC (Universal Distinct Element Code) numerical program. Additionally, numerical results were validated by the lab experiment. The results of this study are expected to help optimize variables such as injection material properties, injection time, and pump pressure in the grouting design in the field.

Characteristics of Water Environment on Manun Reservoir (중산간 농업용 만운저수지의 수질환경특성)

  • Nam, Gui-Sook;Jang, Jeong-Ryeol;Lee, Gwang-Sik;Yoon, Keung-Sup;Lee, Sang-Joon
    • Korean Journal of Environmental Agriculture
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    • v.22 no.1
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    • pp.16-25
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    • 2003
  • Manun Reservoir, located in Andong district has the capacity of 2 million tons in irrigation water supply with the drainage area of $23.8\;km^2$. Manun Reservoir is over fifty year old, and shallow in depth. The ratio of drainage area (DA) to reservoir surface area (SA) as an effective physical parameter on water quality was 56.1 and was higher than those of other agricultural reservoirs. The ratio of reservoir storage (ST) to SA in Manun Reservoir was 4.79, and the mean depth was below 8m. Both ratios of DS/SA, total area (TA)/ST and ST/SA in Manun Reservoir were relatively higher than those in other agricultural reservoir and natural lakes in Korea. These physical parameters in Manun Reservoir, however, had a eutropic potential significance. Average of COD, IN, and TP in Manun Reservoir were 11.1 mg/L 1.426 mg/L, 0.093 mg/L, respectively. In the inflow stream of Manun Reservoir, the TN ($1.426{\sim}3.809\;mg/L$) was higher than those in reservoir. Only Lyngbya spp. was dominant in phytoplankton for this study period and Gymnodinium spp., Peridinium spp., and Cryptomonas spp. were dominant in zooplankton. According to the Carlson's trophic status index, Mnnun Reservoir was eutrophic in 1996, 1997, and 1999, and hypertrophic in 1998.