• Title/Summary/Keyword: Time Determination

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Quantification of Chloride Diffusivity in Steady State Condition in Concrete with Fly Ash Considering Curing and Crack Effect (재령 및 균열효과를 고려한 플라이애시 콘크리트의 정상상태 염화물 확산 특성의 정량화)

  • Yoon, Yong-Sik;Cheon, Ju-Hyun;Kwon, Seung-Jun
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.7 no.2
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    • pp.109-115
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    • 2019
  • In case of the cracks in concrete, the penetration of deterioration ions such as chloride ions in to cracks is accelerated. According to the penetration of chloride ions, structural and durability problems to RC(Reinforced Concrete) structures are caused. In this study, the accelerated chloride diffusion coefficient which is in steady state is evaluated for 2 year aged normal and high strength FA(Fly Ash) concrete, after a range of crack depths are induced up to 1.0 mm in 56 aged day. Considering crack effect by linear regression analysis, high strength concrete has slightly less increasing ratio of diffusion coefficient by crack than normal strength concrete, and diffusion coefficient increases non-linearly as crack width is increased. Also, In two types of concrete, crack effect decrease as the curing period increase. In the case of quantifying crack and curing effect by using exponential function form, the coefficients of determination are higher than those of linear regression analysis. Under steady state, it is thought that there is not a high correlation between the crack effect and the curing effect, and considering the two independent effects, it is believed that reasonable prediction equation for diffusion of concrete with crack can be proposed.

Comparison and discussion of MODSIM and K-WEAP model considering water supply priority (공급 우선순위를 고려한 MODSIM과 K-WEAP 모형의 비교 및 고찰)

  • Oh, Ji-Hwan;Kim, Yeon-Su;Ryu, Kyong Sik;Jo, Young Sik
    • Journal of Korea Water Resources Association
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    • v.52 no.7
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    • pp.463-473
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    • 2019
  • This study compared the characteristics of the optimization technique and the water supply and demand forecast using K-WEAP (Korea-Water Evaluation and Planning System) model and MODSIM (Modified SIMYLD) model considering wtaer supply priority. Currently, The national water resources plan applied same priority for municipal, industrial and agricultural demand. the K-WEAP model performs the ratio allocation to satisfy the maximum satisfaction rate, whereas the MODSIM model should be applied to the water supply priority of demands. As a result of applying the priority, water shortage decreased by an average of $1,035,000m^3$ than same prioritized results. It is due to the increase of the return flow rate as the distribution of Municipal and industrial water increases. Comparing the analysis results of K-WEAP and MODSIM applying the priorities, the relative error was within 5.3% and the coefficient of determination ($R^2$) was 0.9999. In addition, if both models provide reasonable water balance analysis results, K-WEAP is superior to GUI convenience for model construction and data processing. However, MODSIM is more effective in simulation time efficiency. It is expected that it will be able to carry out analysis according to various scenarios using the model.

Experimental determination of design parameters for filtration trench using phosphorus removal granular materials (인 제거 입상소재를 적용한 여과수로 설계인자의 실험적 결정)

  • Jang, Yeoju;Lim, Hyunman;Jung, Jinhong;Ahn, Kwangho;Chang, Hyangyoun;Park, Nari;Kim, Weonjae
    • Journal of Korean Society of Water and Wastewater
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    • v.33 no.1
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    • pp.9-16
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    • 2019
  • The algal blooms in stagnant streams and lakes have caused many problems. Excessive algae leads to disturbance of ecosystem and overload of water treatment processes. Therefore, phosphorus(P), source of algal blooms, should be controlled. In this study, a filtration trench has been developed to convert dissolved phosphorus into hydroxyapatite(HAP) so that it could be crystallized on the surface of 'phosphorus removal granular material'; and residual particulate phosphorus could be removed by additional precipitation and filtration. The front and rear parts of filtration trench consisted of 'phosphorus removal granular material contact bed' and 'limestone filtration bed', respectively. As a result of the column test using phosphorus removal granular material and limestone serially, $PO_4-P$ was removed more than 90% when EBCT(empty bed contact time) of the contact bed was over 20 minutes; and T-P represented 60% of removal efficiency when total EBCT was over 1.5 hours. The results of column tests to figure out the sedimentation characteristics showed that more than 90% of particulate phosphorus could be removed within 24 hours. It was necessary to optimize the filtration part in order to increase removal efficiency of T-P additionally. Also, it was confirmed through the simulation of Visual MINTEQ that most of particulate phosphorus in the column tests is the form of HAP. Based on the results of the study, it could be suggested that the design parameters are over 0.5 hour of EBCT for phosphorus removal granular material contact bed and over 1.5 hours of EBCT for limestone filtration bed.

A Study on the determination of the optimal resolution for the application of the distributed rainfall-runoff model to the flood forecasting system - focused on Geumho river basin using GRM (분포형 유역유출모형의 홍수예보시스템 적용을 위한 최적해상도 결정에 관한 연구 - GRM 모형을 활용하여 금호강 유역을 중심으로)

  • Kim, Sooyoung;Yoon, Kwang Seok
    • Journal of Korea Water Resources Association
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    • v.52 no.2
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    • pp.107-113
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    • 2019
  • The flood forecasting model currently used in Korea calculates the runoff of basin using the lumped rainfall-runoff model and estimates the river level using the river and reservoir routing models. The lumped model assumes homogeneous drainage zones in the basin. Therefore, it can not consider various spatial characteristics in the basin. In addition, the rainfall data used in lumped model also has the same limitation because of using the point scale rainfall data. To overcome the limitations as mentioned above, many researchers have studied to apply the distributed rainfall-runoff model to flood forecasting system. In this study, to apply the Grid-based Rainfall-Runoff Model (GRM) to the Korean flood forecasting system, the optimal resolution is determined by analyzing the difference of the results of the runoff according to the various resolutions. If the grid size is to small, the computation time becomes excessive and it is not suitable for applying to the flood forecasting model. Even if the grid size is too large, it does not fit the purpose of analyzing the spatial distribution by applying the distributed model. As a result of this study, the optimal resolution which satisfies the accuracy of the bsin runoff prediction and the calculation speed suitable for the flood forecasting was proposed. The accuracy of the runoff prediction was analyzed by comparing the Nash-Sutcliffe model efficiency coefficient (NSE). The optimal resolution estimated from this study will be used as basic data for applying the distributed rainfall-runoff model to the flood forecasting system.

Study on Determination of Design Factor of Bioreactor for Sulfate Reduction in Mine Drainage (광산배수 내 황산염 저감을 위한 생물반응기의 설계인자 도출 연구)

  • Kim, Kang-Ho;Kang, Chan-Ung;Kim, Sun-Joon;Kim, Tae-Heok;Ji, Won-Hyun;Jang, Hang-Seok;Park, Hyun-Sung
    • Journal of the Korean Society of Mineral and Energy Resources Engineers
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    • v.55 no.6
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    • pp.527-537
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    • 2018
  • Column tests of a sulfate reducing bacteria (SRB) bioreactor were conducted to determine the design factors for sulfate-rich mine drainage. Various substrates were applied to the bioreactor, including cow manure and its mixture with a mushroom compost, with rice straw and limestone as subsidiary materials. This procedure provided a removal efficiency of up to 82% of the total sulfur with the mixture of cow manure (70%), mushroom compost (10%) and rice straw (20%), and higher efficiencies were observed after 2 days of retention time. In the downflow condition of the flow direction, oxygen supply and re-oxidation of the sulfates occurred, causing a decrease in sulfate removal efficiency. The addition of an inorganic sludge containing heavy metals, which was intended for production of metal-sulfides in the bioreactor, had a negative effect on the long-term operation owing to arsenic release and toxicity to the SRB. The results thus show that a bioreactor using a mixed substrate with cow manure and operating in the downflow direction could reduce sulfates and total dissolved sulfur content; this process confirms the applicability of the SRB bioreactor to sulfate-rich saline drainage.

Determination the optimum extraction method for saponin lancemasides in Codonopsis lanceolata (더덕 사포닌인 lancemasides의 최적 추출 방법 구명)

  • Lee, Min Ju;Nam, Ju Hee;Um, In Eeok;Kang, Chang Keun;Rho, Il Rae
    • Korean Journal of Food Science and Technology
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    • v.51 no.2
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    • pp.103-108
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    • 2019
  • This study was conducted to select the optimal extraction method of codonopsis lanceolata saponin. To investigate the lancemasides content depending on each extraction method, various extractions were performed: reflux (methanol and butanol), hot water, as well as ultrasonic bath (40 kHz; continuous irradiation/interval irradiation) and ultrasonicator (20 kHz) extractions. From the result, the overall lancemasides content were the highest in ultrasonic bath (MeOH; continuous irradiation) extraction, followed by ultrasonic bath (water; continuous irradiation)>ultrasonic bath (MeOH; interval irradiation)>ultrasonicator (MeOH)>hot water>MeOH reflux>BuOH reflux extractions in that order. Sample drying method prior to ultrasonic bath extraction was more effective shade drying than freeze drying. Effective duration and temperature of extraction was 2 hr at $64^{\circ}C$. And ingredient change diverted from aster saponin Hb to lancemasides was identified by extraction condition such as extraction time and temperature.

Agent-based Modeling and Analysis of Tactical Reconnaissance Behavior with Manned and Unmanned Vehicles (에이전트 기반 유·무인 수색정찰 전술행위 모델링 및 분석)

  • Kim, Ju Youn;Han, Sang Woo;Pyun, Jai Jeong
    • Journal of the Korea Society for Simulation
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    • v.27 no.4
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    • pp.47-60
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    • 2018
  • Today's unmanned technology, which is being used in various industries, is expected to be able to make autonomous judgements as autonomous technology matures, in the long run aspects. In order to improve the usability of unmanned system in the military field, it is necessary to develop a technique for systematically and quantitatively analyzing the efficiency and effectiveness of the unmanned system by means of a substitute for the tasks performed by humans. In this paper, we propose the method of representing rule-based tactical behavior and modeling manned and unmanned reconnaissance agents that can effectively analyze the path alternatives which is required for the future armored cavalry to establish a reconnaissance mission plan. First, we model the unmanned ground vehicle, small tactical vehicle, and combatant as an agent concept. Next, we implement the proposed agent behavior rules, e.g., maneuver, detection, route determination, and combatant's dismount point selection, by NetLogo. Considering the conditions of maneuver, enemy threat elements, reconnaissance assets, appropriate routes are automatically selected on the operation area. It is expected that it will be useful in analyzing unmanned ground system effects by calculating reconnaissance conducted area, time, and combat contribution ratio on the route.

Predictive Modeling for the Growth of Salmonella Enterica Serovar Typhimurium on Lettuce Washed with Combined Chlorine and Ultrasound During Storage

  • Park, Shin Young;Zhang, Cheng Yi;Ha, Sang-Do
    • Journal of Food Hygiene and Safety
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    • v.34 no.4
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    • pp.374-379
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    • 2019
  • This study developed predictive growth models of Salmonella enterica Serovar Typhimurium on lettuce washed with chlorine (100~300 ppm) and ultrasound (US, 37 kHz, 380 W) treatment and stored at different temperatures ($10{\sim}25^{\circ}C$) using a polynomial equation. The primary model of specific growth rate (SGR) and lag time (LT) showed a good fit ($R^2{\geq}0.92$) with a Gompertz equation. A secondary model was obtained using a quadratic polynomial equation. The appropriateness of the secondary SGR and LT model was verified by coefficient of determination ($R^2=0.98{\sim}0.99$ for internal validation, 0.97~0.98 for external validation), mean square error (MSE=-0.0071~0.0057 for internal validation, -0.0118~0.0176 for external validation), bias factor ($B_f=0.9918{\sim}1.0066$ for internal validation, 0.9865~1.0205 for external validation), and accuracy factor ($A_f=0.9935{\sim}1.0082$ for internal validation, 0.9799~1.0137 for external validation). The newly developed models for S. Typhimurium could be incorporated into a tertiary modeling program to predict the growth of S. Typhimurium as a function of combined chlorine and US during the storage. These new models may also be useful to predict potential S. Typhimurium growth on lettuce, which is important for food safety purposes during the overall supply chain of lettuce from farm to table. Finally, the models may offer reliable and useful information of growth kinetics for the quantification microbial risk assessment of S. Typhimurium on washed lettuce.

A Study on the Composition of HonJeon(魂殿) space (조선시대 혼전(魂殿)공간의 구성에 관한 연구)

  • Hong, Eun Ki;Kim, Sang Tae;Chang, Hun Duck
    • Korean Journal of Heritage: History & Science
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    • v.45 no.4
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    • pp.74-91
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    • 2012
  • This study puts its focus on Honjeon space which relatively small number of precedent studies chose as a subject of a study. The objective is to analyze Honjeon space's spatial relationship and palaces that consist Honjeon through analysis of spatial configuration and elements that affected construction of Honjeon space. The Royal Funeral, among other ceremonies of Joseon Dysnasty, carries religious characteristic along with functional and structural characteristics. By analyzing "National Five Rites", "Uigwe for the State Funeral 魂殿都監儀軌", and "Annals of Joseon Dynasty", the study organized elementary details about Honjeon space and surrounding spaces to determine the symbolism of Honjeon space's location at each palace and compared them to see if any systematical features existed between Honjeon spaces of each palace. Through this study, it was apparent the king mainly used Jaseongdang Hall of Gyeongbokgung in the early period of Joseon Dynasty and he mainly used Sunjeongjun of Changdeokgung while the queen used Munjeongjun of Changgyeonggung as the time reached the later period of Joseon Dynasty. Also in determination of Honjeon space, the study found that there were records of avoiding Pyeonjeon space in need for political space. The study also determined that places other than Pyeonjeon space was intended to be used for Honjeon space through the analysis which indicates that spaces that were initially used as Pyeonjun in the early Joseon Dynasty and simultaneously as Honjeon space were moved due to changes made in terms of theirs usages. Through the study, it could be also known that primary spaces of Honjeon was composed accordingly to "National Five Rites" and constant pattern of spaces existed among buildings near Honjeon which were arranged according to each palace's characteristic.

Determination of β-Carotene in Infant Formulas by High-Performance Liquid Chromatography (HPLC를 이용한 조제유류 중 베타카로틴 함량 분석 연구)

  • Hwang, Kyung Mi;Bae, Ji Won;Hu, Soo Jung;Oh, Keum Soon
    • Journal of Food Hygiene and Safety
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    • v.34 no.4
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    • pp.334-339
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    • 2019
  • A procedure based on high-performance liquid chromatography (HPLC) is described to determine ${\beta}-carotene$ in infant formulas. The method for ${\beta}-carotene$ analysis was performed on a C18 reversed-phase column using acetonitrile/methanol/dichloromethane (6:1:3, v/v/v) as a mobile phase. ${\beta}-Carotene$ was determined in HPLC with photo diode array (PDA) detector. The parameters of validation were specificity, linearity, LOD, LOQ, accuracy, precision and repeatability. The specificity was confirmed by the retention time and the linearity ($R^2$), which was over 0.999 in the range of 0.125~2 mg/L. The detection and quantification limits were 0.064 and 0.193 mg/L, respectively. The accuracy and precision of this method using an STD spiked sample were 80~119% and 1.02~2.05% respectively. The method was applied to the analysis of various infant formula and follow-up formulas products containing ${\beta}-carotene$, and all the products contained acceptable levels of ${\beta}-carotene$ for nutrition labeling.