• Title/Summary/Keyword: loss calculation

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Radiation Effects on the Ignition and Flame Extinction of High-temperature Fuel (고온연료의 점화 및 화염 소화특성에 미치는 복사효과)

  • Kim, Yu Jeong;Oh, Chang Bo;Choi, Byung Il;Han, Yong Shik
    • Fire Science and Engineering
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    • v.27 no.6
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    • pp.50-56
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    • 2013
  • The radiation effects on the auto-ignition and extinction characteristics of a non-premixed fuel-air counterflow field were numerically investigated. A detailed reaction mechanism of GRI-v3.0 was used for the calculation of chemical reactions and the optically-thin radiation model was adopted in the simulations. The flame-controlling continuation method was also used in the simulation to predict the auto-ignition point and extinction limits precisely. As a result, it was found that the maximum H radical concentration, $(Y_H)_{max}$, rather than the maximum temperature was suitable to understand the ignition and extinction behaviors. S-, C- and O-curves, which were well known from the previous theory, were identified by investigating the $(Y_H)_{max}$. The radiative heat loss fraction ($f_r$) and spatially-integrated heat release rate (IHRR) were introduced to grasp each extinction mechanism. It was also found that the $f_r$ was the highest at the radiative extinction limit. At the flame stretch extinction limit, the flame was extinguished due to the conductive heat loss which attributed to the high strain rate although the heat release rate was the highest. The radiation affected on the radiative extinction limit and auto-ignition point considerably, however the effect on the flame stretch extinction limit was negligible. A stable flame regime defined by the region between each extinction limit became wide with increasing the fuel temperature.

Comparison Of CATHARE2 And RELAP5/MOD3 Predictions On The BETHSY 6.2% TC Small-Break Loss-Of-Coolant Experiment (CATHARE2와 RELAP5/MOD3를 이용한 BETHSY 6.2 TC 소형 냉각재상실사고 실험결과의 해석)

  • Chung, Young-Jong;Jeong, Jae-Jun;Chang, Won-Pyo;Kim, Dong-Su
    • Nuclear Engineering and Technology
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    • v.26 no.1
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    • pp.126-139
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    • 1994
  • Best-estimate thermal-hydraulic codes, CATHARE2 V1.2 and RELAP5/MOD3, hate been assessed against the BETHSY 6.2 tc six-inch cold leg break loss-of-coolant accident (LOCA) test. Main objective is to analyze the overall capabilities of the two codes on physical phenomena of concern during the small break LOCA i.e. two-phase critical flow, depressurization, core water level de-pression, loop seal clearing, liquid holdup, etc. The calculation results show that the too codes predict well both in the occurrences and trends of major two-phase flow phenomena observed. Especially, the CATHARE2 calculations show better agreements with the experimental data. However, the two codes, in common, show some deviations in the predictions of loop seal clearing, collapsed core water level after the loop seal clearing, and accumulator injection behaviors. The discrepancies found from the comprision with the experimental data are larger in the RELAP5 results than in the CATHARE2. To analyze the deviations of the two code predictions in detail, several sensitivity calculations have been performed. In addition to the change of two-phase discharge coefficients for the break junction, fine nodalization and some corrections of the interphase drag term are made. For CATHARE2, the change of interphase drag force improves the mass distribution in the primary side. And the prediction of SG pressure is improved by the modification of boundary conditions. For RELAP5, any single input change doesn't improve the whole result and it is found that the interphase drag model has still large uncertainties.

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New composite distributions for insurance claim sizes (보험 청구액에 대한 새로운 복합분포)

  • Jung, Daehyeon;Lee, Jiyeon
    • The Korean Journal of Applied Statistics
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    • v.30 no.3
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    • pp.363-376
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    • 2017
  • The insurance market is saturated and its growth engine is exhausted; consequently, the insurance industry is now in a low growth period with insurance companies that face a fierce competitive environment. In such a situation, it will be an important issue to find the probability distributions that can explain the flow of insurance claims, which are the basis of the actuarial calculation of the insurance product. Insurance claims are generally known to be well fitted by lognormal distributions or Pareto distributions biased to the left with a thick tail. In recent years, skew normal distributions or skew t distributions have been considered reasonable distributions for describing insurance claims. Cooray and Ananda (2005) proposed a composite lognormal-Pareto distribution that has the advantages of both lognormal and Pareto distributions and they also showed the composite distribution has a higher fitness than single distributions. In this paper, we introduce new composite distributions based on skew normal distributions or skew t distributions and apply them to Danish fire insurance claim data and US indemnity loss data to compare their performance with the other composite distributions and single distributions.

Comparing Calculation Techniques for Effective Rainfalls Using NRCS-CN Method: Focused on Introducing Weighted Average and Slope-based CN (NRCS-CN 방법을 이용한 유효우량 산정기법의 비교분석: 가중평균방법과 경사도 도입을 중심으로)

  • Moon, Geon-Woo;Yoo, Ji-Young;Kim, Tae-Woong
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.34 no.4
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    • pp.1171-1180
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    • 2014
  • The NRCS-CN method is generally used to estimate effective rainfalls in a basin. However, since the curve number which plays a critical role in the NRCS-CN method was originally developed for US watersheds, it is limited to be directly applied to other basins outside the United States. Therefore various modifications have been suggested to revise the NRCS-CN for specific watershed condition. This study introduced the weighted average method and the slope-based CN to estimate effective rainfalls available for Korean watersheds and compared with the observed direct runoff. The overall results achieved from this study indicated that the adjusted slope-based CN considerably increases effective rainfalls in general and makes the duration of effective storm longer. Based on the statistical error analysis performed for various modifications of NRCS-CN, the weighted average method with the adjusted slope-based CN has highest precision with the observed direct runoff. In addition, after analyzing the relation between the initial loss estimated from rainfall-runoff observations and the potential maximum retention from GIS-based data, it turns out that the assumption of linear relationship between the initial loss and the potential maximum retention is not available for Korean watersheds.

Analyzing The Economic Impact of The Fire Risk Reduction at Regional Level in Goyang City (지역단위 화재 위험도 저감의 고양시 경제적 파급효과 분석)

  • Son, Minsu;Cho, Dongin;Park, Chang Keun;Ko, Hyun A;Jung, Seunghyun
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.22 no.2
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    • pp.685-693
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    • 2021
  • This study examined the fire risk of the region in Goyang City using the spatial information data of buildings. The economic damage by industry was assessed according to the probability of fire risk. The study area was confined to Goyang-si, Gyeonggi-do, and the same fire risk reduction rate was applied to each region for the convenience of analysis. The possibility of fire was derived based on the buildings' density and usage in the area by National GIS building-integrated information standard data. The calculation of economic damage by industry in Goyang City due to the fire risk was calculated by combining the Goyang-si industry-related model produced by matching with 30 industrial categories in Input-Output Statistics of Korea Bank and 20 industrial categories in the Goyang-si business survey and the possibility of fire. The basic scenario of production impossibility during six months and business loss due to fire was established and analyzed based on the supply model. The analysis showed that Ilsan-dong-gu, Ilsan-seo-gu, and Deokyang-gu suffered the most economic damage. The "electricity, gas, steam, and water business" showed the greatest loss by industry.

WQI Class Prediction of Sihwa Lake Using Machine Learning-Based Models (기계학습 기반 모델을 활용한 시화호의 수질평가지수 등급 예측)

  • KIM, SOO BIN;LEE, JAE SEONG;KIM, KYUNG TAE
    • The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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    • v.27 no.2
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    • pp.71-86
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    • 2022
  • The water quality index (WQI) has been widely used to evaluate marine water quality. The WQI in Korea is categorized into five classes by marine environmental standards. But, the WQI calculation on huge datasets is a very complex and time-consuming process. In this regard, the current study proposed machine learning (ML) based models to predict WQI class by using water quality datasets. Sihwa Lake, one of specially-managed coastal zone, was selected as a modeling site. In this study, adaptive boosting (AdaBoost) and tree-based pipeline optimization (TPOT) algorithms were used to train models and each model performance was evaluated by metrics (accuracy, precision, F1, and Log loss) on classification. Before training, the feature importance and sensitivity analysis were conducted to find out the best input combination for each algorithm. The results proved that the bottom dissolved oxygen (DOBot) was the most important variable affecting model performance. Conversely, surface dissolved inorganic nitrogen (DINSur) and dissolved inorganic phosphorus (DIPSur) had weaker effects on the prediction of WQI class. In addition, the performance varied over features including stations, seasons, and WQI classes by comparing spatio-temporal and class sensitivities of each best model. In conclusion, the modeling results showed that the TPOT algorithm has better performance rather than the AdaBoost algorithm without considering feature selection. Moreover, the WQI class for unknown water quality datasets could be surely predicted using the TPOT model trained with satisfactory training datasets.

Factors Influencing Acceptance Resistance of Personal Health Record Apps: Focusing on the Privacy Calculus Model (개인건강기록 앱 수용저항에 영향을 미치는 요인: 프라이버시 계산모형을 중심으로)

  • Sang Ho Kim;Eunkyung Kang;Sung-Byung Yang
    • Information Systems Review
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    • v.25 no.1
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    • pp.165-187
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    • 2023
  • The continuous increase in life expectancy and high interest in health has brought about significant changes in the use of health information by the public according to the development of information technology represented by the Internet and smartphones. As the medical market expands to the mobile health environment, many health-related apps have been created and distributed, but the acceptance rate is slow as it has become challenging to provide services due to various regulations. In this study, perceived value, perceived risk factors (psychological risk, risk of time-loss, legal risk), and perceived benefits (usefulness, interaction, autonomy) were derived and verified as factors that affect the acceptance resistance of personal health record apps based on the privacy calculation model. In addition, by analyzing the moderating effect of trust in the manufacturer, how the perceived risk and perceived benefit affect the perceived value was verified. A survey was conducted on Korean college students who recognized the personal health record apps but did not use them, and 127 samples were analyzed using structural equations. As a result of hypothesis verification, perceived value has a negative effect on acceptance resistance, perceived risk (risk of time-loss) has a negative effect on perceived value, and perceived benefits (usefulness, interaction, autonomy) were found to have a positive effect on perceived value. Trust in manufacturers has weakened the impact of perceived risks (legal risk) on perceived values. This study is expected to play an important role in maintaining a competitive advantage in the personal health record app market environment by identifying and proposing detailed criteria for reducing the acceptance resistance of personal health record apps.

AN EXPERIMENTAL STUDY WITH SNUF AND VALIDATION OF THE MARS CODE FOR A DVI LINE BREAK LOCA IN THE APR1400

  • Lee, Keo-Hyoung;Bae, Byoung-Uhn;Kim, Yong-Soo;Yun, Byong-Jo;Chun, Ji-Han;Park, Goon-Cherl
    • Nuclear Engineering and Technology
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    • v.41 no.5
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    • pp.691-708
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    • 2009
  • In order to analyze thermal hydraulic phenomena during a DVI (Direct Vessel Injection) line break LOCA (Loss-of-Coolant Accident) in the APR1400 (Advanced Power Reactor 1400 MWe), we performed experimental studies with the SNUF (Seoul National University Facility), a reduced-height and reduce-pressure integral test loop with a scaled down APR1400. We performed experiments dealing with eight test cases under varied tests. As a result of the experiment, the primary system pressure, the coolant temperature, and the occurrence time of the downcomer seal clearing were affected significantly by the thermal power in the core and the SI flow rate. The break area played a dominant role in the vent of the steam. For our analytical investigation, we used the MARS code for simulation of the experiments to validate the calculation capability of the code. The results of the analysis showed good and sufficient agreement with the results of the experiment. However, the analysis revealed a weak capability in predicting the bypass flow of the SI water toward the broken DVI line, and it was insufficient to simulate the streamline contraction in the broken side. We, hence, need to improve the MARS code.

The Trend of Precedents about Calculation of Damage Compensation for Last Decade (손해배상액 산정에 관한 최근 10년간 판례의 동향 하(下))

  • Park, Young-Ho
    • The Korean Society of Law and Medicine
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    • v.11 no.1
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    • pp.397-445
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    • 2010
  • This thesis introduces the trends of korean courts' ruling on damages in medical malpractice cases for past 10 years. First of all, Korean courts' ruling have had a tendency to pay only non-economic damages for not taking the informed consent. If a doctor cannot get the informed consent from a patient, he compensate only non-economic damages for the infringement of self-determination rights of patient. It's enough for the plaintiff to prove the infringement of self-determination rights, if the plaintiff just want to get non-economic damages. The Korean Supreme court have ruled that if plaintiffs want to get economic damages for the infringement of self-determination rights or informed consent, plaintiffs must prove that the infringement of self-determination rights is the proximate cause of the economic damages of patient. There is another tendency for the Korean Supreme court to limit the damages in medical malpractice cases on the ground of patient's diseases' dangerousness or patient's idiosyncrasy. In the past courts often limit the damages only to 70~80% of total damages, but now a days courts mostly limit the damages to 20~30%. This thesis also introduce the Korean courts' trends about Valuing damages in personal injury actions awarded for gratuitously rendered nursing and medical care.

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Wave Absorbing Characteristics of a Horizontal Submerged Punching Plate (수평형 타공판의 소파특성)

  • 조일형
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.14 no.4
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    • pp.265-273
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    • 2002
  • In this paper, wave absorbing characteristics of a horizontal submerged punching plate are investigated throughout the calculation and the experiment. The punching plate with the array of circular holes can force the flow to separate and to form eddies of high vorticity and cause significant energy loss. As an analytic tool, the linear water wave theory and the eigenfunction expansion method is applied. Darcy's law that the normal velocity of the fluid passing through the punching plate is linearly proportional to the pressure difference between two sides of the punching plate is assumed. The proportional constant called the porous coefficient is deeply dependent to the porosity. To obtain the relationship between the porosity and the porous coefficient the systematic model test for the punching plates with 6 different porosities is conducted at 2-dimensional wave tank. It is found that the porous coefficient is linearly proportional to the porosity(b=57.63P-0.9717). It is also noted that the optimal porosity value is near P=0.1 and the optimal range of submergence depth is $d/h\\leq0.2$ within entire frequency range.