• Title/Summary/Keyword: Material uncertainties

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Topology Optimization of Structures using Interval Finite Element Method (간격 유한요소해석을 이용한 구조물의 위상 최적화)

  • Lee, Dong-Kyu;Shin, Soo-Mi;Park, Sung-Soo
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.19 no.4 s.74
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    • pp.389-398
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    • 2006
  • Structural optimization design has been developed with finite element analysis using effective and fast computational technology. Especially topology optimization design has been recently often used since it yields an optimal topology as well as an optimal shape under satisfied constraints. In general in finite element analysis, it is assumed that the structural material properties such as Young's modulus and Poisson's ratio and the variable of applied loading are fixed with obvious values in structure. However practically these values may take uncertainties because of environmental effect or manufactural error of structures. Therefore static or dynamic analysis of the structures may make an error, then finally it may have an influence on qualify of optimal design. In this study, the topology optimization design of structure is carried out using so called the interval finite element method, and the analysis method Is proposed. The results are also validated by comparing with conventional topology optimization results of density distribution method and finite element analysis results. The present method can be used to predict the optimal topology of linear elastostatic structures with respect to structural uncertainty of behavior.

The Analysis of the Effects of the Previous Corporate Internal Reservation on the Current Investments and Dividends : The Verification of Significance through Dummy Variables under Industrial Classification (법인의 전기 유보금이 당기 투자 및 배당에 미치는 효과 분석 : 업종별 더미변수를 통한 유의성 검증)

  • Yoo, Joon-soo
    • Journal of Venture Innovation
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    • v.2 no.1
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    • pp.131-151
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    • 2019
  • This paper is conducted to find out if the previous corporate internal reservation has a significant effect on current investment and dividend payments by using the dummy variables of each classified industry. The results of the research show that previous corporate internal reservation had a significant effect on current material investments in following fields - manufacturing industries, technical services, wholesale and retail industries, information services, construction and transportation industries - over two years. Especially, investments in tangible assets were more effective than those in development expenses. In human resource investment, previous corporate internal reservation had a significant effect on current human investments in fields of manufacturing, technical services, information services and transportation industries. Among them, investments in education training expense and welfare benefit expense were more effective than those in wages. In the dividend section, previous corporate internal reservation had a significant effect on current dividends in the fields of manufacturing, wholesale and retail, information services, transportation industries, and in other businesses. Among them, Expenditure on dividend amounts was found to be more effective than that on dividend ratio. This paper contributed to the field in a way of empirically demonstrating the effects of previous corporate internal reservation on current investments and dividends by using the method of industrial classification. On the other hand, it also has a limitation since collecting precise taxation data was practically difficult. Therefore, a further developed study is required to find out the standard which shows exactly how much the measured results of the regression analysis reflect the effects of the government policies. Moreover, it is considered necessary for the government to devise policies on vagueness and uncertainties in the domestic and overseas economic and business environments so that companies can conduct investment with confidence.

TET2MCNP: A Conversion Program to Implement Tetrahedral-mesh Models in MCNP

  • Han, Min Cheol;Yeom, Yeon Soo;Nguyen, Thang Tat;Choi, Chansoo;Lee, Hyun Su;Kim, Chan Hyeong
    • Journal of Radiation Protection and Research
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    • v.41 no.4
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    • pp.389-394
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    • 2016
  • Background: Tetrahedral-mesh geometries can be used in the MCNP code, but the MCNP code accepts only the geometry in the Abaqus input file format; hence, the existing tetrahedral-mesh models first need to be converted to the Abacus input file format to be used in the MCNP code. In the present study, we developed a simple but useful computer program, TET2MCNP, for converting TetGen-generated tetrahedral-mesh models to the Abacus input file format. Materials and Methods: TET2MCNP is written in C++ and contains two components: one for converting a TetGen output file to the Abacus input file and the other for the reverse conversion process. The TET2MCP program also produces an MCNP input file. Further, the program provides some MCNP-specific functions: the maximum number of elements (i.e., tetrahedrons) per part can be limited, and the material density of each element can be transferred to the MCNP input file. Results and Discussion: To test the developed program, two tetrahedral-mesh models were generated using TetGen and converted to the Abaqus input file format using TET2MCNP. Subsequently, the converted files were used in the MCNP code to calculate the object- and organ-averaged absorbed dose in the sphere and phantom, respectively. The results show that the converted models provide, within statistical uncertainties, identical dose values to those obtained using the PHITS code, which uses the original tetrahedral-mesh models produced by the TetGen program. The results show that the developed program can successfully convert TetGen tetrahedral-mesh models to Abacus input files. Conclusion: In the present study, we have developed a computer program, TET2MCNP, which can be used to convert TetGen-generated tetrahedral-mesh models to the Abaqus input file format for use in the MCNP code. We believe this program will be used by many MCNP users for implementing complex tetrahedral-mesh models, including computational human phantoms, in the MCNP code.

Assessment of the Internal Pressure Fragility of the PWR Containment Building Using a Nonlinear Finite Element Analysis (비선형 유한요소 해석을 이용한 PWR 격납건물의 내압 취약도 평가)

  • Hahm, Daegi;Park, Hyung-Kui;Choi, In-Kil
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.27 no.2
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    • pp.103-111
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    • 2014
  • In this study, the probabilistic internal pressure fragility analysis was performed by using the non-linear finite element analysis method. The target structure is one of the containment buildings of typical domestic pressurized water reactors(PWRs). The 3-dimensional finite element model of the containment building was developed with considering the large equipment hatches. To consider uncertainties in the material properties and structural capacities, we performed the sensitivity analysis of the ultimate pressure capacity with respect to the variation of four important uncertain parameters. The results of the sensitivity analysis were used to the selection of the probabilistic variables and the determination of their probabilistic parameters. To reflect the present condition of the tendon pre-stressing force, the data of the pre-stressing force acquired from the in-service inspections of tendon forces were used for the determination of the median value. Two failure modes(leak, rupture) were considered and their limit states were defined to assess the internal pressure fragility of target containment building. The internal pressure fragilities for each failure mode were evaluated in terms of median internal pressure capacity, high confidence low probability of failure(HCLPF) capacity, and fragility curves with respect to the confidence levels. The HCLPF capacity was 115.9 psig for leak failure mode, and 125.0 psig for rupture failure mode.

Impacts for Waste Management According to Waste Trade (폐기물 수출입 흐름 변화가 폐기물 관리에 미치는 영향)

  • Lee, Sang-hun
    • Resources Recycling
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    • v.29 no.3
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    • pp.43-50
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    • 2020
  • This study reviewed the examples on analyses of the potential impacts to waste management, due to the recent trends of waste trade regulation, and summarized an analysis strategy of the impacts. As a result, a desirable analysis may begin with reasonable estimation of recent waste amounts and flows, and reasonable prediction of the future trends of waste amounts. Then, it is effective to list various key factors and derive future scenarios of the impacts, as well as employ the traditional viewpoints focusing on waste material flow or environmental regulations. The applicable analyses for each scenario can be largely divided into qualitative and quantitative methods. Due to a high uncertainty in the recent international situations with entailing possible innovative economic changes, qualitative methods may be considered in advance, and then quantitative techniques may be utilized to predict gradual changes at relieved uncertainty of the situations. Based on this review so far, proper methodology and procedures for the impact analysis were suggested on recent waste trade conditions in Korea. Given existence of the recent uncertainties such as the health and economic crises, the analysis preferably focused on deriving strategic scenarios with respect to various aspects, and suggested analysis methods applicable to each scenario.

The evaluation of image guide system in case of rectal cancer (직장암 치료시 영상유도 시스템의 유용성 평가)

  • Jang, Sewuk;Ahn, Seungkwon;Lee, Sangkyoo;Kim, Jooho;Lee, Wonju;Cho, Jeonghee
    • The Journal of Korean Society for Radiation Therapy
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    • v.29 no.1
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    • pp.85-92
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    • 2017
  • purpose: Image Guide System offers therapy precise, especially Intensity Modulated Radiation Therapy. However, organs at pelvis have variation and uncertainties each therapy. it brings IG system for verifying patient's position. In this study, analysis the variation at pelvis during rectal cancer radiation therapy. Moreover design the patient re-setup technique and apply to patients. Material and Method: 40 rectal cancer patient who have radiation therapy. The 530 image which acquired from IG system are analyzed. The bone structure, bladder, gas in the rectum, small bowel, soft tissue, weigh loss are evaluated by the criterion. The criterion are classified by best, good, bad and figure out the ratio with count. The re-setup proceed in case of one or over the two get the bad criterion and figure out the ratio of re-setup results: The ideal of therapy ratio is 19.2 % each criterion. And the good for therapy ratio is 54.9 %, the cases of bad for therapy is 25.8 %. The bad cases are have therapy after re-setup with post process. conclusion: Each pre-treatment image that acquired IG system has different results despite of same patients. The 25.8 % need to re-setup in order to unsuitable therapy. It is implies that the IG system is necessary establishing precise treatment plan like IMRT especially rectal cancer.

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An analysis of benzoic acid, methyl paraben and butyl paraben in soy sauce using isotope dilution liquid chromatography mass spectrometry (동위원소희석 질량분석법을 이용한 간장 중의 안식향산, 메틸파라벤, 부틸파라벤의 분석)

  • Ahn, Seonghee
    • Analytical Science and Technology
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    • v.31 no.6
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    • pp.225-231
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    • 2018
  • Benzoic acid, methyl paraben, and butyl paraben are preservatives that have been used in pharmaceutical, cosmetic, and food products. However, as their toxicities for human have been reported, many nations and organizations including Korea have established a regulation limit for thier usage of these preservatives in food products. The present study developed the isotope dilution liquid chromatography mass spectrometry method for accurate determination of three target preseratives in soysauce. In this study, the isotope dilution liquid chromatography mass spectrometry method was developed for accurate determination of three target preservatives in soy sauce. LC separation was optimized considering the pKa of benzoic acid which is lower than those of methyl and butyl parabens. A C18 column was used with 5 mM ammonium acetate and methanol as mobile phases. Mass spectrometry was operated in negative mode and selected reaction monitoring mode (SRM). Soy sauce sample was cleaned-up with C18 SPE cartridge for removing matrix inferences and color material. Optimized conditions and the method were validated with soy sauce reference materials for the analysis of food preservatives from Health Science Authority in Singapore. The measured values of benzoic acid, methyl and butyl paraben agreed well with reference values within their uncertainties.

Guidelines for dental clinic infection prevention during COVID-19 pandemic (코로나 바이러스 대유행에 따른 치과 의료 관리 가이드라인)

  • Kim, Jin
    • Journal of Korean Academy of Dental Administration
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    • v.8 no.1
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    • pp.1-7
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    • 2020
  • Dental settings have unique characteristics that warrant specific infection control considerations, including (1) prioritizing the most critical dental services and provide care in a way that minimizes harm to patients due to delayed care, or harm to personnel from potential exposure to persons infected with the COVID-19 disease, and (2) proactively communicate to both personnel and patients the need for them to stay at home if sick. For health care, an interim infection prevention and control recommendation (COVID-19) is recommended for patients suspected of having coronavirus or those whose status has been confirmed. SARS-CoV-2, which is the virus that causes COVID-19, is thought to be spread primarily between people who are in close contact with one another (within 6 feet) through respiratory droplets that are produced when an infected person coughs, sneezes, or talks. Airborne transmission from person-to-person over long distances is unlikely. However, COVID-19 is a new disease, and there remain uncertainties about its mode of spreads and the severity of illness it causes. The virus has been shown to persist in aerosols for several hours, and on some surfaces for days under laboratory conditions. COVID-19 may also be spread by people who are asymptomatic. The practice of dentistry involves the use of rotary dental and surgical instruments, such as handpieces or ultrasonic scalers, and air-water syringes. These instruments create a visible spray that can contain particle droplets of water, saliva, blood, microorganisms, and other debris. While KF 94 masks protect the mucous membranes of the mouth and nose from droplet spatter, they do not provide complete protection against the inhalation of airborne infectious agents. If the patient is afebrile (temperature <100.4°F)* and otherwise without symptoms consistent with COVID-19, then dental care may be provided using appropriate engineering and administrative controls, work practices, and infection control considerations. It is necessary to provide supplies for respiratory hygiene and cough etiquette, including alcohol-based hand rub (ABHR) with 60%~95% alcohol, tissues, and no-touch receptacles for disposal, at healthcare facility entrances, waiting rooms, and patient check-ins. There is also the need to install physical barriers (e.g., glass or plastic windows) in reception areas to limit close contact between triage personnel and potentially infectious patients. Ideally, dental treatment should be provided in individual rooms whenever possible, with a spacing of at least 6 feet between the patient chairs. Further, the use of easy-to-clean floor-to-ceiling barriers will enhance the effectiveness of portable HEPA air filtration systems. Before and after all patient contact, contact with potentially infectious material, and before putting on and after removing personal protective equipment, including gloves, hand hygiene after removal is particularly important to remove any pathogens that may have been transferred to the bare hands during the removal process. ABHR with 60~95% alcohol is to be used, or hands should be washed with soap and water for at least 20 s.

Determination of trace arsenic in seawater by flow injection-hydride generation inductively coupled plasma mass spectrometry (연속흐름주입-수소화물생성-유도결합플라스마 질량분석장치를 이용한 바닷물표준시료중의 극미량 비소분석방법의 확립)

  • Suh, Jung-Ki
    • Analytical Science and Technology
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    • v.21 no.4
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    • pp.316-325
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    • 2008
  • An inductively coupled plasma mass spectrometry (ICP-MS) instrument equipped with flow injection-hydride generation system was used for the determination of trace arsenic in seawater sample. The accuracy in this method was verified by the analysis of certified reference materials (CRM) of seawater (CASS-4, NASS-5). The analytical results agreed with certified value within the range of uncertainty. The expanded uncertainties for CASS-4 and NASS-5 in this experiment were ranged from 6.2% to 6.8% obtained from repeated analyses of the CRMs (n=5). The detection limit of $As^+$ (m/z=74.9216) in this method was confirmed about 0.01 ug/kg. Linearity obtained from calibration curve of arsenic was excellent ($R^2=1$). The detection at $As^+$ (m/z=74.9216) and $AsO^+$ (m/z=90.9165) by using oxygen reaction gas in DRC mode was compared. Sensitivity at $AsO^+$ (m/z=90.9165) was decreased about 25-fold, but the analytical results are the same that at $As^+$ (m/z=74.9216).

Utilization of the National-Level Resource Productivity Indicators Considering the Economic Value of Metal Resources (금속 자원의 경제적 가치를 고려한 국가 단위 자원생산성 지표 활용 방안)

  • Jong-Hyo Lee;Hong-Yoon Kang;Yong Woo Hwang;Sang-Hyun Oh
    • Clean Technology
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    • v.30 no.3
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    • pp.276-286
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    • 2024
  • Since the Paris Agreement and the surge in global interest in climate change, the importance of measuring and managing national-level resource productivity has steadily grown. However, concerns about the reliability of productivity indicators persist due to inherent uncertainties. This study estimated the metal and non-metal resource productivities of 38 OECD countries through multiple regression analysis and conducted a comparative analysis of their ranking changes according to their current resource productivities. The study results revealed that the 38 OECD countries could be classified into four categories. First, countries with low overall resource productivities due to a high economic dependence on low-value metal resources by weight exhibited a substantial rise in their non-metal resource productivity rankings. Second, countries that have minimal metal industries in their national economies but generate high value-added from these sectors showed a notable increase in their metal resource productivity rankings. Third, countries with a low proportion of metal industry in their economies and low metal resource productivities experienced significant declines in their metal resource productivity rankings. Fourth, countries with a small disparity between their metal and non-metal resource productivities showed minimal changes in their rankings for both categories. These results highlight that changes in metal resource productivity rankings were more pronounced than those for non-metal resources, which implies that the influence of non-metal resources (biomass, fossil fuels, non-metallic minerals) dominates national-level resource productivity because their economic value is higher than metal resources. These findings suggest that it is necessary to manage the economic value of each resource type as distinct statistical data to provide a more nuanced understanding of national resource productivity.