• Title/Summary/Keyword: Cone index

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EXISTENCE AND MULTIPLICITY OF POSITIVE SOLUTIONS FOR SINGULAR GENERALIZED LAPLACIAN PROBLEMS WITH A PARAMETER

  • Kim, Chan-Gyun
    • East Asian mathematical journal
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    • v.38 no.5
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    • pp.593-601
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    • 2022
  • In this paper, we consider singular 𝜑-Laplacian problems with nonlocal boundary conditions. Using a fixed point index theorem on a suitable cone, the existence results for one or two positive solutions are established under the assumption that the nonlinearity may not satisfy the L1-Carathéodory condition.

Bearing Capacity of Pavement Foundation by Waste Lime Material using the Dynamic Cone Pentrometer (동적 콘관입시험기를 이용한 폐석회 혼합 도로노반 성토체의 현장 지지력 평가)

  • Kim, Young-Seok;Hong, Seung-Seo;Bae, Gyu-Jin
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.12 no.2
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    • pp.927-935
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    • 2011
  • In-situ California Bearing Ratio(CBR) test has been widely used for evaluating the subgrade condition in pavements. However, because the in-situ CBR test is expensive and takes time for operation, it is difficult to figure out the in-situ characteristics of subgrade strength in detail. For faster and economical operation, the Dynamic Cone Penetrometer(DCP) has been often utilized for estimating the subgrade strength in the field. The purpose of this paper is to determine the relationship between CBR value and DCP index of the embankment constructed with mixtures of soil and waste lime. Waste lime used in this study is producted as a by-product in the manufacturing process of making $Na_2CO_3$ from local chemical factory in Incheon. In this field measurement, the geotechnical tests such as field water content, field density, field CBR test, and dynamic cone penetration test were conducted.

A Study for the Optimum Joint Set Orientations and Its Application to Slope Analysis (사면해석을 위한 최적의 절리군 대표방향성 도출 및 활용기법 연구)

  • Cho, Taechin
    • Tunnel and Underground Space
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    • v.28 no.4
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    • pp.343-357
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    • 2018
  • Algorithm which can analyze the slope failure behavior utilizing the comprehensive information of the dense point of joint poles and the joint set orientations, both of which are obtained statistically, and the defect pattern of pole distribution has been developed. This method overcomes the potential incorrectness of the hemispheric projection method utilizing the joint set orientations only and also enhances the reliability of slope failure analysis. To this end a method capable of calculating the joint dispersion index directly from the joint pole distribution, instead of contour map, has been devised. The representative orientations for the slope failure analysis has been determined by considering the number and orientations of cone angle-dependent joint sets as well as the joint dispersion index. By engaging these representative orientations to the hemispheric projection analysis more reliable slope failure examination has been carried out. Sensitivity analysis for the potentially unstable slope of plane failure mode has been performed. Significance of joint strength index and the external seismic loading on the slope stability has been fully analyzed.

Evaluation of Combustion Characteristics of Outdoor Advertisement Materials (옥외 광고물 소재의 연소특성 평가)

  • Eom, Sang-Yong;Kim, Kyoung-Jin;Lee, Su-Kyung
    • Fire Science and Engineering
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    • v.26 no.5
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    • pp.79-84
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    • 2012
  • Combustion characteristics of outdoor advertisement materials were evaluated for fire risk assessment about fire expanding. At this study, the flame retardancy and the limiting oxygen index (LOI) was measured by UL 94 and ASTM D 2863 respectively. At the result of flame retardancy, foamex was V-0 grade and those of others were out of grade. LOI measurement showed that the LOI of foamex was highest in the samples. The cone calorimeter test was done by ISO 5660-1 to find the combustion characteristics. The cone calorimeter test showed that the outdoor advertisement materials were not good to prevent of fire expanding. The time to ignition (TTI) of flex was the fastest and the peak heat release rate (PHRR) as well as the total heat release (THR) of acrylic panel was higher than those of others.

Flame Retardancy of Polypropylene/Montmorillonite Nanocomposites with Halogenated Flame Retardants (할로젠 계열의 난연제가 첨가된 폴리프로필렌/몬모릴로나이트 나노복합재료의 난연특성)

  • 이종훈;나중현;이대회;김명덕;공정호;이영관;남재도
    • Polymer(Korea)
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    • v.27 no.6
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    • pp.569-575
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    • 2003
  • The flame retardancy was investigated when the halogenated flame retardant, decabromodiphenyl oxide (DBDPO) and chlorinated paraffin wax (CPW), was added to the polypropylene (PP) / montmorillonite (MMT) nanocomposites. The flame retardancy of polymer resin could be improved not only by addition of flame retardant but also with nanoparticles compositions. The effect of the contents of flame retardant and nanoparticles on the flame retardancy of polypropylene/ montmorillonite nanocomposite systems was thoroughly examined in terms of limited oxygen index (LOI) and cone calorimetry. As a results of cone calorimetry, the heat release rate (HRR) was reduced by the flame retardant DBDPO and CPW, and CPW was a little better than DBDPO. The LOI increased from flammable region (LOI<19) to nonflammable region (LOI>20) for all the flame retardants used in this study. Especially, the improvement in flame retardancy by compounding with PP and MMT was better than that by adding flame retardant to polypropylene. So, the addition of flame retardant after compounding with montmorillonite was more efficient than simple addition of flame retardant.

Bone changes in the mandibular incisors after orthodontic correction of dental crowding without extraction: A cone-beam computed tomographic evaluation

  • Valerio, Claudia Scigliano;Cardoso, Claudia Assuncao e Alves;Arauujo, Eustaquio Afonso;Zenobio, Elton Goncalves;Manzi, Flavio Ricardo
    • Imaging Science in Dentistry
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    • v.51 no.2
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    • pp.155-165
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    • 2021
  • Purpose: This study aimed to evaluate changes of the alveolar bone and interdental bone septum of the mandibular incisors through cone-beam computed tomography (CBCT) after orthodontic treatment of mandibular dental crowding without dental extraction. Materials and Methods: The sample consisted of 64 CBCT images(32 pre-treatment and 32 post-treatment) from 32 adult patients with class I malocclusion and an average age of 23.0±3.9 years. The width and height of the alveolar bone and interdental septum, the distance between the cementoenamel junction (CEJ) and the facial and lingual bone crests, and the inclination of the mandibular incisors were measured. Results: The distance between the CEJ and the marginal bone crest on the facial side increased significantly (P<0.05). An increased distance between the CEJ and the bone crest on the facial and lingual sides showed a correlation with the irregularity index (P<0.05); however, no significant association was observed with increasing mandibular incisor inclination (P>0.05). The change in the distance between the CEJ and the marginal bone crest on the facial side was correlated significantly with bone septum height(P<0.05). Conclusion: Bone dehiscence developed during the treatment of crowding without extraction only on the incisors' facial side. Increasing proclination of the mandibular incisor was not correlated with bone dehiscence. The degree of dental crowding assessed through the irregularity index was associated with the risk of developing bone dehiscence. The interdental septum reflected facial marginal bone loss in the mandibular incisors.

Cone-beam computed tomography assessment of upper airway dimensions in patients at risk of obstructive sleep apnea identified using STOP-Bang scores

  • Eow, Pei Ying;Lin, Kar Yi;Kohli, Shivani;Math, Swarna Yerebairapura
    • Imaging Science in Dentistry
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    • v.51 no.4
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    • pp.439-446
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    • 2021
  • Purpose: The aim of this study was to identify correlations between the STOP-Bang score and upper airway dimensions using cone-beam computed tomography (CBCT) scans. Materials and Methods: This study included 101 subjects (46 men, 55 women) from dental patients who received CBCT scans from 2014 to 2020. The patients were divided into those with a low obstructive sleep apnoea (OSA) risk (STOP-Bang score<3) and those with an intermediate to high OSA risk (STOP-Bang score≥3), and their upper airway dimensions were then analysed on CBCT scans. Comparisons between the low-risk and intermediate/high-risk groups were conducted using the t-test and the Mann-Whitney test. Correlations between the total STOP-Bang score and upper airway dimension parameters were established using Spearman correlation coefficients. P values≤0.05 were considered to indicate statistical significance. Results: Intermediate/high-risk subjects were predominantly male and over 50 years of age, with a higher body mass index. They had significantly longer upper airways, smaller average airway volumes, and smaller widths and antero-posterior dimensions of the narrowest upper airway segment. The total upper airway length was positively correlated with the STOP-Bang score (rs=0.278). The average volume (rs= -0.203) and width of the narrowest upper airway segment(rs= -0.305) were both negatively correlated with STOP-Bang scores. Conclusion: Subjects with higher STOP-Bang scores had upper airways that were longer, narrower, and smaller in terms of average volume. CBCT scans taken for dental patients as part of investigative procedures could be correlated with STOP-Bang scores to screen for patients at risk of OSA.

Study on Flame Retardancy and Thermal Resistance Properties of Phenolic Foam and Polyurethane Foam (페놀 폼과 폴리우레탄 폼의 난연 및 내열성 연구)

  • Lee, Ju-Chan;Seo, Jung-Seok;Kim, Sang Bum
    • Journal of the Korean Institute of Gas
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    • v.17 no.1
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    • pp.35-41
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    • 2013
  • In this study, flame retardancy of polyurethane foam and phenolic foam were investigated by addition of phosphorous flame retardants. The thermal degradation behavior of polyurethane foam and phenolic foam in the presence of flame retardants has been studied by thermogravimetric analysis(TGA). Heat release rate(HRR), mean HRR, mass loss rate(MLR), total smoke released(TSR) and limited oxygen index(LOI) were tested by cone calorimeter. From the test results, Phenolic foam showed low HRR, MLR and TSR than polyurethane foam.

Effect of Stress History on CPT-DMT Correlations in Granular Soil (응력이력이 사질토의 CPT-DMT 상관관계에 미치는 영향)

  • Lee, Moon-Joo;Choi, Sung-Kun;Kim, Min-Tae;Lee, Ju-Hyeong;Lee, Woo-Jin
    • Journal of the Korean Geotechnical Society
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    • v.26 no.7
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    • pp.7-16
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    • 2010
  • Stress history increases the residual horizontal stress of granular soil and, consequently, the penetration resistance. This study analyzes the effect of stress history on the cone resistance ($q_c$), horizontal stress index ($K_D$) and dilatometer modulus ($E_D$) of CPT and DMT from calibration chamber specimen in OC as well as NC state. Test results show that the normalized cone resistance by mean effective stress correlates well with the relative density and the state parameter, whereas the normalized cone resistance by vertical effective stress is a little affected by stress history. The influence of stress history is more reflected on $K_D$ than $E_D$ and $q_c$. The $K_D/K_0$, in which the effect of stress history on $K_D$ is compensated by the at-rest coefficient of earth pressure, $K_0$, is related to relative density, state parameter and the normalized cone resistance by mean effective stress. It is also observed that the normalized dilatometer modulus by mean effective stress ($E_D/{\sigma}_m'$) shows a unique correlation with the state parameter, regardless of stress history.

Development of A System for Decision of Strength Parameters and of Degree of Compaction in Compacted Soil with Cone Penetrometer (콘관입시험기를 이용한 다짐도 측정 및 지반정수 추출법 개발)

  • Lim, YuJin;Lee, HyeonSeung
    • Journal of the Korean Geophysical Society
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    • v.7 no.1
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    • pp.23-30
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    • 2004
  • To evaluate the compaction in the domestic construction sites, mainly(PBT) plate bearing test is used. PBT may result in over-estimation in the well-compacted area. Estimation method for the degree of compaction was developed from the penetration index of the surface by cone penetration. The developed system is easily attached to the mobile transportation and directly can acquire the degree of compaction.

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