• 제목/요약/키워드: Empirical Test

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The influence of fine particle migration on pore structure of overlying ballast under cyclic loading

  • Yu Ding;Yu Jia;Zhongling Zong;Xuan Wang;Jiasheng Zhang;Min Ni
    • Geomechanics and Engineering
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    • 제35권6호
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    • pp.627-636
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    • 2023
  • The essence of subgrade mud pumping under train load is the migration of fine particles in subgrade soil. The migration of fine particles will change the pore structure of overlying ballast, thus affecting the mechanical properties and hydraulic properties of ballast layer. It is of great theoretical significance and engineering value to study the effect of fine particle migration on the pore structure of ballast layer under cyclic loading. In this paper, a tailor-made subgrade mud pumping test model and an X-ray computed tomography (CT) scanning equipment were used to study the influence of migration of fine particles in subgrade soil on the pore parameters (plane porosity, volume porosity, pore distribution and pore connectivity) of overlying ballast under cyclic loading. The results show that the compression of ballast pores and the blockage of migrated fine particles make the porosity of ballast layer decreases gradually. And the percentage of small pores in ballast layer increases, while the percentage of large pores decreases; the connectivity of pores also gradually decreases. Based on the test results, an empirical model of ballast porosity evolution under cyclic loading is established and verified.

k-모집단 동질성검정에서 피어슨검정의 오차성분 분석에 관한 연구 (Error cause analysis of Pearson test statistics for k-population homogeneity test)

  • 허순영
    • Journal of the Korean Data and Information Science Society
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    • 제24권4호
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    • pp.815-824
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    • 2013
  • 국가단위의 조사와 같은 대규모 표본조사에서는 표본의 대표성을 확보하기 위해 층화, 집락, 계통, 불균등확률추출 등을 종합적으로 사용하는 복합표본설계가 일반화되어 있다. 이러한 복합표본설계에 기초한 범주형 자료분석에서는 자료의 독립성과 다항분포를 가정하는 전통적인 피어슨검정이 왜곡된 검정결과를 가져올 수 있다. 본 연구는 복합표본설계에 의한 범주형조사자료의 k-모집단 동질성검정에서 설계기반 일치통계량인 Wald 검정통계량을 유도하고, 전통적인 피어슨검정통계량을 사용할 경우 발생할 수 있는 오차요인을 항목별로 분해하여, 분산의 편의에 의한 영향, 추정량의 편의에 의한 영향, 기타 분산의 편의와 추정량의 편의가 교락되어 미치는 영향으로 각각 분해하는 식을 도출하였다. 또한, 도출된 식의 각 항목이 피어슨 카이제곱검정통계량에 미치는 상대적 크기를 경험적으로 확인하기 위해 국민건강영양조사 제4기 2차년도 자료를 이용해 경험분석 하였다. 분석결과, 변수에 따른 차이는 있지만 대체로 분산의 편의가 미치는 영향이 추정량의 편의가 미치는 영향보다 크다는 것을 명확히 확인할 수 있었다.

반복삼축시험에 의한 실트 모래 지반의 액상화 특성 연구 (The Study on Liquefaction Characteristics of Silty Sand Soils by Cyclic Triaxial Test)

  • 이송;전제성;김태훈
    • 한국지반공학회논문집
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    • 제15권4호
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    • pp.133-152
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    • 1999
  • 국내 서해안 실트질 모래의 액상화 특성과 시료교란의 영향을 파악하고자 교란된 시료를 재성형하여 반복삼축시험을 수행하였다. 먼저, 실트질 모래의 응력-변형 거동에서 축변형률 $\pm10%$ 근처에서 액상화 현상이 발생했으며, 간극수압 거동은 Seed, Martin, Lysmer 등(1975)이 제안한 식과 거의 유사했다. 또한, 시료의 파괴시 dilatancy 현상을 살펴볼 수 있었다. 다음은 여러 연구자들이 제안한 액상화 평가방법들을 실시하여 그 결과를 비교했을때 액상화에 취약한 심도를 비슷하게 나타내고 있었으며, 재성형을 실시한 반복삼축시험을 통한 방법은 그 중 가장 낮은 안전율을 나타내고 있었다. 또한, 반복삼축 시험으로 구한 응력비와 경험적 방법의 표준관입시험 N값으로 구한 응력비를 비교했을때 시료교란의 영향은 N값이 20이하에서는 상대적으로 작지만, N값이 20이상일 때 교란의 효과와 시료 재성형시의 문제점 등으로 액상화 저항력과 안전율에서 큰 차이를 보였다.

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현장탄성계수에 근거한 보조기층 다짐관리방안 연구 (A Study on Establishing the Subbase Compaction Control Method based on the In-situ Elastic modulus)

  • 최준성;김종민;한진석;김부일
    • 한국도로학회논문집
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    • 제13권1호
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    • pp.33-40
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    • 2011
  • 국내에서 일반적으로 보조기층재료로 사용되고 있는 보조기층 다짐재료의 역학적 특성을 반영한 실내 회복탄성계수는 역학적-경험적 포장설계법에서 적용하는 설계 인자이다. 따라서, 역학적-경험적 포장설계법의 보조기층 현장에서 실시하여야 하는 다짐관리는 다짐 후 측정된 현장 탄성계수가 설계에 적용된 실내 회복탄성계수를 만족하는지 여부를 확인하여야 할 것이다. 이를 위하여 본 연구에서는 기존 다짐관리 시험인 들밀도 시험과 평판재하시험(PBT)의 시험결과와 현장탄성계수와의 상관성을 분석하였고, 현장에서 탄성계수를 측정할 수 있는 소형 충격 재하시험(LFWD)을 통한 현장탄성계수와 실내 회복탄성계수와의 상관관계식과 시험간격을 제안하였다. 또한 제안된 상관관계를 이용하여 현장시험을 통한 보조기층의 다짐관리방안을 제안하였다.

Prediction of 305 Days Milk Production from Early Records in Dairy Cattle Using an Empirical Bayes Method

  • Pereira, J.A.C.;Suzuki, M.;Hagiya, K.
    • Asian-Australasian Journal of Animal Sciences
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    • 제14권11호
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    • pp.1511-1515
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    • 2001
  • A prediction of 305 d milk production from early records using an empirical Bayes method (EBM) was performed. The EBM was compared with the best predicted estimation (BPE), test interval method (TIM), and the linearized Wood's model (LWM). Daily milk yields were obtained from 606 first lactation Japanese Holstein cows in three herds. From each file of 305 daily records, 10 random test day records with an interval of approximately one month were taken. The accuracies of these methods were compared using the absolute difference (AD) and the standard deviation (SD) of the differences between the actual and the estimated 305 d milk production. The results showed that in the early stage of the lactation, EBM was superior in obtaining the prediction with high accuracy. When all the herds were analyzed jointly, the AD during the first 5 test day records were on average 373, 590, 917 and 1,042 kg for EBM, BPE, TIM, and LWM, respectively. Corresponding SD for EBM, BPE, TIM, and LWM were on average 488, 733, 747 and 1,605 kg. When the herds were analyzed separately, the EBM predictions retained high accuracy. When more information on the actual lactation was added to the prediction, TIM and LWM gradually achieved better accuracies. Finally, in the last period of the lactation, the accuracy of both of the methods exceeded EBM and BPM. The AD for the last 2 samples analyzing all the herds jointly were on average 141, 142, 164, and 214 kg for LWM, TIM, EBM, and BPE, respectively. In the current practices of collecting monthly records, early prediction of future milk production may be more accurate using EBM. Alternatively, if enough information of the actual lactation is accumulated, TIM may obtain better accuracy in the latter stage of lactation.

직장남성의 패션행동 및 인상관리행동이 경력성공에 미치는 영향 -PLS 구조방정식 모형을 적용하여- (The Effects of Fashion Behaviors and Impression Management Behaviors on Career Success of Male Office Workers -Applying PLS Structural Equation Modeling-)

  • 류은숙;류은영
    • 한국의류학회지
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    • 제40권1호
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    • pp.131-147
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    • 2016
  • This study investigated the relationship between fashion behavior, impression management behavior, and career success. A conceptual model and hypotheses were established based on theoretical linkages between the constructs. Thereafter, empirical data were collected using a set of questionnaires. For this reason, the sample was taken from 720 office workers' who worked at 14's Korea Enterprise, 697 of which was used for an empirical analysis (sample: men over 30 years of age and more than three years continuous service). This study conducted an exploratory factor analysis and confirmatory factor analysis for the validity test. Cronbach's alpha test is used for the reliability test. Moreover, PLS structural equation modeling (SEM) was employed to test hypothesized relationships in the conceptual model (SPSS 20.0 window/Smart PLS 3.0). This study shows that the proposed model is reasonably fit to the actual data. The following results were obtained from the analyses. First, fashion behavior and impression management behavior is positively related to career success. The result shows that economics of the fashion behaviors sub-types were statistically more significant to influence career success. The self-focused of the impression management behavior sub-types were more than statistically significant to influence career success. This finding has great implications to understand self-management behavior and the career success of male office workers.

격자형 강합성 바닥판 이음부의 전단내력 평가 (Shear Resistance Evaluation of Steel Grid Composite Deck Joint)

  • 신현섭;박기태
    • 한국산학기술학회논문지
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    • 제14권10호
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    • pp.5290-5298
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    • 2013
  • 본 논문에서는 프리캐스트 방식으로 제작 가능한 격자형 강합성 바닥판의 이음부에 기계식 연결방식을 적용하고자 콘크리트 전단키와 고장력볼트로 구성되는 이음부에 대해 Push-out 시험으로 전단내력을 구하였으며, 이를 전단마찰 이론에 근거한 이론식 및 설계식과 비교함으로써 전단내력을 평가하였다. 분석결과에 따르면, 이음부 접합면을 에폭시로 부착한 경우가 전단키를 강판으로 보강한 경우 보다 약 10% 정도 더 큰 전단내력을 갖는 것으로 나타났으나, 실험체간 전단내력의 편차는 전단키를 강판으로 보강한 경우가 더 작게 나타났다. 실험결과를 계산식 및 설계식과 비교한 결과, 기존 설계식으로 안전하게 설계될 수 있음을 알 수 있었다. 그러나, ACI-318에 의할 경우 이음부 전단내력이 과소평가되기 때문에 LRFD에서 제시된 설계식의 적용이 더 적당한 것으로 분석되었다.

여성사용자의 평가어휘지표에 의한 공간 환경 분석에 관한 연구 - 미술관 공간 환경의 비교연구를 중심으로 - (An Empirical Analysis of Museums' Spatial Environments using a Sensibility Rating Scale of Women's)

  • 한명흠
    • 한국실내디자인학회논문집
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    • 제20권6호
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    • pp.192-199
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    • 2011
  • The purposes of this study are to present the criteria for a sensibility rating scale for measuring the general women's perception of museums' spatial environment, through an empirical analysis; and to clarify the characteristics of the presented rating scale in terms of each rating element and factor. For this study, a survey was conducted during August 19 - September 16, 2010, and a total of 342 museum visitors participated in the survey. A sensibility rating scale used for the survey consisted of a total of 32 adjectives selected from a literature review of previous studies. To specify the dimensions of semantic space using the semantic adjectives, words with opposite meanings were analyzed with the semantic differential technique developed by Osgood et al. Using SPSS, a reliability analysis, factor analysis were conducted on the data obtained from the survey. The results of this study can be summarized as follows: According to the women's perception of museums' spatial environment, six factors were found from the 25 semantic ratings of the Museum. The summarized criteria were: 'aesthetic', 'pleasant', 'valuable', 'function', 'affinity', and 'material.' The derived criteria were verified through an empirical test using emotional adjectives. In the coming years, the results of this study will serve as valuable data for constructing a sensibility rating scale for evaluating spatial environments of museums.

Strategic Intuition Capability toward Performance of Entrepreneurs: Evidence from Thailand

  • AUJIRAPONGPAN, Somnuk;RU-ZHE, Jintanee;JUTIDHARABONGSE, Jaturon
    • The Journal of Asian Finance, Economics and Business
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    • 제7권6호
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    • pp.465-473
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    • 2020
  • The objective of this research is to study the confirmative components of strategic intuition capability and the study of causal influence between strategic intuition capability and firm performance of SMEs in Thailand. The consistency method, structural equation models and empirical data were used to test the influential factors on firm performance. Models were then proposed for the development of the strategic intuition capability of entrepreneurs in Thailand. The research sample consisted of 342 SME provincial champion entrepreneurs listed with Thailand's Office of Small and Medium Enterprises. The research results reveal that the model of strategic intuition capability responded well to the empirical data. Additionally, a relationship was identified between firm performance and the causal influence of the strategic intuition capability of entrepreneurs. In accordance with the empirical data, the strategic intuition capability of entrepreneurs had a significant causal influence on firm performance (Chi-square = 35.71, df = 25, P-value = 0.07615, GFI = 0.98, AGFI = 0.96, RMSEA = 0.033, RMR = 0.027). Furthermore, with respect to the development of strategic intuition capability, the development of genuine wisdom based on systematic knowledge management achieved via conscious mental concentration may lead to the next stage of strategic intuition.

Dynamic Linkages between Food Inflation and Its Volatility: Evidence from Sri Lankan Economy

  • MOHAMED MUSTAFA, Abdul Majeed;SIVARAJASINGHAM, Selliah
    • The Journal of Asian Finance, Economics and Business
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    • 제6권4호
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    • pp.139-145
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    • 2019
  • This study examines the dynamic linkages between food price inflation and its volatility in the context of Sri Lanka. The empirical evidence derived from the monthly data for the period from 2003M1 to 2017M12 for Sri Lanka. The relationship between inflation rate and inflation volatility has attracted more attention by theoretical and empirical macroeconomists. Empirical studies on the relationship between food inflation and food inflation variability is scarce in the literature. Food price inflation is defined as log difference of food price series. The volatility of a food price inflation is measured by conditional variance generated by the FIGARCH model. Preliminary analysis showed that food inflation is stationary series. Granger causality test reveals that food inflation seems to exert positive impact on inflation variability. We find no evidence for inflation uncertainty affecting food inflation rates. Hence, the findings of the study supports the Friedman-Ball hypothesis in both cases of consumer food price inflation and wholesale food price inflation. This implies that past information on food inflation can help improve the one-step-ahead prediction of food inflation variability but not vice versa. Our results have some important policy implications for the design of monetary policy, food policy thereby promoting macroeconomic stability.