• Communications for Statistical Applications and Methods
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• 제30권2호
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• pp.191-213
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• 2023

Unit distributions are frequently used in probability theory and statistics to depict meaningful variables having values between zero and one. Using convenient transformation, the unit inverse exponentiated weibull (UIEW) distribution, which is equally useful for modelling data on the unit interval, is proposed in this study. Quantile function, moments, incomplete moments, uncertainty measures, stochastic ordering, and stress-strength reliability are among the statistical properties provided for this distribution. To estimate the parameters associated to the recommended distribution, well-known estimation techniques including maximum likelihood, maximum product of spacings, least squares, weighted least squares, Cramer von Mises, Anderson-Darling, and Bayesian are utilised. Using simulated data, we compare how well the various estimators perform. According to the simulated outputs, the maximum product of spacing estimates has lower values of accuracy measures than alternative estimates in majority of situations. For two real datasets, the proposed model outperforms the beta, Kumaraswamy, unit Gompartz, unit Lomax and complementary unit weibull distributions based on various comparative indicators.

• Geomechanics and Engineering
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• 제17권5호
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• pp.439-444
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• 2019

It is generally known that high strength soil is indicative of well-graded particle size distribution. However, there are some special cases of firm ground despite poor grade distribution, especially a specific gap-graded soil. Based on these discoveries, this study investigated the development of an additive of gap-graded soils designed to increase soil strength. This theoretical concept was used to calculate the mixed ratio required for optimal soil strength of the ground sample. The gap-graded aggregate was added according to Plato's polyhedral theory and subsequently calculated ratio and soil strength characteristics were then compared to characteristics of the original soil sample through various test results. In addition, the underground stress transfer rate was measured according to the test conditions. The test results showed that the ground settlement and stress limit thickness were reduced with the incorporation of gap-graded soil. Further field tests would confirm the reproducibility and reliability of the technology by using gap-graded soil to reinforce soft ground of a new construction site. Gap-graded soil has the potential to reduce the construction cost and time of construction compared to other reinforcing methods.

• 소성∙가공
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• 제19권2호
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• pp.88-94
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• 2010

The next generation of diesel engine can operate at high injection pressure up to 1,800bar. The common rail pipe must have higher internal strength because it is directly influenced by the high-pressure fuel. Folding defects in the Common rail pipe can not ensure the structural safety. Therefore, Preform design and fatigue-life analysis are very important for preventing the head of the common rail pipe from folding in the heading process and for predicting fatigue life according to the amount of folding. In this study, a closed form equation to predict fatigue life was suggested by Goodman theory and pressure vessels theory in ASME Code in order to develop an optimization technique of the heading process and verified its reliability through fatigue-structural coupled field analysis. The results calculated by the theory were in good agreement with those obtained by the finite element analysis.

• 소성∙가공
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• 제31권5호
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• pp.261-266
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• 2022

To reduce the weight of the vehicle, the application of the high strength steel sheets to chassis parts is increased. High forming load is induced during the shearing process of steel chassis parts made of high strength steel, and the possibility of an eccentric load is increased depending on the product seating condition on the die, which decreases the stability and lifespan of the die. In this paper, a three-dimensional finite element analysis with the continuum element was conducted using the damage theory for the cam-trimming process of the front lower arm. The structural analysis of the trimming die was performed with the forming load result obtained from the analysis, and the amount of deflection and the stress distribution of the die during the shearing process were evaluated for the confirmation of the tool stability. The shape of the weak region of the die was modified according to structural analysis and then the stability was confirmed with the finite element analysis. The analysis result showed that the possibility of tool failure during cam-trimming process was remarkably reduced, and the reliability of the proposed modified design was validated.

• 대한토목학회논문집
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• 제1권1호
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• pp.33-42
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• 1981

현행(現行) 철근(鐵筋)콘크리트 표준시방서(標準示方書)는 WSD와 USD의 재래적(在來的)인 두 가지 설계편(設計編)으로 구성(構成)되어 있는데 이들 설계기준(設計基準)은 ACI 318-63 및 318-71 Code에 기초를 두고 있다. 이와 같이 주로 ACI 318-63 시방서(示方書)에 기초를 둔 우리의 WSD와 USD의 안전율(安全率)은 우리의 설계(設計) 및 시공실무(施工實務)에 비(比)해 부적절(不適切)한 것으로 받아들여지고 있다. 더구나 ACI의 안전율(安全率)도 확률적(確率的)으로 결정(決定)된 것이 아니고 주로 경험(經驗)과 현실성(現實性)을 고려하여 결정(決定)된 것이다. 본(本) 연구(硏究)는 현행(現行) 허용응력설계(許容應力設計) 안전율규정(安全率規定)으로 설계(設計)되는 휨 부재(部材)의 안전수준(安全水準)을 2차(次)모멘트 신뢰성이론(信賴性理論)에 의해 고찰(考察)하고, 일관성(一貫性)있는 목표신뢰성(目標信賴性)을 제공(提供)하는 철근(鐵筋) 및 콘크리트의 공칭안전율(公稱安全率)과 휨 허용응력(許容應力)을 합리적(合理的)이고도 효율적(效率的)으로 결정(決定)하는 방법(方法)을 제안(提案)하였다. Cornell의 제(第)1계(階) 이차(二次)모멘트법(法)을 하중(荷重)과 저항(抵抗) 결과변화(結果變化)의 대수변환(對數變換)에 의해 적용(適用)하는 방법(方法)을 본(本) 연구(硏究)의 신뢰성해석법(信賴性解析法)으로 사용하였다. 최적(最適) 철근비(鐵筋比)를 갖는 극한강설계(極限强設計)의 과소철근(過少鐵筋)보에 대응하는 균형철근비(均衡鐵筋比)로 설계(設計)되는 균형단면(均衡斷面)이 되도록 하는 독특한 방법으로 콘크리트의 허용압축응력(許容壓縮應力)을 유도하였다. 우리의 시공(施工) 및 설계실무(設計實務)의 수준(水準)에 적합(適合)한 ${\beta}_0=4$를 안전율(安全率) 결정(決定)을 위한 목표신뢰성지수(目標信賴性指數)로 택하였다. 현행(現行) WSD 시방서(示方書)로 설계(設計)되는 RC 휨 부재(部材)의 안전(安全) 및 신뢰성(信賴性)을 여러 수치계산(數値計算)을 통해 고찰(考察)해본 결과(結果), 현행(現行) WSD 기준(基準)에 의한 설계(設計)는 비정당적(非定當的)이며 일관성(一貫性)없는 신뢰성(信賴性)으로 인하여 비경제적(非經濟的)인 설계(設計)도 된다는 사실(事實)을 알 수 있었다. 적절(適切)한 목표신뢰성지수(目標信賴性指數) ${\beta}_0=4$에 따른 휨 부재(部材)의 철근(鐵筋)과 콘크리트의 합리적(合理的)인 허용응력(許容應力)을 본(本) 연구(硏究)의 신뢰성이론(信賴性理論)에 의해 제안(提案)하였다.

• Geomechanics and Engineering
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• 제28권3호
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• pp.299-311
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• 2022

Water-resisting key stratum (WKS) between coal seams is an important barrier that prevents water inrush from goaf in roof under multi-seam mining. The occurrence of water inrush can be evaluated effectively by analyzing the fracture of WKS in multi-seam mining. A "long beam" water inrush mechanical model was established using the multi-seam mining of No. 2+3 and No. 8 coal seams in Xiqu Mine as the research basis. The model comprehensively considers the pressure from goaf, the gravity of overburden rock, the gravity of accumulated water, and the constraint conditions. The stress distribution expression of the WKS was obtained under different mining distances in No. 8 coal seam. The criterion of breakage at any point of the WKS was obtained by introducing linear Mohr strength theory. By using the mechanical model, the fracture of the WKS in Xiqu Mine was examined and its breaking position was calculated. And the risk of water inrush was also evaluated. Moreover, breaking process of the WKS was reproduced with Flac3D numerical software, and was analyzed with on-site microseismic monitoring data. The results showed that when the coal face of No. 8 coal seam in Xiqu Mine advances to about 80 m ~ 100 m, the WKS is stretched and broken at the position of 60 m ~ 70 m away from the open-off cut, increasing the risk of water inrush from goaf in roof. This finding matched the result of microseismic analysis, confirming the reliability of the water inrush mechanical model. This study therefore provides a theoretical basis for the prevention of water inrush from goaf in roof in Xiqu Mine. It also provides a method for evaluating and monitoring water inrush from goaf in roof.

• 한국심리학회지 : 문화 및 사회문제
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• 제15권1호
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• pp.187-205
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• 2009

본 연구에서는 김정호 등의 동기상태이론에 기초해서, 주관적 웰빙의 인지적 요소의 측정으로 현재 대표적으로 사용되는 삶의 만족척도 외에 삶의 기대척도를 추가한 김정호(2007)의 연구를 확장하여 주관적 웰빙 측정의 보완을 다루었다. 본 연구에는 삶의 기대척도 외에 삶의 만족을 위한 동기의 강도를 측정하기 위해 삶의 동기척도를 포함하였다. 본 연구에는 모두 286명의 남녀 대학생이 참여하였으며 그 결과는 다음과 같다. 먼저 본 연구에서 주관적 웰빙의 구성요소로 삶의 만족과 삶의 기대가 독립적으로 구분이 되는지 보기 위해 각각의 측정에 사용되는 총 10 문항에 대해 요인분석을 실시한 결과 삶의 만족척도와 삶의 기대척도의 문항들이 두 개의 요인으로 잘 구분되었다. 특히 삶의 만족척도뿐만 아니라 삶의 기대척도도 별도의 집단을 통한 검사-재검사에서 좋은 신뢰도를 보였다. 둘째, 주관적 웰빙과 관련된 변인의 설명에 삶의 만족, 삶의 기대 및 삶의 동기가 유의한 예측변인인지를 알아보기 위해 회귀분석을 실시한 결과 전반적으로 삶의 만족이 주요한 예측변인이었고 삶의 기대가 추가적으로 유의한 예측변인이었다. 예외적으로 특성분노의 경우에는 삶의 동기가 주요한 예측변인이었다. 셋째, 삶의 동기, 삶의 만족 및 삶의 기대와 웰빙 관련 변인들간의 관계에서 남녀에 따른 차이를 살펴본 결과 우울, 특성불안, 특성분노, 부정정서 등의 설명에서 약간의 차이를 보였다. 끝으로 동기상태이론의 입장에서 주관적 웰빙의 측정에서 삶의 기대의 포함이 갖는 중요성과 본 연구의 제한점을 논의하였다.