• 대한토목학회논문집
• /
• 제10권3호
• /
• pp.1-6
• /
• 1990

다지점지진하중(多支點地震荷重)을 받는 사경문(四徑問) 연속철도교양(連續鐵道橋梁)의 동적거동(動的擧動)을 응답(應答)스펙트럼법(法)에 의하여 조사(調査)하였다. 소진복(小振福)의 진동(振動)과 재료(材料)의 선형(線形)-탄성거동(彈性擧動)을 가정(假定)하였으며, 지반(地盤)-구조물(構造物) 상호작용(相互作用) 효과(效果)는 무시(無視)하였고, 교량(橋梁)의 횡방향(橫方向) 등답(應答)만을 고려(考慮)하였다. 응답(應答)스펙트럼해석(解析)의 결과(結果)는 시간이력해석결과(時間履歷解析結果)와 비교(比較)되었으며 모우드 최대치(最大値)와 지지점운동(支持點運動)의 중량(重量)은 여러가지 조합법칙(組合法則) 즉(卽), Square-Root-Of-Sum-Squares, Double Sum, 그리고 P-Norm Rule을 적용(適用)하였다.

• Communications for Statistical Applications and Methods
• /
• 제4권1호
• /
• pp.101-109
• /
• 1997

For the detection on variance changes in the nonstationary time series with a unit root two types of test statistics are proposed, of which one is based on the cumulative sum of squares and the other is based on the likelihood ratio test. The properties of the cusum type test statistic are derived and the performance of two tests in small samples are compared through Monte Carlo study. It is ovserved that the test based on the cumulative sum of squares can detect a samll change in the variance faster than the one based on the likelihood ratio.

• 콘크리트학회논문집
• /
• 제14권5호
• /
• pp.677-688
• /
• 2002

철근콘크리트 기둥의 비선형 이축모멘트-곡률 관계를 추적할 수 있는 이론모델을 개발하였다. 개발된 모델은 피복콘크리트 박리나 또는 최대하중 후 나타날 수 있는 기둥의 모멘트 저항능력의 취성적인 감소도 모사할 수 있다. 개발된 모델을 이용 기둥의 구성재료 특성과 철근의 기하학적 배치가 PM 상관도와 모멘트-곡률에 미치는 영향에 대하여 변수영향을 고찰하고 철근콘크리트 기둥의 연성은 축하중의 크기, 횡방향 철근의 간격 또는 체적에 가장 큰 영향을 받음이 이론적으로 고찰된 ACI PM-상관도와 비교하여 ACI 내진설계 기준에 따라 횡방향 철근이 배근된 기둥의 경우, 축하중과 모멘트에 대한 : (square root of sum of squares)값이 약 10% 증가하였으며 최대 축하중은 약 20% 정도 증가하였다.

• 대한산업공학회지
• /
• 제36권4호
• /
• pp.243-247
• /
• 2010

Every products, which made by mass production, is not identical in their size but have variations in some intervals specified by tolerance dimensions. Tolerances play major role in standardization of part and its quality, and also make a huge impact on manufacturing cost. The optimal condition for tolerances is giving the values as loose as possible for low production cost while satisfying quality specification, which usually demand tight control of tolerances. Tolerance analysis is necessary to get an optimal solution for this conflict situation. This paper have studied tolerance analysis for universal joint assembly of vehicle steering system and tried to find useful results of the study for product design and quality control.

• 한국정밀공학회지
• /
• 제27권12호
• /
• pp.75-83
• /
• 2010

Every mechanical part for mass production has dimensions with tolerances in engineering drawing. Tolerance is given to guarantee assemble parts together satisfying functional requirements and dimensional constraints. Tolerance is essential factor for standardization of parts or assembly and has huge influence on manufacturing cost. It will be desirable to have tolerances as broad as possible for minimizing manufacturing cost. This paper describes tolerance analysis of u-joint assembly that is a part of automobile steering system. Within the range of tolerances of parts, accumulated effect is estimated by arithmetic calculation, probability theory and Monte carlo simulation. Each result is compared to investigate the method for increasing productivity.

• 품질경영학회지
• /
• 제33권3호
• /
• pp.91-104
• /
• 2005

Tolerance analysis plays an important role in design and manufacturing stages for reducing manufacturing cost by improving producibility. In most production processes encountered in practice, a process mean may shift or drift in the long run although process is in control. This study discusses the feasibility of three most common inflation factors(Bender, Gilson and Six Sigma) as a correction to Root Sum of Squares(RSS) method to compensate heuristically for a shift of process mean and nonnormal component distributions from simulation experiments and proposes the guidelines for choosing the inflation factor.

• 국제강구조저널
• /
• 제18권5호
• /
• pp.1508-1524
• /
• 2018

Hysteretic energy dissipating devices (HEDDs) have been increasingly applied to building construction to improve the seismic performance. The seismic responses of such damped structures are significantly affected by HEDD's structural properties. An accurate investigation on the propagation of HEDD's structural properties is required for reasonable evaluation of the seismic performance of a structure. This study aims to develop simplified methods that can estimate the collective uncertainty-propagation to the seismic response of damped structures employing HEDDs. To achieve this, three- and six-story steel moment-resisting frames were selected and the propagations of the individual HEDD's property-uncertainties were evaluated when they are subjected to various levels of seismic demand. Based on the result of individual uncertainty-propagations, a simplified method is proposed to evaluate the variation of seismic response collectively propagated by HEDD's property-uncertainties and is verified by comparing with the exact collective uncertainty-propagation calculated using the Monte Carlo simulation method. The proposed method, called as a modified SRSS method in this study, is established from a conventional square root of the sum of the squares (SRSS) method with the relative contributions of the individual HEDD's property-uncertainty propagations. This study shows that the modified SRSS method provides a better estimation than the conventional SRSS method and can significantly reduce computational time with reasonable accuracy compared with the Monte Carlo simulation method.

• Journal of Forest and Environmental Science
• /
• 제34권2호
• /
• pp.119-125
• /
• 2018

The tropical forests in developing countries are faced with the problem of illegal exploitation of trees. However, dearth of empirical means of expressing the dimensions, structure, quality and quantity of a removed tree has imped conviction of offenders. This study aimed at developing a model that can effectively estimate individual tree basal area (BA) from stump diameter (Ds) for Tectona grandis stands in Omo Forest Reserve, Nigeria, for timber valuation in case of illegal felling. Thirty-six $25m{\times}25m$ temporary sample plots (TSPs) were laid randomly in six age strata; 26, 23, 22, 16, 14, and 12 years specifically. BA, Ds and diameter at breast height were measured in all living T. grandis trees within the 36 TSPs. Least square method was used to convert the counted stumps into harvested stem cross-sectional areas. Six basal area models were fitted and evaluated. The BA-Ds relationship was best described by power model which gave least values of Root mean square error (0.0048), prediction error sum of squares (0.0325) and Akaike information criterion (-15391) with a high adjusted coefficient of determination (0.921). This study revealed that basal area estimation was realistic even when the only information available was stump diameter. The power model was validated using independent data obtained from additional plots and was found to be appropriate for estimating the basal area of Tectona grandis stands in Omo Forest Reserve, Nigeria.

• 한국기계가공학회지
• /
• 제19권4호
• /
• pp.45-51
• /
• 2020

In this study, a response spectrum analysis of an electric distributing board (EDB) was conducted to investigate seismic integrity in the design stage. For the seismic analysis, the required response spectra of a safe shutdown earthquake with 2% damping (RRS/SSE-2%) specified in GR-63-CORE Zone 4 was used as the ground spectral acceleration input. A finite element method modal analysis of the EDB was also performed to examine the occurrence of resonance within the frequency range of the earthquake response spectrum. Furthermore, static stress caused by deadweight was analyzed. The resultant total maximum stress of the EDB structure was calculated by adding the maximum stresses from both seismic and static loads using the square root of the sum of the squares (SRSS) method. Finally, the structural safety of the EDB was investigated by comparing the resultant total maximum stress with the allowable stress.

• 한국기계가공학회지
• /
• 제17권1호
• /
• pp.122-129
• /
• 2018

This study conducted a seismic qualification analysis of small savonius style vertical axis wind turbine(VAWT) using finite element method(FEM). The modal analysis was performed on the wind turbine structure to check the occurrence of resonance caused by the rotation of gearbox and windmill blades. Next, it conducted a seismic response spectrum analysis due to horizontal and vertical seismic load of required response spectrum of safe shutdown earthquake with 5 % damping(RRS/SSE 5%) of KS C IEC 61400 and conducted a static analysis due to deadweight and wind load. The total maximum stress of the VAWT structure was calculated by adding the maximum stresses due to each load case using the square root of the sum of the squares(SRSS) method. Finally, the structural safety of the VAWT structure was verified by comparing the total maximum stress and the allowable stress.