• Earthquakes and Structures
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• 제1권1호
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• pp.21-41
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• 2010

Multi-span steel-concrete composite (SCC) bridges are very sensitive to earthquake loading. Extensive damage may occur not only in the substructures (piers), which are expected to yield, but also in the other components (e.g., deck, abutments) involved in carrying the seismic loads. Current seismic codes allow the design of regular bridges by means of linear elastic analysis based on inelastic design spectra. In bridges with superstructure transverse motion restrained at the abutments, a dual load path behavior is observed. The sequential yielding of the piers can lead to a substantial change in the stiffness distribution. Thus, force distributions and displacement demand can significantly differ from linear elastic analysis predictions. The objectives of this study are assessing the influence of piers-deck stiffness ratio and of soil-structure interaction effects on the seismic behavior of continuous SCC bridges with dual load path, and evaluating the suitability of linear elastic analysis in predicting the actual seismic behavior of these bridges. Parametric analysis results are presented and discussed for a common bridge typology. The response dependence on the parameters is studied by nonlinear multi-record incremental dynamic analysis (IDA). Comparisons are made with linear time history analysis results. The results presented suggest that simplified linear elastic analysis based on inelastic design spectra could produce very inaccurate estimates of the structural behavior of SCC bridges with dual load path.

• 한국직업건강간호학회지
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• 제6권1호
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• pp.53-71
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• 1997

Across sectional study was performed to evaluate the chronic effects on central nerve system(CNS) of cumulative exposure of complex organic solvents, using neurobehavioral test. Subjects were 66 (male) dock yard painters of some large ship industry which is located in Ulsan. The neurobehavioral test battery used in this study was NCTB (Neurabehavioral Core Test Battery recommended by WHO(World Health Organization), which consisted of 7 items-Profile of mood states (POMS), Simple reaction time, Santa Ana dexterity test. Digit span, Digit symbol, Benton visual retention test and Pursuit aiming. The subjects were classified by 3 groups according to duration of employment(group 1 ; less than 9 years, group 2 ; 10-14 years, group 3 ; more than 15 years). The results of performance were analyzed considering of work duration, age, educational level, alcohol drinking, smoking and testing time as confounding factors. Benton visual retention test, pursuit aiming correct dot and sum of dot showed significant differences among the groups, and decreased with increasing work duration. It indicated that the mean scores of performance ability were lowering according to work duration. Besides, the tests that didn't show statistical significances but showed linear trends were depression-dejection, vigor, fatigue of POMS, slowest time of simple reaction time and digit span forward. Most of the neurobehavioral test items were correlated with age and educational level. After controlling of confounding factors-age and educational level, the results followed ; digit span backward was different significantly. Tension-anxiety, depression-dejection, anger-hostility of POMS, SD and slowest time of simple reaction time, Santa Ana dexterity test non-preferred hand, digit span forward, Benton visual retention test and pursuit aiming correct dot decreased with increasing of work duration. The correlation analysis was done in order to find out the relationship between subjective symptom and the scores of neurobehavioral core test battery. According to the results of analysis there were no items that had statistical significant relationship(p<0.05).

• 한국지진공학회논문집
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• 제6권2호
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• pp.29-37
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• 2002

본 연구는 철근콘크리트 연성 모멘트골조의 선형.비선형 정적해석을 통한 반응수정계수와 비선형 변위량을 평가하여 합리적인 내진설계의 기초자료를 제공하는 것을 목적으로 한다. 먼저 국내 내진설계 규준에 따라 각 모델을 설계한 후, 철근콘크리트 연성 모멘트골조의 반응수정계수와 비선형 변위량을 평가하였으며, 해석에 사용된 모델은 층수(10, 20, 30), 평면비(1:1, 1:2), 해석방법(2D, 3D)을 변수로 한 27개의 모델이다. 반응수정계수와 비선형 변위량의 평가는 각 모델별 선형.비선형 정적해석을 수행하여 그 결과를 비교 분석하여 산정하였다. 반응수정계수는 강도계수, 연성계수, 잉여도계수, 감쇠계수의 곱으로 산정하였고, 그 결과 해석방향의 저항골조의 수에 따라 2 스팬인 경우 3.5, 3 스팬인 경우 4.3, 4 스팬 이상인 경우에는 평면비나 층수와 상관없이 5.0에 근접한 결과를 나타내었다. 비선형 변위량은 층간변위각비(비선형 변위각/선형 변위각)에 의해 평가되었으며, 층간변위각비는 5.85에서 9.34로 나타났다.

• 한국정밀공학회지
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• 제15권1호
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• pp.78-86
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• 1998

This paper presents a numerical method of the minimum-time trajectory planning for a robot manipulator amid obstacles. Each joint displacement is represented by the linear combination of the finite-term quintic B-splines which are the known functions of the path parameter. The time is represented by the linear function of the same path parameter. Since the geometric path is not fixed and the time is linear to the path parameter, the coefficients of the splines and the time-scale factor span a finite-dimensional vector space, a point in which uniquely represents the manipulator motion. The displacement, the velocity and the acceleration conditions at the starting and the goal positions are transformed into the linear equality constraints on the coefficients of the splines, which reduce the dimension of the vector space. The optimization is performed in the reduced vector space using nonlinear programming. The total moving time is the main performance index which should be minimized. The constraints on the actuator forces and that of the obstacle-avoidance, together with sufficiently large weighting coefficients, are included in the augmented performance index. In the numerical implementation, the minimum-time motion is obtained for a planar 3-1ink manipulator amid several rectangular obstacles without simplifying any dynamic or geometric models.

• 한국지진공학회논문집
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• 제20권5호
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• pp.301-310
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• 2016

There are differences in seismic behavior between non-skewed bridges and skewed bridges due to in-plane rotations caused by pounding between the skewed deck and its abutments during strong earthquake. Many advances have been made in developing design codes and guidelines for dynamic analyses of non-skewed bridges. However, there remain significant uncertainties with regard to the structural response of skewed bridges caused by unusual seismic response characteristics. The purpose of this study is performing non-linear time history analysis of the bridges using abutment-soil interaction model considering pounding between the skewed deck and its abutments, and analyzing global seismic behavior characteristics of the skewed bridges to assess the possibility of unseating. Refined bridge model with abutment back fill, shear key and elastomeric bearing was developed using non-linear spring element. In order to evaluate the amplification of longitudinal and transverse displacement response, non-linear time history analysis was performed for single span bridges. Far-fault and near-fault ground motions were used as input ground motions. According to each parameter, seismic behavior of skewed bridges was evaluated.

• Advances in materials Research
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• 제12권1호
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• pp.15-29
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• 2023

In this paper, fracture analysis of a continuously inhomogeneous arch structure with two longitudinal cracks is developed in terms of the time-dependent strain energy release rate. The arch under consideration exhibits non-linear creep behavior. The cross-section of the arch is a rectangle. The material is continuously inhomogeneous along the thickness of the cross-section. The arch is loaded by two bending moments applied at its end sections. The mechanical behavior of the material is described by using a non-linear stress-strain-time relationship. The two longitudinal cracks are located symmetrically with respect to the mid-span of the arch. Due to the symmetry, only half of the arch is considered. Time-dependent solutions to strain energy release rate are obtained by analyzing the balance of the energy. For verification, time-dependent solutions to the strain energy release rate are derived also by considering the time-dependent complementary strain energy. The evolution of the strain energy release rate with the time is analyzed. The effects of material inhomogeneity, locations of the two cracks along the thickness of the arch and the magnitude of the external loading on the time-dependent strain energy release rate are evaluated.

• 한국산업융합학회 논문집
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• 제5권3호
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• pp.261-268
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• 2002

In this paper, the shape optimization is considered over the upper slab of reinforced concrete culvert. The sequential linear programming method (SLP) is used as a rational approach to this shape optimization. To make a comparison between the arch shaped member and the straight member for the upper slab, the culverts with 5~20m earth height were adopted. It is shown that the optimum rise/span is about 7%-13%, and the arch shaped member is more cheap (over 10%) than the straight member for the construction cost.

• 한국통신학회논문지
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• 제18권2호
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• pp.261-269
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• 1993

多重의 非線形性을 위한 변환을 시행하여 발생되는 待號系列로서 Kasamie 待號系列, GMW 待號系列, 그리고 No-Kumar 待號系列의 構造的인 특성을 褸造的으로 가질 수 있는 褸合待號系列을 제시한다. 본 논문에서 제시된 待號系列은 간단한 變數의 변경으로 旣存 待號系列의 發生알고리듬으로 쉽게 변형될 수 있는 특성을 갖고 있다. 컴퓨터 시뮬레이션과 實驗을 통하여 褸合待號系列은 쉬프트레지스터 段數 n-0(mod 4)에서 發生週期 $2^n$-1,發生群 $2^n/2$+1을 가지며 褸雜도(linear span)의 개선효과를 기대할 수 있음을 보였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1997년도 추계학술대회논문집; 한국과학기술회관; 6 Nov. 1997
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• pp.408-413
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• 1997

The linear dynamic response of a simply supported uniform beam under a moving load of constant magnitude is investigated. When the ratio of the moving weight and the structure weight is small, moving object is considered as a concentrated or distributed moving force, that is large external loading can be considered as a concentrated or distributed moving masses. Result from the numerical solutions of the differential equations of motion are shown graphically. Moreover, when considering the maximum deflection for the mid-span of the hewn, the critical speeds of the moving load have been evaluated.

• Tuberculosis and Respiratory Diseases
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• 제46권6호
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• pp.786-794
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• 1999

연구배경 : 척추의 이상굴곡 등으로 신장을 정확히 측정할 수 없는 환자에서 정상폐활량을 추정하기 위해서는 양팔벌린 손끝길이를 측정하여 신장을 예측한다. 연령을 고려하지 않고 고정된 비(AS/Ht ratio)를 이용하는 방법과 연령을 고려한 회귀방정식을 이용하는 두가지 방법이 있으며 이는 인종에 따라 다르다고 알려져있다. 대상 및 방법 : 우리나라 성인여성에서 양팔별린 손끝길이와 신장 그리고 연령과의 관계를 알아보고자 울산광역시에 거주하는 20-69세의 성인여성중 연령별로 표본추출된 381명(평균연령 $46.6{\pm}12.8$세, 평균신장 $154.3{\pm}5.7cm$)의 자료를 분석하였다. 결 과 : 우리나라 성인여성의 AS/Ht ratio는 $1.004{\pm}0.023$이다. 다중선형회귀분석상 양팔벌린 손끝길이와 연령이 모두 신장과 유의한 선형적 관련성을 보였다. Height(cm)=0.7094 Arm span(cm)-0.0891 Age(yr)+48.54(p=0.0001, $r^2$=0.76) AS/Ht ratio를 통한 신장 예측값와 실측값의 차이 즉, 잔차(residual)는 양팔벌린 손끝길이와 연령에 의해서 유의한 영향을 받는다 (p=0.0001). 양팔벌린 손끝길이 또는 연령이 감소할수록 AS/Ht ratio에 의한 신장 예측값은 실측값보다 낮아지며, 양팔벌린 손끝길이 또는 연령이 증가할수록 AS/Ht ratio에 의한 신장 예측값은 실측값보다 높아진다. 회귀방정식을 통한 신장 예측값과 실측값의 차이는 양팔벌린 손끝길이와 연령에 의한 영향을 받지 않는다(p>0.05). 결 론 : 우리나라 성인여성에서 정상폐활량 추정을 위한 신장 예측치를 구하고자 할 때 양팔벌린 손끝길이와 연령의 두 변수를 이용한 회귀방정식을 이용하는 것이 고정된 AS/Ht ratio를 이용하는 것보다 더 정확하다. As/Ht ratio는 양팔벌린 손끝길이와 연령의 양 극단에서 신장을 정확하게 예측하지 못한다.