• Structural Engineering and Mechanics
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• 제43권6호
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• pp.835-845
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• 2012

This paper focuses on the stochastic response analysis of industrial masonry chimneys to surface blast-induced random ground motions by using a three dimensional finite element model. Underground blasts induce ground shocks on nearby structures. Depending on the distance between the explosion centre and the structure, masonry structures will be subjected to ground motions due to the surface explosions. Blast-induced random ground motions can be defined in terms of the power spectral density function and applied to each support point of the 3D finite element model of the industrial masonry system. In this paper, mainly a parametric study is conducted to estimate the effect of the blast-induced ground motions on the stochastic response of a chimney type masonry structure. With this purpose, different values of charge weight and distance from the charge centre are considered for the analyses of the chimney. The results of the study underline the remarkable effect of the surface blast-induced ground motions on the stochastic behaviour of industrial masonry type chimneys.

• 자원ㆍ환경경제연구
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• 제30권4호
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• pp.581-605
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• 2021

본 연구의 목적은 전통적 에너지효율의 지표인 에너지원단위(Energy Intensity)를 넘어 확률적 프런티어 접근으로 우리나라의 지역별 에너지효율성을 추정하고 이를 에너지효율 개선을 위한 기초적 자료로 제공하고자 함이다. 이를 위해 1998 - 2018년 기간 동안의 우리나라 16개 시·도의 에너지효율성 및 에너지원단위 효율성을 확률적 거리함수를 활용하여 추정한다. 부가적으로 선행연구에서 혼재하고 있는 자본스톡 추계방법들에 따른 에너지효율성 순위의 강건성을 살펴본다. 분석 결과 첫째, 세 가지 에너지효율의 지표에 따라 지역의 순위에 상당한 변동이 있었으므로 이들을 상호보완적으로 사용해야 할 것이다. 둘째, 에너지효율성은 시간이 지남에 따라 미미하지만 조금씩 개선된 반면, 에너지원단위 효율성은 미미하지만 하락했다. 마지막으로 자본스톡 추계방법에 따른 지역별 에너지효율성은 강건하지 않았다. 경제분석에서 중요한 자본스톡 추정 시 신중을 기해야 할 것이다.

• 대한수학회보
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• 제36권2호
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• pp.287-303
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• 1999

The general solution of the functional equation f1(pr, qs) + f2(ps, qr) = g(p,q) + h(r,s) for p, q, r, s $\in$] 0, 1[will be investigated without any regularity assumptions on the unknown functions f1, f2, g, h:]0.1[->R.

• 경영과학
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• 제34권3호
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• pp.1-14
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• 2017

This study empirically analyzes the impact of inventory management performance on the energy efficiency in Korean petrochemical companies. The concept of the distance function is used to define the energy efficiency and the estimation of the distance function is performed using the stochastic frontier analysis. The inventory turnover is selected as the variable indicating the inventory management performance of the company. The main results of this study are as follows. First, the inventory turnover has a positive impact on energy efficiency. Second, during the period over 2011~2015, while the gap in energy efficiency among the companies expanded, the average energy efficiency decreased. Third, the average energy efficiency in upstream process companies was greater than downstream process companies and the gap in energy efficiency among downstream process companies was greater than upstream process companies. Fourth, the average marginal effect of inventory turnover on energy efficiency increased gradually from 2011 to 2015. Finally, the average marginal effect of inventory turnover in downstream process companies was greater than upstream process companies, and the gap in the marginal effect of inventory turnover among downstream process companies was greater than upstream process companies. These results together imply the importance of inventory management in terms of energy efficiency.

• 한국해안·해양공학회논문집
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• 제24권5호
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• pp.305-318
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• 2012

직립 케이슨 방파제에 대한 기존의 성능설계법은 임의의 시간 동안의 평균활동량을 산정하지만 허용활동량을 최초로 초과하는 사건의 발생확률(최초통과확률)은 계산하지 못한다. 설계자는 구조물이 최초로 피해를 입을 확률에 대한 정보를 구조물의 설계 단계뿐 아니라 관리 및 운영에서도 필요로 한다. 따라서 본 연구에서는 케이슨 활동의 최초통과확률을 산정하기 위해 확률과정에 기반한 시간의존 신뢰성 설계법을 개발하였다. 방파제의 활동을 일으키는 폭풍파는 발생 시간과 강도의 임의성의 특징이 있기 때문에 Poisson spike process를 사용하여 케이슨 활동을 정식화할 수 있다. 여기서 방파제의 활동을 일으키는 폭풍파의 발생률은 활동량분포함수와 폭풍파의 평균발생률로 표현된다. 성능설계법으로 모의된 이들은 설계변수들의 다변량 회귀함수로 나타내진다. 결과적으로 활동량분포함수와 폭풍파의 평균발생률은 유의파고, 케이슨 폭, 수심의 함수로 표현되어 케이슨 활동에 대한 최초통과확률을 손쉽게 산정할 수 있다.

• 자원ㆍ환경경제연구
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• 제30권3호
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• pp.471-501
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• 2021

본 연구는 투입물 거리함수에 의한 메타확률 프런티어 방법을 사용하여 1998년부터 2018년까지 4개 소득그룹의 이산화탄소 기준의 환경효율성(EE)을 측정하였다. 에너지 소비가 이산화탄소 배출을 증가시키고, 노동과 자본투입을 증가하면 이산화탄소 배출을 감소시킬 것임을 보여주고 있다. 또한 그룹환경효율성(GEE: Group Environmental Efficiency), 메타환경효율성(MEE: Meta Environmental Efficiency) 및 환경격차(EGR: Environmental Gap Ratio)를 비교하였다. 결과는 GEE가 과대평가되고 MEE는 이 기간 동안 하향세를 보여주고 있다. 중하위 소득그룹의 EGR은 가장 높았다. 그리고 고소득 및 중상위 소득그룹의 MEE 및 EGR이 상대적으로 낮았다. 환경효율성을 높이려면 화석에너지를 저감하고 기준 환경 문제를 해결하는 방법이 보다 과학적이고 기술적인 방법을 찾아 필요가 있음을 시사한다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.292-297
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• 2003

A stochastic approach has been presented for superplastic deformation of Ti-6AJ-4V alloy, and probability function are used to heterogeneous phase distributions. The experimentally observed spatial correlation function are developed, and microstructural evolutions together with superplastic deformation behavior have investigated by means of the probability function. The result have shown that the probability varies approximately linearly with separation with distance, and significant deformation enhanced probability changes during the deformation. The stress-strain behavior with the evolutions of probability function can be correctly predicted by the model. The finite clement implementation using Monte Carlo simulation associated with phase re-distributions shows that better agreement with experimental data of failure strain on the test specimen.

• 한국분말재료학회지
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• 제10권3호
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• pp.201-208
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• 2003

Distributions of diamond particles protruding on the surface of worn diamond segments in circular saw has been investigated. Scanning electron microscope was used to examine the worn ,surface and radial saw blade wear and grinding ratio was measured. The number of protruded diamond particle was approximately 50% of the total number of particles, and that was independent of diamond particle concentration and table speed. It was also noted that the inter-particle distance did not follow a symmetric function like Gaussian distribution function, instead it fitted well with a probability density function based on gamma function. The distribution of inter-particle spacing, therefore, was analyzed using a gamma function model.

• Earthquakes and Structures
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• 제11권4호
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• pp.701-721
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• 2016

Base isolation is a well-established passive strategy for seismic response control of buildings. In this paper, an efficient framework is proposed for reliability-based design optimization (RBDO) of isolated buildings subjected to uncertain earthquakes. The framework uses reduced function evaluations method, as an efficient tool for structural reliability analysis, and an efficient optimization algorithm for optimal structural design. The probability of failure is calculated considering excessive base displacement, superstructure inter-storey drifts, member stress ratios and absolute accelerations of floors of the isolated building as failure events. The behavior of rubber bearing isolators is modeled using nonlinear hysteretic model and the variability of future earthquakes is modeled by applying a probabilistic approach. The effects of pulse component of stochastic near-fault ground motions, fixity-factor of semi-rigid beam-to-column connections, values of isolator parameters, earthquake magnitude and epicentral distance on the performance and safety of semi-rigidly connected base-isolated steel framed buildings are studied. Suitable RBDO examples are solved to illustrate the results of investigations.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2006년도 정기 학술대회 논문집
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• pp.857-864
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• 2006

Due to the difficulties in numerical generation of random fields that satisfy not only the probabilistic distribution but the spectral characteristics as well. it is relatively hard to find an exact response variability of a structural response with a specific random field which has its features in the spatial and spectral domains. In this study. focusing on the fact that the random field assumes a constant over the domain under consideration when the correlation distance tends to infinity, a semi-theoretical solution of response variability is proposed for in-plane and plate bending structures. In this procedure, the probability density function is used directly resulting in a semi-exact solution for the random field in the state of random variable. It is particularly noteworthy that the proposed methodology provides response variability for virtually any type of probability density functions.