• 대한설비공학회지:설비저널
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• 제17권5호
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• pp.590-597
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• 1988

Characteristics of flow regime transitions in inclined upwards gas-liquid two-phase flow have been investigated based upon a statistical analysis of instantaneous pressure drop curves through an orifice. The probability density functions of the curves indicate distinct patterns depending upon two-phase flow regime, which are very similar to those of horizontal two-phase. The dimensionless intensity of fluctuations of the pressure drops sharply change as the flow transitions such as plug-slug, pseudo slug-slug and annular-slug take place. The effects of inclination angle on the flow regime transitions have been also investigated. The results show that the method to identify the flow pattern based upon the statistical analysis of instantaneous pressure drops is suitable for inclined flow as well as horizontal flow.

• Structural Engineering and Mechanics
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• 제46권6호
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• pp.755-773
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• 2013

One of the main requirements of the seismic design codes must be its easy application by structural engineers. The use of practically-applicable models or simplified models as single-degree-of-freedom (SDOF) systems is a good alternative to achieve this condition. In this study, deterministic and probabilistic response transformation factors are obtained to evaluate the response in terms of maximum ductility and maximum interstory drifts of multi-degree-of-freedom (MDOF) systems based on the response of equivalent SDOF systems. For this aim, five steel frames designed with the Mexican City Building Code (MCBC) as well as their corresponding equivalent SDOF systems (which represent the characteristics of the frames) are analyzed. Both structural systems are subjected to ground motions records. For the MDOF and the simplified systems, incremental dynamic analyses IDAs are developed in first place, then, structural demand hazard curves are obtained. The ratio between the IDAs curves corresponding to the MDOF systems and the curves corresponding to the simplified models are used to obtain deterministic response transformation factors. On the other hand, demand hazard curves are used to calculate probabilistic response transformation factors. It was found that both approaches give place to similar results.

• Asian Pacific Journal of Cancer Prevention
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• 제16권14호
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• pp.5655-5661
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• 2015

Purpose: To assess the role of two adjuvant chemotherapy regimens, anthracycline-based and CMF on disease free survival and overall survival breast cancer patients by meta-analysis approach in Eastern Mediterranean and Asian countries to determine which is more effective and evaluate the appropriateness and efficiency of two different proposed statistical models. Materials and Methods: Survival curves were digitized and the survival proportions and times were extracted and modeled to appropriate covariates by two multivariate mixed effects models. Studies which reported disease free survival and overall survival curves for anthracycline-based or CMF as adjuvant chemotherapy that were published in English in the Eastern Mediterranean region and Asia were included in this systematic review. The two transformations of survival probabilities (Ln (-Ln(S)) and Ln(S/ (1-S))) as dependent variables were modeled by a multivariate mixed model to same covariates in order to have precise estimations with high power and appropriate interpretation of covariate effects. The analysis was carried out with SAS Proc MIXED and STATA software. Results: A total of 32 studies from the published literature were analysed, covering 4,092 patients who received anthracycline-based and 2,501 treated with CMF for the disease free survival and in order to analyze the overall survival, 13 studies reported the overall survival curves in which 2,050 cases were treated with anthracycline-based and 1,282 with CMF regimens. Conclusions: The findings illustrated that the model with dependent variable Ln (-Ln(S)) had more precise estimations of the covariate effects and showed significant difference between the effects of two adjuvant chemotherapy regimens. Anthracycline-based treatment gave better disease free survival and overall survival. As an IPD meta-analysis in the Italy the results of Angelo et al in 2011 also confirmed that anthracycline-based regimens were more effective for survival of breast cancer patients. The findings of Zare et al 2012 on disease free survival curves in Asia also provided similar evidence.

• 한국전산구조공학회논문집
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• 제27권6호
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• pp.509-516
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• 2014

일반적으로 지진취약도를 평가할 때 사용되는 해석방법 중 하나인 역량스펙트럼 방법은 증분동적해석에 비해 해석의 정확성이 떨어지는 제한점이 있다. 본 연구에서는 증분동적해석이 가장 정확도가 높은 해석기법이라는 점에 착안하여 증분동적해석을 이용한 지진취약도 곡선의 도출과정을 제안하였다. 타당성 비교를 위하여 역량스펙트럼 방법과 제안된 방법으로 도출한 취약도 곡선을 비교하여 두 해석기법에 의한 지진취약도 곡선의 경향을 분석하였다. 그 결과 Slight damage와 Moderate damage의 경우 두 해석방법이 유사한 곡선 경향을 보이나 Extensive damage와 Complete damage의 경우에는 IDA방법에 의한 곡선이 더 가파른 경향을 보였다. 이는 구조물의 거동을 이상화하여 극한점 이후 구조물의 저항 강도가 떨어지지 않는다고 가정하는 역량스펙트럼 방법의 영향을 받는 것으로 사료된다.

• 대한토목학회논문집
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• 제26권5B호
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• pp.519-528
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• 2006

수공구조물 설계에서 가장 중요한 일은 설계홍수량을 결정하는 것이다. 따라서 설계홍수량 산정에 영향을 미치는 여러 가지 요소 중 적절한 설계 강우의 시간분포 방법을 선택하는 것은 중요한 일이다. 설계 강우의 시간분포 방법에는 여러 가지 방법들이 있으며, 그 중에서 최근 첨두홍수량 산정을 위한 설계 강우의 시간분포 방법에 많이 이용하고 있는 Huff의 4분위법은 6시간 이상의 무강우시간을 갖는 강우사상을 자료로 이용, 분석하여 설계 강우의 시간분포 방법을 제시한 방법이다. 본 연구에서는 Huff의 4분위법에서 이용한 자료와 달리 1961년부터 2004년까지 서울지역 강우 관측자료 중 지속기간별 연 최대치 강우자료를 이용하여 강우의 시간분포 특성을 분석하고 이전의 연구 결과와 비교하였다. 각각의 결과에 대하여 비교한 결과 서울지역의 경우 연 최대치 강우의 지속기간이 짧을 경우 무차원 누가곡선이 Huff의 4분위법 결과에 비하여 비교적 완만하게 나타났으며, 지속기간이 점점 증대될수록 무차원 누가곡선은 Huff의 4분위법 결과와 유사하게 나타났다.

• Journal of applied mathematics & informatics
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• 제17권1_2_3호
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• pp.39-48
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• 2005

A convex region covers a family of curves if it contains a congruent copy of each curve in the family, and a 'worm problem' for that family is to find the convex region of smallest area. In this paper, we find the smallest triangular cover of any prescribed shape for the family S of all triangles of diameter 1.

• 대한수학회지
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• 제52권2호
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• pp.225-237
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• 2015

In this article, we show that many of the genera that Giulietti and Fanali obtained from subfields of the GK curve can be obtained by using similar techniques used by Garcia, Stichtenoth and Xing. In the meantime, we obtain some new genera from the subfields of GK and generalized GK function fields.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2009년도 춘계 학술대회 제21권1호
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• pp.531-532
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• 2009

이 논문에서는 섬유 분포 특성을 반영하여 균열 간격을 계산할 수 있는 수식을 유도하고, 이를 바탕으로 ECC의 1축 인장 거동을 예측하였다. 예측 결과와 실험 결과는 약 10% 오차가 발생하였다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 하계종합학술대회 논문집(2)
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• pp.169-172
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• 2001

We have investigated the mechanical deformation of carbon nanotube using TBMD(tight-binding molecular dynamics) simulation. We have studied four carbon nanotubes, armchair (6, 6), (7, 7), (8, 8), and (9, 9) carbon nanotubes whose length were same. As a result of study, we have known that the nanotube's yield force increases with incresing their diameter. It is similar between (6, 6) and (8, 8) CNT's force-strain curves. Also force-strain curve between (7,7) and (9, 9) CNTs are nearly same.

• Bulletin of the Korean Chemical Society
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• 제24권2호
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• pp.219-221
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• 2003

Rabi oscillation between bound states of a single potential is well known. However the corresponding formula between the states of two different potentials has not been obtained yet. In this work, we derive Rabi formula between the states of a coupled harmonic oscillator which may be used as a simple model for the electron transfer. The expression is similar to typical Rabi formula for a single potential. This result may be used to describe transitions between coupled diabatic potential curves.