• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.7
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• pp.759-768
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• 2012

This paper proposes a method to determine the elastic follow-up factors for the $C(t)$-integral under secondary stress. The rate of creep crack growth for transient creep is correlated with the $C(t)$-integral. Elastic follow-up behavior, which occurs in structures under secondary loading, prevents a relaxation of stress during transient creep. Thus, both the values of $C(t)$ and creep crack growth increase as increasing elastic follow-up. An estimation solution for $C(t)$ was proposed by Ainsworth and Dean based on the reference stress method. To predict the value of $C(t)$ using this solution, an independent method to determine the elastic follow-up factors for cracked bodies is needed. This paper proposed that the elastic follow-up factors for $C(t)$ can be determined by elastic-plastic analyses using the plastic-creep analogy. Finite element analyses were performed to verify this method.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.7 no.1
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• pp.57-69
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• 1995

The development of a finite difference model for cross-shore sediment transport prediction in the surf tone due to the storm surge event is presented in this paper. Using the inhomogeneous diffusion equation with moving boundaries. the present numerical model is found to be robust and efficient and does not possess a number of restrictions imposed in Kriebel and Dean's(1985) numerical model. Our numerical model is validated through comparison with the analytical solution. the data of a large-scale experiment and the field data of Hurricane Eloise. The Present model if able to predict the averaged volumetric erosion rate of a beach due to the time-varying real storm surge hydrographs and satisfies the conservation of sediment between eroded volume in the onshore region and deposited volume in the offshore region. In addition. the present model is able to reasonably predict the recession of a beach with wide berm and dune. and can describe the change of a breaking point by the offshore deposition. From the sensitivity analysis or the present numerical model with various input parameters, it is concluded that the present numerical model is able to analyze the beach change in a reliable manner including the effects of different sizes of sediments.

• Journal for History of Mathematics
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• v.1 no.1
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• pp.33-67
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• 1984

Muslim의 수학은 천문학과 마찬가지로 종교적 필요성이 있었다. 기하학적 지식은 매일 예배하는 Mecca의 방향을 정하기 위한 것이었다면, 산술과 대수는 주로 제일을 계산하기 위해 필요했다. Muslim의 수학은 결국 종교적 욕구를 충족시키는데 끝없을 뿐 과학 일반에의 응용은 없었으나, 전 인류에게 그 지식을 보급시킴으로서 수학사상 중요한 위치를 차지한다. Muslim의 문화가 일어나는 시대는 10세기로 생각할 수 있으며, 특히 이 시기에 학술연구가 시작됐다. 11세기는 Muslim의 황금시기이며 실험과 이론의 두분야에서 눈부신 발달이 있었다. 12세기에는 퇴락의 과정을 밝으면서도 그 문화적 유산은 서구세계에 넘겼다. 본 눈문에서는 산술, 대수, 삼각법을 중심으로 이들 학문의 형성과정과 지식의 전달과정을 살핀다.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2001.05a
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• pp.487-488
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• 2001

저서동물은 생태계 내에서 여러 가지 중요한 역할을 수행하고 있다. 저서생물은 유용저서어류나 유용 무척추동물의 먹이로서 매우 중요한 부분을 차지하고 있다. (Dean, 1973: McIntyre, 1978; McIntyre and Eleftherion,1968) 따라서 저서동물은 먹이생물로서 저서어류의 성장효율과 생산에 큰 영향을 미치는 요인이 될 수가 있다(Mills,1975). 또한 저서동물은 부식질 먹이 연쇄를 통하여 퇴적물내의 영양염을 변화 시킬 뿐만 아니라 최적물 내에서 수괴로의 영양염 재순환의 중요한 매개자 역할을 한다. (중략)

• The Korean Journal of Applied Statistics
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• v.31 no.6
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• pp.721-732
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• 2018

Latent class analysis (LCA) is an important tool to explore unseen latent groups in multivariate categorical data. In practice, it is important to select a suitable set of variables because the inclusion of too many variables in the model makes the model complicated and reduces the accuracy of the parameter estimates. Dean and Raftery (Annals of the Institute of Statistical Mathematics, 62, 11-35, 2010) proposed a headlong search algorithm based on Bayesian information criteria values to choose meaningful variables for LCA. In this paper, we propose a new variable selection procedure for LCA by utilizing posterior probabilities obtained from each fitted model. We propose a new statistic to measure the adequacy of LCA and develop a variable selection procedure. The effectiveness of the proposed method is also presented through some numerical studies.

• Journal of the Korean Society for Nondestructive Testing
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• v.31 no.5
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• pp.479-486
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• 2011

In image-based CFD modeling of carotid bifurcation hemodynamics, it is often not possible (or at least not convenient) to impose measured velocity profiles at the common carotid artery inlet. Instead, fully-developed velocity profiles are usually imposed based on measured flow rates. However, some studies reported a pronounced influence of inflow boundary conditions that were based on actual velocity profiles measured by magnetic resonance imaging which showing the unusual presence of a high velocity band in the middle of the vessel during early diastole inconsistent with a Dean-type velocity profile. We demonstrated that those velocity profiles were induced by the presence of modest secondary curvature of the inlet and set about to test whether such more "realistic" velocity profiles might indeed have a more pronounced influence on the carotid bifurcation hemodynamics. We found that inlet boundary condition with axisymmetric fully-developed velocity profile(Womersley flow) is reasonable as long as sufficient CCA inlet length of realistic geometry is applied.

• Geotechnical Engineering
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• v.12 no.3
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• pp.63-72
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• 1996

Plate anchors are often used for various types of offshore construction and maintenance works. When the plates are embedded in soft clay and subjected to sustanined allowable loads, creep may develop. This paper presents some results from laboratory model test designed to study the creep effect that develops with time for a shallow circular anchor subjected to sustained net loads that are less than the net ultimate uplift capacity. Based on the model test results, relationships among the net load, the rate of strain, and time are developed.

• Geotechnical Engineering
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• v.14 no.3
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• pp.63-72
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• 1998

Laboratory model test results for ultimate uplift capacity of horizontal circular anchors embedded in soft clay overlain by dense sand are presented. The effect of the critical embedment ratio on the thickness of the clay layer was evalyated. An approximate preocedure for estimating the net ultimate capacity is presented.

• Proceedings of the Membrane Society of Korea Conference
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• 1997.04a
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• pp.87-109
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• 1997

Reverse osmosis(R/O), ultrafiltration(UF) and microfiltration (MF) processes are widely used for water treatment. In the seminar, characteristics of typical membrane modules including tubular, hollow fiber, plate and frame and spiral wound types will be discussed in detail. The design methods based on hydrodynamics for hollow fiber and spiral wound modules will be introduced analytically. Concentration polarization (CP) and membrane fouling mechnism as well as the techniques for CP reduction will be handled. The CP control techniques contain chemically modified membrane surface, pretreatment of feed water, operation of low trans-membrane pressure, chemical or physical cleaning methods and artificial production of various fluid turbulences near the membrane surface, etc. In especially, the recent commercial membrane modules for CP control including module rotation, vibration and Taylor or Dean vortex system will be introduced and discussed in detail.

• 한국방재학회:학술대회논문집
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• 2010.02a
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• pp.109.1-109.1
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• 2010

파랑의 거동을 해석하기 위해 몇 십 년 동안 많은 연구들이 진행되었다. 그 중에서 해석적인 방법으로 축대칭 지형과 같은 간단한 지형을 지나는 파랑의 변형을 예측하는 것은 실험에 의한 방법에 비해 시간적, 비용적인 측면에서 유리하다. 또한 수치기법에 의한 오차를 발생하지 않기 때문에 보다 정확한 해를 구할 수 있다는 장점이 있다. 그러나 단일주기, 단일방향에 대한 가정을 거치기 때문에 실제 해역에서의 복잡한 파랑 변형을 예측하는데 한계가 있다. 고유함수전개법을 축 대칭 지형에 적용시키는 연구는 Bender and Dean(2005)에 의해 제시되었으며, 본 연구에서는 이것을 발전시켜 다방향 불규칙파에 대한 파랑 변형을 모의하였다. 그리고 결과를 단일주기에 의한 규칙파와 비교하여 그 특성을 알아보았다.