• 한국수자원학회논문집
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• 제39권2호
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• pp.99-108
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• 2006

부유사의 거동을 나타내는 데는 이송-확산 방정식이나 이 방정식을 간략화한 식들이 이용된다 이 방정식은 여러 가지 가정하에서 유도되었으나, 이러한 가정에 대해서는 심도있는 검토가 되지 못한 상태에 있다 그 이유는 난류의 측정 자체가 매우 힘들며, 유사가 혼합된 흐름의 경우 물과 유사의 속도를 구별해서 측정하기 매우 힘들기 때문이다. 본 연구는 입자 영상 유속계(PIV, Particle Image Velocimeoy)의 일종인 입자 추적 유속계(PTV, Particle Tracking Velocimetry)를 이용하여 개수로 난류에서 물과 유사의 속도를 측정하는 실험적 연구이다. 측정 결과, 하상에서 어느 정도 떨어진 영역에서는 유사의 속도가 물보다 느린 경향을 보였다. 이 속도 지체의 양은 본 연구의 경우 평균 유속 의 약 $5\%$ 정도였으며, 속도 지체가 최대에 이르는 지점은 $g/h\approx0.05\;(g^{+}=30\~50)$정도인 것으로 나타났다. 유사 입자가 물보다 느리게 이동하는 것은 전적으로 유사의 비중이 물보다 크기 때문으로 보인다. 반면, 하상에 근접한 점성 저층에서는 오히려 유사 입자의 속도가 물보다 빠르게 나타났으며, 이것은 물은 고체 경계면에서 점착 조건에 종속되는 데 반하여, 유사 입자는 점성의 영향을 받지 않기 때문으로 보인다.

• 한국항해항만학회지
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• 제29권7호
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• pp.627-634
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• 2005

Gunsan-Janghang Harbor is located at the mouth of Gum River, on the central west coast of Korea The harbor and coastal boundaries are protected from the effects of the open ocean by natural coastal islands and shoals due to depositions from the river, and two breakwaters. The navigation channel commences at the gap formed by the outer breakwater and extends through a bay via a long channel formed by an isolated jetty. For better understanding and analysis of wave transformation process where a wide coastline changes appear due to on-going reclamation works, we applied the spectral wave model including wind effect to the related site, together with the energy balance models. This paper summarizes comparisons of coastal responses predicted by several numerical wave predictions obtained at the coastal waters near Gunsan-Janghang Harbor. Field and numerical model investigations were initially conducted for the original navigation channel management project. We hope to contribute from this study that coastal engineers are able to use safety the numerical models in the area of port and navigational channel design.

• 한국해안해양공학회지
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• 제4권2호
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• pp.130-137
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• 1992

전회의 인천만 2차원 모형(최, 1950)을 개선시켜 개방경계에 8개분조를 부여함으로서 만전체에 조석을 실시간예보할 수 있는 체계구성을 위한 시도를 하였다. 기상영향이 없는 기간에 대한 모형의 hindcast 결과는 치안관측치와 전반적인 일치를 보였다. 또한 인천만 모형과 1차원 한강모형을 동적 연결하여 한 모형체계로서 개선시켜 인천만 조석의 한강으로의 전파를 산정하게 하였다. 이 모형에 의해 1990년 9월의 대홍수를 산정하였으며 추후의 모형개선에 관연된 토의를 서술하였다.

• 복식문화연구
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• 제11권1호
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• pp.118-134
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• 2003

The first purpose of this study is to take a better look it the background of Formalism art in the cultural society and to examine the aesthetic value of the formative arts of formalism architecture that are ail basically founded upon the study of Formalism. Secondly, it analyzes the aesthetic value of Formalism Art to Wear, Which can be explained as a mixture of art and fashion, by investigate to the features of art history. The results are as follows; First, Formalism Art to Wear of Simultaneity does not represent continuance but simultaneous. In other words. inside the same time and place of dimension, events art visualized without transformation. Secondly, formalism Art to Wear of Geometrical Aesthetics deals with a purely genuine atmosphere that pursues absolute perfection, composed abstract of geometrical shapes. Thirdly, Fomarlism Art to Wear of Deformation breaks analysis from balance and symmetry showing extreme transformation nil new vitality. Fourthly, Formalism Art to Wear of Space Extension experiments with post-corporeality. Post-corporeality centers the human body extension that is open to various boundaries of implosion and electronic technologies, providing us with a new Cyborg of the digital body.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집E
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• pp.506-511
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• 2001

This paper presents how redevelopment of the boundary layer in a backward-facing step flow is affected by boundary conditions imposed on velocity at the inlet, top and exit of the flow. A two-dimensional, laminar, incompressible flow over a backward-facing step with an open top boundary has been computed by using numerical methods of second-order time and spatial accuracy and a fractional-step method that guarantees a divergence-free velocity field at all time. The inlet velocity profile above the step is of Blasius type. Along the top boundary, shear-tree and Dirichlet conditions on the streamwise velocity were considered and at the exit fully-developed and convective boundary conditions were examined. (The vertical velocity at all boundaries were assumed to be zero explicitly or implicitly.) From the computed flow fields, the reattachment on the bottom side of shear layer separated from the tip of the step and succeeding redevelopment of the boundary layer were investigated.

• 한국해양환경ㆍ에너지학회지
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• 제13권4호
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• pp.234-240
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• 2010

연안개발로 인해 발생하는 해양환경 변화를 정확히 예측하여 해양환경을 효율적으로 관리하기 위해서는 정확한 조위 및 조류 분포에 관한 자료의 확보가 필수적이다. 그러나 현재 대부분의 환경영향평가에서는 조석 수치모의에서 제한된 조석분조 만을 사용하여 조위와 조류분포를 예측하여 많은 분조의 합성에 의해 발생되는 실제 조석현상을 정확하게 계산하지 못하고 있으며, 이로 인해 환경영향평가에 오류가 발생하고 있다. 본 연구에서는 제한된 분조의외해 개방경계에서 조화상수를 가지고도 연안에서 관측된 조위자료를 활용하여 실시간으로 정확하게 조위 및 조류 분포를 예측할 수 있는 방법을 제안하였다. 4개 분조에 의한 조위와 38개 분조에 의한 조차의 비 그리고 모의조차와 관측조차의 비를 가지고 보정한 조위 예측결과는 관측조위와 잘 일치하였다.

• 대한수학회보
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• 제48권4호
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• pp.791-812
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• 2011

This is a survey on American options. An American option allows its owner the privilege of early exercise, whereas a European option can be exercised only at expiration. Because of this early exercise privilege American option pricing involves an optimal stopping problem; the price of an American option is given as a free boundary value problem associated with a Black-Scholes type partial differential equation. Up until now there is no simple closed-form solution to the problem, but there have been a variety of approaches which contribute to the understanding of the properties of the price and the early exercise boundary. These approaches typically provide numerical or approximate analytic methods to find the price and the boundary. Topics included in this survey are early approaches(trees, finite difference schemes, and quasi-analytic methods), an analytic method of lines and randomization, a homotopy method, analytic approximation of early exercise boundaries, Monte Carlo methods, and relatively recent topics such as model uncertainty, backward stochastic differential equations, and real options. We also provide open problems whose answers are expected to contribute to American option pricing.

• Communications for Statistical Applications and Methods
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• 제25권2호
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• pp.131-157
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• 2018

We propose a robust event date model to estimate the date of a target event by a combination of individual dates obtained from archaeological artifacts assumed to be contemporaneous. These dates are affected by errors of different types: laboratory and calibration curve errors, irreducible errors related to contaminations, and taphonomic disturbances, hence the possible presence of outliers. Modeling based on a hierarchical Bayesian statistical approach provides a simple way to automatically penalize outlying data without having to remove them from the dataset. Prior information on individual irreducible errors is introduced using a uniform shrinkage density with minimal assumptions about Bayesian parameters. We show that the event date model is more robust than models implemented in BCal or OxCal, although it generally yields less precise credibility intervals. The model is extended in the case of stratigraphic sequences that involve several events with temporal order constraints (relative dating), or with duration, hiatus constraints. Calculations are based on Markov chain Monte Carlo (MCMC) numerical techniques and can be performed using ChronoModel software which is freeware, open source and cross-platform. Features of the software are presented in Vibet et al. (ChronoModel v1.5 user's manual, 2016). We finally compare our prior on event dates implemented in the ChronoModel with the prior in BCal and OxCal which involves supplementary parameters defined as boundaries to phases or sequences.

• 한국과학교육학회지
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• 제32권3호
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• pp.541-554
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• 2012

With an emphasis on scientific literary, science education has again became closer to the interests and needs of people and sometimes expands its scope beyond the boundaries of school and the curriculum. Science educators often claim that its historical roots can be traced back to the movements of General Science and Science and Citizenship during the 1920s-40s. This study attempts to re-interpret the historical meanings of the Mechanics' Institute Movement (MIM) from the perspectives of science education. In doing so, this study first introduces the process of the emergence of MIM with a focus on its founder, George Birkbeck, and the Andersonian Institute where evening science classes began to be open to skilled workers. Then the overview of MIM is described, with examples drawn from the London Mechanics' Institute and the Manchester Mechanics' Institute. In discussing science teaching of MIM, the details taken from various mechanics' institutions are examined in terms of why, what, and how to teach sciences. This study argues that the MIM was a unique social phenomenon in which science could respond to the needs of skilled workers through education, providing science learning opportunities which were otherwise unavailable and that the MIM shared many similarities with current practice of science education, moving towards a wider career perspectives, cross-subject, community-based, and informed citizenship.

• 복식
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• 제62권3호
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• pp.96-111
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• 2012

This study is to analyze fashion phenomenon according to the concept of the characteristics of freewheeling to explain the de-constructive, eclectic, avant-garde tendencies in Contemporary Fashion. This study is to elicit the aesthetic characteristics through 400 pieces of visual data analysis from 2001S/S to 2011F/W that have the characteristics of freewheeling, nontechnical experiments do away with the classical form. The oriental ideas include the thoughts of different tastes that break the stereotypes according to the Western values and the pursuit of unconventional beauty. These also insist that everything in the world including human-being, nature and creation is not divided into two equal parts, and even beauty and ugliness originated from one. This study is to find the possibility of interpreting oriental aesthetics with open concepts that transcends the boundaries of full availability, unlike the Western values that accommodate the relative concept of the pursuit of diversity. Therefore, integrated and systematic approaches of oriental aesthetics that place much value on the coexistence of antithetic concepts are needed to understand the ambiguity of complexity and diversity in Contemporary fashion design.