• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.19 no.1
• /
• pp.38-44
• /
• 2007

Using the mathematical model suggested by Bennet et al.(1992), the reflection and transmission coefficients by a circular pile breakwater has been investigated in the framework of potential theory. Flow separation due to sudden contraction and expansion is generated and is the main cause of significant energy loss. Therefore, evaluation of exact energy loss coefficient is critical to enhance the reliability of mathematical model. To obtain the energy loss coefficient, 2-dimensional turbulent flow is analyzed using the FLUENT commercial code. The energy loss coefficient can be obtained from the pressure difference between upstream and downstream. Energy loss coefficient is the function of porosity and the relation equation between them is suggested throughout the curve fitting processing. To validated the suggested relation, comparison between the analytical results and the experimental results is made for four different porosities with good agreement.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.23 no.7
• /
• pp.933-940
• /
• 2017

Draught and trim conditions are highly related to the loading condition of a vessel and are important factors in predicting ship manoeuverability. This paper estimates hydrodynamic coefficients from sea trial measurements with three different trim and draught conditions. A mathematical optimization method for system identification was applied to estimate the forces and moment acting on the hull. Also, fast time simulation software based on the Rheinmetall Defense model was applied to the whole estimation process, and a 4,500 Twenty-foot Equivalent Unit (TEU) class container carrier was chosen to collect sets of measurement data. Simulation results using both optimized coefficients and newly-calculated coefficients for validation agreed well with benchmark data. The results show mathematical optimization using sea measurement data enables hydrodynamic coefficients to be estimated more simply.

• The Mathematical Education
• /
• v.62 no.3
• /
• pp.435-455
• /
• 2023

This study primarily focused on the development of an Explainable Artificial Intelligence (XAI) model to discern and analyze papers with significant impact in the field of mathematics education. To achieve this, meta-information from 29 domestic and international mathematics education journals was utilized to construct a comprehensive academic research network in mathematics education. This academic network was built by integrating five sub-networks: 'paper and its citation network', 'paper and author network', 'paper and journal network', 'co-authorship network', and 'author and affiliation network'. The Random Forest machine learning model was employed to evaluate the impact of individual papers within the mathematics education research network. The SHAP, an XAI model, was used to analyze the reasons behind the AI's assessment of impactful papers. Key features identified for determining impactful papers in the field of mathematics education through the XAI included 'paper network PageRank', 'changes in citations per paper', 'total citations', 'changes in the author's h-index', and 'citations per paper of the journal'. It became evident that papers, authors, and journals play significant roles when evaluating individual papers. When analyzing and comparing domestic and international mathematics education research, variations in these discernment patterns were observed. Notably, the significance of 'co-authorship network PageRank' was emphasized in domestic mathematics education research. The XAI model proposed in this study serves as a tool for determining the impact of papers using AI, providing researchers with strategic direction when writing papers. For instance, expanding the paper network, presenting at academic conferences, and activating the author network through co-authorship were identified as major elements enhancing the impact of a paper. Based on these findings, researchers can have a clear understanding of how their work is perceived and evaluated in academia and identify the key factors influencing these evaluations. This study offers a novel approach to evaluating the impact of mathematics education papers using an explainable AI model, traditionally a process that consumed significant time and resources. This approach not only presents a new paradigm that can be applied to evaluations in various academic fields beyond mathematics education but also is expected to substantially enhance the efficiency and effectiveness of research activities.

• Communications of Mathematical Education
• /
• v.31 no.3
• /
• pp.349-366
• /
• 2017

The 2015 revised curriculum is an integrated curriculum that reflects national and societal needs to foster creative convergent talent in the school curriculum. Along with these changes, the Ministry of Education introduced a system to change the major from 2017 to the fourth year of university. Therefore, each university should prepare to reflect the curriculum and institutional change before welcoming students who have completed the 2015 revised curriculum. The university needs to study the countermeasures for implementing the 2015 revised curriculum and expanding the period of major change when preparing the curriculum and contents of the calculus courses that freshmen take. Handong University has been studying the operation methods of new students who want to decide their major at the first grade, such as operating calculus courses at various levels and allocating appropriate proportions of calculus for preliminary examinations. This case is similar to the basic purpose of the revised curriculum in 2015, so it can suggest implications for the operation of the university calculus class after the curriculum revision. In this paper, we have analyzed the results of the recent freshman mathematics test for the recent 5 years and the students' calculus grades and compared them with the contents of the calculus curriculum operated by Handong University and the 2015 revised higher mathematics curriculum. As a result, we proposed five classes of calculus suitable for college major and it was found that the calculus curriculum should include the missing quadratic method in the 2015 revised curriculum.

• Journal of Elementary Mathematics Education in Korea
• /
• v.23 no.4
• /
• pp.437-457
• /
• 2019

In this study, we analyzed how the content and achievement criteria of the Geometry domain of Korean elementary school mathematics curriculum have changed. To this end, based on the analysis framework based on the 2015 revised curriculum, the achievement standards for each period were classified into continuous, extinct, and additional types, and their characteristics were examined. In the domain of Geometry, continuous achievement standards accounted for 51% of the total, and there were many achievement standards that remained unchanged in grade and domain. The extinctive achievement standard is 20.4% of the total, and the mathematics contents that were rapidly introduced due to the modernization of mathematics in the 3rd curriculum were eliminated the most from the 4th curriculum, and after the 7th curriculum, With the introduction of staged curriculum and the system of school year group, the contents of learning were either integrated or moved to middle school. The additional achievement standard was 28.6% of the total, and the achievement standard was added the most with the introduction of spatial sensory development in the 7th curriculum. The GAct that the additivel achievement standard is more than the extinction achievement standard in the Geometry domain is the result of the efforts to actively introduce the geometric contents appropriate to the times despite the great flow of curriculum revision of the curriculum reduction. It is hoped that the results of these studies will be used as basic data in the formation of new achievement standards in future curriculum development.

• Review of KIISC
• /
• v.28 no.2
• /
• pp.61-77
• /
• 2018

차분 프라이버시는 통계 데이터베이스 상에서 수행되는 질의 결과에 의한 개인정보 추론을 방지하기 위한 수학적 모델로써 2006년 Dwork에 의해 처음 소개된 이후로 통계 데이터에 대한 프라이버 보호의 표준으로 자리잡고 있다. 차분 프라이버시는 데이터의 삽입/삭제 또는 변형에 의한 질의 결과의 변화량을 일정 수준 이하로 유지함으로써 정보 노출을 제한하는 개념이다. 이를 구현하기 위해 메커니즘 상의 연구(라플라스 메커니즘, 익스퍼넨셜 메커니즘)와 다양한 데이터 분석 환경(히스토그램, 회귀 분석, 의사 결정 트리, 연관 관계 추론, 클러스터링, 딥러닝 등)에 차분 프라이버시를 적용하는 연구들이 수행되어 왔다. 본 논문에서는 처음 Dwork에 의해 제안되었을 때의 차분 프라이버시 개념에 대한 이해부터 오늘날 애플 및 구글에서 차분 프라이버시가 적용되고 있는 수준에 대한 연구들의 진행 상황과 앞으로의 연구 주제에 대해 소개한다.

• 기계와재료
• /
• v.24 no.2
• /
• pp.80-93
• /
• 2012

본 연구는 5,000PS급 선박용 SCR 촉매시스템에 관한 내부 유동특성을 전산유체역학(CFD)을 통해 예측하고 설계에 반영하기 위한 기초를 확보하기 위함이다. 따라서 SCR 촉매반응기 내부 유동특성을 수치해석하기 위한 기법을 소개하였고, 촉매 Cell에 대한 수학적 모델링을 제시한 후 SCR 촉매시스템에서 NOx를 환원시켜 주는 촉매담체에 대한 압력강하를 실험과 수치해석을 통해 비교하였다. 그 결과 수치해석 결과가 실험에 매우 근접함을 확인할 수 있었다. SCR 촉매반응기에 대한 유동특성을 수치해석을 수행하여 각 지점에 대한 압력과 속도분포를 확인하였다. 또한 촉매 담체로 배기가스가 유입되는 입구부의 유동균일도를 예측하기 위해 Inlet pipe의 $90^{\circ}$ 각도에서 유입길이를 변화시켜 수치해석을 수행하였다. 그 결과 각도와 길이에 영향을 받는 것으로 나타났다.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.16 no.11
• /
• pp.1194-1200
• /
• 1991

The FEM is a computer-aided mathematical technique for obtaining approximate solution to the differential equations. The pointwise convergence defines the relationship between the mesh size and the tolerance. This will play an important role in improving quality of finite element approximate solution. In the paper. We evaluate the convergence on a certain unknown point with a 1-irregular mesh refinement and spectral order enrichment. This means that the degree of freedom is minimized within a tolerance.

• Proceedings of the Safety Management and Science Conference
• /
• 2013.04a
• /
• pp.173-177
• /
• 2013

공급사슬관리(Supply Chain Management)의 목적은 공급사슬에서 발생하는 재고 및 운송에 관련한 비용을 최소화하는 것이다. 여기서 발생하는 비용은 여러 변수에 의해 결정되기 때문에 공급망 전체를 하나의 시스템으로 보고 모델링하여 분석할 필요성이 있다. 여러 구성요소들을 시간의 흐름에 따라 변화하는 모습을 분석하기 위해 수학적 접근방법을 사용하는 것 보다 시뮬레이션 방법을 사용해 모델링하는 것이 더 효과적이다. 따라서 본 연구에서는 중국의 H자동차의 조달물류의 문제점을 파악하고 이를 개선하기 위한 방안을 마련하기 위해 시뮬레이션 방법을 활용하여 조달물류의 최적 배송주기를 도출하고, 재고관리의 문제점을 개선 하고자 한다.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2008.04a
• /
• pp.453-456
• /
• 2008

This study is underway to develop a prediction model for formwork pressure exerted by self-compacting concrete(SCC). Three major mechanisms related to formwork evolution over time were found, and mathematical modelling of each mechanism was made. A calculation method for real formwork pressure by using the mathematical formulae was also established. To verify predictive capability of the prediction model, a parametric study on parameters used in the model was performed. It was confirmed that the proposed model include the essential parameters that can simulate the real formwork pressure evolution over time.