• Composites Research
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• v.19 no.1
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• pp.1-8
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• 2006

Prediction of damage caused by low-velocity impact in laminated composite plate is an important problem faced by designers using composites. Not only the inplane stresses but also the interlaminar normal and shear stresses playa role in estimating the damage caused. But it is well known that the conventional approach based on the homogenization has the limit in description of damage. The work reported here is an effort in getting better predictions of dynamic behavior and damage in composite plate using DNS approach. In the DNS model, we discretize the composite plates through separate modeling of fiber and matrix for the local microscopic analysis. In the view of microscopic mechanics with DNS model, interlaminar stress behaviors in the inside of composite materials are investigated and compared with the results of the homogenized model which has been used in the conventional approach to impact analysis. Also the multiscale model based on DNS concept is developed in order to enhance the effectiveness of impact analysis, and we present the results of multiscale analysis considering micro and macro structures simultaneously.

• Journal of Korean Tunnelling and Underground Space Association
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• v.11 no.2
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• pp.151-162
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• 2009

This study proposes a new methodology for quantitative rock classification in unsampled rock zone, which occupies the most of tunnel design area. This methodology is to train an ANN (artificial neural network) by using results from a drilling investigation combined with electric resistivity survey in sampled zone, and then apply the trained ANN to making a prediction of grade of rock classification in unsampled zone. The prediction is made at the center point of a shifting window by using a number of electric resistivity values within the window as input reference information. The ANN training in this study was carried out by the RPROP (Resilient backpropagation) training algorithm and Early-Stopping method for achieving a generalized training. The proposed methodology is then applied to generate a rock grade distribution on a real tunnel site where drilling investigation and resistivity survey were undertaken. The result from the ANN based prediction is compared with one from a conventional kriging method. In the comparison, the proposed ANN method shows a better agreement with the electric resistivity distribution obtained by field survey. And it is also seen that the proposed method produces a more realistic and more understandable rock grade distribution.

• 한국공간정보시스템학회:학술대회논문집
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• 2007.06a
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• pp.395-400
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• 2007

본 연구의 목적은 측량성과의 체계적 품질관리, 측량성과 관리업무의 효율성 향상 및 비용절감을 위하여 측량성과의 전자납품 및 품질검사의 자동화 방안을 연구하는데 있다. 이를 위하여 측량성과의 품질관리 현황 및 작업규정을 분석하고, 측량성과의 전자납품 및 품질검사 자동화를 위한 기본방안을 제시하였다. 측량 성과품의 유형을 품질검사의 자동화 측면에 구분을 해보면, 첫째, 품질검사의 자동화가 불가능한 유형, 둘째, 포맷분석과 소프트웨어 개발을 통하여 자동화된 품질 검사가 가능한 유형, 셋째, 제도적인 보완을 통하여 자동화가 가능한 성과품 유형 등 세 가지 종류로 분류가 가능하다. 이러한 측량성과품의 품질검사업무의 자동화는 크게 단기간에 미시적으로 해야 할 사안들과 중 장기에 걸쳐 거시적으로 추진해야할 사안 등 두 가지 측면의 시각으로 접근해야 하며, 업무적인 측면, 제도적인 측면 및 정보기술적인 측면에서 종합적으로 검토되어야 할 것으로 판단된다.

• Journal of the Korean Geographical Society
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• v.39 no.4
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• pp.620-632
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• 2004

This paper tries to examine differences between geography classes taught by majored and non-majored teacher and to find problems in the latter case, tv observing four middle school geography classes in Seoul, from April to May 2003. The observation was fecund on (1) organization of a class (2) dialogue between teacher and students (3) strategy of explanation. In addition, the author conducted personal interviews with social studies teachers in the schools where the observations were made. The analyses of the observed classes were made by micro-ethnographic research method. Major findings of the observation and analysis are as follows. First, the transition from one topic to another topic was not smooth in the case of non-majored teacher class. Second, the questions that the non-majored teacher posed in the classroom played less significant role in keeping up the class in an organized fashion than those that the majored teacher posed. Third, the non-majored teacher focused on the concepts, terms and contents appeared in the textbook and simply tried to explain them, whereas the majored teacher demonstrated teaching methods such as comparing and contrasting cases to provide students with a more dynamic and comprehensive understanding on the topic they teamed. Fourth, the non-majored teacher used maps less frequently and less actively than the majored teacher. In addition, although the non-majored teachers are well aware of their problems in the class as a non-majored teacher, they think that the problems are inevitable in a given curriculum structure of social studies in Korea.

• Journal of Teachers' Pension
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• v.5
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• pp.219-241
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• 2020

연기연금제도는 연금 지급개시연령 도달 이후 일정 기간 연금수급을 포기하는 대신 급여에 일정액을 가산하여 지급하는 제도이다. 연기연금은 지급개시연령 도달 이전에 수급을 신청하면 일정액을 가산하여 차감하고 지급하는 조기연금과 상호보완적인 기능을 수행하며 유연은퇴(flexible retirement)의 주요한 축을 구성한다. 연기연금제도의 정책적 목적은 수급자별 다양한 재무적 상황에 따라 보다 유연한 은퇴설계와 노후소득 확충을 지원하는 제도적 장치를 마련하는 것이다. 하지만 현재 연기연금제도는 국민연금에는 시행되고 있으나 사학연금을 비롯한 직역연금에는 도입되지 않고 있다. 최근 공적연금간 급여규정 수렴화에도 불구하고 사학연금을 비롯한 직역연금에서 연기연금을 도입하지 않는 배경에는 공적연금간 급여 형평성 등 많은 쟁점사항들이 영향을 미치기 때문일 것이다. 하지만 이 연구는 그러한 기저의 논쟁에서 벗어나 제도의 재무적 특성 분석을 목적으로 한다. 분석자료는 연금수급을 위한 요건을 충족한 퇴직자 중 연금수급연령 미도달자로 이들 대기자 그룹의 미시자료를 이용해 연기연금 적용 시 제도의 총급여액 증가를 야기하지 않는 재정 중립적 증액률(plan-neutral deferral rate)을 산출하였다. 분석결과, 분석자료를 대상으로 한 산술적 증액률은 6.75%였으나 민감도 분석의 결과를 반영한 적정수준은 6% 이하일 것으로 사료된다. 이는 장기적 추정의 특성상 적용되는 가정변수 수준에 따라 변동폭이 클 뿐만 아니라 하위 구성집단간의 이질적 특성으로 산출되는 증액률의 편차가 크기 때문이다. 따라서 재정 안정성을 훼손하지 않기 위해서는 보수적 관점의 접근이 필수적이다. 연구의 구성은 크게 세 부분으로 II장에서는 소득활동관련 연금의 주요한 수단으로 연기연금의 제도적 필요성을 검토하고, III장에서는 실제 사학연금 가입자 자료를 이용해 재정 중립적 증액률을 산출하고 주요 변수별, 특성 집단별 증액률에 대한 분석결과 및 시사점을 기술하였다. IV장에서는 장기 재정안정성을 저해하지 않기 위해 적정 증액률 산정 시 추가적으로 고려해야 되는 재무적 관련사항을 기술하였다.

• Journal of Digital Convergence
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• v.17 no.1
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• pp.73-84
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• 2019

By a comparative study of the philosophical backgrounds of universal service in Korea and the US, this research finds that Korea has paid little attention to the relations between universal service and basic human rights even though it has rapidly and successfully implemented universal service of telephone and the internet services in the past. Based on this key finding, it reaches a conclusion that Korea should adopt a new approach in implementing universal service in the future, considering the goals and contributions to the improvement of the basic human rights of universal service because economic goals have been main drivers of the implementation of universal service so far in Korea, which is not appropriate and suitable for the information society that new telecom services are rapidly emerging.

• Education of Primary School Mathematics
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• v.21 no.4
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• pp.375-395
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• 2018

This study examines the influence of the bodily interaction with digital technology on meaning-making process in a mathematical activity. Increasing interest in the use of multi-touch dynamic digital technology has brought the movement of the body to the center of research focus in recent mathematics education literature. Thereby, we investigate the process in which the meaning of the density of rational numbers emerges around the bodily interaction on the multi-touch dynamic digital technology. We analyze a case of a small group of primary school students with microethnography. In the result, the students formed the higher level of meaning of the density, where the finger movement of zooming in-and-out played a crucial role throughout the meaning-maknig process.

• Journal of Digital Contents Society
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• v.13 no.4
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• pp.591-600
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• 2012

Variety media based on the digital technology have emerged from the beginning of the 21th century and have competed with the traditional media in the advertisement market. With the high dependency upon the advertisement market, the Korean media industry has the urgent demand to increase it's pie. Korea regulator allowed PPL and private representatives, which resulted in low outcome. This study analysed the decision factors for the advertising market with the cross-sectional microeconomic data for 28 countries in OECD. The service industry, tax and GDP per capita affect negatively to the market growth rate, and unemployment positively. Therefore the market's growth speed would be slow down and the share of TV decreased. Therefore the two policies were suggested, increasing the direct payment by the audiences and retire of the inefficient broadcasters.

• The Journal of Engineering Geology
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• v.30 no.4
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• pp.457-468
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• 2020

Problems arising during pile design works for plant construction, civil and architecture work are mostly come from uncertainty of geotechnical characteristics. In particular, obtaining the N-value measured through the Standard Penetration Test (SPT) is the most important data. However, it is difficult to obtain N-value by drilling investigation throughout the all target area. There are many constraints such as licensing, time, cost, equipment access and residential complaints etc. it is impossible to obtain geotechnical characteristics through drilling investigation within a short bidding period in overseas. The geotechnical characteristics at non-drilling investigation points are usually determined by the engineer's empirical judgment, which can leads to errors in pile design and quantity calculation causing construction delay and cost increase. It would be possible to overcome this problem if N-value could be predicted at the non-drilling investigation points using limited minimum drilling investigation data. This study was conducted to predicted the N-value using an Artificial Neural Network (ANN) which one of the Artificial intelligence (AI) method. An Artificial Neural Network treats a limited amount of geotechnical characteristics as a biological logic process, providing more reliable results for input variables. The purpose of this study is to predict N-value at the non-drilling investigation points through patterns which is studied by multi-layer perceptron and error back-propagation algorithms using the minimum geotechnical data. It has been reviewed the reliability of the values that predicted by AI method compared to the measured values, and we were able to confirm the high reliability as a result. To solving geotechnical uncertainty, we will perform sensitivity analysis of input variables to increase learning effect in next steps and it may need some technical update of program. We hope that our study will be helpful to design works in the future.