• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.39-39
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• 2011

하천에서 수공구조물을 설계시 구조물의 규모, 형식, 운영방식, 안정성 등을 검토하기 위하여 일반적으로 수리모형실험과 수치모형실험을 이용한다. 수리모형실험은 자연현상의 왜곡을 최소화하여 검토결과를 얻을 수 있다는 장점이 있지만, 많은 시간과 비용, 인력 및 공간이 필요하기 때문에 단기간에 다양한 검토가 필요한 경우에는 많은 제약이 따른다. 반면에 수치모형실험은 제한적인 조건에서 검토목적 및 용도에 따라 다양한 수치모의기법을 활용하여 상대적으로 낮은 비용과 신속하고 다양한 검토가 가능하다는 장점을 가지고 있다. 그러나 수치모형실험은 어디까지나 자연현상에 대한 수학적, 물리적 기법을 활용한 분석이기 때문에 결과에 대한 신뢰성 확보가 매우 중요하다. 최근에는 컴퓨터의 계산능력 향상과 유체의 복잡한 동수역학적 거동 해석 기법의 다양화, 그리고 많은 적용성 검토 연구결과로 인한 신뢰성 향상 등으로 인해 수치모형실험에 대한 관심이 높아지고 있다. 본 연구는 현재 금강에 건설 중인 금강보에 대하여 다차원 수치모형인 EFDC(Environmental Fluid Dynamics Code)를 이용하여 하천 구조물 및 물리적 환경변화에 대한 정밀수리분석을 실시하기 위한 사전절차로, EFDC 모형을 하천수리해석에 적용할 경우 모형에 포함되어 있는 다양한 변수설정 및 제약조건들에 대하여 적용한계를 검토하고자 한다. 검토방법은 금강보가 건설되기 이전의 하천지형 상황에서 EFDC 모형과 HEC-RAS 모형을 이용한 수리분석을 수행하고, 수리거동 결과 들을 상호 비교 분석 한다. 수치모의 대상구간은 금강보 건설구간을 포함하여 약 20km 구간이고, 대상구간에 대하여 3차원 정밀지형자료를 구축하였으며, 과거 호우사상에 대한 구간 내 관측 수위 및 모형별 계산수위결과를 비교 검토하였다.

• KIPS Transactions on Computer and Communication Systems
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• v.1 no.3
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• pp.193-204
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• 2012

This paper specifies a low-cost global mobility management architecture and protocol procedure called LC-$GM^2$, which is based on Proxy Mobile IPv6. In LC-$GM^2$, mobility management is performed by the network entity. The benefit is the elimination of the wireless link data delivery tunnel overhead between a mobile node and the access router. To compare with the well-known Hierarchical Mobile IPv6 mobility management protocol and GPMIP, the location update, packet delivery, and total cost functions generated by a mobile node during its average domain residence time are formulated for each protocol based on Fluid-flow mobility model. Then, the impacts of various system parameters on the cost functions are analyzed. The analytical results indicate that the proposed global mobility management protocol can guarantee lower total costs.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.10
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• pp.1254-1260
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• 2019

Recently, 5G cellular systems have been attracted great attention as a key enabler for Industry 4.0. In this paper, we propose a novel random access based on pilot-assisted opportunistic transmission to support internet-of-things (IoT) scenario in cellular networks. A key feature of our proposed scheme is to enable each of IoT devices to attempt opportunistic transmission of its data packet in Step 3 with randomly selected uplink pilot signal. Both the opportunistic transmission and the pilot randomization in Step 3 are effective to significantly mitigate the occurrence of packet collisions. We mathematically analyze our proposed scheme in terms of packet collision probability and uplink resource efficiency. Through simulations, we verify the validity of our analysis and evaluate the performance of our proposed scheme. Numerical results show that our proposed scheme outperforms other competitive schemes.

• Journal of Gifted/Talented Education
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• v.13 no.4
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• pp.65-94
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• 2003

The purpose of this study is to acquire the information on the current situation of students' selection process in order to renovate the system of picking up the students. As a first step of the study, we examined the validity of the factors of the single-out system such as qualification and the process for the application and the standards and proceeding of the selection. Then we analysed the result of the entrance examination of Hansung Science Highschool in 2002. The analysis was on the correlation between the result of entrance examination and the achievement in the school and the decision of the course after graduation. To know on the achievement of the students, we investigated the records of regular tests and asked the teachers' opinion in math and science classes. As a result, we gained the following points: First, the present single-out system has a danger of excluding students who are much talented in science and math field because it is based on students' achievements in middle schools; Second, the new selection system should consider the character and attitude of the applicants in addition to their knowledge; Third, the continuous observation of the teacher in middle school should be an important factor of the picking up system; Fourth, more questions requiring divergent thinking ability and inquiry skill should be developed as selective examination question. Also examination questions should cover the various contents from mathematics to science, and do not affect pre-learning; Finally, the system of present letting all students stand in one line should be changed into that of letting students in various lines. We can consider using multi-step selection system.

• 한국정보교육학회:학술대회논문집
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• 2004.08a
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• pp.236-241
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• 2004

Algorithms is defined "step-by-step procedure for accomplishing a task that we wish to complete." Algorithms has much educational values. Already many scholar is making researches about paper-and-pencil algorithms in mathematic education. The purpose of this paper is to propose a study on the direction of teaching algorithms with analysis of algorithms

• Journal of Korean Association for Spatial Structures
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• v.8 no.4
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• pp.47-55
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• 2008

This paper deals with basic theories and some numerical results on structural optimization for geodesic dome. First of all, the space efficiency of geodesic dome is investigated by using the ratio of icosahedron's surface area to the internal volume enclosed by it. The procedure how to create the geodesic dome is also provided in systematic way and implemented and utilized into the design optimization code ISADO-OPT. The mathematical programming technique is introduced to find out the optimum pattern of member size of geodesic dome against a point load. In this study, total weight of structure is considered as the objective function to be minimized and the displacement occurred at loading point and member stresses of geodesic dome are used as the constraint functions. The finite difference method is used to calculate the design sensitivity of objective function with respect to design variables. The SLP, SQP and MFDM available in the optimizer DoT is used to search optimum member size patterns of geodesic dome. It is found to be that the optimum member size pattern can be efficiently obtained by using the proposed design optimization technique and numerical results can be used as benchmark test as a basic reference solution for design optimization of dome structures.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.11
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• pp.998-1005
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• 2017

In this paper, we first introduce a systematic verification procedure for hierarchically structured avionics system. By making use of equipment models, it can perform individual verifications of each subsystem, integrated verifications of multiple subsystems, and an integrated verification of a whole system. A multi-mode system integration laboratory is then proposed to make it possible to execute various individual or integrated verification tests at the same time. By mathematically proving that the proposed multi-mode system integration laboratory needs less verification time than the conventional verification methodology, it is expected to enhance the efficiency of the systematic verification procedure and as a result, reduce the overall verification period and costs.

• Journal of Practical Engineering Education
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• v.11 no.2
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• pp.159-165
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• 2019

Engineering design education has been established and implemented as three stages of basic design, element design, and capstone design with the introduction of engineering education accreditation system. In the basic design, the concept and procedure of design is introduced to the beginners of engineering, and the creativity and teamwork is practiced rather than mathematical detailed design for the purpose of being connected to and used effectively in the capstone design. In this study, the opinions of the students performing capstone design after taking basic design were surveyed through questionnaire. Overall, students recognize the importance of basic design education and experienced that it is useful. The results indicate that effective basic engineering design education is being carried out, and are considerably agree to those at the professors in the former survey.

• Journal of Digital Contents Society
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• v.10 no.2
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• pp.367-373
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• 2009

Computer programming education helps students understand abstract concepts better and solve given problems independently. Many previous studies on programming education have focused on procedural programming languages such as BASIC and C, but studies on objected-oriented program ming language like JAVA is rare. This paper examines how an architectural neural, objected-oriented JAVA programming study system can improve logical thinking ability and encourage self-led study and stimulate interests in computers among elementary school students. The system has been developed and is suitable for distributed Internet environment. The experiment results demonstrated that the objected-oriented programming education enhances logical thinking ability, exerts a positive impact on student achievement in math and science, and stimulate interests in computers.

• Journal of the Society of Disaster Information
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• v.11 no.1
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• pp.63-72
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• 2015

This study aims to examine the state of accidents and related issues related to Theme Groups experiential learning experiences of students and suggest ways to improve security measures to prevent future incidents. Case studies of the sunken Sewol ferry and the collapse of the gymnasium at Mauna resort in Gyeongju are conducted by analyzing the existing literature and the data collected from the media sources and related agencies. With a basis on the findings of the analyses, it is suggested that legal foundation and disaster and risk management systems (systematic revision of the laws, raised safety awareness among citizens, production and education of security managers, formation of disaster management organizations, establishment of headquarters in case of emergency and installation of first aid facilities, improved national response system, enforcement of disaster drills, introduction of assessment system, etc.) must be established to contribute to creating a safer society.