• Journal of computational fluids engineering
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• v.8 no.3
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• pp.32-40
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• 2003

CFD analyses of the three-dimensional turbulent flow in the impeller and diffuser of an axial flow pump including suction and discharge parts are presented and compared with experimental data. The purpose of the current study is to validate the CFD method for the performance analysis of the main coolant pump for SMART and to investigate the effect of suction and discharge shapes on the pump performance. To generate a performance curve, not only the design point but also the off-design points were computed. The results were compared with available experimental data in terms of head generated. At the design point, the analysis accurately predicts the experimental head value. In the range of the higher flow rates, the results are also in very good agreement with the experimental data, in magnitude but also in terms of slope of variation. For lower flow rates, the results shows that the analysis considering the suction and discharge well describe the typical S-shape performance curve of the axial pump.

• Communications of Mathematical Education
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• v.25 no.1
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• pp.147-166
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• 2011

In this paper, we listed and discussed the properties of the Pythagorean triples which 5 gifted 9th graders could draw in spreadsheets environments. And we also discussed their implications. In detail, in spreadsheets environments students could make the table of Pythagorean triples easily under several conditions of generate numbers of Pythagorean triples. And they could draw several properties of Pythagorean triples from the tables and could prove them. In spreadsheets environments it is easy to give students chances of generalization of the properties of Pythagorean triples which they had obtained from the concrete table of Pythagorean triples.

• Journal of the Korea Computer Industry Society
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• v.2 no.8
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• pp.1133-1138
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• 2001

In this paper, we implemented that MMT(Multimedia Terminal) demonstrates spot news, weather forecast, sports news and cultural news employed CDMA mobile communication networks. The MMT displays mobile pictures/joint pictures/on screen ad and to make known Bus stop or Mobile stations. The MMT gives driver's and passenger's safety and valuable information for one's use GPS satellites. We verified to make real time mobile picture transfer use of CDMA2000 1×(IS-95C) network and development the scheduler control each module. This system tested on vehicle that train and bus. MMT was implemented high reliability and stability by the embedded system. The mobile terminal shows reliable data transfer rate about 74Kbps on IS-95C.

• Journal of the Korea Computer Industry Society
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• v.5 no.5
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• pp.747-754
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• 2004

In this paper, we obtain an optimal corpus that can represent its characteristics very well from the baseline corpus which consists of unique 1,566,943 names among company names in a directory assistance serve (114). Two kinds of optimal solutions ared considered to obtain the optimal corpus. The first solution is to find phonetically balanced corpus (PBC), which are the minimum set including all possible triphones in the baseline corpus. The second solution is to find the phonetically distributed corpus (PDC), which is a minimum set representing the frequency characteristics of triphones in the baseline corpus. We can obtain 8,699 words as the PBC and 16,783 words (similarity measure R = 0.92) as PDC, respectively. These corpora can be used for the development of speech recognition and speech synthesis.

• Journal of Satellite, Information and Communications
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• v.12 no.1
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• pp.107-113
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• 2017

Recently, digital signage is various changes and converging media. It is common to exhibit and guide focusing on information transfer by using the display. Such a method can not express variously changing digital signage. Therefore, we have to find a way to solve the problem of place and structure. In this paper, we experimented the new direction technique. Finally, we are going to propose acoustic direction technique using a microphone to maximize digital signage and intention of delivery by adding an sound reinforcement method to the visual representation.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.1809-1812
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• 2008

지하방수로는 도시의 지하에 대규모 수로 터널을 시공하여, 도시 지역에 발생한 집중 호우를 초기에 배제하여 제내지 침수 피해를 줄이는 목적으로 사용되는 대표적인 구조적 홍수 피해 경감 대책이다. 효과적으로 침수 피해를 줄일 수 있을 뿐만 아니라, 특히 지하에 설치되어 토지 수용에 대한 부담이 줄어들기 때문에 일본 등지에서 최근 주요 홍수 방어 대책으로 활용되고 있다. 지하방수로 유입부는 크게 접근수로, 유입구, 수직 갱도(vertical shaft)로 구분되며, 접근 수로를 통하여 유입된 흐름은 유입구를 통하여 가속된 후 수직 갱도로 유입되게 된다. 따라서 지하방수로의 배제 능력을 평가하기위해서는 유입구에서의 유량 및 흐름 특성을 정확히 평가하는 것이 매우 중요하다. 나선식 종경사형 유입구(inclined spiral intake)는 지하방수로 유입구 중 가장 일반적으로 사용되는 형식으로 나선식 유입구의 한 형태로 유입구의 외측 또는 중앙선을 따라서 일정한 경사를 주어 사류 유입 흐름을 유도함으로서 유량 배제 효율을 높인 형태이다. 나선식 종경사형 유입구도 일반적인 나선식 유입구와 마찬가지로 접근수로 수위를 측정하여 유입량을 예측할 수 있다. 본 연구에서는 수리 모형 실험을 통하여 나선식 종경사형 유입구에 대한 수위-유입량 관계를 검토하였다. 평탄한 입구를 가지는 안내벽이 있는 형식의 유입구 모형을 이용하여 수위-유입량 관계를 검토하였다.

• Journal of The Korean Association of Information Education
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• v.2 no.2
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• pp.252-259
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• 1998

Vehicle navigation systems employ a certain route planning algorithm that provides the shortest path between the starting point and the destination point. The performance of a given route planning algorithm is measured through the degree of optimal route selection and the time cost to complete searching an optimal path. In this paper, various route planning algorithms are evaluated through computer simulation based on a real digital map database. Among those algorithms evaluated in this paper, the Modified Bi-directional A${\ast}$ algorithm is found to be the best algorithm for use in vehicle navigation systems.

• The KSFM Journal of Fluid Machinery
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• v.10 no.3 s.42
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• pp.17-24
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• 2007

This paper presents the design procedure of a vertical wind turbine named jet-wheel-turbo turbine and the numerical and experimental verifications. The design parameters such as the rotor inlet angle, the diameter-to-hub ratio, the inlet guide outlet angle and the solidity were optimized to maximize the energy transfer, and to further increase the turbine efficiency by applying the side guide vane and the side opening to the rotor. The maximum power coefficient of 0.59, which is much higher than the ever-designed three-bladed horizontal turbines, was experimentally obtained when the optimal inlet- and side-guide vanes were installed and both sides of the rotor were 80% opened. The maximum power coefficients occur at the tip speed ratio ranging between 0.6 and 0.7. This vertical-axis turbine model can be applied to the large-scale power generation system with the speed and torque control algorithm for the specified wind characteristics.

• The Journal of Korean Institute for Practical Engineering Education
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• v.3 no.1
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• pp.69-75
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• 2011

This paper presents a model of e-learning based on ubiquitous computing configuration. First of all, we survey the advanced e-learning systems for foreign and domestic universities. Next we propose the optimal e-learning model based on ubiquitous computing configuration. The proposed e-learning model as following. we propose the e-learning system's hardware and software configurations, that are server and networking systems. Also, we construct the proposed e-learning systems's services. There are attendance and absence service, class management service, common knowledge service, score processing service, facilities management service, personal management service, personal authorization issue management service, campus guide service, lecture-hall management service. Then we propose the laboratory equipment management service, experimental materials management service etc. The proposed model of e-learning based on ubiquitous computing configuration will be able to contribute to the next generation university educational paradigm.

• Proceedings of the Korean Society of Computer Information Conference
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• 2011.01a
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• pp.159-162
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• 2011

이 연구는 인지기제를 활용한 문제기반학습이 학습자의 학업성취도와 수학적 태도에 미치는 효과를 분석하였다. 우선 초등학교 수학과 학습에서 학습자들의 인지과정을 안내할 수 있는 문제기반학습 설계를 위해 문제기반학습 모형에 란다(N. Landa)의 인지기제 교수학습설계이론을 적용하여 인지기제 활용 문제기반학습 모형을 도출하였다. 그리고 초등학교 수학과 4학년 2학기 4개 단원의 8차시를 추출하여 문제를 개발하고 서울시 소재 'ㅈ' 초등학교 4학년 학생들 중 동질집단으로 확인된 2개 학급에 이 모형을 적용하였다. 연구 결과 인지기제 활용 문제기반학습을 적용한 실험집단과 적용하지 않은 통제집단 간 학업성취도 효과에 있어서 통계적으로 유의한 차이가 있었다. 또한 수학적 태도와 관련해서는 하위영역 중 수학에 대한 자아개념과 수학에 대한 태도 영역에서는 유의한 차이가 있었으나 수학에 대한 학습습관 영역에서는 유의한 차이를 보이지 않았다. 특히 세부영역별로 자신감, 흥미, 우월감, 주의집중, 목적의식, 자율학습에 있어서 유의한 차이를 보였으며, 학습기술 적용과 성취동기에 대해서는 유의한 차이가 없었다.