• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.30 no.3
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• pp.21-23
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• 2001

수도직결 급수방식을 5층 건물까지로 확대보급하기 위한 서울시의 제도정비, 시범실시 효과 및 향후 추진계획에 대해 소개한다.

• Communications of Mathematical Education
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• v.34 no.3
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• pp.355-372
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• 2020

The concept of infinite series is an important subject of major mathematics curriculum in college. For several centuries it has provided learners not only counter-intuitive obstacles but also central role of analysis study. As the understanding in concept on infinite series became foundation of development of calculus in history of mathematics, it is essential to present students to study higher mathematics. Most students having concept of infinite sum have no difficulty in mathematical contents such as convergence test of infinite series. But they have difficulty in organizing concept of infinite series of partial sum. Thus, in this study we try to analyze construct the concept of infinite series in terms of APOS theory and genetic decomposition. By checking to construct concept of infinite series, we try to get an useful educational implication on teaching of infinite series.

• Plant Journal
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• v.15 no.2
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• pp.56-61
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• 2019

In this study, the failure analysis of the internal tube occurred in the high pressure feedwater heater for power generation boiler of 500 MW supercritical pressure coal fired power plant was investigated. I suggested a prediction model that can diagnose internal tube failure by changing the position of level control valve on the shell side and the suction flow rate of the boiler feedwater pump. The suggested prediction model is demonstrated through additional cases of feedwater system unbalance. The simultaneous comparison of the shell side level control valve position and the suction flow rate of the boiler feedwater pump compared to the normal operating state value, even in the case of the high pressure feedwater heater for the power boiler, It can be a powerful prediction diagnosis.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.13 no.6
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• pp.529-534
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• 1988

This paper describes a new method to eliminate some selected harmonics in PWM waveforms using the Walsh series which substitute the linear algebraic equations for the nonlinear equations required in the Fourier series harmonic elimination. In addition, this method is simulated to synthesize periodic PWM waveforms and compare the Walsh analysis with the FOurier analysis, Experimental results are shown that a singel-phase PWM waveforms are identified with the proposed Walsh Series.

• KOREAN POULTRY JOURNAL
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• v.37 no.5 s.427
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• pp.119-121
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• 2005

급수관, 급수 탱크 및 닙플 안에 형성된 바이오필름을 제거하는 것은 쉽지 않지만 양계 질병의 위험성으로부터 안전한 환경을 만들기 위해서는 반드시 필요하다. 따라서 본고는 이와 관련하여 2005년 1월 Poultry International지에 발표된 내용을 번역$\cdot$게재한 것이다.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.30 no.3
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• pp.43-51
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• 2001

본고는 수도직결식 급수시스템에 초점을 두어 역류에 대한 실제를 다룬 것이나, 그 내용은 모든 급수방식에 적용되는 것이다.

• School Mathematics
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• v.16 no.2
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• pp.317-334
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• 2014

The purpose of this study is to grasp pre-service secondary teachers' understanding-realities for Taylor series convergence conceptions and to examine a teaching way using GeoGebra based on the understanding-realities. In this study, most pre-service teachers have abilities to calculate the Taylor series and radius of convergence, but they are vulnerable to conceptual problems which give meaning of the equality between a given function and its Taylor series at any point. Also they have some weakness in determining the change of radius of convergence according to the change of Taylor series' center. To improve their weakness, we explore a teaching way using dynamic and CAS functionality of GeoGebra. This study is expected to improve the pedagogical content knowledge of pre-service secondary mathematics teachers for infinite series treated in high school mathematics.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.27 no.5
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• pp.471-475
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• 1998

위생설비 중 급수, 급탕설비는 공기조화설비에 비해 상대적으로 간단한 설비로 인식되어 왔다. 물론 공사비 측면이나 자동제어의 복잡성 등 공기조화설비에 비해 단순한 설비인 것은 사실이지만 급수·급탕설비는 나름대로 시스템측면에서 고려하면 현재 우리가 적용하고 있는 시스템보다 조금이라도 나은 설계가 이루어질 것으로 사료된다. 본고에서는 급수급탕설비 시스템 설계의 일부분을 다루어 보고자 한다.

• Journal of Korea Water Resources Association
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• v.31 no.6
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• pp.821-832
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• 1998

This study investigates the prediction of daily water supply, which is a necessary for the efficient management of water distribution system. Fuzzy neuron, namely artificial intelligence, is a neural network into which fuzzy information is inputted and then processed. In this study, daily water supply was predicted through an adaptive learning method by which a membership function and fuzzy rules were adapted for daily water supply prediction. This study was investigated methods for predicting water supply based on data about the amount of water supplied to the city of Kwangju. For variables choice, four analyses of input data were conducted: correlation analysis, autocorrelation analysis, partial autocorrelation analysis, and cross-correlation analysis. Input variables were (a) the amount of water supplied (b) the mean temperature, and (c)the population of the area supplied with water. Variables were combined in an integrated model. Data of the amount of daily water supply only was modelled and its validity was verified in the case that the meteorological office of weather forecast is not always reliable. Proposed models include accidental cases such as a suspension of water supply. The maximum error rate between the estimation of the model and the actual measurement was 18.35% and the average error was lower than 2.36%. The model is expected to be a real-time estimation of the operational control of water works and water/drain pipes.

• Geophysics and Geophysical Exploration
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• v.4 no.3
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• pp.70-79
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• 2001

The integral equation method is a powerful tool for numerical electromagnetic modeling. But the difficulty of this technique is the size of the linear equations, which demands excessive memory and calculation time to invert. This limitation of the integral equation method becomes critical in inverse problem. The conventional Born approximation, where the electric field in the anomalous body is approximated by the background field, is very rapid and easy to compute. However, the technique is inaccurate when the conductivity contrast between the body and the background medium is large. Quasi-linear, quasi-analytical and extended Born approximations are novel approaches to 3-D EM modeling based on the linearization of the integral equations for scattered EM field. These approximation methods are much less time consuming than full integral equation method and more accurate than conventional Born approximation. They we, however, still approximate methods for 3-D EM modeling. Iterative series methods such as modified Born, quasi-linear and quasi-analytical can be used to increase the accuracy of various approximation methods. Comparisons of numerical performance against a full integral equation and various approximation codes show that the iterative series methods are very accurate and almost always converge. Furthermore, they are very fast and easy to implement on a computer. In this study, extended Born series method is developed and it shows more accurate result than that of other series methods. Therefore, Iterative series methods, including extended Born series, open principally new possibilities for fast and accurate 3-D EM modeling and inversion.