• Journal of Power Electronics
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• 제13권4호
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• pp.679-691
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• 2013

High-power electromagnetic transmitter power supplies are an important part of deep geophysical exploration equipment. This is especially true in complex environments, where the ability to produce a highly accurate and stable output and safety through redundancy have become the key issues in the design of high-power electromagnetic transmitter power supplies. To solve these issues, a high-frequency switching power cascade based emission power supply is designed. By combining the circuit averaged model and the equivalent controlled source method, a modular mathematical model is established with the on-state loss and transformer induction loss being taken into account. A triple-loop control including an inner current loop, an outer voltage loop and a load current forward feedback, and a digitalized voltage/current sharing control method are proposed for the realization of the rapid, stable and highly accurate output of the system. By using a new algorithm referred to as GAPSO, which integrates a genetic algorithm and a particle swarm algorithm, the parameters of the controller are tuned. A multi-module cascade helps to achieve system redundancy. A simulation analysis of the open-loop system proves the accuracy of the established system and provides a better reflection of the characteristics of the power supply. A parameter tuning simulation proves the effectiveness of the GAPSO algorithm. A closed-loop simulation of the system and field geological exploration experiments demonstrate the effectiveness of the control method. This ensures both the system's excellent stability and the output's accuracy. It also ensures the accuracy of the established mathematical model as well as its ability to meet the requirements of practical field deep exploration.

• Journal of the Korean Data and Information Science Society
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• 제17권3호
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• pp.889-904
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• 2006

Our purpose is to ascertain, if possible, whether atomic bomb survivors with cataracts and epilation were more radiosensitive than those survivors with cataracts but without epilation. A major ophthalmologic survey was conducted in Hiroshima and Nagasaki in 1963-64. At that time, 2125 individuals were examined. Among these individuals, estimated eye organ doses, based on the DS86 dosimetry system, and information on the occurrence of epilation within the first 60 days following the bombings are available on 1742. In the analysis of these data we have assumed that each individual represents a sample of one from a binomial distribution, and that the occurrence of cataracts and epilation are independent biological phenomena. We got following results. The threshold for cataract induction and its 95% confidence limits have been estimated from data on the occurrence of cataract and epilation. Among the 1742 study subjects, 40 had both cataracts and severe epilation. The estimated threshold based on these cases is 0.98 sievert(Sv), with 95% lower and upper confidence bounds of 0.72, and 1.32 Sv, respectively, and is highly statistically significant. Among the 27 cases of cataracts where severe epilation was not reported, the estimated threshold is 1.74 Sv with 95% lower and upper confidence bounds of 1.21 Sv, and "not estimable". The difference between these two estimates is not statistically significant although the effect of dose is highly significant in both instances. The potential importance of biases in the DS86 dose estimates is discussed. The difference between the threshold estimated from cataract cases with epilation and that from cases without epilation is not statistically significant at the 5% or 10% level, and thus affords no support for the notion of increased radiosensitivity.

• 한국유체기계학회 논문집
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• 제11권5호
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• pp.15-21
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• 2008

In modem wind power system of large capacity above 1MW, horizontal axis wind turbine(HAWT) is a common type. And, the optimum design of wind turbine to guarantee excellent power performance and its reliability in structure and longevity is a key technology in wind Industry. In this study, mathematical expressions based upon the conventional BEMT(blade element momentum theory) applying to basic 1MW wind turbine blade configuration design. Power coefficient and related flow parameters, such as Prandtl's tip loss coefficient, tangential and axial flow induction factors of the wind turbine analyzed systematically. X-FOIL was used to acquire lift and drag coefficients of the 2-D airfoils and we use Viterna-Corrigan formula to interpolate the aerodynamic characteristics in post-stall region. In order to predict the performance characteristics of the blade, a performance analysis carried out by BEMT method. As a results, axial and tangential flow factors, angle of attack, power coefficient investigated in this study.

• Transactions on Electrical and Electronic Materials
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• 제17권6호
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• pp.335-340
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• 2016

The vibrational energy is prevalent in the natural environment, which is studied by energy researchers as a new energy resource in recent years. Vibration generation utilizes electromagnetic induction technology, piezoelectric technology and certain characteristics of smart materials to convert mechanical energy into electrical energy. In this paper, a new method of using MSMA (magnetic shape memory alloy) to generate electricity is proposed and the principle of generating electricity is demonstrated. Martensitic variants and magnetic domain characteristics of MSMA are analyzed. Combining with Gibbs free energy function thermal theory, the mathematics model of MSMA vibration generator is established. The basic structure of MSMA vibration generator is designed and simulation is done to analyze that the effects of generator output voltage when the input amplitude and frequency of vibration stress change. The simulation experiments verify the feasibility of using MSMA to make the micro vibration generators and the correctness of the mathematical model, which lays a good foundation for the further research and application of MSMA vibration generator.

• 한국학교수학회논문집
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• 제19권3호
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• pp.291-308
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• 2016

본 연구는 수학영재의 심화학습을 위한 주제로 사용해 볼 수 있는 이항계수의 정의와 성질을 탐구하고, 이로부터 수학적 귀납법, 이항정리, 조합의 정의, 도로망 상황 모델 등을 이용한 이항계수가 포함된 등식의 문제해결방법을 연구하였다. 그리고 이러한 내용들이 수학영재 학생들에게는 충분히 탐구의 대상이 될 수 있어 수학영재 교육의 심화학습 주제로 적절하게 다루어질 수 있다는 것과, 수학의 깊은 의미를 경험할 수 있는 학습주제로 사용될 수 있다는 것을 학생들에게 지도한 예시로 소개한다.

• Journal of Advanced Marine Engineering and Technology
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• 제32권6호
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• pp.827-833
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• 2008

In this study, mathematical expressions based upon the conventional BEMT(blade element momentum theory) was applied to basic 100kW wind turbine blade configuration design. Power coefficient and related flow parameters, such as Prandtl's tip loss coefficient, tangential and axial flow induction factors of the wind turbine were analyzed systematically. X-FOIL was used to acquire lift and drag coefficients of the 2-D airfoils and Viterna-Corrigan formula was used o interpolate he aerodynamic characteristics in post-stall region. Also, aerodynamic characteristics, measured in a wind tunnel to calculate he power coefficient was applied. The comparative results such as axial and tangential flow factors, power coefficients were presented in this study. Power coefficient, calculated by in-house code was compared with the GH-Bladed result. The difference of the aerodynamic characteristics caused the difference of the performance characteristics as variation as TSR.

• 한국정보처리학회논문지
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• 제6권8호
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• pp.2098-2115
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• 1999

신경망 회로의 해석에서 아직 해결하지 못하는 부분이 은닉층(hidden layer)의 해석이다. 본 논문에서는 신경망 회로의 기본적인 구성회로로써 하나의 입력(p levels)과 하나의 출력(q levels)을 갖는 2-layer Core-Net를 정의하고, 이 Core-Net의 처리 가능 용량(the capacity)은 2차원 무게값 공간(weight space)을 나눌 수 있는 영역의 수로, {{{{ {a}_{p,q} = {{q}^{2}} over {2}p(p-1)- { q} over {2 } (3 { p}^{2 } -7p+2)+ { p}^{2 }-3p+2}}}}임을 수학적 귀납법으로 증명하였다. 이 Core-Net로 신경망 회로의 중간층 해석이 가능함을 시뮬레이션 예제를 통하여 보였다.

• 한국수학교육학회지시리즈C:초등수학교육
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• 제18권3호
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• pp.217-234
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• 2015

수학 교과에서는 컴퓨터와 인터넷 환경을 교수 학습에 적극적으로 활용해 왔다. 그러나 수학 교수 학습 웹사이트 운영의 질적인 측면에서는 여러 문제점들이 제기되어 왔다. 본 연구는 영국 케임브리지 대학교의 'Millennium Mathematics Project' 사업의 일환으로 1997년부터 운영되고 있는 NRICH 웹사이트의 운영 방식, 웹사이트 체계, 콘텐츠 내용, 콘텐츠의 연계 방식 등을 조사하였다. 이를 바탕으로 주제 중심의 콘텐츠 구성, 지속적 장기적 자료 축적, 이용자들의 참여 유도, 다양한 협력 사업 등의 측면에서 우리나라에 주는 시사점을 정리하였다.

• 한국수학교육학회지시리즈A:수학교육
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• 제44권3호
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• pp.457-475
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• 2005

We have inquired on what the statistical classes of the secondary schools had been aiming to, say the epistermlogical objects. And we now appreciate that the main obstacle to the systematic articulation is the lack of anticipation on what the statistical concepts are. This study focuses on the ingredients of the statistical concepts. Those are to be the ground of the systematic articulation of statistic courses, especially of the one for the school kids. Thus we required that those ingredients must satisfy the followings. i) directly related to the contents of statistics ii) psychologically developing iii) mutually exclusive each other as much as possible iv) exhaustive enough to cover all statistical concepts We examined what and how statisticians had been doing and the various previous views on these. After all we suggest the following three concepts are the core of conceptual developments of statistic, say the concept of distributions, the summarizing ability and the concept of samples. By the concepts of distributions we mean the frequency views on each random categories and that is developing from the count through the probability along ages. Summarizing ability is another important resources to embed his probe with the data set. It is not only viewed as a number but also to be anticipated as one reflecting a random phenomena. Inductive generalization is one of the most hazardous thing. Statistical induction is a scientific way of challenging this and this starts from distinguishing the chance with the inevitable consequences. One's inductive logic grows up along with one's deductive arguments, nevertheless they are different. The concept of samples reflects' one's view on the sample data and the way of compounding one's logic with the data within one's hypothesis. With these three in mind we observed Korean Statistic Curriculum from K to 12. Distributional concepts are dealt with throughout but not sequenced well. The way of summarization has been introduced in the 1 st, 5th, 7th and the 10th grade as a numerical value only. One activity on the concept of sample is given at the 6th grade. And it jumps into the statistical reasoning at the selective courses of ' Mathematics I ' or of ' Probability and Statistics ' in the grades of 11-12. We want to suggest further studies on the developing stages of these three conceptual features so as to obtain a firm basis of successive statistical articulation.

• 한국작물학회지
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• 제55권4호
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• pp.284-291
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• 2010

고 고형분함량 감자 생산을 위한 수확시기를 예측하는 데 있어 에너지 소모량의 추정에 대한 연구결과는 다음과 같다. 1. 각 지역별로 포장의 파종시기부터 수확시기까지 최근 5년간(2005년~2009년) 평균기온, 강수량, 상대습도, 일조시간, 바람, 지중온도 등의 농업환경을 조사한 결과 파종기 저온피해와 괴경비대기 장마기간을 회피한다면 가공용 원료감자는 가공품 생산에 필요시마다 물량을 수급하기 때문에 만숙재배를 하지 않아 품종의존도가 낮아 수확시기의 환경에 대한 비중이 큰 것으로 판단되었다. 2. 파종시기부터 출현까지에는 지중온도에 영향을 많이 받아 지역별 편차가 심해 시뮬레이션에서는 출현시기를 기준으로 감자의 수확적기를 예측하는 것이 바람직하였다. 3 수확시기를 예측하기 위한 생장모형은 $Tp=\frac{Tm{\cdot}Wm^{Tp}}{Wm^{Tm}}$를 사용하고, 생장량 Wm을 계상하는 기본 생장모형은 $Wm={\int}^m_tf(x)dt$를 사용하였다. 4. 기본 생장모형을 통해 Wm을 계상할 때는 광합성율(${\Delta}A$)과 식물체내 에너지 소모(${\Delta}E$) 개념을 적용해야 보다 정밀한 수확시기를 예측할 수 있었으며, 식물체내 에너지 소모에 대한 정의는 기후변화에 대응하여 농업환경에 대처하는 식물체내 에너지 소모를 계상하는 것으로 최근 5년간(2005년~2009년) 수확시기에 따라 고형분함량을 측정한 결과 광합성율만 계상할 때 보다 에너지 소모개념을 적용한 것이 효과적이었다.