• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집B
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• pp.108-112
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• 2000

This paper presents a mathematical model and simulation of the micro-actuator based on thermally induced liquid-vapor phase-change in a partially-filled closed cavity. The volume expansion by liquid-vapor Phase change can generate considerable forces and displacement $({\sim}50{\mu}m)$ required for commercial use. For optimum operation involving many cycles within the closed chamber, active(thermoelectric) heating and cooling is used. The optimization of the system is conducted according to the parameters such as input power and response time. The optimized performance of micro-actuator is reasonable compared to other actuators.

• 한국실내디자인학회논문집
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• 제21호
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• pp.10-16
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• 1999

Mathematics is considered to the beginning of designing thinking because of the sense of logical order system. In this study, it was regarded the mathematics as the logic and the measurement of design system. as is often the case in history, mathematics, it is regard as conceptual model of architectural though, as aesthetic proportional measure and the mirror of thought. The direction of this study is rather multi-sided approaching to the spatial concept than one-sided plane. It is multi-acceptable way to apply mathematical principle to the pace and to be a flexible one. And boundary of interpretation of the flexibility means potential use-ability, and the strictly meaning of flexibility means that the acception of the various Secession and the Change of space. And the various interpretation of the flexibility only can expressed in the relation of opposite concept: the assembly and the disassembly, the expand and the decease, the open and the close and the construct and the de-construct. Mathematics provide the resonable way in architectural thinking and endow the order as logical organizatiov. Regarding these facts, this research is for making it possible to consider the expression property of interior space combination as the way of understanding the accepting of the changes of the times with the mathematical induction, using the rational method like the mathematical arrangement organizatiov.

• 한국학교수학회논문집
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• 제13권1호
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• pp.163-184
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• 2010

본 연구는 수학에 관한 편지 쓰기가 고등학생의 수학적 의사소통 및 성향에 미치는 영향에 대해서 알아보는데 있다. 고등학교 1학년 2개 학급을 대상으로 1개 반을 실험반으로 다른 1개 반을 비교반으로 나누어 2개월간 연구하여 그 결과를 분석하였다. 그 결과는 수학에 관한 편지 쓰기를 수학과 수업에 적용한 실험반이 교과서 중심의 학습 지도 방법을 적용한 비교반보다 수학적 의사소통 및 성향을 신장시키는데 효과적임이 나타났다. 실제로 수학에 관한 편지 쓰기를 통해 고등학생들은 성취감을 느끼고 반성적 사고를 하게 되며, 수학적 이해과정에 도움을 받는 것으로 나타났다. 또한 수학에 관한 편지 쓰기는 학생들이 학습태도를 긍정적으로 바꾸며 수업에 적극적으로 참여하게 하였다. 그러나 자신의 생각이 노출되는 것에 대한 부담을 느끼는 것으로 나타났다. 후속연구에서는 충분한 사전 조사로 수학에 관한 편지 쓰기의 횟수와 시간을 잘 결정하고 연구 기간을 충분히 잡아 학생들의 변화를 지속적으로 관찰하며 평가와의 연계로 학생들의 적극적인 참여를 유도할 필요가 있다고 본다.

• 대한기계학회논문집A
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• 제24권12호
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• pp.3080-3087
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• 2000

We obtain the mathematical model of the hard disk drive actuator system the system response data of the finite element analysis or experimental results. The model is base on the Rayleigh-Ritz method to approximate the dynamic response of the actuator system. The basic idea is to use the curve-fit technique to obtain the approximation coefficients. It allows the dynamic analysis of the actuator system without resort to the repetitive finite element modeling work. Even though the dynamic characteristics of the system of the system are affected somewhat by the structural modification and the change of the material properties, we can use the modified size and dynamic properties of the actuator system in the mathematical model to some extent. In this study, we express the mathematical model of the simplified rectangular plate first and then proceed to the actual hard disk drive actuator system.

• Nuclear Engineering and Technology
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• 제48권5호
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• pp.1280-1290
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• 2016

This paper presents an advanced estimation method for obtaining the probability density functions of a damage parameter for valve leakage detection in a reciprocating pump. The estimation method is based on a comparison of model data which are simulated by using a mathematical model, and experimental data which are measured on the inside and outside of the reciprocating pump in operation. The mathematical model, which is simplified and extended on the basis of previous models, describes not only the normal state of the pump, but also its abnormal state caused by valve leakage. The pressure in the cylinder is expressed as a function of the crankshaft angle, and an additional volume flow rate due to the valve leakage is quantified by a damage parameter in the mathematical model. The change in the cylinder pressure profiles due to the suction valve leakage is noticeable in the compression and expansion modes of the pump. The damage parameter value over 300 cycles is calculated in two ways, considering advance or delay in the opening and closing angles of the discharge valves. The probability density functions of the damage parameter are compared for diagnosis and prognosis on the basis of the probabilistic features of valve leakage.

• Nuclear Engineering and Technology
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• 제27권3호
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• pp.374-384
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• 1995

해석함수 전개 노달방법의 수학적 수한해를 AFEN코드에 약간의 수정을통하여 AFEN노달 방정식의 전치행 렬 방정식을 풀어서 계산하였다. 또한 이 수반해를 사용하여 섭동이론(정확한 섭동이론과 일차근사 섭동이론)을 이용한 계산이 반응도 변화를 예측하기 위해 두개의 잘 알려진 표준문제를 통하여 수행되었다. 본 연구에서 수반해의 계산방법은 물리적 수반해 및 정방정식의 고유치를 필요로 하지 않는다. 계산결과들은 본 논문에서 계산된 수반해가 AFEN방법의 정화한 수학적 수반해임을 보여준다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1998년도 제13차 학술회의논문집
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• pp.474-479
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• 1998

In this paper, we present a mathematical model of the piezoelectric pump and its application to the automobile brake system. The piezoelectric pump consists of a multi-layered piezoelectric element a diaphragm, pumping values, resonant pipes and accumulators, and the maximum pumping power of 62W nab obtained in the previous experiments by using the piezoelectric element of 22mm diameter and 55.5mm length. A detailed mathematical model of the pump is derived here by considering the compressibility of the working oil, nonlinear characteristics of piezoelectric element, the time delay of pumping values' action and be on. The validity of the model is illustrated by comparing the experimental data and the simulation results. Using the mathematical model of the piezoelectric pump, a brake system for automobile disk brake is also simulated in this paper. The brake system consists of a piezoelectric pump as a power source, calipers and its piston to generate brake force, and a three position solenoid value to change the brake situation. It is shown that 15mm/sec of piston speed and 20kN of piston force are obtained by using the piezoelectric element of 33mm diameter and 55.5mm length.

• 한국수학교육학회지시리즈A:수학교육
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• 제51권3호
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• pp.301-321
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• 2012

Since research has barely been done on the minority with low-achievement & low-SES in probability, this research attempted to search the change of their thinking level in the classes of probability and motivate them on the mathematical learning to feel confident in mathematics. We can say that the problems of the educational discriminations are due to the overlook on the individual conditions, situations, and environments. Therefore, in order to resolve some discrimination, 4 students who belonged to the minority group, engaged in the research, based on 10 units of the instructional materials designed for the research. As a result, for the student's thinking level, it was observed that they were improved from the 1st to the 3rd level in probability. Also, the researcher found that the adequate use of the encouragement, the praise, the direct explanation, and the scaffolding enabled them to prompt their learning motives and the increased responsibility on the learning. As time passed, the participants could share their mathematical knowledge and its concept with others, in the increased confidence.

• 한국수학교육학회지시리즈D:수학교육연구
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• 제14권4호
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• pp.361-380
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• 2010

Some 400 Secondary One (i.e. seventh-grade) students from 10 schools were provided with non-routine mathematical problems in their normal mathematics classes as exercises for one academic year. Their attitudes toward mathematics, their conceptions of mathematics and their problem-solving performance were measured both in the beginning and at the end of the year. Hierarchical regression analyses revealed that the introduction of an appropriate dose of non-routine problems would generate some effects on the students' conceptions of mathematics. A medium dose of non-routine problems (as reported by the teachers) would result in a change of the students' conception of mathematics to perceiving mathematics as less of "a subject of calculables." On the other hand, a high dose would lead students to perceive mathematics as more useful and more as a discipline involving thinking. However, with a low dose of non-routine problems, students found mathematics more "friendly" (free from fear). It is therefore proposed that the use of non-routine mathematical problems to an appropriate extent can induce changes in students' "lived space" of mathematics learning and broaden their conceptions of mathematics and mathematics learning.

• 한국수학교육학회지시리즈A:수학교육
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• 제53권2호
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• pp.239-261
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• 2014

The purpose of this study is to analyze the influences of discussion-based learning of mathematics using smart phone application on the middle school students' mathematics learning. For this purpose, we selected 6 open problems suitable for learning mathematical reasoning and five 3rd grade middle school students as participants who expected to participate in 6 lessons of discussion-based learning of mathematics using smart phone application. From the analysis of 6 lessons, we found the following results. First, attending the lessons of discussion-based learning of mathematics using smart phone application makes students more interested in mathematics and change their mathematics learning attitudes more positively. Second, the lessons of discussion-based learning of mathematics using smart phone application facilitate students' mathematical communication with the help of various communication methods using many functions of smart phone applications. Third, the lessons of discussion-based learning of mathematics using smart phone application provide teachers with teaching-learning environment where teachers can easily give their students consultation about mathematics learning or daily life.