• 한국방재학회:학술대회논문집
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• 한국방재학회 2008년도 정기총회 및 학술발표대회
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• pp.513-516
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• 2008

The development of crash cushions is finally completed by full-scale vehicle crash tests. Since the current development of crash cushions is achieved by numerous repeated full-scale vehicle crash tests based on empirical and irrational methods, it requires a great amount of costs. In this research, the more rational procedure based on prototype design by static tests and computer simulation is suggested and it can minimize the number of full-scale vehicle crash tests.

• 한국수학사학회지
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• 제24권1호
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• pp.15-29
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• 2011

본 연구는 동양수학의 뿌리를 찾기 위한 목적의 일환으로 인도의 술바수트라스 기하학에 대해 살펴보았다. 술바수트라스(끈의 법칙)는 고대 인도의 베다시대 (BC 1500~600) 문헌으로 힌두교의 경전 중 하나이다. 이 경전 속에 있는 기하학은 성스런 제단이나 사원을 설계하거나 건축하가 위해서 연구되었다. 이 경전은 간단하고 명백한 평면 도형의 명제부터 도형의 작도법, 제단의 작도법과 같은 기하학적 내용뿐 만아니라, 피타고라스 정리와 활용, 도형의 변형, 분수와 무리수, 연립부정방정식 등과 같은 대수적 내용이 포함한다. 따라서 본 논문에서는 일반적인 술바스트라스 기하학의 특징과 희생제단과 불의제단의 건축을 위한 술바스트라스 기하학을 살펴보고 술바수트라스의 기하학과 다른 문명권의 기하학의 발전을 비교하여 그 특징을 조사하였다.

• Journal of Mechanical Science and Technology
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• 제20권5호
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• pp.658-667
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• 2006

Fractional derivative models, which are used to describe the viscoelastic behavior of material, have received considerable attention. Thus it is necessary to put forward the analysis solutions of dynamic systems containing a fractional derivative. Although previously reported such kind of fractional calculus-based constitutive models, it only handles the particularity of rational number in part, has great limitation by reason of only handling with particular rational number field. Simultaneously, the former study has great unreliability by reason of using the complementary error function which can't ensure uniform real number. In this paper, a new approach is proposed for an analytical scheme for dynamic system of a spring-mass-damper system of single-degree of freedom under general forcing conditions, whose damping is described by a fractional derivative of the order $0<{\alpha}<1$ which can be both irrational number and rational number. The new approach combines the fractional Green's function and Laplace transform of fractional derivative. Analytical examples of dynamic system under general forcing conditions obtained by means of this approach verify the feasibility very well with much higher reliability and universality.

• 대한수학교육학회지:수학교육학연구
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• 제25권3호
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• pp.263-279
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• 2015

유리수에서 실수로의 확장 혹은 무리수의 존재성을 수학적으로 정당화하기 위해서는 완비성 공리가 필요하므로, 실수의 도입은 학교수학에서 가장 가르치기 어려운 주제 중 하나이다. 이 연구에서는 실수를 '유리수와 무리수의 합집합'으로 정의하는 학교수학의 교수학적 변환이 어떠한 교수학적 공백을 남겨놓을 수 있는지를 살펴보고, 유리수에서 실수로의 수 체계 확장의 이유, 임의의 비순환 무한소수의 존재 이유 등에 대한 예비교사들의 설명을 분석하여 대학수학의 학습에도 불구하고 예비교사들의 실수에 대한 피상적인 이해를 구체적으로 확인하였다. 교수학적 공백을 인식하고 학교수학과 대학수학을 연결함으로서, 예비교사들이 실수 개념이 자명하다는 착각으로부터 어떻게 벗어날 수 있었는지를 논의하였다.

• 한국학교수학회논문집
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• 제25권4호
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• pp.375-396
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• 2022

본 연구에서는 2015 수학과 교육과정의 내용을 재구조화하여 새로운 교육과정을 다룰 때 학습량 적정화와 관련한 아이디어를 제공하기 위해 우리나라와 일본의 교육과정에서 차이가 있게 다루는 순환소수를 교육과정의 연계성 관점에서 살펴보고자 한다. 교육과정의 연계성은 수학 내적 연결성의 계통성과 공유성을 의미하며, 이를 바탕으로 우리나라 2015 개정 교육과정과 일본의 2017 개정 교육과정의 순환소수를 도입 시기, 내용, 다루는 방법 등을 비교하고, 두 나라의 중·고등학교 수학 교과서에서 이를 구체적으로 어떻게 다루는지 비교하였다. 연구결과, 우리나라는 무리수 개념 도입 전인 중학교 2학년에서 순환소수를 정의하고 순환소수와 유리수의 관계를 순환소수의 분수 표현으로 다루고 있었다. 반면 일본은 중학교 3학년에서 무리수를 학습한 후 순환소수의 용어를 간단히 다루고 고등학교 <수학I>에서 순환소수 개념을 다루고 <수학III> 교과목에서 극한 개념을 배울 때 유리수와 순환소수의 관계를 다루고 있었다. 이를 바탕으로 향후 교육과정 개정에서 학습량 적정화 등을 고려할 때 순환소수를 어떻게 다룰지 등에 대한 시사점을 제안하였다.

• 대한수학회지
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• 제56권4호
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• pp.985-1000
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• 2019

Let k be an integer with $k{\geq}3$. Define $h(k)=[{\frac{k+1}{2}}]$, ${\sigma}(k)={\min}\(2^{h(k)-1},\;{\frac{1}{2}}h(k)(h(k)+1)\)$. Suppose that ${\lambda}_1,{\ldots},{\lambda}_5$ are non-zero real numbers, not all of the same sign, satisfying that ${\frac{{\lambda}_1}{{\lambda}_2}}$ is irrational. Then for any given real number ${\eta}$ and ${\varepsilon}>0$, the inequality $${\mid}{\lambda}_1p^2_1+{\lambda}_2p^2_2+{\lambda}_3p^2_3+{\lambda}_4p^2_4+{\lambda}_5p^k_5+{\eta}{\mid}<({\max_{1{\leq}j{\leq}5}}p_j)^{-{\frac{3}{20{\sigma}(k)}}+{\varepsilon}}$$ has infinitely many solutions in prime variables $p_1,{\ldots},p_5$. This gives an improvement of the recent results.

• 한국도서관정보학회지
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• 제34권4호
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• pp.203-226
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• 2003

이 연구에서는 KDC 제4판의 언어류 관련부문에 있어서 제반 문제점을 지적한 다음, 그 개선책을 제시함으로써 KDC의 제5판 개정에 일조 하는데 그 의의를 두고 있는데, 연구 결과는 다음과 같다. 첫째, 언어공통구분(보조표)을 상세하게 전개하였는데, 언어류(700) 내에 $\ulcorner$내부 보조표$\lrcorner$로 위치시켜도 무방할 것이다. 둘째, 불합리하고 비논리적인 기호계층구조를 획기적으로 개선하였다. 셋째, 주기설정 미흡으로 분류 불가능한 경우가 발생하므로 꼭 필요한 다양한 분류주기를 설정하였다. 넷째, 불합리한 언어구분 전개를 수정ㆍ보완하였는데 국어구분표(보조표) 및 문학류(800)에도 적용되어야 할 것이다.

• 기술사
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• 제42권3호
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• pp.41-46
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• 2009

A new subway, line 9 linking Western and Eastern Seoul began its services for citizens between Gimpo airport and Gangnam area within 30 minutes by express transit service. Seoul Metro Line 9 Corporation plans to operate both local transit service which will stop at every station, and express transit service that will stop at several key stations including junctions. The passengers on line 9 will be able to transfer to lines 2, 3, 5, 8, Bundang and Incheon International Airport. The Line 9 is expected to disperse the demand for line 2, having the most number of subway users, and will provide passengers with less crowded travel. The new line will also help residents in southern Seoul outskirts and Gyeonggi provincial cities including Bundang vicinity, and Gangdong area commuters get better access to Gimpo and incheon Airports. The Corporation expects to transfer 560,000 passengers daily by the subway line 9. Seoul Development Institute conducted network reshuffle study for Seoul Metro system to sort out congestion problem due to its irrational line alignments and inconvenient transfer. Among several candidate plans of network reshuffling, the direct connection of line 9 with line 5 was chosen as a pilot study. The study found that direct connection of the 2 lines is essential for enhancing transit utility and reducing automobile commuters.

• 가정과삶의질연구
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• 제26권3호
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• pp.1-14
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• 2008

The purpose of the study was to examine the internet purchase behavior of items and self-assessment according to self-concept of elementary school students. The data were collected from 716 elementary school students by a self-administered questionnaire. Frequencies and means, Cronbach's Alpha, factor analysis, t-test, Pearson's correlation analysis, cross-tabulation analysis, cluster Analysis were conducted by SPSSWIN 12.0. The results from this study were as follows; First, from self-concept measurements, 4 factors(affective, social, schooling, Family self-concept) were extracted through factor analysis. Second, the subjects were classified into 3 clusters as self-concept types(high self-concept, middle self-concept, low self-concept) through cluster analysis. Third, the significant variables affecting internet purchase behaviors of items included grade, allowance, rank in class, the number of hours on the internet. As the self-concept gets higher, the frequence of the impulsive purchase and imitation purchases gets lower. In the contrary, as the self-concept gets higher, the self-assessment on the impulse purchases and imitation purchases also gets higher. In combination, these results suggest that irrational purchase behaviors were protected by positive self-concept, therefore it is important that children have positive a self-concept.

• Journal of Nutrition and Health
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• 제10권1호
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• pp.49-58
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• 1977

Nutrition counselors in Korea often encounter difficulty in their attempt to change village women's attitudes regarding food taboos which are counter to good eating habits. There are a great many food superstitions which are not due to religious influence, but seem to be related to shape and composition of food. Many expectant mothers superstitiously avoid eating certain foods for fear that they may cause mental or physical abnormality in their babies. As was shown in a previous survey (Mo, 1966)of villages in all provinces except Jeju Island, such superstitions were common among pregnant and lactating mothers. Many food taboos and superstitions based on non-scientific and irrational ideas do exist even in modern society, and are a major obstacle to nutritionally adequate food consumption. A study of food taboos among women of Jeju Island was undertaken from November to December of 1976, these results to be compared as well with those of the previous study. There were 73 items found to be prohibited during pregnancy. Of these, 48.7% were of the deaf group, 17.4% fish, 5.5% eggs, 4.7% cereal, and only 2.2% fruit. Of 252% women respondents, 111 (45% ) abstained from eating chicken, duck, and shark because of the belief that they would cause their babies to be born with gooseflesh or shark skin. Many of them avoided rabbit meat for fear that their babies might be born with harelip. It was also feared that a baby would become disfigured if his mother ate duck, goat, dog meat, chicken or duck eggs, or soup made of bones. A common superstition was that highly spiced or salty foods would cause the fetus to be hairless. Squid and octopus were believed to cause babies to have weak bones, or none at all. Most of these food taboos were associated with fears concerning Physical structure and appearance of unborn babies. Other taboos were associated with fear of undesirable behavioral characteristics. For example, some mothers thought that a baby would pinch or bite the mother's breast during the weaning period, if crab meat were eaten during pregnancy. Unevenly sliced rice cake, loach, snake meat and eel were also believed to cause a baby to be ill-tempered. The findings of this study are remarkably similar to those of the previous study conducted by the authour in 1966. Most of the same food taboos, based on non-scientific and irrational reasons, were found on Jeju Island as on the peninsula, and thor were similarly wide-spread. The results of correlational analysis show that the most significant factors related to prevalence of food taboos, are level of education and religious background. Number of food taboos is correlated with level of education. Also, food taboos are least freqent among the Christian woman. Proper nutrition education should he undertaken in order to encourage intake of protein-rich food, particularly during pregnancy when nutritional needs of mother and fetus are great.