• 대한수학회보
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• 제29권2호
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• pp.277-283
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• 1992

Let GF(q) be a finite field with q elements where q=p$^{n}$ for a prime number p and a positive integer n. Consider an arbitrary function .phi. from GF(q) into GF(q). By using the Largrange's Interpolation formula for the given function .phi., .phi. can be represented by a polynomial which is congruent (mod x$^{q}$ -x) to a unique polynomial over GF(q) with the degree < q. In [3], Wells characterized all polynomial over a finite field which commute with translations. Mullen [2] generalized the characterization to linear polynomials over the finite fields, i.e., he characterized all polynomials f(x) over GF(q) for which deg(f) < q and f(bx+a)=b.f(x) + a for fixed elements a and b of GF(q) with a.neq.0. From those papers, a natural question (though difficult to answer to ask is: what are the explicit form of f(x) with zero terms\ulcorner In this paper we obtain the exact form (together with zero terms) of a polynomial f(x) over GF(q) for which satisfies deg(f) < p$^{2}$ and (1) f(x+a)=f(x)+c for the fixed nonzero elements a and c in GF(q).

• Kyungpook Mathematical Journal
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• 제50권2호
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• pp.213-228
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• 2010

A weighted version of the geometric mean of k ($\geq\;3$) positive invertible operators is given. For operators $A_1,{\ldots},A_k$ and for nonnegative numbers ${\alpha}_1,\ldots,{\alpha}_k$ such that $\sum_\limits_{i=1}^k\;\alpha_i=1$, we define weighted geometric means of two types, the first type by a direct construction through symmetrization procedure, and the second type by an indirect construction through the non-weighted (or uniformly weighted) geometric mean. Both of them reduce to $A_1^{\alpha_1}{\cdots}A_k^{{\alpha}_k}$ if $A_1,{\ldots},A_k$ commute with each other. The first type does not have the property of permutation invariance, but satisfies a weaker one with respect to permutation invariance. The second type has the property of permutation invariance. We also show a reverse inequality for the arithmetic-geometric mean inequality of the weighted version.

• 호남수학학술지
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• 제27권3호
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• pp.487-504
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• 2005

Let M be a real hypersurface with almost contact metric structure (${\phi}$, ${\xi}$, ${\eta}$, g) in a nonflat complex space form $M_n(c)$. We denote by A and S be the shape operator and the Ricci tensor of M respectively. In the present paper we investigate real hypersurfaces with $g(SA{\xi},\;A{\xi})=const$. of $M_n(c)$ whose structure Jacobi operator $R_{\xi}$ commute with both ${\phi}$ and S. We give a characterization of Hopf hypersurfaces of $M_n(c)$.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2006년도 추계학술대회 논문집
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• pp.56-61
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• 2006

For the safety of railway, it should be evaluated for the running safety by measuring the derailment coefficient. Although railway has run the fixed and maintained rail, some of railway is derailed. This report shows the results that performed the static load test, wheelset manufacturing for test, main line running test on the basis of the derailment theory and experience. It is executed main line test into more than 110km/h for estimating the running safety of Incheon Int'l Airport EMU. As the test results, could confirm the curving performance and running safety of Incheon Int'l Airport EMU from the results of the wheel unloading, lateral force, derailment coefficient etc. Derailment coefficient was less than 0.8, and lateral force allowance limit and wheel load reduction ratio were enough safe.

• 교육시설
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• 제11권5호
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• pp.5-13
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• 2004

To develop a master plan of a university campus, we need to know how students view and use their campus. For this purpose, the well-known Linch's(1960) cognitive mapping methods are used to figure out the image of Yonsei University and its surrounding area which is perceived by the students of Yonsei University. Major findings are that the cognition levels for the edge which divides Yonsei University from the surroundings and the paths which the students commute along are relatively high. The students mainly use campus space near the main gate rather than the space deep inside of the university, which shows they use the campus space unevenly. Therefore, when considering a new master plan of Yonsei University, it is needed to develop methods which increase the even use of the campus space such as developing new commuting paths.

• Kyungpook Mathematical Journal
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• 제56권2호
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• pp.387-396
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• 2016

An $n{\times}n$ matrix A over a commutative ring is strongly clean provided that it can be written as the sum of an idempotent matrix and an invertible matrix that commute. Let R be an arbitrary commutative ring, and let $A(x){\in}M_n(R[[x]])$. We prove, in this note, that $A(x){\in}M_n(R[[x]])$ is strongly clean if and only if $A(0){\in}M_n(R)$ is strongly clean. Strongly clean matrices over quotient rings of power series are also determined.

• Kyungpook Mathematical Journal
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• 제56권2호
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• pp.541-575
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• 2016

Let M be a real hypersurface of a complex space form with almost contact metric structure (${\phi}$, ${\xi}$, ${\eta}$, g). In this paper, we prove that if the structure Jacobi operator $R_{\xi}= R({\cdot},{\xi}){\xi}$ is ${\phi}{\nabla}_{\xi}{\xi}$-parallel and $R_{\xi}$ commute with the structure tensor ${\phi}$, then M is a homogeneous real hypersurface of Type A provided that $TrR_{\xi}$ is constant.

• 자동차안전학회지
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• 제10권4호
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• pp.50-53
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• 2018

Some local government, community rehabilitation center, special school operate buses which can be used by wheel chair user in order to commute. However, there are no regulations or laws for safety management of buses and its wheel chair lifts. To prevent discrimination among the physically challenged people, government of Korea plan to supply buses which wheel chair users are able to on board. Safety management system should be prepared to ensure safe and convenient use of express and intercity buses for wheel chair users. In this study, domestic and international standards and regulations of wheel chair lift are thoroughly reviewed and based on this research, national safety standards for wheelchair lift are suggested for the future.

• 한국ITS학회 논문지
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• 제15권3호
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• pp.94-104
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• 2016

본 연구는 인천광역시의 행정동을 특성에 따라 요인분석과 군집분석을 통하여 유형화 하였다. 그리고 유형별로 통행특성을 분석하여 교통계획의 방향성을 제시하였다. 그 결과 인천광역시의 행정동은 5개의 군집으로 유형화 되었으며 그 특징은 다음과 같다. 첫째, 공업이 발달한 행정동은 승용차를 이용한 출근통행량이 많고 장거리통행이 높게 나타나 출근시차제 및 신호운영정책이 필요한 것으로 분석되었다. 둘째, 상업이 발달한 행정동은 대중교통 이용율이 높고, 장거리의 출근 및 쇼핑 통행량이 많은 특징이 있어 도로의 인프라 개선이 필요한 것으로 분석되었다. 셋째, 인구가 밀집된 행정동은 출근 및 등교통행의 비율이 높고 통행시간이 긴 특징이 있어 출퇴근 시간의 교통개선정책이 필요한 것으로 분석되었다. 넷째, 도시의 특성이 복합적인 행정동은 도보를 이용한 행정동 안에서의 통행이 높은 특징이 있어 보행환경개선정책이 필요한 것으로 분석되었다. 마지막으로 전철역과의 접근성이 높은 행정동은 자전거 이용이 높고 쇼핑 및 등교통행이 많은 특징이 있어 접근성 강화를 위한 계획이 필요한 것으로 분석되었다.

• 대한교통학회지
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• 제32권4호
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• pp.347-356
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• 2014

우리나라에서 자가용 승용차는 전체등록차량의 약 74%의 정도를 차지하고 있고, 여객수송부문에서 차지하는 수단 분담비율도 약 60%(도보, 자전거, 기타 제외) 정도를 차지하는 주요 교통수단이다. 하지만, 자가용 승용차관련 보유 및 이용 관련한 통계는 전무한 상태일 뿐만 아니라, 분담율 산정의 기준이 되는 인-km 수송실적 자료조차 여객기종점통행량을 기초로 추정한 값을 사용하고 있다. 이에 한국교통연구원 국가교통DB센터는 '자가용이용실태조사'를 통해 자가용 승용차의 이용 및 보유관련 다양한 통계자료를 구축하고자 하였으며, 본 연구에서는 '자가용이용실태조사'를 통해 구축된 통행자료 기반으로 가구인별 통행특성 차이를 분석하기 위해 ANOVA(Analysis of Variance)를 실시하였다. 분석 결과, 가구 규모별로 모든 설명요인(주중 vs. 주말, 수도권 vs. 비수도권, 남성 vs. 여성, 출퇴근 시간 vs. 기타시간, 일상 vs. 비일상)간 차이가 있는 것으로 분석되었으며, 주말보다 주중이, 비수도권보다 수도권에서, 여성보다 남성이, 출퇴근 시간이 기타시간보다, 비일상 통행보다 일상통행의 경우 통행당 거리가 길게 나타났다. 특히, 소인가구의 통행당 거리가 다인가구에 비해 상대적으로 짧게 나타나고 있음을 알 수 있었다.