• 대한수학회보
• /
• 제49권2호
• /
• pp.423-434
• /
• 2012

In this paper we give a characterization of real hypersurfaces of type (A) in a complex two-plane Grassmannian $G_2(\mathbb{C}^{m+2})$ which is a tube over a totally geodesic $G_2(\mathbb{C}^{m+1})$ in $G_2(\mathbb{C}^{m+2})$, in terms of two commuting conditions related to the normal Jacobi operator and the shape operator.

• 대한수학회보
• /
• 제39권4호
• /
• pp.635-643
• /
• 2002

Our main goal is to show that if there exist Jordan derivations D and G on a noncommutative (n + 1)!-torsion free prime ring R such that $$D(x)x^n-x^nG(x)\in\ C(R)$$ for all $x\in\ R$, then we have D=0 and G=0. We also prove that if there exists a derivation D on a noncommutative 2-torsion free prime ring R such that the mapping $\chi$longrightarrow[aD($\chi$), $\chi$] is commuting on R, then we have either a = 0 or D = 0.

• 한국수학교육학회지시리즈B:순수및응용수학
• /
• 제11권4호
• /
• pp.287-292
• /
• 2004

The operator $A \; {\in} \; L(H_{i})$, the Banach algebra of bounded linear operators on the complex infinite dimensional Hilbert space $\cal H_{i}$, is said to be p-hyponormal if $(A^\ast A)^P \geq (AA^\ast)^p$ for $p\; \in \; (0,1]$. Let (equation omitted) denote the completion of (equation omitted) with respect to some crossnorm. Let $I_{i}$ be the identity operator on $H_{i}$. Letting (equation omitted), where each $A_{i}$ is p-hyponormal, it is proved that the commuting n-tuple T = ($T_1$,..., $T_{n}$) satisfies Bishop's condition ($\beta$) and that if T is Weyl then there exists a non-singular commuting n-tuple S such that T = S + F for some n-tuple F of compact operators.

• 대한교통학회:학술대회논문집
• /
• 대한교통학회 2007년도 제55회 학술발표회논문집
• /
• pp.181-190
• /
• 2007

본 연구는 기존의 통행수단선택에 관한 연구들이 주로 다룬 개인 및 가구의 사회경제적특성에 관한 변수를 비롯하여 통행이 발생하는 지역의 특성에 관한 여러 가지 변수를 고려하여 통행수단 선택에 미치는 영향을 알아보고자 한다. 분석대상은 첨두시와 비첨두시의 대표적인 목적통행인 출근통행과 쇼핑통행으로 삼았으며 승용차, 버스, 지하철에 관한 다항로짓모형을 이용하였다. 연구결과, 변수들이 목적통행별로 상이한 영향을 미쳤고, 지역특성변수들이 모형의 설명력을 높여준다는 것을 알 수 있었다.

• 대한수학회논문집
• /
• 제25권4호
• /
• pp.629-645
• /
• 2010

A metrical common fixed point theorem proved for a pair of self mappings due to Sastry and Murthy ([16]) is extended to symmetric spaces which in turn unifies certain fixed point theorems due to Pant ([13]) and Cho et al. ([4]) besides deriving some related results. Some illustrative examples to highlight the realized improvements are also furnished.

• 대한수학회보
• /
• 제53권5호
• /
• pp.1353-1362
• /
• 2016

Using the notion of complete nonabelian exterior square $G\hat{\wedge}G$ of a pro-p-group G (p prime), we develop the theory of the exterior degree $\hat{d}(G)$ in the infinite case, focusing on its relations with the probability of commuting pairs d(G). Among the main results of this paper, we describe upper and lower bounds for $\hat{d}(G)$ with respect to d(G). Here the size of the second homology group $H_2(G,\mathbb{Z}_p)$ (over the p-adic integers $\mathbb{Z}_p$) plays a fundamental role. A further result of homological nature is placed at the end, in order to emphasize the influence of $H_2(G,\mathbb{Z}_p)$ both on G and $\hat{d}(G)$.

• 지역연구
• /
• 제12권2호
• /
• pp.37-57
• /
• 1996

Intra-metropolitan spatial segmentation of the labor marker requires barriers of mobility on both supply and demand side of the local labor marker. The phenomena of spatial segmentation of the labor market are particularly applied to the secondary workers rather than to the primary workers. Supply side barriers include the costs of obtaining job information regarding jobs outside of the immediate area, commuting costs, and barriers to residential mobility. Demand side barriers include site-specific technology and product demand, and discrimination. In this paper, I discuss these barriers and examine their implications for differences in segmentation by demographic and skill groups at the intra-metropolitan scale. In particular, I apply a job search model to examine supply side barriers such as information and commuting costs, and an implicit contract model to explain demand side barriers such as dual/internal labor market and firms' (re) location strategies.

• 한국수학교육학회지시리즈B:순수및응용수학
• /
• 제20권3호
• /
• pp.181-198
• /
• 2013

C. Vetro [4] gave the concept of weak non-Archimedean in fuzzy metric space. Using the same concept for Menger PM spaces, Mishra et al. [22] proved the common fixed point theorem for six maps, Also they introduced semi-compatibility. In this paper, we generalized the theorem [22] for family of maps and proved the common fixed point theorems using the pair of semi-compatible and reciprocally continuous maps for one pair and R-weakly commuting maps for another pair in Menger WNAPM-spaces. Our results extends and generalizes several known results in metric spaces, probabilistic metric spaces and the similar spaces.

• 자원ㆍ환경경제연구
• /
• 제11권4호
• /
• pp.659-687
• /
• 2002

This study used a discrete choice model to investigate an association between air pollution and hospital visits for acute respiratory symptoms with the national health interview survey conducted in 1998 in South Korea. The results showed that $NO_2$ and TSP were significantly related to hospital visits in a single-pollutant model, but when they were simultaneously considered, only $NO_2$ remained significant. It was estimated as $NO_2$ level increased by 10%(0.0027ppm) from 0.027ppm (the mean $NO_2$ level), hospital visits increase by 0.176%. This study also measured respondent's out-of-pocket expense and the time cost for commuting and waiting for the visit. We found that on the average, out-of-pocket expense is 5,600 won per hospital visit, but the total cost per hospital visit is measured at 33,440 won with time cost of commuting and waiting at 27,840 won. Time cost was over 63.6~83.3% of the total cost per hospital visit.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2006년도 추계학술대회 논문집
• /
• pp.1581-1587
• /
• 2006

Today's subway system is packed with various informations such as danger/safety signs, directions, and tightly placed advertisements. All these elements are becoming one big chaos rather than convenient source of information for commuters. To solve this problem immediately, it has to be analysed for systematic character of subway spaces and leaded to constructive improvement for the locating subway signs in correct and convenient spots with right contents. Especially in case of transfer stations, structure is complicated and mazed. At the same time, tremendous amount of commuters are passing through and all these commuting are adding more complications and chaos to the system. Therefore, it is harder to focus on gathering environment informations and finding right directions. Better guiding signage for easier transfer is now essential for new standard of modern commuting with total and logical system. Eventually, it will be great help for setting budget efficiency and advanced subway environment through efficient and Koreanized subway transfer system.