• 한국경영과학회지
• /
• 제15권2호
• /
• pp.97-104
• /
• 1990

The problem is a variation of the weighted set-covering problem (SCP) which requires the minimum-cost cover to be self-covering. It is shown that direct extension of the well-known greedy heuristic for SCP can have an arbitrarily large error in the worst case. It remains an open question whther these exists a greedy heuristic with a finite error bound.

• Korean Journal of Mathematics
• /
• 제25권3호
• /
• pp.437-453
• /
• 2017

A new class of sets, called generalized (${\Lambda}$, b)-closed sets, has been introduced and studied. Also, several properties of generalized (${\Lambda}$, b)-closed sets are investigated. Some characterizations of ${\Lambda}_b$-regular spaces and ${\Lambda}_b$-normal spaces are discussed.

• 대한수학회논문집
• /
• 제33권4호
• /
• pp.1181-1203
• /
• 2018

In this paper, we are mainly devoted to find out the general meromorphic solution of some specific type of differential equation. We have also answered an open question posed by Banerjee-Chakraborty [4] by extending their results in a large extent. We have provided an example showing that the conclusion of the results of Zhang-Yang [16] is not general true. Some examples have been exhibited to show that certain claims are true in our main result. Finally some questions have been posed for the future research in this direction.

• 지식정보인프라
• /
• 통권9호
• /
• pp.8-19
• /
• 2002

The Dublin Core element set has been developed over the past years as an open, consensus-building metadata from many user communities. Wider adoption in many countries made this metadata a major resource discovery standard on the internet. The version 1.1 of the Dublin Core element set was adopted as CEN Workshop Agreement 13874 in Europe, and also ratified under the auspices of the National Information Standards Organization in US as ANSI Standard Z39.85. This report summarizes the standardization activities that have taken place in the Dublin Core Metadata Initiative for the past years.

• 한국지능시스템학회논문지
• /
• 제20권4호
• /
• pp.569-573
• /
• 2010

fuzzy r-minimal preopen set, fuzzy r-M precontinuous와 fuzzy r-M preopen 함수의 개념을 소개하며 특성들을 조사한다.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2011년도 제42회 하계학술대회
• /
• pp.1382-1383
• /
• 2011

결정질 실리콘 태양전지에서 전극 형성 공정은 Voc(Open-circuit voltage), Isc(Short-circuit current), Rser(Series resistance), Rshunt(Shunt resistance), FF(Fill factor) 특성에 영향을 주기 때문에 매우 중요하다. 하지만 paste와 선 공정에서의 조건에 따라 특성이 바뀌기 때문에 소성 공정을 최적화하기는 쉽지 않다. 본 연구에서는 Gravure Off-set printing 방식을 이용하여 결정질 실리콘 기판 표면에 미세 전극 형성 공정을 하고 소성 조건 최적화를 위해 peak 온도와 ramp-up 속도를 변화시켜 각 조건별 특성을 비교하였다. Peak 온도가 커질수록, contact resistance의 감소에 따라 Rser가 줄어들었다. 본 연구를 통해 Voc는 619mV, FF는 77.9%로 측정되는 Gravure Off-set 태양전지에 최적화된 소성 공정 조건을 확보하였다.

• 대한수학회논문집
• /
• 제11권3호
• /
• pp.665-672
• /
• 1996

Let U denote the set of all Schwarzian derivatives $S_f$ of conformal function f in the unit disk D. We show that if $S_f$ is a local extreme point of U, then f cannot omit an open set. We also show that if $S_f \in U$ is an extreme point of the closed convex hull $\bar{co}U$ of U, then f cannot omit a set of positive area. The proof of this uses Nguyen's theorem.

• 대한수학회보
• /
• 제59권1호
• /
• pp.167-177
• /
• 2022

A vertex v of a graph G = (V, E) is said to ve-dominate every edge incident to v, as well as every edge adjacent to these incident edges. A set S ⊆ V is called a double vertex-edge dominating set if every edge of E is ve-dominated by at least two vertices of S. The minimum cardinality of a double vertex-edge dominating set of G is the double vertex-edge domination number γ_dve(G). In this paper, we provide an upper bound on the double vertex-edge domination number of trees in terms of the order n, the number of leaves and support vertices, and we characterize the trees attaining the upper bound. Finally, we design a polynomial time algorithm for computing the value of γ_dve(T) for any trees. This gives an answer of an open problem posed in [4].

• 인터넷정보학회논문지
• /
• 제18권2호
• /
• pp.1-11
• /
• 2017

스마트 디바이스를 이용하여 특정 공간에서 미리 설정된 무선랜에 접속하는 방법은 개방형 방식과 사용자 인증 방식으로 나뉠 수 있다. 개방형 방식은 무선랜 접속을 위한 인증이 없이 접속하는 방법이다. 스마트 디바이스 사용자가 자신이 사용하려는 무선랜에 대한 정보를 SSID(Service Set IDentifier)를 통해 공공 무선랜 표기 형식에 따라 제공받아야 하지만, 모든 개방형 무선랜이 이러한 방식을 수동으로 입력하는 방식에는 무리가 있다. 반면에 사용자 인증 방식은 SSID와 PW(PassWord) 설정을 통해 사용자에게 무선랜 접속을 제공하는 방식이다. 따라서 SSID를 통해 공공 무선랜 표기 형식을 따를 수는 있지만, AP 접속을 위해서는 일일이 사용자가 수동으로 패스워드 입력을 통해 AP에 접속해야만 한다. 따라서 본 논문에서는 사용자 인증방식과 공공 무선랜 표기형식을 iBeacon 메시지 수신을 통해 자동적으로 AP에 접속할 수 있는 방안을 제안한다.

• 한국IT서비스학회지
• /
• 제21권4호
• /
• pp.1-26
• /
• 2022

Recently, the number of cases of purchasing food online has been increased, especially in the open market. Therefore, we examined the characteristics of status quo bias and switching costs in the open market. Also, in this study, the causal relationship between the characteristics of status quo bias and switching costs, switching costs and switching intention in the open market was investigated. The analysis result consists of four parts as follows. First, in the open market, rational decision making, which belongs to the characteristics of status quo bias, was found to have a positive (+) effect on time switching cost among switching costs, but did not have a positive (+) effect on economic and psychological switching cost. Second, cognitive misperceptions was consistent with the assumption that it have a positive (+) effect on all of the economic, time, and psychological switching cost, which are switching costs in the open market. Third, psychological commitment was found to have a positive (+) effect on economic and time switching cost among switching costs, but did not have a positive (+) effect on psychological switching cost. Fourth, psychological switching cost, which belongs to switching costs in the open market, was found to have a negative (-) effect like the hypothesis set in switching intention. However, it was found that economic and time switching cost did not have a negative (-) effect on switching intention. This study subdivided the switching costs into three dimensions and compared the degree of influence on the switching intention, and the degree of influence was different for each dimension. Therefore, it was found that when switching from the existing open market to the new open market, it is not possible to simply judge that the switching costs directly has a negative (-) effect on the switching intention or does not.