• Journal of the Korean Mathematical Society
• /
• v.36 no.4
• /
• pp.747-756
• /
• 1999

In ring theory it is well-known that a ring R is (von Neumann) regular if and only if all right R-modules are flat. But the analogous statement for this result does not hold for a monoid S. Hence, in sense of S-acts, Liu (]10]) showed that, as a weak analogue of this result, a monoid S is regular if and only if all left S-acts satisfying condition (E) ([6]) are flat. Moreover, Bulmann-Fleming ([6]) showed that x is a regular element of a monoid S iff the cyclic right S-act S/p(x, x2) is flat. In this paper, we show that the analogue of this result can be held for automata and them characterize regular semigroups by flat automata.

• Journal of the Korean Society for Precision Engineering
• /
• v.13 no.12
• /
• pp.136-141
• /
• 1996

In this paper, the design variables of the extruded parts involving flat die through model experiment are investigated to overcome some current problems such as bending and twisting and get more improved quality products. Above all, the deformation behavior is analyzed in experiment and investigated flow charactristics inside container. Finally, the straight extruded product is obtained by modified bearing land width on the basis of the exit velocities distribution from bended and twisted products.

• Proceedings of the KIPE Conference
• /
• 2004.07b
• /
• pp.709-712
• /
• 2004

본 논문에서는 고밀도 전원 장치에 적합한 플랫 트랜스포머(Flat Transformer)를 사용하여 다양한 출력을 갖는 AC/DC 변환장치의 설계 예를 제시하였다. 기존의 트랜스포머에 비해 플랫 트랜스포머는 다수의 트랜스포머를 병렬로 구성하여 제작하고, 이차 권선이 항상 1턴으로 구성되므로 누설 인덕턴스가 크게 감소하게 되어 고주파 스위칭에 적합한 형태를 가지고 있다. 일차측 AC/DC 변환기는 고조파 규제를 만족시키기 위해 경계 모드 (Boundary Mode)에서 동작하는 역률 보상회로로 구성하여 설계하였으며, 이차측 DC/DC 변환기는 플랫 트랜스포머에 적당한 하프 브리지(Half-Bridge) 컨버터를 적용하였다. 본 논문에서는 500W급 AC/]DC 변환기를 구성하여 다양한 출력을 갖는 전원 장치를 설계/제작하였다.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2005.07b
• /
• pp.1161-1164
• /
• 2005

A Mercury-free, flat light source which shows high luminance and luminous efficiency simultaneously has been developed. An electrodeless, dielectric barrier discharge is used to generate the plasma using Ne-Xe mixture gas of relatively low gas pressure of a few tens torr in a 4.1 inch diagonal size of flat panel. The basic properties of the long gap glow discharge and its accompanying instabilities, which prevents us from having high luminous efficiency discharge have been analyzed. A new structure and optimized driving methods have been used to generate a glow discharge which shows a wide voltage margin of a few hundred volts. The luminous efficiency and luminance could be 110 lm/W at $1300\;cd/m^2$ and 50 lm/W at $5500\;cd/m^2$.

• Communications of the Korean Mathematical Society
• /
• v.38 no.4
• /
• pp.1271-1280
• /
• 2023

The object of the present paper is to introduce a type of non-flat Riemannian manifold, called a weakly cyclic generalized B-symmetric manifold (W CGBS)_n. We obtain a sufficient condition for a weakly cyclic generalized B-symmetric manifold to be a generalized quasi Einstein manifold. Next we consider conformally flat weakly cyclic generalized B-symmetric manifolds. Then we study Einstein (W CGBS)_n (n > 2). Finally, it is shown that the semi-symmetry and Weyl semi-symmetry are equivalent in such a manifold.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2012.10a
• /
• pp.955-956
• /
• 2012

• 한국정보디스플레이학회:학술대회논문집
• /
• 2003.07a
• /
• pp.126-129
• /
• 2003

Electron beam guides hold the promise of a flat-panel display based on CRT technology. We propose to integrate the periodic focusing electrodes of such beam guides on a glass channel plate for a robust and simple design. The feasibility of this idea is tested numerically and experimentally.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2011.06a
• /
• pp.1501-1502
• /
• 2011

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2010.11a
• /
• pp.603-604
• /
• 2010

• Communications of the Korean Mathematical Society
• /
• v.38 no.1
• /
• pp.97-112
• /
• 2023

In this paper, we introduce and study the u-S-weak global dimension u-S-w.gl.dim(R) of a commutative ring R for some multiplicative subset S of R. Moreover, the u-S-weak global dimensions of factor rings and polynomial rings are investigated.