• Communications of the Korean Mathematical Society
• /
• v.35 no.2
• /
• pp.447-454
• /
• 2020

The studies of reversible and NI rings have done important roles in noncommutative ring theory. A ring R shall be called QRUR if ab = 0 for a, b ∈ R implies that ba is contained in the upper nilradical of R, which is a generalization of the NI ring property. In this article we investigate the structure of QRUR rings and examine the QRUR property of several kinds of ring extensions including matrix rings and polynomial rings. We also show that if there exists a weakly semicommutative ring but not QRUR, then Köthe's conjecture does not hold.

• Proceedings of the KIEE Conference
• /
• 2000.07a
• /
• pp.206-208
• /
• 2000

Manual generation of the relay setting summary could involve fatal errors which would result in the big damage to the system. This paper reports the automatic generation system of relay setting reports. Analysing the manual reports of various relays the almost unified format has been designed. The developed system utilizes the graphics and tabular format to enhance the user understanding.

• Korean Journal of Crystallography
• /
• v.10 no.1
• /
• pp.28-32
• /
• 1999

The title compound consisting of a calix[4]arene molecule with four phenyl rings arranged alternately in anti-orientation fashion, two propyloxy groups attached on the upper rim of calix[4]arene, and polyther chain with two phyenyl rings attached on the lower rim of calix[4]arene offers a big cavity inside a molecule with might a potential for forming host-guest complexes.

• Proceedings of the KSME Conference
• /
• 2003.04a
• /
• pp.1663-1666
• /
• 2003

TMA clathrate that is used by PCM of ice storage system in this research creates hydrate crystallization at higher temperature than pure water, and application is expected as PCM because having comparative big dormant temperature without phase separation phenomenon. In case this research uses TMA clathrate by PCM, choose admixture by purpose to control or remove subcooling of TMA clathrate and evaluated experimentally. Subcooling is improved and can expect contraction of freezing machine running time and increase of coefficient of performance as that add admixture to TMA clathrate conclusively. Also, may supply thermal storage system that apply low temperature potential heat thermal storage material that subcooling is improved more extensively laying stress on medium size building and small size building, can expect allowance through localization of ice storage system.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1992.10a
• /
• pp.166-171
• /
• 1992

Mechanical seals are generally used in the fields of industries as sealing devices. The failure of mechanical seals like crack, leakage, breakage fast and severe wear, excessive torque, and squeaking result in big problems. For the development of monitoring system, this study was carried out to identify abnormal phenomina on alumina(AI $\_$2/ O /sub3/) seal ring and resin bonded carbon ring, and to propose the proper parameter for monitoring failure on mechanical seals. Sliding were tests are conducted at 12 experimental conditions that contains 3 different contact pressure and 4 surface conditions. Torque, temperature, and acoustic emission are measured. Optical microstructure and scanning electron microscopy are observed for the wear processing every 10 minute sliding at rotation speed of 1750 RPM.

• Proceedings of the Korea Inteligent Information System Society Conference
• /
• 2006.06a
• /
• pp.344-353
• /
• 2006

Nowadays many people participate in online communities for information sharing. But most recommender systems are designed for personalization of individual user, so it is necessary to develop a recommendation procedure for group users, such as participants in online communities. This paper proposes a group recommender system to recommend books for group users in online communities. For such a purpose, we suggest a group recommendation procedure consisting of two phases. The first phase is to generate recommendation list for 'big user' using collaborative filtering, and the second phase is to remove irrelevant books among previous list reflecting the preference of each individual user. The procedure is explained step by step with an illustrative example. And this procedure can potentially be applied to other domains, such as music, movies and etc.

• Proceedings of the KSME Conference
• /
• 2003.11a
• /
• pp.250-255
• /
• 2003

TMA clathrate that is used as PCM of low temperature thermal storage system in this research creates hydrate crystallization at higher temperature then pure water, and its application is expected as PCM because of comparatively big latent heat without phase separation phenomenon. Acetone, Ethylen Glycol, and Ethanol is used as additive and evaluated experimentally for the purpose of the improvement in subcooling of TMA clathrate. In view of the results so far achieved subcooling is improved, the running time of the refrigerator is reduced. Thus the results are expected to use for the increase of coefficient of performance of low temperature thermal storage system in the building.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2012.05a
• /
• pp.101-102
• /
• 2012

A policy for recycling waste concrete has been extensively studied, but it is still lacking to recycle and reuse as a cementitious powder, and the property has big different depending on the aggregate rates. In this study, the amount of cement powder according to the internal properties of the aggregate were mixed. From as a result, Concrete Powder to play inside the aggregate composition of the cement composition CaO rigs that causes loss of power and strength reduction due to rising real water cement ratio will affect large.

• Proceedings of the KIEE Conference
• /
• 2002.11c
• /
• pp.422-425
• /
• 2002

Position balance control refers to ability that is kept bodily center of gravity under minimum position shake on surface of land. Patients who an injury of brain, a wound of the central nervous system or weakening of leg muscular power is fallen are trend increasing steadily by the car accident body balance function is on an increasing trended. These patients have difficulty in position balance control, receive big restriction walk and life style. This research composed to do body balance function rehabilitation training which elevate leg muscular power using step machine. And expect to become effective rehabilitation training device because measuring bodily pressure center using Force Platform and do so that can confirm training result easily as that is monitor.

• Proceedings of the KIEE Conference
• /
• 2004.10a
• /
• pp.116-119
• /
• 2004

According to industrial development, all fields using chemical instrument and material are generated an electrostatics. This paper is represented the electrostatics distribution analysis of industrial type Inkjet plotter. In order to such experiment, an electrostatics for each portions of plotter(OJ-62) are measured by electrostatic measurement. Based on these, the big large position of electrostatics was analyzed by finite element method(Maxwell-2D), Here it is showed an electrostatic inducement and electric charge theory required.