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거리-시간 측정에 의한 고정도 타행시험법: Ⅱ.단거리 방법의 개발 및 시험
안이기(I.K.Ahn),허남건(N.Hur) 한국자동차공학회 1994 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
In the companion paper of the present paper, a coast down test method to determine the resistance forces on running vehicle based on the distance-time measurement was explained along with the suggestions to improve its accuracy and testing methodology.<br/> In the present paper some of the suggestions discussed previously are implemented and actually road tested to see the applicability of the improved method(short distance method) in the field. From the results, it is shown that. the short distance method which requires only 600m long proving ground road gives at least comparable results on the accuracy compared to the original S-t method which requires 2000m. It is hoped that the present method be further refined to give more accurate results.<br/>
안석기,정회윤,권선형,허남호,최동준,박성익,Ahn, S.K.,Jung, H.,Kwon, S.,Hur, N.,Choi, D.J.,Park, S.I. 한국전자통신연구원 2021 전자통신동향분석 Vol.36 No.4
Multimedia broadcast multicast services (MBMS) have evolved to accommodate broadcasting services in 3GPP standards. One long-standing approach is to comprise the multimedia broadcast multicast service single-frequency network based on the cellular networks of mobile operators, and another approach adds a broadcasting network to 3GPP standards. In this paper, we overview the MBMS architecture and key entities in MBMS services. In addition, the trends of MBMS are discussed in terms of technology and 3GPP standards, where MBMS functionality is described according to 3GPP releases. Finally, we discuss its capability through a comparison with ATSC 3.0, which is the latest terrestrial broadcasting standard, and then we present the current status and future perspectives of MBMS in 3GPP.
SiC/SiC 복합재료 기지재의 균열 폭에 따른 균열치유 특성
서임술(I. S. Seo),안우상(W. S. Ahn),남기우(K. W. Nam) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.11
SiC/SiC composites are among the most promising structural materials for fusion because of their potential application for high performance reactors and superior safety characteristics compared to metallic materials. And a recently developed SiC fiber, Tyranno-SA, was also used as the reinforcement in several SiC/SiC composites. In this study, we examined the relationship between various crack size and bending strength in order to analyze the mechanical properties under the room temperature. The mechanical properties and fracture behaviors were investigated using three-point bending test. we observed an aspect of crack-healing regarding both SiC/SiC composite ceramics and SiC monolithic ceramics as the matrix using a scanning electron microscope. And it was showed that crack healing effect by SiO₂ nano colloidal coating on SiC/SiC composite ceramics was not confirmed clearly. Therefore, we examined the crack-healing effect depending on the size of surface crack on SiC matrix, focusing on the strength recovery of the SiC ceramis as the matrix of SiC/SiC composite ceramics. As the result, It was found that the crack-healing behavior occurred effectively within a width of 1.4 ㎛, regardless of the crack length. And we improved the crack-healing effect, appling to the Hydrostatic Pressure Infiltration in SiO₂ nano colloidal coating method, repeatedly.