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송재필,김기봉,정인근,김현호 中央大學校 建設環境硏究所 2002 環境科學硏究 Vol.13 No.2
무인궤도운전열차(Automated Guide-way Transit, AGT) 시스템의 접지력 및 교량-차량의 동적 응답을 구하기 위해 노면조도가 있는 주행로를 운행하는 AGT 시스템에 대한 동적 운동방정식을 유도하였다. AGT 시스템의 차량은 3차원 11 자유도 모델로 이상화하였고, 교량은 3차원 프레임 모델로 단순화하였다. 동적 운동방정식의 해를 구하기 위하여 컴퓨터 프로그램을 개발하였고, 해석된 결과는 실험자료의 결과치와 비교 분석하였다. 본 연구에서 개발된 프로그램의 해석결과 AGT 교량, 차량 그리고 노면요철의 상호 작용에 의한 교량과 차량의 동적 응답을 구하여 정밀한 교량의 동적증가계수를 산정할 수 있었다. The equations of motion for an automated guide-way transit(AGT) system running on a path with roughness have been derived to investigate dynamic responses and wheel loads of moving vehicles of the AGT system. A vehicle of the AGT system is idealized as three-dimensional model with 11 degree-of-freedom, and a bridge is modelized with three F.E. method. The computer program is developed to solve the dynamic equations, and analytical results are verified by comparing the results with experimental ones. As a result, the computer program which developed in this study can be used for estimate the dynamic responses of bridge and vehicle due to dynamic interaction of bridge, vehicle and surface roughness, and with these results the dynamic increment factor of bridge can be obtained.
송재필,이우현,김기봉 한국강구조학회 1996 韓國鋼構造學會誌 Vol.8 No.2
In this study, a method of increasement the capacity of existing simple span composite bridges, is developed using the post-tensioning. The distribution of post-tension force and flexural moment as well as feasibility increasing flexural capacity of simple span composite bridges are shown by numerical examples.
후긴장을 이용한 단순 합성 격차형교의 보강 방법에 관한 연구
김기봉,송재필 中央大學校 建設環境硏究所 1996 環境科學硏究 Vol.7 No.-
Bridges are designed according to the some kinds of design specifications that are current at the time of design. The design specifications are revised on a regular schedule, and changes are often on the direction of more stringent design standards. And, legal truck loads are increased, and the amount of traffic is increased. Therefore many bridges, that are built in few decades are ago, are needed strengthening. Add on that, deterioration due to lake of maintenance increase the needs of strengthening. One method of strengthening bridges is post-tensioning. In this study, a method of increasement the capacity of existing simple span composite bridges, is developed using post-tensioning. The distribution of post-tensioning force and moment as well as feasibility increasing flexural capacity of simple span composite bridges are shown by numerical examples.
TYFO를 이용한 R.C. 슬래브 보강기법에 관한 연구
김기봉,정영수,송재필 中央大學校 建設環境硏究所 1997 環境科學硏究 Vol.8 No.-
Recently, glassfibers have been used for strengthening in aged RC bridge slabs because of low material cost and easy repairing work. The purpose of this study is to experimentally and analytically investigate the effect of glassfibers for enhancing the capacity of aged RC bridge slabs. The Result shows that yield and ultimate strength of RC slabs with glassfibers are increased as 11~18% and 25~35% comparing with those for RC slabs without strengthening, respectively. Also, ductility of RC slabs strengthened with glassfibers have been significantly increased. Futher tests have been performing on aged RC bridge slabs strengthened with carbon fiber stripes.
친수성 고분자로 코팅한 탄소나노튜브/폴리스티렌 나노복합재료의 유변물성 및 전기적 물성
송재필(Jae Phil Song),김준영(Jun Young Kim),이성재(Seong Jae Lee) 한국고분자학회 2017 폴리머 Vol.41 No.4
폴리스티렌(PS)/표면 개질한 탄소나노튜브(CNT) 나노복합재료를 제조하고 유변물성과 전기적 물성을 고찰하였다. CNT의 표면 개질은 친수성 고분자인 polydopamine(PDA)과 poly(3,4-ethylenedioxythiophene):poly(4-styrene sulfonate)(PEDOT:PSS)로 코팅하는 물리적 방법을 사용하였다. PS/CNT 나노복합재료는 PS 미세 입자와 표면 개질한 CNT를 수상 매질에 분산시킨 후 동결건조하는 라텍스 기법을 활용하여 제조하였다. 이 방법은 나노복합재료의 CNT 분산 및 전기 전도도 향상에 매우 효과적이었다. 친수성 고분자로 코팅한 CNT인 PDA-CNT와 PEDOT:PSS-CNT를 소량 첨가한 경우에도 나노복합재료의 저장 탄성률(G")이 급격히 증가하였는데 이는 PS 매트릭스 내 CNT가 안정적으로 분산되었다는 것을 의미한다. PDA-CNT와 PEDOT:PSS-CNT를 첨가한 나노복합재료의 전기적 임계값은 각각 0.58과 0.32 wt%로 나타났다. PEDOT:PSS로 표면 개질한 CNT의 경우가 전기 전도도 향상 효과가 우수하였는데 이는 CNT를 감싸고 있는 전도성 고분자인 PEDOT:PSS가 CNT간의 전기적 연결에 도움을 주었기 때문으로 판단된다. Polystyrene (PS) nanocomposites containing surface-modified carbon nanotubes (CNTs) were prepared and their rheological and electrical properties were investigated. CNTs were modified with hydrophilic polymers such as polydopamine (PDA) and poly(3,4-ethylenedioxythiophene):poly(4-styrene sulfonate) (PEDOT:PSS). The nanocomposites were prepared via latex technology through which PS particles and CNTs were mixed in aqueous medium and freezedried. This method was very effective in dispersing the CNTs and enhancing electrical conductivity. Storage moduli were substantially increased with a small addition of the CNTs, which indicates they were stably dispersed in PS matrix. Electrical percolation threshold of the nanocomposites containing PDA-CNTs and PEDOT:PSS-CNTs was 0.58 and 0.32 wt%, respectively, and the latter was more effective in enhancing the conductivity. It seems certain that PEDOT:PSS, a conducting polymer, helped in forming an electrical pathway between CNTs.