시멘트 제조사 및 W/C 변화에 따른 콘크리트의 초기 강도발현 특성

金光華,裵正烈,김규도,이승훈,한천구 대한건축학회 2003 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.23 No.1(구조계)

This study is to investigate the influence of cement manufacturing company and W/C on the properties of fresh concrete, strength of hardened concrete and rebound value of P type Schmidt hammer. According to the result, setting time of concrete is shortened with and increase of W/C, and when cement made in A and B corporation is used in concrete, the final setting time is measured at about 10 hours and 13 hours. Compressive strength increases with elapse of time and decrease of W/C, and concrete using cement made in A corporation shows higher compressive strength and rebound value until 24 hours, but from 3rd day, the contrary tendency is shown. As for the properties of early strength, the strength develop fast with decrease of W/C, and the time when compressive strength of 5MPa is gained and the form can be removed, is about 15, 18, 21 hours and 20, 22, 27 hours at the W/C 40, 45, 50% in concrete using cement made in A and B Co. respectively. The correlativity between compressive strength and the rebound value, which a coefficient of correlation is over 0.97, is very favorable. Therefore this method is effective to estimate the strength of removing the form.

트리에탄올아민의 혼입률 변화에 따른 콘크리트의 초기 강도발현 특성

황인성,金光華,김규동,이승훈,한천구 대한건축학회 2003 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.23 No.1(구조계)

In this study, the influence of TEA on early strength development of concrete is discussed in order to reduce a construction period in RC structure by early removal of forms. According to the results, as for the properties of fresh concrete, fluidity of concrete shows no difference, and air content increases with an increase of the mixing ratio of TEA. Setting time is shortened upto mixing ratio of 0.025%, but is retarded above the mixing ratio of 0.025%. The time when compressive strength gains 5MPa is fast in about 2 hours in the case of the mixing ratio of 0.05%, but it is retarded above the mixing ratio of 0.05%. The relativity between compressive strength and the rebound value of P-type Schmidt hammer is also favorable at early age, and compressive strength of 5MPa, which the side forms can be removed, is estimated at the rebound value of 23.

류마티스 관절염과 전신경화증의 중복증후군 1예

이은지,서광원,유충헌,박봉수,허민영,김지현,김혜란,김동욱 인제대학교 2008 仁濟醫學 Vol.29 No.-

Overlap syndrome is a disease that combines major features of more than one rheumatic disease in the same patient. A 58 year-old female who was diagnosed as rheumatoid arthritis (RA) developed skin thickening and dyspnea. Clinical and laboratory findings revealed that she was affected by systemic sclerosis (SSc) and interstitial lung disease. Finally, she was diagnosed as overlap syndrome consistent with RA combined with SSc. The authors report a case of RA-SSc overlap syndrome with relevant literatures.

활성탄에 의한 Polysilane의 분자량 조절

천종현,최광진,박동호 인제대학교기초과학연구소 2002 자연과학 Vol.6 No.-

SiC-fiber의 전구체로 쓰이는 polymethylsilane(PMS), polydimethylsilane(PDMS),polyemthylphenylsilane(PMPS)은 Na촉매 하에 dichloro-organosilanes의 탈 염소화 반응으로 합성된다. 유기용매에 잘 녹는 PMPS를 이용하여 온도, 시간, 첨가제의 농도에 따른 수율과 평균분자량을 조사하였으며,고온에서의 잔류량을 확인하였다. PMPS의 합성시간이 증가할수록 수율과 분산도가 증가하였고 평균분자량이 감소하였다. 활성탄을 첨가하여 합성 시 PMPS은 높은 평균 분자량을 가졌다. Na/C=0.05 첨가 시까지 평균 분자량이 높아졌고, 고분자 분산도는 균일했다. Na/C=0.1 첨가 시 분자량과 분산도가 크게 증가했다. PMPS의 고온 잔류량은 활성탄의 첨가량을 많이 하고, 첨가 후 반응 시간을 늘려줄수록 증가하였다. 반응 시 첨가되는 활성탄의 양과 합성시간을 조절함으로 PMPS의 평균 분자량을 조절할 수 있었다. Polymethylsilane(PMS), polydimethylsilane(PDMS),polyemthylphenylsilane(PMPS), which were used as a precursor of SiC-fiber, were synthesized by dehalocoupling were dichloro-organosilanes using Na as a reductant. By using the PMPS which is easily melted at organic solvent, investigated how yield, average molecular weight and remaining quantity in high temperature be influenced by temperature, time and concentration of additive. When reaction time of PMPS became longer, yield and polydispersity were increased and average molecular weight was decreased. synthesis of PMPS with active carborn as an additive showed high average molecular weight was high while polydispersity was regular. In case of Na/C=0.1, average molecular weight and polydispersity was remarkably increased. Residual quantity in high temperature of PMPS was increased in lots of active carborn and long reaction time. Average molecular weight of PMPS can be controlled by reaction time and amount of active carborn added in polymerization.

One-Pot Conversion of Trimethylsilyl Ethers into Urethanes Using Chlorosulfonyl Isocyanate: Application to the Synthesis of a Novel Neuromodulator Carisbamate

Dong, Guang-Ri,Li, Qing-Ri,Woo, Seol-Hee,Kim, In-Su,Jung, Young-Hoon 대한약학회 2008 Archives of Pharmacal Research Vol.31 No.11

This paper reports a novel synthetic method for the preparation of various urethanes and the application to the synthesis of carisbamate. The reaction of primary (2a, 2e and 2f) or secondary (2g-2i) trimethylsilyl ethers with chlorosulfonyl isocyanate afforded the corresponding urethanes in good yields without affecting the olefin moiety. However, in the case of secondary benzylic trimethylsilyl ether 2j, the corresponding urethane 3j was obtained in low yield. From the difference in reactivity between the primary and secondary benzylic trimethylsilyl ethers, the one-pot synthesis of carisbamate 1 from bis-trimethylsilyl ether 21 was achieved.

Analysis of three-dimensional thermal gradients for arch bridge girders using long-term monitoring data

Guang-Dong Zhou,Huan Zhang,Ting-Hua Yi,Bin Chen 국제구조공학회 2015 Smart Structures and Systems, An International Jou Vol.15 No.2

Thermal loads, especially thermal gradients, have a considerable effect on the behaviors of large-scale bridges throughout their lifecycles. Bridge design specifications provide minimal guidance regarding thermal gradients for simple bridge girders and do not consider transversal thermal gradients in wide girder cross-sections. This paper investigates the three-dimensional thermal gradients of arch bridge girders by integrating long-term field monitoring data recorded by a structural health monitoring system, with emphasis on the vertical and transversal thermal gradients of wide concrete-steel composite girders. Based on field monitoring data for one year, the time-dependent characteristics of temperature and three-dimensional thermal gradients in girder cross-sections are explored. A statistical analysis of thermal gradients is conducted, and the probability density functions of transversal and vertical thermal gradients are estimated. The extreme thermal gradients are predicted with a specific return period by employing an extreme value analysis, and the profiles of the vertical thermal gradient are established for bridge design. The transversal and vertical thermal gradients are developed to help engineers understand the thermal behaviors of concrete-steel composite girders during their service periods.

Crack identification in a rotor with an open crack

Guang Ming Dong,Jin Chen 대한기계학회 2009 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.23 No.11

A finite element (FE) model, which is based on a transfer matrix analysis and local flexibility theorem, is introduced for crack identification of a static (non-rotating) rotor with an open crack. Through numerical simulation, the effects of crack location and crack depth on the mode shapes and the changes in the eigenfrequencies of the cracked rotor are investigated. A crack identification algorithm that makes use of the translations of the first mode at two symmetric points and the contour diagram of crack location versus crack depth for the first two given normalized eigenfrequencies is proposed to estimate the crack location and depth in the rotor. Two illustrative examples are demonstrated and compared for availability and validity of the proposed algorithm.

Optimal sensor placement under uncertainties using a nondirective movement glowworm swarm optimization algorithm

Guang-Dong Zhou,Ting-Hua Yi,Huan Zhang,Huan Zhang,Hong-Nan Li 국제구조공학회 2015 Smart Structures and Systems, An International Jou Vol.16 No.2

Optimal sensor placement (OSP) is a critical issue in construction and implementation of a sophisticated structural health monitoring (SHM) system. The uncertainties in the identified structural parameters based on the measured data may dramatically reduce the reliability of the condition evaluation results. In this paper, the information entropy, which provides an uncertainty metric for the identified structural parameters, is adopted as the performance measure for a sensor configuration, and the OSP problem is formulated as the multi-objective optimization problem of extracting the Pareto optimal sensor configurations that simultaneously minimize the appropriately defined information entropy indices. The nondirective movement glowworm swarm optimization (NMGSO) algorithm (based on the basic glowworm swarm optimization (GSO) algorithm) is proposed for identifying the effective Pareto optimal sensor configurations. The one-dimensional binary coding system is introduced to code the glowworms instead of the real vector coding method. The Hamming distance is employed to describe the divergence of different glowworms. The luciferin level of the glowworm is defined as a function of the rank value (RV) and the crowding distance (CD), which are deduced by non-dominated sorting. In addition, nondirective movement is developed to relocate the glowworms. A numerical simulation of a long-span suspension bridge is performed to demonstrate the effectiveness of the NMGSO algorithm. The results indicate that the NMGSO algorithm is capable of capturing the Pareto optimal sensor configurations with high accuracy and efficiency.

뼈모세포 초기부착에 영향을 미치는 나노수준 거칠기 칼슐포스페이트 박막 개발#

Guang Zhi Dong,고재승,Hyun-Man Kim 대한구강해부학회 2005 대한구강해부학회지 Vol.29 No.1

Surface roughness is well known to affect cellular activity. This study presents a method to fabricate nano-scale surface roughness on the surfaces of polymer, metal, glass with calcium phosphate thin film. Metastable calcium and phosphate ion solution was slowly heated to obtain calcium phosphate thin fibn. Then fresh calcium and phosphate ion solution was added to fabricate nano-scale roughness over tlùs initially forrned thin film. Various surfaces of nano- scale roughness lower than 800 nm of Ra v외ue was obtained. Initial cell adhesion was characterized over the fabricated surfaces using MC3T3-El osteoblastic cellline. Spreading of osteoblastic cell decreased according to the increase of surface roughness. Less stress fibers developed in the cells attaching to the rougher surface. Less focal contacts visualized by staining vinculin was found in the cells of irútial adhesion. All these features of the initial cell adhesion represents that less adhesion signals are generated from the rougher surface. Further study is required to evaluate the effect of these low adhesion signals on the overall cellular activitv.

Successful percutaneous transluminal coronary angioplasty with stent implantation for unstable angina in severe hemophilia A

Dong Kie Kim,Guang Won Seo,Jae Hyun Jung,Young Bok Kim,Ung Kim,Sang Hoon Seol,Tae Hyun Yang,Dae Kyeong Kim,Doo Il Kim,Dong Soo Kim 대한내과학회 2009 대한내과학회 추계학술대회 Vol.2009 No.-