메가골조시스템은 사용되는 구조재료를 절약하면서도 구조물의 강성을 효과적으로 높일 수 있는 장점 때문에 고층건물의 설계에 많이 사용되고 있다. 이러한 메가골조시스템이 주로 적용되고 있는 초고층건물의 구조설계에서는 횡하중에 대한 거주자의 불안감을 최소화시키는 것이 주요한 관심사중의 하나이다. 따라서 본 연구에서는 메가골조구조물의 사용성을 향상시키기 위한 방법으로 일반적인 수동 TMD의 제어성능을 개선한 준능동 TMD(STMD)를 사용하였다. 이를 위하여 TMD에서 일반적으로 사용되고 있는 수동감쇠기 대신 준능동 MR 감쇠기를 사용하여 STMD를 구성하였다. 메가골조구조물의 일반적인 유한요소해석모델은 매우 많은 수의 자유도로 구성되어 있기 때문에 원형모델을 사용하여 STMD의 제어성능을 검토하는 것은 현실적으로 불가능하다. 따라서 메가골조구조물의 동적 거동을 정확하게 표현할 수 있는 최소한의 자유도를 가진 응축모델을 행렬응축기법을 이용하여 제안하였다. 또한 일반적인 행렬응축기법의 효율성을 향상시키기 위하여 메가골조구조물의 특성을 활용한 다단계 행렬응축기법을 제안하였다. 본 연구에서 제안된 응축모델을 사용한 제어의 효율성과 정확성 및 메가골조구조물에 대한 STMD의 제어성능을 예제해석을 통하여 검증하였다.

본 연구에서는 지진하중을 받는 탄성 및 비탄성 구조물에 대하여 수동 및 준능동 TMD의 지진응답제어성능을 평가하였다. 먼저 기존의 연구에서 제안된 식을 사용하여 최적 설계된 수동형 TMD와 본 연구에서 제시된 준능동 TMB가 설치된 탄성 구조물의 변위스펙트럼을 구하였으며, 준능동 TMD가 TMD보다 작은 스트로크를 가지고도 최대변위응답제어에 있어 우수함을 확인하였다. 또한 구조물의 주기와 TMD의 주기가 일치하지 않은 경우의 성능저하에 대한 TMD의 강인성을 평가하였다. 최종적으로 Bouc-Wen 모델을 사용하여 모사된 비탄성이력 특성을 가지는 구조물에 대한 수치해석을 수행하였으며, 이를 통해 탄성구조물에 대하여 최적화된 수동형 TMD의 성능은 구조물 응답의 비탄성이력 부분이 증가함에 따라 크게 저하되는 반면 준능동 TMD는 수동형 TMD보다 약 15-40% 정도의 더 많은 응답감소효과를 가짐을 확인하였다.

Forced vibration testing is important for correlating the mathematical model of a structure with the realone and for evaluating the performance of the real structure. There exist various techniques available for evaluating the seismic performance using dynamic and static measurements. In this paper, full scale forced vibration tests simulating earthquake response are implemented by using a hybrid mass damper. The finite element(FE) model of the structure was analytically constructed using ANSYS and the model was updated using the results experimentally measured by the forced vibration test. System identification of real-scaled 5 story building structure which is located in UNISON INC. is conducted on the updated FE model.

We have made a comprehensive statistical study on the coronal mass ejections(CMEs) associated with helmet streamers. A total number of 3810 CMEs observed by SOHO/LASCO coronagraph from 1996 to 2000 have been visually inspected. By comparing their LASCO images and running difference images, we picked out streamer-associated CMEs, which are classified into two sub-groups: Class-A events whose morphological shape seen in the LASCO running difference image is quite similar to that of the pre-existing streamer, and Class-B events whose ejections occurred in a part of the streamer. The former type of CME may be caused by the destabilization of the helmet streamer and the latter type of CME may be related to the eruption of a filament underlying the helmet streamer or narrow CMEs such as streamer puffs. We have examined the distributions of CME speed and acceleration for both classes as well as the correlation between their speed and acceleration. The major results from these investigations are as follows. First, about a quarter of all CMEs are streamer-associated CMEs. Second, their mean speed is 413 km s-1 for Class-A events and 371 km s-1 for Class-B events. And the fraction of the streamer-associated CMEs decreases with speed. Third, the speed-acceleration diagrams show that there are no correlations between two quantities for both classes and the accelerations are nearly symmetric with respect to zero acceleration line. Fourth, their mean angular width are about 60°, which is similar to that of normal CMEs. Fifth, the fraction of streamer-associated CMEs during the solar minimum is a little larger than that during the solar maximum. Our results show that the kinematic characteristics of streamer-associated CMEs, especially Class-A events, are quite similar to those of quiescent filament-associated CMEs.

We present JHKS near-infrared CCD photometric study for the Galactic open clusters NGC 1641 and NGC 2394. These clusters have never been studied before, and we provide, for the first time the cluster parameters; reddening, distance, metallicity and age. NGC 1641 is an old open cluster with age 1.6 ± 0.2 Gyr, metallicity [Fe/H]= 0.0 ± 0.2 dex, distance modulus(m-M)0=10.4 ± 0.3 mag(d=1.2 ± 0.2 kpc), and reddening E(B-V)=0.10±0.05 mag. The parameters for the other old open cluster NGC 2394 are estimated to be age=1.1±0.2 Gyr, [Fe/H]=0.0±0.2 dex, (m-M)0=9.1±0.4 mag(d=660±120 pc), and E(B-V)=0.05±0.10 mag. The metallicities and distance values for these two old open clusters are consistent with the relation between the metallicities and the Galactocentric distances of other old open clusters. We find the metallicity gradient of 53 old open clusters including NGC 1641 and NGC 2394 to be Δ[Fe/H]/ΔRgc=-0.067 ± 0.009 dex kpc-1.

The present investigation has attemped to optimize hydrogen reduction process for the mass production of Fe-8wt%Ni nanoalloy powder from ball milled powder. In-situ hygrometry study was performed to monitor the reduction behavior in real time through measurement of water vapor outflowing rate. It was found that the reduction process can be optimized by taking into account the apparent influence of water vapor trap in the reactor on reduction kinetics which strongly depends on gas flow rate, reactor volume and reduction.

This study was performed to estimate the emission rate of volatile organic compounds (VOCs) and to evaluate the risk level affected by indoor air pollutants (IAPs) in 27 new apartments (prior to residence) in Seoul City from December 2004 to March 2005. The indoor air pollutants investigated in this study include formaldehyde, several aromatic VOCs (benzene, toluene, styrene, xylene, and ethylbenzene). All measurements were made based on the standard method of Ministry of Environment in Korea. The indoor concentration levels for benzene, xylene, toluene, ethylbenzene, styrene, and formaldehyde have significant increase trend 5 hours after closing windows and doors. Levels of air pollutants did not exhibit significant difference between living rooms and bedrooms. The air exchange rates by the concentration decay method using SF6 were 0.37 for low floor, 0.32 for middle floor, and 0.75 for high floor. The emission rate showed the highest level in the middle floor and second one in the low floor, when estimated by the IAQ model for benzene, toluene, ethylbenzene, xylene, styrene, and formaldehyde. Considering the above result, it is suggested that the estimation of emission rate be considered when the new apartment is designed and constructed with respect to construction materials to emit low VOCs. Moreover, the related regulation should be established for IAQ management.

In this paper, simulating the wind induced responses of a building structure using a linear mass shaker is presented. The shaker force is calculated by using the inverse transfer function of a target structural response to the actuator. Filter and envelop function are used such that the error between wind and exciter induced responses is minimized by preventing the shaker from exciting unexpected modal response and initial transient response. The analyses results from a 76-story benchmark building problem in which wind load obtained by wind tunnel test is given, indicate that the linear mass shaker installed at a specific floor can approximately embody the structural responses induced by the wind load applied to each floor of the structure. The linear mass shaker signal is generated by the proposed method can be effectively used for evaluating the wind response characteristics of a practical building structure and for obtaining an accurate analytical model of the building under wind load.

In this study, numerical analysis of TMD to estimate optimal-design-parameter is investigated using actual excitation, and evaluated by comparing results of numerical analysis and optimal-design-parameter was devised by Soong. It assumed between 1~2 seconds the 1st mode natural period of an aged apartment which has 10~15 stories and then investigated optimal-design-parameter of actual excitation for evaluate optimal frequency ratio and damping ratio according to local site condition. At this time mass ratio was 1% and range of tuned frequency ratio was 0.8Hz to 1.2Hz at intervals of 0.01Hz, and optimal damping ratio was 1% to 14% at intervals of 0.002%. It estimated Optimal-design-parameter was evaluated by numerical analysis according to peak and RMS displacement, acceleration respectively local site. And the result of evaluated respond performance parameter respectively a period was shown low numerical-value than optimal-design-parameter was devised by Soong what is more peak acceleration indicated performance difference of 20% over

일반적으로 구조물이 지진하중에 저항하기 위해서는 충분한 강성과 연성을 확보하여야 한다. 본 연구에서는 대공간 구조시스템의 지붕 구조와 하부 구조 사이에 면진 장치를 도입하는 방법을 사용하여 동적 거동 특성을 규명한다. 하부 구조의 강성과 질량의 크기에 대한 영향을 고려한 대공간 구조 시스템의 동적 거동 특성 규명 및 해석 과정 단순화를 위해 병렬 다질점계 등가모델을 도입한 본 논문은 향후 대공간 구조물의 성능 설계를 위한 기초적인 연구가 될 것이다.

Benzoxazolo carbocyanine compounds were synthesized by condensation of a suitable ortho-ester with an appropriately substituted 2-methylbenzoxazole in the presence of triethylamine. This compounds used as green sensitizing dyes in photographic emulsions. The compounds are characterized by fast atom bombardment mass spectrometry. The values(m/z) of structurally significant ions observed in FAB spectra. It was showed tentative fragmentation pattern in FAB spectroscopy of HN(C2H5)3 cations in glycerol/trifluoroacetic acid matrix.