• Smart Structures and Systems
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• 제9권3호
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• pp.253-271
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• 2012

Finite element (FE) model updating is a useful tool for global damage detection technique, which identifies the damage of the structure using measured vibration data. This paper presents the application of a finite element model updating method to detect the damage of a small-scale reinforced concrete building structure using measured acceleration data from shaking table tests. An iterative FE model updating strategy using the least-squares solution based on sensitivity of frequency response functions and natural frequencies was provided. In addition, a side constraint to mitigate numerical difficulties associated with ill-conditioning was described. The test structure was subjected to six El Centro 1942 ground motion histories with different Peak Ground Accelerations (PGA) ranging from 0.06 g to 0.5 g, and analytical models corresponding to each stage of the shaking were obtained using the model updating method. Flexural stiffness values of the structural members were chosen as the updating parameters. In model updating at each stage of shaking, the initial values of the parameter were set to those obtained from the previous stage. Severity of damage at each stage of shaking was determined from the change of the updated stiffness values. Results indicated that larger reductions in stiffness values occurred at the slab members than at the wall members, and this was consistent with the observed damage pattern of the test structure.

• 농촌지도와개발
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• 제10권1호
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• pp.57-76
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• 2003

This study examined th socioeconomic returns to agricultural research in Korea, using multivariate time series technique and Akino-Hyami formula. Results showed that the socioeconomic returns were quite competitive with internal rates of 49.18% and 56.04% for agricultural research and horticultural research respectively. The lagged response to the investment in research varied according to the type of production: agricultural production responded to agricultural research shock about three tears after the shock, while horticultural and livestock productions responded only after abort seven, and ten years, respectively. The magnitudes of the impacts of investment, however, showed a similar pattern for the three types of production: after responding to the shock, the impact increased until a peak was reached and then declined and got down to zero after some years. The peak was reached within five, seventeen, and twenty tears after the intial expenditures for agricultural, horticultural, and livestock productions, respectively. Moreover, the impacts disappeared about thirty tears after the initial expenditures for all three types of production. These findings were consistent with the results from previous literature on agricultural research, which indicated that the lag lengths of the response to investments on research were between seven and thirty years.

• Journal of Astronomy and Space Sciences
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• 제32권4호
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• pp.297-304
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• 2015

In this study, we documented the midlatitude F2-layer response to five strong geomagnetic storms with minimum Dst < -150 nT that occurred in solar minimum years using hourly values of the F2-layer critical frequency (foF2) from four ionosondes located in different hemispheres. The results were very limited, but they illustrated some peculiarities in the behavior of the F2-layer storm. During equinox, the characteristic ionospheric disturbance patterns over the Japanese station Wakkanai in the Northern Hemisphere and the Australian station Mundaring in the Southern Hemisphere were consistent with the well-known scenario by $Pr{\ddot{o}}lss$ (1993); however, during a December solstice magnetic storm, both stations did not observe any noticeable positive ionospheric disturbances. Over the "near-pole" European ionosonde, clear positive ionospheric storms were not observed during the events, but the "far-from-pole" Southern Hemisphere station Port Stanley showed prominent enhancements in F2-layer peak electron density in all magnetic storms except one. No event produced noticeable nighttime enhancements in foF2 over all four ionosondes.

• International Journal of Contents
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• 제4권3호
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• pp.1-9
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• 2008

The Korean life insurance industry has undergone profound changes, such as the beginning of the variable insurance in July 2001 and the bancassurance enforcement in August 2003. However, little empirical research has analyzed data that includes the bancassurance of life insurance companies operating in Korea. In response to this lack of research, this paper applies DEA (data envelopment analysis) models to measure and decompose their efficiency. We discovered that life insurance companies operating in Korea are a little different in their composition ratio of inputs and outputs, due to the increased variety of distribution channels and new products. We provided efficiency scores, return to scale, and reference frequencies. We also decomposed CCR, BCC, and SBM efficiency into scale efficiency and MIX efficiency. So, we try to investigate whether the sources of inefficiency were caused by the inefficient operation of DMU, disadvantageous conditions, the difference of the composition ratio in inputs and outputs with reference sets, or any combination of the above. Most companies in the sample display had either constant or decreasing returns to scale. The efficiency rankings were less consistent among models and efficient DMUs. In response to this problem, we used the super-efficiency model to rank them and then compared the rankings of the DMUs among the various models. It was also concluded that the availability of panel data, rather than cross-sectional data, would greatly improve the validity of the efficiency estimates.

• 전자공학회논문지SC
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• 제43권3호
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• pp.25-30
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• 2006

디지털 영상처리를 이용해 CCD 센서의 스펙트럼 응답특성을 직접 측정할 수 있는 적외선 영상기법을 제안하고 있다. 이 방법은 쉽고 경제적인 방법으로 상용 CCD 센서의 스펙트럼 감도를 검출할 수 있도록 한다. 본 장치의 핵심 부품은 단색광원기, CCD 지지대, 디지털 영상처리 시스템이 내장된 컴퓨터이다. 방법의 타당성을 증명하기 위해 상용 CCD 카메라에 대해 시험적으로 행한 실험은 이론적인 모델과 잘 일치함을 보여 주었다.

• 대한한방내과학회지
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• 제31권4호
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• pp.837-845
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• 2010

It has been shown that bilateral decrease of point H4,5,6 in Ryodoraku test is related with gastric dysmotility. This suggested that the system of Kyung-Rak related with anatomical gastric disease may not be the Stomach Meridian, in the view that the system of Kyung-Rak is similar to that of Ryodoraku, and which was not consistent with classical contents of Kyung-Rak principle. Therefore, this paper was done to investigate whether bilateral decrease of point H4,5,6 is a general sign of common gastric disease in Ryodoraku test and to study its relation between Kyung-Rak principle and autonomic nervous system as a mediator explaining Ryodoraku response. As shown in the results of this study, different electrical response of Ryodoraku between patients with dyspepsia of gastric dysmotility and gastric ulcer revealed discrepancy of location indicating anatomical stomach between Kyung-Rak principle and Ryodoraku and instability of explanation of autonomic nerve theory to Ryodoraku. Thus, it presented the possibility that artificial application of Kyung-Rak principle against Ryodoraku may destroy its originality in the clinical field. To correctly use Ryodoraku in the diagnosis or evaluation of disease, Ryodoraku test should be used according to Nakatani's suggestion and clinical indication of which is limited to the diseases complicated with dysfunction of the autonomic nervous system.

• Journal of Microbiology and Biotechnology
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• 제24권9호
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• pp.1207-1215
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• 2014

Candida albicans, the major human fungal pathogen, undergoes morphological transition from the budding yeast form to filamentous growth in response to nitrogen starvation. In this study, we identified a new function of GST2, whose expression was required for filamentous growth of C. albicans under nitrogen-limiting conditions. The Gst2p showed Gst activity and required response to oxidative stress. The ${\Delta}gst2$ mutant displayed predominantly yeast phase growth in low ammonium media. Such morphological defect of ${\Delta}gst2$ mutants was not rescued by overexpression of Mep2p, Cph1p, or Efg1p, but was rescued by either overexpression of a hyperactive $RAS1^{G13V}$ allele or through exogenous addition of cyclic AMP. In addition, the ${\Delta}gst2$ mutants had lower levels of RAS1 transcripts than wild-type cells under conditions of nitrogen starvation. These results were consistent with the Ras1-cAMP pathway as a possible downstream target of Gst2p. These findings suggest that Gst2p is a significant component of nitrogen starvation-induced filamentation in C. albicans.

• Wind and Structures
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• 제14권2호
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• pp.113-131
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• 2011

Excessive wind-induced motion in tall buildings can cause discomfort, affect health, and disrupt the daily activities of the occupants of a building. Dynamic vibration absorbers such as the tuned mass dampers (TMDs) can be used to reduce the wind-induced motion below a specified tolerable serviceability limit state (SLS) criterion. This study investigates whether the same probability of not exceeding specified wind-induced motion levels can be achieved by torsionally sensitive structures without/with linear/nonlinear TMDs subjected to partially correlated wind forces, if they are designed to just meet the same SLS criterion. For the analyses, different structures and the uncertainty in the response, wind load and perception of motion is considered. Numerical results indicate that for structures that are designed or retrofitted without or with optimum linear TMDs and satisfying the same SLS criterion, their probability of exceeding the considered criterion is very consistent, if the inherent correlation between the wind forces is considered in design. However, this consistency deteriorates if nonlinear TMDs are employed. Furthermore, if the correlation is ignored in the design, in many cases a slightly unconservative design, as compared to the designed by considering correlation, is achieved.

• Wind and Structures
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• 제24권5호
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• pp.481-500
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• 2017

A novel three-degree-of-freedom (DOF) forced vibration system has been developed for identification of aeroelastic (self-excited) load parameters used in time-domain response analysis of wind-excited flexible structures. This system is capable of forcing sinusoidal motions on a section model of a structure that is used in wind tunnel aeroelastic studies along all three degrees of freedom - along-wind, cross-wind, and torsional - simultaneously or in any combination thereof. It utilizes three linear actuators to force vibrations at a consistent frequency but varying amplitudes between the three. This system was designed to identify all the parameters, namely, aeroelastic- damping and stiffness that appear in self-excited (motion-dependent) load formulation either in time-domain (rational functions) or frequency-domain (flutter derivatives). Relatively large displacements (at low frequencies) can be generated by the system, if required. Results from three experiments, airfoil, streamlined bridge deck and a bluff-shaped bridge deck, are presented to demonstrate the functionality and robustness of the system and its applicability to multiple cross-section types. The system will allow routine identification of aeroelastic parameters through wind tunnel tests that can be used to predict response of flexible structures in extreme and transient wind conditions.

• 대한의용생체공학회:의공학회지
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• 제27권6호
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• pp.384-391
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• 2006

Variation of brain dynamics under Zen meditation has been one of our major research interests for years. One issue encountered is the inaccessibility to the actual meditation level or stage as a reference. In this paper, we propose an alternative strategy for investigating the human brain in response to external flash stimuli during Zen meditation course. To secure a consistent condition of the brain dynamics when applying stimulation, we designed a recording of flash visual evoked potentials (F-VEPs) based on a constant background EEG (electroencephalograph) frontal $\alpha-rhythm$ dominating activities that increase significantly during Zen meditation. Thus the flash-light stimulus was to be applied upon emergence of the frontal $\alpha-rhythm$. The alpha-dependent F-VEPs were then employed to inspect the effect of Zen meditation on brain dynamics. Based on the experimental protocol proposed, considerable differences between experimental and control groups were obtained. Our results showed that amplitudes of P1-N2 and N2-P2 on Cz and Fz increased significantly during meditation, contrary to the F-VEPs of control group at rest. We thus suggest that Zen meditation results in acute response on primary visual cortex and the associated parts.