• Wind and Structures
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• v.16 no.2
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• pp.157-178
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• 2013

Output-only modal parameter identification is based on the assumption that external forces on a linear structure are white noise. However, harmonic excitations are also often present in real structural vibrations. In particular, it has been realized that the use of forced acceleration responses without knowledge of external forces can pose a problem in the modal parameter identification, because an external force is imparted to its impulse acceleration response function. This paper provides a three-stage identification procedure as a solution to the problem of harmonic and white noise excitations in the acceleration responses of a linear dynamic system. This procedure combines the uses of the mode indicator function, the complex mode indication function, the enhanced frequency response function, an iterative rational fraction polynomial method and mode shape inspection for the correlation-related functions of the force-embedded acceleration responses. The procedure is verified via numerical simulation of a five-floor shear building and a two-dimensional frame and also applied to ambient vibration data of a large-span roof structure. Results show that the modal parameters of these dynamic systems can be satisfactorily identified under the requirement of wide separation between vibration modes and harmonic excitations.

• Journal of Chest Surgery
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• v.16 no.3
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• pp.356-361
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• 1983

Pulmonary tuberculosis is still one of unsolved problems in Korea due to increased number of far-advanced and drug-resistant patients, who have poor pulmonary function. We have analyzed 1332 operated Gases during the period of 1958-1981. Annual incidence of the disease decreased from 110 [1960] to 21 [1980]. The ratio between male and female was 7:3 and the age of peak incidence was in the 3rd and 4th decades. Recently, patients below the age of 20 years were slightly decreased, but above 50 years were slightly increased. The patients consisted of far-advanced case in 60% and moderately-advanced in 39% in 1980, as compared with 40% and 59% correspondingly in 1965. Preoperative sputum positively decreased from 91% [1958-1963] to 43.8% [ 1974-1981 ]. Medically treated patients for more than 3 years increased from 16% [1958-1963] to 51% [1974-1981]. From the view of surgical indication, totally destroyed hung increased from 27% [1958-1963] to 4396 [1974-1981 ]. Therefore, pneumonectomy occupied 53.8% of total surgical management recently. Mode of surgical treatment showed that thoracoplasty [33%], resection [57%] in 1958-1963 and thoracoplasty [2%], resection [98%] in 1974-1981. As Semb`s thoracoplasty was the first choice of treatment until 1960, thereafter resection became the choice. Postoperative mortality increased from 1.6-2.096 to 396 recently as well as morbidity. It was mainly due to increased number of poor pulmonary function and postoperative spread of disease. On the basis of our experience, far-advanced and drug-resistant patients increased in number recently, whose pulmonary function was poor. So postoperative mortality and morbidity increased. Proper surgical intervention should be considered before the appearance of resistance for all chemotherapeutic drugs.

• Journal of Chest Surgery
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• v.25 no.1
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• pp.79-85
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• 1992

We have analyzed 1559 operated cases during the 32 year period, from October, 1958 to December, 1990. Annual incidence of the surgical treatment decreased from 101[1960] to 25[1990]. The ratio between male and female was 2.1: 1 and the age of peak incidence was in the 3rd and 4th decades. Recently, patients below the age of 20 years were decreased, but above 50 years were much increased. The patients were consisted of far-advanced case in 71.8% and moderately-advanced case in 22.0% in 1990, as compared with 44% and 54% correspondingly in 1960. Preoperative sputum positivity decreased from 91%[1958~1963] to 38%[1982~1990]. Preoperative antituberculous chemotherapy for more than 3 years increased from 16% [1958~1963] to 56.5% [1982~1990]. From the view of surgical indication, totally destroyed lung and destroyed lobe or segment has been main indication. Recently empyema with parenchymal lesion was increased, and so more extensive surgical resection such as pleuropneumonectomy was performed more frequently. The trends in the mode of surgical treatment revealed that thoracoplasty has virtually disappeared and operations required for residuals of pleural disease have increased. Postoperative mortality increased from 1.6-2.0% to 3.6% recently as well as morbidity. On the basis of our study, far-advanced and drug-resistant patients increased in number recently, whose pulmonary function was poor. So postoperative mortality and morbidity was increased despite improved anesthetic and surgical techniques. Proper surgical intervention should be considered before the appearance of resistance for all chemotherapeutic drugs.

• Bulletin of the Korean Chemical Society
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• v.20 no.3
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• pp.285-290
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• 1999

In the present paper, we report a molecular dynamics (MD) simulation study for the structure and dynamics of H+ ions in non-rigid dehydrated H12-A zeolite framework at 298.15 K, using the same method we used in our previous studies of rigid and non-rigid zeolite-A frameworks. It is found that two different structures appear, depending on the choice of the Lennard-Jones parameter (σ) for the H+ ion, as is also observed in the study of rigid dehydrated H12-A zeolite framework, but the ranges of σ are different for the two structures. It is also found that some of the H+ ions exchanged their sites without changing the number of H+ ions at each site. The agreement between experimental and calculated structural parameters for non-rigid dehydrated H12-A zeolite is generally quite good. The calculated IR spectrum by Fourier transform of the total dipole moment auto-correlation function shows two major peaks, one around 2700 cm-1 and the other around 7000 cm-1. The former appears in the calculated IR spectra of non-rigid zeolite-A framework only system and the latter remains unexplained except, perhaps, as an indication of a new formation of a vibrational mode of the framework due to the adsorption of the H+ ions.

• Journal of Korean Ophthalmic Optics Society
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• v.14 no.2
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• pp.9-14
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• 2009

Purpose: The purpose of this study was to examine the relationship between the accommodative facility, blink rate and accommodative lag according to the change of angles of main viewpoint of near distance worker and study an appropriate viewing angle that mitigates asthenopia, such as headaches or eye fatigue accompanied when reading and staring at the computer or TV for a long time. Methods: Total of 27 people including 12 male university students and 15 female university students in the age of 20 to 36 with frequent near distance works, such as computers, were selected to study the accommodative facility, the blink rate and the accommodative lag in accordance with the change of viewing angles of the near distance workers. The refraction error was corrected completely and the phoropter was shifted to near distance mode to locate the near distance indication at 40 cm. The accommodative facility and the blink rate were measured for one minute at each viewing direction of $40^{\circ}$ downward, $20^{\circ}$ downward, horizontal, and $20^{\circ}$ upward directions based on the horizontal line and the accommodative lag was measured in dynamic retinoscopy using retinoscope. Results: As a result, when the main viewpoint was moved on upper direction from the $40^{\circ}$ below, the accommodative facility was reduced and the blink rate and the accommodative lag were increased so their eyes became dry and the accommodation response was reduced. Conclusions: In near distance works, the eye fatigue level can be minimized by locating a book or a computer screen $40^{\circ}$ below than the horizontal direction.