• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2005년도 학술발표회 논문집
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• pp.529-535
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• 2005

This paper presents a system identification (SI) scheme in time domain using measured acceleration data. The error function is defined as the time integral of the least squared errors between the measured acceleration and the calculated acceleration by a mathematical model. Damping parameters as well as stiffness properties of a structure are considered as system parameters. The structural damping is modeled by the Rayleigh damping. A new regularization function defined by the L1-norm of the first derivative of system parameters with respect to time is proposed to alleviate the ill-posed characteristics of inverse problems and to accommodate discontinuities of system parameters in time. The time window concept is proposed to trace variation of system parameters in time. Numerical simulation study is performed through a two-span continuous truss subject to ground motion.

• Journal of Chest Surgery
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• 제27권4호
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• pp.324-327
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• 1994

Resection and reconstruction of distal trachea or carina have posed tremendous technical challenges for surgeons. Successful outcome depends on thorough preoperative evaluation, careful anesthetic management,strict attention of surgical technique and postoperative care. We report a successful case of revision of tracheal stenosis using femoro-femoral bypass on a 13~year-old boy. The patient complained severe dyspnea about I month following right sleeve pneumonectomy. Preoperative CT scan and intraoperative bronchoscopy showed pin-point tracheal stenosis at a tracheo-bronchial anastomosis site about 1.2cm in length.At operation the lesion was severely adhesed and the lumen was nearly obstructed. The stenotic segment was resected and direct end-to-end anastomosis was done under femoro-femoral bypass for adequate oxygenation. The patient was discharged at postop. 16 days without specific complications and has continued to do well.

• Journal of Mechanical Science and Technology
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• 제18권12호
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• pp.2114-2124
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• 2004

In this paper, a structural damage identification method (SDIM) is developed for cylindrical shells and the numerically simulated damage identification tests are conducted to study the feasibility of the proposed SDIM. The SDIM is derived from the frequency response function solved from the structural dynamic equations of damaged cylindrical shells. A damage distribution function is used to represent the distribution and magnitudes of the local damages within a cylindrical shell. In contrast with most existing modal parameters-based SDIMs which require the modal parameters measured in both intact and damaged states, the present SDIM requires only the FRF-data measured in the damaged state. By virtue of utilizing FRF-data, one is able to make the inverse problem of damage identification well-posed by choosing as many sets of excitation frequency and FRF measurement point as needed to obtain a sufficient number of equations.

• 대한수학회논문집
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• 제22권2호
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• pp.157-161
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• 2007

Let G be a p-mixed abelian group with semi-complete torsion subgroup $G_t$ such that G is splitting or is of torsion-free rank one, and let R be a commutative unitary ring of prime characteristic p. It is proved that the group algebras RG and RH are R-isomorphic for any group H if and only if G and H are isomorphic. This isomorphism relationship extends our earlier results in (Southeast Asian Bull. Math., 2002), (Proc. Amer. Math. Soc., 2002) and (Bull. Korean Math. Soc., 2005) as well as completely settles a problem posed by W. May in (Proc. Amer. Math. Soc., 1979).

• 대한의생명과학회지
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• 제8권4호
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• pp.269-273
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• 2002

Dengue fever (DF) is an acute febrile illness caused by dengue viruses in the family Flaviviridae, genus Flavivirus. DF has so far posed any problem in Korea, however it has been recently believed to be associated with oversea's traveler infected with dengue virus. Antibody titers of sera from DF patients against dengue virus were measured by indirect immunofluorescence assay (IFA) and plaque reduction neutralization test (PRNT), including the haematologic test. Three of patients with DF showed highly fluorescent and neutralizing antibody titers by IFA and PRNT assay. Two of them showed higher, remarkably. Meanwhile, one of them was tested and resulted in severe tirombocytopenia, elevated serum levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT) activities as well as mild leucopenia, increased monocytes and basophils and depressed lymphocytes in haematological differential count.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 추계학술대회논문집
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• pp.614-618
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• 2003

This paper presents a system identification (SI) scheme in time domain using measured acceleration data. The error function is defined as the time integral of the least square errors between the measured acceleration and the calculated acceleration by a mathmatical model. Damping parameters as well as stiffness properties of a structure are considered as system parameters. The structural damping is modeled by the Rayleigh damping. A new regularization function defined by the L$_1$-norm of the first derivative of system parameters with respect to time is proposed to alleviate the ill-posed characteristics of inverse problems and to accommodate discontinuities of system parameters in time. The time window concept is proposed to trace variation of system parameters in time.

• 한국항공운항학회지
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• 제16권2호
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• pp.21-27
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• 2008

An inverse method is introduced to construct the problem for the error analysis of the numerical solution of initial value problem. These problems constructed through this method have a known exact solution, even though analytical solutions are generally not obtainable. The process leading to the exact solution makes use of an initially available approximate numerical solution. A smooth interpolation of the approximate solution is forced to exactly satisfy the differential equation by analytically deriving a small forcing function to absorb all of the errors in the interpolated approximate solution. Using this special case exact solution, it is possible to investigate the relationship between global errors of a candidate numerical solution process and the associated tuning parameters for a given problem. Under the assumption that the original differential equation is well-posed with respect to the small perturbations, we thereby obtain valuable information about the optimal choice of the tuning parameters and the achievable accuracy of the numerical solution.

• 한국수산과학회지
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• 제23권5호
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• pp.407-415
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• 1990

We studied the spatio-temporal characteristics of the Ullung Warm Lens (UWL) using the historical oceanographic data of the National Fisheries Research and Development Agency of Korea in the East Sea from 1967 to 1983. The UWL is basically a subsurface phenomenin found in 100 to 300m depths, and its existence is not well posed in the distribution of the sea surface temperature. The UWL has a typical size of 100 km diameter, and its center migrates within the region of 150 by 150 km south of the Ullung Island. The UWL is almost a permanent feature, and the probability of its occurence within our study area ($129\~132^{\circ}E,\;36\~38^{\circ}N)\;was\;86\%$.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 춘계학술대회논문집
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• pp.430-433
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• 2003

This paper presents a system identification (SI) scheme in time domain using measured acceleration data. The error function is defined as the time integral of the least square errors between the measured acceleration and the calculated acceleration by a mathematical model. Damping parameters as well as stiffness properties of a structure are considered as system parameters. The structural damping is modeled by the Rayleigh damping in SI. The regularization technique is applied to alleviate the ill-posed characteristics of inverse problems. The validity of the proposed method is demonstrated by an experimental study on a shear building model.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 1993년도 Fifth International Fuzzy Systems Association World Congress 93
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• pp.877-880
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• 1993

Fuzzy control algorithms are developed based on fuzzy models of systems. The control issues are posed as multiobjective optimization problems involving goals and constraints imposed on system's variables. Two basic design modes embrace on-and off-line control development. The first type of design deals with the time and state-dependent objectives and pertains to control determination based upon the current state of the system. The second design mode gives rise to explicit forms of fuzzy controller that is learned based on a given list of state-control associations. Both the fuzzy models as well as fuzzy controllers are realized as logic processors.