• Smart Structures and Systems
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• v.6 no.4
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• pp.363-372
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• 2010

Accurate peak response estimation of a seismically excited structure with frictional damping system (FDS) is very difficult since the structure with FDS shows nonlinear behavior dependent on the structural period, loading characteristics, and relative magnitude between the frictional force and the excitation load. Previous studies have estimated the peak response of the structure with FDS by replacing a nonlinear system with an equivalent linear one or by employing the response spectrum obtained based on nonlinear time history and statistical analysis. In case that earthquake excitation is defined probabilistically, corresponding response of the structure with FDS becomes to have probabilistic distribution. In this study, nonlinear time history analyses were performed for the structure with FDS subjected to artificial earthquake excitation generated using Kanai-Tajimi filter. An equation for the probability density function (PDF) of the displacement response is proposed by adapting the PDF of the normal distribution. Coefficients of the proposed PDF are obtained by regression of the statistical distribution of the time history responses. Finally, the correlation between the resulting PDFs and statistical response distribution is investigated.

• Nuclear Engineering and Technology
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• v.43 no.4
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• pp.361-374
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• 2011

Two types of numerical modeling techniques were considered for the dynamic response of a structure subjected to a ground acceleration. One technique is based on the equation of motion relative to ground motion, and the other is based on the equation of absolute motion of the structure and the ground. The analytic background of the former is well established while the latter has not yet been extensively verified. The latter is called a large mass method, which allocates an appropriate large mass to the ground so that it causes the ground to move according to a given acceleration time history. In this paper, through the use of a single degree-of-freedom spring-mass system, the equations of motion of the two techniques were analyzed and useful theorems are provided on the large mass method. Using simple examples, the numerical results of the two modeling techniques were compared with analytic solutions. It is shown that the theorems provide a clear insight on the large mass method.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2007.04a
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• pp.639-644
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• 2007

The accurate peak response estimation of a seismically excited structure with frictional damping system(FDS) is very difficult since the structure with FDS shows nonlinear behavior dependent on the structural period, loading characteristics, and relative magnitude between the frictional force and the excitation load. Previous studies have estimated that by replacing a nonlinear system with an equivalent linear one or by employing the response spectrum obtained based on nonlinear time history and statistical analysis. In the case that on earthquake load is defined with probabilistic characteristics, the corresponding response of the structure with FDS has probabilistic distribution. In this study, nonlinear time history analyses were performed for the structure with FDS subjected to artificial earthquake loads generated using Kanai-Tajimi filter. An equation for the probability density function (PDF) of the displacement response is proposed by adapting the PDF of the normal distribution. Finally, coefficients of the proposed PDF is obtained by regression analysis of the statistical distribution of the time history responses. Finally, the correlation between PDFs and statistical response distribution is presented.

• International Area Studies Review
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• v.13 no.1
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• pp.513-530
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• 2009

The history of Chechnya is characterized by the resistance against the invasions of different foreign countries. Among them, the conflict against the Soviet Union, or Russia has been lasted approximately 200 years and it still remains unsettled. The relation between both country was deteriorated when the Chechnya declared their independence from Russia, and this resulted in the long-lasted war between Russia and Chechnya. One of the driving force of the war for Chechnya was its religion, Islam. The Islam and the brotherhood of Sufi Islam are integrated with Chechen nationalism and they were the key factors during the war against Russia. In this present paper, we will deal with the Chechen national culture and its identification, the conflict history of Chechnya-Russia, Islamization of Chechen, and the power of Sufi Islam in Chechnya in order to give a careful consideration to the conflict between both countries.

• The Journal of Korean Medical History
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• v.36 no.2
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• pp.27-48
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• 2023

This study identifies 164 Korean medicine practitioners among the independence activists and describes the types and characteristics of their independence movements. Their occupations included apothecary pharmacist, herbalist, and medicine dealer. They originated from Gyeongbuk, Hamnam, Pyeongnam, and Gyeongnam, with a higher proportion of Hamnams compared to independence fighters. Their ages are concentrated in the 30s and 40s. Their movements are similar to those of independence heroes, in the order of domestic resistance, the March 1 Movement, and Manchurian resistance. The crimes are Security Law, Exorcism No. 7 of the 8th Reign of Daejeong, Public Order Maintenance Law, and attempted murder. In terms of sentences, the proportion of those sentenced to five years or more in prison is higher, and the proportion of those sentenced to less is lower. The above independence movements in Korean medicine practitioners are characterized by (1) the use of direct force, (2) long-term and planned struggle, (3) the provision of contact points and funding sources, (4) a nationalist line, and (5) low socialist-communist share.

• The Journal of Korean Medical History
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• v.25 no.1
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• pp.43-51
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• 2012

Smallpox and measles might be the typical epidemics through Choson Danasty. Especially Sookjong was the first king who suffered from smallpox during the period of his reign. This study was examined critically focused on the Clinical Records about Smallpox which occurred in the 9th year of Sookjong's reign. The clinical records in Seungjeongwon Ilgi("承政院日記") was the main source and the Annals of the Joseon Dynasty was reffered. It tells us that Sookjong caught infectious disease, smallpox spread in town and the whole process of smallpox. Seungmagalgeuntang(升麻葛根湯) and hwadoktang(火毒湯) were given at the early term for treating Sookjong's smallpox, but later on, Bowontang(補元湯) was given for the treatment of smallpox. It showed us the medical view which placed emphasis on the vital force of human body. A dermatologist, Yoo Sang had joined since the beginning of the treatment and Siyakchung(侍藥廳) was established for Sookjong. Sasunghoichuntang(四聖回天湯) which was Chunyoohyung(全有亨)'s prescription showed us enough clinical experience and the ways of treatments. At the same time, the medical culture at that time was well known through the fact that smallpox was taboo among the royal family.

• Journal of the Earthquake Engineering Society of Korea
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• v.24 no.6
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• pp.243-251
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• 2020

In seismic design standards such as KDS 41 17 00 and ASCE 7, three procedures are provided to estimate seismic demands: equivalent lateral force (ELF), response spectrum analysis (RSA), and response history analysis (RHA). In this study, two steel special moment frames (SMFs) were designed with ELF and RSA, which have been commonly used in engineering practice. The collapse probabilities of the SMFs were evaluated according to FEMA P695 methodology. It was observed that collapse probabilities varied significantly in accordance with analysis procedures. SMFs designed with RSA (RSA-SMFs) had a higher probability of collapse than SMFs designed with ELF (ELF-SMFs). Furthermore, RSA-SMFs did not satisfy the target collapse probability specified in ASCE 7-16 whereas ELF-SMFs met the target probability.

• Journal of The Korean Astronomical Society
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• v.38 no.2
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• pp.165-168
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• 2005

We overview the GRAPE (GRAvity piPE) project. The goal of the GRAPE project is to accelerate the astrophysical N-body simulations. Since almost all computing time is spent for the evaluation of the gravitational force between particles, we can greatly accelerate many N-body simulations by developing a specialized hardware for the force calculation. In 1989, the first such hardware, GRAPE-1, was completed, with the peak speed of 120 Mflops. In 2003, GRAPE-6 was completed, with the peak speed of 64 Tflops, which is nearly 106 times faster than GRAPE-l and was the fastest computer at that time. In this paper, we review the basic concept of the GRAPE hardwares, the history of the GRAPE project, and two ongoing projects, GRAPE-DR and Project Milkyway.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.127-132
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• 2007

In this paper, to overcome local damages of structures, an uncertainty of structural model, installing sensors of structures, and economics of building system, decentralized semi-active magnetorheological(MR) damper using the displacement or velocity transferred to the response of floor installed damper is proposed. Relative magnitude between the control force of dampers and the story shear force is difined as design variables and the performance indices response spectra analysis through nonlinear time history analysis excited by seismic loads is performed according to this design variables. And the performance of this decentralized MR damper is compared with previous centralized LQR control algorithm using 3-stories benchmark building structure excited by El Centro (1940, N.S) in order to evaluate the application of building structures.

• Korea-Australia Rheology Journal
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• v.11 no.3
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• pp.225-232
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• 1999

This study presents 1-dimensional simple model for sheet casting or rectangular fiber spinning process. In order to achieve this goal, we introduce the concept of force flux balance at the die exit, which assigns for the extensional flow outside the die the initial condition containing the information of shear flow history inside the die. With the Leonov constitutive equation that predicts non-vanishing second normal stress difference in shear flow, we are able to describe the anisotropic swelling behavior of the extrudate at least qualitatively. In other words, the negative value of the second normal stress difference causes thickness swelling much higher than width of extrudate. This result implies the importance of choosing the rheological model in the analysis of polymer processing operations, since the constitutive equation with the vanishing second normal stress difference is shown to exhibit the characteristic of isotropic swelling, that is, the thickness swell ratio always equal to the ratio in width direction.