• Journal of the Korean Mathematical Society
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• v.57 no.5
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• pp.1267-1286
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• 2020

We pay attention to a coupled problem by a penalty term which is induced from non-overlapping domain decomposition methods based on augmented Lagrangian methodology. The coupled problem is composed by two parts mainly; one is a problem associated with local problems in non-overlapping subdomains and the other is a coupled part over all subdomains due to the penalty term. For the speedup of iterative solvers for the coupled problem, we propose two different types of preconditioners: a block-diagonal preconditioner and an additive Schwarz preconditioner as overlapping domain decomposition methods. We analyze the coupled problem and the preconditioned problems in terms of their condition numbers. Finally we present numerical results which show the performance of the proposed methods.

• Communications of the Korean Mathematical Society
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• v.36 no.1
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• pp.51-62
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• 2021

Variational method has played an important role in solving problems of uniqueness and existence of the nonlinear works as well as analysis. It will also be extremely useful for researchers in all branches of natural sciences and engineers working with non-linear equations economy, optimization, game theory and medicine. Recently, the existence of infinitely many weak solutions for some non-local problems of Kirchhoff type with Dirichlet boundary condition are studied [14]. Here, a suitable method is presented to treat the elliptic partial derivative equations, especially (p(x), q(x))-Laplacian-like systems. This kind of equations are used in the study of fluid flow, diffusive transport akin to diffusion, rheology, probability, electrical networks, etc. Here, the existence of infinitely many weak solutions for some boundary value problems involving the (p(x), q(x))-Laplacian-like operators is proved. The method is based on variational methods and critical point theory.

• Wind and Structures
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• v.3 no.3
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• pp.177-191
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• 2000

This paper presents an approach for evaluating directionality effects for both wind speeds and wind loads in hurricane-prone regions. The focus of this study is on directional wind loads on low-rise structures. Using event-based simulation, hurricane directionality effects are determined for an open-terrain condition at various locations in the southeastern United States. The wind speed (or wind load) directionality factor, defined as the ratio of the N-year mean recurrence interval (MRI) wind speed (or wind load) in each direction to the non-directional N-year MRI wind speed (or wind load), is less than one but increases toward unity with increasing MRI. Thus, the degree of conservatism that results from neglecting directionality effects decreases with increasing MRI. It may be desirable to account for local exposure effects (siting effects such as shielding, orientation, etc.) in design. To account for these effects in a directionality adjustment, the factor described above for open terrain would need to be transformed to other terrains/exposures. A "local" directionality factor, therefore, must effectively combine these two adjustments (event directionality and siting or local exposure directionality). By also considering the direction-specific aerodynamic coefficient, a direction-dependent wind load can be evaluated. While the data necessary to make predictions of directional wind loads may not routinely be available in the case of low-rise structures, the concept is discussed and illustrated in this paper.

• Journal of Korean society of Dental Hygiene
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• v.12 no.1
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• pp.123-133
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• 2012

Objectives : This study was performed to understand smoking condition and to investigate the relations among knowledge regarding smoking and oral hygiene, awareness of anti-smoking policy, and self-esteem, to provide fundamental basis, developing programs for smoking prevention and anti-smoking. Methods : From September 7, 2010 to September 16, 2010, questionaire survey was conducted for 566 female university students studying dental hygienics at a local district in Jeollanam-do. Collected data was analyzed by Chi-square test, t-test, one way ANOVA, Scheffe multiple range test, Perason's correlation test, and stepwise multiple regression test. Results : 1. Smoking condition of study subjects on general characteristics showed 17.1%, where 14.0% of previous smoking history, and 68.9% of currently nonsmoker. 2. Analysis on the knowledge related to smoking and oral hygiene, awareness of anti-smoking policy, and self esteem on the general characteristics of study subjects have shown better awareness of anti-smoking policy in non-alcoholics. Significant difference was found in knowledge about smoking and awareness of anti-smoking policy according to current resident status, but no difference found in self-esteem. Higher academic grade was related to higher awareness of anti-smoking policy and better ics. aalcell. Better health, but no diffeoral hygiene were related to better awareness of anti-smoking policy, and bewhich were statistically significant. Favorable interpersonal self-estehip was related to better awareness of anti-smoking policy. 3. Analysis on knowledge regarding smoking related health and oral hygiene, awareness of anti-smoking policy, and self-esteem showed higher level of anti-smoking knowledge in non-smoking group(60.44) compared to currently smoking group or group with previous history of smoking, and better awareness of anti-smoking policy in non-smoking group(53.54) than other groups, which was statistically significant. 4. Correlation analysis among smoking related knowledge, awareness of anti-smoking policy, and self-esteem has found relatively high correlation between smoking related knowledge and awareness of anti-smoking policy, which was statistically significant(r=0.481, p<0.001). 5. Among factors influencing awareness of anti-smoking policy, higher level of smoking related knowledge and satisfaction to specialty was related to higher awareness of anti-smoking policy which was lower in current smoker than past smoker, and higher academic grade was related to higher awareness of anti-smoking policy. Conclusions : Following results emphasize the need to establish a novel curriculum by which effective programs for smoking prevention and education of anti-smoking specialist could be provided as well as promoting coaching anti-smoking activity.

• The Korean Journal of Emergency Medical Services
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• v.10 no.1
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• pp.13-21
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• 2006

Purpose: This study aims to examine characteristics and actual conditions of patients using emergency room at farming and fishing villages, solve overcrowding of emergency room at the tertiary hospital and activate local emergency clinics. Methods: It examines department of diagnosis and treatment, vehicles used, sex, age, residential area, visit hour, length of stay, presence or absence of trauma, measures after first aid and degree of severity based on medical records of 6,740 patients using emergency room at farming and fishing villages from Jan. 1 to Dec. 31, 2005. Conclusion : 1. Sex distribution of patients of emergency room was male 54.9% and female 45.1% and age distribution between over 40 and below 50 was most as 15.9%. 2. Transport means to emergency room were 91.4 of private car and others (public transport and going on foot), 7.5 of 119, 129 and police car and 1.0% of ambulance. 3. According to distribution of residential areas of emergency patients, 38.9% were Eup area, 42.1% Myeon area, 11.4% distant area and 7.5% adjacent area. 4. According to distribution of emergency patients by department of diagnosis and treatment, internal medicine was most as 35.8% and 55% of patients visited emergency room from 3:31 p.m. to 11:30 p.m.. 5. According to total hours of diagnosis and treatment of subjects, 51.2% were within 30min. and cases of non-trauma disease were 68.2%. 6. According to degree of emergency of emergency patients, non-emergency cases were 65.3%, urgent cases 27.7% and emergency cases 7.0% and 74.2% of patients returned home after first aid and 20.6% of them hospitalized. In conclusion, characteristics and diversification of patients should be examined and efforts by government and local medical institutions which must organize emergency system and facility and personnel levels suitable to regional conditions are needed in order to prevent overcrowding of emergency center of the tertiary hospital and activate local emergency center.

• Journal of Korean Society of Water and Wastewater
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• v.37 no.4
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• pp.215-229
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• 2023

In this study, non-destructive technologies that can be applied to evaluate the integrity of valve materials, safety against internal pressure caused by corrosion, and the blocking function of large-diameter water valves during operation without requiring specimen collection or manpower entering the inside of the valve were tested to assess the reliability of the technologies and their suitability for field application. The results showed that the condition of the graphite structure inside the valve body can be evaluated directly through the optical microscope in the field without specimen collection for large-diameter water butterfly valves, and the depth of corrosion inside the valve body can be determined by array ultrasound and the tensile strength can be measured by instrumented indentation test. The reliability of each of these non-destructive techniques is high, and they can be widely used to evaluate the condition of steel or cast iron pipes that are significantly smaller in thickness than valves. Evaluation of blocking function of the valves with mixed gas showed that it can be detected even when a very low flow rate of mixed gas passes through the disk along with the water flow. Finally, as a result of evaluating the field applicability of non-destructive technologies for three old butterfly valves installed in the US industrial water pipeline, it was found that it is possible to check the material and determine the suitability of large-diameter water valves without taking samples, and to determine the corrosion state and mechanical strength. In addition, it was possible to evaluate safety through the measurement results, and it is judged that the evaluation of the blocking function using mixed gas will help strengthen preventive response in the event of an accident.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.6A
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• pp.648-656
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• 2007

This paper is about band pass filter, using Ceramics in the condition of center frequency 370Hz at milli-wave. The band pass filter is applied to Broadband Convergence Network, representing WLL(Wireless Local Loop) and LMDS(Local Multi-point Distribution Service). Sticking ceramic between strip line on a dielectric material substrate with which conductor's covers upper and basal surface, One will house the exterior by using structural resonance. In this Non Radiative Microstrip Line Filter structure, based upon simulations, generalized the two formulas finding resonant frequency of 1step ceramic resonator and bandwidth of 4step ceramic resonator. Also, As a result of experiment, using Network Analyzer, about created a experiment of structure based on the simulation result of 4-step ceramic resonator, It showed good characteristic of targeted bandwidth, comparing simulated result of 36.58GHz$\sim$37.650GHz with experimented result of 36.6GHz$\sim$37.65GHz.

• Journal of the Korean Society of Combustion
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• v.12 no.2
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• pp.26-33
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• 2007

To reveal the newly found liftoff height behavior of hydrogen jet, we have experimentally studied the stabilization mechanism of turbulent, lifted jet flames in a non-premixed condition. The objectives of the present research are to report the phenomenon of a liftoff height decreasing as increasing fuel velocity, to analyse the flame structure and behavior of the lifted jet, and to explain the mechanisms of flame stability in hydrogen turbulent non-premixed jet flames. The velocity of hydrogen was varied from 100 to 300m/s and a coaxial air velocity was fixed at 16m/s with a coflow air less than 0.1m/s. For the simultaneous measurement of velocity field and reaction zone, PIV and OH PLIF technique was used with two Nd:Yag lasers and CCD cameras. As results, it has been found that the stabilization of lifted hydrogen diffusion flames is related with a turbulent intensity, which means that combustion occurs at the point where the local flow velocity is balanced with the turbulent flame propagation velocity.

• Smart Structures and Systems
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• v.6 no.7
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• pp.851-866
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• 2010

This paper presents a new concept of using PZT (lead zircornate titanate) transducers as a non-destructive testing (NDT) tool for evaluating quality of concrete. Detection of defects in concrete is very important in order to check the integrity of concrete structures. The electro-mechanical impedance (EMI) response of PZT transducers bonded onto a concrete specimen can be used for evaluating local condition of the specimen. Measurements are carried out by electrically exciting the bonded PZT transducers at high frequency range and taking response measurements of the transducers. In this study, the compression test results showed that concrete specimens without sufficient compaction are likely to fall below the desired strength. In addition, the strength of concrete was greatly reduced as the voids in concrete were increased. It was found that the root mean square deviation (RMSD) values yielded between the EMI signatures for concrete specimens in dry and saturated states showed good agreement with the specimens' compressive strength and permeable voids. A quality metric was introduced for predicting the quality of concrete based on the dry-saturated state of concrete specimens. The simplicity of the method and the current development towards low cost and portable impedance measuring system, offer an advantage over other NDE methods for evaluating concrete quality.

• Structural Engineering and Mechanics
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• v.68 no.5
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• pp.591-601
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• 2018

Non-moment beam-to-column connections, which are usually referred to as simple or shear connections, are typically designed to carry only gravity loads in the form of vertical shears. Although in the analysis of structures these connections are usually assumed to be pinned, they may provide a small amount of rotational stiffness due to the typical connection details. This paper investigates the effects of this small rotational restraint of simple beam-to-column connections on the behavior and seismic response of steel braced non-moment resisting frames. Two types of commonly used simple connections with bolted angles, i.e., the Double Web angle Connection (DWC) and Unstiffened Seat angle Connection (USC) are considered for this purpose. In addition to the pinned condition - as a simplified representation of these connections - more accurate semi-rigid models are established and then applied to some frame models subjected to nonlinear pushover and nonlinear time history analyses. Although the use of bracing elements generally reduces the sensitivity of the global structural response to the behavior of connections, the obtained results indicate considerable effects on the local responses. Namely, our results show that consideration of the real behavior of connections is essential in designing the column elements where the pin-connection assumption significantly underestimates design of outer columns of upper stories.