• Journal of the Korean Society for Nondestructive Testing
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• v.32 no.6
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• pp.703-710
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• 2012

A structural health monitoring technique for locating impact position in a composite plate is presented in this paper. The method employs a single sensor and spatial focusing properties of time reversal(TR) and inverse filtering(IF). We first examine the spatial focusing efficiency of both approaches at the impact position and its surroundings through impact experiments. The imaging results of impact localization show that the impact location can be accurately estimated in any position of the plate. Compared to existing techniques for locating impact or acoustic emission source, the proposed method has the benefits of using a single sensor and not requiring knowledge of anisotropic material properties and geometry of structures. Furthermore, it does not depend on a particular mode of dispersive Lamb waves that is frequently used in other ultrasonic testing of plate-like structures.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.5
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• pp.170-177
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• 1997

In this study, an analysis technique using simple beam model for predicting structure crashworthiness of the passenger car side impacted with an angle by another passenger car was investigated. The simple model was composed of major beam-like side structure which carry almost all side impact load. A procedure of component collapse test, calculation of load carrying capability and dynamic simulation was carryed out sequentially. Transient dynamic algorithms and a computer program to simulate deformations and motions of the impacted car was developed. The developed procedure was applied to a 3 door passenger car side impacted with an angle of 75 degree and the analysis results show good agreements with the actual test results.

• Journal of Environmental Science International
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• v.24 no.9
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• pp.1211-1220
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• 2015

Soil is the most important factor in natural environment for bio-diversity. Urbanization and development of city devastate urban soil by the fraternization of green network and run off pollution. In these facts, preservation of soil is the main issue in maintain of quality urban environment. In order to handle this issue, the gold network that link fragment soil patches is considered in maintain quality soil. This study researched the infiltration Treebox design technique based on the Low Impact Development. This technique suggest reduction of impervious area of the soil due to urbanization. The main concept of this study is encourage more permeable surfaces in urban area by using a infiltration planter. The function of the planter is hold run off as much as possible from intensive rainfall, and utilizes it in drought season. Also, this planter provides fertile soil for organism habitat by keeping appropriate moisture supplying.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.5
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• pp.813-821
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• 2002

Glass fiber reinforced PET matrix composite was manufactured by rapid press consolidation technique as functions of temperature, pressure and time in pre-heating, consolidation and solidification stages. The optimal manufacturing conditions for this composite were discussed based on the void content, tensile, interlaminar shear and impact properties. In addition, the levels of crystallinity with various manufacturing conditions were measured using differential scanning calorimetry to investigate the mechanical properties of this composite material as a function of crystallinity. Among many processing parameters, the mold temperature and the cooling rate after forming were found to be the most critical factors in determining the level of crystallinity and mechanical properties. The level of crystallinity affects the tensile properties to some degree. However, impact properties are affected much more. It also affects the degree of ductility, which determines the impact energy of this material.

• The Journal of Asian Finance, Economics and Business
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• v.9 no.2
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• pp.243-254
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• 2022

Customers' perceptions of information about a company's products or services have altered as a result of the development of ICT and social networks. This gives rise to a fact that buzz marketing, which is a marketing technique employed commonly in today's business and communication, has a significant impact on customers' electronic word of mouth intention (e-WOM). However, very few studies about this issue have been conducted so far, which reveal a gap in understanding buzz marketing from an academic perspective. Based on the results of a cross-sectional survey in Binh Duong city, this study investigates the efficiency and effect of buzz marketing on customers' e-WOM intention through mediating variables of message credibility. Data from 367 time-lagged individual samples were collected and analyzed by the structural equation modeling method (SEM). Results showed that creativity, clarity, and humor variables have a positive relationship with message credibility and then impact the intention to conduct e-WOM of social networks' users. Marketing campaigns employing the buzz technique should be launched with easy-to-understand and entertainable messages. Findings from this study also provide managers with a scientific understanding of buzz marketing and the effectiveness of this technique as well as reveal the potential for future studies to explore further in this area.

• Journal of Communications and Networks
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• v.6 no.4
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• pp.317-330
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• 2004

In this paper, we explore the utility of recently discovered multiple-antenna techniques (namely MIMO techniques) for medium access control (MAC) design and routing in mobile ad hoc networks. Specifically, we focus on ad hoc networks where the spatial diversity technique is used to combat fading and achieve robustness in the presence of user mobility. We first examine the impact of spatial diversity on the MAC design, and devise a MIMO MAC protocol accordingly. We then develop analytical methods to characterize the corresponding saturation throughput for MIMO multi-hop networks. Building on the throughout analysis, we study the impact of MIMO MAC on routing. We characterize the optimal hop distance that minimizes the end-to-end delay in a large network. For completeness, we also study MAC design using directional antennas for the case where the channel has a strong line of sight (LOS) component. Our results show that the spatial diversity technique and the directional antenna technique can enhance the performance of mobile ad hoc networks significantly.

• Journal of Biomedical Engineering Research
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• v.10 no.3
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• pp.279-284
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• 1989

Measurement of cardiac output during exercise by noninvasive technique is very needed in the area of sports medicine. However there are only two noninvasive techniques, one of which is $CO_2$ subscript rebreathing technique and the other one is impedance cardiography. While $CO_2$ rebreathing technique needs special breathing and metablic steady state, impedance cardiography has motion Uiiau problem. In this study maior sources of the mothion artifact during treadmill exercise was found experimentally to. be the impact caused by each step on the treadmill. Thus special shoes to reduce the impact were developed. These are the shoes with silicon rubber and hard sponge attached to the soles. It was possible to measure cardiac output with the newly developed shoes for Burke protocol whose speed of the treadmill was constant 3.5 miles/hour while it was impossibel with the conventional exercise shoes.

• Tunnel and Underground Space
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• v.7 no.3
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• pp.230-237
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• 1997

As concrete structure is getting old and decrepit, its inspection and diagnosis is getting important. Therefore, it is necessary to estimate the soundness of structure using non-destructive tests for effective repairs and maintenances. But, applications of non-destructive tests in tunnel have been used restrictively, due to accessibility only from one side in tunnel lining and presence of tunnel installations. Recently, the various non-destructive techniques have been studied. Especially, ground penetrating radar(GPR) and impact echo (IE) methods have been researched for tunnel inspection. In this study, the applicability of impact echo test in tunnel lining inspection has been investigated. This paper described the tunnel inspection for lining thickness and internal flaw using impact echo tests. Model tests were carried out using impact echo test systems on two concrete models, Model I is measuring for lining thickness, Model II is detecting for internal flaw. Also, the test were applied for lining inspections in a tunnel constructed by NATM. From the results of impact echo tests, we have concluded that impact echo test is a very useful and effective technique for inspecting the concrete tunnel linings.

• Journal of Environmental Impact Assessment
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• v.3 no.1
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• pp.43-52
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• 1994

This study conducted a visual impact assessment of an apartment complex project proposed in Jungkye-dong, Seoul. Three design alternatives of the project-alternatives 1, 2, and 3-which differed in form, color, scale, and arrangement of buildings were simulated with computer image processing technique. The simulations were presented to the public who were mainly residents in the project area, and visual impact resulted from the alternatives was assessed by them. Their responses were then statistically analyzed. It was found that, in terms of compatibility with the surrounding landscape, alternative 1 was the most favourable because it was more traditional, natural, and diverse than alternatives 2 and 3. At the same time, the alternative was most preferred by the public because it was more plain, natural, and diverse than other alternatives. It was suggested that the visual impact assessment with public participation conducted in this study would help both planners and the public to make more intelligent decisions.

• Journal of Ocean Engineering and Technology
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• v.7 no.2
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• pp.37-43
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• 1993

The simplest vibrtion absorber is the impact damper which consists of a small mass allowed to impact between two gaps sp that energy is dissipated by conversion into noise and heat. Impact damping is a passive vibration control technique to attenuate the vibrations of lightly damped. It has been investigated to reduce the excessive vibrations of turbin blades, radar antennas, machine tools and tall light poles. In this paper, the efficiency of impact vibration absorber was investigated. A steady state vibration of two equispaced impacts per cycle was assumed. The analysis based on the assumption has been considered and the theory is examined experimentally.