• Journal of Korean Society of Environmental Engineers
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• v.36 no.9
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• pp.597-603
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• 2014

The aim of the present study is to compare sound performance depending on thickness, materials, and structure of polymer soundproof panels consisting of PC, PMMA, HDPE, and PP, respectively. As a result of comparing sound transmission loss (STL) of single layer panel made of four types of polymer, the better sound transmission loss was obtained in order of PC, PMMA, HDPE, and PP, which was obviously followed mass law. 8 mm of single panel showed 5~6 dB(A) greater STL than that of 4 mm panels and lower frequency for coincidence effect so that STL of 8 mm panels decreased around 4,000~5,000 Hz, indicating less STL of 4 mm panels than those of 8 mm. When it comes to structure, 4 mm panels with air layer appeared similar value of STL with 8 mm single panels under 300 Hz. In range of high frequency above 2,000 Hz, 4 mm panels with air layer performed better than 8 mm of single layer panel while resonance effects were observed at 500~630 Hz. It was found that these results could be practically utilized as fundamental data for noise barriers design considering the change to each condition.

• 한국지구물리탐사학회:학술대회논문집
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• 2006.06a
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• pp.141-151
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• 2006

A blank test was done to calculatee the car itself's magnetic effect as noise and to eliminate it from the data set of total magnetic intensity(=magnetic flux density) exploration in a car-borne magnetic exploration system. To calculate the induced magnetic intensity(= magnetization) and the remanent magnetic intensity(= magnetization) of the car itself, we have installed the magnetometer on a fixed point and measured the magnetic intensity letting the car move around the magnetometer, and we have changed the data set into an analogous data set as if acquired in the condition that we have parked the car on the same fixed point and measured the magnetic intensity moving the magnetometer around the magnetometer. Through an inversion with the later data set as input, we have calculated the magnetic center and the magnetic moments of the induced magnetic intensity(= magnetization) and the remanent magnetic intensity(= magnetization) of the car itself with the two centers coincided because of some barriers of the inversion algorithm that we have used in this study. On the other hand, we have extracted the magnetic anomaly by reducing i. e. vectorially eliminating the induced magnetic intensity(= magnetization) and the remanent magnetic intensity(= magnetization) of the car itself calculated forwardly, from the magnetic exploration data set acquired by the car-borne magnetic exploration system.

• Structural Engineering and Mechanics
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• v.68 no.1
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• pp.67-80
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• 2018

Recently, U-section decks have been more and more used in metro and light rail bridges as an innovative concept in bridge deck design and a successful alternative to conventional box girders because of their potential advantages. U-section may be viewed as a single vent box girder eliminating the top slab connecting the webs, with the moving vehicles travelling on the lower deck. U-section bridges thus solve many problems like limited vertical clearance underneath the bridge lowest point, besides providing built-in noise barriers. Beam theory in mechanics assumes that plane section remains plane after bending, but it was found that shearing forces produce shear deformations and the plane section does not remain plane. This phenomenon leads to distortion of the cross section. For a box or a U section, this distortion makes the central part of the slab lagging behind those parts closer to the webs and this is known as shear lag effect. A sample real-world double-track U-section metro bridge is modelled in this paper using a commercial finite element analysis program and is analysed under various loading conditions and for different geometric variations. The three-dimensional finite element analysis is used to demonstrate variations in the transverse bending moments in the deck as well as variations in the longitudinal normal stresses induced in the cross section along the U-girder's span thus capturing warping and shear lag effects which are then compared to the stresses calculated using conventional beam theory. This comparison is performed not only to locate the distortion, warping and shear lag effects typically induced in U-section bridges but also to assess the main parameters influencing them the most.

• Journal of the Korea Society of Computer and Information
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• v.16 no.12
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• pp.11-21
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• 2011

An embedded sensor is significantly influenced by its spatial environment, such as barriers or distance, through low power and signal strength. Due to these causes, noise data frequently occur in an embedded sensor. Because the information acquired from the embedded sensor exists in a time series, it is hard to detect an error which continuously takes place in the time series information on a realtime basis. In this paper, we proposes an error detection method based on time-series prediction that detects error signals of embedded sensors in real time in consideration of the physical characteristics of embedded devices. The error detection method based on time-series prediction proposed in this paper determines errors in generated embedded device signals using a stable distance function. When detecting errors by monitoring signals from an embedded device, the stable distance function can detect error signals effectively by applying error weight to the latest signals. When detecting errors by monitoring signals from an embedded device, the stable distance function can detect error signals effectively by applying error weight to the latest signals.

• Journal of Distribution Science
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• v.17 no.9
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• pp.127-131
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• 2019

Purpose - This study focuses on clues that can clearly amplify the effects of background music. Review which store environments have a direct and positive impact on consumer responses, such as purchases. Research design, data, and methodology - This study focuses on clues that can clearly amplify the effects of background music. The purpose of this study is to examine what kind of store environment, combined with background music, has a direct and positive effect on consumer reactions such as purchase, and suggest future research directions. Results - The manager decides to use background music in the store because it is relatively inexpensive and easy to identify the emotional response of the consumer. In addition, appropriate background music lowers the psychological purchasing barriers of consumers. Previous studies have often not conducted a basic review of whether consumers perceive background music when it is used in retail stores. For example, it is necessary to make sure that the volume of the background music is loud enough and that the noise is properly excluded despite the congestion of the store so that the pure influence of the background music on the consumer can be measured. A way for store managers to clarify and differentiate their identity is to create a unique and satisfying store atmosphere for their customers. In order to help customers focus on their purchases, store managers must use marketing elements to integrate the five senses. And they should plan background music aiming at synergy effect of these five senses. In other words, in order to make the store atmosphere positive, it is not enough to have a suitable visual design interior or background music in the store, and consumers should have the opportunity to smell, taste and touch it directly. Conclusions - In conclusion, we hope that the following issues will be studied by several scholars in the future. It should be clarified that the impact of background music on customers varies depending on the customer's movement in the store, the selection of the background music genre order, and the timing (interval) of background music exposure to the customer.

• The Journal of Internal Korean Medicine
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• v.41 no.6
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• pp.1141-1161
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• 2020

Objectives: Parkinson's disease (PD) is a neurodegenerative disease of the elderly characterized by impaired behavior from lack of dopamine secretion. However, no accurate quantitative diagnosis method has been established. The purpose of this study was to analyze the patent trends (PTs) of health examination and daily monitoring/healthcare technology for PD. Methods: For analyzing PTs, a search summary for classifying each analysis target technology was set, and a final search formula was constructed by collecting keywords. After constructing a database of related patents through the final search formula, noise was removed to extract valid patents. PTs by major countries were analyzed using the valid patents, and PTs and growth stages were analyzed by the detailed technologies. Results: The survey analysis showed that, despite the existence of unpublished patents between 2018 and 2020, patent activity has increased rapidly in the recent period, and this increasing trend was led by the USA. This technology is considered to be in its early- or mid-stage growth period, which means that the marketability is high and the barriers are low. Korea's market share is only about 25%, but it has a larger number of applications than those of Europe and Japan. Integrated monitoring and diagnosis technologies for PD have a share of 34%. Conclusion: The advances in diagnosis and healthcare technology for PD means that traditional Korean medicine must continue to pay attention to related technologies and to review plans that are applicable to clinical practice.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.25 no.6
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• pp.549-558
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• 2012

A topology optimization method for phononic crystals is developed for the design of sound barriers, using the level set approach. Given a frequency and an incident wave to the phononic crystals, an optimal shape of periodic inclusions is found by minimizing the norm of transmittance. In a sound field including scattering bodies, an acoustic wave can be refracted on the obstacle boundaries, which enables to control acoustic performance by taking the shape of inclusions as the design variables. In this research, we consider a layered structure which is composed of inclusions arranged periodically in horizontal direction while finite inclusions are distributed in vertical direction. Due to the periodicity of inclusions, a unit cell can be considered to analyze the wave propagation together with proper boundary conditions which are imposed on the left and right edges of the unit cell using the Bloch theorem. The boundary conditions for the lower and the upper boundaries of unit cell are described by impedance matrices, which represent the transmission of waves between the layered structure and the semi-infinite external media. A level set method is employed to describe the topology and the shape of inclusions. In the level set method, the initial domain is kept fixed and its boundary is represented by an implicit moving boundary embedded in the level set function, which facilitates to handle complicated topological shape changes. Through several numerical examples, the applicability of the proposed method is demonstrated.