• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.12
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• pp.272-278
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• 2018

Traffic volume has been greatly increasing due to urban development and the improvement of living standards, and many complaints are being raised due to the increasing road noise. As a countermeasure against these problems, highly soundproof walls are installed on the sides of roads. However, the ability to bear wind loads is a major design requirement for soundproof walls, which contributes to the exponential increases in construction costs and restricts the height of the walls. The aim of this study is to improve the performance of soundproof walls and to dramatically reduce wind loads while maintaining excellent price competitiveness. Based on Helmholz's resonator theory, a new concept is proposed for a ventilation-type soundproofing plate that can pass through a fluid like air and reduce noise. A full-scale metal soundproofing plate was produced to satisfy the quality standards of highways by conducting a sound-pressure transmission-loss test, wind tunnel test, and material quality test. To verify the reliability, the wall was manufactured and installed, and the sound insulation effect was examined by measuring the noise over time. In the future, ventilated soundproof walls on roads could create a pleasant living environment due to the high noise-insulation effect.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.8
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• pp.787-794
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• 2010

Recently, with sudden increase of supplying rate of cars and quantity of goods transported, traffic noisy becomes one of important factors obstruct environment of exhibition and view facilities have purpose in calmness and unsatisfaction about this is high now. Therefore, in case of exhibition and view facilities, it has to be grasped that satisfaction degree about the noisy in and out of the exhibition room by performing effect valuation on traffic noisy from design step. However the level of internal noise cannot be measured at the design phrase of the structure due to the noise of traffic. Up until now a walls transmission loss, based on the law of mass, is predicted using this method. However measuring the internal sound level after actual construction reveals that there is a large difference from measurements made at the design stage, and it is very difficult to find a solution after the opening of the structure. From research looking from this perspective the internal sound level was predicted- calculating the internal sound absorption ability, using acoustic simulation and loss prevention of an insulated wall- based on data collected to evaluate the internal sound of an exhibition room at a Folk Museum adjacent to a freeway. The results of this research are considered to provide important data for the prediction of internal sound level at the time of construction of exhibition facilities similar to this.

• Journal of the Korean housing association
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• v.21 no.4
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• pp.129-137
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• 2010

This study surveys the degree of residents' satisfaction on the current street space to suggest alternatives for the improvement of the street space design in detached house areas. In the results of the survey, we find the following. First, in the result of analysis on age, residential term, having children or not, income level, and type of house ownership, residents are homogeneous in social and economic characteristics. There are similarity in geographical, locational conditions, neighboring facilities, deterioration of residential house, and the time of residential formation among residential areas. Second, satisfactory determinants of residents on street space according to street types, are maintenance, protection of privacy, and parking space. Third, satisfactory determinants of residents on street hierarchy is the inner circulation road while unsatisfactory one is the inner roads. Fourth, age, residential term and type of house ownership are significant factors influencing residents' satisfaction. Factors influencing satisfaction on street space are also affecting total satisfaction and factors associated with street environment are perceived more important ones than factors associated with street activities. Thus we find the degrees of satisfaction for residents on street type and street hierarchy are different despite that general characteristics of residents are similar. We also find residents consider street noise and maintenance as critical factor among physical factors of street space.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.10 no.1
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• pp.74-92
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• 2000

This study was performed to evaluate the working conditions In construction workers through measurements of working environments and to improve the working conditions and to design the appropriate environmental and health management system. The results of measurement for working environments in construction work are as following: 1. The excess rate of noise and dust concentration in express highway construction, road construction, building construction and interior painting was 28.6% and 24.5% respectively. 2. The excess rate of mixed organic solvents concentration in interior painting was 39.3%. 3. The chain type bulldozer has the highest level of vibration; the excess rate was 85.7%, and among the vibration instruments, the level of left hand's vibration of all vibrators exceeded the criterion and in the case of drilling all the level of vibration exceeded the criterion in both hands. On the basis of the results in this research the environmental and health management system for construction workers must be considered. Therefore, it is necessary to be introduced the special medical examination and measurement of working environments in construction industry. In defining "the working place" of Article 39 of Enforcement regulations of industrial safety and health act, the word "indoors" should be deleted. Then the eligible industry for measurement of working environment must be extended. And it is also necessary for construction industry to be performed group health management service by agencies such as other manufacturing industry.

• International Journal of Highway Engineering
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• v.12 no.3
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• pp.87-92
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• 2010

As the Concept "how environmental friendly" becomes more and more important in road construction. However, so far there is no estimation method. Environmental friendly concept can be incorporated at the plan level in order to influence decision making, and support policies that affect environment. The overall goal of this study was to develop environmental friendly concept measures for the national highway and to develop a methodology to implement a more environmental friendly concept. The research identified 8 performance measures through a project analysis that could address environmental impact assessment system's ten strategic goals - Topography, Wildlife, hydrology, landuse, air quality, water quality, soil, waste, noise, landscape. The qualitatively and quantitatively evaluation approach was selected as the decision support framework and performance measure were investigated using the AHP(Analytic Hierarchy Process) and pilot corridor for a 10 section and calculate the index values. The methodology was applied to a pilot corridor comprised of a 120km section of national highway in korea. The methodology made it possible to identify the specific performance measures that need improvement to enhance the overall environmental friendly concept. It is fairly intuitive, based on readily available data, and is easy to apply. It provides a powerful tool for government to assess the relative environmental friendly conceptof their transportation corridors now and in the future. It allows for comparisons within a corridor and with other corridors and identifies the improvements needed to enhance the environmental friendly concept.

• Korean Journal of Environment and Ecology
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• v.23 no.2
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• pp.169-176
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• 2009

The purpose of this study was to provide basic data for developing the practical park management. For this, satisfaction degree, satisfaction factors and estimated model by satisfaction variables of visitors analyzed through a questionnaire survey in Byeonsanbando National Park, Korea. In the evaluation of the satisfaction, variables of 'careless cooking'. 'collection of natural plants & animals', 'Noise and urination on the road' and 'Littering problem' at Naesosa and 'crowding', 'touting', 'Indiscreet use' and 'Illegal merchant' at Gyeokpo was most unsatisfied than any other variables. Satisfaction factors by Factor Analysis were loaded with 'user management' at Naesosa(65.1%) and 'business behavior management at Gyeokpo(68.4%) by the highest contribution degree. In estimated model of satisfaction by Multiple Regression Analysis showed in order of 'Injury of landscape resource', 'Lack of information facility', 'crowding' and 'Lack of employee's guidance or kindness' at Naesosa and 'Injury of landscape resource', 'Lack of information facility', 'Illegal merchant', Lack of facility to stay' and 'Lack of employee's guidance or kindness' at Gyeokpo. So, Mountain and marine National Parks needed different management policy and are required to institutional apparatus for user education.

• Journal of Korean Society of Transportation
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• v.33 no.4
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• pp.323-336
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• 2015

Estimating the risks on the roadway using surrogate safety measures (SSM) has an advantage in that it focuses on the vehicle trajectory directly involved in conflicts. On the other hand, there is a restriction on estimating the risks of continuous segments due to the limited data collected from a location. To overcome the restriction, this study presents the scheme of acquiring the vehicular trajectory using real time kinematics-differential global positioning system (RTK-DGPS) and develops a methodology which contains the considerations of the problems to calculate the SSM such as time-to-collision (TTC), deceleration rate to avoid collision (DRAC) and acceleration noise (AN). By using the methodology, this study shows a result from an experiment executed in a section where the variation of vehicular movement can be observed from several continuous flow roadway sections near Seoul and Gyeonggi Province in Korea. The result illustrated the risks on the roadway by the SSM metrics in certain situations like merging and diverging, stop-and-go, and weaving. This study would be applied to relate the dangers with characteristics of drivers and roadway sections, and prevenst accidents or conflicts by detecting dangerous roadway sections and drivers' behaviors. This study contributes to improving roadway safety and reducing car-accidents.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.4
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• pp.31-40
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• 2016

In vehicular ad-hoc networks (VANETs), vehicles sense information on emergency incidents (e.g., accidents, unexpected road conditions, etc.) and propagate this information to following vehicles and a server to share the information. However, this process of emergency message propagation is based on multiple broadcast messages and can lead to broadcast storms. To address this issue, in this work, we use a novel approach to detect the vehicles that are farthest away but within communication range of the transmitting vehicle. Specifically, we discuss a signal-to-noise ratio (SNR)-based linear back-off (SLB) scheme where vehicles implicitly detect their relative locations to the transmitter with respect to the SNR of the received packets. Once the relative locations are detected, nodes that are farther away will set a relatively shorter back-off to prioritize its forwarding process so that other vehicles can suppress their transmissions based on packet overhearing. We evaluate SLB using a realistic simulation environment which consists of a NS-3 VANET simulation environment, a software-based WiFi-IP gateway, and an ITS server operating on a separate machine. Comparisons with other broadcasting-based schemes indicate that SLB successfully propagates emergency messages with latencies and hop counts that is close to the experimental optimal while reducing the number of transmissions by as much as 1/20.

• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.8
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• pp.34-41
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• 2017

Vehicle to Infrastructure(V2I) communication means the technology between the vehicle and the roadside unit to provide the Intelligent Transportation Systems(ITS) and Telematic services. The vehicle collects information about the probe data through the evolved Node B(eNodeB) and after that eNodeB provides road conditions or traffic information to the vehicle. To provide these V2I communication services, we need a link adaptation technology that enables reliable and higher transmission rate. The receiver transmits the estimated Channel State Information(CSI) to transmitter, which uses this information to enable the link adaptation. However, due to the rapid channel variation caused by vehicle speed and the processing delay between the layers, the estimated CSI quickly becomes outdated. For this reason, channel interpolation and prediction scheme are needed to achieve link adaptation in V2I communication system. We propose the Advanced Discrete Prolate Spheroidal Sequence(ADPSS) channel interpolation and prediction scheme. The proposed scheme creates an orthonomal basis, and uses a correlation matrix to interpolate and predict channel. Also, smoothing is applied to frequency domain for noise removal. Simulation results show that the proposed scheme outperforms conventional schemes with the high speed and low speed vehicle in the freeway and urban environment.

• Journal of Broadcast Engineering
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• v.19 no.3
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• pp.372-384
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• 2014

DTV field tests have been performed to measure field strength and to check reception ratio on indoor and outdoor sites. They use an antenna of 9m to measure DTV signal in case of outdoor measurement on the road. Modern skyscrapers require the analysis of vertical-directional wave propagation by measuring vertical-directional DTV signal. Even if the field strength is above the reception threshold of $43dB{\mu}V/m$, the reception is impossible in case of strong multi-path or high impulse noise. So, vertical-directional field measurement is essential in environment of tall buildings. In this paper, we developed an octo type multi-copter to measure vertical-directional DTV signal level. A compact and portable DTV signal level meter, an antenna, a microwave transmitter for data transmission, and a recording equipment are equipped in the multi-copter. Three different sites are selected to test the measurement system. Developed measurement system using the multi-copter is very useful in measuring vertical-directional DTV signal, especially in apartments, non-accessible area by vehicles, and forbidden areas.