• Journal of the Korea Institute of Information and Communication Engineering
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• v.1 no.1
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• pp.47-54
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• 1997

New algorithms for frequency channel assignment in small cellular mobile radio system are proposed. The algorithms are for a channel assignment method which control the transmitter power level based on the distance between the cell site and the mobile unit. These algorithms are such that any channel can be used by any cell site and mobile unit, as long as a required threshold level of carrier to interference ratio is maintained. As the cochannel reuse distance decreases, the proposed algorithms have given an increase in capacity in comparison to a fixed channel assignment.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.11a
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• pp.415-418
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• 2000

There has been a steady increase in geoenvironmental engineering projects where geotechnical engineering has been combined with environmental concerns. Many of these projects involve some investigation on contaminant around unplaned waste landfill. In this study, investigation and test on contamination characteristics of wastes dumped at municipal site were carried out. Testing wastes were sampled at this site. Sampled wastes were divided into waste itself and soil to analysis the characteristics of waste and soil. As a result of this study, the concentration of soil and waste were investigated. And measured concentration were compared with related concentration criteria.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.1420-1425
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• 2005

In a case of an example in Korea, some areas of Yangsan near Busan which exist on soft ground with aquifer, showed us some difficulties of the preparing for housing site and earth structures. From these experiences, recently, the development and research of technology is getting increased, which minimize the influence to the environment from construction work, which is in an agreement with eco-friendly construction in terms of the reasonable processing of ground water. On this case study, one area of Japan that has many site on soft ground with aquifer, is introduced as the reasonable processing of ground water. The applications of the technology for ground water in Korea are discussed.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2001.09a
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• pp.83-90
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• 2001

The site effects of local geological conditions on seismic ground motion are performed using 2D numerical method. For the analysis, a numerical method far ground response analysis using FE-BE coupling method is developed. The total system is divided into two parts so called far field and near field. The far field is modeled by boundary element formulation using the multi-layered dynamic fundamental solution that satisfied radiational condition of wave. And this is coupled with near field modeled by finite elements. In order to verify the seismic response analysis, the results are compared with those of commercial code. As a result, it is shown that the developed method can be an efficient numerical method to solve the seismic response analysis of the site effect in 2D problem.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.2
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• pp.191-198
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• 2010

The noise by the construction activities is one of the main issues in Korea. To prevent the noise from construction site, construction company installs temporary noise barriers along the construction site boundary. Normally sound insulation performance ($R_w$) of the temporary noise barriers made by metal or plastic is between 18 and 31 dB and metallic noise barriers are around 5 dB higher than plastic noise barriers. Sound absorption performance (NRC) of the temporary noise barriers are between 0.20 and 0.59 so it's difficult to characterize their acoustic performance. In this study, it has founded that sound insulation performance of the temporary noise barrier has been improved about 3dB by stick the high density acoustic sheet and insertion loss of noise barrier is getting increased as the source and receiver approached the temporary noise barriers.

• Journal of the Korean Society of Safety
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• v.28 no.4
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• pp.72-80
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• 2013

Accident prevention plan it a construction site should be analyzed and made with risk evaluation and management, from recent year, in Korea. Accidents occurred in construction site are related to all parties such as owner, main and subcontractor, labour. But analyzing some relationship between main and subcontractor is very important to estimate what risk between then are existed in a site. There are some different aspects concerning with risk management between them. Everywork has its own risk in there, This is the reason why everywork which are made by subcontractor himself should be evaluated for risk level. And main contractor should provide for subcontractor to prevent each risk at the work, all the time.

• International Journal of Highway Engineering
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• v.15 no.2
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• pp.57-63
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• 2013

PURPOSES : This study was performed to investigate a feasibility of job-site use of recycled concrete aggregate exceeding 3% of absorption rate. Test variables are coarse aggregate types such as natural aggregate, job-site processed recycled aggregate, and recycled aggregate processed from the intermediate waste treatment company. METHODS : First, aggregate properties such as gradation, specific gravity and absorption rate were determined. Next a basic series of mechanical properties of concrete was tested. RESULTS : All strength test results such as compression, flexure and modulus were satisfied for the minimum requirements. Finally up to first 48 elapsed days the shrinkage strains of concretes made from both recycled aggregates (in case of volume-surface ratio of 300) appeared to be greater than 26% of the companion concretes made from natural aggregates. CONCLUSIONS : Drying shrinkage result is ascribed to greater absorption rate and specific gravity of those specimens made from recycled aggregate. This may be reduced with an addition of admixtures.

• Journal of Aerospace System Engineering
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• v.3 no.1
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• pp.6-11
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• 2009

It is anticipated that quality assurance for the Ka band Communication Payload System(COPS) development program of the communication, Ocean & Meteorological Satellite(COMS) may be a core technical factor to be concerned in order to avoid any failure, and to assure its final performance during the mission lifetime in space. Those can be managed and verified and assessed by performing the Quality Assurance (QA) and risk management which helps to prevent and to reduce the critical fails. This paper introduces the Product Assurance (PA) system and procedures for controlling and monitoring sub-contractors which were participated in Ka band Communication Payload System (COPS) development. Also this paper shows Quality Assurance (QA) procedures and detailed their processes for assured the product performed by local companies from site survey for selecting companies to delivery of their equipment.

• 한국지구물리탐사학회:학술대회논문집
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• 2007.06a
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• pp.237-240
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• 2007

The evaluation of shear modulus (or shear wave velocity) profile of site is very important in the various fields of geotechnical engineering. To obtain shear wave velocity profile, various in-situ seismic methods using surface waves have been developed. These surface wave based in-situ seismic methods have their own strength and weakness. In this study, new seismic site characterization method using the harmonic wavelet analysis of wave (HWAW) was proposed to overcome some of weaknesses in the existing surface wave based seismic site characterization methods. HWAW method which is based on time-frequency analysis using harmonic wavelet transform have been developed to determine phase and group velocities of waves. In order to estimate the applicability of HWAW method, field tests were performed. Through field applications and comparison with other test results, the applicability of the proposed method were verified.

• Journal of Environmental Science International
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• v.6 no.3
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• pp.205-211
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• 1997

For the prediction of multi-site rainfall with radar data and ground meteorological data, a rainfall prediction model was proposed, which uses the neural network theory, a kind of artifical Intelligence technique. The Input layer of the prediction model was constructed with current ground meteorological data, their variation, moving vectors of rain- fall field and digital terrain of the measuring site, and the output layer was constructed with the predicted rainfall up to 3 hours. In the application of the prediction model to the Pyungchang river basin, the learning results of neural network prediction model showed more Improved results than the parameter estimation results of an existing physically based model. And the proposed model comparisonally well predicted the time distribution of ralnfall.