• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.10a
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• pp.727-732
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• 2009

The objective of this study is to analyze and evaluate design factors relating to sound reduction performance in dry wall system. The main contents of this study are as follows. 1) Analysis and pre-evaluation of sound reduction performance of drywall system ; The sound reduction performance was pre-evaluated by INSUL simulation and these results of analyzing walls were analyzed by screening DOE(design of experiment) for selecting major factors that dominant influence the sound reduction performance. These main factors relating to sound reduction performance can be used for development of 1st grade sound reduction performance drywall system. 2) Design and evaluation of 1st grade sound reduction performance drywall system; The evaluation test of the sound reduction performance gave vaues higher than 1st grade (Rw+C=64). When campared with existing dry wall system, respectivelly, the new system shows performance higher than 8 dB.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.2 s.107
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• pp.107-114
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• 2006

The present experimental study deals with noise reduction and improvements in cooling performance in a plasma display panel (PDP) television (TV). The main ideas of the fan system noise reduction are maintenance of uniform inflow condition and reduction of the system loss, ${\Delta}P.$ The discrete noise is mainly related with the inflow condition therefore removing the structure which distorts inflow makes the discrete noise reduction. The broadband noise in PDP TV is related with the system losses which result from the presence of the fan downstream obstacle, PDP rear case. Through the modification of the distance and preventing the leakage flow between the fan and rear case, we can obtain the system loss and broadband noise reduction. Additionally we can reduce fan rotating speed because of increased flow rate which obtains from the reduction of system loss (resistance). Finally, 4.2 dB(A) noise reduction and $10\%$ increase in flow rate are achieved. From these results, we show that the reduction of system loss is the most effective way of the fan system noise reduction.

• Korean System Dynamics Review
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• v.14 no.1
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• pp.55-68
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• 2013

It is necessary to evaluate the greenhouse gases (GHGs) reduction policy by central and regional governments to set up the suitable GHG emissions measures. Quantitative, qualitative and synthetic methods have been adopted by previous researches to estimate GHG reduction policy. However, these methods mostly focused on the results of the reduction policy, rather than understanding and fixing the integrated structures of GHG emissions. In this research, System Dynamics(SD) was applied to 1 million green homes program, self-carfree-day system and carbon point program. The results showed that SD analyses could be appliable for the estimation of GHG reduction policy by developing the feedback loops and dynamic simulation model. SD can be consider as a supplementary tool to estimate the GHG reduction policies through the recognition of the structure in complex real system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.15 no.7
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• pp.553-564
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• 1990

The co-efficient matrix of linear second-order partial differential equations in the general form is partitioned with (n-1)x(n-1) submartices and is transformed into the block tridiagonal system. Then the cyclic odd-even reduction technique is applied to this system with the large-grain data granularity and the block cyclic reduction algorithm to solve unknown vectors of this system is created. But this block cyclic reduction technique is not suitable for the parallel processing system because of its parallelism chanigng at every computing stages. So a new algorithm for solving linear second-order partical differential equations is presentes by the block cyclic reduction technique which is modified in order to keep its parallelism constant, and to reduce gteatly its execution time. Both of these algoriths are compared and studied.

• Nuclear Engineering and Technology
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• v.35 no.1
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• pp.25-34
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• 2003

The research on the development of the fault monitoring system for the thermal reduction reactor has been performed preliminarily in order to support the successful operation of the thermal reduction reactor. The final task of the development of the fault monitoring system is to assure the integrity of the thermal$_3$ reduction reactor by the acoustic emission (AE) method. The objectives of this paper are to identify and characterize the fault-induced signals for the discrimination of the various AE signals acquired during the reactor operation. The AE data acquisition and analysis system was constructed and applied to the fault monitoring of the small- scale reduction reactor, Through the series of experiments, the various signals such as background noise, operating signals, and fault-induced signals were measured and their characteristics were identified, which will be used in the signal discrimination for further application to full-scale thermal reduction reactor.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.333-333
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• 2000

When the generalized singular perturbation method is used for model reduction, the state variables of the original system is reconstructed from the reduced order model. The state reduction error is defined, which shows how well the reconstructed state variables approximate the state variables of the original system equation.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.1117-1121
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• 2008

Recently energy consumption and $CO_2$ emission issue are important problem on international society. The present study has been conducted economic analysis considering economical value of $CO_2$ reduction effect. We analyze annual energy cost and annual $CO_2$ emission of the cogeneration system and gas boiler system in hotel. The first results shows that annual energy cost of cogeneration system (751,740,126 won) is more profitable than gas boiler system (801,128,408 won) by 6.2% (49,388,281 won). The second results shows that annual $CO_2$ emission of cogeneration system (3,297 ton) is less than gas boiler system (3,536 ton) by 6.8% (239 ton). The Economical value of $CO_2$ reduction effect is 4,773,898 won. The cost effect according to the reduction of $CO_2$ is corresponding to 9.7% of reduction cost for total energy cost. The result of this study means that $CO_2$ reduction effect is essential item in introduction and change of facility for economic analysis.

• Journal of Powder Materials
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• v.12 no.1
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• pp.56-63
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• 2005

Ag powder was prepared from $AgNO_3$ by wet chemical reduction method using various reduction agent system involving $AgNO_3$, $AgNO_2$(AgCl) and Ag complex ion aqueous solution. The pure Ag powder could be prepared regardless of reaction system but the particle shape and distribution were affected very much according to the kind of reduction agents and reaction systems. The optimum reaction system for the preparation of the silver powder having the uniform particle shape and size distribution was Ag complex ion aqueous solution-reduction agent system and in particular, $H_2O_2$ and $C_6H_8O_6$as a reduction agent leaded the more uniform particle shape and size distribution.

• Nuclear Engineering and Technology
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• v.51 no.3
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• pp.719-722
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• 2019

Gamma-ray images generally suffer from a lot of noise because of low photon detection in the gamma camera system. The purpose of this study is to improve the image quality in gamma-ray images using a gamma camera system with a fast nonlocal means (FNLM) noise reduction algorithm with an acceleration function. The designed FNLM algorithm is based on local region considerations, including the Euclidean distance in the gamma-ray image and use of the encoded information. To evaluate the noise characteristics, the normalized noise power spectrum (NNPS), contrast-to-noise ratio (CNR), and coefficient of variation (COV) were used. According to the NNPS result, the lowest values can be obtained using the FNLM noise reduction algorithm. In addition, when the conventional methods and the FNLM noise reduction algorithm were compared, the average CNR and COV using the proposed algorithm were approximately 2.23 and 7.95 times better than those of the noisy image, respectively. In particular, the image-processing time of the FNLM noise reduction algorithm can achieve the fastest time compared with conventional noise reduction methods. The results of the image qualities related to noise characteristics demonstrated the superiority of the proposed FNLM noise reduction algorithm in a gamma camera system.

• Journal of the Korea Safety Management & Science
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• v.20 no.3
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• pp.1-9
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• 2018

This study is intended to look into the effect of construction safety supervision system on risk control and reduction. To achieve this, a survey was carried out to 114 companies in construction, ordering, contract and management. The overall findings were as follows. The effect of construction safety supervision system on risk control and reduction showed that factors of supervision system, supervision cost and supervision method had a positive effect on risk control and reduction. And their perception of the introduction of safety supervision system in construction sites according to process showed that there was a difference between them according to the field of ordering, contract and supervision. There was the biggest difference between owner and contractor in double supervision system, but no difference between them in the perception of risk reduction. These results show that all ordering, contract and supervision are positively needed for the introduction of construction safety supervision. This means that there is a difference between owner and contractor in the perception of process according to system operation. All companies agree to system improvement by the settlement of safety supervision system for the prevention of safety accidents and safe construction, but the systematic complement of safety supervision is the burden of contractor. And there is a big difference between owner and contractor in the perception of responsibility and concern for cost burden.