• Proceedings of the Computational Structural Engineering Institute Conference
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• 2007.04a
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• pp.309-314
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• 2007

Optimal layer sequencing of a multi-layered acoustical foam is solved to maximize its sound transmission loss. A foam consisting of air and poroelastic layers can be optimized when a limited amount of a poroelastic material is allowed. By formulating the sound transmission loss maximization problem as a one dimensional topology optimization problem, optimal layer sequencing and thickness were systematically found for several frequencies. For optimization, the transmission losses of air and poroelastic layers were calculated by the transfer matrix derived from Biot's theory. By interpolating five intrinsic parameters among several poroelastic material parameters, dear air-poroelastic layer distributions were obtained; no filtering or post-processing was necessary. The optimized foam layouts by the proposed method were shown to differ depending on the frequency of interest.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.430-431
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• 2011

Recently the power system consists of the more complicated structure, due to increase of power demands. In this circumstance, the congestion and loss capacity in transmission line is also increased. Accordingly, the investment planning of transmission system is required to reduce the congestion and loss of the transmission line. In study of the planning of domestic and international transmission expansion, the reliability of transmission planning and minimizing Investment cost is focused. However, the study has not been performed systematically in economic aspects. Typically, the congestion and loss costs have been individually calculated. It is not consider the mutual relationship between the congestion cost and the loss cost. This paper proposes a method to compute concurrently the congestion and loss costs. This purpose is to calculate the more exact value for economic assessment of the power system operation.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.50 no.1
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• pp.10-14
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• 2001

The superconducting transmission cable is one of interesting part in power application using high temperature superconducting wire. One important parameter in HTS cable design is transport current sharing because it is related with current transmission capacity and loss. In this paper, we calculate self inductances of each layer and mutual inductances between two layers from magnetic field energy, and current sharing of each layer for 4-layer cable using the electric circuit model which contain inductance and resistance (by joint and AC loss). Also, transport current losses which are calculated by monoblock model and Norris equation are compared. As a results, outer layer has always larger transport current than inner layer, and current capacity of each layer is largely influenced by resistance per unit cable length. As a conclusion, for high current uniformity and low AC loss, we have to decrease inductances themselves or those differences.

• KIEE International Transactions on Power Engineering
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• v.5A no.2
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• pp.193-198
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• 2005

This paper proposes a new method to handle transmission line losses using loss distribution factors (LDF) rather than marginal loss factors (MLF) in electricity market operation. Under a competitive electricity market, the bidding data are adjusted to reflect transmission line losses. To date the most proposed approach is using MLFs. The MLFs are reflected to bidding prices and market clearing price during the trading and settlement of the electricity market. In the proposed algorithm, the LDFs are reflected to bidding quantities and actual generations/ loads. Computer simulations on a 9-bus sample system will verify the effectiveness of the algorithm proposed. Moreover, the proposed approach using LDFs does not make any payments residual while the approach using MLFs induces payments residual.

• Journal of Advanced Marine Engineering and Technology
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• v.33 no.5
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• pp.653-661
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• 2009

In order to reduce the noise and oscillation, it is consider a matter in all aspects about the noise stem from accumulator and the characteristic of transmission, Transformation of outside shape has change of noise occurrence at transmission process. Therefore, performed sound numerical analysis and conducted an experiment to examine the birthplace of accumulator's external shape change. In a sound numerical analysis, we can fond out transmission loss between inlet and outlet's sound pressure. In an experiment, we can make out transmission loss by sound wave separation theory through drawing sound pressure inlet and outlet.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.26 no.6
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• pp.1571-1582
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• 2016

One of the issues, which is dealed with in undirectional data transmission technology, is reducing the packet loss in TCP based data transfer. We can decrease the packet loss by using several well known error correction approaches. Although we utilize those previous approaches, the packet loss by both link errror and buffer overflow could be occurred. In this paper, we propose the RED(REliable Data diode). RED also uses the TCP proxy approach for supporting the TCP based data transfer which is similar with the existing unidirectional data transmission technologies. The RED transmission system could alleviate the packet loss caused by buffer overflow by exploiting the delaying transmission of TCP packets. Furthermore, in order to reduce the packett loss caused by link error in the unidirectional transmission link, the RED transmission system transmits one or more duplicated packets to the RED reception system by considering both the remaining resources and packet importance.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.11 s.116
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• pp.1140-1148
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• 2006

In this paper, transmission loss of smart panel was investigated using piezoelectric shunt damping. Admittance of piezoelectric system was introduced to represent electro-mechanical coupling of smart panel and to predict the performance of shunt damping. Finite element method was used to obtain numerical admittance. In order to illuminate the effect of noise reduction in the shunt system, transmission loss of the smart panel was investigated. Two models were considered to show the relation between admittance and transmission loss of smart panel. It was observed that admittance of piezoelectric system could be used as a design index of smart panel.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.701-705
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• 2007

The equipment noise of machine room that generates at the building where human-being is living, is becoming to an object of strong civil appeal, and because it influences to the residential space through the floor or wall, its damage is very serious level. Accordingly, while an efficient forming of the sound insulating measures is earnest, as most of the transmission loss data was the material measured in laboratory, in case when it was applied to the job site, due to the precision difference of constructing work and the influence of detoured transmitting sound, the case of disaccord is the most. Therefore, this thesis has intended to present a fundamental data for an efficient establishment of sound insulation measure, by means of comparison analysis with the existing transmission loss data, after measurement of the transmission loss on the object of various walls, at the construction equipment machinery room.

• Composites Research
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• v.25 no.5
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• pp.154-158
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• 2012

The effect of structure on the sound absorption and sound transmission loss of composite sheet was investigated. A sheet of polypropylene was bonded by hot press with nonwoven fabric sheets of polyethylene terephthalate on the top side and the back side. Absorption coefficient of composite sheet using nonwoven fabric with surface density of $0.64kg/m^2$ was 0.1-0.2. It is 100-400% improvement compare to that of polypropylene sheet. The transmission loss of composite sheet was increased with surface density of polypropylene board and introduction of hemisphere hole on the surface of sheet. Two types of composite sheet were made using flat sheet and sine wave shaped sheet and the effect of sheet structure on the transmission loss was investigated.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.6
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• pp.634-640
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• 2009

Helmholtz resonator has been used, especially in intake and exhaust systems of vehicles, due to its good noise reduction characteristics at low frequencies. Many approaches have been developed to predict the acoustic behavior of the resonator with the assumption that there is no leakage from the resonator. However, its behavior may be affected by leakage which may exist in manufacturing processes or on purpose. This study investigates the effect of leakage on the noise reduction characteristics of Helmholtz resonator with two practical examples. One is a resonator with a gap between baffle and housing of the resonator and the other one is a resonator with two drain holes on the baffle. The measured transmission loss shows that the resonance frequencies are considerably shifted to higher frequency due to the leakage. The Boundary Element Method was applied to predict the transmission loss of the Helmholtz resonator with drain holes. The comparison between the measured and predicted transmission loss shows that the acoustic impedance of the holes is essential for accurate predictions of the transmission loss.