• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.414-418
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• 2008

The effects of paper properties such as density, air permeability, water vapor transmission rate on the thermal performance of plate-type enthalpy exchanger were experimentally investigated. Three enthalpy exchanger samples having different properties were made, and were tested according to the standard test procedure (KS B 6879). Effective efficiencies were defined, which accounted for the air leakage between supply and exhaust streams. Results showed that paper density affected the sensible heat transfer of the samples. Sensible heat transfer increased with density of the paper. It was also shown that water vapor transmission rate alone was not a proper indicator for the efficiency of latent heat transfer. Air permeability should also be considered for adequate evaluation of the latent heat transfer. Best performance was obtained for the sample having highest paper density and moderate water vapor transmission ratio.

• 한국입자에어로졸학회지
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• 제6권2호
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• pp.81-90
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• 2010

Several studies have suggested the possibility of airborne transmission of infectious diseases such as tuberculosis, pandemic influenza. because the number of patients increases explosively, if infectious disease had a high basic reproduction number, pharmaceutical interventions such as vaccination, chemoprophylaxis in the early stage of epidemic. Thus, non-pharmaceutical interventions such as mask-wearing, installing air cleaners, school closure are important to control and prevent the infectious diseases. However, the current technology on the mask, air cleaning, ventilation, and etc., seems to be not originated from the understanding of infection via airborne transmission. It is important to estimate the aerodynamic behavior of saliva droplets by coughing or speaking in order to understand the phenomena of airborne infection. In addition, the prediction of transmission of infectious diseases through the air is critical to prevent or minimize the damage of infection. In this review, we reviewed the recent studies on the airborne infection by focusing on the aerodynamic characteristics of saliva droplets and modeling of airborne transmission.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2007년도 정기 학술대회 논문집
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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.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 하계학술대회 논문집 C
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• pp.1337-1340
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• 1995

For the purpose of rational design of air insulation, it is need to experiment with similar to real shape test object and conform the characterisics. But basic distances of air insulation of transmission line, tower, etc. can be acquired from flashover characteristic of rod-rod, rod-plane electrodes. In this paper, before field test of 765kV transmission line for determination of distances of phase to ground insulation, we execute lightning, switching impulse test with test electrod(rod-rod, rod-plane) against clearances of air insulation. Each tests use up-down method and consist of 30 times flashover test. Flashover data treatment program and air correction program following IEC 60-1(1987) standard were completely builted.

• Journal of Information Technology Applications and Management
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• 제28권6호
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• pp.87-95
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• 2021

Recently interest for air pollution is gradually increasing. However, according to the environmental assessment of air quality, the level of air pollution in the nation is quite serious, and air pollutants measuring facilities are also not enough. In this paper, a secure air pollutants sensor system based low power wireless communication is designed and implemented. The proposed system is composed of three parts: air pollutants measuring sensors module, LoRa-based data transmission module, and monitoring module. In the air pollutants measuring module, the MSP430 board with six big air pollutants measuring sensors are used. The air pollutants sensing data is transmitted to the control server in the monitoring system using LoRa transmission module. The received sensing data is stored in the database of the monitoring system, and visualized in real-time on the map of the sensor locations. The implemented air pollutant sensor system can be used for measuring the level of air quality conveniently in our daily lives.

• 한국군사과학기술학회지
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• 제13권2호
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• pp.243-251
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• 2010

The military has been putting great efforts into applying data communication on existing voice communication systems being used in NCW(Network Centric Warfare). Data communication will be an effective choice in one of many effort to yield a minimum kill chain, comparing to legacy voice communications, when tactical units conduct their missions. However, the required budget will be enormous, in case of the replacement of a lot of legacy communication systems with new one. As a cost-effective alternative, the tactical data communication systems using the conventional radio systems instead of the development of new radio systems has been proposed. It is mandatory, though, to ensure QoS while maintaining data communication by making use of legacy radio systems already in use. This paper focuses on the performance issues experimented and analyzed for tactical data communication through the legacy radio systems as the first step towards guaranteed QoS. We have conducted various experiments such as the transmission error rate on certain tactical messages, performance evaluation of redundant transfers, the relationship between the transmission frame size and rate of error, the identification of error points in the transmission frame, and techniques to reduce the errors in both hopping and non-hopping modes. As a result of the performance experiments, The adaptive communication module which decides the redundant transmission or the Forward Error Correction(FEC) technique by analyzing channel status and current transmission status(hopping/non-hopping) of the legacy radio should be designed. the FEC technique in non-hopping, and the redundant transmission technique in hopping mode was recommended from the result of experiment with the frame size is 20bytes in non-hopping and 10Bytes frame size in hopping mode.

• Journal of Mechanical Science and Technology
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• 제19권8호
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• pp.1568-1575
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• 2005

The calculation of the transmission loss of the silencers with complicated internal structures by the conventional BEM combined with the transfer matrix method is incorrect at best or impossible for 3-dimensional silencers due to its inherent plane wave assumption. On this consideration, we propose an efficient practical means to formulate algebraic overall condensed acoustic equations for the whole acoustic structure, where particle velocities on the domain interface boundaries are unknowns, and the solutions are used later to compute the overall transfer matrix elements, based on the multi-domain BEM data. The transmission loss estimation by the proposed method is tested by comparison with the experimental one on an air suction silencer with perforated internal structures installed in air compressors. The method shows its viability by presenting the reasonably consistent anticipation of the experimental result.

• 반도체디스플레이기술학회지
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• 제23권1호
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• pp.104-109
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• 2024

In this paper, we propose structures of a socket that can improve signal transmission characteristics compared to the existing silicone rubber socket. A coaxial rubber socket was proposed to improve signal distortion due to electromagnetic interference between signal lines. And an air gap rubber socket was proposed to improve the degradation of reflection characteristics due to high dielectric constant. Using a 3D electromagnetic field simulator, the S-parameter and crosstalk of the three sockets were compared and the signal transmission characteristics were analyzed. In both coaxial rubber socket and the air gap rubber socket, S-parameter and crosstalk were improved compared to the silicone rubber socket. Among them, the air gap rubber socket was the best for S-parameter, and the coaxial rubber socket was the best for crosstalk.

• 한국항만학회지
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• 제8권1호
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• pp.31-40
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• 1994

Experimental study is carried out to verify the advantages of an air chamber structure in controlling the wave transformation and its dynamic responses. The open, cross and vertical mooring systems are employed in experiments to investigate the variations of wave transmission ratio, natural period of the structures and tensile force acting on the mooring line according to the change of the initial air depth inside the air chamber structure. Experimental results show that the air chamber floating structure expresses the smaller wave transmission ratio and tensile force acting on the mooring line than general one without air chamber, expecially in the long period region of incident wave. Therefore, it is concluded that the air chamber structure suggested in this study can play good roles as a wave controlling castal structure, and a substitute structure of a general floating structure.

• 소음진동
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• 제9권4호
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• pp.795-805
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• 1999

Rubber mounts so called grommets and pipes are two major paths of vibration transmission from a compressor, an important vibration source in an air conditioner, to the whole unit. A procedure of configuring the suction and discharge pipes of the compressor was developed in this paper so as to reduce the vibration transmission through the pipes as well as the grommets. Through investigating the effects of shapes and connecting disrections of pipe elements on vibration transmission, a guideline to configure the pipe layout, which enables to reduce vibration transmission, was proposed. The initial pipe layout by the guideline was optimized with the objective function, minimization of boty vibration transmission and the cost, and with the constraints to yield the final dimensions of the pipes. The procedure not only minimizes the transmitted force to the circumferential devices but enables to eliminate rubber blocks or dampers, which are generally used to avoid resonances of the pipe system.