• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.13 no.2
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• pp.58-66
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• 1984

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.333-337
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• 2003

The use of reactive shearing structural intensity to place small patches of constrained layer damping material in order to achieve the largest reduction in the radiated sound power of Air-conditioner outdoor unit is described. The normal surface velocity of each panel was measured using a laser doppler vibrometer. Experimental results indicated that patches of constrained layer damping material placed over areas of high reactive structural intensity reduced the radiated sound power significantly more than patches of the same area placed over areas of low reactive structural intensity

• Journal of Environmental Science International
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• v.20 no.1
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• pp.81-91
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• 2011

Air quality monitoring networks are very important facilities to manage urban air pollution control and to set up an environmental policy. Since air quality monitoring network of Daegu was allocated from 1980s to mid-90s, there is need to reevaluate it and relocated its site. This study was evaluated the position of Daegu air quality monitoring station by unit environmental sensitivity index, grid emission rate, CAI (Comprehensive Air-quality Index) point. The investigation domain covered an area of 16 $\times$ 24 km centered at the metropolitan area of Daegu with grid spacing of 2 km. The location of alternative air quality monitoring networks was selected through optimization and quintiles analysis of total score. The result showed that all things considered, new air quality monitoring network need to install grid numbers 10, 28, 36, 37, 46. We also recommand three scenarios of alternative air quality monitoring network when considering unit environmental sensitivity index, emission rate and CAI point.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2017.05a
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• pp.237-238
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• 2017

• Journal of Hydrogen and New Energy
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• v.31 no.3
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• pp.322-327
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• 2020

In this work, a study for the reduction of the electric power consumption has been estimated in main air compressors in the air separation unit through cryogenic distillation columns with PRO/II with PROVISION V10.2 at AVEVA company. Both required LNG mass flow rate and cold heat contained in 1 ton of LNG were also predicted using Peng-Robinson equation of state with Twu's new alpha function. Through this work, we concluded that 32.33-48.69% of electric power could be saved by using LNG cold heat.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.18 no.2
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• pp.115-121
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• 2008

In winter season, the survey was performed in three commercial office buildings in the metropolitan Seoul, Pusan, and Gwangju city. The purpose of the survey was to evaluate the effectiveness of ventilation for offices in commercial buildings. The data were compared to standard of applicable to the indoor ventilation in office. The results indicated that the most commercial office buildings used the air handing unit and fan coil unit as HVAC system, and the intake amount of fresh outdoor air were very inadequate to compared to the ASHRAE standard value of $0.57\;m^3/min/person$. Also the surveyed all commercial office building used the HVAC system as a meas of controlling temperature for office indoor air. Ultimately, these results presented that there were possibility of evoking indoor air quality problems by the insufficient ventilation.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.324-329
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• 2003

An air-conditioner has various noise sources such as cooling fan noise, pumping noise, flow noise and impact noise. Among these, impact noise is the most unpleasant source. This is because the noise is produced in indoor unit of air-conditioner. To control the noise source effectively, first we must identify the noise sources. When we identify impact noise source, the measurement have to be carried out simultaneously. So we use beamforming method that requires less measurement points than intensity method and acoustic holography. The objective of this paper is to estimate the location of impact source. This objective can be achieved by using minimum variance cepstrum that is able to detect impulse embedded in noise. In this study, modified beamforming method based on cepstrum domain is proposed. Then this method applied to air-conditioner noise sources which produce impact noise.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.957-963
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• 2008

The refrigerant-induced noise of the air conditioner is one of the irregular noises which occurs at the indoor unit. Because the air-conditioner makers are always trying to reduce the sound pressure level radiated from indoor unit, reducing the refrigerant-induced noise at low cooling mode is very important problem. But it is very difficult to estimate whether the refrigerant-induced noise occurs or not before it becomes problem. In this paper, a method to predict the refrigerant-induced noise is suggested using flow pattern map. It is estimated that the irregular noise from the refrigerant comes from the slug flow in a pipe.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.28 no.1
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• pp.42-47
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• 2016

Adjacent housing units suffer inevitable thermal losses if an unheated unit exists in an apartment building. Thermal loss of the units adjoining the unheated apartment can be neglected because the contact area is small and insulators are located in the walls. When insulators are not included in the slab between the upper and lower units, 70% of the heat supplied by an Ondol system may be used in the original unit, but 30% is transferred to the unit on the lower floor. Another 30% can be obtained from the ceiling if the upper floor housing unit is heated. This strong thermal connection is a characteristic of Ondol heating in apartment buildings. When there is an unheated unit, the lower floor unit uses 42.3% more heating energy if there is no insulation and 19.5% if a 35 mm insulator is used as in the current guidelines. Therefore, much thicker insulation should be applied to weaken the thermal connection.

• ETRI Journal
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• v.32 no.2
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• pp.195-203
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• 2010

A new vertical transition between a substrate integrated waveguide in a low-temperature co-fired ceramic substrate and an air-filled standard waveguide is proposed in this paper. A rectangular cavity resonator with closely spaced metallic vias is designed to connect the substrate integrated waveguide to the standard air-filled waveguide. Physical characteristics of an air-filled WR-22 to WR-22 transition are compared with those of the proposed transition. Simulation and experiment demonstrate that the proposed transition shows a -1.3 dB insertion loss and 6.2 GHz bandwidth with a 10 dB return loss for the back-to-back module. A 40 GHz low-temperature co-fired ceramic module with the proposed vertical transition is also implemented. The implemented module is very compact, measuring 57 mm ${\times}$ 28 mm ${\times}$ 3.3 mm.