• Transactions on Electrical and Electronic Materials
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• v.18 no.4
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• pp.221-224
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• 2017

This paper dealt with the extraction of series arc signals based on wavelet transform in order to improve the accuracy of arc detection in indoor wiring systems. Three types of arc sources including a cord-cord, a terminal-cord, and an outlet-plug were fabricated to simulate typical arc defects. An arc generator fabricated according to UL 1699 was used to generate arcs. The optimal mother wavelet was selected as bior1.5 by calculating the correlation coefficients between the detected single current pulse and the wavelet. The detected arc current signals were then decomposed into eight levels using the discrete wavelet transform that implements the multi-resolution analysis method. By analyzing the decomposed components, the detail components D6, D7, and D8 were associated with arc signals, which were used for signal reconstruction. From the result, it was verified that the proposed method can be used for the extraction of the series arc signal from the AC mains, which is expected to be applied to further analysis of arc signals in indoor wiring systems.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.128-131
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• 2011

Management of indoor air quality of underground subway station is an important issue. The air handling unit (AHU) installed in the underground subway station is the main facility determining the air quality of station. Especially for removing particulate matters, it is important to operate the appropriate air filter. In this study, we studied particle collection efficiency of axail-flow cyclone for subway AHU. The particle collection efficiencies of axial-flow cyclones with three different outlet shape have been evaluated.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.1267-1271
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• 2009

In the present study, performance characteristics on environment change of A/C applied fin-tube and PF heat exchangers were experimentally investigated. Capacity and COP changing an outlet air velocity, an indoor/outdoor temperature and a relative humidity were obtained. Air－enthalpy calorimeter was used. As the air velocity, indoor temperature and relative humidity increase, capacity and COP increase. PF A/C has smaller refrigerant weight than the fin-tube A/C. The performance of PF-2 A/C with the squarer fin was more excellent than that of PF-1 A/C with the triangler fin.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.9
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• pp.855-862
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• 2005

An experimental investigation has been carried out for aluminum foam heat sink inserted into the annulus to examine the feasibility as a heat sink for high performance forced water cooling in the annulus. The local wall temperature distribution, inlet and outlet pressures and temperatures, and heat transfer coefficients were measured for heat flux of 13.6, 18.9, 25.1, 31.4 $kw/m^2$ and Reynolds number ranged from 120 to 2000. Experimental results show that the friction factor is higher than clear annulus without aluminum foam, while the significant augmentation in Nu is obtained. This technique can be used for the compactness of the heat exchanger.

• Journal of the Korean Society of Industry Convergence
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• v.27 no.5
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• pp.1209-1215
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• 2024

In this study, fundamental research was conducted on the development of an adsorption-desorption ventilation system incorporating thermoelectric elements to improve indoor air quality (IAQ) and energy efficiency. The experiment was conducted using a thermoelectric module and silica gel as a commonly used adsorbent to evaluate the cooling and heating effects during the adsorption and desorption process. The main experimental results show that applying 3W power to the thermoelectric module reduces the outlet air temperature and improves the adsorption efficiency, while excessive power (4-5W) reduces the adsorption efficiency due to increased heat load. Additionally, when the flow rate on the adsorption side is increased, the completion time decreases. On the other hand, if the flow rate on the desorption side is increased, the completion time is also shortened. It was confirmed that as the flow rate increases, the movement of heat and moisture generated during the adsorption and desorption process becomes faster, and the reaction progresses more quickly.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2009.10a
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• pp.286-288
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• 2009

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.1207-1212
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• 2008

The purpose of this study is to evaluate the location of the outlets in the mechanical ventilation system installed in apartment. We performed the numerical analysis to estimate the ventilation effectiveness and the indoor $CO_2$ concentration considering the occupants and the condition with inlet and outlet in each room. From the numerical results, modified location of the outlets is about 10% high than designed one with respect to the ventilation effectiveness when the occupants are not considered. But designed location of inlet and outlet in living room and kitchen is better than modified one with respect to the reduction of $CO_2$ concentration in the living room and kitchen with occupants. In case of our model, Air change per hour (0.7) is not enough to sustain the acceptable criteria of $CO_2$ concentration (1000ppm) in the room with the occupants

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.24 no.4
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• pp.351-357
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• 2012

To reduce the summertime cooling load of a plant factory, a concept design was performed for the double skin window which utilizes the low temperature air from a ground coupled heat exchanger. The design parameters were selected as the number of cavity air inlet, the cavity thickness, the location of cavity air inlet, and the configuration of cavity air outlet. A parametric study was conducted in a systematic way to evaluate the heat transfer characteristics of the double skin window. As the number of cavity air inlet and the cavity thickness increase, the heat flux from outside air to indoor air was decreased. The effect of the location of cavity air inlet was not significant and the larger cavity air outlet area gave us relatively better heat blocking performance from outside hot air. This study demonstrated that it is possible to develop an improved double skin window by utilizing a ground coupled heat exchanger.

• Journal of the Korean Solar Energy Society
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• v.26 no.4
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• pp.9-16
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• 2006

Geothermal-energy has been getting popular as a natural energy source for green buildings these days. Public building with gross area more than $3000m^2$, planned after March, 2005, should spend about 5% of total building cost for equipment run by natural energy source (e.g. geothermal, solar heat, solar power, etc) according to renewable energy promotion law in Korea. As a result geothermal-energy using heat pump system is emerging as a effective alternative for realistic and economic plan although design guidelines and construction code for the system is in progress and technical data is far from sufficient. The quantitative analysis on the performance of geothermal-energy using heat pump system is insufficient for appropriate design of it. In this paper, cooling performance of geothermal-energy using heat pump system of residential and retail etc. mixed-use building has been analyzed on the basis of temperature comparison between inlet and outlet of heat exchangers of the operating system. Additionally, dry-bulb temperature and relative humidity have been measured and analyzed together as an index of indoor thermal environment.

• 유체기계공업학회:학술대회논문집
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• 2002.12a
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• pp.147-151
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• 2002

Cross flow fan system is widely used for various applications, especially for the air-moving device of heaters, air-conditioners, and air-curtains. Although there are efforts for the optimization of cross-flow fan flow path with different methods of approach, it is still being investigated by many researchers through experimentally and/or theoretically, because the flow pattern of the cross flow fan is not stereotyped. This paper presents some results from numerical experiments for the optimization of the flow path through a cross-flow fan to be applied to indoor wall-mounted room heater. Two dimensional analysis has been applied to a specific fan system including inlet and diffuser outlet. Flow characteristics art presented and discussed for two different flow path at three different operating conditions represented by rotational speed(800, 1,000, 1,200 rpm) of the In. According to the simulated results for the specific fan system under consideration, it could be found that the flow pattern resembles each other at different rotational speed (to say from 800 rpm to 1,200 rpm) for a fixed flow path, while the secondary flows mostly absorbs the speed effects. By changing the flow path significant increase in volume flow rate is estimated upto 2.65 at the same rotational speed. According to the present experience, fan flow path design can be performed more efficiently by incorporating this type of numerical experiments combined with the model tests.