• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.27-32
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• 2009

The measuring apparatus such as heat meter is legally obliged to be installed and used for heat rating with heat or flow rate in residential buildings in Korea. There are two kinds of apparatus to measure heat consumed at each households, i.e., heat meter and hot water flowmeter. Contrast to the most of buildings with hot water flowmeter well being used for rating, heat meters have been used only 42.6% in the buildings with central heating system. But there is a critical problem in the course of using hot water flowmeter for heat rating, yielding distorted and unfair result which is different from the real value of heat supplied. Experiments with several parameters were carried out in this study to analyze this phenomenon quantively and alternative methods were proposed for rational heat rating.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.17 no.6
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• pp.29-37
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• 2014

The objective of this study is to estimate the cost and benefits of street trees for their planting types, specifically, single row, single row+bottom, double row, double row+bottom. Different planting types are compared and analyzed by using Net Present Value (NPV) and benefit-cost ratio (BCR). Existing data are collected from the literature reviews for the use of meta-analysis method for estimating cost and benefit. The elements for analyzing costs are management and planting costs, and benefits are air purification, energy saving and landscape view. The discount rate is applied at a minimum of 3% and a maximum of 5.5%. The unit used in this calculation is km/year. The result shows that the net benefit is highest in double row, followed by single row, double row+bottom, and single row+bottom. The BCR is the highest in double row, followed by single row, double row+bottom, and single row+bottom. The BCR reaches the break-even point from 9 to 17 years depending on the planting types.

• Journal of Korean Society of Water and Wastewater
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• v.27 no.6
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• pp.703-709
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• 2013

Among many microalgae cultivation types, heterotrophic culture with low cost carbon sources and energy saving culture method is crucial. A result of estimating the effects of pH on wastewater treatment using heterotrophic growing microalgae Chlorella sorokiniana shows that there was no difference in microalgae growth amount and nitrogen, phosphorus removal rate by wide range of pH(5 ~ 9). From pH 5 to 9, total nitrogen, phosphorous and glucose removal rates were 10.5 mg-N/L/d, 2 mg-P/L/d, 800 ~ 1000 mg/L respectively. This study reveals that C. sorokiniana cannot metabolite glycerol heterotrophically, however, glucose and acetate were proper carbon sources for growth and T-N, T-P and TOC removal. This research highlights the potential of heterotrophic microalgal growth with wastewater treatment plant with wide range of pH and carbon sources.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2016.05a
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• pp.207-208
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• 2016

The most important things for the production of recycled aggregates are saving energy, suppressing the generation of by-product fine particles and sustaining the performance of concrete. As solutions, this study proposes this technology of improving the performance of recycled aggregates through forced carbonation.1) It is to stimulate and carbonate the bond paste part that causes the deterioration of recycled aggregates. Particularly, the purpose of this technology is to fill and chemically stabilize pores inside the bond paste, further improving the quality of recycled aggregates with a decreased absorption rate and an enhanced aggregate strength. Ultimately, it is possible to obtain a carbonation model, depending on the paste ratio and particle-size distribution of recycled aggregates. Moreover, by calculating the optimum carbonation period through the verification of this carbonation model, it is possible to examine how much the strength is improved by the reformation of recycled aggregated.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.6C
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• pp.603-613
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• 2006

Low-power design is one of the most important challenges encountered in maximizing battery life in portable devices as well as saving energy during system operation. In this paper we propose a low-power DCT (Discrete Cosine Transform) architecture using a modified Computation Sharing Multiplication (CSHM). The overall rate of Power consumption is reduced during DCT: the proposed architecture does not perform arithmetic operations on unnecessary bits during the Computation Sharing Multiplication calculations. Experimental results show that it is possible to reduce power dissipation up to about $7\sim8%$ without compromising the final DCT results. The proposed low-power DCT architecture can be applied to consumer electronics as well as portable multimedia systems requiring high throughput and low-power.

• Proceedings of the SAREK Conference
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• 2005.11a
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• pp.33-38
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• 2005

A hybrid ventilation system was introduced to predict the ventilation performance of the apartments. This ventilation system was composed of the natural supply-air inlet and the forced exhaust-air outlet. Analysis was conducted by CFD technique and was performed on three ventilating flow rates; 30, 60, 120 $m^3/h$. As the results, residents feel comfortable thermally and in air flow conditions for 60 $m^3/h$. But the case of 30 $m^3/h$ shows 1100ppm of $CO_2$ concentration due to the deficient of air flow rate. In the case of 120 $m^3/h$, however, residents feel uncomfortable thermally and in air currents. In this study the energy saving for space heating is also an important factor. A detailed prediction for more complicated whole apartment space will be investigated in the future.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.29 no.3
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• pp.142-147
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• 2017

Improvement of the enthalpy exchange element's energy efficiency is of current interest from anenergy-saving viewpoint. In this study, a LiCl-impregnated spacer was devised as a means to improve the performance of the enthalpy exchange element. Two samples were tested : one with and one without impregnated spacers of $338{\times}338{\times}380mm$ sizes with 2.0 mm channel spacing. The results showed that the temperature efficiencies of the two samples were approximately the same. The humidity efficiency, however, was strongly affected by the LiCl impregnation. The impregnated sample yielded a 9% higher humidity efficiency under cooling and the difference increased to 14% under aheating condition. It was anticipated that more moisture would beadsorbed on the LiCl-impregnated spacers, which was delivered to their roots and eventually to the air in neighboring channels. Separate moisture adsorption tests revealed that both the adsorption rate and the amount of the adsorbed moisture are higher for the LiCl-impregnated specimen.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.1
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• pp.181-187
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• 2012

LED is just a semiconductor which can produce light. Currently, there are active research works on LED lighting technologies according to the growth of energy-saving environmental industry. Especially, LED communication is one of the active research works in these fields. In this paper, we design a LED communication-based PC-PC transmission system. A transmission circuit system(transmitter) using LED and a receiving circuit system(receiver) using PD(photo detector) and Op-amp are designed, respectively. The experiments for the designed system are performed as follows. One computer is connected at the end of transmitter and receiver, respectively, and text files are transmitted by using text transmission programming. In this experiment, we test the performance with various baud rates, LED colors, transmission ranges.

• Proceedings of the SAREK Conference
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• 2007.11a
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• pp.105-112
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• 2007

Recently developed raised floor heating system is not only capable of basic function to reduce noise between floors, but also is a multi-functional floor heating system enabling natural ventilation. The procedure of this system for natural ventilation is to import outdoor air through bottom space of the floor heating system, circulate indoor space and discharge it out of ceiling. In winter, powerless natural ventilation is possible with buoyancy effect caused by temperature difference between outdoor and indoor. And it also allows saving of energy by importing pre-heated air in bottom space of the floor heating system. To evaluate ventilation performance of this system, on-site measurement was conducted in 2 test laboratories, and the nominal air change rate was satisfied as 0.4$\sim$0.8 h-1 under the condition of outdoor temperature $5^{\circ}C{\sim}-5^{\circ}C$, which was evaluated as highly possible to be applied as a natural ventilation system in multi-family houses.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.15 no.1
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• pp.118-124
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• 2001

To guide the esti-on of electric d e d and energy saving, this proposed the Power Laaddensity, Elechic pwer consumption and the installed state of Power facility. For this purp~se, it wasconducted a questionnaire survey of the consumption-cattern of Electric power in 1W a p a r t t housings.As a 1-esult it is found that (i) the d m u m value of Power Load density is 7.70[~A/m"l, (ii) the avtragevalue of Power Load dens'||'&'||' is ~ . ~ A / mm' dl (iiijthe average load rate is Ed[%]. Also, the consumptionof electricity one year at tlie whole a m n t s of couniry is 14,0X[GWyearl, it was equivalent to 7[%1 ofthe total-consunmhon of electricity one year at the whole of co1mtnr. co1mtnr.