• Journal of Korean Society for Atmospheric Environment
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• v.11 no.E
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• pp.45-54
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• 1995

Indoor air quality models are useful to predict indoor air pollutant concentrations as a function of several indoor factors. Indoor air quality model was developed to evaluate the pollutant removal efficiency of variable-air-volume/bypass filtration system (VAV/BPFS) compared with the conventional variable-air-volume (VAV) system. This model provides relative pollutant removal effectiveness of VAV/BPFS by concentration ratio between the conventional VAV system and VAV/BPFS. The predictions agree closely, from 5 to 10 percent, with the measured values for each energy load. As a results, we recommend the VAV/BPFS is a promising alternative to conventional VAV system because it is capable of reducing indoor air pollutant concentration and maintaining good indoor air quality.

• Journal of the Korean Society of Combustion
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• v.6 no.2
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• pp.15-22
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• 2001

A pressure-based, unstructured finite volume method has been applied to couple the chemical kinetics and fluid dynamics and to capture effectively and accurately the steep gradient flame field. The pressure-velocity coupling is handled by two methodologies including the pressure-correction algorithm and the projection scheme. A stiff, operator-split projection scheme for the detailed nonequilibrium chemistry has been employed to treat the stiff reaction source terms. The conservative form of the governing equations are integrated over a cell-centered control volume with collocated storage for all transport variables. Computations using detailed chemistry and variable transport properties were performed for two laminar reacting flows: a counterflow hydrogen-air diffusion flame and a lifted methane-air triple flame. Numerical results favorably agree with measurements in terms of the detailed flame structure.

• Journal of Environmental Health Sciences
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• v.23 no.4
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• pp.57-66
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• 1997

Successful energy conservation and good indcfor air quality (IAQ) are highly dependent on ventilation system. Air filtration is a primary solution of indoor air control strategies in terms of reducing energy consumption and improving ihdoor air quality. A conventional system with bypass filter, as it is called variable-air-volume/bypass filtration system (VAV/BPFS), is a variation of the conventional variable air volume (VAV) systems, which is designed to eliminate indoor air pollutant and to save energy. Bypass filtration system equipped with a high-efficiency particulate filter and carbon absorbent provides additional cleaned air into indoor environments and maintain good IAQ for human health. The objectives of this research were to compare the relative total decay rate of indoor air pollutant concentrations, and to develop a mathematical model simulating the performance of VAV/BPFS. All experiments were performed in chamber under the controlled conditions. The specific conclusions of this research are: 1. The VAV/BPFS system is more efficient than the VAV system in removing indoor air pollutant concentration. The total decay rates of aerosol, and total volatile organic compound (TVOC) for the VAV/BPFS system were higher than those of the conventional VAV system. 2. IAQ model predictions of each pollutant agree closely with the measured values. 3. According to IAQ model evaluation, reduction of outdoor supply air results in decreased dilution removal rate and on increased bypass filtration removal rate with the VAV/BPFS. As a results, we recommends the VAV/BPFS as an alternative to conventional VAV systems.

• Journal of Information Processing Systems
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• v.15 no.5
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• pp.1131-1140
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• 2019

Characteristics of fruit tree canopies are important target information for adjusting the pesticide application rate in variable rate spraying in orchards. Therefore, the target detection of the canopy characteristics is very important. In this study, a canopy volume measurement method for peach trees was presented and a variable rate spraying system based on canopy volume measurement was developed using the ultrasonic sensing, one of the most effective target detection method. Ten ultrasonic sensors and two flow control units were mounted on the orchard air-assisted sprayer. The ultrasonic sensors were used to detect the canopy diameters and the flow controls were used to modify the flow rate of the nozzles in real time. Two treatments were established: a constant application rate of $300Lha^{-1}$ was set as the control treatment for the comparison with the variable rate application at a $0.095Lm^{-3}$ canopy. The tracer deposition at different parts of peach trees and the tracer losses to the ground (between rows and within rows) were analyzed in detail under constant rate and variable rate application. The results showed that there were no significant differences between two treatments in the liquid distribution and the capability to reach the inner parts of the crop canopies.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2016.05a
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• pp.93-95
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• 2016

In recent years, attention of ship owners for the energy saving of the vessel is being collected due to the volume decline. Ship accommodation consists of watertight type windows and is closed, Ship HVAC is used to promote a comfortable environment for the crew. In addition requirements for comfort of the crew is getting stronger with the improvement of living standards, there is a need for HVAC improvements. In this paper, propose method to save energy and improve HVAC controls by using the HVAC structure of the variable air volume.

• Solar Energy
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• v.15 no.3
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• pp.53-58
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• 1995

The objectives of this study are to introduce the energy simulation program BLDSYM, to verify the approach, and to demonstrate the energy saving opportunities. A case study model for Hoover Middle School, OK, USA has been introduced as a base case simulation. Air-side variable air volume(VAV) and water-side variable flow hydronic(VFH) system have been recommended, modeled and simulated to quantify the energy savings compared with the base system, which is typically constant air and water flow system. More than 30% of energy savings could be obtained with the optimum variable flow system.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1995.05a
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• pp.88-93
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• 1995

The purpose of this study is to introduce the energy simulation program BLDSYM, verify the approach. and demonstrate the energy saving opportunities. A case study model for Hoover Middle School, OK USA has been introduced as a base case simulation. Air-side variable air volume (VAV) and water-side variable flow hydronic (VFH) system have been recommended, modeled and simulated to quantify the energy savings compared with the base system, which is typically constant air and water flow system. More than 30 % of energy savings could be obtained with the optimum variable flow system.

• International Journal of High-Rise Buildings
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• v.1 no.2
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• pp.125-129
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• 2012

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.29 no.2
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• pp.39-45
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• 2000

1970년대부터 사용된 변풍량 공조 시스템 (Variable Air Volume System)은 실내 부하 변동에 따라 급기 온도를 일정하게 유지시키고 실별, 존별 송풍량을 변화시켜 실온을 제어하는 방식으로, 에너지 절약, 개별 제어 등의 장점 때문에 적용이 확대되었고 특히 단일덕트 변풍량 공조 시스템은 이러한 이유 때문에 많은 건물에 적용되고 있다. 그러나 현 제어시스댐의 풍량 측정의 문제점과 공조기내에서 풍량변화 및 급/배기 댐퍼의 개도 변경으로 인한 환기 댐퍼의 비선형 특성을 고려하지 않고 제어하기 때문에 외기량 확보를 정확히 유지 못하는 실정이다. 따라서 단일덕트 변풍량 시스템의 환기댐퍼 및 급기, 환기 팬의 제어 방식의 종류와 특성 및 문제점에 대하여 설명하고자 한다.

• Proceedings of the KIEE Conference
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• 1998.07b
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• pp.420-422
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• 1998

All Fault Detection and Diagnosis(FDD) methods utilize classification techniques. The objective of this study was to demonstrate the application of classification techniques to the problem of diagnosing faults in data generated by a variable-air-volume(VAV) air-handling unit(AHU) simulation model and to describe the characteristics of the techniques considered. Artificial neural network classifier and fuzzy clustering classifier were considered for fault diagnostics.