• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.1424-1428
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• 2009

The performance of a heat pump using river water as a heat source was compared with that of a conventional air-conditioner for cooling and a boiler system for heating. The heat pump system using river water considered the 1-stage cycle for cooling and the 2-stage cycle for heating. The COPs of the river water source heat pump were $0.5{\sim}1.1$ higher than those of the conventional system in the cooling season. The LCC of the river water source heat pump system was lower 13.5% and 32.4% than that of the conventional system I and II. In addition, when the initial cost ratios of the river water source heat pump system to the conventional system I and II were less than 1.2 and 1.4, respectively, an acceptable payback was found to be less than 5 years.

• 대한기계학회논문집B
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• 제24권5호
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• pp.687-693
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• 2000

Recently, a scroll compressor is widely used, because a scroll compressor features low noise, due to less pulsation of gas pressure, than that of the rotary compressor. The major source of noise in air-conditioner is a compressor. Therefore, noise reduction in a compressor is quite significant as an element technology in air-conditioner field. For a reduction of noise, the source of noise must be identified. This paper presents detailed analyzes for the major noise source (fluid-borne noise and structure-borne noise) causes in a scroll compressor, which will make possible a low noise and vibration design of a scroll compressor.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 추계학술대회 논문집
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• pp.789-792
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• 2005

The dominant noise sources of Diesel Multiple Units are powerpack, which is composed of engine, transmission and cooling system, noise and wheel-rail rolling noise. The interior noise of a running vehicle is determined by structure-borne noise and air-borne noise from these noise sources. The contributions of interior noise from each noise source are calculated by air-borne transfer functions and structure-borne transfer functions of noise sources. In this paper, source separation technique is proposed to determine these transfer functions from the results of stationary and running tests of existing vehicle. With this technique, it is possible to get hold of contributions of interior noise from .noise sources of running vehicle. This source separation technique makes it possible to take efficient measures for reduction of interior noise at the early car-development stage.

• 대한기계학회논문집B
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• 제27권10호
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• pp.1489-1497
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• 2003

Aerosol charge neutralizers with various radioactive sources have been used to apply an equilibrium charge distribution to aerosols of unknown charge distribution. However, the performance of aerosol charge neutralizers is not well known, especially for highly charged particles. Measurements of highly charged particles are needed in air cleaning devices, e.g. electrostatic precipitator, bag filter with a pre-charger, and electrical cyclone. In this study, the particle charging characteristics of two different aerosol charge neutralizers were experimentally investigated for singly charged monodisperse particles and highly charged polydisperse particles. One has radioactive source of $^{85}$ Kr (beta source, 2 mCi) and the other has $^{210}$ Po (alpha source, 0,5 mCi). The air flow rate passing through each aerosol charge neutralizer was changed from 0.2 to 2.5 L/min. The results show that the charge distribution of singly charged monodisperse particles passing through the $^{85}$ Kr aerosol charge neutralizer is well agreed with the Boltzmann equilibrium charge distribution at an air flow rate of 0.3 L/min, However, it deviates from the equilibrium charge distribution when the air flow rates are 0.6, 1,0, and 1,5 L/min, On the other hands, the effect of air flow rate is insignificant for the $^{210}$ Po aerosol charge neutralizer. The non-equilibrium character in charge distribution of highly charged polydisperse particles passing through the $^{85}$ Kr aerosol charge neutralizer greatly depends on the air flow rate, however it is insensitive to the air flow rate for the $^{210}$ Po aerosol charge neutralizer.

• 한국멀티미디어학회논문지
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• 제16권12호
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• pp.1465-1474
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• 2013

In this paper, air pollutant tracing models using perceptron neural network(PNN) and non-negative least square(NNLS) are proposed. When the measured values of the air pollution and the contribution concentration of each source by chemical transport modeling are given, they estimate and trace the amount of the air pollutants emission from each source. Two kinds of emissions data are used in the experiments : CH4 and N2O of Geumgo-dong landfill greenhouse gas, and PM10 of 17 areas in Northeast Asia and eight regions of the Korean Peninsula. Emission values were calculated using pseudo inverse method, PNN and NNLS. Pseudo inverse method could be used for the model, but it may have negative emission values. In order to deal with the problem, we used the PNN and NNLS methods. As a result, the estimation using the NNLS is closer to the measured values than that using PNN. The proposed tracing models have better utilization and generalization than those of conventional pseudo inverse model. It could be used more efficiently for air quality management and air pollution reduction.

• 대한방사선기술학회지:방사선기술과학
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• 제30권2호
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• pp.147-151
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• 2007

AAPM TG43 프로토콜에서 선원 강도의 측정은 공기커마강도로 권고하고 있다. 본 연구는 제조사에서 제공되는 공기커마강도의 정확성이 ${\pm}5%$ 범위 이내에 있는지 측정으로 검증하는데 목적이 있다. Standard imaging사의 MAX-4001 Electrometer와 HDR 1000 Plus, 그리고 6 french bronchial Applicator를 재료로 사용하여, 이온함의 중심축의 바닥으로부터 10 mm 지점에서 90 mm 지점까지 이온화 전류를 측정하였다. 측정된 이온화 전류 곡선에서 최대 이온화 전류를 나타내는 거리를 교정의 기준점으로 정하고, 이 이온화 전류 측정치로부터 공기커마강도를 구하였다. 이온화 전류 곡선의 정점인 최대 이온화 전류에 대응하는 거리는 50 mm이었다. 이 거리는 UW-ADCL의 교정 검증서의 선원의 기준점과 완전히 일치하였다. 측정으로 계산된 공기커마강도는 제조사에서 제공된 교정치보다 약 0.5% 더 높게 측정되었다. 제조사에서 제공되는 교정 검증서의 공기커마강도는 신뢰할 수 있는 정확성을 가졌다는 결과를 얻었다. 측정에서 우물형 이온함 안의 dead space의 길이와 선원의 dwell position으로 이동 오차 그리고 산란선의 영향 등을 고려하면, 정확한 측정과 교정의 결과를 얻을 수 있다고 생각된다.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 2000년도 THE THIRD INTERNATIONAL CONFERENCE ON AGRICULTURAL MACHINERY ENGINEERING. V.III
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• pp.632-638
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• 2000

This paper represents the characteristics of evapotranspiration rate (EVTR) and graft-taking of watermelon grafted seedlings in a graft-taking enhancement system using fluorescent lamps as artificial lighting source. Four air temperature levels of 23, 25, 27 and 29C, three humidity levels of 85, 90 and 95%R.H. and two photosynthetic photon flux (PPF) levels of 30 and 50 ${\mu}$mol m$\^$-2/ S$\^$-1/ were provided to investigate the effects of air temperature, relative humidity and light intensity on EVTR and graft-taking of grafted seedlings. EVTR of grafted seedlings increased with increasing air temperature and the passage of time after grafting. Also EVTR increased with decreasing relative humidity. As relative humidity decreased and air temperature increased, vapor pressure deficit increased and thus EVTR increased. It is required to maintain a low level vapor pressure deficit for suppressing EVTR of grafted seedlings during first 1-2 days after grafting. Therefore, less EVTR at initial stage after grafting would be adequate for smooth joining of the scion and rootstock.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2002년도 학술대회지
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• pp.487-490
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• 2002

The real chip and similarity model were used to investigate the thermal behavior and velocity distribution of air from the heat source with the location and the amount of heat experimentally and numerically, and compared. The heat generated in the block is not cooled by convection and show the high temperature by the stagnation of heat flow. After maintaining the high temperature of block by the natural convection, the sudden drop of temperature with the air flow was shown in the channel but the decreasing rate was small with the time. The inward block was effected by infinitesimal air flow generated between block and channel and outward block was effected by the entry condition.

• 설비공학논문집
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• 제11권6호
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• pp.871-879
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• 1999

Present study explains some experimental results on the aerodynamic noise of the cross-flow fan usually installed in the indoor unit of the room air-conditioners and provides a simple reduction method of radiating sound to decrease the total noise level. The spectrums of the noise of the cross-flow fan were analyzed by the spectral decomposition method to characterize the generated sound. The unsteady fluctuating flow field was also measured using the I-type hot-wire probe. Comparing the spectral characteristics of the sound and the flow velocity, a useful noise reduction method was proposed which bounds the region with a fence where the flow fluctuations were noticeably changed in the same fashion as the source spectral distribution functions vary. To validate the proposed method for reducing noise generated by the cross-flow fan, the sound pressure levels of the cross-flow fan system were compared of the experimental rig with and without the bounding fence for various flow rates.

• The Korean Journal of Ecology
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• 제15권3호
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• pp.247-255
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• 1992

In order to estimate effects of air pollution for herbs in the plnus thunbergii forests arrounding onsan industrial complex, this study was surveyed. number of species of herb also had a difference over 10 species by distance at the source of air pollution, and species diversity and evennes were also increasing at remote sites in industrial complex as woody plants. At the vicinity of industrial complex, $SDR_4$ of calamagrostis arundinatios arundinacea., miscanthus sinensis and cymbopogon tortilis var. goeringii were very high, and those of lianas as cocculus trilobus, lonicera japonica and paederia scandens, and phytolacca americana were low, but because of being higher than other sites, it was able to inferred that lianas had a tolerance to air pollution. The composition of biological spectra of herbs showed to type of $H-D_1-R_{2-3}-1$ at near site in the source of air pollution and $H-D_1-R_{1-3}-t$ at the other sites, and the propotion of lians forms were relatively high at the vicinity of industril complex.