• 한국항해항만학회지
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• 제33권3호
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• pp.175-180
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• 2009

본 연구에서는 슈퍼요트의 쾌적한 실내환경조성을 목적으로 기초자료를 수집하였으며, 요트가 주로 운항되는 여름철 실내공간에 형성되는 실내환경성능에 대해 실측을 통해 분석함으로써 다음과 같은 결과를 얻었다. 1) 외부와 연결된 살롱의 문을 닫을 경우 선박배기가스의 실내유입은 거의 없으나 문을 여는 경우에는 급속히 실내공기가 오염되므로 쾌적한 실내공기환경을 유지하기 위해 실내환기방법 및 환기량에 대한 대책이 필요하다. 2) 운항 시에는 모든 실이 선원보호 소음규제치인 60dB을 넘고 있어 실내의 소음대책이 시급하다. 3) State cabin과 Guest cabin은 에어컨가동에 의해 과냉됨으로써 실내 환경이 쾌적범위를 벗어나고 있어 이에 대한 대책이 필요하다.

• 한국환경보건학회지
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• 제47권4호
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• pp.330-338
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• 2021

Background: This study was conducted to provide background information for the proper management of radon contamination in apartments using mechanical ventilation facilities in residential environments. Objectives: To this end, this study compared and evaluated changes in radon concentrations based on different operating intensities of mechanical ventilation with or without natural ventilation. Methods: For the continuous measurement of radon concentrations, an RAD7 instrument was installed in four apartments equipped with a ventilation system. The measurements were done for comparison of ventilation types and different ventilation intensities ("high", "middle", "low"). Results: The results confirmed that both mechanical and natural ventilation sufficiently reduced the radon concentration in the apartments. In particular, mechanical ventilation at "high" intensity was the most effective. Natural ventilation combined with mechanical ventilation and then natural ventilation alone were the second and the third most effective, respectively. Conclusions: When using ventilation to reduce indoor radon concentrations, it is most effective to operate mechanical ventilation ("high") or natural ventilation and mechanical ventilation at the same time. In cases where mechanical ventilation is available alone, it is recommended to operate it at a minimum of "middle" intensity.

• Bulletin of the Korean Chemical Society
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• 제34권8호
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• pp.2394-2398
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• 2013

Nicotine is the main component of environmental tobacco smoke, and its presence in indoor air is widely used as a secondhand-smoke indicator. Environmental tobacco smoke is a major source of indoor air pollution, but sufficient investigation of the uncertainty of its measurement, which mirrors the reliability of nicotine measurement, has not been performed. We calculated the uncertainty of measurement of indoor air nicotine concentration at low, medium, and high concentrations of 11.3798, 10.1977, $98.3768{\mu}g/m^3$, respectively, and we employed the Guide to the Expression of Uncertainty in Measurements (GUM), proposed by the International Organization for Standardization (ISO). The factors considered in determining the uncertainty were uncertainty of the calibration curve (calibration curve and repeated measurements), desorption efficiency, extraction volume, and sampling airflow (accuracy and acceptable limits of flowmeter). The measurement uncertainty was highest at low concentrations; the expanded measurement uncertainty is $0.9435{\mu}g/m^3$ and is represented as a relative uncertainty of 63.38%. At medium and high (concentrations, the relative uncertainty was 13.1% and 9.1%, respectively. The uncertainty of the calibration curve was largest for low indoor nicotine concentrations. To increase reliability of measurement in assessing the effect of secondhand smoke, measures such as increasing the sample injection rate ($1{\mu}L$ or more), increasing sampling volume to increase collected nicotine, and using gas chromatography-mass spectrometry (GC/MS) or GC/MS/MS, which has a lower quantitation threshold, rather than gas chromatography with nitrogen phosphorous detector, should be considered.

• 센서학회지
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• 제23권1호
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• pp.1-6
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• 2014

In many medical image devices, dc noise often prevents normal diagnosis. In wireless capsule endoscopy systems, multipath fading through indoor wireless links induces inter-symbol interference (ISI) and indoor electric devices generate impulsive noise in the received signal. Moreover, dc noise, ISI, and impulsive noise are also found in optical fiber communication that can be used in remote medical diagnosis. In this paper, a blind signal processing method based on the biased probability density functions of constant modulus error that is robust to those problems that can cause error propagation in decision feedback (DF) methods is presented. Based on this property of robustness to error propagation, a DF version of the method is proposed. In the simulation for the impulse response of optical fiber channels having slowly varying dc noise and impulsive noise, the proposed DF method yields a performance enhancement of approximately 10 dB in mean squared error over its linear counterpart.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.1421-1424
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• 2006

Recently Requirement of indoor environment is increased in APT. Among indoor noises of APT, noise of plumbing system in bathroom is very serious problem except of floor impact noise. Plumbing system with wan hanging unit make a good grade and recognition in rating noise of bathroom in grade of house rating. But it is hard to find a data which are measured in APT built. In this study, the effect of noise reduction is checked by measuring the noise of plumbing system with wall hanging unit that is built. As result the upper household's Peak sound level is measured 80dB(A), the under household's peak sound level is measured 40dB(A).

• International Journal of Air-Conditioning and Refrigeration
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• 제17권2호
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• pp.37-44
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• 2009

It is well known that a refrigerant-induced noise is caused by two-phase flow in the indoor unit of a heat pump air-conditioner. Especially when the flow pattern in a pipe is intermittent flow, the irregular noise occurs frequently. But it is very difficult to avoid this kind of the noise for the application of air-conditioner. Therefore, in this research, the flow patterns at two-phase flow state in a pipe of the indoor unit for the air-conditioner are researched using cycle simulator at typical cycle conditions. In order to find the relationship between refrigerant-induced noise and flow pattern, the noise patterns are investigated with respect to the estimated flow pattern from the various flow pattern maps. Base on the estimations of the flow patterns by those maps, the refrigerant-induced noise is evaluated as decreasing tube diameter, which can transit the flow pattern from slug to annular flow.

• 한국음향학회지
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• 제8권1호
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• pp.59-66
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• 1989

공조설비소음의 특성을 파악하기 위하여 서울의 도심에 위치한 고층 사무소 건물을 대상으로 송풍기의 파워레벨과 취출구를 통한 실내소음레벨을 측정하였다. 또한 공조설비소음이 문제시되는 건물에 흡음챔버와 사이드브랜치를 설치하여 소음기의 감음성능을 평가하였다. 연구의 결과, 실내소음레벨은 송풍기 발생소음의 영향으로 500Hz 이하의 저주파수 대역에서 ISO의 허용 기준치인 NR40을 초과하였으며 흠음챔버는 넓은 대역의 주파수, 사이드브랜치는 특정공명주파수에서 감음효과가 크게 나타났다.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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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.

• 한국산업보건학회지
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• 제28권4호
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• pp.382-392
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• 2018

Objective: Allergic diseases such as asthma due to fungal exposure in houses have increased, and proper management is urgent. Mold can grow in the air, floor, walls, and other areas according to environmental conditions, and there are many limitations to the conventional methodology for examining fungal exposure. For this reason, the degree of fungal contamination is being evaluated by ERMI (Environmental Relative Moldiness Index), a quantitative analysis method proposed by the EPA. In this study, we compared ERMI values between water-damaged dwellings and non-damaged ones to evaluate the effectiveness of Korean ERMI values. We also explored the association of ERMI values with the level of airborne mold and characteristics of dwellings. Methods: Floor dust was collected after installing a Dustream collector on the suction port of a vacuum cleaner. The collected samples were filtered to remove only 5 mg of dust, and DNA was extracted using the FastDNA SPIN KIT protocol. Results: The ERMI values were found to be 19.6 (-6.9-58.8) for flooded houses, 7.5 (-29.2-48.3) for leaks/condensation, and 0.8 (-29.2-37.9) for non-damaged dwellings. The airborne concentration of mold for flooded, leakage or condensed, and non-damaged houses were $684CFU/m^3$, $566CFU/m^3$, and $378CFU/m^3$, respectively. The correlation between ERMI values and the levels of airborne mold was low (R = 0.038), but a weakly significant association of the ERMI values with the concentration of particulate matter ($PM_{10}$) was observed as well(R=0.231,P<0.05). Conclusions: Our findings show that the reference value using ERMI can be used to distinguish water-damaged and non-damaged dwellings. It is believed that ERMI values could be a promising tool for assessing long-term fungal exposure in dwellings.

• 한국위성정보통신학회논문지
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• 제11권4호
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• pp.58-62
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• 2016

본 논문에서는 실내 임펄시브 노이즈 채널 환경에서 비콘 기반의 측위 시스템의 측위 정밀도를 향상시킬 수 있는 전처리 기법을 제안하였다. 임펄시브 노이즈는 복잡한 실내 구조 환경이나 간섭 환경에서 발생하며 이는 무선 통신에서 신호 복조 오류 확률을 증가시켜 정확한 데이터 복조를 어렵게 한다. 제안한 전처리 기법은 사용자의 위치 좌표를 산출하기 위한 비콘 기반의 삼각측량법을 수행하기 이전에 적용 및 수행되며, 제안 기법을 데이터 복소의 오류 확률을 감소시켜 정확한 데이터를 삼각측량법의 입력값으로 제공한다. 신뢰성 있는 데이터 입력을 통해 위치 좌표 결과값의 신뢰도를 향상시키는 매커니즘이다. 따라서 임펄시브 노이즈 완화를 위해 신호의 시간-주파수 분해능이 우수한 웨이블릿 잡음 제어 방법을 기반으로 임펄시브 노이즈에 특성에 따라 노이즈를 제거하는 적응적 임계 함수를 제안하였다. 컴퓨터 시뮬레이션을 통해 제안한 적응적 임계 함수가 기존의 기법과 대비로 비교적 Bit Error Rate 성능 및 Signal-to-Noise Ratio 성능을 향상시키는 결과를 확인하였다.