• 환경위생공학
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• 제16권1호
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• pp.1-8
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• 2001

Since most people spend over 80% of their time indoor, indoor air quality tends to be the dominant contributor to personal exposure. In this study, indoor and outdoor $NO_2$concentrations were measured and compared with simultaneously personal exposures of 27 house-wives and female workers of kindergarten. Time activity pattern and house characteristics were used to determine the effects of these factors on personal exposure. Since house-wives student spent most their times in indoor with mean of 89.8%, their $NO_2$ exposure was associated with indoor $NO_2$ level(r= 0.92) rather than outdoor $NO_2$ level(r= 0.87). female workers were also associated with indoor $NO_2$ level(r= 0.70) though sample number were small. Using time-weighted average model, $NO_2$ exposures of house-wives were estimated by $NO_2$ measurements in indoor home and outdoor home levels. Estimated $NO_2$ personal exposures were significantly correlated with measured $NO_2$ personal exposures (r= 0.90). These results might mean that air pollutants exposure of old and feeble persons, and infants could be estimated by measuring concentrations of indoor home.

• 한국환경과학회지
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• 제11권12호
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• pp.1205-1215
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• 2002

To evaluate the change for water quality after the water gate operation in Shiwha lake, in situ survey were conducted on september in 2000 and January, march, jane in 2001. Chemical characteristics and eutrophication level was estimated from the survey data. The water quality of the Shihwa lake was greatly affected by pollutant load from rainfall, and formation of stratification in summer and winter was increased to effect on nutrient release from sediment. Especially, high concentration of chlorophyll-a was occurred in autumn, due to increased nutrient, high water temperature and low salinity after rainfall runoff. The mean concentration of DIN, DIP were 0.346mg/L, 0.0217mg/L in surface water and 0.826mg/L, 0.0415mg/L in bottom water, respectively, which were over III grade of seawater standard. Also high percentage of ammonia nitrogen to DIN in bottom water for autumn and winter was affected by released nutrient from sediment. Correlation analysis of chlorophyll-a versus TSS was shown that organic matter was affected by autochthonous organic matter stem from the algae, these factor showed reverse correlation about salinity. Closely correlations among to the water quality constituent in continuity survey was appeared. The results of eutrophication index estimation showed the high potentiality of red tide occurrence in Shiwha lake, particularity in summer or fall. Overall water quality was greatly improve to compared with measuring data during 1997~1998 at the beginning water gate operation, which reported by KORDI. Therefore, to improve of water quality in Shiwha lake, we need to establish of management plan about nutrient release from sediment, rainfall runoff, maximum of seawater exchange.

• 한국멀티미디어학회논문지
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• 제8권3호
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• pp.313-321
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• 2005

연속 계조 영상을 이진 영상으로 변환하는 방법을 해프토닝이라 한다. 이와 같은 해프토닝 방법 중 오차확산법은 연속 계조 영상을 이진 영상으로 표현할 때 우수한 화질을 보이지만 에지 영역에서는 에지 정보가 흐려지는 특성이 있다. 이를 개선하기 위해 원영상의 국부적인 공간 정보를 이용하여 에지를 강조하는 방법을 제안한다 제안 방법은 인간의 시각이 한 점을 인식하지 않고 국부 평균을 인식함을 고려하여 한 화소와 인접 화소의 평균을 이용한 비율 값을 국부 평균에 가중치로 적용하고 에지 강조 정보량(EEI : Edge enhancement information)을 구한다. 이때 국부 평균에 적용되는 가중치는 원 화소와 3$\times$3 블록의 평균과의 차이 값과 공간 활성도(LAM : Local activity measure)의 비율을 이용하여 계산된다 공간 활성도는 국부 공간의 변화량을 표현하는 척도로 3$\times$3 블록의 평균과 블록의 화소의 차이 값의 제곱의 합으로 구한다 EEI를 양자화기 입력에 더하여 해프톤 영상의 에지를 강조한다. 제안 방법의 성능은 에지 상관도 평가 함수로 평가했으며 제안 방법을 영상에 적용한 결과 이진 영상의 에지가 강조되어 시각적으로 선명한 결과를 보이며 미세한 에지도 잘 보존되었다. 또한 눈에 거슬리는 규칙적 패턴도 줄어 개선된 화질을 보여주었다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 추계학술대회 논문집
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• pp.456-459
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• 2009

we studied a data acquisition and control system of a wind turbine for measuring and controlling a voltage fluctuations of a wind turbine system. The wind turbine system is installed out control area. So, it is so important for supervising to wind turbine of a maintenance, wind speed, optical resources wind turbine output, wind speed, wind direction, over voltage of a generator. This system can be supplied a data of over voltage, under voltage, voltage fluctuations of a wind turbine for controlling an EMS : Energy Management System or a SCADA : Supervision Control and Data Acquisition at a constitute of a wind farm. The of voltage fluctuation system of a wind turbine is improving an electric power supply power quality of a distribution line and unspecified individuals of used wind turbine.

• 한국해양공학회지
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• 제25권4호
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• pp.23-27
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• 2011

This experimental study was performed to find rpms of the impeller and the surface flow accelerator to make a uniform velocity vertical distribution in the circular water channel. PIV technique was employed to measure the water velocity profiles into the water depth from the free surface. The number of instantaneous velocity profiles was decomposed into mean and turbulence velocity components, and the distribution of velocity fluctuation and turbulence intensity were computed for each experimental condition. From these results, the velocity uniformity was quantitatively determined to present the flow quality in the measuring section of the circular water channel. It has been shown that the proper operation of the surface flow accelerator would make the uniform velocity profiles and reduce the velocity fluctuation near the free surface.

• 대한산업공학회지
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• 제32권1호
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• pp.51-60
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• 2006

When the nature of measuring a performance variable is destructive or very expensive, it is attractive to use a surrogate variable which is highly correlated with the performance variable and less expensive to measure. In this paper, we propose rectifying screening procedures using the performance and surrogate variables. Two screening procedures are considered; a statistically-based screening procedure to reduce the current proportion of nonconforming items to a specified lower value after screening, and an economically-based screening procedure where the screening limit is determined so that the expected cost is minimized. It is assumed that the surrogate variable given the performance variable is normally distributed with known mean and standard deviation. For two screening procedures, methods of finding the optimal solutions are presented and numerical examples are also given.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 춘계학술대회 논문집
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• pp.595-601
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• 2004

The pantograph for Korean High Speed Train was developed and had been evaluating by through 'G7-R&D project' for home grown high speed train technology. In this paper, from the point of view in mechanical aspect, comparison study on the current collection characteristics between the KHST pantograph and contact wire in catenary system on the High-Speed Line and Ho-Nam/Kyoung-Bu conventional lines is conducted. A measuring system for the performance and mechanical characteristics of the KHST pantograph is used for this study, which was developed and installed on the Proto-type Korean High Speed Train, and physical characteristics were measured while the KHST runs on the High-Speed Line and conventional lines. Through this study, remarkable variations of characteristics which can affect to a current collection quality of high-speed train are found and analyzed from measured mean contact forces in both tracks.

• 한국연소학회지
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• 제1권1호
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• pp.75-82
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• 1996

Laser induced incandescence, LII, recently developed technique for measuring soot concentration in flames, can overcome most of limitations of conventional laser extinction measurement. In this study, experiments were performed to investigate the effect of laser intensity, detection wavelength, and also laser beam quality on both LII signal at a particular position and peak-to-centerline LII signal ratio. The results of LII signal with increasing laser intensity shows its near-independence of laser intensity once threshold level of laser intensity has been reached. However, this near-independence depends on laser beam quality and the incident optical setup. The peak-to-centerline LII signal ratio slowly but continuously increases with laser power. This fact is due to the dependence of LII signal on particle mean diameter. LII signal is attenuated during it passes through the flame containing soot particles. The attenuation rate is inversely proportional to detection wavelength. In this study, LII signal at 680 nm band is 10% greater than the signal at 400 nm band.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.1213-1219
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• 2008

This experimental study was to analyze thermal comfort and indoor air quality(IAQ) with ventilation and humidification in the classroom when system air conditioner was operated. The thermal comfort was estimated by the PMV index and the concentration of $CO_2$ and total suspended particle(TSP) were measured and compared with ventilation and humidification. As a result, the class room temperature distribution was $2{\sim}5^{\circ}C$ low during operating ventilation system and humidification. At 60% RH, PMV values of measuring points were ranged from +0.5 to -0.5 indicating optimal the range of thermal comfort. The average concentration of $CO_2$ gas and TSP were reduced 645 ppm, 0.17 mg/$m^3$ respectively, during operating the ventilation system. From the results, to maintain comfortable environment in the heated classroom, the ventilation and humidification were needed in winter season.

• 대한방사선기술학회지:방사선기술과학
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• 제30권3호
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• pp.251-257
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• 2007

디지털 MTF의 정확도를 결정하는 요소로는 정확한 엣지 각도의 결정, 합성 ESF 또는 합성 LSF을 작성을 위한 재 샘플링, 스무징, 커브핏팅 등을 들 수가 있다. 본 실험에서는 Edge를 이용한 MTF커브 핏팅방법을 구현하였고, 슬릿법에 의한 MTF산출결과와 비교하였다. 실험결과 공간주파수 2.0 LP/mm 근방까지의 저주파수영역에서는 엣지법이 높은 수치를 나타내며 2.0 LP/mm 이상의 주파수 영역에서는 MTF값이 역전이 되어 슬릿법이 더욱 높은 값을 나타내었다. 이는 Cunningham의 보고와 완전히 일치한다.