• 한국환경보건학회지
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• 제33권5호
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• pp.359-364
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• 2007

The aim of this study were to assess the personal exposure to volatile organic compounds (VOCs) and to estimate the personal exposure using time-weighted average model. Three target VOCs (benzene, toluene, xylene) were analyzed in personal exposure samples and residential indoor, residential outdoor and workplace indoor microenvironments samples in the iron mill 30 workers during working 5 days. Personal exposure to VOCs significantly correlated with workplace concentration p<0.05), suggesting workplace had strong source and major contribution to personal exposure. Personal exposure could be estimated with time activity pattern and time weighted average (TWA) model of residential indoor and workplace concentrations measured. Time weighted mean microenvironments concentrations were close approximately of personal exposure concentrations. Total exposure for participants can be estimated by TWA with microenvironments measurements and time activity pattern.

• 한국대기환경학회지
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• 제17권3호
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• pp.251-258
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• 2001

Indoor and outdoor nitrogen dioxide(NO$_2$) concentrations of 122 houses were measured and compared with measurements of personal NO$_2$ exposure simultaneously . Time activity patterns were used to determine the impacts on NO$_2$ exposure assessment and time weighed average model to estimate the personal NO$_2$ exposure. Most people spent their times more than 80% of indoor and more than 50% in home, respectively. Personal NO$_2$ esposure was found to be significantly associated with both indoor NO$_2$ concentration(r=0.70) and outdoor NO$_2$ concentration (r=0.68). Using time weighted average model, personal NO$_2$ exposure was estimated with NO$_2$ measurements in indoor home, indoor workplace and outdoor home. The estimated NO$_2$ measurements were significantly correlated with measured personal exposures(r=0.69, N=122). For the difference between measured and estimated NO$_2$ exposures by multiple regression analysis showed that NO$_2$ concentrations in near workplace and other outdoors of no NO$_2$ measurements affected the personal NO$_2$ exposures(p=0.023).

• 전기학회논문지
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• 제63권7호
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• pp.962-967
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• 2014

In this paper, through a digital potentiometer and exponentially weighted moving average filter, pulse and PPG waveform measurable device was fabricated in radial artery. If this device is not proper about signal size in analog part, MCU can judge easily by adjusted amplification through digital potentiometer, using exponentially weighted moving average filter is able to filter out more clear value of ADC. I presumed pulse rate as value of measuring time between point of maximum contraction from sensing signal in radial artery of wrist. Therefore, this means can measure stable pulse rate and PPG waveform, finger as well as radial artery, whether signal size of each person is different finger as well as radial artery.

• 융합보안논문지
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• 제8권3호
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• pp.33-39
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• 2008

소트프웨어 고장 시간은 테스팅 시간과 관계없이 일정하거나. 단조증가 혹은 단조 감소 추세를 가지고 있다. 이러한 소프트웨어 신뢰모형들을 분석하기 위한 자료척도로 자료에 대한 추세 검정이 개발되어 있다. 추세 분석에는 산술평균 검정과 라플라스 추세 검정등이 있다. 추세분석들은 전체적인 자료의 개요의 정보만 제공한다. 본 논문에서는 고장시간을 측정하는 도중에 지수가중 이동 평균 관리도를 이용하여 관리 상태에 있는 자료만 가지고 정보분석을 해야 효율성이 있을 것으로 판단된다. 따라서 본 논문에서는 기존의 추세 검정과 지수가중이동평균 관리도를 사용하여 실제 소프트웨어 자료를 비교 분석하는 것을 목표로 하고 있다.

• 한국환경보건학회지
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• 제26권4호
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• pp.58-64
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• 2000

Indoor air quality tends to be the dominant contributor to personal exposure, because most people spend over 80% of their time indoors. In this study, indoor and outdoor NO$_2$ concentrations were measured and compared with simultaneously personal exposures of 21 university students in weekday and weekend. House characteristics and activity pattern were used to determine the impacts of these factors on personal exposure. Since university students spent most of their times in indoor, their NO$_2$ exposure was associated with indoor NO$_2$ level rather than outdoor NO$_2$ level both weekday and weekend in spite of different time activity. Using time-weighted average model, NO$_2$ exposures of university students were estimated by NO$_2$ measurements in indoor home, indoor school, and outdoor home levels. Estimated NO$_2$ personal exposures were significantly correlated with measured NO$_2$ personal exposures($r^2$=0.87). However, estimated personal NO$_2$ exposures by time-weighted average model were underestimated, comparing with the measured personal NO$_2$ exposure. Using multiple regression analysis, effect of personal NO$_2$ exposure for transportation was confirmed.

• 한국도로학회논문집
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• 제15권5호
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• pp.135-144
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• 2013

PURPOSES : The purpose of this paper is to develop a methodology to estimate level of service of arterial including Exclusive Median Bus Lanes. METHODS : On 6 Exclusive Median Bus Lanes routes in Seoul, bus travel time and number of bus-stop per km were investigated. Also whether or not passing lane exists at bus-stop was checked. Based on the data from sites, bus travel time was estimated according to length of segment, number of bus-stop per km and whether or not passing lane exists at bus-stop. RESULTS : A bus travel time table was developed according to length of segment, number of bus-stop per km and whether or not passing lane exists at bus-stop. After bus travel speed and passenger car travel speed is estimated based on each travel time table and length of segment, two speeds are combined with weighted average speed using traffic volume of each lane group. Then weighted average speed is a measure of effectiveness of arterial including Exclusive Median Bus Lanes. CONCLUSIONS : It can be concluded that the proposed methodology can estimate level of service of arterial including Exclusive Median Bus Lanes considering the operation characteristics of Exclusive Median Bus Lanes.

• Journal of Welding and Joining
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• 제8권1호
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• pp.31-42
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• 1990

Arc must be stable during welding first of all other factors for obtaining sound weldment, especially in the automation of welding process. Arc stability is somewhat sophisticated phenomenon which is not clearly defined yet. In consumable electrode welding, the voltage and current variation due to metal transfer enables to assess arc stability. Recently, statistical analyses of the voltage and current waveform factors are performed to assess the degress of arc stability which is assessed and controlled by operator's own experience by now. But, considering the increasing need and the trend of automation of welding process, it is necessary to monitor arc stability in real-time. In this sutdy, the modified stability index composed of two voltage and current wvaeform factors (arc time and short circuit time) reduced from four factors (arc time, short circuit time, average arc current and average short circuit current) in Mita's index by the welding electrical circuit modeling is proposed and verified by experiments to be well estimating arc stability in the static sense. Also, the recursive calculation form estimating present arc stability in the dynamic sense is developed for real-time estimation. The results of applying the recursive index during welding show good estimation of arc stability in real-time. Therefore, the results of this study offers the mean for real-time control arc stability.

• 산업경영시스템학회지
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• 제16권28호
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• pp.93-101
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• 1993

In this paper, two adaptive exponentially weighted moving avenge control chart schemes which available for real-time are proposed. The weighting coefficient is estimated using a recursive kalman filter algorithm. Simulated average run lengths indicate the proposed schemes are sensitive to process shifts And their performance is comparable to CUSUM control chart and customary EWMA control chart.

• 한국산업보건학회지
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• 제33권1호
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• pp.3-5
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• 2023

Objective: This study introduces exposure concentrations of time-weighted average standard (TWA) evaluation and short-time exposure standard (STEL) evaluation for trichloroethylene in the cleaning process. Methods: Trichloroethylene measurement was conducted according to the KOSHA Guide (A-24-2019) method. It was carried out twice. Results: As a result of the first measurement, TWA concentration exceeded 4 times the exposure standard and STEL concentration exceeded 16 times, but the inaccuracy and breakthrough of the collection time could not be considered, so the second measurement was conducted. The second measurement result was lower than the first measurement result, but exceeded the exposure standards (TWA, STEL). Conclusions: We were able to confirm that the exposure level of workers in the cleaning process using trichloroethylene exceeded the exposure standard. And it is also considered necessary to grasp the approximate concentration using a detector tube in the preliminary survey.

• Journal of applied mathematics & informatics
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• 제42권3호
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• pp.709-723
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• 2024

We study the distributions of waiting times in variations of the geometric distribution of order k. Variation imposes length on the runs of successes and failures. We study two types of waiting time random variables. First, we consider the waiting time for a run of k consecutive successes the first time no sequence of consecutive k failures occurs prior, denoted by T^(k). Next, we consider the waiting time for a run of k consecutive failures the first time no sequence of k consecutive successes occurred prior, denoted by J^(k). In addition, we study the distribution of the weighted average. The exact formulae of the probability mass function, mean, and variance of distributions are also obtained.