• 한국산업보건학회지
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• 제23권4호
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• pp.348-355
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• 2013

Objectives: In working environment measurement, sampling is an important stage for obtaining reliable result as analysis. A personal air sampling pump is one of the most fundamental and important element in the work environment measurement, but it remains at the level of calibrating the flow rate of the pump before and after sampling. There is no checking whether the flow rate set at the initial stage would be hold during sampling. The purpose of this study was to develop a method to evaluate the flow rate performance of particulate sampling pump with three-pieces cassette holder containing filters commonly used to sample particulate. Materials and methods: We tested back pressure of particulate sampling pumps commonly used in Korea with three-pieces cassette holder containing various filters, and tried to find out the combination conditions of filters in accordance with back pressure required by ISO standard 13137. Results: We found out the matrix of sampling media such as three-pieces cassette holder containing filters applicable to the pressure drop required by the ISO standard for evaluating the flow rate stability under increasing pressure drop and long term(8 hour) performance. Conclusions: This evaluation method using sampling media matrix for checking flow rate stability proposed by this study could be very useful tool to find out good performance pumps before sampling.

• 한국산림과학회지
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• 제95권3호
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• pp.370-377
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• 2006

본 연구는 지속가능한 산림경영에 적합한 표본조사 방법을 제시하기 위해 계통적 추출법, 계통적 집락추출법, 그리고 층화집락추출법을 이용하여 경기도 양평군의 산림을 대상으로 자료를 수집한 후 통계검증을 실시하였다. 표본조사 방법은 계통적 집락추출법이 가장 효율적인 것으로 분석되었는데, 계통적 집락추출법을 적용할 경우 집락의 형태와 집락 내의 표본점 간의 거리를 결정하기 위해 5가지 집락의 형태와 표본점간의 거리 4가지에 대하여 통계검증을 실시하였다. 그 결과 집락의 형태는 삼각형 그리고 집락 내의 표본점 간의 거리는 50m가 가장 적합할 것으로 평가되었다.

• 한국토양환경학회지
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• 제3권1호
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• pp.3-9
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• 1998

본 연구는 휘발성 유기 화합물로 오염된 가솔린 지역에서 soil-gas의 분석결과로부터 오염도를 유추하는 기법에 대하여 서술 하였다. Soil-gas의 채취방법으로는 펌프를 이용한 1)grab sampling법과 흡착제 trap을 사용한 2)passive sampling법이 있다. Grab sampling법은 특정시간에 특정장소에서의 오염도를 보여주며, 반면에 passive sampling법은 특정위치에서 시간에 따른 오염도의 변화를 보여 준다. Soil-gas의 분석은 1)PID나 FID와 같은 작은 검지기에 의해서 총괄 탄화수소량을 측정할수도 있고 2)기체농도에 따라서 색깔이 변하는 지시약이 채워진 기체검지기 튜브를 사용할수도 있으며 3)여러가지 화합물을 한 번에 분석할수 있는 이동형 GC를 사용할수도 있다. Soil-gas를 이용한 측정법은 매우 값싸며 세밀한 정밀조사를 하기 위한 전단계에서 사용할 수 있는 유용한 방법으로 추천할만하다 하겠다.

• 한국산업보건학회지
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• 제16권4호
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• pp.346-355
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• 2006

The purpose of this study was conducted to ascertain the difference between impinger and passive sampling methods in the process of sampling and analyzing on airborne formaldehyde. Formaldehyde generating workplaces included in this study comprised four types of manufacturing industry such as two workplaces of products of wood, cork, straw and plaiting materials manufacturing industries, one casting metal manufacturing industry, and one parts and accessories for motor vehicles and it′s engines manufacturing industry. Workplaces contained in this study were located in some manufacturing area of Busan industrial complex and this study was carried out during a period from January 2003 to December 2004. Analytical accuracy, precision and detection limit of two methods was compared. Exposure level of its airborne concentration was evaluated in formaldehyde generating workplaces those were classified by types of industry, working process, and time. The results were as follows ; 1. A rate of recovery was 107.1% in impinger method and 101.8% in passive method, and precision was 7.79% in impinger method and 4.40% in passive method. There was no statistical significance in analytical accuracy and precision between two methods. A limitation of detection was 0.011 ppm in passive method which was lower than that of impinger method (0.020 ppm) by 1.8 times. 2. Airborne formaldehyde concentration of impinger method was different from passive method. It′s concentration by passive method was higher by 5.1 times than that by impinger method in the parts and accessories for motor vehicles and it′s engines manufacturing industry (P<0.05). Only in molding process among several types of processes, formaldehyde concentration in passive method was higher by 5.1 times than that in impinger method (P<0.05). Furthermore, formaldehyde concentration in passive method was higher by 1.7 times than that in impinger method (P<0.05) in the first half of year 2003. 3. The geometric mean of formaldehyde concentration in impinger method was lower than that in passive method, but there was no statistical significance of formaldehyde concentration by the difference of sampling method. In conclusion, it is difficult to conclude which is better between the two sampling methods because of no statistical significance for the difference of concentration. Because of lacks of certified passive sampling and analytical method, at present situation, studies on verification of accuracy and precision, obstructive reaction against validity on its exposure assessment, and research to develop domestically manufactured passive sampler in terms of cost-effectiveness should be continuously carried out.

• 한국산림과학회지
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• 제46권1호
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• pp.29-43
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• 1980

본조사지역(本調査地域)에 적용(適用)된 표본조사법(標本調査法)은 임분구성상태(林分構成狀態)를 고려(考慮)하여 단순무작위추출법(單純無作爲抽出法), 계순적추출법(系純的抽出法) 및 부차추출법(副次抽出法) 등(等)이었다. 표본점수(標本點數)의 산출(算出)을 위(爲)하여 변이계수(變異係數)는 40%를 적용(適用)하였으며 그 결과(結果) 단순무작위추출법(單純無作爲抽出法) 및 계순적추출법(系純的抽出法)에서는 공(共)히 57개소(個所)의 표본점수(標本點數)를 산출(算出)하였다. 그러나 부차추출법(副次抽出法)에서는 전림(全林)에서 1차(次)로 5개소(個所)의 Block unit, 2차(次)로 4개소(個所)의 Major unit, 3차(次) 2개소(個所)의 Minor unit를 추출(抽出)하여 소요(所要) 표본점수(標本點數)를 40개소(個所)로 하였다. 전림추정재적(全林推定材積) 및 전림실측재적(全林實測材積)을 구(求)하여 비교검토(比較檢討)한 결과(結果)는 다음과 같다. 1. 표본조사방법별(標本調査方法別)로 추정오차율(推定誤差率)을 비교(比較)한 결과(結果) 단순무작위추출법(單純無作爲抽出法)이 9.24%, 계통적(系統的) 추출법(抽出法)이 8.36%, 부차추출법(副次抽出法)이 7.54%의 순(順)으로서 부차추출법(副次抽出法)이 가장 높은 정도(精度)를 나타냈다. 2. 전림실측재적(全林實測材積)과 각(各) 표본조사법(標本調査法)에 의(依)한 전림추정재적(全林推定材積)과의 오차율(誤差率)을 비교(比較)한 결과(結果) 단순무작위추출법(單純無作爲抽出法)이 7.92%, 계통적추출법(系統的抽出法)이 4.18%, 부차추출법(副次抽出法)이 0.39%의 순(順)으로서 이때에도 역시(亦是) 부차추출법(副次抽出法)이 가장 높은 정도(精度)를 나타냈다. 3. 이상(以上)과 같은 여러가지 결과(結果)를 종합적(綜合的)으로 통계분석(統計分析)하여 비교검토(比較檢討) 해볼 때 본(本) 조사지역(調査地域)에서는 부차추출법(副次抽出法)이 가장 정도(精度)가 높은 결과(結果)를 얻었으며 표본점(標本點)의 추출(抽出) 개소수(個所數)도 가장 적게 이용(利用)되었으므로 시간(時間), 노력(努力) 및 조사경비(調査經費)가 타방법(他方法)에 비(比)하여 절감(節減)될 수 있는 기초적(基礎的)인 결과(結果)가 나타났다고 사료(思料)되며 삼림조사법(森林調査法)으로는 부차추출법(副次抽出法)이 가장 이상적(理想的)인 방법(方法)으로 구명(究明)되었다.

• 제어로봇시스템학회논문지
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• 제22권9호
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• pp.710-715
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• 2016

Due to its simplicity and high reliability, the box-counting(BC) method is one of the most frequently used techniques to estimate the fractal dimensions of a binary image with a self-similarity property. The fractal calculation requires data sampling that determines the size of boxes to be sampled from the given image and directly affects the accuracy of the fractal dimension estimation. There are three non-overlapping regular grid methods: geometric-step method, arithmetic-step method and divisor-step method. These methods have some drawbacks when the image size M becomes large. This paper presents a BC algorithm for enhancing the accuracy of the fractal dimension estimation based on a new sampling method. Instead of using the geometric-step method, the new sampling method, called the coverage ratio-step method, selects the number of steps according to the coverage ratio. A set of experiments using well-known fractal images showed that the proposed method outperforms the existing BC method and the triangular BC method.

• Communications for Statistical Applications and Methods
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• 제14권1호
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• pp.57-69
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• 2007

Adaptive cluster sampling design is known as a sampling method for rare clustered population. Three modified adaptive cluster sampling designs are proposed. The adjusted Hansen-Hurwitz estimator and the Horvitz-Thompson estimator are considered. Efficiency issue of the proposed sampling designs is discussed in a Monte-Carlo simulation study.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1994년도 Proceedings of the Korea Automatic Control Conference, 9th (KACC) ; Taejeon, Korea; 17-20 Oct. 1994
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• pp.106-111
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• 1994

We proposed a new variable sampling rate model which expresses the phenomena with both rapid and slow components. A method for determining the variable sampling rate and the older of the time series model was explained. The proposed variable sampling rate model was evaluated based oil an information criterion(AIC). Tile variable sampling rate model brought smaller an information criterion than one of a constant sampling rate model of conventional type, and was proved to be effective as a prediction model of the system with both rapid and slow components.

• Journal of Communications and Networks
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• 제5권4호
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• pp.319-327
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• 2003

We consider the problem of low-sampling rate high-resolution channel estimation and timing for digital ultrawideband (UWB) receivers. We extend some of our recent results in sampling of certain classes of parametric non-bandlimited signals and develop a frequency domain method for channel estimation and synchronization in ultra-wideband systems, which uses sub-Nyquist uniform sampling and well-studied computational procedures. In particular, the proposed method can be used for identification of more realistic channel models, where different propagation paths undergo different frequency-selective fading. Moreover, we show that it is possible to obtain high-resolution estimates of all relevant channel parameters by sampling a received signal below the traditional Nyquist rate. Our approach leads to faster acquisition compared to current digital solutions, allows for slower A/D converters, and potentially reduces power consumption of digital UWB receivers significantly.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권7호
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• pp.3217-3238
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• 2018

In this paper, a depth image up-sampling method is put forward by using pixel classifying and jointed bilateral filtering. By analyzing the edge maps originated from the high-resolution color image and low-resolution depth map respectively, pixels in up-sampled depth maps can be classified into four categories: edge points, edge-neighbor points, texture points and smooth points. First, joint bilateral up-sampling (JBU) method is used to generate an initial up-sampling depth image. Then, for each pixel category, different refinement methods are employed to modify the initial up-sampling depth image. Experimental results show that the proposed algorithm can reduce the blurring artifact with lower bad pixel rate (BPR).