• 한국해양학회지:바다
• /
• 제26권1호
• /
• pp.37-48
• /
• 2021

본 연구에서는 해수 중 생물에게 실질적으로 이용되어질 수 있는 자유용존상 농도(freely dissolved concentration)를 보다 쉽고 빠르게 검출하고자 해수를 고속으로 회전시키는 수동형 채집 장치를 제작하였다. 이 고속회전식 수동형 채집 장치(high speed rotation-type passive sampling device)를 한반도 주변해역에 적용하여 해수 중 다환방향족탄화수소(polycyclic aromatic hydrocarbons, PAHs)의 자유용존상 농도를 측정하였다. 또한 대용량 해수 채취법(high volume water sampling)으로부터 구한 PAHs의 용존상 농도(dissolved concentration)와 고속회전식 수동형 채집 장치로부터의 자유용존상 농도를 비교하여 생물에게 직접적으로 이용 될 수 있는 비율을 조사하였다. 그 결과, 고속회전식수동형 채집 장치 모터의 회전속도를 900 rpm으로 가동하였을 때, 소수성이 낮은 저분자 PAHs 화합물(log KOW 3.4 ~ 5.2)은 5시간 만에 평형에 도달하였다. 반면 소수성이 비교적 높은 고분자 화합물(log KOW 5.6 ~ 6.8)의 경우, 평형에 도달하는 데 걸리는 시간은 최소 2일에서 한 달 정도 소요될 것으로 예상되었다. 그러나 실행보정물질(performance reference compounds)를 이용할 경우, 5시간 가동만으로도 평형상태에서의 고분자 화합물의 농도 예측이 가능하였다. 수동형 채집 장치를 적용하여 측정된 조사해역에서의 PAHs의 자유용존상 농도는 0.32 ~ 1.2 ng/L으로 다른 대양에서의 농도보다는 높았지만, 항구나 해안과 같은 연안보다는 매우 낮은 수준이었다. 용존상 및 자유용존상이 모두 검출된 PAHs를 대상으로 생물에게 이용 될 수 있는 비율은 서해병 폐기물 배출해역 위치와 인접한 조사구간에서 가장 높았다. 또한 생물 체내 잔류농도를 예측하였을 때, 폐기물 배출해역이 포함된 외해가 연안보다 비교적 높은 것으로 나타났다.

• 센서학회지
• /
• 제29권3호
• /
• pp.141-148
• /
• 2020

To find food, homes, and mates, some animals have adapted special sensing capabilities. Rather than using a passive method, they discharge a signal and then extract the necessary information from the response. More importantly, they use the slope of the detected signal to find the destination of an object. In this paper, similar strategy is mathematically formulated. A perturbation and correlation-based gradient estimation method is developed and used as a sensing strategy. This method allows us to adaptively sense an object in a given environment effectively. The proposed strategy is based on the use of gradient values; rather than instantaneous measurements. Considering the gradient value, the sampling frequency is planned adaptively, i.e., sparse sampling is performed in slowly varying regions, while dense sampling is conducted in rapidly changing regions. Using a temperature sensor, the proposed strategy is verified and its effectiveness is demonstrated.

• 한국대기환경학회지
• /
• 제21권5호
• /
• pp.481-494
• /
• 2005

The monitoring of persistent organic pollutants (POPs) in the atmosphere is a basis for the study of the fate of POPs in multimedia environments. Recently, passive air samplers (PASs) for POPs have been developed. In this paper, we deal with the principle, properties, and applications of the PAS. The principle of PAS, which has no pump, is physical sorption of semi-volatile organic chemicals on various sorbent materials. The PAS is much smaller than a high-volume air sampler and does not need electricity. These properties of the PAS make it possible to conduct various-scaled environmental monitoring all over the world including the Arctic and Antarctic, but the major disadvantage of PAS is its long sampling periods up to 2 years. To date, four kinds of PAS have been developed: polyurethane foam (PUF), polymer-coated glass (POG), semi-permeable membrane devices (SPMDs), and XAD resin-based PAS. Among them, SPMDs have been commercialized and are most widely used now. Meanwhile, the POPs emitted from China have a large potential to influence the levels and fates of POPs in Korea. Since characteristics of PAS are quite useful to monitor long-range transport of POPs, the use of PAS is highly recommended.

• 한국대기환경학회지
• /
• 제24권2호
• /
• pp.143-152
• /
• 2008

This study investigates the variation and spatial distribution of nitrogen dioxide($NO_2$) concentrations measured with passive diffusive samplers at 40 curbside points in Daejeon. Average $NO_2$ concentration was $39.8{\pm}18.0\;ppb$ (n=1,127) and the significant difference in concentrations by regional groups (Dong-gu, Jung-gu, Seo-gu, Daedeok-gu, Yuseong-gu) was not observed. The frequency distribution of $NO_2$ concentration was found to be a normal distribution with the high frequency in the concentration range of 30 to 40 ppb (20 to 25%). Average $NO_2$ concentration measured during the rainy periods was lower than that measured during the non-rainy periods and the decrease of concentration by rainfall was about 16% (7 ppb). The variation of $NO_2$ concentrations measured by passive diffusive samplers during the sampling period was similar to that continuously measured at the air quality monitoring station.

• 제어로봇시스템학회논문지
• /
• 제14권12호
• /
• pp.1294-1301
• /
• 2008

Under passive RFID environment, this paper presents a new localization of a mobile robot traversing over the floor covered with tags, which is superior to existing methods in terms of estimation performance and cost effectiveness. Basically, it is assumed that a mobile robot is traveling along a series of straight line segments, each segment at a certain constant velocity, and that the number of tags sensed by a mobile robot at each sampling instant is at most one. First, for a given line segment with known starting point, the velocity and position of a mobile robot is estimated using the spatial and temporal information acquired from the traversed tag. Some discussions are made on the validity of the basic assumptions and the localization for the initial segment with unknown starting point. Second, for a given tag distribution density, the optimal tag arrangement is considered to reduce the position estimation error as well as to make easy the tag attachment on the floor. After reviewing typical tag arrangements, the pseudorandom tag arrangement is devised inspired from the Sudoku puzzle, a number placement puzzle. Third, through experiments using our passive RFID localization system, the validity and performance of the mobile robot localization proposed in this paper is demonstrated.

• 대한환경공학회지
• /
• 제33권11호
• /
• pp.790-796
• /
• 2011

본 연구에서는 시화지구의 공단과 주거 지역에서의 휘발성 유기화합물 농도를 능동식과 수동식 시료채취기를 이용해 측정하고 그 특성을 비교 분석하였다. TVOC의 평균농도는 패시브샘플러(passive sampler)의 경우 공단지역이 주거지역보다 1.86배 더 높게 나타났다. 능동식 시료채취기의 경우 공단지역이 주거지역보다 1.07배 더 높게 나타났다. Passive sampler를 이용하였을 경우 공단지역이 주거지역보다 대부분의 물질에서 농도가 높게 나타났지만 열탈착 흡착 튜브(thermal desorption tube)를 이용했을 경우는 트리클로로에틸렌, 톨루엔, 에틸벤젠, 자일렌 등 일부 물질의 농도에 있어서 주거지역이 오히려 높게 나타났다. 전체 BTEX 비율 중에서 전반적으로 톨루엔이 차지하는 비율이 가장 컸으며, passive sampler의 경우 공단지역이 주거지역보다 톨루엔, 에틸벤젠, 자일렌의 상대비율이 높게 나타났다. 그러나 열탈착 흡착 튜브의 경우는 오히려 주거지역이 더 높게 나타났다. 본 연구를 통해서 대기오염 목적성분의 시간적, 공간적 농도 특성 파악을 위한 passive sampler를 이용하면 오염관리 혹은 역학적 연구에 도움이 되는 적절한 시료채취 방법이라는 사실을 알 수 있었다.

• 대한전자공학회논문지TC
• /
• 제45권6호
• /
• pp.34-51
• /
• 2008

인터넷이 일상생활에서 중요한 위치를 차지함에 따라 인터넷에서 발생되는 트래픽의 특성을 밝히는 것은 매우 중요한 연구과제로 주목을 받고 있다. 그러나 인터넷 트래픽은 대용량이므로 쉽게 다룰 수 없다. 이러한 문제는 인터넷 트래픽 측정 연구에 가장 큰 장애다 많은 연구자들은 다양한 샘플링 기법을 통해 트래픽을 다를 수 있는 양으로 샘플링하여 분석하고 있다. 본 연구에서는 기존의 인터넷 측정 연구에서 사용된 샘플링 기법을 비교 분석하고, 가장 효과적인 샘플링 방안을 제시하고자 한다. 연구에 비교 사용된 샘플링 기법은 규칙적 샘플링, 단순 랜덤 샘플링, 층화 샘플링이며, 샘플링 단위는 1/10, 1/100, 1/1000을 사용하였다. 분석한 항목은 트래픽 크기 분석, 엔트로피 분석, 패킷 크기 분석이다. 단순 랜덤 샘플링은 무난한 결과를 보였고, (간격을 패킷 개수로 설정한) 규칙적 샘플링은 대상과 샘플링 강도에 상관없이 고른 결과를 보였다. 한편, 간격을 시간으로 설정한 규칙적 샘플링은 매우 좋지 않을 결과를 나타내었다. 전송층 프로토콜을 기준으로 층화 샘플링 수행할 경우 더욱 좋은 결과를 얻을 수 있었다. 연구 결과를 통해 샘플링 기법이 시간에 따른 트래픽의 흐름을 얼마나 잘 유지하는가가 샘플링 성능을 좌우함을 알 수 있었다. 또한 엔트로피 분석은 샘플링에 강하고, 이상 트래픽 탐지에 매우 적절함이 확인되었다. 그러나 병목 현상에 의한 트래픽 크기 감소는 잘못된 엔트로피 분석 결과를 유발할 수 있음을 발견하였다. 마지막으로, 패킷 크기 분포는 패킷 샘플링 방식이나 강도에 영향을 받지 않음을 발견하였다.

• 농촌지도와개발
• /
• 제16권4호
• /
• pp.1021-1048
• /
• 2009

Based on Rural living indicator -2005 survey data, in RDA this study attempted to investigate Rural Residents' real life satisfaction or identity model by the types of leisure consumption depending on each generation and explored the relationship between leisure consumption and the enhancement of self-identity/ interpersonal relationship, and that between leisure consumption satisfaction and real life satisfaction. Based on systematic random sampling with constructed questionnaires, 1,870 data were collected and analyzed. Overall, the results of this study showed that there are statistically significant differences between generation in leisure consumption. In detail, the findings of this study are as follows. The types of Rural Residents' leisure consumption can be divided into three styles including Semi-leisure type, Passive leisure type and Total leisure type consumption. The preferred types of leisure consumption of Rural Residents' were Semi-leisure type, Passive leisure type and Total leisure type in order. Except for times-pending leisure culture consumption, Semi-leisure type and Passive leisure type influenced on the enhancement of self-identity and interpersonal relationship, then the enhancement of self-identity and interpersonal relationship influenced on leisure consumption-satisfaction, and finally leisure consumption satisfaction influenced on real life satisfaction.

• 한국환경보건학회지
• /
• 제41권2호
• /
• pp.116-125
• /
• 2015

Objective: This study was carried out to use pine needles as a passive air sampler (PAS) for atmospheric polychlorinared dibenzo-p-dioxins/furans (PCDD/Fs). Methods: PCDD/Fs concentrations in ambient air ($C_a$, $pg/m^3$) and deposited pine needles ($C_p$, pg/g dry) were analyzed simultaneously from June 1 to December 31. Air samples were taken using two low volume PUF active air samplers with an overall average air volume of approximately $1,200Sm^3$. Pine needles were collected the end of December near the air sampler. PCDD/Fs was analyzed by HRGC/HRMs. Results: A good correlation was shown ($R^2=0.6357$, p=0.0001) between $C_a$ and $C_p$, but a better correlation ($R^2=0.7372$, p<0.0001) existed between the logarithm of octanol-air partitioning coefficient ($LogK_{oa}$) and Log($C_p/C_a$). The average PCDD/Fs sampling rates from air to pine needles were 0.045($0.018-0.185m^3/day-g\;dry$). Conclusion: It was found that pine needles can be used as PAS for atmospheric PCDD/Fs, and they are especially suitable for long time PAS compared to PUF disk PAS.

• Ocean and Polar Research
• /
• 제31권2호
• /
• pp.189-198
• /
• 2009

Passive air samplers with polyurethane foam (PUF) disks were employed to determine seasonal gas phase variation of polycyclic aromatic hydrocarbons (PAHs) in ambient air on Anmyeon island from March 2007 to January 2008. Sum of 13 PAHs ranged between $3.5\;ng/m^3$ and $27.6\;ng/m^3$. Total PAHs during the heating season was 6.2 times higher than non-heating season. The dominant PAHs components during sampling periods were low and middle molecular weight PAHs including phenanthrene, fluoranthene, pyrene and chrysene. Gas exchange fluxes of PAHs across the air-water interface of the Yellow Sea were calculated using a modified two-film exchange model. PAHs fluxes ranged from $196\;ng/m^2/d$ net volatilization during summer to $3830\;ng/m^2/d$ net absorption during winter. Passive air sampler provides a convenient and cost-effective tool for measuring averaged gas phase PAHs, which was successfully used for calculation of gas exchange flux of PAHs in the Yellow Sea.