• Journal of Korean Society for Atmospheric Environment
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• v.18 no.E1
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• pp.1-12
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• 2002

One technique for determining dry acid deposition fluxes involves measurement of time - averaged ambient concentrations of dry acid deposition species using filter packs (FP) coupled with estimates of mean deposition velocities for the exposure period. A critical problem associated with filter pack data comparisons between various field sampling networks is the use of diverse sampling flow rates and duration protocols. Field experiments were conducted to evaluate the effects of varying sampling flow rates, from 1.5 to 10 standard liters per minute, on total nitrate and sulfate measurements of specific dry acid deposition species . Collocated FP samplers were used to determine sampling and analysis data reproducibility and representativeness . Ambient air samples were simultaneously collected using groups of filter packs operated at various flow rates over identical 7 day periods. The species measured were sulfur dioxide, particulate sulfate , nitric acid and particulate nitrate. Statistical results (ANOVA; alpha level 5%) showed that neither the low nor high sampling flow rates caused a significant difference in the measurements of total sulfate and adjusted total nitrate (ATN) . However, it was concluded that for high flow rate sampling measurements, total nitrate (TN) could be affected during extended sampling durations because of potential nitric acid overloading and breakthrough. Although the previous workers (Costello, 1990; Quillian, 1990) used much higher sampling flow rates (~ 17 sLpm) than employed here, it was assumed that for a high loading (> 50$\mu\textrm{g}$ HNO$_3$) of nitric acid on the Nylon filters, a significant fraction (~10%) of nitric acid could pass through the Nylon filters and be collected on the carbonate impregnated filters. It was concluded that even at the highest sampling flow rate employed (10 sLpm) at the Cary Forest site, nitric acid breakthrough was less than 10% of the total HNO$_3$ collected. However, for a heavily polluted urban airshed or with longer sampling times , higher filter loadings could result in substantial nitric acid breakthrough and HNO$_3$concentrations would be underestimated.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.5
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• pp.3029-3035
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• 2013

Background: Most developing countries have been unable to implement well-organized health care systems, especially comprehensive Pap smear screening-based programs. One of the reasons for this is regional differences in medical services, and a low-cost portable cervical screening system is necessary. To improve regional discrepancies in cervical screening systems, we investigated the usefulness and acceptability of cervical selfsampling by liquid-based cytology (LBC) for 290 volunteers in the Lao PDR. Materials and Methods: Following health education with comprehensive documents, cervical self-sampling kits by LBC were distributed in three provincial, district, and village areas to a total of 290 volunteers, who were asked to take cytology samples by themselves. Subsequently, the acceptability of self-sampling was evaluated using a questionnaire. Results: The documents were well understood in all three regions. Regarding the acceptability of self-sampling, the selections for subsequent screening were 62% self-sampling, 36% gynecologist-sampling, 1% either method, and 1% other methods. The acceptability rates were higher in the district and the village than in the province. For the relationship between acceptability and pregnancy, the self-sampling selection rate was higher in the pregnancy-experienced group (75%) than in the pregnancy-inexperienced group (60%). For the relationship between selection of self-sampling and experience of screening, the self-sampling selection rate was higher in the screening-inexperienced group (62%) than in the screening-experienced group (52%). Conclusions: Our data show that this new way forward, involving a combination of self-sampling and LBC, is highly acceptable regardless of age, educational background, and residence in rural areas in a developing country.

• Journal of Biomedical Engineering Research
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• v.31 no.4
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• pp.316-320
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• 2010

HRV(Heart rate variability) analysis parameter is widely used as an index to evaluate the autonomic nervous system and cardiac function. For reliable HRV analysis, we need to acquire the accurate ECG signals. Most of commercially available portable ECG devices have low sampling rate because of low power consumption and small size issues, which make it difficult to measure RR-interval accurately. This study is to improve the accuracy of RR-interval by developing R-wave interpolation technique, based on the morphological characteristics of the QRS complex. When the developed method was applied to ECG obtained at 200 Hz and the results were compared with 1000 Hz reference device, the error range decreased by 1.33 times in sitting and by 2.38 times in cycling exercise. Therefore, the proposed interpolation technique is thought to be useful to improve the accuracy of R-R interval in the portable ECG device with low sampling rate.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.11
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• pp.4677-4683
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• 2015

When there is no sampling frame within a certain group or the group is concerned that making its population public would bring social stigma, we say the population is hidden. It is difficult to approach this kind of population survey-methodologically because the response rate is low and its members are not quite honest with their responses when probability sampling is used. The only alternative known to address the problems caused by previous methods such as snowball sampling is respondent-driven sampling (RDS), which was developed by Heckathorn and his colleagues. RDS is based on a Markov chain, and uses the social network information of the respondent. This characteristic allows for probability sampling when we survey a hidden population. We verified through computer simulation whether RDS can be used on a hidden population of cancer survivors. According to the simulation results of this thesis, the chain-referral sampling of RDS tends to minimize as the sample gets bigger, and it becomes stabilized as the wave progresses. Therefore, it shows that the final sample information can be completely independent from the initial seeds if a certain level of sample size is secured even if the initial seeds were selected through convenient sampling. Thus, RDS can be considered as an alternative which can improve upon both key informant sampling and ethnographic surveys, and it needs to be utilized for various cases domestically as well.

• IEIE Transactions on Smart Processing and Computing
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• v.3 no.1
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• pp.19-27
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• 2014

Compressive sensing is an emerging sampling technique which enables sampling a signal at a much lower rate than the Nyquist rate. In this paper, we propose a novel framework based on Kronecker compressive sensing that provides multi-resolution image reconstruction capability. By exploiting the relationship of the sensing matrices between low and high resolution images, the proposed method can reconstruct both high and low resolution images from a single measurement vector. Furthermore, post-processing using BM3D improves its recovery performance. The experimental results showed that the proposed scheme provides significant gains over the conventional framework with respect to the objective and subjective qualities.

• Journal of Ecology and Environment
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• v.47 no.2
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• pp.35-41
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• 2023

Background: Several species of amphibians in agricultural areas are often infected with ranaviruses; however, the biological or ecological factors that cause this infection are not well understood. In this study, we investigated whether local tadpole density, Gosner developmental stage, and weather conditions affected ranavirus infection in Dryophytes japonicus tadpoles in rice paddies over three months. Results: During the study, eight samplings were undertaken between June 6 and August 21, 2022. No die-off of tadpoles occurred, but 20 of 110 tadpoles (18.8%) were found to be infected with ranavirus. The tadpole density at the sampling site and Gosner stage of the sampled tadpoles were not related to the daily ranavirus infection rate. The mean daily highest temperature during the two weeks prior to the sampling date and the mean daily lowest and highest temperatures during the week prior to the sampling date were negatively related to the daily infection rate. Conclusions: Our results suggest that low and extreme temperatures caused by flooding and draining of paddy fields or climate change in summer could be a significant risk factor for ranavirus infection in summer-breeding frogs in agricultural areas.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.12C
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• pp.1249-1256
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• 2006

This paper proposes, based on a bandpass sampling theory, a novel method to find valid sampling frequency range and minimum sampling rate with low computational complexity for downconversion of multiple bandpass radio frequency (RF) signals. Guard-bands or spacing between adjacent downconverted signal spectrums are also taken into consideration in determining sampling frequency for practical implementation. Moreover, we verify through comparison with other method that the proposed method has more advantageous properties.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.12A
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• pp.1286-1295
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• 2007

This paper proposes, based on a bandpass sampling theory, a novel method to find valid sampling frequency range and minimum sampling rate with low computational complexity for downconversion of N bandpass radio frequency(RF) signals, under application of all possible signal placements(full permutations) in a IF stage. Additionally, we have developed a complexity-reducing method to obtaine the opttimal and minimal sampling rate for supporting the user-wanted guard-band or spacing between adjacent downconverted signal spectrums. Moreover, we have verified through comparisons with other methods that the proposed methods have more advantageous properties.

• The Journal of the Acoustical Society of Korea
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• v.23 no.1
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• pp.54-60
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• 2004

In order to mitigate the problems in storage space and network bandwidth for the full CD quality audio, current digital audio is always restricted by sampling rate and bandwidth. This restriction normally results in low sample rate audio or calls for the data compression scheme such as MP3. However, they can only reproduce a lower frequency range than a regular CD quality because of the Nyquist sampling theory. Consequently they lose rich spatial information embedded in high frequency. The propose of this paper is to propose efficient high frequency enhancement of low sample rate audio using n adaptive filtering and DWT analysis and synthesis. The proposed algorithm uses the LMS adaptive algorithm to estimate the missing high frequency contents in DWT domain and it then reconstructs the spectrally enhanced audio by using the DWT synthesis procedure. Several experiments with real speech and audio are performed and compared with other algorithm. From the experimental results of spectrogram and sonic test, we confirm that the proposed algorithm outperforms the other algorithm and reasonably works well for the most of audio cases.

• Journal of Environmental Health Sciences
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• v.42 no.2
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• pp.102-111
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• 2016

Objectives: This study was conducted to evaluate the use of polyurethane foam disk passive air samplers (PUF PAS) for better measurement of atmospheric polychlorinared dibenzo-p-dioxins/furans (PCDD/Fs) concentrations compared to PUF PAS combined with high volume air samplers (HVS). Methods: Air samples were collected by a low volume air sampler (LVS) and PUF PAS. A total of two pairs were continuously collected for six months, but the PUF was replaced every two months. Results: A good correlation was shown ($R^2=0.8595$, p<0.0001) between atmospheric PCDD/Fs concentration measured by the LVS and PUF PAS. The average air sampling rate ($1.5m^3/day-sampler$) of all PCDD/Fs congeners showed a middle of the means which were measured using a HVS by other researchers in different cities. In addition, the air sampling rates of the LVS for each congener made less difference than did those of the HVS. Conclusion: It was found that measurements using the LVS were less influenced by atmospheric peak PCDD/Fs concentrations. However, trace POPs such as PCDD/Fs may involve relatively large analytical errors in measurement, and as a result the air sampling rate of the respective PCDD/Fs isomer is also likely to involve errors. The method of using a regression straight line between the concentrations obtained from the LVS and those from the PUF PAS was judged higher than the method using the air sampling rate, since the former compensated for the experimental errors in the process of evaluation of atmospheric PCDD/F concentrations using the PUF PAS.