• Journal of Ecology and Environment
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• v.47 no.4
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• pp.250-260
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• 2023

Background: Crabgrass (Digitaria ciliaris, Poaceae) is a globally distributed weed, including in Afro-Eurasia, America, and Australia. As a highly gregarious plant, crabgrass is an important habitat for a diverse array of insects, and a potential habitat for agricultural pests. To compare the insect communities associated with the crabgrass community, insects were sampled using sweep sampling (100 sweeps per sample) at five sites, including Daejeon (Daejeon and Gap rivers), Anseong, Namhae, and Inje, with a focus on the Daejeon River. Results: A total of 5,888 individual insects belonging to eight orders, 42 families, and 115 species were collected from the five sites. Both the number of species and individuals of Hemiptera were the highest at all of the sites. In the present study, 73% of the insect population fed on D. ciliaris as a host plant. The dominant species in the D. ciliaris community was Laodelphax striatellus (Delphacidae), being ubiquitous at all the sites which showed a high abundance of rice pests in the communities and the suitability of D. ciliaris as an alternative host plant for them. The Shannon-Wiener diversity index was highest in Inje on 17 September (2.88), and the Chao1-bc diversity index was highest in the Gap River on 5 September (80). The sampling efficiency of 100 sweep samples (sample coverage) was calculated to be as high as 90%. The results of the samples taken from September to November in the Daejeon River showed that the number of species and individuals decreased gradually over time, and the number of dominant species decreased sharply between September and October. Similarity analysis indicated that sampling dates that were closer together yielded sampled assemblages with higher faunal similarity. In addition, in each sampling, the difference in the minimum temperature during the two-week period prior to sampling and faunal similarities were negatively correlated. Conclusions: This study provides foundational data that could enhance our understanding of insect diversity in D. ciliaris. The data can facilitate ecological conservation and management of Korean grasslands generally, as well as identification of potential pests that may disperse from D. ciliaris communities to nearby farmland.

• Proceedings of the IEEK Conference
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• 2000.07b
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• pp.1080-1083
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• 2000

In this paper, we show that a variation in sampling rate give rise to system performance degradation and propose a method to effectively reduce the error. We first capture the variation as a first order autoregressive (AR) model and project it as an additional sensor measurement noise. By considering that the sensor measurements include correlated noise, we perform a decorrelation process and then apply a standard Kalman filter (SKF) to estimate the target-state. As a result of the two-step procedure, we achieve a significant reduction in the target state estimation error.

• Journal of Korean Society for Atmospheric Environment
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• v.21 no.6
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• pp.593-603
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• 2005

Passive sampler using 4-amino-3-hydrazino-5-mercapto-1, 2, 4-triazole (AHMT) was developed to determine formaldehyde in indoor environment. The chromatography paper cleaned by $3\%$ hydrogen peroxide solution was experimently determined as a optimum absorbtion filter for the collection of formaldehyde. The passive sampler with a broad cross-sectional area and a short diffusion length was quite good in sensitivity. The passive sampler and the active sampling method with an impinger were strongly correlated with a correlation coefficient of 0.9848. The limits of detection and quantification of the passive sampler for the measurement of formaldehyde in the indoor environment were 7.5 and 10.2 ppb, respectively. Temperature ($19\∼28^{circ}C$) and relative humidity ($30\∼90\%$) had slight influence on the sampling rate of the passive sampler. However, the increase of flow velocity on the surface of sampler resulted in the increase of sampling rate.

• Survey Research
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• v.11 no.3
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• pp.103-114
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• 2010

It is difficult to obtain the population information of target variables when a new sampling design for successive survey is executed. In a research of the Korea National Tourism Survey, we propose a method for selection of efficient stratification variables which are found in a combination of a existing sample data and a new frame list. At first, if there isn't common identification number between the frame list and the sample data, we find a device to substitute for absence of identification number. At second, we suggest a method to search stratification variables correlated with target variables using statistical methods like regression analysis.

• Journal of Environmental Health Sciences
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• v.18 no.2
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• pp.135-145
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• 1992

This study was carried out to find out some characteristic responses of biological samples under the exposure of trace metals with the considering of Sex, age, residence period and smoking. Blood, Urine and Hair were collected from 116 dwellers in the vicinity of a smelting factory. Cd, Cu, Pb and Zn concentrations were determined by flame atomic absorption spectrophotometry and the following results were found important. 1) The concentrations of trace metals in the blood were 0.010+ 0.003 $\mu$g/ml in Cd, 0.82+ 0.11 $\mu$g/ml in Cu, 0.23_+ 0.13 $\mu$g/ml in Pb and 5.78_+ 1.43 $\mu$g/ml in Zn, those in the urine were 1.7_+ 1.7 $\mu$g/l in Cd, 16.5_+ 16.0 $\mu$g/l in Cu, 24.6_+ 23.0 $\mu$g/l in Pb and 367.7_+ 283.4 $\mu$g/l in Zn, and those in the hair were 0.52_+ 0.56 $\mu$g/g in Cd, 11.00_+4.01 $\mu$g/g in Cu, 8.53_+ 7.05 $\mu$g/g in Pb and 383.23_+ 110.56 $\mu$g/g in Zn. 2) In sex, the concentrations of Zn in the blood and urine of male were higher than those of female, however, the concentrations of Cd and Zn in the hair of female were higher than those of male. 3) The concentrations of Cd, Pb and Zn in the urine showed an increasing trend by age. 4) While the concentration of Cd in the urine increased, the concentration of Pb in the hair decreased by residential period in all the samples. 5) The concentrations of Cd and Zn in the blood and that of Zn in the urine of smoking group were higher than those of non-smoking group. The concentration of Pb in the blood of smoking group and those of Cd, Pb and Zn in the urine of non-smoking group showed increasing the trend by age. The concentrations of Cd and Zn in the urine of non-smoking group, the concentration of Zn in the hair of smoking group showed increasing trend by residential period, however, the concentrations of Pb in the blood and hair and that of Zn in the hair showed decreasing trend by residential period. 6) When the correlations of the concentrations between Zn (main smelting metal) and other metals were analyzed, Zn in the blood was significantly correlated with Cu, Pb and Zn in the urine (positively) and Zn in the urine was significantly correlated with Zn in the blood, Cd, Cu and Pb in the urine, and Pb in the hair (positively). Zn in the hair was significantly correlated with Cd in the urine and Cu in the hair (positively). 7) Consequently, it was useful to note that samples of urine showed higher sensitivity under the metal exposure than those of blood and hair in individual sampling. In addition, as trace metals showed higher accumulation in the hair of the groups, sampling of hair was more highly recommended than those of urine and blood in group sampling.

• Journal of Preventive Medicine and Public Health
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• v.43 no.4
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• pp.301-308
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• 2010

Objectives: In most DEHP exposure assessment studies, single spot urine sample was used. It could not compare the exposure level among studies. Therefore, we are going to represent the necessity of selection of proper sampling time of spot urine for assessing the environmental DEHP exposure, and the association urinary DEHP metabolites with steroid hormones. Methods: We collected urine and plasma from 25 men. The urine sampling times were at the end of the shift (post-shift) and the next morning before the beginning of the shift (pre-shift). Three metabolites of DEHP {mono(2-ethylhexyl) phthalate [MEHP], mono-(2-ethyl-5-hydroxyhexyl)phthalate [MEHHP], and mono(2-ethyl-5-oxohexyl)phthalate [MEOHP]} in urine were analyzed by HPLC/MS/MS. Plasma luteinzing hormone, follicle stimulating hormone, testosterone, and $17{\beta}$- estradiol were measured at pre-shift using a ELISA kit. A log-transformed creatinine-adjusted urinary MEHP, MEHHP, and MEOHP concentration were compared between the post- and pre-shift. The Pearson’s correlation was calculated to assess the relationships between log-transformed urinary MEHP concentrations in pre-shift urine and hormone levels. Results: The three urinary metabolite concentrations at post-shift were significantly higher than the concentrations in the pre-shift (p<0.0001). The plasma hormones were not significantly correlated with log-transformed creatinine - adjusted DEHP metabolites. Conclusions: To assess the environmental DEHP exposure, it is necessary to select the urine sampling time according to the study object. There were no correlation between the concentration of urinary DEHP metabolites and serum hormone levels.

• Journal of Korea Multimedia Society
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• v.23 no.7
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• pp.883-890
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• 2020

In this paper, we propose a variational expectation-maximization algorithm that computes posterior probabilities from Latent Dirichlet Allocation (LDA) model. The algorithm approximates the intractable posterior distribution of a document term matrix generated from a corpus made up by 50 papers. It approximates the posterior by searching the local optima using lower bound of the true posterior distribution. Moreover, it maximizes the lower bound of the log-likelihood of the true posterior by minimizing the relative entropy of the prior and the posterior distribution known as KL-Divergence. The experimental results indicate that documents clustered to image classification and segmentation are correlated at 0.79 while those clustered to object detection and image segmentation are highly correlated at 0.96. The proposed variational inference algorithm performs efficiently and faster than Gibbs sampling at a computational time of 0.029s.

• Research in Community and Public Health Nursing
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• v.18 no.2
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• pp.223-231
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• 2007

Purpose: This study was to compare differences in and correlation among depression. sleep and fatigue between younger and older elders. Method: A total of 370 subjects aged between 65 and 88 were selected through convenient sampling. Data were collected using a self report questionnaire from March to December, 2005. Results: Younger elders showed lower levels of depression and fatigue than older ones. The level of sleep satisfaction was higher in older elders than in younger ones. In both groups, fatigue was positively correlated to depression, and depression and fatigue were negatively correlated to sleep satisfaction. In addition, fatigue was affected by depression, the number of persons in household and sleep satisfaction. Conclusion: Older elders showed more serious health problems than younger ones. It is necessary to develop comprehensive intervention programs in order to promote healthy lifestyle for older elders.

• Research in Community and Public Health Nursing
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• v.17 no.2
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• pp.235-241
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• 2006

Purpose: This study was to review dysmenorrhea and its relief methods in nursing students by using base data for reducing dysmenorrhea. Method: The subjects were 92 students, data were collected by questionnaire surveys using convenience sampling and analyzed by the SPSS 12.0 program. Results: Medium amount of menstruation was most frequently answered and massage on painful sites was the most frequently used relief method(p<0.05). Frequency of medication was once a day during menstrual period, and methods that the most wanted to use when pain got severe was alternative methods(aroma, massage, and acupuncture)(p<0.05). Amount of menstruation showed a negative correlation with the duration(r=-0.32), dysmenorrhea was correlated with the severest days of dysmenorrhea(r=0.24) and the frequency of medication(r=-0.23). Conclusion: These results suggested that dysmenorrhea was correlated with the severest days of dysmenorrhea and the frequency of medication, but other variables showed no relations with menstrual characteristics.

• Journal of Korean Academy of Nursing
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• v.34 no.2
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• pp.270-277
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• 2004

Purpose: The purpose of this study was to investigate the relationship between decision-making factors(theoretical knowledge, expertise, empowerment, intuition) and participation in proportion to nurses's clinical experience. Method: Data was collected by quota sampling from July 10, 2001 to August 22, 2001 from 132 clinical nurses who work for 3 General hospitals. Data was analyzed using SPSSWIN 10.0 with crosstab, ANOVA, and stepwise multiple regression. Result: Expertise(F=34.347, p=.000), empowerment(F=29.316, p=.000), and participation(F=3.276, p=.041) were significantly different among 3 clinical experience groups. Clinical experience correlated with expertise(r=.551, p=.000) and empowerment(r=.492, p=.000), and Decision-making participation also correlated with expertise(r=.351, p=.000) and empowerment(r=.265, p=.002). Decision-making participation is effected by theoretical knowledge(under 3.00yr clinical experience), expertise(3.01-5.00yr), and empowerment(above 5.01yr). Conclusion: These findings indicate that factors(theoretical knowledge, expertise, or empowerment) on decision-making participation varies as nurses's clinical experience differs. Therefore, decision-making needs bilateral agreement between staff nurses and nurse managers rather than the responsibility of one.