• 사회복지연구
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• 제44권3호
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• pp.301-322
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• 2013

본 연구는 한국노동패널조사의 1~11차 년도(1998~2008년) 자료를 이용하여 가구특성과 빈곤지속기간이 빈곤탈피에 미치는 영향을 분석하였다. 특히 빈곤지속기간이 경과할수록 빈곤탈피율이 낮아지는 현상이 진정한 지속기간의존성에 의한 것인지 또는 표본이질성에 기인한 것인지를 검증하고 비관찰 이질성을 통제할 때 독립변수의 영향력이 어떻게 달라지는지를 분석하는데 초점을 두었다. 관찰 비관찰 이질성을 통제하면 지속기간의존성이 대부분 사라진다는 분석결과는 겉으로 보이는 지속기간의존성이 사실은 표본이질성으로 인한 가식적 관계임을 의미한다. 또한 비관찰 이질성을 통제한 모형에서는 가구특성의 영향력이 더욱 커졌다. 연령, 교육수준, 가구형태, 가구원 수 등의 인구 사회적 특성과 취업상태 및 종사상 지위 등 경제활동 특성이 빈곤탈피율에 영향을 미친다.

• 한국물환경학회지
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• 제31권6호
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• pp.610-618
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• 2015

This study was conducted to find out the influence of sample size (accumulated survey areas) on the seven biological indices of benthic macroinvertebrates. BMI, the index similar to Zeilika-Marvan’s saprobic index, tended to be independent on the variations of sample size. The other indices (Shannon-Weaver’s diversity, Margalef’s richness, Menhinick’s richness, Pielou’s evenness, and Lenat’s EPT index) showed the considerable variations along with the increase of sample size and environmental conditions. To get the appropriate index values, it should be sampled at least 6 replicates more based on 30×30cm Surber sampler. In addition, the habitat heterogeneity index of benthic macroinvertebrates suggested in this study, it will be able to be used for evaluating the heterogeneity of habitats.

• Applied Microscopy
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• 제42권1호
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• pp.49-52
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• 2012

For TEM study of biological samples or polymers that are contained in organic structure, it is often required that the sample is prepared by using ultramicrotome and stained with proper agents to increase the contrast of organic structure. In this study, we investigated an efficient TEM sample preparation method for ductile heterogeneity material by using ultramicrotomy. Cryo-ultramicrotomy is a suitable method that is capable of rendering sample hardness for various ductile materials. However, it has several factors to consider, such as experimental cost, working time and finding the optimal staining conditions. To satisfy these considerations, we prepared TEM sample by using ultramicrotome without cryofunction, and secured the sample hardness by applying the staining process prior to ultrathin sectioning. The cross-linked polyethylene structure in the sample was stained with the 2% $RuO_4$ solution in a sealed test tube for 24 hours at $4^{\circ}C$. After the sample staining, ultrathin sections of sample were prepared using ultramicrotome. As a result, it was revealed that the difficulties associated with staining of ultrathin sections prepared by low-temperature conditions were improved. In addition, appropriate staining depth of sample could be selected for sectioning process. The quality of TEM sample obtained by using this method was better than that of cryo-ultramicroscopy. Finally, it is expected that our method could be effectively applied in TEM sample preparation for a variety of nano-bio convergence materials.

• Asian-Australasian Journal of Animal Sciences
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• 제25권7호
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• pp.1045-1054
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• 2012

The phylogenetic diversity of the bacteria in hot composting samples collected from three spatial locations was investigated by molecular tools in order to determine the influence of gradient effect on bacterial communities during the thermophilic phase of composting swine manure with rice straw. Total microbial DNA was extracted and bacterial near full-length 16S rRNA genes were subsequently amplified, cloned, restriction fragment length polymorphism-screened and sequenced. The superstratum sample had the highest microbial diversity among the three samples which was possibly related to the surrounding conditions of the sample resulting from the location. The results showed that the sequences related to Bacillus sp. were most common in the composts. In superstratum sample, 45 clones (33%) and 36 clones (27%) were affiliated with the Bacillus sp. and Clostridium sp., respectively; 74 clones (58%) were affiliated with the Clostridium sp. in the middle-level sample; 52 clones (40%) and 29 clones (23%) were affiliated with the Clostridium sp. and Bacillus sp. in substrate sample, respectively. It indicated that the microbial diversity and community in the samples were different for each sampling site, and different locations of the same pile often contained distinct and different microbial communities.

• 한국지하수토양환경학회지:지하수토양환경
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• 제16권6호
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• pp.1-9
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• 2011

A bibliographical review of Gy sampling theory for particulate materials was conducted to provide readers with useful means to reduce errors in soil contamination investigation. According to the Gy theory, the errors caused by the heterogeneous nature of soil include; the fundamental error (FE) caused by physical and chemical constitutional heterogeneity, the grouping and segregation error (GE) aroused from gravitational force, long-range heterogeneous fluctuation error ($CE_2$), the periodic heterogeneity fluctuation error ($CE_3$), and the materialization error (ME) generated during physical process of sample treatment. However, the accurate estimation of $CE_2$ and $CE_3$ cannot be estimated easily and only increasing sampling locations can reduce the magnitude of the errors. In addition, incremental sampling is the only method to reduce GE while grab sampling should be avoided as it introduces uncertainty and errors to the sampling process. Correct preparation and operation of sampling tools are important factors in reducing the incremental delimitation error (DE) and extraction error (EE) which are resulted from physical processes in the sampling. Therefore, Gy sampling theory can be used efficiently in planning a strategy for soil investigations of non-volatile and non-reactive samples.

• Genomics & Informatics
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• 제17권1호
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• pp.2.1-2.12
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• 2019

Chronic obstructive pulmonary disease (COPD) is a type of progressive lung disease, featured by airflow obstruction. Recently, a comprehensive analysis of the transcriptome in lung tissue of COPD patients was performed, but the heterogeneity of the sample was not seriously considered in characterizing the mechanistic dysregulation of COPD. Here, we established a new transcriptome analysis pipeline using a deconvolution process to reduce the heterogeneity and clearly identified that these transcriptome data originated from the mild or moderate stage of COPD patients. Differentially expressed or co-expressed genes in the protein interaction subnetworks were linked with mitochondrial dysfunction and the immune response, as expected. Computational protein localization prediction revealed that 19 proteins showing changes in subcellular localization were mostly related to mitochondria, suggesting that mislocalization of mitochondria-targeting proteins plays an important role in COPD pathology. Our extensive evaluation of COPD transcriptome data could provide guidelines for analyzing heterogeneous gene expression profiles and classifying potential candidate genes that are responsible for the pathogenesis of COPD.

• 응용통계연구
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• 제30권2호
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• pp.301-309
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• 2017

일반적으로 각 N개의 모집단에서 2개 이상의 표본이 추출되었을 때, $H_0:{\mu}_1={\cdots}={\mu}_N$의 가설에 대하여 검정할 수 있지만 각 모집단으로부터 표본이 한 개씩 추출된다면 ${\bar{X}}$가 존재하지 않으므로 모평균의 차이 검정은 불가능하다. 하지만 하나씩 추출된 표본으로 구성된 집단을 두 집단으로 나누어 임의의 평균을 생성함으로써 평균의 차이를 비교한다면 표본들 사이에 존재할 수 있는 이질성을 파악할 수 있다. 따라서 우리는 두 집단으로 나눌 수 있는 조합의 수만큼 평균 차이를 검정할 수 있는 최소 조합 t-검정 방법을 제안하고자 한다. 최종적으로 본 논문에서는 한 개씩 추출된 표본들 사이의 이질성을 확인하기 위하여 평균 차이를 검정할 수 있는 방법을 제안하였고 모의실험 연구를 통해 성능을 확인하였고 실제 자료 분석을 통해 결과를 도출하였다.

• The Journal of Asian Finance, Economics and Business
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• 제8권2호
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• pp.15-23
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• 2021

This study investigates the presence of the day-of-the-week anomaly in exchange rate for 30 developing countries with free floating exchange rate regimes using daily data from January 2, 2011 to December 31, 2019. First, we apply the GARCH panel to estimate the intraday effect for all the sampled countries. Second, we run poolability test to check whether the coefficients of the GARCH panel are the same for all countries sampled. The result of poolability test rejects the homogeneity assumption. This implies that our sample countries contain heterogeneity. Third, we apply mean-group estimation by averaging the coefficients for all individual GARCH estimations. Fourth, we divided our sample of developing countries into three groups based on capital restriction index for the reason that the effect of monetary policy on the exchange rate depends on the degree of capital account liberalization. The empirical evidence for the return equation suggests that Mondays are connected with lower volatility whereas Thursdays experiences higher return compared to Tuesdays. The lowest estimated coefficient for full sample, group 1 and group 2, is Friday, but for group 2 is Thursday. We find similar result for the volatility equations, which show that Monday returns are lower compared to Tuesday.

• Asian Pacific Journal of Cancer Prevention
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• 제15권8호
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• pp.3691-3698
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• 2014

Background: Published studies on the association between the Ras Association Domain Family 1 isoform A (RASSF1A) Ala133Ser polymorphism and cancer susceptibility have yielded conflicting results. Thus, a meta-analysis was here performed to assess the possible association. Materials and Methods: All eligible case-control studies published up to November 2013 on the association between RASSF1A Ala133Ser polymorphism and cancer susceptibility were identified by searching PubMed, Web of Science, Science Direct and hand search. Bothfixed-effect and random-effect models were used to calculate pooled odds ratios (ORs) with 95% confidence intervals (CIs) by using the Comprehensive Meta-Analysis software version 2.2. Results: A total of 10 studies including 4,572 cancer cases and 4,320 controls were included in the meta-analysis. Overall, significantly increased cancer risk was associated with the variant Ser133 when all studies were pooled (Ser vs Ala: OR=1.51, 95% CI=1.08-2.12, $P_{heterogeneity}{\leq}0.001$; Ser/Ser+Ala/Ser vs Ala/Ala: OR=1.55, 95% CI=1.08-2.22, $P_{heterogeneity}{\leq}0.001$). Moreover, in subgroup analyses by cancer types, a significant association between RASSF1A Ala133Ser polymorphism and lung cancer risk was found (Ser vs Ala: OR=2.27, 95% CI=1.29-4.02, $P_{heterogeneity}$=0.61; Ser/Ser+Ala/Ser vs Ala/Ala: OR=2.42, 95% CI=1.33-4.42, $P_{heterogeneity}=0.75$). In addition, in subgroup analyses by ethnicity, it was found that the RASSF1A Ala133Ser polymorphism was associated with overall cancer risk in Asians (Ser vs Ala: OR=1.37, 95% CI=1.06-1.77, $P_{heterogeneity}=0.06$) and Caucasians (Ser/Ser+Ala/Ser vs Ala/Ala: OR=2.21, 95% CI=1.01-4.82, $P_{heterogeneity}{\leq}0.001$). Conclusions: This meta-analysis suggests, for the first time, that RASSF1A Ala133Ser polymorphism may contribute to cancer susceptibility, especially for lung cancer. Besides, additional well-designed studies with larger sample size focusing on different ethnicities and cancer types are needed to confirm these findings.

• 응용통계연구
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• 제32권3호
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• pp.331-348
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• 2019

전이성 종양의 성장패턴 차이와 변화율에 따른 종양 이질성(tumor heterogeneity)을 파악하는 것은 종양세포의 약물에 대한 민감성을 파악하고 적절한 치료법을 찾아내기 위해 중요하다. 일반적으로 N개의 표본의 집단이 구분된다면 t-test 혹은 ANOVA 분석을 통해 집단별 평균의 차이에 대한 검정이 가능하다. 그러나 본 논문에서 다루는 데이터와 같이 집단이 구분되지 않는 경우 이러한 방법들은 사용될 수 없다. 표본들 사이의 이질성을 검정하기 위한 통계적 방법들이 연구되어 왔다. 최소 조합 t-검정 방법은 그 중 하나이다. 본 논문에서는 상이한 비율로 데이터를 양분하는 조합도 고려하는 최대 조합 t-검정 방법을 제안한다. 한편, 표본의 이질성을 검정하는 것이 군집분석에서 최적의 군집의 개수가 2개 이상인지를 검정하는 것과 같음에 착안하여 새로운 방법을 제안한다. 최대 조합 t-검정과 gap통계량을 이용하면 이전에 제안된 방법보다 개선된 제1종의 오류를 범할 확률과 검정력을 갖는다는 것을 모의실험을 통해 확인하였고 실제 자료 분석을 통해 결과를 도출하였다.