• 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.

• Genomics & Informatics
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• 제20권4호
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• pp.49.1-49.7
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• 2022

Many packages for a meta-analysis of genome-wide association studies (GWAS) have been developed to discover genetic variants. Although variations across studies must be considered, there are not many currently-accessible packages that estimate between-study heterogeneity. Thus, we propose a python based application called Beta-Meta which can easily process a meta-analysis by automatically selecting between a fixed effects and a random effects model based on heterogeneity. Beta-Meta implements flexible input data manipulation to allow multiple meta-analyses of different genotype-phenotype associations in a single process. It provides a step-by-step meta-analysis of GWAS for each association in the following order: heterogeneity test, two different calculations of an effect size and a p-value based on heterogeneity, and the Benjamini-Hochberg p-value adjustment. These methods enable users to validate the results of individual studies with greater statistical power and better estimation precision. We elaborate on these and illustrate them with examples from several studies of infertility-related disorders.

• 한국정보과학회논문지:정보통신
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• 제31권3호
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• pp.305-313
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• 2004

웹 객체의 저장과 처리를 위한 캐시의 사용이 증대하고 있으며, 캐시 저장영역의 효율적인 관리를 위한 많은 연구가 활발히 이루어지고 있다. 웹 캐싱 기법은 전통적인 기법과 차이가 있다. 특히 웹 캐싱의 처리 단위인 웹 객체의 이질성과, 시간에 따른 웹 객체 참조특성 변화는 기존 기법들의 성능을 감소시키는 중대한 원인이 되고 있다. 본 연구에서는 새로운 웹 캐싱 기법인 ACASH(the Adaptive Caching Algorithm with Size Heterogeneity)를 제안하였다. ACASH는 웹 객체와 캐시 영역을 이질성을 기반으로 분할 관리함으로서 객체의 이질성 편차를 줄였고, 시간의 흐름에 따른 객체 참조 특성의 변화를 적응적으로 반영하고 있다. 또한 객체의 이질성을 고려한 두 개의 실험 모델에 대해, 기존의 대체 기법들과 비교 실험을 통해 ACASH의 우수성을 확인하였다.

• East Asian Economic Review
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• 제16권4호
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• pp.315-331
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• 2012

Previous studies of location choice have focused on country-level data more than firm-level data and been more concerned with host countries' distinctive features than with firm heterogeneity. Therefore, they do not answer the question of who will go where in terms of location choice. To analyze the role of firm heterogeneity in determining location choice, we develop a theoretical model and analyze data on 3,644 Korean manufacturing multinationals operating in 87 countries between 1982 and 2006. The results of our conditional logit analysis indicate that not only host country characteristics but also firm heterogeneous factors such as productivity, labor intensity, and size have considerable influence on the decision of where to locate FDI.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권4호
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• pp.1866-1888
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• 2017

Efficient energy consumption in WSN is one of the key design issues for improving network stability period. In this paper, we propose a new Heterogeneity-aware Energy-efficient Clustering (HEC) technique which considers two types of heterogeneity - network lifetime and of sensor nodes. Selection of cluster head nodes is done based on the three network lifetime phases: only advanced nodes are allowed to become cluster heads in the initial phase; in the second active phase all nodes are allowed to participate in cluster head selection process with equal probability, and in the last dying out phase, clustering is relaxed by allowing direct transmission. Simulation-based performance analysis of the proposed technique as compared to other relevant techniques shows that HEC achieves longer stable region, improved throughput, and better energy dissipation owing to judicious consumption of additional energy of advanced nodes. On an average, the improvement observed for stability period over LEACH, SEP, FAIR and HEC- with SEP protocols is around 65%, 30%, 15% and 17% respectively. Further, the scalability of proposed technique is tested by varying the field size and number of sensing nodes. The results obtained are found to be quite optimistic. The impact of energy heterogeneity has also been assessed and it is found to improve the stability period though only upto a certain extent.

• 한국산림과학회지
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• 제97권2호
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• pp.165-170
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• 2008

Litterfall has been recognized an important part of the forest ecosystem production, playing a major pathway in energy flow and nutrient cycling through the ecosystem. This study was carried out to examine the quantity and components, temporal variation, and spatial heterogeneity of the litterfall in the mixed broadleaved-Korean pine forest. The data were collected from the 9ha permanent experimental plot, of which on the center area, i.e. $150m{\times}150m$, the total number of 319 circular litterfall traps with the size of $0.5m^2$ were established to collect falling litterfall. The results showed that the annual amount of litterfall was totalized 3,033.7 kg/ha, occupying broad-leaves of 39.3%, conifer-leaves of 29.5%, others of 18.5%, branches of 10.4%, and seeds of 2.3%. The peak point of the litterfall production was made at the end of September, proportionating 32.2% of total amount. The analysis of semivariogram revealed the existence of high spatial heterogeneity, calculated the scale of spatial heterogeneity ranged from 11.6 m to 29.1 m. The result of proportion (C/[Co+C]) showed that spatial heterogeneity of autocorrelation in total spatial heterogeneity were from 97.0% to 100%. The relatively heavy branches and others had significant differences in litterfall production between the areas of canopy gap and closed canopy in the 95% probability level, but the other components did not show statistical differences.

• The Journal of Asian Finance, Economics and Business
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• 제7권4호
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• pp.29-39
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• 2020

The purpose of this study is to investigate the determinants of blockholder presence in the Korean stock market. This study examines previous theories and studies, points that previous studies did not examine, and proposes two hypotheses. To verify two hypotheses, fundamental data were collected from firms listed on Korea Exchange from 2005 to 2017. As explanatory variables, we use the factors and characteristics of the firms used in the previous studies. Logistic regression analysis was conducted to test the determinants of blockholder presence. We find that firm size is the most distinctive factor determining the presence of blockholder, and firm idiosyncratic risk is the most similar factor determining the existence of each blockholder. Tobin Q shows significant value in family and government, and R&D intensity appears to be a negative related to the presence of blockholder in financial institutions. We also find that the determinant of blockholder presence differs from the mechanisms that govern each individual blockholder type when all blockholders grouped together. This suggests that there is blockholder heterogeneity within Korea listing firms. Our findings contribute to investors and policy makers who interested in the determinants of the presence of blockholder and blockhoder heterogeneity in Korea stock market.

• 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.

• BMB Reports
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• 제28권1호
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• pp.46-50
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• 1995

Three kinds of mouse tumor necrosis factor (TNF), which have molecular weights of 35 kDa, 45 kDa, and 18 kDa on SDS-PAGE, were partially purified from serum-free culture supernatants of mouse peritoneal macrophages induced with lipopolysaccharide. Analysis of the native molecular weights by gel filtration indicated that the 18 kDa and 45 kDa TNFs aggregate into 50 kDa and 100 kDa molecules, respectively, while the 35 kDa TNF is contained in high molecular weight aggregates of approximately 200 kDa. The three kinds of cytotoxic factors all elicited tumor reducing responses.

• 디지털융복합연구
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• 제16권2호
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• pp.151-156
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• 2018

이 연구의 목적은 TPM을 대한 주제로 작성된 논문 중 검증이 가능한 18편의 논문을 대상으로 메타분석을 실시하는 것이다. 분석을 위해 5개의 가설을 설정하고 각 연구논문에서 제시한 t값을 투입하여 CMA로 메타분석을 실시하였다. 분석 결과 4개 가설에 있어서 I-square 값이 모두 75%이상인 것으로 나타나 이질성이 매우 큰 것으로 분석되었다. 따라서 모든 연구의 모집단 효과크기는 같다는 귀무가설은 기각되었다. 이질성의 원인은 분석에 사용된 개별연구의 응답자분포, 연구조건, 연구시기, 연구지역 등의 연구특성이 다르기 때문이다. 이러한 경우 효과크기의 차이를 분석하기 위해서는 연구특성별로 구분할 수 있는 개별연구들의 요약 통계량이 필요하다. 그러나 개별연구들에서는 효과차이를 분류할 수 있도록 하는 요약통계량이 제시되지 않아서 이질성의 원인에 대한 분석을 실시할 수 없는 것이 아쉬운 점이라 하겠다.