• Advances in environmental research
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• v.1 no.1
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• pp.15-35
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• 2012

Mercury (Hg) is a global environmental pollutant that has been the cause of many public concerns. One particular concern about Hg in aquatic systems is its trophic transfer and biomagnification in food chains. For example, the Hg concentration increases with the increase of food chain level. Fish at the top of food chain can accumulate high concentrations of Hg (especially the toxic form, methylmercury, MeHg), which is then transferred to humans through seafood consumption. Various biological and physiochemical conditions can significantly affect the bioaccumulation of Hg-including both its inorganic (Hg(II)) and organic (MeHg) forms-in fish. There have been numerous measurements of Hg concentrations in marine and freshwater fish worldwide. Many of these studies have attempted to identify the processes leading to variations of Hg concentrations in fish species from different habitats. The development of a biokinetic model over the past decade has helped improve our understanding of the mechanisms underlying the bioaccumulation processes of Hg in aquatic animals. In this review, I will discuss how the biokinetic modeling approach can be used to reveal the interesting biodynamics of Hg in fish, such as the trophic transfer and exposure route of Hg(II) and MeHg, as well as growth enrichment (the increases in Hg concentration with fish size) and biomass dilution (the decreases in Hg concentration with increasing phytoplankton biomass). I will also discuss the relevance of studying the subcellular fates of Hg to predict the Hg bioaccessibility and detoxification in fish. Future challenges will be to understand the inter- and intra-species differences in Hg accumulation and the management/mitigation of Hg pollution in both marine and freshwater fish based on our knowledge of Hg biodynamics.

• Journal of the Korea Society of Computer and Information
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• v.25 no.2
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• pp.231-239
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• 2020

Cryptocurrency, represented by Bitcoin, initially received little public attention, but recently raised global cryptocurrency investments with recognition of future value. The academic interest in cryptocurrency lies elsewhere. This is because the future value of cryptocurrency is likely to be highly applicable to the technology underlying cryptocurrency. The technology is the blockchain. The purpose of this study is to find out what factors influence logistics companies to adopt blockchain technology. Based on the TOE frame, this study presented expected profit, organizational readiness, technology compatibility, and competitive pressure as factors of adoption of blockchain technology. And the effects of these factors on the adoption intention of logistics companies were analyzed empirically. A survey was conducted on Korean logistics companies. Analysis of the collected data showed that expected profit, organizational readiness, technology compatibility, and competitive pressures influence the intention to adopt blockchain technology. Among them, however, expected profit and organizational readiness were found to have the greatest influence on adoption intention.

• Journal of Microbiology and Biotechnology
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• v.24 no.3
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• pp.313-323
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• 2014

Significant alteration in the microbial community can occur across reclamation areas suffering subsidence from mining. A reclamation site undergoing fertilization practices and an adjacent coal-excavated subsidence site (sites A and B, respectively) were examined to characterize the bacterial diversity using 454 high-throughput 16S rDNA sequencing. The dominant taxonomic groups in both the sites were Proteobacteria, Acidobacteria, Bacteroidetes, Betaproteobacteria, Actinobacteria, Gammaproteobacteria, Alphaproteobacteria, Deltaproteobacteria, Chloroflexi, and Firmicutes. However, the bacterial communities' abundance, diversity, and composition differed significantly between the sites. Site A presented higher bacterial diversity and more complex community structures than site B. The majority of sequences related to Proteobacteria, Gemmatimonadetes, Chloroflexi, Nitrospirae, Firmicutes, Betaproteobacteria, Deltaproteobacteria, and Anaerolineae were from site A; whereas those related to Actinobacteria, Planctomycetes, Bacteroidetes, Verrucomicrobia, Gammaproteobacteria, Nitriliruptoria, Alphaproteobacteria, and Phycisphaerae originated from site B. The distribution of some bacterial groups and subgroups in the two sites correlated with soil properties and vegetation due to reclamation practice. Site A exhibited enriched bacterial community, soil organic matter (SOM), and total nitrogen (TN), suggesting the presence of relatively diverse microorganisms. SOM and TN were important factors shaping the underlying microbial communities. Furthermore, the specific plant functional group (legumes) was also an important factor influencing soil microbial community composition. Thus, the effectiveness of 454 pyrosequencing in analyzing soil bacterial diversity was validated and an association between land ecological system restoration, mostly mediated by microbial communities, and an improvement in soil properties in coal-mining reclamation areas was suggested.

• Journal of Korean Society of Transportation
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• v.27 no.5
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• pp.135-144
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• 2009

This study estimates the expected number of accidents in Kyungbuk Province to capitalize on experience gained from four years of accident history using the Empirical Bayes (EB) Method. The number of accidents of each site in Kyungbuk Province is recalculated using the Equivalent Property Damage Only (EPDO) method to reflect the severities of the accidents. A cluster analysis is performed to determine similar sites and a unique Safety Performance Function (SPF) is established for each site. The overdispersion parameter is built to correct the difference between the actual number of accidents and the underlying probability distribution. To adjust for varying traffic characteristics of each site, a relative weight is applied and eventually estimates the expected number of accidents. The results show that the highest accident sites are Kimcheon, Youngcheon, and Chilgok, but on the other hand the lowest is Gunwi.

• ALGAE
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• v.33 no.4
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• pp.305-318
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• 2018

In Trachelomonas hispida, the adult envelope that surrounds the monad is oval in shape and covered with spines. Development of the lorica is an interesting, but poorly known phenomenon. We observed in detail the formation of spineless envelopes of T. hispida using light microscopy and scanning electron microscopy. The results showed that young cells formed delicate and net-like envelopes. The structure changed with age, and mature specimens had solid, thick loricae with small pores. As the loricae aged, they changed their shape, and rope-like fibres from the external layer started to unwind, progressing from the apical pore, exposing the underlying net-like structure. X-ray spectrometry showed that Fe was the major mineral component in young and mature loricae, whereas old loricae did not contain Fe salts, although they did contain a high number of Mn compounds. We also noticed a different pattern of mineralization process in the envelopes. Apart from the even distribution of mineral deposition over the entire lorica, we observed that it started from the apical pore and ended at the posterior end. There was considerable morphological variation in envelope shape and ornamentation, which had collars and folds around the apical pore and process at the posterior end. This suggested that many varieties of T. hispida should be taxonomically reappraised. We also discuss a hypothetical role for the spines on lorica surfaces in aquatic ecosystems.

• Korean Journal of Clinical Pharmacy
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• v.31 no.3
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• pp.231-236
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• 2021

Background: Sarcopenia is a skeletal muscle disorder that involves the loss of muscle mass and function. Handgrip strength (HGS) is the most commonly used tool to assess muscle strength to diagnose sarcopenia. HGS is also associated with various diseases and health outcomes. Thus, we aimed this study to examine the HGS status in Korean adults and relevant factors of HGS. Methods: Data was obtained from the 7th Korea National Health and Nutrition Examination Survey (KNHANES), a population-based nationwide survey. The estimated mean value of HGS was calculated in each age group. The mean HGS in men and women aged over 40 was compared according to the household income level, lifestyle factors, and comorbidities. Results: A total of 16,708 participants were included in this study. The mean HGS showed a maximum value in the 30s for both men and women, and then tended to decrease with increasing age. When analyzed for people aged 40 or older, the mean HGS was significantly higher in the current or past smoker, drinker, and aerobic exercise groups in both men and women. The mean HGS was lower in the group with comorbidities such as hypertension, dyslipidemia, type 2 diabetes, and bone diseases. Conclusion: Our study found that the mean HGS was significantly different between those with and without underlying chronic diseases. In groups with relevant comorbidities, close monitoring for the development of sarcopenia and taking preventive measures such as exercise and nutritional support may be recommended.

• The Korean Journal of Applied Statistics
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• v.34 no.6
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• pp.863-874
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• 2021

In this paper, we propose a post-selection inference procedure for the fused lasso signal approximator (FLSA). The FLSA finds underlying sparse piecewise constant mean structure by applying total variation (TV) semi-norm as a penalty term. However, it is widely known that this convex relaxation can cause asymptotic inconsistency in change points detection. As a result, there can remain false change points even though we try to find the best subset of change points via a tuning procedure. To remove these false change points, we propose a post-selection inference for the FLSA. The proposed procedure applies a permutation test based on CUSUM statistic. Our post-selection inference procedure is an extension of the permutation test of Antoch and Hušková (2001) which deals with single change point problems, to multiple change points detection problems in combination with the FLSA. Numerical study results show that the proposed procedure is better than naïve z-tests and tests based on the limiting distribution of CUSUM statistics.

• Korean Journal of Clinical Laboratory Science
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• v.50 no.4
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• pp.484-491
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• 2018

Primer $Sj{\ddot{o}}gren's$ Syndrome (pSS) is an autoimmune/inflammatory illness. The platelet indices (PIs) indicate the inflammatory response and activity/severity of many diseases. A vitamin D deficiency is accompanied by the increased tendency of autoimmune diseases. This study investigated whether the vitamin D levels are related to the altered platelet indices in pSS. A total of 261 individuals were included in this analytical cross-sectional study. The laboratory data of pSS patients were evaluated and the relationship between the PIs and vitamin D status was examined. According to these findings, in patients with pSS, the vitamin D levels were lower than the healthy control group (P<0.05). The vitamin D levels were negatively associated with PDW (P=0.012), but positively correlated with PCT (P<0.001). The cut-off point was obtained with receiver operating characteristics (ROC) curves for PDW: 12.53 (AUC 0.921, sensitivity 90%, specificity 85%), for PCT; 0.29 (AUC 0.660, sensitivity 68%, specificity 55%). In multivariate linear regression analysis, the most significant parameters for the effects of PDW are the following: vitamin D (${\beta}=-0.373$; t=-2.626; sig.=0.013) and plateletcrit (${\beta}=-0.308$; t=-2.13; sig.=0.040). A vitamin D deficiency may be accompanied by changes in PIs in pSS. A higher PDW and lower PCT supports the underlying inflammation, which may be vitamin D related useful parameters to consider in approaching to pSS.

• Journal of Dental Anesthesia and Pain Medicine
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• v.21 no.3
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• pp.237-244
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• 2021

Background: This study aimed to analyze Twitter users' emotional tendencies regarding oral surgery procedures before and after the coronavirus disease 2019 (COVID-19) pandemic worldwide. Methods: Tweets posted in English before and after the COVID-19 pandemic were included in the study. Popular tweets in 2019 were searched using the keywords "tooth removal", "tooth extraction", "dental pain", "wisdom tooth", "wisdom teeth", "oral surgery", "oral surgeon", and "OMFS". In 2020, another search was conducted by adding the words "COVID" and "corona" to the abovementioned keywords. Emotions underlying the tweets were analyzed using CrystalFeel - Multidimensional Emotion Analysis. In this analysis, we focused on four emotions: fear, anger, sadness, and joy. Results: A total of 1240 tweets, which were posted before and after the COVID-19 pandemic, were analyzed. There was a statistically significant difference between the emotions' distribution before and after the pandemic (p < 0.001). While the sense of joy decreased after the pandemic, anger and fear increased. There was a statistically significant difference between the emotional valence distributions before and after the pandemic (p < 0.001). While a negative emotion intensity was noted in 52.9% of the messages before the pandemic, it was observed in 74.3% of the messages after the pandemic. A positive emotional intensity was observed in 29.8% of the messages before the pandemic, but was seen in 10.7% of the messages after the pandemic. Conclusion: Infectious diseases, such as COVID-19, may lead to mental, emotional, and behavioral changes in people. Unpredictability, uncertainty, disease severity, misinformation, and social isolation may further increase dental anxiety and fear among people.

• The Korean Journal of Physiology and Pharmacology
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• v.25 no.2
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• pp.139-146
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• 2021

Mitochondrial NADP+-dependent isocitrate dehydrogenase 2 (IDH2) produces NADPH, which is known to inhibit mitochondrial oxidative stress. Ureteral obstruction induces kidney inflammation and fibrosis via oxidative stress. Here, we investigated the role and underlying mechanism of IDH2 in unilateral ureteral obstruction (UUO)-induced kidney inflammation using IDH2 gene deleted mice (IDH2-/-). Eight- to 10-week-old female IDH2-/- mice and wild type (IDH2+/+) littermates were subjected to UUO and kidneys were harvested 5 days after UUO. IDH2 was not detected in the kidneys of IDH2-/- mice, while UUO decreased IDH2 in IDH2+/+ mice. UUO increased the expressions of markers of oxidative stress in both IDH2+/+ and IDH2-/- mice, and these changes were greater in IDH2-/- mice compared to IDH2+/+ mice. Bone marrow-derived macrophages of IDH2-/- mice showed a more migrating phenotype with greater ruffle formation and Rac1 distribution than that of IDH2+/+ mice. Correspondently, UUO-induced infiltration of monocytes/macrophages was greater in IDH2-/- mice compared to IDH2+/+ mice. Taken together, these data demonstrate that IDH2 plays a protective role against UUO-induced inflammation through inhibition of oxidative stress and macrophage infiltration.