• Journal of Periodontal and Implant Science
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• v.48 no.6
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• pp.347-359
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• 2018

Purpose: Periodontitis and rheumatoid arthritis (RA) share a similar inflammatory pathogenesis. Porphyromonas gingivalis (Pg) can induce anticyclic-citrullinated peptide autoantibodies (anti-CCP antibodies), a key factor in the development of RA. This study aimed at evaluating the relationships between the 2 diseases and identifying the clinical implications thereof, with a focus on periodontal pathogens in Korean adults. Methods: A total of 260 RA patients and 86 age- and sex-matched control patients without arthritis were enrolled in this prospective cross-sectional study. Periodontal indices and the prevalence and amount of periodontal pathogens were compared between the groups. Correlations between periodontal and RA indices were examined, as were correlations between 9 periodontal pathogens and RA indices. Results: The RA group had significantly higher values than the control group for all investigated periodontal indices (P<0.05) except the number of teeth. The gingival index (GI) was correlated with the disease activity score 28 (DAS28) (r=0.125, P=0.049), RA disease duration (r=0.253, P<0.001), erythrocyte sedimentation rate (ESR) (r=0.162, P=0.010), and anti-CCP antibody titer (r=0.205, P=0.004). Probing pocket depth (PPD) was correlated with ESR (r=0.139, P=0.027) and anti-Pg antibody titer (r=0.203, P=0.001). Bleeding on probing (BOP) was correlated with DAS28 (r=0.137, P=0.030), RA disease duration (r=0.202, P=0.001), ESR (r=0.136, P=0.030), anti-Pg antibody titer (r=0.177, P=0.005), and anti-CCP antibody titer (r=0.188, P=0.007). Clinical attachment level (CAL) and periodontitis severity were correlated with anti-Pg antibody titer (the former r=0.201, P=0.002; the latter r=0.175, P=0.006). The quantity of Pg was positively correlated with the serum anti-Pg antibody titer (r=0.148, P=0.020). Conclusions: The GI, BOP, and PPD showed positive relationships with several RA indices. The anti-Pg antibody titer had positive relationships with PPD, BOP, CAL, and periodontitis severity. Thus, increasing values of periodontal indices could be used as a risk indicator of disease development in RA patients, and an increasing anti-Pg antibody titer could be considered as a warning sign in RA patients suffering with periodontitis.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.30 no.6
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• pp.253-262
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• 2018

Oscillating Water Column (OWC) Wave Energy Converters (WEC) harness electricity through a Power-Take-Off (PTO) system from the induced-airflow by seawater oscillating inside a chamber. In general, an air chamber with a relatively small cross-sectional area is required compared to seawater chamber to obtain high-velocity air in the PTO system, and in order to simulate an accurate air flow rate in the air chamber, a three-dimensional study is required. In this study, the dynamic response of OWC-WEC that is equipped with the channel of seawater exchange for the case of irregular waves has been numerically studied. The open source CFD software, OLAFLOW for the simulation of wave dynamics to the openFOAM and FOAM-extend communities, was used to simulate the interaction between the device and irregular waves. Based on the numerical simulation results, we discussed the fluctuation characteristics of three dimensional air flow in the air-chamber, wave deformation around the structure and the seawater flow inside the channel of seawater exchange. The numerical results the maximum air flow velocity in the air-chamber increases as the Ursell value of the significant wave increases, and the velocity of airflow flowing out from the inside of air chamber to the outside is greater than the speed of flowing into the air chamber from the outside.

• The Journal of the Korean dental association
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• v.57 no.4
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• pp.213-220
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• 2019

Purpose: The aim of this study was to evaluate the red fluorescence characteristics of bacterial dental deposits assessed by quantitative light-induced fluorescence (QLF) technology and confirm whether the red fluorescence can distinguish and evaluate quantitatively accumulation of bacterial dental deposits. Methods: This retrospective cross-sectional study used QLF images captured at a dental clinic from January to December 2016. In each QLF image, a skilled examiner selected one region where the presence of deposits was suspected. Then, the regions were classified into three groups of not detectable deposits(ND), half detectable deposits (HD), and full detectable deposits (FD) by two examiners according to classification criteria. Only those images where the regions of bacterial dental deposits were classified identically by all examiners were used for analysis. The mean red fluorescence intensity (RFI) was defined as the mean value of R/G for all pixels in the regions. The RFI was compared between groups using Welch's ANOVA test, and the Spearman correlation was calculated to assess the association between RFI and accumulation of deposits. Results: In this study, 351 images among the collected images of 605 subjects were finally selected. The mean age of subjects was about 44 years. The R/G values of the ND, HD and FD were 0.73, 1.26 and 1.83 respectively. There were significant differences between all groups (p<0.001), and strong positive correlation was identified between the R/G value and the accumulation of deposits (r = 0.90, p<0.001). Conclusion: The intensity of red fluorescence as observed in the QLF images correlated well with the accumulation maturation of the deposits, which indicates that the QLF technology can be used to evaluate the status of oral hygiene.

• Clinical and Experimental Otorhinolaryngology
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• v.11 no.4
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• pp.275-280
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• 2018

Objectives. Middle vault deviation has a significant effect on the aesthetic and functional aspects of the nose, and its management continues to be a challenge. Spreader graft and its modification techniques have been focused, but there has been scarce consideration for removing surplus portion and balancing the upper lateral cartilage (ULC). This study aimed to report the newly invented triangular-shaped resection technique ("triangular resection") of the ULC and to evaluate its efficacy for correcting middle vault deviation. Methods. A retrospective study included 17 consecutive patients who presented with middle vault deviation and underwent septorhinoplasty by using triangular resection at a tertiary academic hospital from February 2014 and March 2016. Their outcomes were evaluated pre- and postoperatively including medical photographs, acoustic rhinometry and subjective nasal obstruction using a 7-point Likert scale. Results. The immediate outcomes were evaluated around 1 month after surgery, and long-term outcomes were available in 12 patients; the mean follow-up period was 9.1 months. Nasal tip deviation angle was reduced from $5.66^{\circ}$ to $2.37^{\circ}$ immediately (P<0.001). Middle vault deviation also improved from $169.50^{\circ}$ to $177.24^{\circ}$ (P<0.001). Long-term results were $2.49^{\circ}$ (P=0.015) for nasal tip deviation and $178.68^{\circ}$ (P=0.002) for middle vault deviation. The aesthetic outcome involved a complete correction in eight patients (47.1%), a minimally visible deviation in seven patients (41.2%) and a remaining residual deviation in two patients (11.8%). Pre- and postoperative minimal cross-sectional areas (summation of the right and left sides) were 0.86 and 1.07, respectively (P=0.021). Fifteen patients answered about their nasal obstruction symptoms and the median symptom score had alleviated from 6.0 to 3.0 (P=0.004). Conclusion. Triangular resection of the ULC is a simple and effective method for correcting middle vault deviation and balancing the ULCs without complications as internal nasal valve narrowing.

• Yonsei Medical Journal
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• v.59 no.9
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• pp.1026-1033
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• 2018

Purpose: Consistent evidence indicates that cervical and breast cancer screening rates are low among socioeconomically deprived women. This study aimed to assess trends in cervical and breast cancer screening rates and to analyze socioeconomic inequalities among Korean women from 2005 to 2015. Materials and Methods: Data from the Korean National Cancer Screening Survey, an annual nationwide cross-sectional survey, were utilized. A total of 19910 women were finally included for analysis. Inequalities in education and household income status were estimated by slope index of inequality (SII) and relative index of inequality (RII), along with calculation of annual percent changes (APCs), to show trends in cancer screening rates. Results: Cervical and breast cancer screening rates increased from 54.8% in 2005 to 65.6% in 2015 and from 37.6% in 2005 to 61.2% in 2015, respectively. APCs in breast cancer screening rates were significant among women with higher levels of household income and education status. Inequalities by household income in cervical cancer screening uptake were observed with a pooled SII estimate of 10.6% (95% CI: 8.1 to 13.2) and RII of 1.4 (95% CI: 1.3 to 1.6). Income inequalities in breast cancer screening were shown to gradually increase over time with a pooled SII of 5.9% (95% CI: 2.9 to 9.0) and RII of 1.2 (95% CI: 0.9 to 1.3). Educational inequalities appeared to diminish over the study period for both cervical and breast cancer screening. Conclusion: Our study identified significant inequalities among socioeconomically deprived women in cervical and breast cancer screening in Korea. Especially, income-related inequalities were greater than education-related inequalities, and these were constant from 2005 to 2015 for both cervical and breast cancer screening.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.31 no.3
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• pp.202-212
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• 2021

Objectives: The reproductive health of female workers has been extensively investigated in South Korea and other countries worldwide. However, few studies have discussed the reproductive health of male workers. In this study, we reviewed the recent literature that reports on the effects of occupational exposure on the reproductive health of male workers and the health of their children. Methods: In May 2020 we used the PubMed search engine to search the literature over the last 10 years and chose case-control, cohort, and cross-sectional studies and reviews. We selected epidemiological studies that investigated the association between pre-pregnant occupational exposure and the reproductive health of male workers and the health of their children. We excluded case reports, non-epidemiological studies (animal experiments, cellular-level experiments, and similar articles), and studies that described postnatal occupational exposure. Results: We eventually selected 23 studies. The studies that included exclusively male workers reported that those employed in the agricultural sector or those exposed to pesticides showed lower blood levels of reproductive hormones and a high risk of lympho-hematopoietic system cancer in their children. Male workers exposed to complex organic solvents and organic compounds showed a high risk of poor semen quality, increased time to pregnancy, decreased blood levels of reproductive hormones, and a high risk of lympho-hematopoietic system cancer in their children. Male workers employed in occupations that involved significant social contact, or in the leather and livestock industries, and in occupations with high levels of exposure to lead and organic solvents showed a high risk of malignancies, including lympho-hematopoietic system cancer, neuroblastoma, and central nervous system tumors in their children. Studies that investigated both male and female workers reported that children of male smelters showed a high risk of premature birth, and children of male workers exposed to metals showed a high risk of hypospadias and cryptorchidism. Children of male welders and workers employed in the glass, ceramic, and tile industries showed a high risk of premature birth. Conclusion: The findings of this study will serve as basic data for further research on male workers' reproductive health and provide a scientific basis for the development of strategies to protect the reproductive health of males employed in high-risk occupations. Moreover, the results of this study may provide guidelines to improve the understanding of and knowledge on male workers' reproductive health.

• Journal of the Korean Society of School Health
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• v.34 no.1
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• pp.22-32
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• 2021

Purpose: Discrimination experienced in the early stages of life among ethnic minority adolescents is known to affect depression and also adversely affect health throughout adulthood and old age. The purpose of this study was to identify whether discrimination experienced by ethnic minority adolescents and their mothers and depression among mothers affect depression in ethnic minority adolescents according to gender. Methods: This was a cross-sectional study using the data of 2018 National Multicultural Family Survey in Korea. The study sample comprised 2,446 ethnic minority adolescents aged 11~18 and their mothers. The data were analyzed using descriptive statistics, pearson correlation analysis, and ordinal logistic regression with SPSS/WIN 25.0 and STATA IC 16. Results: 18.4% of the adolescents (boys: 15.1%, girls: 20.5 %) felt sad or frustrated sometimes or more often for at least two weeks during the past year. Also, 8.3% of the adolescents and 29.6% of their mothers experienced discrimination during the past year. Boys were influenced more than girls by bullying at school (OR=5.17, 95% CI: 2.85~9.38), academic performance (very bad's OR=5.79, 95% CI: 1.54~21.63) and mother's depression (often's OR=2.31, 95% CI: 1.14~4.64). Girls were influenced more than boys by experience of discrimination (OR=2.72, 95% CI: 1.69~4.39). Conclusion: The findings showed that discrimination experienced by ethnic minority adolescents and their mothers in Korean society increases depression in ethnic minority adolescents and has different effects by gender. Therefore, a gender-specific and mother-inclusive intervention is recommended to prevent depression in ethnic minority adolescents.

• Journal of Korean Tunnelling and Underground Space Association
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• v.23 no.5
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• pp.359-370
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• 2021

Duct slabs, which are used to build ventilation facilities in underground spaces with transverse ventilation system, need to secure fire resistance according to longitudinal and heavy vehicle traffic of tunnels. This study measured the temperature change at the construction joint of the precast fireproof duct slab which integrates fire resistance material and duct slab under the RWS fire scenario. As a result, it was confirmed that if there is no reinforcement of the construction joint, damage will occur in concrete inside the construction joint, leading to damage to the fireproofing layer. On the other hand, when one side of the construction joint was reinforced with fireproofing materials, it showed more than three times the fire resistance performance compared to when there was no reinforcement. At this time, cross-sectional losses of concrete and fireproofing layer were shown in blocks without reinforcement, but no damage was seen in the reinforced blocks.

• Journal of Korean Neurosurgical Society
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• v.64 no.1
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• pp.100-109
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• 2021

Objective : Diffuse astrocytic tumour (DAT) is a diffuse infiltrative astrocytoma tumour accompanied by molecular parameters such as the presence or absence of isocitrate dehydrogenase (IDH) gene mutations. Ki-67 is a marker for DAT proliferation, while programmed death ligand 1 (PD-L1) indicates an immune evasion mechanism. This study aimed to analyze the correlation among mutant IDH1 R132H, Ki-67, and PD-L1 immunoexpression in the DAT. Methods : A cross-sectional study was carried out on 30 paraffin blocks of DAT cases. Paraffin block samples consist of grade II (n=14), grade III (n=8), and grade IV (n=8). In this study, the immunohistochemistry-staining of mutant IDH1 R132H, Ki-67, and PD-L1 were carried out to determine the frequency of DAT with IDH1 mutations. Results : Our study shown the frequency of IDH1 mutations in grade II 50.0% (7/14), grade III 37.5% (3/8), and grade IV 12.5% (1/8). Our study also showed a difference in Ki-67 and PD-L1 expression between each the degree of DAT histopathology (p=0.0001 and p=0.002, respectively). There was an association between both mutant IDH1 R132H, and Ki-67 with PD-L1 expression in DAT (p=0.0087 and p=0.0049, respectively). Conclusion : DAT with the mutant IDH1 is frequently observed in grade II and small number of grade III. The expression of wild type IDH1, Ki-67, and PD-L1 were found to be higher in high grade DAT (grade III and grade IV). There is a correlation between each of mutant IDH1 status and Ki-67 with PD-L1 expression in DAT.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.31 no.1
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• pp.32-36
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• 2021

This study was investigated in carbon diffusion behavior of laser-carburized TiZrN coating layer and the changes of mechanical properties. The carbon paste was deposited on TiZrN coatings, and the laser was irradiated to carburize into the coatings. The XRD peak corresponding to the (111) plane shifted to a lower angle after the carburization, showing the lattice expansion by doped carbon. The decreased grain size implied the compression by the grain boundary diffusion of carbon. The XPS spectra for the bonding states of carbon was analyzed that carbon was substitute to nitrogen atoms in TiZrN, as carbide, through the thermal energy of laser. In addition, the combination of sp2 and sp3 hybridized bonds represented the formation of an amorphous carbon. The cross-sectional TEM image and the inverse FFT of the TiZrN coating after carburizing were observed as the wavy shape, confirming the amorphous phase located in grain boundaries. After the carburization, the hardness increased from 34.57 GPa to 38.24 GPa, and the friction coefficient decreased by 83 %. In particular, the ratio of hardness and elastic modulus (H/E) which is used as an index of the elastic recovery, increased from 0.11 to 0.15 and the wear rate improved by 65 %.