• Journal of Periodontal and Implant Science
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• v.52 no.3
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• pp.183-193
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• 2022

Purpose: We retrospectively analysed patients' dental and periodontal status according to the presence of non-communicable diseases (NCDs) and the effects of NCDs on periodontal treatment outcomes. Factors influencing disease recurrence were investigated using decision tree analysis. Methods: We analysed the records of patients who visited the Department of Periodontology, Pusan National University Dental Hospital from June 2014 to October 2019. As baseline subjects, 1,362 patients with periodontitis and who underwent full-mouth periodontal examinations before periodontal treatment were selected. Among them, 321 patients who underwent periodontal examinations after the completion of periodontal treatment and 143 who continued to participate in regular maintenance were followed-up. Results: Forty-three percent of patients had a NCD. Patients without NCDs had more residual teeth and lower sum of the number of total decayed, missing, filled teeths (DMFT) scores. There was no difference in periodontal status according to NCD status. Patients with a NCD showed significant changes in the plaque index after periodontal treatment. The decision tree model analysis demonstrated that osteoporosis affected the recurrence of periodontitis. Conclusions: The number of residual teeth and DMFT index differed according to the presence of NCDs. Patients with osteoporosis require particular attention to prevent periodontitis recurrence.

• Women's Health Nursing
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• v.28 no.3
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• pp.250-263
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• 2022

Purpose: The purpose of this study was to develop a webtoon education program on preventive self-management related to premature labor (PSM-PL) for women of childbearing age, to evaluate its effects, and to assess the usability of webtoon education for women of childbearing age. Methods: The study design was a stratified randomized trial with repeated measures. The participants were Korean women of childbearing age (between the ages of 19 and 49 years), with 49 participants each. The preventive health management self-efficacy related to premature labor (PHMSE-PL) scale, the preventive self-management knowledge related to premature labor (PSMK-PL) scale, and usability of webtoon education were assessed. The intervention group read six episodes of the PSM-PL webtoon within 2 days after clicking an online link. The control group did not receive anything but was given the webtoon after the last measurement. To test the effect of the repeatedly measured variables, a generalized estimating equation model was used. Results: The experimental group had statistically significantly greater increases in PHMSE-PL and PSMK-PL scores from baseline to immediately after and 2 weeks later than the control group. The average score for usability of webtoon education was high (4.52; standard deviation, 0.62) on a scale of 1-5. Conclusion: This webtoon education program on PSM-PL was a feasible and acceptable program that increased self-efficacy and knowledge of preventive health management of premature labor in women of childbearing age. Future studies that adopt a webtoon format can be beneficial for childbearing women with other risk factors.

• The Journal of Internal Korean Medicine
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• v.42 no.2
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• pp.175-183
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• 2021

Diabetes mellitus, commonly known as diabetes, comprises a group of metabolic disorders characterized by a high blood sugar level over a prolonged period of time. Diabetes is classified into type 1 diabetes and type 2 diabetes, and the incidence and prevalence of diabetes, mostly type 2, have increased remarkably in recent decades. A diagnosis of type 2 diabetes is greatly influenced by heredity, and it is important to prevent diabetes in people with a family history by improving lifestyle and environmental factors. Controlling overeating, obesity, lack of exercise, and stress is effective to prevent diabetes. The patient in this case report had impaired fasting glucose and mild hyperlipidemia. The patient experienced improvements in these sequelae after the administration of herbal medicine (Yangkyuksanwha-tang) for 12 weeks and the implementation of a plant-based diet. The complete blood count, XXXX, fasting blood sugar, HbA1c, insulin, and C-peptide levels were measured, and the Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) and HOMA-β were calculated according to the FBS and fasting insulin levels. Total cholesterol, triglyceride, FBS, and HbA1c levels all decreased after 12 weeks compared with baseline measures. There was no change in the insulin secretory ability; the C-peptide level did not change as a result of β-cell function; and the HOMA-β level reflected an improved insulin secretory ability.

• The Journal of the Acoustical Society of Korea
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• v.40 no.2
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• pp.176-182
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• 2021

This paper evaluates and compares the performance of the Deep Nerual Network (DNN)-based speech enhancement models according to various loss functions. We used a complex network that can consider the phase information of speech as a baseline model. As the loss function, we consider two types of basic loss functions; the Mean Squared Error (MSE) and the Scale-Invariant Source-to-Noise Ratio (SI-SNR), and two types of perceptual-based loss functions, including the Perceptual Metric for Speech Quality Evaluation (PMSQE) and the Log Mel Spectra (LMS). The performance comparison was performed through objective evaluation and listening tests with outputs obtained using various combinations of the loss functions. Test results show that when a perceptual-based loss function was combined with MSE or SI-SNR, the overall performance is improved, and the perceptual-based loss functions, even exhibiting lower objective scores showed better performance in the listening test.

• Journal of Positioning, Navigation, and Timing
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• v.10 no.4
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• pp.379-385
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• 2021

In order to synchronize a remote system time to the reference time like Coordinated Universal Time (UTC), it is required to compare the time difference between the two clocks. GNSS Precise Point Positioning (PPP) is one of the most general geodetic positioning methods and can be used for time and frequency transfer applications which require more precise time comparison performance than GNSS code. However, the PPP technique has a main drawback of day-boundary discontinuity which comes from the PPP model that the code measurements are applied to resolve the floating carrier-phase ambiguities. The Integer PPP (IPPP) technique is one of the methods which has been studied to compensate the day-boundary discontinuities exited in the conventional PPP. In this paper, we investigate the time and frequency capabilities of PPP and IPPP by using the measurement data obtained from two time transfer receivers which are closely located and using common reference 1 Pulse Per Second (PPS) and RF signals. From the experiment, it is investigated that the IPPP method can effectively compensate the day-boundary discontinuities without producing frequency offset. However, the PPP method can generating frequency offset which can severely degrade the time comparison performance with long-term period data.

• Journal of Ecology and Environment
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• v.46 no.4
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• pp.292-303
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• 2022

Background: Climate change significantly influences the geographical distribution of plant species worldwide. Selecting indicator species allows for better-informed and more effective ecosystem management in response to climate change. The Korean Peninsula is the northernmost distribution zone of warm temperate evergreen broad-leaved (WTEB) species in Northeast Asia. Considering the ecological value of these species, we evaluated the current distribution range and future suitable habitat for 13 WTEB tree species designated as climate-sensitive biological indicator species. Results: Up-to-date and accurate WTEB species distribution maps were constructed using herbarium specimens and citizen science data from the Korea Biodiversity Observation Network. Current northern limits for several species have shifted to higher latitudes compared to previous records. For example, the northern latitude limit for Stauntonia hexaphylla is higher (37° 02' N, Deokjeokdo archipelago) than that reported previously (36° 13' N). The minimum temperature of the coldest month (Bio6) is the major factor influencing species distribution. Under future climate change scenarios, suitable habitats are predicted to expand toward higher latitudes inland and along the western coastal areas. Conclusions: Our results support the suitability of WTEB trees as significant biological indicators of species' responses to warming. The findings also suggest the need for consistent monitoring of species distribution shifts. This study provides an important baseline dataset for future monitoring and management of indicator species' responses to changing climate conditions in South Korea.

• Composites Research
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• v.35 no.5
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• pp.340-346
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• 2022

In this study, an optimal structural design of composite helicopter blades is performed using the genetic algorithm-based optimizer PSGA (Particle Swarm assisted Genetic Algorithm). The blade sections consist of the skin, spar, form, and balancing weight. The sectional geometries are generated using the B-spline curves while an opensource code Gmsh is used to discretize each material domain which is then analyzed by a finite element sectional analysis program Ksec2d. The HART II blade formed based on either C- or D-spar configuration is exploited to verify the cross-sectional design framework. A numerical simulation shows that each spar model reduces the blade mass by 7.39% and 6.65%, respectively, as compared with the baseline HART II blade case, while the shear center locations being remain close (within 5% chord) to the quarter chord line for both cases. The effectiveness of the present optimal structural design framework is demonstrated, which can readily be applied for the structural design of composite helicopter blades.

• Journal of The Korean Society of Clinical Toxicology
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• v.20 no.2
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• pp.51-57
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• 2022

Purpose: Despite previous studies reporting the development of rhabdomyolysis (RM), this affliction tends to be neglected as an envenomation sign in South Korea. The current retrospective study investigates the prevalence and prognosis of RM after a snakebite. We further searched for predictors of snakebite-induced RM, which can be observed at presentation. Methods: This study included 231 patients who presented to the ED within 24 hours after a snakebite. The patients were classified according to the severity of RM, and the data, comprising baseline characteristics and clinical course including the level of creatine kinase (CK), were collected and compared according to the severity of RM. Results: The prevalence of RM and severe RM were determined to be 39% and 18.5%, respectively. Compared to the group without RM or with mild RM, the group with severe RM had a higher grade of local swelling, a higher frequency of acute kidney injury and neurotoxicity, and a greater need for renal replacement therapy and vasopressor administration. However, the incidence of acute renal injury in the RM group was 7.7%, with two patients needing renal replacement therapy. No mortalities were reported at discharge. Results of the multinomial logistic regression model revealed that the WBC levels are significantly associated with the risk of severe RM. Conclusion: RM should be considered the primary clinical sign of snake envenomation in South Korea, although it does not seem to worsen the clinical course. In particular, physicians should pay attention to patients who present with leukocytosis after a snakebite, which indicates the risk of developing RM, regardless of the CK level at presentation.

• Geomechanics and Engineering
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• v.30 no.6
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• pp.565-577
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• 2022

In this study, a series of three-dimensional numerical parametric study was conducted to investigate deformation mechanisms of an existing box culvert due to an adjacent multi-propped basement excavation in clays. Field measurements from an excavation case history are first used to calibrate a baseline Hardening Soil Small Strain (HS-small) model, which is subsequently adopted for parametric study. Results indicate that the basement-box culvert interaction along the basement centerline can be considered as a plane strain condition when the length of excavation (L) reaches 14 H_e (i.e., final excavation depth). If a plane strain condition (i.e., L/H_e=12.0) is assumed for analyzing the basement-box culvert interaction of a short excavation (i.e., L/H_e=2.0), the maximum settlement and horizontal movement of the box culvert are overestimated significantly by up to 15.7 and 5.1 times, respectively. It is also found that the deformation of box culvert can be greatly affected by the basement excavation if the distance between the box culvert and retaining wall is less than 1.5 H_e. The induced deformation in the box culvert can be dramatically reduced by improving the ground inside the excavation or implementing other precautionary measures. For example, by adding jet grouting columns within the basement and installing an isolation wall behind the retaining structures, the maximum settlements of box culvert are shown to reduce by 37.2% and 13.4%, respectively.

• Clean Technology
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• v.29 no.1
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• pp.53-58
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• 2023

This study shows the summary of the economic performance of excess electricity conversion to hydrogen as well as methane and returned conversion to electricity using a fuel cell. The methane production process has been examined in a previous study. Here, this study focuses on the conversion of methane to electricity. As a part of this study, capital expenditure (CAPEX) is estimated under various sized plants (0.3, 3, 9, and 30 MW). The study shows a method for economic optimization of electricity generation using a fuel cell. The CAPEX and operating expenditure (OPEX) as well as the feed cost are used to calculate the discounted cash flow. Then the levelized cost of returned electricity (LCORE) is estimated from the discounted cash flow. This study found the LCORE value was ¢10.2/kWh electricity when a 9 MW electricity generating fuel cell was used. A methane production plant size of 1,500 Nm³/hr, a methane production cost of $11.47/mcf, a storage cost of $1/mcf, and a fuel cell efficiency of 54% were used as a baseline. A sensitivity analysis was performed by varying the storage cost, fuel cell efficiency, and excess electricity cost by ±20%, and fuel cell efficiency was found as the most dominating parameter in terms of the LCORE sensitivity. Therefore, for the best cost-performance, fuel cell manufacturing and efficiency need to be carefully evaluated. This study provides a general guideline for cost performance comparison with LCORE.