• Journal of the Korean Geotechnical Society
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• 제36권12호
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• pp.77-86
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• 2020

In this study, the importance of implied strength correction for shallow depths at a region of moderate to low seismicity with primary focus on its effect upon site natural period and mean period of the ground motion is investigated. In addition to the most commonly used Modified Kondner-Zelasko (MKZ) model, this paper uses a quadratic/hyperbolic (GQ/H) model that can capture the stress - strain response at large strains as well as small strain stiffness dependence. A total of six site profiles by downhole tests are used and 1D site response analyses are performed using three input motions with contrasting mean periods. The difference between non-corrected and corrected analyses is conditional on the site period as well as mean ground motion period. The effect of periods is analyzed by correlating them with the effective peak ground acceleration, maximum shear strains and amplification factors. The comparative study reveals that the difference is more prominent in soft sites with long site periods. Insignificant differences are observed when soil profiles are subjected to ground motion with very short mean period.

• Economic and Environmental Geology
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• 제55권3호
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• pp.281-293
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• 2022

We examined degradation characteristics of lead based pigments(white lead, Red lead, Litharge) according to atmospheric environmet condition, for example atmospheric gas(CO₂, NO₂) and soluble salt. Painted samples not changed material compositions but were occured the color change(𝚫E 4~31) after exposed UV irradiation. All sample were not affected by CO₂ gas not only color but chemical composition. However, samples were remakably changed color exposed NO₂ gas and it was formed secondary product like as lead nitrate. Such as red lead and white lead samples' color difference were 𝚫E 2 and 𝚫 10 respectively and became dark, along with litharge became bright and color difference was 𝚫E 5 after react with NO₂ gas. It confirm that NO₂ was influential factor than CO₂ in the case of same concentration. Furthermore salt spray test was taken to figure out soluble salt influence in fine dust. The result showed noticeable color change and secondary product was formed on samples' surface. The glue film peeled off or hole, and color changed around the secondary products. After salt spray, XRD pattern showed decrease peak intensity and lower crystalinity. As a result of salt spray test, white lead was formed new product litharge and litharge was formed litharge and minium. According to the results, influential atmospheric factors for conservation of paint pigments were UV, NO₂, soluble salt, and litharge was most weakness throughout lead base pigments.

• Journal of Marine Bioscience and Biotechnology
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• 제13권2호
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• pp.76-85
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• 2021

Crassostrea gigas were fermented using L. brevis BJ20 to prepare fermented oyster extract (FO). The participants of this study were randomly assigned to FO and placebo (CON) groups. The FO group was given 1.0 g of FO supplementation and the CON group was given sucrose each day for eight weeks. The effects of FO supplementation on body composition, muscula r strength, and blood factors associated with muscle growth were assessed. The FO supplement was enriched with arginine (6,183.3 mg), phenylalanine (217.9 mg), leucine (122.6 mg), isoleucine (59.8 mg), valine (16.4 mg), and γ-amino butyric acid (GABA, 1,053.7 mg). The total fat was significantly decreased in the FO group compared with the CON group (p < 0.05). 60D/S Ext.T/Wo rk and 60D/S Flex.T/Work concomitantly with 60D/S Flex.PeakTQ/BW were significantly increase d by FO treatment compared to CON group (p < 0.05). However, posture stability was not significa ntly different between the groups. The levels of angiotensin-converting enzyme were significantly decreased within the FO group (p < 0.05). The FO group showed significantly decreased levels of tumor necrosis factor-α and increased levels of human growth hormone compared with the CON group (p < 0.01). The levels of insulin-like growth factor-1 increased (p < 0.01) in the FO group while that of creatine kinase and triglyceride decreased significantly compared with the CON group (p < 0.05). These results demonstrated that FO supplementation is effective in preventing sarcopenic obesity and maintaining and strengthening muscular function in elderly wom en. Hence, FO supplements can be used as functional ingredients for these benefits.

• Journal of the Korea institute for structural maintenance and inspection
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• 제26권4호
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• pp.20-29
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• 2022

The operational modal analysis (OMA) technique, which extracts the modal parameters of a structural system using ambient vibrations, has been actively developed as a field of structural health monitoring of cable-supported bridges. In this paper, the short and long-term modal parameters of a cable-stayed bridge were evaluated using the acceleration data obtained from the two ambient vibration tests (AVTs) and three years of continuous measurements. A total of 27 vertical modes and 1 lateral mode in the range 0.1 ~ 2.5 Hz were extracted from the high-resolution AVTs which were conducted in the 6th and 19th years after its completion. Existing OMA methods such as Peak-Picking (PP), Eigensystem Realization Algorithm with Data Correlation (ERADC), Frequency Domain Decomposition (FDD) and Time Domain Decomposition (TDD) were applied for modal parameters extraction, and it was confirmed that there was no significant difference between the applied methods. From the correlation analysis between long-term natural frequencies and environmental factors, it was confirmed that temperature change is the dominant factor influencing natural frequency fluctuations. It was revealed that the decreased natural frequencies of the bridge were not due to changes in structural performance and integrity, but to the environmental effects caused by the temperature difference between the two AVTs. In addition, when the TDD technique is applied, the accuracy of extracted mode shapes is improved by adding a proposed algorithm that normalizes the sequence so that the autocorrelations at zero lag equal 1.

• Journal of Conservation Science
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• 제36권6호
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• pp.494-504
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• 2020

Ten historic sites (denoted as A- J in this study) of a tomb were found during the construction of the east-west expressway in District 2 of Hyangnam, Hwaseong, which is implemented by the Gyeonggi-do headquarters of the Korea Land & Housing Corporation. Thetombswere first detected at siteH, and further investigations revealed various tombs from the Three Kingdoms period; artifacts such as gilt-bronze shoes and caps were excavated from wooden coffins in the tombs. The pottery examined in this study was the only pottery artifact excavated from the site. Its raw clay was soft and loose, reddish brown, and had quartz and feldspar particles of < 1 mm, which appeared to have been added as reinforcing agents. The firing temperature of the pottery was estimated to be under 800-870 ℃ as the mica remains and tridimite, which is the phase transition mineral of quartz, was not produced; a slight endothermic peak was also detected because of the hydration of sericite at 800 ℃. The condition of the artifact was severely weakened because of various factors, such as soil pressure from the stratum formed over the site and repeated freezing and thawing. The artifact could not be collected alone, and thus, surrounding soil that had attached to the artifact was also collected; the artifact was transported to the laboratory and conservation treatment was conducted in a safe and systematic manner.

• Journal of Korean Neurosurgical Society
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• 제66권3호
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• pp.332-339
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• 2023

Objective : The present study aimed to investigate the clinical characteristics of electrolyte imbalance in patients with moderate to severe traumatic brain injury (TBI) who underwent craniotomy and its influence on prognosis. Methods : A total of 156 patients with moderate to severe TBI were prospectively collected from June 2019 to June 2021. All patients underwent craniotomy and intracranial pressure (ICP) monitoring. We aimed to explore the clinical characteristics of electrolyte disturbance and to analyze the influence of electrolyte disturbance on prognosis. Results : A total of 156 patients with moderate and severe TBI were included. There were 57 cases of hypernatremia, accounting for 36.538%, with the average level of 155.788±7.686 mmol/L, which occurred 2.2±0.3 days after injury. There were 25 cases of hyponatremia, accounting for 16.026%, with the average level of 131.204±3.708 mmol/L, which occurred 10.2±3.3 days after injury. There were three cases of hyperkalemia, accounting for 1.923%, with the average level of 7.140±1.297 mmol/L, which occurred 5.3±0.2 days after injury. There were 75 cases of hypokalemia, accounting for 48.077%, with the average level of 3.071±0.302 mmol/L, which occurred 1.8±0.6 days after injury. There were 105 cases of hypocalcemia, accounting for 67.308%, with the average level of 1.846±0.104 mmol/L, which occurred 1.6±0.2 days after injury. There were 17 cases of hypermagnesemia, accounting for 10.897%, with the average level of 1.213±0.426 mmol/L, which occurred 1.8±0.5 days after injury. There were 99 cases of hypomagnesemia, accounting for 63.462%, with the average level of 0.652±0.061 mmol/L, which occurred 1.3±0.4 days after injury. Univariate regression analysis revealed that age, Glasgow coma scale (GCS) score at admission, pupil changes, ICP, hypernatremia, hypocalcemia, hypernatremia combined with hypocalcemia, epilepsy, cerebral infarction, severe hypoproteinemia were statistically abnormal (p<0.05), while gender, hyponatremia, potassium, magnesium, intracranial infection, pneumonia, allogeneic blood transfusion, hypertension, diabetes, abnormal liver function, and abnormal renal function were not statistically significant (p>0.05). After adjusting gender, age, GCS, pupil changes, ICP, epilepsy, cerebral infarction, severe hypoproteinemia, multivariate logistic regression analysis revealed that hypernatremia or hypocalcemia was not statistically significant, while hypernatremia combined with hypocalcemia was statistically significant (p<0.05). Conclusion : The incidence of hypocalcemia was the highest, followed by hypomagnesemia, hypokalemia, hypernatremia, hyponatremia and hypermagnesemia. Hypocalcemia, hypomagnesemia, and hypokalemia generally occurred in the early post-TBI period, hypernatremia occurred in the peak period of ICP, and hyponatremia mostly occurred in the late period after decreased ICP. Hypernatremia combined with hypocalcemia was associated with prognosis.

• Composites Research
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• 제21권5호
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• pp.23-30
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• 2008

Stab threats using sharp edged or pointed Instruments could be easily encountered by police officers or soldiers. In this study, the shear thickening fluids (STF) was impregnated into Kevlar fabrics to improve the stab protection and the resistance of STF impregnated Kevlar fabrics was experimentally investigated. The puncture and cut resistance were tested using a drop test machine withspike and knife indenters fabricated based on the National Institute of Justice (NIJ) standard. The STF was filled with spherical $SiO_2$ particles having an average diameter of 100nm, 300nm, and 500nm. The effect of particle size on puncture and cut resistance of STF impregnated Kevlar fabrics was also investigated. The measured impact load histories showed that STF impregnation into fabric leads to withstand higher peak loads than that of neat fabrics under spike test. The test results showed that Kevlar impregnated with STF exhibit remarkable improvements in puncture resistance while it is slightly influential on the cut resistance. Specifically, particle size is the one of the dominant factors controlling fabric resistance to puncture under spike impact test.

• Journal of the Korea Organic Resources Recycling Association
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• 제32권2호
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• pp.5-14
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• 2024

A study approached the development of a process for efficiently recycling discarded cigarette butts, reported as a major source of microplastic pollution in aquatic environments. Cigarette butts were sorted to extract filters, and cellulose acetate, the raw material of the filters, was extracted to a high degree of purity. The sorting of filters from cigarette butts was conducted through both wet and dry processes, each with optimized sorting conditions. Wet stirring sorting considered factors such as solid-liquid ratio, stirring speed, and stirring temperature. The highest efficiency of wet stirring sorting, at 46.21%, was observed with a solid-liquid ratio of 1:45, stirring speed of 200 rpm, and stirring temperature of 50℃. Dry wind power sorting took into account moisture content and residence time. The filter sorting efficiency reached its peak at 57.10% with a moisture content of 20% and a residence time of 5 minutes. There was no significant difference in the recovery rate of cellulose acetate between the two sorting processes. Dry wind power sorting was deemed a more advantageous process in terms of energy and environmental considerations within the scope of this study.

• Korean Journal of Radiology
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• 제25권3호
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• pp.243-256
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• 2024

Objective: We aimed to investigate whether 2-[¹⁸F]fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography (2-[¹⁸F]FDG PET/CT) can aid in evaluating the risk of malignancy in ampullary tumors detected by endoscopy. Materials and Methods: This single-center retrospective cohort study analyzed 155 patients (79 male, 76 female; mean age, 65.7 ± 12.7 years) receiving 2-[¹⁸F]FDG PET/CT for endoscopy-detected ampullary tumors 5-87 days (median, 7 days) after the diagnostic endoscopy between June 2007 and December 2020. The final diagnosis was made based on histopathological findings. The PET imaging parameters were compared with clinical data and endoscopic features. A model to predict the risk of malignancy, based on PET, endoscopy, and clinical findings, was generated and validated using multivariable logistic regression analysis and an additional bootstrapping method. The final model was compared with standard endoscopy for the diagnosis of ampullary cancer using the DeLong test. Results: The mean tumor size was 17.1 ± 7.7 mm. Sixty-four (41.3%) tumors were benign, and 91 (58.7%) were malignant. Univariable analysis found that ampullary neoplasms with a blood-pool corrected peak standardized uptake value in earlyphase scan (SUVe) ≥ 1.7 were more likely to be malignant (odds ratio [OR], 16.06; 95% confidence interval [CI], 7.13-36.18; P < 0.001). Multivariable analysis identified the presence of jaundice (adjusted OR [aOR], 4.89; 95% CI, 1.80-13.33; P = 0.002), malignant traits in endoscopy (aOR, 6.80; 95% CI, 2.41-19.20; P < 0.001), SUVe ≥ 1.7 in PET (aOR, 5.43; 95% CI, 2.00-14.72; P < 0.001), and PET-detected nodal disease (aOR, 5.03; 95% CI, 1.16-21.86; P = 0.041) as independent predictors of malignancy. The model combining these four factors predicted ampullary cancers better than endoscopic diagnosis alone (area under the curve [AUC] and 95% CI: 0.925 [0.874-0.956] vs. 0.815 [0.732-0.873], P < 0.001). The model demonstrated an AUC of 0.921 (95% CI, 0.816-0.967) in candidates for endoscopic papillectomy. Conclusion: Adding 2-[¹⁸F]FDG PET/CT to endoscopy can improve the diagnosis of ampullary cancer and may help refine therapeutic decision-making, particularly when contemplating endoscopic papillectomy.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• 제34권1호
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• pp.77-84
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• 2024

Objectives: Interventions promoting physical exercise and healthy habits in workplaces have been shown to be effective in reducing risk factors for metabolic syndrome. This study was conducted to examine the effects of an individualized conditioning exercise program of IT company office workers with or at higher risk of metabolic syndrome. Methods: A total of 444 IT company office workers with or at higher risk of metabolic syndrome participated in a 3-month conditioning exercise program. Body composition data using bioelectrical impedance analysis and cardiopulmonary data using cardiopulmonary exercise testing from 53 individuals (mean age: 34.8 ± 7.1 years, sex : 21% female, height : 170.4 ± 6.8 cm, weight : 75.2±12.2 kg, body mass index : 25.8±3.3 kg/m²) who have successfully completed pre-test, intervention, and post-test were analyzed. The 12 weeks intervention encompassed: (1) health counseling (2) supervised exercise(endurance-based, aerobic exercise, or circuit training once a week for 50 minutes at heart rate reserve(HRR) of 77-95%) (3) self-directed exercise and biweekly health screening checks. Results: The results indicated a significant decrease in body weight, body fat mass and body mass index, respectively. Moreover, VO₂peak, AT VO₂ and AT Time significantly improved, respectively. Resting blood pressure(SBP/DBP) showed positive changes but were not statistically significant. We observed the correlation between characteristics of participants and rate of changes in cardiopulmonary outcomes of participants, there are no significant correlation. These results indicate positive changes in body composition and cardiorespiratory fitness parameters following individualized conditioning exercise program. Conclusions: Individualized workplace exercise program for preventing metabolic syndrome can lead to improvements in body composition and cardiorespiratory fitness.