• Structural Engineering and Mechanics
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• v.70 no.1
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• pp.13-31
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• 2019

A nonlinear finite element model (FEM) using ATENA-3D software to simulate the axially compressive behavior of circular steel tube confined concrete (CSTCC) columns infilled with ultra high performance concrete (UHPC) was presented in this paper. Some modifications to the material type "CC3DNonlinCementitious2User" of UHPC without and with the incorporation of steel fibers (UHPFRC) in compression and tension were adopted in FEM. The predictions of utimate strength and axial load versus axial strain curves obtained from FEM were in a good agreement with the test results of eighteen tested columns. Based on the results of FEM, the load distribution on the steel tube and the concrete core was derived for each modeled column. Furthermore, the effect of bonding between the steel tube and the concrete core was clarified by the change of friction coefficient in the material type "CC3DInterface" in FEM. The numerical results revealed that the increase in the friction coefficient leads to a greater contribution from the steel tube, a decrease in the ultimate load and an increase in the magnitude of the loss of load capacity. By comparing the results of FEM with experimental results, the appropriate friction coefficient between the steel tube and the concrete core was defined as 0.3 to 0.6. In addition to the numerical evaluation, eighteen analytical models for confined concrete in the literature were used to predict the peak confined strength to assess their suitability. To cope with CSTCC stub and intermediate columns, the equations for estimating the lateral confining stress and the equations for considering the slenderness in the selected models were proposed. It was found that all selected models except for EC2 (2004) gave a very good prediction. Among them, the model of Bing et al. (2001) was the best predictor.

• Archives of Plastic Surgery
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• v.46 no.2
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• pp.108-113
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• 2019

Background The aim of this study was to assess the safety of one-per-mil tumescent injections into viable skin flaps that had survived an ischemic insult, in order to assess the potential suitability of one-per-mil tumescent injections in future secondary reconstructive procedures such as flap revision and refinements after replantation. Methods Forty groin flaps harvested from 20 healthy Wistar rats weighing 220 to 270 g were subjected to acute ischemia by clamping the pedicle for 15 minutes. All flaps showing total survival on the 7th postoperative day were randomly divided into group A (one-per-mil tumescent infiltration; n=14), group B (normal saline infiltration; n=13), and group C (control, with no infiltration; n=13) before being re-elevated. Transcutaneous oxygen tension ($TcPO_2$) was measured before and after infiltration, and changes in $TcPO_2$ were statistically analyzed using analysis of variance, the paired t-test, and the independent t-test. The viability of flaps was also assessed using the Analyzing Digital Images software at 7 days after the second elevation. Results Thirty-nine flaps survived to the final assessment, with the sole exception of a flap from group A that did not survive the first elevation. $TcPO_2$ readings showed significant decreases (P<0.05) following both one-per-mil tumescent ($99.9{\pm}5.7mmHg$ vs. $37.2{\pm}6.3mmHg$) and normal saline ($103{\pm}8.5mmHg$ vs. $48.7{\pm}5.9mmHg$) infiltration. Moreover, all groin flaps survived with no signs of tissue necrosis. Conclusions One-per-mil tumescent infiltration into groin flap tissue that had survived ischemia did not result in tissue necrosis, although the flaps experienced a significant decrease of cutaneous oxygenation.

• Korean Journal of Agricultural Science
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• v.48 no.2
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• pp.251-264
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• 2021

Bovine respiratory syncytial virus (BRSV) and bovine viral diarrhea virus (BVDV) are the main viral contributors to bovine respiratory disease (BRD) with high mortality and morbidity. BRD control measures include vaccination that modulates immunological profiles reflected in blood cells, serum, and body secretions, such as milk. This study evaluated the immune responses to an inactivated BRD vaccine in lactating cows reared in a natural environment on a dairy farm. The cows were intramuscularly inoculated with the vaccine, and serum, blood, and milk were collected pre-and post-vaccination. Our study revealed a prominent increase in BRSV-specific antibodies both in serum and milk, while the change in BVDV-specific antibodies was insignificant. Serum interleukin (IL)-1β and IL-6 levels significantly decreased, but this change was not reflected in milk. Evaluation of pattern recognition receptors (PRRs) via RT-qPCR revealed downregulation of nucleotide-binding oligomerization domain 2 (NOD2). The concentrations of BRSV antibodies, BVDV antibodies, IL-2, and IL-17A in serum and milk were strongly correlated, implying a concurrent influence on both body fluids. Thus, immunological factors modulated as a result of vaccination generally measured in serum were reflected in milk, demonstrating the suitability of milk evaluation as an alternative approach for immunological observations. Furthermore, the correlation between BRSV antibodies and NOD2 and that between BVDV antibodies and toll-like receptor (TLR) 2, TLR3, TLR4, and TLR5 imply the possible role of PRRs for the assessment of the immune response developed in immunized cows reared on the farm.

• Journal of Korea Water Resources Association
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• v.55 no.spc1
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• pp.1197-1210
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• 2022

Recently, users' complaints on drinking water quality are increasing according to emerging interest in the drinking water service issues such as pipe aging and various water quality accidents. In the case of drinking water quality complaints, not only the water pollution but also the inconvenience on the chlorine residual for disinfection are included, thus various efforts, such as rechlorination treatment, are being attempted in order to keep the chlorine concentration supplied evenly. In this research, for a more accurate water quality simulation of water distribution network, the water quality reaction coefficients were estimated, and an optimization method of chlorination/ rechlorination scheduling was proposed consideirng satisfaction of water quality standards and chlorine residual equalization. The proposed method was applied to a large-scale real water network, and various chlorination schemes were comparatively analyzed through the grid search algorithm and optimized based on the suitability and uniformity of supplied chlorine residual concentration.

• Korean Journal of Environment and Ecology
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• v.37 no.6
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• pp.484-498
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• 2023

This study aimed to analyze the appropriateness of the criteria and methods of the feasibility study for national park re-planning. The rate of 'release area' was derived at a lower rate in the absolute evaluation (the second) than the relative evaluation(the third) Seoraksan and Juwangsan National Parks as well as Gayasan National Park. Despite the third evaluation method aiming to maintain park area through retention by setting the areas available for release as 10% rather than applying release, it was found that the absolute evaluation method did not derive more areas available for release. When the second and third ecology-based assessments were applied to study sites, both second and third ecological-based assessments showed that the actual release areas were not reflected in the extraction in 2011. Consequently, it was found that the ecological-based assessment was only a means of assistance instead of a means of critical decision-making for determining the release area. From the district adjustment of the park planning easibility study, it can be determined that interactive exchange and priority application of release criteria as external factors acted more significantly.

• Journal of the Korea Institute of Building Construction
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• v.24 no.2
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• pp.193-202
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• 2024

This research delves into the evaluation of the suitability of ultrasonic pulse velocity as a diagnostic tool for early detection of frost damage in concrete. The investigation involves the measurement of compressive strength and ultrasonic pulse velocity concerning the depth of freezing for individual mortar specimens, followed by an analysis of their microstructure and their interrelation. The findings indicate a consistent decrease in both compressive strength and ultrasonic pulse velocity with increasing freezing depth. Furthermore, a correlation between compressive strength and ultrasonic pulse velocity concerning the depth of early frost damage is established. Consequently, the study asserts the potential of utilizing the ultrasonic pulse velocity method for early detection of frost damage in concrete, with prospects for quantifying the depth of damage through further research endeavors.

• The Journal of Engineering Geology
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• v.34 no.1
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• pp.67-105
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• 2024

This study compares the quartzites of four quartzite units: The Fagfog Quartzite, Dunga Quartzite (member of the Robang Formation), Pandrang Quartzite (member of the Kalitar Formation) and the Chisapani Quartzite. The analysis shows variations in flakiness and elongation, as the Fagfog Quartzite displays low flakiness whereas the Pandrang and the Chisapani have moderate and the Dunga Quartzite has shown variations. The density values of the four quartzite units remain consistent, indicating uniform physical properties and porosity levels. However, bulk density values differ among the quartzites, suggesting variations in particle arrangement, porosity, and density. Regarding strength measures, the Pandrang and the Chisapani Quartzite have higher strength characteristics as compared to the Fagfog and the Dunga Quartzites. The Pandrang Quartzite has the highest average point load strength index, classifying it as "Extremely Strong". The resistance to impact and crushing forces varies among the quartzites, with lower Aggregate Impact Value (AIV) and Aggregate Crushing Value (ACV) indicating higher strength and durability. Durability tests show that the Fagfog Quartzite has high durability against slaking, with a slight decrease observed after the fifth cycle. The Dunga Quartzite shows varying degrees of weathering, while the Pandrang and the Chisapani Quartzite have minimal weight changes, indicating strong resistance to weathering. Magnesium sulfate soundness tests indicate high durability and resistance to degradation for all four units. The Los Angeles abrasion value (LAAV) tests indicate favorable resistance to abrasion for the majority of the Fagfog, Dunga, and the Pandrang Quartzites samples, while Chisapani Quartzite shows more variability in LAAV values. The Pandrang Quartzite shows a higher proportion of elongated particles but lower flakiness index values as compared to Fagfog and Dunga Quartzites while Chisapani Quartzite stands out with a significantly higher presence of flaky particles and lower elongation index values. Mechanically, the Fagfog and Dunga Quartzite show higher strength and better resistance to abrasion and freeze and thaw. The Pandrang Quartzite shows moderate resistance to crushing and sudden effect, while the Chisapani Quartzite has variable resistance to effect. This comparative study emphasizes the diversity and complexity of quartzite rock types, showing the need for comprehensive characterization and assessment to determine their suitability for specific applications.

• Journal of the Korean Geosynthetics Society
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• v.23 no.1
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• pp.27-37
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• 2024

In this study, direct algorithm-based back analysis was utilized to perform back analysis on two actual earth retaining wall fields, which was then compared with genetic algorithm-based method to evaluate the suitability of the back analysis. Additionally, in order to propose effective utilization methods of the program, the measurement data, as the input for the back analysis, was varied for each excavation step, and the applicability of the back analysis results(displacement, axial force) was examined. The research findings indicate that both direct algorithm and genetic algorithm show high applicability; however, the optimization for this program is better predicted by the direct algorithm. Moreover, in order to effectively use the back analysis program employing the direct algorithm, it was evaluated that relatively accurate prediction of the earth retaining wall behavior could be achieved by inputting measurement data from the 7th excavation step for fields with final excavation steps ranging from 8 to 11.

• Korean Journal of Ecology and Environment
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• v.45 no.3
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• pp.271-277
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• 2012

The present study was conducted to assess the suitability of domestic natural waters as a Daphnia magna culture medium. In order to assess survival rate and reproductive output, young female daphnids (parent animals), aged less than 24 hours at the start of the test and produced in the Elendt M4 medium, were exposed to Elendt M4 medium, de-chlorinated tap water, and natural mineral water for 21 days. D. magna cultured in Elendt M4 medium (reference medium) and natural mineral water met the criteria of OECD No. 211, Daphnia magna Reproduction Test Guidelines in terms of percent adult survival, first day of reproduction, and average young production. However, the mortalities of adult daphnids observed in de-chlorinated tap water were more than 20% in two reproduction tests for 21 days. Mortality was observed on exposure days 13, 15, and 18 in de-chlorinated water. The use of D. magna is recommended in water of hardness >80 mg $CaCO_3\;L^{-1}$. However, the hardness of de-chlorinated tap water used in the present study was 50~53 mg $CaCO_3\;L^{-1}$. Therefore, it is judged that the delayed mortalities observed in de-chlorinated tap water were caused by a rapid decreased in hardness when the medium was changed from Elendt M4 to de-chlorinated tap water. When D. magna is cultured using domestic natural waters (underground water, surface water, and de-chlorinated water), the quality-control (QC) data should be maintained through a standardization for health assessment method, toxicity test method using reference chemical, test intervals of reference toxicant toxicity test, and data treatment and interpretation. In the long term, national research programs are needed for the development of test species which are representative of domestic aquatic environmental conditions among indigenous daphnids.

• Korean Journal of Psychosomatic Medicine
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• v.28 no.2
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• pp.143-154
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• 2020

Objectives : The purpose of this study was to examine cognitive and psychological characteristics of patients with military service suitability issues compared to the general psychiatric outpatients. Methods : 108 patients who visited psychiatric clinic center due to military service suitability issues and 80 general psychiatric patients were recruited from the Department of Psychiatry of university hospital. ANCOVA and chi-equare test were used to examine differences between two groups. Furthermore, we utilized paired t-test to compare the scrore within military group depending on when they performed the psychological assessment. Results : There were no significant differences between military group and general outpatient group in WAIS-IV scores. However, military group scored remarkably higher than control group on validity scales, F-r and Fp-r whereas they scored lower on validity scale, K-r. Furthermore, military group showed significantly higher on BDI and MMPI-2-RF, EID, RCd, RC2, RC3, COG, HLP, SFD, NFC, STW, SAVE, SHY, DSF, NEGE-r, INTR-r. As a result of comparison within the military group following the periods of assessment, military group did not show the significant differences on the overall scales of MMPI-2-RF. Conclusions : The present study showed that military group tends to report their psychological distress more exaggeratedly. In addition, they had significantly elevated not only emotional distress such as depression and anxiety but interpersonal problem. The implications and limitations were discussed along with some suggestions for the future studies.