• The Journal of Korean Academy of Prosthodontics
• /
• v.57 no.2
• /
• pp.127-133
• /
• 2019

Purpose: The purpose of present study was to investigate fracture strength and mode of failure of endodontically treated teeth restored with metal cast post-core system, prefabricated fiber post system, and newly introduced polyetherketoneketone (PEKK) post-core system. Materials and methods: A total of 21 mandibular premolar were randomly grouped into 3 groups of 7 each according to the post material. Group A was for metal cast post core; Group B for prefabricated glass fiber post and resin core; and Group C for milled PEKK post cores. All specimens were restored with metal crown. The fracture strength of each specimen was measured by applying a static load of 135-degree to the tooth at 2 mm/min crosshead speed using a universal testing machine. After the fracture strength measurement, the mode of failure was observed. The results were analyzed using Kruscal-Wallis test and post hoc Mann-Whitney U test at confidence interval ${\alpha}=.05$. Results: Fracture resistance of PEKK post core was lower than those of cast metal post and fiber reinforced post with composite resin core. In the aspect of fracture mode most of the root fracture occurred in the metal post core, whereas the post detachment occurred mainly in the fiber reinforced post. In the case of PEKK post core, teeth and post were fractured together. Conclusion: It is necessary to select appropriate materials of post for extensively damaged teeth restoration and clinical application of the PEKK post seems to require more research on improvement of strength.

• Journal of Gynecologic Oncology
• /
• v.29 no.6
• /
• pp.100.1-100.13
• /
• 2018

Objective: To investigate survival outcomes in endometrioid endometrial cancer (EEC) patients with single vs. multiple positive pelvic lymph nodes. Methods: We performed a retrospective evaluation of all consecutive patients with histologically proven International Federation of Gynecology and Obstetrics (FIGO) stage IIIC1 EEC who underwent primary surgical treatment between 2004 and 2014 at seven Italian gynecologic oncology referral centers. Patients with pre- or intra-operative evidence of extra-uterine disease (including the presence of bulky nodes) and patients with stage IIIC2 disease were excluded, in order to obtain a homogeneous population. Results: Overall 140 patients met the inclusion criteria. The presence of >1 metastatic pelvic node was significantly associated with an increased risk of recurrence and mortality, compared to only 1 metastatic node, at both univariate (recurrence: hazard ratio [HR]=2.19; 95% confidence interval [CI]=1.2-3.99; p=0.01; mortality: HR=2.8; 95% CI=1.24-6.29; p=0.01) and multivariable analysis (recurrence: HR=1.91; 95% CI=1.02-3.56; p=0.04; mortality: HR=2.62; 95% CI=1.13-6.05; p=0.02) and it was the only independent predictor of prognosis in this subset of patients. Disease-free survival (DFS) and disease-specific survival (DSS) were significantly longer in patients with only 1 metastatic node compared to those with more than 1 metastatic node (p=0.008 and 0.009, respectively). Conclusion: The presence of multiple metastatic nodes in stage IIIC1 EEC represents an independent predictor of worse survival, compared to only one positive node. Our data suggest that EEC patients may be categorized according to the number of positive nodes.

• Korean journal of health promotion
• /
• v.18 no.4
• /
• pp.177-183
• /
• 2018

Background: Many studies have reported that adolescents living with single parent have a high risk of obesity. However, those studies did not explore the implication of the gender of single parent living with adolescents. This study investigated the differences in obesity rates according to status of co-residence with their parents in Korean adolescents. The family living with single parent was classified into the family living with single father and the family living with single mother. Methods: This cross-sectional study involved 59,602 adolescents who participated in the 2017 Korea Youth Risk Behavior Web-based Survey. The data on height, weight, status of co-residence with parents, and the other variables were obtained through online questionnaires. Results: In male adolescents, the family living with single mother was related to a high proportion of obesity (odds ratio [OR] 1.24, 95% confidence interval [CI] 1.09-1.40) and overweight (OR 1.17, 95% CI 1.03-1.34). However, in female adolescents, the family living with single father was related to a high proportion of obesity (OR 1.49, 95% CI 1.23-1.82). In addition, female adolescents living with neither parent were more likely to be obese (OR 1.47, 95% CI 1.13-1.91) and overweight (OR 1.31, 95% CI 1.00-1.70). Conclusions: This study showed a risk of obesity in adolescents living with single parent differs according to the gender of single parent living with adolescents. Not adolescents living with a same-gender parent, but those living with an opposite-gender parent have a high risk of obesity.

• Korean Journal of Remote Sensing
• /
• v.37 no.3
• /
• pp.515-530
• /
• 2021

This study is to estimate soil moisture (SM) using Sentinel-1A/B C-band SAR (synthetic aperture radar) images and Multiple Linear Regression Model(MLRM) in the Yongdam-Dam watershed of South Korea. Both the Sentinel-1A and -1B images (6 days interval and 10 m resolution) were collected for 5 years from 2015 to 2019. The geometric, radiometric, and noise corrections were performed using the SNAP (SentiNel Application Platform) software and converted to backscattering coefficient of VV and VH polarization. The in-situ SM data measured at 6 locations using TDR were used to validate the estimated SM results. The 5 days antecedent precipitation data were also collected to overcome the estimation difficulty for the vegetated area not reaching the ground. The MLRM modeling was performed using yearly data and seasonal data set, and correlation analysis was performed according to the number of the independent variable. The estimated SM was verified with observed SM using the coefficient of determination (R²) and the root mean square error (RMSE). As a result of SM modeling using only BSC in the grass area, R² was 0.13 and RMSE was 4.83%. When 5 days of antecedent precipitation data was used, R² was 0.37 and RMSE was 4.11%. With the use of dry days and seasonal regression equation to reflect the decrease pattern and seasonal variability of SM, the correlation increased significantly with R² of 0.69 and RMSE of 2.88%.

• Korean Journal of Remote Sensing
• /
• v.37 no.3
• /
• pp.531-542
• /
• 2021

Open-pit mines require constant monitoring as they can cause surface changes and environmental disturbances. In open-pit mines, there is little vegetation at the mining site and can be monitored using InSAR (Interferometric Synthetic Aperture Radar) coherence imageries. In this study, activities occurring in mine were analyzed by applying the recently developed InSAR coherence-based NDAI (Normalized Difference Activity Index). The March 5 Youth Mine is a North Korean mine whose development has been expanded since 2008. NDAI analysis was performed with InSAR coherence imageries obtained using Sentinel-1 SAR images taken at 12-day intervals in the March 5 Youth Mine. First, the area where the elevation decreased by about 75.24 m and increased by about 9.85 m over the 14 years from 2000 was defined as the mining site and the tailings piles. Then, the NDAI images were used for time series analysis at various time intervals. Over the entire period (2017-2019), average mining activity was relatively active at the center of the mining area. In order to find out more detailed changes in the surface activity of the mine, the time interval was reduced and the activity was observed over a 1-year period. In 2017, we analyzed changes in mining operations before and after artificial earthquakes based on seismic data and NDAI images. After the large-scale blasting that occurred on 30 April 2017, activity was detected west of the mining area. It is estimated that the size of the mining area was enlarged by two blasts on 30 September 2017. The time-averaged NDAI images used to perform detailed time-series analysis were generated over a period of 1 year and 4 months, and then composited into RGB images. Annual analysis of activity confirmed an active region in the northeast of the mining area in 2018 and found the characteristic activity of the expansion of tailings piles in 2019. Time series analysis using NDAI was able to detect random surface changes in open-pit mines that are difficult to identify with optical images. Especially in areas where in situ data is not available, remote sensing can effectively perform mining activity analysis.

• Korean Journal of Environment and Ecology
• /
• v.35 no.3
• /
• pp.223-236
• /
• 2021

This study aims to provide basic data for the systematic conservation and efficient management of forest ecosystems by analyzing changes in understory vegetation of temperate broad-leaved deciduous forests. One-hectare permanent survey plot, consisting of 100 subplots sized 10 × 10 meters, was installed in Gwangneung forest in Pocheon, Gyeonggi-do in 2003. The state of stands and the understory vegetation in the permanent survey plot were examined at a 5-year interval from 2003 to 2018. The vascular plants found in the survey area were 56 families, 128 genera, 176 species, 18 variants, 4 varieties, and 1 subspecies, for a total of 199 taxa. The number of species in both the shrub layer and the herbaceous layer showed a tendency to decrease with time. The MRPP-tests showed a significantly differing species composition of the shrub layer in all years except 2008-2013, whereas significant differences were found in all years concerning the herbaceous layer. As for the average importance value, Euonymus oxyphyllus (18.23%), Acer pseudosieboldianum (16.48%), and Callicarpa japonica (13.85%) were dominant in the shrub layer, while Ainsliaea acerifolia (23.41%), Disporum smilacinum (9.45%), and Oplismenus undulatifolius (5.62%) were dominant in the herbaceous layer. In the shrub layer, the richness of Smilax china, Lonicera subsessilis, and Philadelphus schrenkii was high when the basal area and the stand density of an upper layer were high. By contrast, smaller basal area and stand density were associated with the richness of Acer pseudosieboldianum, Deutzia glabrata, Morus bombycis, and Cornus kousa. Furthermore, it was found out that the impact of the basal area and the stand density on the herbaceous layer decreased over time, while the herb layer's species composition was greatly affected by cover degrees of Euonymus oxyphyllus and Acer pseudosieboldianum in the shrub layer. In conclusion, the number of species in the understory vegetation in Gwangneung forest is continuously decreasing, thus implying that species diversity, basal area, and stand density of an upper layer can influence the species composition in understory vegetation.

• Journal of Environmental Impact Assessment
• /
• v.30 no.1
• /
• pp.13-23
• /
• 2021

In this study, we performed a Random Walker analysis to predict the Major Movement Paths of otters. The scope of the research was a simulation analysis with a radius of 7.5 km set as the final range centered on the Ansim-wetland in Daegu City, and a field survey was used to verify the model. The number of virtual otters was set to 1,000, the number of moving steps was set to 1,000 steps per grid, and simulations were performed on a total of 841 grids. As a result of the analysis, an average of 147.6 objects arrived at the boundary point under the condition of an interval of 50 m. As a result of the simulation verification, 8 points (13.1%) were found in the area where the movement probability was very high, and 9 points (14.8%) were found in the area where the movement probability was high. On the other hand, in areas with low movement paths probabilities, there were 8 points (13.1%) in low areas and 4 points (6.6%) in very low areas. Simulation verification results In areas with high otter values, the actual otter format probability was particularly high. In addition, as a result of investigating the correlation with the otter appearance point according to the unit area of the evaluation star of the movement probability, it seems that 6.8 traces were found per unit area in the area where the movement probability is the highest. In areas where the probability of movement is low, analysis was performed at 0.1 points. On the side where otters use the major movement paths of the river area, the normal level was exceeded, and as a result, in the area, 23 (63.9%), many form traces were found, along the major movement paths of the simulation. It turned out that the actual otter inhabits. The EN-Simulator analysis can predict how spatial properties affect the likelihood of major movement paths selection, and the analytical values are used to utilize additional habitats within the major movement paths. It is judged that it can be used as basic data such as to grasp the danger area of road kill in advance and prevent it.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.26 no.1
• /
• pp.11-36
• /
• 2021

The solar annual (Sa) and semiannual (Ssa) tides account for much of the non-uniform annual and seasonal variability observed in sea levels. These non-equilibrium tides depend on atmospheric variations, forced by changes in the Sun's distance and declination, as well as on hydrographic conditions. Here we employ tidal harmonic analyses to calculate Sa and Ssa harmonic constants for 21 Korean coastal tidal stations (TS), operated by the Korea Hydrographic and Oceanographic Agency. We used 19 year-long (1999 to 2017) 1 hr-interval sea level records from each site, and used two conventional harmonic analysis (HA) programs (Task2K and UTide). The stability of Sa harmonic constants was estimated with respect to starting date and record length of the data, and we examined the spatial distribution of the calculated Sa and Ssa harmonic constants. HA was performed on Incheon TS (ITS) records using 369-day subsets; the first start date was January 1, 1999, the subsequent data subset starting 24 hours later, and so on up until the final start date was December 27, 2017. Variations in the Sa constants produced by the two HA packages had similar magnitudes and start date sensitivity. Results from the two HA packages had a large difference in phase lag (about 78°) but relatively small amplitude (<1 cm) difference. The phase lag difference occurred in large part since Task2K excludes the perihelion astronomical variable. Sensitivity of the ITS Sa constants to data record length (i.e., 1, 2, 3, 5, 9, and 19 years) was also tested to determine the data length needed to yield stable Sa results. HA results revealed that 5 to 9 year sea level records could estimate Sa harmonic constants with relatively small error, while the best results are produced using 19 year-long records. As noted earlier, Sa amplitudes vary with regional hydrographic and atmospheric conditions. Sa amplitudes at the twenty one TS ranged from 15.0 to 18.6 cm, 10.7 to 17.5 cm, and 10.5 to 13.0 cm, along the west coast, south coast including Jejudo, and east coast including Ulleungdo, respectively. Except at Ulleungdo, it was found that the Ssa constituent contributes to produce asymmetric seasonal sea level variation and it delays (hastens) the highest (lowest) sea levels. Comparisons between monthly mean, air-pressure adjusted, and steric sea level variations revealed that year-to-year and asymmetric seasonal variations in sea levels were largely produced by steric sea level variation and inverted barometer effect.

• Korean Journal of Agricultural and Forest Meteorology
• /
• v.23 no.4
• /
• pp.374-390
• /
• 2021

Growth and yield of field vegetable crops would be affected by climate conditions, which cause a relatively large fluctuation in crop production and consumer price over years. The yield prediction system for these crops would support decision-making on policies to manage supply and demands. The objectives of this study were to compile literatures related to onion and garlic and to perform data-mining analysis, which would shed lights on the development of crop models for these major field vegetable crops in Korea. The literatures on crop growth and yield were collected from the databases operated by Research Information Sharing Service, National Science & Technology Information Service and SCOPUS. The keywords were chosen to retrieve research outcomes related to crop growth and yield of onion and garlic. These literatures were analyzed using text mining approaches including word cloud and semantic networks. It was found that the number of publications was considerably less for the field vegetable crops compared with rice. Still, specific patterns between previous research outcomes were identified using the text mining methods. For example, climate change and remote sensing were major topics of interest for growth and yield of onion and garlic. The impact of temperature and irrigation on crop growth was also assessed in the previous studies. It was also found that yield of onion and garlic would be affected by both environment and crop management conditions including sowing time, variety, seed treatment method, irrigation interval, fertilization amount and fertilizer composition. For meteorological conditions, temperature, precipitation, solar radiation and humidity were found to be the major factors in the literatures. These indicate that crop models need to take into account both environmental and crop management practices for reliable prediction of crop yield.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.41 no.6
• /
• pp.727-736
• /
• 2021

Road tunnel lengths are increasing. Some 1,300 tunnels with 1,102 km in length had been increased till 2019 from 2010. There are 64 tunnels over 3,000 m in length, with their total length adding up to 276.7 km. Safety facilities in the event of a tunnel fire are critical so as to prevent large-scale casualties. Standards for installing disaster prevention facilities are being proposed based on the guidelines of the Ministry of Land, Infrastructure and Transport, but they may be limited to deep underground tunnels. This study was undertaken to provide guidelines for the spacing of evacuation connection passages and the widths of evacuation connection doors. Evacuation with various spacing and widths was simulated in regards to evacuation time, which is the measure of safety, using the evacuation analysis simulation software EXODUS Ver.6.3 and the fire/smoke analysis software SMARTFIRE Ver.4.1. Evacuation connection gates with widths of 0.9 m and 1.2 m, and spacings of 150 m to 250 m, were set to every 20 m. In addition, longitudinal slopes of 6 % and 0 % were considered. It was determined to be safe when the evacuation completion time was shorter than the delay diffusion time. According to the simulation results, all occupants could complete evacuation before smoke spread regardless of the width of the evacuation connection door when the longitudinal slope was 6 % and the interval of evacuation connection passage was 150 m. When the evacuation connection passage spacing was 200 m and the evacuation connection gate width was 1.2 m, all occupants could evacuate when the longitudinal slope was 0 %. Due to difference in evacuation speed according to the longitudinal slope, the evacuation time with a 6 % slope was 114 seconds shorter (with the 190 m connection passage) than with a 0 % slope. A shorter spacing of evacuation connection passages may reduce the evacuation time, but this is difficult to implement in practice because of economic and structural limitations. If the width of the evacuation junction is 1.2 m, occupants could evacuate faster than with a 0.9 m width. When the width of a connection door is 1.2 m with appropriate connection passage spacing, it might provide a means to increase economic efficiency and resolve structural limitations while securing evacuation safety.