• The Journal of Advanced Prosthodontics
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• v.11 no.3
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• pp.179-186
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• 2019

PURPOSE. The purpose of this study was to compare two novel impression methods and a conventional impression method for edentulous jaws using 3-dimensional (3D) analysis software. MATERIALS AND METHODS. Five edentulous patients (four men and one woman; mean age: 62.7 years) were included. Three impression techniques were used: conventional impression method (CI; control), simple modified closed-mouth impression method with a novel tray (SI), and digital impression method using an intraoral scanner (DI). Subsequently, a gypsum model was made, scanned, and superimposed using 3D analysis software. Mean area displacement was measured using CI method to evaluate differences in the impression surfaces as compared to those values obtained using SI and DI methods. The values were confirmed at two to five areas to determine the differences. CI and SI were compared at all areas, while CI and DI were compared at the supporting areas. Kruskal-Wallis test was performed for all data. Statistical significance was considered at P value <.05. RESULTS. In the comparison of the CI and SI methods, the greatest difference was observed in the mandibular vestibule without statistical significance (P>.05); the difference was < 0.14 mm in the maxilla. The difference in the edentulous supporting areas between the CI and DI methods was not significant (P>.05). CONCLUSION. The CI, SI, and DI methods were effective in making impressions of the supporting areas in edentulous patients. The SI method showed clinically applicability.

• Journal of Soil and Groundwater Environment
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• v.26 no.5
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• pp.49-59
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• 2021

The effects of green manure crops, hairy vetch and sesban, supplemented with HS (humic substance) on biological soil health indicators was studied in a pot containing two kinds of reclaimed soil previously contaminated with petroleum hydrocarbons; a soil remediated by land-farming (DDC) and another soil by low-temperature thermal desorption (YJ). Treatments include no plant (C), plants only (H), and plants+2% HS (PH), which were evaluated in a pot containing respective soil. Biological indicators include microbial community analysis as well as soil enzyme activities of dehydrogenase, 𝛽-glucosidase, N-acetyl-𝛽-D-glucosaminidase (NAG), acid/alkaline phosphatase, arylsulfatase, and urease. Results showed an increase of enzyme activities in pot soils with plants and even greater in soils with plants+HS. The enzyme activities of DDC soil with plants (DDC_P) and with plants+HS (DDC_PH) increased 1.6 and 3.9 times on average, respectively than those in the control. The enzyme activities YJ soil with plants (YJ_P) and with plant+HS (YJ_PH) increased 1.8 and 3.8 times on average, respectively than those in the control. According to microbial community analysis, the relative abundance of nitrogen-fixing bacteria in DDC and YJ soil was increased from 1.5% to 7% and from 0 to 5%, respectively, after planting hairy vetch and sesban. This study showed that mixed planting of green manure crops with a supplement of humic substance is highly effective for the restoration of biological health indicators of reclaimed soils.

• The Journal of the Convergence on Culture Technology
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• v.7 no.4
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• pp.385-390
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• 2021

This study aims to provide primary data for R&D on rollator-walking frame through researching the usability test of the rollator-walking frame and the effect of rollator-walking frames on the lives of senior citizens. This study surveyed 60 senior citizens living in Sungnam City in South Korea. As the result of the usability test, we can find users' dissatisfaction with the folding, weight, shape of backrest and material of chair. The survey shows that the frequency of outdoor activity is mostly increased by the convenience of product. However, the inconvenience while using facilities, such as elevators or public transportations, gave a significant impact on the decrease in going out experiences. Therefore, for better outside lifestyle of senior citizens, it is important to improve the function of the product, however, we need to make improvement of urban infrastructure.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.32 no.2
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• pp.163-171
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• 2022

Objectives: Fit performance may vary depending on the ambient aerosol number and ratio in respective test environment. Although several instrument can measure it, they differ with respect to the measurement principle and the range of ambient aerosols collected to calculate the fit factor. Methods: In this study, the fit performance between a condensation nuclei counter(CNC) and an optical particle counter(OPC) was compared according to ambient aerosol number concentration, and evaluated consistency. One type respirators(N95 masks) was worn by 50 participants PortaCount®(Pro+ 8038) and MT®(05U) were connected with one probe to one mask, and Fit Factors(FFs) were measured simultaneously. Results: The interclass correlation coefficient of the fit factor and ambient aerosol number, as measured by the two instrument, was 0.82 and 0.79, respectively, indicating a high consistency level. On the other hand there was a significant correlation between the successful test performance of the OPC instrument and the ambient aerosol number. Conclusions: The test was passed with the CNC and OPC instruments when the ambient aerosol number was 635-3,332 particles/cm³ and 368-1,976 particles/cm³, respectively. Thus, the ideal ambient aerosol number of particles differed between the two instrument.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.45 no.4
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• pp.150-156
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• 2022

As the 4th industrial revolution emerges, the implementation of smart factories are essential in the manufacturing industry. However, 80% of small and medium-sized enterprises that have introduced smart factories remain at the basic level. In addition, in root industries such as injection molding, PLC and HMI software are used to implement functions that simply show operation data aggregated by facilities in real time. This has limitations for managers to make decisions related to product production other than viewing data. This study presents a method for upgrading the level of smart factories to suit the reality of small and medium-sized enterprises. By monitoring the data collected from the facility, it is possible to determine whether there is an abnormal situation by proposing an appropriate algorithm for meaningful decision-making, and an alarm sounds when the process is out of control. In this study, the function of HMI has been expanded to check the failure frequency rate, facility time operation rate, average time between failures, and average time between failures based on facility operation signals. For the injection molding industry, an HMI prototype including the extended function proposed in this study was implemented. This is expected to provide a foundation for SMEs that do not have sufficient IT capabilities to advance to the middle level of smart factories without making large investments.

• Development and Reproduction
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• v.26 no.4
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• pp.135-144
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• 2022

As the number of coronavirus disease 2019 (COVID-19) vaccinations increases, various side effects are being reported, and menstrual abnormalities have been reported as a side effect in women. However, it is still unclear whether the COVID-19 vaccine has detrimental effects on the female reproductive system. Therefore, we investigated the effect of excessive immune response on reproductive function by administering Lipopolysaccharides (LPS) instead of the COVID-19 vaccine. The immune response in mice was induced by injection of LPS. Mice injected with saline 5 times were used as a control group, and mice injected with LPS 5 times were used as an experimental group. Repeated administration of LPS significantly reduced the number of corpus luteum (CL). On the other hand, the injection of LPS did not affect the development of follicles leading before the CL. The expression of the apoptosis-related genes Fas and Fas-L increased in the experimental group. In addition, the expression of the inflammation-related genes increased in the experimental group. In this study, we confirmed that LPS had detrimental effects on the uterus and ovaries in mice. These results suggest that injection of LPS can cause immune reactions within the uterus and ovaries and cause hormonal changes, which can have adverse effects such as abnormal operation or bleeding of the menstrual cycle. These results are expected to help determine the cause of decreased reproductive function, infertility, or physiological disorders caused by the COVID-19 vaccine.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.36 no.2
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• pp.191-196
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• 2023

In this paper, for the application of ultrasonic cleaners for cleaning dentures and transparent braces, Pb(Mn_1/3Nb_2/3)O₃-Pb(Ni_1/3 Nb_2/3)O₃-Pb(Zr,Ti)O₃ [PMN-PNN-PZT] system ceramics were manufactured and their dielectric and piezoelectric properties were investigated. Overall the best properties suitable for the device applications such as ultrasonic cleaner were obtained from the ceramics sintered at 920℃: bulk density of 7.8 g/cm³, the dielectric constant (ε_r) of 1,689, piezoelectric charge constant (d₃₃) of 433 pC/N, planar electromechanical coupling factor (k_p) of 0.64, mechanical quality factor (Qm) of 835, S₁₁^E of 13.37 (10^-12 N/m²), and Curie temperature of 315℃ By using the physical properties of this composition, the ultrasonic cleaner was designed and simulated using the commercial ATILA software. For the three-layered ceramics with the dimension of 25 mm × 25 mm × 2.5mm, an excellent displacement of 8.998 10^-3 m) and the sound pressure of 147.68 dB were recorded.

• Korean Journal of Plant Resources
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• v.36 no.3
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• pp.207-218
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• 2023

Hepatocellular carcinoma (HCC) has a poor prognosis and high metastasis and recurrence rates. Although extracts of Alnus hirsuta (Turcz. ex Spach) Rupr. (AH) have been demonstrated to possess potential anti-inflammatory and anti-cancer activities, the underlying mechanism of AH in HCC treatment remains to be elucidated. We investigated the effects and potential mechanisms of AH on migration and invasion of Hep3B cells. Within the non-cytotoxic concentration range, AH significantly inhibited motility and invasiveness of Hep3B cells in a concentration-dependent manner. Inhibitory effects of AH on cell invasiveness are associated with tightening of tight junctions (TJs), as demonstrated by an increase in transepithelial electrical resistance. Immunoblotting indicated that AH decreased levels of claudins, which form major components of TJs and play key roles in the control and selectivity of paracellular transport. Furthermore, AH inhibited the expression and activity of matrix metalloproteinase (MMP)-2 and MMP-9 and simultaneously increased the levels of tissue inhibitor of metalloproteinase (TIMP)-1 and TIMP-2. These effects were related to inactivation of the phosphoinositide 3-kinase (PI3K)/AKT pathway in Hep3B cells. Therefore, AH inhibits migration and invasion of Hep3B cells by inhibiting the activity of MMPs and tightening TJs through suppression of claudin expression, possibly by suppressing the PI3K/AKT signaling pathway.

• Journal of Auto-vehicle Safety Association
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• v.15 no.2
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• pp.35-41
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• 2023

On December 19, 2015, as Article 29-3 (Installation of Accident Recording Devices and Provision of Information) of Motor Vehicle Management Act came into force, In Korea, the EDR (Event Data Recorder) reports are often used for the analysis of various traffic accident cases such as multiple collisions, traffic insurance crimes, and sudden unintended acceleration (SUA), and the others. So many investigators have analyzed the driver's behavior and vehicle situation by comparing the time zero in the EDR report to the actual crash time in dash-cam (or CCTV). Time zero (T0) is defined as the reference time for the record interval or time interval when recording an accident in Article 56-2, Enforcement rule of Performance and Standard for Automobile and Automotive parts. Also in the EDR report, time zero (T0) is defined as whichever of the following occurs first; 1. "wake-up" by an air-bag control system, 2. Continuously running algorithms (by monitoring of longitudinal or lateral delta-V), 3. Deployment of a non-reversible deployment restraint. We have already proposed the "Flowchart & Checklist" to adopt the EDR report for traffic accident investigation and the necessity of specialized institutions or courses to systematically educate or analyze the EDR data. Therefore, in this paper, we report to traffic accident investigators notable points and analysis methods based on some real-world traffic accidents that can be misjudged in specifying time zero (T0).

• Particle and aerosol research
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• v.19 no.2
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• pp.21-30
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• 2023

Solar cells, converting abundant solar energy into electrical energy, are considered crucial for sustainable energy generation. Recent advancements focus on nanoparticle-enhanced solar cells to overcome limitations and improve efficiency. These cells offer two potential efficiency enhancements. Firstly, plasmonic effects through nanoparticles can improve optical performance by enhancing absorption. Secondly, nanoparticles can improve charge transport and reduce recombination losses, enhancing electrical performance. However, factors like nanoparticle size, placement, and solar cell structure influence the overall performance. This study evaluates the performance of silver nanoparticles incorporated in a p-i-n structure of perovskite solar cells, generated via aerosol state by the evaporation and condensation system. The silver nanoparticles deposited between the hole transport layer and transparent electrode form nanoparticle embedded transport layer (NETL). The evaluation of the optoelectronic properties of perovskite devices using NETL demonstrates their potential for improving efficiency. The findings highlight the possibility of nanoparticle incorporation in perovskite solar cells, providing insights for sustainable energy generation.