• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.32 no.3
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• pp.242-252
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• 2022

Objectives: Firefighters and police officers are exposed to various occupational hazards. No studies in Korea have investigated the occurrence of cancer by type of cancer for the two occupations. This study aims to investigate the risk of occurrences associated with types of cancers in firefighters and police officers. Methods: Utilizing National Health Insurance(NHI) Claims data from 2006-2015, the study included 8,871,468 general workers, 25,001 firefighters, and 102,274 police officers. Using general workers as a control group, we calculated the standardized incidence ratios(SIR) by types of cancer for firefighters and police officers. After calculating the SIR for all subjects, the SIR was calculated by stratifying according to gender. Results: SIR of colon cancer 1.38(95% CI, 1.11-1.69), cancer of the liver and intrahepatic bile ducts 1.27(95% CI, 1.04-1.54), and 1.88(95% CI, 1.28-2.65) bladder cancer were higher firefighters than general workers. SIR of Lip, oral cavity, and pharynx 1.26(95% CI, 1.07-1.47), Stomach 1.14(95% CI, 1.06-1.23), colon 1.33(95% CI, 1.21-1.46), liver and intrahepatic bile ducts 1.21(95% CI, 1.10-1.32), pancreas 1.24(95% CI, 1.02-1.49), other skin 1.60(95% CI, 1.26-2.00), bladder 1.27(95% CI, 1.04-1.54), other urinary tract 1.46(95% CI, 1.27-1.68), other parts of central nervous system 1.68(95% CI, 1.10-2.46) were higher police officers than general workers. Conclusions: Both firefighters and police officers are exposed to various cancer occurrence risks, necessitating the development of occupational medical protection measures to reduce risk exposure factors.

• Journal of Dental Anesthesia and Pain Medicine
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• v.22 no.5
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• pp.339-348
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• 2022

Background: To compare the anesthetic efficacy of supplemental buccal infiltration (BI) (1.7 ml) versus intraligamentary (IL) injection containing 0.4 ml of 4% articaine with 1:100.000 epinephrine after an inferior alveolar nerve block (IANB) with 1.7 ml 2% lidocaine in the first and second mandibular molars diagnosed with irreversible pulpitis (IP). Methods: One hundred subjects diagnosed with IP of either the mandibular first (n = 50) or second molars (n = 50) and failed profound anesthesia following an IANB were selected. They randomly received either the IL or BI techniques of anesthesia. Pain scores on a 170 mm Heft-Parker visual analog scale were recorded initially, before, and during supplemental injections. Furthermore, pulse rate was measured before and after each supplemental injection. During the access cavity preparation and initial filing, no or mild pain was assumed to indicate anesthetic success. The chi-square test, Mann-Whitney U test, and independent samples t-test were used for the analyses. Results: The overall success rates were 80% in the IL group and 74% in the BI group, with no significant difference (P = 0.63). In the first molars, there was no significant difference between the two techniques (P = 0.088). In the second molars, IL injection resulted in a significantly higher success rate (P = 0.017) than BI. IL injection was statistically more successful (P = 0.034) in the second molars (92%) than in the first molars (68%). However, BI was significantly more successful (P = 0.047) in the first molars (88%) than in the second molars (64%). The mean pulse rate increase was significantly higher in the IL group than in the BI group (P < 0.001). Conclusions: Both the IL and BI techniques were advantageous when used as supplemental injections. However, more favorable outcomes were observed when the second molars received IL injection and the first molars received BI.

• The Journal of the Acoustical Society of Korea
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• v.41 no.3
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• pp.278-286
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• 2022

In this study, a 33-mode Free-Flooded Ring (FFR) transducer was designed to apply piezoelectric single crystal PIN-PMN-PT, which has high piezoelectric constants and electromechanical coupling coefficient. To ensure low-frequency high transmitting sensitivity characteristics with a small size of FFR transducer, the commercial FFR transducer based on piezoelectric ceramics was compared. To develop the FFR transducer with broadband characteristics, a piezoelectric segmented ring structure inserted with inactive elements was applied. The oil-filled structure was applied to minimize the change of acoustic characteristics of the ring transducer. It was verified that the transmitting voltage response, underwater impedance, and beam pattern matched the finite element numerical simulation results well through an acoustic test. The difference in the transmitting voltage response between the measured and the simulated results is about 1.3 dB in cavity mode and about 0.3 dB in radial mode. The fabricated FFR transducer had a higher transmitting voltage response compared to the commercial transducer, but the diameter was reduced by about 17 %. From this study, it was confirmed that the feasibility of a single crystal-applied FFR transducer with compact size and high-power characteristics. The effectiveness of the performance prediction by simulation was also confirmed.

• Advances in nano research
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• v.13 no.6
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• pp.575-585
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• 2022

Due to its biofilm formation and colonization of the osteocyte-lacuno canalicular network (OLCN), Staphylococcus aureus (S.aureus) implant-associated bone infection (SIABI) is difficult to cure thoroughly, and may occur recurrently subsequently after a long period dormant. It is essential to explore an alternative therapeutic strategy that can eradicate the pathogens in the infected foci. To address this, the polymethylmethacrylate (PMMA) bone cement and Fe3O4 nanoparticles compound cylinder were developed as implants based on their size and mechanical properties for the alternative magnetic field (AMF) induced thermal ablation, The PMMA mixed with optimized 2% Fe₃O₄ nanoparticles showed an excellent antibacterial efficacy in vitro. It was evaluated by the CFU, CT scan and histopathological staining on a rabbit 1-stage transtibial screw model. The results showed that on week 7, the CFU of infected soft tissue and implants, and the white blood cells (WBCs) of the PMMA+2% Fe₃O₄+AMF group decreased significantly from their controls (p<0.05). PMMA+2% Fe₃O₄+AMF group did not observe bone resorption, periosteal reaction, and infectious reactive bone formation by CT images. Further histopathological H&E and Gram Staining confirmed there was no obvious inflammatory cell infiltration, neither pathogens residue nor noticeably burn damage around the infected screw channel in the PMMA+2% Fe₃O₄+AMF group. Further investigation of nanoparticle distributions in bone marrow medullary and vital organs of heart, liver, spleen, lung, and kidney. There were no significantly extra Fe₃O₄ nanoparticles were observed in the medullary cavity and all vital organs either. In the current study, PMMA+2% Fe₃O₄+AMF shows promising therapeutic potential for SIABI by providing excellent mechanical support, and promising efficacy of eradicating the residual pathogenic bacteria in bone infected lesions.

• Therapeutic Science for Rehabilitation
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• v.11 no.4
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• pp.55-68
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• 2022

Objective : This review aimed to provide information for clinical application by confirming the principles and characteristics of the tool through a review of tongue movement and measurement tools for patients with swallowing disorders. Results : We identified 15 tools used as tongue exercises and measurement tools in the field of dysphagia. According to principle, the tools were classified as either a bulb sensor, resistive sensor sheet, mouthpiece with sensor, or other techniques. The bulb sensor was easy to use but had limitations in fixing the position when measuring tongue pressure. The resistive sensor sheet could be measured at a more stable position than the bulb sensor. A mouthpiece with a sensor could be used in an individual's oral cavity such that the position was fixed when measuring the tongue pressure. Other techniques had the advantage of being wireless and capable of sensing light. Conclusion : Based on this literature review, it is necessary to facilitate the selection of the best tool for quantitative tongue measurement in dysphagia. The review can also be used to develop a Korean tongue movement tool model that can be used in hospitals and community centers.

• Journal of the Korean Society of Radiology
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• v.16 no.6
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• pp.761-769
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• 2022

Pads with high dielectric materials have been used in a variety of applications to locally improve the field sensitivity and homogeneity of RF pulses in clinical MRI studies. In this study, we aimed to improve such pads in consideration of the practical problems associated with the application of actual clinical images. A high permittivity pad to increase the attenuated B1 field strength was fabricated and tested in 7T MRI. Sim4Life simulation and experimental results show stronger and relatively uniform B1 near field. In order to improve the image quality in the whole cerebellum, known as a region with low sensitivity, a guide was made to reduce the mechanical change of the pad. In order to improve the wearing comfort, the pad was designed by dividing it into upper and lower parts. The facial pad showed an overall signal increase effect in areas such as the turbinate in the nasal cavity. Signal increase was expected in areas such as the frontal lobe and eyes, but the effect was either insignificant or it was difficult to see the effect in the imaging protocol. In conclusion, this paper showed a cerebellar-optimized pad with an improved nasal signal while maintaining its effectiveness.

• The Korea Journal of Herbology
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• v.34 no.4
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• pp.27-35
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• 2019

Objectives : Osteoarthritis is characterized by degeneration of articular cartilage, which is characterized by chronic pain, stiffness and decrease range of motion. The present study was designed to compare the therapeutic effect of Dioscoreae Rhizoma water extract (DRW) and Dioscoreae Rhizoma 30% ethanol extract (DRE) on the monosodium iodoacetate (MIA)-induced osteoarthritis rats. Methods : Osteoarthritis was induced by injection of MIA ($50{\mu}{\ell}$ with $80mg/m{\ell}$) into the knee joint cavity of rats. After adaptation period for seven days, rats were divided by 5 groups (n=10/group): normal group, control group, positive control (indomethacin 5 mg/kg), DRW 200 mg/kg treated group, DRE 200 mg/kg treated group (n=10/group). The hind paw weight distribution was measured with the changes of reactive oxygen species (ROS), peroxynitrite ($ONOO^-$) in articulation tissue. Also, the cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), tumor necrosis factoralpha ($TNF{\alpha}$), interleukin-6 (IL-6), matrix metalloproteinase-1 (MMP-1), and tissue inhibitor of metalloproteinases-1 (TIMP-1) were investigated by western blot analysis. Results : The administration of DRW and DRE significantly decreased the hind paw weight distribution. The ROS and $ONOO^-$ levels of cartilaginous tissue were significantly decreased in DRW and DRE compared to control group. The results showed that DRE decreased inflammatory cytokines such as iNOS and $TNF{\alpha}$. Also DRE decreased MMP-1 and increased TIMP-1. Conclusions : Based on the above results, Dioscoreae Rhizoma extract seems to have the therapeutic effect on osteoarthritis via suppression of inflammation.

• Phonetics and Speech Sciences
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• v.14 no.2
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• pp.77-86
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• 2022

This study aimed to investigate the voice onset time (VOT) of plosives in the VCV syllables by the place of articulation and phonation type spoken by children with bilateral cochlear implants (CIs) in comparison with children with typical hearing (TH). In all, 15 children with bilateral CIs and 15 children with TH participated in this study, aged between 5 to 10 years. All children produced 9 VCV syllables and their VOT were analyzed by the Praat software. There was no significant difference in mean VOT between children with bilateral CIs and children with TH. However, there was a significant difference in mean VOT by the place of articulation, such that the VOT for velars were longer than those for bilabials and alveolars. Additionally, there was a significant difference in mean VOT by the phonation type, such that the VOT of aspirated consonants were longer than those of lenis and fortis consonants. The results of this study suggest that children with bilateral CIs can distinguish the acoustic properties of plosive consonants and control the speech timing between the structures of the larynx and the oral cavity at a similar level as children with TH.

• Journal of Korean Society of Forest Science
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• v.111 no.3
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• pp.374-384
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• 2022

There is an increasing demand for Tetradium daniellii seedlings due to their uses as alternative energy, for ecological restoration, and as a honey plant. This study was conducted to determine the optimum container for superior seedling production of T. daniellii. Experiments were performed using five plastic container types (500, 350, 320, 300, and 250 ml) for forestry facility cultivation. The height and root collar diameter growth of T. daniellii seedlings were significantly high in the 350-ml container. High growth appeared primarily in the container with a larger cavity volume and lower growing density. Root development was most active in full sunlight. The maximum dry matter production was observed in the 350-ml container, which was similar to the results of height and root collar diameter growth. QI, an index showing the quality of a seedling, was maximum at 0.97 in the 350-ml container. In conclusion, the 350-ml container is optimum for superior seedling production of T. daniellii.

• Journal of the Korean Geotechnical Society
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• v.37 no.11
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• pp.93-105
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• 2021

In this study, we evaluated the effect of soil fine contents on the formation of underground cavities and ground cave-ins induced by damaged sewer pipes. Simulating the domestic rainfall conditions and ground conditions, model tests were performed under three different fine particle contents conditions (7.5%, 15%, and 25%). By repeating the groundwater supply and drainage twice, ground settlement and the amount of discharged soil were obtained. Also, digital images were taken at regular time intervals during the model tests, and internal displacement and deformation were measured using PIV technique. As the cycles were repeated, the soil with high fine content showed greater resistance to the formation of underground cavities. The ground cave-ins, identified by the collapse of the surface, occurred only when the fine particle content was 15%. It is presumed to be due to the suffusion phenomenon; further study was needed to investigate the effect of fine particle contents on the suffusion phenomenon and associated changes of soil strength.