• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.36 no.3
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• pp.292-297
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• 2023

Triboelectric devices are attracting attention from researchers as self-powered electronic systems that can instantly convert mechanical input into electrical energy output. To improve triboelectric energy harvesting performance, increasing the number of contacts as well as the contact area has been carried out by numerous researchers. In this study, we design a shaker-type energy harvester which is called as maracas triboelectric generator (M-TEG), inspired by the structure of maracas, one of the musical percussion instruments. A tripod frame is inserted to the inside of a cylindrical case, which is a device with the electrodes of aluminum and copper. Then, the triboelectric energy harvesting characteristics between polypropylene (PP) balls and the electrodes are measured. The M-TEG with the frame generates the energy harvesting signals up to ~100 V and ~2.5 ㎂ due to larger contact area and numbers, which enhances the voltage and current output by 250% and 610% compared to that without the frame, respectively. This study presents the feasibility of self-powered sensors and toys using improved triboelectric energy performance with a low-cost and simple manufacturing process in the interesting structure.

• CELLMED
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• v.12 no.1
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• pp.1.1-1.2
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• 2022

Mental health is attributed to person's well-being, abilities and productivity. The purpose of this study is to suggest the effects of K-culture to people in adversity. It is PungmulPanGut, represented by traditional Korean play culture. Pungmul is a performance with four percussion instruments, Janggu (Korean hourglass drum), Buk (barrel shaped drum), Jing (large gong), Kkwaenggwari (small gong), and play. In Korean, "pan" means that it's a place to do something. Gut means to make a wish. The ensemble Better Than Medicine (eBTM) is a team that has trained and worked with Gamuak (歌,舞,樂; singing, dancing, playing) for a long time, but is not perfect (we refer this as 2% lacking in music). The characteristic of our team is that we share joy while voluntarily participating and doing what we like. It is a combination of singing, dancing, playing musical instruments, and exciting people. There is wind-like energy and there is mutual cooperation, not competition. As we concentrate, we become immersed in each other's breathing and movement. So it makes us forget the hard situation, the hardships, the pain, and so on. In the meantime, our pleasures peak and share happy energy with each other. Even though we are two percent less skilled, our sense of happiness doubles. Music together is not competition but cooperative work and healing. Therefore, we suggest that PungmulPanGut can be better K-culture than medicine in promoting mental health.

• Restorative Dentistry and Endodontics
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• v.47 no.3
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• pp.34.1-34.12
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• 2022

Objectives: This study aimed to evaluate the success rate of endodontic treatments performed by undergraduate students and the factors associated with the outcome. Materials and Methods: A follow-up of 3 to 8 years after root canal filling was carried out in 91 patients. At the follow-up visits, medical and dental history questionnaires were applied along with clinical and radiographic examinations. Data collected in the clinical exam included: the presence of pain, swelling, sinus tract, mobility, tenderness to palpation and percussion, periodontal probing profile, and type/quality of coronal restoration. Postoperative and follow-up radiographs were digitalized and analyzed by 2 trained and calibrated examiners to assess periapical healing. The treatment outcome was based on strict clinical and radiographic criteria and classified as success (absence of any clinical and radiographic sign of apical periodontitis) or failure (other combination). Logistic regression was used to investigate the impact of clinical and radiographic variables on endodontic treatment outcomes at a 5% significance level. Results: The success rate of endodontic treatments was 60.7%. The only risk factor significantly associated with failure was the presence of a periapical lesion on the postoperative radiograph (odds ratio, 3.35; 95% confidence interval, 1.17-9.54). Conclusions: The success rate of endodontic treatments performed by undergraduate students was low and was jeopardized by the presence of a periapical lesion on the postoperative radiograph.

• (The) Research of the performance art and culture
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• no.37
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• pp.157-186
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• 2018

Ulsan Soeburi song was reenacted in the 1980s based on the testimony and songs of late Choi Jae man (1987 death), the last blacksmith of the iron production plant at Dalcheon dong, Ulsan in August 1981. The purpose of this study is to analyze Soeburi song from the musical perspective based on 13 kinds of data including video in 1981, and confirm the changing patterns in the tradition process. The derived results are summarized as follows. In the results of examining Soeburi Song data in 2017, the percussion instruments consist of kkwaenggwari 2 (leading small gong 1, follow small gong 1), jing 2 (large gong 2), buk 4 (drum 4), janggu 4 (double headed drum 4), taepyongso 1 (Korean shawm 1), and Jangdan (rhythm) consists of five such as Jilgut, Jajinmori, Dadeuraegi, Deotbaegi, Jajin Deotbaegi. The vocal songs are sung accompanied by the Deotbaegi Jajin Deotbaegi (beat) of quarter small triplet time, or without accompaniment. The scale is mostly Mi La do's third note or Mi La do re's fourth note, and the range does not exceed one octave. All the cadence tones are the same as La. From the results of observing Soeburi song performance until today after the excavation in 1981, it is found that there are four major changes. First, the composition of the music is differentiated into 'long Jajin (slow fast)', and , , and are added. Second, the singing method is based on 'single cantor + multi post singers' since 1980's reenactment, and a single post singer was also specified from time to time. In addition, , which was performed in 2013, became the foundation of . Third, a melodic change of was observed. All beat structures are quarter small triplet time, but the speed gets slow, Mi La do's three notes are skeletonized to be corrected with high re and low sol, and then the characteristics of Menari tori (the mode appeared in the eastern province of the Korean peninsula) are to be clear. Lastly, the four percussion instruments such as kkwaenggwari, jing, janggu, and buk are frequently used, and depending on the performance, sogo (hand drum), taepyongso, yoryeong (bell) are also added. Jangdan played Jajinmori, Dadeuraegi, Deotbaegi and Jajin Deotbaegi from the beginning, and thereafter, the Jilgut Jangdan was added. Through these results as above, it is confirmed that at the time of the first excavation, a simple form of such as has been changed into a male labor song, the purpose of which has changed, and that the playability has become stronger and changed into a performing arts.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.7
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• pp.4828-4834
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• 2015

From the moment that a firing pin triggers the detonator to the moment that a grenade leaves a barrel is called Action Time. Since a loading and percussion of 40mm grenade happens simultaneously, action time should be within a certain time in order to prevent a Jamming malfunction. Previously, unreliable action time device of 40mm grenade made it difficult to improve quality assurance of K4 Grenade Machine Gun. Here, various sensors were compared and a special device was designed to seek an accurate measurement on action time. In this device, the gap between a signal from an optical sensor in Firing Pin and that from Eddy current probe in the barrel was recorded and data were sent to a computer in real time. Confirming if action time is within the criteria, it is expected that action time plays an important role in quality assurance on 40mm grenade.

• Journal of the korean academy of Pediatric Dentistry
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• v.43 no.4
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• pp.452-460
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• 2016

Burkitt lymphoma (BL) is an aggressive form of non-Hodgkin's B-cell lymphoma found primarily in the pediatric population. In the oral cavity, this tumor can grow rapidly and often brings about facial swelling or development of an exophytic mass involving the jaws. A 5-year-old boy was referred for swelling and pain in the left mandibular area. The patient showed diffuse swelling on the left side of the mandible and firm-moderate tenderness upon palpation. An intraoral examination showed moderate mobility and sensitivity to percussion on the left primary first and second molars, without severe caries. A radiographic examination revealed complete loss of the lamina dura on the left primary second molar and permanent first molar. There was a radiolucent osteolytic lesion and destruction of the cortical bone of the left mandibular body. Based on the clinical, radiographic, and immunohistochemical findings, the patient was diagnosed with BL, and was referred to a pediatrician for systemic evaluation and intensive chemotherapy. Even before the completion of chemotherapy, the swelling resolved and the displaced teeth were relocated to a normal position. This patient showed a good prognosis due to prompt diagnosis and intensive chemotherapy. Early diagnosis and referral for treatment can prevent the development of BL.

• Restorative Dentistry and Endodontics
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• v.36 no.3
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• pp.196-202
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• 2011

Objectives: The aim of this study was to investigate levels of matrix metalloproteinase-8 (MMP-8) and substance P (SP) in root canal exudates during root canal treatment (RCT) of nonvital, painful teeth. Materials and Methods: Patients scheduled for nonsurgical RCT were prospectively selected; the study was performed after obtaining informed consent from the patients and was approved by the Institutional Review Board for Clinical Research of Gangnam Severance Hospital, Yonsei University (3-2008-0118). Canal exudates samples were collected using sterilized paper points from teeth scheduled for RCT across three different time periods. MMP-8 and SP levels were measured using enzyme-linked immunosorbent assay (ELISA). Data were analyzed using a mixed model analysis and the Pearson correlation analysis (p < 0.05). Results: MMP-8 and SP levels in GCF were decreased during RCT (p < 0.0001), and they showed a weak positive correlation to each other (p < 0.05). Patients' subjective pain levels and the response from percussion test were significantly related to SP level. Conclusions: This study demonstrated that periradicular inflammation endodontic origin can elevate SP and MMP-8 levels in root canal exudates. Interestingly, SP level of canal exudates showed a possibility of being used as an indicator of pain due to periapical pathosis.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.12
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• pp.327-332
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• 2016

Sting (Gordon Sumner) is a British musician and singer-songwriter. He was the principal songwriter, lead singer, and bassist for the new wave rock band 'The Police' from 1977 to 1984, before launching a solo career in 1985. With his stylish and sophisticated sensibility and musical spectra, he achieved 100 million album sales. In this thesis, after he disbanded the group THE POLICE, his career as a solo artist with his wide variety of musical colors has been acknowledged for his reputation over more than 30 years. Therefore, I analyze 'Sting' of music included in 'Straight To My Heart' and 'Be Still My Beating Heart' in. Songs in indicate that the drum part the tunes that there is in a record doesn't break away from the basic way of music. The role of the whole rhythm division through the various percussions or can see a synthesizer than the role as the cord musical instrument that there are lots of tunes placing a great deal of weight on the role as the rhythmic musical instrument more. The unique instrument-based rhythm of the early Sting and role dispensation create a unique sound that is quite different from what the musician subsequently recorded. The feature and rhythmic characteristic, which is the arrangement that appeared outstandingly in this record, I am trying to explain about the way in which I lead the basic flow of the tune through the rhythm division of the other musical instruments which I split that is, the drum beat and break away from a rhythm from the divided general way and include a percussion.

• Journal of dental hygiene science
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• v.14 no.4
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• pp.589-596
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• 2014

This study was designed to investigate the using status and awareness of pit and fissure sealant, and how it affects on secondary caries when performed on above of initial caries. After classifying 446 occlusal surface into four groups, performed pit and fissure sealant, induced artificial caries, used DIAGNOdent (Kavo) to measure degree of secondary caries. Also, distributed a questionnaire on dental clinic in metropolitan area to find out using status and awareness of pit and fissure sealant, the following results were obtained. 1) On inspection and percussion, Group 4 corresponding to the enamel caries showed the highest secondary caries after sealant and was statistically significant difference in the order of initial group, stained group, sound group (p<0.05). 2) Inspection showed the highest percentage on tooth fissure caries diagnostic methods before sealant. 3) 56.6% didn't know about DIAGNOdent, 91.6% didn't have it. 4) In clinically, the most cause of secondary caries after sealant was a broken sealant, making caries on the downward. Based on the results of above study, degree of caries under sealant could affect on secondary caries, needs publicity about the use and necessity of objective fluorescence device.

• The Journal of Advanced Prosthodontics
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• v.3 no.4
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• pp.229-235
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• 2011

PURPOSE. The aim of this retrospective study was to evaluate cumulative survival rate (CSR) of Implantium implants followed for 5 years and association between risk factors and the CSR. MATERIALS AND METHODS. A total of two hundred forty-nine Implantium Implants System (Dentium, Seoul, Korea) placed in ninety-five patients from 2004 to 2009 were investigated with several identified risk factors (sex, systemic disease, smoking, alchohol, reason of tooth loss, length, arch (maxilla or mandible), replace tooth type (incisor, canine, premolar or molar) Kennedy classification, prosthodontic type, prosthodontic design, opposite dentition, abutment type, occlusal material, occlusal unit, splint to tooth, cantilever, other surgery). Clinical examination (mobility, percussion, screw loosening, discomfort, etc.) and radiographic examination data were collected from patient records including all problems during follow-up period according to protocols described earlier. Life table analysis was undertaken to examine the CSR. Cox regression method was conducted to assess the association between potential risk factors and overall CSR. RESULTS. Five of 249 implants were failed. Four of these were lost before loading. The 5-year implant cumulative survival rate was 97.37%. Cox regression analysis demonstrated a significant predictive association between overall CSR and systemic disease, smoking, reason of tooth loss, arch, Kennedy classification and prosthodontic design (P<.05). The screw related complication was rare. Two abutment screw fractures were found. Another complications of prosthetic components were porcelain fracture, resin facing fracture and denture fracture (n=19). CONCLUSION. The 5-year CSR of Implantium implants was 97.37 %. Implant survival may be dependent upon systemic disease, smoking reason of tooth loss, arch, Kennedy classification and prosthodontic design (P<.05). The presence of systemic diseases and combination of other surgical procedures may be associated with increased implant failure.