• Restorative Dentistry and Endodontics
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• 제38권3호
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• pp.154-159
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• 2013

Objectives: The aim of this study was to compare the cleaning efficacy of different final irrigation regimens in canal and isthmus of mandibular molars, and to evaluate the influence of related variables on cleaning efficacy of the irrigation systems. Materials and Methods: Mesial root canals from 60 mandibular molars were prepared and divided into 4 experimental groups according to the final irrigation technique: Group C, syringe irrigation; Group U, ultrasonics activation; Group SC, VPro StreamClean irrigation; Group EV, EndoVac irrigation. Cross-sections at 1, 3 and 5 mm levels from the apex were examined to calculate remaining debris area in the canal and isthmus spaces. Statistical analysis was completed by using Kruskal-Wallis test and Mann-Whitney U test for comparison among groups, and multivariate linear analysis to identify the significant variables (regular replenishment of irrigant, vapor lock management, and ultrasonic activation of irrigant) affecting the cleaning efficacy of the experimental groups. Results: Group SC and EV showed significantly higher canal cleanliness values than group C and U at 1 mm level (p < 0.05), and higher isthmus cleanliness values than group U at 3 mm and all levels of group C (p < 0.05). Multivariate linear regression analysis demonstrated that all variables had independent positive correlation at 1 mm level of canal and at all levels of isthmus with statistical significances. Conclusions: Both VPro StreamClean and EndoVac system showed favorable result as final irrigation regimens for cleaning debris in the complicated root canal system having curved canal and/or isthmus. The debridement of the isthmi significantly depends on the variables rather than the canals.

• Journal of Radiation Protection and Research
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• 제40권2호
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• pp.101-109
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• 2015

대기 중에 존재하는 우라늄 동위원소 분석을 위해서 일반적으로 알파분광분석법(alpha spectrometry)이 사용되고 있으며, 정확한 분석을 위해서는 정밀한 방사화학 전처리가 요구된다. 보편적인 방사화학 전처리 방법으로는 회화법(ashing method) 및 알칼리 용융법(alkali fusion method)가 있다. 그러나 회화법의 경우 전처리 시간이 길어 빠른 분석이 어렵다는 단점이 있으며, 이와 달리 알칼리 용융법은 단시간 내에 전처리가 가능하다는 장점은 있으나 보편적으로 전처리 장비의 무게가 무겁고 분석 소요 비용 역시 상당히 높다는 단점이 있다. 이러한 단점들은 신속한 분석 결과가 요구되는 방사능 사고 분석 또는 IAEA 안전조치 물자재고 검사(Physical Inventory Verification, PIV) 수행시, 효율성을 저하시키는 원인이 된다. 이에 본 연구에서는 간편하면서도 주어진 짧은 시간 내에 공기 중 우라늄 동위원소 분석을 완료하는 것을 목적으로, 초음파 세척법(ultrasonic cleaning method)을 이용한 새로운 방사화학 전처리 방법을 개발하였다. 또한 초음파 세척법의 효율성 분석을 위해 전처리 소요시간, 편의성, 소요비용, 우라늄 동위원소 회수율의 측면에서 기존의 방법들과 비교 분석하였다. 동일 조건의 공기 포집시료에 대해 비교실험을 수행한 결과, 본 연구에서 개발한 초음파 세척법을 활용한 공정은 상대적으로 전처리 시간도 짧고, 이동이 간편하며, 저가이며, 단순함에도 불구하고 기존 방식과 비교하여 유사한 회수율을 보였다.

• 비파괴검사학회지
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• 제27권3호
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• pp.224-230
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• 2007

This work is aimed to explore a possibility of using the generalized Lamb waves for nondestructive evaluation of the bonding quality of layered substrates. For this purpose, we prepared two sets of specimens with imperfect bonding at their interfaces; 1) TiN-coated specimens with various wear conditions, and 2) CVD diamond specimens with various cleaning conditions. A dispersion simulation performed for layered substrates with imperfect interfaces are carried out to get the characteristics of dispersion curves that can be used for bonding quality evaluation. Then the characteristics of dispersion curves of the fabricated specimens are experimentally determined by use of an ultrasonic backward radiation measurement technique. The results obtained in the present study show that the lowest velocity mode (Rayleigh-like) of the generalized Lamb waves are sensitively affected by the bonding quality. Therefore, the generalized Lamb waves can be applied for nondestructive evaluation of imperfect bonding quality in various layered substrates.

• 한국염색가공학회지
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• 제23권4호
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• pp.290-297
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• 2011

In this study, the possibility of the practical development of highly sensitive clothing textiles using fibrillated wool fibers were considered by determining the dyeability, the physical and mechanical properties of fibrillated wool fibers treated under strong acid and high temperature ultrasonic wave irradation and they were compared with those of untreated wool fibers. The color strengths of the dyed fibrillated wool fabrics increased by the acid metal complex dyes contrary to the untreated wool fabrics, and color fastness properties to rubbing, light, and dry cleaning were excellent, similar to those of the untreated wool fabrics. The tensile strengths of fibrillated wool fabrics were also kept after the dyeing. Moreover, the Numeri, Fukurami, and THV of the fibrillated wool fabrics were better than those of the untreated wool fabrics.

• 한국자동차공학회논문집
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• 제7권9호
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• pp.36-47
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• 1999

Three-way catalyst converter, cleaning up the exhaust gas contamination of SI engine, has the best efficiency when A/F ratio is near the stoichiometry . The feedback control using oxygen sensors in the exhaust manifold has limits caused by the system delays. So the accurate measurement of air flow rate to an engine is essential to control the fuel injection rate especially on transient condition like the rapid throttle opening and closing. To measure the rapid change of flow rates. the air flow meter for the engine requires quick response, flow reversal detection, and linearity . Tjhe proposed integration type air flow meter (IFM), composed of an ultrasonic flow meter with an integration circuit, has significantly improved the measurement accuracy of air mass inducted through the throttle body. The proposed control method estimated the air mass at the cylinder port using the measured air mass at the throttle . For the fuel dynamic model, the two constant fuel model is introduced . The control parameters from air and fuel dynamics are tuned to minimize the excursion of the air fuel ratio. As a result A/F ratio excursion can be reduced within 5% when throttle rapidly opens and closes at the various engine conditions.

• 한국기계가공학회지
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• 제19권2호
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• pp.1-8
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• 2020

While dental clinics still use the ultrasonic scaling/surgery tool for teeth scaling and cleaning the tool's use is expanding steadily to include treatment of damaged teeth and bone tissue. In this study, a handpiece moving system (HMS) was developed to evaluate bone scaling and cutting in the field of dentistry. The HMS, through a scaling test of bone using a scaler tip, it was able to identify surface damage. Additionally, a thermos-graphic camera was used to observe the temperature distribution that occurred during the bone scaling and cutting process. Consequently, we found that increasing the working load increased the amount of surface damage. Changes in temperature distribution occurred slowly and were maintained within safety bounds for 10 minutes. Going forward, we will compare the HMS performance on scaling and cutting with other devices.

• 한국음향학회지
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• 제16권5호
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• pp.12-17
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• 1997

본연구에서는 압전세라믹을 이용하여 외부에 노출된 유리판에 부착된 물방울을 효율적으로 제거할 수 있는 초음파 물기 제거장치를 개발하였다. 초음파 진동장치의 제작을 위하여 유한요소법을 사용하여 유리면의 진동특성을 분석하였고 이 결과를 바탕으로 체적의 효과를 얻을 수 있는 초음파 진동액츄에이터의 구조와 규격을 결정하였다. 진동장치의 제작에 있어서는 시뮬레이션 결과를 바탕으로 진동의 균일한 분포를 위해서 보조진동판을 사용하였고 주어진 크기의 유리판의 최적조건을 찾기 위해 보조진동판과 유리판의 다양한 두께와 압전소자의 크기와 두께에 따라서 그 특성을 알아보고 성능을 평가하였다. 구동 발진기는 유리판의 공진점을 추적하기 위해 일정 주파수대역을 스위핑하는 가변주파수 발진기로 제작하였다.

• 한국전기전자재료학회논문지
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• 제36권2호
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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.

• 한국방재안전학회논문집
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• 제17권1호
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• pp.27-35
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• 2024

본 논문은 순환골재 표면에 부착된 시멘트 페이스트 및 모르타르를 제거하는 데 있어 화학적 중화반응 및 초음파 세척의 적용 가능성을 평가하기 위한 실험적 연구 결과를 제시한다. 최적의 초음파 세척 효율 및 화학적 중화반응을 도출하기 위하여 초음파 진동수, 화학용액의 종류 등을 변수로 한 실험이 수행되었다. 그 결과 최적 진동수는 24 kHz로 나타났으며, 염산 15% 용액에 침지시킨 후 30분 가진하는 것이 최적 조건이라는 결론이 도출되었다. 또한, 품질 개선된 순환 굵은 골재의 비중, 흡수율, 마모율은 일반골재와 유사하며 KS F 2527 기준을 모두 만족하는 것으로 나타났다. 따라서, 본 연구를 통해 제안된 방법을 통해 품질 개선된 순환골재는 콘크리트용으로 사용이 가능할 것으로 판단된다.

• 대한치과의사협회지
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• 제53권10호
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• pp.743-750
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• 2015

Objectives: This study compared the mechanical efficacy of sonic activated and passive ultrasonic irrigation for removing intracanal medicament from a simulated root canal under controlled conditions. Materials and Methods: Thirty simulated root canal in resin blocks were randomly divided into 3-groups. The canals were enlarged using ProTaper files and K3XF (#30/0.06). After cleaning and drying, canals were filled with Calcipex. Overfilled materials were wiped out and measured their weight to the unit of 1/10mg. After one week storage in 100% humidity $37^{\circ}C$ temperature, canals were irrigated using 20mL of saline with one of following methods according to the designated groups (n = 10). For group-NI, 30-gauge nickel-titanium irrigation needle was used. During irrigation with every 5mL, needle was moved in-and-out with 4-mm amplitudes. EndoActivator and ultrasonic tip were used for group-EA and group-UT respectively for 20 seconds after every 5mL irrigation using needle. Then the weight was measured again to calculate the weight of residual remnants. The data were analyzed by one-way ANOVA and Duncan's post-hoc test at a significance level of 95%. Results: The weight of the residual medicaments were $3.62{\pm}0.81mg$, $2.84{\pm}0.28mg$, and $2.73{\pm}0.90mg$ for group-NI, -EA, and -UT, respectively. Group-EA and group-UT had no significant differences to remove intracanal medicament and left significantly less amount of paste than group-NI (p < 0.05). Conclusions: Under the controlled conditions of this study, the sonic activation and PUI have similar mechanical efficacy for removing intracanal medicament.