• 대한디지털의료영상학회논문지
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• 제16권2호
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• pp.1-7
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• 2014

This study is to increase the accuracy of the diagnosis of benign prostatic hyperplasia by presenting a method that can accurately measure the residual urine amount of the bladder by using an ultrasound image. Agar powder, Propanol and distilled water were used as materials for making a phantom. In order to measure the volume, a $10m{\ell}$ cylinder, syringe and beaker were used. The image was obtained by scanning phantoms produced into six shapes. Each constant value was obtained by using the expression designed to measure the residual urine amount of the bladder and was compared and analyzed. The measuring method of Bladder volume was presented and a constant value for each shape was obtained and five observers measured it five times. According to the results of clinical application, the errors of Ellipse-beanbag, Shield-shield were 11.0%, 18.2%, respectively. Constant values depending on the shape of each phantom were presented in order to accurately measure the volume of the bladder in measuring the amount of residual urine for the diagnosis of benign prostatic hyperplasia. The accuracy of the volume using this was verified statistically(p > 0.05). Therefore, it is considered to be useful in diagnosing benign prostatic hyperplasia by using the ultrasound imaging measuring method presented.

• Corrosion Science and Technology
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• 제15권4호
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• pp.182-188
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• 2016

Significant piping wall thinning caused by Flow-Accelerated Corrosion (FAC) and Erosion-Corrosion (EC) continues to occur, even after the Mihama Power Station unit 3 secondary pipe rupture in 2004, in which workers were seriously injured or died. Nuclear power plants in many countries have experienced FAC and EC-related cases in steam cycle piping systems. Korea has also experienced piping wall thinning cases including thinning in the downstream straight pipe of a check valve in a feedwater pump line, the downstream elbow of a control valve in a feedwater flow control line, and failure of the straight pipe downstream of an orifice in an auxiliary steam return line. Cause analyses were performed by reviewing thickness data using Ultrasonic Techniques (UT) and, Scanning Electron Microscope (SEM) images for the failed pipe, and numerical simulation results for FAC and EC cases in Korea Nuclear Power Plants. It was concluded that the main cause of wall thinning for the downstream pipe of a check valve is FAC caused by water vortex flow due to the internal flow shape of a check valve, the main cause of wall thinning for the downstream elbow of a control valve is FAC caused by a thickness difference with the upstream pipe, and the main cause of wall thinning for the downstream pipe of an orifice is FAC and EC caused by liquid droplets and vortex flow. In order to investigate more cases, additional analyses were performed with the review of a lot of thickness data for inspected pipes. The results showed that pipe wall thinning was also affected by the operating condition of upstream equipment. Management of FAC and EC based on these cases will focus on the downstream piping of abnormal or unusual operated equipment.

• Composites Research
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• 제16권1호
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• pp.26-33
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• 2003

열-음향방출(thermo-acoustic emission)기법을 이용함으로써, 직교형 복합재료적층판의 저온냉각 시에 형성되는 미세손상을 검출하고 평가하여 그 유효성을 검토하였다. 액체질소에 의한 저온냉각($-191^{\circ}C$)으로 생성된 미세손상은 가열-냉각 열부하사이클 시에 발생하는 음향방출(AE)거동의 해석을 통해 평가되었다. 저온냉각에 따른 섬유파단과 모재파손은 초음파 C스캔, 광학현미경, 주사형 전자현미경을 통해 관찰되었으며, 이들 미세파손 모드는 AE신호의 퓨리에 변환(FFT)처리해석, 단시간 퓨리에 변환(STFT)처리해석으로 분류되는 3종류의 서로 다른 특징을 갖는 AE신호로 검출될 수 있었다. 이들 AE신호특성을 시간 단계별로 검출하여 저온냉각시에 형성되는 복합재료 미세파괴의 과정을 실시간으로 평가할 수 있었으며, 또한 열부하 사이클시의 AE신호해석을 통해서 저온 냉각으로 생성된 미세파손의 정도를 추정할 수 있었다.

• Journal of Periodontal and Implant Science
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• 제49권3호
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• pp.193-204
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• 2019

Purpose: The reaction of cells to a titanium implant depends on the surface characteristics of the implant which are affected by decontamination. The aim of this study was to evaluate the cytocompatibility of titanium disks treated with various decontamination methods, using salivary bacterial contamination with dental pellicle formation as an in vitro model. Methods: Sand-blasted and acid-etched (SA) titanium disks were used. Three control groups (pristine SA disks [SA group]; salivary pellicle-coated SA disks [pellicle group]; and biofilm-coated, untreated SA disks [NT group]) were not subjected to any decontamination treatments. Decontamination of the biofilm-coated disks was performed by 14 methods, including ultrasonic instruments, rotating instruments, an air-powder abrasive system, a laser, and chemical agents. MG63 cells were cultured in the presence of the treated disks. Cell proliferation assays were performed on days 2 and 5 of cell culture, and cell morphology was analyzed by immunofluorescence and scanning electron microscopy (SEM). A vascular endothelial growth factor (VEGF) assay was performed on day 5 of culture. Results: The cell proliferation assay revealed that all decontaminated disks, except for the 2 groups treated using a plastic tip, showed significantly less cell proliferation than the SA group. The immunofluorescence and SEM analyses revealed that most groups showed comparable cell density, with the exception of the NT group, in which the cell density was lower and bacterial residue was observed. Furthermore, the cells grown with tetracycline-treated titanium disks showed significantly lower VEGF production than those in the SA group. Conclusions: None of the decontamination methods resulted in cytocompatibility similar to that of pristine SA titanium. However, many methods caused improvement in the biocompatibility of the titanium disks in comparison with the biofilm-coated, untreated titanium disks. This suggests that decontamination is indispensable for the treatment of peri-implantitis, even if the original biocompatibility cannot be restored.

• 한국재료학회지
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• 제31권11호
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• pp.593-600
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• 2021

Herein, a series of g-C₃N₄ modified Bi₂MoO₆ nanocomposites using Bi₂MoO₆ and melamine as original materials are fabricated via sintering process. For presynthesis of Bi₂MoO₆ an ultrasonic-assisted hydrothermal technique is researched. The structure and composition of the nanocomposites are characterized by Raman spectroscopy, X-ray diffraction (XRD), and high-resolution field emission scanning electron microscopy (SEM). The improved photoelectrochemical properties are studied by photocurrent density, EIS, and amperometric i-t curve analysis. It is found that the structure of Bi₂MoO₆ nanoparticles remains intact, with good dispersion status. The as-prepared g-C₃N₄/Bi₂MoO₆ nanocomposites (BMC 5-9) are selected and investigated by SEM analysis, which inhibits special morphology consisting of Bi₂MoO₆ nanoparticles and some g-C₃N₄ nanosheets. The introduction of small sized g-C₃N₄ nanosheets in sample BMC 9 is effective to improve the charge separation and transfer efficiency, resulting in enhancing of the photoelectric behavior of Bi₂MoO₆. The improved photoelectronic behavior of g-C₃N₄/Bi₂MoO₆ may be attributed to enhanced charge separation efficiency, photocurrent stability, and fast electron transport pathways for some energy applications.

• Advances in concrete construction
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• 제13권6호
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• pp.433-450
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• 2022

The conventional disposal methods of waste tires are harmful to the environment. Moreover, the recycling/reuse of waste tires in domestic and industrial applications is limited due to parent product's quality control and environmental concerns. Additionally, the recycling industry often prefers powdered rubber particles (<0.60 mm). However, the processing of waste tires yields both powdered and coarser (>0.60 mm) size fractions. Reprocessing of coarser rubber requires higher energy increasing the product cost. Therefore, the waste tire rubber (WTR) less favored by the recycling industry is encouraged for use in construction products as one of the environment-friendly disposal methods. In this study, WTR fiber >0.60 mm size fraction is collected from the industry and sorted into 0.60-1.18, 1.18-2.36-, and 2.36-4.75-mm sizes. The effects of different fiber size fractions are studied by incorporating it as fine aggregates at 10%, 20%, and 30% in the self-compacting rubberized concrete (SCRC). The experimental investigations are carried out by performing fresh and hardened state tests. As the fresh state tests, the slump-flow, T500, V-funnel, and L-box are performed. As the hardened state tests, the scanning electron microscope, compressive strength, flexural strength and split tensile strength tests are conducted. Also, the water absorption, porosity, and ultrasonic pulse velocity tests are performed to measure durability. Furthermore, SCRC's energy absorption capacity is evaluated using the falling weight impact test. The statistical significance of content and size fraction of WTR fiber on SCRC is evaluated using the analysis of variance (ANOVA). As the general conclusion, implementation of various size fraction WTR fiber as fine aggregate showed potential for producing concrete for construction applications. Thus, use of WTR fiber in concrete is suggested for safe, and feasible waste tire disposal.

• Journal of Periodontal and Implant Science
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• 제53권4호
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• pp.295-305
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• 2023

Purpose: Various methods have been proposed to achieve the nearly complete decontamination of the surface of implants affected by peri-implantitis. We investigated the in vitro debridement efficiency of multiple decontamination methods (Gracey curettes [GC], glycine air-polishing [G-Air], erythritol air-polishing [E-Air] and titanium brushes [TiB]) using a novel spectrophotometric ink-model in 3 different bone defect settings (30°, 60°, and 90°). Methods: Forty-five dental implants were stained with indelible ink and mounted in resin models, which simulated standardised peri-implantitis defects with different bone defect angulations (30°, 60°, and 90°). After each run of instrumentation, the implants were removed from the resin model, and the ink was dissolved in ethanol (97%). A spectrophotometric analysis was performed to detect colour remnants in order to measure the cumulative uncleaned surface area of the implants. Scanning electron microscopy images were taken to assess micromorphological surface changes. Results: Generally, the 60° bone defects were the easiest to debride, and the 30° defects were the most difficult (ink absorption peak: 0.26±0.04 for 60° defects; 0.32±0.06 for 30° defects; 0.27±0.04 for 90° defects). The most effective debridement method was TiB, independently of the bone defect type (TiB vs. GC: P<0.0001; TiB vs. G-Air: P=0.0017; TiB vs. GE-Air: P=0.0007). GE-Air appeared to be the least efficient method for biofilm debridement. Conclusions: T-brushes seem to be a promising decontamination method compared to the other techniques, whereas G-Air was less aggressive on the implant surface. The use of a spectrophotometric model was shown to be a novel but promising assessment method for in vitro ink studies.

• Advances in nano research
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• 제14권5호
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• pp.435-442
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• 2023

Sports activities, including playing tennis, are popular with many people. As this industry has become more professionalized, investors and those involved in sports are sure to pay attention to any tool that improves athletes' performance Tennis requires perfect coordination between hands, eyes, and the whole body. Consequently, to perform long-term sports, athletes must have enough muscle strength, flexibility, and endurance. Tennis rackets with new frames were manufactured because tennis players' performance depends on their rackets. These rackets are distinguished by their lighter weight. Composite rackets are available in many types, most of which are made from the latest composite materials. During physical exercise with a tennis racket, nanocomposite materials have a significant effect on reducing injuries. Materials as strong as graphite and thermoplastic can be used to produce these composites that include both fiber and filament. Polyamide is a thermoplastic typically used in composites as a matrix. In today's manufacturing process, materials are made more flexible, structurally more vital, and lighter. This paper discusses the production, testing, and structural analysis of a new polyamide/Multi-walled carbon nanotube nanocomposite. This polyamide can be a suitable substitute for other composite materials in the tennis racket frame. By compression polymerization, polyamide was synthesized. The functionalization of Multi-walled carbon nanotube (MWCNT) was achieved using sulfuric acid and nitric acid, followed by ultrasonic preparation of nanocomposite materials with weight percentages of 5, 10, and 15. Fourier transform infrared (FTIR) and Nuclear magnetic resonance (NMR) confirmed a synthesized nanocomposite structure. Nanocomposites were tested for thermal resistance using the simultaneous thermal analysis (DTA-TG) method. scanning electron microscopy (SEM) analysis was used to determine pores' size, structure, and surface area. An X-ray diffraction analysis (XRD) analysis was used to determine their amorphous nature.

• Restorative Dentistry and Endodontics
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• 제48권3호
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• pp.28.1-28.13
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• 2023

Objectives: This study aimed to investigate the effect of the application method of 2% chlorhexidine (CHX) and its influence on the adhesion of fiberglass posts cemented with a self-adhesive resin cement. Materials and Methods: Sixty human mandibular premolars were endodontically treated and divided into 5 groups (n = 12), according to the canal irrigant and its application method: 2 groups with conventional syringe irrigation (CSI)-2.5% sodium hypochlorite (NaOCl) (control) and 2% CHX- and 3 groups with 2% CHX irrigation/activation-by passive ultrasonic irrigation (PUI), Easy Clean file, and XP-Endo Finisher file. Two roots per group were evaluated for smear layer (SL) removal by scanning electron microscopy. For other roots, fiber posts were luted using a self-adhesive resin cement. The roots were sectioned into 6 slices for push-out bond strength (BS) (7/group) and nanoleakage (NL) (3/group). Data from SL removal were submitted to Kruskal-Wallis and Student-Newman-Keuls tests (α = 0.05). Data from BS and NL were evaluated by 2-way analysis of variance and Tukey's test (α = 0.05). Results: For SL removal and BS, the CHX irrigation/activation promoted better values than CSI with CHX (p < 0.05), but it was not significantly different from CSI with NaOCl (p > 0.05). For NL, the lowest values were obtained by the chlorhexidine irrigation/activation groups (p < 0.05). Conclusions: Active 2% CHX irrigation can be used to improve the post space cleaning and adhesion before fiber post cementation with self-adhesive resin cements.

• 대한치과보철학회지
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• 제51권3호
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• pp.167-174
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• 2013

연구 목적: 본 연구는 서로 다른 세가지 블라스팅 처리를 한 티타늄 디스크에$Nd:YVO_4$ 레이저 조사 조건을 달리한 후 조사하여 티타늄의 표면 거칠기 및 표면 변화를 관찰하기 위함이다. 연구 재료 및 방법: 디스크 형태의 상용 순수 티타늄 시편을 30개 준비하여 시료 표면을 각각 10개씩 $ZrO_2$ (zirconium dioxide), $Al_2O_3$ (aluminium oxide), RBM (resorbable blasted media)으로 블라스팅(blasting)하고 초음파 세척하였다. $Nd:YVO_4$ 레이저(Laser Pro D-20, Laserval $Korea^{(R)}$, Seoul, South Korea)에서 주사속도(100, 300, 500 mm/s)와 시간당 진동량(반복률) (5, 15, 35 kHz)을 다르게 하여 9가지 조건을 설정하였다. 레이저 조사 후 주사전자현미경, X-선 회절 분석 및 에너지 분산X선 분광분석, 표면 거칠기 분석을 통해 각 시편을 평가하고 분석하였다. 결과: 주사전자현미경의 결과 레이저 조사를 시행하지 않은 티타늄 표면은 방향성이 없는 불규칙한 형상을 보였고 레이저 조사를 처리한 시편은 특징적인 형태가 관찰되었다. X-선회절분석결과$ZrO_2$, RBM 의 고유피크는 관찰되지 않았으나 $Al_2O_3$분사한 군에서는 알루미나의 고유 피크가 관찰되었다. 에너지 분산X선 분광분석을 통해 관찰한 티타늄의 산화도 경향성과 표면 거칠기는 유사하였다. 표면 거칠기는 주사속도와 반복률에 따른 차이를 보였다(P<.05). 결론: 레이저 조사 조건에 따라 티타늄 디스크의 미세구조와 표면 거칠기가 변화되었다. 레이저 조사는 골유착을 증진시키기 위한 임플란트 표면을 변화시키는 방법중의 하나로 여길 수 있을 것이다.