• 대한인간공학회지
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• 제32권5호
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• pp.421-427
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• 2013

Objective: This paper is to analyze the impact of musical training to the fast ${\alpha}$ wave activation of the EEG. Background: EEG is neurological research method that can observe the brain function in real time. EEG can be used to determine the nervousness and relaxedness of a person who receives stimuli in a structured environment. Therefore, it is possible to interpret the functional state of human brain by the analysis of EEG. Method: The brain activities of two groups of university students in the point of RFA(Relative Fast Alpha) caused by different music are analyzed in this paper. One is the group of music majors and the other is the group of non-majors. Results: Music major and non-major groups show meaningful differences in RFA during exposed to classic and metal music. Conclusion: Learning experience on music affects RFA increment of music majors. Application: The result of this study will be used as basic data to evaluate the learning effects of students who want to study music.

• 대한치과보철학회지
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• 제43권1호
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• pp.78-94
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• 2005

Purpose. The purpose of this study was to compare the effects of various surface treatments by measuring resonance frequency and histomorphometric analyses. Material and methods. In 5 adult dogs, the mandibular premolar were extracted. Six months later, 30 screw titanium implants (Dentium Co., Seoul, Korea) 6mm in length and 3.4mm in diameter, were placed in the mandibles of 5 dogs. Implants were divided into five groups following to surface treatment methods ; Group 1 is machined controls, Group 2 is sandblasted with large grit and acid-etched (SLA), Group 3 is anodized (Autoelectric Co., Korea, 660Hz, Duty10), Group 4 is hydroxyapatite(HA) coated by ion beam assisted deposition(E-beam), Group 5 is hydroxyapatite(HA) coated with Sol-gel coating process. Resonance frequency was measured implant placement immediately, and 3, 6 weeks and 10 weeks of healing perods. With the animal subject's sacrifice 10 weeks after implantation, implants were removed on bloc and histologic and computer-based histomorphometric analyses were performed. Histomorphometric analysis involved quantification of the entire bone to metal contact around the implants. Statistical analyses were performed using the SPSS for Windows (ver. 9.0 SPSS Inc.) Statistical differences were considered significant at P<0.05. Results. The results were as follows : 1) In five groups, mean value of resonance frequency analysis(RFA) were highest in group 5 (Sol-gel implant) at implantation and those of group 4 (E-beam)was highest at 10 weeks . but there was no correlation between surface treatments and RFA. 2) In all surface treatment groups, the RFA values of implants decreased until 3 weeks and increased to 10 weeks. 3) The percentage of direct bone-to-implant contact (BIC) had statistical significance between five groups in cancellous bone, (P<0.05) the percentage of bone density inside the thread had no statistical significance between five groups. (P>0.05) 4) There was a significant difference between cortical bone and cancellous bone in BIC. (P<0.05) and bone density. (P<0.05) 5) There was a correlation between the RFA value of implants at 10 weeks and BIC in cancellous bone, and between the RFA value of implants at 10 weeks and bone density in cortical bone. (P<0.05). Conclusions. These results indicate that surface treatment does not affect the implant stability in case of good bone quality.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2021년도 학술발표회
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• pp.406-406
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• 2021

극한강우사상의 분석은 다양한 극치 분포로 구성된 극치이론을 통해 가능하다. 일반적으로 단일 지점의 극한사상의 분석을 위한 지점빈도해석 (Point Frequency Analysis, PFA)이 다양한 재현기간에 해당하는 강우량을 추정하는데 널리 사용되어왔다. 하지만 수문기후학적 극치기록은 시간적 그리고 공간적으로 제한적이다. 따라서 모의 불확실성을 줄이고 신뢰성 높은 결과를 도출하기 위해 서로 유사한 분포를 가질 수 있는 인근 지점의 활용하는 지역빈도해석 (Regional Frequency Analysis, RFA) 방법이 개발되어 적용되고 있다. 본 연구에서는 부산, 울산, 경남지역의 기상청 종관기상관측시스템(Automated Synoptic Observing System, ASOS) 울산, 부산, 통영, 진주, 거창, 합천, 밀양, 산청, 거제, 남해지점 일강수량을 자료를 기반으로 Metropolis-Hasting 알고리즘을 사용하여 일반극치분포(Generalized Extreme Value, GEV)의 매개변수를 추정하고 PFA 및 RFA의 불확실성을 평가하고자 한다. 이러한 연구는 공간적 구성 요소(예, 지리적 좌표, 고도)를 고려하지 못하며 추가변수 (예, 공변량)를 분석에 결합할 수 없는 등의 RFA의 한계를 극복하고, 명시적으로 불확실성을 추정하여 결과의 신뢰성을 확보 할 수 있는 계층적 베이지안 모델의 개발에 도움이 되리라 기대된다.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제30권6호
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• pp.554-560
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• 2008

In posterior maxilla, it is difficult to achieve primary stability of implants due to sinus pneumatization, alveolar bone loss, and low bone quality. The accurate and objective primary stability assessment is important for good prognosis of implants. Purpose: The aim of this study was to assess the primary stability of the non-submerged, internal type implants with maxillary sinus augmentation using deproteinized bovine bone mineral by a resonance frequency analyzer, when residual alveolar bone height is under 8mm Materials and methods: A total of 20 implants was placed into 5 grafted maxillary sinuses in 5 patients. Deproteinized bovine bone mineral (Bio-$Oss^{(R)}$) was used as graft material. SS II implants (diameter 4.1mm, and length 11.5mm, SLA suface)) were placed. All of the patients received maxillary sinus graft procedure by 1-step technique. Residual bone height was $1.3{\sim}7.8mm$ (mean 4.4mm) measured by panorama radiography. After implant placement, RFA was measured at 4,8,12,20 weeks. The results were divided into 2 groups; RFA value under 4mm and over 5mm of bone height. It was statistically analyzed. Results: 1. The primary stability of implants was increased with time 2. The RFA value was above 65 ISQ at 12 weeks 3. There was no correlation between RFA and residual alveolar bone height in maxillary sinus augmentation by 1-step technique. Conclusion: 1-step surgical procedure is a feasible option for patients with as little as 4mm residual alveolar bone height, when utilizing non-submerged, internal type implants with xenografts.

• Journal of Korean Dental Science
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• 제4권1호
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• pp.26-32
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• 2011

Purpose: The quality of implant surface is one of the factors that influence wound healing of implant site and subsequently affect osseointegration. The objective of modification of the surface properties of an implant is to affect the biological consequence. The purpose of this study is to evaluate the biologic response of osseous tissue to anodized implants. Materials and Methods: Two machined titanium implants for control group were installed in a tibia of each rabbit and two anodized implants for test group were installed in the other tibia of each rabbit. At the moment the implants were installed, resonance frequency analysis (RFA) values were measured. After healing periods of 1, 2, 3, and 7 weeks, the implants were uncovered and RFA values were measured again. Removal torque was measured for one implant in the test group and one implant in the control group. Histological evaluation was executed in the other implants. Results: Both of test group and control group have the tendency of greater RFA change rate and removal torque value as healing periods became longer, but were statistically insignificant (P>0.05). However, in the case of the same healing period, the test group tended to have greater RFA change rate and removal torque than the control group (P<0.05). More active new bone formation from endosteal surface was noted on the anodized surface than machined surface in specimen after 1 week. There were no significant differences between the test group and control group in histological evaluations. Conclusion: In summary, the anodized surface showed slightly favorable results and it is postulated that it may facilitate improved stability in bone.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제29권5호
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• pp.383-393
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• 2007

The aim of the present study is to investigate the effect of anodized surface of osseointegration implants by using of resonance frequency analysis (RFA) and histomorphometric analysis. A total of 96 screw-shaped implants were devided into 4 groups. Seventy-two implants were prepared by electrochemical oxidation with 3 different ways; Group 1 (n=24) were prepared at galvanostatic mode in 0.25M sulfuric acid and phosphoric acid, Group 2 (n=24) were prepared at galvanostatic mode in calcium glycerophosphate and calcium acetate, and Group 3 (n=24) were prepared at galvanostatic mode in 0.25M sulfuric acid and phosphoric acid followed by Calcium metaphosphate(CMP) coating. Control group (n=24) were the RBM surfaced implants. The implants were placed in the mandibles of 12 mini pigs. Bone tissue responses were evaluated by resonance frequency analysis(RFA) and histomorphometric analysis that were undertaken at 2, 4 and 6weeks after implant placement. The following result were obtained. 1. Twenty-two of 96 implants (4 in control group, 5 in group 1, 7 in group 2, and 6 in group 3) were failed due to faliure of osseoitegration. The failure rate of osseointegration was 22.9%. 2. The mean values of RFA in control, group 2 and groups 3 showed the similar values, but there was no significant difference among groups. 3. Histomorphometric evaluation demonstrated significantly higher bone-to-implant contact ratio in group 2 at 3 and 4 weeks after implant placement than other groups (p<0.05), but there was no significant difference among groups at 6weeks after implant placement.

• 대한치과보철학회:학술대회논문집
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• 대한치과보철학회 2006년도 춘계학술대회 및 제3차 한일 공동 국제 학술대회
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• pp.102-102
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• 2006

• Journal of Periodontal and Implant Science
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• 제50권1호
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• pp.56-66
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• 2020

Purpose: A stability-measuring device that utilizes damping capacity analysis (DCA) has recently been introduced in the field of dental implantology. This study aimed to evaluate the sensitivity and reliability of this device by measuring the implant stability of ex vivo samples in comparison with a resonance frequency analysis (RFA) device. Methods: Six implant beds were prepared in porcine ribs using 3 different drilling protocols to simulate various implant stability conditions. Thirty-six pork ribs and 216 bone-level implants measuring 10 mm in height were used. The implant beds were prepared using 1 of the following 3 drilling protocols: 10-mm drilling depth with a 3.5-mm-diameter twist drill, 5-mm drilling depth with a 4.0-mm-diameter twist drill, and 10-mm drilling depth with a 4.0-mm-diameter twist drill. The first 108 implants were external-connection implants 4.0 mm in diameter, while the other 108 implants were internal-connection implants 4.3 mm in diameter. The peak insertion torque (PIT) during implant placement, the stability values obtained with DCA and RFA devices after implant placement, and the peak removal torque (PRT) during implant removal were measured. Results: The intraclass correlation coefficients (ICCs) of the implant stability quotient (ISQ) results obtained using the RFA device at the medial, distal, ventral, and dorsal points were 0.997, 0.994, 0.994, and 0.998, respectively. The ICCs of the implant stability test (IST) results obtained using the DCA device at the corresponding locations were 0.972, 0.975, 0.974, and 0.976, respectively. Logarithmic relationships between PIT and IST, PIT and ISQ, PRT and IST, and PRT and ISQ were observed. The mean absolute difference between the ISQ and IST values on a Bland-Altman plot was -6.76 (-25.05 to 11.53, P<0.05). Conclusions: Within the limits of ex vivo studies, measurements made using the RFA and DCA devices were found to be correlated under a variety of stability conditions.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제45권1호
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• pp.29-33
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• 2019

Objectives: Bone density seems to be an important factor affecting implant stability. The relationship between bone density and primary and secondary stability remains under debate. The aim of this study was to compare primary and secondary stability measured by resonance frequency analysis (RFA) between different bone types and to compare implant stability at different time points during 3 months of follow-up. Materials and Methods: Our study included 65 implants (BioHorizons Implant Systems) with 3.8 or 4.6 mm diameter and 9 or 10.5 mm length in 59 patients. Bone quality was assessed by Lekholm-Zarb classification. After implant insertion, stability was measured by an Osstell device using RFA at three follow-up visits (immediately, 1 month, and 3 months after implant insertion). ANOVA test was used to compare primary and secondary stability between different bone types and between the three time points for each density type. Results: There were 9 patients in type I, 18 patients in type II, 20 patients in type III, and 12 patients in type IV. Three implants failed, 1 in type I and 2 in type IV. Stability values decreased in the first month but increased during the following two months in all bone types. Statistical analysis showed no significant difference between RFA values of different bone types at each follow-up or between stability values of each bone type at different time points. Conclusion: According to our results, implant stability was not affected by bone density. It is difficult to reach a certain conclusion about the effect of bone density on implant stability as stability is affected by numerous factors.

• 대한치과보철학회지
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• 제43권2호
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• pp.248-257
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• 2005

Statement of problem. Cortical bone plays an important role in the primary implant stability, which is essential to immediate/early loading. However, immediate load-bearing capacity and primary implant stability according to the change of the cortical bone thickness have not been reported. Purpose. The objectives of this study were (1) to measure the immediate load-bearing capacity of implant and primary implant stability according to the change of cortical bone thickness, and (2) to evaluate the correlation between them. Material and methods.48, screw-shaped implants (3.75 mm$\times$7 mm) were placed into bovine rib bone blocks with different upper cortical bone thickness (0-2.5 mm) and resonance frequency (RF) values were measured subsequently. After fastening of healing abutment. implants were subjected to a compressive load until tolerated micromotion threshold known for the osseointegration and load values at threshold were recorded. Thereafter, RF measurement after loading, CT taking and image analysis were performed serially to evaluate the cortical bone quality and quantity. Immediate load-bearing capacity and RF values were analyzed statistically with ANOVA and post-hoc method at 95% confidence level (P<0.05). Regression analysis and correlation test were also performed. Results. Existence and increase of cortical bone thickness increased the immediate load-bearing capacity and RF value (P<0.05) With the result of regression analysis, all parameter's of cortical bone thickness to immediate load-bearing capacity and resonance frequency showed significant positive values (P<0.0001). A significant high correlation was observed between the cortical bone thickness and immediate load-beating capacity (r=0.706, P<0.0001), between the cortical bone thickness and resonance frequency (r=0.753, P<0.0001) and between the immediate load-bearing capacity and resonance frequency (r=0.755, P<0.0001). Conclusion. In summary, cortical bone thickness change affected the immediate load-baring capacity and the RF value. Although RF analysis (RFA) is based on the measurement of implant/bone interfacial stiffness, when the implant is inserted stably, RFA is also considered to reflect implant/bone interfacial strength of immediately after placement from high correlation with the immediate load-baring capacity. RFA and measuring the cortical bone thickness with X-ray before and during surgery could be an effective diagnosis tool for the success of immediate loading of implant.