• Journal of Periodontal and Implant Science
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• 제30권2호
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• pp.429-442
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• 2000

Based on current evidence in the literature, it is known that endotoxin is a weakly adherent surface phenomenon and that power-driven instruments can be used to accomplish definitive root detoxification and maximal wound healing without overinstrumentation of root and without extensive cementum removal. And one of the newly developed curette tips used with low power of piezoelectric ultrasonic scaler, is effective to remove calculus and not to remove the excessive cementum. The purpose of this study is therefore, to assess the influence of ultrasonic power and various working parameters on root substitute removal when instrumentation is performed with the curette tip on piezoelectric ultrasonic scaler. This study assessed defect depth, width and area resulting from instrumentation using a piezoelectric ultrasonic scaler with a curette type tip in vitro to acrylic resin block as a root substitute. The working parameters was standardized by the sledge device which controls lateral force(0.5 N, 1 N, 2 N) and instrumentation time(5 sec, 10 sec, 20 sec) and power setting was adjusted 0,2,4,8 in P mode. Power setting had the greatest influence on defect depth compared to lateral force and instrumentation time(standardized regression parameter estimates${\pm}$standard error, $0.37{\pm}0.02$, $0.19{\pm}0.02$, $0.07{\pm}0.02$). The effects on defect area also greatest for power setting($0.57{\pm}0.03$) compared to lateral force and instrumentation time($0.33{\pm}0.03$, $0.12{\pm}0.03$). The effect of the power setting on the defect width($0.15{\pm}0.01$) is not so great as defect depth or defect area compared to lateral force($0.12{\pm}0.01$) and effect of instrumentation time is minimal($0.02{\pm}0.01$). It could be concluded that the power setting has the greatest influence on the defect depth and area in curette type tip with low power of piezoelectric ultrasonic device. Many parameters can be adjusted in various situation in clinical use of piezoelectric ultrasonic scaler but the power setting is the first parameter to be adjusted.

• 대한의용생체공학회:의공학회지
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• 제32권3호
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• pp.198-206
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• 2011

Hearing devices like cochlear implant, vibrant soundbridge, etc. try to offer better sound for people. In hearing devices, several beamformers including conventional directional microphone are applicable to noise reduction. Each beamformer has different directional response and it could change sound intelligibility or quality for listeners. Therefore, we investigated the performance of three beamformers, which are first and second order directional microphone, and broadband beamformer(BBF) with a computer simulation assuming hearing device microphone configuration. We also calculated objective measurements which have been used to evaluate speech enhancement algorithms. In the simulation, a single speech and a single babble noisewere propagated from the front and $135^{\circ}$ azimuth degrees respectively. Microphones were configured in an end-fire array and the spacing was varied in comparison. With 3 cm spacing, BBF had about 3 dB higher enhanced SNR than that of directional microphones. However, enhancement of segmental SNR and frequency weighted segmental SNR were similar between the first order directional microphone and broadband beamformer. In addition when steady state noise was used, broadband beamformer showed the increased performance and had the highest enhanced SNR, and segmental SNR.

• Journal of Periodontal and Implant Science
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• 제31권3호
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• pp.531-542
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• 2001

Periodontal debridement is most important procedure in periodontal treatment, because periodontal disease is the biofilm infection. The use of ultrasonic instrument has many clinical advantages compared to classical hand instrument. The introduction of newly developed ultrasonic scaler tips made the use of ultrasonic scaler popular. However the study of tooth substance removal according to the working parameters of ultrasonic scaler with newly developed tips is not sufficient. The purpose of this study is to evaluate the effects of working parameters of piezoelectric ultrasonic scaler with curette tip on casting gold removal. The working parameters was standardized by the sledge device which controls lateral force(0.5 N, 1.0 N, 2.0 N) and power setting was adjusted 2, 4, 8 in P mode and S mode and instrumentation time was 5 seconds. The defect depth and width were measured with profile meter and defect surface was examined by SME. The depth of defect was significantly large in S mode( $39.58{\pm}19.35{\mu}m$) compared to P mode( $8.37{\pm}6.98{\mu}m$). There was significant decrease of depth of defect between 1.0N($32.87{\pm}27.18{\mu}m$) and 2.0N( $14.86{\pm}15.04{\mu}m$). The area of defect was also significantly large in S mode($4482.42{\pm}3551.71{\mu}m^2$) compared to P mode( $922.06{\pm}960.32{\mu}m^2$). There was significant decrease of area of defect between 1.0N($3889.12{\pm}3936.00{\mu}m$) and 2.0N( $974.66{\pm}986.01{\mu}m$). The change of mode did not effect on the width of the defect. The change of power setting did not effect on the depth, width, and area of defect. In spite of limitation of this study it could be concluded that the use of piezoelectric ultrasonic scaler with curette tip on S mode could make significant tooth substance loss.

• 한국방사선학회논문지
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• 제14권7호
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• pp.1003-1011
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• 2020

본 연구는 듀얼 에너지 CT를 사용하여 금속인공물을 감소시키는 기법을 적용함에 있어 단일 선원과 이중 선원간의 영상 차이를 비교 평가하고자 한다. 단일 선원 장치로는 Discovery CT 256(GE, USA), 이중 선원 장치로는 Somatom Definition Flash(Siemens Health Care, Forchheim, Germany)를 이용하였다. 자체 제작한 팬텀(의료용 Titanium Screw를 삽입한 돼지다리)을 이중에너지 CT를 이용하여 동일 조건하에 선량을 변화시키며 영상을 얻은 후 정량적, 정성적 평가 하였다. 평가 방법으로는 뼈 주변, 조직 주변으로 나누고 금속삽입물로 인해 발생한 금속인공물(선속경화, 산란, 줄무늬)에 대하여 SNR을 측정하여 비교 분석하였다. 단일 선원 장치와 이중 선원 장치 간 금속 인공물 감소기법에는 영상의 차이가 있었다. 단일 선원 장치에서는 금속삽입물에 의한 선속경화 인공물이 이중 선원 장치에서 얻은 영상보다 많은 감소를 보이며 인공물의 방해 없이 주변 조직부가 잘 관찰 되었다. 이중 선원 장치에서는 금속삽입물에 의한 산란과 줄무늬 인공물이 단일 선원 장치에서 보다 많은 감소를 보이며 금속삽입물을 둘러싼 인접 조직들의 신호가 감소 없이 잘 관찰 되었다. 환자를 검사 시 보고자 하는 부위가 금속삽입물에 인접한 주변 조직이냐, 금속삽입물을 감싸는 전체적 조직이냐에 따라 단일 선원 장치와 이중 선원 장치를 구분하여 검사가 행해진다면 진단적으로 도움이 되는 영상을 획득할 수 있을 것으로 생각된다.

• 전자공학회논문지
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• 제53권10호
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• pp.34-39
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• 2016

본 논문에서는 체내 이식용 신경 신호 기록 장치를 위한 저전압 저전력 아날로그 front-end 집적회로를 설계하였다. 제안된 집적 회로는 1 Hz에서 5 kHz 주파수 대역에 존재하는 신경 신호를 처리하기 위해 저잡음 neural 증폭기와 대역폭 조절이 가능한 능동 bandpass 필터로 구성되어 있다. Neural 증폭기는 우수한 잡음 특성을 위해 source-degenerated folded-cascode 연산증폭기를 기반으로 하여 설계하였고, 능동 필터의 경우 저전력의 current-mirror 연산증폭기를 이용하여 설계하였다. 능동 필터의 high-pass cutoff 주파수는 1 Hz에서 300 Hz까지 제어가 가능하며, low-pass cutoff 주파수는 300 Hz에서 8 kHz까지 제어가 가능하다. 전체 아날로그 front-end 회로는 53.1 dB의 전압 이득 성능과 1 Hz에서 10 kHz 대역에 대해서 $4.68{\mu}Vrms$의 입력 잡음 성능과 3.67의 noise efficiency factor 성능을 보인다. $18-{\mu}m$ CMOS 공정을 이용하여 설계를 하였고 1-V 전원에서 $3.2{\mu}W$의 전력 소모 성능을 갖는다. 칩 레이아웃 면적은 $0.19 mm^2$ 이다.

• Journal of Korean Neurosurgical Society
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• 제47권5호
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• pp.338-344
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• 2010

Objective : This study assessed the safety and efficacy of one level unilateral laminotomy bilateral decompression (ULBD) with the placement of a device for intervertebral assisted motion (DIAM) compared with one level ULBD only in elderly patients with degenerative lumbar spinal stenosis (DLSS). Methods : A non randomized prospective analysis was performed on 16 patients who underwent one level ULBD with DIAM (Group A) and 20 patients with one level ULBD only (Group B) between February 2007 and March 2008. Radiographic imaging, visual analog scale (VAS) and MacNab outcome scale were obtained before and after surgery at a mean interval of 21 months (range 17-27 months). Results : The disc height, interpedicular distance, slip distance and segmental lordotic angle were similar between two groups. In the group A, there was no significant difference between the pre- and post-operative imaging in terms of the sagittal balance and disc height. Both groups showed significant improvement in the clinical outcomes. In addition, there was significantly less low-back pain in the group A than in the group B at the last follow up, while the clinical improvement of the leg pain and MacNab outcome scale showed no significant difference in the two groups. There were no major complications or DIAM associated complications. Conclusion : ULBD with DIAM is a safe and efficacious treatment for selective elderly patients with DLSS, particularly for relieving low back pain comparing to ULBD. ULBD with DIAM did not alter the disc height or sagittal alignment at the mean 21 months follow-up interval.

• 전자공학회논문지SC
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• 제48권5호
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• pp.74-80
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• 2011

본 연구는 유통되는 이식형(implantable) 의료기기의 추적(tracking) 및 회수(recall) 처리를 신속하고 정확하게 수행할 수 있는 통합 전산 관리시스템 설계하는 것을 목적으로 한다. 이를 위해 최신 FDA 규정을 만족하는 시스템을 MSF/CD 설계방법론을 기반으로 설계하였다. 추적과 회수의 주요한 4가지 가상 시나리오를 설정하고 workflow diagram을 작성하여 개념설계하였다. 또한 business workflow를 만족하는 서버의 논리 DB를 개발하여 논리설계 단계까지 시스템을 설계하였다. 제안된 시스템으로 이식형 의료기기의 심각한 부작용 등 문제 발생 시 신속하고 정확한 추적과 회수 처리가 가능하여 이식형 의료기기를 장착한 환자의 생명유지 및 국민 건강 보호를 위한 정부 차원의 효율적인 관리가 가능할 것으로 사료된다.

• Journal of Periodontal and Implant Science
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• 제35권4호
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• pp.1109-1116
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• 2005

The purpose of this study was to observe the effects of periodontal therapy, including nonsurgical periodontal therapy with azithromycin, surgical therapy, and maintenace therapy on the drug-induced gingival enlargement, by means of measuring gingival thickness. The test group of 18 patients with drug-induced gingival enlargement received scaling, root planing with azithromycin for 5 days, with or without surgical periodontal treatment. The control group of 18 patients who had not taken any medication, received scaling and root planing, with or without surgical periodontal treatment. Both groups received supportive periodontal therapy every 3 months for 2 years. The mean period of total treatment is 32 months in the test group and 31 months in the control group. The thickness of the buccal gingiva was measured using an ultrasonic device of $SDM^{(R)}$(Krupp Corp., Essen, Germany). The results revealed that the test $group(1.21{\pm}0.51mm)$ showed statistically thicker buccal gingiva than the control $group(1.01{\pm}0.3mm)$. In the test group, the buccal gingiva was thickest on 2nd molars and was thinnest on canines of both dental arches. In the control group, the buccal gingiva was thickest on central incisors in the maxilla and 2nd molars in the mandible, while the thinnest areas were on canines in the maxilla and 1st premolars in the mandible. It would be concluded that the periodontal treatment with azithromycin aids in decreasing the degree of the gingival enlargement but cannot prevent the recurrence completely.

• Journal of Periodontal and Implant Science
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• 제52권2호
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• pp.116-126
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• 2022

Purpose: This study evaluated the efficacy of treating periodontitis using subgingival nano-hydroxyapatite powder with an air abrasion device (NHAPA) combined with scaling and root planing (SRP). Methods: A total of 28 patients with stage III periodontitis (grade B) were included in this study, although 1 was lost during follow-up and 3 used antibiotics. The patients were divided into a test group and a control group. All patients first received whole-mouth SRP using hand instruments, and a split-mouth approach was used for the second treatment. In the test group, the teeth were treated with NHAPA for 15 seconds at 70% power per pocket. Subgingival plaque samples were obtained from the 2 deepest pockets at the test and control sites before treatment (baseline) and 3 months after treatment. The full-mouth plaque index (PI), gingival index (GI), papillary bleeding index (PBI), bleeding on probing (BOP), probing depth (PD) and clinical attachment level (CAL) were recorded at baseline and at 1- and 3-month post-treatment. Real-time polymerase chain reaction was used to determine the colonisation of Treponema denticola (Td), Porphyromonas gingivalis (Pg), and Aggregatibacter actinomycetemcomitans in the subgingival plaque. Results: From baseline to the first month, the test group showed significantly larger changes in BOP and CAL (43.705%±27.495% and 1.160±0.747 mm, respectively) than the control group (36.311%±27.599% and 0.947±0.635 mm, respectively). Periodontal parameters had improved in both groups at 3 months. The reductions of PI, GI, BOP, PD, and CAL in the test group at 3 months were greater and statistically significant. The total bacterial count and Td and Pg species had decreased significantly by the third month in both groups (P<0.05). Conclusions: Applying NHAPA in addition to SRP improves clinical periodontal parameters more than SRP alone. Subgingival NHAPA may encourage clot adhesion to tooth surfaces by increasing surface wettability.