• 대한치과보철학회지
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• 제52권1호
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• pp.34-41
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• 2014

연구 목적: 임플란트의 종류가 다양해짐에 따라 임플란트 드라이버의 호환성에 대한 연구가 필요하여 임플란트 제품별 드라이버의 형태를 분류하고 직경을 측정하여 비교 분석하였다. 연구 재료 및 방법: 단국대학교 부속치과병원에서 사용 중인 12개회사[Nobel Biocare (Nobel), Institute Straumann (Straumann), Zimmer Dental (TSV), Shinhung (Luna), Astra Tech Dental (Astra), Dentium (Dentium), Osstem Implant (Osstem), DIO Implant (DIO), BIOMET 3i (3i), NeoBiotech (Neo), Megagen Implant (Megagen), SNUCONE (SNUCONE)] 임플란트 제품 드라이버를 연구대상으로 하였으며 임플란트 드라이버의 형태를 분류하고 이 중 호환이 가능한 Hexagon과 torx에 해당하는 드라이버들의 유효길이, 유효길이별 상단, 중단, 하단의 직경을 각각 10개씩 측정하였다. 각 직경의 측정값을 호환성 분석공식에 대입하여 호환성을 산출하였다. 결과: 분석결과, 유효길이 상단에서는 Neo, 3i, Megagen, DIO, SNUCONE, Luna들은 같은 직경(1.20 mm)을 가졌으며 Osstem (1.17 mm)은 호환 가능한 범위에 있었다. Dentium, Astra는 같은 직경(1.25 mm)을 가지며 TSV (1.23 mm) 가 이들과 호환 가능하였다. 유효길이 중단에서는 Dentium과 Astra가 같은 직경(1.35 mm)을 가졌고 3i, DIO, Osstem, TSV도 1.25 mm의 동일한 직경을 가졌다. Neo와 Megagen은 가장 작은 직경(1.22 mm)로 나머지와 호환되었다. 유효길이 하단에서는 일부 드라이버에 호환성이 확인되었으나 대부분 나사의 연결부 깊이가 2 mm 이내인 점을 감안하면 유효하지 않은 결과로 판단되었다. Nobel은 Straumann에 사용할 수 있는 것으로 나타났으며 대부분의 hexagon driver를 trox에 사용할 수 있었다. 결론: 임플란트 드라이버의 각 부위별 직경을 측정한 결과 임플란트 제품간의 호환성이 존재한다는 것을 알 수 있었다. 그러나 호환성이 있는 드라이버의 반복적인 사용이 임플란트 나사와 드라이버에 미치는 영향에 대한 연구가 아직 부족하므로 응급상황 시에만 제한적으로 사용할 것을 권장하며 이에 대한 추가적인 연구가 필요할 것으로 사료된다.

• Smart Structures and Systems
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• 제6권1호
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• pp.17-27
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• 2010

The approach to damage detection and localization adopted in this paper is based on a statistical comparison of models built from the response time histories collected at different stages during the structure lifetime. Some of these time histories are known to have been recorded when the structural system was undamaged. The consistency of the models associated to two different stages, both undamaged, is first recognized. By contrast, the method detects the discrepancies between the models from measurements collected for a damaged situation and for the undamaged reference situation. The damage detection and localization is pursued by a comparison of the SSE (sum of the squared errors) histograms. The validity of the proposed approach is tested by applying it to the analytical benchmark problem developed by the ASCE Task Group on Structural Health Monitoring (SHM). In the paper, the results of the benchmark studies are presented and the performance of the method is discussed.

• Smart Structures and Systems
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• 제6권1호
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• pp.73-85
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• 2010

The potential offered by the thermo-mechanical properties of shape memory alloys (SMA) in structural engineering applications has been the topic of many research studies during the last two decades. The main issues concern the long-term predictability of the material behaviour and the fatigue lifetime of the macro structural elements (as different from the one of wire segments). The laboratory tests reported in this paper are carried out on bar specimens and they were planned in order to pursue two objectives. First, the creep phenomenon is investigated for two different alloys, a classical Ni-Ti alloy and a Cu-based alloy. The attention is then focused on the Cu-based alloy only and its fatigue characteristics at given temperatures are investigated. Stress and thermal cycles are alternated to detect any path dependency.

• Smart Structures and Systems
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• 제4권2호
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• pp.153-169
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• 2008

The use of pre-tensioned shape memory alloy (SMA) wires to retrofit historic masonry structures is investigated. A small wall, serving as a prototype masonry specimen, is constructed to undergo a series of shaking-table tests. It is first studied in its original state, and its dynamic characteristics (in terms of modal frequencies) are extracted from the recorded signals. The results are then compared with those obtained when an increasing number of couples of pre-stressed SMA wires are introduced in the specimen to link the bricks together. A three-dimensional finite element model of the specimen is developed and calibrated according to the modal parameters identified from each experimental test (with and without SMA wires). The calibration process is conducted by enhancing the masonry mechanical behaviour. The results and the effectiveness of the approach are presented.

• 대한한방내과학회지
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• 제43권6호
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• pp.1255-1263
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• 2022

Objective: To report a clinical case of Guillain-Barré syndrome-like neurological symptoms, including limb weakness, phantosmia, and nausea/vomiting after COVID-19 vaccination (AstraZeneca) that was improved by traditional Korean medicine (TKM) treatment. Methods: A 73-year-old male complained of extreme limb weakness, severe phantosmia, and nausea/vomiting after COVID-19 vaccination. No abnormalities had appeared in various radiological and laboratory tests, but the symptoms had continued to worsen for three months before visiting our clinic. Results: The patient was diagnosed with neurological complications suspicious of Guillain-Barré syndrome after COVID-19 vaccination. The patient was treated with acupuncture, moxibustion, herbal drugs (Banhabakchulchunma-tang), and nasal inhalation therapy with Aquilariae Lignum. Three weeks after Korean medicine treatment, his neurological symptoms had improved. Nausea/vomiting and phantosmia continued to show improvement, and muscle strength was gradually recovered in both lower limbs. Conclusion: Traditional Korean medicine could be a choice for the treatment of neurological complications after COVID-19 vaccination.

• 대한치과보철학회지
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• 제54권4호
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• pp.387-392
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• 2016

목적: 본 연구의 목적은 grooved abutment가 지대주 나사풀림 현상에 미치는 영향을 확인하는 것이다. 재료 및 방법: 2015년 3월부터 7월까지 연세대학교 치과대학병원 보철과에 내원한 50명, 51개 임플란트에 대해서 임플란트 보철 장착 후 6개월 점검 시 지대주 연결나사의 안정성을 평가하였다. 대조군은 groove가 없는 지대주를 사용한 30개 임플란트이었고, 실험군은 groove가 있는 지대주를 사용한 21개 임플란트이었으며, Astra, Straumann, Implantium, Osstem 시스템이 사용되었다. 6개월 점검 시에 지대주 연결나사의 풀림여부를 조사하였고, 동일한 힘으로 재체결 시 지대주 연결나사의 추가 회전각을 측정하였으며, 보철물 협측하방 부위에서 PTV를 측정하였다. SPSS 프로그램을 이용하여 정규성 분석 후 Mann-Whitney 분석을 시행하였다. 결과: 51개 임플란트에 대해 보철 장착 후 6개월 점검을 시행한 바, 나사 풀림이나 보철물 파절 등의 특이할 만한 합병증은 나타나지 않았다. 6개월 후 지대주 연결나사의 추가회전각은, 실험군 평균은 $4.75^{\circ}$이었고 대조군 평균은 $7.35^{\circ}$이었으며, 통계적으로 유의한 차이는 없었다 (P = .576). PTV에서도 유의한 차이는 없었다 (P = .767). 결론: 지대주의 groove 여부가 지대주 연결나사의 안정성에 미치는 영향은 유의한 차이가 없으나, 이에 대해 좀더 장기적이고 다수의 증례를 이용한 추가적인 연구가 필요해 보인다.

• 구강회복응용과학지
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• 제21권2호
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• pp.113-132
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• 2005

The purpose of this study was to assess the stress-induced pattern at the supporting bone, the implant fixture, the abutment and the abutment screw according to a friction-fit joint (Astra; Model 1) or slip- fit joint (Frialit-2; Model 2) in the internal connection system under vertical and inclined loading using finite element analysis. In conclusion, in the internal connection system of the implant and the abutment connection methods, the stress-induced pattern at the supporting bone, the implant fixture, the abutment and the abutment screw according to the abutment connection form had difference among them, and the stress distribution pattern usually had a widely distributed tendency along the inner surface of the implant fixture contacting the abutment post. The magnitude of the stress distributed in the supporting bone, the implant fixture, the abutment and the abutment screw was higher in the friction-fit joint than in the slip-fit joint. But it is considered that the further study is necessary about how this difference in the magnitude of the stress have an effect on the practical clinic.

• 구강회복응용과학지
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• 제22권1호
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• pp.55-74
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• 2006

The external contour of an implant can have significant effects on the load transfer characteristics and may result in different bone failure rates for different implant system. The purpose of this study was to investigate the effects of crest module shape and occlusal load direction on bone failure modes of five commercially available dental implant systems. Five different implant systems with internal connection; ITI (Model 1), Astra (Model 2), Bicon (Model 3), Friadent (Model 4), and Paragon (Model 5), comparable in size, but different in thread profile and cest module shapes, were compared using the finite element method. Conclusively, in the internal connection system of the implant-abutment connection methods, the stress-induced pattern at the supporting bone according to the abutment connection form had differenence among them, and implants with narrowing crestal module cross-sections at the top of the cortical bone created more favorable load transfer characteristics in this region. But it is considered that the future study is necessary about how this difference in the magnitude of the stress have an effect on the practical clinic.

• Journal of Species Research
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• 제9권4호
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• pp.448-454
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• 2020

Nine free-living heterotrophic flagellates were cultured from marine intertidal sediments and freshwater sediments from Korea. These species are described with uninterpreted records based on light microscopy of living cells and reported taxonomically for the first time from Korea. Diagnostics of these species are as follows; Notosolenus hemicircularis: 9-11.8 ㎛ long with flagellar reservoir, ventrally flattened and dorsally convex with hyaline semicircular collar around short anterior neck, and 8 ridges on cell surface. Thecamonas tranhens: 4.5-7.1 ㎛ long, plastic with proboscis comprising an anterior flagellum surrounded by membranous sleeve. Bodomorpha minima: 4.5-7.0 ㎛ long, rigid with small rostrum in anterior end and active anterior flagellum. Cercomonas hiberna: 5.6-10.9 ㎛ long, very plastic with pseudopodia, cytoplasmic strand and 1 or 2 contractile vacuoles. Cercomonas pellucida: 7.5-13 ㎛ long, plastic with pseudopodia, cytoplasmic strand and single contractile vacuole. With nucleus closely connected to basal bodies. Eocercomonas echina: 4.7-6.5 ㎛ long, plastic with pseudopodia, cytoplasmic strand and 1 or 2 contractile vacuoles. Paracercomonas astra: 5.7-7.3 ㎛ long, moderately metabolic with pseudopodia, cytoplasmic strand and 1 or 2 contractile vacuoles. Paracercomonas minima: 5-9 ㎛ long, metabolic with pseudopodia, cytoplasmic strand and single contractile vacuole. Paracercomonas producta: 6.1-9.9 ㎛ long, very metabolic with pseudopodia, long cytoplasmic strand and single contractile vacuole.

• Smart Structures and Systems
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• 제7권1호
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• pp.41-57
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• 2011

A deeper understanding of the effectiveness of adopting devices mounting shape memory alloy (SMA) elements in applications targeted to the mitigation of vibrations is pursued via an experimental approach. During a seismic event, less than 1000 loading-unloading cycles of the alloy are required to mitigate the earthquake effects. However, the aging effects during the time of inactivity prior to the oscillations (several decades characterized by the yearly summer-winter temperature wave) should be considered in order to avoid and/or minimize them. In this paper, the results obtained by carrying out, in different laboratories, fatigue tests on SMA specimens are compared and discussed. Furthermore, the effects of seismic events on a steel structure, with and without SMA dampers, are numerically simulated using ANSYS. Under an earthquake excitation, the SMA devices halve the oscillation amplitudes and show re-centering properties. To confirm this result, an experimental campaign is conducted by actually installing the proposed devices on a physical model of the structure and by evaluating their performance under different excitations induced by an actuator.