미니 임플란트 직경에 따른 피로파절강도의 비교 연구

허유리,손미경,김희중,최한철,정재헌 大韓齒科補綴學會 2012 대한치과보철학회지 Vol.50 No.3

Purpose: This study was conducted to obtain difference in fracture strength according to the diameter of one-body O-ring-type of mini implant fixture, to determine the resistance of mini implant to masticatory pressure, and to examine whether overdenture using O-ring type mini implant is clinically usable to maxillary and mandibular edentulous patients. Materials and methods: For this study, 13 mm long one body O-ring-type mini implants of different diameters (2.0 mm, 2.5 mm and 3.0 mm) (Dentis, Daegu, Korea) were prepared, 5 for each diameter. The sample was placed at 30 from the horizontal surface on the universal testing machine, and off-axis loading was applied until permanent deformation occurred and the load was taken as maximum compressive strength. The mean value of the 5 samples was calculated, and the compressive strength of implant fixture was compared according to diameter. In addition, we prepared 3 samples for each diameter, and applied loading equal to 80%, 60% and 40% of the compressive strength until fracture occurred. Then, we measured the cycle number on fracture and analyzed fatigue fracture for each diameter. Additionally, we measured the cycle number on fracture that occurred when a load of 43 N, which is the average masticatory force of complete denture, was applied. The difference on compressive strength between each group was tested statistically using one-way ANOVA test. Results: Compressive strength according to the diameter of mini implant was 101.5 ± 14.6 N, 149 ± 6.1 N and 276.0 ± 13.4 N, respectively, for diameters 2.0 mm, 2.5 mm and 3.0 mm. In the results of fatigue fracture test at 43 N, fracture did not occur until 2×106 cycles at diameter 2.0 mm, and until 5×106 cycles at 2.5 mm and 3.0 mm. Conclusion: Compressive strength increased significantly with increasing diameter of mini implant. In the results of fatigue fracture test conducted under the average masticatory force of complete denture, fracture did not occur at any of the three diameters. All of the three diameters are usable for supporting overdenture in maxillary and mandibular edentulous patients, but considering that the highest masticatory force of complete denture is 157 N, caution should be used in case diameter 2.0 mm or 2.5 mm is used. 연구 목적: 일체형의 o-ring type 미니 임플란트 고정체의 직경에 따른 파절강도의 차이를 비교하고자 한다. 연구 재료 및 방법: 길이 13 mm의 one body o-ring type의 미니 임플란트(Dentis, Daegu, Korea)를 직경2.0, 2.5, 3.0 mm 각각 5개씩 준비하였다. Instron universal testing machine 에 수직면에서 30도 각도로 샘플을 위치시키고 off-axis loading을 가하여 영구변형이 일어난 하중 값을 파절강도로 하고 5개의 시편의 평균을 구하여 각 직경에 따른 임플란트의 고정체의 파절강도를 비교하였다. 또한, 각 직경마다 3개의 시편을 준비하고 동적하중 피로 시험기를 이용하여, 파절이 발생할 때까지 파절강도의 80%, 60%, 40%의 loading 을 가하여 파절되는 cycle수를 측정하여 각 직경의 피로 파절을 분석하였다. 추가적으로 총의치의 평균 저작력인 43 N의 하중을 가하여 파절되는 cycle 수를 측정하였다. 각 군간의 차이를 검증하기 위해서 일원분산분석(one-way ANOVA test)을 시행하였고, 통계처리는 SPSS ver.12 (SPSS Inc. Chicago, IL, USA) 을 이용하여 실시하였다. 결과: 직경 3.0 mm 의 미니 임플란트는 평균 276.0 ± 13.4 N의 압축력을 받았을 때 영구 변형이 일어났고 직경 2.5 mm 미니 임플란트가 149.0 ± 6.1 N, 2.0 mm 미니 임플란트가 101.5 ± 14.6 N일 때 영구 변형이 일어났다. 각 군간의 파절강도에는 유의한 차이가 있었다(P<.001). 총의치의 평균 저작력 하중에서 실시한 피로 파절 실험 결과, 세직경 모두 5×106 cycle까지 파절이 일어나지 않았다. 결론: 미니 임플란트의 정적 하중 하에서 최대 압축강도는 직경이 증가할수록 유의적으로 증가하였다. 최대 압축강도는 세 직경 모두 총의치의 평균 저작력 보다는 크나 최대 교합력보다는 직경 3.0 mm에서만 크게 나타났다. 총의치의 평균 저작력 하중에서 실시한 피로 파절 실험 결과, 세 직경 모두 파절이 일어나지 않았다.

동기적 검사점 기법에서의 쓰레기 처리 기법

정광식,안병주,유헌창,황종선 고려대학교 컴퓨터과학기술연구소 2001 JOURNAL OF COMPUTER SCIENCE & ENGINEERING TECHNOLO Vol.3 No.-

이 논문은 동기적 검사점 기법에서 결함 포용을 목적으로 불안전 저장 장치(volatile storage)에 저장되는 메시지 로그과 안전 저장 장치에 저장되는 검사점의 쓰레기 처리 기법을 제안한다. 기존의 동기적 검사점 기법을 기반으로 한 결함 정보 쓰레기 처리 기법은 가장 최근의 검사점을 제외한 모든 결함 정보를 쓰레기 처리하였다. 하지만 TCP/IP와 같은 신뢰성을 갖는 동기적 검사점 기법이 가장 최근의 검사점만을 복귀 회복 기법에서 사용한다면, 불필요한 복귀(sympathetic rollback)가 발생된다. 이 논문은 동기적 검사점 기법에서 손실 메시지(lost message)를 해결하기 위해 각 프로세스가 동기화된 가장 최근의 검사점외에 검사점이나 메시지 로그를 유지해야 한다는 것을 입증했다. 또한 손실 메시지 해결을 위해 관리되어야 하는 검사점이나 메시지 로그가 쓰레기 처리되어지기 위해 필요한 조건을 새롭게 정의하며, 이 정의를 기반으로 한 검사점과 메시지 로그의 쓰레기 처리 알고리즘을 제안한다. 제시된 조건을 기반으로 한 검사점과 메시지 로그의 쓰레기 처리는 송수신 메시지에 부가된 손실 메시지 관련 프로세스 정보를 이용하므로 쓰레기 처리를 위한 부가적인 메시지를 발생시키지 않는다. 제안된 기법은 일반 메시지가 송수신되기 전까지 쓰레기 처리가 지연되는 '지연 쓰레기 처리 현상(lazy garbage collection)'을 발생시킨다. 하지만 '지연 쓰레기 처리 현상'은 분산 시스템의 일관성을 위배하지 않는다. This paper presents a garbage collection protocol for checkpoints and message logs which are saved on the stable storage or volatile storage for fault tolerancy. The previous works of garbage collections in coordinated checkpointing protocol delete all the checkpoints except for the last checkpoints on each processes. But implemented on top of reliable communication protocol like as TCP/IP, rollback recovery protocol based on only last checkpoints makes sympathetic rollback. We show that the old checkpoints or message logs except for the last checkpoints have to be preserved in order to replay the lost messages. And we define the conditions for garbage collection of checkpoints and message logs for lost messages and present the garbage collection algorithm for checkpoints and message logs in coordinated checkpointing protocol. Since the proposed algorithm uses process information for lost message piggybacked with messages, the additional messages for garbage collection is not needed. The proposed garbage collection algorithm makes 'the lazy garbage collection effect', because relying on the piggybacked checkpoint information in send/receive message. But 'the lazy garbage collection effect' does not break the consistency of the whole systems.

Dentacolor Resin System의 색안정성 및 물흡수도에 관한 연구

고영무,정재헌,최유석 大韓齒科器材學會 1995 대한치과재료학회지 Vol.22 No.2

The purpose of this study was to measure the color stability and water sorption of Dentacolor resin system at various time intervals over 6 week period. Ten, 20 x 1mm discs of the resin specimen were prepared according to ADA specification No.27 and cured with a photo-polymerization equipment(Dentacolor XS and Unilux AC). The color parameters of L*, a*, b* were measured with a computerized colorimeter(Hunter Associates Laboratory Inc., USA) in the transmittance mode. The total color change(ΔE) occurred during two different time periods was calculated using the following equation: ?? The amount of water sorption measurements was done in accordance with ADA specification No.27 for one week in distilled water at 37 ±1℃ and then stored extended up to 6 weeks. The obtained results were as follows : l. At first week, total color difference(ΔE) value of Dentacolor resin system was 1.430 ±0.664. 2. It was found that the range of total color difference(ΔE) of Dentacolor resin system was between 0.5∼1.430 for 6 weeks. 3, The amount of water sorption for one week was 0.30 ±0.119mg/cm²and it was lower than the 0.7mg/cm²/week for type Ⅱ composites in ADA specification No.27. 4. The amount of water sorption of Dentacolor resin system after 6 weeks was much more than its amount of water sorption of the first week, but it was not significant difference(p>0.05).

Protective effects of ginsenoside Rg2 and astaxanthin mixture against UVB-induced DNA damage

Chung, Yu Heon,Jeong, Seul A.,Choi, Hyun Seok,Ro, Seungil,Lee, Jung Sup,Park, Jong Kun ZOOLOGICAL SOCIETY OF KOREA 2018 ANIMAL CELLS AND SYSTEMS Vol.22 No.6

<P><B>ABSTRACT</B></P><P>Ultraviolet B (UVB) radiation induces skin damage, skin matrix degradation, and wrinkle formation through photochemical reaction and oxidative stress. Therefore, protecting the skin from UVB can prevent skin aging. In this study, we investigated the effects of a mixture (RA) of Rg2, a ginsenoside, and astaxanthin, an antioxidant, on the responses of HaCaT cells exposed to UVB (700 J/m<SUP>2</SUP>). The cells were incubated for 24 h after UVB exposure and cell viability was determined by MTT assay. UVB decreased cell viability by 60% compared to that of untreated control cells, whereas RA increased cell viability in a concentration-dependent manner, and this increase was significantly higher than that in the single treatment groups. Further, UVB increased the levels of DNA lesions such as cyclobutane pyrimidine dimer (CPD) and 8-hydroxyguanine (8-OHdG). Conversely, RA decreased both CPD and 8-OHdG levels in a concentration-dependent manner. UVB exposure also increased phosphorylation of ataxia-telangiectasia mutated (ATM) protein kinase and p53 and subsequently increased the levels of GADD45α, p21, and matrix metalloproteinases (MMPs)-3, -9, and -13. Additionally, UVB exposure decreased the level of COL1A1. However, RA treatment decreased the levels of p-ATM, p-p53, GADD45α, p21, MMP-3, -9, and -13 and increased the level of COL1A1 in a concentration-dependent manner. These results suggest that RA reduces UVB-induced cytotoxicity and genotoxicity through up-regulation of DNA repair via the combined effects of Rg2 and astaxanthin.</P>

Protective effects of Aronia melanocarpa and Rubus coreanus extracts mixture against the UVB-induced cyto- and genotoxicity

Yu Heon Chung,Hyun Seok Choi,Seul A Jeong,Ha Yan Cho,Ga In Beak,Jae Kwan Lee,Jong Kun Park 한국식품영양과학회 2018 한국식품영양과학회 학술대회발표집 Vol.2018 No.10

Dentacolor Resin System 의 색안정성 및 물흡수도에 관한 연구

정재헌(Chae Heon Chung),최유석(Yu Seok Choi),고영무(Yeong Mu Ko) 조선대학교 구강생물학연구소 1995 Oral Biology Research (Oral Biol Res) Vol.19 No.2

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한우 Band 3 및 CHS 유전병의 분자유전학적 기초연구

정행진,유성란,상병찬,이준헌 충남대학교 농업과학연구소 2005 농업과학연구 Vol.32 No.1

Many bovine genetic diseases are currently unidentified in Korea because of the relatively low monitoring systems in the livestock farms. The molecular detection system using PCR-RFLP of two genetic diseases, namely Band 3 (Erythrocyte Membrane Protein Band Ⅲ) and CHS (Chediak-Higashi Syndrome), have been identified in Japan and used for screening large number of cattle whether each individual has the genetic disease or not. Using the 22 unrelated Korean cattle (Hanwoo) individuals, molecular detection system based on PCR-RFLP have been investigated, which can be distinguishable carriers for the genetic diseases. Even though we could not found the causative mutations for two genetic diseases, the PCR-RFLP techniques used in this study are very valuable for the screening the genetics diseases in Korean cattle, especially for the proven or candidate bulls.

Contour of lingual surface in lower complete denture formed by polished surface impression

Yu-Ri Heo,Hee-Jung Kim,Mee-Kyoung Son,Chae-Heon Chung 대한치과보철학회 2016 The Journal of Advanced Prosthodontics Vol.8 No.6

PURPOSE The aim of this study was to analyze the shapes of lingual polished surfaces in lower complete dentures formed by polished surface impressions and to provide reference data for use when manufacturing edentulous trays and lower complete dentures. MATERIALS AND METHODS Twenty-six patients with mandibular edentulism were studied. After lower wax dentures were fabricated, wax was removed from the lingual side of the wax denture and a lingual polished surface impression was obtained with tissue conditioner. The definitive denture was scanned with a three-dimensional scanner, and scanned images were obtained. At the cross-sections of the lingual frenum, lateral incisors, first premolars, first molars, and anterior border of the retromolar pads, three points were marked and eight measurements were taken. The Kruskal-Wallis test and a post hoc analysis with the Mann-Whitney test were performed. RESULTS Each patient showed similar values for the same areas on the left and right sides without a statistically significant difference. The height of the contour of the lingual polished surface at the lingual frenum was halfway between the occlusal plane and lingual border, it moved gradually in a downward direction. The angle from the occlusal plane to the height of the contour of the lingual polished surface was increased as it progressed from the lingual frenum towards the retromolar pads. CONCLUSION The shape of the mandibular lingual polished surface was convex at the lingual

석류피 추출물의 항균활성

유자헌,서충석,임미정 숙명여자대학교 약학연구소 2004 약학논문집-숙명여자대학교 Vol.20 No.-

Antimicrobial activity of pomegranate (Punica granatum Linne) peel extract was investigated using MIC assay. Pomegranate peel extract showed antimicrobial activities against E. coli, S. aureus, and P. acnes, and its MICs were about 0.05-0.4mg/ml. The antimicrobial activities of pomegranate peel extract were also confirmed by disk diffusion assay. Pomegranate peel extract inhibited the growth of E. coli, S. aureus, and P. acnes, resulting in the formation of growth inhibitory zones on agar plates. This is the first report on the antimicrobial property of the pomegranate peel extract. Owing to this property, the studies can be further extended to exploit pomegranate peel as a natural antimicrobial agent.

The affects of pulmonary function after gym ball exercise for sedentary behavior students: randomized controlled trial

Chung, Hyuk-Goo,Kim, Yong-Soon,Lee, Dong-Yeop,Hong, Ji-Heon,Yu, Jae-Ho,Kim, Jin-Seop Diva Enterprises Private Limited 2018 Indian journal of public health research & develop Vol.9 No.11