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      • 초고속 치과용 핸드피스 개발

        한명철,김정관,최명욱,이왕근,김헌주 한국공작기계학회 2008 한국공작기계학회 춘계학술대회논문집 Vol.2008 No.-

        The dental high-speed handpiece is one of the most popular and important devices that has been widely used as the main means of cutting tooth structure and restorative materials in dentistry, In consideration of usage and marketability of the dental handpiece, it is obviously worthy of investigating it. In this paper, a high speed dendal handpiece is developed through reverse engineering with 3D X-Ray CT equipment and wire cutter for the Mark II model in NSK. The demension of the handpiece parts is obtained through this process, and 3D modeling is performed with CATIA V5. The interference between parts can be examined through the part assembly in CATIA, and the performance is finally compared with Mark II model in NSK.

      • 역전파알고리즘 기반 자율주행로봇의 지역경로계획설계

        정헌,박경석,이경웅,박기두,최한수 조선대학교 전자정보통신연구소 2002 電子情報通信硏究所論文誌 Vol.5 No.2

        The research about the AMR has been progressed, which can bridge a disadvantage that a robot performs under a position unmoved. The AMR-Research constitutes skelton, path planning, AMRcontrol, sensor fusion and obstacle avoidance etc... The path planning of autonomous mobile robot use two method. One is global path planning and another is local path planning. In this paper, we study the local path planning of autonomous mobile robot move in unknown enviroment. This local path planning is based on neural network using the direction indicator rules learning. Also the system is made up of sensor system. The experimental results show that the developed direction indicator system operates properly and strongly at circumstance

      • Staphylococcus aureus와 Coagulase-Negative Staphylococcus Species에 대한 Arbekacin의 시험관내 항균력

        위성헌,강진한,허동호,이동건,김상일,김양리,최정현,김종현,유진흥,허재균,신완식,강문원 대한감염학회 2001 감염 Vol.33 No.4

        Background : Most strains of methicillin-resistant Staphylococcus aureus (MRSA) now exhibit high-level resistance to various antibiotics, such as β -lactam antibiotics, aminoglycosides, macrolides, tetracyclines and quinolones. Recent reports describing the therapeutic failure of vancomycin for MRSA infections have arisen considerable concerns regarding the emergence of MRSA strains, which will require new therapeutic agents. Arbekacin, an aminoglycoside antibiotic, has antibacterial activity against both gram-positive and gram-negative bacteria and is stable in the presence of aminoglycoside inactivating enzymes produced by S. aureus. In this study, we compared the antibacterial activity of arbekacin with those of vancomycin, gentamicin, and amikacin against Staphylococcus aureus (S. aureus) and coagulase-negative staphylococci (CNS). Methods : For a collection of 549 S. aureus and 251 CNS isolates from three Catholic University Hospitals in Korea, minimum inhibitory concentrations (MICs) of arbekacin, vancomycin, amikacin and gentamicin were determined by agar dilution method using Mueller-Hinton agar according to NCCLS (National Committee for Clinical Laboratory Standards, USA)criteria. Results : Among 549 S. aureus isolates, 278 isolates were MRSA and 271 isolates were methicil sensitive S. aureus (MSSA). MIC50 & MIC90 of arbekacin against 549 S. aureus were 0.5 & 1 ㎍/mL, and MIC50 & MIC90 of vancomycin were 1 & 1 ㎍/mL. MIC of arbekacin against 549 S. aureus isolates ranges from 0.03 to 4 ㎍/mL, and MIC of vancomycin against 549 S. aureus ranges from 0.25 to 2 ㎍/mL. MIC90 of amikacin against 549 S. aureus was 32㎍/mL, and that of gentamicin was 128 ㎍/mL. MICs of amikacin and gentamicin were variable, ranging from 0.125 to 256, and otherwise arbekacin and vancomycin revealed relatively narrow range of MICs. MIC90 of arbekacin against 278 MRSA isolates & 271 MSSA were 1 & 0.5 ㎍/mL, and those of vancomycin against MRSA & MSSA were 1 & 1 ㎍/mL. MIC90 of amikacin against 278 MRSA & 271 MSSA isolates were 32 & 4 ㎍/mL, and that of gentamicin against MRSA & MSSA isolates were 128 & 32 ㎍/mL respectively. Among 251 CNS isolates, 122 isolates were MRCNS and 129 were MSCNS. MICSO & MIC90 of arbekacin against 251 CNS isolates were 0.25 & 2 ㎍/mL, and those of vancomycin were 1 & 2 ㎍/mL. MIC of arbekacin against 251 CNS isolates ranges from 0.015 to 32 ㎍/mL, and that of vancomycin isolates ranges from 0.25 to 2 ㎍/mL, MIC90 of arbekacin against 122 MRCNS & 129 MSCNS isolates were 2&0.3 ㎍/ML, and those of vancomycin were 2&s ㎍/ML. MIC90 of amikacin against 251 CNS isolates was 32 ㎍/ML, and that of gentamicin was 128 ㎍/ML for CNS. MIC90 of amikacin against 122 MRCNS & 129 MSCNS isolates were 128 & 8㎍/mL, and those of gentamicin ere 256 & 32 ㎍/mL. Conclusion : Considering above results, arbekacin can be useful agent against most strains of MRSA and MRCMS, which exhibit high-level resistance to amikacin and gentamicin. (Korea J Infect Dis 33:254~260, 2001)

      • KCI등재

        치과용 자성 어태치먼트 재료의 안정성 개선에 관한 연구 : II.질화티타늄 코팅이 치과용 자성재의 내식성에 미치는 영향 Ⅱ.Effect of TiN Coating on Corrosion Resistance of Dental Magnetic Materials

        최한철,고영무,정재헌,신종연,김일선,최성욱,정효수 대한치과기재학회 1999 대한치과재료학회지 Vol.26 No.4

        Dental magnetic materials have been applied to removable prosthetic appliances, maxillofacial prostheses, obturator and dental implant but they still have some problems such as low corrosion resistance in oral environments. To increase the corrosion resistance of dental magnetic materials, surfaces of Sm-Co and Nd-Fe-B based magnetic materials were plated with TiN and then electrochemical corrosion test were performed in 4 kinds of electrolyte solutions(0.9% NaCl. 1% lactic acid, 0.05% HCl and modified Fusayama's artificial saliva). From this study, corrosion behavior, amount of elements released, mean average surface roughness values and the changing of mean surface microhardness values were measured comparing with control group of non-sputtered plating magnetic materials. The results were as follows: 1. TiN layer coated on magnet grows into preferred direction with lamellar structure and its thickness is 3.0㎛. 2. Sm-Co base magnetic materials coated with TiN have good corrosion resistance in 1% lactic acid and their pitting corrosion can not be seen. 3. Nd-Fe-B base magnetic materials coated with TiN showed good tendency of corrosion resistance in 0.05% HCl solution. 4. The amount of elements released from both Sm-Co and Nd-Fe-B base magnetic materials coated with TiN were more significantly decreased than that of uncoated magnetic materials. 5. The mean surface roughness values of both Sm-Co and Nd-Fe-B base magnetic materials coated with TiN were smooth than that of uncoated magnetic materials after corrosion test. 6. The decreasing rate of microhardness of both Sm-Co and Nd-Fe-B base magnetic materials coated with TiN were lower than that of uncoated magnetic materials after corrosion test. 7. Dental magnetic materials coated with TiN produced various corrosion products such as TiO, TiO₂, Ti₂O₃on the surface and resulted in better corrosion resistance than uncoated magnetic materials. In conclusion, it is considered that the corrosion problem of dental magnetic materials could be solved to some extent by EB-PVD with TiN on the surface of dental magnetic materials.

      • 지연유합과 불유합에서 저신호 강도 초음파의 유용성

        윤여헌,김종오,고영도,유재두,정준모,오종건,방한천,최창호,신명철 대한골절학회 2003 대한골절학회지 Vol.16 No.1

        목 적 : 저 신호 강도 초음파를 이용한 지연유합과 불유합의 치료에 대한 유용성을 알아보고자 하였다. 대상 및 방법 : 2001년 7월부터 2002년 5월까지 본원에 내원한 지연유합 7례와 불유합 8례를 대상으로 5개월간 저 신호 강도 초음파로 치료하여 5개월후 골유합 여부를 알아 보았다. 결 과 : 총 15례 중 대퇴골 간부 2례, 경골 간부 1례, 상완골 간부 1례, 요골 1례의 지연유합에서 골유합을 얻었고 대퇴골 간부 불유합 3례에서 유합을 얻었다. 지연주합은 71%의 유합율을, 불유합은 37.5%의 유합율을 보였다. 결 론 : 저 신호 강도 초음파는 골유합을 촉진 시킬 수 있으며 지연유합에서 시도해 볼 만 하나 불유합 치료를 위해서는 보다 많은 연구가 필요 하다. Purpose : To evaluation of usefulness of low-intensity ultrasound for nonunion and delayed union. Materials and Methods : For 5 months, we treated 7 delayed union and 8 nonunion using low-intensity ultrasound. After 5 months, in checked X-ray AP and Lateral view, when cortical bridge formation was done, we through union. Results : In 7 delayed union, 5 cases-2 femur, tibia, humerus, radius were healed. In 8 nonunion, 3 femur nonunion were healed. Union rate was 71% in delayed union 37.5% in nonunion. Conclusion : we thought that the low-intensity ultrasound has capacity of induction of union and was considered as the method of treatment for delayed union.

      • SCISCIESCOPUS

        Batteries: Cable‐Type Flexible Lithium Ion Battery Based on Hollow Multi‐Helix Electrodes (Adv. Mater. 38/2012)

        Kwon, Yo Han,Woo, Sang‐,Wook,Jung, Hye‐,Ran,Yu, Hyung Kyun,Kim, Kitae,Oh, Byung Hun,Ahn, Soonho,Lee, Sang‐,Young,Song, Seung‐,Wan,Cho, Jaephil,Shin, Heon,Cheol,Kim, Je Y WILEY‐VCH Verlag 2012 Advanced Materials Vol.24 No.38

        <P>The first ever demonstration of a cable‐type lithium ion battery architecture with outstanding omni‐directional flexibility is described by Je Young Kim, Heon‐Cheol Shin, and co‐workers on page 5192. The Front Cover image illustrates the unique battery architecture comprising a skeleton frame surrounding an empty space, that is, a hollow‐spiral anode with a multi‐helical structure. This design enables the battery to reliably power an LED screen or an MP3 player even under severe mechanical twisting and bending. </P>

      • KCI등재

        치과용 자성재의 안정성 개선에 관한 연구 : I. 치과용 자성재의 전기화학적 부식에 대한 스퍼터링 도금의 효과 I. Effects of Sputtered Film Deposition on the Electrochemical Corrosion of Dental Magnetic Materials

        고영무,최한철,정재헌,정효수,최성욱 대한치과기재학회 1999 대한치과재료학회지 Vol.26 No.4

        In order to investigate the various properties of dental magnetic materials studies on corrosion behavior, decreasing rate of magnetic flux density, amount of elements released, mean average surface roughness values and the changing of mean surface microhardness values for dental application were done. To increasing the corrosion resistance of dental magnetic materials, surfaces of Sm-Co and Nd-Fe-B based magnetic materials were plated with gold(Au), platinum(Pt), titanium(Ti), chromium(Cr) and cobalt(Co), and then electrochemical corrosion test were performed in 4 kinds of electrolyte solution(0.9% NaCl, 1% lactic acid, 0.05% HCl and modified Fusayama's artificial saliva). The results were as follows: 1. In Sm-Co and Nd-Fe-B based magnetic materials, the pitting corrosion of experimental group was higher than that of the control group, the experimental group was less corrosive than control hroup. 2. The amount of elements released from experimental group was more significantly decreased than that of control group. 3. Decreasing rate of magnetic flux density of experimental groups was significantly lower than that of control group after corrosion test. 4. The mean average surface roughness value of one(Sm-Co based magnetic materials not plated) of the control group was much increased in modified Fusayama's artificial saliva after first corrosion but that of the other(Nd-Fe-B based magnetic materials not plated) was much increased in 0.05% HCl solution. 5. The decreasing rate of surface microhardness values of experimental groups were lower than that of control group after corrosion, 6. Intergranular corrosion started first from the grain boundary of the control group and they advanced gradually to general corrosion, and the pitting corrosion occurred locally at area of existing pits in experimental group.

      • KCI등재

        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.

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