• The Journal of the Korean bone and joint tumor society
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• v.17 no.2
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• pp.58-64
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• 2011

Purpose: The purpose of this study is to observe unicameral bone cyst (UBC) outcome after the fracture has healed and if there is any identifiable prognostic factors. Materials and Methods: 13 UBC patients with pathologic fracture from 2001 to 2010 were reviewed. The mean follow up were 26 months (3-90 months). There were 11 male and 2 female patients and the mean age of the patients were 10.2 years old (6-16 years). 9 involved proximal humerusand 2 involved humerus shaft and 1 involved proximal femur and 1 involved proximal tibia. The treatment of UBC fracture was conservative cast application to heal the fracture initially, and 1 patient was treated with primary auto bone graft and open reduction with internal fixation. 5 patients were treated with steroid injection during follow up period and 2 patients with auto bone graft. We analyzed the change of UBC during pathologic fracture healing period and prognostic factor about age, the size of UBC, the involvement of physis. Results: The mean duration of the fracture healing was 8.2 months. Complete healing were occurred at 4 patients (31%). No statiscal difference was checked with age about UBC healing (p=0.42). But, more larger size about UBC and more closer to physis, the healing was difficult (p=0.05, p=0.03). Conclusion: While pathologic fracture of UBC was possibly healed, active treatment should be applied especially those cysts that involvescloser area of the physis or large size.

• Journal of Dental Rehabilitation and Applied Science
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• v.24 no.4
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• pp.317-324
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• 2008

The objective of this study was to test effects of (1) where the occlusal contact points locate on a full veneer crown, and (2) which direction the contact forces are directed to, on the stresses within the luting cement layer that might suffer microfracture. A total of 27 finite element models were created for a mandibular first molar, combining 9 different locations of the occlusal contact points and 3 different loading directions. Type 3 gold alloy was used for crown material with a chamfer margin, and the luting cement material was glass ionomer cements in uniform thickness of $75{\mu}m$. Modeled crowns were loaded at 100 N. Different patterns in the cement stress were observed in the vicinity of the buccal and lingual margins. Whereas, the peak stress in buccal margin occurred approximately 0.5 mm away from the external surface, the highest stress in lingual margin was observed at approximately 1 mm. Significantly different distribution of stresses was recorded as a function either of the location of the occlusal contact points or of the loading direction. Higher stresses were produced by more obliquely acting load, and when the loaded point was in the vicinity of the cusp tip.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.7
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• pp.709-715
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• 2011

In order to observe the wake interaction between tip vortices generated by a two-bladed rotor with slightly different pitch angles, the velocity components of the tip vortices were measured by using a two-dimensional LDV system. It was observed that the swirl velocity components of the ensuing blade deviated from the Vatistas' n = 2 vortex model and the axial velocity components of the preceding blade deviated from the Gaussian profile. It was also found that in the wake-age range of $200^{\circ}$ to $240^{\circ}$, the filament of the ensuing blade tip vortex was stretched as result of the closing in of two vortices. The results from these observations suggest the possibility that a similar wake interaction is generated in actual rotor blades, especially, in the ones with articulated hubs.

• Proceedings of the Korean Information Science Society Conference
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• 2011.06a
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• pp.403-406
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• 2011

한국해양연구원에서는 국토해양부의 지원을 받아 2010년 7월부터 새로운 개념의 해저로봇 개발에 착수하였다. 새로이 개발되는 해저로봇은 프로펠러 방식으로 추력을 얻는 기존의 해저로봇과는 달리 여러 개의 관절로 이루어진 6개의 다리를 이용하여 해저면에 근접해서 보행과 유영으로 이동하는 해저로봇으로 강조류와 악시계의 환경에서도 운용이 가능한 로봇이다. 이 해저보행로봇 시스템은 선상시스템과 완충기, 그리고 해저보행로봇으로 구성되며, 이들 사이는 광변환기를 통해서 광케이블로 연결된다. 선상시스템에는 해저로봇의 제어 및 모니터링을 위하여 10대의 컴퓨터가 설치되어 있고, 완충기와 해저로봇에 각각 1대의 입출력 컴퓨터가 내장되어 장착된 센서와 모터의 인터페이스를 담당한다. 본 논문에서는 해저보행로봇의 통신 시스템을 소개하고, 이 통신 시스템에서 사용되기 위하여 설계된 메시지의 통신 프로토콜을 설명한다. 해저보행로봇 시스템의 주 네트워크는 기가비트 이더넷이며, 안정된 통신 환경의 소규모 독립 네트워크이다. 완충기와 해저보행로봇에는 최대 100㎐로 동작하는 다양한 직렬 통신 방식을 갖는 다수의 센서와 모터가 장착되어 있는데, 입출력 컴퓨터가 이더넷 네트워크와의 인터페이스 역할을 수행하여 계층적 네트워크를 구성한다. 로봇 제어에서는 실시간성이 중요하기 때문에 이더넷에서 통신 메시지는 한 번의 전송으로 여러 컴퓨터에 전달할 수 있도록 멀티캐스팅을 사용하여 전송된다. 설계된 통신 프로토콜은 이러한 해저로봇 시스템의 특성에 적합한 간결한 구조로 설계되었으며, 최대 255개의 주소를 지정할 수 있고 255 종류의 메시지 형태를 설정할 수 있다.

• Journal of Dental Rehabilitation and Applied Science
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• v.26 no.3
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• pp.265-271
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• 2010

One of the most important aspect of esthetic dentistry is shade selection. Alterations to perception of color can occur as a result of numerous factors, including light source, tooth surface texture, observer's ability, surrounding colors, the angle of observation, light and dark adaptation and others. During the clinical procedures, tooth might be in dry or semi-dry condition. The purpose of this study was to compare the shade changes in wet and dry conditions of natural tooth. Groups of measurement are an initial wet condition as control, dry in 10seconds, 1 minute, 5minutes and 30seconds air dry. Using Shadeeye, color difference(${\Delta}E$) between measurements were analyzed and there were significant differences between groups. But most of the differneces were <3.7 ${\Delta}E$ unit. Such differences are below the threshold for perceivable color mismathces in intraoral condition. Shade selection with an intraoral colorimeter could be changes in dry and wet condition but there might be no significant differences in visual color mathing.

• Journal of Dental Rehabilitation and Applied Science
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• v.28 no.1
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• pp.27-36
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• 2012

As the popularity of implant treatment using a variety of problems have been reported. The proper torque values recommended by the manufacturer and the actual tightening force applied to the observed differences. Period for each product used in this study using different torque controllers accuracy for each of the comparisons, were analyzed. Error rate varies by the manufacturer, but all the products used in the reference period for increasing the error rate increased. Repeat the initial tightening, but the reference, showed a value close to the reference value for the width of change was larger. However, increasing the number of repeated tightening of the reference value for the error rate increased, but has reduced the width of the observed changes.

• Journal of the Korean Orthopaedic Association
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• v.56 no.6
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• pp.498-503
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• 2021

Purpose: The aim of this study were to find ideal entry point of straight antegrade humeral intramedullary nail (SAHN) for the treatment of proximal humerus fracture in Korean and to analyze anatomical conformity using computed tomography. Materials and Methods: From May 2014 to October 2016, the study was conducted retrospectively on 74 Korean patients who had taken computed tomography on both normal and affected shoulder joint as result of shoulder injury. The mean age of the patients was 64.5 years (range, 22-95 years). Radiologic evaluation was done using multiplanar reconstruction technique of the computer tomography on normal proximal humerus. We located ideal entry point of SAHN as the point where humerus intramedullary center axis and humeral head meet. Distance between the entry point and local anatomical landmark was measured. We defined the critical distance as the distance between entry point and the most medial point of the supraspinatus attachment site. For adequate fixation and avoidance of injury to rotator cuff, critical distance should be over 8 mm according to Euler, and we defined the critical type when it is less than 8 mm. Critical distance, sex, age, height, body weight, body mass index was evaluated for the statistical significance. Results: The ideal entry point was as follows: the mean anteroposterior distance, the sagittal distance to the lateral margin of bicipital groove, was 11.5 mm and the mean mediolateral distance, the coronal distance to the lateral margin of grater tuberosity, was 20.5 mm. The mean critical distance, distance from the entry point to the just medial to insertion of the supraspinatus tendon, was 8.0 mm. Critical type with critical distance less than 8 mm was found in 41 in 74 patients (55.4%). Conclusion: The ideal entry point of SAHN in Korean was located on 11.5 mm posteriorly from the lateral margin of bicipital groove and 20.5 mm medially from lateral margin of greater tuberosity. More than half of the cases were critical type. Since critical type can possibly cause rotate cuff injury during nail insertion on entry point, surgeon should consider anatomical variance before choosing surgical option.

• The Journal of the Korean bone and joint tumor society
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• v.11 no.2
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• pp.126-133
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• 2005

Purpose: to know the treatment result of squamous cell carcinoma in extremity had poor prognosis with risk factor including burn scar and chronic osteomyelitis. Material and Methods: Between Octorber 1993 and September 2002, 20 patients with squamous cell carcinoma in extremity had no distant metastasis was got operation and followed over 36 months. Amputation was done when it was hard to get enough wide margin or neurovascular structure was involved instead of wide excision. Mean age of patients was 57.2 years old and male to female was 16 to 4. TMN staging and histologic grading were performed. Results: There were 6 metastasis (30%) in 20 cases for mean 48.3 months (36-84 months). 3 metastasis to local lymph node and 3 distant metastasis were happened at lung (in 3 cases) and thorasic vertebra (in 1 case). Survival was 18 cases at last look. 5-year survival rate was 50%. 3 local recurrence was developed at average 11 months (4-18 months). Complication was focal skin defect after wide excision and skin graft in 2 cases. The patients by wide excision got average 1.9 time operation and by amputation got average 1.3 time. Conclusion: Squamous cell carcinoma at extremity in Korea had high metastasis rate due to burn scar and chronic osteomyelitis, and it showed equal treatment result which treated by wide excision compared with amputation.

• Journal of Dental Rehabilitation and Applied Science
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• v.26 no.3
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• pp.323-337
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• 2010

The objective of this study was to examine the availability of the new impression coping by comparing with conventional coping in implant pick-up impression technique. Five implant fixtures were installed on #14, 21, 23, 25, 27 in acrylic resin model. That model with 5 fixtures was standard model, which was divided 3 groups; using new flag type impression coping, conventional impression coping splinted with self-curing resin, conventional impression coping without splinting. We made metal circular cones for calculation 3-dimensional coordinates by attaching to implant fixtures or analogs. Three-dimensional relationships of each model were calculated. Data was analyzed by multiple ANOVA and Bonferroni. The accuracy of impression between using new flag type impression coping and conventional impression coping did not show differences in 3 - dimensional analysis.Within limitations of this study, the new flag type impression coping is available in implant pick-up impression technique.

• Journal of Dental Rehabilitation and Applied Science
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• v.26 no.4
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• pp.419-432
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• 2010

Various torque generating devices have been developed and employed to apply a proper torque. These devices are usually calibrated by the manufacturer to apply appropriate torque levels for their specific implants and attachments. The purpose of this investigation was to determine and compare the accuracy of the torque controllers. In this study, 4 types of torque controllers were used; torque limiting device(TLD), torque indicating device(TID) and contra angle torque driver(CA), electronic torque controller(ETC). Digital torque gauge was employed to measure the de-torque value. Thirty cycles of tightening and loosening were repeated with each torque controller. All implant torque controllers have shown slight errors and deviations. The contra angle torque driver exhibited the most accurate data. In the limitation of this study, it would be recommended that the implant torque controllers should be checked whether uniformed and precise torque can be generated and a measuring error should be corrected.