• 대한치과기공학회지
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• 제37권1호
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• pp.9-15
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• 2015

Purpose: The purpose of this study was to compare the accuracy of the maxillary three-unit fixed dental prosthesis (FDPs) made using two CAD/CAM milling machines : DCM Group(Dentaim CAD/CAM milling machine), WCM Group(Wieland CAD/CAM milling machine). Methods: Each of 10 duplicate models was scanned by blue light scanner(Identica, Medit, Korea), and the three-unit FDPs (STL file) was designed using DelcamCAD. A total of 20 three-unit FDPs was fabricated, comprising 2 groups of 10 specimens each (shrinkage ratio is 1:1). The first three-unit FDPs STL file was used as a CAD reference model (CRM). Obtained STL files by scanning the inner surface of three-unit FDPs were convened into the point clouds-ASC II files. Discrepancies between the point clouds and CRM were measured by superimposition software. Statistical methods to analyze the data were used non-parametric method. The mean (SD) values were compared by a Mann-Whitney U-test. Type one error rate was set at 0.05. Results: WCM group had small discrepancies with $2.17{\mu}m$ of mean value compared to $4.44{\mu}m$ in DCM group. The accuracy values between the two groups showed a sratistically significant difference (Table 2, p<.05). Conclusion: The accuracy of the three-unit fixed dental prosthesis(FDPs) made of two CAD/CAM milling machines were statistically different. Accuracy with which the prosthesis made of WCM group was superior.

• Journal of Audiology & Otology
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• 제25권2호
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• pp.104-109
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• 2021

Background and Objectives: To assess whether the audiological and clinical outcomes of type 0 tympanoplasty (T0) performed using cartilage were comparable with those of ossiculoplasty in patients who underwent canal wall down mastoidectomy (CWDM). Subjects and Methods: This study included patients who had chronic otitis media with cholesteatoma and underwent CWDM with ossiculoplasty involving partial ossicular replacement prosthesis (PORP), total ossicular replacement prosthesis (TORP), or T0. Anatomical success rates and hearing outcomes were analyzed. Results: Seventy-two patients were included in this study; 29 of them underwent CWDM with T0, 27 underwent CWDM with PORP, while 16 underwent CWDM with TORP. The difference in mean improvement in the air-bone gap (ABG) between the groups was not significant. The differences in the rates of ABG closure to ≤10 dB HL (p=0.030) and ≤20 dB HL (p=0.029) were significant. There were significant differences in improvements in the ABG at 3 kHz among the PORP, TORP, and T0 groups. Conclusions: The audiological outcomes of CWDM with ossiculoplasty seemed to be better than those of CWDM with T0 with no significant difference in the incidence of complications following ossiculoplasty and T0.

• 대한청각학회지
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• 제25권2호
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• pp.104-109
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• 2021

Background and Objectives: To assess whether the audiological and clinical outcomes of type 0 tympanoplasty (T0) performed using cartilage were comparable with those of ossiculoplasty in patients who underwent canal wall down mastoidectomy (CWDM). Subjects and Methods: This study included patients who had chronic otitis media with cholesteatoma and underwent CWDM with ossiculoplasty involving partial ossicular replacement prosthesis (PORP), total ossicular replacement prosthesis (TORP), or T0. Anatomical success rates and hearing outcomes were analyzed. Results: Seventy-two patients were included in this study; 29 of them underwent CWDM with T0, 27 underwent CWDM with PORP, while 16 underwent CWDM with TORP. The difference in mean improvement in the air-bone gap (ABG) between the groups was not significant. The differences in the rates of ABG closure to ≤10 dB HL (p=0.030) and ≤20 dB HL (p=0.029) were significant. There were significant differences in improvements in the ABG at 3 kHz among the PORP, TORP, and T0 groups. Conclusions: The audiological outcomes of CWDM with ossiculoplasty seemed to be better than those of CWDM with T0 with no significant difference in the incidence of complications following ossiculoplasty and T0.

• 대한의용생체공학회:의공학회지
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• 제19권3호
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• pp.291-296
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• 1998

설계방법론을 적용하여 새로운 기계식 인공심장판막을 설계 하였다. 심장판막의 기능을 정의하고 기능구조 결과에 따라 체계적인 설계변이 탐색을 수행하였으며, 이에 의하여 다양한 가능성을 검토하였다. 심장판막에 요구되는 제반 요구조건들을 기준으로 하여 최적 모델을 결정하였다. 설계된 심장판막의 시제품을 제작하여 모의순환계를 이용한 거동특성측정 실험을 수행하였다. 설계된 신규모델은 유량과 파형특성 및 거동특성면에서 대체로 양호한 결과를 보였다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2007년도 하계학술대회 논문집
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• pp.250-252
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• 2007

In this paper presents a control algorism for myoelectric hand prosthesis(MHP) with 2 degree of freedom(DOF), which consists of a mechanical hand, a surface myoelectric sensor(SMES) for measuring myoelectric signal, a control system and a charging battery. The actuation for the 2-DOF hand functions such as grasping and wrist rotation was performed by two DC-motors, and controlled by myoelectric signal measured from the residual forearm muscle. The two controllers were made of a RISC-type microprocessor, and its software was executed on a real-time kernel. The experimental results were showed that the proposed a control algorism is feasible for the MHP.

• Journal of Chest Surgery
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• 제21권4호
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• pp.706-710
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• 1988

Intravascular hemolysis occurs in the majority of patient with mechanical valve prosthesis. The primary cause is mechanical trauma to red cells from turbulent blood flow through the prosthesis. Degree of hemolysis is dependent upon the type, size and material of valve and aggravated by paravalvular leakage. Clinically important hemolytic anemia is required medical management or consideration of reoperation. In severe hemolysis, reoperation is recommended without delay when seems to be renal failure. In this case, postoperative severe mechanical hemolysis was developed immediately after aortic valve replacement with St. Jude medical valve in a 13 year-old male patient. Neither significant paravalvular leakage nor valvular dysfunction was found through redo, but the mechanical valve was strongly suspected the cause of severe hemolysis. The St. Jude Medical valve was changed with Ionescu-Shiley bioprosthesis and any significant clinical problems were not noted through the postoperative course.

• 대한치과보철학회지
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• 제31권4호
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• pp.611-624
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• 1993

The purpose of this study was to analyze the stress distribution of the natural teeth, the implant, the prosthesis and the supporting tissue according to the types of implant and connection modality in the five-unit fixed partial denture with a implant pier abutment. A Two dimensional stress analysis model was constructed to represent a mandible missing the first and second premolars and first molar. The model contained a canine and second molar as abutment teeth and implant pier abutments with and without stress-absorbing element. Finite element models were created and analyzed using software ANSYS 4.4A for IBM 32bit personal computer. The results obtained were as follows. 1. Implant group, compared to the natural teeth group, showed a maximum principal stress at the superior portion of implants and a stress concentration at :he neck and end portion. 2. Maximum principal stress and maximum Von Mises stress were always lower in the case of rigid connection than nonrigid connection. 3. A cylinder type implant with stress absorbing element and screw type implant were generally similar in the stress distribution pattern. 4. A screw type implant, compared to the cylinder type implant, showed a relatively higher stress concentration at both neck and end portion of it. 5. Load B cases showed higher stress concentration on the posterior abutments in the case of nonrigid connector than rigid connector. 6. A maximum displacement was always lower in the case of rigid connection than nonrigid connection. These results suggest that osseointegrated implant can be used as an intermediate abutment.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제46권2호
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• pp.133-142
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• 2020

Objectives: In this study, we determined the incidence and pattern of screw loosening in patients who received dental implants. Materials and Methods: Patients who received implants between January 2008 and October 2013 and completed their prosthetic rehabilitation were evaluated for the incidence, frequency, and onset of screw loosening using dental charts and radiographs. The association between each factor and screw loosening was analyzed using the chi-square test and a multivariate analysis with binary logistic regression models (P<0.05). Results: Total 1,928 implants were placed in 837 patients (448 males, 389 females), whose follow-up period after loading varied from 0.25 to 70 months (mean period, 31.5 months). Screw loosening occurred in 7.2% of implants. Most cases occurred less than six months after loading. Among those, 22.3% experienced recurrent screw loosening. Screw loosening was most common in the molar region (8.5%) and frequently associated with an implant diameter of ≥5 mm (14.2%). External implant-abutment connections (8.9%) and screw-retained implant prostheses (10.1%) showed higher incidence of problems than internal implant-abutment connections and cement-retained implants, respectively. Screw loosening was most common in implant prostheses with single crowns (14.0%). Conclusion: Within the limits of the current study, we conclude that the incidence of screw loosening differs significantly according to the position of implant placement, the type of implant and manufacturer, implant diameter, the type of implant-abutment connection, the type of retention in the implant prosthesis, and the type of implant prosthesis.

• 로봇학회논문지
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• 제19권2호
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• pp.159-168
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• 2024

Lower limb amputees are increasing due to various reasons. It is difficult for lower limb amputees to walk without an assistive device such as a prosthetic leg. In this paper, an electronically controlled knee-type prosthetic leg with a 4-bar linkage structure for lower limb amputees was developed. The knee-type prosthetic leg has a 4-bar linkage structure and assists walking by using an integrated drive module. The torque is 90 Nm, the rotation speed is up to 120 deg, and it weight 1.9 kg, so it is lighter than a commercial prosthetic leg, so it can be used for a long time because there is less fatigue when walking. An integrated control board was developed by applying various sensors and microprocessor. The motor drive and encoder are built into the integrated drive module. The integrated control board and integrated drive module communicate using CAN. When a lower limb amputee wears a knee-type prosthetic leg and walks, it shows a shape similar to the swing phase graph of a normal people, and it is possible to walk naturally while walking.

• Clinics in Shoulder and Elbow
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• 제10권1호
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• pp.84-91
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• 2007

목적: 총 7예의 금속형 요골 골두 치환술을 경험하여 적응증을 바탕으로 국내 요골두 치환술의 실태와 필요성을 소개하고자 하였다. 대상 및 방법: 2006년 4월부터 고려대학교 정형외과 교실에서 경험하였던 총 7예의 환자를 대상으로 수술 적응증, 수술 소견 및 수술 후 상태를 조사하였다. 그리고 치환물의 술 전 준비상태와 보험 적용 여부를 조사하였다. 금속형 치환물은 양극성 유형의 요골두 치환물(Tornier SA. Saint-Ismier, France)을 사용하였다. 결과: 전 예에서 요골두 분쇄 골절 이외에 $1{\sim}2$ 곳의 다른 골절 및 연부조직 손상을 동반한 복합 손상으로 요골두 치환술의 적응증에 해당되었다. 요골두 골절은 Mason 분류상 III형이 3예, IV형이 4예였고 분쇄골절로 인해 만족할만한 내고정을 얻지 못해 치환술을 시행하였다. 술 후 평가에서는 우수 2예, 양호 4예, 불량 1예였고 추시 시 치환물의 문제로 인한 합병증은 보이지 않았다. 술 전 수술 기구의 공급 부족으로 2예에서 수술 날짜를 변경하였고 치환물에 대한 비용은 산재 환자 2예를 제외한 5예에서 환자 개인이 부담하였다. 결론: 요골 골두의 분쇄를 포함한 주관절의 복합 손상에서 금속형 치환물은 술 전 계획 하에 준비되어야 하며, 의료보험의 적용으로 의사 및 환자들의 치료 선택에 도움을 주어야 할 것으로 생각되었다.