지대주 나사 풀림 방지를 위한 새로운 Lock Screw 시스템의 효과에 대한 유한요소해석적 연구

Purpose: The purpose of this finite element analysis study is to introduce the novel Lock screw system and analyze its mechanical property to see if it can prevent abutment screw loosening. Materials and Methods: The Lock screw is a component tightened on the inside of the implant abutment which applies compressive force to the abutment screw head. To investigate the effect, modeling was done using CAD program and it was analyzed by finite element analysis under various load conditions. First, the preload was measured according to the tightening torque of the abutment screw then it was compared with the theoretical value to verify the analytical model. The validated analytical model was then divided into those with no external load and those with 178 N, and the tightening torque of the lock screw was changed to 10, 20, 30 Ncm respectively to examine the property of stress distribution on the implant components. Results: Using Lock screw under various loading conditions did not produce equivalent stresses beyond the yield strength of the implant components. In addition, the axial load was increased at the abutment-abutment screw interface. Conclusion: The use of Lock screw does not exert excessive stress on the implant components and may increase the frictional force between the abutment-abutment screw interface, thus it is considered to prevent loosening of the abutment screw.ope

Use of digital scan data for evaluation of edentulous ridge relationship : a case report for removable prosthesis with unilateral cross bite

After the teeth were extracted, maxillary and mandibular alveolar ridges show the opposite resorption pattern and as a result, the mandibular arch is enlarged than maxillary arch relatively. In this situation, we should evaluate both alveolar ridge relationship and arrange the artificial teeth properly for stability of removable prosthesis. This case is a 77 years old male patient who wishes to make removable prosthesis and has atrophic alveolar ridge. By use of model scanner and CAD software, the angle between interalveolar crest line and occlusal plane was easily measured. Depending on the measurement, the artificial teeth are arranged in unilateral cross bite and after completion, patientwas satisfied with the denture which showed proper stability, retention, support.ope

훈증소독의 효과와 과제 : 규장각 방충소독을 중심으로

규장각한국학연구원(이하 약칭 "규장각"으로 함)은 261,000여권의 고전적을 소장하고 있으며 이를 보존하는 것을 제 1의 임무로 부여 받고 있다. 보존이란 원혈 그대로를 영구히 후세에 전하는 일이다. 자료의 보존 방법으로는 소독(방제), 포쇄, 채광, 항온항습, 지질의 화학약품처리 방법이 있고, 또한 이용의 증진을 위해서는 복본제작(영인복원) 및 대체 매체 개발로 디지털화, 마이크로필름화가 있다. 본고에서는 소독만을 다루고자한다. 규장각은 매년 3주간씩 폐관하며 소독을 실시하고 있으나 일부 연구자들의 불만이 끊이지 않는 것이 사실이다. 따라서 1주를 줄여서 2주일(14일)간만 하였으면 한다. 그러나 충분히 검증되지 않은 약효 때문에 기간을 줄여서 실시 할 수 있을지 의문이다. 규장각 소독문제는 2006년도 핫이슈로 되었다. 다행히, 최근 천연소독약제의 개발로 상시소독이 가능하게 되어서 기간 문제는 다소해소할 수 있게 되었다. 본고에서는 소독방법 중에서 훈증소독의 방법을 제시하고, 아울러 개선방안을 찾고자 한다

Evaluating the Precision of Automatic Segmentation of Teeth, Gingiva and Facial Landmarks for 2D Digital Smile Design Using Real-Time Instance Segmentation Network

Digital smile design (DSD) technology, which takes pictures of patients' faces together with anterior dentition and uses them for prosthesis design, has been recently introduced. However, the limitation of DSD is that it evaluates a patient with only one photograph taken in a still state, and the patient's profile cannot be observed from various viewpoints. Therefore, this study aims to segment the patient's anterior teeth, gingiva and facial landmarks using YOLACT++. We trained YOLACT++ on the annotated data of the teeth, lips and gingiva from the Flickr-Faces-HQ (FFHQ) data. We evaluated that the model trained by 2D candid facial images for the detection and segmentation of smile characteristics. The results show the possibility of an automated smile characteristic identification system for the automatic and accurate quantitative assessment of a patient's smile.ope

규장각 디지털 아카이브의 구축 의의

아카이브 시스템이란 분실 파손에 대비하여 컴퓨터 프로그램이나 데이터 파일의 사본을 보존하는 시스템(각종 백업, CD, DVD, 고용량 저장장치에 담겨진 데이터 파일 등), 또는 정부, 관공서 및 기록보존소를 의미하는 문서보존관(Archives)에서 유래된 말이다. 이상은 오프라인 상에서 의미하는 것이며, 디지털 아카이브란 소장품이나 자료 등을 디지털로 구축(복원, 사본 이미지 및 텍스트, 영상 등)하여 보관, 관리하는 일종의 데이터베이스로서 그 대상은 문자, 화상정보, 3차원 정보, 음악, 녹음자료 등 각종 유형의 전자적 디지털정보가 포함된다. 규장각 디지털 아카이브 시스템은 홈페이지에서는 응용 프로그램을 지원하기 어렵고 권한부여나 공동구축 등 멀티테스킹 게시판 구축도 기술적으로 어려움이 있어서, 2007년 3월에 규장각 운영위원회 및 간부회의로부터 개발 승인을 받아 2007년 4월부터 설계 및 디자인에 들어갔고, 2007년 5월부터 프로그램개발에 착수하여 2007년 8월에 테스트 및 시험가동, 2007년 10월에 정식으로 오픈을 하게 되었다. 오픈식 전에 개발 보고 및 사용법 등 직원 교육을 실시하였다

The use of implant surveyed fixed prosthesis for removable partial denture with a few unilateral remaining teeth : a case report

As implant can be covered by National Health Insurance Service (NHIS), it was increased the interest in the removable partial denture (RPD) with the surveyed fixed prosthesis supported by implant fixture. To achieve predictable result, it needs the prudent implant planning by basic principles of RPD and patient’s residual ridge. This 67 years old age male had a few unilateral remaining teeth, and hoped the treatment covered by NHIS. As using CAD software, the position of implant is planned with regarding to occlusal table of provisional denture, basic principles of RPD, and resorbed residual ridge. The definitive prostheses can ensure the stability and retention of removable prosthesis. When planning implant fixed prostheses, the digital technique was utilized to consider basic principle of RPD and resorbed residual ridge. As a result, it provided satisfactory prostheses.ope

Accuracy Improvement of Intraoral Scanning and Buccal Bite Registration Using Healing Abutment as Landmarks: An In Vitro Study

This study aimed to determine the influence of the healing abutment (HA), placed at the implant placement site, on the accuracy of intraoral scanning and buccal bite registration in quadrant maxillary and mandibular models when using three types of intraoral scanner (IOS) and elucidate the distribution of arch distortion. Six experimental groups based on whether the HA was connected and the location of missing teeth were digitized using one laboratory scanner (Identica T500) and three IOSs (Trios 3, CS3600, and i500). Three-way ANOVA was used to analyze the effects of the scanner, location and number of missing teeth, and HA using Tukey investigation analyses for multiple comparisons (α = 0.05). Linear distances between hemispheres from the upper and lower arches were analyzed using the Jonckheere–Terpstra trend test to investigate the tendency of distortion from anterior to posterior tooth positions (α = 0.05). The accuracy of IOSs in groups with HAs was found significantly more accurate than groups without HAs. There was a significant trend in distortion from anterior to posterior tooth positions when using the Trios 3 and i500 IOSs. The scanning accuracy was affected by the presence of an HA, and the distortion along with the arch span may vary with the IOS utilized.ope

A Review of the Digital Impression Taking Technique of Implants by Using a Coded Healing Abutment

Conventional implant-level impression techniques required removal of healing abutments at least twice until the placement of definitive restorations. The use of coded healing abutments may simplify this procedure since they provide information necessary to design implant abutments such as implant hex position and platform diameter. This could minimize peri- implant tissue irritation and reduce the laboratory time and costs when used in combination with an intraoral scanner. The aims of this article were to describe the structure, clinical availability, and limitations of the coded healing abutments and review the studies related to their use.ope

Method development on energy-flow networks by using critical pathes

학위논문 (석사)-- 서울대학교 대학원 : 산업공학과, 2014. 8. 홍성필.에너지-흐름 네트워크 문제는 마디 간 에너지 차이가 호의 흐름을 발생시키는 네트워크 상에서 흐름균형, 에너지균형, 흐름 및 에너지 상하한 등의 제약조건을 만족시키면서 비용함수를 최소화하는 문제를 의미한다. 본 논문에서는 다양한 현실문제를 포함하는 에너지-흐름 네트워크 문제를 수리적으로 정의하고 그 문제가 NP-Hard에 속함을 보인다. 그리고 몇 가지 관찰을 통해 하한과 가능해를 동시에 제시하는 알고리듬을 제안한다. 몇 가지 문제에 적용한 결과 실험적으로는 대체로 하한과 아주 가까운 해를 출력한다는 사실을 확인했다.Energy-Flow network problem is the problem that minimizes total energy cost with flow-balance, energy balance and upper and lower bound of energy and flow constraints. In this paper, we de칗e the E-F network problem which includes various problems in 칎ld such as water distribution problem and gas pipeline problem. The problem is NP-hard. We present the Critical Path algorithm which is faster than the most common algorithm and print out the feasible solution and lowerbound of objective. The results show that the proposed method achieves lowerbound-close solution.국문 초록 1. 서론 2. 문제 정의 및 모형화 3. 관찰 4. 해법 5. 현실문제 응용 및 결과 6. 결론 및 추후 연구 과제 참고 문헌 영문 초록Maste

Transfer Learning via Deep Neural Networks for Implant Fixture System Classification Using Periapical Radiographs

In the absence of accurate medical records, it is critical to correctly classify implant fixture systems using periapical radiographs to provide accurate diagnoses and treatments to patients or to respond to complications. The purpose of this study was to evaluate whether deep neural networks can identify four different types of implants on intraoral radiographs. In this study, images of 801 patients who underwent periapical radiographs between 2005 and 2019 at Yonsei University Dental Hospital were used. Images containing the following four types of implants were selected: Brånemark Mk TiUnite, Dentium Implantium, Straumann Bone Level, and Straumann Tissue Level. SqueezeNet, GoogLeNet, ResNet-18, MobileNet-v2, and ResNet-50 were tested to determine the optimal pre-trained network architecture. The accuracy, precision, recall, and F1 score were calculated for each network using a confusion matrix. All five models showed a test accuracy exceeding 90%. SqueezeNet and MobileNet-v2, which are small networks with less than four million parameters, showed an accuracy of approximately 96% and 97%, respectively. The results of this study confirmed that convolutional neural networks can classify the four implant fixtures with high accuracy even with a relatively small network and a small number of images. This may solve the inconveniences associated with unnecessary treatments and medical expenses caused by lack of knowledge about the exact type of implant.ope