Journal of the Korea Academia-Industrial cooperation Society
/
v.20
no.7
/
pp.20-25
/
2019
In this paper, the structural weakness analysis and quality improvement of small fixed wing UAV of the hard landing type were studied. Unlike conventional aircraft, small UAV does not use runways because of its small size. Instead, small UAV use hand launch takeoff and hard landings. This type has many operational advantages because it can take off and land in a narrow space. But, the hard landing has a strong impact on the structure of the UAV and can cause serious damage. In order to analyze the exact cause of this phenomenon, the structural analysis was carried out using the 3D structural analysis program (ABAQUS) to identify the location of the fracture. And to improve the accuracy of the structural analysis, properties of the material were obtained through specimen test. As a result of the analysis, structural weaknesses were identified and improved. Thus, the validity of the study was verified by demonstrating the quality of enhanced structure through a real impact test at a higher level of 1.5 times the maximum impact during operation.
Journal of the Korea institute for structural maintenance and inspection
/
v.25
no.6
/
pp.262-269
/
2021
This paper conducts an evaluation of the structural performance of the lap splice detail of SD700 headed bar experiment for developing an RC beam with different depths joint details. The experiment variable is lap splice length, yield strength, and end anchorage of main reinforcements. For all specimens, a headed bar was applied to the main reinforcement of the beam with low depth (B2), and the beam with high depth (B1) was applied to the main reinforcement with two splice methods: straight headed bar and 90° hooked-headed bar. The experimental results were that specimens of applying SD500 and SD600 had the results of flexural fracture at the lap splice location, which maximum load was similar. For specimens of appling SD500, the 90° hooked-headed bar of B1, suppressed horizontal cracks in the lap splice section compared to the straight headed bar. Specimens of applying an SD 700 headed bar had the results of brittle anchorage failure. In addition, maximum load was increased with the lap splice length increasing. For specimens of applying SD700 headed bar, test for test maximum load/theoretical load for test development length/design development length were estimated to be 1.30~1.48 for the ACI 318-19 equation, and 1.14~1.30 for the KDS-2021 equation. Thus, ACI 318-19 equation had conservatively greater safety factors as estimated development lengththened.
Journal of the Korea institute for structural maintenance and inspection
/
v.28
no.2
/
pp.53-60
/
2024
Prestressed concrete (PSC) bridges are vulnerable to corrosion and fracture of tendons, and in particular, structures using the internal post-tensioned with grouted system have difficulties in maintenance due to limitations of inspection. In this study, the actual behavior of PSC I girder bridge was analyzed according to tendon damage. The target PSC I girder bridge, an decommissioned highway bridge of upper and lower bridges, had the service period of 33 years and 20 years, respectively. Deflection and concrete strain were measured according to the location of damaged tendon and loading method. Regardless of the age of the bridge, its structural performance decreased when the damaged tendon was closer to the center of the girder. The change in behavior increased as the truck load approached to the girder where the tendon cut. If the load was applied to the adjacent girder where the tendon was cut, the structural performance was likely to be maintained due to the influence of the entire structural system. The change in deflection was difficult to observe visually, while the concrete strain exceeded the cracking strain. Therefore, it is recommended that future monitoring and inspection of PSC I girder bridges should focus on concrete strain or cracking.
Dong-Hui Nam;Pil-Jong Kim;Ki-Tae Koo;Yang-Jo Seol;Yong-Moo Lee;Young Ku;In-Chul Rhyu;Sungtae Kim;Young-Dan Cho
Journal of Periodontal and Implant Science
/
v.54
no.1
/
pp.53-62
/
2024
Purpose: This study aimed to evaluate the long-term cumulative survival rate (CSR) of dental implants with micro-threads in the neck over a 10-year follow-up period and to examine the factors influencing the survival rate of dental implants. Methods: This retrospective study was based on radiographic and dental records. In total, 151 patients received 490 Oneplant® dental implants with an implant neck micro-thread design during 2006-2010 in the Department of Periodontology of Seoul National University Dental Hospital. Implant survival was evaluated using Kaplan-Meier analysis. Cox proportional hazard regression analysis was used to identify the factors influencing implant failure. Results: Ten out of 490 implants (2.04%) failed due to fixture fracture. The CSR of the implants was 97.9%, and no significant difference was observed in the CSR between external-and internal-implant types (98.2% and 97.6%, respectively, P=0.670). In Cox regression analysis, 2-stage surgery significantly increased the risk of implant failure (hazard ratio: 4.769, P=0.039). There were no significant differences in influencing factors, including sex, age, implant diameter, length, fixture type, location, surgical procedure, bone grafting, and restoration type. Conclusions: Within the limitations of this retrospective study, the micro-thread design of the implant neck was found to be favorable for implant survival, with stable clinical outcomes.
Park, Ki-Bong;Kang, In-Hyi;Choi, Nam-Kil;Jang, Young-Il;Jeon, Ju-Seob
Journal of radiological science and technology
/
v.28
no.3
/
pp.203-209
/
2005
Objective True lateral scapular image was very important to diagnosis the scapular fracture and dislocation induced by traumatic injury. The aim of this study was to know the patient rotation angle to be showing the scapular true lateral in Korean. Subjects and Materials Thirty patients(22men, 8 women, mean ages 53.4)with scapular pain, had supine anteroposterior projection taken with $32^{\circ}$, $37^{\circ}$, $42^{\circ}$ trunk rotation angle changing the manual angulation material. Radiographs were evaluated independently by 5 experienced observers(1 orthopedics surgery specialist, 1 diagnostic radiology specialist, 3 radiological technologist) They assessed overlab of vertebral border and axillary border of scapular as follows; Totally overlapping of vertebral border and axillary border is 4, partially overlapping is 3, not overlapping is 2 and oblique location with two borders is 1. All observers scored using by PACS monitor. Results $32^{\circ}$ trunk rotation was scored $1.53{\pm}0.39$, $37^{\circ}$ trunk rotation was scored $3.83{\pm}0.15$ and $42^{\circ}$trunk rotation was scored $2.17{\pm}0.43$. There was no difference(p<0.05) between group of more than 100cm of the girth of the chest and group of less than 100cm. Similarly, men and women group showed no difference(p<0.05) with trunk rotation statistically. Conclusions There was no result of trunk rotation angle to radiograph the true scapular lateral image up to date. This studies were summarized as follows; Adaptation of $37^{\circ}$ trunk rotation was the best to show the true scapular lateral image in Korean. Our results were very useful to get the true scapular lateral images in clinic.
Purpose: The aim of this study was to evaluate clinical outcomes of implant supported fixed-hybrid prostheses (FHP) in the fully edentulous arches. Materials and methods: Patients in this retrospective study were restored with fixed-hybrid prostheses supported by 4 to 6 implants and functioned more than 1 year of loading. Outcome measures were marginal bone change of implant related with sex, anatomical location (maxilla vs. mandible), opposing teeth, loading time of patients, tilting of posterior implant by Mann- Whitney U test and cantilever length of superstructure by regression analysis, and complication rates. Significance level was set P<.05. Results: A total number of 84 implants (16 restorations) placed in 16 patients were observed for 28 months and mean marginal bone loss was $0.53{\pm}0.39mm$. There were no differences of marginal bone loss according to sex, anatomical location (maxilla vs. mandible), opposing teeth, loading time of patients (P>.05), and cantilever length was not significantly related with a marginal bone loss of implant next to cantilever (P>.05). Complication was shown in 11 patients and veneer fracture and dislodging of artificial teeth were most prevalent. Conclusion: Within the limitations of this study, although marginal bone loss of FHP was very little, complication rates were high. Irrespective of tilting of most posterior implants, marginal bone loss of most posterior implants next to cantilever was less than those of the other implants positioned anteriorly. Cantilever length (<17 mm) did not affect a marginal bone loss of most posterior implants.
The location and geometry of the Ulsan Fault play important roles in interpreting tectonic evolution of the southeastern part of the Korean Peninsula. Dipole-dipole electrical resistivity surveys and seismic refraction surveys were carried out in the Yaksoo area, Ulsan in order to measure the thickness of the alluvium covering the Ulsan Fault and to find associated fracture zones and possibly the location of its major fault plane. The collected data were analyzed and interpreted. Some results reported previously by others were also used in this interpretation. No low resistivity anomalies were found in the cross-sectional resistivity image of the survey line located in the east of the Dong River. In contrast, well-developed continuous low resistivity anomalies were detected in the west of the Dong River. This strongly suggests that the major fault plane of the Ulsan Fault is located under or in the west part of the Dong River. Two refraction boundaries corresponding to the underground water level and the bottom of the alluvium were found by refraction surveys carried out on the limited part of the east survey line. The thickness of the alluvium was found to be about 30 m. Small faults in the basement rock identified by reflection surveys were not detected by both resistivity and refraction seismic surveys. This might be explained by assuming that low resistivity anomaly is more closely related to the clay contents than the water contents. On the other hand, it may be resulted by the limited resolution of the resistivity and refraction surveys. Detailed study is required to clarify the reason. Resistivity survey is frequently considered to be a good exploration method to detect subsurface faults. However, it appears to be less useful than reflection seismic survey in this work. In dipole-dipole resistivity survey, the number of separation should be increased to survey deeper subsurface with the same resolution. However, signal to noise ratio decreases as the number of separation increases. In this survey area, the signal to noise ratio of up to sixteen separations was good enough based on the statistical properties of measurements.
Lim Hong Chul;Chun Seung Joo;Rho Young Jin;Hwang Jin Ho;Park Chan Eung;Kim Tae Un
Journal of Korean Orthopaedic Sports Medicine
/
v.2
no.2
/
pp.163-167
/
2003
Purpose: The purpose of this study is to describe causes and injury mechanisms during inline skating and to find preventive measures .Materials and Methods: We have carefully selected 57 patients who have been treated in our hospital and nearby hospital. There are 37 males and 20 females, and mean age is 9 years 9 months (range,6-40 years old) . We have meticulously investigated their injured sites, their favorite location for inline skating , their use of protective means while they were on the wheels and their injury mechanisms . Results: Injury consisted of 50 fractures,1 meniscal tear,2 medial collateral ligament rupture and 4 contusion or sprain. Fracture sites varied as follows : 33(66$\%$) cases in distal radius and ulna,5(10$\%$) in elbow. 3(6$\%$) in diaphysis of humerus, etc Location at the time of injury varied as follows : 22 cases(39$\%$) in their apartment complex, 19 cases in (33$\%$) narrow streets, and 16 cases(28$\%$) in parks Only five patients admitted that any means of protection were used.2 cases only had knee pad on , 1 case put on elbow pad in addition, and 2 cases put on wrist guard as well. However none of the patients had helmet on Conclusion: We would strongly like to stress the importance of using sufficient protections and of choosing area where it is safe to ride, in order to reduce the risk of accidents. In addition, continuous and effective prior education from inline skate circles may be in order before riding the inline skate.
Kim, Tae Yong;Yoon, So Hee;Ko, Jung Hoon;Lee, Tae Ho;Yi, Seung Rim
Journal of the Korean Orthopaedic Association
/
v.55
no.4
/
pp.324-330
/
2020
Purpose: Korean studies on the prevalence of a tarsal coalition are quite rare, and there are very few reports on the prevalence of multiple tarsal coalitions among adults in the foreign literature. Therefore, this study examined the characteristics and prevalence of tarsal coalition in the Korean population based on imaging tests. Materials and Methods: The prevalence of tarsal coalition and its anatomical location and histological classification were reviewed retrospectively among 4,711 patients (4,454 males and 257 females) with an ankle sprain or ankle fracture who underwent foot and ankle computed tomography and magnetic resonance imaging between March 2009 and February 2019 at the authors' institution. Results: Over a period of 10 years, 78 patients (1.7%) had a tarsal coalition, among whom 53 patients (67.9%) had an isolated tarsal coalition and 25 patients (32.1%) had multiple tarsal coalitions. Regarding the anatomical location, a talocalcaneal coalition was the most common type in both isolated (31 patients, 37 cases [62.7%]) and multiple (22 patients, 23 cases [45.1%]) tarsal coalitions. In the isolated coalition group, the second-most common type was calcaneonavicular coalition (10 patients, 16.9%), followed by naviculocuneiform (nine patients, 15.3%) and cuboidonavicular coalitions (three patients, 5.1%). In the multiple coalition group, the second-most common coalition type was calcaneonavicular coalition (14 patients, 14 cases [27.5%]), followed by talonavicular coalition (six patients, six cases [11.8%]). From a total of 60 cases of talocalcaneal coalition, 24 cases (40.0%) were in the posterior facet, 18 cases (30.0%) in the middle facet, and four cases (6.7%) in the anterior facet. Regarding the histological classification, cartilaginous coalition was the most common in both single (32 patients, 35 cases [59.3%]) and multiple (20 patients, 37 cases [72.5%]) coalition groups. Conclusion: The present study found that talocalcaneal coalition was the most common type of tarsal coalition. In contrast to previous reports that a talocalcaneal coalition generally occurs in the middle facet, it was usually observed in the posterior facet in the present study. In addition, although multiple tarsal coalitions have been reported to be quite rare, this study confirmed that they are not rare and can occur in a range of patterns.
The Journal of the Korean bone and joint tumor society
/
v.6
no.1
/
pp.10-16
/
2000
Object : The aim of the current study is to assess the results of segmental resection and replantation for primary malignant or aggressive tumors of the upper limb. Materials and Methods : From 1986 to 1994, ten patients who had primary malignant or aggressive tumors of the upper limb were managed with segmental resection and replantation method. The average duration of follow-up was 7 years and 7 months. Primary indication of this method is stage II B tumors which, because of their extend, could otherwise be adequately treated only by amputation. Three patients had chondrosarcoma, two had osteosarcoma, two had giant cell tumors with pathologic fracture, one had extensive chondroblastoma, one had Ewings sarcoma, and one had leiomyosarcoma. The location of the tumor was humerus in 6 patients, scapula in 3 patients, and soft tissue of forearm in 1 patient. Wide resection margins were achieved in 7 patients and marginal margin in three. Results : One patient died on 40 months after surgery due to systemic metastasis. Nine patients have remained disease free without local recurrence or metastasis. The average overall functional rating was 65% (43~90%) for ten patients on the last follow-up by the functional rating system of Enneking. The mean grasping power and pinching power of operative hand was 75%(28~95%) and 65%(43~90%) of the opposite hand, respectively. Complications associated with this surgical method included three wound dehiscences and one nerve injury that resolved with proper wound care and time. Conclusion : It was concluded that segmental resection and replantation might be used for partial limb salvage in selected cases for the treatment of primary malignant or aggressive tumors of the upper limb.
본 웹사이트에 게시된 이메일 주소가 전자우편 수집 프로그램이나
그 밖의 기술적 장치를 이용하여 무단으로 수집되는 것을 거부하며,
이를 위반시 정보통신망법에 의해 형사 처벌됨을 유념하시기 바랍니다.
[게시일 2004년 10월 1일]
이용약관
제 1 장 총칙
제 1 조 (목적)
이 이용약관은 KoreaScience 홈페이지(이하 “당 사이트”)에서 제공하는 인터넷 서비스(이하 '서비스')의 가입조건 및 이용에 관한 제반 사항과 기타 필요한 사항을 구체적으로 규정함을 목적으로 합니다.
제 2 조 (용어의 정의)
① "이용자"라 함은 당 사이트에 접속하여 이 약관에 따라 당 사이트가 제공하는 서비스를 받는 회원 및 비회원을
말합니다.
② "회원"이라 함은 서비스를 이용하기 위하여 당 사이트에 개인정보를 제공하여 아이디(ID)와 비밀번호를 부여
받은 자를 말합니다.
③ "회원 아이디(ID)"라 함은 회원의 식별 및 서비스 이용을 위하여 자신이 선정한 문자 및 숫자의 조합을
말합니다.
④ "비밀번호(패스워드)"라 함은 회원이 자신의 비밀보호를 위하여 선정한 문자 및 숫자의 조합을 말합니다.
제 3 조 (이용약관의 효력 및 변경)
① 이 약관은 당 사이트에 게시하거나 기타의 방법으로 회원에게 공지함으로써 효력이 발생합니다.
② 당 사이트는 이 약관을 개정할 경우에 적용일자 및 개정사유를 명시하여 현행 약관과 함께 당 사이트의
초기화면에 그 적용일자 7일 이전부터 적용일자 전일까지 공지합니다. 다만, 회원에게 불리하게 약관내용을
변경하는 경우에는 최소한 30일 이상의 사전 유예기간을 두고 공지합니다. 이 경우 당 사이트는 개정 전
내용과 개정 후 내용을 명확하게 비교하여 이용자가 알기 쉽도록 표시합니다.
제 4 조(약관 외 준칙)
① 이 약관은 당 사이트가 제공하는 서비스에 관한 이용안내와 함께 적용됩니다.
② 이 약관에 명시되지 아니한 사항은 관계법령의 규정이 적용됩니다.
제 2 장 이용계약의 체결
제 5 조 (이용계약의 성립 등)
① 이용계약은 이용고객이 당 사이트가 정한 약관에 「동의합니다」를 선택하고, 당 사이트가 정한
온라인신청양식을 작성하여 서비스 이용을 신청한 후, 당 사이트가 이를 승낙함으로써 성립합니다.
② 제1항의 승낙은 당 사이트가 제공하는 과학기술정보검색, 맞춤정보, 서지정보 등 다른 서비스의 이용승낙을
포함합니다.
제 6 조 (회원가입)
서비스를 이용하고자 하는 고객은 당 사이트에서 정한 회원가입양식에 개인정보를 기재하여 가입을 하여야 합니다.
제 7 조 (개인정보의 보호 및 사용)
당 사이트는 관계법령이 정하는 바에 따라 회원 등록정보를 포함한 회원의 개인정보를 보호하기 위해 노력합니다. 회원 개인정보의 보호 및 사용에 대해서는 관련법령 및 당 사이트의 개인정보 보호정책이 적용됩니다.
제 8 조 (이용 신청의 승낙과 제한)
① 당 사이트는 제6조의 규정에 의한 이용신청고객에 대하여 서비스 이용을 승낙합니다.
② 당 사이트는 아래사항에 해당하는 경우에 대해서 승낙하지 아니 합니다.
- 이용계약 신청서의 내용을 허위로 기재한 경우
- 기타 규정한 제반사항을 위반하며 신청하는 경우
제 9 조 (회원 ID 부여 및 변경 등)
① 당 사이트는 이용고객에 대하여 약관에 정하는 바에 따라 자신이 선정한 회원 ID를 부여합니다.
② 회원 ID는 원칙적으로 변경이 불가하며 부득이한 사유로 인하여 변경 하고자 하는 경우에는 해당 ID를
해지하고 재가입해야 합니다.
③ 기타 회원 개인정보 관리 및 변경 등에 관한 사항은 서비스별 안내에 정하는 바에 의합니다.
제 3 장 계약 당사자의 의무
제 10 조 (KISTI의 의무)
① 당 사이트는 이용고객이 희망한 서비스 제공 개시일에 특별한 사정이 없는 한 서비스를 이용할 수 있도록
하여야 합니다.
② 당 사이트는 개인정보 보호를 위해 보안시스템을 구축하며 개인정보 보호정책을 공시하고 준수합니다.
③ 당 사이트는 회원으로부터 제기되는 의견이나 불만이 정당하다고 객관적으로 인정될 경우에는 적절한 절차를
거쳐 즉시 처리하여야 합니다. 다만, 즉시 처리가 곤란한 경우는 회원에게 그 사유와 처리일정을 통보하여야
합니다.
제 11 조 (회원의 의무)
① 이용자는 회원가입 신청 또는 회원정보 변경 시 실명으로 모든 사항을 사실에 근거하여 작성하여야 하며,
허위 또는 타인의 정보를 등록할 경우 일체의 권리를 주장할 수 없습니다.
② 당 사이트가 관계법령 및 개인정보 보호정책에 의거하여 그 책임을 지는 경우를 제외하고 회원에게 부여된
ID의 비밀번호 관리소홀, 부정사용에 의하여 발생하는 모든 결과에 대한 책임은 회원에게 있습니다.
③ 회원은 당 사이트 및 제 3자의 지적 재산권을 침해해서는 안 됩니다.
제 4 장 서비스의 이용
제 12 조 (서비스 이용 시간)
① 서비스 이용은 당 사이트의 업무상 또는 기술상 특별한 지장이 없는 한 연중무휴, 1일 24시간 운영을
원칙으로 합니다. 단, 당 사이트는 시스템 정기점검, 증설 및 교체를 위해 당 사이트가 정한 날이나 시간에
서비스를 일시 중단할 수 있으며, 예정되어 있는 작업으로 인한 서비스 일시중단은 당 사이트 홈페이지를
통해 사전에 공지합니다.
② 당 사이트는 서비스를 특정범위로 분할하여 각 범위별로 이용가능시간을 별도로 지정할 수 있습니다. 다만
이 경우 그 내용을 공지합니다.
제 13 조 (홈페이지 저작권)
① NDSL에서 제공하는 모든 저작물의 저작권은 원저작자에게 있으며, KISTI는 복제/배포/전송권을 확보하고
있습니다.
② NDSL에서 제공하는 콘텐츠를 상업적 및 기타 영리목적으로 복제/배포/전송할 경우 사전에 KISTI의 허락을
받아야 합니다.
③ NDSL에서 제공하는 콘텐츠를 보도, 비평, 교육, 연구 등을 위하여 정당한 범위 안에서 공정한 관행에
합치되게 인용할 수 있습니다.
④ NDSL에서 제공하는 콘텐츠를 무단 복제, 전송, 배포 기타 저작권법에 위반되는 방법으로 이용할 경우
저작권법 제136조에 따라 5년 이하의 징역 또는 5천만 원 이하의 벌금에 처해질 수 있습니다.
제 14 조 (유료서비스)
① 당 사이트 및 협력기관이 정한 유료서비스(원문복사 등)는 별도로 정해진 바에 따르며, 변경사항은 시행 전에
당 사이트 홈페이지를 통하여 회원에게 공지합니다.
② 유료서비스를 이용하려는 회원은 정해진 요금체계에 따라 요금을 납부해야 합니다.
제 5 장 계약 해지 및 이용 제한
제 15 조 (계약 해지)
회원이 이용계약을 해지하고자 하는 때에는 [가입해지] 메뉴를 이용해 직접 해지해야 합니다.
제 16 조 (서비스 이용제한)
① 당 사이트는 회원이 서비스 이용내용에 있어서 본 약관 제 11조 내용을 위반하거나, 다음 각 호에 해당하는
경우 서비스 이용을 제한할 수 있습니다.
- 2년 이상 서비스를 이용한 적이 없는 경우
- 기타 정상적인 서비스 운영에 방해가 될 경우
② 상기 이용제한 규정에 따라 서비스를 이용하는 회원에게 서비스 이용에 대하여 별도 공지 없이 서비스 이용의
일시정지, 이용계약 해지 할 수 있습니다.
제 17 조 (전자우편주소 수집 금지)
회원은 전자우편주소 추출기 등을 이용하여 전자우편주소를 수집 또는 제3자에게 제공할 수 없습니다.
제 6 장 손해배상 및 기타사항
제 18 조 (손해배상)
당 사이트는 무료로 제공되는 서비스와 관련하여 회원에게 어떠한 손해가 발생하더라도 당 사이트가 고의 또는 과실로 인한 손해발생을 제외하고는 이에 대하여 책임을 부담하지 아니합니다.
제 19 조 (관할 법원)
서비스 이용으로 발생한 분쟁에 대해 소송이 제기되는 경우 민사 소송법상의 관할 법원에 제기합니다.
[부 칙]
1. (시행일) 이 약관은 2016년 9월 5일부터 적용되며, 종전 약관은 본 약관으로 대체되며, 개정된 약관의 적용일 이전 가입자도 개정된 약관의 적용을 받습니다.