로프각도와 강판두께를 고려한 패드아이 용접부 강도설계에 관한 연구

정호승,김정렬,Jeong, Ho-Seung,Kim, Jung-Ryul 한국마린엔지니어링학회 2007 한국마린엔지니어링학회지 Vol.31 No.4

Pad-eye is connected to crane with sling. When block is lift, pad-eye have a various applied force. Applied force on pad-eye is related to sling angle. Sling angle is decided by various parameters, including pad-eye location, sling length and crane location. Welded joint on pad-eye requires strength design because sling angle changes force on pad-eye. Strength design for welded joint of pad-eye will calculate with general mechanical design and FE analysis. FE analysis would become a useful tool in the analysis of welded joint. A commercial software(ANSYS 10.0) was used in the structural strength analysis for welded joint of pad-eye.

유한요소법을 이용한 극저온 미니어쳐 글로브 밸브의 구조설계에 관한 연구

정호승(Ho-Seung Jeong),김영환(Young-Hwan Kim),조종래(Jong-Rae Cho),김정환(Jeong-Hwan Kim),김정렬(Jung-Ryul Kim),박재현(Jae-Hyoun Park) 한국마린엔지니어링학회 2007 한국마린엔지니어링학회지 Vol.31 No.4

열점소성 유한요소법을 이용한 대형 배기밸브 스핀들 마찰용접 공정개발

정호승(Ho-Seung Jeong),박희천(Hee-Cheon Park),오중석(Jung-Seok Oh),한명섭(Myoung-Seoup Han),조종래(Jong-Rae Cho) 한국마린엔지니어링학회 2006 한국마린엔지니어링학회 학술대회 논문집 Vol.2006 No.-

Inertia welding is a solid-state welding process in which butt welds in materials are made in bar and in ring form at the joint face, and energy required for welding is obtained from a rotating flywheel. The stored energy is converted to frictional heat at the interface under axial load. The quality of the welded joint depends on many parameters, including axial force, initial revolution speed and energy, amount of upset, working time, and residual stresses in the joint. Inertia welding was conducted to make the large exhaust valve spindle for low speed marine diesel engine, superalloy Nimonic 80A for valve head of 540㎜ and high alloy SNCrW for valve stem of 115㎜. Due to different material characteristics, such as, thermal conductivity and flow stress, on the two sides of the weld interface, modeling is crucial in determining the optimal weld geometry and parameters. FE simulation was performed by the commercial code DEFORM-2D. A good agreement between the predicted and actual welded shape is observed. It is expected that modeling will significantly reduce the number of experimental trials needed to determine the weld parameters, especially for welds for which are very expensive materials or large shaft.

이종재료 마찰용접에 의한 초내열합금 대형 배기밸브 스핀들 개발

박희천,정호승,조종래,이낙규,오중석,한명섭,Park Hee-Cheon,Jeong Ho-Seung,Cho Jong-Rac,Lee Nak-Kyu,Oh Jung-Seok,Han Mvoung-Seoup 한국마린엔지니어링학회 2005 한국마린엔지니어링학회지 Vol.29 No.8

Inertia welding is a solid-state welding process in which butt welds in materials are made in bar and in ring form at the joint race, and energy required lot welding is obtained from a rotating flywheel. The stored energy is converted to frictional heat at the interface under axial load. The quality of the welded joint depends on many parameters, including axial force, initial revolution speed and energy amount of upset. working time, and residual stresses in the joint. Inertia welding was conducted to make the large exhaust valve spindle for low speed marine diesel engine. superalloy Nimonic 80A for valve head of 540mm and high alloy SNCrW for valve stem of 115mm. Due to different material characteristics such as, thermal conductivity and flow stress. on the two sides of the weld interface, modeling is crucial in determining the optimal weld geometry and Parameters. FE simulation was performed by the commercial code DEFORM-2D. A good agreement between the Predicted and actual welded shape is observed. It is expected that modeling will significantly reduce the number of experimental trials needed to determine the weld parameters. especially for welds for which are very expensive materials or large shaft. Many kinds of tests, including macro and microstructure observation, chemical composition tensile , hardness and fatigue test , are conducted to evaluate the qualify of welded joints. Based on the results of the tests it can be concluded that the inertia welding joints of the superalloy exhaust valve spindle are better properties than the material specification of SNCrW.

마찰 용접을 이용한 선박용 2 행정 기관용 배기밸브 스핀들의 개발 및 적용

오중석(Jung-Seok Oh),한명섭(Myoung-Seoup Han),박희천(Hee-Cheon Park),정호승(Ho-Seung Jeong),조종래(Jong-Rae Cho) 한국마린엔지니어링학회 2006 한국마린엔지니어링학회 학술대회 논문집 Vol.2006 No.-

나이모닉 일체형으로 사용되고 있는 선박용 2 행정 저속엔진의 배기밸브 스핀들을 고온, 고압, 배기가스 및 반복 충격 하중에 노출된 스핀들의 Head부분은 기존의 나이모닉 소재를 적용, 기존 재질의 우수한 성질을 유지하고 설계적으로 나이모닉 소재의 적용이 불필요한 Stem부는 오스텐나이트 계열의 SNCrW 소재를 사용하여 관성마찰 용접 방식으로 접합하여 제품을 제작하고, 접합부의 미세조직 관찰, 성분분석, 인장, 경도, 피로시험 등의 기계적, 금속적 특성평가를 통해 마찰용접제품에 대한 신뢰성을 확인하고 양산 생산을 위한 기술적 토대를 마련하였다.

대구경 비구면 렌즈의 설계 및 가공기술의 개발

곽민석(Min-Seok Kwak),박재현(Jae-Hyoun Park),정호승(Ho-Seung Jeong),김정렬(Jung-Ryul Kim),김동균(Dong-Kyun Kim),한종석(Jong-Suk Han) 한국마린엔지니어링학회 2006 한국마린엔지니어링학회 학술대회 논문집 Vol.2006 No.-

This study is described the modeling of aspheric lens, manufacturing and inspection. The aspheric lens is different from a convex lens and concave lens in that is useful to aspherical, but modeling method of this isn't open to the public. Therefore, This study is designed to the aspheric lens of geometric form, manufactured a sample by CAM, which is applied to Euler method. So, we have verified modeling and CAM process for aspheric lens through a experiment.

Modified Phemister술식을 이용한 견봉쇄골관절 탈구의 치료

윤형구(Hyung-Ku Yoon),전광표(Kwang-Pyo Jeon),정대은(Dae-Eun Jung),정호승(Ho-Seung Jeon),박순용(Soon-Young Park) 대한정형외과학회 1995 대한정형외과학회지 Vol.30 No.2

감염성 슬관절염의 관절경적 치료 이후 예후 인자에 대한 분석

강상우(Sang-Woo Kang),최의성(Eui-Sung Choi),김동수(Dong-Soo Kim),정호승(Ho-Seung Jung),홍석현(Seok-Hyun Hong),고반석(Ban-Suk Go) 대한정형외과학회 2019 대한정형외과학회지 Vol.54 No.1

목적: 관절경적 수술을 시행받은 감염성 슬관절염 환자들에서 성별, 나이, 기저질환, 증상 발생 후 수술까지 걸린 기간, 발병 전 침습적 시술의 시행 여부, 관절 천자액의 세균 배양, Gächter 분류를 통한 세균 감염의 정도가 치료 예후에 미치는 영향에 대해 알아보고자 한다. 대상 및 방법: 2014년 6월부터 2016년 12월까지 감염성 슬관절염으로 관절경적 수술을 시행받은 51명의 환자를 대상으로 하였으며, 평균 추시 기간은 14.2±2.1개월(12-20개월)이었다. 남자가 27명(52.9%), 여자가 24명(47.1%)이며, 평균 나이는 55.1±17.6세(13-84세)였다. 수술 전 시행한 관절 천자검사상 백혈구 수가 50,000개 이상, 다형핵 백혈구 수의 비율이 95% 이상인 환자를 감염성 슬관절염으로 진단하고 수술을 시행하였다. 모든 환자에서 관절경적 수술과 수술 후 지속적인 관절 세척을 시행하였다. 결과: C-반응 단백의 초기 평균 수치는 9.55±6.76 mg/dl (1.51-31.06 mg/dl)에서 최종 평균 수치는 0.74±1.26 mg/dl (0.08-6.77 mg/dl)로 감소하였으며, 평균 C-반응 단백의 정상화 기간은 27.6±18.9일(8-93일)이었다. 관절경적 수술과 항생제 사용 후 발열, 동통, 부종 등의 임상증상이 호전되고 C-반응 단백의 수치가 0.5 mg/dl 이하로 감소하여 감염성 슬관절염의 완치 판정을 받은 환자는 51예 중 44예(86.3%)이며, 최종적으로 두 번 이상의 관절경적 수술을 시행한 환자가 5예, prosthesis of antibiotic-loaded acrylic cement 후 인공관절 치환술로 전환한 환자가 2예이다. 결론: 지금까지 문헌들에서 알려진 것처럼 증상 발생 후 수술까지 걸린 기간과 Gächter 분류에 따른 병기는 감염성 슬관절염의 치료 성공 여부에 유의하게 영향을 주었다. 하지만 이외의 인자들은 통계적으로 유의한 상관관계가 없었다. 단 관절 천자액에서 세균이 배양된 환자군은 대조군보다 유의하게 C-반응 단백의 정상화 기간이 짧아 치료 기간을 반영하는 것으로 보인다. Purpose: This study examined the effects of gender, age, underlying disease, duration after onset of symptoms, preoperative invasive procedures, bacterial culture of joint fluid, and stage of infection by the Gächter classification on the prognosis of patients with infectious knee arthritis who underwent arthroscopic surgery. Materials and Methods: From June 2014 to December 2016, 51 patients who underwent arthroscopic surgery for infective knee arthritis were enrolled in this study. The average follow-up period was 14.2±2.1 months (range, 12-20 months). The subjects were 27 men (52.9%) and 24 women (47.1%), with an average age of 55.1±17.6 years (range, 13-84 years). A preoperative evaluation of the joint aspiration with a count of more than 50,000 leukocytes and a polymorphonuclear leukocyte count of 95% or more was performed. All patients underwent arthroscopic surgery and postoperative continuous joint irrigation. Results: The initial mean value of the C-reactive protein decreased from 9.55±6.76 mg/dl (range, 1.51-31.06 mg/dl) to a final mean of 0.74±1.26 mg/dl (range, 0.08-6.77 mg/dl); the mean duration of C-reactive protein normalization was 27.6±18.9 days (range, 8-93 days). Among the 51 patients who received arthroscopic surgery and antibiotics, 44 patients (86.3%) with infectious knee arthritis completed treatment with improved clinical symptoms, such as fever, pain, and edema, and the C-reactive protein decreased to less than 0.5 mg/dl. Finally, 5 cases were treated with two or more arthroscopic operations, and 2 cases were converted to arthroplasty after prosthesis of antibiotic-loaded acrylic cement. Conclusion: The duration of surgery after the onset of symptoms and the stage according to the Gächter classification are important prognostic factors for predicting the successful treatment of infectious knee arthritis. On the other hand, the other factors were not statistically significant. Nevertheless, patients with bacteria cultured from the joint fluids appear to reflect the treatment period because the period of normalization of the C-reactive protein is shorter than that of the control group.

전방 경추 유합술 후 Polyetheretherketone (PEEK) 케이지의 침강

김용민(Yong Min Kim),오규원(Kyu Won Oh),김동수(Dong Soo Kim),최의성(Eui Sung Choi),손현철(Hyun Chul Shon),박경진(Kyung Jin Park),조병기(Byung Ki Cho),박지강(Ji Kang Park),정호승(Ho Seung Jeong),오정욱(Jung Wook Oh) 대한정형외과학회 2014 대한정형외과학회지 Vol.49 No.3

목적: 전방 감압술 및 polyetheretherketone (PEEK) 케이지를 이용한 유합술 시행 후 침강의 발생률 및 방향을 평가하고, 침강의 유발 요인을 분석하고자 하였다. 대상 및 방법: 2003년 7월부터 2011년 11월까지 전방 감압술 및 PEEK 케이지를 이용한 전방 유합술을 시행받은 32명(36분절)을 대상으로 하였다. 전방분절높이, 후방분절높이와 케이지 모서리 거리를 단순 방사선 사진에서 측정하였다. 2 mm 이상 감소를 침강으로 정의하였으며 3 mm 이상을 중등도 침강으로 구분하여 통계적 분석을 시행하였다. 결과: 14개의 분절(38.9%)에서 침강이 발생하였으며 중등도 침강은 7개 분절(19.4%)에서 발생하였다. 전, 후방분절높이를 이용하여 전방과 후방의 침강을 비교하였으며 전방에서의 침강이 후방에서보다 많이 발생하였다(p<0.001). 전, 후방에서 모두 하방으로 침강이 많이 발생하였다(p<0.001, p=0.047). 침강의 위험 요소로는 추간판 간격의 신연 및 삽입된 케이지의 높이가 통계적으로 유의하였다(p<0.05). 결론: 케이지 사용 후 침강이 높은 비율로 발생하였으며, 수술 중 추간판 간격의 과도한 신연을 방지하고 적절한 높이의 케이지를 사용하는 것이 침강 예방에 도움이 될 것으로 생각된다. Purpose: The purpose of this study is to evaluate the rate and direction of subsidence that occurred after anterior cervical discectomy and fusion using the polyetheretherketone (PEEK) cage and to analyze the risk factors of subsidence. Materials and Methods: Thirty two patients (36 segments) who underwent anterior cervical discectomy and fusion using the PEEK cage and autologous cancellous iliac bone graft from July 2003 to November 2011 were enrolled in this study. anterior segmental height (ASH), posterior segmental height (PSH) and cage corner distance (CCD) were measured on plain radiographs. Subsidence was defined as ≥2 mm decrease in the average of ASH and PSH at the final follow up compared to that measured in the immediate postoperative period. A decrease of more than 3 mm was defined as severe subsidence for further statistical analysis. Results: Subsidence of more than 2 mm was observed in 14 segments (38.9%) and severe subsidence (≥3 mm) was observed in seven segments (19.4%). The direction of subsidence was examined by comparison of means of decreased ASH and PSH and anterior subsidence outweighed posterior subsidence (p<0.001). Examination of CCD showed that inferior subsidence was more frequent than superior subsidence (p<0.001, p=0.047). Among the suspicious risk factors for subsidence, intraoperative disc space distraction (anterior distraction: p=0.031, posterior distraction: p=0.007) and height of inserted cage (p=0.032) showed statistical significance. Conclusion: Considerable incidence of subsidence was observed after use of the cage. Using a cage of appropriate height and prevention of intraoperative over-distraction of disc space will be helpful to prevention of subsidence of the cage after anterior cervical discectomy and fusion using the PEEK cage.