선반 기어박스의 기어열 - 축계 진동 해석 및 저감에 관한 연구

최영휴,박선균,배병태,정택수,김청수 한국공작기계학회 2001 한국공작기계학회 춘계학술대회논문집 Vol.2001 No.-

In this study, torsional and lateral vibrations of a gear box transmission system were analyzed theoretically using some mathematical models and examined to determine the causes of its excessive vibrations. As the results, it was found there exist possibility of resonance between gear mesh frequencies and lateral vibration mode of the transmission shaft during the third shifting mode operation. In order to avoid this resonance, we proposed changing the arrangement of gears on the transmission shaft. The measured vibration levels of the improved gear box were dramatically reduced. These results may be helpful to design a machine tool gear box with low noise and vibration.

NC선반 기어박스의 기어열 : 축계 진동해석 Spindle System for an NC Lathe Gear Box

최영휴,박선균,배병태,정택수,김청수 한국공작기계학회 2000 한국공작기계학회 추계학술대회논문집 Vol.2000 No.-

In this study, two mathematical models are first constructed to analyze vibration characteristics of a gear train - spindle system of an NC lathe gear box. One is a lumped parameter model which is used for calculating natural frequencies of the torsional vibration, the other is a finite element model for analyzing lateral vibration and critical speeds of the spindle system. In addition, this study examines some possible resonance conditions such as gear mesh frequencies, IX shaft rpm frequencies over whole operating speed range, and so on. The results may be helpful to design a machine tool gear box with low noise and vibration.

國民學校 敎師 自然 및 算數科 再敎育의 分析的 硏究 : Based on the Choong Buk Province

黃秉德,梁仁煥,崔炳文,趙璇衡,朴根生 淸州大學校 科學敎育硏究所 1977 淸州大學校 科學敎育硏究所 Vol.1 No.-

Our college has retrained many primary school teachers during 5 years is science, and during 4 years in case of mathematics. Many problems are found out in the process of retraining them in our school. This study is aimed to research the actual condition of the retraining and to find out the way to improvement from the problems. However, Our study will have some limitation as follows: (1) For our study, only 300 teachers are chosen from the total 1,869 attended at our college(Cheong Ju Teachers College) in 1976. (2) The administrational and financial affairs are analyzed only according to the Ministry of Education with UNICEF funds from 1972 to 1976, and (3) We didn't take any consideration of Ministry of Education Project in Suggesting the way of improvement. Following are some problems found in our study: 1) Throughout the nation, only 23% of primary school teachers were taught in science and mathematice reservice work during the 5 years, and it can be said that it takes about 20 years to retrained all the teachers without consideration of natural increase of teachers. 2) The proportion of selecting primary school teachers in all the country for this reservice training is extreme, for example, Jeju Province is 57.9%, Seoul 17.7%. 3) The proportion of woman teachers selected in Choong Buk primary school is only 3.5% of total woman teachers, who takes 32% of total Choong Buk primary teachers during 5 years. Therefore, it is said that the number is very little. 4) Some teachers have been reselected in the reservice training. In case of the Choong Buk Board of Education. the 6% of teachers selected once were reselected for 5 years. 5) When the test are enforced on attendants to get data before the reservice training. We could find that they didn't understand the basic concept of science except a grade under their charge. 6) In the process of inquiry study, they didn't know even the scientific terms of expectation and reasoning. 7) After 60 hours of reservice training course. We tested them about understanding of the contents of text, and their marks are from 10 to 100. the marks show large individual difference among them. 8) Some teachers may have neither teaching ability nor knowledge of the basic concept, that is 11.3% of total attendants are less than 30 marks in mathematics test. 9) It is too very large work to study reservice text during the 60 hours. 10) There are many difficult signs in the mathematics reservice text having no connection with the actual primary school mathematics text book. 11) In the reservice text of science, there are omitted the method of teaching materials production, the model of inquiry learning, and the evaluation method. 12) From the analysis of questionary response for finding the actual condition of administration of teaching materials, We could find out 15% of primary schools in Choong Buk Province do almost not prepare teaching materials, and 15% of its never put them to practical use. Therefore, We could say that total 30% of them have been teaching without teaching materials. 13) The 42% of attendants in mathematics class answer that they do not understand the new mathematical signs, and 42% of them answer the shortage of hours (60 hours) to understand their reservice text book. 14) The 25% of them answer that they teach children with cramming education, and almost of them want good teachers guide books. As mentioned above, there are found many problems to be solved for reservice training of science education in our country. Some of them will be solved in our study. So We find out its and We suggest the ways solving the problems as follows: A. On the administration of reservice training. 1) The reservice training work for primary school teachers is very significant and will have to be continued. 2) It will be done in not only summer vacation but also winter one for finishing immediatly all over the country. 3) The 60 hours of science reservice training course work are very short, and the classmember of attendants will be regulated. 4) The funds for reservice operation and travelling expenses for attendants will be realized. B. On selecting the attendants 1) When the attendants are selected, there will be consideration of age, rank, term of their service, sex and academic background. 2) as far as possible, it will be selected as homogeous groups, and it will be effective to teach them with division between class teacher and nonclass teacher. 3) When select attendants are it will be taken consideration of balance between city and province for the diffusion effect and parallel development in reservice training work. 4) It must give a chance to woman as same as to man teacher according to a rule of equal select chance. 5) The principal, instructor and school inspector will be reeducated for fixing of science curriculum. C. On reservice training text book 1) The text book must reedit moderatly for 60 hours, or the time of retraining for the text book finished will be extented. In our opinion, it is to be desired that the time have to be added. 2) The difficult signs must be omitted, taking into account for the mathematics knowledge and time of education period. 3) In the science reservice training text book, it must supplement the tack for framming of inquiry teaching plan, the method for making teaching materials, and the skill for replacing of teaching materials. D. For the curriculum management of science. 1) The Governmental Company must settle the shortage of science teaching materials in primary school. 2) For the charge of the old state of teaching method, the teachers must devote themselves to teach children without miscellaneous duties. 3) The authorities concerned (for example, Ministry of Education, Teachers College, etc.) must make guide books for science teachers, and supply them to primary school teachers. 4) It must be given the chance of long period reeducation to the incompetent primary school teachers, and problem will have to be studied under the situation of educational administration.

골다공증성 대퇴골 골절의 위험인자 평가

정선관,박성훈,김혜원,이영환,윤권하,최시성,노병석,원종진 圓光大學校 醫科學硏究所 2007 圓光醫科學 Vol.22 No.1

치면열구전색제의 열구 침투에 primer의 효과

정혜선,최병재,최형준,이제호 大韓小兒齒科學會 1999 大韓小兒齒科學會誌 Vol.26 No.2

본 연구의 목적은 치면열구전색제 수복시에 상아질 접착제의 primer 도포의 치면열구전색제 열구 침투도 향상 효과를 확인하는 것으로 발거된 영구 구치상에서 통상적으로 치면열구 전색제를 도포한 대조군과 Scotchbond™ Multi-Purpose system과 ?? 2 system의 primer 도포 후에 치면열구전색제를 도포한 실험군들의 열구 기저부까지 전색제 침투 성공률을 비교하여 다음과 같은 결론을 얻었다. 1. Scotchbond™ Multi-Purpose system과 All-Bond 2 system의 primer를 사용한 군의 열구 기저부까지 치면열구전색제 침투 성공률은 primer를 사용하지 않은 대조군보다 높았으나 통계학적으로 유의성 있는 차이는 없었다(p>0.05) 2. 열구 깊이와 폭 및 '깊이/폭' 값은 열구 기저부까지 전색제 침투성공율에 대하여 통계학적으로 유의성 있는 효과를 나타내었다.(p<0.05) 3. 열구 기저부까지 전색제 침투 성공률은 열구 깊이가 25㎛ 증가할 때마다 약 0.9배로 감소하였고, 열구 입구의 폭이 25㎛ 증가할 때마다 약 1.1배로 증가하였으며, 열구의 '깊이/폭' 비율이 1 증가할 때마다 약 0.6배로 감소하였다. The objective of this study is to confirm the effect of dentine bonding primer application on penetration of sealant. Extracted permanent molars were used to compare penetration success rate of control group (sealant application only) and experimental groups (sealant application after applying the primers of Scotchbond™ Multi-Purpose system and All-Bond 2 system). The following results were obtained: 1. The experimental groups using the primers showed increased sealant penetration success rate to the base of fissure when compared to control group but there was no statistically significant differences(p>0.05). 2. The depth, width and 'depth/width' value of fissure had statistically significant effect on sealant penetration success rate(p<0.05). 3. The penetration success rate decreased about 0.9 times as the depth of fissure increased every 25㎛, and increased about 1.1 times as the width of the fissure orifice increased every 25㎛, and decreased about 0.6 times as the 'depth/width' value increased every 1. From the above results, it can be concluded that fissure morphology had a great effect on sealant penetration and for better penetration, use of dentine bonding primer can be helpful but it needs more study in clinical bases.

의도적 유치발치술에 의한 이소매복 영구치의 맹출유도

최인영,김승혜,김성오,최형준,이제호,최병재,손흥규,송제선 大韓小兒齒科學會 2011 大韓小兒齒科學會誌 Vol.38 No.4

맹출에 관계되는 여러 요소가 부정적으로 작용할 때 맹출장애가 유발될 수 있다. 맹출장애의 일종인 매복이 발생할 경우 주 기적인 관찰, 공간확보, 외과적노출, 교정적견인, 외과적노출과 교정적견인의 병행, 발거 후 자가치아이식 등의 방법을 고려 할 수 있다. 첫 번째 증례는 9세 남환에서 상악 좌측 측절치의 수평매복을 발견하여 상악 좌측 유측절치 및 유견치를 발거 후 5개월 뒤 개창술(window opening)을 시행한 증례로, 8개월의 정기검진시 치아가 부분맹출 하였으며 18개월 후 매복된 상악 좌측 측 절치가 치축이 개선되며 자발적으로 맹출하였다. 두 번째 증례는 10세 남환에서 상악 우측 제1소구치의 이소매복을 발견하여 상악 우측 제 1 유구치를 발거한 증례로, 10개월 뒤 치아가 부분맹출하였으며 19개월 후 매복된 상악 우측 제1소구치가 자발 적으로 맹출하였다. 본 증례들에서 이소매복된 영구치는 맹출경로에 있는 유치의 의도적 발거 후 경과관찰을 한 결과 맹출 위치의 개선 및 자발 적 맹출이 유도되었기에 보고하는 바이다. When many factors involved in the eruption of the teeth act as negative effects, they can cause eruption disturbance. Periodic observation, space acquirement, surgical exposure, orthodontic traction, orthodontic traction accompanied with surgical exposure, and surgical repositioning are considered as the treatment options of an impacted tooth, which is a form of eruption disturbance. In the first case, a male patient, age 9, visited Yonsei University Dental Hospital (YUDH) with a chief complaint of ectopic impaction of the upper left lateral incisor. We extracted the upper left primary lateral incisor and primary canine, and 5 months later, a window opening procedure was executed. Eight months later, the upper left lateral incisor partially erupted, and 18 months after the extraction, the axis of the tooth improved and the tooth erupted spontaneously. In the second case, a male patient, age 10, visited YUDH with a chief complaint of ectopic impaction of the upper right first premolar. We extracted the upper right first primary molar. Ten months later, the upper right first premolar erupted partially, and 19 months after the extraction, the upper right first premolar erupted spontaneously. We reported two cases in which improvement of eruption path and spontaneous eruption of an ectopic impacted tooth was achieved by extracting the deciduous tooth which interfered with the proper eruption of it.

역위 매복된 상악 중절치의 외과적 재위치 후 치근 발육 정지

송제선,최병재,최형준,김성오,손흥규,이제호 대한소아치과학회 2007 大韓小兒齒科學會誌 Vol.34 No.1

상악 중절치의 매복은 소아 환자의 심미적 사회적 기능적 문제를 일으킬 수 있어 적절한 치료를 통해 바로잡아 주어야 한다. 상악 중절치 매복의 치료로 외과적 노출 후 교정적 견인이 어려울 경우 발치하기에 앞서 외과적 재위치(surgical repositioning) 혹은 치조 내 자가치아이식(intra-alveolar autotransplantation)을 고려해 볼 수 있다. 본 증례는 5세 9개월 된 남아의 역위 매복된 상악 우측 중절치를 치근 발육 초기인 Nolla's stage 6.5에 부분 맹출된 위치로 외과적 재위치를 시행하여 자발적 맹출을 기대하였으나 21개월 간의 추적 검사 결과 치관 발육 및 맹출이 정지된 증례이다. 그 원인으로서 수술 시 치배를 발거하고 치조와를 적합하는 과정에서 Hertwig's epithelial root sheath(HERS)가 손상 받았기 때문으로 생각된다. 매복 치아의 외과적 재위치 시에는 본 증례와 같이 합병증 발생 가능성이 있으므로 신중한 적응증의 선택, 치근 발달 정도를 고려한 적절한 치료 시기의 결정, 최소한의 손상을 주는 외과적 술식 등의 노력이 필요할 것이다. Impaction of the maxillary central incisor may cause social, esthetic, and functional problems in children. There are various means of treatment for the inverted maxillary central incisor, such as extraction, surgical opening followed by orthodontic traction, surgical repositioning or intra-alveolar autotransplantation prior to extraction. In this case, we surgically repositioned the inverted maxillary central incisor to normal semi-erupted position in a 5-year-old boy. The developmental stage of the inverted tooth was Nolla’ s 6.5, which indicates formation of less than one third of the root. After surgical reposition, we did follow-up for 21 months, expecting spontaneous growth. Unfortunately, poor prognosis was noted : further root was not observed. Such failure seems to originate from possible injury on Hertwig’ s epithelial root sheath by surgical trauma. We performed surgical repositioning to retain the tooth instead of extraction. However, arrest of root development occurred, which is one of the critical complications. In order to increase the success rate of the surgical reposition procedure, minimal surgical trauma is required as well as selection of adequate indication and decision of proper time of treatment considering the stage of root development.

Cariogram을 이용한 모자간 우식활성도의 상관성 및 우식위험요소 평가

이석우,송제선,최병재,최형준,이제호 大韓小兒齒科學會 2009 大韓小兒齒科學會誌 Vol.36 No.3

영유아기 치아우식증은 복잡하고 다인자적 질환으로 숙주 및 미생물, 식이, 시간 등의 위험요소에 의해 질환이 진행된다. 이 중 미생물로 대변되는 Streptococcus mutans(S. mutans)는 우식 개시에 있어 중요한 역할을 하며, 어머니를 통한 수직 감염이 잘 알려져 있다. 영유아기의 어머니를 통한 조기 감염은 향후 유치열기 우식 발생과 높은 연관성을 나타내므로 우식위험요소에 대한 조기 파악은 미래의 치아우식증 예방에 있어 매우 중요하다. 최근 치아우식증의 원인 및 이에 미치는 요소들에 대한 연구가 활발하게 이루어지면서 우식 진행에 대한 정확한 예측을 위한 여러 가지 우식위험도평가(caries risk assessment) 도구가 개발되었는데, 이 중 대표적인 한 가지가 Cariogram이다. Cariogram은 개인의 우식활성도 및 우식위험요소(caries risk factor)의 상호작용을 그래프로 나타낸다. 이번 연구의 목적은 3~5세의 중증 유아기우식증(Severe Early Childhood Caries; S-ECC)에 해당되는 어린이들과 그들의 어머니 사이에서 우식관련타액검사 및 최근 개발된 Cariogram을 이용하여 S. mutans의 수준 및 우식활성도에 대한 상관관계가 존재함과 우식위험요소 간의 연관성을 파악해 보았는데, 이를 통해 다음과 같은 결론을 얻을 수 있었다. 1. 중증 유아기우식증을 보이는 어린이에서 구강 내 존재하는 Streptococcus mutans의 수준은 비우식군보다 높았다(p<0.05). 2. 모자간 구강 내 존재하는 Streptococcus mutans 수준은 상관관계를 보였다(p<0.05). 3. 모자간 우식활성도를 Cariogram을 통해 측정해 본 결과 상관관계를 보였다(p<0.05). 4. 우식활성도에 미치는 우식위험요소는 어린이에서 숙주요소가 가장 큰 영향을 주는 것으로 나타났다. 이상의 결과로 S. mutans가 향후 치아우식증 발생 가능성을 예측하는데 있어 유용한 우식위험요소가 될 수 있으며, Cariogram을 통한 향후의 우식진행과 관련된 여러 가지 우식위험요소가 예측 가능하므로 이에 대한 조기 대처 및 예방적 처치가 가능하리라 사료된다. Dental caries during infantile and early childhood period is a complex disease resulting from multiple caries factors. Streptococcus mutans(S. mutans) plays a critical role in the initiation of caries, and its early transmission through mothers provides a strong etiologic factor for future development of caries in the primary dentition. Therefore, early detection of caries risk factor is important for prevention of caries. Recent studies about etiologic factors of caries have brought advent of various tools for caries risk assessment in order to predict progress of caries more accurately. Cariogram is a common tool for caries risk assessment, which illustrates present caries risk assessment and correlation of caries risk factors for an individual graphically. The aim of this study was to assess if there is any correlation in the level of S. mutans and caries activity and to verify the effect of caries risk factors between children with age ranging from 3 to 5 years with severe early childhood caries(S-ECC) and their mothers using caries-related salivary test and Cariogram. The results of this study were as follows. 1. Children with S-ECC had a statistically higher level of Streptococcus mutans compared to caries-free children(p<0.05). 2. There was significant correlation between mothers and their children in the aspect of the level of Streptococcus mutans(p<0.05). 3. When caries activity was assessed using Cariogram, significant correlation between mothers and their children was found(p<0.05). 4. When each caries risk factor was evaluated for its affect on caries activity, host was more influential factor compared to microorganism and diet in children. Based on these results, we could conclude that assessing the level of S. mutans can be an effective tool for predicting possibility of caries formation in future. Since prediction of future caries progression and evaluation of caries risk factor became possible with Cariogram, we may conduct early and preventive measures for treatment of caries.

계승영구치가 선천적 결손된 유치의 치근 흡수

이정은,이제호,최형준,김성오,송제선,손흥규,최병재 대한소아치과학회 2009 大韓小兒齒科學會誌 Vol.36 No.4

유치의 정상적인 치근 흡수는 계승 영구치의 맹출 압력으로 단핵구 세포가 방출되어 파골세포로의 분화가 촉진되어 일어나며, 계승 영구치의 맹출 경로를 따라 유치의 치근이 흡수되어서 유치가 탈락하게 된다. 계승 영구치가 선천적으로 결손되었을 때에도 유치의 치근은 흡수될 수 있는데, 유치의 비정상적 치근흡수는 외상이나 염증, 교합압의 증가, 지지조직의 약화 등으로 발생할 수 있다. 치아의 선천적 결손은 인간에서 가장 흔한 발육이상이며, 영구치가 결손되었을 때 유치는 만기 잔존할 수 있다. 영구치의 선천적 결손은 전신질환이 있는 경우뿐만 아니라 국소적 원인이나 인류 진화에 따른 영향 등에 의해서도 발생한다. 이 증례들은 계승 영구치가 선천적으로 결손된 어린이에서 유치의 치근이 비정상적으로 흡수된 경우로 계승 영구치가 결손 된 유전치와 유견치, 유구치의 치근이 1/2 ~ 3/4정도까지 흡수 되었으며 흡수 부위는 불규칙적인 형태를 보였다. 원인으로는 흡수에 감수성이 높은 유치의 치주인대, 그리고 성장에 따라 증가되는 저작근육과 저작력, 혼합치열기에 유발되는 비정상적 교합 등을 생각할 수 있다. 계승 영구치가 결손된 유치가 비정상적인 치근 흡수를 보이는 경우에 유치는 유지될 수도 있지만, 여러 요인에 의하여 탈락될 경우에는 공간을 유지 할 것인지 판단해야 하며, 향후 보철치료나 교정치료를 요하므로 장기적인 치료계획을 수립해야 한다. Root resorption of primary teeth usually occurs as the succeeding permanent teeth erupt, which induces differentiation of the hemopoietic cells into osteoclasts. Their root resorption pattern reflects the eruption path of the succeeding permanent teeth, and eventually the primary teeth shed as their succeeding permanent teeth erupt. Even when a permanent tooth germ is congenitally missing, root resorption of the corresponding primary tooth may still occur due to various factors, such as inflammation, traumatic occlusal force, and weakness of periodontium etc. Such congenital missing of permanent teeth is a commonly observed phenomenon in human be ing, and it often accompanies delayed retention of primary teeth. The etiologic factors for congenital missing in elude not only systemic diseases, but also local factors and human evolution process. In the radiographs of the cases in this report, the primary teeth without succeeding permanent teeth show pathologic root resorption. Root resorption progressed about 1/2~3/4 of the roots, and the surfaces of the resorption area were irregular. Considering high susceptibility of the periodontal ligament of primary teeth to root resorption, pathologic root resorption of primary teeth with delayed retention can be explained by the increased masticatory muscle force and abnormal occlusion developed during the mixed dentition. When the primary teeth without succeeding permanent teeth are lost, decision for space maintenance is required and long-term treatment plan for further prosthetic or orthodontic treatment should be establsihed.

간 허혈성괴상의 CT소견에 대한 실험적 연구 : 간실질 및 피막의 경시적 변화와 병리조직의 비교 Changes of CT Findings of Liver Parenchyama and Capsule with Time Lapse Correlated with Histopathology

김창근,김강득,최시성,정선관,노병석,원종진 圓光大學校 醫科學硏究所 1994 圓光醫科學 Vol.10 No.1-2

In order to evaluate CT findings with time and to confirm the capsular structure correlating with its histopathologic findings, we experimentally induced ischemic necrosis of liver in 20 rabbits. Incision of the abdomen was performed under anesthesia. Ligation of hepatic artery, portal vein and hepatic duct of right inferior posterior lobe of the liver after injection of macroaggregated albumin into right inferior posterior portal vein in order to prevent from developing collateral circulation as possible. Precontrast and postcontrast enhanced CT images were obtained at 1. 2. 4 days and 1, 2. 4. 6 weeks after induction of ischemic necrosis. Necrotic area in the liver showed homogeneous low density compared to normal liver, and no contrast enhancement after contrast material administration, and marked volume loss with time. CT attenuation value of necrotic area at 1 day(36.7±6.4 M±SD, Hounsfield unit) approached to two third of that of normal liver(56.3±7.3) and showed no significant change until two weeks but increased significantly after four weeks. On contrast enhanced CT images, capsular structure was obsereved as a high density rim along the liver surface of the necortic area in 8 of 15 cases. From the first day on, homogenous ischemic or coagulation necrosis was observed but rarely findings of edema, hemorrhage and cystic change were observed on histopathologic specimen. In all of the histologic samples taken from 10 cases during th 2nd to 6th week, fibrous thickening with rich vascularity was observed along the surface of the necrotic area. In conclusion, ischemic necrosis of the liver showed homogeneous low density and no contrast enhancement. CT attenuation value of necrotic area increased significantly with time associated with markedly decrease in volume. Capsular structure attributed to the hypertrophy of the liver capsule and rich vascularity within it.