상악 4절치의 후방견인시 나타나는 현상에 관한 유한요소법적 분석

천옥진,김태우,서정훈 대한치과교정학회 1995 대한치과교정학회지 Vol.25 No.5

상악치열에서 제 1 소구치를 발거하고, 이 위치로 견치를 후방이동시킨 상태에서 retraction archwire를 사용하여 상악 4절치를 한 묶음으로 후방견인시켰을 때 초기에 나타나는 모든 힘 체계와 개개치아의 이동양상을 살펴보고 바람직하지 않은 치아이동을 감소시키기 위한 방안을 모색하고자 본 연구를 시행하였다. 먼저 유한요소법을 이용하여 상악 치아와 치근막의 해부학적 형태 및 생체적 특성을 컴퓨터로 재현시키고 모형화된 브라켓을 부착시킨 후, beam 요소를 사용하여 5종의 retraction loop를 하나씩 부여한 다섯 가지의 탄선을 모형화하고, 브라켓과 탄선간에는 gap 요소를 사용하여 모형화함으로써 전체 유한요소 모형을 완성하였다. loop의 형태, activation의 양, gable bend와 torque의 조건에 따른 차이를 검토하기 위해, 각 조건을 변화시켜 loop를 activation시켰을 때 탄선이 발휘하는 힘과 모멘트, 치아이동의 변위를 3차원적으로 정량적 및 가시적으로 평가하고 비교, 분석한 결과 다음과 같은 결론을 얻었다. 1. tear-drop loop archwire 사용시 각 치아의 근원심이동 및 설측이동이 발치공간 폐쇄에 도움이 되었으나, 바람직하지 못한 상하이동과 각 방향으로의 회전이동이 부가적으로 나타났다. 2. 다섯 가지의 retraction archwire 중 T-loop archwire에서 공간폐쇄에 도움이 되는 치아이동이 가장 작게 나타났으며, 각 방향으로의 회전이동 역시 가장 작게 나타났다. 3. tear-drop loop archwire에서 activation 양을 증가시킴에 따라 공간폐쇄에 도움이 되는 치아이동이 점차 증가했으나, 바람직하지 못한 상하이동과 각 방향으로의 회전이동이 함께 증가했다. 4. tear-drop loop archwire에서 loop의 전후방에 gable bend 부여시 전치에서 근원심방향의 치체이동에 도움이 되었으나, 모든 치아에서 상하이동과 각 방향으로의 회전이동이 함께 증가했다. 5. tear-drop loop archwire의 절치부에 치근 설측 torgue 부여시 이들 치아의 순설경사를 개선시키는 효과를 얻었으나, 그 반작용으로 견치 치관의 설측회전이 크게 증가했으며, 전치의 상하이동과 모든 치아에서 각 방향으로의 회전이동이 증가했다. This study was designed to investigate force systems and tooth movements produced by retraction archwire during retraction of four maxillary incisors after the maxillary canine retraction into the maxillary first premolar extraction space using the computer-aided three-dimensional finite element method. A three-dimensional finite element model, consisting of 2248 elements and 3194 nodes, was constructed. The model consisted of maxillary teeth and surrounding periodontal membranes, .022˝x.028˝-slot brackets, and 5 type of retraction archwires(.019˝x.025˝stainless steel archwire) modeled using the beam elements. The contact between the wire and the bracket slot was modeled using the gap elements because of the non-linear elastic behaviors of the contact between them. The forces and moments, and displacements produced by retraction archwire were measured at various conditions to investigate the difference according to types of loops, magnitudes of activation force, gable angle, and anterior lingual root torque. The results were expressed quantitative and visual in the three-dimensional method. The following conclusions can be drawn form this study : 1. When the tear-drop loop archwire was activated, the mesio-distal and lingual translational movements of the teeth helped to close the extraction space, but unwanted movements of the teeth including intrusions and extrusions, and rotational movements in each direction occurred. 2. Activation of T-loop archwire compared with those of other types of retraction archwires produced the least translational movements of the teeth helped to space closure and also least unwanted movements of the teeth. 3. Increasing amount of activation in the tear-drop archwire led not only to increase of translational movements of the teeth helped to space closure, but also increase if unwanted movements of the teeth. 4. Addition of gable bend in the tear-drop archwire helped anterior teeth to translational movements in the mesio-distal direction, but increased unwanted movements of the teeth. 5. Addition of anterior lingual torque in the tear-drop archwire helped central and lateral incisor to improve their facio-lingual inclination, but increased unwanted movements of the teeth.

Mn-Ce 복합 산화물에 의한 톨루엔 촉매 산화

천태진,최성우,이창섭 한국환경과학회 2005 한국환경과학회지 Vol.14 No.4

Activity of manganese oxide supported on γ-Al₂O₃ was increased when cerium was added. Also, cerium-added manganese oxide on v-Al₂O₃ was more effective in oxidation of toluene than that without cerium. XRD result, it was observed that MnO₂+CeO₂ crystalline phases were present in the samples. For the used catalyst, a prominent feature has increased by XPS. TPRITPO profiles of cerium-added manganese oxide on γ-Al₂O₃ changed significantly increased at a lower temperature. The activity of 18.2 wt% Mn+10.0 wt% Ce/γ-Al₂O₃ increased at a lower temperature. The cerium added on the manganese catalysts has effects on the oxidation of toluene.

Mn이 첨가된 V₂O_(5)/TiO₂ 촉매상에서 질소산화물의 저온 SCR 특성

천태진,최상기,최성우 한국환경과학회 2004 한국환경과학회지 Vol.13 No.6

V₂O_(5)/TiO₂ catalysts promoted with Mn were prepared and tested for selective catalytic reduction of NOx in NH3. The effects of promoter content, degree of catalyst loading were investigated for NOx activity while changing temperatures, mole ratio, space velocity and O₂ concentration. Among the various V₂O_(5) catalysts having different metal loadings, V₂O_(5)(l wt.%) catalyst showed the highest activity(98%) under wide temperature range of 200-250 C. When the V₂O_(5) catalyst was further modified with 5 wt.% Mn as a promoter, the highest activity(90-47%) was obtained over the low temperature windows of 100-2000. From Mn-V₂O_(5)/TiO₂, it was found that by addition of 5 wt.% Mn on V₂O_(5)/TiO₂ catalyst, reduction activity of catalyst was improved, which resulted in the increase of catalytic activity and NOx reduction. According to the results, NOx removal decreased for 10%, but the reaction temperature down to 100℃.

흰쥐 두힘살근 지배신경축 규명에 관한 연구

강태천,이흥식,이인세,서제훈,이봉희 대한해부학회 1997 Anatomy & Cell Biology Vol.30 No.6

分權化된 組織의 社內對替價格決定方法에 관한 小考

全泰玩 건국대학교 1985 商經論叢 Vol.- No.20

총수담관결찰이 백서 신세뇨관의 S-100 면역반응에 미치는 영향

金天浩,李永浩,朴景蘭,申台均,金源式 충남대학교 의과대학 지역사회의학연구소 1991 충남의대잡지 Vol.18 No.1

For the study on the changes of S-100 reactivity at the renal tubular epithelium of rats(SpragueDawley, b.w. 250± 20gm. male), the common bile duct ligation was performed under ether anesthesia. At 1st, 3rd, 5th and 7th day after operation, the S-100 immunoreactivity were compared with control rats. The results were as followings; 1. In the control rat, S-100 positive reactions were observed at the collectiong tubule, Henle's loop, distal tubule(partly) and renal papilla. 2. In common bile duct ligated rats, S-100 positive reactions were observed at the proximal convoluted tubule in the rats 1 day after operation, and at the collecting tubule and proximal convoluted tubule in the 3 days after operation.

노인성질환 환자의 돌봄을 위한 전반적인 상태 평가표 및 돌봄을 이한 육체적 노동 요구 평가표의 타당도 및 신뢰도

김태유,김상윤,임병훈,권오영,최낙천 대한노인병학회 2002 대한노인병학회지 Vol.6 No.4

Monotone Chain의 도구경로를 구하는 최적 알고리즘

양태천 慶星大學校 1992 論文集 Vol.13 No.3

Shrinking and expanding solids (called offsetting) is useful in many engineering applications. In CAD/CAM, to find the the tool path (offset) for a given shape, an efficient algorithm is needed. In this paper, we give an optimal linear time algorithm for findidng the tool path for a monotone chain using a stack.

해체주의 이론의 행정학적 적용

한태천 경운대학교 산업기술연구소 2000 産業技術硏究論文誌 Vol.3 No.1(B)

This paper is a study on the public administrative application of the deconstruction theory. The deconstruction theory is to pull down that sociologists have been traditional fixed conceptions, methods, and structures or frameworks. As a result of study The deconstruction theory is just one we account for public administrative phenomena which are what we call 'see in a new light', do away with conventionalities', and 'reform structures' in public administrative works.

슬래그-패각계 조합물의 경화특성

송태웅,천성민 경남대학교 신소재연구소 2002 신소재연구 Vol.14 No.-

고로 수쇄슬래그의 알칼라 자극제로 굴껍질 하소물을 사용하고 충진재로서 굴껍질 분말을 사용한 수경성 조합물을 제조하였다. 알칼리 자극제의 혼합 비율은 경화 특성에 큰 영향을 미쳤으며, 10∼20%일 때 가장 높은 강도가 발현되었다. 또한, 굴껍질 분말의 충진재로서의 역할은 첨가량이 30%일 때 가장 효과적이었으며, 알칼리 자극제 혼합량에 상관없이 강도 상승의 효과를 나타내었다. A hydraulic mixture was prepared from blast furnace slag, calcined oyster shell as an alkaline stimulant, and powdered oyster shell as a filler. Hardening properties of the mixture were remarkably affected by the amount of alkaline stimulant. The amount of alkaline stimulant for the best strength of hardened body was about 10∼20% by weight. Addition of powdered oyster shell was most effective as a filler at 30% without relation to the amount of alkaline stimulant.