교정용 와이어의 비틀림 모멘트

최광철,김경호,박영철,강창수 대한치과교정학회 2000 대한치과교정학회지 Vol.30 No.4

각형 호선이 edgewise 브라켓에 삽입되면 first, second order는 bending에 의해, third order는 torsion(비틀림)에 의해 3차원적인 force system이 발생한다. Bending에 관하여는 분석적 그리고 실험적인 많은 연구가 보고 되어 있는 반면 비틀림에 관해서는 상대적으로 많은 연구가 이루어 지지 않았다. 본 연구의 목적은 각형 와이어의 재료와 단면의 형태가 와이어의 비틀림 모멘트에 어떻게 영향을 주는지를 이론적, 실험적으로 밝혀서 임상적으로 적절한 모멘트를 가할 때 호선의 재료와 굵기를 합리적으로 선택할 수 있도록 하는데 있다. 실험재료로는 third order조절을 위해 가장 많이 사용하는 호선을 사용하였다. 크기별로 0.016×0.022, 0.017×0.025, 0.019×0.025인치 그리고 재료로는 stainless steel (Ormco), TMA (Ormco), NiTi (Ormco), 그리고 braided stainless steel (DentaFlex, Dentaurum) 네 가지를 사용하여 총 12개의 조합을 사용하였다. Torsion formula를 이용하여 비틀림 강성 (toraue/twist rate)를 계산하였고 torque gauge를 이용하여 비틀림 강성, 항복 비틀림 모멘트 (yield torsional moment), 그리고 최대 비틀림 모멘트 (ultimate torsional moment)를 측정하였다. Torsion formula에 의하면 비틀림 강성 (T/θ)은 재료적인 특성(G)과 호선의 단면의 특성(J)에 비례하고 호선의 길이(L)에 반비례한다. 대부분의 실험치는 이론적인 값과 비슷하게 나타났다. As a rectangular wire is inserted into edgewise brackets the wire exerts a force system three-dimensionally. The force system may include bending force in first and second orders and a torsional force in third order. Analytical and experimental studies on bending force have been introduced, but information about torsion is still lack. The purpose of this study was to estimate the torsional moment in the force system of rectangular arch wires through theoretical and experimental studies. Wires most frequently used for third order control were selected as study materials. Cross sections of 0.016×0.022, 0.017×0.025, 0.019×0.025 inch rectangular wires in four different materials such as stainless steel (Ormco), TMA (Ormco), NiTi (Ormco), and braided stainless steel (DentaFlex, Dentaurum) were used. The torque/twist rate of each test material was calculated using the torsion formula. Torque/twist rate, yield torsional moment, and ultimate torsional moment were measured with a torque gauge. The torsion formula assesses that the torque/twist rate (T/θ) is proportional to the characteristics of material (G) and cross section (J), and is inversely proportional to the length of wire (L) Most experimental results corresponded with the formula. The relative stiffness was calculated for reference to a logical sequence of wire changes.

치주인대의 응력 분포 양상에 관한 실험 연구

최광철,김경호,박영철,한정윤 대한치과교정학회 2001 대한치과교정학회지 Vol.31 No.1

원하는 형태의 치아이동을 얻기 위해서는 M/F(Moment/Force) ratio의 조절이 필요하며, 이를 위해서는 치아의 저항중심의 위치를 아는 것은 매우 중요한 일이다. 본 연구에서는 실제 치아주위 환경을 비교적 유사하게 재현할 수 있는 치조골상과 치아의 이동을 시뮬레이션하는 장치를 제작하고, LVDT를 이용한 3차원 운동을 실시간으로 측정할 수 있는 시스템을 사용하여, 힘에 대한 3차원 공간상에서의 치주인대 응력 분포 양상 및 치아 저항중심과 회전축의 위치변화를 계측한 결과 다음과 같은 결론을 얻었다. 1.상악 견치에 원심방향으로 힘을 가했을 때, 치아의 저항중심의 위치는 힘의 크기와는 무관하였으며, 치근의 치경부측 약 29% 부위에 위치하였다. 이는 2차원 모형(42%) 보다 치관 쪽에 위치한다. 2.모멘트만 가하는 경우 치아의 저항중심과 회전축은 일치하였다. 3.치아에 가해지는 모멘트가 증가하는 경우 방향에 관계없이 치아는 정출되는 경향을 보였다. 4.힘이 가해지는 위치, 저항중심, 회전축간에는 일정한 관계가 성립했다(a×b = 49.6mm2). 이 관계식을 통해서 수평력이 가해질 때 예상되는 치아운동 양상을 알 수 있다. 5.수평력이 가해질 때 회전축의 위치는 일직선으로 나타난다. In order to achieve a desirable tooth movement, it is of great importance to control the M/F ratio and to know the location of the center of resistance. The purpose of this study was to locate the center of resistance and the axis of rotation, and to estimate the stress distribution in the periodontal ligament with experimental model. After preparing a model of an upper canine with a simulated periodontal ligament and alveolar bone, the force and moment were applied. The tooth movement was traced using measuring device with LVDTs(Linear variable differential transformers) that can measure three dimensional tooth movement in real time. The results were as follows. 1.The location of center of resistance by transverse force was 29% of root length measured from alveolar crest to apex regardless of force magnitude. The position of the center of resistance is more coronal than that of two-dimensional model(42%). 2.The center of resistance and the axis of rotation coincide when couple moment was applied. 3.As the magnitude of moment increases, tooth tends to extrude irrespective of the direction of the moment. 4.The relationship between location of force and axis of rotation (a x b =49.6mm2) was obtained. A tooth movement can be predicted through this formula. 5.The centers of rotation by transverse force were plotted linearly.

교정용 loop 스프링의 force system에 영향을 주는 요소

최광철,김경호,박영철 대한치과교정학회 1999 대한치과교정학회지 Vol.29 No.5

생역학적으로 우수한 스프링을 설계하기 위해서 스프링의 형태에 여러 가지 변화를 주면서 각 상황에서 force system이 변하는 양상을 수치분석계산과 spring tester를 이용한 실험과 비교하였다. 주어진 해부학적인 한계내에서 최대한 생역학적 효율을 높이는 요소들을 제시하였다. 1. 스프링의 높이가 증가하면 M/F ratio는 증가하고 L/D rate은 감소한다. 2 스프링의 최소 굽힘 모멘트 부위보다 위에 wire를 첨가하면 M/F ratio는 증가하고 L/D rate는 감소한다. 3. 스프링의 최소 굽힘 모멘트 부위보다 아래에 wire를 첨가하면 M/F ratio는 감소하고 L/D rate도 감소한다. 4. 스프링의 위쪽에 아무리 wire를 많이 첨가하여도 스프링의 높이 이상의 M/F ratio는 얻을 수 없다. 5. 제한된 높이의 스프링으로 충분한 M/F ratio를 얻기 위해서는 부가적인 모멘트가 필요하다. 6. 스프링의 수평 길이가 증가할수록 M/F ratio와 L/D rate는 감소하므로 부가적인 모멘트는 점점 각도가 증 가할 수 있도록 스프링 전체에 부여할 필요가 있다. 7. L/D rate는 재료, 단면, 그리고 형태에 영향을 받지만 M/F ratio는 재료나 단면에 관계없이 스프링의 형태에만 영향을 받는다. The shape of orthodontic retraction spring was varied and force system of each case was obtained using numerical analysis and verified with spring tester. The factors for obtaining biomechanically efficient spring under anatomic limitation were suggested as follows. 1. M/F ratio increases and L/D rate decreases as loop height increases. 2. M/F ratio increases and L/D rate decreases as incorporation more wire above minimum bending moment area. 3. M/F ratio decreases and L/D rate decrease as incorporating more wire below minimum bending moment area. 4. M/F ratio can not be greater than spring height no matter how much wire is incorporate at the apex of the loop. 5. Additional moment is necessary to obtain enough M/F ratio for translation under anatomical limitation. 6. additional moment should be incorporated at every part of the spring because M/F ratio and L/D rate decreases as horizontal spring length increases. 7. Material, cross section, and shape of the spring influence L/D rate, whereas M/F ratio is influenced by the shape of the spring independent from material and cross section.

Effect of subcutaneous drain on wound dehiscence and infection in midline laparotomy for gynecological disease (KGOG 4001)

( Chel Hun Choi ),( Nam Kyeong Kim ),( Kidong Kim ),( Yong Jae Lee ),( Keun Ho Lee ),( Jong-min Lee ),( Kwang Beom Lee ),( Dong Hoon Suh ),( Sunghoon Kim ),( Min Kyu Kim ),( Seok Ju Seong ),( Myong Ch 대한산부인과학회 2022 대한산부인과학회 학술대회 Vol.108 No.-

Objective: To identify the effect of subcutaneous (SQ) drain on wound dehiscence and infection in patients who underwent midline laparotomy for gynecological disease. Methods: Patients planned to undergo midline laparotomy for gynecologic disease, BMI< 35, age >18 years and ECOG performance status 0-2 were 1:1 randomized to case (with SQ drain) vs. control (without SQ drain) at 9 institutes in Korea, from February 2021 to December 2021. We compared the incidence of wound dehiscence at 4 weeks post-surgery and cumulative incidence of wound dehiscence and infection up to 4 weeks post-surgery between case and control group. Results: Of the 174 randomized patients (case 84, control 90), 12 patients were dropped due to follow-up loss (case 5, control 7) and 162 patients (intention-to-treat [ITT] cohort: case 79, control 83) were included. Fourteen patients (case 10, control 4) did not follow assigned intervention depending on the operator’s decision because the SQ layer was either too thick or too thin, and were excluded from per-protocol [PP] analysis (case 69, control 79). In ITT cohort, the frequency of cancer surgery (63/79 [79.7%] vs. 64/83 [77.1%]; p=0.683) and surgery time (mean ± standard deviation = 227.7±133.9 minutes vs. 226.7±118.2 minutes; p=0.960) were comparable in the case and control group. Mean wound length was also similar in both groups (case vs. control; 24.2 cm vs. 24.3 cm; p=0.933). There were no significant differences in the incidence of wound dehiscence at 4 weeks post-surgery (1/79 [1.3%] vs. 2/83 [2.4%]; p>0.999), the cumulative incidence of wound dehiscence (7/79 [8.9%] vs. 5/83 [6.0%]; p=0.491), and the cumulative incidence of wound infection (1/79 [1.3%] vs. 0/83 [0.0%]; p=0.488) between case and control group. PP analysis showed similar result to ITT analysis. Conclusion: SQ drain insertion did not decrease wound dehiscence and infection in patients who underwent midline laparotomy for gynecological disease.

Hg 분위기 열처리에 따른 적외선 감지용 Hg0.7Cd0.3Te 박막의 구조적 특성 변화

김광천 ( Kwang Chon Kim ),이차헌 ( Cha Hyun Lee ),최원철 ( Won Chel Choi ),김현재 ( Hyun Jae Kim ),김진상 ( Jin Sang Kim ) 한국센서학회 2010 센서학회지 Vol.19 No.5

CMCIS 시스템을 위한 MDEC 모듈의 설계 및 구현

정현철(Hyon-Chel Jung),김태군(Tea-Koon Kim),강동원(Dong-Won Kang),김재영(Jea-Young Kim),이세진(Se-jim Kim),조성칠(Sung-chil Cho),김홍삼(Hong-Sam Kim),이용희(Yong-Hee Lee),서광석(Kwang-Suk Seo),박명철(Myeong-Chul Park) 한국컴퓨터정보학회 2016 한국컴퓨터정보학회 학술발표논문집 Vol.24 No.1

본 논문에서는 다중 생체계측 장비를 CMCIS(Central Monitoring and Cardiology Information System) 기반의 통합 시스템에 연동하기 위한 MDEC(Medical Device Exchange Communication)의 설계 및 구현을 소개한다. MDEC은 6종의 계층장비의 신호를 받아 각 서버로 데이터를 전송할 수 있도록 설계하고 Linux OS을 포팅 하였다. 각 장비별 프로토콜에 대해 최소화된 기본 프로토콜을 정의하고 통신방법에 따라 UART 포트 혹은 USB 포트를 생체정보의 물리적 입력장치로 사용하였다. 호스트 서버와는 유무선 LAN울 통해 정보를 전달할 수 있게 하드웨어를 설계하였다. 본 연구의 결과는 CMCIS 기반의 통합 시스템을 구축하는 기반기술로 향후 효율적 의료서비스에 기여할 것으로 사료된다.

Reflow of Phosphorous Silicate Glass Layer Formed on Textured Si Surface in Crystalline Si Solar Cells

Kim, Jin-Sung,Seo, Min-Woo,Ahn, Kwang-Soon,Choi, Chel-Jong American Scientific Publishers 2012 Journal of Nanoscience and Nanotechnology Vol.12 No.7

<P>We have investigated the reflow behavior of phosphorus silicate glass (PSG) layer formed on textured Si surface using transmission electron microscopy and simulation. For conventional wet oxidation process, stress-dependent surface reaction and stress-dependent oxidant diffusion led to the oxidation retardation in both convex and concave regions of the textured Si surface, respectively. However, PSG film formed by POCl3-diffusion underwent reflow, resulting in the formations of thinner and thicker PSG films in convex and concave regions, respectively. Simulation results showed that the reflow of PSG films causes lateral thermal mismatch stresses to increase and decrease in convex and concave regions, respectively.</P>

設計品質 向上을 爲한 設計審査 模型 設定

김만균,장문철,최병관,함효준 대한설비관리학회 1999 대한설비관리학회지 Vol.4 No.1

Recently, the situation of the new product development has been drastically changed. Also, the development of DR(Design Review) Model for analysis has been interested by researchers. Presented in the paper is concerned with the set-up of DR model for improvement of design quality. The proposed model describes the relationship between input/output and factors of production such as quality, cost, delivery, moral, safety and design quality, etc. Also, these factors are associated with a significant positive correlation between DR and design quality, development and delivery on the production. So, DR is applied broadly in whole process of new product development and we can make it very successfully in developing time, quality, function, cost and delivery.

경피적 담도 조형술후 발생한 거대 담즙종 1예

김제형,황호근,최두환,유광현,류준형,최석채,김학철 圓光大學校 醫科學硏究所 1995 圓光醫科學 Vol.11 No.1

Biloma has been defined as an extraductular collection of bile within a defined capsular space. Development of an intraabdominal bile collection usually occurs secondary to traumatic or iatrogenic injury including abdominal surgery, percutaneous catheter drainage and transhepatic cholangiogram. Spontaneous bile leakage associated with other primary causes, including sickle cell anemia, gall bladder cancer and hepatocellular carcinoma, has been reported rarely. We present a case of biloma secondary to traumatic injury with liver biopsy, who had right upper guadrant pain, jaundice and yellowish skin discoloration in a patient with cholangiocellular carcinoma. Huge biloma was confirmed by percutaneous transhepatic biliary drainage and drained with pig tail catheter successfully. A case of huge biloma secondary to liver biopsy is presented with brief review of the literatures.

Effects of the flow rate of O₂ annealing ambient on structural and electrical properties of n+ emitter junctions formed using screen‐printed phosphorus diffusion process

Kim, Jin‐,Sung,Yun, Hyung‐,Joong,Seo, Min‐,Woo,Janardhanam, V.,Ahn, Kwang‐,Soon,Choi, Chel‐,Jong John Wiley Sons, Ltd 2012 Surface and interface analysis Vol.44 No.11

<P>We have investigated the effects of the flow rate of O<SUB>2</SUB> annealing ambient on the structural and electrical properties of the emitters with n+/p junctions formed using the screen printing of phosphorus (P) dopant paste, followed by O<SUB>2</SUB> annealing. The reaction between P‐paste and Si led to the formation of phosphorus silicate glass layer, of which P atoms were mostly segregated in surface and interface regions. The sheet resistance of the screen‐printed n+ emitters formed under O<SUB>2</SUB> flow rate of 5 l/min (LPM) was lower than that of 1 LPM. The recombination mechanism dominated the current transport in the forward bias regions of the screen‐printed n+ emitter, regardless of O<SUB>2</SUB> flow rate. The n+ emitter formed under O<SUB>2</SUB> flow rates of 5 LPM exhibited better rectification behavior with low reverse leakage, as compared with that of 1 LPM. The formation of thicker phosphorus silicate glass film caused by the increase in the O<SUB>2</SUB> flow rate resulted in the increase in the equilibrium concentration of Si interstitials in bulk Si and provided more P atoms being incorporated in n+/p emitter junction. The increases in maximum concentration of P atoms and junction depth caused by the increase in the O<SUB>2</SUB> flow rate could be responsible for superior junction quality of n+ emitter formed under O<SUB>2</SUB> flow rates of 5 LPM. Copyright © 2012 John Wiley & Sons, Ltd.</P>