• 제목/요약/키워드: Defect Position

검색결과 241건 처리시간 0.022초

고무사출성형의 적정설계 (Optimum Design of Rubber Injection Molding Process)

  • 이은주;임광희;부타이지양
    • Korean Chemical Engineering Research
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    • 제49권1호
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    • pp.47-55
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    • 2011
  • K사의 고무 사출성형에 있어서 애로사항인 등속조인트 부트(boots)의 크 (crack) 발생 등의 문제점을 해결하기 위하여, 상용 CAE 프로그램인 MOLDFLOW(Ver. 5.2)를 이용한 전산모사를 수행하여 적정금형설계를 도출하고 적정작업조건을 구축하였다. 그 결과 크 의 발생 원인은 크 이 발생하는 위치에 형성되는 weld 및 meld line의 형성 때문이고, 또한 크 이 발생하는 위치에서의 가류(curing)가 불완전한 것이 확인되었다. 이와 같은 weld 및 meld line의 형성을 방지하기 위해서 게이트(gate)의 위치를 변경하고 최적위치에 설계함으로써, 유동선단(melt front)의 충돌 또는 수지흐름의 만남을 최소화하는 충전패턴(fill pattern)을 형성하고 부트 안쪽 하단의 크 발생을 방지하였다. Weld 및 meld line과 에어트랩(air trap) 불량이 가장 큰 게이트 위치는 각각 최적 게이트위치를 기준으로 서로 정반대 방향임이 관찰 되었다. 한편 몰드(mold)의 온도를 $170^{\circ}C$로 유지하게 함으로써 크 이 발생했던 위치에 가류조건을 만족시켰다.

한국의 심장혈관수술 현황 (Cardiovascular Surgery in Korea)

  • 김형묵
    • Journal of Chest Surgery
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    • 제18권3호
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    • pp.371-382
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    • 1985
  • Over the past 4 decades after World War II a great deal of data and clinical experiences have been accumulated relating to the diagnosis and surgical treatment of congenital and acquired cardiovascular diseases in Korea. Clinical data on cardiovascular surgical cases performed in all 22 hospitals for open heart surgery in Korea was collected from it`s starting up to December 1984. The first recorded open heart surgery for a young adult atrial septal defect was performed by Young Kyoon Lee, M.D. on August 7, 1959, Seoul National University Hospital, Korea. And, some scattered reports on cardiovascular surgical cases in it`s early period have changed recently the number of hospitals for open heart surgery and clinical cases enormously in total amount of 13, 100 cardiovascular operations performed on 12, 990 cases up to December 1984. Of the total 13, 100 cardiovascular operations, congenital cardiovascular anomaly occupied 70%. Of the congenital cases, 6, 580 operations for acyanotic group [operative mortality 4.5%], and 2, 489 operations for cyanotic group [operative mortality 20%]. The incidence of congenital cardiovascular anomaly in order of frequency was ventricular septal defect [29%], patent ductus arteriosus [26%], Tetralogy of Fallot [22%], atrial septal defect [8, 6%], pulmonary valve stenosis [3.0%], and endocardial cushion defect [1.1%]. Of the 3, 412 valvular heart disease cases, which occupied 85% of total 4, 031 acquired cardiovascular disease, individual incidence was in mitral 2, 565 [63.5%], double valve 451 [11.1%], and simple aortic valve 351 [8.7%]. Total number of valve replaced, mechanical and tissue, was 2, 795, and 1, 884 for mitral, 808 for aortic, and 103 for tricuspid in position. Operative mortality for prosthetic valve replacement in total was 9.8%. Remained acquired cardiovascular cases chronic constrictive pericarditis [7.9%], cardiac tumor [1.9%], coronary artery bypass [1.8%], cardiac trauma [1.2%] and less than 1% of thoracic aortic aneurysm. Overall operative mortality for open and non-open cardiovascular surgical operation was 7.7% [congenital acyanotic group 3.2%, congenital cyanotic group 19.4%, and acquired group 7.8%]. In conclusion, present status of cardiovascular surgery in Korea is stabilized with accumulation of clinical cases and experiences, and the future in the field of cardiovascular surgery is promising, especially in the infant cardiac surgery and aortocoronary bypass surgery, with abrupt increase of specialized cardiac centers, trained specialists, and expanding social health insurance.

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전단간섭법을 이용한 감육 곡관부의 변형 계측 (Deformation Measurement of Well Thinning Elbow by Using Shearography)

  • 정현철;김경석;장호섭;정성욱;강기수
    • 비파괴검사학회지
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    • 제26권5호
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    • pp.321-328
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    • 2006
  • 본 논문에서는 전단간섭계를 이용하여 감육 곡관부의 변형을 계측하고 내부 감육 결함의 위치를 찾고자 하였다. 전단간섭법은 비파괴검사(NDT)와 응력/변형률 해석에 적용되어왔던 광학적 방법의 한가지이다. 이 기술은 간섭계에서 tilt mirror를 조작함으로써 조절이 가능한 민감도를 갖는 변위의 1차 도함수를 직접 측정할 수 있다는 이점을 지니고 있다. 본 논문에서는, 국부적으로 감육이 발생한 탄소강 곡관부에 대해 실험하였으며, 전단간섭법을 곡관부의 변형량 측정과 내부 감육결함 검사에 적용하였다. 실험 결과로부터, 이 기술이 내부 결함이 있는 배관부에도 적용이 가능함을 확인하였다.

악성종양 절제술 후 상악 재건의 장기 추적관찰 (Long Term Follow Up of Maxilla Reconstruction Following the Ablative Cancer Surgery)

  • 이한얼;안희창;최승석;조동인
    • Archives of Plastic Surgery
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    • 제34권4호
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    • pp.448-454
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    • 2007
  • Purpose: The objective of this study was to evaluate the outcomes of using the free flap in the reconstruction of maxillary defects. Methods: 27 consecutive cases of maxillary reconstruction with free flap were reviewed. All clinical data were analyzed, including ideal selection of flap, time of reconstruction, recurrence of cancer, postoperative complications, flap design, and follow-up results. The main operative functional items, including speech, oral diet, mastication, eye globe position and function, respiration, and aesthetic results were evaluated. Results: Among the 24 patients who underwent maxillary reconstruction with the free flap, 14 patients underwent immediate reconstruction after maxillary cancer ablation, and 10 patients underwent delayed reconstruction. There occurred 1 flap loss. Recurrences of the cancer after the reconstruction happened in 2 cases. Postoperative complications were 3 cases of gravitational ptosis of the flap, 2 cases of the nasal obstruction, and 1 case of fistula formation. Out of 27 free flaps, there were 15 latissimus dorsi myocutaneous flaps, 5 radial forearm, 4 rectus abdominis myocutaneous flaps, 1 scapular flap, 2 fibula osteocutaneous flap, respectively. Flaps were designed such as 1 lobe in 9 cases, 2 lobes in 9 cases, and 3 lobes in 5 cases. Among the 14 patients who had intraoral defect or who had palatal resection surgery, 2 patients complained the inaccuracy of the pronunciation due to the ptosis of the flap. It was corrected by the reconstruction of the maxillary buttress and hung the sling to the upper direction. All of the 14 patients were able to take unrestricted diets. In 6 patients who had reconstruction of inferior orbital wall with rib bone graft, they preserved normal vision. Aesthetically, most of the patients were satisfied with the result. Conclusion: LD free flap is suggested in uni-maxilla defect as the 1st choice, and fibular osteocutaneous flap and calvarial bone graft to cover the larger defect in bi-maxilla defect.

HDD 디스크-스핀들 시스템의 동특성 개선에 관한 연구 (A Study on Dynamic Performance Improvement of HDD Disk-Spindle System)

  • 좌성훈;손진승;이행수;홍민표;고정석;곽주영;조은형
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2001년도 춘계학술대회논문집
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    • pp.1130-1135
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    • 2001
  • This paper investigated the dynamic performance of HDD disk-spindle system to reduce disk fluttering. Rocking frequencies of the disk-spindle system and radial NRRO are measured to escape the ball defect frequencies and to determine the relative optimal position of the disk in the motor. It was found that disk fluttering was reduced by increasing disk thickness, inserting viscoelastic material between the disk and the spacer and decreasing the gap between the disk and the base.

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가변구조 시스템을 이용한 브러시리스 서보모터의 위치제어 (Position Control of Brushless Servo Motor using Variable Structure System)

  • 조창희;원종수
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 1990년도 추계학술대회 논문집 학회본부
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    • pp.10-14
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    • 1990
  • Variable Structure System(VSS) la being extended to a new control system of ac servo machines for its merits of simple mechanism and robustness. This paper has studied about applying VSS to position control for brushless servo motor. But VSS has the chattering problem of control input. This chattering phenomenon cause acoustic noises, torque ripple and increase harmonics of the current. One of the useful way to eliminate this defect of VSS, linearlizing the switching function is discussed here. Though the conventional method of linearizing the switching function diminishes the chattering, it may degrade the robustness of the system. In this paper, new linearized switching function which shows robust performance to the parametric variation and reduces chattering simultaneously is introduced and assured by simulation.

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CAN 시간지연에 대한 아라고 진자의 위치제어 성능분석 (Analysis of the Position Control Performance under the Time Delay in the Controller Area Network)

  • 박태동;이재호;윤수진;박기헌
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2006년 학술대회 논문집 정보 및 제어부문
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    • pp.354-356
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    • 2006
  • In this paper, the position control performance of networked control systems is analyzed when time delay through the network is considered. Integrating a control system into a network has great advantages over the traditional control system which uses point to point connection: it allows remarkable reduction in wiring, makes it easy to install and maintain the system, and improves compability. However, a networked control system has the critical defect that network uncertainties, such as time delay, can degrade the control system's performance. Therefore, the major concern of a networked control system is analyzing the effect of network uncertainties. This paper is concerned with PID controller performance for stability region, critical stability region and unstability region under the time delay in the Controller Area Network.

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레이저 슬릿빔의 경사각과 카메라 자세 추정 알고리즘을 이용한 벽면 결함 측정 (Measurement of Defects on the Wall by use of the Inclination Angle of Laser Slit Beam and Position Tracking Algorithm of Camera)

  • 김영환;송상호;윤지섭;강이석
    • 제어로봇시스템학회:학술대회논문집
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    • 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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    • pp.339-339
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    • 2000
  • In this parer, a method of measuring the size of defects on the wall and restructing the defect image of 3-dimension is developed based on the tracking algorithm of a camera position which uses the inclination angle of line slit beam for overcoming the difficulty of the corresponding problem identifying the image point in the both image. In the experiments, an algorithm for estimating the horizontal angle of CCD camera is presented and validated by applying it to the measurement of area and length under the variations of both the distance and the angle of CCD camera. And its performance is compared to that of the rotating and mapping method of image which has the Euclidian distance.

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Comparison of numerical simulation and experiment for the OiSF-Ring diameter in czochralski-grown silicon crystal

  • Oh, Hyun-Jung;Wang, Jong-Hoe;Yoo, Hak-Do
    • 한국결정성장학회지
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    • 제10권5호
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    • pp.356-361
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    • 2000
  • The radial position of OiSF-ring has been meaningful data in industry. Thus it's position was calculated by application of (V/G)/sub crit/ = 0.138 ㎟/minK and point defect dynamics for industrial scale grower with various pull rates. After the calculation, compared with experimental result. OiSF-ring diameters expected with calculation were good agreement with experimental results. In order to show validity of the predicted temperature distribution using STHAMAS which is one of the global simulator for Cz crystal growing, temperature was measured along the axis of crystal using thermocouples, and compared with the calculated temperature. We found the effective thermal conductivity K/sub m/ (r) which gives in accordance with the temperature distribution at the axis of crystal and crystal/melt interface shape between experimental and computational results. Therefore, effective thermal conductivity K/sub m/ (r) was applied instead of solving melt convection problem.

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심지융착기의 압착벨트 운동에 대한 연구 (A Study on the Press Belt Motion in the Fusing Press M/C)

  • 허유;안성기;장승호
    • 한국염색가공학회지
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    • 제17권5호
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    • pp.53-60
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    • 2005
  • Fusing press m/c is used for heating and pressing the specimens that are fed into between the two moving belts. Therefore the belt movement, belt temperature, and the pressure between belts must be kept constant. Especially, the belts should move in a limited operation range. When the belts run far out of the operation point, the machine has to be stopped, which results in a product defect because the fusing conditions, e.g., temperature and pressure, change during the transient process time period. It is important to avoid the belt stopping by maintaining the belt movement in a limited range. This study reports about the movement of the endless fusing belt in a long-span roller fusing m/c. The belt position changes as the 1st-order system does; if the roller axes are slanting each other with a certain angle, the belt running around the two rolls shows a dynamic behavior with the time that deviates fastly at the beginning from the initial condion and slows down. Then it reaches at a final position. The skewer the axes, the greater the position change. The inital change rate of the belt becomes large as the skewness of the axes between the two rollers increases.