• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2001년도 제33회 춘계학술대회 개최
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• pp.236-242
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• 2001

In this paper the effect of bump compliance, load, and the number of pad on the lift-off speed is studied. When the load is greater and bump compliance lower, the shaft is lifted off at higher rotating speed. And when the load is applied near the center of pad, lift-off speed is lower. When the number of pad increases, the lift-off speed is higher. The lift-off characteristics can be used to lengthen the life time of the coating and design the rotating machinery supported by bump bearings.

• 한국전기전자재료학회논문지
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• 제11권12호
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• pp.1079-1083
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• 1998

In this study, ultrasonic power of Aluminum wire bonder, bond time and bond force are investigated and valued in order to minimize failure of bonding pad lift. We also tried to control those 3 factors properly. We got the conclusion that if we turn down the ability of ultrasonic power or bond time, we can get a pad lift from a boundary between bond pad ad wire because pad metal and wire joining is unstable, but it is best condition when it ultrasonic power is 100∼130unit, bond time is 15∼20msec and bond force is 4∼6gf.

• Tribology and Lubricants
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• 제17권6호
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• pp.441-446
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• 2001

In this paper the effect of bump compliance, load, and the number of pad on the lift-off speed is studied. When the load is greater and bump compliance lower, the shaft is lifted off at higher rotating speed. And when the load is applied near the center of pad, lift-off speed is lower. When the number of pad increases, the lift-off speed is higher. The lift-off characteristics can be used to lengthen the lift time of the coating and design the rotating machinery supported by bump bearings.

• Journal of Advanced Marine Engineering and Technology
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• 제31권4호
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• pp.350-355
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• 2007

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.

• Archives of Plastic Surgery
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• 제34권2호
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• pp.250-257
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• 2007

Purpose: Aging changes of midface include drooping of lower lid, wrinkles of malar area, orbitomalar groove and deepening of nasolabial fold from drooping of malar fat pad. Improvement of lower lid can be achieved through lower blepharoplasty, but improvement of cheek can not be gained. Superficial subciliary cheek lift(by Moelleken, 1996) is a method that lifts malar fat pad through extended subciliary incision. We obtained simultaneous improvement of lower lid, malar wrinkles and orbitomalar groove with modification of this technique. Methods: From December 2003 to January 2006, we performed this method on 21 patients among volunteers for lower blepharoplasty who wanted to correct orbitomalar groove and malar wrinkles. Under local anesthesia, lateral extension of subciliary incision is done 1cm from the lateral orbital rim. Skin-muscle flap is elevated, and dealing of orbital fat and septum is the same as with ordinary lower blepharoplasty. After downward subcutaneous dissection through extended incision, exposing the upper 1/3 level of malar fat pad, superolateral fixation is done to superior deep temporal fascia. Excision of the upper part of fat pad is performed, if needed. After excision of overlapped skin-muscle flap, skin closure is done. Results: We obtained satisfactory results with this simple method for improvement of orbitomalar groove and malar wrinkles among patients for lower blepharoplasty. During a follow-up period of 5 months on the average, no revision was performed. Conclusion: Under local anesthesia, lower blepharoplasty and improvement of orbitomalar groove and malar wrinkles can be achieved at the same time. It is good for patients who do not want conventional midface-lifting. But surgeons should select patients and perform cautiously for it may leave a scar of the extended incision that require over 2 months for maturation and it is insufficient for improvement of nasolabial fold compared to conventional mid face-lifts.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 춘계학술대회논문집
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• pp.94-99
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• 2003

As the rotating speed of rotors is increased, the instability and power loss become serious problems. Gas bearings are introduced as a good solution to those problems. But in the development of gas bearings, high load capacity and high damping force to vibrations are required. In this study a new air bearing using leaf spring pad is introduced to improve load capacity and damping force. The experimental results of the leaf spring pad air bearings show high load capacity and high damping forces. And the results show that leaf spring pad air bearings can be simultaneously acted as radial and thrust bearings

• Archives of Plastic Surgery
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• 제32권2호
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• pp.262-266
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• 2005

In some blepharochalasis patients, upper blepharoplasty alone is not satisfactory because of narrow distance between eyebrow and eyelash. On that occasion, eyebrow lift is advisable. There are many methods of classical eyebrow lift, such as direct excision, transblepharoplasty approach, anterior hairline technique, and so on. But they are not so effective, have a tendency to recur and also give rise to side effects; unacceptable scar, facial nerve palsy, sensory loss and hematoma, etc. Some patients who have prominent nasolabial folds, are reluctant to perform face lift procedure due to psychologic or economic burden. The authors performed the eyebrow lift procedure separately or simultaneously with face lift or forehead lift. After making 2 or 3 slit incisions, we passed absorbable suture material, 3-0 vicryl, through suborbicularis oculi fat layer. Then it was passed through subperiosteal plane and fixated to the temporalis fascia. When patients complain prominent nasolabial folds, malar fat pad was elevated also in the same manner. This methods is effective and has minimal complication such as facial nerve palsy, scar, sensory loss. Recurrent tendency was rarely observed during follow-up. Dimples were observed at slit incision sites but they disappeared within 2 or 3 weeks. Eyebrow lift and malar fat lift by absorbable suture elevation with subperiosteal dissection is a simple and less morbid. Because of its effectiveness and little side effect or complication, this procedure can be a useful method.

• 마이크로전자및패키징학회지
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• 제17권2호
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• pp.41-47
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• 2010

PCB와 BGA 패드의 형태가 무연솔더 접합부의 기계적 특성에 미치는 영향을 연구하었다. 현재 BGA/PCB 패드의 형태는 NSMD (Non-Solder Mask Defined)와 SMD (Solder Mask Defined) 두 가지 구조로 형성되어 있다. 본 연구에서는 OSP 도금처리한 무연솔더(Sn-3.0Ag-0.5Cu, Sn-1.2Ag-0.5Cu)의 패드 형태를 NSMD, SMD로 달리하여 낙하충격시험, 굽힘충격시험, 고속전단시험을 통한 솔더 접합부의 기계적 특성을 연구하였다. 낙하충격과 굽힘충격시험의 경우 패드 구조에 따른 솔더볼 접합부의 특성수명은 동일한 경향을 나타내었으며, 솔더접합부의 기계적 특성은 SMD가 NSMD보다 우수하였다. 이 이유는 SMD의 경우 낙하충격 시험과 고속 전단시험 모두 IMC에서 파단이 일어난 반면에 NSMD의 경우 낙하충격 시험 후의 파단면은 패턴을 감싸고 있는 랜드 상단 모서리 부분에서 파단이 일어났기 때문인 것으로 판단된다. 전단시험의 경우에는 NSMD 접합부에서 패드 lift현상이 발생하였다. 따라서 BGA/PCB의 패드구조의 조합은 SMD/SMD > SMD/NSMD > NSMD/SMD > NSMD/NSMD 순으로 기계적 특성 수명이 우수하였다.

• Tribology and Lubricants
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• 제28권5호
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• pp.197-202
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• 2012

In this study, with the purpose of fundamentally improving the unbalance response vibration of a large PRT motor-generator rotor by design, a performance improvement design analysis is carried-out by retrofitting tilting pad bearings, replacing the plain partial journal bearings that were originally applied for operation at a rated speed of 1,800 rpm. In this process, a goal of the design analysis is to obtain a design solution for maximizing the direct stiffness of the bearings while satisfying the key basic lubrication performance requirements such as the minimum lift-off speed and maximum oil-film temperature. The results show that with a careful design application of tilting pad journal bearings for operation at such a relatively low speed of 1,800 rpm, direct stiffness increment of the bearings by about two times can be effectively achieved. Prevention of pad unloading is also considered in the analysis. Moreover, the designs of elliptical and offset half journal bearings are also analyzed and reviewed.

• Tribology and Lubricants
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• 제28권6호
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• pp.265-271
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• 2012

In the preceding Part I study, for improving the unbalance response vibration of a large PRT motor-generator rotor fundamentally by design, a series of design analyses were carried out for bearing improvement by retrofitting from original plain partial journal bearings, applied for operation at a rated speed of 1,800 rpm, to final tilting pad journal bearings. To satisfy evenly key basic lubrication performances such as the minimum lift-off speed and maximum oil-film temperature, a design solution of 5-pad tilting pad journal bearings and maximizing the direct stiffness by about two times has been achieved. In this Part II study, a detailed rotordynamic analysis of the large PRT motor-generator rotor-bearing system will be performed, applying both the original plain partial journal bearings and the retrofitted tilting pad journal bearings, to confirm the effect of rotordynamic vibration improvement after retrofitting. The results show that the rotor unbalance response vibrations with the tilting pad journal bearings are greatly reduced by as much as about one ninth of those with the plain partial journal bearings. In addition, for the tilting pad journal bearings there exist no critical speed up to the rated speed and just one instance of a concerned critical speed around the rated speed, whereas for the plain partial journal bearings there exist one instance of a critical speed up to the rated speed and two instances of concerned critical speeds around the rated speed.