• 한국정밀공학회지
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• 제23권2호
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• pp.65-72
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• 2006

Downcoiler is one of the major facilities in hot strip mill operation. The key to good coiling is having good equipment, modem control systems, excellent maintenance and an understanding of coiling process. Therefore, this study aims to develop a program that is useful for calculating machine design parameters and simulating coiling process. In this study, the pinching and coiling mechanism of the downcoiler was thoroughly studied and some of operational factors and their effects on the coiling process were investigated. The software was developed to estimate engineering parameters for coiler component design and to determine optimal setting values for successful coiling operation. In order to check the accuracy and usefulness of the developed software, the simulation of the downcoiler in $\#2$ Hot Strip Mill in Pohang Works was performed. The simulation results suggested that the set-up value for unit tension could be lowered. Test coiling operation by using the lowered set-up value for unit tension resulted in much more successful coiling in the aspect of strip quality and power consumption.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1997년도 추계학술대회논문집
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• pp.32-39
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• 1997

The coiling station of ISP coil box is an equipment that winds a hot bar rolled at reduction unit into a coil without mandrel. In the coiling process, the roll gap of the bending unit is a significant one of several factors that influence bar coiling. To obtain a good bar-coil, the roll gap must be set appropriately according to the bar thickness. In this study, with 2-dimensional isothermal elastic-plastic finite element method, authors investigated influence of the change of the roll gap on the initial coiling shapes and the formed inner diameters of coils. Based on finite element analysis, authors proposed the appropriate roll gap according to the bar thickness to be able to wind a hot bar. The inner diameters of coils by results of analysis comparatively agreed with coling operation conducted in plant.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.955-958
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• 2003

Strip top mark is one of the major problem areas in hot strip coiling operation. The key for good coiling is having a precise detection instrument of strip head end and an understanding of QOC(quick open control) control algorithm and mechanism. Therefore, this study aims at developing QOC monitoring system that is useful for avoiding strip top mark at coiling process. In this study, strip movement between mandrel and unit roll(wrapper roll) was thoroughly studied using high speed camera. The monitoring system was developed to calculate QOC open time and to estimate optimal open time values for good coiling operation. Its performance has been proven by extensive field tests on downcoiler of #2 Hot Strip Mill Line in Pohang Works.

• 한국전산구조공학회논문집
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• 제26권1호
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• pp.1-7
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• 2013

본 논문에서는 해저케이블 부두 하역용 장비인 코일링 암(coiling arm)에 대한 국산화 자체개발 내용 중 구조설계 및 해석결과 내용을 제시하였다. 상세 구조설계를 위해 3차원 CAD 프로그램을 이용하여 고 정밀도의 모델링을 수행하였고, 유한요소 기법을 이용하여 전산구조해석을 수행하였다. 코일링 암의 활용 목적에 맞추어 하역대상 케이블을 선박에서 케이블 탱크로 하역시 효과적으로 가이드 할 수 있도록 베어링 및 롤러 부품을 설계하여 메인 암이 회전하고 케이블 가이드가 이동할 수 있도록 하였고, 기존의 외국 모델에서 사용하던 와이어 및 모터 시스템을 이용한 케이블 가이드 작동방식을 유압 시스템을 이용한 작동방식으로 변경하여 원가절감을 달성하면서 사용자가 직관적으로 작동할 수 있도록 설계하였다. 장비 자체의 자중 및 하역 케이블 하중조건에 대한 응력 해석을 수행하였고, 유압시스템의 과작동에 따른 파손 가능성을 고려하였다. 케이블 가이드의 운동 및 설치 지면의 경사도에 따른 전복 안전성 해석을 수행하였으며, 설치장소의 풍하중 효과도 추가로 고려하였다. 본 연구를 통해 기존 수입품 코일링 암의 작동방식 개선과 독자적인 구조설계 및 해석 방법을 확립하였으며, 실제 국내 최초로 자체 개발된 제품의 현장설치 완료 및 하역작업의 효율적이고 정상적인 운영을 완료 및 검증하였다.

• Journal of Korean Neurosurgical Society
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• 제45권1호
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• pp.5-10
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• 2009

Objective : Direct surgical clipping of paraclinoid aneurysms poses technical challenges to even very experienced neurosurgeons, making endovascular treatment an alternative treatment modality in many centers. We have therefore retrospectively evaluated the safety and efficacy of endovascular detachable coil embolization of paraclinoid aneurysms. Methods : From June 1997 to June 2007, 65 patients underwent endovascular detachable coiling for 67 paraclinoid aneurysms (of which 9 were ruptured and 58 were unruptured) in our institute. Their medical records, radiological images and readings, and operation records were reviewed retrospectively. Results : After the initial embolization procedure, complete occlusion was achieved in 29 (43.3%) of the aneurysms treated by endovascular detachable coiling. Six aneurysms required retreatment, with two each requiring one, two, or three additional endovascular procedures. Fifty-five (82.1%) aneurysms were measured by three-dimensional time of flight (TOF) magnetic resonance images (MRI) or transfemoral cerebral angiography (TFCA) at a mean follow-up of 29.7 months (range from 4 to 94 months), with 39 aneurysms (70.9%) showing complete occlusion. Thromboembolic events (3.8%) were the most frequent complication. Rupture did not occur during or after any of the procedures. According to the Glasgow Outcome Scale (GOS), 98.4% of the patients treated by coil embolization had a score of 4 or 5. Conclusion : Our results indicate that endovascular detachable coiling is a safe and effective treatment modality in paraclinoid aneurysms.

• Journal of Korean Neurosurgical Society
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• 제45권4호
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• pp.224-230
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• 2009

Objective : We aimed to analyze clinical and radiological outcomes retrospectively in patients with basilar apex aneurysms treated by coiling or clipping. Methods : Outcomes of basilar bifurcation aneurysms were assessed retrospectively in 77 consecutive patients (61 women, 16 men), ranging in age from 25 to 79 years (mean, 53.7 years) from 1999 to 2007. Results : Forty-nine patients out of 77 patients (63.6%) presented with subarachnoid hemorrhages of the 49 patients treated with coiling, 27 (55.1 %) showed complete occlusion of the aneurysm sac. Of these, 13 patients (26.5%) developed coil compaction on angiographic or MRI follow-up, with recoiling required in 9 patients (18.4%). Procedural complications of coiling were acute infarction in nine patients and the bleeding of the aneurysms in six patients. The remaining 28 patients underwent microsurgery : twenty-six of these (92.9%) with microsurgery followed up with conventional angiography. Complete occlusion of the aneurysm sac was achieved in 19 patients (73.1%). Operation-related complications of microsurgery were thalamoperforating artery injuries in three patients, retraction venous injury in two, postoperative epidural hemorrhage (EDH) in one, and transient partial or complete occulomotor palsy in 14 patients. Glasgow Outcome Scores (GOS) were 4 or 5 in 21 of 28 (75%) patients treated with microsurgery at discharge, and at 6 month follow-up, 20 of 28 (70.9%) maintained the same GOS. In comparison, GOS of four or 5 was observed in 36 of 49 (73.5%) patients treated with coiling at discharge and at 6 month follow-up, 33 of 49 patients (67.3%) maintained the GOS from discharge. Conclusion : Basilar top aneurysms were still challenging lesions based on our series. Endovascular or microsurgery endowed with its inborn risks and procedural complications for the treatment of basilar apex aneurysms individually. Microsurgery provided better outcome in some specific basilar apex aneurysms. For reaching the most favorable outcome, endovascular modality as well as microsurgery was inevitably considered for each specific basilar apex aneurysm.

• Journal of Korean Neurosurgical Society
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• 제41권5호
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• pp.318-322
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• 2007

Regarding the bilateral vertebral artery [VA] dissecting aneurysms, treatment strategy remains controversial because there have not been enough cases to reach a conclusion on the best treatment. We present a patient underwent staged microsurgical trapping and endovascular coiling for each dissecting aneurysm of bilateral VA presenting subarachnoid hemorrhage [SAH]. The ruptured side was managed by VA trapping procedure without any neurological deficit. Postoperative cerebral angiography revealed patent right PICA without filling of previous right dissecting aneurysm and spontaneous occlusion of the left dissecting aneurysm one month after trapping procedure. However, follow-up angiography revealed recanalization and growing of the left VA dissecting aneurysm one year after the operation. The patient underwent endovascular embolization using GDC for the proximal occlusion of the left VA and postoperative course was uneventful.

• Corrosion Science and Technology
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• 제3권5호
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• pp.209-215
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• 2004

Flexible hydraulic hose assembly that consists of hose and joints is used widely on various construction heavy equipments, agricultural machines, motor vehicles, and industrial heavy machines that require flexibility on hydraulic pipelines. It is classified by the maximum usage pressure which is determined by the winding layers of coiling steel wire and the inner diameter of the hoses. In this paper, we designed and performed an accelerated life test for assessing the reliability of a flexible hydraulic hose assembly. In the proposed accelerated life test, typical impulse pressure testing method is applied with the half omega flexing operation to simulate the practical flexing motion of the hose assembly.

• Journal of Korean Neurosurgical Society
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• 제53권6호
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• pp.383-385
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• 2013

We present an unusual case of peritoneal catheter migration following a ventriculoperitoneal shunt operation. A 7-month-old infant, who had suffered from intraventricular hemorrhage at birth, was shunted for progressive hydrocephalus. The peritoneal catheter, connected to an 'ultra small, low pressure valve system' (Strata$^{(R)}$; PS Medical,Gola, CA, USA) at the subgaleal space, was placed into the peritoneal cavity about 30 cm in length. The patient returned to our hospital due to scalp swelling 21 days after the surgery. Simple X-ray images revealed total upward migration and coiling of the peritoneal catheter around the valve. Possible mechanisms leading to proximal upward migration of a peritoneal catheter are discussed.

• 한국초전도ㆍ저온공학회논문지
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• 제16권4호
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• pp.49-52
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• 2014

REBCO coated conductor (CC) tapes with superior mechanical and electromechanical properties are preferable in applications such as superconducting coils and magnets. The CC tapes should withstand factors that can affect their performance during fabrication and operation of its applications. In coil applications, CC tapes experience different mechanical constraints such as tensile or compressive stresses. Recently, the critical current ($I_c$) degradation of CC tapes used in coil applications due to delamination were already reported. Thermal cycling, coefficient of thermal expansion mismatch among constituent layers, screening current, etc. can induce excessive transverse tensile stresses that might lead to the degradation of $I_c$ in the CC tapes. Also, CC tapes might be subjected to very high magnetic fields that induce strong Lorentz force which possibly affects its performance in coil applications. Hence, investigation on the delamination mechanism of the CC tapes is very important in coiling, cooling, operation and design of prospect applications. In this study, the electromechanical properties of REBCO CC tapes fabricated by reactive co-evaporation by deposition and reaction (RCE-DR) under transversely applied loading were investigated. Delamination strength of the CC tape was determined using the anvil test. The $I_c$ degraded earlier under transverse tensile stress as compared to that under compressive one.