• Journal of the Computational Structural Engineering Institute of Korea
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• v.26 no.1
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• pp.1-7
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• 2013

Structural design and analysis of a coiling arm unloading machine for submarine cable have been originally conducted in this study. Three-dimensional CAD modeling process is practically applied for the structural design in detail. Finite element method(FEM) and multi-body dynamics(MBD) analyses are also used to verify the safety and required motions of the designed coiling arm structure. The effective moving functions of the designed coiling arm with respect to rotational and radial motions are achieved by adopting bearing-roller mechanical parts and hydraulic system. Critical design loading conditions due to its self weight, carrying cables, offshore wind, and hydraulic system over operation conditions are considered for the present structural analyses. In addition, possible inclined ground conditions for the installation of the designed coiling arm are also considered to verify overturn stability. The present hydraulic type coiling arm system is originally designed and developed in this study. The developed coiling arm has been installed at a harbor, successfully tested its operational functions, and finished practical unloading mission of the submarine cable.

• Journal of Korean Neurosurgical Society
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• v.59 no.4
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• pp.341-345
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• 2016

Objective : Solitaire AB stent-assisted coiling facilitates the endovascular treatment of wide-necked intracranial aneurysms. We present our experience of coiling the micro-aneurysms of wide-neck with Solitaire AB stent assisting in a single center. Methods : Thirty-one Solitaire AB stents were used to treat via endovascular approach patients with 31 wide-neck micro aneurysms in a single center in China. Technical and clinical complications were recorded. Modified Rankin Scale was used to evaluate the patients' conditions via clinic and telephone follow-up. Results : The mean width of aneurysm sac was $2.30{\pm}0.42mm$, and the mean diameter of aneurysm neck was $2.83{\pm}.48mm$. Complete occlusion was achieved in 28 aneurysms (90.32%); neck remnant was seen in 3 aneurysms (9.68%). Technical and clinical complications related to the procedure were encountered in four patients (12.5%). Two patients died (6.25%). No patient had a permanent deficit. Conclusion : Solitaire AB stent was a safe and efficiency tool in assisting coiling of micro aneurysms with wide neck, but may be not suitable for a blaster-like one. Mid- and long-term follow-up will be required to elucidate the impact of the Solitaire AB stent on recanalization rate.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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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.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1863-1868
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• 2008

In an electrospinning process, nanofibers are produced from a droplet of a viscoelastic polymer solution subjected to strong electric field. To date, intrinsic bending instability of the electrical jets has resulted in random piles of nanofibers on a grounded collector plate. Here we report a novel electrospinning process where a hollow micropillar is constructed by the coiling of nanofibers on a sharp grounded collector. We show that the hollow microstructure formation can be explained by the viscous fluid rope coiling theory. The current process can be employed for the fabrication of three-dimensional scaffolds for cell culturing and the three-dimensional nanoprinting.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2002.05a
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• pp.39-43
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• 2002

A new model for heat transfer and thermal deformation analysis according to strip mm in coiling process has been proposed. Finite difference analyses for heat transfer of cold rolled coil have been carried out under various coiling tensions and strip crown using the equivalent thermal conductivity for the radial direction of cold rolled coil which is a function of strip thickness, surface characteristics and compressive pressure. The compressive pressure is calculated from a equation expressed as a function of hoop stress and coil tension considering strip mm obtained by experiment. Finite element method for thermal deformation of cold rolled coil has been performed to investigate the effects of the strip crown, the coil tension and temperature. From these analyses, it is found that the axial inhomogeneity of thermal deformation is increased as the strip crown, compressive pressure, and temperature drop in cold coiled strip increase.

• Journal of Korean Neurosurgical Society
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• v.42 no.1
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• pp.59-63
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• 2007

Operative clipping after previous endovascular coiling in an aneurysm is a different problem from primary clipping procedure for neurosurgeons. With the increasing use of coil embolization, neurosurgeons will more and more face the similar situation. We report surgical clipping cases of intracranial aneurysm regrown after endovascular coiling. Three patients with a history of subarachnoid hemorrhage due to ruptured aneurysm underwent endovascular treatment (EVT) with detachable coils. The aneurysms were in the posterior communicating artery, the middle cerebral artery and distal anterior cerebral artery (DACA). Two near-total occlusions and one partial occlusion were achieved by EVT. After several months, angiographic follow-up revealed regrowth of the aneurysm requiring surgical clipping. Here, we report three cases in which surgical clipping was more difficult than a usual clipping procedure performed several months after EVT, because of adhesion and coil bulging into the aneurysmal neck. The difficulty of the treatment of the residual aneurysm after coiling is discussed, as are the surgical complications and limitations of clipping.

• Journal of Korean Neurosurgical Society
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• v.48 no.1
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• pp.88-90
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• 2010

Retroperitoneal hematoma (RH) due to radiologic intervention for an intracranial lesion is relatively rare, difficult to diagnose, and can be lifethreatening. We report a case of RH that developed in a patient on anticoagulant therapy following endovascular coiling of a ruptured anterior communicating artery (AcoA) aneurysm. An 82-year-old man presented with a 12-day history of headache. Computed tomography (CT) on admission demonstrated slight subarachnoid hemorrhage, and left carotid angiography revealed an AcoA aneurysm. The next day, the aneurysm was occluded with coils via the femoral approach under general anesthesia. The patient received a bolus of 5,000 units of heparin immediately following the procedure, and an infusion rate of 10,000 units/day was initiated. The patient gradually became hypotensive 25 hours after coiling. Abdominal CT showed a huge, high-density soft-tissue mass filling the right side of the retroperitoneum space. The patient eventually died of multiple organ failure five days after coiling. RH after interventional radiology for neurological disease is relatively rare and can be difficult to diagnose if consciousness is disturbed. This case demonstrates the importance of performing routine physical examinations, sequentially measuring the hematocrit and closely monitoring systemic blood pressures following interventional radiologic procedures in patients with abnormal mental status.

• Proceedings of the KSME Conference
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• 2000.11a
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• pp.837-842
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• 2000

In the coiling process of helical steam generator tubes of integral reactor SMART, a considerable amount of spring back, which induces dimensional inaccuracy and difficulty in fabrication, has been arised. In this research, an analytical model was derived to evaluate the amount of the spring back for steam generator tubes. The model was developed on the basis of beam theory and elastic-perfectly plastic material property. This model was extended to consider the effect of plastic hardening and the effect of the tensile force on the spring back phenomena. Parametric studies were performed for various design variables of steam generator tubes in order to minimize the spring back in the design stage. A sensitivity analysis has shown that the low yield strength, the high elastic modulus, the small helix diameter, and the large tube diameter result in a small amount of the spring back. The amount of the spring back can be controlled by the selection of adequate design values in the basic design stage and reduced to an allowable limit by the application of the tensile force to the tube during the coiling process.

• Korean Journal of Metals and Materials
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• v.48 no.3
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• pp.187-193
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• 2010

The solute carbon content in ferrite is one of the important factors to obtain good formability in low carbon steels. Although most of the carbons are consumed by the formation of grain boundary cementite during coiling after hot-rolling, the carbon content after coiling is normally observed much more than that of equilibrium. In this study, a classical nucleation and growth model is used to simulate the precipitation kinetics of the grain boundary cementite from coiling temperature (CT) to room temperature (RT). The predicted precipitation behaviors depending on the initial carbon content and the cooling rate are compared with the reported. As a result, the lateral growth of thickening of cementite is a major factor for the sluggish reaction of grain boundary cementite. The reduction of solute carbon content after coiling is divided into three regions: a) increase due to no cementite precipitation, b) decrease due to the fast length-wise growth of cementite, c) increase due to the slow thickness-wise growth of cementite.

• Journal of Korean Neurosurgical Society
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• v.57 no.6
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• pp.455-459
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• 2015

Objective : A cost comparison of the surgical clipping and endovascular coiling of unruptured intracranial aneurysms (UIAs), and the identification of the principal cost determinants of these treatments. Methods : This study conducted a retrospective review of data from a series of patients who underwent surgical clipping or endovascular coiling of UIAs between January 2011 and May 2014. The medical records, radiological data, and hospital cost data were all examined. Results : When comparing the total hospital costs for surgical clipping of a single UIA (n=188) and endovascular coiling of a single UIA (n=188), surgical treatment [$mean{\pm}$standard deviation (SD) : \$8,280,000{\pm}1,490,000$] resulted in significantly lower total hospital costs than endovascular treatment ($mean{\pm}SD$ : \$11,700,000{\pm}3,050,000$, p<0.001). In a multi regression analysis, the factors significantly associated with the total hospital costs for endovascular treatment were the aneurysm diameter (p<0.001) and patient age (p=0.014). For the endovascular group, a Pearson correlation analysis revealed a strong positive correlation (r=0.77) between the aneurysm diameter and the total hospital costs, while a simple linear regression provided the equation, y (\)=6,658,630+855,250x (mm), where y represents the total hospital costs and x is the aneurysm diameter. Conclusion : In South Korea, the total hospital costs for the surgical clipping of UIAs were found to be lower than those for endovascular coiling when the surgical results were favorable without significant complications. Plus, a strong positive correlation was noted between an increase in the aneurysm diameter and a dramatic increase in the costs of endovascular coiling.