• Journal of Korean Neurosurgical Society
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• v.48 no.3
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• pp.207-212
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• 2010

Objective : To assess the feasibility, safety, and effectiveness of the balloon-assisted technique with HyperForm balloon in the endovascular treatment of wide-necked intracranial aneurysms. Methods : A total of 34 patients with 34 wide-necked intracranial aneurysms were treated with endovascular coil embolization using balloon-assisted technique with Hyperform balloon. Twenty-nine aneurysms (85.3%) were located in the anterior circulation. The group of patients was comprised of 16 men and 18 women, aged 33 to 72 years (mean : 60.6 years). The size of aneurysms was in the range of 2.0 to 22.0 mm (mean 5.5 mm) and one of neck was 2.0 to 11.9 mm (mean 3.8 mm). The dome to neck ratio was ranged from 0.83 to 1.43 (1.15). Sixteen patients were treated for unruptured aneurysms and the remaining 18 presented with a subarachnoid hemorrhage. Results : In the 34 aneurysms treated by the remodeling technique with HyperForm balloon, immediate angiographic results consisted of total occlusion in 31 cases (91.2%) and partial occlusion in three cases (8.8%). There were five procedure-related complications (14.7%), including two coil protrusions and three thromboembolisms; Except one patient, all were successfully resolved without permanent neurologic deficit. No new bleeding occurred during the follow-up. Twenty patients (59%) underwent angiographic follow-up from 2 to 33 months (mean 9.2 months) after treatment. Focal recanalization with coil compaction of the neck portion was observed in 5 cases (25%). Only one case showed major recanalization and underwent stent-assisted coil embolization. Conclusion : The balloon-assisted technique with Hyperform balloon is a feasible, safe, and effective endovascular treatment of wide-necked cerebral aneurysms.

• Journal of Korean Neurosurgical Society
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• v.64 no.3
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• pp.427-436
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• 2021

Objective : The fate of partially thrombosed intracranial aneurysms (PTIAs) is not well known after endovascular treatment. The authors aimed to analyze the treatment outcomes of PTIAs. Methods : We retrospectively reviewed the medical records of 27 PTIAs treated with endovascular intervention between January 1999 and March 2018. Twenty-one aneurysms were treated with intraluminal embolization (ILE), and six were treated with parent artery occlusion (PAO) with or without bypass surgery. Radiological results, clinical outcomes and risk factors for major recurrence were assessed. Results : The initial clinical status was similar in both groups; however, the last status was better in the ILE group than in the PAO group (p=0.049). Neurological deterioration resulted from mass effect in one case and rupture in one after ILE, and mass effect in two and perforator infarction in one after PAO. Twenty cases (94.2%) in the ILE group initially achieved complete occlusion or residual neck status. However, 13 cases (61.9%) showed major recurrence, the major causes of which included coil migration or compaction. Seven cases (33.3%) ultimately achieved residual sac status after repeat treatment. In the PAO group, all initially showed complete occlusion or a residual neck, and just one case ultimately had a residual sac. Two cases showed major recurrence, the cause of which was incomplete PAO. Aneurysm wall calcification was the only significantly protective factor against major recurrence (odds ratio, 36.12; 95% confidence interval, 1.85 to 705.18; p=0.018). Conclusion : Complete PAO of PTIAs is the best option if treatment-related complications can be minimized. Simple fluoroscopy is a useful imaging modality because of the recurrence pattern.

• Journal of Korean Neurosurgical Society
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• v.43 no.1
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• pp.21-25
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• 2008

Objective : Both endovascular coil embolization and microsurgical clipping are now firmly established as treatment options for the management of cerebral aneurysms. Moreover, they are sometimes used as complementary approaches each other. This study retrospectively analyzed our experience with endovascular and microsurgical procedures as complementary approaches in treating a single aneurysm. Methods : Nineteen patients with intracranial aneurysm were managed with both endovascular and microsurgical treatments. All of the aneurysms were located in the anterior circulation. Eighteen patients presented with SAH, and 14 aneurysms had diameters of less than 10 mm, and five had diameters of 10-25 mm. Results : Thirteen of the 19 patients were initially treated with endovascular coil embolization, followed by microsurgical management. Of the 13 patients, 9 patients had intraprocedural complications during coil embolization (intraprocedural rupture, coil protrusion, coil migration), rebleeding with regrowth of aneurysm in two patients, residual sac in one patient, and coil compaction in one patient. Six patients who had undergone microsurgical clipping were followed by coil embolization because of a residual aneurysm sac in four patients, and regrowth in two patients. Conclusion : In intracranial aneurysms involving procedural endovascular complications or incomplete coil embolization and failed microsurgical clipping, because of anatomical and/or technical difficulties, the combined and complementary therapy with endovascular coiling and microsurgical clipping are valuable in providing the best outcome.

• Journal of Korea Foundry Society
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• v.19 no.6
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• pp.456-465
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• 1999

The overall objective of this study is to investigate the effect of Ag addition on the mechanical properties and microstructure of rapid solidified 7000 Al series alloys. Al-Zn-Mg-Cu alloys with small amounts of Ag was fabricated into the powder by gas atomization. The powder was extruded after the cold compaction and degassing and then followed by T6 heat treatment. Microstructure observation, phase analysis, room and high temperature tensile test and hardness test were pursued. The tensile strength and hardness of Ag-added alloy after heat treatment was increased with increasing Ag contents. However, the elongation of extruded alloys was not increased as much as to be expected. The reason of this result seems to be related to $the{\Omega}$ phase, which contribute to the high temperature strength stability of Al-Cu-Zn alloys through the formation of eutectoid with Ag addition.

• Magazine of the Korean Society of Agricultural Engineers
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• v.44 no.3
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• pp.122-135
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• 2002

Although fly ash possesses viable engineering properties, an overwhelming majority of fly ash from coal combustion is still placed in storage or disposal sites. Similarly, sludges generated from various water treatment operations are predominantly subjected to the fate of land disposal. To prepare sludges fur land disposal typically requires time consuming dewatering schemes, which can become extremely difficult to execute depending upon the composition of the sludge and its affinity for water. This study was undertaken to reuse fly ash and sludge as construction materials. This paper includes geotechnical properties of fly ash and fly ash-lime-sludge mixture and results of compaction test, UU-test, falling head test, leaching test and CBR test. The effect on mixing fly ash with sludge and lime and the effect of curing period and the results are obtained from this test.

• Geomechanics and Engineering
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• v.12 no.1
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• pp.71-83
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• 2017

Collapsible soil presents a porous unsaturated structure, its sudden settlement after humidification, without supplementary charge, can be of a big nuisance for the foundations and therefore for the constructions built on it. To improve its structure and limit its instability, samples of laboratory reconstituted soil, with different percentages of water contents and compacted at different compaction energies, were treated with glass-fiber. The study of the mechanical behavior was performed by oedometer tests. The microstructure was explored by the Scanning Electron Microscope (SEM). The results obtained show clearly the efficiency of the treatment with glass fiber on reducing the collapsibility of such soil.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.2
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• pp.28-34
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• 1998

Powder metallurgy processes are able to form Net-Shape products and have been widely used in the production of automobile parts to improve its productivity. However, because of pores in powder products, the toughness of powder products are generally poor. Therefore, forged products are used in parts which suffer severe fatigue loads. In this paper, the choice of powder materials and production processes such as mixing, compaction, sintering, heat treatment to produce automobile spline hub are studied. Three type of materials are selected and processed and its microstructure and properties are investigated by tensile test, compression ring test, and impact test. Materials and processing methods are selected from the results. Finally, experimental spline hubs are manufactured by selected processes from selected powders and proved by torsional durability test.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 1996.12a
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• pp.97-101
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• 1996

Municipal and sanitary landfills can pose environmental problems due to leachate, landfill gas md unstable geotechnical properties. Most governmental bodies delay the correction of landfill problems or landfill replacement until a crises stage is reached. The replacement of a landfill is often made difficult due to costly regulatory controls, public opposition to siting and the high cost of closure for the previous landfill unit. Solutions to extending landfill life and capacity Involve waste minimization by recycling, refuse compaction and waste-to-energy incineration. Incineration can reduce the volume of refuse by 50-95%. The largest installed bases of municipal waste Incinerators are located in Japan and the U.S. The volume of waste contained in a landfill can be estimated by load count tabulations, weight-and-volume measurements or a material balance analysis based on the trash profile of user categories. for an existing landfill, core samples may be collected and analyzed for use in a material balance analysis. Newly generated refuse contains approximately 50% of the heating value of coal. However, landfill properties vary significantly due to the waste profile of the contributors and biodegradation due to time and weathering. The volume of the Nanji-do landfill

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.738-739
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• 2006

This paper will describe a powder and processing method that facilitates single press-single sintered densities approaching $7.5g/cm^3$. At this sintered density, mechanical properties of the powder metal (P/M) component are significantly improved over current P/M technologies and begin to approach the performance of wrought steels. High performance gears have the added requirement of rolling contact fatigue durability that is dependent upon localized density and thermal processing. Combining high density processing of engineered P/M materials with selective surface densification enables powder metal components to achieve rolling contact fatigue durability and mechanical property performance that satisfy the performance requirements of many high strength automotive transmission gears. Data will be presented that document P/M part performance in comparison to conventional wrought steel grades.

• Journal of Powder Materials
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• v.7 no.3
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• pp.123-130
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• 2000

The simulated DUPIC fuel provides a convenient way to investigate fuel properties and behaviours such as thermal conductivity, thermal expansion, fission gas release, leaching and so on. Several pellets simulating the composition and microstructure of the DUPIC fuel were fabricated from resintering powder through the OREOX process of the simulated spent fuel pellets, which were prepared from the mixture of stable forms of constituent nuclides. This study describes the powder treatment, OREOX, compaction and sintering to fabricate simulated DUPIC fuel using the simulated spent fuel. The homogeneity of additives in the powder was observed after attrition milling. The microstructure of the simulated spent fuel was in agreement with the previous studies. The densities and the grain size of simulated DUPIC fuel was pellets are higher than those of simulated spent fuel pellets. Small metallic precipitates and oxide precipitates were observed on matrix grain boundaries.