• Journal of Digital Convergence
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• v.15 no.9
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• pp.321-333
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• 2017

This study was a qualitative study using Colaizzi's phenomenological study method to understand the experience of reconstructing life through hemodialysis in chronic renal failure patients and to clarify the meaning of their vivid experience. The participants were eight chronic renal failure patients receiving hemodialysis. Data were collected through individual in - depth interviews with participants. The five categories that were found in the study were 'The beginning of unexpected difficulties', 'Burden of survival brought on by hemodialysis', 'The driving force of recovery', 'Choices and concentration of today in order', ' Every day life which must be woven sincerely'. The results of this study will help clinicians better understand the physical and mental suffering experienced by patients with chronic renal failure receiving hemodialysis and how they are constantly trying to adapt to a changed lifestyle. Also it might provide basic data for the development of efficient nursing intervention for the health management of hemodialysis patients.

• Proceedings of the KIEE Conference
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• 1998.07c
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• pp.1166-1169
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• 1998

The Load characteristic of electric railway requires the power demand of the high capacity which amplitude is spacial-temporally fluctuated due to frequent starting and stopping with large tractive force. The conventional electric railway mainly consists of the resistance controlled and the thyristor controlled locomotives, are compensated for their bad characteristics of the power factor$(70\sim80%)$ with installation of another capacitor improving power factor at the substation. Since 1994, VVVF train car with good characteristics of power factor(100%) have been introduced and operated in Kwa-Chon Line. From the present technical tendency, it is judged that introduction of the locomotive with various controlled methods is necessary. The protective equipments installed at the substation are complicated and various aspects to detect faults and reduce their extension, so the universal countermeasures are required. Specially in the case of the fault occurrence it is difficult to calculate the fault location because of the change in the contactline constant according to modifying the characteristics of the contactline (the dualized catenary wire and extension, etc), so much time is required for the detection of fault location. In BT-fed method distance-relays and fault-locators are not installed, we have so many difficulties in the quick accident recovery.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.11
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• pp.1595-1602
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• 2010

A disposable drug infuser is used to provide drugs to patients who are not hospitalized; in this infuser, an elastic recovery force is exerted by a diaphragm made of a rubber-like materialsuch that a constant amount of drugs is provided to a patient. The drug infuser has to control the speed and amount of drugs to be released, as well as the overall duration for which they are to be administered. However, in a drug infuser with an elastic diaphragm, the infusion pressure depends on the amount of drug remaining within the infuser, and the amount of drug infused gradually decreases as the amount remaining in the infuser decreases. In this study, a finite element procedure involving the application of the fluid-structure interaction technique was developed and the performance of the elastic type disposable drug infuser was analyzed. The optimum design for ensuring that the infusion pressure remains constant throughout the duration of usage, including during infusion and discharge, was determined by this procedure.

• Bulletin of the Korean Chemical Society
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• v.30 no.11
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• pp.2589-2594
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• 2009

Aging phenomena of plasma polymer films were studied by using the surface analysis techniques of contact angle measurement, X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (TOFSIMS), and atomic force microscopy (AFM). The polymer films were grown on an aluminum substrate by using a plasma polymerization method from a gas mixture of acetylene and helium, and the films were subsequently modified to have a hydrophilic surface by oxygen plasma treatment. Aging of the polymer films was examined by exposing the samples to water and air environments. The aging process increased the hydrophobicity of the surface, as revealed by an increase in the advancing contact angle of water. XPS analysis showed that the population of oxygen-containing polar groups increased due to the uptake of oxygen during the aging, whereas TOF-SIMS analysis revealed a decrease in the polar group population in the uppermost surface layer. The results suggest that the change in surface property from hydrophilic to hydrophobic nature results from the restructuring of polymer chains near the surface, rather than compositional change of the surface. Oxidative degradation may enhance the mobility and the restructuring process of polymer chains.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.713-721
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• 2004

Variable air intake and variable exhaust nozzle of hypersonic engines are designed and tested in this study. Dimensions for variable geometry air intake, ram combustor and variable geometry exhaust nozzle are defined based on the requirements of a pre-cooled turbojet engine. Hypersonic Ramjet Engine is designed as a scaled test bed for each component. Actuation forces of moving parts for variable intake and variable nozzle are reduced by balancing the other force in the opposite direction. A demonstrator engine which includes variable intake and variable nozzle is designed and the components are fabricated. Composite material with silicone carbide is applied for high temperature parts under oxidation environment such as leading edge of the variable intake and combustor liner. Internal cooling structure is adopted for both moving and static parts of the variable nozzle. Pressure recovery and mass capture ratio of the variable intake at Mach 5 is obtained by a hypersonic wind tunnel test. Flow characteristics of the variable nozzle are obtained by a low temperature flow test. Wall temperature and heat flux of the nozzle at Mach 3 is obtained by a firing test. As results, the intake and the nozzle are proved to be used at designed pressure and temperature environment.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.8 s.185
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• pp.171-177
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• 2006

This study was performed as a part of the research on the development of a maskless and electroless process for fabricating metal micro/nanostructures by using a nanoindenter and an electroless deposition technique. $2-{\mu}m$-deep indentation tests on Ni and Cu samples were performed. The elastic recovery of the Ni and Cu was 9.30% and 9.53% of the maximum penetration depth, respectively. The hardness and the elastic modulus were 1.56 GPa and 120 GPa for Ni and 1.51 GPa and 104 GPa for Cu. The effect of single-point diamond machining conditions such as the Berkovich tip orientation (0, 45, and $90^{\circ}$ ) and the normal load (0.1, 0.3, 0.5, 1, 3, and 5 mN), on both the deformation behavior and the morphology of cutting traces (such as width and depth) was investigated by constant-load scratch tests. The tip orientation had a significant influence on the coefficient of friction, which varied from 0.52-0.66 for Ni and from 0.46- 0.61 for Cu. The crisscross-pattern sample showed that the tip orientation strongly affects the surface quality of the machined are a during scratching. A selective deposition of Cu at the pit-like defect on a p-type Si(111) surface was also investigated. Preferential deposition of the Cu occurred at the surface defect sites of silicon wafers, indicating that those defect sites act as active sites for the deposition reaction. The shape of the Cu-deposited area was almost the same as that of the residual stress field.

• Journal of Korean Neurosurgical Society
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• v.29 no.3
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• pp.353-359
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• 2000

Objective : The fracture on the frontal bone in head-injured patients may be commonly encountered in the clinical situations. Biomechanical studies demonstrate that the anterior wall of the frontal sinus is intermediate in its ability to resist fracture on direct impact. If the frontal sinus is large and the anterior table is able to disperse the force of the impact over a greater area, the posterior table and intracranial contents usually can be spared. We analyzed the clinical features of the patients who presented with frontal skull fracture due to frontal blows. Patients and Methods : From January, 1992 to December, 1997, 172 patients with frontal skull fracture were selected among 1911 patients with head injury who were admitted to department of neurosurgery. Clinical records and radiological studies of all patients were reviewed and evaluated retrospectively. Results : The neurobehavioral changes was seen in 34 cases(19.8%) and showed statistical significances in case of facial bone fractures, acute subdural hematoma(SDH), and positive frontal lobe releasing sign(p<0.05). The good glasgow outcome score group(GOS, good recovery & moderate disability) at discharge was revealed in 77.3% of total patient population. The poor GOS group(severe disability & vegetative state & death) at discharge was revealed in 22.7%. The poor GOS group at discharge have statistical significances with acute epidural hematoma(EDH), traumatic intraventricular hemorrhage(t-IVH), traumatic intracranial lesion, poor initial glasgow coma scale(GCS) scores & Revised Trauma Score(RTS)(p<0.05). Conclusion : Because of their anatomical relationships and neurobehavioral patterns due to vulnerability of the frontal lobe, the frontal injury should be considered as complicated facial injuries. Therefore, these patients are more likely to have a cosmetic or neuropsychiatric problems.

• Korean Journal of Metals and Materials
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• v.56 no.11
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• pp.779-786
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• 2018

There have been previous attempts to observe the occurrence of dynamic ferritic transformation at temperatures even above $Ae_3$ in a low-carbon steel, and not only in steels, but recently also in titanium alloys. In this study, a new approach is proposed that involves treating true stress-true strain curves in uniaxial compression tests at various temperatures, and different strain rates in 0.1C-6Ni steel, which is a model alloy used to decelerate the kinetics of ferrite transformation from austenite. The initial flow stress up to peak stress was used to analyze the change in dynamic softening phenomena, such as dynamic recovery, dynamic recrystallization, and dynamic transformation. It is worth mentioning that for predicting the occurrence of dynamic transformation, flow stress before reaching peak stress is much more sensitive to the change in the dynamic softening rate due to dynamic transformation, compared to peak stress. It was found that the occurrence of dynamic ferritic transformation could be successfully obtained even at temperatures above $Ae_3$ once the deformation condition was satisfied. This deformation condition is a function of both the strain rate and the deformation temperature, which can be described as the Zener - Hollomon parameter. In addition, the driving force of dynamic ferritic transformation might be much less than that of the dynamic recrystallization of austenite at a given deformation condition. By applying this technique, it is possible to predict the occurrence of dynamic transformation more sensitively compared with the previous analysis method using peak stress during deformation.

• Neurospine
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• v.15 no.4
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• pp.362-367
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• 2018

Objective: To assess the efficacy of cervical open-door laminoplasty by hydroxyapatite implant insertion between the lamina and the lateral mass without suturing. Methods: All patients who underwent cervical open-door laminoplasty with C2/C7 undermining and insertion of hydroxyapatite implants from C3 to C6 were retrospectively evaluated for surgical time and neurological outcomes according to the Japanese Orthopaedic Association (JOA) score. To assess the alignment of the cervical spine and postoperative cervical pain, the C2-7 angle and a visual analogue scale score were used, respectively. Results: The population consisted of 102 women and 222 men ranging in age from 32 to 90 years. The average surgical time was 86 minutes. Fourteen of 1,296 hydroxyapatite implants were kept in place with sutures due to a weak restoration force of the hinge during surgery. No hydroxyapatite implant dislocation was detected on cervical computed tomography at 1 year after surgery. The average JOA score was $10.2{\pm}2.5$ before surgery and $14.6{\pm}2.8$ at 1 year after surgery. The average recovery rate was 61.8%. The average C2-7 angle at the neutral position was $7.1^{\circ}{\pm}6.2^{\circ}$ before surgery and $6.5^{\circ}{\pm}6.3^{\circ}$ at 1 year after surgery. Conclusion: This method enabled us to achieve minimal exposure of the lateral mass, prevention of lateral mass injury and dural injury, and a shorter surgical time while maintaining acceptable surgical outcomes. The idea that firm suture fixation is needed to prevent spacer deviation during cervical open-door laminoplasty may need to be revisited.

• Journal of the Earthquake Engineering Society of Korea
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• v.23 no.3
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• pp.159-167
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• 2019

2016 Gyeongju and 2017 Pohang earthquakes led Koreans to acknowledge that the Korean peninsula is not an earthquake-free zone anymore. Among various buildings crucial to after-shock recovery, general hospital buildings, especially existing old ones, are very significant so seismic retrofitting of those must be an important issue. Self-centering energy dissipative(SCED) brace is one of retrofitting methods, which consists of tendon with restoring force and friction device capable of dissipating seismic energy. The strength of the SCED brace is that the tendon forces a structure to go back to the original position, which means residual drift can be negligible. The residual drift is a very important parameter to determine usableness of general hospitals after shock. To the contrary, buckling-restrained braces(BRB) are also a very effective way to retrofit because they can resist both compressive and tensile, but residual drift may exist when the steel core yields. On this background, the seismic retrofitting effect of general hospitals reinforced with SCED braces was investigated and compared to that of the BRD in this study. As a result, although the floor acceleration cannot be reduced, the story drift and residual drift, and the shear demand of walls significantly decreased. Consequently, seismic retrofitting by SCED braces are very effective for domestic low-rise general hospitals.