• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.11a
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• pp.182-183
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• 2008

In this study, rotor dynamic analysis have been conducted using three-dimensional solid model. Analysis object has smaller size and higher speed than any general CNC spindle. It is important to consider the real supporting conditions and external forces for whirl behavior analysis. As a results, the bearing stiffness is higher, whirl motion is less than before.

• Journal of the Korean Society of Hazard Mitigation
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• v.1 no.1 s.1
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• pp.81-90
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• 2001

This paper presents the results of the parametric study on the longitudinal behavior of 2-span continuous railway bridge. To perform the main objective of this paper, the effects of pier shaft stiffness, pier height, the size of pier foundation, and the bearing stiffness on the longitudinal behavior of the bridges are studied. Within the limits of this study, the research result has revealed that the variation of the fixed pier is more effective than that of the moved pier. In addition, the control of the hearing stiffness is much less expensive than that of any other parameters.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.13 no.10
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• pp.785-790
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• 2003

This paper presents an approach to optimally design the air-hearing surface (ABS) of the optical flying head for near-field recording technology (NFR) NFR is an optical recording technology using very small beam spot size by overcoming the limit of beam diffraction. One of the most important problems in NFR Is a head disk interface (HDI) issue over the recording band during the operation. A multi-criteria optimization problem is formulated to enhance the flying performances over the entire recording band during the steady state. The optimal solution of the slider, whose target flying height is 50 nm, is automatically obtained. The flying height during the steady state operation becomes closer to the target values than those for the Initial one. The pitch and roll angles are also kept within suitable ranges over the recording band. Especially. all of the all-hearing stiffness are drastically increased by the optimized geometry of the air hearing surface.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.05a
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• pp.1021-1026
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• 2000

The thermal characteristics of high-speed air spindle system with built-in motor are studied. Experiment and finite element method analysis obtain temperature rise and temperature distribution of housing. For the analysis three-dimensional model is built and temperature rise and distribution in thermal steady state are computed for each rotational frequency. Generally. It is said that the heat generation of air bearing is negligible. But it is certain that the heat generation of air bearing can not be negligible especially in high-speed conditions Frequency response test for air spindle system is executed. In case that the heat generation of air spindle system is high, natural frequency of the system becomes lower when it reaches thermal steady-state and it means that the stiffness of air hearing becomes smaller due to the change of bearing clearance. It is shown that the temperature rise of all spindle system causes thermal expansion md induces the variation of hearing clearance. In consequence the st illness of air bearing becomes smaller.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.2
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• pp.116-123
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• 2002

Applying a general coupled lateral and torsional vibration finite element model of gear pair element, this paper intends to look into in detail the coupled lateral and torsional vibration characteristics of a turbo-chiller rotor bearing system, having a bull-pinion speed increasing gear. Investigations have been carried out systematically by comparing the uncoupled and coupled natural frequencies and their mode shapes upon varying the gear mesh stiffness with considerations on rotating speeds, and also by comparing the strain energies of lateral and torsional vibration modes. Results hale shown that some modes may hale the coupled lateral and torsional mode characteristics as the gear mesh stiffness Increases over a certain value, and moreover that their associated dominant modes may be different from their initial modes, j.e., a certain dominant mode may change from an initial torsional one to a lateral one or from an initial lateral one to a torsional one.

• Journal of Korean Academy of Nursing
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• v.26 no.4
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• pp.903-916
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• 1996

The purpose of this study was to discover practical health problems which hemodialysis clients experienced so as to present basic data for development of a health assessment tool. The research subjects were 70 clients receiving hemodialysis in Seoul and Inchon from Mar. 1996 to Sep. 1996. Data were collected by researcher's informal indepth interview and nurses' open ended question. Content analysis was applied to collect similar contents and common experiences in order to derivate concepts and categories for better understanding of hemodialysis clients' experiences. As a result, 9 categories derivated to identify the health problems of clients receiving hemodialysis were as follows : 1) They experienced 'the decreased digestive function' which contained the changed appetite, nausea, vomiting, constipation and diarrhea. 2) They experienced 'the decreased respiratory and circulatory function' which contained dyspnea, changed blood pressure, tingling sensation and the fear of aggrevated vascular condition. 3) They experienced 'the aggrevated oral condition' which contained dry mouth and destruction of teeth and their soft tissue. 4) They experienced 'the decreased sensory function' which contained visual disturbances, sensation difficulty, and hearing loss. 5) They experienced 'the aggrevated skin condition' which contained dark brown skin color, dry skin (and hyperpigmentatic freckle, seborrheric keratosis, scale), itching sense, and alopethia. 6) They experienced 'the decreased urinary reproductive function' which contained anuria or oliguria, dysmenorrhea, sterility and decreased libido. 7) They experienced 'the restricted activity' which contained decreased activity, muscle cramp and stiffness of joint. 8) They experienced 'the changed mental status' which contained memory disturbance, decreased cognition, disorientation, neurosis and psychosis. 9) They experienced 'the aggrevated general condition' which contained kyphosis, weight loss, fatigue, sleep disturbance, bleeding tendency, inflammation, generalized edema and foul oder of uremia.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.523-530
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• 2006

A rotordynamic analysis was performed with a dry vacuum pump, which is a major equipment in modern semiconductor and LCD manufacturing processes. The system is composed of screw rotors, lobes picking air, helical gears, driving motor, and support rolling element hearings of rotors and motor. The driving motor-screw rotor system has a rated speed of 6,300rpm, and was modeled utilizing a rotordynamic FE method for analysis, which was verified through the results of its 3-D finite element model. As loadings on the bearings due to the gear action were significant in the system considered, each resultant bearing load was calculated determinately and indeterminately by considering the generalized forces of the gear action as veil as the rotor itself. Each resultant hearing loading was used in calculating each stiffness of rolling element bearings. Design goals are to achieve wide separation margins of critical speeds and favorable unbalance responses of the rotor in the operating range. Then, a complex rotordynamic analysis of the system was carried out to evaluate its forward synchronous critical speeds, whirl natural frequencies and mode shapes, and unbalance responses under various unbalance locations. Results show that the entire system is well designed in the operating range. In addition, the procedure of rotordynamic analysis for dry vacuum pump rotor-bearing system was proposed and established.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.8
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• pp.4567-4570
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• 2013

Background: Nasopharyngeal carcinoma (NPC) is the commonest radiocurable cancer in Malaysia. This study aimed to determine the treatment outcomes and late effects of radiotherapy for NPC patients treated in University Malaya Medical Centre (UMMC). Materials and Methods: All newly diagnosed patients with NPC referred for treatment to the Oncology unit at UMMC from 2004-2008 were retrospectively analyzed. Treatment outcomes were 5 years overall survival (OS), disease free survival (DFS), cause-specific survival (CSS), locoregional control (LRC) and radiotherapy-related late effects. The Kaplan-Meier method was used for survival analysis and differences in survival according to AJCC stage was compared using the log-rank test. Results: A total of 176 patients with newly diagnosed NPC were treated in UMMC during this period. Late presentation was common, with 33.5% presenting with T3-4 disease, 84.7% with N1-3 disease and 75.6% with AJCC stage 3-4 disease. Radical RT was given to 162 patients with 22.7% having RT alone and 69.3% having CCRT. The stipulated OTT was 7 weeks and 72.2% managed to complete their RT within this time period. Neoadjuvant chemotherapy was given to 14.8% while adjuvant chemotherapy was administered to 16.5%. The 5 years OS was 51.6% with a median follow up of 58 months. The 5 years OS according to stage were 81.8% for stage I, 77.9% for stage II, 47.4% for stage III and 25.9% for stage IV. The 5 years overall CSS, DFS and LRC were 54.4%, 48.4% and 70.6%, respectively. RT related late effects were documented in 80.2%. The commonest was xerostomia (66.7%). Other documented late effects were hearing deficit (17.3%), visual deficit (3.1%), neck stiffness (3.1%), dysphagia (3.4%), cranial nerve palsy (2.5%), pneumonitis (0.6%) and hypothyroidism (1.2%). Conclusions: The 5 years OS and LRC in this study are low compared to the latest studies especially those utilizing IMRT. Implementation of IMRT for NPC treatment should be strongly encouraged.

• Pediatric Infection and Vaccine
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• v.24 no.1
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• pp.65-70
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• 2017

Cytomegalovirus (CMV) infection is one of the most common congenital infections. The first case of discordant congenital CMV infection in twins occurred in Korea. A 31-year-old woman became pregnant with twins (dichorionic-diamniotic). An elective caesarean section was performed at 37 weeks. The first baby was male, weighing 2,410 g with an Apgar score of 8/9. The second baby was female, weighing 1,380 g with an Apgar score of 5/8. She had experienced intrauterine growth retardation, and presented with microcephaly, micrognathia, and joint stiffness. During the work-up for discordant twins, the second baby's serum test was positive for CMV immunoglobulin M. Her urine, blood, and cerebrospinal fluid (CSF) were CMV polymerase chain reaction positive. The first baby's CMV tests were negative. Ophthalmologic exam and audiometry performed on the second baby showed CMV retinitis and bilateral sensorineural hearing loss. She was treated with intravenous ganciclovir. Currently, she is bed-ridden and has significant developmental delay. Although the causes of discordant congenital CMV infection in twins are unclear, this case shows that discordant congenital CMV infection should be considered in twins with significant differences in intrauterine growth or clinical symptoms after birth.