• Journal of Biomedical Engineering Research
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• v.41 no.5
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• pp.179-184
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• 2020

Purpose: The purpose of this study was to evaluate the effect according to the NEX, VENC, targeted cardiac phases on the velocity measurement of 4D phase-contrast MRI. Materials and Methods: The abdominal aortic phantom was made to experiment. The working fluid was mixed with water and glycerin to mimic the density and viscosity of human blood. The inlet velocity was Reynolds number 2000. The experimental conditions were NEX 1 and 4, VENC 102 cm/s and 200 cm/s, and 10 and 15 targeted cardiac phases, respectively. The average flow rate, average velocity, maximum velocity, and cross-section area were measured. Results: As a result of the case-by-case comparison, the error rate was less than 5%. There was no significant difference (p > 0.05). Conclusion: It is expected that this result will be useful for acquiring blood flow information in clinical practice.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.610-614
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• 1996

Sealing of lubricat-air mixture in the high performance machining conte is one of most the important characteristics to carry out enhanced lubrication. High speed spindle requires non-contact type of sealing mechanism. Evaluating an optimum seal design to minimize leakage is concerned in the aspect of flow control. Effect of geometry and leakage path are evaluated according to variation of sealing geometry, Velocity, pressure, turbulence intensity of profile is calculated to fina more efficient geometry and variables. This offers a methodological way of enhancement seal design for high speed spindle. The working fluid is regarded as two phases that are mixed flow of oil phase and air phase. It is more reasonable to simulate an oil jet or oil mist type high speed spindle lubrication. Turbulence and compressible flow model are used to evaluate a flow characteristic, This paper arranges a geometry of mostly used non-contact type seal and analyzes leakage characteristics to minimize a leakage on the same sealing area.

• Journal of the Korea Society for Simulation
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• v.6 no.2
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• pp.1-14
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• 1997

The characteristics of the flow and energy conversion in OMACON liquid-metal MHD system are investigated. Numerical simulation of two-phase flow in the OMACON system without magnetic field was carried out by the Phoenics code and the energy conversion characteristics are studied in association with the fact that the mechanical energy loss at the nozzle of the OMACON system are to be converted into electrical energy. In this system, working fluid (gas) is injected through the mixer located at the bottom of the riser, and is mixed with hot liquid metal. Therefore in the riser two-phase flow is developed under the influence of the gravity. In this study, the interaction between the gas and liquid is considered by the use of IPSA(InterPhase Slip Algorithm) where standard drag coefficient has been used. It has been assumed that in the flow regime the liquid is continuous and the gas is dispersed. For the liquid and gas, the continuity equations, momentum equations and energy equations are solved respectively in association with void fraction in the flow field. In order to calculate the energy conversion efficiency, firstly the ratio of the mechanical energy loss of liquid metal flow at the nozzle to the input thermal energy is considered. Secondly flow pattern of liquid metal in the generator has been analyzed, and the characteristics of the conversion of the mechanical energy into the electrical energy has been investigated. For an representative case where Hartmann number is 540 and magnetic field is 0.35 T, the present analysis shows that the energy conversion efficiency is 0.653. This result is considered to be reasonable in comparison with published experimental results.

• Journal of Korean Academy of Nursing
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• v.28 no.1
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• pp.171-183
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• 1998

The purpose of this study was to identify the incidence of urinary incontinence in adult women and to identify factors related to life style and sexual intercourse that were related to incontinence. The sample consisted of 1,065 women living in Seoul or one of five provinces. Data for this study were collected from January 16 to June 23 using structured questionnaires. The Urinary Symptom Questionnaire developed by Jackson and a demographic questionnaire were used to collect the data. The data were analyzed using frequency, percentage with an SPSS/PC$^{+}$ program. The major finding are as follows : 1. The distribution of age of subjects was as follows : 20-29(10.1%), 20-39(17.8%), 40-49(27.3%). 50-59(22.3%), 60-69(12.9%), 70-79(6.1%). 80-89(2.8%), more than 90(0.6%). The frequency of normal delivery, 0(155%), 1-2(36.0%), 3-4(29.2%), 5-6(13.0%). more than 7(6.3%). The rate of subjects with menopause was 40.8%. 2. It was reported that 50.7% of the subjects experienced urinary incontinence with stress, mixed. and urgency incontinence being 49.8%, 43.4%, 6.8% respectively. 3. The lower urinary symptoms and incidence with urinary incontinence were as follows : Daily frequency. 22.3%, nocturia. 40.8%, urgency, 71.2%, bladder pain 47.8%, unexplainned incontinence, 32.4%, noctural incontinence, 16.1%, and frequency of incontinence, 37.7%. In term of quantity of incontinence, drop/pants damp, 29.5%, dribble/pants wet, 20.5%, flood or soaking through to outer clothing, 1.7%, and flood or running down legs or onto floor, 0.2%. 4. The symptoms related to sexual intercourse and incidence of urinary incontinence were as follows : dry vagina, 39.1%, sex life trouble, 10.8%, pain during sexual intercourse, 27.4%, and urine leakage during sexual intercourse. 8.8%. 5. Life style problems related to urinary incontinence were as follows : fluid intake restriction, 20.0%, affected daily task, 24.5%. avoidance of placess and situations, 35.0%, interference in physical activities, 30.6%, interference in relationships with other people. 19.0%. interference in relationships with husband/companion, 8.1%, and time after attack of urinary symptoms, 76.9%. In term of the feeling about the rest of their lifves the women reported : perfectly happy, 11.3%. pleased, 16.9%. mostly satisfied, 20.2%, mixed feelings, 21.0%, mostly dissatisfied, 21.0%, very unhappy 8.5%, and desperate. 1.0%. In conclusion. this study was a preliminary study to provide nursing practices guidelines for incontinence in adult women. Nurse working with adult women should develop and provide adequate care for these women.n.

• Radiation Oncology Journal
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• v.11 no.1
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• pp.79-82
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• 1993

From October 1989 to March 1992, ten patients diagnosed as primary central nervous system (CNS) lymphoma were treated with radiation therapy at Asan Medical Center. To obtain pathologic diagnosis, five patients had stereotactic biopsy and the others underwent craniotomy & tumor removal. According to the classification by International Working Formulation, seven of 10 patients showed diffuse large cell types and the remaining 3 had diffuse mixed cell types. Computed tomographic scans of the brain disclosed solitary (6 cases) or multiple (4 cases) intracranial lesions. All patients received 4000 cGy/20 fx to the whole brain followed by an additional 2000 cGy/10 fx boost to the primary lesion. Six patients with initial cerebrospinal fluid (CSF involvement were treated with whole brain irradiation and intrathecal Methotrexate (IT-MTX) chemotherapy. One of them received an additional spinal irradiation after 3 cycles of IT-MTX chemotherapy because of MTX induced arachnoiditis. One patient received 3 cycles of systemic chemotherapy prior to rodiation therapy and one received 5 cycles of salvage chemotherapy for recurrence. With a median follow up time of 8 months, all patients were followed from 7 to 26 months. Radiologically seven patients showed complete remission and the remaining three showed partial remission at one month after radiotherapy. The 1 and 2 year survival rate was $86{\%}\;and\;69{\%}$ respectively. Until now, two patients expired at 7 and 14 months. These patients developed extensive CSF seeding followed by local failure. Considering initial good response to radiation therapy and low incidence of extraneural dissemination in primary CNS lymphoma, we propose to increase total tumor dose to the primary lesion by hyperfractionated radiotherapy or stereotactic radiosurgery. For the patients with CSF involvement at diagnosis, we propose craniospinal irradiation with IT MTX chemotherapy.

• Journal of Korean Neurosurgical Society
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• v.30 no.5
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• pp.575-580
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• 2001

Purpose : In general, pineal region tumors are managed by using microsurgical approach or stereoctactic biopsy. However, in selected cases endoscopic approach to pineal lesions might prove to be as effective as microsurgery and less invasive. We report an alternative surgical strategy for managing certain patients with pineal neoplasms that allows treatment of the symptomatic hydrocephalus as well as tumor biopsy under direct vision in the same sitting. Materials and Methods : Twenty-two patients with pineal region tumors with associated hydrocephalus were treated in one session by endoscopic third ventriculostomy and endoscopic tumor biopsy at our institution from October 1996 to January 2000. All patients were retrospectively evaluated. Results : There was no operative mortality. There was one cause of significant bleeding during biopsy, but was controlled endoscopically, and the patient recovered completely without neurologic deficit resulting from intra-operative bleeding. The symptoms related to increased intracranial pressure(ICP) have resolved in all patients, and the need for a shunt is completely eliminated. Histological diagnosis was achieved in 21 of the 22 patients by this procedure. A biopsy was not obtained in one patient. Although this pineal region tumor was seen endoscopically, this could not be biopsied because of technical difficulties in working around an enlarged massa intermedia. The lesions included fourteen germinomas, three mixed germ cell tumors, and one each of the followings: pineocytoma, pineoblastoma, pineocytoma/pineoblastoma(intermediate type), meningioma, and low grade glioma. Five of the 22 patients subsequently underwent formal microsurgical tumor removal. Additional chemotherapy or radiotherapy could then be initiated according to the histological diagnosis. Conclusion : We consider that endoscopy affords a minimally invasive way of reaching three objectives by one-step surgery in the management of pineal region tumors with associated hydrocephalus : 1) cerebrospinal fluid(CSF) sample for analysis of tumour markers and cytology, 2) treatment of hydrocephalus by third ventriculostomy, and 3) several biopsy specimens can be obtained identifying tumors which will require further open surgery or adjuvant radiation and/or chemotherapy. However, complications and morbidities should be emphasized so as to be avoided with further technical experience.