• Nuclear Engineering and Technology
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• v.26 no.2
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• pp.179-189
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• 1994

A performance of reactor coolant pump in two-phase flow is examined using the pump geometric conditions and the performance of the pump in single-phase flow. Wall friction loss of the reactor coolant pump in single-phase flow is prdicted using the Truckenbrodt boundary layer theory, and the head loss in two-phase flow is predicted with calculated well friction loss and separation loss coefficients. The analysis results are compared with the Combustion Engineering pump test data. The effect of two-phase multiplier on the peak clad temperature in Loss-of-Coolant Accident is also examined using the RELAP5 and the results indicate the importance of its accuracy.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.19 no.3
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• pp.194-204
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• 2007

A numerical analysis and hydraulic experiments were undertaken to investigate the head loss occurring when a flow passes through vertical perforated walls. The numerical analysis applied continuity, momentum and energy equations to the control volumes that were set near the perforated wall. Non-dimensional equations were then derived to calculate both upstream depth and head loss for the given values of downstream depth and velocity. The hydraulic experiments were performed with several single and triple perforated plates varying their opening ratios and intervals. The numerical results with the single plates were compared with the experimental results, and it was shown that the contraction coefficient of the vertical line jet formed after the perforated plates relies on downstream Froude number as well as opening ratio. Based on the experimental results, empirical formulas were formulated. Finally, the formulas were applied to the triple plates sequentially from downstream side to upstream side, and it was found that in general the predicted values nicely agreed with the experimental results.

• Korean Journal of Audiology
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• v.23 no.4
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• pp.210-213
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• 2019

The auricle is a three-dimensional cartilaginous frame covered with thin overlying skin. Due to its complex features, reconstructing helical rim defects after the excision of an auricular mass is challenging. Shortage of subcutaneous tissue and the presence of a tightly bound epithelium further hamper the primary closure of lateral (anterior) auricular skin defects. We present herein a case in which we used a helical rim advancement flap along with an additional postauricular skin flap. We achieved a satisfactory esthetic result with minimal loss of helical diameter and a low risk of flap necrosis by preserving the vascular network of the flap. This technique is less traumatic and will facilitate faster healing as well as improved patient recovery.

• Journal of Audiology & Otology
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• v.23 no.4
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• pp.210-213
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• 2019

The auricle is a three-dimensional cartilaginous frame covered with thin overlying skin. Due to its complex features, reconstructing helical rim defects after the excision of an auricular mass is challenging. Shortage of subcutaneous tissue and the presence of a tightly bound epithelium further hamper the primary closure of lateral (anterior) auricular skin defects. We present herein a case in which we used a helical rim advancement flap along with an additional postauricular skin flap. We achieved a satisfactory esthetic result with minimal loss of helical diameter and a low risk of flap necrosis by preserving the vascular network of the flap. This technique is less traumatic and will facilitate faster healing as well as improved patient recovery.

• Korean Journal of Head & Neck Oncology
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• v.11 no.2
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• pp.185-190
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• 1995

Transient and permanent hypocalcemia after various types of thyroidectomy are well-known complications, and are more common after bilateral subtotal thyroidectomy for Graves' disease. However, their causative mechanisms are not well explained. Four hundred thirty patients with Graves' disease who underwent bilateral subtotal thyroidectomy from January 1983 through December 1992 were analyzed to determine the incidence and risk factors for the development of postthyroidectomy hypocalcemia. Of the 430 patients underwent bilateral subtotal thyroidectomy, symptomatic transient and permanent hypocalcemia developed in 24.2 % (104/430) and 0.5 % (2/430), respectively. With analysis of potential risk factors, the increase in incidence of the postthyroidectomy hypocalcemia was found to be statistically related to the larger thyroid gland, the larger amount of blood loss during thyroidectomy, the smaller remnant thyroid tissue, the higher levels of serum alkaline phosphatase and TBII titers. Our data suggest that impairment of parathyroid gland blood supply, degree of thyrotoxic osteodystrophy and autoimmune process of each patient are regarded as main mechanisms of postthyroidectomy hypocalcemia in patients with Graves' disease.

• Korean Journal of Head & Neck Oncology
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• v.37 no.2
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• pp.51-55
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• 2021

Background/Objectives: Extracapsular dissection has the advantage of reducing complications by minimizing tissue loss of the parotid without intentionally exposing the facial nerve in patients with benign parotid tumor. However, there has been controversy over the surgical results. Thus, the surgical outcomes of extracapsular dissection for benign parotid tumor was compared to those of superficial parotidectomy. Materials & Methods: A retrospective chart review was conducted with 132 patients who received surgery for benign parotid tumor in our center from January 2014 to December 2018 retrospectively. Results: A total of 132 people were enrolled, with 62 people receiving extracapsular dissection, 38 people receiving partial superficial parotidectomy and 32 people receiving superficial parotidectomy. No significant difference was found between the three groups regarding complications such as facial nerve palsy, Frey's syndrome, or first bite syndrome. Operation time and hospital stay was significantly short in extracapsular dissection group. Conclusion: For well-selected cases, extracapsular dissection can be considered as an option for surgery of benign parotid tumor.

• The KSFM Journal of Fluid Machinery
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• v.17 no.5
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• pp.19-26
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• 2014

The cross flow turbine attracts more and more attention for its relatively wide operating range and simple structure. In this study, a novel type of micro cross flow turbine is developed for application to a step in an irrigational channel. The head of the turbine is only H=4.3m and the turbine inlet channel is open ducted type, which has barely been studied. The efficiency of the turbine with inlet open duct channel is relatively low. Therefore, a guide nozzle on the turbine inlet is attached to improve the performance of the turbine. The guide nozzle shapes are investigated to find the best shape for the turbine. The guide nozzle plays an important role on directing flow at the runner entry, and it also decreases the negative torque loss by reducing the pressure difference in Region 1. There is 12.5% of efficiency improvement by attaching a well shaped guide nozzle on the turbine inlet.

• Earthquakes and Structures
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• v.16 no.6
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• pp.727-741
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• 2019

A reinforced concrete water tank is a typical functional liquid storage structure and cracks are the greatest threat to the liquid storage structure. Tanks are readily cracked due to seismic activity, thereby leading to the leakage of the stored liquid and a loss of function. In order to study the effect of cracks on liquid storage tanks, self-healing and leakage tests for bending cracks and through cracks in the walls of a reinforced concrete water tank were conducted. Material performance tests were also performed. The self-healing performance of bending cracks in a lentic environment and through cracks in a lotic environment were tested, thereby the self-healing width of bending micro-cracks in the lentic environment in the short term were determined. The through cracks had the capacity for self-healing in the lotic environment was found. The leakage characteristics of the bending cracks and through cracks were tested with the actual water head on the crack. The effects on liquid leakage of the width of bending cracks, the depth of the compression zone, and the acting head were determined. The relationships between the leakage rate and time with the height of the water head were analyzed. Based on the tests, the relationships between the crack characteristics and self-healing as well as the leakage were obtained. Thereby the references for water tank structure design and grading earthquake damage were provided.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.6
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• pp.430-437
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• 2012

In order to obtain information on the design parameters of the horizontal laterals in floodplain filtration, laboratory-scale sand-box experiments were performed where the head distributions on the laterals and the groundwater profiles were measured according to the change in parameters including lateral diameter, hydraulic conductivity of the sand, water level at the well and raw-water supply rate. Measured data were analyzed using a numerical code in order to identify the discharge intensity distribution along the laterals. It was observed from the result that the lowering of the water level at the well had minimal adverse effect on the performance of the floodplain filtration. Results also elucidated that the low conveyance of the laterals to transmit the filtrate was compensated and supplemented by a natural augmentation in horizontal conveyance through the aquifer when the raw-water supply rate exceeded the adequate recovery rate. With this mechanism, the water quality is expected to improve further since the travel distance through the aquifer is amplified. Based on these findings it can be suggested that the diameter of the lateral used in the floodplain filtration may be smaller than those in riverbank/bed filtration. It was also found that the ratio between the head loss occurring in a lateral and the total head loss in the floodplain filtration was proportional to the exit velocities of the laterals, which may be used to design and/or evaluate the lateral in floodplain filtration.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.11
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• pp.5805-5809
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• 2012

Aims: The study aimed to compare treatment compliance and nutritional outcomes in nasopharyngeal carcinoma (NPC) patients during chemoradiation. Methods: Clinical information of patients with NPC that underwent chemoradiation during 2004-2009 were retrieved from the hospital database and retrospectively reviewed. Patients were categorised into a prophylactic percutaneous endoscopic gastrostomy (PPEG) group and a non-PPEG group. Clinical information including treatment compliance, weight, haematological and renal toxicity was compared. Results: A total of 219 patients were reviewed and categorised into PPEG (n=77) and non-PPEG (n=142). Significant differences in absolute percentage weight loss between groups were found from the $3^{rd}$ cycle of chemotherapy. There were 24.2, 20.3 and 24.8% in the third, the fourth and the fifth cycles of chemotherapy, respectively. Migration of grade 2 to grade 3 weight loss was obviously seen in the $3^{rd}$ cycle as well. A significant difference of grade 3 or more hypokalemia was found with values of 14.3% and 50% in the PPEG and non-PPEG groups, respectively. Other toxicity parameters and treatment compliance were not different between the groups. Conclusions: Use of PPEG resulted in decreased severe weight loss, reduced migration from grade 2 to grade 3 weight loss and reduced hypokalaemia. However, benefits in treatment compliance could not be detected. So consideration of PPEG in NPC patients requires care.