• Korean Journal of Head & Neck Oncology
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• v.12 no.1
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• pp.3-7
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• 1996

Nasopharyngeal carcinoma(NPC) is a disease whose primary initial treatment is radiation. Results of radiation therapy in early stage disease is promising; however, in stage IV disease, the best reported five-year survival is only about 30%. In patients with post-radiation recurrent disease, radiation controls only a small portion of patients, as well as being associated with significant radiation injury. In this paper we discuss the use of salvage treatment modalities for post-radiation recurrence. A retrospective chart review and analysis of salvage treatment results were performed for 39 patients with recurrent post-radiation NPC and positive cervical lymph nodes during the period beginning 1985 until 1995. Mean age of these patients was 52.3$\pm$10.37 years and male: female ratio was 1.8 : 1. Twenty patients were treated with salvage treatment, and ten patients were treated by salvage chemotherapy. A total of nine patients underwent surgical salvage treatment, including neck dissection(6), transnasal laser surgery and booster radiotherapy(2), and primary surgery(1). Salvage treatment were effective in reducing patients' pain in twenty patients (51.3%) and prolonging life in nine patients(23.1%); however, recurrence of disease within six months and/or residual disease by clinical or radiologic exam was noted in all patients receiving salvage radiotherapy, chemotherapy, laser surgery with radiotherapy, and primary site surgery. In the group undergoing salvage neck dissection, three patients(50%) were disease free for at least two years. Of the different modalities, radiotherapy was associated with the best quality of life while catastrophic salvage surgery resulting in insignificant prolongation of life was associated with the poorest quality of life. We conclude that salvage surgery is the optimal choice of treatment for regional recurrence such as nodal failure, however palliative salvage therapy could be preferred in other cases with recurrent post-radiation NPC.

• Magazine of the Korea Concrete Institute
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• v.3 no.2
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• pp.123-132
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• 1991

The purpose of this study was to Investigate the effects of bent - up bar Within beam - column 1lint core with High - Strength Concrete up to 800kg/$cm^2$. To achieve these objectives, 5 specimens were designed and tested under monotoric loading and reversed cyclic loadings. The primary variables were the number of bent-up bars, compressive strength of concrete and loading patterns. The results showed that the load capacity of specimen subjected to monotonic loading had more large than that of specirnn subjected to reversed cyclic loadings and the bent - up bar within joint core could prevented the crack at the joint face from propagating into the pint core but the failure was concentrated at the face of beam - column pint. Thus the study on flexural strength ratio should be accomplished before using bent - up bars within the joint core.

• Journal of Korean Neurosurgical Society
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• v.63 no.3
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• pp.386-396
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• 2020

Objective : To generate synthetic spine magnetic resonance (MR) images from spine computed tomography (CT) using generative adversarial networks (GANs), as well as to determine the similarities between synthesized and real MR images. Methods : GANs were trained to transform spine CT image slices into spine magnetic resonance T2 weighted (MRT2) axial image slices by combining adversarial loss and voxel-wise loss. Experiments were performed using 280 pairs of lumbar spine CT scans and MRT2 images. The MRT2 images were then synthesized from 15 other spine CT scans. To evaluate whether the synthetic MR images were realistic, two radiologists, two spine surgeons, and two residents blindly classified the real and synthetic MRT2 images. Two experienced radiologists then evaluated the similarities between subdivisions of the real and synthetic MRT2 images. Quantitative analysis of the synthetic MRT2 images was performed using the mean absolute error (MAE) and peak signal-to-noise ratio (PSNR). Results : The mean overall similarity of the synthetic MRT2 images evaluated by radiologists was 80.2%. In the blind classification of the real MRT2 images, the failure rate ranged from 0% to 40%. The MAE value of each image ranged from 13.75 to 34.24 pixels (mean, 21.19 pixels), and the PSNR of each image ranged from 61.96 to 68.16 dB (mean, 64.92 dB). Conclusion : This was the first study to apply GANs to synthesize spine MR images from CT images. Despite the small dataset of 280 pairs, the synthetic MR images were relatively well implemented. Synthesis of medical images using GANs is a new paradigm of artificial intelligence application in medical imaging. We expect that synthesis of MR images from spine CT images using GANs will improve the diagnostic usefulness of CT. To better inform the clinical applications of this technique, further studies are needed involving a large dataset, a variety of pathologies, and other MR sequence of the lumbar spine.

• Childhood Kidney Diseases
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• v.10 no.2
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• pp.201-212
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• 2006

Purpose : Vesicoureteral reflux(VUR) is the major risk factor of urinary tract infection(UTI) in children and may result in serious complications such as renal scarring and chronic renal failure. The purpose of this study was to evaluate the relationship between VUR and renal scar formation, the usefulness and correlation of various imaging studies in reflux nephropathy, and the spontaneous resolution of VUR. Methods : We retrospectively reviewed 106 patients with VUR with no accompanying urogenital anomalies in the Department of Pediatrics, Bundang CHA Hospital during the period from Jan. 1996 to Mar. 2005. Ultrasonography and $^{99m}Tc$-dimercaptosuccinic acid(DMSA) scan were performed in the acute period of UTI. Voiding cystourethrography(VCUG) was performed 1 to 3 weeks after treatment with UTI. Follow-up DMSA scan was performed 4 to 6 months after treatment and a follow-up VCUG was performed every 12 months. Results : The mean age at detection of VUR was $13.8{\pm}22.2$ months and the male to female ratio was 2:1. The incidence of renal scarring showed a tendency of direct correlation between severity of VUR(P<0.001) and abnormal findings of renal ultrasonography(P<0.01). 63.2%(24 of 38 renal units) of renal parenchymal defects present in the first DMSA scan disappeared on follow-up DMSA scans. Follow-up DMSA scans detected renal scars in 7(14%) of 50 renal units with ultrasonographically normal kidneys. Meanwhile, ultrasonography did not show parenchymal defects in 7(36.8%) of 19 renal units where renal scarring was demonstrated on a follow-up DMSA scan. The spontaneous resolution rate of VUR was higher(75%) in cases with low grade(I to III) VUR(P<0.01). Conclusions : The presence and severity of VUR and abnormal findings of renal ultrasonography significantly correlated with renal scar formation. DMSA scan was useful in the diagnosis of renal defects. Meanwhile renal ultrasonography was an inadequate method for evaluating renal parenchymal damage. Therefore, follow-up DMSA scans should be performed to detect renal scars even in children with low-grade VUR and normal renal ultrasonography.

• Journal of Korean Society of Steel Construction
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• v.24 no.6
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• pp.671-682
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• 2012

The use of sinusoidal corrugated web girder for the box-type girders and gable steel main frames has recently been increasing very much. The reasons are that the thin web of the girder affords a significant weight reduction compared with rolled beam and welded built-up girder, and that corrugation prevents the buckling failure of the web. Improvements of the automatic fabrication process makes mass production of the corrugated web and unit possible, and applications of this girder have been extended considerably. Thus, the research for the optimum design processer considering the production data is needed practically. For doing this research, we develope the discrete optimum structural design program in consideration of production list data for the research, and the program apply to the single girder under the uniform load and the concentrated load as numerical example. We consider objective function as minimum weight of the girder, and use slenderness ratio, stress of flanges and corrugated web, and the girder deflection as the constraint functions. And also the Genetic Algorithms is adopted to search the global minimum point by using the production list as a discrete design variable. Finally, to verify the optimality of the design, we conduct a comparison of the results of the discrete optimum design with those of the continuous one, and also analyze the characteristics of the optimum cross-section.

• Journal of Chest Surgery
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• v.30 no.3
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• pp.315-321
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• 1997

A clinical analysis was performed on 326 cases of the non-penetrating rib fractures experienced in the department of thoracic and cardiovascular surgery, Chosun University Hospital and 102 cases of the non-penetrating rib fractures those has been admitted and treated in the department of thoracic and cardiovascular surgery, Jeonnam Hwasoon lung-ang Hospital during a period from Jan. 1994 to Dec. 1995. 1. Sex ratio was 3.4:1 in urban and 3.6:1 in rural communities with male predominance. 2. Most· common cause were traffic accident in both communities. 3. Hemothorax, pneumothorax and hemopneumothorax which needed thoracostomy were observed iii 146 cases(44.7%) in the urban and 12 cases(11.7%) in the rural communities. 4. Left thorax was the spell site of rib fractures in both communiti s. 5. Rib fracture was prevalent from 3rd to 6th rib in both communities. 6. Open thoracotomy was performed in 37 cases(11.3%) in urban and 3 cases(2.9%) in rural communities. 7. Overall mortality was 4.29%(14 cases) in urban area and, 1.96%(2 cases) in rural communities, and cause of death were hypovolemic shock, brain edema, sepsis, respiratory failure, asphyxia, and cardiogenic shock.

• Journal of Chest Surgery
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• v.31 no.3
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• pp.266-270
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• 1998

The management of malignant pleural effusion is a difficult problem. Tetracycline was probably the most commonly used sclerosing agent, but parenteral tetracycline is no longer available. This prospective study was designed to determine the efficacy of insufflated talc in producing plerodesisin patients with malignant pleural effusions. Fifteen patients managed between March 1995 and March 1997 underwent thoracoscopy and had 4 gm sterile asbestos-free talc insufflation throughout the pleural space. The mean interval between the procedure and last follow-up was 101 days(range: 25-233 days). The results of treatment were clinically and radiologically compared with pre-operative status. The results were as follows: 1. The patients were 6 men and 9 women with a mean age of 55.1 years(range: 31-74 years). The primary tumors were lung cancer in 10 patients, breast cancer in two, hepatoma in one, stomach cancer in one, and adenocarcinoma of unkown origin in one. 2. Cancer cell positive ratio was 36% in sputum cytology study and 100% in thoracoscopic biopsy. 3. Symptoms improved in 94% of patients treated by talc pleurodesis. 4. After 30 days of the procedure, there was radiologically no recurrence of plural fluid in 94% patients. 5. There were wound infection in one, respiratory failure in one. In conclusion, the insufflation of 4 gm sterile asbestos-free talc in the pleural space is an effective method to control malignant pleural effusions and patients selection is important factor for reexpansion the lung.

• Journal of Energy Engineering
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• v.27 no.2
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• pp.14-25
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• 2018

The combined cycle power plant has a cycle of operating the gas turbine with fuel, such as natural gas, and then producing steam using residual heat. The fuel gas is supplied to the gas turbine at a level of 4 to 5 MPa, $200^{\circ}C$ through a compressor and a heat exchanger. In this study, the risk assessment method considering the piping system stress was carried out for safe operation and soundness of the gas fuel supply piping system. The API 580/581 RBI code, which is well known for its risk assessment techniques, is limited to reflect the effect of piping stress on risk. Therefore, the systematic stress of the pipeline is analyzed by using the piping analysis. For the study, the piping system stress analysis was performed using design data of a gas fuel supply piping of a combined cycle power plant. The result of probability of failure evaluated by the API code is compared to the result of stress ratio by piping analysis.

• The Journal of Korean Society for Radiation Therapy
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• v.8 no.1
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• pp.41-54
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• 1996

The secondary electrons developed by interaction between primary beam and a tray mounted for blocks in Megavoltage irradiation result in excess soft radiation dose to the surface layer. To reduce this electron contamination, electron filters have been used to be attached under a tray. Various filters with Cu and Al plates in six different thickness and Cu/Al combined plates in 3 different thickness were tested to measure the reduction rate of secondary electron contamination to the surface layer. The measurement to find optimal filter was performed on 6MV linear accelerator in $10 cm{\times}10 cm$ field size and fixed 78.5cm source to measurement points distance from surface to maximum build up point in 2mm intervals. The result was analyzed as the ratio of measured doses with using filters, to standard doses of measured open beam. The result of this study was fellowing : 1. The contaminated low energy radiation were mainly produced by blocking tray. 2. The surface absorbed dose was slowly increased by increasing irradiation field size but rapidly increased at field size above $15cm{\times}15cm$. 3. Al plate upto 2.5mm thickness used as a filter was found to be inadequate due to the failure of reduction of the surface absorbed dose below doses of the under surface upto the maximal build up. Cu 0.5mm plate and Cu 0.28mm/A1 1.5mm compound plate were found to be optimal filters. 4. By using these 2 filters, the absorbed dose to the surface were effectively reduced $5.5\%$ in field size $4cm{\times}4cm,\;11.3\%$ in field size $10cm{\times}10cm,\;22.3\%$ in field size $25cm{\times}25cm$. 5. In field size $10cm{\times}10cm$, the absorbed dose to the surface of irradiation was reduced by setting TSD 20cm at least,. but effective and enough dose reduction could be achieved by setting TSD 30cm as 2 optimal filters used. 6. More surface dose absorbed at TSD less than 7.4cm with a tray and filters together indicated that soft radiation was also developed by filters. 7. The variation of PDD by the different size of irradiation field was minimal as 2 optimal filters used. There was also not different in variation of PDD according to using any of two different filters. 8. PDD was not effected either by various TSD or by using the different filter among two.

• Journal of Korean Tunnelling and Underground Space Association
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• v.14 no.4
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• pp.293-308
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• 2012

The shear behavior at the particle/surface interface such as rock joint can determine the mechanical behavior of whole structure. Therefore, a fundamental understanding of the mechanisms governing its behavior and accurately estimation of the interface strength is essential. In this paper, PFC, a numerical analysis program of discrete element method was used to investigate the effects of the surface roughness on interface strength. The surface roughness was characterized by smooth, intermediate, and rough surface, respectively. In order to investigate the effects of particle shape and crushing on particle/surface interface behavior, one ball, clump, and cluster models were created and their results were compared. The shape of particle was characterized by circle, triangle, square, and rectangle, respectively. The results showed that as the surface roughness increases, interface strength and friction angle increase and the void ratio increases. The one ball model with smooth surface shows lower interface strength and friction angle than the clump model with irregular surface. In addition, a cluster model has less interface strength and friction angle than the clump model. The failure envelope of the cluster model shows non-linear characteristic. From these findings, it is verified that the surface roughness and particle shape effect on the particle/surface interface shear behavior.