• Clinical and Experimental Pediatrics
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• v.62 no.10
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• pp.395-399
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• 2019

Background: The esophagus is the most common part of gastrointestinal (GI) tract at the risk of stricture. Benign disorders are the leading causes of narrowing. Caustic ingestion is the most common cause of esophageal stricture in children, especially in developing countries. Clinical responses to the topical application of Mitomycin C in various medical procedures have been reported. Purpose: The study aimed to evaluate the methodology, efficacy, and side effects of Mitomycin C in the treatment of esophageal strictures. Methods: This study included 30 children with resistant esophageal strictures. Upper GI endoscopy was performed up to the area of stricture, esophageal dilatation was done, endoscopy was repeated, and Mitomycin C was applied topically under direct endoscopic vision. The effect of the procedure was followed over a period of 3-5 years. Results: The response to Mitomycin C was excellent (clinically and endoscopically) in 28 patients (93.3%) and good (endoscopically only) in 2 patients (6.7%). No side effects of topical Mitomycin C in children with esophageal strictures were reported in this study. Conclusion: Esophageal dilatation followed by local Mitomycin C application may be a useful strategy for treating resistant esophageal strictures.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2001.05a
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• pp.23-28
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• 2001

Since non-corrosive Fiber Reinforced Polymer(FRP) tendons have been in increasing use for underground and coastal structures constantly contacted with fresh water or sea water because of their superiority to metallic ones in corrosion-resistance, new non-metallic anchoring system for FRP tendons has been developed and investigated to verify the effectiveness of tendon force, which consist of mainly FRP pipes and Highly Expansive Mortar(HEM). The major factors considered in this experiment were expansive pressures of HEM during its hydration, sleeve lengths and types, and anchoring methods of tendon. New anchoring system were investigated from the pull-out tests. The pull-out procedures of the FRP tendons in the various pipe filled with HEM were analyzed and improved ideas were suggested to develop novel non-metallic anchoring system for FRP tendons The pull-out tests for the FRP tendon and new non-metallic anchoring system were conducted. The results show that non-metallic anchoring system for the FRP tendon has been more stablized due to the gradual expansive pressrure of HEM, as tims goes. Since tile lower stiffness of FRP pipes causes the weakness of anchoring force, it requires the increase of stiffness using a carbon fiber or an increased section area.

• Corrosion Science and Technology
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• v.10 no.4
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• pp.131-135
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• 2011

The demands of high-strength steel have been steadily increased to reduce the weight of vehicles. Although the TRIP steel has been the promising candidate material for the purpose, high strength hinders the application due to the susceptibility to hydrogen delayed fracture in the corrosive environment. Moreover, the testing method was not specified in the ISO standards. In this work, the test method to evaluate the susceptibility of hydrogen delayed fracture was studied by slow strain rate testing technique. The four test experimental parameters were studied : strain rate, hydrogen charging time, holding time after hydrogen charging, and holding time after cadmium plating. The steel was fractured by hydrogen in case the strain rate was in the range of $1{\times}10^{-4}{\sim}5{\times}10^{-7}/sec$. It was confirmed that the slow strain rate test is effective method to evaluate the susceptibility to hydrogen delayed fracture. The holding time over 24 hrs after hydrogen charging, nullified the hydrogen effect, that is, the specimen was no more susceptible to hydrogen after 24 hrs even though the specimen was fully hydrogen-charged. Moreover, cadmium electroplating could not prevent from diffusing out the hydrogen from the steel in the experiment. The effective experimental procedures were discussed.

• Korean Journal of Bronchoesophagology
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• v.5 no.1
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• pp.14-21
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• 1999

Perforating injury of the thoracic esophagus leads to an almost Immediate exposure of the mediastinum to both oral secretions and refluxed gastric contents. And necrotizing inflammatory response developed inevitably. So, without proper managements, mediastinitis results in severe dehydration or septic conditions, and consequently the life of the patient can be threaten. We experienced recently 4 cases of esophageal perforation. Three cases were Boerhaave's syndromes and the other one was instrumental perforation in patient with corrosive esophageal stricture. Curative surgical procedures were done in 3 cases and the drainage procedure was only possible in the other one due to hepatic failure. And the patient with the drainage management was dead.

• Restorative Dentistry and Endodontics
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• v.46 no.2
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• pp.18.1-18.13
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• 2021

Composite resins are the most commonly used dental restorative materials after minimally invasive dental procedures, and they offer an aesthetically pleasing appearance. An ideal composite restorative material should have wear properties similar to those of tooth tissues. Wear refers to the damaging, gradual loss or deformation of a material at solid surfaces. Depending on the mechanism of action, wear can be categorized as abrasive, adhesive, fatigue, or corrosive. Currently used composite resins cover a wide range of materials with diverse properties, offering dental clinicians multiple choices for anterior and posterior teeth. In order to improve the mechanical properties and the resistance to wear of composite materials, many types of monomers, silane coupling agents, and reinforcing fillers have been developed. Since resistance to wear is an important factor in determining the clinical success of composite resins, the purpose of this literature review was to define what constitutes wear. The discussion focuses on factors that contribute to the extent of wear as well as to the prevention of wear. Finally, the behavior of various types of existing composite materials such as nanohybrid, flowable, and computer-assisted design/computer-assisted manufacturing materials, was investigated, along with the factors that may cause or contribute to their wear.

• Journal of Chest Surgery
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• v.30 no.1
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• pp.48-54
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• 1997

Between 1987 and 1995, eleven patients with severe chronic corrosive stenosis of the hypopharynx and esophagus underwent surgical restoration of digestive continuity at Inje University Seoul Palk Hospital. There were 7 male and 4 female patients aged from 21 to 47 years (mean, 34 years). The caustic material was acid in 6 patients and alkali in 5 patients. The esophagus was reconstructed using the right colon In 9 and left colon in 2. The cervical approach and the side of proximal anastomosis depended on the status of the pyriform slnus of the hypopharynx. In the neck, J-formed incision was made along the sternocleidomastoid muscle. The sternohyoid and thyrohyoid muscles were divided transversely to expose the thyroid cartilage. Hypopharyngeal opening for proximal anastomosis was made by reverse triangular formed resection of the thyroid cartilage after elevation of perichondrium. Immediately after operation, dysphagia and aspiration into trachea were common, so training of swallowing was required. Feeding gastrostomy was usually maintained for 3 months until restoration of swallowing function was confirmed . There was graft necrosis in 3 patients, who were treated with jejunal free graft. Revisional procedures for stenosis of cervical anastomosis in B patients consisted of widening of pharyngocecostomy site in 2 and resection of adhesive band in one. Return of normal swallowing assuring normal nutrition was obtained in 10 of 11 cases.

• Journal of Chest Surgery
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• v.6 no.2
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• pp.225-230
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• 1973

Five cases of esophageal cancer developed at the site of esophageal lye stricture were reported. Duration of lye stricture was between 13 and 40years, and all 5 cases had taken normal diet without appreciable troubles after recovery from the acute stage of burn till the suspected onset of esophageal malignaney. Outstanding symptoms of this grave condition were rather acute progressive dysphagia and frequent episodes of esophageal foreign bodies, Diagnosis could be confirmed easily by endoscopic biopsy in suspected eases, and all were epidermoid carcinoma histopathologically. Curative resection of this condition was made in neither of the cases, and their prognoses were more grave than other esophageal malignancies in our experience. The development of esophageal carcinoma at the site of corrosive esophagitis with resulting benign stricture has now been suspected as a cause and effect relationship between these two conditions, and Kiviranta: stated that the incidence of esophageal cancer in patients with lye stricture of longer duration is a thousand times higher than normal population. During last one decade the authors experienced 5 cases of esophageal carcinoma developed at the site of lye stricture of the esophagus among about 350 cases of lye burned esophagus at the Department of Thoracic & Cardiovascular Surgery, the National Medical Center in Seoul, Korea. In Korea they still use lye as a detergent in rural area, and there are still many persons ingesting lye for suicidal attempt or on accident. Lye stricture of the esophagus is, therefore, the most common esophageal disease needing surgical procedures, and the authors believe that there will be much more eases of lye stricture complicated by esophageal eareinoma repoted in near future in this Country.

• Journal of Periodontal and Implant Science
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• v.31 no.2
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• pp.333-344
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• 2001

The present study was performed to evaluate the effect of tetracycline - HCl on the change of implant surface microstructure according to application time. Implants with pure titanium machined surface and titanium plasma-sprayed surface were utilized. Implant surface was rubbed with 50mg/ml tetracycline - HCl solution for 1 min., $1\frac{1}{2}\;min$., 2 min., $2\frac{1}{2}\;min$. and 3min. respectively in the test group and with saline for 1 min. in the control group. Then, the specimens were processed for scanning electron microscopic observation. The following results were obtained. 1. Pure titanium machined surfaces conditioned with saline for 1 min., showed a few shallow grooves and ridges and were less irregular. 2. Pure titanium machined surfaces conditioned with 50mg/ml tetracycline - HCl solution showed more irregular and corrosive surfaces compared to the control group irrespective of the application time of tetracycline - HCl solution. 3. Titanium plasma-sprayed surfaces conditioned with saline for 1 min., were deposited with round amorphous particles and showed round or irregular pores that can be connected to each other. 4. The irregularity of titanium plasma-sprayed surfaces conditioned with 50mg/ml tetracycline - HCl solution was lessened and the flattened areas were wider relative to the application time of tetracycline - HCl solution. 5. Titanium plasma-sprayed surfaces conditioned with tetracycline - HCl solution for 1 min. and $1\frac{1}{2}\;min$. were very similar to that of the control group, but the surfaces conditioned for 2 min., $2\frac{1}{2}\; min$. and 3 min. were changed. In conclusion, pure titanium machined surfaces were changed irrespective of the application time of tetracycline - HCl solution. And titanium plasma-sprayed surfaces conditioned with tetracycline - HCl solution began to be changed from $1\frac{1}{2}\;min$. This results will be applicable to the regenerative procedures for peri-implantitis treatment.

• Restorative Dentistry and Endodontics
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• v.28 no.5
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• pp.369-377
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• 2003

The aim of this study was to evaluate the effect of two polishing methods and chemical conditioning on the surface of hybrid composites. Ninety cylindrical specimens (diameter：8mm, depth：2mm) were made with three hybrid composites-Filtek Z250, Tetric Ceram. DenFil. Specimens for each composite were randomly divided into three treatment subgroups $^{\circled1}$ Mylar strip (no treatment). $^{\circled2}$ Sof-Lex XT system, $^{\circled3}$ PoGo system. Average surface roughness(Ra) was taken using a surface profilometer at the time of setting and after immersion into 0.02N lactic acid for 1 week and 1 month. Representative specimens were examined by scanning electron microscopy. The data were analyzed using ANOVA and Scheffe's tests at 0.05% significance level. The results were as follows：1. Mylar strip resulted in smoother surface than PoGo and Sof-Lex system (p<0.001). Sof-Lex system gave the worst results. 2. Tetric Ceram was smoother than DenFil and Z250 when cured under only mylar strip. However, it was significantly rougher than other materials when polished with PoGo system. 3. All materials showed rough surface after storage in 0.02N lactic acid, except groups polished with a PoGo system. The PoGo system gave a superior polish than Sof-Lex system for the three composites. However. the correlation to clinical practice may be limited, since there are several processes. such as abrasive, fatigue, and corrosive mechanisms. Thus. further studies are needed for polishing technique under in vivo conditions.

• Journal of the Korean Institute of Gas
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• v.25 no.2
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• pp.42-51
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• 2021

Facilities that supply specialty gases used in semiconductor manufacturing mainly handles with hazardous and dangerous substances with flammable, toxic, and corrosive properties, and gas cabinets are mainly used as such supply facilities. The effects of the supply facilities were analyzed for each leak through the rupture disk in the gas cabinet and a leak where the leak hole. In this case, gas leaked to the outside depending on the leak area. It is a factor that creates a risk depending on the concentration of the leaked gas. Depending on the risk of leakage, all measures such as safe operation procedures should be reviewed again.