• Clinical and Experimental Pediatrics
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• 제62권10호
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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.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2001년도 춘계학술발표대회 논문집
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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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• 제10권4호
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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.

• 대한기관식도과학회지
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• 제5권1호
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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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• 제46권2호
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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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• 제30권1호
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• pp.48-54
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• 1997

본 인제대학교 의과대학 흉부외과학교실 서울백병 원에서는 1986년 10월부터 1995년 12월까지 부식제 의 음용으로 하인두와 식도 입구부터 심한 협착이 발생한 1 1례의 환자에서 하인두의 양배꼴동에 대용식 도를 문합하는 식도재건술을 시행하였다. 환자는 남자 7례, 여자 4례로 모두가 성인으로 연령은 21세 에서 47세까지로 평균 34세였다. 식도협착의 원인이 된 부식제는 산성이 6례: 알칼리성이 5례였다. 이들의 부식제 음용 동기는 자살 목적이 9례였 고, 사고로 인한 경우가 2례였다. 부식제의 음용후 최종적으로 식도재건술까지의 기간은 4개월에서 부 터 21년까지 였다. 식도재 건술시 이용한 대용식도는 9례에서는 우측 결장을 사용하였고, 2례는 이 전에 우측 결장을 이용한 식도재건술이 실패한 상태여서 좌측 결장을 사용하였다. 모든 환자에서 식도 절제술은 하지 않았고 결장은 흉골하로 거상하였다. 경부 문합은 환자의 머리를 똑바로 놓은 상태에서 경부에 J형태로 피부를 절개하고 흉골설골, 갑상설 골근을 절단하고 갑상연골의 연골막을 박리하여 감상연골을 역삼각형모양으로 부분절제하고 양배꼴동을 열고 결장과 단단문합하였다. 수술 직후 類觀隙\ulcorner환자는 음식물을 삼킬 때 연하곤란과 기도내로 음식물이 넘어가 고형 음식물로 삼키는 훈련이 필요하였다. 수술 후 발생한 합병증은 대용식도의 괴사가 3례가 발생하여 유리공장을 이식하였다. 3례에서는 경부 문합부위에 협착이 있어 2례에서 상부문합부위를 확장하였고 1례에서는 유착띠제거술을 시행하였으며 모두 협착이 해소되었다. 수술 후 외래 추적관찰에서 10례에서는 정상적으 로 음식물을 삼킬 수 있었고 유리공장을 사용하여 2차수술을 시행한 1례는 유리공장의 괴사로 3차수술 을 기다리고 있다.

• Journal of Chest Surgery
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• 제6권2호
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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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• 제31권2호
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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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• 제28권5호
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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.

• 한국가스학회지
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• 제25권2호
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• pp.42-51
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• 2021

반도체 제조에 사용하는 특수가스를 공급하는 설비는 인화성·독성·부식성을 지닌 유해·위험물질을 주로 취급하는데, 이러한 공급설비로는 주로 가스캐비닛이 사용되고 있다. 가스캐비닛 내 파열판을 통한 누출, 누출 개구부의 확대가 가능한 누출, 누출 개구부가 확대되지 않는 누출의 케이스별로 공급장치 내부 상태 및 외부로의 확산 영향을 누출 원인별로 분석하였다. 이 경우 누출 단면적에 따라 공급장치 외부로 가스가 누출되는 경우가 발생함을 확인하였다. 외부로 누출되는 가스의 농도에 따라 폭발분위기 형성 등 위험성이 존재하는 요인으로 작용하며, 위험에 따라 공급설비의 안전운전절차 등 제반 조치사항을 다시 검토할 필요가 있음을 확인하였다.