• Journal of the korean academy of Pediatric Dentistry
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• v.31 no.1
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• pp.59-65
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• 2004

Root perforations that result in a communication of the root space with the periodontal tissues occasionally occur during endodontic procedures. They may be induced iatrogenically. Successful treatment depends mainly on immediate sealing of the perforation and prevention of infection. Several factors affect the achievement of these goals, most important of which are time of occurrence, size and location of the perforation. Identification of root perforations is possible by direct observation of bleeding, radiography and an apex locator. Perforation defects may be repaired by nonsurgical or surgical techniques. We report two cases of root perforation. One was treated by glass ionomer, other was treated by composite resin with calcium hydroxide.

• Journal of Dental Rehabilitation and Applied Science
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• v.30 no.2
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• pp.176-183
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• 2014

Severely absorbed edentulous ridge cannot bear mechanical stress, causes undesired transformation of oral environment and makes patients difficult to adapt to dentures. Nowadays implant overdenture can be a treatment of choice in order to relieve patients' discomfort and improve stability and retention of the denture. Placement of implant on maxilla is difficult because of its bone quality and anatomic structure. It also has wide supportive tissue and convenience of border sealing, which provides sufficient support and stabilization with conventional complete denture. Mandible, on the other hand, is difficult to obtain sufficient support, retention and stabilization with conventional complete denture. Therefore, implant overdenture is recommended on mandible. Locator attachment has been improved for convenience of use and male parts of various retention enabled it to replace ball type attachment clinically. In this study, we restored maxillary arch with conventional denture, and mandibular arch with implant and tissue-supported overdenture and Locator attachment system.

• Food Science and Preservation
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• v.6 no.3
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• pp.270-275
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• 1999

During the storage period of chives(Allium Tubersum fouler) at low temperature(4-5$^{\circ}C$), weight loss in chives by the packages of LDPE, p.p and HDPE film was decreased less than 1%, however that of chives unpacked was remarkably increased as time went by. Soluble solids of unpacked chives was decreased from 6.0 to 4.6 $^{\circ}$Brix after 2 weeks storage and that of LDPE film sealed was lessened to 4.9-5.9 $^{\circ}$Brix, the treatment of deaeration showed a tendency to decrease a lot to 4.5-4.7 $^{\circ}$Brix. The vitamin C content of chives unpacked was 37.1mg% at before storage, but after one week decreased very much to 15.2mg%, and that in chives packed by the different methods was visibly lessened after 2 weeks storage. the Vitamin C content in chives processed by deaeration sealing method was lessened compared to that at chives processed by sealing only. In the bag of chives packed by HDPE film had low CO$_2$ and C$_2$H$_4$ concentration and the gas concentration in the bag of chives processed by P.P. film was increased as storage period went by. Conclusively the freshness of chives packaged by LDPE and HDPE film maintained for 3 weeks, at P.P film for 2 weeks, but the marketability of chives unpacked was degraded in 3-4 days.

• Journal of Dental Rehabilitation and Applied Science
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• v.39 no.4
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• pp.250-259
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• 2023

The use of digital technology in fixed prosthetic treatment using implants enables predictive treatment through diagnosis and virtual surgery by integrating clinical and radiological information of patients. Existing digital scanning methods require several components to be removed, such as removing the healing abutment and connecting the scan body. In the scannable healing abutment developed in consideration of this point, scanning is performed directly on the healing abutment, maintaining soft tissue sealing and simplifying scanning. Digital technology can also be used when obtaining the intermaxillary relationship. Recently, various digital technologies have been reported to acquire the intermaxillary relationship of edentulous patients using surgical guides, patient-specific scanning devices, or scans of the inside of temporary dentures. In this case, the implant-supported fixed prosthesis treatment was performed through scanning the scannable healing abutment and the inner side of the temporary denture to obtain the intermaxillary relationship, thereby simplifying the treatment process and obtaining aesthetically and functionally excellent clinical results.

• Journal of the Korea Organic Resources Recycling Association
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• v.24 no.4
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• pp.21-29
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• 2016

This study was conducted to review Waste Transfer Stations(WTSs) in Seoul, especially focusing on three aspects, main roles, neighbor friendly and regulation compliance, and to draw out recommendation for improvement. The 46 units of all 65 WTSs treated large amount of waste on a day shipping-out schedule, the other 19 WTSs treated small amounts of wastes which were transported after 3~30 days stock. About 57% of WTSs are located in residential or commercial area. Other 57% of WTSs were open without walls. 79% of WTSs were placed alone. Just 17% of WTSs were permitted as environmental infrastructures by urban planning law, and 31% of WTSs were operated by private waste haulers who were permitted by waste management law. Most WTSs in Seoul seemed to go well with on-going policy demand, such as regionalizing waste treatment facilities, expanding waste recycling, and so on. However lots of WTSs did not implement sufficient environmental protection measures, and partly not compliant with regulations related to urban infrastructures. In the future, the issue on sealing facilities and integrating functions of waste management facilities could be considered in order to fit in urban environment.

• Restorative Dentistry and Endodontics
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• v.15 no.2
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• pp.104-114
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• 1990

The purpose of this study was to evaluate the adaptation of root canal filling material to the dentinal wall of root canal and to compare the sealing ability of the root canal filling materials using ultrasonic endodontic instrument with injection-molded thermoplasticized gutta-percha filling method and lateral condensation method. Fifty fresh human single root exlracted for orthodontic treatment, were randomly selected, and instrumented by step-back technique. And then, the teeth were divided into 5 groups according to each root canal filling methods. In the experimental group 1 and group 2, the root canals were filled with gutta perdia cases using ultrasonic instrument with and without sealer. In the experimental group 3 and 4, using jection-moldeed thermoplasticized gutta-percha method by obtul$^{(R)}$ canals were filled with and without sealer. In the control group, the canals were filled with sealer by lateral candensation. And then, 5 teeth of each group were immersed in black Indian ink, decalcified and cleared. The depth of dye penetration into the root canal were evaluated with stereoscope (Reichert Ltd., USA). Among the 5 teeth remaining in each group, the single longituding grooves were made on the labial and lingual root surfaces and then immersed in the liquid nitrogen to fracture the teeth spontaneously without any distortions of gutta-percha. Each specimens were examined with X-650 Scanning Electron Microscope(Hitachi ltd, Japan) to show the adaptation to the canal wall, void, homogenicity of filling material and location of gutta-percha or sealer in the dentinal tubules of the root canal. The observations were as follows : 1. The experimental group 1 showed smaller mean dye penetration than control group, and showed the penetraton of sealer in the dentinal tubules of apical third of the root canal. 2. The experimental group 2 and group 4 showed the penetration of gutta-percha in the dentinal tubules of root canals. 3. The experimental group 1 and group 3 showed less mean dye penetration than the experimental group 2 and group 4. 4. The experimental group 1 and group 2 showed better adaptation of filling materials than control group.

• Journal of Periodontal and Implant Science
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• v.32 no.3
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• pp.655-664
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• 2002

The purpose of this study was to observe the degree of surface obliteration of dentinal tubule using Gluma(R) desensitizer and MS coat(R) with 15 specimens made out of 15 extracted lower incisors. They were divided into Root planning group(control), Gluma(R) desensitizer group(test I ) and MS coat(R) group(test II). Degree of Obliteration was examined under the scanning electron microscope(${\times}$2000). The following results were obtained: 1. In the root planning group(control), the complete open of dentinal tubule surface was accounted for 73.8%, the partial obliteration for 17.2% and the complete obliteration for 9.0%. 2. In the Gluma(R) desensitizer group (test I), the complete open of dentinal tubule surface was accounted for 23.6%, the partial obliteration for 42.8% and the complete obliteration for 33.6%. 3. In the MS coat(R) group (test II), the complete open of dentinal tubule surface was accounted for 19.2%, the partial obliteration for 45.6% and the complete obliteration for 35.2%. 4. The average number of open dentinal tubules in the control was significantly higher than in the test I and II (P<0.05), but there were no statistically significant differences between the test I and II. 5. The average number of the partially obliterated and the completely blocked dentinal tubules in the control was significantly lower than the test I and II(P<0.05), but there were no statistically significant differences between the test I and II. The results of this study suggest that Gluma(R) desensitizer and MS coat(R) is significantly effective on dentinal tubule obliteration, therefore they were effective on hypersensitivity caused by periodontal treatment

• Journal of Chest Surgery
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• v.26 no.1
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• pp.44-46
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• 1993

There are several methods for managing pneumothorax through thoracoscope. Among them, electric cautery of bleb or bulla is very simple to do and can be done through the conventional thoracoscope. It is cosmetically excellent because it needs only incision. It is economically cheap comparing other methods because it does not need staplers or clips and other disposables. However, this method has been controversial for its success rate because of the ability of sealing off the air-leaking from the lung tissue. To evaluate the success rate, 29 cases of pneumothorax treated by electric cautery and instillation of oxytetracyline solution through the thoracoscope were analyzed. Among 29 patients, 18 were male and 11 female ranging 17 to 43 years old. The indications for thoracoscopy were recurrence in 20 cases and persistence in 9 cases. The underlying casuses of pneumothorax were bleb in 10 cases and bulla with bleb or not in 19 cases. Twenty one cases were successful [4%] and 8 cases were failed. The failed 8 cases were explored from 14 to 28 days after thoracoscopy.Six cases were explored through transaxillary minithoracotomy and 2 were done through limited posterolateral thoracotomy. The causes of failure were the necrotic lung tissue occured by excessive electric cautery in 6 cases and the necrotic lung tissue and residual bulla in two cases. In 10 bleb cases, 9 were successful [90.0%]. But in 19 cases of bulla, 12 were successful [63.2%]. In conclusion, the success rate of electric cautery through thoracoscope was 72. 4% and the causes of failure were lung necrosis and residual bulla. The success rate of the bleb cases was higher than that of the bulla cases.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.1
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• pp.183-189
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• 2018

In this study, the bond strength between concrete and metal films was investigate according to changing water content ratio of substrate concrete by pull-out test in order to develop the new finishing design methods for building structures using the metal films. The following conclusions were obtained as a result of the studies. It was find that the colour of metal did not change before and after the metal spraying. Also, the water content ratio of substrate concrete must be controlled under 10% weight to confirm the standard bond strength of finishing material to concrete. 2.5 MPa. To enhance the bond strength between concrete and metal films, it is very effective to strengthen the concrete surface using the agent which strengthen the concrete surface and seal the pore of metal film by the sealing agents. Therefore, the control of concrete surface treatment and water content ratio are necessary to secure the bond strength of metal films.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2014.11a
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• pp.300-300
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• 2014

해양환경 하에서 대형 강구조물의 경우 장기간 부식손상을 방지하기 위해 아크 용사코팅 기술이 오래전부터 유용하게 이용되어 왔다. 아크 용사코팅 기술은 타 용사코팅 기술에 비해 경제성과 생산성이 뛰어나 대형 강구조물에 적용되고 있다. 용사재료로는 Al, Zn 또는 그 합금들이 주로 사용되어 강재에 대해 희생양극 방식효과를 나타낸다. 그러나 아크용사에 의해 적층된 코팅 층은 용사공정 중 불가피하게 수많은 기공과 산화물이 포함되어 내식성 및 내구성에 악영향을 미치게 된다. 따라서 본 연구에서는 알루미늄 합금의 용사코팅 층에 대하여 다양한 후처리를 통해 내식성과 더불어 내구성을 향상시키고자 하였다. 용사코팅은 알루미늄 합금 선재(1.6 ${\varnothing}$)를 사용하여 아크용사를 실시하였다. 용사 시 용사거리는 200 mm, 공기압력은 약 $7kg/cm^2$ 정도로 유지하면서 용사코팅을 실시하여 약 $200{\mu}m$ 두께로 코팅 층을 형성시켰다. 이후 용사코팅 층의 표면에 다양한 후처리재를 적용하였으며, 내구성을 평가하기 위하여 후처리 적용 전후 시험편에 대하여 캐비테이션 실험을 실시하였다. 캐비테이션 실험은 ASTM G32-92에 의거하여 주파수 20 kHz의 초음파 진동 장치(ultrasonic vibratory device)를 사용하였다. 그리고 시험편 표면과 발진 혼에 부착된 팁(tip)과의 거리는 1 mm로 일정하게 유지시킨 뒤, 캐비테이션 발생 시간을 변수로 하여 실험을 실시하였다. 손상된 용사코팅 층의 표면은 주사전자현미경과 광학현미경으로 관찰하였으며, 시험편 손상깊이는 3D 현미경으로 비교 분석하였다. 또한 캐비테이션 실험 전후의 무게를 측정하여 무게 감소량을 상호 비교하였다. 그리고 전기화학적 실험은 천연해수 속에서 자체 제작한 홀더(holder)를 이용하여 $0.33183cm^2$의 용사코팅 층만을 노출시켜 실시하였다. 그리고 기준전극은 은/염화은 전극을, 대극은 백금전극을 사용하였다. 분극실험을 통해 후처리 적용에 따른 용사코팅 층의 부식전위 및 부식전류밀도를 비교 평가하였다. 그 결과, 용사코팅 층에 의하여 강재에 대한 희생양극 방식전위가 확보되었으며, 후처리재가 적용된 용사코팅 층에서 내식성 및 캐비테이션 저항성이 향상되었다.