• Restorative Dentistry and Endodontics
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• v.11 no.1
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• pp.53-61
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• 1985

This study was conducted to evaluate and compare the apical leakage in the following retrograde techniques; apicoectomys, retrograde filling with zinc oxide eugenol cement, non-zinc and zinc amalgam, and cold-burnished gutta-percha method. One hundred twenty five upper anterior and lower premolar teeth were divided into five above mentioned groups and each tooth was individually prepared for its particular group. The specimens were incubated at $37^{\circ}C$ for 14 days and then were infiltrated by 2% methylene blue for 24 hours. The apical leakage was evaluated by measuring the degree of dye penetration between the filling material and the canal wall. The results were as follows: 1. The cold-burnished gutta-percha group showed the least amount of apical leakage and the apicoectomy group showed the greastest amount of apical leakage. 2. Statistics showed that there were significant differences among the groups (P<0.05), however there was no difference between the zinc oxide eugenol cement retrograde filling group and the non-zinc amalgam retrograde filling group (P>0.05).

• The Journal of the Korea institute of electronic communication sciences
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• v.12 no.6
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• pp.1227-1232
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• 2017

In this study, we have studied a system to reduce the inconvenience and the accident rate at the intersection when the visually impaired use traffic information by using pressure sensor and ultrasonic sensor. By using the pressure sensor to light the strip LED, the driver recognizes the pedestrian, thereby reducing the accident rate. In addition to the pedestrian signal light information, the ultrasonic sensor and Bluetooth transmit the bus position information to the application so that the user can listen to the voice.

• Proceedings of the Technology Innovation Conference
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• 2005.02a
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• pp.200-219
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• 2005

현재 홈네트워킹의 솔루션으로 제기되고 있는 것은 이더넷(Ethernet), 전화선(Phone line), 전력선(PLC), 무선랜(Wireless LAN), 블루투스(Blue tooth) 등 다양하다. 그러나 국내 홈네트워킹 시장과 기술의 진행 방향 및 잠재 시장 전망에 대한연구가 부족한 현실에서 시장 참여자들의 불 확실성은 높을 수 밖에 없다. 이에 어떤 기술이 홈네트워킹 시장을 주도할 지를 전망하는 것이 무엇보다 시급한 과제가 되고 있다. 따라서 본 연구에서는 홈네트워킹 유선 전송 기술분야에서 유력한 규격으로 예상되는 PLC를 중심으로 홈네트워킹의 수요를 예측하고자 한다. 홈네트워킹 시장은 홈네트워킹 장치들이 Built-in 형태로 보급되는 신규주택과 소비자의 선택에 의해 홈네트워킹 장치들이 설치되는 기존 주택 시장으로 나누어 질 수 있다. 본 연구에서는 기존 주택 시장을 대상으로 컨조인트 방법을 통한 소비자의 선호 구조를 홈네트워킹을 구현시키는 각 기술에 대한 (기술)로드맵과 결합하여 동적인 소비자의 선택을 관찰함으로써 각 기술이 확산되는 과정을 살펴볼 것이다. 추가적으로 PLC의 기술적 특징들을 가상적으로 변화시켜가면서 다른 기술과의 경쟁관계를 살펴봄으로써 PLC의 기술개발 전략에 시사점을 도출할 것이다. 본 연구를 통해 홈네트워킹의 관련 실무자에게는 향후 홈네트워킹 시장 진입이나 제품 개발, 기술 협력 제휴시 유용한 자료가 될 것으로 보인다. 또한 정부의 정책담당자들에게는 홈네트워킹 확산의 장애요인 해소를 위한 정책 가이드라인을 제공할 수 있을 것으로 기대하고 있다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.3
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• pp.121-126
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• 2019

Recently IoT named Internet of Things technology is widely used throughout the industry. In this paper, a smart vending machine system is proposed to solve inconvenience of vending machine which is commonly seen. This allows users to purchase goods without cash and saves management costs by allowing vending machine managers to stock and sell conveniently. For the production of this smart vending machine, Analysis example using UML which is object-oriented analysis method and flowchart and screen design applying it are presented. Also this presented method is shown to being applied usefully for a guideline of building smart vending machine commercialization system based on IoT.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.10a
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• pp.654-657
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• 2014

In this paper, we proposed a short distance control method of AtoN charge and discharge regulator. The proposed control measures, was constructed by applying the communication standards NEMA018 of AtoN and control function analysis of the charge and discharge regulator that has been operating in the country. By using the control method is proposed, while maintaining the waterproof without product degradation, there is an advantage that can communicate control wired or wireless. Also, it is possible to ensure the accessibility of the charge and discharge regulator in operation, it is effective for maintenance. In this paper, installed the application to control the charge and discharge regulator to the smart-phone. by using a PC and Blue-tooth communication, to examine the effectiveness of the control information. Future, control method of power controller, can provide a national standard.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.4
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• pp.719-724
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• 2021

In this paper, we studied properties of smart farms that can automatically control not only the temperature and humidity but also the illumination to improve plant productivity. The smart farm was designed to allow the controllers to operate through Arduino by receiving input values from each sensor. In addition, to maximize the convenience of smart farm, the Bluetooth communication module is used to control the smart phone. The study confirmed that the automation function of smart farms can create an environment suitable for plants to grow.

• Restorative Dentistry and Endodontics
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• v.48 no.2
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• pp.17.1-17.8
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• 2023

The present report describes the endodontic treatment of an Oehlers type II dens invaginatus in a maxillary lateral incisor with 5 root canals, an extremely rare condition. Apical periodontitis and related symptoms were noted. Cone-beam computed tomography was used to aid the diagnosis, reveal tooth morphology, and assist in canal location. The pulp chamber was carefully accessed, and the root canals were explored under magnification. All root canals were prepared with an R25 Reciproc Blue system and sodium hypochlorite (NaOCl) irrigation. After initial preparation, a self-adjusting file (SAF) with NaOCl and ethylenediaminetetraacetic acid was used to complement the disinfection. Additionally, calcium hydroxide medication was applied. Vertical compaction was used to fill the canals with a calcium silicate-based endodontic sealer and gutta-percha. After 12 months, the patient exhibited healing of the periapical region, absence of symptoms, and normal dental function. In conclusion, this nonsurgical treatment protocol was successful in promoting the cure of apical periodontitis. Both complementary disinfection with an SAF and use of calcium hydroxide medication should be considered when choosing the best treatment approach for dens invaginatus with very complex anatomy.

• Journal of the korean academy of Pediatric Dentistry
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• v.27 no.1
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• pp.54-61
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• 2000

Amalgam, though a widely used dental material, does not bond to the tooth substrate Therefore, retentive preparation of the cavity is necessary. Such amalgam restorations, until corrosion products form and plug the margin, will show significant marginal leakage. Unless this is prevented early on, saliva and bacteria may enter the cavity causing postoperative hypersensitivity, dissolution and collapse of the restoration, discoloration of the margin and secondary caries, leading to shortened life-span of the restoration and pulpal pathosis. Recently, a method of restoration has been introduced whereby tooth material can be preserved, cavity margin can be sealed and preventive treatment of pit and fissure can be administered while retaining all the advantages of conventional amalgam restorations. Such sealed amalgams involve removing the carious lesion without extending the cavity for prevention and using pit and fissure sealants to seal cavity margins and pit and fissures to reduce microleakage. In this study, finishing of the amalgam and sealant application were performed after different intervals following of amalgam restoration to compare the microleakage of sealed and conventional amalgam restorations. Thirty bicuspids were prepared with Class V cavity preparations on the buccal and lingual surfaces. After amalgam placement, they were divided into the following groups and treated accordingly. Group 1 : Polishing after 24 hours Group 2 : Immediate sealant application without polishing Group 3 : No polishing, but sealant applied after thermocycling 500 times After treatment, the samples were thermocycled 500 times between $5^{\circ}C$ and $55^{\circ}C$ with a dwell time of 30 seconds. After thermocycling, the samples were dipped into 1% methylene blue kept in a $37^{\circ}C$ incubator at 100% humidity for 24 hours. The teeth were then embedded in resin and cut bucco-lingually along the tooth axis and observed with a stereomicroscope to determine the degree of microleakage, The following results were obtained : 1. Group 2 showed the least microleakeage, while group 1 showed the greatest. 2. Group 1 showed significantly greater microleakage compared to group 2 (p<0.05). However, no significant differences were found between group 1 and 3(p>0.05). No significant differences in microleakage were also found between cup 2 and 3(p<0.05).

• The korean journal of orthodontics
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• v.30 no.3 s.80
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• pp.317-333
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• 2000

The purpose of this study was to determine the proliferative activity of the osteoblasts and fibroblasts in the midpalatal area and to investigate the adjacent periodontal tissues of individual tooth following rapid expansion of the palate. Ten young adult dogs, aged approximately ten months, were used in the experiment. The experimental design was consisted of 1 week expansion group(Group E1, 3 dogs), 2 week expansion group(Group E2, 3 dogs), 2 week expansion and 2 week retention group(Group E3, 3 dogs), and control group(Group C, 1 dog). For each group, expansion screw was activated one time per day(1/4 turn;$90^{\circ}$) following Hyrax-screw application. The experimental animals in each group were sacrificed at 1, 2 and 4 weeks following palatal expansion. Maxillary tissue blocks were obtained and prepared ior the histomorphologic and immunohistochemical studies. Light mcroscope, polarizing microscope, and soft X-ray apparatus were used in this study, and following results were obtained. 1. In polarizing microscopic study, the expansion groups(E1 & E2) showed blue color representing bone resorption and new bone formation in midpalatal suture area. E3 groups skewed less blue color compared to the E1 and E2 group. But yellow color increased by calcification in the E3 groups. 2. Immunohistochemical study revealed that positive responses of the osteoblasts to PCNA and undifferentiated fibroblasts to EGF in E1 group were somewhat increased. Positive response to PCNA and EGF were increased in fibroblasts and the osteoblasts forming new bone in E2 group. In E3 group, the positive response cell concentrated the periphery of edge of palatal process in both PCNA and EGF. 3. Throughout the expansion period(E1 & E2), light microscopic study showed the edges of the extensive resorption and new palatal processes, indicating bone remodeling within the suture. E3 group exhibited less remodeling of midpalatal suture area. E2 group and E3 group showed cementum formation and resorption at the apex of 3rd premolar and 1st molar E3 group exhibited extensive hyalinized zone on the cervical portion of buccal side of 1st molar. 4. Soft X-ray analysis of E1 group showed hypomineralized defect and microfractures in various parts of the suture areas when compared with control animals. There was no significant difference in the degree of mineralization in the midpalatal suture region between the C and E3 groups. Tooth axis showed tipping of 3rd premolar and 1st molar in the E2 group and E3 group. Based upon these experimental results, it is concluded that the undifferentiated mesenchymal cells always presented in midpalatal suture area following RPE. Differentiated osteoblasts and fibroblasts possess proliferating cellular activity until the 2 week retention period. The posterior teeth are tend to tip buccally as RPE force applied. Retention group exhibited irreversible response with severe hyalinized zone on the buccal surface of the first molar.

• Restorative Dentistry and Endodontics
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• v.23 no.2
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• pp.537-549
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• 1998

The purpose of this study was to evaluate the influence of root resection and retrograde cavity preparation methods on the apical leakage in endodontic surgery. To investigate the effect of various root resection and retrograde cavity preparation methods on the apical leakage, 71 roots of extracted human maxillary anterior teeth and 44 mesiobuccal roots of extracted human maxillary first molars were used. Root canals of the all the specimens were prepared with step-back technique and filled with gutta-percha by lateral condensation method. Three millimeters of each root was resected at a 45 degree angle or perpendicular to the long axis of the tooth according to the groups. Retrograde cavities were prepared with ultrasonic instruments or a slow-speed round bur, and occlusal access cavities were filled with zinc oxide eugenol cement. Three coats of clear nail polish were placed on the lateral and coronal surfaces of the specimens except the apical cut one millimeter. All the specimens were immerged in 2% methylene blue solution for 7 days in an incubator at $37^{\circ}C$. The teeth were dissolved in 14 ml of 35% nitric acid solution and the dye present within the root canal system was returned to solution. The leakage of dye was quantitatively measured via spectrophotometric method. The obtained data were analysed statistically using two-way ANOVA and Duncans Multiple Range Test. The results were as follows: 1. No statistically significant difference was observed between ultrasonic retrograde cavity preparation method and slow-speed round bur technique, without apical bevel (p>0.05). 2. Ultrasonic retrograde preparation method showed significantly less apical leakage than slow-speed round bur technique, with bevel (p<0.0001). 3. No statistically significant difference was found between beveled resected root surface and non-beveled resected root surface, with ultrasonic technique (p>0.05). 4. Non-beveled resected root surface showed significantly less apical leakage than beveled resected root surface, with slow-speed round bur technique (p<0.0001). 5. No statistically significant difference in apical leakage was found between the group of retrograde cavity prepared parallel to the long axis of the tooth and the group of one prepared perpendicular to the long axis of the tooth (p>0.05). 6. Regarding isthmus preparation, ultrasonic retrograde preparation method showed significantly less apical leakage than slow-speed round bur technique, in the mesiobuccal root of maxillary molar, without bevel (p<0.0001).