• The Journal of Korean Academy of Prosthodontics
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• v.55 no.3
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• pp.286-291
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• 2017

Maintaining the blood supply of the interdental alveolar bone is crucial for preserving the interdental papilla. Rebuilding the interimplant papilla between adjacent implants is more difficult than rebuilding the interdental papilla between the natural tooth and implant. Therefore, preserving the interimplant tissue is necessary when adjacent implants are closely placed. In this case report, three effective methods for maintaining the surrounding tissue, namely strategic serial extraction, immediate implantation, and provisionalization of adjacent maxillary central incisors, were performed. The marginal gingiva and interimplant papilla were well maintained for 24 months.

• Journal of the korean academy of Pediatric Dentistry
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• v.43 no.4
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• pp.401-409
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• 2016

This research investigates into overall oral health status of adolescent girl inmates in a juvenile detention facility and ordinary school students in the same age range of 11 to 18 years old and compares the results focusing on the difference between the two groups. The last 5 years dental records for girl inmates in Juvenile detention facility and for students who have visited the Department of Pediatric Dentistry at Ajou University Hospital was colleted and analyzed. The restorative treatments took up the greatest part in their history of treatments. While the percentage of extractions of permanent teeth due to dental caries had been gradually increased, in Juvenile detention facility students, throughout the transition period from middle school to high school, in dental hospital patients, the phenomenon of the same kind has hardly been detected. After that record analysis, oral examination for Juvenile detention facility students and dental hospital patients was conducted. DMFT index for dental hospital patients are 4.15, whereas, the value for Juvenile detention facility students are as twice as high to be 7.53.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.30B no.9
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• pp.94-105
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• 1993

In this paper propose a Koaren character recognition system using a neural network is proposed. This system is a multilayer neural network based on the masking field model which consists of a input layer, four feature extraction layers which extracts type, direction, stroke, and connection features, and an output layer which gives us recognized character codes. First, 4x4 subpatterns of an NxN character pattern stored in the input buffer are applied into the feature extraction layers sequentially. Then, each of feature extraction layers extracts sequentially features such as type, direction, stroke, and connection, respectively. Type features for direction and connection are extracted by the type feature extraction layer, direction features for stroke by the direction feature extraction layer and stroke and connection features for stroke by the direction feature extraction layer and stroke and connection features for the recongnition of character by the stroke and the connection feature extractions layers, respectively. The stroke and connection features are saved in the sequential buffer layer sequentially and using these features the characters are recognized in the output layer. The recognition results of this system by tests with 8 single consonants and 6 single vowels are promising.

• Journal of Internet Computing and Services
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• v.4 no.3
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• pp.39-46
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• 2003

Generally, the existing watermarking techniques for copyright protection of a digital image are fragile in geometric distortion and all watermark extractions need the same time regardless of degree of distortion. In this paper, we propose the incremental watermarking technique that used a Complex Wavelet Transform(CWT) in order to solve these problems. The proposed incremental watermarking technique embeds a watermark in a phase component after a CWT with an original image, and a watermark is extracted from an watermarked image by stages. A watermark owner can insist on copyright of an image after comparing a correlation between the extracted watermark and the original watermark if it is larger than the threshold. Also, the incremental watermark extraction determines the extraction time of a watermark by the level of distortion. The proposed technique through performance evaluation displayed that it was robust in geometric distortion than the existing watermarking technique.

• The korean journal of orthodontics
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• v.44 no.5
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• pp.236-245
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• 2014

Objective: To evaluate the therapeutic effects of a preformed assembly of nickel-titanium (NiTi) and stainless steel (SS) archwires (preformed C-wire) combined with temporary skeletal anchorage devices (TSADs) as the sole source of anchorage and to compare these effects with those of a SS version of C-wire (conventional C-wire) for en-masse retraction. Methods: Thirty-one adult female patients with skeletal Class I or II dentoalveolar protrusion, mild-to-moderate anterior crowding (3.0-6.0 mm), and stable Class I posterior occlusion were divided into conventional (n = 15) and preformed (n = 16) C-wire groups. All subjects underwent first premolar extractions and en-masse retraction with preadjusted edgewise anterior brackets, the assigned C-wire, and maxillary C-tubes or C-implants; bonded mesh-tube appliances were used in the mandibular dentition. Differences in pretreatment and post-retraction measurements of skeletal, dental, and soft-tissue cephalometric variables were statistically analyzed. Results: Both groups showed full retraction of the maxillary anterior teeth by controlled tipping and space closure without altered posterior occlusion. However, the preformed C-wire group had a shorter retraction period (by 3.2 months). Furthermore, the maxillary molars in this group showed no significant mesialization, mesial tipping, or extrusion; some mesialization and mesial tipping occurred in the conventional C-wire group. Conclusions: Preformed C-wires combined with maxillary TSADs enable simultaneous leveling and space closure from the beginning of the treatment without maxillary posterior bonding. This allows for faster treatment of dentoalveolar protrusion without unwanted side effects, when compared with conventional C-wire, evidencing its clinical expediency.

• Imaging Science in Dentistry
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• v.47 no.1
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• pp.45-50
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• 2017

Purpose: The aim of this study was to investigate the incidence of bisphosphonate-related osteonecrosis of the jaw (BRONJ) after tooth extraction in patients with osteoporosis on oral bisphosphonates in Korea and to evaluate local factors affecting the development of BRONJ. Materials and Methods: The clinical records of 320 patients who underwent dental extraction while receiving oral bisphosphonates were reviewed. All patients had a healing period of more than 6 months following the extractions. Each patient's clinical record was used to assess the incidence of BRONJ; if BRONJ occurred, a further radiographic investigation was carried out to obtain a more definitive diagnosis. Various local factors including age, gender, extraction site, drug type, duration of administration, and C-terminal telopeptide (CTx) level were retrieved from the patients' clinical records for evaluating their effect on the incidence of BRONJ. Results: Among the 320 osteoporotic patients who underwent tooth extraction, 11 developed BRONJ, reflecting an incidence rate of 3.44%. Out of the local factors that may affect the incidence of BRONJ, gender, drug type, and CTx level showed no statistically significant effects, while statistically significant associations were found for age, extraction site, and duration of administration. The incidence of BRONJ increased with age, was greater in the mandible than the maxilla, and was associated with a duration of administration of more than 3 years. Conclusion: Tooth extraction in patients on oral bisphosphonates requires careful consideration of their age, the extraction site, and the duration of administration, and close postoperative follow-up should be carried out to facilitate effective early management.

• Journal of The Korean Dental Society of Anesthesiology
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• v.12 no.4
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• pp.229-233
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• 2012

Hemophilia, the most common of the inherited bleeding disorder, is the result of a deficiency of clotting factor. Since bleeding after dental treatment may cause severe or even fatal complications, people with hemophilia must be given special dental care. We report on the diagnosis and treatment of a 9-year-old boy having severe hemophilia visited our department with the chief complaints of pus discharge on the left lower molar region. In the clinical and radiographic examination, periapical abscess and dental caries were diagnosed. Considering complexity of the treatment and complication in the coagulation, it was decided to carry on the treatment under general anesthesia. Clotting factor IX concentrates were intended to provide 50-70% plasma level. Pulpectomy, resin restoration and Stainless steel crown were given under general anesthesia. Several teeth were extracted and the sockets were packed with Surgicel$^{(R)}$ (Oxidized Regenerated Cellulose, Johnson and Johnson Co. Neuchatel, Switzerland) under general anesthesia. Transpalatal arch and lingual arch were given for maintaining the extracted space before discharged. For people with severe hemophilia, factor replacement is necessary before scaling, surgery or regional block injections. Therefore, if several extractions are needed, dental care under general anesthesia would be effective and efficient management.

• KSBB Journal
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• v.25 no.3
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• pp.205-214
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• 2010

Many successive liquid-liquid extractions occur enabling purification of the crude material to occur. In high performance counter-current chromatography (HPCCC), crude material is partitioned between two immiscible layers of solvent phases. The stationary phase (SP) is retained by hydrodynamic force field effect and the mobile phase (MP) is pumped through the column. Purification occurs because of the different solubility of the components in the liquid mobile and stationary phases. There are many key benefits of liquid stationary phases such as high mass and volume injection loadings, total sample recovery, and easy scale-up. Many researchers showed that predictable scale-up from simple test is feasible with knowledge of the stationary phase retention for the planned process scale run. In this review we review the recent advances in HPCCC research and also describe the key applications such as natural products and synthetics (small or large molecules).

• Korean Journal of Environmental Agriculture
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• v.32 no.3
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• pp.171-178
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• 2013

BACKGROUND: Consensus of heavy metal phytoavailability in soils needs to be introduced for soil management protocols in relation to safer food production in the contaminated agricultural soils. For this, setting up the method for evaluation of metal phytoavailability in soil is an essential prerequisite. METHODS AND RESULTS: The current study was carried to select a proper single extraction method for determination of phytoavailable metal concentration in soil. Two extraction methods were examined including 1 M $NH_4NO_3$ extraction and 0.01 M $Ca(NO_3)_2$ extraction methods using 142 soil samples collected from the agricultural soils nearby abandoned mining area in Korea. Corelation analysis was conducted between phytoavailable metal concentrations and soil properties potentially influencing on the metal phytoavailability. Both methods showed similar significance (p<0.001) in correlation with soil properties such as soil pH. However, higher correlation coefficients between phytoavailable metal concentrations and soil properties were observed when used $Ca(NO_3)_2$ extraction rather than using $NH_4NO_3$ extraction. CONCLUSION(S): It appeared that 0.01 M $Ca(NO_3)_2$ extraction was better option for determination of phytoavailable metals in soils and further study to test the efficiency of this method is required in combination with plant uptake.

• Applied Chemistry for Engineering
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• v.7 no.5
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• pp.977-984
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• 1996

Liquid-liquid extractions by use of hollow fiber membrane module are fast because of the large surface area per volume. In these membranes, the extractant and feed can be contacted at high speed and two flows are completely independent, so there are no problems with loading and channeling. In this paper, it was investigated the selectivities of extractants for extraction of heavy metals from aqueous solution into organic extractants by using the hollow fiber membrane. To identify the effect of distribution ratio on mass transfer in the membrane, we also compared the distribution ratio with mass transfer coefficient. From these experiments for the system with high distribution ratio, effect of the distribution ratio on mass transfer was weak compare with the low distribution ratio system in the hollow fiber membrane.