Uniform Stability of Intervalwise Receding Horizon Controls for Linear Time-Varying Systems

김기백(Ki Baek Kim),권욱현(Wook Hyun Kwon) 대한전기학회 1997 대한전기학회 학술대회 논문집 Vol.1997 No.11

미성숙 상악 영구 중절치에서의 치근파절 치험례

김기백,김선미,최남기,양규호,Kim, Ki-Baek,Kim, Seon-Mi,Choi, Nam-Ki,Yang, Kyu-Ho 대한소아치과학회 2007 大韓小兒齒科學會誌 Vol.34 No.3

성장 발육중인 어린이나 청소년에서 치아에 가해지는 외상성 손상은 성인에 비하여 흔히 일어난다. 외상이 일어난 후부터 적절한 치료가 시행될 때까지 소요된 시간은 특히 예후를 결정하는데 중요한 요소이며, 외상성 치아 손상을 입은 환자를 검사하고 치료하는데 사용되는 시간이 제한되어 있기 때문에, 만약 적절한 치료가 시간 내에 시행되지 않는다면 환자에게 심각한 결과를 초래할 수 있다. 이전 연구들에 의하면, 외상의 발생율은 8-10세 아이들에게서 가장 흔하고, 가장 많이 이환된 치아는 상악 영구 중절치이며, 남자의 경우가 여자보다 2:1로 빈도가 높았다. 상악 중절치의 치근 완성시기는 평균 10세 정도로 알려져있다. 외상성 손상에 이환된 호발 연령대의 상악 영구 중절치는 대부분 발육중인 미성숙된 치아로, 혈류공급이 왕성하여 손상시 재혈관화에 의한 치유가 비교적 쉽게 일어날 수 있어 치수 생활력에 대한 긍정적인 예후가 기대될 수 있다. 본 증례는 외상성 손상을 받은 미성숙 상악 영구 중절치의 치근파절 치험례로, 통상적인 근관치료를 하지 않고 보존적인 술식을 통하여 치아의 생활력을 유지할 수 있었기에 그 치료 경과 및 결과를 보고하는 바이다. Traumatic dental injuries in childhood and adolescent occurred more frequently than in adult. The time between the accident and the treatment is one of the most critical factors to prognosis, and because of the limited time available to examine and treat patients with traumatic dental injuries, if not treat appropriately, the result would be critical for the patient. In the previous studies, the prevalence and incidence of traumatic injuries were the most frequent at the age of 8 to 10 years, the majority of dental injuries involve the anterior teeth, especially the maxillary incisors, and males were more prevalent than females in an approximated proportion of 2:1. As the mean age of complete root formation is 10 years old, the maxillary permanent incisor involved in the most affected age group is usually immature, and the possibility of pulpal healing through excellent revascularization exists, more positive prognosis for pulp vitality would be expected. These are treatment cases of the immature maxillary permanent central incisor involved in the traumatic injury, and reports for progress and results of preserving the pulp vitality through the conservative treatment instead of the conventional endodontic root therapy.

해외 치과기공물 서비스 수출 전략모형 제안

김기백(Ki-Baek Kim),김주환(Joo-Hwan Kim),김재홍(Jae-Hong Kim) 한국콘텐츠학회 2013 한국콘텐츠학회논문지 Vol.13 No.7

본 연구의 목적은 해외 치과기공물 서비스 수출을 연구하는 것으로서, 우리나라 및 해외 치과기공물 서비스의 현황분석, 그리고 해외 진출 시 문제점과 진출 전략을 제시하였다. 세계화와 정보화 추세의 진전으로 의료서비스시장 규모가 점점 커지고 있으며, 의료 서비스시장은 질이 가장 중요시 되는 고부가가치의 서비스산업이라는 새로운 인식하에 시장 개발과 고용창출을 이루려는 각국의 노력과 함께 급부상하며 유망산업분야로 떠오르고 있다. 고부가가치의 의료서비스 산업을 해외 시장으로 확장 발전시키기 위하여, 결론적으로 첫 번째 의료서비스의 해외진출과 글로벌화 강화, 두 번째는 전문화를 통한 의료서비스의 고급화, 마지막으로 전문경영체제 구축 및 의료 서비스 시스템 혁신이 필요하다. The purpose of this study is to research how to effectively export the dental prosthetic restoration and the service to the overseas. The study showed the present status of dental prosthetic restoration service in South Korea and some suggested ways to improve the export of the dental prosthetic restoration service to the overseas. The size of the medical service market has been gradually increased because of the globalization and the development of the information-oriented tendency. The medical industry is being perceived as a highly valuable service industry that emphasizes the importance of quality. Through the efforts of the nations attempting to develop the market and create new employment, the medical field is becoming a prospective field of trade. In order to develop the medical industry, the strategies; firstly, medical institutions need to explore overseas markets and strengthen globalization; secondly, medical service should be upgraded through specialization; and finally, specialized management system has to be established and medical management system has to be innovated.

치과용 탄성 인상재를 기반으로 채득된 디지털 모형의 정확성 연구: 3차원 중첩 분석

김기백 ( Ki Baek Kim ),정재관 ( Jae Kwan Jung ),김재홍 ( Jae Hong Kim ) 한국치위생과학회 2014 치위생과학회지 Vol.14 No.2

The purpose of this study was to evaluate the accuracy of digitized elastomeric impression materials of crown abutment, using non-contact white light scanner and virtual three-dimensional superimpositional analysis. The stone models and impressions were digitized white light scanner to create three-dimensional surface models. Stone models were used as CAD reference model (CRM). The resulting point clouds (ASC file) from digitization of impressions using converting software. Discrepancies between the points in the point clouds and CRM were measured by superimpositional software. Mean and standard deviation of values of discrepancies were analyzed by one-way ANOVA and multiple comparison (α=0.05). The mean discrepancy between the impressions for the extra-light body (XLB), light body (LB), and heavy body (HB) group were 5.10±1.45 μm, 6.30±1.87 μm, 9.80±1.52 μm, respectively. The different impression materials affected the digitization of impressions significantly (p<0.05). As a result, digitization of elastomeric impression materials on dental scanner was influenced by material sort.

도재 소성과정이 Ni-Cr 금속도재관의 변연 및 내면 적합도에미치는 영향

김기백 ( Ki Baek Kim ),김석환 ( Seok Hwan Kim ),김재홍 ( Jae Hong Kim ) 한국치위생과학회 2014 치위생과학회지 Vol.14 No.3

The purpose of this study in vitro investigation was to compare the marginal and internal fit of Ni-Cr alloy metal ceramic crown before and after porcelain veneering. Furthermore, this study evaluated whether the influence of the porcelain firing on the precision of fit of dental prostheses. The maxillary right incisor was selected as an abutment for experiments. Ten working models were prepared. Ni-Cr alloy cores appropriate for each abutment were prepared by lost wax technique. The marginal area and four internal areas of the crowns were measured at two stages: before veneering process and after upper porcelain firing. Silicone replica techniques were used. The data were statistically analyzed with the paired t-test(α=0.05). Mean±SD marginal and internal gap were 67.1±23.3 μm for the nickle chrome alloy core group and 74.4±21.9 μm for the metalceramic crown group. There were statistically significant differences in all investigated areas (p<0.05). Within the limitations of this study, none of the Ni-Cr alloy metal crown values measured after porcelain firing process exceeded 120 μm, which is the clinically acceptable threshold.

지대치 형태에 따른 지르코니아 코어의 변연 적합도

김기백 ( Ki Baek Kim ),김석환 ( Seok Hwan Kim ),김재홍 ( Jae Hong Kim ) 한국치위생과학회 2015 치위생과학회지 Vol.15 No.1

The present study investigated the influences of various abutment teeth shapes (maxillary right canine, pre-molar, molar) on the marginal adaptation of computer aided design/computer aided manufacturing-fabricated zirconia core. In vitro adaptation of zirconia cores manufactured by three different abutments were evaluated. Thirty zirconia cores were made per each models and the adaptation was evaluated through a silicone replica technique. The measurement of the adaptation was carried out using digital microscope. The mean and standard deviation of each reference point were analyzed using the one-way (ANOVA) and Tukey’s honestly significant difference tests (α=0.05). The overall marginal fits of the zirconia cores were as follows: canine: 47.59 μm, pre-molar: 43.74 μm, molar: 40.36 μm. They were no statistically significant differences between groups for adaptation (p>0.05). This confirmed that the type of abutment teeth used does not determine the precision of fit of zirconia core.

저온열화현상이 지르코니아 코어와 전장도재의 전단결합강도에 미치는 영향

김기백 ( Ki Baek Kim ),김재홍 ( Jae Hong Kim ) 한국치위생과학회 2014 치위생과학회지 Vol.14 No.1

본 연구는 최근 심미보철물 제작에 널리 사용되는 지르코니아의 저온열화가 수복물의 안정성 및 내구성에 영향을 미치는 여부를 확인하기 위하여 전단결합강도를 측정하였다. 디스크 형태의 시편을 각각 7개씩 제작한 후 전장도재를 축성하여, ISO 13356 규격에 의거한 조건으로 고압증기 멸균기에 저온열화의 정도를 조절하기 위하여 3, 5, 10시간 동안 수열처리를 진행하였다. 제한된 조건하에 시행된 실험을 통해 전단결합강도를 확인하였으며, 측정 후 파절양상을 관찰하였다. 저온열화 처리 전후의 시편에 대한 전단결합강도의 변화는 각 실험군별 유의한 차이가 있었다(p<0.05). 10시간을 저온열화 처리한 시편이 가장 낮은 전단결합강도로 나타났으며, 처리시간이 길어질수록 전단결합강도가 낮아지는 경향을 보였다. 파절 양상으로 저온열화 처리를 하지 않은 시편에서 응집성 파절을 보였으며, 저온열화 처리가 길어질수록 혼합형 파절 경향으로 전환되었다. 결론적으로 본 연구는 저온열화 현상이 진행될수록 지르코니아 코어와 전장도재 간의 결합강도가 낮아지는 경향을 확인하였다. 본 실험결과를 토대로 치과용 지르코니아를 이용한 보철물 제작과정과 환자에게 장착 후 안정적인 사용을 위하여 저온열화 현상에 대한 주의가 필요할 것으로 생각된다. The purpose of this study was to evaluate the influence of low temperature degradation (LTD) on the bonding strength of yttria-stabilized tetragonal zirconia polycrystal (Y-TZP). The push-shear bond test method was used to investigate the core-veneer bonding strength of industrially manufactured Y-TZP core ceramic and manufacturer recommended veneering ceramic. Four groups from ceramic-zirconia specimens (n=28; n=7 per group) were assigned into four experimental aging conditions, namely storage in an autoclave at 134℃ for 0, 3, 5, 10 hours. Bonding strength was obtained using a universal testing machine with crosshead speed 0.5 mm/min. Data were statistically analyzed using one-way ANOVA and Tukey.s test (α=0.05). In bonding strength test, the group which was treated with LTD showed lower bonding strength than no treated group. The ceramic-zirconia bonding strength was affected by LTD (p<0.05). Digital microscope examination of the fracture surface showed mixed failures with adhesive and cohesive types in LTD with treated Y-TZP groups.

[수정기사] 샌드블라스팅 처리와 라이너가 지르코니아와 전장도재의 전단결합 강도에 미치는 영향

김기백,김재홍,Kim, Ki-Baek,Kim, Jae-Hong 대한치과기공학회 2021 대한치과기공학회지 Vol.43 No.2

샌드블라스팅 처리와 라이너가 지르코니아와 전장도재의 전단결합 강도에 미치는 영향

김기백,김재홍,Kim, Ki-Baek,Kim, Jae-Hong 대한치과기공학회 2021 대한치과기공학회지 Vol.43 No.1

Purpose: This study aimed to compare the shear bond strength between zirconia cores and veneer ceramics as per the sand blasting and liner treatments. Methods: The following 4 groups of zirconia-veneering ceramic specimens were prepared: (1) Group I, untreated; (2) Group II, with 110 ㎛ aluminium oxide (Al2O3) sandblasting; (3) Group III, with liner (IPS e.max ZirLiner; Ivoclar Vivadent); and (4) Group IV, with 110 ㎛ Al2O3 sand blasting and liner. Surface roughness was measured for all the prepared specimens, and the surface morphology was observed using a scanning electron microscope. All the samples (n=40) were fixed with measuring jigs, and shear bond strengths were obtained using a universal testing machine with a crosshead speed of 0.5 mm/min. The shear bond strength data were analyzed using one-way analysis of variance and t-test. The post hoc comparison was performed using the Tukey's test (α=0.05). Results: A significant difference in the surface roughness was observed between the specimens of groups I and II (p<0.05). Surface treatment with liner and sandblasting showed higher shear bond strength between zirconia core and veneering ceramic (p<0.05). Conclusion: The sand blasting and liner treatment increased the shear bond strength between zirconia core and veneering ceramic.

고온에서의 예혼합 초소형 화염의 연소안정한계 연구

김기백,이경호,홍영택,권오채,Kim, Ki-Baek,Lee, Kyoung-Ho,Hong, Young-Taek,Kwon, Oh-Chae 한국수소및신에너지학회 2006 한국수소 및 신에너지학회논문집 Vol.17 No.2

In order to provide the database for designing microcombustors, the combustion characteristics of premixed methane and propane air microflames at normal and elevated temperatures and atmospheric pressure generated on a microtube were studied experimentally and computationally. The stability limits of premixed microflames and the propensity of the microflames near the stability limits were experimentally determined, while the structure of the microflame at the fuel-leanest limit was obtained using a two-dimensional CFD simulation with a reduced kinetic mechanism. For all the microflames, the stability limits were observed only in the fuel-rich region. Results also show substantial extension of stability limits with elevated temperature that is realistic condition for micro fuel processing and significant fuel dilution immediately near the tube exit due to a low Peclet number times Lewis number effect.