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      • KCI등재

        AC4A 알루미늄 합금의 주조특성에 미치는 미량 첨가원소의 영향

        오승환,김헌주,Oh, Seung-Hwan,Kim, Heon-Joo 한국주조공학회 2017 한국주조공학회지 Vol.37 No.5

        The effects of minor additives on the casting properties of AC4A aluminum alloys were investigated. Measurements of the cooling curve and microstructure observations were conducted to analyze the effects of Ti-B and Sr minor elements during the solidification process. A fine grain size and an increase in the crystallization temperature for the ${\alpha}-Al$ solution were evident after the addition of 0.1wt% Al-5%Ti-1%B additive. The modification effect of the eutectic $Mg_2Si$ phase with the addition of 0.05% Al-10%Sr additive was prominent. A fine eutectic $Mg_2Si$ phase and a decrease in the growth temperature of the eutectic $Mg_2Si$ phase were evident. Fluidity, shrinkage and solidification-cracking tests were conducted to evaluate the castability of the alloy. The combined addition of Al-5%Ti-1%B and Al-10%Sr additives showed the maximum filling length owing to the effect of the fine ${\alpha}-Al$ grains. The macro-shrinkage ratio increased, while the micro-shrinkage ratio decreased with the combined addition of Al-5%Ti-1%B and Al-10%Sr additives. The macro-shrinkage ratio was nearly identical, while the micro-shrinkage ratio increased with the addition of the Al-10%Sr additive. The tendency of the occurrence of solidification cracking decreased owing to the effect of the fine ${\alpha}-Al$ grains and the modification of the $Mg_2Si$ phase with the combined addition of Al-5%Ti-1%B and Al-10%Sr additives.

      • KCI등재

        가토의 상악동 골이식술시 미분화 간엽 줄기세포의 골형성 효과

        오승환,채영원,김범수,여인범,조필귀,Oh, Sung-Hwan,Choi, Young-Won,Kim, Bum-Soo,Yeo, In-Bum,Jo, Pil-Kwy 대한악안면성형재건외과학회 2006 Maxillofacial Plastic Reconstructive Surgery Vol.28 No.6

        Undifferentiated mesencymal stem cells(UMSCs) have been thought to be multipotent cells that can replicate as undifferentiated cells and that have the potential to differentiate into lineages of mesenchymal tissue including the bone, cartilage, fat, tendon, muscle, and marrow stroma. It can be used to sinus lifting, Guided bone regeneration, other bone graft in dental part. The purpose of this study is to evaluate the effect of mesencymal stem cells on sinus augmentation with autogenous bone, fibrin glue mixture in a rabbit model. 8 New Zealand white rabbits were divided randomly into 4 groups based on their time of sacrifice(1, 2, 4 and 8 weeks). First, undifferentiated mesenchymal stem cells were isolated from iliac crest marrow of rabbits and expanded in vitro. cell culture was performed in accordance with the technique described by Tsutsumi et al. In the present study, The animals were sacrificed at 1, 2, 4 and 8 weeks after transplantation, and the bone formation ability of each sides was evaluated clinically, radiologically, histologically and histomorphologically. According to the histological observations, Stem cell group showed integrated graft bone with host bone from sinus wall. At 2 and 4weeks, It showed active newly formed bone and neovascularization. At 8 weeks, lamella bone was observed in sinus graft material area. Radiologically, autobone with stem cell showed more radiopaque than autobone without stemcell. there were significant differences in bone volume between 2 and 4 weeks (p<0.05). In summary, the autobone with stem cells had well-formed, newly formed bone and neovasculization, compared with the autobone without stem cells (esp. 2 weeks and 4 weeks) The findings of this experimental study indicate that the use of a mixture of mesenchymal stem cell yielded good results in osteogenesis and bone volume comparable with that achieved by autogenous bone. Therefore, this application of this promising new sinus floor elevation method for implants with tissue engineering technology deserves further study.

      • SCOPUSKCI등재
      • KCI등재

        Thin Block and Chip Bone Graft Technique을 이용한 치조골 수직 증강술 : 증례보고

        오승환,Oh, Sung-Hwan 대한악안면성형재건외과학회 2008 Maxillofacial Plastic Reconstructive Surgery Vol.30 No.1

        It would be desirable to regenerate bone vertically in a predictable way; such a technique would allow for more favorable implant - crown ratio and better esthetics for implant placement. Traditionally, several techniques has been proposed for this purpose including GBR with particulated bone and block bone graft using mandible or illium however, the efficacy of these techniques has not been firmly established because they have some week points or complications each other that it is difficult to draw firm conclusion for superiority. In recent years, We have treated 11-cases of vertical deficiency of alveolar bone using thin block and chip bone graft technique and the postoperative results showed good prognosis with few complications. So we report the results of its treatment and cases with review of literature.

      • KCI등재

        악교정 수술 중 발생한 지연성 악성 고열증의 치료

        오승환,민승기,권경환,조필귀,송윤강,Oh, Sung-Hwan,Min, Seung-Ki,Kwon, Kyung-Hwan,Jo, Pil-Kwy,Song, Yun-Kang 대한악안면성형재건외과학회 2005 Maxillofacial Plastic Reconstructive Surgery Vol.27 No.4

        Malignant hyperthermia is a catastrophic, hypermetabolic syndrome that arises in susceptible individuals when they are exposed to certain inhalational anesthetics or muscle relaxants. It is characterized by hyperthermia, tachycardia, acidosis, and muscle rigidity. It has been noted that the majority of cases of malignant hyperthermia are fatal unless early diagnosis and treatment are performed. We experienced a 24 year old male Malignant hyperthermia presented for orthognathic surgery under $O_2-N_2O$-sevoflurane anesthesia without succinylcholine. Two half hours after induction, tachycardia developed and was followed by unstable blood pressure and hyperpyrexia. Anesthesia was terminated and vigorous emergency treatment was attempted. The patient was treated by the intravenous administration of dantrolene sodium. The diagnosis of an acute malignant hyperthermia reaction by clinical criteria can be difficult because of the nonspecific nature and variable incidence of many of the clinical signs and laboratory findings. So the malignant hyperthermia clinical grading scale is recommended for use as an aid to the objective definition of this disease. This clinical grading system provides a new and comprehensive clinical case definition for the malignant hyperthermia syndrome. We recently encountered a case of delayed malignant hyperthermia during sevoflurane anesthesia that was successfully treated by the intravenous administration of dantrolene sodium. In conclusion, exposure to sevoflurane should be avoided in patients thought to be susceprible to malignant hyperthermia.

      • KCI등재

        하악우각부골절에서 제3대구치의 역할에 관한 통계적 연구

        오승환,Oh, Sung-Hwan 대한악안면성형재건외과학회 1998 Maxillofacial Plastic Reconstructive Surgery Vol.20 No.3

        Purpose : This study attempted to relate the incidence of fractures at the mandibular angle with the presence and state of eruption of lower third molars, and to find out the real risk factors for angle fractures in the states of lower third molars. Materials and Methods : Medical records and radiographs of 395 patients with mandibular fractures were retrospectively reviewed. The presence and states of third molars were assessed for each patients and related to the occurrence of angle and other mandibular fractures. Results : Of 395 patients with mandibular fractures, 142 had angle fractures. The incidence of angle fractures was found to be significantly greater when partial erupted lower third molars were present and it had a definite role for risk factors for angle fractures. But there were no clear relationship between the incidence of angle fracrtures and states of without, fully erupted lower third molars. Furthermore, the states of patial and unerupted lower third molar had an effect on bony segment displacement. Conclusions : This study provides clinical evidence to suggest that patial erupted third molar teeth weaken the mandibular angle both quantitatively and qualitatively.

      • KCI등재

        장골과 경골의 자가입자망상골 이식에 관한 임상적 비교연구

        오승환,Oh, Sung-Hwan 대한악안면성형재건외과학회 1998 Maxillofacial Plastic Reconstructive Surgery Vol.20 No.3

        This is a clinical and retrospective study of 36 patients received the autogenous particulated cancellous bone grafts from anterior iliac and proximal tibial metaphysis and we compared the clinical postoperative complications in operation sites and donor site morbidity. The results of this study indicate that, in all our patients, the proximal tibia provided an adquate volume of cancellous bone and there were no special contraindications, in choosing and using the proximal tibia as a donor site in most oral and maxillofacial cancellous bone graft surgeries. Furthermore, the proximal tibial metaphysis would appear a more easily obtainable cancellous bone source and offer a superior clinical results than anterior iliac crest in donor site morbidity.

      • 지능형 주거 공간을 위한 24시간 연속적인 건강 모니터링 시스템 구현

        오승환,이희영 전남대학교 전자통신기술연구소 2001 전자통신기술논문지 Vol.4 No.1

        This paper presents a wireless potable telemetry healthcare monitoring system with the characteristics of small size (42mmx75mmx15mm) and low power consumption (90mw) for the elderly and the disabled. The healthcare system consists of a measurement device, a diagnosis S/W and a user interface S/W. The measurement device is designed according to the international specifications of the recommendation of AAMI (Association for the Advancement of Medical Instrumentation). The measurement device has the functions that adjust gain and cut-off frequency to acquire various bio-signals such as ECG, EMG and EEG. It has wireless communication using Bluetooth to send a data between a host computer and other device.

      • KCI등재후보

        미래 전력발전을 위한 종합전투실험체계 개념설계 연구

        오승환,홍윤기,Oh, Seung-Hwan,Hong, Yoon-Gee 한국국방경영분석학회 2010 한국국방경영분석학회지 Vol.36 No.3

        이 연구는 복합시스템 구축과 소요제기 결정에 활용하기 위하여 복합시스템 엔지니어링과 아키텍처 방법론으로 개발한 복합시스템 개념설계 모형을 제시하고 있으며, 모형의 검증은 Process Transition Map, 전문가 설문기법으로 수행하였다. 또한 미래 전력발전에 활용할 수 있도록 종합전투실험체계에 대한 개념설계를 프로세스 단계별 산출물을 작성하여 제시하였다. This Study proposes that a SoS(System of Systems) Conceptual Design Model which is developed for the SoS establishment, requirement and decision, utilizing SoS engineering and architecture methodology, and the Model performed with the Process Transition Map using subject matter expert survey. Establishing an Integrated Battle Experimentation System(IBES) for the future force development, the process product of IBES was conceptually designed using a SoS Conceptual Design Model.

      • KCI등재

        TG Osseotite 임플란트의 성공률에 대한 임상적 연구

        오승환,민승기,채영원,Oh, Sung-Hwan,Min, Seung-Ki,Chae, Young-Won 대한악안면성형재건외과학회 2005 Maxillofacial Plastic Reconstructive Surgery Vol.27 No.1

        The purpose of this study is to review the prognosis of the TG Osseotite implant(3i Co, USA) placed in partial edentulous area of oral cavity and to suspect the possible causes leading to failure. 124 TG Osseotite implants that had been inserted between 2000 - 2002 were followed up for 2 years(avg : 9.5 months) in function. Medical records, and radiographs were evaluated and analyzed by the over all success rate, gender and age factor, general disease, implant fixture length and diameter, implant site, bone density, and various surgical methods. Chi square test was used statistically. Of the 124 TG Osseotite implants, 9 implants(7.3%) were removed in early phase and 3 implants(2.4%) were in late phase. The cumulative survival rate was 90.2%. The failure of the TG Osseotite implant was closely related with the use of bone graft techniques such as sinus elevation or immediate implantation and not with the age, sex, general disease, implant site, bone density of implanted site. The failure of the TG Osseotite implant was well developed when it was the wide type of implant and it was inserted for single tooth replacement. The developement of peri-implantitis was the most important factor in the failure of the TG Osseotite implant.

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