High-Q 능동여파기를 이용한 마이크로파 발진기의 위상잡음 개선에 관한 연구

학위논문(석사)--서울대학교 대학원 :전기·컴퓨터공학부,2002.Maste

손실매질에서 안테나의 전력전송 특성에 관한 연구

Thesis(doctors) --서울대학교 대학원 :전기. 컴퓨터공학부, 2008.8.Docto

The Influence of trauma to the primary teeth on their permanent successors

학위논문(박사)--서울대학교 대학원 :치의학과 소아치과학전공,1995.Docto

TAT-BMP의 생체 내 적용을 위한 전달체 발굴 및 평가

Dept. of Dentistry/박사Although the need for bone regeneration is gradually increasing due to aging, clinical modality is not yet definite. Exogenous growth factors, like bone morphogenetic proteins (BMPs) should have sufficient bioactivity and be in harmony with the carrier system by controlled release of biological factors with mechanical support. Recombinant human BMP-2 (rhBMP-2) are currently used in clinics, but their efficacy remains obscure.Contrary to soluble hydrophilic rhBMP-2, inactive form TAT-BMP-2 fusion protein has a hydrophobic nature that requires an appropriate scaffold system toward in vivo application. In this regard, this study aims to explore the most proper scaffold among collagen, fibrin and hydrogel, which all have in-vivo biocompatibility, biodegradability by evaluating bone regeneration efficacy when combined with TAT-BMP-2 in the critical sized defect of a rabbit skull. Also, chemical residues of the most excellent scaffold,hydrogel, were detected by several methods to proceed into preclinical study. The results are as follows:1. The bone regeneration efficacy of hydrogel and collagen were in themselves comparable.2. 5μg of the TAT-BMP-2 and hydrogel composite induced 50% more efficient bone regeneration than blank, collagen and fibrin. Also it exhibited the most superior bone mineral density.3. Fibrin seemed to inhibit osteoinduction. Furthermore, the TAT-BMP-2 fibrin composite did not demonstrate significant bone regeneration compared to control or other experimental groups.4. The concentration dependency of the TAT-BMP-2 and hydrogel composite in bone regeneration needs further investigation.5. The elution buffer of hydrogel contained EDC and TCEP, which needs to be removed by serial dialysis.These results indicated that TAT-BMP-2 hydrogel composite showed the most effective in vivo mode of action to deliver secretory growth factors. Further treatments to remove the chemical residues in hydrogel should be done to move forward clinical application.ope

산업적 호스트를 이용한 미생물 유래의 파이테이즈 유전자의 기능적 발현에 관한 연구

Thesis (master`s)--서울대학교 대학원 :농생명공학부,2003.Cereals, legumes, and oilseed crops are grown in over 90% of the world''s harvested area. These crops serve as a major source of nutrients for humans and animals. An important constituent in these crops is phytic acid(myo-inositol hexaphosphate). the salt form, phytate, is the major storage form of phosphorus and accounts for more than 80% of the total phosphorus in creals and legumes. Phytase is an enzyme capable of hydrolyzing phytic acid to less-phosphorylated myo-inositol derivates. Monogastric animals, such as pig, poultry and fish, are not able to metabolized phytic acid, and therefore inorganic phosphate is added to their diets to safety the phosphorus requirement. This consequently contributes to phosphorus pollution problems in areas of intensive livestock production. Phytic acid also acts as an anti-nutritional agent in monogastric animals by chelating various metal ions needed by the animal, such as calcium, copper, and zinc. Therefore the enzymatic hydrolysis of phytic acid into less phosphorylated myo-inositol derivatives in the intestine of monogastric animals is desirable. Many attepts to enzymatically hydrolyze phytic acid have been made to improve the nutitional value of feed and to decrease the amount of phosphorus excreted by animals. So, this study was conducted to construct the recombinant phytase gene from Pseudomonas syringae MOK1 and Penicillium oxalicum PJ3 with commercial vectors in industrial hosts and to characterize the recombinant proteins. 1. Psudomonas syringae MOK1 genes with pET vector were transfored into E. coli BL21(DE3). 2. Transformed cells were induced by IPTG, after 6 h the cell extract were assayed phytase activity. The result of phytase activity was about 0.4 U/ml 3. Penicillium oxalicum PJ3 phytase gene with pPICZ¥áA vector were transfored into P. pastoris GS115 Mut+. 4. Recombinant phytase activity was increased steadily up to 120 h after the methanol induction and cell growth pattern was also similar to increase ratio of phytase activity. 5. The enzyme had a optimum pH of 4.5, and showed over 70% of the maximum activity in the pH range of 3.7-5.0. The optimum temperature for the enzyme activity was 55¡É, and showed over 70% of the maximum activity in the broad temperature range of 38-61¡É. 6. The specific activity of the purified enzyme was 306.62U/mg of protein at 55¡É and pH 4.5. 7. The Km and Vmax values determined by the Line-Weaver Burk plot were 0.37 mM and 526.3 U/mg respectively. 8. In SDS-PAGE analysis, the sample contains little minor contaminated proteins. Upon deglycosylation in vitro by Endo H, the molecular size of the expressed phytase by the control cells was reduced from 67kDa to 50kDa.Maste

Sealed amalgam restoration의 미세누출에 관한 연구

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 and with a dwell time of 30 seconds. After thermocycling, the samples were dipped into 1% methylene blue kept in a 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 (p0.05). No significant differences in microleakage were also found between cup 2 and 3(p<0.05)

Study on Undergraduate-Driven Autonomous Vehicle Competition

The current autonomous vehicle competitions are dominated by a few leading research institutions and universities. Since the leading research groups have been able to accumulate their knowledge and to develop their own algorithms for autonomous vehicle for many years, the technology gap seems too big for other followers to catch up with. On the other hand, recent researches predict that there would be a sharp rise in demand for engineers with background in autonomous vehicle technology. Therefore, it would be warranted to further expand the base of the academia and autonomous vehicle industry. In an effort to achieve this goal, it would be beneficial to hold a new format of autonomous vehicle competition event where undergraduate students can play a leading role. So, this study is to analyze the current autonomous vehicle competitions and thus to establish a strategic plan to develop a unique and improved competition event. This study investigates the pros and cons of the domestic and international autonomous vehicle competitions. Based on the analysis for the current autonomous vehicle competitions, the authors suggest a strategic plan to initiate an autonomous vehicle competition. To implement the aforementioned strategic plan, it is necessary to develop a systematic environment where the education and communication are actively available. Through the strategic plan the authors propose, the newly launching autonomous vehicle competition will able to encourage the undergraduate students and professors to dive in the cutting-edge technology thereby increasing technology competitiveness.2

화학-기계적 우식 제거법을 이용한 유구치 우식의 치료: 증례보고

The conventional drilling method of caries removal makes vibration and thermal stimuli, so that children are afraid of dental treatment. Recently, various non-invasive caries removal techniques of alternatives to traditional methods are introduced and chemo-mechanical caries removal is one of them. comprises a gel that is composed of three different amino acids and a low concentration of sodium hypochlorite and specially-designed hand instruments. This report describes two cases of dental caries treatment with . The carious dentin was eliminated with gel with instruments and then composite resin restoration was conducted

상악 측절치의 치내치에 대한 증례보고

Dens invaginatus is a malformation of tooth resulting from an infolding of the enamel epithelium during tooth development. This malformation shows a broad spectrum of morphologic variations. This invagination frequently allows the entry of irritants and microorganism, which usually lead to necrosis of the adjacent pulp tissue and then to periapical or periodontal abscess. Root canal treatment of such tooth is often difficult because of the un usual form and complicated pulpal space. This article reports 2 cases of dens invaginatus in maxillary lateral incisors. The first case was successfully treated with . In the second case, involved tooth was extracted and this extracted tooth was observed using the micro-computed tomography