507 research outputs found
๋ฐ์ด์ค ๊ธฐ๋ฐ ๋ค์ด์ฌ์ ์ด์ฉํ ํด๋ฆฌ์์คํฐ์๋ง์ด๋ ์์ง ๊ฐ๋ฐ
ํ์๋
ผ๋ฌธ (์์ฌ)-- ์์ธ๋ํ๊ต ๋ํ์ : ๊ณต๊ณผ๋ํ ์ฌ๋ฃ๊ณตํ๋ถ, 2019. 2. ์์ฒ ํฌ.The growing interest in renewable resource-based feedstock chemicals and polymeric materials has promoted numerous studies in bio-sources. According to the current global production of bioplastics in 2017, PET and polyamide are the top two engineering plastics worldwide. PET exhibits disadvantages due to relatively low physical strength and Tg. One way to modify PET to yield a higher Tg and better mechanical properties is to combine polyesters and polyamides. Poly(ester-amide)s (PEAs) have a good melt processability and a less water absorption known as a serious drawback of polyamide. For these reasons, PEAs are attracting widespread interests in many researchers. Though much effort has been involved into PEAs, most of the existing studies have increased biodegradability by polymerizing aliphatic PEAs and to the best of our knowledge, only a few studies have been conducted on PEAs for engineering plastics containing aromatic residues. In this study, for the development of bioplastics having mechanical properties superior to PET, monomers for the polymerization of PEAs were selected and synthesized based on amino acids and dimethyl esters which are non-edible bio-based materials. In the initial stage of the research, polymerization was attempted by synthesizing monomers of terephthalamide structure in order to have better mechanical properties. Monomers of terephthalamide structure had a high melting point due to excellent packing between the benzene ring and hydrogen bonding due to the presence of adjacent amide bonds. By this reason, monomers were decomposed when the polymerization proceeded at the melt-process, which made monomers of terephthalamide structure not suitable as monomers for thermal bulk polymerization. To overcome this problem, the amide bond was introduced into the aliphatic diol to lower the melting point and dimethyl terephthalate having a low melting point was selected as the counterpart of polymerization that led to drastically lowering the melt-process temperature for thermal bulk polymerization. The thermal stability of every monomer and oligo-polymer synthesized by solution polymerization was evaluated. Four different diols were selected for thermal bulk polymerization based on the sufficient difference in their melting points and decomposition temperatures. In the same process as PET, thermal polymerization was successfully completed for all four diols and analyses were conducted by selecting the representative polymer synthesized with PSuP diol and DMT. Through FT-IR spectroscopy, it was confirmed that the polymer had both an ester bond and an amide bond. The model polymer having a weight average molecular weight of about 55,000 and a polydispersity index of 1.28 was polymerized. Thermal analysis showed that the glass transition temperature was nearly twice as high as that of PET, which enabled various fields to utilize PEAs in applications requiring much wider temperature range. Based on the results, the establishment of further experimental direction on how to change the internal carbon chain length of the diol will proceed.์ฌ์ ๊ฐ๋ฅํ ์์์ ๊ธฐ๋ฐ์ผ๋ก ํ ํํ ๋ฌผ์ง ๋ฐ ๊ณ ๋ถ์ ์ฌ๋ฃ์ ๋ํ ๊ด์ฌ์ด ๋์์ง๋ฉด์ ๋ฐ์ด์ค ๊ธฐ๋ฐ ๋ฌผ์ง๋ค์ ๋ํ ๋ง์ ์ฐ๊ตฌ๋ค์ด ์งํ๋๊ณ ์๋ค. ์ ์ธ๊ณ ๋๋ถํด์ฑ ๋ฐ์ด์ค ํ๋ผ์คํฑ ์์ฐ๋ 1,2 ์๋ ํด๋ฆฌ์ํธ๋ ํ
๋ ํํ๋ ์ดํธ์ ํด๋ฆฌ์๋ง์ด๋์ด๋ค. ํด๋ฆฌ์ํธ๋ ํ
๋ ํํ๋ ์ดํธ๋ ๋ฎ์ ๋ฌผ์ฑ๊ณผ ์ ๋ฆฌ์ ์ด์จ๋๋ฅผ ๊ฐ์ง๋ ๋ช
ํํ ๋จ์ ์ ๋ณด์ ํ๊ณ ์๋ค. ์ด๋ฌํ ๋จ์ ์ ๋ณด์ํ๊ธฐ ์ํ ๋ฐฉ๋ฒ ์ค ํ๋๋ก ํด๋ฆฌ์์คํฐ์ ํด๋ฆฌ์๋ง์ด๋๋ฅผ ๊ฒฐํฉํ ํด๋ฆฌ์์คํฐ์๋ง์ด๋๋ฅผ ์คํฉํ๊ณ ์ ํ๋ ์ฐ๊ตฌ๋ค์ด ์งํ๋๊ณ ์๋ค. ํ์ฌ๊น์ง, ์ง๋ฐฉ์กฑ ๋จ๋์ฒด๋ฅผ ์ด์ฉํ ํด๋ฆฌ์์คํฐ์๋ง์ด๋ ์คํฉ์ ๊ดํ ์ฐ๊ตฌ ์ธ์ ๋ฐฉํฅ์กฑ ๋จ๋์ฒด๋ฅผ ํฌํจ์ํจ ์คํฉ์ ๊ดํ ์ฐ๊ตฌ๋ ๊ฑฐ์ ์งํ๋๊ณ ์์ง ์๋ค. ํด๋ฆฌ์ํธ๋ ํ
๋ ํํ๋ ์ดํธ ๋ณด๋ค ์ฐ์ํ ๋ฌผ์ฑ์ ๋ฐ์ด์ค ํ๋ผ์คํฑ ๊ฐ๋ฐ์ ์ํด ๋ณธ ์ฐ๊ตฌ์์๋ ๋น์์ฉ ๋ฐ์ด์ค ๊ธฐ๋ฐ ๋ฌผ์ง์ธ ์๋ฏธ๋
ธ์ฐ๊ณผ ๋ค์ด๋ฉํธ์์คํฐ๋ฅผ ๊ธฐ๋ฐ์ผ๋ก, ํด๋ฆฌ์์คํฐ์๋ง์ด๋ ์คํฉ์ ์ํ ๋จ๋์ฒด๋ฅผ ์ ์ ๋ฐ ํฉ์ฑํ๊ณ ์ด์ ํฉ์ฑ์ ์งํํ์๋ค. ์ฐ๊ตฌ ์งํ ์ด๊ธฐ์๋, ๋ณด๋ค ์ฐ์ํ ๋ฌผ์ฑ์ ๋ณด์ ํ๊ณ ์ ํ
๋ ํํ์๋ง์ด๋ ํํ์ ๋จ๋์ฒด๋ฅผ ํฉ์ฑํ์ฌ ์คํฉ์ ์๋ํ์๋ค. ํ
๋ ํํ์๋ง์ด๋ ํํ์ ๋จ๋์ฒด๋ ๋ฒค์ ๊ณ ๋ฆฌ ์ฌ์ด์ ์ฐ์ํ ์ ์ธต์ฑ๊ณผ ๋ฐ๋ณต๋๋ ์๋ง์ด๋ ๊ฒฐํฉ์ผ๋ก ์ธํ ์์ ๊ฒฐํฉ์ผ๋ก ์ธํด ๋์ ์ต์ ์ ๋ณด์ ํ์ฌ ์ฉ์ต ๊ณต์ ์ผ๋ก ์คํฉ์ ์งํ ์ ๋ถํด๋๋ ํ์์ด ๋ฐ์ํ๊ธฐ ๋๋ฌธ์ ์ด ์คํฉ์ ์ํ ๋จ๋์ฒด๋ก ๋ถ์ ํฉํ๋ค๊ณ ํ๋จํ์๋ค. ์ด๋ฅผ ๊ฐ์ ํ๊ณ ์ ์๋ง์ด๋ ๊ฒฐํฉ์ ์ง๋ฐฉ์กฑ ๋ค์ด์ฌ์ ๋์
์์ผ ์ต์ ์ ๋ฎ์ถ๊ณ , ์คํฉ ๋์๋ฌผ๋ก ์ต์ ์ด ๋ฎ์ ๋ค์ด๋ฉํธํ
๋ ํํ๋ ์ดํธ๋ฅผ ์ ์ ํ์ฌ ์ด ์คํฉ์ ์ํ ์ฉ์ต ๊ณต์ ์จ๋๋ฅผ ๋ํญ ๋ฎ์ถ์๋ค. ์คํฉ์ ์ฌ์ฉ๋๋ ๋ชจ๋ ๋จ๋์ฒด์ ์ฉ์ก ์คํฉ์ ํตํด ํฉ์ฑํ ์ฌ๋ฆฌ๊ณ ํด๋ฆฌ๋จธ์ ์ด์ ์์ ์ฑ์ ํ๊ฐํ์ฌ ๋
น๋์ ๊ณผ ๋ถํด ์จ๋๊ฐ ์ถฉ๋ถํ ์ฐจ์ด๋ฅผ ๋ํ๋ด๋ 4 ์ข
๋ฅ์ ๋ค์ด์ฌ์ ์ ์ ํ์๊ณ , ์ด๋ฅผ ์ด์ฉํ ์ด ์คํฉ์ ์งํํ์๋ค. ํด๋ฆฌ์ํธ๋ ํ
๋ ํํ๋ ์ดํธ์ ๋์ผํ ๊ณต์ ์ผ๋ก, 4 ์ข
๋ฅ์ ๋ค์ด์ฌ ๋ชจ๋ ์ด ์คํฉ์ ์ฑ๊ณต์ ์ผ๋ก ์งํ ์๋ฃํ์๊ณ ๋ํ ์คํฉ์ฒด๋ฅผ ์ ์ ํ์ฌ ์ฌ๋ฌ ๋ถ์์ ์งํํ์๋ค. ์ ์ธ์ ๋ถ๊ด๋ฒ์ ํตํด, ํด๋น ๊ณ ๋ถ์๊ฐ ์์คํฐ ๊ฒฐํฉ๊ณผ ์๋ง์ด๋ ๊ฒฐํฉ ๋ ๋ชจ๋๋ฅผ ๋ณด์ ํจ์ ํ์ธํ์๊ณ , ์ ค ํฌ๊ณผ ํฌ๋ก๋งํ ๊ทธ๋ํผ ๋ถ์์ ํตํด ์ค๋ํ๊ท ๋ถ์๋์ด ์ฝ 55,000, ๋ค๋ถ์ฐ์ง์๋ 1.28์ ๊ฐ์ ๊ฐ์ง๋ ๊ณ ๋ถ์๊ฐ ์คํฉ๋์์์ ํ์ธํ์๋ค. ์ด ๋ถ์์ ํตํด ์ ๋ฆฌ์ ์ด์จ๋๊ฐ ํด๋ฆฌ์ํธ๋ ํ
๋ ํํ๋ ์ดํธ์ ๋นํด 2 ๋ฐฐ ๊ฐ๊น์ด ๋์์ ํ์ธํ์ฌ ํจ์ฌ ๋ ๋์ ์ฌ์ฉ ์จ๋ ๋ฒ์๊ฐ ์๊ตฌ๋๋ ๋ถ์ผ์์์ ํ์ฉ ๊ฐ๋ฅ์ฑ์ ํ๋ณดํ์๋ค.Abstract i
Contents v
List of Tables and Figures viii
1. Introduction 1
2. Experiments 4
2.1. Materials 4
2.2. Synthesis of Monomers with Terephthalamide Structure 5
2.2.1. Ethanolamine-DMT-Ethanolamine (EDE) Trimer 5
2.2.2. Propanolamine-DMT-Propanolamine (PDP) Trimer 5
2.2.3. DMT-Cadaverine-DMT (DCD) X-mer 6
2.2.4. MCCB-Cadaverine-MCCB (MCM) Trimer 7
2.2.5. Tyramine-TCL-Tyramine (TTT) Trimer 9
2.2.6. Ethanol-Tyramine-TCL-Tyramine-Ethanol Pentamer 9
2.3. Synthesis of Aliphatic Diol Monomers Containing Amide Bonds 12
2.3.1. Dimethyl Malonate Based Diol (EME/PMP) 12
2.3.2. Dimethyl Succinate Based Diol (ESE/PSP) 13
2.3.3. Dimethyl Adipate Based Diol (EAE/PAP) 13
2.3.4. Dimethyl Suberate Based Diol (ESuE/PSuP) 14
2.4. Solution Polymerization of Poly(ester-amide)s 17
2.4.1. Polymerization with Terephthalamide Structure Monomers 17
2.4.1.1. EDE Trimer 17
2.4.1.2. MCM Trimer 17
2.4.1.3. TTT Trimer 19
2.4.2. Polymerization with Aliphatic Diol Monomers 19
2.5. Thermal Bulk Polymerization of Poly(ester-amide)s 20
2.5.1. Polymerization with Terephthalamide Structure Monomers 21
2.5.1.1. EDE/PDP Trimer, EG, and DMT Terpolymer 21
2.5.1.2. DCD X-mer Based Poly(ester-amide)s 24
2.5.1.3. Acetylation of TTT Trimer for Polymerization of Poly(ester-amide)s 26
2.5.2. Polymerization with Aliphatic Diol Monomers 26
2.5.2.1. Large Scale Polymerization for Preparation of Tensile Test Specimens 28
2.6. Characterization 29
2.7. Thermal Properties 30
2.8. Mechanical Properties 31
3. Results and Discussion 32
3.1. Synthesis of Monomers and Polymerization with Terephthalamide 32
3.2. Analyses of Causes of Failure in Thermal Bulk Polymerization and
Establishment of New Experimental Direction 36
3.3. Synthesis of Tailor-made Diols Containing Amide Bonds and Thermal
Properties of Diols 40
3.4. Polymerization of Poly(ester-amide)s with Tailor-made Diols 43
3.5. Establishment of Further Research Direction through Representative Compound Selection and Various Analyses Thereof 46
4. Conclusion 57
5. References 59Maste
A case of unexpected adjacent tooth extrusion after implant fixed prosthetic treatment, who had undergone mandibular resection and reconstruction due to ameloblastoma
Ameloblastoma is a benign odontogenic epithelial tumor with high recurrence rate and requires extensive resection of the surrounding tissue and reconstruction of defect site.
Because of the anatomical limitation of the reconstruction site, prosthetic treatment with implants is the first recommendation. This is a case of prosthetic restoration of the
reconstruction site with implant fixed prosthesis in patient who underwent mandibular resection and iliac bone reconstruction due to ameloblastoma. However 14 months
after completion of implant prosthesis, adjacent natural tooth erupted unexpectedly, resulting in 1mm infra-occlusion occurred including posterior implant prosthesis and
anterior natural teeth. In adults, implant infra-occlusion may occur due to residual growth after placement of the maxillary anterior implant. But this case, hypo-occlusion of
molar implant and open bite of anterior natural teeth is occurred due to extrusion of adjacent tooth, is rare. Thus we report the treatment process including orthodontic treatment
with intrusion of the posterior tooth, and investigate the causes of sudden, unexpected tooth extrusion.ope
Importance of immediate surgical intervention and antifungal treatment for rhinocerebral mucormycosis: a case report
Rhinocerebral mucormycosis (RCM) is an opportunistic, potentially life-threatening fungal disease. This infective disease invades not only the facial sinuses, but also the maxilla, zygoma, and rhino-cerebral structures with a massive destruction of the facial skeletons and soft tissue. This disease progresses within various underlying diseases, such as diabetes mellitus, hematologic malignancy, renal failure, and systemic immunodepression. The relationship between mucormycosis and these underlying conditions have been discussed extensively in the literature. The authors studied 6 cases of RCM diagnosed by a tissue biopsy and treated at the department of oral and maxillofacial surgery, from 1997 to 2012. Patients were treated with several kinds of surgical interventions and antifungal agents, and their clinical & radiological signs, underlying conditions, surgical methods, and outcomes were analyzed.ope
Low-grade osteosarcoma arising from cemento-ossifying fibroma: a case report
Cemento-ossifying fibromas are benign tumors, and, although cases of an aggressive type have been reported, no cases of cemento-ossifying fibroma transforming into osteosarcoma have been documented previously. Low-grade osteosarcoma is a rare type of primary bone tumor, representing 1%-2% of all osteosarcomas. A 45-year-old female patient was diagnosed with cemento-ossifying fibroma, treated with mass excision several times over a period of two years and eight months, and followed up. After biopsy gathered because of signs of recurrence, she was diagnosed with low-grade osteosarcoma. The patient underwent wide excision, segmental mandibulectomy, and reconstruction with fibula free flap. The aim of this report is to raise awareness of the possibility that cemento-ossifying fibroma can transform into osteosarcoma and of the consequent necessity for careful diagnosis and treatment planning.ope
Development of Unsteady Preconditioned Multi-Phase Roem and Ausmpw+ Schemes
๋ณธ ๋
ผ๋ฌธ์ 2015๋
๋ ๋ฏธ๋์ฐฝ์กฐ๊ณผํ๋ถ์ ์ฌ์์ผ๋ก NSL์ฌ์
(NRF-2014M1A3A3A02034856)๊ณผ ๋ฏผใ๊ตฐํ๋ ฅ ๊ธฐ์ ์ฌ์
(Civil-Military Technology Cooperation Program)์ ์ง์์ ๋ฐ์ ์์ฑ๋์์ต๋๋ค.OAIID:RECH_ACHV_DSTSH_NO:420160000004648010RECH_ACHV_FG:RR00200003ADJUST_YN:EMP_ID:A001138CITE_RATE:FILENAME:๋น์ ์_์์กฐ๊ฑดํ_๊ธฐ๋ฒ์_์ ์ฉํ_๋ค์์ ๋_RoeMAUSMPW+_์์น๊ธฐ๋ฒยทยท.pdfDEPT_NM:๊ธฐ๊ณํญ๊ณต๊ณตํ๋ถEMAIL:[email protected]_YN:FILEURL:https://srnd.snu.ac.kr/eXrepEIR/fws/file/696b8222-7074-43e7-8294-9499eb9c0b74/linkCONFIRM:
Reduction of superior-lateral intact mandibular condyle dislocation with bone traction hook
Lateral and superior-lateral dislocations of the intact condyle are a rare complication, following traumatic insult to the mandible. We report an unusual case of a 54-year-old male patient who experienced both types of dislocations of the intact condyles with symphysis fracture following a road-traffic accident. Under general anesthesia, conventional manipulation was unsuccessful in relocating the condyles into the glenoid fossa. After applying a percutaneous traction force, using a bone traction hook placed at the sigmoid notch, the displaced intact mandibular condyles were repositioned, and the symphyseal fracture was finally reduced and fixed. The mouth opening was within normal limits, and favorable occlusion was confirmed one month postoperatively. To our knowledge, this is the first case of dislocation of both intact condyles--associated with symphysis fracture--being reduced with bone traction hook.ope
Prognosis of gingival squamous cell carcinoma diagnosed after invasive procedures
Gingival squamous cell carcinoma (SCC) has a relatively poor prognosis, because differential diagnoses of periodontitis and osteomyelitis are difficult to exclude. As such, gingival SCC is usually diagnosed late, following invasive procedures such as extraction or curettage. The purpose of this study was to classify gingival SCC patients into two groups according to the location of their primary lesion: dentate and edentulous, and to determine the appropriate treatment strategy by comparing clinical and histological features as well as treatment results. The medical records of 76 patients diagnosed with gingival SCC and treated at one institute from 1 January 1993 to 31 December 2007 were reviewed. The overall 5-year survival rate was 60.7%, and the mean survival was 98 months. Factors affecting survival included bone invasion of the primary lesion (p = 0.035), neck node metastasis (p = 0.001), and local recurrence (p = 0.000). The results suggest that more aggressive treatment, such as setting a broad surgical field and enforcing preventive neck dissection, can improve outcome, although they are associated with increased rate of cancer bone invasion and neck metastasis in patients diagnosed with cancer after receiving invasive procedures.ope
Considerations and Protocols in Virtual Surgical Planning of Reconstructive Surgery for More Accurate and Esthetic Neomandible with Deep Circumflex Iliac Artery Free Flap
Purpose: The reconstruction of mandibular defects poses many difficulties due to the unique, complex shape of the mandible and the temporomandibular joints. With development of microvascular anastomosis, free tissue transplantation techniques, such as deep circumflex iliac artery (DCIA) flap and fibular free flap (FFF), were developed. The DCIA offers good quality and quantity of bone tissue for mandibular segmental defect and implant for dental rehabilitation. Virtual surgical planning (VSP) and stereolithography-guided osteotomy are currently successfully applied in three-dimensional mandibular reconstruction, but most use FFF. There are only a few articles on reconstruction with the DCIA that assess the postoperative results.
Methods: Three patients admitted during a five month period (April of 2013 to August of 2013) underwent resection of mandible and DCIA musculo-osseous reconstruction using a VSP and stereolithographic modeling and assessment of outcomes included technical accuracy, esthetic contour, and functional outcomes.
Results: This technique yielded iliac bone segment with excellent apposition and duplication of the preoperative plan. Flap survival was 100 percent and all patients maintained preoperative occlusion and contour.
Conclusion: Based on our experience, we offer considerations and logically consistent protocols by classification of mandibular defects, and demonstrate the benefits in VSP and stereolithographic modeling of mandibular reconstructive surgery with DCIA flap.ope
Sectioned images and surface models of a cadaver for understanding the free vascularised anterior rib flap
Background: The purpose of this study is to describe the vascularised anterior rib flap on sectioned images and surface models using Visible Korean for medical education and clinical training in the field of mandibular reconstructive surgery.
Materials and methods: Serially sectioned images of the thorax were obtained from a cadaver. Significant structures in the sectioned images were outlined and stacked to create a surface model.
Results: The PDF file (8.45 MB) of the assembled models can be downloaded for free from our website (http://vkh.ajou.ac.kr/Products/PDF/Vascularized_anterior_rib_flap.zip). In this file, important anatomical structures related to the vascularised anterior rib flap can be examined in the sectioned images. All surface models and stereoscopic structures of the vascularised anterior rib flap are expressed in real time.
Conclusions: We hope that these state-of-the-art sectioned images, outlined images, and surface models will help students and trainees gain a better understanding of the anatomy of the vascularised anterior rib flap.ope
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