• Structural Engineering and Mechanics
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• 제70권2호
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• pp.133-141
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• 2019

The aim of the present paper is to present the cyclic behavior of strengthened reinforced concrete shear wall test specimen, which was reinforced with cold drawn welded wire mesh fabric. Two reinforced concrete shear wall specimens have been tested in the present study. The walls were tested under reversed cyclic loading with loading applied near the tip of the walls. The control wall is tested in its original state to serve as a baseline for the evaluation of the repair and strengthening techniques. The two test specimens include a control wall and a repaired wall. The control wall test specimen was designed and detailed to simulate non-ductile reinforced concrete shear walls that do not meet the modern seismic provisions. The response of the original wall was associated with the brittle failure. The control shear wall was repaired by addition of the reinforcements and the concrete and then it was reloaded. The effectiveness of the repair technique was investigated. Test results indicate that there can be a near full restoration of the walls' strength. The data from this test, augmenting other data available in the literature, will be useful in calibrating improved analytical methods as they are developed.

• 대한치과기공학회지
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• 제46권1호
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• pp.15-19
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• 2024

An ideal post material should have physical properties similar to those of dentin. Post materials with high elastic moduli may cause root fractures. This clinical report describes the treatment of a severely damaged tooth using a recently introduced material. Polyetherketoneketone (PEKK) is a semicrystalline high-performance thermoplastic polymer. PEKK is a promising material for custom post-and-core fabrication because of its elasticity close to that of dentin, good shock absorbance, machinability, and low cost. A laboratory scanner was used to digitize the conventional impression of a severely damaged maxillary right first molar. A custom PEKK post-and-core was designed and milled using computer-aided design and computer-aided manufacturing technology. Using the proposed technique, a custom PEKK post-and-core was fabricated accurately and human error was reduced. Restoration was luted with resin cement. Custom PEKK post-and-core restorations are a viable alternative for treating severely damaged teeth.

• 대한치과보철학회지
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• 제36권1호
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• pp.133-149
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• 1998

Clinical application of composite resin recently draw great concerns in dentistry. Especially due to advantages such as esthetics, adhesiveness, simple clinical procedures, various shapes and kinds of composite resins are widely being applied to prosthodontics, conservative dentistry, and orthodontics. But, clinical problems attributable to the polymerization shrinkage of composite resin have been proposed, and we have to regard clinical problems such as secondary caries, loss of restoration, fracture of the surrounding tooth structure, marginal discoloration, and tooth sensitivity, and many portions are remained to be overcome. Therefore, this study attempts to analyze stress distribution between resin and tooth structure which is generated during polymerization shrinkage of composite resin using three dimensional finite element method. Three dimensional finite element models with conventional box-shape cavity and erosion/abrasion type V-shape lesion cavity in upper central incisor were developed. These cavities were filled with four different types of placement techniques. (bulk filling, horizontal increment filling, oblique occlusal increment filling, oblique gingival increment filling) The stresses generated by polymerization shrinkage of composite resin were calculated. The results analyzed with three dimensional finite element method were as follows : 1. The increment filling technique showed the highest maximum normal stress in both conventional box-shape and V-shape cavities and showed a tendency to decrease after complete polymerization. 2. The bulk filling technique resulted in increased stresses during the curing process in both conventional box-shape and V-shape cavities and the highest maximum normal stress occurred after complete polymerization. 3. The bulk filling resulted in the lowest maximum normal stress in both box-shape and V-shape cavities 4. Regardless of placement method, in conventional box-shape cavity, the maximum normal stress increased in dentin floor, enamel, dentin sequence and in V-shape cavity, the maximum normal stress increased in enamel, dentin sequence.

• 복식
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• 제59권6호
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• pp.140-155
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• 2009

This study tries to find out the special twine technique of flat string and refers to historical documents, records, artifacts of excavated articles, and real materials. In Japan weaved cloth is called Jomul or Jonue and these methods were brought to Japan from Korea during Aska Period(645${\sim}$710) and Nara Period(710${\sim}$794). Among those knot methods, the 1/1 knot was written as a Shillajo on a documentary record at Heian Period, Engisik, and Samdaesillok which is a historic document from King Saiya to King Gowooko(858${\sim}$887). Also 2/2 knot weaving was recorded as Goryeojo that the technique originated for a long time in Japan. During the Joseon Dynasty, Gunmok was written as Dahoi, and Gwangdahoe, which means wide and flat Gunmok, was the name of Dae(Belt). The frame for the twine Gwangdahoe is no longer in Korea, but only can be found in Japan as a Goraiwoochi loom for Shillajo and Goryeojo from Korea. There are currently artifacts by the techniques of Shillajo and Goryeojo that were excavated in 15${\sim}$17C in Korea. Therefore this study was looked into the artifacts from 6${\sim}$8C in $Sh{\"{O}}so$-in, and the features of Dae (Belt) weaved by Shillajo and Goryeojo case method. Gwangdahoe excavated artifacts in the mid Jeosun Dynasty was restored by the process of Goryeojo weaving method.

• 구강회복응용과학지
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• 제25권3호
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• pp.243-253
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• 2009

임플란트 술식에서 방사선 영상 기술, 컴퓨터 소프트웨어의 발전으로 정확한 진단 및 surgical guide의 제작이 가능해졌다. 본 증례는 양악 무치악 환자에서 고정성 임플란트 보철을 위해 CAD/CAM technique을 이용하여 수술을 하고 즉시 하중을 가한 증례이다. Planning software program을 이용하여 해부학적 구조물과 단면상을 고려하여 상 하악에 각각 6개씩의 임플란트를 최적의 위치에 계획하였다. 정밀한 surgical guide 이용하여 미리 계획된 위치와 방향으로 무절개 임플란트 식립 수술을 시행하였다. 즉시 사용 가능한 고정성 임시 보철물을 미리 제작해 수술 직후 장착하여 환자의 만족도를 높였으며, 이를 6개월간 평가하여 심미적이며, 기능적으로 안정적인 최종 보철물을 제작할 수 있었다.

• 대한치과보철학회지
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• 제52권3호
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• pp.252-257
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• 2014

완전 무치악 환자에서 전악 수복시 환자 고유의 악간관계, 교합평면의 위치, 구순지지, 치아형태와 교합양상을 알 수 없기 때문에 그 모든 것을 임시의치에 기록한 후 이것을 최대한 최종 보철물에 반영하여 이상적인 보철물을 제작해 주어야 한다. 본 증례의 환자는 치주질환에 의한 다수 치아 동요가 존재하여 예후가 불량한 잔존치아 전악 발거 후 임플란트 식립하여 임시치아에 환자의 수직 및 수평 악간관계, 교합평면의 위치, 수직 및 수평 피개의 양, 치아 크기, 전치부 길이를 기록하였다. 그 후 임시치아를 스캐너와 CAD/CAM 기술을 이용하는 double scanning technique로 복제하여 임시치아와 동일한 형태의 단일 구조 지르코니아 브릿지 보철물을 제작하였다. 치료 이후 4개월간의 임상 관찰에서 환자는 심미적, 기능적으로 만족하고 안정적으로 유지되었기에 이를 보고하고자 한다.

• 대한토목학회논문집
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• 제33권3호
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• pp.987-995
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• 2013

본 연구의 목적은 국내 하천 복원의 자연친화적인 설계를 위한 무독성 호안공법의 수리적 안정성을 검토하는 것이다. 최근 들어 공학적 효율 위주의 치수 기능만을 위한 하천관리 정책에서 벗어나 하천의 환경적 기능의 개선을 위한 생태하천 복원사업이 이루어지고 있다. 그러나 신규 호안공법에 대한 부적절한 수리학적 설계기준이 자주 홍수기 경제적 손실을 유발하고 있다. 사석 및 블록의 안정성에 관한 연구는 크게 하천에서 제방, 하상보호, 세굴방지 등의 목적과 바다에서 호안 또는 방조제의 축조에 따라 투하하는 사석의 안정성에 기초를 둔 연구가 대부분이며 경험식으로 이루어져 있다. 본 연구에서는 최고 유속 3.5 m/s인 고속수로를 제작하여 수리실험을 수행하였으며, 무독성 접착제를 이용한 블록공법에 대한 다양한 조건의 수리실험을 통해서 수리적 안정성을 위한 호안블록의 한계유속을 구하였다.

• 한국환경복원기술학회지
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• 제13권5호
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• pp.81-89
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• 2010

This study was conducted to evaluate the effects of early revegetation by analyzing the characteristics of germination and growth of Chrysanthemum zawadskii using vegetation-plant in rock slopes. After making up a growing basis of approximately 20-cm depth and 10-cm diameter by using a boring machine, the surface of rock slopes was planted with vegetation-plant. The number of germinating populations by soil media was 41 in H.s, 4 in T.s, 3 in M.s, and 0 in M.g.s. The germination rate (%) by soil media was 20.0% in H.s, 3.3% in T.s, 2.5% in M.s and 0% in M.g.s. In monthly changes of growth rate, the aspect was northwest direction, the soil media was H.s, and the treatment was microorganism plot. The main factors affecting survivorship and growth of population were soil media and treatment plot. The interaction between each factor had a good effects in bearing x treatment plot, soil media x treatment plot. but, it is recommended that the mulching of vegetation plant is highly needed to help the germination of seed and growth of vegetation because of loss of seed and soil media occurred due to rainfall. Therefore, The result suggests that the revegetation technique using boring in rock slope was very efficient in respect of the early revegetation and the landscape.

• Restorative Dentistry and Endodontics
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• 제18권1호
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• pp.55-72
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• 1993

The aim of this study was to compare the marginal leakage of class II light curing composite resin restoration according to filling methods. With using acid etching technique and dentin bonding agent, various methods were suggested to eliminate or reduce the marginal leakage. In this study, class II cavities were prepared in 100 extracted human premolars with cementum margin(1mm below the CEJ) and the teeth were randomly assigned to 5 groups of 20 teeth each. The teeth in group 1, 2, 3 and 4 were restored by direct filling methods using P-50 and Clearfil Photoposterior of 10 teeth each, but the method of insertion of the restorative materials varied with each group. And the teeth in group 5 were restored by inlay method using Kulzer Inlay and CR Inlay. Filling methods are as follows : Group 1 : The composite resin was inserted in one layer in the proximal box and one layer in the occlusal portion. Group 2 : Insertion was in two equally thick horizontal layers in the proximal box. Group 3 : Insertion was in two diagonally placed layers in the proximal box. Group 4 : The composite resin was inserted in the same way as in group 3 except that a glass ionomer liner was first placed on the axial wall and gingival floor. Group 5 : The teeth were restored by Inlay technique using dure cure resin cement. All the teeth were thermocycled, stained with 1 % methylene blue solution, sectioned mesiodistally, and scored for marginal leakage. To compare the marginal leakage, ANOVA and T-test were used in analysis. The following results were obtained : 1. In direct filling methods, there was no significant difference in marginal leakage at both occlusal and cervical margins. 2. In all groups, occlusal margin showed significantly less leakage than cervical margin. 3. In group using glass ionomer liner, there was no significant reduction of marginal leakage at the cervical margin. 4. The group restored by inlay method showed significantly less marginal leakage than groups restored by direct filling methods at both occlusal and gingival margins. 5. There was no significant difference in each group according to filling materials.

• Archives of Plastic Surgery
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• 제34권1호
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• pp.123-127
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• 2007

Purpose: Rigid external distraction(RED) is a highly effective technique for correction of maxillary hypoplasia in patients with cleft or syndromic craniosynostosis. Despite many advantages of RED, it also has the problem of relapse as the conventional advancement surgery. Bicoronal approach, that is the common approach to gain access to the craniofacial skeleton, had some morbidity, such as hair loss, sensory loss, wide scar and temporal hollowing. We present our clinical experience of RED distraction with minimal invasive approach and early rigid fixation to overcome these disadvantages. Methods: A 27-year-old female patient with Crouzon's disease underwent Le Fort III osteotomy and RED device application through the minimal invasive direct skin incisions. After the latent period of 5 days, distraction was undertaken until proper convexity and advancement were obtained. During the rigid retention period, inflammation occurred on the right cheek, and proper conservative managements were done including continuous irrigation. To maintain the stability of distraction, early rigid fixation was undertaken on the osteotomy sites through another skin incisions. Preoperative and postoperative orthodontic treatments were performed. Serial photographs and cephalometric radiographs were obtained preoperatively, after distraction and 6 months after distraction. Results: The cephalometric analysis demonstrated postoperatively significant advancement of the maxilla and improvement of facial convexity. After 6-month follow-up period, the maxilla was stable in the sagittal plane and no relapse was found. Facial scars were not noticeable and other deformity and morbidity did not occur. Conclusion: This effective and stable technique will be a good alternative for the patients who need large amount of distraction and for adult patients with severe maxillary hypoplasia or syndromic craniosynostosis.