• Title/Summary/Keyword: 천공판

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Explicit Nonlinear Finite Element Analysis for Flexural/Shear Behavior of Perfobond FRP-Concrete Composite Beam (퍼포본드 FRP-콘크리트 합성보의 휨/전단거동에 관한 외연적 비선형 유한요소해석 연구)

  • Yoo, Seung-Woon
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.21 no.11
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    • pp.771-776
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    • 2020
  • In this study, the flexural/shear behavior characteristics of perfobond FRP-concrete composite beams using an FRP plate with perforated webs as formwork and reinforcement are analyzed through an analytical method. Compared with the existing experimental results, we have proved its usefulness and use it in future practice. When the nonlinearity is very large in this case, the nonlinear finite element analysis by an explicit method will be effective. The concrete damage plasticity (CDP) model adopted in this study is considered to be able to adequately simulate the nonlinear behavior of concrete, and the determination of several variable factors required in the model is compared with the experimental results and values used in the study. This recommendation will require review and adjustment for more diverse cases. The effect of the perfobond of the composite beam with perforated web is considered to be somewhat effective in terms of securing the initial stiffness, but in the case of the apex, it is considered that the cross-sectional loss and the effect of improving the bonding force should be properly arranged. The contact problem, such as slipping of the FRP plate and concrete, is considered to be one of the reasons that the initial stiffness is slightly larger than the test result, and the slightly difference from the experimental results is attributed to the separation problem between concrete and FRP after the peak.

Jangdo(Small Ornamental Knives) manufacturing process and restoration research using Odong Inlay application (오동상감(烏銅象嵌)기법을 활용한 장도(粧刀)의 제작기술 및 복원연구)

  • Yun, Yong Hyun;Cho, Nam Chul;Jeong, Yeong Sang;Jang, Chu Nam
    • Korean Journal of Heritage: History & Science
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    • v.49 no.2
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    • pp.172-189
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    • 2016
  • In this research, literature research on the Odong material, mixture ratio, casting method and casting facility was conducted on contemporary documents, such as Cheongong Geamul. Also, a long sword was produced using the Odong inlay technique. The sword reproduction steps were as follows; Odong alloying, silver soldering alloying, Odong plate and Silver plate production, hilt and sheath production, metal frame and decorative elements, such as a Dugup (metal frame), production, Odong inlay assembly and final assembly. For the Odong alloy production, the mixture ratio of the true Odong, which has copper and gold ratio of 20:1, was used. This is traditional ratio for high quality product according to $17^{th}$ century metallurgy instruction manual. The silver soldering alloy was produced with silver and brass(Cu 7 : Zn 3) ratio of 5:1 for inlay purpose and 5:2 ratio for simple welding purpose. The true Odong alloy laminated with silver plate was used to produce hilt and sheath. The alloy went through annealing and forging steps to make it into 0.6 mm thick plate and its backing layer, which is a silver plate, had the matching thickness. After the two plates were adhered, the laminated plate went through annealing, forging, engraving, silver inlaying, shaping, silver welding, finishing and polishing steps. During the Odong colouring process, its red surface turns black by induced corrosion and different hues can be achieved depending on its quality. To accomplish the silver inlay Odong techniques, a Hanji saturated with thirty day old urine is wrapped around a hilt and sheath material, then it is left at warm room temperature for two to three hours. The Odong's surface will turn black when silver inlay remains unchanged. Various scientific analysis were conducted to study composition of recreated Odong panel, silver soldering, silver plate and the colouring agent on Odong's surface. The recreated Odong had average out at Cu 95.57 wt% Au 4.16wt% and Cu 98.04 wt% Au 1.95wt%, when documented ratio in the old record is Cu 95wt% and Au 5wt%. The recreated Odong was prone to surface breakage during manufacturing process unlike material made with composition ratio written in the old record. On the silver plate of the silver and Odong laminate, 100wt% Ag was detected and between the two layers Cu, Ag and Au were detected. This proves that the adhesion between the two layers was successfully achieved. The silver soldering had varied composition of Ag depending on the location. This shows uneven composition of the silver welding. A large quantities of S, that was not initially present, was detected on the surface of the black Odong. This indicates that presence of S has influence on Odong colour. Additional study on the chromaticity, additional chemical compounds and its restoration are needed for the further understanding of the origin of Odong colour. The result of Odong alloy testing and recreation, Odong silver inlay long sword production, scientific analysis of the Odong black colouring agent will form an important foundation of knowledge for conservation of Odong artifact.

Utilization and Development of Major Wood Resources in Kangwon-do -Permeability system of monomer in wood polymer composites- (강원도(江原道) 지역(地域)의 침활엽수재(針闊葉樹材) 목재자원(木材資源)의 이용개발(利用開發)을 위한 기초적(基礎的) 연구(硏究) -복합목재 제조를 위한 단량체의 침투기구-)

  • Lee, Won-Yong;Lee, Sung-Jae
    • Journal of Forest and Environmental Science
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    • v.14 no.1
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    • pp.1-13
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    • 1998
  • In this paper, it has been discussed on the relation between the anatomical features of woods and the penetration of methyl methacrylate monomer system into major Korean tree species, especially the Pinus koraiensis, Larix leptolepis, Quercus mongolica and Tilia amurensis. 1. There was some differences in penetration of polymers among different tree species, but generally the penetration of ring porous woods seems to be larger than that of diffuse porous woods and it was very difficult to penetrate to Larix leptolepis, especially to the that of heart wood. 2. The penetration on transeverse surface was relatively easy but radial and tangential impregnation were somewhat hard and differences between them were negligible. 3. The penetration of sapwood was larger than that of heartwood and its differences varied according to the existence of tyloses or contents in vessel. 4. Generally the polymer penetration of earlywood was larger than that of latewood in ring porous woods, but on the contrary, penetration of earlywood was small than that of latewood on diffuse porous woods. 5. Vessel diameter of wood had nearly no relation to polymers penetration. This seems to come from the reason that effective vessel diameter varies with the existence of tyloses or contents in vessel. 6. The penetration of ray tracheids was larger than that of ray parenchyma cells in softwoods, but penetration of hardwood rays seems to be small in comparison with softwood ray parenchyma cells. 7. Specific gravity and annual ring width had no relation to the penetration of polymer.

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Considerations for Postoperative Results of Pressure Sores around Buttock Region by Musculocutaneous Flaps and Perforator Flaps (근피피판과 천공지피판을 이용한 둔부 주위 욕창 재건술의 술후 결과에 대한 고찰)

  • Bae, Seong-Hwan;Nam, Su-Bong;Kim, Kyung-Hoon;Lee, Jae-Woo;Oh, Heung-Chan;Choi, Soo-Jong;Bae, Yong-Chan
    • Archives of Plastic Surgery
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    • v.38 no.6
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    • pp.815-820
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    • 2011
  • Purpose: Perforator flaps have been widely used for reconstruction of pressure sores because they have many benefits, especially reducing tension. Otherwise in order to prevent recurrence of a pressure sore, sufficient thickness of a flap is desirable, so a musculocutaneous flap is also useful for reconstruction of a pressure sore. Therefore, the authors considered about the postoperative results of reconstruction of pressure sores between using perforator flaps and musculocutaneous flaps. Methods: In this study, 33 patients (46 flaps) who underwent reconstructive operation of pressure sores from January 2007 to February 2011 were reviewed. Patients operated by using perforator flaps were 18 (18 flaps), and musculocutaneous flaps were 17 (28 flaps). We studied postoperative complications and recurrence. Results: We experienced five patients (10 flaps) with complications or recurrences who were operated using musculocutaneous flaps and one patient using a perforator flap. One case using a perforator flap stemmed from dehiscence caused by a urinary fistula occurring in two months after the surgery. Among ten cases using musculocutaneous flaps, one case was caused by total necrosis of flap, five cases by partial necrosis of flap and dehiscence, and four cases by recurrences during follow-up period. Conclusion: Even if more cases were required, it can be more considerable to operate using the perforator flap rather than the musculocutaneous flap to reduce the complication or recurrence of pressure sore.

Sound Absorption Capability and Anatomical Features of Highly Sound Absorptive Wood (고흡음성 목재의 흡음성능과 구조적 특징)

  • Kang, Chun-Won;Kang, Wook;Kim, Gwang-Chul
    • Journal of the Korean Wood Science and Technology
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    • v.38 no.4
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    • pp.292-297
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    • 2010
  • Sound absorption capability and anatomical features of kagikazura (Uncaria rhynchophylla) and larch (lalix kaemferi) wood were estimated. Sound absorption coefficients had been measured by the two microphone transfer function method and anatomical features of kagikazura wood examined by SEM observation. The sound absorption coefficients of Uncaria rhynchophylla was higher than lalix kaemferi. Especially, in the frequency range of 1 to 4KHz, sound absorption coefficients of kagikazura was about 2~3 times higher than those of lalix kaemferi. Abundant and big vessel observed on the cross sectional surface of kagikazura wood and simple perforation plate observed on the longitudinal surface. It was surmised that the abundant big vessel element and simple perforation plate behaved as a sound absorbing pore.

The Posterior Tibial Perforator Adipofascial Flap for Reconstruction of Lower Leg (후경골 동맥 천공지 지방 근막 섬피판을 이용한 전경골부의 재건)

  • Hong, Seung Eun;Pyon, Jai Kyong
    • Archives of Plastic Surgery
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    • v.34 no.3
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    • pp.352-357
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    • 2007
  • Purpose: The coverage of distal soft tissue defects and bony exposure of the lower extremity has long been recognized to be difficult clinical problem. Covering with a local skin flap is usually impractical because of the extensive and deep crush, hence free flap has been used commonly for the coverage of the wound. Although it can provide good results, it has many disadvantages. Designing an adipofascial flap raised on perforating vessels of the posterior tibia artery is a reliable and simple method to perform, and it can solve these problems. Methods: From May 2005 to May 2006, 8 patients underwent reconstruction of lower leg defects utilizing various type of the posterior tibial artery perforator adipofascial flaps. The flap provided a durable and thin coverage for the defect, as well as a well vascularized bed for skin grafting. Results: The flap size ranged $15-80cm^2$, and skin graft was done for the recipient site. The flap were successfully used for the lower extremity reconstruction in most cases. Minor complications occurred in 4 cases. There was no functional disability of the donor site with esthetically pleasing results. Furthermore, these flaps were both easy to raise and insured sufficient arterial blood supply. Conclusion: We believe there are many advantages to this posterior tibial artery perforator adipofascial flap and that it can be highly competitive to the free flaps in the lower extremity reconstruction.

Cossonid Weevils (Coleoptera: Curculionidae) Infested on Wood Cultural Properties (목재문화재를 가해하는 막대바구미류(딱정벌레목, 바구미과)에 대한 보고)

  • Hong, Ki-Jeong;Oh, Jun-Suk;Lee, Yang-Su;Park, Sang-Wook
    • Korean journal of applied entomology
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    • v.50 no.3
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    • pp.247-251
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    • 2011
  • Wood products are sometimes infested with cossonid weevils. A cossonid weevil, Hexarthrum brevicorne Wollaston has been found on wood boards used for printing books in the Jeonju Confucian temple and school (2004), a wood cabinet in the Museum of Milyang (2007), a wood wardrobe in the Museum of Seoul (2008) and on wood boards used for printing Buddhist scriptures in the temple of Suncheon (2008). Wood utensils for living in the Museum of Seoul were found to be infested with another cossonid weevil, Rhyncolus sculpturatus (Waltl) in 2008. To protect the cultural property from insect pests in the field of conservation science, more comprehensive insect pest management (IPM) programs are required.

Study on the Radial Variation of Structural Element in the Diffuse-Porous Woods (주요산공재(主要散孔材) 구성요소(構成要素)의 방사방향(放射方向) 변동(變動)에 관한 연구(硏究))

  • Han, Cheol-Soo
    • Journal of the Korean Wood Science and Technology
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    • v.15 no.2
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    • pp.26-52
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    • 1987
  • Among the diffuse-porous woods which arc dominant in Korea and used as construction materials due to their wood quality, ten species of six genus involving seven species of three genus in Betulaceae were studied on the radial variation of structural demenb. The species studied were Betula platyphylla var. japonica, B. ermanii, B. davurica, B. scstata, B. schmidtii, Carpinus laxifora, Alnus japonica, Prunus sargentii. Acer mono and Diospyros kaki. Wood fiber, vessel elements and ray increased rapidly in size from pith to a certain annual ring. After then the radial variation in size of the main structural elements seemed to be divided into three types; levelled off curve pattern indicating constant size(type I), continuously increasing curve pattern showing ever increase in size (type II) and parabolic curve pattern showing the gradual decrease after the maximum (type III), but the variation types by structural dements were different even in the same species. Based on the results from this study, it appears to be reasonable to consider the stabilized age of wood fiber, vessel elements and ray rather than considering wood fiber length in distinguishing mature woods from juvenile woods.

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A Clinical Manifestation of Meckel's Diverticulum (Meckel 게실의 임상양상)

  • Lee, Jin Beom;Lee, Yong Soon;Yoo, Eun Sun;Kim, Hae Soon;Son, Se Jeong;Park, Eun Ae;Lee, Seung Joo;Sung, Sun Hee;Seo, Jeong Wan
    • Clinical and Experimental Pediatrics
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    • v.45 no.4
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    • pp.466-472
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    • 2002
  • Purpose : The diagnosis of Meckel's diverticulum is difficult and delayed because it presents with various clinical symptoms. We evaluated clinical, imaging and pathologic findings of Meckel's diverticulum to facilitate detection of Meckel's diverticulum in children. Methods : Review of clinical, imaging, surgical and pathological findings in 10 children aged 7 days to 14 years with Meckel's diverticulum during an 8-year period, 1993-2001, at Ewha Womans University Hospital was undertaken. Results : The male to female ratio was 2.3 : 1. The chief complaint was painless lower gastrointestinal( GI) bleeding; others were abdominal pain, abdominal distention and vomiting, in order of frequency. The diagonsis before surgery were Meckel's diverticulum in 5 patients, non-reducible intussusception in 3 patients and intestinal obstruction in 2 patients. The diverticulum was located between 35 cm to 70 cm proximal to the ileocecal valve. The length of the diverticulum ranged from 4 cm to 12 cm and 80% of it was within 5 cm. A Meckel scan($^{99m}Tc-pertechnetate$ scintigraphy) after cimetidine administration was done in 6 cases. All 5 cases that presented with lower GI bleeding had ectopic gastric mucosa confirmed on pathology. Out of 5 cases of ectopic gastric mucosa, only 4 cases were positive on the Meckel's scan. Conclusion : In cases of unexplained GI bleeding, obstruction, or inflammation diagnostic workup should be carried out to rule out Meckel's diverticulum. Laparoscopy, high resolution ultrasonography and computed tomography of the abdomen may be indicated in the assessment of pediatric patient with lower GI bleeding, especially in patients with suspected bleeding from Meckel's diverticulum showing negative Meckel's scan.

Low Noise Breaker (저소음 브레이커 개발)

  • 김정태;전오성;윤병옥;이영화
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 1995.04a
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    • pp.213-216
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    • 1995
  • 공사장의 건설기계 소음은 저주파 에너지를 많이 가지고 있기 때문에, 일단 소음이 발생되면 그 전파가 멀리까지 감쇄없이 진행하는 물리적 특징을 가지고 있으며 현실적으로 흡음재처리를 통한 소음방지효과는 저조한 실정이다. 특히, 선진국에서는 건설기계 등의 엄격한 소음 인증제도 실시로 인해 국내 일부 건설장비 생산제품이 외국에서 요구하는 소음규제치를 초과하기 때문에 저소음, 저진동 건설기계 설계 기술의 발전이 없으면, 향후 수출여건이 점차 어려워지고 있다. 이와같은 주변여건의 변화로 인해 건설기계를 생산하는 입체에서는 공사장 소음과 같은 저주파 에너지에 의해 지배 받는 소음문제를 효과적으로 저감시키기 위한 건설기계의 저소음, 저진동 설계의 필요성을 심각하게 인식하고 있는 실정이다. 건설기계중, 소음이 문제시되는 기계로는 지반정지공사, 기초공사, 콘크리트공사, 포장공사, 파괴 및 해체공사와 기타등 6가지가 있다. 이중에서 환경연구원의 연구결과에 따르면, 항타기, 브레이커 및 착암기가 높은 소음도를 나타내고 있다. 가장 높은 소음을 배출하고 있는 항타기는 기초 공사에 쓰이는 것으로써 지반 천공후 H빔을 싣는 디젤 항타기의 경우, 소음도가 107dBA를 보여주고 있다. 이 값은 기계로부터 7m 떨어진 거리에서 측정된 값이다. 또, 파괴 및 해제공사에 쓰이는 브레이커는 98dBA의 소음도를 보여주고 있다. 착암기는 작용원리에 따라 91-96dBA의 소음을 배출하고 있다. 본 연구에서는 건설기계중 소음이 높아 문제시 되고 있는 유압 브레이커의 저소음 설계기술개발에 관한 내용이다. 저소음 브레이커의 개발을 위해 소음에너지의 전달경로를 검토하고, 현실성있는 소음방지 대책을 제시하였다. 연구결과, 브레이커의 설계개량을 통해, 10dB의 소음저감효과를 볼 수 있어 만족스러운 결과를 도출할 수 있었다.타를 처리하기에는 부적절한 방법임이 널리 알려진 사실이다[3]. 최근에 Ben Mrad와 Fassois[4]는 신호에 잡음이 존재하여도 이를 잘 처리할 수 있는 확률적(stochastic) 방법을 개발하여 기존의 결정적 방법들과 그 결과를 비교하였다. 그러나, 개발된 방법은 응답 신호에 백색잡음(white noise)이 섞이는 특수한 경우에만 사용할 수 있게 만들어져서 이 방법의 실질적인 적용에는 어려움이 있다. 본 연구에서는 기존의 방법들의 단점을 극복할 수 있는 새로운 회귀적 모우드 변수 규명 방법을 개발하였다. 이는 Fassois와 Lee가 ARMAX모델의 계수를 효율적으로 추정하기 위하여 개발한 뱉치방법인 Suboptimum Maximum Likelihood 방법[5]를 기초로 하여 개발하였다. 개발된 방법의 장점은 응답 신호에 유색잡음이 존재하여도 모우드 변수들을 항상 정확하게 구할 수 있으며, 또한 알고리즘의 안정성이 보장된 것이다.. 여기서는 실험실 수준의 평 판모델을 제작하고 실제 현장에서 이루어질 수 있는 진동제어 구조물에 대 한 동적실험 및 FRS를 수행하는 과정과 동일하게 따름으로써 실제 발생할 수 있는 오차나 error를 실험실내의 차원에서 파악하여 진동원을 있는 구조 물에 대한 진동제어기술을 보유하고자 한다. 이용한 해마의 부피측정은 해마경화증 환자의 진단에 있어 육안적인 MR 진단이 어려운 제한된 경우에만 실제적 도움을 줄 수 있는 보조적인 방법으로 생각된다.ofile whereas relaxivity at high field is not affected by τS. On the other hand, the change in τV does not affect low field profile but strongly in fluences on both inflection

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