• International Journal of Naval Architecture and Ocean Engineering
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• 제2권1호
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• pp.45-56
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• 2010

Polymer composite materials offer high strength and stiffness to weight ratio, corrosion resistance, and total life cost reductions that appeal to the marine industry. The advantages of composite construction have led to their incorporation in U.S. yacht hull structures over 46 meters (150 feet) in length. In order to construct even larger hull structures, higher quality composites with lower cost production techniques need to be developed. In this study, the effect of composite hull fabrication processes on mechanical properties of glass fiber reinforced plastic (GFRP) composites is presented. Fabrication techniques investigated during this study are hand lay-up (HL), vacuum infusion (VI), and hybrid (HL+VI) processes. Mechanical property testing includes: tensile, compressive, and ignition loss sample analysis. Results demonstrate that the vacuum pressure implemented dining composite fabrication has an effect on mechanical properties. The VI processed GFRP yields improved mechanical properties in tension/compression strengths and tensile modulus. The hybrid GFRP composites, however, failed in a sequential manor, due to dissimilar failure modes in the HL and VI processed sides. Fractography analysis was conducted to validate the mechanical property testing results.

• Macromolecular Research
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• 제14권3호
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• pp.331-337
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• 2006

In the present study we investigated the relationship between the morphology and mechanical properties of electrospun polysulfone (PSF)/polyurethane (PU) blend nonwovens, by using the electrospinning process to prepare three types of electrospun nonwovens: PSF, PU and PSF/PU blends. The viscosity, conductivity and surface tension of the polymer solutions, were measured by rheometer, electrical conductivity meter and tensiometer, respectively. The electrospun PSF/PU blend nonwovens were characterized by scanning electron microscopy (SEM) and with a universal testing machine. The SEM results revealed that the electrospun PSF nonwoven had a structure consisting of cross-bonding between fibers, whereas the electrospun PU nonwoven showed a typical, point-bonding structure. In the electrospun PSF/PU blend nonwovens, the exact nature of the point-bonding structure depended on the PU contents. The mechanical properties of the electrospun PSF/PU blend nonwoven were affected by the structure or the morphology. With increasing PU content, the mechanical behaviors, such as Young's modulus, yield stress, tensile strength and strain, of the electrospun PSF/PU blend nonwovens were by up to 80%.

• 국제물리치료학회지
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• 제12권2호
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• pp.2359-2364
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• 2021

Background: Patients with stroke have limited ankle range of motion (ROM) due to soft tissue abnormalities around the ankle and thus experience functional impairment. Increased muscle tension and reduced ankle ROM impair gait and hinder the activities of daily living. Joint mobilization and stretching are effective interventions that improve gait performance by enhancing the ankle ROM. Objectives: To investigate the effects of ankle joint mobilization and calf muscle stretching on gait speed and gait performance in patients with stroke. Design: This was a randomized controlled trial. Methods: Twenty patients with stroke patients were randomized into two groups. The joint mobilization group (JMG) underwent anteroposterior mobilization of the talocrural joint and the joint mobilization stretching group (JMSG) underwent calf muscle stretching in addition to joint mobilization. Gait speed and gait parameters were measured using the 10-meter walk test and the GAITRite. Results: Both the JMG and JMSG groups showed significant improvements in gait speed, affected-side step length, and cadence after the intervention (P<.05). Conclusion: Joint mobilization and stretching were effective interventions for improving gait performance by enhancing ankle function in patients with stroke.

• Computers and Concrete
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• 제22권3호
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• pp.337-353
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• 2018

The present study focuses on examining the structural behaviour of steel-fibre-reinforced concrete (SFRC) beams under high rates of loading largely associated with impact problems. Fibres are added to the concrete mix to enhance ductility and energy absorption, which is important for impact-resistant design. A simple, yet practical non-linear finite-element analysis (NLFEA) model was used in the present study. Experimental static and impact tests were also carried out on beams spanning 1.3 meter with weights dropped from heights of 1.5 m and 2.5 m, respectively. The numerical model realistically describes the fully-brittle tensile behaviour of plain concrete as well as the contribution of steel fibres to the post-cracking response (the latter was allowed for by conveniently adjusting the constitutive relations for plain concrete, mainly in uniaxial tension). Suitable material relations (describing compression, tension and shear) were selected for SFRC and incorporated into ABAQUS software Brittle Cracking concrete model. A more complex model (i.e., the Damaged Plasticity concrete model in ABAQUS) was also considered and it was found that the seemingly simple (but fundamental) Brittle Cracking model yielded reliable results. Published data obtained from drop-weight experimental tests on RC and SFRC beams indicates that there is an increase in the maximum load recorded (compared to the corresponding static one) and a reduction in the portion of the beam span reacting to the impact load. However, there is considerable scatter and the specimens were often tested to complete destruction and thus yielding post-failure characteristics of little design value and making it difficult to pinpoint the actual load-carrying capacity and identify the associated true ultimate limit state (ULS). To address this, dynamic NLFEA was employed and the impact load applied was reduced gradually and applied in pulses to pinpoint the actual failure point. Different case studies were considered covering impact loading responses at both the material and structural levels as well as comparisons between RC and SFRC specimens. Steel fibres were found to increase the load-carrying capacity and deformability by offering better control over the cracking process concrete undergoes and allowing the impact energy to be absorbed more effectively compared to conventional RC members. This is useful for impact-resistant design of SFRC beams.

• 인문언어
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• 제2권2호
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• pp.5-50
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• 2002

This paper aims to illustrate and illuminate the relationship between language and its neighbor disciplines, in particular between language and literature, language and religion, and language and music. 1. Language and literature. Literature is an art of language. Therefore, linguistics, the science of language, should be able to explain how the grammar of literature elevates and ordinary language into a literary language. I illustrate poetic syntax with examples from Shelley, Coleridge, and Wordsworth. 2. Language and religion. I show how a linguistic analysis of a religious text can illuminate the background, authorship, chronology, etc., of a religious text with an example from the Book of Daniel. I also illustrate how a misanalysis of a poetic meter led to a mistranslation with an example from the Book of Psalms. 3. Language and music. First I trace an epochal event in the history of the Western music, i.e., the change of the musical style from the liturgical music of Latin in which the rhythm was created by the alternation of syllable duration into the liberated music of German in which the rhythm was generated by the alternation of lexical stress. I then illustrate a parallelism between linguistic and musical structures with several musical pieces including Gregorian chant, the 16th century music of Palestrina, the 17th century music of Schutz, the 18th century music of Mozart, and the 19th century Viennese music. Finally, the importance of text-tune (verse-melody) association is discussed with examples of mismatches in translated Korean hymns and contemporary Korean lyrical songs. In the concluding part, I speculate on some factors that are responsible for the same organizational devices in three different modes of human communication. An answer may be that all are under the same laws of mind that govern the way man perceives and organizes nature, i.e., the same cognitive abilities of man, in particular, the capacity to organize and impose structure on their respective inputs.

• 수산해양기술연구
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• 제23권1호
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• pp.6-10
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• 1987

한국 근해에서 조업하는 트로올선에 알맞은 중층 트로올어구를 개발하기 위하여 부산수산대학 실습선 부산 404호(160 GT, 750Ps)로서 조업하기에 알맞게 설계된 어구로서 어구의 유체저항을 측정하고, 그것으로부터 어구의 유체저항을 추산할 수 있는 식을 유도하고, 또한 전개판의 전개력계수와 항력계수를 구한 것을 요약하면 대략 다음과 같다. 1. 어구의 전항력 T=2.15 v 상(1.12), 그물의 항력 R 하(N)=1.96 v 상(1.01)으로서 v의 지수는 1에 가까워서 그물이 물을 잘 여과시켜줌을 시사한다. 2. 소산의 저항의 식에 따라 구한 그물의 유체저항의 추산식은 R 하(N)=4.3$\times$d/l$\times$abv 라고 표현할 수 있다. 3. 전개판의 전개력은 그물의 항력의 19~22%이고, 전개력계수는 1.5정도이며, 항력은 그물의 항력의 5~7%이고, 항력계수는 0.42정도이다

• 한국방재학회 논문집
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• 제10권5호
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• pp.27-33
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• 2010

본 연구에서는 2,000 kN 용량의 actuator를 이용, 12 m 경간의 실물 크기로 제작된 프리스트레스트 콘크리트 보의 구조성능 평가를 위한 실험을 수행하였다. 보의 양 단에는 접합을 위한 강판을 매립하였으며 시험체는 별도로 제작된 철골 보에 고력볼트접합 방식으로 세팅되었다. 프리스트레스트 콘크리트와 슬래브 콘크리트의 설계기준강도는 각각 50 MPa와 24 MPa이며, 인장 철근으로 사용된 2-HD25 철근은 매립강판의 구성요소 중 하나인 수직강판에 용접하였다. 실험은 변위제어법에 의하여 수행되었으며 10 mm의 변위를 증가시키며 loading과 unloading을 반복적으로 가력하였다. 실험결과를 살펴보면, 탄성거동구간에서는 약 88.34%, 비탄성거동구간에서는 약 86.97% 그리고 소성거동구간에서는 약 66.83%의 프리스트레싱에 의한 변위복원능력을 나타냄을 알 수 있었다.

• 수산해양기술연구
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• 제47권1호
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• pp.1-9
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• 2011

In order to investigate the cause and magnitude of scale effect occurring in the model experiments of fishing nets, five pairs of Nylon pyramid nets and one pair of PE ones in which all the two nets paired were equal each other in the factors determining their flow resistance, i. e., the ratio d/l of diameter d to length l of bars, the angle f between two adjacent bars, the attack angle q of nettings to the water flow, and the wall area S of nets, and different in the values of d and l were prepared. Then, the nets were attached to the circular steel frame alternately and their flow resistances with shapes in water were measured on the sea ascribing no turbulent flows by using the tension meter made of a block bearing for the experiment. All the Nylon nets were spreads out easily in water to form a circular cone at relatively low velocity of water and showed the resistance smaller a little in the nets with larger d and l than them with smaller d and l, because the filtration of water through meshes become easier in nets especially with larger l. But PE nettings were not spread out sufficiently on account of their small flexibility and showed higher resistance especially in them with thicker twines. Therefore, the difference in bar length or mesh size and flexibility of nettings between prototype and model nets are regarded to become factors ascribing scale effect. Especially the influence of the difference in mesh size may become large significantly in actual model experiments because the mesh size of model nets is decided at much larger value than that given by scale ratio and so the difference of mesh size between the two nets become much larger than that between nets used in this experiment.

• Archives of Plastic Surgery
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• 제38권2호
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• pp.135-142
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• 2011

Purpose: Deficiencies of the abdominal wall can be the a result of infection, surgery, trauma, or primary herniation. For abdominal wall reconstruction, synthetic materials have been shown to provide a better long-term success rate than primary fascial repair. But, synthetic materials cannot elicit angiogenesis or produce growth factor and are therefore plagued by an inability to clear infection. As a result of the inherent drawbacks of synthetic, significant effort has been spent on the identification of new bioprosthetic materials. The aim of our study is to evaluate the effectiveness of a synthetic material (PROCEED$^{(R)}$) and an ADM ($SureDerm^{TM}$) to repair abdominal wall defects in a rabbit models. Methods: We measured the tensile strength of the $SureDerm^{TM}$ and PROCEED$^{(R)}$ by a Tension meter (Instron 4482). 16 Rabbit models were assigned to this study for abdominal wall reconstruction. Abdominal defect of 8 rabbits were reconstructed by PROCEED$^{(R)}$ and the rest were reconstructed by $SureDerm^{TM}$. We assessed gross and histologic examinations for the reconstructed abdominal wall. Results: The tensile strength of $SureDerm^{TM}$ and Gore Tex$^{(R)}$ is $14.64{\pm}0.51Mpa$, $8.54{\pm}0.45Mpa$. PROCEED$^{(R)}$ was estimated above the limits of measurement. Inflammatory reaction of PROCEED$^{(R)}$ persisted for 32weeks, but $SureDerm^{TM}$ decreased after 16weeks. Vascular ingrowth into the $SureDerm^{TM}$ was seen after 32 weeks. The basement membrane of $SureDerm^{TM}$ changed into a form of pseudoperitoneum. In PROCEED$^{(R)}$, it seemed like pseudoepithelial lining was made from the fibrosis around the mesh. Conclusion: In our study, the $SureDerm^{TM}$ not only have less inflammatory reaction and presented more angiogenesis than the PROCEED$^{(R)}$, but also have pseudoperitoneum formation. It is expected that $SureDerm^{TM}$ is useful for abdominal wall reconstruction. However, a long-term study of its usage consequences are thought to be needed.

• 한국약용작물학회지
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• 제5권4호
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• pp.318-324
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• 1997

파종기(播種期)와 생육초기(生育初期) 관수(灌水)가 삼도시호(三島柴胡)의 수량(收量)에 미치는 영향(影響)을 구명(究明)코자 1995년부터 1996년까지 시험(試驗)을 수행(遂行)한 결과(結果)를 요약(要約)하면 다음과 같다. 1. 봄파종 시호(柴胡)의 출현일수(出現日數)는 파종후(播種後) 10일 간격으로 20mm씩 3회 관수한 시험구에서 38일로 무관수구(無灌水區)의 54일에 비하여 16일 단축(短縮)되었다. 2. 입모율(立毛率)은 10일간격 20mm씩 3회 관수한 시험구에서 64%인데 비하여 자연강우시 46%, 무관수에서는 25%로 아주 저조하였다. 3. 파종기(播種期)에 관수(灌水)한 경우 지상부(地上部) 및 지하부(地下部)의 생육(生育)이 무관수(無灌水) 및 자연강우(自然降雨)에서 보다 양호(良好) 하였으며 10a당 수량(收量)은 10일 간격 20mm 3회 관수한 경우 58kg으로 자연강우, 무관수에 비하여 각각 20%, 94%의 증수효과(增收效果)가 있었다. 4. 생육초기(生育初期)$(5{\sim}6$월) 10일 간격으로 30mm씩 6회에 걸쳐 관수한 것이 가장 효과적(效果的)이었다.