• Journal of Korean Society of Coastal and Ocean Engineers
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• v.11 no.3
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• pp.141-148
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• 1999

The magnitude of breaking wave forces given by plunging breakers incident on a pile structure is much greater than the forces calculated by Morison's formula, but those forces may act on pile for very short duration in the range of a few multiples of 0.01 second. Hence, a dynamic analysis for the impact forces of breaking waves may be necessary for the accurate determination of pile displacements in the first stage of design. The time series of the impact force along the pile length is thus required, which may be estimated from the pressure distribution. In the present study, breaking wave pressures are measured for a vertical pile at real field which is easily subjected to plunging breakers in stormy weather conditions. The measured data are analyzed and compared with other results to quantify the characteristics of breaking wave pressures in real fields.

• Journal of Gastric Cancer
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• v.2 no.2
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• pp.63-68
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• 2002

위의 parietal cell 혹은 대식세포와 유사한 세포 내부에서 H. pylori가 발견된다는 보고가 있기는 하나 일반적으로 H. pylori는 Shigella와 같은 침습성 세균은 아닌 것으로 알려져 있다. 그럼에도 불구하고 H. pylori에 감염된 위점막에는 많은 수의 호중구를 위시한 염증세포의 침윤이 관찰되는데 H. pylori가 위상피세포에 부착할 경우 위상피세포를 자극하여 interleukin-8을 위시한 cytokine을 발현케하고 이에 의하여 호중구 등의 염증세포가 몰려들게 된다. 한편 고유층에 몰려든 호중구에서는 다시 interleukin-8을 위시한 일련의 호중구 활성화 chemokine을 분비하여 염증반응을 증폭해 나갈 것이다. 호중구에서 발현되는 myeloperxidase나 활성산소 등도 위점막의 조직 손상에 기여할 것이다. 위상피세포를 덮고 있는 점액층은 위상피세포를 보호한다고 알려져 있으나 H. pylori 감염의 경우 점액층에 의하여 H. pylori의 운동성이 증가하고 이것이 위상피세포로부터의 cytokine 발현을 자극하여 염증반응을 증폭하는 데 관여할 가능성도 있다. H. pylori는 위상피세포에 대하여 apoptosis를 유도함과 동시에 고유층에 몰려든 호중구에 대하여는 apoptosis를 억제케하여 궁극적으로 염증반응을 증폭 및 지속시켜 나가는 쪽으로 작용한다. 한편 H. pylori는 위상피세로로부터 COX-2의 발현을 증가시키는데 이는 위상피세포의 APOPTOSIS를 억제하는 방향으로 작용한다. 이외에 H. pylori의 urease에 의하여 발생한 암모니아나 H. pylori 자신이 분비하는 세포독소가 세포 손상을 유발할 가능성도 있다. 상술한 여러 독성 인자들 중 어느 하나가 단독으로 작용하기보다는 여러 인자가 같이 동시에 또는 시차를 두고 작용할 가능성이 많다고 생각된다.

• Applied Chemistry for Engineering
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• v.33 no.2
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• pp.216-221
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• 2022

Biocompatible polysaccharide coating technology can be a promising solution to overcome unexpected diseases caused by inflammatory reactions of metallic biomaterials (e.g., stent restenosis, etc.). However, due to their inherent hydrophilicity, it is difficult to maintain the coating layer for a long time in the physiological wet-environment. Herein, catechol functionalized hyaluronic acid was synthesized and introduced to the polymeric stent (polylactic acid) as the adhesive biocoating material. Surprisingly, even with the low degree of substitution of catechol (1.26%), a significant improvement in the underwater stability was observed, confirmed by capillary experiments and spectroscopic analysis. Our results may provide an insight into the positive role of catechol molecular adhesive group in the in-vivo stability of biocoating materials.

• Journal of the Korea Concrete Institute
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• v.19 no.1
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• pp.67-74
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• 2007

We perform an experimental study of concrete beam with pultruded fiber reinforced polymer(FRP) plank using as a permanent formwork and the tensile reinforcement. A satisfactory bond at the interface between the smooth surface of the pultruded plank and the concrete must be developed for the FRP plank and the concrete to act as a composite structural member. Two kinds of aggregate were bonded to the FRP plank using a commercially available epoxy. No additional flexural or shear reinforcement was provided in the beams. For comparison we test two types of control specimen. One control did not have any aggregate bonded to the FRP plank and the other control had infernal steel reinforcing bars instead of the FRP plank. The beams were loaded by central patch load to their ultimate capacity. The experimental results were compared to current ACI 318 (2005) and ACI 440 (2006) code predictions. This study demonstrates that the FRP plank has the potential to serve as formwork and reinforcing for concrete structures.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.9
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• pp.692-700
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• 2011

The use of electric field has been studied as an alternative for biofilm control dominated by disinfectants and antibiotics. This technology would be advantageous in the environmental respect that biofilm can be controlled based on electron transfer, not using chemical disinfectants and antibiotics. Control mechanisms which were reported by earlier studies are organized as; (1) bacterial adhesion control by electrostatic repulsion at a negative current, (2) bacterial adhesion control using bacterial motion and (3) bacterial inactivation by direct oxidation at a positive current, (4) bioelectric effect leading to biofilm inactivation. In this review article, we summarized the technologies for biofilm control using electric field and provided some application examples from previous studies.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.6
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• pp.30-36
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• 2018

Researches on strengthening and rehabilitation are important since structural capacity is degraded by deterioration or damage of structural members. An effective strengthening scheme such as an externally bonded Carbon Fiber Reinforced Polymers (CFRP) can improve the structural performance of a concrete structure in a cost-effective way. Therefore, many experimental studies on strengthening methods have been widely carried out. In regards to the shear strengthening of a concrete beam, variables of the experimental studies were the amount of CFRP, the angle of the strip, the width of the strip, and the interaction between the materials. However, there are insufficient researches on bi-directional CFRP layout compared to the previous researches. In this study, a total of ten concrete beams were designed and tested to evaluate the shear strengthening effect using CFRP strips. The effectiveness of strengthening was investigated based on the shear contribution of materials, strain distribution of stirrup, and the maximum shear capacity of specimens.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.2A
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• pp.261-271
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• 2006

Many uncertainties affecting to the structural behavior of prestressed concrete (PSC) bridges reinforced with the un bonded external tendons are analyzed on the basis of the analytical method introduced in the companion paper. Many design parameters, which must be considered in design procedure, such as friction slip at the deviators, number of deviators, time-dependent deformations of concrete, relaxation of tendon and influence of loading history in PSC bridges are reviewed, and a lot of valuable results are obtained through this parametric study. In advance, the structural responses according to the external tendon profiles are analyzed to grasp if an optimum tendon profile depends on the applied loading type, and the obtained results show that the most stable structural response is revealed when the locations of deviators are coincident with the loading points.

• Journal of the Korea Concrete Institute
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• v.15 no.1
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• pp.102-109
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• 2003

The grouted splice steeve has been applied widely due to its superior construction efficiency, such as the unnecessity of post concrete and the large allowable limit to the arrangement of reinforcing bars. However, studies on grout-filled splice steeve still have not been sufficiently peformed. The purpose of this study is to investigate the confining effect of mortar grouted splice sleeve on reinforcing bar, known to strengthen the bond capacity between grout mortar and reinforcing bar. To accomplish this objective, totally 6 full-sized specimens were made and tested under monotonic loading. Each specimens were equipped with strain gauges at the 12 location of sleeve and reinforcing bar. The experimental variables adopted in this study are embedment length and size of reinforcing bars. Following conclusions are obtained; 1) Under ultimate strength condition, the confining pressure of grouted splice sleeve calculated from measured tangential and axial strain of the sleeve is over $200{\sim}300kgf/{cm}^2$ at any location of sleeve and improved with reduction in embedment length of reinforcing bar. 2) Untrauer and Henry's equation which describe bond strength of mortar as a function of its compressive strength and confining pressure, predicted the measured bond capacity of this test within the 5% limits.

• Electronics and Telecommunications Trends
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• v.22 no.4 s.106
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• pp.96-108
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• 2007

혼합현실 기술을 휴대가 용이한 모바일 기기상에서 효과적으로 구현하기 위해서는 기기에 부착된 카메라의 위치를 인식하는 기술을 시작으로 입력된 실세계 공간에 가상의 디지털 정보를 정합하고 표현하는 기술, 사용자가 표현된 혼합현실 환경과 현실감있게 상호작용하는 기술, 그리고 다양한 응용분야에 맞게 혼합현실 콘텐츠를 저작하는 기술에 이르기까지 여러 가지 세부 기술들이 요구된다. 본 논문에서는 언급한 세부 기술들에 대한 개요와 국내외적으로 진행되고 있는 관련 기술들의 동향을 구체적인 사례를 통해 소개한다.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2000.10a
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• pp.23-24
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• 2000

프레임에 그물감을 부착하여 구성되어 있는 가두리 시설은 대부분 수면에 반잠수 상태로 부유되어 계류되어 있기 때문에 파랑이 작용하면 운동을 하게 되며, 특히 파도가 높은 해역에서는 파에 의해 구조물이 연직 방향으로 크게 운동을 하여 어류에 나쁜 영향을 미칠 뿐만 아니라 해상 작업을 하는 인부에게도 매우 위험하다. 이와 같은 문제점을 해결하기 위해서는 파랑에 의한 운동이 최소화되도록 구조물을 설계해야 한다. (중략)