• Composites Research
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• v.20 no.2
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• pp.32-38
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• 2007

Natural fibers can refer to all types of fibres only produced by nature. Their lengths vary from particles to long strands. Natural fibers are categorized roughly by six types, depending on the types of sources; base, leaf, seed, grasses, fruit and wood. Of these fibers, jute, flax, sisal and ramie are the most commonly used as reinforced materials in preparing polymer composites. In development and improvement of these composites, many studies have been implemented to overcome the drawbacks such as incompatibility, moisture problems and so on. The range of industry sectors of natural fiber-reinforced polymer composites becomes more extensive gradually and many of the companies all over the world are engaged in fabrications or applications. This paper mainly discussed the recent status of the domestic/overseas market and research issues of natural fiber-reinforced polymer composites. We made an exception of wood-polymer composites market which have played a great role because they had been often dealt with.

• Journal of the Korean Recycled Construction Resources Institute
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• v.8 no.2
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• pp.204-211
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• 2020

Poly-Lactic Acid(PLA) fiber is an eco-friendly material and is biodegradable, so it can be utilized for manufacturing porous construction materia ls with interna l pore connection. In this study, domestic PLA fiber products(0.5mm india meter, 1.0mm in length, 10mm in length) were tested for melting at high temperatures and high alkality, and they were incorporated with FA-based geopolymer. Compressive strength was obtained through high temperature curing and alkali activator, however the complete melting of the PLA fiber was not ensured. The previous study handling PLA fiber with 0.003mm in diameter was completely dissolved, but 0.5mm and 1.0mm in diameter showed 42.5% and 33.3% of dissolution ratio, respectively. In addition, the increasing fiber volume led floating fibers during curing, which had a negative effect on its workability and solubility. Although the properties of PLA fiber may vary depending on the raw materials and production conditions, PLA fiber with 0.1mm or less diameter is recommended for porous construction material.

• Korean Journal of Veterinary Research
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• v.38 no.3
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• pp.600-605
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• 1998

춘천지역에서 포획한 한국 야생랫드(시궁쥐)에서 Capillaria hepatica에 자연감염된 예를 보고한다. Capillaria hepatica의 충란이 포획된 68마리의 랫드중 17마리에서 발견되었다. Capillaria에 감염된 랫드의 간장은 충란과 함께 림프구, 단핵구, 호산구의 침윤이 관찰되었고 심한 괴사소견을 보였다. 또한 섬유화, 출혈 hemosiderin의 침착이 뚜렷하게 관찰되었다. 최근 국내에서 자연에서 채집된 랫드의 Capillaria hepatica의 감염을 보고한 자료가 없는 것으로 미루어 Capillaria hepatica의 숙주감염을 파악하는 자료로 활용될 수 있을 것이다.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2012.03a
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• pp.61-61
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• 2012

현재 기능성 의류 섬유시장에서도, 요구하는 주요 기능들의 퍼포먼스 수준을 보여주는 과학적 수치들과 함께 기능성 섬유제작 과정에서 얼마나 친환경적인 제조과정을 거쳤는가에 대한 정보들도 요구하고 있는 중이다. 섬유에 인간과 환경에 유해한 성분이 최대한 배제됐으며 생산 과정에서의 자연자원의 낭비가 이뤄지지 않았음을 증명해야한다. CPB 전처리 공정은 혼방직물과 같이 서로 다른 물성을 가지는 직물에 대한 저온 처리로 섬유 손상을 최소화하고, $CO_2$ 발생량 및 에너지 소비량을 감소시킬 수 있는 이점이 있다. CPB 전처리는 호발, 정련, 표백을 포함하는 공정으로 일욕으로 처리 시 패딩, 수세, 와인딩 공정을 단축시키기 때문에 약품 소비량 감소와 에너지 사용 절감 효과가 있어 전 세계적으로 확산되고 있는 Green Technology이다. 본 연구에서는 CPB용 전처리 조제(4~5종)을 일욕화 하여 가공업체 생산성 향상 및 원가절감, 환경유해성 감소를 목표로 하여 CPB 전처리의 최적 가공조건을 확립하는 것이 목표이다. 첨가 용제의 종류 및 첨가량을 변화시켜 각 조성비에 따른 sample을 제조하여 정련성, 호발성, 알칼리 안정성, Whiteness를 측정하여 전처리 성능을 분석하고, 과수안정성, 금속이온 봉쇄력을 비교하여 최적 조성비 및 중합조건을 확립하였다.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.39 no.3
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• pp.177-186
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• 2013

Skin dermal fibroblast is the major collagen-producing cell type in human skin. As aging process continues in human skin, collagen production is reduced and fragmentation is increased, which is initiated by matrix metalloproteinase-1 (MMP-1). This imbalance of collagen homeostasis impairs the structure and function of dermal collagenous extracellular matrix (ECM), thereby promoting skin aging. Cysteine-rich protein 61 (CCN1), a member of the CCN family, negatively regulates collagen homeostasis in primary human skin dermal fibroblast cells. It is known in aging fibroblast cells that elevated CCN1 expression substantially reduces type I procollagen and concurrently increases MMP-1, which initiates fibrillar collagen degradation. And proliferation rate of aging fibroblast cells is reduced compared to the pre-aging fibroblast cells. In this study, we confirmed that the replicative senescence dermal fibroblast cells increased the expression levels of MMP-1 and decreased the production of type I procollagen. Our results also showed that the replicative senescence dermal fibroblast cells increased in the expression of CCN1 and decreased in the proliferation rate. Hydrolyzed Ulva pertusa extracts are the materials to improve photo-aging by reducing the expression of MMP-1 that was increased by ultraviolet and by promoting the synthesis of new collagen from fibroblast cells. In this study, we also investigated the hydrolyzed U. pertusa extract to see whether it inhibits CCN1 protein expression in the senescence fibroblasts. Results showed that the hydrolyzed U. pertusa extract inhibited the expression of MMP-1 and increased the production of type I procollagen in the aging skin fibroblast cells cultured. In addition, the proteins that regulate collagen homeostasis CCN1 expression were greatly reduced. The hydrolyzed U. pertusa extract increased the proliferation rate of the aging fibroblast cells. These results suggest that replicative senescent fibroblast cells may be used in the study of cosmetic ingredients as a model of the natural aging. In conclusion, the hydrolyzed U. pertusa extract can be used in anti-wrinkle functional cosmetic material to improve the natural aging skin care as well as photo-aging.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.3
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• pp.93-100
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• 2008

The use of fiber reinforced polymer (FRP) composites is significantly growing in construction and infrastructure applications where durability under harsh environmental conditions is of great concern. In order to examine the applicability of FRP rebar as a reinforcement in flexural member, flexural tests were conducted. 12 beams with different FRP materials such as CFRP, GFRP and Hybrid FRP and reinforcement ratio were tested and analyzed in terms of failure mode, moment-deflection, flexural capacity, ductility index and sectional strain distribution. The test results were also compared with the theoretical model represented in ACI 440.1R06. Test results indicate that the flexural capacity of the beams reinforced by FRP bars can be accurately predicted using the ultimate design theory. They also show that the current ACI model for computing the deflection overestimates the actual deflection of GFRP series and underestimates the deflection of CFRP series.

• Journal of Chest Surgery
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• v.40 no.9
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• pp.613-616
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• 2007

Background: Spontaneous hemopneumothorax is a rare disease and can be life threatening; it occurs in $1{\sim}12%$ of patients with spontaneous pneumothorax. We analyzed clinical reviews and treatments, as well as complications of spontaneous hemopneumothorax patients that were treated to aid in the optimal management. Material and Method: We studied retrospectively 30 cases with spontaneous hemopneumothorax for 11 years, from 1995 to 2006, at our hospital. Result: All the patients were male and most of the patients were under 30 years. The sides with the disorder were as follows: right in 15 cases and left in 15 cases. Patients showed mostly initial symptoms of chest pain, dyspnea and hypovolemic shock. All patients underwent a closed thoracostomy and 27 patients underwent surgery. Chemical pleurodesis was peformed because of postoperative persistent air leakage and one case was treated in the ICU due to re-expansion pulmonary edema, There were no other complications such as fibrothorax seen during the follow-up periods. Conclusion: The most important finding is proper initial management, as the spontaneous hemopneumothorax can potentially lead to a life-threatening condition. Recently, video assisted thoracoscopic surgery (VATS) is common procedure for general thoracic surgery and overcomes the weak points of performing a thoracotomy. The results of VATS are encouraging.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.4
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• pp.86-95
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• 2019

Recently, the applications of carbon fiber have been broader than ever when it comes to such industrials as automobiles, ships, aerospace, civil engineering and architecture because of their lightweight-ness and high mechanical properties. This study analyzed mechanical properties and flexural behavior of carbon fiber reinforced cement composites(CFRC) with different fiber contents and fiber lengths, and also impact resistance by natural drop test on mortar specimens was compared and examined. In addition, contents of carbon fiber(CF) were varied by 0.5%, 1.0%, 2.0% and 3.0%. Fiber lengths was used for 6 mm and 12 mm, respectively. As a result of the test, the flow value was very disadvantageous in terms of fluidity due to the carbon fiber ball phenomenon, and the unit weight was slightly reduced. In particular, the compressive strength was decreased with increasing carbon fiber contents. On the other hand, the flexural strength was the highest with 12 mm fiber length and 2% fiber content. As the results of the impact resistance test, the specimens of plain mortar takes about 2~3 times to final fracture, while the specimens of CFRC is somewhat different depending on the increase of the fiber contents. However, when the fiber length is 12 mm and the fiber content is 2%, the impact resistance was the highest.

• Journal of the Korean Society of Radiology
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• v.81 no.3
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• pp.726-732
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• 2020

Neurofibromatosis type 1 (NF1) is a common autosomal-dominant disorder. Vasculopathies associated with NF1 are rare and can cause aneurysms, stenoses, and arteriovenous malformations. Aneurysms may rupture spontaneously, which could be fatal. Spontaneous mesenteric hemorrhage due to rupture of an inferior mesenteric artery aneurysm associated with NF1 has rarely been reported. Herein, we report a case of spontaneous rupture of a fusiform aneurysm in the superior rectal artery in a 56-year-old woman with NF1 who was successfully treated with transcatheter arterial embolization.

• Journal of the Korean Geosynthetics Society
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• v.6 no.3
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• pp.25-30
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• 2007

The major reason to employ electrokinetic geosynthetics is to take advantage of its ability to densify very low permeability materials in shorter time periods than ordinary seepage consolidation. A number of laboratory scale experiments was carried out with acrylic column using natural clayey soil. The testing results indicate that (1) the electrically induced settlement was faster than the gravitational one, (2) the higher the voltage, the faster the dewatering but the less final settlement, and (3) the pH extended as low as 3 in the anode section and as high as 11 near the cathode.