• Computational Structural Engineering : An International Journal
• /
• 제3권1호
• /
• pp.19-29
• /
• 2003

In the present study, finite element linear buckling analysis is performed for grid-stiffened composite plates. A hybrid element with drilling degrees of freedom is employed to reduce the effect of the sensitivity of mesh distortion and to match the degrees of freedom between skins and stiffeners. The preliminary static stress distribution is analyzed for the determination of accurate load distribution. Parametric study of grid structures is performed and three types of buckling modes are observed. The maximum limit of buckling load was found at the local skin-buckling mode. In order to maximize buckling loads, stiffened panels need to be designed to be buckled in skin-buckling mode.

• Steel and Composite Structures
• /
• 제30권4호
• /
• pp.315-325
• /
• 2019

Double skin composite walls offer structural and economic merits over conventional reinforced concrete counterparts in terms of higher capacity, greater stiffness, and better ductility. This paper investigated the axial behavior of double skin composite walls with steel truss connectors. Full-scaled tests were conducted on three specimens with different height-to-thickness ratios. Test results were evaluated in terms of failure mode, load-axial displacement response, buckling loading, axial stiffness, ductility, strength index, load-lateral deflection, and strain distribution. The test data were compared with AISC 360 and Eurocode 4 and it was found that both codes provided conservative predictions on the safe side.

• 한국가구학회지
• /
• 제24권1호
• /
• pp.60-69
• /
• 2013

Timber is an eco-friendly material that is suitable for low carbon and green growth, and recently, studies on utilization and manufacture of timber are increasing. Thus, we need a stable supply of wood working materials for the formative element and widespread function of timber. It is necessary to develop the use of timber because it enhances the added value of this material by making the most of it. In this way, skin-timber is an appropriate material for life articles because skin-timber has a variety of functions including the ability for storage use, the beauty of structure, the ability to maintain heat and insulation, and the capability to control humidity. In this study, I developed household items using skin-timbers that are made up of circular columns and square columns of pine, larch, and yellow popular. The circular and square columns have an inner hole that is approximately 90% of the external structure's width. I intended for the concept of these designs to display creativity considering functionality and productivity. These items are life articles and furniture for modern people. They are eco-friendly products that are varnished with traditional lacquer and natural oil. According to the result of this study, skin-timbers are made of domestic pine, larch, and yellow popular and are resource of furniture, household items, and woodcraft. I believe skin-timber is not only a useful material for processability and design applicability, but it also has the capability to be a multifunctional and high value-added material. Also, if the standards, such as cortex thickness, outside diameter, and length, of skin-timber are producted diversely, I believe skin-timber can be have more the possibility of industrial products' development.

• Fibers and Polymers
• /
• 제6권4호
• /
• pp.322-331
• /
• 2005

Graduated compression stockings (GCS) have been widely used for the prophylaxis and treatment of venous diseases. Their gradient pressure function largely related to their fabric structure and material properties. By combing fabric physical testing and wear trials, this study investigated the GCSs fabric structure and material properties at different locations along the stocking hoses, and quantitatively analyzed the effects of fabrics on skin pressure longitudinal and transverse distributions. We concluded that, Structural characteristics and material properties of stocking fabrics were not uniform along the hoses, but a gradual variation from ankle to thigh regions, which significantly influenced the corresponding skin pressure gradient distributions; Tensile (WT, EM) and shearing properties (G) generated most significant differences among ankle, knee and thigh regions along the stocking hose, which significantly influenced the skin pressure lognitudinal gradient distribution. More material indices generating significant gradual changes occurred in the fabric wale direction along stocking hose, meaning that materials properties in wale direction would exert more important impact on the skin pressure gradient performances. And, the greater tensibility and smoother surface of fabric in wale direction would contribute to put stocking on and off, and facilitate wearers' leg extension-flexion movements. The indices of WT and EM of stocking fabrics in series A have strong linear correlations with skin pressure lognitudinal distribution, which largely related to their better performances in gradual changes of material properties. Skin pressure applied by fabric with same material properties produced pronounced differences among four different directions around certain cross-sections of human leg, especially at the ankle region; and, the skin pressure magnitudes at ankle region were more easily influenced by the materials properties, which were considered to be largely related to the anatomic structure of human leg.

• 한국약용작물학회지
• /
• 제27권2호
• /
• pp.143-150
• /
• 2019

Background: Skin is an organ that protects the human body from various environmental stimuli that can induce immune system activation. Skin aging can be largely divided into two categories: physiological aging, which is caused by the a decreased physiological function of the skin and structural changes with aging, and photoaging, which is caused by the chemical stress induced by external stimuli such as ultraviolet (UV) radiation. Methods and Results: The objective of this study was to investigate the anti-wrinkle and UV protective effect of catechin-rich green tea extract (CGTE) in activated keratinocyte (HaCaT cells) and UV-induced skin damage in hairless mice. The results showed that CGTE inhibits the tumor necrosis factor-alpha interferon-gamma ($TNF-{\alpha}+IFN-{\gamma}$)-induced expression of matrix metalloproteinase (MMP)-1 in HaCaT cells. In addition, the CGTE treatment significantly reduced wrinkle formation, epidermal thickness, collagen deposition, and transepidermal water loss in dorsal skin irradiated with UVB. However, the ${\beta}$-glucosidase activity was significantly increased. The CGTE treatment inhibits mRNA expression and enzyme activity of MMP-2 and MMP-9 in the dorsal skin irradiated with UVB. Conclusions: It is expected that CGTE can be effectively used as a functional food and cosmetic ingredient to improve skin moisture retention and reduce wrinkle formation.

• 대한두개안면성형외과학회지
• /
• 제21권6호
• /
• pp.357-362
• /
• 2020

Background: Full-thickness skin grafts (FTSGs) have been widely used after facial skin cancer resection, for correcting defects that are too wide to be reconstructed using a local flap or if structural deformation is expected. The preauricular, posterior auricular, supraclavicular, conchal bowl, nasolabial fold, and upper eyelid skin areas are known as the main donor sites for facial FTSG. Herein, we aimed to describe the effectiveness of using infraclavicular skin as the donor site for specific cases. Methods: We performed FTSG using the infraclavicular skin as the donor site in older Asian adults following skin cancer resection. Outcomes were observed for > 6 months postoperatively. The Manchester Scar Scale was used for an objective evaluation of satisfaction following surgery and scarring. Results: We analyzed the data of 17 patients. During follow-up, the donor and recipient sites of all patients healed without complications. Upon evaluation, the average Manchester Scar Scale scores for the recipient and donor sites were 7.4 points and 5.7 points, respectively. Conclusion: In general, conventional donor sites, such as the preauricular, posterior auricular, and supraclavicular sites, are widely used for facial FTSG because they achieve good cosmetic results. However, the infraclavicular skin may be a useful donor for facial FTSG in cases where the duration of time spent under anesthesia must be minimized due to a patient's advanced age or underlying health conditions, or when the recipient site is relatively thick area, such as the nose, forehead, or cheek.

• Composites Research
• /
• 제26권4호
• /
• pp.259-264
• /
• 2013

본 연구에서는 기계적 전기적 기능을 모두 만족하는 다중대역 스킨구조물에서의 복사 소자를 2중 사출으로 제작하였다. 추후 외부 스킨 구조 변형에 따른 복사 소자의 안정성을 검증하기 위하여 충격 및 좌굴에 대한 시험과 축 하중과 전단 하중에 대한 강도 해석을 실시하였다. 그리고 다중 대역 안테나 스킨 구조의 복사 소자에 대한 실험적 방법과 해석적 방법을 통한 강도 분석 결과, 구조의 허용 하중을 예측하고 충격과 좌굴에 대한 안정성을 평가할 수 있었다.

• Macromolecular Research
• /
• 제15권3호
• /
• pp.205-210
• /
• 2007

Collagen is the major structural protein of connective tissues. It can be used as a prosthetic biomaterial applicable to artificial skin, tendon, ligaments, and collagen implants. The objective of this study is to investigate the possibility of realizing wound dressing medical products by the synthesis of composite materials with collagen and a biodegradable polymer, PLLA, via a surface modification process. Type I collagen was obtained from pig skin by a separation process. The structural characteristics of the extracted collagen were confirmed by SDS-polyacrylamide (PAcr) gel electrophoresis (PAGE) and FTIR. Also, PLLA-g-PAcr was synthesized by the radical polymerization of acrylamide initiated by AIBN in the presence of PLLA. The surface of PLLA was modified by the presence of the acrylamide residues. The structural characteristics of the copolymer were analyzed by FTIR, $^1H-NMR$ and contact angle measurements. The water uptake and WVTR of the collagen/PLLA-g-PAcr composite tended to increase with increasing collagen concentration and with decreasing EDC concentration.

• 한국전산구조공학회논문집
• /
• 제30권5호
• /
• pp.445-452
• /
• 2017

본 연구에서의 날개 앞전은 날개의 공기역학적인 기능뿐만 아니라 조류 등의 외부의 손상을 줄 수 있는 것으로부터 날개 내부 구성요소를 보호하고 안전한 항공기 운항을 위한 반드시 필요한 구조 요소이다. 복합재 무인기의 날개 경량화를 위한 최적의 제작 모델을 비교 검토하였다. MSC. Patran/Nastran을 이용한 유한요소해석을 통하여 비틀림 하중의 변위 형상을 비교 확인하였으며, 각 모델들의 비틀림 강도 실험을 통하여 적층 유형, 두께 변화 및 형상 적용에 따른 경량화 성능 개선을 확인하므로써 소형 복합재 무인기 최적의 경량화 날개 앞전스킨의 형태를 제시하였다.

• Applied Microscopy
• /
• 제44권1호
• /
• pp.15-20
• /
• 2014

Cytokeratin 19 (CK19) expressed in epidermis of skin, bulge region of hair follicle, outermost layer of outer root sheath and proximal and distal to bulge. Vimentin is a fibrous protein that localized in cytoplasm of fibroblast and forms cytoskeleton to maintain shape of cell and nucleus. In this study, CK19 and vimentin in skin were confirmed with light, fluorescence and transmission electron microscope. As a result, CK19 was localized epidermis, hair follicles, outer root sheath and nucleus of Merkel's cell. However, vimentin was localized some epidermis, dermis, hypodermis and nucleus of Merkel's cell. The role of CK19 is self-renewal and homeostasis in skin. Also, hair follicle regeneration and hair growth is known to be related. It is supposed that required of structural proteins that make up cytoskeleton is increased. Thereby, expression of CK19 is increased. It is considered that vimentin localized in order to stabilize structure of cell and cytoskeleton of fibroblasts. Also, CK19 and vimentin present in nuclei of Merkel's cell, and to act as a fibrous protein that make up end of a nerve fiber present in Merkel's cell and paracrine function of Merkel's cell.