• International Journal of Korean Welding Society
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• 제3권1호
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• pp.39-44
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• 2003

The welded specimens were made by butt welding of the 2 wires of 50mm length using the pulsed YAG laser. The laser welded wires were tested for investigating the shape memory effect and the ability of super elasticity. The fatigue properties of the welded wires were investigated using the rotary bending fatigue tester specially designed for wires. Moreover, the effect of defocusing distance during laser welding on the static and fatigue properties was Investigated. The shape memory effect and super elasticity of the laser welded wires were approximately identical with that of base metal at the test temperature below 353K. However, the welded wires were broken within elastic limit at the test temperature above 353k. Under the cyclic bending loading conditions, the welded wires could be useful only below the elastic limit, while the base metal had sufficient fatigue life even the stress induced M-phase region. The fatigue strength of the welded wires was about half of that of the base metal. The deterioration of the static and fatigue properties in the welded wires was proven to be from the large difference of the transformation behavior between the base metal and welded part that is caused by vaporization of Ni-content at the welded part during the welding process. The defocusing distance below 3mm acted more largely on lowering the strength of the welded wires than that of 6mm or 8mm.

• 한국의류산업학회지
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• 제15권6호
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• pp.1000-1009
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• 2013

Well-fitting riding breeches provide a comfortable ride. Horse-riding breeches should fit the lower body with patches located on the inside of hip and knees to prevent tears and slips. This study provides information about the fit of women's breeches using 3D human body scan data wearing commercially available two breeches according to posture. To get information about breeches fit, we measured the angle of waist line, the length, and the area of the breeches fit on four 20's women. This research showed the problem which was down for waist back line in the case of the horseback riding pose. The back waistline of the riding breeches should be raised compared to the front waistline; subsequently, an increased waistline angle results in less back waistline decrease. The breeches have plenty of length from back waist to crotch so the breech fit can be improved. The thigh circumference increased when riding in the front; therefore, good elasticity of the weft direction of the fabric is recommended. The length increase and the peripheral increase of the front knee significantly increased the surface area of the knee; consequently, knee patch material should be a two-way elastic fabric in all directions to enhance comfort according to riding motion.

• 한국농공학회논문집
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• 제60권1호
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• pp.59-65
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• 2018

The object of this paper was to analyze combined load acting on agricultural reservoir. This study was carried out to 3-D numerical modeling for displacement characteristic and seismic acceleration characteristic. The results of study were analyzed and summarized as follow. It was found that the displacement caused by combined load acting on railway and agricultural reservoir did not reflect the effect of load and the seismic wave consistently. The ground accelerations that occur in railway and dam were amplified because 3-D numerical analysis program interprets ground as an elastic body. Actual ground shows characteristics of elasticity and plasticity, so measured values will show different tendency. As a result of analyzing displacement characteristics, it is considered to be related to stiffness. The Ofunato seismic wave, the displacement (77.1 mm) of the body satisfied the allowable displacement (220 mm), but The Hachinohe seismic wave (282.8 mm) did not. It is considered that displacement caused by combined load is affected not only by acceleration but also by characteristics of materials.

• Structural Engineering and Mechanics
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• 제18권1호
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• pp.59-78
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• 2004

This paper is devoted to illustrate some numerical procedures to solve the boundary equilibrium problems of three-dimensional solids that are subjected to thermal strains. The constitutive equations take into account the bounded tensile strength of the material and they are presented in the framework of non-linear elasticity and small strains. The associated equilibrium problem is solved numerically by means of the finite element method and the numerical techniques, i.e. the Newton-Raphson method and the secant method, are revised in order to assure the solution convergence of the discretized problem. Some numerical examples are illustrated.

• 한국세라믹학회지
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• 제26권6호
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• pp.850-854
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• 1989

The elastic moduli and dissolution rates of 15 glasses with different mole ratios of sodium-magnasium-phosphate as potential non-toxic biomaterials were investigated. In this study, a 3-pint bending test, sonic resonance technique, and theoretical calculation were used to evaluate the modulus of elasticity. The dissolution rates at 37$^{\circ}C$(human body temperature) were determined by the measurement of mass changes in each sample for 24 weeks.

• Steel and Composite Structures
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• 제45권6호
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• pp.839-850
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• 2022

This paper presents an analytical solution to study the combined effect of non-local and stretching effect on the vibration of advanced functionally graded (FG) nanoplates. A new quasi-3D plate theory is presented; there are only five unknowns and any shear correction factor is used. A new displacement field with a new shear warping function is proposed. The equilibrium equations of the FG nanoplates are obtained using the Hamilton principle and solved numerically using the Navier technique. The material properties of functionally graded nanoplates are presumed to change according to the power-law distribution of ceramic and metal constituents. The numerical results of this work are compared with those of other published results to indicate the accuracy and convergence of this theory. Hence, a profound parameterstudy is also performed to show the influence of many parameters of the functionally graded nanoplates on the free vibration responses is investigated.

• 폴리머
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• 제36권4호
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• pp.440-447
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• 2012

분지화된 폴리에스테르계 공중합체를 제조하고, 공중합체의 분자량, 용융점도, $T_g$, 1/2 method temperature($T_{1/2}$) 및 레올로지 특성을 고찰하여 레이저 프린터 토너 바인더로의 적용을 검토하였다. 디메틸테레프탈레이트(DMT), 에틸렌글리콜(EG), 2,2-bis(4-(2-hydroxypropoxy)phenyl)propane(HPP)으로 제조한 선형공중합체는 분자량이 낮고, 용융탄성이 낮아 이를 개선하기 위하여 분지제로 3 또는 4 관능기를 가진 2-(hydroxymethyl)-2-ethylpropane-1,3-diol(trimethylol propane, TMP), 2,2-bi(hydroxymethyl)-1,3-propanediol(pentaerythritol, PER), 1,2,4-benzenetricarboxylic anhydride(trimellitic anhydride, TMA), 글리세롤 등을 첨가하여 분지화된 공중합체를 제조하였다. 분지제의 함량과 종류에 따른 열적, 레올로지 특성을 고찰하였다. 분지제의 함량이 15 mol% 이상 첨가한 공중합체는 $140^{\circ}C$ 정도의$T_{1/2}$ 값을 가지고, 높은 분자량과 용융탄성을 나타내어 토너를 융착 인쇄하는 레이저 프린터의 핫멜트 토너로서 적당하였다.

• 혜화의학회지
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• 제21권1호
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• pp.1-9
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• 2012

Objectives : The aim of this experiment is to find out relationship between the effect of cosmetics and 4 types of pattern identification about fluid-humor, which are based on the general idea of traditional oriental medicine, Qi-Blood and deficiency-excess. Methods : Korean female volunteers in good health (n=25, $23.12{\pm}2.83$) participated in this experiment. Three Korean medical doctors classified them into 4 groups: Blood-deficiency: group A; Blood-excess: group B; Qi-deficiency:group C; Qi-excess:group D). Cosmetics that contains herb extract for Blood deficiency were given to all volunteers and they used the cosmetics for 4 weeks. Volunteers were assessed non-invasively with the skin measuring devices before and after using cosmetics. And we analyzed the correlation of skin physiological parameters with 4 groups. Results : Three doctors diagnosed participants and classified them into 4 groups ; group A(n=8),group B(n=7), group C(n=3), group D(n=5) as highest score. After 4 weeks, facial skin moisture showed no significant difference in comparison between 4 groups. Sebum showed significant increase in Group A and significantly decreased Group B. Measurement of facial skin elasticity tended to increase in Group A, C, D but skin elasticity was decreased significantly in Group B. Conclusions : In case of a group that pattern identification about fluid-humor corresponds to herb extract in cosmetic, skin improving effect was better than the other group that pattern identification oppose to properties of herb in cosmetic. Therefore, from the view of traditional oriental medicine, it is very important to understand user's pattern of identification or physical conditions and properties of herbs in cosmetics on the matter of safety and efficacy.

• 대한화장품학회지
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• 제39권4호
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• pp.281-288
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• 2013

히알루론산(HA)은 피부의 세포외기질을 구성하는 주성분이다. 인간의 피부에서 히알루론산의 양은 노화와 함께 감소되는 것으로 보고되어 있으며, 이것은 노화에 따른 피부 수분 감소, 주름 형성 및 피부 탄력 저하에 관여한다고 알려져 있다. 지금까지 밝혀진 히알루론산 합성효소(hyaluronan synthase, HAS)들 중에 HAS-2가 사람의 피부 섬유아세포에서의 히알루론산의 합성을 조절하는 것으로 알려져 있다. 본 연구에서는 천궁으로부터 분리된 ferulic acid가 사람의 피부 유래 섬유아세포에서 히알루론산의 생성에 미치는 효과를 확인하였다. Semi-quantitative RT-PCR과 quantitative real-time PCR을 통해 ferulic acid가 HAS-2의 발현을 증가시키는 것을 확인하였으며 ELISA assay를 통해 ferulic acid가 히알루론산의 생성을 증가시키는 것을 확인하였다. 결론적으로 본 연구를 통해 ferulic acid는 피부 노화에 따른 히알루론산의 감소에 의해 나타나는 건조, 주름 및 탄력 저하와 같은 현상을 개선시킬 가능성을 가진 물질임을 확인하였다.

• 대한화장품학회지
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• 제31권3호
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• pp.213-218
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• 2005

최근 노령화 인구의 증가와 다양한 피부미용 기술들이 증대됨에 따라 피부노화 개선에 대한 소비자의 욕구가 높아지고 있다. 또한 기능성 화장품법 시행 후 효능원료 개발에 대한 연구들이 활발히 수행되고 있어 안전하며 임상학적으로 효능이 있는 주름기능성 화장품 개발은 화장품업계의 주요 관심 과제이다. 대표적인 피부 고민들 가운데 주름살 증가와 탄력성 감소와 같은 피부노화 현상을 개선할 수 있는 항주름 연구 및 항노화 원료들에 대한 연구 동향을 소개하고자 한다.