• 한국지반공학회지:지반
• /
• 제12권4호
• /
• pp.87-100
• /
• 1996

그리드(grid) 형태의 토목섬유와 흙 사이의 마찰특성은 표면마찰 뿐만아니라 그리드에 의한 수동저항을 동시에 측정할 수 있는 인발시험(pull-out test)에 의해 평가되고 있다. 본 연구에서는 보강토 구조물에서 가장 많이 사용되고 있는 지오그리드(geogrid)와 국내에 널리 분포되어 있는 화강 풍화토를 대상으로 실내 인발시험을 수행하였으며, 인발시험의 주요 영향 인자들인 인발속도, 토조 전면벽의 위치, 지오그리드 시료의 폭 및 지오그리드 수동 저항부재의 유.무 등이 흙/지오그리드 마찰특성에 미치는 영향을 평가하였다.

• Steel and Composite Structures
• /
• 제22권5호
• /
• pp.1141-1162
• /
• 2016

Concrete-filled double skin steel tube (CFDST) beam-columns are widely used in industrial plants, subways, high-rise buildings and arch bridges. The CFDST columns have the same advantages as traditional CFT members. Moreover, they have lighter weight, higher bending stiffness, better cyclic performance, and have higher fire resistance capacities than their CFT counterparts. The scope of this study is to develop finite element models that can predict accepted capacities of double skin concrete-filled tube columns under the combined effect of axial and bending actions. The analysis results were studied to determine the distribution of stresses among the different components and the effect of the concrete core on the outer and inner steel tube. The developed models are first verified against the available experimental data. Accordingly, an extensive parametric study was performed considering different key factors including load eccentricity, slenderness ratio, concrete compressive strength, and steel tube yield strength. The results of the performed parametric study are intended to supplement the experimental research and examine the accuracy of the available design formulas.

• Biomolecules & Therapeutics
• /
• 제4권2호
• /
• pp.202-204
• /
• 1996

Clonidine, an antihypertensive drug, stimulates postsynaptic $\alpha_2$adrenergic receptors in the CNS and lowers arterial pressure by erects on both cardiac output and peripheral resistance. However, many patients experience that sedation and xerostomia occured upon oral administration of clonidine. These side effects are due to high plasma peak concentration and can be avoided when clonidine is given transdermally. In this study, we performed the skin irritation test for transdermal administration of clonidine patch on New Zealand white rabbits. Twelve New Zealand white rabbits were divided into two groups according to the dose levels, respectively. After transdermal administration of clonidine patch with two doses, clinical manifestations, body weight loss and postmortem findings were observed. We could not find any significant evidence of skin irritation by transdermal administration of clonidine patch.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2002년도 가을 학술발표회 논문집
• /
• pp.419-426
• /
• 2002

In this study, the steel strip reinforcement bolted with braced angles is displayed skin friction resistance as well as passive resistance through existing the steel strip reinforcement. To understand pullout behavior characteristics, friction effects between soil and reinforcement are evaluated with the width of reinforcement, magnitude of surcharge, and existence of passive resistance member through laboratory pullout test. To analyze interference effects for passive resistance member, various tests are carried on case that the number, the location, and the spacing of braced angles are different. Using this test result, pullout resistance factor is calculated to consider location of braced angles and degree of interference for spacing ratio.

• 대한조선학회논문집
• /
• 제54권1호
• /
• pp.71-81
• /
• 2017

In this study, a series of full-scale extrapolation procedures based on the Granville's similarity scaling method, which was employed by Schultz (2007), is modified and then applied to compare the resistance performance between two different anti-fouling coatings. As an analysis example, the low frictional AF coating based on a novel skin-friction reducing polymer named FDR-SPC (Frictional Drag Reduction Self-Polishing Copolymer), which had been invented by the present author, is employed. The low frictional coating, which gives 25.4% skin frictional reduction in lab test, is estimated to give 18.2% total resistance reduction for a 176k DWT bulk carrier.

• 한국지반공학회지:지반
• /
• 제8권3호
• /
• pp.13-22
• /
• 1992

Model pile tests using calibration chamber are performed in !his paper in order to clarify the effect of the fundamental differences between the newly developed SPLT(Simple Pile Loading Test)and the conventional pile loading test on the pile bearing capacity. They are : (1) the direction of the applied load to mobilize the skin friction ; and (2) the use of reduced sifted sliding core. The conclusions obtained from the model pile tests are as follows : (1) The skin friction in tension loading is found to be somewhat smaller than that in compression loading. The average ration is 0.73 with the coefficient of variation (COV) of 0.18. (2) The ratio of the tip resistance rosin연 the reduced sized sliding core to that using the whole shoe shows wide scattering ; its average is 0.99 and the COV is 0.28. The aver - age of 0.99 means that there is no considerable difference in the tip resistance whether the reduced sized sliding core or the whole shoe is used, on condition that penetration depth ratio is larger than 4 : if the boundary effect of the chamber test is considered, the resistance of the whole shoe might be even larger.

• Structural Engineering and Mechanics
• /
• 제91권1호
• /
• pp.63-73
• /
• 2024

Improving the blast resistance of structural establishments has become an imperative engineering commitment to prevent property damage and fatalities in terrorist incidents. This study investigates the effects of blast mass and stand-off distance on CFRP skin concrete core sandwich bunkers of varying thicknesses using ABAQUS/Explicit software with CONWEP functionality. The considered parameters include TNT masses of 1, 10, and 25 kg and stand-off distances of 0.1, 1, 2, and 2.5 meters on structures with 200, 250, and 500 mm core thicknesses. The study finds that there exists a declining response corresponding to the blasting mass reduction coupled with increases in the stand-off distance and core thickness. The 500 mm thick bunker sustains less damage compared to those with 200 mm and 250 mm core thicknesses. The sandwich configuration remains structurally advantageous vs. those without skins. The sandwich bunker with a 500 mm thick concrete core gives the best performance against the 10 kg TNT blast load with a 1 m standoff distance exhibiting a 22.8% reduction in damage vs. that without skins. Mathematical expressions are then formulated for predicting maximum von Mises stress, principal stress, and displacement of sandwich bunkers as functions of TNT masses, stand-off distances, and core thicknesses.

• 한국지반공학회지:지반
• /
• 제8권2호
• /
• pp.21-30
• /
• 1992

말뚝의 주면마찰력은 전체 지지력중 상당한 하중을 지지할 수 있으나 실제 설계시에는 무시되는 경우가 많이 있다. 주면마찰력을 설계에 반영할 경우에도 계산결과의 신뢰도는 매우 낮은 것이 현실이다. 국내의 사정은, 설계 자료로 활용할 수 있는 것은 표준관입시험 결과뿐인 경우가 대부분으로 빈곤하며 특히 국내에 많은 화강암, 편마암의 풍화잔류토에 관해서는 설계자료가 극히 희박해 외국에 비해 열악하다. 최근에 국내에서 개발된 간편한 말뚝재하시험(simple pile loading test: SPLT)의 사용은 선단지지력과 주면마찰력의 별도 측정이 가능하도록 하였다. 본 연구에서는 풍화잔류토 지반에서의 SPLT 결과를 분석하여 N값에 의한 새로운 설계관계식을 제안하였다.

• 셀메드
• /
• 제13권5호
• /
• pp.18.1-18.3
• /
• 2023

Objective: A case report on the improvement of patients with acanthosis nigricans by Ortho-Cellular Nutrition Therapy (OCNT). Methods: A 23-year-old Korean male who has begun to have the symptoms of acanthosis nigricans two years ago has been experiencing more severe symptoms in the past year. Results: Skin pigmentation and lichenification symptoms improved after Ortho-Cellular Nutrition Therapy (OCNT). Conclusion: Ortho-Cellular Nutrition Therapy (OCNT) is effective in relieving the symptoms of patients with acanthosis nigricans.

• Journal of Power Electronics
• /
• 제18권4호
• /
• pp.1268-1277
• /
• 2018

A relatively high operating frequency is required for efficient wireless power transfer (WPT). However, the alternating current (AC) resistance of coils increases sharply with operating frequency, which possibly degrades overall efficiency. Hence, the evaluation of coil AC resistance is critical in selecting operating frequency to achieve good efficiency. For a Litz wire coil, AC resistance is attributed to the magnetic field, which leads to the skin effect, the proximity effect, and the corresponding conductive resistance and inductive resistance in the coil. A numerical calculation method based on the Biot-Savart law is proposed to calculate magnetic field strength over strands in Litz wire planar spiral coils to evaluate their AC resistance. An optimized frequency can be found to achieve the maximum efficiency of a WPT system based on the predicted resistance. Sample coils are manufactured to verify the resistance analysis method. A prototype WPT system is set up to conduct the experiments. The experiments show that the proposed method can accurately predict the AC resistance of Litz wire planar spiral coils and the optimized operating frequency for maximum efficiency.