• Structural Engineering and Mechanics
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• 제77권6호
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• pp.745-751
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• 2021

Concrete filled double skin tubular members (CFDST) consist of double concentric circular or square steel tubes with concrete filled between the two steel tubes. The CFDST members, having a hollow section inside the internal tube, are generally lighter than ordinary concrete filled steel tubular members (CFT) which have a solid cross-section. Therefore, when the CFDST members are applied to bridge piers, reduction of seismic action can be expected. The present study aims to investigate, experimentally, the behavior of CFDST stub columns with double concentric square steel tubes filled with concrete (SS-CFDST) when working under centric compression. Two test parameters, namely, inner-to-outer width ratio and outer square steel tube's width-to-thickness were selected and outer steel tube's width-to-thickness ratio ranging from 70 to 160 were considered. In the results, shear failure of the concrete fill and local buckling of the double skin tubes having largest inner-to-outer width ratio were observed. A method to predict axial loading capacity of SS-CFDST is also proposed. In addition, the load capacity in the axial direction of stub column test on SS-CFDST is compared with that of double circular CFDST. Finally, the biaxial stress behavior of both steel tubes under plane stress is discussed.

• 대한가정학회지
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• 제35권4호
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• pp.95-110
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• 1997

According to the design method for constructing the crotch angle of traditional Korean men's trousers there are differences in from after its completion. Since there is no standardization of visual & aesthetic pattern for the construction method which is stablished by the calculation formular of waist girth hip girth pantleg end and upper outer leg length it is difficult to be used for educational use or for teaching materials. Therefore the purpose of this project according to five models in proportion to the physical standard of Korea in ages from 24 to 29 years old is to establish a design criterion and the standardization of construction methods by introduction the pant construction method of the crotch angle by converting the sitting posture length to seaming crotch center point both knees width in the Korean way of sitting. The production method for the pattern design is as follow: (1) The waist girth formular is {{{{ { w} over {4 } }}}}+{{{{ {w} over {10 } }}}}(2) The hip girth formular is {{{{ {H } over { 4} }}}}+{{{{ {H } over {5 } }}}}(3) The pantleg end formular is {{{{ {H } over {4 } }}}}(4) A crotch angle is fixed at 70 degress.(5) The ratio of outer leg length to leg width is 5:8 (6) The component ratio of the upper outer leg length to the pant length in 5:8(7) The ratio of the division point of front / right inner leg length and left inner leg width to upper outer leg length is 5 : 8

• 한국정밀공학회지
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• 제30권4호
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• pp.434-441
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• 2013

Bending motion has been used in the surgical instruments with bending structures and tendon mechanisms. A simplified bending angle amplification ratio between the proximal and distal bending joint was derived in this article. The bending structure of disk and rib in the proximal joint was analyzed based on finite element method with an emphasis on the circumferential uniformity of bending stiffness. Regarding the distal joint, optimal design and sensitivity analysis was done with four design variables of outer and inner diameter, rib height and rib width while maximizing the deformation under the stress distribution below the yield stress. Outer diameter and rib width are most critical to maximum deformation as the outer diameter and inner diameters are so to maximum equivalent stress.

• Journal of Electrical Engineering and Technology
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• 제8권6호
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• pp.1424-1430
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• 2013

This paper presents design procedure of the magnetic bearings used for high-speed electric machines and flywheel energy storage systems. Magnetic bearing can be categorized by inner-rotor type and outer-rotor type according to the position of the rotary disc. These two types are applicable based on application environments such as application space, required attraction force, and controllability. Magnetic bearing is generally designed based on the ratio (geometrical coefficient or geometrical efficiency) of pole width to rotor journal radius but proper ratio is only decided by the analysis. This is the difficulty of the magnetic bearing design. In this paper, proper design technology of the inner-rotor type and outer-rotor-type eight pole magnetic bearings is introduced and compared with the FEM analysis results, which verifies the proposed design procedure is suitable to be applied to the design of the magnetic bearings for the industrial applications and flywheel energy storage system.

• 대한가정학회지
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• 제39권10호
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• pp.97-109
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• 2001

It is thought that a composition of trousers is related to fabrics with single breadth. Therefore, trousers are designed with pattern using this fabrics with single breadth. However, in the old pattern of trousers, the breadth of 33cm-35cm was not considered in designing patterns. In this context, deciding which pattern design is better is not easy as there are a variety of estimation methods. So in this study, standardization of drafting is pursued by an objective pattern design. For this, a base angle of the trouser closely relating to a form and function was measured and using the height and the base angle, a trouser pattern design was tried. For a measurement of the base angle, 5 subject were selected. They are 25-29 year-old male graduates with fine physical standard. The base angle was measured with symphysis pubis point as a standard when subjects sat with their legs crossed, when they stood with their legs open (not forced artificially) and when they laid down with their legs open. The distance between a knee inside joint and knees was measured three times and the resultant value was used for the pattern design. For a design of trousers, the height was applied and the base angle was fixed. As a pattern drawing, using the height, a base angle and circumference of the hip, a trouser was designed. The production method for the pattern design is as follow: (1) The length formula, is height + $\frac{height}{2}$ (2) The hip girth formula is $\frac{hipgirth}{2}$ - $\frac{hipgirth}{20}$(3) A crotch angle is fixed at $72^{\circ}$. (4) The ratio of outer leg length to leg width is 5 : 8. (5) The component ratio of the upper outer leg length to the pant length is 5 : 8. (6) The ratio of the division point of front right inner leg length and left inner width to upper outer leg length is 5 : 8.

• 한국농공학회지
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• 제12권3호
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• pp.2019-2028
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• 1970

1. 트랙터에 의(依)한 효율적(效率的) 경기방법(耕起方法)을 실험(實驗) 고찰(考察)하여 다음과 같은 결과(結果)를 얻었다. 가. 포장내측경기(圃場內側耕起)에 있어서 선회소요시간(旋回所要時間)을 최소(最少)하는 효율적(效率的) 선회법(旋回法)은 선회간격(旋回間隔)이 zr(r=최소선회반경(最少旋回半徑))보다 작을때는 Q 자형(字型), 클때는 U 자형(字型)이다. 나. 포장내측경기(圃場內側耕起)의 단위선회구(單位旋回區) 건(巾) w는 2.5r 시(時) 가장 효율적(效率的)이다. 다. 포장주변부(圃場周邊部) 경기(耕起)에 있어서는 W>-0.0345L + 35.84 시(時)는 혼합경법(混合耕法)이 능률적(能率的)이고 W<-0.0345 + 35.84 시(時)는 반접속경법(半接續耕法)이 능률적(能率的)이다. 라. 포장주변부(圃場周邊部)의 건(巾)l는 내측경기시(內側 耕起時)와 주변경기시(周邊耕起時)에 있어서 모두 적을수록 효과적임으로 최소치(最少値)인 2r가 가장 적합(適合)하다. 2. 트랙터에 의(依)한 단위포장(單位圃場)과 경기능률(耕起能率)과의 관계(關係)를 고찰(考察)하여 다음과 같은 결과(結果)를 얻었다. 가. 종횡비(縱橫比)$\frac{L}{W}$ 및 면적(面積) A가 크면 일반적(一般的)으로 경기능률(耕起能率)은 증가(增加)한다. 나. 경기능률(耕起能率)의 증가율(增加率)은 종횡비(縱橫比) 및 면적(面積)이 크면 클수록 증가율(增加率)이 점차적으로 감소(減少)한다. 다. $\frac{L}{W}-T$ 곡선(曲線)에서 $\frac{L}{W}$에 대(對)한 T의 변화(變化)가 큰 범위(範圍)는 대략(大略) 20a에서 6, 30a에서 5, 50a에서 4, 80a에서 3, 100a에서 2.5 이내(以內)이다. 라. T-A 곡선(曲線)의 변화율(變化率)은 $\frac{L}{W}$의 영향(影響)을 받으나 대략(大略) $T=A^{-\frac{2}{3}}$ 곡선(曲線)의 변화율(變化率)과 같다. 마. 종횡비(縱橫比)가 3이상(以上)일때는 면적(面積)의 크기에 상관(相關)없이 경기능률(耕起能率)에 미치는 10a 면적증가(面積增加)의 효과는 약(約) 5 정도(程度)의 종횡비(縱橫比) 증가효과와 같다. 바. 종횡비(縱橫比)가 $2{\sim}3$일때는 면적(面積)의 크기에 상관(相關)없이 경기능률(耕起能率)에 미치는 10a 면적증가(面積增加)의 효과는 약(約) $4{\sim}2$ 정도(程度)의 종횡비(縱橫比) 증가효과와 같으면 이는 종횡비(縱橫比)가 적을수록, 면적(面積)이 클수록 차차(次次) 감소(減少)한다.

• 한국농공학회지
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• 제18권2호
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• pp.4096-4104
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• 1976

This experiment was carried out to investigate the efficient turning method which will be able to use every cutting methods, to calculate the width of the center field which must transpose from rotary cutting method to return cutting method, to investigate the effects of L/W and unit field on the operation efficiency. The results are summarized as follows: 1. In case of cutting in the outer field, the efficient turning method is the "$\alpha$" type turning method (half U-shaped turning method) at the first rotation, is the "$\beta$" type turning method (T-shaped turning method) at the second to fourth rotation. 2. In case of cutting in the inner field, the efficient turning method which takes the least turning time is the "a" type turning method ($\Delta$-shaped turning method). 3. The width of the center field (W') changes by the length-width ratio (L/W) and width (W), W' is 9.0m in case that L/W is 2.5 and W is 30m. 4. The larger L/W and area of unit field (A) become, the more operation efficiency (E) increases, and the limits that E is affected signicantly by L/W is 2 to 3.5 and A is within 5,000$m^2$. within 5,000$m^2$.

• 대한기계학회논문집B
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• 제23권6호
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• pp.761-768
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• 1999

This paper is studied to find the optimum condition of double-inlet Sirocco fan installed in an indoor PAC for low noise operation by the Taguchi method. The goal of this study is to obtain the best combination of each control factor which results in a desired flowrate of Sirocco fan with minimum variability. In this study, the parameter design of the Taguchi method is adopted for robust design by the dynamic characteristic analysis using orthogonal arrays and S/N ratios. The flowrate measurements are conducted by using a multiple-nozzle-type fan tester according to the orthogonal array L9($3^4$). The results of this study can be summarized as follows ; (i) The optimum condition of control factor is a set of where A is an inner to outer diameter ratio($D_1/D_2$), B is a width to outer diameter ratio($L/D_2$), C is a blade attachment angle(${\theta}$) and D is a number of blade(Z), (ii) The flowrate under the optimum condition satisfies the equation $y=0.0384{\cdot}M$ where M is a signal factor, namely number of revolution. The flowrate performance improves about 7.3% more largely as compared with the current condition, which results in about 35RPM reduction of number of revolution for the target flowrate $18.5m^3/min$, and (iii) The sensitivity analysis shows that the major factors in contribution to flowrate performance are A, B, and D ; the percentage contributions of each control factor are 44.01%(Z), 26.77%($D_1/D_2$) and 20.42%($L/D_2$).

• 한국전자파학회논문지
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• 제21권3호
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• pp.269-277
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• 2010

본 논문에서는 0.5~2 GHz 캐비티 백 스파이럴 안테나 설계에 대하여 기술하였다. 안쪽 부분은 Archimedean 스파이럴로, 바깥 부분은 log 스파이럴로 구현된 암(arm) 패턴, 백 캐비티(backing cavity), 그리고 급전용으로 Marchand 동축형 밸런을 설계하였다. 동작 대역의 저주파 대역에서 안테나 특성을 향상시키기 위하여 종단 저항을 사용하였다. CST사의 MWS툴을 이용하여 시뮬레이션 하였고, VSWR, 축비(axial ratio), 이득 그리고 반전력 빔폭을 고찰하였다. 최종적으로 제작 및 측정을 통해 설계 방법의 타당성을 검증하였고, 상용 스파이럴 안테나와의 성능을 비교하였다.

• Steel and Composite Structures
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• 제49권4호
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• pp.441-456
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• 2023

Aiming at the development trend of light weight and high strength of engineering structures, this paper experimentally investigated the seismic performance of circular-in-square high-strength concrete-filled double skin steel tubular (HCFDST) stub columns with out-of-code width-to-thickness (B/t) ratios. Typical failure mode of HCFDST stub columns appeared with the infill material crushing, steel fracture and local buckling of outer tubes as well as the inner buckling of inner tubes. Subsequently, the detailed analysis on hysteretic curves, skeleton curves and ductility, energy dissipation, stiffness degradation and lateral force reduction was conducted to reflect the influences of hollow ratios, axial compression ratios and infill types, e.g., increasing hollow ratio from 0.54 to 0.68 and 0.82 made a slight effect on bearing capacity compared to the ductility coefficients; the higher axial compression ratio (e.g., 0.3 versus 0.1) significantly reduced the average bearing capacity and ductility; the HCFDST column SCFST-6 filled with concrete obviously displayed the larger initial secant stiffness with a percentage 34.20% than the column SCFST-2 using engineered cementitious composite (ECC); increasing hollow ratios, axial compression ratios could accelerate the drop speed of stiffness degradation. The out-of-code HCFDST stub columns with reasonable design could behave favorable hysteretic performance. A theoretical model considering the tensile strength effect of ECC was thereafter established and verified to predict the moment-resisting capacity of HCFDST columns using ECC. The reported research on circular-in-square HCFDST stub columns can provide significant references to the structural application and design.