• 한국전자통신학회논문지
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• 제13권3호
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• pp.533-538
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• 2018

WLAN 이중 대역 동작을 위한 수정된 야기 다이폴 안테나를 제안하였다. 제안된 안테나는 오픈 슬리브 다이폴안테나와 기생소자들로 구성되었다. 각 WLAN 동작 대역에서 오픈 슬리브의 영향, 방사 특성, 그리고 기생소자의 영향에 관하여 분석하였다. 측정 결과 제안된 안테나의 임피던스 대역폭은 320 MHz (2.4 - 2.72 GHz)와 640 MHz (5.04 - 5.68 GHz)이고 각 WLAN 대역에서의 최대 이득은 7.74 dBi와 6.93 dBi이다.

• 한국정밀공학회지
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• 제26권2호
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• pp.94-100
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• 2009

In diesel engines, it is inevitable that the torsional vibration is produced by the fluctuation of engine torque. Therefore, it is necessary to establish preventive measures to diminish the torsional vibration. The sleeve spring type damper is one of the preventive measures for reducing the torsional vibration. In this study, a closed form equation to predict spring constant of the sleeve spring and torsional characteristic of the torsional vibration damper was proposed to calculate stiffness of the damper and verified their availability through the finite element analysis. The theoretical values have a good agreement with the results obtained by the finite element analysis. The results obtained from the equation derived enable the designers in actual fields to be more efficient.

• 한국기계가공학회지
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• 제14권1호
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• pp.29-35
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• 2015

In this study, a FEM analysis is undertaken of a rubber sleeve which is mounted onto a spreading mandrel so as to avoid marking the first wrappings of coils (known as the 'end-mark'), as occasionally occurs when a concentrated load is placed on the edge of a steel sheet, significantly reducing its quality. A commercial numerical package, ANSYS, was utilized to analyze the structural behavior of the rubber sleeve. In general, the strain of the sleeve increases as the thickness of the rubber layer (H) covering the tubes increases, thus also increasing the surface of the sleeve for a constant boundary condition, and decreasing the pitch (P) between each tube, resulting in an increase in the strain on the surface of the sleeve for all rubber thickness conditions tested here. In a comparison of two different materials, rubber and urethane, when H=3 mm and P=1.1D, the maximum total deformations in these cases are 0.12669 mm and 0.086623 mm, respectively.

• 대한기계학회논문집A
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• 제33권12호
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• pp.1471-1481
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• 2009

In diesel engines, it is inevitable that the torsional vibration is produced by the fluctuation of engine torque. Therefore, it is necessary to establish preventive measures to diminish the torsional vibration. The sleeve spring type damper is one of the preventive measures for reducing the torsional vibration. In this study, the closed form equations to predict the spring constant of a sleeve spring and the torsional characteristics of the torsional vibration damper are proposed to calculate stiffness of the damper and verified their availability through the finite element analysis and experiments. And the stability of the sleeve spring torsional vibration damper is verified by analyzing the inner star and outer star, which are the core parts of the damper, and 2-roll bending process is proposed to manufacture sleeve spring. The program to calculate the initial radius including spring-back effect is developed, and the FEA method to analyze elasto-plastic problem was verified through analysis of 90$^{\circ}$bending process. The results of the analysis are in good agreements with those of the experiments. The newly proposed method can be used as an advanced technique that remarkably curtails cost of production and replaces the conventional forming.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.198-203
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• 2008

In the present study, the deformation behavior of both of metal and polymer combination on impact was investigated. They have showed a different deformation behavior when the co-axially combined projectile was impacted on rigid target. The theory according to Taylor's simplified approach assumes an ideally rigid-plastic material model exhibiting rate-independent behavior and simple one-dimensional wave propagation concepts that neglect radial inertia. In the case of impact with polymeric materials, elastic strain in general are not negligible compared with plastic strain; and the rigid-plastic material behavior assumed by Taylor for metallic materials cannot be applied any more. Since, the sleeve and the core materials have widely different mechanical properties, they will produce a significant difference of mechanical impedance with each other. Therefore these impedance mismatch influences on the deformation behavior sleeved polymer projectile on impact. As a result, sleeved projectiles will generate a very interesting impact behavior. Therefore, the according to sleeved metal material and core polymer material can see expected. The objective of this study was to investigate the factors which influences on deformation behavior pattern of sleeve materials surface.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 춘계학술대회논문집
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• pp.214-219
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• 2002

As the tangential flow inside the clearance of tribe elements such as bearings and seals is increased as the shaft speed increases, the system stability will be decreased due to the increment of the instability parameter. To reduce the tangential flow inside the clearance of the balance sleeve, anti-swirl injection mechanism is applied. The balance sleeve is used in resisting the axial force induced by impeller in high pressure multi-stage pump. In this paper, total three cases are experimentally investigated; original balance steeve, anti-swirl injection balance steeve with 0 axial degree and anti-swirl injection balance sleeve with 30 axial degree. Experiments are focused in the comparison of vibration level and leakage flow rate. The results clearly shows that the anti-swirl injection balance sleeve with 0 axial degree improves the vibration characteristics. However, the anti-swirl injection balance sleeve with 30 degree aggravates the vibration characteristics. In the standpoint of leakage performance, both anti-swirl injection balance sleeves show the better result than the original balance sleeve.

• 한국정밀공학회지
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• 제26권12호
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• pp.94-101
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• 2009

In diesel engines, it is inevitable that the torsional vibration is produced by the fluctuation of engine torque. Therefore, it is necessary to establish preventive measures to diminish the torsional vibration. The sleeve spring type damper is one of the preventive measures for reducing the torsional vibration. In this study, 2-roll bending process was proposed to manufacture sleeve spring; The program to calculate the initial radius including springback effect was developed and the FEA method to analyze elasto-plastic problem was verified through analysis of 90 degree bending process. The elasto-plastic analysis of 2-roll bending process was carried out by the FEA method verified to set a new criterion, and the new process design parameter(contact angle) in the 2-roll bending process was proposed.

• 한국의류학회지
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• 제26권11호
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• pp.1502-1513
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• 2002

The purpose of this study was to find relations between construction factors and adaptability on the 5 available raglan sleeve patterns through the drafting method. Also it was to suggest a functional sleeve pattern according to appearance and adaptability test. Three women in her twenties who have standard figure was selected as subjects. Raglan sleeves of 5 experimental clothes were rated by the appearance test and adaptability test. The major conclusions of this study are as follows. 1. The construction factors of the raglan sleeve are sleeve slant, sleeve cap height, biceps line, breast width. Bicep lines increased and sleeve cap height decreased as the sleeve slant decreased. The higher adaptability scores of raglan sleeves were, the lower sleeve slants were. 2. According to the appearance evaluation, B type was recorded the highest score 3. According to the adaptability scores, A type was recorded the highest score. In the pulled length of the waist-line, A type was the lowest movements among the pattern type. In the pulled length of the sleeve-line, A type was the lowest movements among the pattern types. Therefore A type was evaluated by the bort functional sleeve pattern type. Through the experiments, it was known that appearance and adaptability of the raglan sleeve patterns were effected by construction factor.

• Journal of Welding and Joining
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• 제17권1호
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• pp.82-87
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• 1999

The basic remote sleeve repair-welding technology by the pulsed Nd:YAG laser for increasing the lifetime of the steam generator tube in a nuclear power plant has been developed. The relationship between the connection width and welding parameters have been investigated for the fundamental research to apply the sleeve-repair-welding technique to the nuclear industry. The Inconel 600 tube and Inconel 690 sleeve used for high temperature and high pressure service were welded as round lap welding by Nd:YAG laser. It was observed that the tensile shear strength, 340MPa of the welded specimen is equivalent to about 60% of that of the base metal (Inconel 600), 550MPa. The difference between the hardness of the base metal and that of the laser welds was about 10%. Ductile fracture was partly occurred in the weld but the cracking has not been observed. In spite of absence of the crack, the strength of welds was not sufficient in terms of the tensile shear strength.

• 한국소음진동공학회논문집
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• 제12권8호
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• pp.632-638
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• 2002

As the tangential flow inside the clearance of tribo elements such as bearings and seals is increased as the shaft speed increases, the system stability will be decreased due to the increment of the instability parameter. To reduce the tangential flow inside the clearance of the balance sleeve, anti-swirl injection mechanism is applied. The balance sleeve is used in resisting the axial force induced by impeller in high pressure multi-stage pump. In this paper, total three cases are experimentally investigated; original balance sleeve, anti-swirl injection balance sleeve with 0 axial degree and anti-swirl injection balance sleeve with 30 axial degree. Experiments are focused in the comparison of vibration level and leakage flow rate. The results clearly shows that the anti-swirl injection balance sleeve with 0 axial degree improves the vibration characteristics. However, the anti-swirl injection balance sleeve with 30 degree aggravates the vibration characteristics. In the standpoint of leakage performance, both anti-swirl injection balance sleeves show the better result than the original balance sleeve.