• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2010년도 추계학술대회 논문집
• /
• pp.23-24
• /
• 2010

• 대한물리치료과학회지
• /
• 제22권1호
• /
• pp.43-48
• /
• 2015

Background : The purpose of this study was find out more effective method for improving muscle strengthening in lower extremities according squatting exercise method among knee joint angle 45, 60, 90 degree and between gym ball behind back and wall. Methods : Participants were 21 university students(males 10, females 11) who didn't have any problem with orthopedic surgery. We divided participants to two groups with gym ball group and wall group. Gym ball group were performance squatting exercise with gym ball behind back. Each group had performance squatting exercise according knee joint angle 45, 60, 90 degree. We collected data from E.M.G of Biceps femoris, Gastrocnemius, Vastus medialis and lateralis, Tibialis anterior in lower extremity according knee joint angle 45, 60, 90 degree of each groups. We analyzed data using by ANOVA and ANCOVA of SPSS PC ver. 12.0 in order to determine more effective method according various squatting exercise. Results : Each groups show significantly difference value of biceps femoris, vastus lateralis and medialis, tibialis anterior, gastrocnemius lateralis and medialis among knee joint angle 45, 60, 90 degree. But there was no significantly difference value between gym ball group and wall group according knee joint angle. Conclusions : We suggested that squatting exercise with gym ball was more effective method improving lower extremity muscle strengthening, and changing knee joint angle was more effective compared than continued knee joint angle.

• 한국지능시스템학회논문지
• /
• 제19권4호
• /
• pp.499-503
• /
• 2009

Y. R$\acute{e}$ball$\acute{e}$ [11]교수는 쇼케이적분 기준에 의한 필요측도의 표현에 관해 조사한다. 또한 쇼케이적분 표현관 관련된 필요측도의 순위를 결정 연장을 생각한다. 이 논문에서, 우리는 결정연장이 쇼케이 기대효용에 따른 애매한(구간치로 명명함) 필요측도를 가지는 경우를 생각한다. 더욱이, 구간치 필요측도에 대한 단조 집합치 함수를 갖는 기호에 대한 약 쇼케이적분표현과 필요측도에 대한 구간치 효용함수를 갖는 기호에 대한 강 쇼케이적분 표현에 대한 두 가지 정리를 증명한다.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 2009년도 추계학술대회 논문집
• /
• pp.124-127
• /
• 2009

In this paper, a longitudinal die insert fracture which occurred during cold forging of a high strength ball-stud with a sound die design nearly optimized empirically for relatively low strength material of SCM435 is introduced and the reason is revealed. A comparative study between SCM435 and ESW105 is quantitatively made using a thermoelastic finite element method for die structural analysis coupled with a forging simulator theoretically based on a rigid-plastic finite element method. It has been shown that the longitudinal die insert fracture caused from non-optimized value of shrink fit, emphasizing that the die optimal design is inevitable for cold forging of high strength materials.

• 한국정밀공학회지
• /
• 제23권3호
• /
• pp.171-178
• /
• 2006

The sonication mettled is widely used with surfactants to suspend individual single-walled carbon nanotubes in solution, and it is well known that sonication-induced tube cutting occurs. Recently, it is found out that ultrasonicated nanotubes yield simultaneous separation by tube length and diameter. Nanotubes that have been cut shortest possess the greatest enrichments of large-diameter species. In this study, single-walled carbon nanotubes are cut using a ball milling method. Similar fracture behavior is observed fur the ball milled nanotubes: i.e., large diameter tubes are cut shorter. The ability to separate carbon nanotubes by diameter and length will contribute to tile development of nanotube-based applications.

• 대한수학회보
• /
• 제54권2호
• /
• pp.705-714
• /
• 2017

Let $A^2_{{\alpha},{\beta}}(\mathbb{B}_n)$ denote the space of holomorphic functions that are $L^2$ with respect to a weight of form ${\omega}_{{\alpha},{\beta}}(z)=(1-{\mid}z{\mid}^{\alpha}e^{-{\frac{\beta}{1-{\mid}z{\mid}}}}$, where ${\alpha}{\in}\mathbb{R}$ and ${\beta}$ > 0 on the unit ball $\mathbb{B}_n$. We obtain some results for the boundedness and compactness of $Ces{\grave{a}}ro$ operator on $A^2_{{\alpha},{\beta}(\mathbb{B}_n)$.

• 소성∙가공
• /
• 제16권6호
• /
• pp.479-487
• /
• 2007

Die life is generally estimated taking failure life and wear amount into consideration. In this study, the forging die life was investigated considering both of these two factors. The fatigue life prediction for the die was performed using the stress-life method, i.e. Goodman's and Gerber's equations. The Archard's wear model was used in the wear life simulation. These die life prediction techniques were applied to the die used in the forging process of the socket ball joint of a transportation system. A rigid-plastic finite element analysis for the die forging process of the socket ball was carried out and also the elastic stress analysis for the die set was performed in order to get basic data for the die fatigue life prediction. The wear volume of the die was measured using a 3-dimensional measurement apparatus. The simulation results were relatively in good agreement with the experimental measurements.

• Journal of Advanced Marine Engineering and Technology
• /
• 제12권2호
• /
• pp.35-45
• /
• 1988

In this paper an experimental review of condition monitoring method using time domain vibration signals and statically measured wave forms of a multi-components damaged ball bearing is presented first time. Many investigators studied already about vibration characteristics of a single point damaged ball bearing but they did not make efforts to verify vibration phenomena of a multi-components damaged one. Even in case of a tripple components damaged (i.e, outer race, inner race and rolling element) one, the high frequency resonance technique (HERT) and the displacement time domain technique can be also used for its fault detection. According to experimental results undertaken a static displacement measuring method, the defect locations of components can be proposed confidently with simple calculation of the rotating angles of each component.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2001년도 춘계학술대회 논문집
• /
• pp.346-349
• /
• 2001

Nowadays the amount of plastic products is increasing in modern industry. Plastic materials are continuously developed to satisfy the mechanical, physical, and chemical properties. The increasing application of plastic parts in automobile and aerospace industries is due to the fact that it can reduce the structural weight and can lessen the environmental contamination. Among many manufacturing technologies for plastic parts, the injection molding process is very attractive because of its low cost and short production time. Through various analyses of resin flow and molding process for the conventional gate and cooling mechanism, a new type of mold was designed which had different gate location and cooling systems. Newly designed ball seat has an excellent performances, i.e. diminished weld-line, residual stress density, higher magnitude less crack propagation and smaller dimensional contractions effect.

• 한국공작기계학회:학술대회논문집
• /
• 한국공작기계학회 2004년도 추계학술대회 논문집
• /
• pp.428-432
• /
• 2004

The important problem in the high speed spindles is to reduce and minimize the thermal effect by the motor and ball bearings. Thermal characteristics according to the bearing preload and hollow shaft cooling are studied for the test spindle with the oil mist lubrication and high frequency motor. Bearings and motor e main heat generation, and heat generation by ball bearings as a function of load, viscosity and gyroscopic moment effect are considered. Temperature distribution and thermal displacement according to the speed of spindle are measured by thermocouple and gap sensor. The results show that the fitting preload and hollow haft cooling are very effective to minimize the thermal effect by the motor and ball bearings.