• 한국CDE학회논문집
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• 제10권5호
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• pp.375-379
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• 2005

Durability of rubber dust cover in the ball joint for automotive suspension parts is analyzed by FEM and compared with experimental data. Upper open area of ball joint is sealed by dust cover for preventing outflow of the lubricating oil and intrusion of send, dust, water, etc. This rubber cover undergoes repeated loadings such as tension and compression while the car is running. Analysis about rubber material needs to consider every kinds of nonlinearities arise in finite element analysis, which are geometric nonlinearity due to large displacement and small strain, materially nonlinearity and nonlinear boundary condition such as contact. The deformation behavior of dust cover is analysed by using the commercial finite element program MARC. In the study, this program could solve these kinds of nonlinear analysis accurately. Finite element model of dust cover is considered as 3-dimensional half model based on 2-dimensional axisymmetric model. Material property of rubber is modeled by Ogden model and input data for calculation takes form uniaxial tension test of rubber specimen. The final object of the study is obtaining the design specification of dust covers and the result of analysis should be a useful data to design of rubber cover.

• 대한기계학회논문집A
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• 제21권6호
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• pp.871-883
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• 1997

Kinetodynamics of a cam driving slider mechanism consists of kinematic analysis and force analysis. The kinematic analysis is to determine the kinematic characteristics of a cam driving mechanism and a slider mechanism. The force analysis is to determine the joint forces of links, the contact forces of the cam and follower, and the driving torque of a main shaft. This paper proposes a close loop method and a tangent substitution method to formulate the relationships of kinematic chains and to calculate the displacement, velocity and acceleration of the cam driving slider mechanism. Also, and instant velocity center method is proposed to determine the cam shape from the geometric relationships of the cam and the roller follower. For dynamic analysis, the contact force and the driving torque of the cam driving slider mechanism are calculated from the required sliding forces, sliding motion and weight of the slider.

• 한국생산제조학회지
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• 제21권1호
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• pp.130-136
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• 2012

Dynamic as well as static and geometric design parameters such as inertia, tooth profile, backlash and clearance can be directly considered via multi-body dynamic analysis along with contact analysis. However, it is time consuming to use finite elements for the consideration of the tooth flexibility in the multi-body dynamic analysis of gears. A computationally efficient procedure, so called, Gear Stiffness Module, is suggested to resolve this calculation time issue. The characteristics of gear tooth compliance are discussed and rotational stiffness element concept for the Gear Stiffness Module is presented. Transmission error analyses for a spur gear system are carried out to validate the reliability and efficiency of the module. Compared with the finite element model, the Gear Stiffness Module yields considerably similar results and takes only 3% of calculation time.

• Steel and Composite Structures
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• 제38권6호
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• pp.617-635
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• 2021

This paper numerically investigated the behavior of built-up square concrete-filled steel tubular (CFST) columns under combined preload and axial compression. The finite element (FE) models of target columns were verified in terms of failure mode, axial load-deformation curve and ultimate strength. A full-range analysis on the axial load-deformation response as well as the interaction behavior was conducted to reveal the composite mechanism. The parametric study was performed to investigate the influences of material strengths and geometric sizes. Subsequently, influence of construction preload on the full-range behavior and confinement effect was investigated. Numerical results indicate that the axial load-deformation curve can be divided into four working stages where the contact pressure of curling rib arc gradually disappears as the steel tube buckles; increasing width-to-thickness (B/t) ratio can enhance the strength enhancement index (e.g., an increment of 1.88% from B/t=40 to B/t=100), though ultimate strength and ductility are decreased; stiffener length and lip inclination angle display a slight influence on strength enhancement index and ductility; construction preload can degrade the plastic deformation capacity and postpone the origin appearance of contact pressure, thus making a decrease of 14.81%~27.23% in ductility. Finally, a revised equation for determining strain εscy corresponding to ultimate strength was proposed to evaluate the plastic deformation capacity of built-up square CFST columns.

• 한국의류학회지
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• 제34권11호
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• pp.1880-1888
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• 2010

This study was a preliminary investigation of the influence of surface characteristics of substrates on the detergency of particulate soil. A PET film was surface modified with NaOH and DMF for different times. The surface morphology of the film was scanned by AFM and the surface energies were calculated from the measured contact angles between several solutions and film based on a geometric mean and the Lewis acid base method. The surface morphology of the PET film treated with NaOH and DMF became more etched and swelled with an increased treatment time, respectively. The surface roughness and surface area of film treated with NaOH enlarged with increased treatment time. However, the coefficient of friction of film treated with NaOH and coefficient of friction, surface roughness, and surface area of film treated with DMF increased and then decreased with increased treatment time. The contact angle of film treated with DMF decreased with increased treatment time in water and surfactant solution; however, the effect of treatment time on the contact angle was different in both solutions for film treated with NaOH. By the treatment of PET film with NaOH and DMF, the polar group of the surface energy increased and the nonpolar group decreased; however, the change of total surface energy was not significant.

• 대한기계학회논문집A
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• 제26권8호
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• pp.1527-1533
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• 2002

When a mechanism transfers a motion to an intersected shaft, a cylindrical cam mechanism may be the best choice among the mechanisms. The cylindrical cam with a roller follower provides to transfer the motions to the intersect shafts simply without other connecting equipments of the intersect shafts. Typical example may be a roller-gear-cam mechanism. But the shape of the cam must be exactly defined in order to satisfy the conditions for the prescribed motion of the follower. This paper proposes a new method for the shape design of the cylindrical cams and also a CAD program is developed by using the proposed method. The relative velocity method calculates the relative velocity of the follower versus the cam at a center of roller, and then determines a contact point by using the geometric relationships and the kinematic constraints. The constraint used in the relative velocity method is that the relative velocity must be parallel to a common tangent line at the contact point of two independent bodies, i. e. the cam and the follower. Then, the shape of the cam is defined by the coordinate transformation of the trace of the contact points. Finally, this paper presents an example in order to prove the accuracy of the proposed methods in this paper and the application of the CAD program"CamDesign".

• 한국산학기술학회논문지
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• 제17권3호
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• pp.310-316
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• 2016

도전성 평판에 부분적으로 걸쳐 회전하는 축형 동전기 휠을 구동원으로 이용하는 비접촉 반송 시스템을 제안한다. 회전하는 동전기 휠에는 3축력이 발생되는데 이 중 중력방향 힘과 횡방향 힘은 자기안정성을 갖고 있으므로 공간상에서 반송 시스템의 동적 안정성을 확보하기 위해서는 길이 방향 힘만을 제어하는 것으로 충분하다. 동전기 휠은 원주 방향을 따라 주기적으로 반복되는 극성을 갖는 영구자석으로 구성되어있으므로 기본 극의 기하학적 형상이나 극수 등은 안정성 여유에 큰 영향을 미친다. 또한 휠과 전도판간의 중첩된 영역 역시 횡방향으로의 강성을 결정하는 주요 인자이므로 본 논문에서는 안정성을 성능 지표로 휠을 구성하는 주요 설계 변수에 대한 민감도 해석을 수행한다. 얻어진 설계 값을 이용하여 제작된 시스템으로 휠을 포함하는 이동 개체의 수동적인 안정성을 실험적으로 검증한다.

• 한국환경보건학회지
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• 제40권6호
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• pp.435-441
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• 2014

Objectives: Bisphenol A, or BPA, is a chemical component in polycarbonate plastic with which many people come into contact every day. A great deal of controversy has arisen over its safety since this material, which is known to disrupt the human endocrine system and cause neurological difficulties and cancer, is commonplace in beverage containers, food can liners, and receipt paper rolls. In this study, we determined the levels of exposure to BPA of workers in the service industry depending on the number of receipts contacted. Methods: The participants were 16 male and 18 female workers employed in the service industry. Using a questionnaire, we investigated general and job characteristics. Urine samples were collected and analyzed by the LC-MS/MS technique after enzymatic hydrolysis and solid phase extraction (SPE). Results: The geometric mean (GM) concentration of urinary BPA from all subjects was 1.02 ng/ml. Workers were exposed significantly to more BPA according to the number of receipts they contacted, their work experience, and working hours per day. The BPA concentration of those who touched more than 100 receipts per day was 3.09 ng/ml, while that of the other participants was 0.61 ng/ml. It was shown that wearing gloves can protect from BPA exposure. Conclusion: We determined the urinary BPA concentrations of workers in service industry and found that the contact with receipts could increase the BPA exposure of service workers.

• 한국건축시공학회지
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• 제16권4호
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• pp.341-348
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• 2016

이 연구에서는 폭발원점으로부터 보호시설의 결정적 피해경감을 위해 설치되는 방호벽의 설계요구조건을 제안한다. 이를 위하여 일부지역에 구축된 방호벽과 관련한 현장조사 및 설계도서 검토를 수행한다. 규명된 방호벽 제원을 바탕으로 구조해석에 사용될 방호벽을 모델링하고, 방호벽에 대한 실질적인 위협을 판단한다. 구조 모델링 및 폭발위협 분석이 완료되면, 방호벽 및 보호시설의 손상정도를 충격, 관입, 파쇄 및 폭압효과 측면에서 수치해석을 통해 계산한다. 해석결과에 따르면, 방호벽의 두께는 최소 45cm 이상이어야 하며, 현재 설치된 방호벽은 단면증설을 통해 구조보강이 필요한 것으로 나타났다.

• 복식문화연구
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• 제19권4호
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• pp.723-739
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• 2011

This research seeks to analyze western men's costume in the Baroque era in relation to men's physical beauty from its most detailed and interesting perspective to fomulate a plausible reasoning related to the aesthetic sense of body as expressed in men's costume. This research used national and international books, theses and internet data upon which to base a literature review for a correct understanding of Baroque style and at the same time empirical research to analyze the body image expressed in men's costume. The Baroque style expressed in the 17th century costume offered a dynamic feeling through wavy curves, and its brilliant and colorful decorations created a passionate and charming mood resembling a flame. Accordingly, this research studied the body image as it appeared in the form of 17th century western men's costume by dividing it into the contact beauty of the human body and the manner of hiding the architectural beauty of the human body. First, the exposed silhouette by clothing coming into contact with the human body could be found mainly in upper-class men's costume in the first half of the 17th century. The shorter and tighter doublets and knee breeches could be analyzed in terms of erotic imagery that emphasized masculinity, aristocratic imagery that stressed a distinctive status, and geometric imagery that expressed a triangular pattern. Second, the constructive expression by hiding the human body could be found in upper-class men's costume starting in the mid-17 century. The wearing of the justaucorps could be studied in terms of how it came into contact with the beauty of the human body but also how this clothing style the hid the architectural beauty of human body.