• 한국공간구조학회논문집
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• 제14권4호
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• pp.55-64
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• 2014

In this study, Intersecting Tensegrity System that is integrated solid compression members with tension members was presented. This system is set up by connecting upper and lower compression members of pyramid shape with exterior tension members. In this system, the solid compression members are intersected each other and connected by a tension member in the center. This system is a variation of Tensegrity system, has a improved feature that the system is able to induce prestresses in all of tension members easily by adjusting the distance of a tension member in the center. The proposed system was studied by modeling, and the structural behavior of the system was investigated by mechanical analysis of the model. Furthermore, the features of the structural behavior variations was investigated when the composition elements(total height, size of surface, intersection length, etc.) are changed variously. It was also showed that the system is able to be used as a temporary space structure system with a membrane roof of inverse conical shape.

• 한국추진공학회지
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• 제19권6호
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• pp.1-9
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• 2015

본 연구에서는 전열포의 플라즈마 발생장치에서 외부회로로부터 가해지는 펄스형 전기에너지에 의한 플라즈마 발생현상을 대상으로 영차원적 모델링 및 전산해석을 수행하였다. 전극 사이의 보어 내 플라즈마의 균일 온도 가정을 채용하여 질량 및 에너지 방정식을 간소화하였으며, 보어 및 전극 표면 상의 용발 모델 및 플라즈마 물성치 계산모델과 연계하였다. 해석결과는 1차원적 해석모델과 비교하여 상당히 일치함을 보여 영차원적 해석결과의 유효성을 확인할 수 있다.

• 동력기계공학회지
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• 제8권3호
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• pp.30-35
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• 2004

In the steel making industries, the continuous casting process has been applied to the number of company because of its economical benefit. Casting rolls are utilized for frictional drive and transport of solidifying slap. Dimensional tolerances, mechanical stability and surface condition of the cast roll can affect both the surface and internal quality of the product being cast. To overcome these problems, the industry is accelerating on the rate of technology improvements. Samples were overlaid on the S45C steel by submerged arc welding process. And the hardness, wear, electrochemical corrosion and oxidation tests were carried out. Test results were that all these materials were satisfying basic requirements of caster rolls. By these results, the addition of 0.1%Nb and 0.15%V increase mechanical properties and tempering resistance by its superior carbide forming characteristics in low carbon $12{\sim}13%Cr$ martensitic stainless steels.

• International Journal of Precision Engineering and Manufacturing
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• 제6권3호
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• pp.24-28
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• 2005

Stress state of chip formation zone is one of the main problems in metal cutting mechanics. In two-dimensional case this process is usually considered as consistent shears of work material along one of several shear surfaces, separating chip from workpiece. These shear planes are assumed to be trajectories of maximum shear stress forming corresponding slip-line field. This paper suggests a new approach to the constriction of slip-line field, which implies uniform compression in chip formation zone. Based on the given model it has been found that imaginary shear line in orthogonal cutting is close to the trajectory of maximum normal stress and the problem about its determination has been considered as well. It has been shown that there is a second central slip-line field inside chip, which corresponds well to experimental data about stress distribution on tool rake face and tool-chip contact length. The suggested model would be useful in understanding mechanistic problems in machining.

• 한국정밀공학회지
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• 제31권12호
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• pp.1161-1170
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• 2014

Delta sash is an important part of automobile door, which has the functions of supporting and guiding seesaw of car's window, preventing dust and air from outside. In previous manufacturing process, each part of the delta sash was independently formed by tandem processes, and rubber is bonded to steel by poisonous glue. So, the previous processes, including roll forming process and toxic gases, had low production rate and high failure rate. In this study, progressive process design of the delta sash was proposed in order to increase productivity and high utilization of the materials. And instead of the poisonous glue used for adhesion of rubber in the previous tandem process, embossing and piercing processes were designed in the new guide to help the rubber to adhere well to steel. And the optimal piercing distance was designed to ensure structural safety, and prototypes were manufactured for verifying reliability of the processes.

• 대한기계학회논문집B
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• 제22권12호
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• pp.1657-1668
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• 1998

In the analysis of a mushy solidification system with natural convection using a fixed grid method, the enthalpy method has been used to account for the release of latent heat. The variable viscosity, Darcy source, and hybrid methods have been employed for the velocity suppression in a mushy region. The choice of the values of solid viscosity and permeability constant in conjunction with the Darcy source term plays an important role in forming the location and shape of the phase boundaries. In this work the effects of these major parameters related to steady-state behavior in the system of mushy solidification are investigated through a simple test problem. The effective specific heat based on the spatial gradients of the enthalpy and temperature is adopted for the treatment of the release of latent heat. The effects of the Prandtl and Rayleigh numbers on the shape of mushy region are examined using the hybrid method.

• 한국표면공학회지
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• 제40권1호
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• pp.16-22
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• 2007

Recently, mesoporous metallic materials are becoming more and more important in various applications like catalysts, electrochemical detectors, batteries, and fuel cells because of their high surface area. Among the various methods for manufacturing mesoporous structure, surfactant templating method followed by electroplating has been tried in this study. A mesoporous metallic film was prepared by electrodeposition from electroplating solution mixed with surfactant template. Nonionic type lyotropic liquid crystalline surfactant, Brij56, and nickel acetate based solution were selected as a template material and electroplating solution, respectively. To determine the content of surfactant forming a hexagonal column structure, the phase diagram of electroplating solution and surfactant mixture has been exploited by polarized optical microscopy equipped with heating and cooling stage. Nickel films were electroplated on Cu foil by stepwise potential input method to alleviate the concentration polarization occurred during the electroplating process. TEM and XRD analyses were performed to characterize the size and shape of mesostructures in manufactured nickel films, and electrochemical characterization was also carried out using cyclic voltammetry.

• 한국정밀공학회지
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• 제16권4호통권97호
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• pp.19-25
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• 1999

This paper addresses a development work of a SLA apparatus on laboratory basis. The SLA test machine is composed of optical, movement, curing and control subsystems. Optical part is performed by a He-Cd laser with mirror combination and mechanical movement is achieved by X-Y table. The developed system is evaluated by several test runs, and shows a good precision capability in forming a basic part. The technique used in this work can be extended to replace the high technology transfer cost of commercial RP machine.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2002년도 추계학술대회 논문집
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• pp.103-107
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• 2002

A contact-less power supply system (CPS) allows electrical energy to supply to mobile consumers without any electrical or mechanical contact. CPS works in the same principle as a transformer, with the track litz cable forming the primary circuit and the pickup as the secondary. The track power supply generates the high frequency alternating current in the track cable. The captured AC magnetic field generated by the track conductors produces electrical energy in the pickup coil and the pickup rectifier converts the high frequency AC power to DC while regulating the power to the load. This paper presents the theoretical analysis, simulation and experiment리 results of the series-parallel resonant converter working as contact-less power supply system.

• 한국세라믹학회지
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• 제39권5호
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• pp.460-466
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• 2002

티타늄 임플란트의 표면을 열산화법을 이용하여 티타늄의 표면 위에 생체활성을 갖는 $TiO_2$ 박막을 생성시켜 다양한 의료분야의 응용 가능성을 검토하였다. 시판되고 있는 순수한 티타늄 디스크를 세척 공정을 거친 후, 공기와 아르곤 분위기에서 500, 550, 600, 650, 700${\circ}C$의 온도로 10분간 각각 열산화 처리를 실시하였다. 열처리된 시편의 인산칼슘 결정의 형성 능력을 시험하기 위하여 36.5${\circ}C$의 Eagle's minimum essential medium 용액에서 15일 동안 침적시험을 행하였다. 침적하기 전과 후의 시편의 표면 형상과 표면 조성을 Field Emission-Scanning Electron Microscopy(FE-SEM)와 Energy Dispersive X-ray Spectrometry(EDS)로 각각 분석하였다. In vitro 시험에서 미세한 $TiO_2$ 결정이 생성된 박막의 표면에는 탄소가 함유된 인산칼슘 결정이 생성됨을 확인하였다.