• 동력기계공학회지
• /
• 제7권1호
• /
• pp.20-24
• /
• 2003

Boiler is one of the most important utilities providing steam to turbine in order to supply mechanical energy in thermal power plant. It is composed of thousands of tubes for high efficient heat transfer. Water is converted to steam inside the waterwall tubes. Many chemical components dissolved in boiler water come out of itself, deposit to the tube wall surface, prohibit heat transer, raise tube metal temperature, eventually fail the boiler tubes. Several tasks such as fracture surface study, tensile test, hardness test, metallurgical test, composition analysis of sticking elements were conducted to identify the root cause of tube failure.

• 한국원자력학회:학술대회논문집
• /
• 한국원자력학회 2004년도 추계학술발표회 발표논문집
• /
• pp.537-538
• /
• 2004

The performance of the ECWS was predicted for the anticipated operational occurrences. The inadvertent close of loop isolation valve is the most severe case for the five anticipated operational occurrences considered in this design and meets the design criteria of the ECWS. The correlation of critical heat flux for the geometry of three pins sub-channel analysis will be studied in the feature.

• 한국소음진동공학회논문집
• /
• 제21권3호
• /
• pp.199-205
• /
• 2011

This paper proposes a framework to predict the mechanical fault of hot rolling mill system (HRMS). The optimum process of HRMS is usually identified by the rotating velocity of working roll. Therefore, observing the velocity of working roll is relevant to early know the HRMS condition. In this paper, we propose the framework which consists of two methods namely spectrum matrix which related to case-based fast Fourier transform(FFT) analysis, and three dimensional condition monitoring based on novel visualization. Validation of the proposed method has been conducted using vibration data acquired from HRMS by accelerometer sensors. The acquired data was also tested by developed software referred as hot rolling mill facility analysis module. The result is plausible and promising, and the developed software will be enhanced to be capable in prediction of remaining useful life of HRMS.

• 한국가구학회지
• /
• 제19권5호
• /
• pp.307-318
• /
• 2008

Scientific methods for grading urushi lacquer includes general properties (viscosity, pH etc), and quantitative analysis of moisture, urushiol, gum, laccase content etc, and properties of coating layer such as set to touch drying time, gloss, color difference, delamination strength, tensile strength of film. The grading results evaluated by scientific method showed n order with chinese urushi lacquer (E) > domestic urushi lacquer (A) > japanese urushi lacquer (C) > chinese urushi lacquer (D) > domestic urushi lacquer (B). It is different from hose of traditional methods. Therefore, a more accurate grading of urushi lacquer should be ade by combining traditional method with scientific method.

• 소성∙가공
• /
• 제14권3호
• /
• pp.207-214
• /
• 2005

Blanking process is widely used fur producing various structural parts. However, fine blanking technology is frequently used as a single step blanking operation with clean cut surface of a sheared surface because the fractured surface of parts causes serious problems in the final product and therefore it must be removed by the post-processing in case of the conventional blanking. In the present investigation, a fine blanking process was designed within the framework of progressive die to produce a carrier plate assembled within the auto transmission. Finite element analysis of the shearing behavior at the respective stage of the progressive fine blanking was conducted to validate the designed die parameters. Finally the designed progressive fine blanking process was experimentally evaluated by using the machined die.

• 한국전산유체공학회:학술대회논문집
• /
• 한국전산유체공학회 2007년도 춘계 학술대회논문집
• /
• pp.130-133
• /
• 2007

A two-phase method in CFD has been developed and is applied to model the cavitation flow. The governing equation system is two-phase Navier-Stokes equation, comprised of the mixture mass, momentum and liquid-phase mass equation. It employs an implicite, dual time, preconditioned algorithm using finite difference scheme in curvilineal coordinates and Chien ${\kappa}-{\varepsilon}$ turbulence equation. The experimental cavitating flows around ogive-cylinder and venturi type objects are employed to test the solver. To prove the capabilities of the solver, several three-dimentional examples are presented.

• 한국정밀공학회지
• /
• 제14권11호
• /
• pp.17-24
• /
• 1997

Despite the increasing demands for improved product design, a limited number of works have been reported in the field of sheet metal forming. In the present study, introducing the Taguchi method, an otpimal and robust combination of parameters in found and a data base management system is utilized for knowledge acquisition. Analysis data, estimation rules of formability and graphical representation of the analysis have been employed for the dewigner's understanding and evaluation. The developed system is applied to a deep drawing process. Through the present study, it is shown that the developed systerm is useful for the design and the formability estimation of sheet metal forming processes.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2002년도 추계학술대회 논문집 Vol.15
• /
• pp.67-70
• /
• 2002

The electrodeless lamp is intended as a high efficacy replacement for the incandescent reflector lamp in many applications. but Increasing awareness of electromagnetic compatibility(EMC) issues in lighting application, the problems of interference generation by electrodeless fluorescent lighting system have been highlighted. In this paper, Maxwell 2D finite element analysis program(ansoft) is used to obtain electromagnetic properties associated with the coil and nearby structures. and also evaluated Flux, B, H, by changing the input current.

• 소성∙가공
• /
• 제20권4호
• /
• pp.291-295
• /
• 2011

The injector housing has two functions, namely, positioning the injector and protecting it from coolant. The conventional manufacturing process of the injector housing by machining has some drawbacks such as considerable loss of material and environmental pollution caused by excessive use of cutting oil. In this paper, precision cold forging is proposed as a new manufacturing process in order to improve these issues. A numerical study was conducted to compute the metal flow, strain, load and other process variables using DEFORM-2D, a finite element analysis(FEA) code for metal forming. Two process methods were investigated and optimal conditions were computed with the FEA code. A prototype was manufactured from the optimal process method and the metal flow and hardness were obtained from the prototype.

• 유공압시스템학회논문집
• /
• 제3권1호
• /
• pp.7-14
• /
• 2006

In this paper, an in-process diagnosis method for performance of position control servo system was studied, which was based upon null bias, slew-rate ratio and delay time measurement. Slew-rate ratio and delay time were analyzed by theoretical analysis, computer simulation and experiment. As a result of these analysis, when spool of servovalve was weared, slew-rate ratio was decreased and delay time was increased.