• 대한기계학회논문집A
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• 제34권11호
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• pp.1765-1771
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• 2010

MEMS 소자의 공정에서 가공된 비아 홀 품질은 소자의 성능에 가장 중요한 요소의 하나이다. Nd:$YVO_4$ 레이저로 가공한 비아 홀에 대한 레이저 미세가공의 일반적인 특징을 설명하고 그것의 측정에 대한 효율적인 최적화 방법을 소개한다. 본 논문의 최적화 방법은 직교다항식, 분산분석과 반응표면최적화는 최적 레이저 공정변수를 결정하고 주요 영향을 이해하는데 사용된다. 유의한 레이저 공정변수를 확인하고 이의 비아 홀 품질에 관한 영향을 고찰하였다. 레이저 공정변수의 최적 수준을 가지는 확인 실험은 최적화 방법의 유효성을 설명하기 위해 수행하였다.

• 한국기계가공학회지
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• 제19권6호
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• pp.73-79
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• 2020

Although engineering plastics that are light-weight and have excellent mechanical performance have been widely applied in various industries in place of steel structures to reduce the burden of cost and time, there have been few studies related to their surface roughness. This study aims to evaluate the optimal effects of feed rate, cutting speed, and depth of cut as cutting parameters as well as nose angle on the surface characteristics of MC nylon in CNC lathe machining. To determine the best conditions under different nose radii, the experiments were performed based on the Taguchi L9(34) orthogonal array method, in which the resulting data was analyzed using the S/N ratio and ANOVA. Results indicate that the most significant contribution was feed rate followed by nose angle and cutting speed, whereas the depth of cut did not influence the performance. This study demonstrates that the suggested method for improving the surface finishing of MC nylon is efficient compared with results obtained from experimentation and prediction.

• 한국해양공학회지
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• 제21권4호
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• pp.1-7
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• 2007

Based on the eigenfunction expansion method, the wave-absorbing performance of a square or circular pile breakwater was investigated. Flow separation resulting from sudden contraction and expansion is generated and is the main cause of significant energy loss. Therefore, evaluation of an exact energy loss coefficient is critical to enhancing the reliability of the mathematical model. To obtain the energy loss coefficient, 2-dimensional turbulent flow is analyzed using the FLUENT commercial code, and the energy loss coefficient can be obtained from the pressure difference between upstream and downstream. It was found that energy loss coefficient of circular pile is 20% that of a square pile. To validate the fitting equation for the energy loss coefficient, comparison between the analytical results and the experimental results (Kakuno and Liu, 1993) was made for square and circular piles with good agreement. The array of square piles also provides better wave-absorbing efficiency than the circular piles, and the optimal porosity value is near P=0.1.

• Tribology and Lubricants
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• 제34권4호
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• pp.132-137
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• 2018

Ultrasonic waves are used in various applications in multiple devices, sensors, and high-power machinery, such as processing machines, welders, and cleaners, because the acoustic vibration frequencies are above the human audible frequency range. In ultrasonic machining, electrical energy at a high frequency of 20 kHz or more is converted into mechanical vibration by a vibrator and an amplifier. This technique allows instantaneous separation between a tool and a workpiece during machining, machining by pulse impulse force at the time of re-contact and minimizes the minute elastic deformations of the workpiece and machine tools due to the cutting effect. The Al7075 alloy used in this study is a typical aluminum alloy with superior strength that is mainly used in aircrafts, automobiles, and sporting goods. To investigate the optimal conditions for machining aluminum alloy using ultrasonic vibration, the present experiment utilized the Taguchi orthogonal array method, and the coefficient of friction was analyzed using the characteristics of the Taguchi technique. In ultrasonic friction and abrasion tests, the changes in the friction coefficient were measured in the absence of ultrasonic vibrations and at 28 kHz and 40 kHz. As a result, the most considerable influence on the friction coefficient was found to be the normal load, and the frequency of ultrasonic vibrations increases, the coefficient of friction increases. It was thus confirmed that the amount of wear increases when ultrasonic vibration is applied.

• 소성∙가공
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• 제13권4호
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• pp.342-349
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• 2004

The form-joining process (or clinching) uses a set of die and punch to impose the plastic deformation-induced geometric constraint on a sheet metal pair. The joining strength from the process ranges 50-70 percent of that of the resistance spot welding. In this paper, a new form-joining process with the aid of an adhesive is proposed in which an epoxy adhesive is applied to a sheet metal pair, and before it cures the pair is clinched to cause the geometric constraint in the form of a protrusion. In order to reduce the forming load and the height of protrusions, a new die and punch set with a very small clearance is devised to reduce the depth of drawing and the forming load. Taguchi method is employed to find the optimal values of design parameters. To implement each case of the orthogonal array, the finite element method is used. The experiments show that in the tensile-shear test, the bonding strength of the new form-joining process with an epoxy adhesive is approximately the same as that of the resistance spot welding; and in comparison with the other two form-joining processes with an epoxy adhesive, the height of protrusions is reduced by more than 65 percent and the forming load by 50 percent.

• 한국전자파학회논문지
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• 제12권5호
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• pp.694-704
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• 2001

본 논문에서는 상세화된 빔 패턴에 대한 제한조건들은 유지한 채 잡음이나 간섭신호에 대한 효과적인 제거를 제공하는 Eigencanceller의 성능을 평가하였다. Eigencanceller는 배열입력으로 간섭신호와 잡음이 수신되는 경우와 희망신호, 간섭신호 그리고 잡음이 수신되는 경우에 따라 제한조건들이 달라지게 되고 최적의 가중치에 대한 해도 달라진다. 각각의 경우에 가중치 벡터에 대한 정상상태에서의 분석을 통해서 희망 신호의 유.무에 관계없이 최적의 가중치 벡터에 대한 식들은 모두 동일하게 간섭신호에 직교하는 부분공간(subspace)으로의 희망신호의 사영의 형태로 간략화 됨을 알 수 있었다. 그리고 Eigencanceller구조가 DMI(direct matrix inversion)방식보다도 우수한 성능을 보임을 수학적인 분석가 시뮬레이션을 통해 살펴보았다.

• 소성∙가공
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• 제16권4호
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• pp.254-259
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• 2007

Dent resistance is an important characteristic to avoid damage on automotive outer panels. From a practical point of view, dents can be caused in a number of ways. Considering doors as an example, denting can occur from stone impacts or from the careless opening of an adjacently parked vehicle door. Denting can occur where the door surface is smooth and may not have sufficient curvature to resist dent. These exterior body parts are designed to improve dent resistance using a combination of work hardening and bake hardening. In brief, dent is affected by the shape of the parts and the material properties such as yield strength, strain and thickness. In this work, forming of door outer panel is investigated by Taguchi method. Main parameters are yield strength, thickness, blank size, blank holding force and so on. For the given value of design parameters, forming analysis of the eighteen cases are carried out according to L18 orthogonal array. After comparing the performance by simple conversion of simulation results into dent resistance, the final suggestion of the forming parameters is verified for the optimal improvement of dent resistance.

• 한국자동차공학회논문집
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• 제17권1호
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• pp.176-181
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• 2009

The passenger airbag(PAB) designed for standard sized adults may induce unexpected results to children in out-of-position(OOP) postures. In this work, using MADYMO software, simulations of the OOP injury of children have been performed with respect to PAB design parameters and child dummy positions. The attention is focused on some details with respect to the injury of 3 and 6 year old children in two OOP postures. Among the various design parameters of the passenger airbag systems, four parameters are selected for the sensitivity analysis of the injury with the Taguchi method: bag folding pattern, vent hole size, position of the cover tear seam and the type of door tear seam. An optimal combination of the parameters is suggested.

• 반도체디스플레이기술학회지
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• 제15권4호
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• pp.86-91
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• 2016

End milling is an important and common machining operation because of its versatility and capability to produce various profiles and curved surfaces. This paper presents an experimental study of the cutting force variations in the end milling of SM25C with HSS(high speed steel) and carbide tool. This paper involves a study of the Taguchi design application to optimize cutting force in a end milling operation. The Taguchi design is an efficient and effective experimental method in which a response variable can be optimized, given various control and noise factors, using fewer resources than a factorial design. This study included feed rate, spindle speed and depth of cut as control factors, and the noise factors were different cutting tool in the same specification. An orthogonal array of $L_9(3^3)$ of ANOVA analyses were carried out to identify the significant factors affecting cutting force, and the optimal cutting combination was determined by seeking the best cutting force and signal-to-noise ratio. Finally, confirmation tests verified that the Taguchi design was successful in optimizing end milling parameters for cutting force.

• 전기전자학회논문지
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• 제22권4호
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• pp.1152-1157
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• 2018

논문에서는 밭농사에 적합하도록 설계된 와이어 기반 농약살포장비의 이동을 위한 구조물 설치 위치의 어려움을 해결하고자 한다. 이를 위해 간접적으로 대지구조를 파악할 수 있는 대지저항률 측정방법과 분석기술을 적용한다. 선정된 밭농사 지역에 일정 간격의 전극을 현장에 설치하고 내장형 제어보드에 다수의 스위치를 구동시켜 대지저항률 데이터를 자동 취득한다. 그리고 2차원 영상복원 알고리즘을 사용하여 대지분석을 수행하고 그 결과를 통해 실제 구조물 타설에 적합한 최적지점을 선정하고자 한다.