• 대한기계학회논문집A
• /
• 제39권9호
• /
• pp.923-928
• /
• 2015

본 논문에서는 고경도의 재료를 효과적으로 가공하기 위하여 초음파-자기연마 복합가공을 제시하고, 초음파-자기연마 복합가공의 효율성을 검증하기 위해. 실험계획법을 적용하여 각 인자의 영향력을 평가하였다. 그 결과, 기존의 자기연마가공보다 초음파-자기연마가공의 가공효율이 더 높게 나타났으며, 초음파-자기연마 복합가공에서 가장 적절한 주파수는 28kHz 인 것으로 나타났다. 또 표면거칠기에 대한 인자의 영향을 평가하였을 때, 초음파의 진폭이 가장 큰 영향을 미치는 것을 확인하였다. 그러나 $55{\mu}m$ 의 진폭이 적용되었을 때, 자속밀도의 변화에도 불구하고 가공효율이 오히려 떨어지는 것으로 나타났다. 이러한 결과로부터 지나치게 큰 초음파 진폭은 오히려 자기연마가공의 효과를 저하시키는 것임을 알 수 있었다.

• 한국자동차공학회논문집
• /
• 제20권3호
• /
• pp.20-25
• /
• 2012

As a kind of distributed energy system, the co-generation system based Diesel engine using after-treatment device was devised for its environmental friendly and economic qualities. It is utilized in that the electric power is produced by the generator connected to the Diesel engine, and waste heat is recovered from both the exhaust gases and the engine itself by the finned tube and shell & tube heat exchangers. An after-treatment device composed ceramic heater and DOC(Diesel Oxidation Catalyst) is installed at the engine outlet in order to completely reignite the unburned fuel from the Diesel engine. In this study, mutual relation of each experimental condition was derived through minimum number of experiment using Taguchi Design and ANOVA recently used in the various fields. It is found that the total efficiency (thermal efficiency plus electric power generation efficiency) of this system reaches maximum 94.4% which is approximately higher than that of the typical diesel engine exhaust heat recovery system.

• 한국정밀공학회지
• /
• 제19권2호
• /
• pp.114-125
• /
• 2002

As semi-solid forging (SSF) is compared with conventional easting such as gravity die-easting and squeeze casting, the product without inner defects can be obtained from semi-solid forming and globular microstructure as well. Generally speaking. SSF consists of reheating, forging, ejecting precesses. In the reheating process, the materials are heated up to the temperature between the solidus and liquidus line at which the materials exists in the form of liquid-solid mixture. The process variables such as reheating time, reheating temperature, reheating holding time, and induction heating power have much effect on the quality of the reheated billets. It is difficult to consider all the variables at the same time when predicting the quality. In this paper, Taguchi method, regression analysis and neural network were applied to analyze the relationship between processing conditions and solid fraction. A356 alloy was used for the present study, and the learning data were extracted by the reheating experiments. Results by neural network were on good agreement with those by experiment. Polynominal regression analysis was formulated by using the test data from neural network. Optimum processing condition was calculated to minimize the grain size, solid fraction standard deviation, otherwise, to maximize the specimen temperature average. In this time, discussion is liven about reheating process of row material and results are presented with regard to accurate process variables for proper solid fraction, specimen temperature and grain size.

• Journal of Advanced Marine Engineering and Technology
• /
• 제34권8호
• /
• pp.1068-1073
• /
• 2010

용접 넥 플랜지는 파이프간의 상호연결에 널리 사용되고 있다. 이 플랜지는 열간 단조 공정으로 제작되며, 심해에서 고압이 요구되는 분야에 사용되는 경우 플랜지 기저부 및 목 부분에 높은 항복강도가 요구된다. 일반적으로 항복강도 향상을 위해 탄소함유량을 높이면 고 강도를 얻을 수 있으나, 용접이 요구되는 제품의 특성상 탄소함유량을 최대 0.47로 제한함으로써 고용체 강화에 의한 강도 향상에는 한계가 있다. 이러한 경우 탄소 함유량의 변화 없이 강도를 향상시킬 수 있는 결정립 미세화 강화를 이용하여 제품의 항복강도를 향상시킬 수 있다. 본 연구에서는 다구찌 기법을 통해 최적의 결정립 미세화를 위한 단조공정을 제시하고 타당성을 검토하기 위해 유한요소해석을 수행하였다.

• 대한기계학회논문집A
• /
• 제38권8호
• /
• pp.905-910
• /
• 2014

본 논문에서 연구한 스틸그레이팅이란 배수로 덮개로 오수 또는 우수의 경사진 유입로를 형성하여 견고성을 증가시키고, 배수를 원활히 하며, 배수관로 내부의 악취 확산을 방지할 수 있는 배수로 덮개를 말한다. 근래에 생활수준 향상 등으로 인해 도시의 악취 문제가 대두되고 있다. 하지만 기존 제품들은 잦은 고장 등으로 인해 악취 저감 기능을 상실하고 이로 인한 행정력과 예산 낭비를 초래하고 있다. 또한 악취 저감 스틸그레이팅 수요 증가에 따라 예산 절감의 필요성이 대두되고 있다. 따라서 본 연구에서는 다구찌 기법과 솔리드웍스를 이용하여 강성적 측면과 배수 성능적 측면에서 스틸그레이팅의 설계 파라미터를 동시적으로 최적화시키고자 하였다.

• 한국공작기계학회논문집
• /
• 제16권6호
• /
• pp.146-152
• /
• 2007

An active micro-mixer, which was composed of an oscillating micro-stirrer in the microchannel to provide rapid, effective mixing at high flow, rates was analyzed. The effects of molecular diffusion and disturbance by the stirrer were considered with regard to two types of mixer models: the simple straight microchannel and microchannel with an oscillating stirrer. Two types of mixer models were studied by analyzing mixing behaviors such as their interaction after the stirrer. The mixing was calculated by Lattice Boltzmann methods using the D2Q9 model. In this study, the time-averaged mixing index formula was used to estimate the mixing performance of time-dependent flow. The mixing indices of the two models compared. From the results, it was found that the mixer with an oscillating stirrer was much more enhanced and stabilized. Therefore, an optimum design for a dynamic micro-mixer with an oscillating stirrer was performed using Taguchi method in order to obtain a robust solution. The design parameters were established as the frequency, the length and the angle of the stirrer and the optimal values were determined to be 2, 0.8D and ${\pm}75^{\circ}$, respectively. It was found that the mixing index of the optimal design increased 80.72% compared with that of the original design.

• 한국미생물·생명공학회지
• /
• 제49권3호
• /
• pp.337-345
• /
• 2021

Lipase (triacylglycerol lipase, EC 3.1.1.3) is an enzyme capable of hydrolyzing triacylglycerol, to produce fatty acids and glycerol and reverse the reaction of triacylglycerol synthesis from fatty acids and glycerol through transesterification. Applications of lipase are quite widespread in the industrial sector, including in the detergent, paper, dairy, and food industries, as well as for biodiesel synthesis. Lipases by yeasts have attracted industrial attention because of their fast production times and high stability. In a previous study, a lipase-producing yeast isolate was identified as Zygosaccharomyces mellis SG1.2 and had a productivity of 24.56 U/mg of biomass. This productivity value has the potential to be a new source of lipase, besides Yarrowia lypolitica which has been known as a lipase producer with a productivity of 0.758 U/mg. Lipase production by Z. mellis SG1.2 needs to be increased by optimizing the production medium. The aims of this study were to determine the significant component of the medium for lipase production and methods to increase lipase production using the optimum medium. The two methods used for the statistical optimization of production medium were Taguchi and RSM (Response Surface Methodology). The data obtained were analyzed using Minitab 18 and SPSS 23 software. The most significant factors which affected lipase productivity were olive oil and peptones. The optimum medium composition consisted of 1.02% olive oil, 2.19% peptone, 0.05% MgSO₄·7H₂O, 0.05% KCl, and 0.2% K₂HPO₄. The optimum medium was able to increase the lipase productivity of Z. mellis SG1.2 to 1.8-fold times the productivity before optimization.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2009년도 추계학술대회 논문집
• /
• pp.130-136
• /
• 2009

The goal of this paper is to develop a standard side mirror geometry that will perform well across multiple vehicles. One of the important performance attributes of a side mirror is the amount of wind noise generated under the flow conditions on a car. PowerFLOW can be used for Computer Aided Testing of the aeroacoustics performance of a design in addition to directing design modifications based on a detailed analysis of the flow structures responsible for the noise generation. Alternatively, a Design of Experiment (DOE) approach is useful to explore the design space without any a-priori assumptions of the effects of design parameter changes. Some general design guidelines regarding the significant mirror geometry factors will be determined which may help to reduce vehicle development time and cost in the future. The results of this research will also allow us to estimate the trade-off between cost saving and performance optimum related to using a standard mirror shape for different vehicles.

• Design & Manufacturing
• /
• 제14권1호
• /
• pp.15-21
• /
• 2020

Smart systems in different application areas such as automotive, medical and consumer electronics require a novel manufacturing method of electronic, optical and mechanical functions into products. Traditional methods including mechanical assembly, bonding of plastic and electronic circuit cause the problems in large size of products and complicated manufacturing processes. In this study, thermoforming and film insert molding were applied to fabricate a dome shaped plastic part embedded with electronic circuits. The deformation of patterns printed on PET film was predicted by thermoforming simulation using T-SIM, and the results were compared with those by experiment. In order to decrease spring-back after thermoforming, the Taguchi method of design of experiment was used. Through ANOVA analysis, it was found that mold temperature was the most dominant parameter for spring-back. By using flow analysis, gate design was performed to decrease injection pressure. During film insert molding, the wash-out of ink printed on film occurred for Polycarbonate. When the resin was changed to PMMA, the wash-out disappeared due to low melt temperature.

• 한국정밀공학회지
• /
• 제23권4호
• /
• pp.91-98
• /
• 2006

A light guide panel (LGP) is an element of the LCD back light unit, which is used for display devices. In this study, the laser marking process is applied to the fabrication of light guide panels as the new fabrication process. In order to obtain a light guide panel which has high luminance and uniformity, four principal parameters such as power, scanning speed, ratio of line gap, and number of line were selected. A Web-based design tool was developed to generate patterns of light guide panel at any location, and the tool may assist the designer to develop optimized patterns. Topcon-BM7 was used for luminance measurement of each specimen with $100mm{\times}100mm$ area. By Taguchi method optimized levels of each parameters were found, and luminance of $3523cd/cm^2$ and uniformity of 92% were achieved using the laser machined BLU.