In the development of a digital multi-process welding machine, we aimed to analyze the heat dissipation effects resulting from changes in the transformer's shape. Two installation configurations for the transformer, vertical and horizontal, were proposed. Thermal-flow analysis was conducted for the welding machine, taking into account variations in spacing between each proposed configuration. The results indicated that the shape and spacing of the components did not significantly alter the airflow around the reactor coil, which is the main heat-generating component of the machine. When comparing the heat dissipation effects across models with different transformer spacings, it was observed that models with narrower spacing exhibited improved heat dissipation, while the vertical configuration demonstrated a slightly higher heat dissipation effect overall. Transient analysis revealed the irregularities in internal flow and the resulting scattered temperature distribution over time within the welding machine.

The present research focuses on the tribological behavior of the AA5083 alloy-based hybrid surface composite using aluminosilicate and multi-walled-carbon nanotube through friction stir processing for automotive applications. The friction stir processing parameters (tool rotation and traverse speed) are varied based on full factorial design to understand their influence on the tribological characteristics of the developed hybrid composite. The surface morphology and composition of the worn hybrid composite are examined using a field-emission scanning electron microscope and an energy-dispersive x-ray spectroscope. No synergistic interaction is observed between the wear rate and friction coefficient of the hybrid composite plate. Also, adhesive wear is the major wear mechanism in both base material and hybrid composite. The influence of friction stir process parameters on wear rate and the friction coefficient is analyzed using the hybrid polynomial and multi-quadratic radial basis function. The models are utilized to optimize the friction stir processing parameters for reducing the rate of wear and friction coefficient using multi-quadratic RBF algorithm optimization.

In this study, we proposed a simulator for the development of a digital multi-process welding machine and a welding process monitoring system. The simulator, which mimics the data generation process of the welding machine, is composed of process control circuit, peripheral device circuit, and wireless communication circuit. Utilizing this simulator, we aimed to develop a welding process monitoring system that can monitor the welding situations of four multi-process welding machines and three processes each, with data transmission through wireless communication. Through the operation of the proposed simulator, sequential digital processing of multi-process welding data and wireless communication were achieved. The welding process monitoring system enabled real-time monitoring and accumulation of the process data. The selection of upper and lower limits for process variables was carried out using a deep neural network based on allowable changes in bead shape, enabling the management of welding quality by applying a process control technique based on the trend of received data.

Most of automobile steering parts are manufactured through the multi-stage cold forging process using round-bar drawn materials. The same process is applied to the ball stud parts of the outer ball joint, and various research activities are being carried out to reduce the extreme manufacturing cost in order to survive in the limitless competition. In this paper, we present a quantitative prediction method for the limiting life of the die as a method for cost reduction in the multi-stage cold forging process. The load on the die was minimized by distributing the forming load based on process optimization through finite element analysis. In addition, based on the quantitative prediction algorithm of the limiting life of the die, the application of the split die and the optimization of the phosphate treatment of the material surface are presented as a conclusion as a method to improve the limiting life of the die.

In this study, as part of the paradigm shift for manufacturing innovation, data from the multi-stage cold forging process was collected and based on this, a big data analysis technique was introduced to examine the possibility of quality prediction. In order for the analysis algorithm to be applied, the data collection infrastructure corresponding to the independent variable affecting the quality was built first. Similarly, an infrastructure for collecting data corresponding to the dependent variable was also built. In addition, a data set was created in the form of an independent variable-dependent variable, and the prediction accuracy of the quality prediction model according to the traditional statistical analysis and the tree-based regression model corresponding to the big data analysis technique was compared and analyzed. Lastly, the necessity of changing the manufacturing environment for the use of big data analysis in the manufacturing process was added.

Forged part made of Cold heading quality wire materials are used for automotive brake systems. The cost reduction of forged products is a major issue because of the strict shape change. A series of studies were conducted to minimize the cost of EPB spindle process among brake parts. In order to reduce the material cost, heat treatment-abbreviated material was applied and the formability on the processes was verified by the ductile fracture theory. In addition, the causes of shape fixation and die life degradation were analyzed using the numerical simulation. The process cost has been minimized by re-designing process, changing the product shape, and the die material.

In this study, using a wet chemical process, we evaluate the effectiveness of different solution concentrations in removing layers from a solar cell, which is necessary for recovery of high-purity silicon . A 4-step wet etching process is applied to a 6-inch back surface field(BSF) solar cell. The metal electrode is removed in the first and second steps of the process, and the anti-reflection coating(ARC) is removed in the third step. In the fourth step, high purity silicon is recovered by simultaneously removing the emitter and the BSF layer from the solar cell. It is confirmed by inductively coupled plasma mass spectroscopy(ICP-MS) and secondary ion mass spectroscopy(SIMS) analyses that the effectiveness of layer removal increases with increasing chemical concentrations. The purity of silicon recovered through the process, using the optimal concentration for each process, is analyzed using inductively coupled plasma atomic emission spectroscopy(ICP-AES). In addition, the silicon wafer is recovered through optimum etching conditions for silicon recovery, and the solar cell is remanufactured using this recovered silicon wafer. The efficiency of the remanufactured solar cell is very similar to that of a commercial wafer-based solar cell, and sufficient for use in the PV industry.

This study is about the process capability index (PCI). In this study, we introduce several indices including the index CPR and present the characteristics of the CPR as well as its validity. The difference between the other indices and the CPR is the way we use to estimate the standard deviation. Calculating the index, most indices use sample standard deviation while the index CPR uses range R. The sample standard deviation is generally a better estimator than the range R . But in the case of the panel process, the CPR has more consistency than the other indices at the point of non-conforming ratio which is an important term in quality control. The reason why the CPR using the range has better consistency is explained by introducing the concept of ‘flatness ratio’. At least one million cells are present in one panel, so we can’t inspect all of them. In estimating the PCI, it is necessary to consider the inspection cost together with the consistency. Even though we want smaller sample size at the point of inspection cost, the small sample size makes the PCI unreliable. There is ‘trade off’ between the inspection cost and the accuracy of the PCI. Therefore, we should obtain as large a sample size as possible under the allowed inspection cost. In order for CPR to be used throughout the industry, it is necessary to analyze the characteristics of the CPR . Because the CPR is a kind of index including subgroup concept, the analysis should be done at the point of sample size of the subgroup. We present numerical analysis results of CPR by the data from the random number generating method. In this study, we also show the difference between the CPR using the range and the CP which is a representative index using the sample standard deviation. Regression analysis was used for the numerical analysis of the sample data. In addition, residual analysis and equal variance analysis was also conducted.

In this study, a method to remove residual powder on a multi-layered graphene and a new approach to transfer multi-layered graphene at once are studied. A graphene one-step transfer (GOST) method is conducted to minimize the residual powder comparison with a layer-by-layer transfer. Furthermore, a residual powder removing process is investigated to remove residual powder at the top of a multi-layered graphene. After residual powder is removed, the sheet resistance of graphene is decreased from 393 to 340 Ohm/sq in a four-layered graphene. In addition, transmittance slightly increases after residual powder is removed from the top of the multi-layered graphene. Optical and atomic-force microscopy images are used to analyze the graphene surface, and the Ra value is reduced from 5.2 to 3.7 nm following residual powder removal. Therefore, GOST and residual powder removal resolve the limited application of graphene electrodes due to residual powder.

1970년대 중반 석유 파동 이후 대체 에너지 개발에 대한 관심이 커지면서 그 중에서 혐기성 공정에서 발생하는 바이오가스 생산과 활용 기술 개발에 대한 연구가 진행되고 있다. 바이오 가스의 주성분은 50-70%CH4/30-40%CO2으로 이루어져 있고 이 때 메탄을 > 95% 순도로 농축하면 도시가스와 자동차 연료로 사용이 가능하다. 바이오가스의 정제기술로 막 분리법은 낮은 에너지 소모량, 이동성 및 쉬운 작동성 등의 장점을 가지고 있다. 본 연구에서는 바이오가스를 95% 이상의 메탄으로 농축하기 위해 폴리설폰 중공사막과 다단 분리막 공정을 이용하였다. 분리막 공정에서 압력, 온도, 막면적 등 다양한 공정 변수에서 95% 이상의 메탄 순도를 얻기 위한 연구를 진행하였다.

본 연구에서는 막 결합형 축전식 탈염공정의 단수를 10단 형태의 모듈로 설계하여 처리용량을 증대하고자 하였다. MCDI에 사용된 이온교환고분자로는 아민기가 함유된 폴리설폰(APSf)과 술폰기가 함유된 폴리이서이서케톤(SPEEK)을 합성하여 캐스팅법으로 탄소전극에 제조하였다. 공정변수는 흡착전압 및 시간, 탈착전압 및 시간, 공급액의 유속과 농도 등을 달리하여 염 제거효율을 측정하였다. 대표적으로 Nacl 100 mg/L, 유속 100 mL/min, 흡착조건 1.2 V/3 min, 탈착조건 -0.5 V/5 min에서 98.3%의 염 제거효율을 보였다.

바이오가스를 98% 이상의 고순도 메탄가스로 정제하여 자동차연료나 도시가스로 활용한다면 경제적으로 매우 큰 효과를 기대할 수 있다. 본 연구에서는 음 식물쓰레기 처리시설에서 발생하는 바이오가스를 정제하여 98% 이상의 고순도 메탄가스를 95% 이상 분리 회수하는 분리막 정제 시스템 개발을 하고자 하였다. 분리막 공정 설계에 필요한 데이터를 확보하기 위하여 분리막 모듈의 이산화탄소/메탄 혼합기체 분리시험을 수행하였으며, 다양한 운전조건에서 얻어진 실험결과를 바탕으로 공정설계를 수행하였다. 최종 생산되는 메탄 순도 98%, 이산화탄소 순도 95% 이상을 만족하는 운전 조건에서 메탄, 이산화탄소 회수율과 이에 필요한 각 단의 막면적과 비율을 확인하였다.

본 연구에서는 막 결합형 축전식 탈염공정의 단위셀의 단수를 늘려 적층된 10단 형태의 모듈을 설계하여 제작하 였다. 아민기가 함유된 폴리설폰(APSf)과 술폰기가 함유된 폴리이서이서케톤(SPEEK)을 합성하였으며 캐스팅법으로 다공성 탄소전극에 코팅하여 제조하였다. 10단 모듈에 대하여 흡착전압 및 시간, 탈착전압 및 시간, 공급액의 유속과 농도 등의 운전 조건과 CaSO4, MgCl2 등의 2가 이온 용액과 수도수에 대하여 염 제거효율을 측정하였다. 대표적으로 NaCl 100 mg/L의 공급 액을 사용하였을 때, 유속 100 mL/min, 흡착조건 1.2 V/3 min, 탈착조건 -0.5 V/5 min에서 98.3%의 염 제거효율을 보였다.

The purposes of this study were to investigate the influences of channel assessments on the usage of multi-channels by product types, and the differences in the usage of multi-channels among product types in buying decision making process for fashion products. Data were collected from 510 consumers in their 20s to 50s with purchasing experiences through multi-channel distribution system and living in Seoul and Kyunggi province; 491 were analyzed after deleting incomplete questionnaires. Factor analysis, multiple regression analysis and one-way ANOVA were used for statistical analysis by using SPSS 18.0. The results were as follows: 5 factors were extracted for channel assessment: utility, accuracy, risk, price benefit and sharing information. Price benefits, utility and sharing information for online channel tended to influence positively on the usage of online channel and online+offline channels. Accuracy and low perceived risk of offline influenced positively on offline and on+offline channel usages. The usage levels of on-line and off-line channels for cosmetics were significantly lower than the usage levels for clothes and accessories on information search, evaluation of alternatives, and purchase stages. Significant differences were also found in the usage levels of multi-channels (on+off-line) on information search and evaluation of alternatives stages. The usage levels of the multi-channels for clothes were the highest followed by those of accessories and cosmetics in order.

The carbon capture and storage (CCS) technology from industrial flue-gas has been an important environmental issue in these days. However, membrane process has a number of breakthrough-point to commercialization in scale-up. In this work, process optimization for high purity and high CO2 recovery with lower the capture cost has been investigated. Lab-made membrane pilot process using real flue gas has been also set up to derive industrial factor.

A multi-step deposition process for the gap-filling of submicrometer trenches using dimethyldimethoxysilane (DMDMOS), (CH3)2Si(OCH3)2, and CxHyOz by plasma enhanced chemical vapor deposition (PECVD) is presented. The multistep process consisted of pre-treatment, deposition, and post-treatment in each deposition step. We obtained low-k films with superior gap-filling properties on the trench patterns without voids or delamination. The newly developed technique for the gapfilling of submicrometer features will have a great impact on inter metal dielectric (IMD) and shallow trench isolation (STI) processes for the next generation of microelectronic devices. Moreover, this bottom up gap-fill mode is expected to be universally for other chemical vapor deposition systems.

Flat sheet membranes consisting of a selective layer and a porous support usually require gutter layer to reduce the bulk pores of the substrates. The gutter layer mitigates the geometric restrictions of support, which enables selective layer to have defect-free morphology with thin thickness (< 100 nm). For this reason, the gutter layer has been introduced to many industrial membranes, and the systematical studies of the effects of the gutter layer properties on membrane performance should be needed. Herein, we introduced several gutter layers with different thicknesses into graphene oxide intercalated polymer TFC membranes to determine the relationship between gutter layer properties and total membrane performances. This study provides more practical insight to determine the optimum gutter layer properties in designing TFC membranes.