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.

Domestic dust remover began to be manufactured and installed in the late 1980s by introducing Japanese products and technologies. Currently, the design standards of dust remover are applied to Japan's design standards and partly sub-unit technology was developed for the domestic environment, but no technology was not developed. In addition, most of the manufacturers are small or small, so many of them have been installed and operated for 25 years because they develop small technologies such as parts deformation and functional addition rather than core technology development. Mechanical dust remover require about 70% of manufacturing costs compared to conventional hydraulic dust remover, which can reduce initial production costs, reduce maintenance costs due to low failure rates, and can be operated reliably. Existing hydraulic dust remover had a problem of contaminating rivers due to leakage of hydraulic oil, but mechanical dust remover have no factors that cause water pollution. Therefore, this study developed a rack-type operating structure for optimal and new construction by developing a multi-stage rack structure of mechanical decontamination components, which are substitutes of conventional rotary and hydraulic dust remover.

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.

To meet rapidly changing market demands, manufacturers strive to increase both of productivity and diversity at the same time. As a part of those effort, they are applying flexible manufacturing systems that produce multiple types and/or options of products at a single production line. This paper studies such flexible manufacturing system with multiple types of products, multiple Bernoulli reliability machines and dedicated buffers between them for each of product types. As one of the prevalent control policies, priority based policy is applied at each machines to select the product to be processed. To analyze such system and its performance measures exactly, Markov chain models are applied. Because it is too complex to define all relative transient and its probabilities for each state, an algorithm to update transient state probability are introduced. Based on the steady state probability, some performance measures such as production rate, WIP-based measures, blocking probability and starvation probability are derived. Some system properties are also addressed. There is a property of non-conservation of flow, which means the product ratio at the input flow is not conserved at the succeeding flows. In addition, it is also found that increased buffer capacity does not guarantee improved production rate in this system.

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.

Reinforced earth retaining walls are applied to various fields such as clay part, cut part, adjacent part of structure (alternation, culvert) and reinforcement soil alternation in Korea. Therefore, they are applied more favorably than concrete retaining wall because of its excellent economy and construction. Analysis of reinforced earth retaining wall construction shows that the height is more than 10m higher than that of foreign countries, and when it is applied in multi - stage, it is more than 20m. The reinforced earth retaining wall was introduced in Korea in the 1980s, and the number of years of damage has been increasing due to the fact that the number of public years has been increased to 30 years since it was first applied to the present. Especially, in the case of multi-stage reinforced earth retaining walls having a height of 10 m or more, And the risk of the risk to reach the situation is found. Therefore, in this study, damage characteristics occurred in reinforced earth retaining wall constructed in multi - stage in expressway were analyzed.

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.

A centrifugal cyclone dust collecting apparatus includes a hydro cyclone dust collecting apparatus for separating solid or liquid using liquid or suspension as a medium. In this study, the formation mechanism and improvement of air core and inner air layer were confirmed through Particle Image Velocimetry. These results showed that the modified experimental model was designed in the conventional method suitable for the separation of juvenile fish and eggs. The inlet speed of the multi-stage hydrocyclone dust collector, which can increase the inlet velocity and minimize floatage in the turbulence chamber, was increased from 0.15 to 0.30 m/s. As a result, the air core was stably formed, the inner air layer was increased with increasing speed. In addition, the dust collecting efficiency of egg and juvenile fish was 97.8% on average, It can infer that this system confirmed the ability to efficiently collect particles of 40 μm or more.

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.

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.

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.

연소 후 생성되는 연소가스 중 CO2는 온실가스 기체중 하나로, CO2를 처리하기 하기 위해 CCS 기술 개발이 세계적으로 주목 받고 있다. 하지만 단일막을 이용한 CO2 포집 공정에서는 약 14%의 CO2를 포함한 연소 배기가스로부터 고 순도, 고회수율을 달성하기란 매우 어렵다. 본 연구에서는 다단막 공정 디자인 및 다양한 운전 변수를 통하여 14%의 CO2를 가지고 있는 혼합모사가스로부터 순도 73% 회수율 74%의 포집 효율을 얻을 수 있었다.

The objective of this study was to investigate the optimal design on the tubular shaft and solid shaft for A-IMS of commercial vehicle. The tubular shaft and the solid shaft were designed by 6 stage processes and the results were analyzed by using a finite element analysis method. The coefficient of friction was set to Oil_Cold conditions as referred to the analysis library. It was found that the actual underfill phenomenon was not observed on the tubular shaft and solid shaft. The metal flow of the tubular shaft and solid shaft revealed that the folding phenomenon was not occurred, so there is no problem in actual production. Principal stress and load characteristics of tubular shaft were higher than those of solid shaft since the tubular shaft has many deformation from stage 1 to stage 3.

다단기체분리 공정을 수행하기 위해 폴리이미드 중공사막 모듈을 제조하여 혼합기체 N2 : SF6 = 50 : 50에 대한 기체분리특성을 확인하였다. 제조된 중공사막 모듈은 0.5 MPa에서 stage cut을 조절하여 투과 유량, 농도 등의 성능을 측정하 였다. 중공사막 모듈은 1단 분리 테스트에서 N2/SF6 선택도가 높을수록 동일한 stage cut에서 높은 SF6 회수율을 얻을 수 있 었다. 1단 시험결과에 따라 SF6 회수율과 농축농도를 동시에 높이기 위해 2단 기체 분리 테스트 진행함으로써 SF6 회수율 95% 이상, SF6 회수농도 98% 이상을 농축할 수 있었다.

The side wall thickness variation of the product to the process of ironing and the die pad was studied using a progressive die of the multi-stage drawing product in the process of ironing and the die pad. Experimental results because ironing is possible to increase the side wall thickness of the product is applied to the intermediate drawing process rather than applied in the initial process. The roundness and concentricity were easy control. A die pad is applied to a stand pad to the sixth step from the first step. The seventh step and the eighth step are applied integrated pad. The integrated pad of the seventh step and the eighth step appeared to be advantageous to control the roundness and concentricity.

Mathematical models are developed for single and multi-stage membrane processes to simulate gas separation in MATLAB®. The single-stage membrane process simulations are validated through comparison with mixed-gas experimental results at different operating condition. Based on this validated single-stage process model, multi-stage membrane processes including 2 or 3 stages membranes with recycle streams are simulated. The resulting simulation outputs are shown to reproduce experiment results with reasonable accuracy. Hence, this process modeling framework can be utilized in future design and optimization studies.

산업화로 인한 온실가스의 발생량이 증가 하면서 지속적인 온실가스 감축노력이 이루어 지고 있다. 그 중 CO2는 대표적인 온실가스로 세계 기후변화 협약 등에 의한 규제가 요구 되고 있으며 CO2를 분리 회수 및 저장(Carbon Capture and Storage : CCS)기술의 중요성이 커지고 있다. 연소 후 포집기술에는 흡착법, 흡수법, 분리막법 등이 있으며 그 중 분리막법은 CO2 포집 단가 및 플랜트 비용면에서 잠재성이 크다. 본 연구에서는 PES 중공사막을 이용하여 CO2 순도회수율 90%을 목표로 이산화탄소 분리기술을 연구 하였으며 전산모사를 통한 분리막 공정을 설계하였다.