• Title/Summary/Keyword: Process

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Substitutability of coagulation process by pre-treatment of coagulation·flotation using natural algae coagulant (천연조류제거제를 활용한 응집·부상 전처리공정의 기존 응집공정 대체 가능성)

  • Jang, Yeo-Ju;Jung, Jin-Hong;Lim, Hyun-Man;Chang, Hyang-Youn;Kim, Weon-Jae
    • Journal of Korean Society of Water and Wastewater
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    • v.31 no.1
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    • pp.39-50
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    • 2017
  • In the coagulation/sedimentation (C/S) process of the water treatment process, the inflow of massive algal bloom causes many problems including fouling of filter media. This study was conducted to find out the way to remove the algae's harmful effects by addition of pre-treatment prior to C/S process. Many Jar-tests were conducted such as (1) ACF (Algae Coagulation Flotation) process using natural algae coagulant (Water $Health^{(R)}$), (2) ACF + C/S process and (3) C/S process with a variety of conditions using cultured algae. The average values of turbidity were (1) 0.42 NTU for ACF process, (2) 0.13 NTU for ACF + C/S process and (3) 0.25 NTU for C/S process. It was shown that the treatment efficiency of ACF process could get low turbidity results, and ACF + C/S process could achieve more efficient results than those of C/S process. Any negative effects of ACF process to the efficiency of C/S process were not observed in ACF + C/S process. In order to reduce the unfavorable effects of algae, it was found out that the introduction of ACF process in the forms of (1) ACF or (2) ACF + C/S could be one of the effective and alternative solutions.

Evaluation of Applicability and Economical Efficiency of Peroxone Process for Removal of Micropollutants in Drinking Water Treatment (정수처리에서 미량유해물질 제거를 위한 Peroxone 공정의 적용성 및 경제성 평가)

  • Son, Hee-Jong;Kim, Sang-Goo;Yeom, Hoon-Sik;Choi, Jin-Taek
    • Journal of Environmental Science International
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    • v.22 no.7
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    • pp.905-913
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    • 2013
  • We compared the applicability and economical efficiency of peroxone process with those of ozone process in the existing water treatment plant on downstream of Nakdong River. After comparing the peroxone process for removing geosmin with the ozone process in lab scale test, peroxone process showed much higher removal efficiency than the ozone process at the same ozone dosage. Proper range of $H_2O_2/O_3$ ratio were 0.5~1.0 and the half-life of geosmin was about 5.5~6.8 min when the $H_2O_2/O_3$ ratio was set to 0.5 during 1~2 mg/L of ozone dosage. Peroxone process could reduce the ozone dosage about 50 to maximum 30% for the same geosmin removal efficiency compared to the ozone process in the pilot scale test. In case of 1,4-dioxane treatment, peroxone process could have 3~4 times higher efficiency than ozone process at the same ozone dosage. The results of estimating the economical efficiency of ozone and peroxone process for treating geosmin and 1,4-dioxane by using pilot scale test, in case of the removal target was set to 85% for these two materials, the cost of peroxane process could be reduced about 1.5 times compared to ozone process, and in the same production cost peroxone process could have 2~3 times higher removal efficiency than ozone process. The removal efficiency by peroxone process showed a large difference depending on the physicochemical characteristics of target materials and raw water, therefore detailed examination should be carried out before appling peroxone process.

Tabu Search-Genetic Process Mining Algorithm for Discovering Stochastic Process Tree (확률적 프로세스 트리 생성을 위한 타부 검색 -유전자 프로세스 마이닝 알고리즘)

  • Joo, Woo-Min;Choi, Jin Young
    • Journal of the Society of Korea Industrial and Systems Engineering
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    • v.42 no.4
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    • pp.183-193
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    • 2019
  • Process mining is an analytical technique aimed at obtaining useful information about a process by extracting a process model from events log. However, most existing process models are deterministic because they do not include stochastic elements such as the occurrence probabilities or execution times of activities. Therefore, available information is limited, resulting in the limitations on analyzing and understanding the process. Furthermore, it is also important to develop an efficient methodology to discover the process model. Although genetic process mining algorithm is one of the methods that can handle data with noises, it has a limitation of large computation time when it is applied to data with large capacity. To resolve these issues, in this paper, we define a stochastic process tree and propose a tabu search-genetic process mining (TS-GPM) algorithm for a stochastic process tree. Specifically, we define a two-dimensional array as a chromosome to represent a stochastic process tree, fitness function, a procedure for generating stochastic process tree and a model trace as a string of activities generated from the process tree. Furthermore, by storing and comparing model traces with low fitness values in the tabu list, we can prevent duplicated searches for process trees with low fitness value being performed. In order to verify the performance of the proposed algorithm, we performed a numerical experiment by using two kinds of event log data used in the previous research. The results showed that the suggested TS-GPM algorithm outperformed the GPM algorithm in terms of fitness and computation time.

Problems of Special Causes in Feedback Adjustment

  • Lee, Jae-June;Cho, Sin-Sup
    • Journal of Korean Society for Quality Management
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    • v.32 no.2
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    • pp.201-211
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    • 2004
  • Process adjustment is a complimentary tool to process monitoring in process control. Process adjustment directs on maintaining a process output close to a target value by manipulating another controllable variable, by which significant process improvement can be achieved. Therefore, this approach can be applied to the 'Improve' stage of Six Sigma strategy. Though the optimal control rule minimizes process variability in general, it may not properly function when special causes occur in underlying process, resulting in off-target bias and increased variability in the adjusted output process, possibly for long periods. In this paper, we consider a responsive feedback control system and the minimum mean square error control rule. The bias in the adjusted output process is investigated in a general framework, especially focussing on stationary underlying process and the special cause of level shift type. Illustrative examples are employed to illustrate the issues discussed.

Economic Selection of Optimum Process Mean for a Mixture Production Process (혼합물 생산공정의 최적 공정평균의 경제적 선정)

  • Lee, Min-Koo
    • Journal of Korean Society for Quality Management
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    • v.33 no.4
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    • pp.111-116
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    • 2005
  • This paper considers the problem of optimally choosing the sub-process means of a mixture production process where two important ingredients are mixed. The quantity of each ingredient is controlled through each corresponding sub-process. The values of the sub-process mean directly affect the defective rate, production, scrap and reprocessing costs for the mixture production process. After inspecting every incoming item, each conforming item is sold in a regular market for a fixed price and any nonconforming item is scraped. A model is constructed on the basis of the selling price, production, inspection, and scrap and reprocessing costs. The goal is to determine the optimum sub-process mean values based on maximizing expected profit function relating selling price and cost components. A method of finding the optimum sub-process means is presented when the quantities of the two ingredients are assumed to be normally distributed with known variances. A numerical example is given and numerical studies are performed.

A Study on the Process Sequence Design of a Short-Neck Flange (숏넥 플랜지의 공정설계에 관한 연구)

  • 장용석;최진화;고병두;이호용;황병복
    • Journal of the Korean Society for Precision Engineering
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    • v.17 no.6
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    • pp.127-134
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    • 2000
  • The current three-stage cold farming process to produce a flange is investigated for the purpose of improvement of manufacturing process. The main goal of this study is to obtain an appropriate process sequence, which can produce the required part with less manufacturing cost. The current process sequence is simulated using finite element method and design criteria are examined. Based on the results of simulation of the current three-stage process. a design strategy for improving the process sequence is analyzed using the thick-walled pipes. Because it has a reduced process-sequence without buckling of the workpiece or overloading of tools, the new process has distinct advantages over the conventional process. Numerical results show that the newly proposed process with selected presses is the most economical way to produce the required part.

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Effect of Viscosity Variation on Flow Characteristic in Thixoforming Process of Semi-Solid Aluminium Alloys (반용융 알루미늄 합금의 Thixoforming 공정에서 점도의 변화가 유도특성에 미치는 영향)

  • 강충길;이유철
    • Transactions of Materials Processing
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    • v.8 no.2
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    • pp.188-199
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    • 1999
  • Semi-Solid Forming Process(Thixoforming, Rheocasting) is a novel forming process which has some advantages compared with conventional die casting, squeeze casting and hot/cold forging. In this study. Thixoforming process was selected as analysis processing in terms of billet handling and easiness of automation process. The Thixoforming process consists of reheating process of billet, billet handling, filling inot the die cavity and solidification of SSM part. In filling process, two rheology models which were Newtonian and Non-Nettonian model (Ostwald-deWaele)were verified with experimental results. The Ostwald-deWaele model shows the good agreement to the real flow and filling phenomena in die cavity. To give a boost the economical efficiency of Thixoforming process and to ensure the good forming result, reheating device coupled die set was proposed and the initial billet temperature for system that was found from experimental resluts. This study presents an overview of application of numerical analysis for simulation of semi-solid metal forming process to reduce the lead time for development of manufacturing part in industrial field.

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Optimization of Glass Micro Molding Process for Glass Microlens Arrays (유리 마이크로 렌즈 어레이 성형을 위한 유리 마이크로 성형 공정 최적화)

  • Bae, Hyung-Dae;Choi, Min-Seok;Kang, Shin-Ill
    • Transactions of the Society of Information Storage Systems
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    • v.2 no.4
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    • pp.236-239
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    • 2006
  • Glass micro molding process is the most suitable process for fabricating high precision glass microlens amy at low cost. A new glass micro molding process was proposed. Tungsten carbide mold was fabricated by imprinting and sintering process to overcome the difficulties of the conventional process. In the glass micro molding process, process conditions such as processing temperature and compression force were changed. Geometrical properties of the replicated glass microlens array were measured and compared at variety process conditions. The condition of glass micro molding process was optimized. The experimental result showed that developed process was effective to produce a glass microlens array.

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A Study on Implementation of Automobile Control Software Testing Process Based on TMMi (TMMi 기반 자동차 제어 SW 테스팅 프로세스 구축에 관한 연구)

  • Jang, Jin-Wook
    • Journal of Information Technology Services
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    • v.8 no.3
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    • pp.159-169
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    • 2009
  • The issue of method of software testing process implementation has recently been in the spotlight in korea and some vendor make every effort to improve the software testing process through the evaluation of TMMi. The level of software process is at initial level, nevertheless, so the high quality of software is not guaranteed. This paper apply to the TMMi Level2 Assessment criteria of Automobile control software testing process. The test policy and strategy, test planning, test monitoring and control, test design and execution, test environment goal. The result need to emerge development process connection on the test policy and strategy process, test planning process etc. Also, the study analyzed the infra structure to reach the repeated level via key process area. As the result the process implementation in organization suggests the policy development and the implementation activity. Finally, the practical can refer to this paper in order to implementation the software testing process.

Problems of Special Causes in Feedback Adjustment

  • Lee Jae June;Cho Sinsup;Lee Jong Seon;Ahn Mihye
    • Proceedings of the Korean Society for Quality Management Conference
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    • 2004.04a
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    • pp.425-429
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    • 2004
  • Process adjustment Is a complimentary tool to process monitoring in process control. Process adjustment directs on maintaining a process output close to a target value by manipulating another controllable variable, by which significant process improvement can be achieved. Therefore, this approach can be applied to the 'Improve' stage of Six Sigma strategy. Though the optimal control rule minimizes process variability in general, it may not properly function when special causes occur in underlying process, resulting in off-target bias and increased variability in the adjusted output process, possibly for long periods. In this paper, we consider a responsive feedback control system and the minimum mean square error control rule. The bias in the adjusted output process is investigated in a general framework, especially focussing on stationary underlying process and the special cause of level shift type. Illustrative examples are employed to illustrate the issues discussed.

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