• Transactions on Electrical and Electronic Materials
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• 제12권2호
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• pp.56-59
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• 2011

The characterization of the chemical mechanical polishing (CMP) process for undensified phophosilicate glass (PSG) film is reported using design of experiments (DOE). DOE has been used by experimenters to understand the relationship between the input variables and responses of interest in a simple and efficient way, and it typically is beneficial for determining the appropriatesize of experiments with multiple process variables and making statistical inferences for the responses of interest. The equipment controllable parameters used to operate the machine consist of the down force of the wafer carrier, pressure on the back side wafer, table and spindle speeds (SS), slurry flow (SF) rate, pad condition, etc. None of these are independent ofeach other and, thus, the interaction between the parameters also needs to be understoodfor improved process characterization in CMP. In this study, we selected the five controllable equipment parameters the most recommendedby process engineers, viz. the down force (DF), back pressure (BP), table speed (TS), SS, and SF, for the characterization of the CMP process with respect to the material removal rate and film uniformity in percentage terms. The polished material is undensified PSG which is widely used for the plananization of multi-layered metal interconnects. By statistical modeling and the analysis of the metrology data acquired from a series of $2^{5-1}$ fractional factorial designs with two center points, we showed that the DF, BP and TS have the greatest effect on both the removal rate and film uniformity, as expected. It is revealed that the film uniformity of the polished PSG film contains two and three-way interactions. Therefore, one can easily infer that process control based on a better understanding of the process is the key to success in current semiconductor manufacturing, in which the size of the wafer is approaching 300 mm and is scheduled to continuously increase up to 450 mm in or slightly after 2012.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2007년도 춘계학술논문 발표대회
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• pp.113-118
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• 2007

Now a performance process of Demolition works is 'Before-Removal & After-Classification' method in Korea. This method is short of demolition time, but construction wastes contained substances lower recycling rate of construction, raise expenses of reclamation & treatment. Then the government has decided upon a positive 'Before-Classification & After-Removal' method, and substantially raise a recycling rate of construction wastes. Therefore, this study makes an investigation into state of internal and external demolition field through evaluating technological level, we make a proposal of dismantling method from there. Also, we put dismantling to the test in an apartment by proposed work process. As the result, it made a term of works increased for removing interior material. To solve this problem, we need to develop tools and methods of construction that can remove efficiently. From now on, we continuously need to study a breakdown system of dismantling, analysis of dismantling process and general system by inspecting entire demolition process. And we have to study details for making a specific thesis of method of removing interior material which was based on developing a suitable partial demolition machine and dismantling works.

• 대한환경공학회지
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• 제31권12호
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• pp.1081-1088
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• 2009

Rhodamine B (RhB)의 제거를 위해 철 전극을 이용한 전기응집 (EC) 공정의 성능에 대해 연구하였다. RhB 제거 효율에 대한 전극 물질 (알루미늄, 철), 전류밀도, NaCl 첨가량, 초기 pH 및 초기 염료 농도와 같은 운전인자의 영향을 연구하였다. 이들 운전 인자에 대한 최적 운전 범위는 실험을 통하여 결정되었다. 희생 전극 물질로서 철 전극의 성능이 알루미늄 전극보다 우수하였다. 최적 전기분해 시간, 전류밀도, NaCl 첨가량 및 pH는 각각 10 분, 1630 A/$m^2$, 4 g/L 및 중성의 pH 이었다. 최적의 공정 조건하에서 RhB 농도가 230 mg/L인 조건에서 RhB는 효과적으로 제거되었고 (> 93.4%), RhB의 COD도 역시 감소하였다(> 88.9%). RhB의 색도와 COD 제거에 대한 상기 조건에서의 전기 에너지 소비량은 각각 10.3 and 10.8 kWh/kg RhB으로 나타났다. 전기응집 공정은 RhB와 같은 염색폐수 처리에 효과적인 것으로 나타났다.

• 한국공작기계학회논문집
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• 제13권2호
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• pp.104-111
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• 2004

Ultrasonic machining is a non-thermal, non-chemical, md non-electorial material removal process, and thus results in minimum modifications in mechanical properties of the brittle material during the process. Also, ultrasonic machining is a non-contact process that utilize ultrasonic vibration to impact a brittle material. In this research characteristics of micro-hole machining for brittle materials by ultrasonic machining(USM) process have been investigated. And the effect of ultrasonic vibration on the machining conditions is analyzed when machining fir non-conductive brittle materials using tungsten carbide tools with a view to improve form and machining accuracy.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2005년도 춘계학술대회 논문집
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• pp.168-173
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• 2005

Composite material is combined with two or more chemical ingredient and different components. FRP has been widely used for the structure of aircraft, ships, automobiles, sporting goods and other machines because of their high specific strength, high specific stiffness and excellent fatigue strength. Recently, the development of machine tool and cutting tool greatly relies on high speed process to satisfy high precision, high efficient machining, shortened process time to maximize material removal rate (MRR) through high cutting speed and feed speed. The research molded CFRP, GFRP as stacking sequence methods of two direction (orientation angle $0^{\circ}\;and\;0^{\circ}/9^{\circ}$) hand lay-up, drilled molded plates using cemented carbide drill and examined chip shapes, surface roughness properties.

• 한국수자원학회논문집
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• 제30권3호
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• pp.235-245
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• 1997

대청호 원수를 취수하여 정수하는 대청수도에서 이취미를 제거하고 THM(Trihalomethanes) 발생량을 줄이기 위하여 기존 표준정수공정에 오존과 활성탄여과공정을 추가한 pilot plant 실험을 수행하였다. pilot 실험결과 표준정수공정에서 DOC(dissolved organic carbon)는 약 25% 제거되었으나, 오존공정에서는 거의 제거되지 않았고, 30일이 지난 후 GAC(granular activated carbon)에서는 약 75%까지 제거되는 것으로 나타났다. 표준정수공정에서 이취미는 약 30%, 오존산화공정에서 약 60%정도 제거되었고, 활성탄여과에서 대부분 제거되었으나, Column 1과 2에서는 DOC와 같이 이취미물질도 파과(breakthrough) 되는 것으로 나타났다. 전염소처리 대신에 중1, 2염소처리를 도입할 경우 전염소처리와 비교하여 약 25%정도의 THM발생량이 감소하였으며, 후염소처리만할 경우 약 30%까지 감소하는 것으로 나타났다.

• International Journal of Precision Engineering and Manufacturing
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• 제8권4호
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• pp.10-15
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• 2007

Taguchi methods have been used for a long time to improve the product quality and process performance of a manufacturing system, Few researchers have applied this methodology in laser beam cutting (LBC) of sheet metals and found the considerable improvement in cut qualities. In all experimental investigations of LBC so far, the objective was to optimize the single quality characteristic at a time. In this paper the simultaneous optimization of multiple quality characteristics such as Kerf width and material removal rate (MRR) during pulsed Nd:YAG LBC of thin sheet of magnetic material (high Silicon-steel) has been presented using Taguchi's quality loss function. The results show the considerable improvement in multiple S/N ratio as compared to initial cutting condition. Also, the comparison of results from single and multi-objective optimization have been presented and it was found that the loss in quality is always possible shifting from single quality to multiple quality optimization.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.1068-1071
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• 2001

Recently, the minimum line width shows a tendancy to decrease and the multi-level to increase in semiconductor. Therefore, a planarization technique is needed, which chemical polishing(CMP) is considered as one of the most important process. CMP accomplishes a high polishing performance and a global planarization of high quality. But there are several defects in CMP such as microscratches, abrasive contaminations, and non-uniformity of polished wafer edges. Spin Etching can improve the defects of CMP. It uses abrasive-free chemical solution instead of slurry. Wafer rotates and chemical solution is simultaneously dispensed on a whole surface of the wafer. Thereby chemical reaction is occurred on the surface of wafer, material is removed. On this study, TEOS film is removed by CMP and Spin Etching, the results are estimated at a viewpoint of material removal rate(MRR) and within wafer non-uniformity(WIWNU).

• 한국물환경학회지
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• 제20권6호
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• pp.571-576
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• 2004

Since anaerobic/anoxic/oxic process, which is a typical mainstream biological nitrogen and phosphorus removal process, utilizes influent organic matter as an external carbon source for phosphorus release in anaerobic or anoxic stage, influent COD/T-P ratio gives a strong influence on performance of phosphorus removal process. In this study, a bench scale experiment was carried out for SBR process to investigate nitrogen and phosphorus removal at various influent COD/T-P ratio and nitrate loadings of 23~73 and 1.6~14.3g $NO_3{^-}-N/kg$ MLSS, respectively. The phosphorus release and excess uptake in anoxic condition were very active at influent COD/T-P ratios of 44 and 73. However, its release and uptake was not obviously observed at COD/T-P ratio of 23. Consequently, phosphorus removal efficiency was decreased. In addition, the phosphorus release and uptake rate in anoxic condition increased as the nitrate loading decreased. Specific denitrification rate had significantly high correlation with organic materials and nitrate loadings of the anoxic phase too. The rate of phosphorus release and uptake in the anoxic condition were $0.08{\sim}0.94kg\;S-P/kg\;MLSS{\cdot}d$ and $0.012{\sim}0.1kg\;S-P/kg\;MLSS{\cdot}d$, respectively.

• Tribology and Lubricants
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• 제39권5호
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• pp.216-219
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• 2023

This study employs molecular dynamics simulations to investigate the material behavior of workpieces in waterjet machining processes. To gain fundamental insights into waterjet machining, simulations were conducted using pure water, excluding abrasive particles. The simulation model comprised thousands of water molecules interacting with a single crystal metal workpiece. Water molecule clusters were imparted with various velocities to initiate collisions with the metal workpiece. The material behavior of the metal surface was analyzed with respect to the applied velocity conditions, considering the intricate interplay between water molecules and the workpiece at the atomic scale. The results demonstrated that the machining of the metal workpiece occurred only when water molecules were endowed with velocities above a certain threshold. In cases where energy was insufficient, the metal workpiece exhibited a slight increase in surface roughness due to mild plastic deformation, without undergoing substantial material removal. When machining occurred, the ejection of material revealed a 3-fold symmetric pattern, confirming that material removal in waterjet machining of the metal workpiece is primarily driven by plastic deformation-induced material ejection. This research provides crucial insights into the mechanisms underlying waterjet machining and enhances our understanding of material behavior during the process. The findings can be valuable in optimizing waterjet machining techniques.