• 한국전기전자재료학회논문지
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• 제18권1호
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• pp.24-29
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• 2005

Chemical mechanical polishing (CMP) has been widely accepted for the global planarization of multi-layer structures in semiconductor manufacturing. Copper has been the candidate metallization material for ultra-large scale integrated circuits (ULSIs), owing to its excellent electro-migration resistance and low electrical resistance. However, it still has various problems in copper CMP process. Thus, it is important to understand the effect of the process variables such as turntable speed, head speed, down force and back pressure are very important parameters that must be carefully formulated in order to achieve desired the removal rates and non-uniformity. Using a design of experiment (DOE) approach, this study was performed investigating the main effect of the variables and the interaction between the various parameters during CMP. A better understanding of the interaction behavior between the various parameters and the effect on removal rate, non-uniformity and ETC (edge to center) is achieved by using the statistical analysis techniques. In the experimental tests, the optimum parameters which were derived from the statistical analysis could be found for higher removal rate and lower non-uniformity through the above DOE results.

• Nuclear Engineering and Technology
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• 제52권10호
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• pp.2230-2237
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• 2020

Self-priming venturi scrubber is one of the most effective devices used to collect aerosols and soluble gas pollutants from gaseous stream during severe accident in a nuclear power plant. The present study focuses on investigation of dust particle removal efficiency of the venturi scrubber both experimentally and theoretically. Venturi scrubber captures the dust particles in tiny water droplets flowing into it. Inertial impaction is the main mechanism of particles collection in venturi scrubber. The water injected into venturi throat is in the form of jets through multiple holes present at venturi throat. In this study, aerosols removal efficiency of self-priming venturi scrubber was experimentally measured for different operating conditions. Alumina (Al₂O₃) particles with 0.4-㎛ diameter and 3950 kg/㎥ density were treated as aerosols. Removal efficiency was calculated for different gas flow rates i.e. 3-6 ㎥/h and liquid flow rates i.e. 0.009-0.025 ㎥/h. Experimental results depict that aerosols removal efficiency increases with the increase in throat velocity and liquid head. While at lower air flow rate of 3 ㎥/h, removal efficiency decreases with the increase in liquid head. A theoretical model of venturi scrubber was also employed and experimental results were compared with mathematical model. Experimental results are found to be in good agreement with theoretical results.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1998년도 하계종합학술대회논문집
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• pp.481-484
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• 1998

In this study, oxide(TEOS) CMPs were carried out for various head pressures. Table and head speeds are fixed at 25 RPM. Head pressures are 5, 7.5, 10, 12.5 PSI, and under these conditions, 1,587, 1,631, 2,556, 2,871.agns./min of oxide (TEOS) removal rates and 14.7, 18.5, 9.52, 7.9% of uniformities are obtained, respectively. Also, these experiments for local and global planarizations were done using the patterned 4" wafers. These conditions are applicable to STI(shallow trench isolation) structures and planarizations for sub-half micron lithography.aphy.

• 대한두경부종양학회지
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• 제23권2호
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• pp.195-198
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• 2007

Schwannoma is a slow-growing benign tumor of neurogenic origin. The lesion is derived from the Schwann cells surrounding neural tissue. It can grow in almost all regions of the body. Schwannoma of the external auditory canal is a rare finding. Recently, we experienced schwannoma of the external auditory canal of a 29-year-old female who had surgical removal completely and verified histopathologically as schwannoma.

• 대한두경부종양학회지
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• 제10권2호
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• pp.212-217
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• 1994

The Horner's syndrome includes anisocoria as a result of miosis of the involved pupil with ptosis of the upper and lower lids, which results in slight narrowing of the palpebral fissure. Ipsilateral facial hyperemia and anhidrosis over the face and neck are less common features. The findings with Horner's syndrome are a result of the loss of sympathetic innervation to the ipsilateral eye and face. Recently we experienced 3 cases of Horner's syndrome that developed postoperatively and report briefly with literature.

• Tribology and Lubricants
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• 제16권6호
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• pp.415-424
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• 2000

The use of magnetoresistive (MR) head requires much tighter control of particle contamination in a drive since loose particles on the disk surface will generate thermal asperities (TA). In this study, a spinoff test was performed to investigate the adhesion and removal capability of a particle to disk surface. Numerical simulation was also performed to investigate dominant factor of particle detachment and to support experimental results. It was shown that particles are detached from the disk surface by the moment derived from the centrifugal force and the drag force and that the centrifugal force and capillary force are the dominant force, which determines spin-off of a particle on the disk surface. Removal of particles smaller than several micrometers, which are the main source of TA generation, is extremely difficult since the adhesion forces exceed the centrifugal force. Lubricant types and manufacturing process also influence the particle removal. Lower bonding ratio and lower viscosity of the lubricant will help to increase the removal rate of the particles from the disk surface.

• Archives of Plastic Surgery
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• 제48권1호
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• pp.49-54
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• 2021

Background Reconstruction after removal of a malignant tumor in the head and neck region is crucial for restoring tissue integrity, function, and aesthetics. We retrospectively analyzed patients who underwent intraoral reconstruction surgery using radial forearm free flaps (RFFF) and anterolateral thigh free flaps (ALT) at a single institution to provide more information supporting the choice of a reconstruction method after removal of head and neck cancer. Methods The charts of 708 patients who underwent head and neck reconstruction between 1998 and 2018 at the Department of Plastic and Reconstructive Surgery at our institution were retrospectively reviewed. Patients' age, sex, and history of radiation therapy, diabetes mellitus, and smoking were retrieved. The primary cancer site, types of defects, and complications were investigated. Results Overall, 473 and 95 patients underwent reconstruction surgery with RFFF and ALT, respectively. RFFF was more often used in patients with cancers of the pharynx, larynx, esophagus, or tonsil, while ALT was more frequently used in patients with cancers of the mouth floor with tonsil or tongue involvement. The proportion of patients undergoing ALT increased gradually. Flap failure and donor site morbidities did not show significant differences between the two groups. Conclusions RFFF and ALT flaps resulted in similar outcomes in terms of flap survival and donor site morbidity. ALT can be an option for head and neck reconstruction surgery in patients with large and complex defects or for young patients who want to hide their donor site scars.

• 한국정밀공학회지
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• 제22권4호
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• pp.44-51
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• 2005

In this paper, a new polishing head with the variable pressure structure was studied to improve the planarization uniformity of the conventional template-metal head. Metal surface waviness and slurry distribution on the pad have been known to affect the polishing uniformity even in the synchronized quill and platen velocities. A polishing head with silicon rubber sheet was used to get a curved pressure distribution. In the experiment, the vertical deflection behavior on the pad was characterized with back pressure in the air chamber. Quill force increased linearly with backpressure. However, backpressure under a quill force made the upward movements of the quill. In the wafer polishing experiments, polishing rate and polishing thickness distribution were severely changed with backpressure. The best uniformity was observed with the standard deviation off.5％ level of average polishing removal 215nm at backpressure 12.1kPa.

• 상하수도학회지
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• 제22권4호
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• pp.461-466
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• 2008

Because of their simplicity, efficiency, and economy, slow sand filters are appropriate means of water treatment for small water systems. In this study, the effect of filtration velocity and dirty skin (Schmutzdecke) was evaluated on the performance of turbidity removal. Also, removal characteristics of particulate were investigated in the case of the usage of non-woven fabric on the surface of sand and the application of PCF as pretreatment process. Comparative column tests were carried out for the various operation condition. From the result of column tests, filtration velocity had little effect on the turbidity removal rate. The formation of algal biofilm on the surface of media is helpful in turbidity removal, while non-woven fabric is not as effective as expected. The relative contribution of biomass and accumulated particulates to head loss development in slow sand filters requires further study.

• 대한두경부종양학회지
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• 제12권1호
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• pp.22-25
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• 1996

A very important and interesting problem occasionally seen in the neck of children and adults is a branchial cleft anomaly. It is a rare congenital neck disease and presents a painless palpable mass of neck in most cases. We have retrospectively reviewed the medical records of 28 patients operated upon for branchial cleft anomaly at Department of Surgery, Chonnam University Hospital between January, 1991 and December, 1995. Three of these lesions were considered to have originated from the first branchial cleft, and 25 from the second branchial cleft. Females are about twice more common than male patients. Pathological findings showed the cysts were lined squamous epithelium and subepithelial lymphoid follicles in most cases. Five out of 28 patients with branchial cleft anomalies had previous incision procedures. All patients after complete removal of branchial anomalies have no recurrences.