• Transactions of the Korean Society for Noise and Vibration Engineering
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• 제24권10호
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• pp.763-769
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• 2014

This study is on the experiment and prediction of the pipe noise due to the internal fluid. The vibration of pipe external surface and noise in air were measured according to the internal fluid velocity and pipe type. In the experiment, the vibration and noise level of the straight pipe and rounded pipes show that the vibration and noise level are almost same. The 900 mitred pipe shows the high vibration and noise level. In the prediction of noise due to the internal flow, the method using the pipe surface vibration and radiation efficiency shows good agreement with experimental result.

• Ocean Systems Engineering
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• 제5권4호
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• pp.245-259
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• 2015

The numerical simulation of wave slamming on a 3D platform deck was investigated using a coupled Level-Set and Volume-of-Fluid (CLSVOF) method for overset grid system incorporated into the Finite-Analytic Navier-Stokes (FANS) method. The predicted slamming impact forces were compared with the corresponding experimental data. The comparisons showed that the CLSVOF method is capable of accurately predicting the slamming impact and capturing the violent free surface flow including wave slamming, wave inundation and wave recession. Moreover, the capability of the present CLSVOF method for overset grid system is a prominent feature to handle the prediction of wave slamming on offshore structure.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 한국추진공학회 2006년도 제27회 추계학술대회논문집
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• pp.299-302
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• 2006

We present an innovative means of numerically treating interfaces associated with chemically active energetic materials. Recent advances in wave tracking technique based on the Ghost Fluid Concept is extended to handle multi-material multi-phase interfaces associated with chemical environment associated with explosion. We show several work-in-progress applications of our code, including the impact problems involving both energetic and inert elements. Accurate modeling of the equation of state and the constitutive relations are also discussed

• Journal of the Korean Institute of Gas
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• 제27권2호
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• pp.32-38
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• 2023

In a chemical plant, while supplying corrosive fluid to a storage tank with a pump, an accident occurred where the corrosive fluid leaked through the upper exhaust vent because the level indicator was not accurately determined. There are various causes of leakage accidents, but we focused on the sticking of the level indicator of the level gauge, which is the direct cause. As a result of the analysis, the level indicator used in the workplace where the accident occurred was randomly replaced, and in the summer when the accident occurred, the tubular type level gauge was found to be more likely to stick than other types because thermal expansion easily occurs. In addition, there were difficulties in reviewing the proper installation because the installation standards for measuring instruments installed in storage tanks were not clear in Korea. Therefore, in this study, based on accident cases and overseas standards, we are going to find out about precautions when installing storage tank instrumentation.

• Journal of Periodontal and Implant Science
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• 제44권3호
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• pp.118-125
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• 2014

Purpose: The present split mouth study evaluates the effect of nonsurgical periodontal treatment on the gingival crevicular fluid (GCF) leptin level in chronic periodontitis. Methods: Ninety sites from 30 nonobese chronic periodontitis patients were selected and divided as follows: group I, 30 healthy sites receiving no treatment; group II, 30 periodontitis sites receiving scaling and root planing (SRP); and group III, 30 periodontitis sites receiving SRP with tetracycline local drug delivery. At baseline, after GCF sampling and clinical parameter recording, the assigned treatment was performed for the study groups. During recall visits, GCF sampling followed by clinical parameter recording was done for groups II and III. Results: Reductions in the probing depth and the clinical attachment level (CAL) were highly significant at different time intervals (except between day 0 and 45) in both groups II and III. Upon comparison, group III showed significant gain in CAL between day 0 and 15 and between day 0 and 45. After treatment, the reduction in the GCF leptin level was more significant in group III than in group II at day 15 but re-elevated almost to the pretreatment levels at day 45. Conclusions: Nonsurgical periodontal therapies were not effective in maintaining stable reduction in the GCF leptin level during the study period.

• 한국가시화정보학회:학술대회논문집
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• 한국가시화정보학회 2003년도 추계학술대회 논문집
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• pp.51-54
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• 2003

Fluid is an effective element in computer animation. Recently, the techniques from CFD have been actively applied to CG production. In this paper, we describe our fluid animation system which implements a variety of established simulation and rendering methods. We also explain our new techniques such as chemical reaction and hardware-assisted fluid animation that are being developed to enhance the features of our software system.

• Tuberculosis and Respiratory Diseases
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• 제47권5호
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• pp.595-600
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• 1999

Background: The estimation of ADA activity in pleural fluid has been proved useful tool in the diagnosis of tuberculous pleural effusions. However, there is controversy about its usefulness when estimated in bronchial washing fluid in the patients with pulmonary tuberculosis. This study aims at evaluating the usefulness of measuring ADA activity in bronchial washing fluid of tuberculous patients as biochemical marker in the early diagnosis of the disease. Methods: We examined the difference of ADA activity in bronchial washing fluid among the group I(tuberculosis group), group II(lung cancer group) and group III(control group). Results: There was significantly higher bronchial washing fluid ADA level in tuberculosis group compared to the lung cancer and control groups(p<0.01). Conclusion: These results suggest that bronchial washing fluid ADA activities seem to be a useful tool in the diagnosis of pulmonary tuberculosis.

• Tuberculosis and Respiratory Diseases
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• 제59권4호
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• pp.361-367
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• 2005

Background : Differential diagnosis of lymphocytic pleural effusion is difficult even with many laboratory findings. Nitric oxide(NO) level is higher in the sputum or exhaled breath of patients with active pulmonary tuberculosis than in those without tuberculosis. In addition, there are some reports about the increased level of NO metabolites in body fluids of cancer patients. However, there is no data on the NO levels in the pleural fluid of patients with tuberculous pleurisy. Method : The serum and pleural fluid NO in the patients with acute lymphocytic pleural effusion were analyzed. Results : Of total 27 patients, there were 14 males and average age of patients was 48 years. The final diagnosis was tuberculous pleurisy in 17 cases and malignant pleural effusion in 10. The pleural fluid NO level was $540.1{\pm}116.4{\mu}mol$ in the tuberculous pleurisy patients and $383.7{\pm}71.0{\mu}mol$ in the malignant pleural effusion patients. The serum NO level was $624.7{\pm}142.0{\mu}mol$ in tuberculous pleurisy patients and $394.4{\pm}90.4{\mu}mol$ in malignant pleural effusion patients. There was no significant difference in the serum and pleural fluid NO level between the two groups. The NO level in the pleural fluid showed a significant correlations with the pleural fluid neutrophil count, the pleural fluid/serum protein ratio, and pleural fluid/serum albumin ratio (p<0.05 in each). The protein concentration, leukocyte and lymphocyte count in the pleural fluid were significantly higher in the tuberculous pleurisy patients than the malignant pleural effusion patients (p<0.05 in each). Conclusion : NO is not a suitable marker for a differential diagnosis of lymphocytic pleural effusion. However, the NO level in the pleural fluid might be associated with the neutrophil recruitment and protein leakage in the pleural space.

• The KSFM Journal of Fluid Machinery
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• 제1권1호
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• pp.41-48
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• 1998

This study was carried out to investigate the effect of design parameters on the volume flow-rate and the noise level and to finally find the optimal design variables. Eighteen cross-flow fans were designed by the method of orthogonal array, and the flow-rate and the noise level were measured. These data were analyzed by the neural network system. The effects of eight design variables(scroll exit angle, scroll arc length et al.) on the fan performance and the noise level were valuated and discussed. This experiment shows that the design solutions suggested by neural network system may increase its volume flow-rate and reduce noise simultaneously.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• 제26권8호
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• pp.351-356
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• 2014

Typical trouble patterns in solar thermal systems include working fluid leakage and freezing other than breakdown of pump. A fluid sensor for measuring electric resistance of fluid was developed and installed at the top of the collector piping in order to check the fault of solar system. Working fluid level in the pipe was determined by measuring electric resistance from a fluid sensor. On the base of this, it was confirmed that the fluid sensor diagnoses leakage of fluid. Electric resistance of propylene glycol aqueous solution was measured in the range of $0{\sim}70^{\circ}C$ and 0~40% of concentration. The response surface analysis was performed by using a central composite design, and the regression equation was derived from the relationship between electric resistance, temperature, and concentration. Through the experiment in a real solar system, we can estimate a concentration of working fluid when a pump is not operating and predict a possibility of freezing. Finally, an effective algorithm for trouble shooting was proposed to operate and maintain the solar system.