• Journal of Korea Foundry Society
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• v.43 no.6
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• pp.279-285
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• 2023

In order to predict the mechanical properties of ductile cast iron heat treated in an intercritical temperature range, samples machined from cast iron with a tensile strength of 450 MPa were heat-treated at various intercritical temperatures and air-cooled, after which a microstructural analysis and Brinell hardness test were conducted. As the heat treatment temperature was increased in the intercritical temperature range, the ferrite fraction in the ductile cast iron decreased and the pearlite fraction increased, whereas the nodularity and nodule count did not change considerably from the corresponding values in the as-cast condition. The Brinell hardness values of the heat-treated ductile cast iron increased gradually as the heat treatment temperature was increased. Based on the measured alloy composition, the fraction of each stable phase and the hardness model from the literature, the hardness of the ductile cast iron heat treated in the intercritical temperature range was calculated, showing values very similar to the measured hardness data. In order to check whether it is possible to predict the hardness of heat-treated ductile cast iron by using the phase fraction obtained from thermodynamic calculations, the volumes of graphite, ferrite, and austenite in the alloy were calculated for each temperature condition. Those volume fractions were then converted into areas of each phase for hardness prediction of the heat-treated ductile cast iron. The hardness values of the cast iron samples based on thermodynamic calculations and on the hardness prediction model were similar within an error range up to 27 compared to the measured hardness data.

• Tuberculosis and Respiratory Diseases
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• v.46 no.6
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• pp.817-825
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• 1999

Background : Forceps biopsy, bronchial brushing, and bronchial washing are used in conjunction with bronchoscopy to provide specimens for histologic and cytologic analysis in patients with suspected lung cancer. This study was performed to evaluate how many times brushing should be done and how much fluid should be used during bronchial washing for increasing diagnostic yield, and to evaluate which combination of these procedures gives the highest diagnostic yield. Methods : Forty patients, with suspected lung cancer, who had bronchoscopically visible lesions were enrolled in this prospective study. During one bronchoscopic examination four forceps biopsies, four bronchial brushings, and bronchial washing were done in all patients. The patients were divided into four groups by the amount of normal saline used for bronchial washing; group I, 10 ml ; group II, 20ml ; group III 30ml, and group IV, 40ml. We analyzed the results in 36 patients confirmed as lung cancer. Results : The diagnostic sensitivity of bronchial washing before and after forceps biopsy and bronchial brushing were 36% and 28%, respectively. The cumulative diagnostic sensitivity of bronchial washing was 47% and significantly higher than that of bronchial washing before or after forceps biopsy and bronchial brushing (p<0.05). The diagnostic sensitivity of bronchial washing with saline of 30ml was significantly higher than that of bronchial washing with saline of 10ml or 20ml (p<0.05). The diagnostic sensitivity of the first brushing was 75%, the second brushing 78%, the third brushing 83%, and the fourth brushing 67%. With repeated brushing up to three times, the diagnostic sensitivity increased to 92% (p<0.05). However, inclusion of the fourth brushing did not give a further increase of the diagnostic sensitivity. The diagnostic sensitivity of forceps biopsy was 86%. The diagnostic sensitivities of forceps biopsy by the type of bronchial lesion were as follows: tumor, 88%; infiltration, 67%; infiltration with nodularity, 80%; and collapse, 100%. The combination of forceps biopsy and bronchial washing gave a diagnostic sensitivity of 89%. The diagnostic sensitivity of combining forceps biopsy with bronchial brushing was 97%. Addition of bronchial washing did not increase the diagnostic yield over forceps biopsy and bronchial brushing. Conclusion : In patients with central lung cancer, forceps biopsies and repeated brushings up to three times should be done for maximal diagnostic yield.