• Tuberculosis and Respiratory Diseases
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• 제45권5호
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• pp.1000-1011
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• 1998

연구배경: 기관지 천식 환자들과 만성폐쇄성폐질환의 진단이나 기도폐쇄 정도를 알기 위하여 통상적으로 노력성 호기곡선이나 최대호기류량곡선을 이용한 환기기능검사가 널리 이용되고 있다. 그러나 외래를 방문하는 환자들이나 자가 치료를 하는 환자들의 경과관찰에는 검사의 간편성으로 인해 peak flow meter를 이용한 peak expiratory flow(PEF)가 많이 이용된다. 이 경우 PEF의 변이성이 크기 때문에 절대값이나 증상이 없을 때의 최대값을 기준으로 비교하여 사용하기도 하는데 검사 판정의 객관성은 추정정상치가 가장 높을 것이다. 그러나 현재까지 국내에서는 최대호기류량곡선을 이용한 PEF(FEFmax)의 추정정상치의 보고는 다수 있으나 peak flow meter를 이용한 보고는 아직까지 없었다. 이에 실제 환자들이 스스로 쉽게 측정할 수 있는 PEF의 추정정상치를 산출하고 이 값이 $FEV_1$을 비롯한 다른 환기기능검사를 어느 정도 정확하게 예측할 수 있는 지를 조사 연구하였다. 방 법: 호흡기 증상이나 기왕 병력이 없는 건강한 남자 129명(나이 ; 19-74 세), 여자 125명(나이 ; 18-67세)을 대상으로 외래에서 mini-Wright peak flow meter(Clement Clarke International Ltd. England)를 이용하여 3 회 이상 PEF를 측정하였다. 아울러 Microspiro HI-501 portable spirometer(Chest Co., Japan)로 노력성호기곡선, 최대호기류량곡선을 측정 분석하여 $FEV_1$, FVC, $FEV_1/FVC$, $FEF_{25-75%}$, $FEF_{25%}$, $FEF_{50%}$, $FEF_{75%}$와 FEFmax를 구하여 각각의 추정정상치를 구하였고 PEF의 $FEV_1$ 및 FEFmax에 대한 설명력을 회귀분석을 통해 구하였다. 결 과: PEF(L/min)의 추정정상치는 남자가 -2.45$\times$Age(year) + 1.36 $\times$ Height(cm) + 427였고 ($R^2=0.28$), 여자에서는 -0.96 $\times$ Age(year) + 2.01 $\times$ Height(cm)+129였다($R^2=0.12$). 최대호기류량곡선에서 산출한 FEFmax는 PEF보다 납자에서는 $125{\pm}74.0$(L/min), 여자에서는 $118{\pm}52.2$(L/min) 적었다. PEF로 예측할 수 있는 $FEV_1$(ml)값은 남자에서 5.98 $\times$ PEF(L/min) + 303 이고 ($R^2=0.43$), 여자에서는 4.61 $\times$ PEF(L/min) +291 이었다($R^2=0.33$). 결 론: 건강한 성인 254명(남자 129명, 여자 125명)을 대상으로 peak flow meter로 측정한 PEF의 추정정상치를 연령과 신장을 변수로 하여 구하였다. 여기서 측정한 PEF로 $FEV_1$ 및 FEFmax를 어느 정도 예측할 수 있었다. 그리고 측정기계 및 방법에 따라서 PEF 값이 달라짐을 확인하였는데 이런 점을 유의한다면 PEF의 측정은 향후 환자 진료에 많은 도움이 될 것으로 생각한다.

• Tuberculosis and Respiratory Diseases
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• 제71권3호
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• pp.188-194
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• 2011

Background: When patients with chronic respiratory symptoms have a normal spirometry result, it is not always easy to consider bronchial asthma as the preferential diagnosis. Forced expiratory flow between 25% and 75% of vital capacity ($FEF_{25{\sim}75%}$) is known as a useful diagnostic value of small airway diseases. However, it is not commonly used, because of its high individual variability. We evaluated the pattern of bronchodilator responsiveness (BDR) and the correlation between $FEF_{25{\sim}75%}$ and BDR in patients with suspicious asthma and normal spirometry. Methods: Among patients with suspicious bronchial asthma, 440 adult patients with a normal spirometry result (forced expiratory volume in one second [$FEV_1$]/forced vital capacity [FVC] ${\geq}70%$ & $FEV_1%$ predicted ${\geq}80%$) were enrolled. We divided this group into a positive BDR group (n=43) and negative BDR group (n=397), based on the result of BDR. A comparison was carried out of spirometric parameters with % change of $FEV_1$ after bronchodilator (${\Delta}FEV_1%$). Results: Among the 440 patients with normal spirometry, $FEF_{25{\sim}75%}%$ predicted were negatively correlated with ${\Delta}FEV_1%$ (r=-0.22, p<0.01), and BDR was positive in 43 patients (9.78%). The means of $FEF_{25{\sim}75%}%$ predicted were $64.0{\pm}14.5%$ in the BDR (+) group and $72.9{\pm}20.8%$ in the BDR (-) group (p<0.01). The negative correlation between $FEF_{25{\sim}75%}%$ predicted and ${\Delta}FEV_1%$ was stronger in the BDR (+) group (r=-0.38, p=0.01) than in the BDR (-) group (r=-0.17, p<0.01). In the ROC curve analysis, $FEF_{25{\sim}75%}$ at 75% of predicted value had 88.3% sensitivity and 40.3% specificity for detecting a positive BDR. Conclusion: BDR (+) was not rare in patients with suspicious asthma and normal spirometry. In these patients, $FEF_{25{\sim}75%}%$ predicted was well correlated with BDR.

• Nuclear Engineering and Technology
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• 제56권4호
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• pp.1454-1459
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• 2024

Researchers have applied theoretical and CFD models for years to analyze the fluidelastic instability (FEI) of tube arrays in steam generators and other heat exchangers. The accuracy of each approach has typically been evaluated using the discrepancy between the experimental critical flow velocity and the predicted value. In the best cases, the predicted critical flow velocity was within an order of magnitude comparable to the measured one. This paper revisits the quasi-steady approach for damping controlled FEI in a normal triangular array with a pitch ratio of P/d = 1.375. The method addresses the fluidelastic frequency at the stability threshold as an input parameter for the approach. The excellent agreement between the estimated stability thresholds and the equivalent experimental results suggests that the fluidelastic frequency must be included in the quasi-steady analysis, which requires minimal computing time and experimental data. In addition, the model allows a simple time delay analysis regarding flow convective and viscous effects.

• Journal of Chest Surgery
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• 제28권5호
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• pp.464-470
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• 1995

From Jan 1988 to Dec 1993, 196 consecutive patients with various pulmonary diseases underwent pneumonectomy. Mean age was 54.0 years[range:7-74 . The underlying diseases were lung cancer[154 cases , destroyed lung[29 cases with pulmonary tuberculosis or empyema thoracis and others[13 cases . The overall mortality and complication rate were 5.6% and 14.8%. In the groups of more than and less than 60 years of age, there was significant differences in mortality rate[P=0.004 . In the group of pneumonectomy and pleuropneumonectomy, there was no significant differences in mortality[P=0.164 and complication rate[P=0.052 . In the group of normal and abnormal EKG, there was no significant differences in mortality[P=0.560 and complication rate[P=0.693 . In the preoperative FEV1, preoperative FVC and predicted postoperative FEV1, prognostic cut-off points were 1800cc, 2600cc and 1300cc, and at points, positive predicted value were 12.3%, 10.5%.and 7.7% and negative predicted value were 97.8%, 98.3% and 96.2% respectively. The preoperative FEV1 is the most reliable indicator in assessment of prognosis of pneumonectomy.

• 한국공작기계학회논문집
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• 제10권2호
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• pp.79-88
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• 2001

This paper suggests to predict the failure of helical gear extrusion die. The basic assumption that constitutes the frame-work for any combined stress failure theory is that failure is predicted to occur when the maximum value of stress becomes equal to or exceeds the value of the same modulus that produces failure in a simple uniaxial stress test using the same material. The stresses which were calculated to each critical points are applied maximum normal stress theory and distor-tion energy theory. The theroretical analysis and experimental results for Samanta process and New process dies were com-pared.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2002년도 가을 학술발표회 논문집
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• pp.295-302
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• 2002

Shear strength of the rock joint is dependent on the roughness and the compressive strength of the joint surface, normal stress and etc. Roughness of the joint profile is described by JRC suggested by Barton and Choubey (1977). Choice of the JRC value is subjective. A number of studies have been carried out to quantify the JRC. Predicted shear strengths by Barton's Equation using the new quantification method of JRC suggested by Chun and Kim (2001) were compared results of shear tests and new criteria of shear strength which have a better accuracy to predict shear strength was suggested.

• 한국정밀공학회지
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• 제12권8호
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• pp.53-62
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• 1995

In recent years, the rapid development of the machine tool and tough insert has made metal removal rates increase, and automatic system without human supervision requires a higher degree reliability of machining process. Therefore the control of chips is one of the important topics which deserves much attention. The chip classification was made based upon standard deviation of the mean cutting force measured by a tool dynamometer. STS304was chosen as the workpiece which is known as the difficult-to-cut material and mainly saw-toothed chip produced, and the chip type according to the standard deviation of mean cutting force was classified into five categories in this experiment. Long continuous type chip which interrupts the normal cutting process, and damages the operator, tool and workpiece has low standard deviation value, while short broken type chip, which is favourable chip for disposal, has relatively large standard deviation value. In addition, we investigated the possibility that the chip type can be predicted analyzing the relationship between chip type and cutting condition by the trained neural network, and obtained favourable results by which the chip type can be predicted with cutting conditon before cutting process.

• The Korean Journal of Physiology
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• 제20권2호
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• pp.184-191
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• 1986

Membrane potential of cells in the isolated rabbit coronary sinus was measured by conventional glass microelectrode and investigated the effect of $[K^+]_0$ variation in control, 20 mM and Ach-containing Tyrode solution. The results obtained were as follows: 1) The resting membrane potential exposed to normal Tyrode solution containing 3 mM $K^+\;was\;about\;-60{\sim}\;-65mV$. At extracellular $K^+$ concentrations from 1 to 30 mM the resting Potential was reasonably well described by Goldman -Hodgkin -Katz equation on the assumption that $[K^+]_1$ was 150 mM and that the ratio of membrane permeability coefficient for $Na^+\;and\;K^+,\;P_{Na}/P_K\;({\alpha})$ was 0.07. 2) In 20 mM Na-Tyrode solution (replacing by equimolar Tris) the resting membrane potential was hyperpolarized by 15 to 20 mV and showed slightly deviated to depolarized direction compared to the predicted value by Goldman-Hodgkin -Katz equation. 3) In the presence of $10^{-6}M$ Ach, the resting potentials at $[K^+]_0$ levels from 1 to 30 mM were well fitted with the predicted value on the assumption that $P_{Na}/P_K$ was 0.0144. It could be concluded that the low resting membrane potential of coronary sinus cells reflects a relatively high ratio $P_{Na}/P_K$ of about 0.07.

• Journal of Preventive Medicine and Public Health
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• 제28권3호
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• pp.690-705
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• 1995

Pulmonary function tests were conducted on 815 healthy primary school children (390 males and 425 female) in rural area using Collins Survey Spirometer (Warren E. Collins, Inc., U.S.A.) with X-Y Recorder. Respiratory symptoms(cough, sputum, sore throat, chest pain, chest tightness, dyspnea, coryza) were surveyed by the interviews. Multiple regression analysis and regression diagnostics were done for prediction equations of FVC, $FEV_1,\;PEFR\;and\;FEF_{25-75%}$. FVC, $FEV_1,\;PEFR\;and\;FEF_{25-75%}$ values in 3 groups of children classified by the number of symptom were compared each other through standard variable value. FVC, $FEV_1,\;PEFR\;and\;FEF_{25-75%}$ showed highly significant correlation with age, height and weight. Prediction equations for FVC, $FEV_1,\;PEER,\;FEF_{25-75%}$ are functions of height only in both male and female children aged between 6 and 12 years old. PEFR showed a significant difference related with the number of symptom in female. These results suggest that the PEFR is sensitive PFT parameter in this study.

• Asian Pacific Journal of Cancer Prevention
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• 제16권12호
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• pp.5037-5041
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• 2015

Background: An hCG regression curve has been used to predict the natural history and response to chemotherapy in gestational trophoblastic disease. We constructed hCG regression curves in high-risk gestational trophoblastic neoplasia (GTN) treated with EMA/CO and identified an optimal hCG level to detect EMA/CO resistance in GTN. Materials and Methods: Eighty-one women with GTN treated with EMA/CO were classified as primary high-risk GTN (n = 65) and single agent-resistance GTN (n = 16). The hCG levels prior to each course of chemotherapy were plotted in the 10th, 50th, and 90th percentiles to construct the hCG regression curves. Diagnostic performance was evaluated for an optimal cut-off value. Results: The median hCG levels were 264,482 mIU/mL mIU/mL and 495.5 mIU/mL mIU/mL for primary high-risk GTN and single agent-resistance GTN, respectively. The 50th percentile of the hCG level in primary high-risk GTN and single agent-resistance turned to normal before the 4th and the 2nd course of chemotherapy, respectively. The 90th percentile of the hCG level in primary high-risk GTN and single agent-resistance turned to normal before the 9th and the 2nd course of chemotherapy, respectively. The hCG level of ${\geq}118.6mIU/mL$ mIU/mL at the 5thcourse of EMA/CO predicted the EMA/CO resistance in primary high-risk GTN patients with a sensitivity of 85.7% and a specificity of 100%. Conclusion: EMA/CO resistance in primary high-risk GTN can be predicted by using an hCG regression curve in combination with the cut-off value of 118.6 mIU/mL at the 5thcourse of chemotherapy.