• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1999년도 추계학술대회논문집
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• pp.45-48
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• 1999

The optimal blank design method by sensitivity analysis has been applied to the formings of oil-pan, tailored blank and front panel have been chosen as the examples. Die shape is prepared by a commercial CAD system. Excellent results has been obtained between the numerical results and the target contour shapes. Through the investigation, the proposed systematic method of optimal blank design is found to be effective in the practical forming processes.

• 한국광학회지
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• 제8권1호
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• pp.73-79
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• 1997

랜드/그루브 기록 광디스크에서 랜드와 그루브의 영향, 각종 수차 그리고 수광계의 변화가 포커스에러신호에 미치는 영향을 나이프엣지법과 비점수차법으로 구분하여 시뮬레이션을 통해 분석하였다. 그루브의 영향에 의해 포커스에러신호에서 Aero Cross 점이 Shift되는데, 이는 디스크 반사 회절빔의 파면이 Defocus 성분을 포함하고 있기 때문이라는 것을 밝혔다. 또한 회절빔의 각 차수별로 포커스에러신호를 분석함으로써 빔점수차 방식에서 랜드와 그루브의 영향으로 에러신호의 감도가 감소함을 보았다.

• 한국농공학회:학술대회논문집
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• 한국농공학회 1999년도 Proceedings of the 1999 Annual Conference The Korean Society of Agricutural Engineers
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• pp.499-505
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• 1999

The time paramters most frequently used in hydrology are the tuime of concentration, lag time , time base, time to equilibrium , time to peak, time of travel, and residence time. Especially the time of concentraion constitute an important part of operating rainfall-runoff modeling and determining critical rainfall intensity. In the result of simulation , we discoved that SCS foumula has the highest value with length, Kerby with height and SCS with slop respectively, while only Kraven formula has the lowest value in them. With concerning to relative sensitivty, the time of concentraion was marked the constant effect according to increase of length and slope level, and the length has much more effect than the slope relatively in parameters.

• Journal of Chest Surgery
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• 제33권8호
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• pp.669-675
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• 2000

Background: Tuberculous pleurisy is the leading cause of pleural effusion in Korea. And differential diagnosis of tuberculous pleurisy with other cause is clinically very important. Traditional diagnostic methods such as routine analysis of pleural fluid, staining for acid-fast bacilli or pleural biopsy have major inherent limitaion. This study was designed to evaluate the significance of pleural fluid polymerase chain reaction(PCR) and adenosine deaminase (ADA) activity in early diagnosis of tuberculous pleurisy. Material and Method: Between March 1996 and July 1997, 198 patients with pleural effusion reviewed retrospectively. The study group included 112 cases with tuberculous effusion and 86 cases with non-tuberculous effusions, whose diagnoses were confirmed by pleural biopsy, microbiological methods, or cytology. We compared the results of PCR and pleural fluid levels of ADA between tuberculous and non-tuberculous effusions. Result: Mean age was 47.54$\pm$19.52 years(range 2 to 85 years). The positive rate of PCR was significantly higher in tuberculous group than non-tuberculous group(p<0.05). The sensitivty, specificity, positive predictive value(PPV), and negative predictive value(NPV) for PCR were 31.7, 90.9, 83.0, and 48.8%, respectively. Mean ADA activity was significantly higher in tuberculous group than non-tuberculous group(83.2 U/L vs 49.8 U/L)(p<0.05). With diagnostic thresholds of 40 U/L, the sensitivity, specificity, PPV, and NPV of ADA for tuberculosis were 75.9, 70.9, 77.3, and 69.3% respectively. At a level of 70 U/L, the sensitivity, specificity, PPV, and NPV of ADA for tuberculosis were 70.1, 75.9, 82.9, and 60.3% respectively. Conclusion: PCR is very highly specific, but less sensitive methods in diagnosis of tuberculous pleurisy. But ADA level of pleural fluid has acceptable sensitivity and specificity in diagnosis of tuberculous pleurisy. ADA activity is more useful test in the evaluation of pleural effusions.

• 대한핵의학회지
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• 제22권1호
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• pp.39-45
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• 1988

To evaluate diagnostic accuracy of liver scintigraphy we analysed liver scans of 143 normal and 258 patients with various liver diseases. Three ROC curves for SOL, liver cirrhosis and diffuse liver disease were fitted using rating methods and areas under the ROC curves and their standard errors were calculated by the trapezoidal rule and the variance of the Wilcoxon statistic suggested by McNeil. We compared these results with that of National Institute of Radiological Science in Japan. 1) The sensitivity of liver scintigraphy was 74.2% in SOL, 71.8% in liver cirrhosis and 34.0% in diffuse liver disease. The specificity was 96.0% in SOL, 94.2% in liver cirrhosis and 87.6% in diffuse liver diasease. 2) ROC curves of SOL and liver cirrhosis approached the upper left-hand corner closer than that of diffuse liver disease. Area (${\pm}$ standard error). under the ROC curve was $0.868{\pm}0.024$ in SOL and $0.867{\pm}0.028$ in liver cirrhosis. These were significantly higher than $0.658{\pm}0.043$ in diffuse liver disease. 3) There was no interobserver difference in terms of ROC curves. But low sensitivty and high specificity of authors' SOL diagnosis suggested we used more strict decision threshold.