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문민주 대한영상의학회 1993 대한영상의학회지 Vol.29 No.1
To evaluate the results and clinical impact of defecography in patients with anorectal diseases, 304 defecographic examinations from 304 patients were reviewed. The defecographic results were screened for the anorectal angle and perineal descent at rest, squeezing and during straining. Changes of rectal configuration and canal width during straining were reviewed. 304 patients had defecation problems such as terminal constipation, defecation defficulty, blood or mucus discharge, tenesmus, obstruction sensation etc.. They were performed anorectal physical examination and anal manometry etc.., and were later treated by operation and conservative management. Normal anorectal angle were measured to be $101^{\circ}$91$^{\circ}$131$^{\circ}$at rest, during squeezing and straining respectively, In the spastic pelvic floor syndrome, increase of anorectal angle less than 10 degrees from rest to straining was observed. Incontinent patients had a larger anorectal angle(mean: 128$^{\circ}$) at rest. 7.8cm of perineal descent was found in descending perineal syndrome in comparison to 4.0cm in normal. Normal anal canal width was measured 1.4cm only during straining. but identified in incontinent patients at rest (mean:1.2cm). Abnormal rectal configuration was found in 254 defecographic examinations: rectoceles were observed in 235 cases and were associated with rectal prolapse in 115 cases, and rectal prolapses were found in 134 cases. In conclusion, the anorectal angle was valuable in evaluation of spastic pelvic floor syndrome and fecal incontinence. Degree of perineal descent was abnormally inccreased in descending perineal synddrome. In the cases of the rectoceles and rectal prolapses, defecography is helpful in preoperative evaluation of rectal wall change and postoperative follow up.
문민주 대한영상의학회 1989 대한영상의학회지 Vol.25 No.2
For the evaluation of acute appendicitis many diagnostic methods such as physical ex-amination laboratory findings plain abdomen and barium enema have been widely used. But the overall accuracy was ranged from 50% to 84% and negative appendectomy rate was reported between 5% and 35% In these days resolusion ultrasonography is well known to be a good imaging modality in evaluation of acute appendicitis and its complications. Using high resolution ultrasonography 138 patients with right lower quadrant abdominal pain were examined for 16 months. The results were compared to post-operative findings and clinical follows: 1. the sex distribution of cases were 58 males and 80 females and most common in the third decade(33.3%) 2. The positice ultrasonographic findings were in 69 cases(50%) those were simple appendi-citis without complication in 46 cases (66.7%) acute appendicitis with periappendicitis in 9 cases (13.0%) acute appendicitis with abscess in 6 cases (8.7%) acute appendicits with appendicolith in 4 cases (5.8%) and perforated appendicitis in 4 cases (16%) 3. The ultrasonographic findgs of normal appendix were in 69 cases(50%) those were nonvisualization of appendix in 62 cases (91.3%) and visualization of normal appendix with single thin echogenic wall in 6 cases(8.7%) 4. In the 50 cases of control group the visualization of normal appendix on ultrasonography were in 8 cases (16%). 5. The ovarall accuracy was 95.7% with 97.1%of sensitivity and 94.4% of specificity.
누설유량과 회전체동역학적 성능을 고려한 래버린스 씰 설계
문민주,이정인,서준호 한국트라이볼로지학회 2023 한국트라이볼로지학회지 (Tribol. Lubr.) Vol.39 No.2
This study proposes a procedure for designing a labyrinth seal that meets both leakage flow rate and rotordynamic performance criteria (effective damping, amplification factor, separation margin, logarithmic decrement, and vibration amplitude). The seal is modeled using a one control volume (1CV) bulk flow approach to predict the leakage flow rate and rotordynamic coefficients. The rotating shaft is modeled with the finite element (FE) method and is assumed to be supported by two linearized bearings. Geometry, material and operating conditions of the rotating shaft, and the supporting characteristics of the bearings were fixed. A single labyrinth seal is placed at the center of the rotor, and the linearized dynamic coefficients predicted by the seal numerical model are inserted as linear springs and dampers at the seal position. Seal designs that satisfy both leakage and rotordynamic performance are searched by modifying five seal design parameters using the multi-grid method. The five design parameters include pre-swirl ratio, number of teeth, tooth pitch, tooth height and tooth tip width. In total, 12500 seal models are examined and the optimal seal design is selected. Finally, normalization was performed to select the optimal labyrinth seal designs that satisfy the system performance requirements.