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저온 디젤 연소에서 스월비에 따른 CO 배출 및 연비 변화
국상훈(Sanghoon Kook),Paul C. Miles(Paul C. Miles),Michael Bergin(Michael Bergin),배충식(Choongsik Bae) 한국자동차공학회 2005 한국자동차공학회 춘 추계 학술대회 논문집 Vol.2005 No.11_1
Engine-out CO emission was measured over a wide range of swirl ratios and injection timings on low-temperature diesel combustion regime in a small~bore single-cylinder diesel engine. Our previous work has shown that late-cycle mixing plays an important role even in so-called dilution-controlled low-temperature combustion systems. In this study. we employ multi-dimensional numerical simulation to characterize the flow structures and their impact on CO emissions. 65% exhaust gas recirculation is simulated with additional N₂ and CO₂, The CO emission shows optimal values at swirl ratio of 2.59 and limited ranges of injection timings. The numerical simulations show that the formed CO is trapped inside bowl at high swirl of 7.12. while CO is lifted out due to an enhanced reverse squish flow with a swirl ratio of 2.59. For a lower swirl ratio of 1.44, the existence of a single, large bulk flow structure limits the mixing process. The measured fuel conversion efficiency shows maximum value at low swirl ratio. The source of the maxima is clarified by the analysis of the work conversion efficiency, combustion efficiency, and heat transfer loss. Results show heat loss plays important role in determining the fuel conversion efficiency.
Gallbladder Torsion with Accompanying Acute Appendicitis
Se Kook Kee,Jae Oh Kim,Oh Kyoung Kwon,Soon Young Nam,Jong Yeol Kim,Michael Sung 대한외과학회 2009 Annals of Surgical Treatment and Research(ASRT) Vol.77 No.2
Gallbladder torsion is a rare clinical entity and it is a difficult condition to diagnose preoperatively. About 500 cases of gallbladder torsion have been reported since 1898, when Wendel first described gallbladder volvulus. This condition most commonly occurs in elderly women and the symptoms of this disease are largely non-specific and they mimic those of acute cholecystitis. Even with the recent advances of radiologic imaging modalities, making a preoperative diagnosis of gallbladder torsion is difficult and most cases are diagnosed at the time of surgery. An early diagnosis and prompt cholecystectomy for this disease are important in order to avoid the complications of gangrene and perforation, and to reduce mortality. A high index of suspicion of gallbladder torsion on the basis of the clinical situation and the specific findings on the radiologic images, usually ultrasonography and computed tomography (CT) scanning, can make the correct preoperative diagnosis possible. Gallbladder torsion is a rare disease, and gallbladder torsion with accompanying acute appendicitis is extremely rare. We report here on a case of gallbladder torsion with accompanying acute appendicitis in an 89-year-old woman and we review the clinical aspects of gallbladder torsion. Unfortunately, the diagnosis of gallbladder torsion was missed in this case, so we retrospectively reviewed and correlated the CT findings with the surgical findings.