• Journal of Chest Surgery
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• v.40 no.6 s.275
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• pp.414-419
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• 2007

Background: Replacing the ascending aorta is a standard surgical option for treating acute type A aortic dissection. But replacing the aortic arch has recently been reported as an acceptable procedure for this disease. We compared the effects of aortic arch replacement for treating acute type A aortic dissection with the effects of ascending aortic replacement. Material and Method: From 2002 to 2006, 25 patients undewent surgical treatment for acute type A aortic dissection, 12 patients undewent ascending aortic replacement and 13 patients underwent aortic arch replacement. Among the aortic arch group, an additional distal stent-graft was inserted during the operation in 5 patients. 19 patients (11 arch replaced patients and 8 ascending aortic replaced patients) were followed up at the out patient clinic for an average of $756{\pm}373$ days. All the patients undewent CT scanning and we analyzed their distal aortic segments. Result: 4 patients who underwent ascending aortic replacement died, so the overall mortality rate was 16%. Among the 11 long term followed-up arch replacement patients, 2 patients (18.1 %) developed distal aortic dilatation and one of them underwent thoracoabdominal aortic replacement later on. However, among the 8 the ascending aortic replaced patients, 5 patients (62.5%) developed distal aortic dilatation. Conclusion: Aortic arch replacement is one of the safe options for treating acute type A aortic dissection. Aortic arch replacement for treating acute type A aortic dissection could contribute to a reduced distal aortic dilatation rate and fewer secondary aortic procedures.

• Journal of Chest Surgery
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• v.40 no.6 s.275
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• pp.420-427
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• 2007

Background: Postpneumonectomy empyema (PPE) due to bronchopleural fistula (BPF) can be a surgical challenge for surgeons. We analyzed the follow-up outcomes after performing omentopexy and thoracoplasty for the treatment of PPE with BPF after pneumonectomy. Material and Mehod: Between December 1991 and January 2006, 9 patients underwent BPF closure using an omental pedicled flap for the treatment of PPE with BPF after pneumonectomy. There were 7 males and 2 females (mean age: $45.9{\pm}9$ years). The patients were followed up for a mean of 58 months (median: 28 months, range: $6{\sim}169$). When we performed omentopexy, the surgical procedures for empyema were thoracoplasy for 8 patients and the Clagett procedure for 1 patient. Thoracoplasty was performed for the latter patient due to recurrence of empyema, Result: For the 8 patients who were treated by omentopexy and thoracoplasty, there was 1 operation-related death due to sepsis. During follow up, 1 patient, who was treated by omentopexy and a Clagett procedure, died of acute hepatitis 40 months postoperatively. The early mortality was 11.1% (8/9). Of the 8 patients, including the 1 late death patient, successful closure of the BPF were achieved in all patients (8/9) and the empyema was cured in 7 patients (7/8). Conclusion: The BPF closure using an omental pedicled flap was an effective method for treating PPE with BPF due to 75-destroyed lung, and thoracoplasty with simultaneous omentopexy was effective and safe for removing dead space if the patient was young and in a good general condition.

• Journal of the Korean Institute of Gas
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• v.26 no.3
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• pp.45-53
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• 2022

In order to improve the emission of diesel engines, natural gas-diesel dual fuel combustion compression ignition engines are in the spotlight. In particular, a reactivity controlled compression ignition (RCCI) combustion strategy is investigated comprehensively due to its possibility to improve both efficiency and emissions. With advanced diesel direct injection timing earlier than TDC, it achieves spontaneous reaction with overall lean mixture from a homogeneous mixture in the entire cylinder area, reducing nitrogen oxides (NOx) and particulate matter (PM) and improving braking heat efficiency at the same time. However, there is a disadvantage in that the amount of incomplete combustion increases in a low load region with a relatively small amount of fuel-air. To solve this, sensitive control according to the diesel injection timing and fuel ratio is required. In this study, experiments were conducted to improve efficiency and exhaust emissions of the natural gas-diesel dual fuel engine at low load, and evaluate combustion stability according to the diesel injection timing at the operation point for power generation. A 6 L-class commercial diesel engine was used for the experiment which was conducted under a 50% load range (~50 kW) at 1,800 rpm. Two injectors with different spray patterns were applied to the experiment, and the fraction of natural gas and diesel injection timing were selected as main parameters. Based on the experimental results, it was confirmed that the brake thermal efficiency increased by up to 1.3%p in the modified injector with the narrow-angle injection added. In addition, the spray pattern of the modified injector was suitable for premixed combustion, increasing operable range in consideration of combustion instability, torque reduction, and emissions level under Tier-V level (0.4 g/kWh for NOx).