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정준철,김형철,주종우 대한외과학회 2011 Annals of Surgical Treatment and Research(ASRT) Vol.80 No.6
Duodenal gastrointestinal stromal tumors (GISTs) are uncommon and a relatively small subset of GISTs whose optimal surgical procedure has not been well defined. Because submucosal spread and local lymph node involvement is infrequent in GISTs, wide margins with routine lymph node dissection may not be required. Various techniques of limited resection for duodenal GISTs have been described depending on the site and the size of the tumors. In this study, we report two cases of GIST involving the third and fourth portion of the duodenum successfully treated by segmental duodenectomy with end-to-end duodenojejunostomy. This technique should be considered as a treatment option for GIST located at the third and fourth portion of the duodenum.
An Unusual Presentation of Schwannoma in the Interatrial Space
정준철,김경환,장형우 대한흉부외과학회 2015 Journal of Chest Surgery (J Chest Surg) Vol.48 No.1
We report the case of a 69-year-old woman who was diagnosed with intracardiac schwannoma without symptoms. Preoperative echocardiography and cardiac magnetic resonance imaging showed a mass attached to the interatrialseptum. The initial diagnosis was a myxoma or a bronchogenic cyst. The tumor was successfully excised undercardiopulmonary bypass. However, the pathology of the excised tumor was consistent with schwannoma. We suggestthat cardiovascular surgeons consider schwannoma to be a possible differential diagnosis for a mass close tothe interatrial septum.
Isolated Congenital Left Ventricular Diverticulum in Adults
정준철,김경환,오홍철 대한흉부외과학회 2015 Journal of Chest Surgery (J Chest Surg) Vol.48 No.5
Isolated congenital left ventricular diverticulum is a rare cardiac malformation. Here, we report the case of a 33- year-old woman who had suffered from recurrent transient ischemic attacks for 6 years. Preoperative cardiac magnetic resonance imaging and computed tomography angiography revealed a diverticulum near the apex. The diverticulum was successfully obliterated by cardiopulmonary bypass. We suggest that isolated congenital left ventricular diverticulum can be easily corrected with a low surgical risk by patch repair and plication techniques.
정준철,김경환 대한흉부외과학회 2016 Journal of Chest Surgery (J Chest Surg) Vol.49 No.6
Background: Median sternotomy is the standard approach for atrial septal defect (ASD) closure. However, minimally invasive cardiac surgery (MICS) has been introduced at many centers in adult/grown-up congenital heart patients. We retrospectively reviewed the results of right anterolateral thoracotomy compared with conventional median sternotomy (CMS) for ASD closure at Seoul National University Hospital. Methods: We retrospectively analyzed 60 adult patients who underwent isolated ASD closure from January 2004 to December 2013 (42 in the CMS group, 18 in the MICS group). Preoperative, operative, and postoperative data were collected and compared between the 2 groups. Results: The MICS group was younger (44.6 years vs. 32.4 years, p=0.002) and included more females (66.7% vs. 94.4%, p=0.025) than the CMS group. Operation time (188.4 minutes vs. 286.7 minutes, p<0.001), cardiopulmonary bypass time (72.7 minutes vs. 125.8 minutes, p<0.001), and aortic cross-clamp time (25.5 minutes vs. 45.6 minutes, p<0.001) were significantly longer in the MICS group. However, there were no significant differences in morbidity and mortality between groups. Only chest tube drainage in the first 24 hours (627.1 mL vs. 306.1 mL, p<0.001) exhibited a significant difference. Conclusion: MICS via right anterolateral thoracotomy is an alternative choice for ASD closure. The results demonstrated similar morbidity and mortality between groups, and favored MICS in chest tube drainage in the first 24 hours.
정준철,심수보 한국통신학회 1991 韓國通信學會論文誌 Vol.16 No.12
적응 필터를 이용한 잡음제거기 모형은 실제의 경우 잡음신호원 으로부터 주신호입력까지 경로 전달함수와 잡음제거기의 잡음신호입력 까지의 경로 전달함수가 모두 존재한다. 종래의 잡음제거기 모형에서 한쪽의 경로 전달함수만을 고려한점을 개선하여 제안된 새 모형에서 두 방향의 전달함수가 모두 존재하는 것으로 하여 적응 잡음제거기의 최적 전달함수를 유도하였다. 적응 필터는 적응 속도가 빠른 JP 격자필터를 이용하였고 ANC-ALE 모형에 의해 SNR이 더욱 개선됨을 나타내었으며 시뮬레이션을 통하여 확인하였다. 아울러 dc bias가 특별한 신호에 대해 잡음제거기에 더욱 효과적으로 작용함을 보였다. In the actual case, a model of noise canceller using adaptive filter has both a channel transfer function from noise source to main signal input and to noise canceller input. The previous models of noise canceller have been considered to be only one side channel transfer function. Therefore, it is proposed that a new model has two channel transfer functions and derives an optimal tranfer function of adaptive noise canceller. The adaptive filter is using the joint process lattice filter that has fast adaptive speed. The signal noise radio has been improved by a model of ANC-ALE and it is confirmed with computer simulation. Beside, a dc bias is very effective for noise cancelling, especially to the particular signal.