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전방 스피커 어레이 재생 방식 기반 음향 재현 성능 평가
유재현,장대영,이태진 한국방송∙미디어공학회 2015 방송공학회논문지 Vol.20 No.5
고화질, 고품질 방송에 대한 관심이 크게 증가하면서 영상 신호 뿐만 아니라 음향 신호의 고품질화를 요구하는 목소리도 높아지고 있다. 음향 신호의 고품질화에 기여하는 요소 중 하나는 가령, 10.2채널, 22.2채널 등과 같은 재생 채널 수의 확장이지만 이는 많은 수의 스피커를 설치해야만 하는 문제점이 발생한다. 이와 같은 문제를 해결하기 위한 한 가지 방법으로 전방 스피커 어레이를 통한 입체 음향 재생 방식을 들 수 있는데 본 논문에서는 스피커 어레이 기반 음장 재생 방식인 음장합성 기술 (Wave Field Synthesis, WFS)에 대한 소개 및 이론적인 분석을 하고 이 기술로 구현한 전방 스피커 어레이 시스템의 입체 음향 재현 성능을 확인하기 위한 주관 청취 평가 결과를 제시한다. 결론적으로, WFS에 기반한 전방 스피커 어레이 재생 방식이 디스크리트 5.1채널 재생 방식과 비교하여 만족스러운 음장감을 제공한다는 것을 알 수 있었다.
유재현,유환국,이원용,나찬영,정윤섭,김응수,백완기,한재진,이영탁 대한흉부심장혈관외과학회 1993 Journal of Chest Surgery (J Chest Surg) Vol.26 No.2
Supravalvular aortic stenosis is an uncommon, congenital narrowing of ascending aorta just above aortic valve. Eleven patients underwent an aortoplasty to relieve supravalvular aortic stenosis at Sejong General Hospital from July 1985 to December 1991. Age ranged from 5 to 14 years(median 9 years). There were 7 male and 4 female patients. Seven patients had characteristics of Williams' syndrome including elfin face and mental retardation. All patients had localized, hourglass type but 4 patients had atypical findings. Preoperative left ventricula-aortic pressure gradient ranged from 40 to 190 mmHg(mean 88 mmHg). To relieve severe supravalvular aortic stenosis, extended aortoplasty was used in 7 patients and standard aortoplasty in 4 patients. Postoperative pressure gradient ranged from 0 to 40 mmHg (mean 16.6 mmHg). Follow-up pressure gradient with Doppler ranged from 0 to 88mmHg(mean 32.5mmHg).
유재현,임승평,Yu, Jae-Hyeon,Im, Seung-Pyeong 대한흉부심장혈관외과학회 1991 Journal of Chest Surgery (J Chest Surg) Vol.24 No.6
We experienced a case of leiomyoma on proximal thoracic esophagus. The patient, a 42-year-old female, noted the insidious onset of dysphagia and chest discomfort for 6 months. Esophagogram showed a smooth filling defect in upper third of thoracic esophagus, T1-T4 level and esophagoscopy revealed a firm mobile mass about 6cm in length with normal overlying mucosa. The lesion was approached the Rt. posterolateral thoracotomy through 4th ICS and enucleated of tumor without difficulty. The patient`s hospital course was uncomplicated.
유재현 대한흉부심장혈관외과학회 1991 Journal of Chest Surgery (J Chest Surg) Vol.24 No.11
Bleeding after open heart surgery with cardiopulmonary bypass was a cause of concern. requiring reexploration of the chest in approximately 8 percent of patients who have had operations on the heart. From April., 1983 to October, 1991, 16 patients[2%] out of 777 patients who underwent open cardiac surgery had emergency reexploration with bleeding at the Department of Thoracic and Cardiovascular Surgery, Chungnam National University Hospital. In 12 cases[75%], reexploration was performed for continuous bleeding and the reminder[4 cases] were performed for suspected tamponade & hypotension. There were 9 cases[56%] of congenital heart disease and 7 cases of acquired heart disease. The mean blood loss were 997$\pm$472ml /sq. M in total cases and 1442$\pm$ 647ml /sq. M in cases repair of cyanotic heart disease. The mean interval till reoperation was 16.6hr [1hr~72hr] and 41 hr[12~72hr] in tamponade cases and 8.4hr[1hr~24hr] in continuous bleeding cases. The bleeding sites were identified in 7 cases: aortotomy site in 2 cases, ventriculotomy site, SVC, thymus, pleura and sternum wiring site in each other case. But no specific sites was found in the remaining 9 cases. The 8 cases had complications but all except 1 cases with hypoxic brain damage were recovered without sequale. We conclude that emergency thoractomy after open heart surgery may be lifesaving and-/or diminishing complications with bleeding if performed promptly with excessive bleeding, tamponade and unexpected hypotension.
초 저체온법과 전혈류 정지술을 이용한 하공정맥 폐쇄증의 수술 치험: 1례 보고
유재현 대한흉부심장혈관외과학회 1991 Journal of Chest Surgery (J Chest Surg) Vol.24 No.7
Membranous obstruction of the inferior vena cava[IVC] is a rare congenital anomaly that may present clinical features of Budd-Chiari syndrome caused by chronic obstruction of hepatic drain. We have experienced a case of IVC obstruction caused by hour-glass constriction and membrane in its center. Operative correction was accomplished using profound hypothermia [20%] and total circulatory arrest of 26 minutes. This technique permitted resection of membrane with direct vision and removal of thrombus of IVC and hepatic vein. After then constricted IVC was repaired with autologous pericardial patch. Total circulatory arrest was used intermittently for good visual field. Postoperative course was smooth and postoperative angiography showed unobstructed flow through the IVC in spite of slight constriction of cavoatrial junction and nearly complete disappearance of collateral vessels.