CSMA/CA 기반 MANET 환경에 적합한 MAC 계층 Backoff Algorithm 분석 및 제안

임청용수(Lim Cheong-yong-soo),이동훈(Lee dong-hun) 한국통신학회 2012 한국통신학회 학술대회논문집 Vol.2012 No.6

기존 네트워크 무전기 시험장비 개선방안 제시

임청용수(Lim Cheong-yong-soo),조동훈(Cho dong-hun) 한국통신학회 2013 한국통신학회 학술대회논문집 Vol.2013 No.6

사용자 정의 변조신호 생성기법 분석 및 제안

임청용수(Lim Cheong-yong-soo),이상민(Lee Sang-min) 한국통신학회 2015 한국통신학회 학술대회논문집 Vol.2015 No.06

SDR 무전기 시험을 위한 계측기 분석 및 제안

임청용수(Lim Cheong-yong-soo),이상민(Lee Sang-min) 한국통신학회 2014 한국통신학회 학술대회논문집 Vol.2014 No.6

토끼 폐장 분리관류 모형을 이용한 LPD 폐보존액과 ET-Kyoto 폐보존액의 비교

임청,김경환,김영태,성숙환,김주현,Lim, Cheong,Kim, Kyung-Hwan,Kim, Young-Tae,Sung, Sook-Whan,Kim, Joo-Hyun 대한흉부심장혈관외과학회 1997 Journal of Chest Surgery (J Chest Surg) Vol.30 No.12

폐보존방법을 개선시키기 위하여 많은 보존액들이 개발되고 있다. 본 연구의 목적은 가장 많이 알려진 세포외액형 폐보존액인 저포타슘 덱스트란(LPD)용액과 tiehalose를 포함하는 새로 개발된 세포외액형 폐보존액인 ET-Kyoto용액의 폐 보존효과를 비교분석하여 앞으로 있을 폐이식에 대비하고자 한 것이다. 12마리의 가토로부터 폐장블록을 적출하여 $10^{\circ}C에서$ 4시간동안 보관한 다음 혈액으로 재순환시키는 폐장분리관류모형을 이용하였다. 각군은 6마리씩의 토끼로 구성되었고 LPD용액과 ETK용액을 각각 100 mL/kg씩 주입하였다. 폐보존액 주입전에 20$\mu\textrm{g}$의 prostaglandin El을 사용하여 폐동맥수축을 예방하였다. 60분간의 재관류후 유출혈액의 산소분압은 Em군에서 LPD군보다 $높았으며(486.5\pm80.3$ mmHg versus 432.5 $\pm$ 82.9 mmHg at FiO2 1.0, p-value = NS), 평균 폐동맥압은 비슷하였다(33.7 $\pm2.2$ mmHg versus $35.5\pm2.0$ mmHg, p-value = NS). 흡기말기도내압은 ETK군에서 현저히 $낮았으며(8.0\pm0.6$ mmHg versus 11.8 $\pm$ 1.4 mmHg, p-value : 0.02), 습윤중량은 두군간의 통계학적인 차이는 $없었다(70.2\pm6.9%$ versus 78.5 $\pm$ 6.1%). 상기 결과로 두가지 \ulcorner보존액은 임상적으로 사용가능할만큼 만족할만한 보존기능을 확인 할 수 있었다. 그러나 두 군간의 보존효과에서는 현저한 차이가 없었다. For Improvement of lung preservation, many tripes of preservation solution were developed and tested. The aim of this study was to compare the effect of the most frequently used extracellular type pieservation solution (Low Potassium Dextran, LPD) with a newly developed trehalose containing extracellular type preservation solution(ET-Kyoto, ETK) on postischemic lung function. Twelve New-Zealand white rabbit lungs were harvested and studied on an isolated, blood-perfused model of lung function after 4 hours of cold ischemia at $10^{\circ}C$ In group I (n=6), lungs were preserved with 100 mL/kg of LPD solution; in group II(n=6), lungs were preserved with 100 mL/kg of ETK solution. A few minutes before flushing with preservation solutions, 20$\mu\textrm{g}$ of PGEI were injected into main pulmonary artery. Functions of the preserved lung were compared with PO2, PA pressure, t acheal air pressure, and drylwet ratio. The pulmonary efferent blood oxygen tension at the end of the 60-minute reperfusion period was higher in group II compacted with group I(486.5 $\pm$ 80.3 mmHg versus $432.5\pm82.9$ mmHg at FiO2 1.0, p-value = NS). The mean pulmonary arterial pressure was similar in both $groups.(33.7\pm2.2$ mmHg versus $35.5\pm2.0$ mmHg, p-value : NS). The peak inspiratory airway pressure was significantly lower in group 11(8.010.6 mmHg versus 11.8 $\pm$ 1.4 mmHg, p-value=0.02) The water content of the lung was lower in group II $(70.2\pm6.9%$ versus 78.5 $\pm6.1%),$ but not significant. These data demonstrate that a newly-developed trehalose-containing ET-Kyoto solution yield equal or slightly superior lung function after reperfusion compared with LPD solution.

폐에 발생한 양성 투명세포종 -치험 1례 보고-

임청,김관민,성숙환,김주현,Lim, Cheong,Kim, Kwhan-mien,Sung, Sook-whan,Kim, Joo-Hyun 대한흉부심장혈관외과학회 1995 Journal of Chest Surgery (J Chest Surg) Vol.28 No.9

We experienced a case of benign clear cell tumor, a very rare form of lung tumor. A forty-year-old male complained of non-specific right flank pain for 1 month prior to admission. Under the suspicion of a benign lesion, an exploratory thoracotomy was done. Since the first case was reported in 1963 by Leibow and Castleman, about 40 cases have been reported worldwide by 1993. Basically it was believed to be a benign lesion but in certain cases, it showed malignant behavior. Simple surgical excision is satisfactory to this benign lesion. But close long-term follow up is mandatory. We report this first case in Korea with the review of literature.

삼첨판막 치환술의 장기성적

임청,강문철,김경환,김기봉,안혁,Lim, Cheong,Kang, Moon-Chul,Kim, Kyung-Hwan,Kim, Ki-Bong,Ahn, Hyuk 대한흉부심장혈관외과학회 2001 Journal of Chest Surgery (J Chest Surg) Vol.34 No.9

배경: 삼첨판막친환술은 매우 드물게 시행되는 수술이며 그 장기 성적은 만족치 못한 수준이다. 또한 어떤 종류의 인공판막을 사용하느냐에 대하여도 논란이 많은 상황이다. 서울대학교병원 흉부외과에서는 1989년 1월부터 1998년 12월까지 10년동안 71명의 환자에서 72례의 삼첨판막 치환술을 시행하였으며 이 결과를 토대로 장단기 성적과 위험요인들을 분석하였다. 대상 및 방법: 평균나이는 42$\pm$13세(16~65세)였으며 남여비는 32/39였다. 술전진단은 50례의 후천성판막질환과 18례의 선천성심장질환이 있었고 삼첨판폐쇄부전만 단독으로 있었던 경우도 4례 있었다. 사용된 인공판막은 기계판막이 69개, 조직판막이 3개였다. 승모판막치환술 또는 대동맥판막치환술과 같이 시행된 경우는 50례였고 1례에서는 폐동맥판막 치환술이 같이 시행되었다. 결과: 조기사망은 7례(9.7%), 만기사망은 7례(13.0%)였고 10년 생존율은 59.2$\pm$7.2%였다. 삼천판막혈전증은 5례에서 11번에 결쳐 발생하였으며 그중 1례는 재수술을 시행받았다. 생존자들의 대부분은 심장기능분류 I-II의 상태로 현재까지 외래 추적관찰중이다. 결론: 삼첨판막치환술은 비록 혈전증등의 위험이 상존하기는 하지만 비교적 낮은 사망률과 이환율을 보이고 있으며 기계판막의 경우에도 조직판막과 비교하여 큰 차이 없이 좋은 장기성적을 얻을 수 있었다. Background: Tricuspid valve replacement is very rarely performed procedure and its long-term result is not yet satisfactory. Moreover, it is not well known whether bioprosthesis or mechanical prosthesis is the best selection for artificial valve. We reviewed 72 cases of tricuspid valve replacements in 71 patients between January 1989 and December 1998, trying to analyze the overall results and risk factors for mortality and morbidity. Material and Method: Average age of the patients at the time of operation was 42$\pm$13 years(range 16 to 65 years) and the sex ratio of male versus female was 32/39. Primary diagnosis consisted of 50 cases of aquired valvular heart disease and 18 cases of congenital heart disease, such as Ebstein’s anomaly. 4 cases had isolated tricuspid valve regurgitation. Implanted valves were 69 mechanical prosthesis and 3 bioprosthesis. Concomitant mitral or aortic valve replacements were performed in 50 cases. One patient received concomittant pulmonary valve replacement. Result: There were 7(9.72%) operative deaths and 7(13.0%) late deaths. Actuarial survival at 10 years was 59.2$\pm$7.2%. Prosthetic tricuspid valve thrombosis occurred 11 times in 5 patients. Reoperation for prosthetic tricuspid valve failure was performed in 1 patient. In this case, examination of the explanted prostheses showed that the tricuspid stenosis was the result of valve thrombosis. Among the 47 survivors, 46 patients(98%) were in functional class I or II. Conclusion: In our ten-year experience of tricuspid valve replacement, mortality and morbidity were satisfactory. Mechanical prosthesis in tricuspid position showed comparable clinical results as bioprosthesis.

흉선종의 수술적 치료 및 그 위험인자에 관한 임상적 고찰

임청,성숙환,김주현,Lim, Cheong,Sung, Sook-whan,Kim, Joo-Hyun 대한흉부심장혈관외과학회 1997 Journal of Chest Surgery (J Chest Surg) Vol.30 No.1

흉선종은 조직학적으로 양성의 양상을 보인다 하더라도 종종 악성의 경과를 밟는 까닭에 그 치료방침과 예후에 관한 많은 논란이 있어왔다. 이에 서울대학교 의과대학 흉부외과학교실에서는 1987년부터 1994년까지의 최근 8년간 흉선암과 낭종, 유암종을 제외한 흉선종으로 수술받은 41명의 환자들을 대상으로 수술결과와 위 험 인자에 관한 분석을 시도하였다. 남여비는 21 :20으로 차이가 없었으며 평균나이는 46세로 40대에 주로 발생하였다. 중증근무력증 환자는 22명으로 53.7%였으며 수술적 완전절제를 원칙으로하여 31명에서 완전절제를, 7명에서 부분절제, 3명에서 조직생검을 시행하였다. Masaoka의 병기분 류로는 I기가 27례, II기가 4례, III기가 10례였으며 IV기는 없었다. 병리 조직학적으로는 상피세포형이 14례, 임파구형이 11례,혼합형이 19례였으며 수술후 주위조직으로의 침윤이 의심되는 경우 방사선치료 또는 항암화학요법을 추가하였다. 그 결과 수술사망은 없었으며 술후 평균 36개월의 추적조사를 통해 5 명의 환자가 재발하였으며 3명의 환자가 사망하였다. 예후에 관한 위험요인의 분석을 통해 단일 요인으로서 조직학적 침윤유무가 가장 \ulcorner요한 위험 인자임을 알 수 있었다. Though thymoma is considered benign In a histopathologic specimen, its unusual behavior makes it important for surgeons to manage this neoplasm as cancerous lesion. Hence we clinically analysed the surgical cases of thymoma in our hospital, And we suggest the risk factors for its prognosis From January 1987 to December 1994, we experienced 41 surgical cases of thymoma, excluding thymic carcinoma and cysts. There were 21 male and 20 female; age ranged from 16 to 64 years. Among them, myasthenia gratis was present in 22 patients(53.7%). Surgical treatment consisted of complete resection in 31 patients, partial resection In 7 patients, and biopsy only in 3 patients. According to Masaoka's classification, there were 27 patients in milage 1, 4 patients in stage II, and 10 patients In stage III. Histopathology was of epithelial type in 14 patients, Iymphocytic type in 11, and mixed type in 19. Eleven patients had adjuvant radiotherapy, chemotherapy, or b th and there was no surgical mortality. Postoperative follow-up ranged from 1 to 88 months (mean )6 months) and three patients died and 5 patients suffered recurrences during the follow-up period. Postoperative risk factors were advanced Masaoka stage, invasiveness, and surgical method.

체외순환후 혈중 Thromboxane $B_2$와 Endothelin-1 농도 변화에 미치는 Aprotinin의 효과

임청,윤태진,김연승,김승후,이재담,노준량,송명근,Lim, Cheong,Yun, Tae-jin,Kim, Yeon-seung,Kim, Seung-hoo,Lee, Jae-dam,Rho, Joon-Ryang,Song, Meong-Gun 대한흉부심장혈관외과학회 2000 Journal of Chest Surgery (J Chest Surg) Vol.33 No.3

Background: Thromboxane A2 and endothelin-1 are the potent vasoconstrictors affecting pulmonary pathophysiology in response to whole body inflammatin following CPB. Aprotinin, as an antiiflammatory agent, may decrease the release of such vasoactive substance from pulmonary tissues, preventing pulmonary hypertension after cardiopulmonary bypass. Material and Method: Ten mongrel dogs(Bwt. ac. 20kg) were subjected to cardioupulmonary bypass for 2 hours and postbypass pulmonary vascular resistance(0, 1, 2, 3 hours) were compared with prebypass level. The dogs were divided into 2 groups; control group(n-5) and aprotinin group(n=5). In the aprotinin group, aprotinin was administered as follows; 50,000 KIU/kg mixed in pump priming solution, 50,000 KIU/kg prebypass intravenous infusion over 30 minutes, 10,000 KIU/kg/hour postbypass continuous infusion. Prebypass and postbypass 0, 1, 2, 3 hour pulmonary vascular resistance were measured. At prebypass and postbypass 0, 90, 180 minutes, blood samples were obtained from pulmonary arterial and left atrial catherers for the assay of plasma thromboxane B2 a stable metabolite of thromboxane A2, and endothelin-1 concentrations. Result: The ratios of pustbypass over prebypass pulmonary vascular at postbypass 0, 1, 2, 3 hours were 1.28$\pm$0.20, 1.82$\pm$0.23, 1.90$\pm$0.19, 2.14$\pm$0.18 in control group, 1.58$\pm$0.18, 1.73$\pm$0.01, 1.66$\pm$0.10, 1.50$\pm$0.08 in aprotinin group ; the ratios gradually increased in control group while decreased or fluctuated after postbypass 1 hour in aprotinin group. There was statistically significant difference between control group and aprotinin group at postbypass 3 hours(P=0.014). Pulmonary arterial plasma concentration of thromboxane B2(pg/ml) at prebypass, postbypass 0, 90, 180 minutes were 346.4$\pm$61.9, 529.3$\pm$197.6, 578.3$\pm$255.8, 493.3$\pm$171.3 in control group, 323.8$\pm$118.0, 422.6$\pm$75.6, 412.3$\pm$59.9, 394.5$\pm$154.0 in aprotinin group. Left atrial concentrations were 339.3$\pm$89.2, 667.0$\pm$65.7, 731.2$\pm$192.7, 607.5$\pm$165.9 in control group, 330.0$\pm$111.2, 468.4$\pm$190.3, 425.4$\pm$193.6, 4.7.3$\pm$142.8 in aprotinin group. These results showed decrement of pulmonary thromboxane A2 generation in aprotinin group. Pulmonary arterial concentrations of endothelin-1(fmol/ml) at the same time sequence were 7.84$\pm$0.31, 13.2$\pm$0.51, 15.0$\pm$1.22, 16.3$\pm$1.73 in control group, 7.76$\pm$0.12, 15.3$\pm$0.71, 22.6$\pm$6.62, 14.9$\pm$1.11 in aprotinin group. Left atrial concentrations were 7.61$\pm$17.2, 57.1$\pm$28.4, 18.9$\pm$18.2, 31.5$\pm$20.5 in control group, 5.61$\pm$7.61, 37.0$\pm$26.2, 28.6$\pm$21.7, 37.8$\pm$30.6 in aprotinin group. These results showed that aprotinin had no effect on plasma endothelin-1 concentration after cardiopulmonary bypass. Conclusion: Administration of aprotinin during cardiopulmonary bypass could attenuate the increase in pulmonary vascular resistance after bypass. Inhibition of pulmonary thromboxane A2 generation was thought to be one of the mechanism of this effect. Aprotinin had no effect on postbypass endothelin-1 concentration.

CCD Camera를 이용한 이동체의 궤적 추출 알고리즘

임청,김용득,Lim Cheong,Kim Yong-Deak 대한전자공학회 2005 電子工學會論文誌-SP (Signal processing) Vol.42 No.2

영상을 이용한 이동체의 확인과 추출은 용이하지 않다. 어떠한 이동체인지, 어떠한 주위환경인가에 따라 그 추출방식이 다양하고 특수화 될 수밖에 없기 때문에 좀 더 환경적 요소의 영향을 적게 받을 수 있는 방법이 요구 되고 있는 실정이다. 본 논문에서는 CCD 카메라의 촬영방식인 인터레이스 방식의 원리와 CCD의 노출 시간 동안 이동한 이동체 영상의 특징등 을 이용 촬영된 동영상중 이동체가 발견된 한 장의 정지영상에서 이동체를 추출할 수 있는 이동체 추출 알고리즘을 제안한다. It is not easy to find and extract a moving object from its background. The extraction method is specific as what it is and how its environment is. So recently the more general method which is less affected by its environmental elements is required. So, In this paper we report on the moving object extraction algorithm using the features of the interlaced-image-capturing method which is adopted in the CCD Camera, an afterimage for exposing time and the fact that an afterimage has same color level. Unlike much of existing algorithms it is use oかy one stationary picture to apply this algorithm.