멜라토닌이 백서의 임의형 등피판 생존에 미치는 영향

홍승은,김양우,범진식,강소라 대한성형외과학회 2008 Archives of Plastic Surgery Vol.35 No.6

Purpose: In skin flap surgery, surgeons often encounter distal ischemia of the flap. If a powerful free radical scavenger is used, it may reduce the formation of free radical and improves the survival of flap. Thus, the present study purposed to examine whether the survival of flap can be enhanced by administering melatonin, which is known to be a powerful free radical scavenger a antioxidant molecule. Received July 22, 2008 Revised August 26, 2008 Accepted September 8, 2008 Address Correspondence: Yang Woo Kim, M.D., Department of Plastic and Reconstructive Surgery, Ewha Womans University Mokdong Hospital, 911-1 Mok-dong, Yangcheon- gu, Seoul 158-710, Korea. Tel: 02)2650-5149/Fax: 02)2651- 9821/E-mail: ywkim@ewha.ac.kr Methods: We divided 40 Sprague-Dawley rats into 4 groups, 10 in each group. For the control group(n=10), we intraperitoneally injected only carrier solution once 30 minutes before the operation, and once a day for 7 days from the day of operation. Among the experimental groups, a group(n=10) was administered with dimethyl sulfoxide(DMSO), in another group(n=10), melatonin was intraperitoneally injected, and in the other(n=10) melatonin was intraperitoneally injected and applied topically(2cc of 1% melatonin) to the operation site. Caudally based skin flaps measuring 3×10cm2 were elevated on the mid-dorsum of the rats. and then repositioned. On the seventh postoperative day, the survival area of the flap was measured and tissues were examined under the light microscope. Results: The control group, the DMSO group, the melatonin administration group and the melatonin administration and application group showed the mean survival rates of 55.26±9.2%, 70.29±7.47%, 81.45± 4.14% and 86.1±1.52%, respectively, for 30cm2 of flap. Compared to the control group, the experimental groups showed a significantly high increase in survival area at significance level of 95%. Conclusion: In this study, the survival rate of flap was enhanced through the administration of melatonin after flap surgery. This suggests that melatonin not only functions as a powerful free radical scavenger and oxygen radical scavenger but also stabilizes and protects cells, and by doing so, enhances the survival of moderately injured ischemic sites in the distal end of flap.

밀리미터파 기반 다중홉 다중빔 셀룰라 네트워크(M3CN) 시스템 설계 및 성능 분석

홍승은,최은영,김일규,방승찬 에스케이텔레콤 (주) 2014 Telecommunications Review Vol.24 No.2

본 논문에서는 LTE 대비 1,000배의 용량에 해당하는 120도 섹터셀 기준 최대 100Gbps 용량을 제공할 수 있는 5세대 이동통신 시스템의 후보 아키텍처를 제안한다. 제안하는 아키텍처는 1GHz 이상의 광대역폭 확보가 가능한 밀리미터파를 활용하고 장애물에 의한 밀리미터파 신호 봉쇄를 극복하기 위한 다중홉의 중계기지국을 도입하는 멀티레벨토폴로지를 사용하며 그리고 모바일 트래픽 폭증을 수용할 수 있도록 다중빔을 동시에 제공한다. 이러한 밀리미터파기반 다중홉 다중빔 셀룰라 네트워크(M3CN) 시스템은 고정형 3D 빔형성을 통해 고차-섹터화를 제공함으로써 시스템 용량을 획기적으로 증가시킬 수 있다. 또한 고차-섹터화에 따른 간섭 문제를 분석하고 간섭을 해결하는 협력 기반다중빔 전송 방식을 제안한다. 제안한 M3CN 시스템 성능 분석을 위해 링크레벨 시뮬레이션이 수행되고 이를 통해MCS별 블록-오류-율(BLER)을 도출하고 이에 기반하여 최대 시스템 용량을 제시한다.

밀리미터파 활용 5세대 이동통신 기술 개발 동향

홍승은,김일규,방승찬,Hong, S.E.,Kim, I.K.,Bang, S.C. 한국전자통신연구원 2013 전자통신동향분석 Vol.28 No.6

최근 모바일 스마트 기가 및 서비스의 새로운 패러다임 진화에 따른 초연결(Hyper connection) 사회로의 진입과 빅데이터 출현으로 인해, 모바일 트래픽은 해마다 2배씩 증가하여 10년 뒤 1,000배 이상 증가할 것으로 예상하고 있으며, 이처럼 급격히 증가하는 모바일 트래픽 증가로 인해 모바일 망 사업자의 부담이 가중되고 있다. 추가 주파수 확보가 제한된 기존의 4G 이동통신으로는 이러한 모바일 트래픽 폭증에 따른 1,000배 용량 증대를 수용할 수 없고, 따라서 광대역폭 확보가 가능한 밀리미터파 기반의 5세대 이동통신 기술 개발이 전 세계적으로 시작되고 있다. 본고에서는 비/저활용 되어 왔던 밀리미터파를 개척하여 5세대 이동통신 기술로 활용하는 기술 개발 동향을 살펴본다. 특히, 한국전자통신연구원에서 진행하고 있는 '중추 네트워크 원전기술 개발 과제' 내용을 중점적으로 소개하고자 한다.

표준 기술동향 - 60GHz 주파수 대역 기반 밀리미터파 무선전송기술 표준화 동향

홍승은,이우용,정현규,Hong, Seung-Eun,Lee, U-Yong,Jeong, Hyeon-Gyu 한국정보통신기술협회 2010 TTA저널 Vol.130 No.-

ATM 상에서 실시간 가변비트율 MPEG-2 동영상 서비스를 위한 고속 자원 재할당 프로토콜

홍승은,장경훈,김덕진,고성제 한국통신학회 1999 韓國通信學會論文誌 Vol.24 No.8

ATM과 같은 고속 패킷교환 망의 도입은 일정한 화질을 갖는 동안 동영상 서비스를 가능하게 하였다. 망 자원 사용의 효율성과 화질 사이의 타협이 절실히 요구되는 현 상황에서, ATM Forum과 ITU-T에서 정한 고정된 트래픽 기술자(Traffic Descriptor)로는 이를 만족시킬 수 없다. 따라서 본 논문에서는 동영상 세션을 발생된 트래픽에 따라 시간적으로 분할하여 각 구간에서 발생되는 트래픽을 효율적으로 기술할 수 있는 트래픽 기술자를 설정한 후, 망과의 협상을 통해 망 자원을 재할당하고 재할당된 자원에 트래픽을 적응시키는 고속 자원 재할당 프로토콜(Fast Resource Reallocation Protocol: FRRP)을 제안한다. 또한 FRRP가 효율적으로 운용될 수 있는, MPEG 부호화 알고리즘과 망 제어가 통합된 시스템 모델을 제안하고 실제 동영상 트래픽(Star Wars)을 사용한 시뮬레이션에 의해 셀 손실율 관점에서 FRRP의 성능 평가를 수행한다. 실험 결과는 고정된 트래픽 기술자 사용 시 발생하는 셀 손실율의 5∼35% 정도만을 나타내었다. The introduction of fast packet switching networks such as the ATM leads to the possibility of video services with constant quality. However, the fixed traffic descriptor(TD), which is defined by ATM Forum and ITU-T, can not simultaneously satisfy network efficiency and video quality. This paper presents fast resource reallocation protocol (FRRP) which can provide an effective compromise between network efficiency and video quality. This protocol reallocates the network resources and then adapts the traffic to the reallocated resources. In the proposed method, a video session is divided into several time-intervals according to its generated traffic and TD is calculated which well characterizes the traffic during the specific subdivided interval. In addition, a system model, where MPEG coding algorithm and network control are unified, is proposal and the performance of the FRRP in terms of cell loss rate(CLR) is evaluated though the simulation using real video traffic(Star Wars). Simulation results show that the FRRP has only 5 ~35% CLR of the fixed TD.

Energy‐efficient mmWave cell‐free massive MIMO downlink transmission with low‐resolution DACs and phase shifters

홍승은,나지현 한국전자통신연구원 2022 ETRI Journal Vol.44 No.6

The mmWave cell-free massive MIMO (CFmMIMO), combining the advantages of wide bandwidth in the mmWave frequency band and the high- and uniform-spectral efficiency of CFmMIMO, has recently emerged as one of the enabling technologies for 6G. In this paper, we propose a novel framework for energy-efficient mmWave CFmMIMO systems that uses low-resolution digital–analog converters (DACs) and phase shifters (PSs) to introduce lowcomplexity hybrid precoding. Additionally, we propose a heuristic pilot allocation scheme that makes the best effort to slash some interference from copilot users. The simulation results show that the proposed hybrid precoding and pilot allocation scheme outperforms the existing schemes. Furthermore, we reveal the relationship between the energy and spectral efficiencies for the proposed mmWave CFmMIMO system by modeling the whole network power consumption and observe that the introduction of low-resolution DACs and PSs is effective in increasing the energy efficiency by compromising the spectral efficiency and the network power consumption.

The Effect of Botulinum Toxin on an Iatrogenic Sialo-Cutaneous Fistula

홍승은,권정우,강소라,박보영 대한두개안면성형외과학회 2016 Archives of Craniofacial Surgery Vol.17 No.4

A sialo-cutaneous fistula is a communication between the skin and a salivary gland or duct discharging saliva. Trauma and iatrogenic complications are the most common causes of this condition. Treatments include aspiration, compression, and the administration of systemic anticholinergics; however, their effects are transient and unsatisfactory in most cases. We had a case of a patient who developed an iatrogenic sialo-cutaneous fistula after wide excision of squamous cell carcinoma in the parotid region that was not treated with conventional management, but instead completely resolved with the injection of botulinum toxin. Based on our experience, we recommend the injection of botulinum toxin into the salivary glands, especially the parotid gland, as a conservative treatment option for sialo-cutaneous fistula.

TDD MAC 프로토콜 설계 기술

홍승은 대한전자공학회 2002 대한전자공학회 워크샵 Vol.2002 No.10

On the Effect of Shadowing Correlation and Pilot Assignment on Hybrid Precoding Performance for Cell-Free Mmwave Massive MIMO UDN System

홍승은 한국통신학회 2021 ICT Express Vol.7 No.1

One of promising transmission technologies for beyond-5G wireless communication is cell-free massive MIMO where all the access nodes (ANs) cooperate to coherently serve all the user equipments (UEs). Based on the benefits from massive MIMO, the novel notion of cell-free network architecture is adequate to overcome the inter-cell interference limitation in ultra-dense network (UDN) environments, owing to the full cooperation among ANs. In this paper, we develop synergetic operations between the cell-free massive MIMO and mmWave ultra-wide frequency band, which is able to provide a genuine high-quality and robust wireless pervasive service by fully utilizing the basic three pillars for wireless capacity, such as bandwidth, spectral efficiency and network densification. For this goal, we study the impacts of analog precoding schemes to be combined with zero-forcing digital precoding on cell-free mmWave massive MIMO UDN systems. In addition, we investigate the effect of correlated shadowing and pilot assignment strategies on the average spectral efficiency performance for the proposed hybrid precoding schemes in both outdoor and indoor UDN environments.

둔부재건을 위한 천공지피판의 다양한 도안

홍승은,변재경 대한성형외과학회 2007 Archives of Plastic Surgery Vol.34 No.2

Purpose: The gluteal artery perforator flaps earned its popularity in buttock reconstruction due to the lower morbidity of the donor site and the flexibility in the design. Speedy and safe reconstruction is important for the success of buttock reconstruction. If a proper design is selected, satisfactory results can be obtained with more simple method of surgery. Methods: Between April 2005 and April 2006, buttock reconstruction by using gluteal artery perforator flaps were performed on sacral sores(6 cases), ischial sores(2 cases) and malignant melanoma on buttock(1 case). Various designs depending on the location and the size of the defect was made. In those designs, perforator was used as an axis for the minimal dissection of the vessel. Donor site from which sufficient amount of soft tissue can be transferred was selected, and also not causing high tension against the recipient site during the donor site closure. In addition, postoperative aesthetics, and the possibility of another design of a second operation which can be necessary in the future, was considered.Results: Patient follow up was for a mean period of 10.8 months. All flaps survived except for one that had undergone partial necrosis. Wound dehiscence was observed in one patient treated by secondary closure. Most patients presented with cosmetically and functionally satisfying resultsConclusion: By designing the flap using the perforator as an axis, depending on the defect size and degree, reconstruction can be performed with only a small tension to the donor and the recipient site. And the minimal perforator dissection allowed easier and faster reconstruction. Selection of a proper design is the key procedure which greatly affects operation time and result success.