무선 센서 네트워크를 위한 분산 클러스터링 기법

나성원(Sung-Won Na),최승권(Seung-Kwon Choi),조용환(Yong-Hwan Cho) 한국엔터테인먼트산업학회 2013 한국엔터테인먼트산업학회 학술대회 논문집 Vol.2013 No.5

클러스터 기반의 무선 센서 네트워크 환경에서는 제한적인 에너지를 보유하고 있는 노드들로 구성되기 때문에 에너지를 효율적으로 사용할 수 있는 방법들이 필요하다. 이러한 배경에 따라 본 논문에서는 네트워크 전체의 정보를 알지 못하더라도 균일한 크기의 클러스터를 형성하고 에너지를 효율적으로 사용할 수 있는 클러스터링 기법을 제안하였다. 제안 기법은 시뮬레이션을 통해 노드의 수명, 노드의 에너지 소모량 등을 기존의 LEACH 및 HEED와 비교하여 보았다. 이를 통하여 제안 기법이 기존의 연구들에 비하여 노드들 간의 균형있는 에너지 소모를 유도하고, 전체 네트워크의 수명을 연장시킬 수 있음을 확인하였다.

무선 센서 네트워크에서 효율적인 에너지 사용을 위한 클러스터링 알고리즘

나성원(Sung-Won Na),최승권(Seung-Kwon Choi),이태우(Tae-Woo Lee),조용환(Yong-Hwan Cho) 한국컴퓨터정보학회 2014 韓國컴퓨터情報學會論文誌 Vol.19 No.6

최근 무선 센서 네트워크(WSN)이 침입 탐지와 생태, 환경, 대기, 산업, 교통, 화재 감시 등에 다양하게 적용되어 사용되고 있다. 본 논문에서는 에너지 효율적인 클러스터링 알고리즘을 제안한다. 제안 알고리즘은 수신전력을 바탕으로 하여 최적위치의 클러스터헤드를 선출하고 이를 통해 균일한 클러스터사이즈를 가지도록 한다. 또한 최대 깊이가 제한된 MST를 이용한 라우팅 트리를 구성하고 멀티 홉 전송을 통해 센서 노드의 위치에 관계없이 균일한 에너지 소모를 유도하도록 하였다. 이를 통해 제안 알고리즘은 기존의 LEACH나 HEED에 비해 노드의 에너지 소모를 감소시키고 균등한 에너지 소모를 유도하여 네트워크 수명을 증대시킬 수 있다. 시뮬레이션 결과 제안 알고리즘이 공평한 에너지 소모를 통해 네트워크 수명을 증대시킬 수 있음을 확인하였다. Recently, wireless sensor networks(WSNs) are widely used for intrusion detection and ecology, environment, atmosphere, industry, traffic, fire monitoring. In this paper, an energy efficient clustering algorithm is proposed. The proposed algorithm forms clusters uniformly by selecting cluster head that optimally located based on receiving power. Besides, proposed algorithm can induce uniform energy consumption regardless of location of nodes by multi-hop transmission and MST formation with limited maximum depth. Through the above, proposed algorithm elongates network life time, reduces energy consumption of nodes and induces fair energy consumption compared to conventional LEACH and HEED. The results of simulation show that the proposed clustering algorithm elongates network life time through fair energy consumption.

임상연구 : 체외순환 없는 관상동맥우회술 시 수술 전 투여한 Hydroxyethyl Starch (6% HES 130/0.4)가 혈역학 및 혈액응고에 미치는 영향

나성원 ( Sung Won Na ),남상범 ( Sang Beom Nam ),김대희 ( Dae Hee Kim ),심재광 ( Jae Kwang Shim ),양혜건 ( Hye Gun Yang ),곽영란 ( Young Lan Kwak ) 대한마취과학회 2006 Korean Journal of Anesthesiology Vol.51 No.6

Background: It is important to maintain adequate intravascular volume during off-pump coronary artery bypass surgery (OPCAB) to prevent hypotension. The aim of this study was to assess the effect of acute volume loading with new colloid solution, 6% hydroxyethyl starch (HES) 130/0.4 on hemodynamics and coagulation in patients undergoing OPCAB. Methods: With the IRB approval, forty patients undergoing OPCAB were allocated to two groups receiving 10 ml/kg of Plasma solution A (Control group, n = 21) or HES 130/0.4 (HES group, n = 19) for 30 min before pericardiotomy. We measured hemodynamic variables and coagulation parameters at 10 min after anesthesia induction (T1), 10 min after fluid loading (T2), 10 min after Y-graft formation (T3), and after sternum closure. Amount of infused fluid, blood loss, tranfusion and urine output were recorded intraoperatively and for 16 hr after surgery. Thromboelastography and electrolytes were also measured. Results: Both groups were similar in demographic data and fluid/blood volume during and after surgery. Cardiac index and right ventricular ejection fraction were maintained throughout the surgery in HES group but were decreased in Control group. The ratio of arterial oxygen partial pressure to inhaled oxygen fraction was increased in HES group after surgery. Thromboelastography and other parameters didn`t demonstrate significant differences between the groups. Conclusions: Acute HES loading before pericardiotomy could prevent the decrease of cardiac index and right ventricular ejection fraction in OPCAB patients. Additionally, it showed desirable effects on oxygenation without adverse effects on coagulation. (Korean J Anesthesiol 2006; 51: 669∼74)

임상연구 : 우심실기능평가에 있어서 경식도심초음파와 열희석법의 비교

나성원 ( Sung Won Na ),권태동 ( Tae Dong Kweon ),오영준 ( Young Jun Oh ),홍용우 ( Yong Woo Hong ),김지호 ( Ji Ho Kim ),곽영란 ( Young Lan Kwak ) 대한마취과학회 2006 Korean Journal of Anesthesiology Vol.51 No.1

Background: It is important to evaluate the right ventricular (RV) function intraoperatively for optimal management of patients undergoing cardiac surgery. The clinical relevance of thermodilution method to tranesophageal echocardiography (TEE) for the measurements of RV function during off-pump coronary artery bypass surgery (OPCAB) was evaluated in this study. Methods: Fifty patients undergoing OPCAB were included. RV function was assessed with both thermodilution method and TEE after anesthesia induction (T1), 10 min after leg elevation (T2), 10 min after returning to the supine position (T3), 10 min after Y-graft formation started (T4), 10 min after sternum closure (T5) and 10 min after applying 5 cmH2O of positive end expiratory pressure (T6). Fractional area change (FAC) and tricuspid annular plane systolic excursion ratio (TAPSE) were measured by TEE and compared to RV ejection fraction (RVEF) measured by thermodilution technique. RV end diastolic area (EDA) derived from TEE was compared to RV end diastolic volume index (EDVI) derived from thermodilution technique. Results: There was no significant correlation between echocardiographic data and thermodilution data by linear regression analysis. However, only in patients with right coronary artery stenosis less than 90%, TAPSE and FAC were significantly correlated with RVEF (P = 0.008 and 0.01, respectively) and EDA was significantly correlated with EDVI (P = 0.013) only at T4. Conclusions: RV performance measured by thermodilution technique did not correlate well with TEE finding in severe coronary artery disease patients. The correlation was significant during hemodynamically stable period (during Y-graft formation) in patients without severe right coronary artery disease. (Korean J Anesthesiol 2006; 51: 58~64)

네트워크 에이전트에 의한 정보자산 인증 및 시간 설정에 따른 최상위 보안 시스템 설계

나성원(Sung-Won Na),조용환(Yong-Hwan Cho) 한국엔터테인먼트산업학회 2013 한국엔터테인먼트산업학회논문지 Vol.7 No.1

최근 우리경제의 대외적 위상이 강화되고 기술개발 투자가 늘어남에 따라 기술개발 경쟁력 및 성과 또한 크게 향상되었다. 최근 우리 기술개발 성과에 대한 효율적인 관리와 보호가 제대로 이루어지지 않고 있어 기술유출로 인한 피해가 상당히 발생하고 있다. 대부분의 정보유출은 이동식 저장장치를 통하여 또는 분실했을 경우 정보자산의 유출이 발생하는바, 현재의 보안관련 연구는 중앙통제에 의한 Local Point에 복사 또는 암호화에 의한 data이동은 활발하게 이루어지고 있으며 더욱이 보안 USB에 의한 데이터 복사가 다양한 방법에 의해 연구되고 있다.[4] 그러나 이동식 저장장치의 분실에 대한 통제 및 중요자산의 이용횟수 등을 통한 제한이 불가능한 상태이다. 따라서 이번 본 논문에서 제안하는 중요한 정보자산을 Local Point의 적정성을 통한 인증과 시간 설정을 통해 일정시간만 허용하고 이후에는 삭제되어 정보자산을 제3자에 의한 선취를 근본적으로 차단하는 방안을 제안하고자 한다. Strengthen the external phase of our economy, and to increase investment in technology development, technology development competitiveness and performance has been improved greatly. Recent achievements in the development of our technology for the efficient management and protection do not work well due to technology leakage has caused damage considerably. Information leaks through removable storage devices, or if you have lost most of the information assets of a spill occurs, the current security-related research by the central control Local Point briskly move the data by encryption or copy is made, and Moreover the data is copied by the Security USB is being studied by a variety of methods. [4] However, through limiting the number of times it has been used for the loss of a removable storage device control and critical asset disabled state. This study, therefore, we propose to challenge the critical information assets through authentication and the adequacy of the Local Point Time settings only allow a certain amount of time after the information has been deleted, and preoccupied by a third-party assets that essentially blocked.

유사도 기반 얼굴인식 시스템 성능 향상 연구

나성원(Na, Seong-Won),이상훈(Lee, Sang-Hun),윤경로(Yoon, Kyoung-Ro) 한국방송·미디어공학회 2021 한국방송공학회 학술발표대회 논문집 Vol.2021 No.6

최근 팬데믹으로 인해 다양한 산업에서 온라인화가 빠르게 진행되고 있다. 이러한 흐름에 따라 생체 신호를 이용한 로그인 시스템이나 자동 출결관리 시스템의 개발 또한 활발하게 연구되고 있다. 이에 본 논문에서는 생체 정보 중 얼굴을 이용하여 산업에서 도입 가능한 수준까지 얼굴인식 시스템의 성능을 향상 시키고자 한다. 우리는 성능향상을 위해 먼저 얼굴인식 시스템에서 성능 저하원인인 영상 속 얼굴 위치 및 각도 변화를 해결하고자 정면 얼굴 Capture 방법을 제안하였다. 두 번째로는 FRR 오류가 발생하면 추가적으로 정면얼굴을 추출하여 개인 인증을 다시 시도방법을 제안하였다. 검증을 위해 얼굴인식 분야에서 가장 많이 사용되고 있는 유사도 기반 프레임워크를 구현하여 제안한 성능향상 방법을 적용, 실험 하였으며 420명의 Database를 구축하고 2주 동안 99개의 비디오 데이터를 수집하여 실제 산업에서 도입 가능한 환경과 유사하게 구축해 우리의 제안 방법을 테스트 및 검증하였다.

임상연구 : 체외순환 없는 관상동맥우회술을 시행 받는 환자에서 수술 전 안지오텐신 전환효소 억제제 중단이 혈역학에 미치는 영향

이용경 ( Yong Kyung Lee ),나성원 ( Sung Won Na ),남순호 ( Soon Ho Nam ),남성범 ( Sang Boem Nam ),채영근 ( Young Keun Chae ),송하나 ( Ha Na Song ),곽영란 ( Young Lan Kwak ) 대한마취과학회 2007 Korean Journal of Anesthesiology Vol.52 No.1

Background: Angiotensin-converting enzyme inhibitors (ACE-I) have been widely used for cardiac patients. This study investigated the effect of omitting ACE-I medication on hemodynamics during induction of anaesthesia and operation in patients chronically treated with ACE-I undergoing off pump coronary artery bypass graft surgery (OPCAB). Methods: Sixty patients scheduled for OPCAB were included in this study. Patients not treated with ACE-I were included in control group (Group I, n = 20). And then, patients treated with ACE-I more than 4 weeks were randomly divided into two groups: continuing group including patients who continued ACE-I medication until the morning of surgery (Group 2, n = 20) and discontinuing group including patients who discontinued ACE-lone day before the surgery (Group 3, n = 20). Norepinephrine (8㎍/ml) was infused when systolic blood pressure decreased below 90 mmHg during induction and operation. Amount of norepinephrine infused and hemodynamic data were recorded. Results: Significantly larger amount of norepinephrine was infused in Group 2 than in other two groups during obtuse marginal artery anastomosis. Total amount of norepinephrine infused during the all coronary anatsomosis was significantly larger in Group 2 than those values in other two groups. Conclusions: Continuing ACE-I treatment until the morning of surgery significantly increased the use of norepinephrine during the anastomosis. In contrast, there was no significant difference in the use of norepinephrine between Group I and Group 3. Discontinuing ACE-I before the surgery may helpful to maintain hemodynamics stable during coronary anastomosis in OPCAB. (Korean J Anesthesiol 2007; 52: 34~41)

증례보고 : 개심술 후 발생한 우심실부전 환자에서 대동맥 내 풍선펌프를 이용한 치료경험 -증례보고-

최승호 ( Seung Ho Choi ),나성원 ( Sung Won Na ),오영준 ( Young Joon Oh ),심재광 ( Jae Kwang Shim ),정형준 ( Hyeong Jun Jeong ),곽영란 ( Young Lan Kwak ) 대한마취과학회 2006 Korean Journal of Anesthesiology Vol.50 No.5

The intraaortic balloon pump (IABP) is the most effective and widely used device for temporary mechanical assistance of left heart. Considering left and right ventricular (RV) interdependence, IABP may also alleviate predominantly RV dysfunction following cardiac surgery. This is the case of a 61-year-old female patient who had experienced RV failure after cardiac surgery. After tricuspid valve replacement, preexisting RV failure was progressively aggravated and systemic blood pressure could not be maintained in spite of aggressive pharmacological support on second postoperative day. Thus, mechanical support with IABP was considered to increase coronary perfusion pressure in this case. IABP dramatically improved hemodynamics and cardiac function. It was removed on fifth postoperative day and she has remained well. In conclusion, IABP could play a role in RV failure following cardiac surgery and timely treatment of the heart failure with mechanical circulatory assistance would prevent further complications. (Korean J Anesthesiol 2006; 50: 596~9)

무선 센서 네트워크를 위한 에너지 인지 클러스터링 기법

오충식(Chung-Shick Oh),나성원(Sung-Won Na),김남중(Nam-Jung Kim),최승권(Seung-Kwon Choi),조용환(Yong-Hwan Cho) 한국엔터테인먼트산업학회 2013 한국엔터테인먼트산업학회논문지 Vol.7 No.1

본 논문에서는 무선 센서 네트워크 관련 연구 분야에서 가장 중요한 이슈인 에너지 효율성에 기반을 두어, 클러스터 구성의 복잡성을 감소시키고 클러스터 헤드 재선출과 클러스터 재구성을 통하여 노드의 에너지 소모를 최소화하면서 네트워크 수명을 연장시킬 수 있는 에너지 인지 클러스터링 기법을 제안하였다. 제안 기법은 노드의 에너지를 고려한 클러스터 헤드 재선출과 불필요한 오버헤드를 감소시키도록 필요에 따라 동적으로 클러스터를 재구성하도록 하여 전체 네트워크의 에너지 효율을 높일 수 있도록 하였다. NS-2를 이용한 시뮬레이션 결과 제안 알고리즘을 적용한 기법이 에너지 효율을 높여 노드의 에너지 소모를 감소시키고 네트워크의 수명을 증가시켰음을 확인하였다. This paper proposes an energy-aware clustering method that can increase network lifetime and reduce complexity of cluster formation based on the energy efficiency which is the most important issue of the research field related to wireless sensor networks. The proposed method increases the energy efficiency of entire network by reforming cluster dynamically for reducing unnecessary overhead, and it also provides energy aware cluster head reelection. Simulation results using NS-2 show that the proposed method increases network lifetime and reduces energy consumption by increasing energy efficiency of each node.

증례보고 : 카테콜아민에 의한 심근병증과 울혈성 심부전이 동반된 갈색세포종 환자의 마취경험

최은미 ( Eun Mi Choi ),박청훈 ( Chung Hoon Park ),홍승범 ( Seung Bum Hong ),나성원 ( Sung Won Na ),오영준 ( Young Jun Oh ) 대한마취과학회 2009 Korean Journal of Anesthesiology Vol.56 No.5

Catecholamine-induced cardiomyopathy associated with pheochromocytoma is a relatively well-recognized but rare entity. We report a case of 15-year old man with a pheochromocytoma and severe heart failure caused by a catecholamine-induced cardiomyopathy. He had symptoms such as fatigue, cold sweating, and dyspnea for 7 months. The chest x-ray showed an enlarged cardiac shadow and pulmonary edema. Echocardiography showed severe decreased left ventricular contractility with multiple thrombi and right ventricular hypokinesia with mild pulmonary hypertension. This report describes our experience of the anesthetic management for the removal of pheochromocytoma with catecholamine-induced cardiomyopathy, which barely responded to high vasopressin and epinephrine. (Korean J Anesthesiol 2009;56:601~4)