소아에서 흉부 압박상 후 발생한 경부기관의 완전 파열

변정훈,조성래,조성호 대한흉부외과학회 2007 Journal of Chest Surgery (J Chest Surg) Vol.40 No.4

흉부 압박상에 의한 경부 기관의 파열은 매우 드물게 발생하며, 여러 가지 기전에 의해 설명되고 있다. 기관 손상을 받은 많은 환자는 병원에 도착하기 전에 사망하기 때문에 빠른 진단에 의한 치료는 예후를 결정하는 데 매우 중요하다. 교통사고에 의한 흉부 압박상으로 호흡곤란을 주소로 내원한 8세의 남아에서 발생한 경부 기관의 완전파열 1예를 조기 진단하여 수술치험하였기에 문헌고찰과 함께 보고하는 바이다.

활성탄 또는 촉매가 장착된 배리어 유전체 방전 하이브리드. 공기청정 시스템의 나노입자 및 잔류 오존 제거 특성

변정훈,황정호,지준호,강석훈,Byeon, Jeong-Hoon,Hwang, Jung-Ho,Ji, Jun-Ho,Kang, Suk-Hoon 대한기계학회 2003 大韓機械學會論文集B Vol.27 No.4

DBD(Dielectric Barrier Discharge) plasma in air is well established for the production of large quantities of ozone and is more recently being applied to aftertreatment processes for HAPs(Hazardous Air Pollutants). Aim of this work is to determine design and operating parameters of a hybrid air cleaning system. DBD and ESP(Electrostatic Precipitator) are used as nano particle charger and collector, respectively. Pelletized MnO$_2$ catalyst or activated carbon is used fer ozone decomposition or adsorption material. AC voltage of 7~10 KV(rms) and 60 Hz is used as DBD plasma source. DC - 8 KV is applied to the ESP for particle collection. The overall particle collection efficiency for the hybrid system is over 85 % under 0.64 m/s face velocity. Ozone decomposition efficiency with pelletized MnO$_2$ catalyst or activated carbon packed bed is over 90 % when the face velocity is under 0.4 m/s in dry air.

Femoro-Supragenicular Popliteal Bypass with a Bridging Stent Graft in a Diffusely Diseased Distal Target Popliteal Artery: Alternative to Below-Knee Popliteal Polytetrafluoroethylene Bypass

변정훈,김태규,송윤규 대한흉부외과학회 2017 Journal of Chest Surgery (J Chest Surg) Vol.50 No.5

Background: Lesions in distal target arteries hinder surgical bypass procedures in patients with peripheral arterial occlusive disease. Methods: Between April 2012 and October 2015, 16 patients (18 limbs) with lifestyle- limiting claudication (n=12) or chronic critical limb ischemia (n=6) underwent femoral–above-knee (AK) polytetrafluoroethylene (PTFE) bypass grafts with a bridging stent graft placement between the distal target popliteal artery and the PTFE graft. Ring-supported PTFE grafts were used in all patients with no available vein for graft material. Follow-up evaluations assessed clinical symptoms, the ankle-brachial index, ultrasonographic imaging and/or computed tomography angiography, the primary patency rate, and complications. Results: All procedures were successful. The mean follow-up was 12.6 months (range, 11 to 14 months), and there were no major complications. The median baseline ankle-brachial index of 0.4 (range, 0.2 to 0.55) significantly increased to 0.8 (range, 0.5 to 1.0) at 12 months (p<0.01). The primary patency rate at 12 months was 83.3%. The presenting symptoms resolved within 2 weeks. Conclusion: In AK bypasses with a diffusely diseased distal target popliteal artery or when below-knee (BK) bypass surgery is impossible, this procedure could be clinically effective and safe when used as an alternative to femoral-BK bypass surgery.

차세대 공중전술네트워크를 위한 Learning-Backoff 기반 무선 채널 접속 방법

변정훈,박상준,윤준혁,김용철,이원우,조오현,주태환 중소기업융합학회 2021 융합정보논문지 Vol.11 No.1

원활한 작전 수행을 통한 국방력의 강화를 위해 전술네트워크의 기능은 필수적이다. 전시 상황에서 다양한 전술, 전략은 수많은 정보들을 근거로 한다. 이를 위해 정찰기를 비롯한 다양한 정보 수집 장치 및 자원들이 방대한 양의 정보 수집을 위해 사용되고, 이들 대다수는 전술네트워크를 통해 정보를 전달한다. 채널의 사용 여부를 판단하여 상황에 따라 경쟁 기반으로 채널에 접속을 하는 국방전술네트워크 환경에서, 매우 높은 이동성을 갖는 정찰기 등 고속 이동 노드는 불필요한 채널 점유로 인하여 잠재적인 성능 열화 문제가 발생할 수 있다. 본 논문에서는 채널 예약 시점을 정하는 경쟁 윈도우(Contention Window)의 크기를 경험적으로 학습시켜 네트워크 처리량을 증가시키는 Learning-Backoff 방식 의 무전 채널 접속 방법을 제안한다. 제안하는 방법은 고속 이동 노드의 수가 많아짐에 따라 더욱 좋은 성능을 보이고 있으며, 정찰기 4대가 운영되는 특정 작전 시나리오에 적용하였을 경우 처리량이 최대 25% 증가한다. For strengthening the national defense, the function of tactical network is essential. tactics and strategies in wartime situations are based on numerous information. Therefore, various reconnaissance devices and resources are used to collect a huge amount of information, and they transmit the information through tactical networks. In tactical networks that which use contention based channel access scheme, high-speed nodes such as recon aircraft may have performance degradation problems due to unnecessary channel occupation. In this paper, we propose a learning-backoff method, which empirically learns the size of the contention window to determine channel access time. The proposed method shows that the network throughput can be increased up to 25% as the number of high-speed mobility nodes are increases.

식도에서 발생한 양성 신경초종 -수술치험 2예-

변정훈,박성달 대한흉부외과학회 2005 Journal of Chest Surgery (J Chest Surg) Vol.38 No.8

Esophageal schwannoma is very rare and almost of all cases are diagnosed as esophageal submucosal tumor preoperatively. Final diagnosis is made by postoperative immunohistochemical (IHC) staining of the surgical specimen. We experienced two cases of esophageal submucosal tumor, one was 63 year old female suffering from three months of dysphagia and another was 39 year old female complaining of two months of intermittent dysphagia. Two esophageal tumors were completely removed by esophagectomy and enucleation through right thoracotomy respectively. Postoperative IHC staining demonstrated S-100 positive without mitotic figures and confirmative diagnosed was made as benign esopphageal schwannoma. 식도에 발생하는 신경초종은 매우 드문 질환으로 알려져 있으며, 술 전 대부분 식도 점막하종양으로 진단된다. 확진은 술 후 시행되는 면역조직화학 검사에 의해 내려진다. 본원에서는 3개월 동안의 연하곤란을 주소로 내원한 63세 여자 환자와, 2개월간의 간헐적인 연하곤란을 주소로 내원한 39세의 여성에서 발생한 식도 점막하 종양을 우측개흉술을 통한 식도 절제술 및 종양 적출술을 각각 시행하여 제거하였다. 술 후 면역조직화학 검사 결과 2예 모두 S-100양성으로 나타나 식도의 양성 신경초종으로 확진되었다.

수중 네트워크의 링크 적응을 위한 기계 학습 기반 MCS 예측 모델 적용 방안

변정훈,조오현 중소기업융합학회 2020 융합정보논문지 Vol.10 No.5

This paper proposes a link adaptation method for Underwater Internet of Things (IoT), which reduces power consumption of sensor nodes and improves the throughput of network in underwater IoT network. Adaptive Modulation and Coding (AMC) technique is one of link adaptation methods. AMC uses the strong correlation between Signal Noise Rate (SNR) and Bit Error Rate (BER), but it is difficult to apply in underwater IoT as it is. Therefore, we propose the machine learning based AMC technique for underwater environments. The proposed Modulation Coding and Scheme (MCS) prediction model predicts transmission method to achieve target BER value in underwater channel environment. It is realistically difficult to apply the predicted transmission method in real underwater communication in reality. Thus, this paper uses the high accuracy BER prediction model to measure the performance of MCS prediction model. Consequently, the proposed AMC technique confirmed the applicability of machine learning by increase the probability of communication success. 본 논문은 수중 IoT 네트워크에서 센서의 전력 소비를 줄이고 네트워크의 처리량을 향상하는 수중 링크 적응 방법을 제안한다. 링크 적응 방법의 하나인 AMC(Adaptive Modulation and Coding) 기술은 SNR(Signal Noise Rate)과 BER(Bit Error Rate)의 강한 상관관계를 이용하지만, 수중에 바로 적용하는 것은 어렵다. 따라서 수중 환경에 적합한 머신러닝 기반의 AMC 기술을 제안한다. 제안하는 MCS(Modulation Coding and Scheme) 예측 모델은 수중 채널 환경에서 목표 BER 값을 달성하기 위한 통신 방법을 예측한다. 예측된 통신 방법을 실제 수중 무선 통신에서 적용하는 것은 현실적으로 어렵기 때문에 본 논문에서는 높은 정확도의 BER 예측 모델을 사용해 MCS 예측 모델의 성능을 확인한다. 결과적으로 제안하는 AMC 기술은 통신 성공 확률을 올림으로써 머신러닝의 적용 가능성을 확인시켰다.

Successful Application of Veno-Venoarterial Extracorporeal Membrane Oxygenation for Acute Exacerbation of Asthma Followed by Stress Cardiomyopathy

변정훈,전영정,황상원,박재홍,이지현 연세대학교의과대학 2016 Yonsei medical journal Vol.57 No.2

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중년 부인에 발생한 자발성 벽내성 식도 박리-치험 1예-

변정훈,조성래,조성호 대한흉부외과학회 2006 Journal of Chest Surgery (J Chest Surg) Vol.39 No.7

자발성 벽내성 식도 박리는 드문 질환으로, 주로 70∼80대 여성 노인층에 발생하며, 갑작스런 흉통과 연하 장애를 증상으로 하는 것으로 알려져 있다. 추정되는 발생기전은 여러 가지가 있지만 현재까지 확립된 것은 없다. 진단은 식도 조영술과 식도 내시경으로 가능하며 다른 흉통을 일으키는 질환과의 감별 진단을 요한다. 치료는 대부분 보존적 치료로 합병증 없이 증세호전을 기대할 수 있다. 본원에서 체험한 중년 여성에 발생한 자발성 식도 벽내성 박리 1예를 문헌 고찰과 함께 보고하는 바이다.

Factors Affecting Pneumonia Occurring to Patients with Multiple Rib Fractures

변정훈,김한용 대한흉부외과학회 2013 Journal of Chest Surgery (J Chest Surg) Vol.46 No.2

Background: Rib fractures are the most common type of thoracic trauma and cause other complications. We explored the risk factors for pneumonia in patients with multiple rib fractures. Materials and Methods: Four hundred and eighteen patients who visited our hospital with multiple rib fractures between January 2002 and December 2008 were retrospectively reviewed. Chest X-rays and chest computed tomography were used to identify injury severity. Patients with only a single rib fracture or who were transferred to another hospital within 2 days were excluded. Results: There were 327 male patients (78%), and the median age was 53 years. The etiologies of the patients’ trauma included traffic accidents in 164 cases (39%), falls in 78 cases (19%), slipping and falling in 90 (22%), pedestrian accidents in 30 (7%), industrial accidents in 41 (10%), and assault in 15 (4%). The median number of rib fractures was 4.8. Pulmonary complications including flail chest (2.3%), lung contusion (22%), hemothorax (62%), pneumothorax (31%), and hemopneumothorax (20%) occurred. Chest tubes were inserted into the thoracic cavity in 216 cases (52%), and the median duration of chest tube insertion was 10.26 days. The Injury Severity Score (ISS) and rib score had a median of 15.27 and 6.9, respectively. Pneumonia occurred in 18 cases (4.3%). Of the total cases, 33% of the cases were managed in the intensive care unit (ICU), and the median duration of stay in the ICU was 7.74 days. Antibiotics were administered in 399 patients (95%) for a median of 10.53 days. Antibiotics were used for more than 6 days in 284 patients (68%). The factors affecting pneumonia in patients with multiple rib fractures in multivariate analysis included age (p=0.004), ISS (p<0.001), and rib score (p=0.038). The use of antibiotics was not associated with the occurrence of pneumonia (p=0.28). In-hospital mortality was 5.3% (n=22). Conclusion: The factors affecting risk of pneumonia in patients with multiple rib fractures included age (p=0.004), ISS (p<0.001), and rib score (p=0.038). Elderly patients with multiple traumas have a high risk of pneumonia and should be treated accordingly.

Size Distributions of Aerosol Particles and Bioaerosols at a Municipal Composting Facility

변정훈,박철우,윤기영,박재홍,황정호 한국대기환경학회 2006 한국대기환경학회 학술대회논문집 Vol.- No.-