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OFDMA 시스템의 시간 및 주파수 동기 성능 향상을 위한 동기화 알고리즘
노정호,선태형,장경희,Noh Jung-Ho,Sun Tae-Hyoung,Chang Kyung-Hi 한국통신학회 2006 韓國通信學會論文誌 Vol.31 No.4A
OFDMA 방식은 다중 사용자가 서로 다른 부반송파를 통해 동시에 신호를 전송하는 방식으로서, 주파수 효율이 높고, 간단한 단일 탭 등화기로 고속 전송 시 급격히 증가하는 인접 서브캐리어 간 간섭의 보상이 가능하며, FFT를 사용하여 고속으로 구현할 수 있기 때문에 최근 고속 데이터 무선 통신을 위한 전송방식으로 사용되고 있다. 하지만 이러한 OFDMA 시스템의 장점은 부반송파간의 직교성이 유지되는 경우에만 가능하며, 직교성이 깨지는 경우에는 인접 채널 간섭이 발생되어, 시스템 성능을 저하시키게 된다. 따라서 OFDM 시스템에서는 주파수 및 시간 동기의 중요성이 크게 강조된다. 본 논문에서는 효율적인 동기 성능을 위하여 802.16d/e 및 WiBro 시스템에서 사용되는 프리앰블을 분석하여 기존에 사용되던 방식에 비해 정확도가 높은 Timing Metric 을 유도함으로써 보다 확실한 시간 동기 알고리즘을 제안하고, 시간영역에서 소수배 주파수 옵셋 추정만이 가능한 문제점을 해결하기 위해 정수배 주파수 옵셋 추정이 가능한 주파수 동기화 구조를 제안한다. 제안된 시간 및 주파수 동기 알고리즘을 적용한 시스템의 모의실험을 통하여 OFDMA 시스템에서의 인접 채널 간 간섭에 의한 성능 열화가 저하됨을 알 수 있다. In OFDMA system, multiple users transmit signal through the subcarriers assigned to the user. Capabilities of high data-rate transmission in OFDMA system come from the ability to compensate the ICI (Inter Carrier Interference) using a single-tap equalizer and to implement transmitter and receiver by employing high speed FFT circuitry. Issues of time and frequency synchronization in OFDM system is quite essential to preserve the orthogonality among subcarriers not to produce ICI. In this paper, we Int analyze the preamble used in 802.16 d/e and WiBro system. Then we propose an effective timing synchronization algorithm, which is more accurate than the conventional one in the sense of timing position, and integral frequency offset estimation scheme for the simultaneouse estimation of the fractional and integral frequency offset. Through the simulation utilizing the proposed synchronization algorithm and structure, we show that the performance degradation due to the adjacent channel interference can be mitigated for the than conventional ones.
노정호,정남수,박정욱,신동선,전창훈 대한척추외과학회 2008 대한척추외과학회지 Vol.15 No.2
Study Design:Retrospective radiologic assessmentObjectives:To assess the clinical importance of MRI for the diagnosis of posterior spinal ligament complex injuries in thora-columbar fractures.Summary ofLiterature Review:Evaluation of spinal instability is important in thoracolumbar fractures. When simple radiogra-phy and CT alone are performed, spinal instability may be missed, especially that involving the posterior spinal ligament com-plex.Materials and Methods:Eighty-seven patients who were evaluated using simple radiography, computed tomography (CT), andmagnetic resonance imaging (MRI) between March 1994 and March 2003 were included in the study. The local kyphotic anglewas measured on lateral radiography, and it was then compared to the fracture pattern on MRI. Statistical analysis was per-formed using ANOVA.Results:There was no correlation between the local kyphotic angle on radiography and fracture involvement on MRI (p=0.106).In 41 patients who were found to have involvement of the anterior column on CT, 25 had anterior column involvement, 4 hadmiddle column involvement, and 12 had posterior column involvement on MRI. In 36 patients who were found to haveinvolvement of the middle column on CT, 17 had involvement of the middle column and 19 had involvement of the posteriorcolumn on MRI. The fractures of the ten patients who were found to have posterior column involvement on CT were all seenon MRI. The coincidence of fracture patterns between CT and MRI, which was evaluated using Cohen's Kappa analysis, was0.434. The sensitivity of CT compared with MRI was 0.741 in the middle column and 0.243 in the posterior column.Conclusions:Many thoracolumbar fractures are missed on both simple radiography and CT. MRI is essential for accurate diag-nosis of posterior spinal ligament complex injuries, especially when there is involvement above the middle column, or whencanal encroachment is seen on CT.
Fibrous Dysplasia in the Epiphysis of the Distal Femur
노정호,이재우 대한슬관절학회 2017 대한슬관절학회지 Vol.29 No.1
Fibrous dysplasia is a common benign skeletal lesion that may involve a single bone or multiple bones. Although fibrous dysplasia can affect any bone, monostotic fibrous dysplasia of the long bone typically occurs in the diaphysis or metaphysis. We report a very rare case of monostotic fibrous dysplasia involving the epiphysis of the distal femur in a young man.
노정호,이기행,정세훈,황선욱 대한고관절학회 2019 Hip and Pelvis Vol.31 No.1
Purpose: Isolated greater trochanteric (GT) fractures are often identified using plain radiography of patients with post-traumatic hip pain. In many cases, the fracture extends to form an occult intertrochanteric fracture. We conducted a study to determine the frequency of occult intertrochanteric fractures in patients diagnosed with isolated GT fractures using plain radiographs. Materials and Methods: Among 3,017 individuals who visited our emergency department with a trauma-induced pertrochanteric femur fracture between July 2004 and March 2018, 100 patients diagnosed with isolated GT fractures using plain radiographs were retrospectively analyzed. Patients were divided into two groups, those with: i) isolated GT fractures (group A) and ii) occult intertrochanteric fractures (group B). In addition, plain radiographs, magnetic resonance imaging results, and treatment methods were further analyzed in each group. If surgery treatment was needed, it was performed by one surgeon, and in all cases, a 2-hole dynamic hip screw was used. Results: Among the 100 cases of isolated GT fractures diagnosed using plain radiograph, additional examinations revealed that 10 (10.0%) were suffering from isolated GT fractures alone, while the remaining 90 (90.0%) were further diagnosed with occult intertrochanteric fracture. Gender, age, mechanism of injury, and bone mineral density did not correlate with fracture type. Conclusion: In our analysis, 90% of injuries initially diagnosed as isolated GT fractures were found to extend into occult intertrochanteric fractures upon further examination with additional imaging modalities. Therefore, additional evaluation should be performed to test for the potential presence of occult intertrochanteric fractures and to establish appropriate treatment plans.
스마트패드 및 임베디드 모듈을 이용한 지상중계 및 통제시스템 개발
노정호,정현철,송용규 한국항공우주학회 2013 한국항공우주학회 학술발표회 논문집 Vol.2013 No.4
본 논문은 스마트 패드와 임베디드 모듈을 이용하여 지상중계기 및 지상통제 시스템 개발에 관한 연구이다. 운용인원의 최소화 및 휴대성, 편의성을 향상을 목표로 하였으며, GCS는 안드로이드 운영체제 기반의 Galaxy Note 10.1을 사용하여 어플리케이션으로 개발하였다. 지상 중계기는 임베디드 모듈 및 무선 공유기를 사용하여 인터넷 연결을 통해 실시간 지도데이터 전송 및 무인항공기의 영상, 그리고 비행데이터를 유선 이더넷을 통한 외부 전송, Wi-Fi를 이용하여 다수의 스마트 패드를 통해 전송할 수 있도록 하였다. 무인항공기 추적 안테나 시스템을 통합하고 운반, 설치 및 운용이 편리하도록 하였다. 또한 실제 비행시험을 통해 성능을 검증하였다. This paper describes a development of Ground Control System(GCS), including Ground Data Terminal(GDT). It is intended to improve portability and convenience in use and to minimize the operational personnel. We developed Android Apps for ground monitoring software, used smartpad(Galaxy Note 10.1, samsung) based on Android OS. And we used embedded ARM module and wireless router for GDT, integrated Tracking Antenna System. GCS can receive flight data and camera image from UAV and Geographic Information System(GIS) through the internet. GCS was executed in a flight experiment with an flying UAV to check the performance.
다중검출기 컴퓨터 단층 영상 분석을 이용한 Resident's ridge의 형태학적 연구
노정호,민병현,박정욱,안병문,Roh, Jeong-Ho,Min, Byoung-Hyun,Park, Jeong-Wook,Ahn, Byung-Moon 대한관절경학회 2008 대한관절경학회지 Vol.12 No.1
목적: 전방십자인대 재건술시 흔히 관찰하게 되는 Resident's ridge의 실제 형태학적 위치 및 모양을 알아보고자 한다. 대상 및 방법: 2007년 1월부터 2007년 8월까지 본원에서 시행한 48례의 정상 대퇴골 원위부를 촬영한 MD CT(Multidetector-Row Computed Tomography) 영상을 분석하였다. 과간절흔의 외측벽에서 1 mm 이상의 높이 변화를 보이는 경우를 Resident's ridge로 정의 하였다. $Lucion^{(R)}$ 프로그램을 이용하여 3차원 재구성한 영상을 통해 과간절흔의 전후방 길이, resident's ridge의 길이, 높이, 과간절흔의 후방 피질골로부터의 거리를 측정하였다. 결과: 환자의 평균 연령은 $59{\pm}16$세였으며 남성이 16례, 여성이 32례 이었다. Resident's ridge가 존재 하지 않았던 경우는 9례 이었으며 과간 절흔의 전후방 길이는 $25.4{\pm}3.5$ mm, Resident's ridge 의 길이와 높이의 평균값은 각각 $8.2{\pm}2.6,\;3.5{\pm}1.5$ mm 이었으며 Resident's ridge의 후방 피질골로부터의 거리는 $7.6{\pm}2.6$ mm 이었다. 결론: Resident's ridge는 많은 예에서 존재하며 뚜렷한 길이와 높이가 있기 때문에 전방십자인대 재건술시 주요한 landmark로 사용할 수 있다. Purpose: The purpose of this study was to report the real geometry of Resident's ridge doing in anterior cruciate ligament reconstruction Materials and Methods: From Jan 2007 to Aug 2007, 48 cases which had normal distal femoral condyle analyzed with Multidetector-Row Computed Tomography. Resident's ridge was defined as change of height above 1 mm in lateral wall of intercondylar notch. Anterior-posterior length of intercondylar notch, length and height of Resident's ridge, distance of Resident's ridge from posterior cortex were estimated with 3-D reconstruction using $Lucion^{(R)}$ program. Results: Cases were $59{\pm}16$ years olds and male was 16 cases, female was 32 cases. 9 cases had no Resident's ridge, anterior-posterior length of intercondylar notch was $25.4{\pm}3.5$ mm, average of length and height of the Resident's ridge was $8.2{\pm}2.6,\;3.5{\pm}1.5$ mm. Distance of the Resident's ridge from posterior cortex was $7.6{\pm}2.6$ mm. Conclusion: Resident's ridge was used as landmark in anterior cruciate ligament reconstruction, which presented in many cases and which had distinct length and height.
노정호,이재우,남영준,최기용 대한정형외과학회 2017 Clinics in Orthopedic Surgery Vol.9 No.1
Background: To assess the hemostatic effect of QuikClot Combat Gauze (QCG) compared to that of standard gauze during cruciate- retaining total knee arthroplasty (TKA). Methods: Sixty knees underwent TKA using a pneumatic tourniquet in this prospective randomized study. After implantation of the femoral and tibial components and hardening of the bone cement, the tourniquet was deflated and QCG (group 1) or standard gauze (group 2) was packed into the joint cavity for 5 minutes for hemostasis. Perioperative bleeding volume and blood transfusion volume were compared between two groups. Results: The mean intraoperative bleeding volume was 64.7 ± 12.7 mL in group 1 and 63.9 ± 9.2 mL in group 2 (p = 0.808). The mean postoperative blood drainage was 349.0 ± 170.6 mL in group 1 and 270.1 ± 136.3 mL in group 2 (p = 0.057). The average postoperative blood transfusion volume was 323.7 ± 325.9 mL in group 1 and 403.6 ± 274.8 mL in group 2 (p = 0.314). Conclusions: QCG was not significantly effective for reducing perioperative bleeding volume or the blood transfusion rate compared with standard gauze during TKA.
골다공증성 척추압박골절 및 방출성골절에 대한 polymethylmethacrylate를 이용한 경피적 척추체 성형술의 효과
노정호,이진석,이형진,양지호,이일우,김문찬 대한신경외과학회 2004 Journal of Korean neurosurgical society Vol.35 No.4
Objective : The purpose of this study is to determine the efficacy and safety of percutaneous vertebroplasty for patients with osteoporotic spinal bursting fracture. Methods : The authors reviewed retrospectively 77 patients who underwent percutaneous vertebroplasty for osteoporotic spinal fracture from May 1, 2000 to March 31, 2003. They were divided into simple compression, mild bursting and severe bursting fracture groups. Cause of injury, height loss of fractured vertebra, operation time interval after fracture, injected amount of polymethylmethacrylate, cement leakage and clinical outcome were investigated. Results : Out of 77 patients, 29 cases(38%) were bursting fractures consisted of 23 mild(mean neural canal involvement = 11%) and 6 severe cases(42.8%). Out of the 30 bursting fracture levels, bone cement leakages occurred in 15 vertebral levels(50%), which were more common compared with compression fracture(25%). But the improvement of back pain of the bursting fracture patients(83%) was not different from that of compression fracture patients(87%). In compression fractures, cement leakages were more common when vertebroplasty was done at the time of less than 10 days after onset of symptoms compared with more than 10 days. Conclusion : Bone cement leakages are more common in bursting fractures than compression fractures. Nonetheless, the complication is not significant and the same clinical improvement could be anticipated. For elderly patients especially those having difficulty in open surgery under general anesthesia due to their condition, percutaneous vertebroplasty may be considered as a therapeutic option.
자가 슬개건을 이용한 전방십자인대 재건술 시 경골터널 생성중 핵심 확공기의 파열 - 증례보고 -
노정호,양보규,박정태,제민수,Noh, Jung-Ho,Yang, Bo-Kyu,Park, Jung-Tae,Je, Min-Soo Korean Arthroscopy Society 2010 대한관절경학회지 Vol.14 No.1
This is a case of the core reamer breakage during anterior cruciate ligament reconstruction using bone-patellar tendon-bone autograft. A 19-year-old man with acute anterior cruciate ligament rupture had reconstruction surgery. During tunneling in the proximal tibia, the core reamer have been cracked open and broken. Rest of the procedure was performed routinely except the tibial sided fixation of bone block which was performed with larger interference screw than usual. The patient followed the accelerated rehabilitation program. The result was satisfactory at 2 years after surgery.