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.

OFDMA 시스템의 시간 및 주파수 동기 성능 향상을 위한 동기화 알고리즘

노정호,신태형,장경희 한국통신학회 2006 韓國通信學會論文誌 Vol.31 No.4

Toxicological evaluation of genotoxicity and 28-day oral toxicity study on freeze-dried powder of Allomyrina dichotoma larvae

노정호,윤은영,김지영,이병석,황재삼,정은주,문경식 한국응용곤충학회 2015 Journal of Asia-Pacific Entomology Vol.18 No.4

Edible insects have noteworthy potential as an alternative food material because of their economical efficiency and nutritional value. This study was conducted to evaluate toxicological effects on in vitro and in vivo experiments for Allomyrina dichotoma (A. dichotoma),whose larvae are known for containing biologically valuable functions. The present study included testings for genotoxicity and 28-day repeated oral toxicity. The genotoxic potentialwas evaluated by a standard battery test. To evaluate the repeated dose toxicity, the freeze-dried powder of A. dichotoma larvae was orally administered to Sprague–Dawley (SD) rats at dose levels of 0, 250, 850 and 2500 mg/kg bodyweight per day for 28 days. The powder exhibited nomutagenic or clastogenic effects based on the results of in vitro and in vivo genotoxicity tests. Also, there were no treatment-related changes or findings on the repeated oral toxicity in rats after 28 days oral administration. In conclusion, the results of these experiments suggest that the NOAEL (No Observed Adverse Effect Level) of the freeze-dried powder from A. dichotoma larvae was determined to be 2500 mg/kg/day or more in both sexes of SD rats.

Toxicological Study of Freeze-dried Allomyrina dichotoma Larvae by Oral Gavage to Sprague-Dawley Rats for 4 weeks

노정호,이병석,윤은영,황재삼,정은주,문경식 한국실험동물학회 2013 한국실험동물학회 학술발표대회 논문집 Vol.2013 No.2

Economic Crisis, Democratization, and Welfare State Generosity in South Korea, 1972-2005: Evidence from Structural Break Estimation

노정호 한국사회과학협의회 2012 Korean Social Science Journal Vol.39 No.2

In this article, I examine the effects of economic crisis and democratization on welfare state generosity in South Korea. While there are many qualitative studies documenting welfare policy expansion after the 1997 Asian financial crisis or the 1987 democratization, statistically solid empirical research remains lacking. This study fills the gap by employing several time-series methods for testing for structural breaks. Using 1972-2005 data, I show that the two economic crises, one in 1979 and the other in 1997, play major roles in explaining the growth of the Korean welfare state. This result is consistent with the hypothesis that economic crisis leads the public to ask the government for protection. I also show that democratization led to an increase in the expenditure on welfare programs, but its effect is statistically not robust.

스마트패드 기반 다중임무 GCS 개발

노정호,정현철,이영배,조완석,송용규 한국항공우주학회 2013 한국항공우주학회 학술발표회 논문집 Vol.2013 No.11

본 논문은 스마트 패드를 이용하여 다중임무 명령이 가능한 지상통제 시스템 개발에 관해 다룬다. 지상 통제 시스템은 안드로이드 어플리케이션 형태로 개발하였으며, 고정익 및 회전익 그리고 비행선 등 다양한 형태의 무인기에 사용이 가능하다. 구글지도를 이용하여 지리정보시스템을 구현하고, 무인항공기의 다양한 임무를 간편하게 설정 할 수 있도록 개발하였다. 또한 지상 중계기를 사용하여 무인항공기와 지상과의 통신 및 다중 기기의 운용을 관리하도록 하였다. 그리고 시뮬레이션을 이용하여 무인항공기 미션을 수행하며 지상통제 시스템의 성능 및 기능을 확인하였다. This paper describes a GCS(Gronund Control System) for multiple mission command using Smart Pad. The developed GCS is android application software and it is compatible with various forms of UAV(Unmanned Aerial Vehicle). Established a GIS(Geographic Information System) with Google Maps in the application, and developed for simply set up a multi-mission of UAV. Also developed GDT(Ground Data Terminal) for communication between UAV and GCS and for managing a number of device. And finally tested GCS’s functions and performance with UAV operating simulation.

조합논리회로의 고장 검출율 개선을 위한 회로분할기법

노정호,김상진,이창희,윤태진,안광선 대한전자공학회 1998 電子工學會論文誌, C Vol.c35 No.4

Partitioning problem of large combinational logic has been studied in real world. Most of logic include undectable faults from the structure of it's redundant, fan-out-reconvergent, and symetrical feature. BPT algorithm is proposed to enhance the fault voverage for combinational logic partitioning. This algorithm partitions the logic by cut the lines related to undetectable structure when seperating. Controllability and observability are considered in the process of partitioning. This algorithm is evaluated effective by testing ISCAS85 circuits.

LPG연료 추진선박 기술동향

노정호,전현민,이지웅,이재웅,이원주,김태균,김종수 해양환경안전학회 2021 해양환경안전학회 학술발표대회 논문집 Vol.2021 No.06

흉요추부 골절에서 자기공명영상의 임상적 중요성

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.

One- Year Serial Follow-up Magnetic Resonance Imaging Study of RigidFix for Femoral Fixation in Anterior Cruciate Ligament Reconstruction

노정호,이재우 대한슬관절학회 2017 대한슬관절학회지 Vol.29 No.3

Purpose: To assess graft slippage at the site of femoral fixation by follow­up magnetic resonance imaging (MRI) after anterior cruciate ligament (ACL) reconstruction with a four­strand autogenous hamstring tendon using RigidFix (DePuy Mitek).Materials and Methods: Twenty­one subjects diagnosed with ACL rupture underwent ACL reconstruction using hamstring autograft with the transtibial technique. RigidFix was used for femoral fixation and Intrafix and washer screw were used for tibial fixation. Follow­up MRIs were taken immediately after surgery and at 1, 3, 6, and 12 months after surgery. Slippage of the graft and breakage of the RigidFix cross­pin were assessed. Side­to­side difference (SSD) on stress radiographs was measured to assess residual laxity.Results: Mean slippage of the graft was 0.21±0.31 mm at one year after surgery. Cross­pin breakage was noted in two subjects: in one subject, immediately after surgery and in the other subject, at 6 months after surgery. Mean SSD was 1.32±1.07 mm at the last follow­up. The correlation coefficient between graft slippage and SSD was 0.131 (p=0.571).Conclusions: RigidFix is a stable fixation device for hamstring autograft with minimally statistically significant but clinically insignificant graft slippage. Cross­pin breakage did not affect the clinical outcomes. Careful preparation of the graft is needed for performing the technique correctly.