정보의 상관도를 이용한 OFDM신호의 PAPR저감 기법

김상우,유흥균,Kim Sang-Woo,Hieu Nguyen Thanh,Ryu Heung-Gyoon 한국전자파학회 2005 한국전자파학회논문지 Vol.16 No.3

In this paper, a new PAPR reduction method using correlation of input data sequence is proposed in order to overcome the serious drawbacks, such as necessity of side information transmission or increase of system complexity and calculation which are the basis of previous SLM, PTS and DSI method. A new PAPR reduction method can be classified into Method 1 and Method 2. Method 1 reduces the correlation between the smallest sub-sequence and neighbor smallest sub-sequence. And, to consider the own correlation in detail, the Method 2 reduces two case of correlation between neighbor smallest sub-sequences and neighbor largest sub-sequences. According to simulation result, Method 1 and Method 2 has about 0.5 $\~$ O.8 dB and 1 $\~$ l.2 dB PAPR reduction effect respectively. If more detailed process to reduce the correlation of input data sequence is considered, we can achieve better PAPR reduction performance. 본 논문에서는 SLM, PTS 그리고 DSI와 같은 OFDM 시스템에서 발생하는 높은 PAPR 문제를 해결하기 위한 기존의 PAPR 저감 기법들에서 나타나는 부가정보 전송의 필수성, 시스템 복잡도 및 계산량 증가와 같은 단점들을 해결하기 위해 입력되는 정보의 상관도를 이용하는 새로운 PAPR 저감 기법을 제안한다. 제안된 새로운 PAPR 저감 기법의 예로 Method 1과 Method 2를 제시한다. Method 1은 IFFT에 입력되는 병렬 데이터 시퀀스내의 최소 부분 시퀀스들 간의 상관도를 낮추어 주는 방식이며, 보다 많은 자체 상관도를 저감하기 위해, Method2는 최소 부분 시퀀스들 간의 상관도 뿐만 아니라 최대 부분 시퀀스들 간의 상관도 또한 낮추어준다. 성능 분석 결과에서, Method 1과 Method 2는 각각 0.5 $\~$ O.8 dB와 1 $\~$ 1.2 dB의 PAPR 저감 효과를 보였다. 이는 기존의 기법들보다 PAPR저감 효과는 작게 나타나지만 기존의 기법들이 갖는 여러 단점들을 해결할 수 있는 장점을 갖는다. 또한 보다 자세한 자체 상관도 저감을 통해 보다 큰 PAPR저감 효과를 기대할 수 있다.

On the improvement of the stability robustness in the discrete-time LQ regulator

김상우,권욱현,Kim, Sang-Woo,Gwon, Uk-Hyeon 제어·로봇·시스템학회 1995 제어·로봇·시스템학회 논문지 Vol.1 No.2

본 논문에서는 이산시간 LQ 조절기의 안정도 강인성을 주파수 영역및 시간영역에서 고찰하고 그 향상책을 제시하낟. 주파수영역에서 강인성 척도인 궤환차행렬(return difference matrix) 의 최소특이치가 상태가중치 행렬과 제어가중치 행렬의 비와 반비례함을 보이고, 시간영역에서 매개변수의 변화에 대한 안정도 강인성 범위들을 얻는다. 이 범위들의 점근적 성질을 밝히기 위하여 LQ 궤환이득의 특이치들이 상태가중치 행렬과 제어기중치 행렬의 비의 증가함수 임을 보인다. 몇가지 조건하에서 시스템 행렬(입력행렬)에 대한 안정도 강인성 범위가 상태 가중치 행렬과 제어가중치 행렬의 비가 증가(감소)함에 따라서 증가함을 보이고, 이러한 사실들을 예제를 통하여 검증한다.

임산부에서 시력저하로 발견된 림프구성 뇌하수체염 1예

김상우,권정도,박도훈,Sang Woo Kim,Jung Do Kwon,Do Hoon Park 대한안과학회 2006 대한안과학회지 Vol.47 No.7

Purpose: To report a rare case of lymphocytic hypophysitis in a 31-year-old woman who presented with gradually progressive bilateral visual loss during the third trimester of pregnancy. Methods: Ophthalmologic examination revealed best corrected visual acuity of 0.02 OD and counting fingers at 20 cm OS. Pupil examination revealed no relative afferent pupillary defect in either eye and intraocular pressure was normal in both eyes. A visual field test revealed nearly total visual defect sparing superotemporal area OD and total defect OS. An MRI of the head was performed. Results: At the time of transsphenoidal surgery following the patient`s delivery, a frozen biopsy of the lesion revealed diffuse lymphocytic infilteration and fibrosis of the pituitary gland consistent with the diagnosis of lymphocytic hypophysitis. Postoperatively the patient was treated for hypopituitarism. At 5 weeks postoperative, her best corrected visual acuity was 1.0 OU, and visual field defects resolved in both eyes. On follow-up by telephone for postoperative 7 months, the patient remained visually asymptomatic. Conclusions: The clinical presentation of lymphocytic hypophysitis may mimic pituitary adenoma, lymphoma, germinoma, and histiocytosis. The diagnosis should be suspected in any pregnant or postpartum patient with an intrasellar or suprasellar mass.

뇌졸중(腦卒中) 환자(患者)에서 강압혈(降壓穴) 자침(刺針)과 대추혈(大推穴) 사혈(瀉血)의 강압효과(降壓效果)

김상우,박인범,김철홍,서정철,윤현민,장경전,송춘호,안창범,Kim, Sang-woo,Pak, In-bum,Kim, Cheol-hong,Seo, Jung-chul,Youn, Hyoun-min,Jan, Kyung-jeon,Song, Choon-ho,Ahn, Chang-bum 대한침구의학회 2002 대한침구의학회지 Vol.19 No.5

Objective : The aim of this research was to investigate the depressive effect of acupuncture on Gangap-point and depletion on Taech'u-point in stroke patients. Methods : We measured the blood pressure of the patients who were admitted in the Oriental Medical hopital of Dongeui medical center from 21. Oct. 2001. to 20. Jan. 2002. 19 stroke patients were devided into two groups. 12 patients were treated by acupunctured on Gangap-point. The other 7 patients were treated by depletion on Taech'u-point. The activity of daily living was measured. If systolic blood pressure was over 160 mmHg or diastolic blood pressure was over 90 mmHg, acupunctured on Gangap-point and depletion on Taech'u-point were performed. Then 30minutes and 60minutes later, systolic, diastolic blood pressure and pulse rates were measured Results : After 30 minute treatment. both acupuncture on Gnagap-point and depletion on Taech'u-point significantly depressed the systolic blood pressure. After 60 minute treatment. only depletion on Taech'u-point were statistically significant in depressing the systolic blood pressure. Pulse rates were not significantly changed. Conclusion : These results suggest that depletion on Taech'u-point is more effective in depressing the systolic blood pressure than acupuncture on Gnagap-point.

간 경화도 측정을 위한 3.0T 자기공명 탄성계수 영상의 유용성에 대한 고찰 : 확산계수 영상 및 T2 강조 영상과의 비교

김상우,강충환,김성호,김경수,김순배,Kim, Sang-Woo,Kang, Chung-Hwan,Kim, Sung-Ho,Kim, Kyung-Soo,Kim, Soon-Bae 대한디지털의료영상학회 2012 대한디지털의료영상학회논문지 Vol.14 No.1

The purpose of this study is to evaluate the mutual relations by measuring SNR from T2 weighted image and ADC values on the basis of the stiffness values from liver tissues. This study was conducted that total 37 people(23 of males and 11 of females) were taken the liver MRI examination and average age was $54.5{\pm}12.7$ years old. The equipment was MAGNETOM Skyra 3.0T (SIEMENS, Erlangen, Germany) and 32 channel body-array coil. The examination were conducted with HASTE T2 weighted image by axial plane, Spin-echo EPI (echo planner image) DWI (b-value = 800) and Magnetic resonance elastography. The ROIs (region of interest: 200-300 $mm^2$) were established on the basis of the first axial stiffness image corresponded 95% confidence interval from axial stiffness image and then were measured values. After drawing the grid lines, signals were measured SNR from T2 weighted image and ADC values on the same locations that were analysed other 3 planes respectively. The results were showed correlation (0.057) that were increased to SNR from T2 weighted image by increasing stiffness value that no significant difference statistically p = 0.003. Other results were showed correlations (-0.301) that were decreased to ADC values by increasing stiffness values that no significant difference statistically p = 0.088. In the 3.0T equipment, the results may be error in much the same fashion as the 1.5T from ADC values by evaluation of fibrosis stage. However, Magnetic resonance elastography would be useful method that is used to diagnose exactly liver fibrosis stages in the 3.0T.

다중위성 및 현장관측을 이용한 동해남부 연안용승 발생 전후의 해양환경 특성

김상우,고우진,김성수,정희동,야마다게이꼬,Kim, Sang-Woo,Go, Woo-Jin,Kim, Seong-Soo,Jeong, Hee-Dong,Yamada, Keiko 해양환경안전학회 2010 해양환경안전학회지 Vol.16 No.4

본 연구에서는 하계 냉수대 발생과 관련하여 2007년 6월과 8월의 현장 및 위성에서 관측한 NOAA 해양표면수온과 SeaWiFS 해색 영상 및 QuikScat 자료를 이용하여 동해 남부해역의 수온과 클로로필 a 농도의 단기 변동과 바람을 살펴보았다. 특히, 동한난류 해역의 수온과 Chl-a의 공간적인 분포에 주목하였다. 현장관측 자료의 분석 결과, 울산 부근의 연안용승이 발생 이전인 6월의 클로로필 a 농도의 피크는 전체 조사 정점에서 50m 층에 보였고, 8월의 그 피크는 육지에 근접한 정점 4와 5에서는 10m 그리고 그 외 정점은 30m 층에 나타났지만 정점 5를 제외하고 그 농도는 6월보다 낮게 나타났다. 결과적으로, 클로로필 a 농도의 피크는 농도 차이는 있지만 8월이 6월보다 20-40m 얕은 층에 형성되었고, 이것은 남풍계열의 바람에 의한 연안용승으로 하부층의 영양염 공급 등과 관계하는 것 같다. 위성관측 수온과 클로로필 a 농도는 음의 상관관계를 보였고, 냉수가 발생한 곳에서 클로로필 a 농도는 고농도를 나타내었다. 또한, 남풍계열의 바람에 의한 영향과 동한난류의 이안은 연안에서 발생한 냉수와 Chl-a 등을 외해로 이동시키는 역할을 하였다. The objective of this paper is to explore the short-term variability of water temperature and chlorophyll a (Chl-a) derived from in-situ and satellite data (NOAA, Sea WiFS and QuikScat) in the upwelling region of the southeastern part of Korean Peninsula in June and August, 2007. Particularly we focused on the spatial variability of sea surface temperature(SST) and Chl-a in the East Korean Warm Current region. In the results of the in-situ data, the peaks of Chl-a in june was shown at a depth of 50m The peaks of Chl-a in August was shown at a depth of 10m at the stations 4 and 5 near the land, and a depth of 30m at the other stations. The Chl-a concentrations in August were also lower than those in june except for station 5. As a result, the peaks of Chl-a in August occurred at a depth of 20~40 m shallower than those of Chl-a in june. This indicates that the nutrient-rich water within the mixed layer depth may be immediately supplied by the coastal upwelling, which is due to the southerly component of wind. The relationship between SST and Chl-a showed a negative correlation, and the high concentration of Chl-a occurred in the cold water area. The southerly wind and the East Korean Warm Current influenced a remarkable offshore movement of the cold water and Chl-a near the coastal area.

청소년의 봉사활동 참여정도와 정신건강과의 관계에서 자아존중감의 매개효과 검증

김상우,장혜영,Kim, Sang woo,Jang, Hye young 대한물리치료과학회 2021 대한물리치료과학회지 Vol.28 No.2

Purpose: The purpose of this study is to examine whether the level of participation in physical activity affects the mental health of adolescents, that is, their subjective well-being. In addition, we would like to see if adolescents can improve their satisfaction with life away from the negative emotions they are currently feeling through physical activities such as hand-help and consolation activities and check if self-esteem has mediating effects in this process. Design: Survey. Methods: The survey was conducted by the surveyor, with a total of 9,041. Results: First, it shows that the higher frequency of adolescents' physical activity leads to higher self-esteem and subjective well-being. Second, it shows that the higher the self-esteem leads to higher subjective well-being felt by adolescents. Third, the level of youth physical activity itself contributes to subjective well-being while also affecting self-esteem, and the self-esteem also affects the subjective well-being that adolescents perceive. Conclusion: It will be necessary to provide programs to enhance subjective well-being for students with poor school life adaptation and satisfaction with life, as well as continuous attention such as organization and counseling of programs in schools to enhance self-esteem. In addition, it is considered that by encouraging and guiding teenagers with low satisfaction with life and low self-esteem to physical activities such as volunteer activities and leisure activities that suit their aptitude, and the adolescents will get away from the negative emotions they are currently feeling and increase their satisfaction with adaptation to school life and life.

SLM 기반 Walsh Hadamard 변환 및 DSI 기법을 이용한 PAPR 저감 기법

김상우,김남일,유흥균,Kim Sang-Woo,Kim Namil,Ryu Heung-Gyoon 한국전자파학회 2005 한국전자파학회논문지 Vol.16 No.11

본 논문에서는 OFDM(Orthogonal Frequency Division Multiplexing) 시스템에서 다중 케리 어(multi carrier) 변조에 의해 크게 발생되는 PAPR(Peak to Average Power Ratio)을 저감하기 위한 방법으로 WHT(Walsh Hadamard Transform)를 이용한 PAPR 저감 기법들을 제안한다. 제안하는 방법은 기본적으로 WHT를 기존의 PAPR 저감 기법들과 혼합하여 추가적인 대역 손실 및 큰 복잡도의 증가 없이 추가적인 PAPR저감 성능을 나타내도록 하는 방법으로, 본 논문에서는 SLM(Selective Mapping) 및 DSI(Dummy Sequence Insertion) 방법을 WHT와 결합한 방법을 제시하며, 시뮬레이션 결과로부터, WHT를 이용한 PAPR 저감 기법들이 기존의 PAPR 저감 기법보다 항상 약 1 dB 가량의 더 나은 PAPR 저감 효과를 나타냄을 확인하였다. 또한 제안된 방법은 PAPR저감뿐만 아니라 주파수 다이버시티(diversity) 효과를 얻을 수 있기 때문에 비선형 증폭기에 의한 비선형 왜곡뿐만 아니라 다중 경로 페이딩(multipath lading)이 심하게 일어나는 무선 채널 환경에서 보다 안정된 데이터 전송을 가능케 할 것으로 기대된다. In this paper, we propose some PAPR(Peak to Average Power Ratio) reduction methods using WHT(Walsh Hadamard Transform) to reduce high PAPR generated in OFDM system because of multi carrier modulation. These proposed methods are the methods which has additional PAPR reduction performance without a loss of bandwidth efficiency and a large increment of calculation complexity than common PAPR reduction methods by combining the WHT with some common methods. In this paper, we propose two PAPR reduction methods made by combining a SLM(Selective Mapping) and DSI(Dummy Sequence Insertion) with a WHT. From simulation result, we can find that the PAPR reduction methods using a WHT can get about 1 dB additional PAPR reduction performance than common PAPR reduction methods; they are SLM and DSI. And, because our proposed methods have not only PAPR reduction effect, but also frequency diversity effect, more stabile data transmission is possible in nonlinear HPA and multipath fading channel.

척수내 결핵종 - 증 례 보 고 -

김상우,김성민,심영보,최선길,Kim, Sang Woo,Kim, Sung Min,Shim, Yong Bo,Choi, Sun Kil 대한신경외과학회 2001 Journal of Korean neurosurgical society Vol.30 No.2

Intramedullary spinal tuberculoma is a rare form of central nervous system tuberculosis. The authors presented a case of 41 years old male with intramedullary and intradural extramedullary tuberculoma of the thoracic spinal cord without systemic involvement. The preoperative diagnosis was a metastatic cancer. Subtotal removal of intradural extramedullary and intramedullary mass was performed and pathological diagnosis was tuberculosis granuloma. We suggest that Intramedullary spinal tuberculoma must be considered in the differential diagnosis of the spinal cord compressive lesions in our country.

다분절 퇴행성 경추질환에서의 전방 금속판 사용 유무에 따른 환자의 예후분석

김상우,김성민,신동익,조용준,심영보,최선길,Kim, Sang Woo,Kim, Sung Min,Shin, Dong Ik,Cho, Yong Jun,Shim, Young Bo,Choi, Sun Kil 대한신경외과학회 2001 Journal of Korean neurosurgical society Vol.30 No.12

Objectives : The rates of pseudarthrosis for two- and three level fusion have been reported to be 17-63 and 50% without anterior cervical plating. The purpose of this study is to assess the effects of anterior cervical plating in the treatment of multilevel degenerative cervical disease such mostly the additional risks associated with hardware implants and its benefits, fusion rate and radiographic results, and clinical outcomes. Methods : Forty-seven patients who underwent operations between 1993 and 1997 were retrospectively reviewed. The technique for operation was same for both groups(Smith Robinson with autologous iliac bone graft). Group I consisted of 35 consecutive patients treated with anterior cervical decompression and fusion with anterior cervical plate fixation. Group II consisted of 12 consecutive patients treated without plate fixation. We compared clinical outcomes by Prolo score, radiographic results in the rate of fusion, cervical lordosis by Gore angle, disc height by Farfan method, and surgical complications between two groups. Results : The favorable clinical outcomes(excellent and good) by Prolo score were observed with the use of anterior cervical plate fixation(89% vs 75%). The successful fusion rate of multilevel cervical fusion was as seen with anterior cervical plate fixation(97% vs 75%). The overall graft complication rate in multilevel fusions was decreased, with anterior cervical plate fixation, and the hardware related complications were relatively minimal without serious consequences. Conclusion : Anterior cervical plate fixation in the treatment of multilevel cervical disorders is an effective stabilizing method which provides increased bony fusion rate, decreased graft complications, maintained cervical lordosis, early mobilization of the these patients without serious hardware related complications.