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.

1992 - 93 년 하계 득량만의 수온과 염분의 분포

김상우,조규대,노홍길,이재철,김상현,신상일 ( Sang Woo Kim,Kyu Dae Cho,Hong Kil Rho,Jae Chul Lee,Sang Hyun Kim,Sang Il Shin ) 한국수산과학회 1995 한국수산과학회지 Vol.28 No.1

As a part of the multidisciplinary oceanographic study for the productivity enhancement in Deukryang Bay, temperature and salinity were observed from 1992 through 1993. From the results, only the data in summer of two years are compared. Owing to the contrary meteorological conditions in both summers both of temperature and salinity had the patterns of horizontal distributions quite different from each other. In 1992 with low precipitation, there was a tendency of temperature increase and salinity decrease from the bay mouth towards the bay head. In 1993 when the air temperature was abnormally low, isotherms and isohalines tended to be parallel to the local axis of the bay where the warmer and less saline water distributed along the western coast. Reduced solar radiation and increase in the relative importance of the distribution of properties along the current that was parallel to the axis of the bay could be responsible for this result. Vertical structures of both temperature and salinity were dependent on the stirring effect of tidal current. Stratification was destroyed during the spring tide while it was formed during the neap tide.

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.

조구등이 MCAO 모델 흰쥐에서 gliosis 억제에 미치는 영향

김상우,김선애,송봉근,Kim, Sang-Woo,Kim, Sun-Ae,Song, Bong-Keun 대한한방내과학회 2010 大韓韓方內科學會誌 Vol.31 No.4

Objectives : In condition of brain infarction, irreversible axon damage occurs in central nerve system(CNS), because gliosis becomes physical and mechanical barrier to axonal regeneration. Reactive gliosis induced by ischemic injury such as middle cerebral artery occlusion is involved with up-regulation of GFAP and CD81. The current study is to examine the effect of the Uncariae Ramulus et Uncus on CD81 and GFAP expression in the rat brain following middle cerebral artery occlusion. Methods : In order to study ischemic injuries on brain, infarction was induced by middle cerebral artery occlusion(MCAO) using insertion of a single nylon thread, through the internal carotid artery, into a middle cerebral artery. Cresyl violet staining, cerebral infarction size measurement, immunohistochemistry and microscopic examination were used to detect the expression of CD81 and GFAP and the effect on the infarct size and pyramidal cell death in the brain of the rat with cerebral infarction induced by MCAO. Results : The following results were obtained 1. Measuring the size of cerebral infartion induced by MCAO in the rat after injection of Uncariae Ramulus et Uncus showed the size was decreased. 2. Intravenous injection of Uncariae Ramulus et Uncus showed pyramidal cell death protection in the hippocampus in the MCAO rat. 3. Water extract injection of Uncariae Ramulus et Uncus decreased GFAP expression significantly in the MCAO rat. 4. Uncariae Ramulus et Uncus water extract decreased CD81 expression in the MCAO rat. 5. The administration of water extract of Uncariae Ramulus et Uncus induced up-regulation of c-Fos expression significantly compared with MCAO. 6. The admistration of water extract of Uncariae Ramulus et Uncus increased ERK expression significantly compared with MCAO. Conclusion : We observed that Uncariae Ramulus et Uncus could suppress the reactive gliosis, which disturbs the axonal regeneration in the brain of the rat with cerebral infaction after MCAO by controlling the expression of CD81 and GFAP. The effect may be modulated by the up-regulation of c-Fos and ERK. These results suggest that Uncariae Ramulus et Uncus can be a candidate to regenerate CNS injury.

전기로 산화슬래그 골재를 사용한 철근콘크리트 부재의 구조 성능 검토

김상우,이용준,정유진,류득현,김길희,Kim, Sang Woo,Lee, Young Jun,Jung, You Jin,Ryu, Deug Hyun,Kim, Kil Hee 한국건설순환자원학회 2010 한국건설순환자원학회지 Vol.5 No.1

멀티코드 CDMA 시스템에서 비선형 왜곡에 대처하는 PAPR 저감 기법

김상우,김남일,김선애,서재원,유흥균,Kim Sang-Woo,Kim Namil,Kim Sun-Ae,Suh Jae-Won,Ryu Heung-Cyoon 한국전자파학회 2005 한국전자파학회논문지 Vol.16 No.12

Multi-code code division multiple access(MC-CDMA) 시스템은 다수의 코드 사용으로 인한 용량의 증가를 통해 다양한 속도, 다양한 품질의 서비스를 제공할 수 있다는 장점을 갖는다 그러나, 여러 개의 코드들이 합쳐지면서 PAPR(Peak to Average Power Ratio)이 크게 증가되므로 비선형 왜곡에 의한 시스템 성능이 크게 저하되고, 이를 위해 HPA(High Power Amplifier)에서 많은 양의 back-off를 해야 하므로 큰 전력 손실이 나타난다. 본 논문에서는 들어오는 정보 데이터에 상응하는, 즉 입력 데이터의 상관 관계에 의한 constraint code의 삽입함으로써 PAPR을 효율적으로 낮출 수 있는 방법을 제안한다. PAPR 저감 효과는 사용된 constraint code의 길이와 index에 의존하며, PAPR 저감 효과와 constraint code의 길이 사이에 trade-off가 존재한다. HPA 및 AWGN 채널을 고려한 시뮬레이션 결과에서, 1) Input back-off 없이 가능한 모든 constraint code를 사용해 신호를 선택한 경우와 2) 약간의 input back-off와 몇 가지 constraint code만을 이용해 신호를 선택한 경우에서, BER성능이 선형 HPA를 사용한 OFDM의 성능과 거의 같게 나타남을 확인할 수 있다. Multi-code code division multiple access(MC-CDMA) has been proposed for providing the various service rates with different quality of service requirement by assigning multiple codes and increasing the capacity. However, it suffers from the serious problem of high peak to average power ratio(PAPR). So, it requires large input back-off, which causes poor power consumption in high power amplifier(HPA). In this paper, we propose a new method that can reduce PAPR efficiently by constraint codes based on the opposite correlation to the incoming information data in MC-CDMA. PAPR reduction depends on the length and indices of constraint codes in MC-CDMA system. There is a trade-off between PAPR reduction and the length of constraint codes. From the simulation results, we also investigate the BER improvement in AWGN channel with HPA. The simulation results show that BER performance can be similar with linear amplifier in two cases: 1) Using exact constraint codes without input back-off and 2) a few constraint codes with small input back-off.

MODIS 이미지를 이용한 지표특성에 따른 토양수분의 시·공간적 분포 특성

김상우,신용철,이태화,이상호,최경숙,박윤식,임경재,김종건,Kim, Sangwoo,Shin, Yongchul,Lee, Taehwa,Lee, Sang-Ho,Choi, Kyung-Sook,Park, Younshik,Lim, Kyoungjae,Kim, Jonggun 한국농공학회 2017 한국농공학회논문집 Vol.59 No.6

In this study, we analyzed the impacts of land surface characteristics on spatially and temporally distributed soil moisture values at the Yongdam and Soyang-river dam watersheds in 2014 and 2015. The soil moisture, NDVI (Normalized Difference Vegetation Index) and temperature values at the spatio-temporal scales were estimated using satellite-based MODIS (MODerate Resolution Imaging Spectroradiometer) products. Then the Pearson correlations between soil moisture and land surface characteristics (NDVI, temperature and DEM-digital elevation model) were estimated and analyzed, respectively. Overall, the monthly soil moisture values at the time step were highly influenced by the precipitation amounts. Also, the results showed that the soil moisture has the strong correlation with DEM while the temperature was inversely correlated with the soil moisture. However the monthly correlations between NDVI and soil moisture were highly varied along the time step. These findings indicated that water loss near the land surface are highly occurred by soil and plant activities as evapotranspiration and infiltration during the no/less precipitation period. But the high precipitation amounts reduce the impacts of land surface characteristics because of saturated condition of land surface. Thus these results demonstrated that soil moisture values are highly correlated with land surface characteristics. Our findings can be useful for water resources/environmental management, agricultural drought, etc.

나노제너레이터의 연구소개 및 최근 기술동향

김상우,김성수,윤홍준,류한준,Kim, Sang-Woo,Kim, Seongsu,Yoon, Hong Joon,Ryu, Hanjun 한국진공학회 2014 진공 이야기 Vol.1 No.4

Since recent electronics technologies have been developed and they tend to spend huge amount of electrical power, self-powered electronics have been paid attention worldwide. To realize self-powered electronics, energy harvesting technology, which generally converts ambient energy into electrical energy, has to be introduced. Among numerous energy sources, mechanical, thermal, and electrostatic event would be of broad interest in field of energy harvesting. Here, this article introduces the promising alternative energy concepts of nanogenerator including piezoelectric, triboelectric, and hybrid types. With these nanogenerators, we are able to apply onto not only self-powered system, but expect these open green energy market.

청보리 사일리지 및 목건초 급여가 엘크 사슴의 생산성 및 경제성에 미치는 영향

김상우,서상원,김동훈,김재환,김영신,김관우,윤세형,Kim, Sang Woo,Suh, Sang Won,Kim, Dong Hoon,Kim, Jae Hwan,Kim, Young Sin,Kim, Kwan Woo,Yoon, Sei Hyung 한국초지조사료학회 2013 한국초지조사료학회지 Vol.33 No.1

본 연구는 사슴의 조사료 원으로 엘크사슴에 대한 청보리 사일리지 급여가 사슴의 사료섭취량, 체중변화 및 경제성에 미치는 영향을 구명하기 위하여 실시하였다. 엘크사슴 21두를 공시하여 건초구, 청보리 사일리지구 및 건초+청보리 사일리지구로 나누어 농후사료를 3.7 kg 정량급여 하고 조사료는 자유채식 시켰으며, 그 결과는 다음과 같다. 엘크사슴의 일당증체량은 건초구, 청보리 사일리지구 및 건초+청보리 사일리지구 혼합구가 각각 0.26, 0.36 및 0.44 kg으로 건초+청보리 혼합구가 가장 높았고, 엘크사슴의 청보리 사일리지 일일섭취량은 6.25~9.00 kg (풍건) 범위였으며, DM 섭취량은 건초구, 건초+청보리 사일리지 혼합구 및 청보리 사일리지 순으로 높은 경향을 보였다. 녹용 생산량은 건초구, 청보리 사일리지구 및 건초+청보리 사일리지구가 각각 8,037, 7,713 및 8,585 g으로 건초+청보리 사일리지 혼합구가 가장 많았다. 3개 처리구간 일당증체량, 녹용생산량 및 사료섭취량은 사슴의 개체차가 심하여 통계적으로 유의성은 인정되지 않았지만(p>0.05) 증체량 및 녹용산량은 증가하는 경향을 보였다. 경제성 분석에서는 건초+청보리 사일리지 혼합구가 건초 및 청보리 사일리지 단독급여구보다 소득지수가 29~43% 높게 나타났다. 이상의 결과를 종합적으로 고려할 때 사슴의 조사료 원으로 청보리 사일리지는 기호성에서 건초를 대체할 만큼의 섭취량을 가지므로 이용가능성이 있었으며, 조사료 원으로 연중 공급이 가능하고, 경제적인 측면에서도 건초보다 유리하여 농가에서 사슴의 조사료 원으로 사용이 가능할 것으로 사료된다. 또한 청보리 사일리지 급여 시에는 청보리 사일리지 단독 급여보다는 청보리와 건초를 각각 50%씩 혼합 급여하는 것이 일당증체량, 증체, 녹용생산량 및 경제성에서 가장 바람직한 것으로 사료된다. This study was conducted to determine the effect of dietary whole-crop barley silage on the daily feed intake, daily weight gain, velvet antler yield and economic efficacy in elk during growth. A total of 21 elk (average BW 303 kg, 5 years old) were allotted randomly to three treatments. The three treatments were T1 (hay diet), T2 (whole-crop barley silage), and T3 (50% hay + 50% whole-crop barley silage). The average daily weight gain of T3 was higher than the others throughout the entire experimental period. The average daily feed intake of elk in decreasing order was as follows; T1>T3>T2. The velvet antler yield was higher in T3 group (8,585 g) compared with T1 (8,037 g) and T2 (7,713 g). However, there were no significant differences in the average daily feed intake, average daily weight gain, or velvet antler yield (p>0.05). In economic efficacy, T3 was gained about 29~43% more value than T1 or T2. In conclusion, the mixed feeding of 50% hay and 50% whole-crop barley silage was more effective than feeding hay of barley alone, in terms of average daily weight gain, velvet antler yield, and economic efficacy in elk.

동결 전 단계적 노출처리방법이 유리화동결 및 초급속동결-융해 후 생쥐 성숙난자의 생존력에 미치는 영향에 관한 연구

김상우,이재익,김미경,이영아,이규섭,윤만수,Kim, Sang-Woo,Lee, Jae-Ik,Kim, Mi-Kyung,Lee, Young-Ah,Lee, Kyu-Sup,Yoon, Man-Soo 대한생식의학회 2000 Clinical and Experimental Reproductive Medicine Vol.27 No.2

Objective: This study was carried out to compare the effects of the stepwise exposure treatments on the morphological normality, fertilization and blastocyst formation rate of the frozen-thawed mouse mature oocytes by vitrification or ultra-rapid freezing and to use as a fundamental data for the cryopreservation of human oocytes. Materials and Methods: The morphological normality and fertilization rates of the vitrified and ultra-rapid frozen mouse mature oocytes after three-stepwise exposure treatments (1step, 3step and 5step) were observed. After choosing the 3step exposure treatment groups, we observed the morphological normality and fertilization, blastocyst formation rate of the vitrified and ultra-rapid frozen mouse mature oocytes. Results: The morphological normality and fertilization rates of the vitrified mouse mature oocytes after three-stepwise exposure treatments (1step, 3step and 5step) were 75%, 85%, 88% and 58%, 61 %, 54% respectively. There were no significant differences among treatments(p>0.05). The morphological normality and fertilization rate of the control was 92% and 65%. There were no significant differences in fertilization rate among control and treatments (p>0.05). The morphological normality and fertilization rates of the ultra-rapid frozen mouse mature oocytes after three-stepwise exposure treatments (1step, 3step and 5step) were 83%, 83%, 84% and 75%, 63%, 56% respectively. There were no significant differences among treatments (p>0.05). The morphological normality and fertilization rate of the control was 95% and 67%. There were no significant differences among control and treatments (p>0.05). The morphological normality and fertilization rate of the vitrified or ultra-rapid frozen mouse mature oocytes after 3step exposure treatment were 69% and 75%, respectively. The blastocyst formation rate was 60% and 57%. The results did not differ significantly between vitrification and ultra-rapid freezing (p>0.05). Conclusion: As known in the above results, there were no significant differences in the fertilization and blastocyst formation rate of the frozen-thawed mouse mature oocytes by vitrification or ultra-rapid freezing among the control and treatments. It is suggested that vitrification and ultra-rapid freezing method were effective for the cryopreservation of mouse mature oocytes.