• 제목/요약/키워드: Gwangju region

검색결과 279건 처리시간 0.023초

An Assessment of the Usefulness of Time of Flight in Magnetic Resonance Angiography Covering the Aortic Arch

  • Yoo, Yeong-Jun;Choi, Sung-Hyun;Dong, Kyung-Rae;Ji, Yun-Sang;Choi, Ji-Won;Ryu, Jae-Kwang
    • 방사선산업학회지
    • /
    • 제12권4호
    • /
    • pp.325-332
    • /
    • 2018
  • Carotid angiography covering the aortic arch includes contrast-enhanced magnetic resonance angiography (CEA), which is applied to a large region and usually employs contrast media. However, the use of contrast media can be dangerous in infants, pregnant women, and patients with chronic renal failure (CRF). Follow-up patients informed of a lesion may also want to avoid constant exposure to contrast media. We aimed to apply time-of-flight (TOF) angiography to a large region and compare its usefulness with that of CEA. Ten patients (mean age, 58 years; range, 45~75 years) who visited our hospital for magnetic resonance angiography (MRA) participated in this study. A 3.0 Tesla Achieva magnetic resonance imaging (MRI) system (Philips, Netherland) and the SENSE NeuroVascular 16-channel coil were employed for both methods. Both methods were applied simultaneously to the same patient. Three TOF stacks were connected to cover the aortic arch through the circle of Willis, and CEA was applied in the same manner. For the quantitative assessment, the acquired images were used to set the regions of interest (ROIs) in the common carotid artery (CCA) bifurcation, internal carotid artery, external carotid artery, middle cerebral artery, and vertebral artery, and to obtain the signal-to-noise ratio (SNR) and the contrast-to-noise ratio (CNR) for the soft tissues. Three radiologists and one radiological resident performed the qualitative assessment on a 5-point scale - 1 point, "very bad"; 2 points, "bad"; 3 points, "average"; 4 points, "good"; and 5 points, "very good" - with regard to 4 items: (1) sharpness, (2) distortion, (3) vein contamination, and (4) expression of peripheral vessels. For the quantitative assessment, we estimated the mean SNR and CNR in each of the 5 ROIs. In general, the mean SNR was higher in TOF angiography (166.1, 205.2, 154.39, 172.23, and 161.95) than in CEA(92.05, 95.43, 84.76, 73.69, and 88.3). Both methods had a similar mean CNR: 67.62, 106.71, 55.9, 73.74, and 63.46 for TOF angiography, and 67.82, 71.19, 60.52, 49.45, and 64.07 for CEA. In all ROIs, the mean SNR was statistically significant (p<0.05), whereas the mean CNR was insignificant (p>0.05). The mean values of TOF angiography and CEA for each item in the qualitative assessment were 4.2 and 4.28, respectively for item 1; 2.93 and 4.55, respectively, for item 2; 4.6 and 3.13, respectively, for item 3; and 2.88 and 4.65, respectively, for item 4. Therefore, TOF angiography had a higher mean for item 3, and CEA had a higher mean for items 2 and 4; there was no significant difference between the two methods for item 1. The results for item 1 were statistically insignificant (p>0.05), whereas the results for items 2~4 were statistically significant (p<0.05). Both methods have advantages and disadvantages and they complement each other. However, CEA is usually applied to a large region covering the aortic arch. Time-of-flight angiography may be useful for people such as infants, pregnant women, CRF patients, and followup patients for whom the use of contrast media can be dangerous or unnecessary, depending on the circumstance.

일일 인구이동으로 본 국토공간의 도시체계 변화: 2005년과 2012년 (The Changes of Urban System Reflected in Daily Movement: 2005-2012)

  • 손승호
    • 대한지리학회지
    • /
    • 제50권2호
    • /
    • pp.203-216
    • /
    • 2015
  • 본 연구는 일일 인구이동에 의한 네트워크와 유동패턴을 통해 한국의 도시체계 변화를 고찰하였다. 일일 인구이동이 일상적인 통행패턴을 반영하므로, 도시간 연결관계에 의한 도시체계는 생활권의 관점으로 인식할 수 있다. 2012년 들어 도시간 인구이동이 증가하면서, 도시 네트워크의 연결체계를 비롯하여 출발지와 도착지로 구성되는 통행권의 수가 모두 증가하였다. 통행량의 분산에도 불구하고 서울을 중심으로 하는 수도권과 부산을 중심으로 하는 부산권의 공간범위는 확대되었다. 서울지향형 고속교통망이 구축된 강원도에서는 춘천을 중심으로 하는 소양강문화권과 영동지방의 생활권 분리가 심화되었다. 교통망의 접근성이 양호한 대전과 그 주변지역을 아우르는 생활권은 경기남부까지 확대되었다. 전남에 형성된 기존의 생활권은 광주의 중심성이 약화되면서 목포와 순천을 중심으로 서부와 동부에서 분절되었다. 생활권은 거시적으로 광역 행정경계와 대체로 일치하였지만, 도 경계를 넘어 다른 광역단체의 시군과 통합되는 사례가 증가하였다. 서울과 그 주변 도시간의 상호작용이 강화된 것은 서울을 중심으로 하는 세계도시-지역의 발전 가능성을 높여준다.

  • PDF

황사 발원지에서 선포토미터를 활용한 에어로졸의 광학적 특성 산출과 미세먼지속 황사구분 (Aerosol Optical Properties Retrieval and Separation of Asian Dust using AERONET Sun/Sky Radiometer Measurement at the Asian Dust Source Region)

  • 신동호;노영민
    • 대한원격탐사학회지
    • /
    • 제32권3호
    • /
    • pp.245-251
    • /
    • 2016
  • 황사의 주요 발원지인 중국 북부 둔황지역에 선포토미터를 설치하여 440, 675, 870 그리고 1020 nm 채널에서 황사의 파장별 입자편광소멸도를 산출하였다. 이와 함께 발원한 황사가 장거리 수송과정에 위치한 제주 고산과 일본 오사카에 설치된 선포토미터를 함께 분석하였다. 황사 발원지에서 1020 nm 파장에서 입자편광소멸도가 0.34로 가장 높은 수치를 보였다. 또한, 초미세먼지농도가 증가하는 경우 입자편광소멸도는 감소하는 경향을 보였다. 우리는 본 연구에서 선포토미터의 입자편광소멸도 산출을 통해 에어로졸에서 황사의 구성 비율이 변화함을 확인하였다.

와이블데이터를 이용한 소형풍력발전기 출력에 대한 평가 (Evaluating the Output of Small-size Wind Power Generators Using Weibull Data)

  • 유기표;김영문
    • 한국태양에너지학회 논문집
    • /
    • 제32권2호
    • /
    • pp.95-104
    • /
    • 2012
  • This study purposed to predict wind energy for small size wind power generators at 50m above the ground in each area using mean wind speed data for 10 minutes collected from 2001 to 2011 by meteorological data in large cities having over 60% of 15 story (50m) or higher apartments including Seoul, Daejeon, Gwangju and Daegu representing the inland region, and Busan, Incheon and Ulsan representing the coastal region. In the results of analysis, we confirmed close agree ment between observatory weather data and probability density distribution obtained using Weibull's parameters, and this suggests that Weibull's parameter is applicable to the estimation of wind energy. Hourly output energy using the mean wind speed for 10 minutes and output energy obtained from Weibull's parameter showed an error less than 5%, and thus it was found that wind energy can be evaluated using Weibull's modulus.

세계도시지역론과 그 지역정책적 함의 (Global City-Regions Theory and its Implications for Regional Development Policy in Korea)

  • 이재하
    • 대한지리학회지
    • /
    • 제38권4호
    • /
    • pp.562-574
    • /
    • 2003
  • 이 연구는 아주 최근에 새롭게 제기된 세계도시지역론을 고찰하고 이에 기초하여 한국의 지역발전 정책을 위한 함의를 제안하고 있다. 세계의 주요한 거대도시지역으로. 이루어진 정치ㆍ경제적 조직체 또는 다중심적 구조를 지닌 새로운 규모의 도시조직으로 정의되는 세계도시지역은 세계경제의 역동적인 성장뿐만 아니라 지역발전도 동시에 유발함으로써 세계화시대에서 대안적인 신지역주기 발전모델로 평가된다. 한국에서 세계도시지역모델의 정책적 적용은 특히, 비수도권의 거대도시지역의 세계적 경쟁력 강화와 수도권과 비수도권 간의 극심한 지역격차를 완화하기 위해서 필요시 된다. 그러나 부산, 대구, 광주, 대전 등의 비수도권의 광역시가 세계도시지역으로 발전하기 위해서는 시ㆍ도 통합과 지방분권과 같은 제도개혁이 선행되지 않으면 안 된다.

계절과 서식지 유형에 따른 국내 Eurasian otter (Lutra lutra)의 스트레스 반응 (Stress Responses of Eurasian Otter (Lutra lutra) in Relation to Habitats and Season)

  • 이건주;조현진;나정은;장재민;장진우;이학영
    • 생태와환경
    • /
    • 제53권1호
    • /
    • pp.80-90
    • /
    • 2020
  • In order to understand the stress responses, we measured the concentration of stress hormones by using the fresh feces of wild otters in the Gwangju stream and Seomjin river during summer and winter in 2018. We compared seasonal and regional number of spraints (=otters' feces), temperature, altitude, water width, land cover, and water quality with stress hormones. The stress hormone levels were higher in summer than in winter, and significantly different to season and region. In addition, the number of feces were different according to the season and region, and showed a negative correlation with stress hormone. This study suggested assessing stress hormones as another promising method for the analysis of status of wild otters and it will contribute to establish the management and conservation policy, especially in urban area.

지역별 기상조건과 급수온도에 따른 태양열 온수공급 시스템 성능에 관한 연구 (A Study on Performance of Solar Thermal System for Domestic Hot Water According to the Weather Conditions and Feedwater Temperatures at Different Locations in Korea)

  • 손진국
    • 한국태양에너지학회 논문집
    • /
    • 제39권6호
    • /
    • pp.41-54
    • /
    • 2019
  • The purpose of this study is to analyze the performance of solar thermal system according to regional weather conditions and feedwater temperature. The performance analysis of the system was carried out for the annual and winter periods in terms of solar fraction, collector efficiency and it's optimal degree. The system is simulated using TRNSYS program for 6 cities, Seoul, Incheon, Gangneung, Mokpo, Gwangju, and Ulsan. Simulation results prove that the solar fraction of the system varies greatly from region to region, depending on weather conditions and feedwater temperatures. Monthly average solar fraction for winter season from November to February, a time when heat energy is most required, indicated that the highest is 73.6% in Gangnueng and the lowest is 56.9% in Seoul. This is about 30% relative difference between the two cities. On the other hand, the collector efficiency of the system for all six cities was analyzed in the range between 40% and 42%, indicating small difference compare to the solar fraction. The annual average solar fraction is rated the highest at 40 collector degree, while monthly average solar fraction during winter season is rated at 60 degree.

Fabrication and Characterization of N×N Plastic Optical Fiber Star Coupler based on Fused Combining

  • Kim, Kwang Taek;Lee, Byeong Ha;Lee, Cherl-Hee;Lee, Jonghun
    • 한국광학회지
    • /
    • 제24권1호
    • /
    • pp.17-22
    • /
    • 2013
  • High performance plastic optical fiber (POF) $N{\times}N$ star couplers are implemented based on fusing and combining technology. A set of cladding-removed POFs are fused into a solid body by heating and pressing them together to form the transition region between the input and output sides. The operation principle of the proposed star coupler is explained based on ray optics. To demonstrate the performance of the device, $2{\times}2$, $4{\times}4$ and $6{\times}6$ type POF couplers were fabricated and characterized. Performances of the POF star couplers were evaluated in terms of the flatness of the coupling ratios and excess losses.

Solution-Derived Amorphous Yttrium Gallium Oxide Thin Films for Liquid Crystal Alignment Layers

  • Oh, Byeong-Yun
    • Transactions on Electrical and Electronic Materials
    • /
    • 제17권2호
    • /
    • pp.109-112
    • /
    • 2016
  • We demonstrated an alternative electrically controlled birefringence liquid crystal (ECB-LC) system with ion beam (IB)-irradiated yttrium gallium oxide (YGaO) alignment films using a sol-gel process. The surface roughness of the films was dependent on the annealing temperature; aggregated particles on surface were observed at lower annealing temperatures, whereas a smooth surface could be obtained with higher annealing temperatures. Higher transmittance in the visible region was observed at higher annealing temperatures. The film had an amorphous crystallographic state irrespective of the annealing temperature. Furthermore, ECB-LC cell with our IB-irradiated YGaO film yielded faster response time when compared to ECB-LC cell with rubbed polyimide. Considering the fast response time and high transmittance, the IB-irradiated YGaO-base LC system is a powerful alternative application for the liquid crystal display industry.

푸른들영농조합의 친환경농산물 유통실태와 발전과제 (Marketing Issues of Pureundeul Farming Corporation at Asan City)

  • 김호;윤종열
    • 한국유기농업학회지
    • /
    • 제13권1호
    • /
    • pp.69-84
    • /
    • 2005
  • Pureundeul fanning corporation(PFC) is an cgmplary body of all producer organizations for environmentally friendly agriculture(EFA) in Korea. It is located at Asan in Chungnam and has 301 farmers. They attained more than 10 billion wons as a sale in 2004. And The direct marketing channel of the EFA products is the second logistics center(Asan) ${\to}$ the first logistics center(Gwangju Gyunggi) ${\to}$ local hansalim shops ${\to}$ consumers. It is needed to construct the system of the direct marketing as follows : First, it needs to construct the direct marketing system within the region for EFA products of Asan. Second, the direct shop and suppling area should be enlarged as a way to promote sales with the demand increase of EFA products. Third, an aggressive promotion campaign is be needed for increasing motivation of consumption and understanding of EFA products.

  • PDF