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        검색결과 1,061

        781.
        2020.04 KCI 등재 SCOPUS 서비스 종료(열람 제한)
        The main objective of this research is to investigate the impact of board size and board composition on financial performance of banks. The sample of this study consists on two countries listed bank sector Pakistan and China. The annul data is used from 2009-2018 to find the objective of this study. The Panel regression model is used to check the relationship between dependent and independent variables. Return on Asset and Return on Equity is used as performance checker dependent variables. The results of this study confirm board size coefficient value positive for ROA and negative for ROE but shows insignificant behavior for Pakistani banking sector while in Chinese banking sector the coefficient value of board size positively for ROA and ROE at 10% level. The board composition coefficient shows the negatively significant with ROA but insignificantly related to ROE for Pakistani banking sector. However, in Chinese banking sector the coefficient value of board composition is insignificant for both ROA and ROE. This study is helpful for banks, management of banks, policy makers, researcher as well as Government.
        782.
        2020.01 KCI 등재 서비스 종료(열람 제한)
        To determine the size distributions of water-soluble inorganic ionic species (WSIS) in roadside aerosols, sampling experiments were carried out in the urban roadside area of Jeju City on August 2018 and January 2019 by using the eight-stage cascade impactor sampler. The mass of roadside aerosols were partitioned at 57% in fine fraction, 36-37% in coarse fraction, and 6-7% in giant fraction, regardless of summer and winter. The mass concentrations of WSIS except for Na+ and SO42- in roadside aerosols were higher in winter than in summer. The size distributions of Na+, Mg2+, Ca2+ and Cl- were characterized by bimodal types with coarse particle mode peaking around 3.3-4.7㎛ and 5.8-9.0㎛ . The size distributions of NO3 - and K+ shifted from a single fine mode peaking around 0.7-1.1㎛ in winter to bimodal and/or trimodal types with peaks around coarse mode in summer. SO4 2- and NH4 + showed a single fine mode peaking around 0.7-1.1㎛ . The MMAD of roadside aerosols was lower than that of Na+, Mg2+, Ca2+ and Cl-. Based on the marine enrichment factors and the ratio values of WSIS and the corresponding value for sea water, the composition of roadside aerosols in Jeju City may be practically affected by terrestrial sources rather than marine source.
        783.
        2019.11 KCI 등재 서비스 종료(열람 제한)
        본 연구는 전기비저항 측정시 실험체 크기에 따른 영향에 대해 비저항추정모델을 이용한 해석적 검토를 목적으로 한다. 실험에서는 콘크리트 실험체를 제작하여 전극 간격별 겉보기 비저항 측정하였다. 측정된 겉보기 비저항은 실험체 크기가 작아지고 외측(가장자리)에 가까울수록 겉보기 비저항치의 왜곡현상이 심해진다는 것을 확인할 수 있었다. 측정치와 해석치의 비교·분석 결과, 실험체 크기의 영향성 검토에 REM이 활용될 수 있을 것으로 기대된다.
        784.
        2019.10 KCI 등재 서비스 종료(열람 제한)
        본 연구의 목적은 컴퓨터단층 혈관조영술에서 혈관 직경을 정확하게 측정할 수 있는 새로운 측정 방법 인 상대적 측정법의 기초연구 자료를 제공하고자 한다. 비이온성 요오드 조영제를 자체 제작한 관류 팬텀에 일정한 속도로 흐르게 한 후 컴퓨터단층 혈관조영술 검사를 시행하였다. 원시 데이터를 얻은 후 다중평 면재구성 및 최대강도투사법으로 영상을 재구성하였고 장비사에서 제공하는 거리측정 장치를 사용하여 팬텀의 직경을 측정하였다. 측정법은 고식적 측정법과 본 연구에서 제안하는 상대적 측정법을 사용하였다. 관류팬텀의 평균 직경은 다중평면재구성기법과 최대강도투사법 모두에서 상대적 측정법이 기존 측정법 보다 실측에 더 가깝게 나타났다(34% VS 24%, p<0.05). 하지만 두 가지 측정법 모두 실측보다 여전히 확대된 결과를 나타내고 있음을 확인하였다. 따라서 상대적 측정 방법에 대한 추가 연구가 필요한 실정이며, 이에 본 연구가 기초 자료를 제공할 수 있을 것이라 사료된다.
        785.
        2019.10 서비스 종료(열람 제한)
        온실 가스의 대부분을 차지하는 이산화 탄소는 시멘트 제조과정에서 많이 발생한다. 최근에 배출된 이산화 탄소를 활용하기 위한 방안으로 탄산화 양생 기법이 연구 중이다. 탄산화 양생은 굳지않은 콘크리트의 초기 강도 발현을 급속으로 증진 시킨다. 본 연구에선 탄산화 양생의 효율을 높이고 정량적으로 평가를 하였다. (1) 압력 챔버 내 시편에 이산화 탄소를 350 kPa로 가압하여 양생하는 방법, (2) 챔버 내 시편을 이산화 탄소 농도 20%와 상대습도 75±5%의 조건에서 양생하는 방법을 활용하였다. (1)번 양생 기법에서 이산화 탄소 압력 감소량을 모니터링하여 반응한 이산화 탄소 양을 정량적으로 평가하였다. 또한, 시편을 크기별로 달리하여 탄산화 양생이 미치는 영향을 평가하였다.
        786.
        2019.10 서비스 종료(열람 제한)
        본 연구는 철근 콘크리트 내 강제 부식된 철근의 단조가력(Monotonic loading) 부착성능을 파악하고, 추후 해석모델 검증을 위한 데이터를 확보하기 위한 것이다. 이를 위해 이전 연도에 진행된 연구(철근 콘크리트의 가속 부식 실험 방법 정립 및 부식 특성 분석)를 바탕으로 제작된 철근 콘크리트 부재의 부식이 진행되었다. 철근의 직경, 철근 부식도, 콘크리트 압축 강도가 실험 변수로 지정되었고, 선행 연구를 바탕으로 자체 제작한 인발 시험기를 활용하여 실험 변수에 따른 철근의 콘크리트 인발 거동을 실험하였다.
        787.
        2019.05 KCI 등재 서비스 종료(열람 제한)
        본 연구는 콘크리트 내부 공극 및 계면 사이에 깊게 침투가 가능한 실란복합화합물을 기반으로한 표면보호재 (Silane Surface Protection Material, SSPM)를 사용한 기존 콘크리트 내구성 향상 방안 도출을 위해 실시되었다. SSPM을 적용한 모르타르의 미세구조 평가, 잔골재의 입도 분포에 따른 침투깊이 및 공극량을 측정하였다. 그 결과 모르타르 내부에 액상 및 크림형질의 SSPM이 침투된 것으로 나타났으며, 공극량 평가결과 잔골재의 입도분포에 관계없이 SSPM을 적용하였을 때 공극량이 감소하는 것으로 나타났다. 침투깊이 평가결과 잔골재의 입도분포에 관계없이 SSPM 도포량이 증가함에 따라 침투깊이가 증가하는 것으로 나타났으며, 공극량이 상대적으로 많은 일반잔골재(Type 2)로 제작한 모르타르의 침투깊이가 적게 나타났다. 콘크리트에 적용할 경우 침투깊이는 다소 감소할 것으로 판단되나, 콘크리트 표면에 침투하여 내구성을 향상 시길 수 있을 것으로 판단된다.
        788.
        2019.04 서비스 종료(열람 제한)
        This study investigated the damping properties of preplaced concrete with W/C and coarse aggregate size was . Experimental results show that the damping ratio of the C40 is 2.63%, which is 1.72 times higher than the damping ratio of the C30 of 1.53%. The higher the water cement ratio, the higher the damping ratio is. In addition, the damping ratio of the C-PA series is reduced by 17% to 60% as compared with the C-series. The difference of the damping ratio due to the coarse aggregate size in the C-PA series was found to be within the standard deviation
        789.
        2019.04 서비스 종료(열람 제한)
        The core is extracted to evaluate the concrete compressive strength of the actual structure. However, the core strength can vary in the core size due to two reasons - size effect in fracture mechanics and effect of coring damage. Therefore, the purpose of this study was to assess quantitatively the difference in strength due to these effects. The core damage tended to increase relatively as the core section was smaller. The strength difference due to the size effect in fracture mechanics did not show any significant difference according to the curing condition and was measured to be similar to the previous study.
        790.
        2019.04 서비스 종료(열람 제한)
        This paper presents an automated determination technique of optimal subset sizes for digital image correlation (DIC) analysis of speckle patterned images. The smaller subset size would typically have the higher DIC accuracy with respect to local minute deformation, but insufficient speckle pattern information within the excessively small often augment DIC errors due to lack of correlation features. Therefore, optimal subset size determination is crucial for the precise DIC analysis. To automate the optimal subset size determination process, first, the reference and test speckle pattern images are obtained from the target structure surface with a certain time interval. Then, an initial seed point which will be used for the subset center point is assigned on the reference speckle pattern image. Subsequently, normalized cross correlation (NCC) between the reference and test images is performed by increasing subset sizes from the seed point. Next, the matching distance between the two images is calculated using the maximum correlation coefficient. As the subset size increases, the matching distance between the two subsets converges a certain value. It physically means that the sufficient correlation features will be included in the subset. Finally, the optimal subset size can be determined by selecting the minimum subset size where the matching distance value starts to be converged. The proposed technique is experimentally validated using an aluminium plate with sprayed speckle pattern.
        791.
        2019.03 KCI 등재 서비스 종료(열람 제한)
        To analyze main factors of size planning of community facilities that were created as part of development of a rural area, the present condition of factors deciding size of community facilities was analyzed, factors that influence size planning by the type of community facility were drawn with Delphi anaysis. The results of analyzing the present condition of size planning factors of community facilities show that facilities have been generally planned as multi-purpose and multi-functional facilities. And on the basis of the purpose of facilities, their functions and organization, and their operation programs, facilities are classified into community-centered, agritourism-centered, and combined ones. Using Delphi analysis, major factors that could affect size planning of community facilities were drawn on 26 community-centered, 28 agritourism-centered, and 30 combined. And the factors tended not to be applied well for size planning of community facilities.
        792.
        2019.03 KCI 등재 서비스 종료(열람 제한)
        본 논문에서는 노후된 중소규모 RC슬래브 교량에 대한 응답계수를 분석하였다. 이 응답계수는 진동수 기반 교량의 내하력 예측 모델에서 중요한 변수이며, 정적 및 동적 응답계수로 구성되어 있다. 정적 및 동적 응답계수는 교량의 현재와 이전(또는 설계) 상태의 진동수 변화와 충격 계수 변화에 따라 각각 결정된다. 여기서 충격계수 변화는 충격계수 응답스펙트럼에서 교량의 고유진동수에 따라 산출된다. 본 연구에서 고려한 총 4개의 대상교량은 지간길이가 12 m이고 시공 후 30년 이상 된 RC슬래브 노후 교량이다. 진동수 분석을 위해 덤프 트럭을 이용한 현장 동적 재하시험과 설계기반 FE모델을 이용한 고유치 해석을 통해 교량의 현재 및 설계 상태의 고유 진동수를 각각 도출하였다. 충격계수 응답스펙트럼 개발에 있어서 좀 더 현실적인 조건을 반영하기 위해 3축이동하중과 단순지지 및 양단고정 조건을 고려하였다. 분석 결과 응답계수는 0.21에서 0.91까지 광범위하게 분포하였고, 정적 응답계수가 총 응답계수 결과에 크게 기여한 반면 동적 응답계수는 결과에 작은 영향을 미쳤다. 1축 이동하중과 단순지지 조건에서의 응답계수와 비교해 보았을 때 최대 오차는 약 3%미만으로 매우 작게 나타났다.
        793.
        2018.12 KCI 등재 서비스 종료(열람 제한)
        본 연구에서는 2015년에서 2017년 사이에 유럽항공우주국 Sentinel-1 위성이 촬영한 Synthetic Aperture Radar (SAR) 영상을 활용하여 한강 유역 내 하천의 유량을 추정하는 모형을 개발하였다. 한강 유역 내 15개 중소규모 하천을 연구지역으로 선정하였으며 SAR 인공위성 영상 자료와 수위 및 유량관측소에서 산정한 유량 자료를 모형 구축을 위하여 사용하였다. 우선, 오류 보정을 위해 다양한 전처리 과정을 거친 12장의 SAR 영상 을 히스토그램 매칭 기법을 적용하여 이미지의 밝기 분포를 동일하게 만들었다. 이후 임계치 분류방식을 사용하여 추출된 하천 수체의 면적과 지상 관측유량자료와의 관계식을 도출하여 유량추정모형을 구축하였다. 그 결과, 1개소를 제외한 14개 관측소에서 인공위성에서 추출한 하천 면적을 입력 자료로 하는 멱함수 형태의 유량추정모형을 구축할 수 있었다. 14개 관측소의 최소, 평균, 최대 결정 계수(R2)는 0.3, 0.8, 0.99로 나타났다.
        794.
        2018.11 KCI 등재 서비스 종료(열람 제한)
        본 연구에서는 전기비저항에 대한 실험실 레벨의 측정에서 실험체 크기가 겉보기 비저항에 미치는 영향에 대해 검토하였다. 실험은 실험체의 측변과 높이가 다른 실험체를 제작하여 겉보기 비저항을 측정하였다. 실험결과, 실험체의 측변과 높이이 작을수록 겉보기 비저항이 크게 나타났다. 또한 전기비저항 측정에 미치는 실험체 크기의 영향은 선형적으로 나타나지 않음을 확인하였다.
        795.
        2018.10 서비스 종료(열람 제한)
        Background : The Kenaf (Hibiscus cannabinus L.) is an annual plant rich in phenolics compound and antioxidant activity. Particle size has an enormous effect on extraction of plant bioactive compound. Therefore, to evaluate the optimum particle size on extraction of bioactive compound from Kenaf was investigated. Methods and Results : Three kind of kenaf leaves; EF-1 and G-1 from Israel and Korea were collected in 2016 and the collected leaves were dried and pulverized are sorted by particle size. After adding 50 ㎖ of 100% ethanol per 0.5 ㎎ of the powder, the powder is extracted in an ultrasonic bath at 30℃ for 1 hour and then stirred for 1 hour at 250 rpm in the wise stirring. After extraction, the extract was filtered using filter paper. In the total polyphenol, flavonoid and antioxidant activity were higher in 100 to 200 ㎛ particle size of Gandae. On the other hand, phenolic compound, falvonoud and antioxidant were higher in 45 to 100 ㎛ particle size of EF-1 and G-1 Kenaf. Conclusion : Based on the results, the Israel varieties showed the best results compared to the Kenaf varieties of Korea. Among them, EF-1 had a particle size of 45 – 100 ㎛ Showed the higher antioxidant activity. It is believed that the smaller the particle size, the larger the specific surface area, which leads to an increase in the extraction efficiency of kenaf.
        796.
        2018.10 KCI 등재 서비스 종료(열람 제한)
        바둑은 최상의 착점을 찾기 위해 컴퓨터가 완전탐색을 하여 모든 가능한 착점들을 탐색할 수 없는 가장 복잡한 보드게임이다. AlphaGo 이전에 모든 강력한 컴퓨터바둑 프로그램들은 게임트리 내 매우 큰 분기수와 국면평가에서의 어려움을 극복하기 위해 몬테카를로 트리탐색(Monte-Carlo Tree Search)을 사용해 왔다. 본 논문에서는 MCTS를 활용하여 초소형 바둑에서의 최상의 수순과 덤의 크기를 알고자 했다. 2줄바둑에서의 게임결과는 빅이 되었으며 덤의 크기는 0집, 반면에 3줄바둑에서는 흑이 항상 승리하고 덤의 크기는 9집이 되어야 함을 알아냈다.
        797.
        2018.10 서비스 종료(열람 제한)
        Background : This study was carried out to introduce Atractylodes macrocephala as a new income element in Gangwon area and to develop the technology necessary for stable quality seedling production. Methods and Results : For the production of high quality seedlings of Atractylodes macrocephala, seedling growth characteristics were investigated according to the types of plug cell size and seedling raising period. Atractylodes macrocephala seeds were sown on February 14, 2018 in 72, 105, 128, 162, and 200 plug trays. The emergence period after sowing was March 2, and the final occurrence rate was 76.6 - 79.5%. The number of days of emergence took 18 to 20 days from sowing date. Growth of seedlings tended to be better with less number of plug trays, such as seedling height, seedling width, leaf length, leaf width and leaf number. On the other hand, roots (net formation) increased rapidly as the number of plug trays increased. After 60 days, the matured seedling rate was good at 75.5 ± 8.4% for the 200 plug tray and 72.5 ± 4.1% for the 162 plug tray. The net formation ratio of matured seedling was the best in 60 days of seeding in 162 plug trays. The rooting rate was 98.0 ± 2.1 - 99.3 ± 1.2% when seeded for 60 days or more regardless of the type of plug tray. Conclusion : In order to produce efficient and stable seedlings in the cultivation of Atractylodes macrocephala in Gangwon area, it was considered to be advantageous for 60 days of seedling settling in the plug trays of more than 162 and less than 200.
        798.
        2018.10 서비스 종료(열람 제한)
        The study was conducted to evaluate the penetration performance of Surface Protection Material(SPM) according to the particle size distribution of fine aggregate. The fine three types of aggregates were used, and the amounts of SPM were applied 0.13, 0.25, 0.36, and 0.51 kg/㎡. Test results indicated that the penetration depth of SPM were improved with increasing the amounts of application of SPM. And The penetration depth of SPM were improved with increasing the percentage of passing weight of size of sieve between 0 and 1.25mm.
        799.
        2018.06 KCI 등재 서비스 종료(열람 제한)
        To investigate the distribution characteristics of grain size and organic matter of surface sediments from the Nakdong-Goryeong Mid-watershed, surface sediments were collected and analyzed. The samples were collected from six sited at four different times between May 2013 and May 2014. The were analyzed for grain size, water content, ignition loss, chemical oxygen demand, total organic carbon and total nitrogen. The surface sediments were mainly composed of medium sand (mean 44.7%) and coarse sand (mean 32.8%) and became coarser in May 2014. Fine sediments at the site NG-2 were poorly sorted and positively skewed, and occur in a tributary environment that is relatively low-energy compared with the other sites. The water content at the studied sites (15.3 ~ 34.9%) averaged 20.25%, and ignition loss (0.4 ~ 5.8%) and total nitrogen (274 ~ 2493 mg/kg) averaged 1.33% and, 696 mg/kg, respectively. These values indicated that the sediments were not seriously contaminated when compared with the sediment pollution evaluation standard of the National Institute of Environmental Research. The chemical oxygen demand (mean 0.17%) was at the non-polluted level compared with United States Environmental Protection Agency sediment quality standards. The total organic carbon (mean 0.18%) at all sites except site NG-2 (lowest effect level) was the no effect level of the Ontario sediment quality guidelines. The COD/IL (0.02 ~ 0.20) and C/N (0.73 ~ 6.76) were less than 1 and 10, respectively. Organic matter in the study area produced naturally from aquatic organisms. Results of principal component analysis showed that fine sediments (very fine sand and silt) were significantly affected by organic matters (ignition loss, chemical oxygen demand, total organic carbon and total nitrogen). In addition, the highest organic matters content in the study area occurred at the site with the finest sediments (NG-2).
        800.
        2018.05 서비스 종료(열람 제한)
        Background : Seed germination for Adenophora triphylla var. japonica Hara. is not good when grown in direct seeding. This experiment was conducted to identify seedling box suitable for seedling transplantation and cultivation to improve farm income and public health. Methods and Result : To investigate the effect on growth, sizes of seedling box used were as follows (width × length × height, in ㎝); 2.5 × 2.5 × 4 (custom), 4 × 4 × 4, 4.5 × 4.5 × 6, 5.0 × 5 × 9.6, 5 × 5 × 11.2, 5 × 5 × 17, and for sowing in narrow strips; 33.5 × 55 × 13, 33.5 × 49 × 23, 33.5 × 49 × 30. The weight of the ground part decreased as box height became lower, highest at 17 ㎝ tall (0.65 g) and lowest at 4 ㎝ (0.23 g). In terms of root length of the seedlings, the longest was 9.0 - 9.3 ㎝ at box height of 17 ㎝ and decreased as height decreased. Root weight increased as box height decreased, the highest at 4 ㎝. After the seedlings were planted, more than 90% survived in seedling box compared to the 50% rooting rate on sown in narrow strips where root net formation did not occur. During harvesting period, plant height was 15.8 - 17.5 ㎝ with a shoot diameter of 13.3 - 20.7 ㎜, leaf length of 5.6 - 7.9 ㎝ and leaf numbers 15.6 - 22.3. Moreover, leaf width was the widest at 8.6 ㎝ at 6 ㎝ box height while dry weight was the most at 6.7 g at 11.2 ㎝. Survival rate and growth characteristics of the ground part were lower in seedling box for sowing in narrow strips. For the underground characteristics, root number increased as box height decreased while dry weight increased as box height increased, with 1.7 - 3.5 and 6.2 - 6.8 less in seedling box for sowing in narrow strips, respectively. The yield in a 17 ㎝ high seedling box was 152 ㎏ per 10 a, 16% higher than conventional level, and decreased as box height decreased. Conclusion : These results suggest that the optimum seedling box height is 11.2 - 17 ㎝ to have lower root numbers and higher dry weight and yield.