• 천문학회보
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• 제37권2호
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• pp.131.1-131.1
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• 2012

We use three-dimensional magnetohydrodynamic (MHD) simulations of flux emergence from solar subsurface to corona. In our previous work, we reported the relation between magnetic-field configuration and the flux expansion factor. Following these results, we investigate where an upflow is generated in an active region and how its location is related to the flux expansion factor. We also derive physical quantities of a real active region from observation data provided by Nobeyama Radioheliograph (NoRH), X-Ray Telescope (XRT), and Extreme Ultraviolet Imaging Spectrometer (EIS) onboard Hinode. These physical quantities are plasma density, temperature and flow. By comparing the simulation result and observational one, we will discuss the properties of the location producing a solar wind.

• Smart Structures and Systems
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• 제22권6호
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• pp.643-662
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• 2018

One of the methods for investigation of mechanical behavior of materials is numerical simulation. For simulation, its need to model behavior is close to real condition. PFC is one of the rock mechanics software that needs calibration for models simulation. The calibration was performed based on simulation of unconfined compression test and Brazilian test. Indeed the micro parameter of models change so that the UCS and Brazilian test results in numerical simulation be close to experimental one. In this paper, the effect of four micro parameters has been investigated on the uniaxial compression test and Brazilian test. These micro parameters are friction angle, Accumulation factor, expansion coefficient and disc distance. The results show that these micro parameters affect the failure pattern in UCS and Brazilian test. Also compressive strength and tensile strength are controlled by failure pattern.

• 한국환경보건학회지
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• 제24권1호
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• pp.38-46
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• 1998

This study was to investigate the effects of carbon loadings, temperature and expansion ratio on the waterborne organic removal by the biologically active GAC fluidized bed on a laboratory scale. The raw water to be treated comes from midstream of Han river. BACFB(Biological Activated Carbon Fluidized Bed) process was very effective to remove the biodegradable fraction of dissolved organic matter. The more carbon weighed, the more DOC removed in a range from 16.7 to 133.3 g/l. DOC and UV$_{254}$ were removed more than 40% and 20% above 20$\circ$C respectively. Between 5$\circ$C and 10$\circ$C, DOC and UV$_{254}$ were eliminated about 30% and 15% respectively. In general, even if the temperature was higher, DOC removal was a little sensitive, probably influenced by GAC's residual adsorption capacity. UV$_{254}$ reduction was little fluctuated in accordance with water temperature. The gradual increase in expansion ratio from 10% to 75% didn't greatly affect on the removal of DOC and UV$_{254}$. The expansion ratio, therefore, is not a key factor over the critical expansion ratio.

• 농촌계획
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• 제10권3호
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• pp.41-51
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• 2004

This study aims to develop a potential evaluation method for urban spatial expansion using remote sensing (RS) and geographic information system (GIS). A multi-criteria evaluation method with several criteria and their weighting values was introduced to evaluate the score and quantification of the potential surface around the existing cities. The six criteria with one geographic factor, slope, and five accessibility factors, time distance from center of the city, national road, interchange of expressway, a big city, and station, were defined for the potential. RS techniques were applied for classification of the actual urban expansion maps between two periods, and GIS functions were used for score of accessibility criteria with a distance decay function from geographic, road and several point maps, which was developed in this study. The new methodology was applied to a test area, Suwon, between 1986 and 1996. In order to optimize the six weighting values, this study made new findings to search the optimal combination of the weighting values from new methodology, weighted scenario method for intensity order (WSM), combined with intensity order and AHP method, including a trial and error method for sensitivity analysis to make the intensity order. The optimal combination of the weighting values by the new method generated the optimal potential surface, considering spatial trend of urban expansion in the test area.

• 한국지반공학회지:지반
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• 제5권1호
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• pp.35-46
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• 1989

사질토에 있어서의 말뚝지지력을 해석하기 위하여 아세톤 고형, 수지충진기법을 사용한 모형말뚝 실험을 하여 흙의 변형을 조사하였다. 이 결과로부터 새로운 변형형태가 가정되었으며, 구형공동확장이론을 적용하여 새로운 해석법을 제시하였다. 새로운 해석법에 의한 말뚝지지력은 극한 구형공동확장압력과 지지력 상관계수로 표시된다. 본 해석법의 결과는 공동확장이론을 근거로 한 타 해석법과 비교되었다. 비교 결과, 본 해석법은 공동확장이론에 의한 말뚝지지력 해석의 결점으로 지적되는 실제보다 높은 지지력을 주는 문제점을 해결할 수 있을 것으로 기대된다.

• 한국음향학회지
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• 제41권4호
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• pp.389-396
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• 2022

본 논문은 냉장고 수축팽창 소음의 원인 및 메커니즘을 파악하고 소음 감소 방법을 제안한다. 냉장고에서 발생하는 수축팽창 소음은 주로 내부부품 사이의 접촉면에서 발생하는 스틱슬립 현상에 의한 것이다. 스틱슬립 현상을 일으키는 요인을 규명하기 위해 마찰실험이 수행되었다. 또한 내부부품의 진동레벨을 측정하여 수축팽창 소음의 특성 및 위치를 규명하였다. 실험 결과를 바탕으로 요인별 소음 특성을 검증하는 실험이 진행되었다. 이를 통해 마찰실험과 냉장고 수축팽창 소음 발생 위치와 빈도가 동일한 것을 확인하였다. 하중적재로 수직력이 증가하면 진동레벨도 증가하였다. 또한 표면거칠기를 증가하였을 때 수축팽창 소음이 저감되는 것으로 확인되었다. 따라서, 마찰실험 결과와 동일하게 접촉면의 표면거칠기를 증가하는 것이 수축팽창 소음저감 방법이라는 결론을 도출하였다.

• 한국ITS학회 논문지
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• 제7권3호
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• pp.29-37
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• 2008

본 논문은 RFID 시스템을 통해 수집되는 데이터를 '국가도로교통량조사'에 활용하는 것에 목적을 두고 있다. 연구 수행에 있어 RFID 전자태그 보급의 한계성을 극복하기 위해서, 먼저 RFID 시스템을 통하여 표본데이터를 수집하고 이를 전수화(표본데이터를 조사지점을 통과하는 모든 차량의 수로 만드는 과정) 하였다. 최적의 전수화 방법론을 선정하기 위하여 세가지 방법론(시간계수 모델, 퍼지 모델, 신경망 모델)을 적용하였으며 분석결과 시간계수를 이용한 모델이 최적의 전수화 방법론으로 선정되었다. RFID 시스템을 '국가도로교통량조사'에 활용할 수 있는 방안을 모색하기 위해 '제주도'를 모델로 하여 분석한 결과 인프라 구축의 한계로 인하여 상시조사를 대체할 수는 없으나, 수시조사는 활용에 대한 새로운 가능성을 확인하였다. 따라서 교통량 조사(상시조사)에 있어 RFID 시스템을 활용한다면 기존 검지기에 비해 비용저감 효과가 있을 것으로 기대된다.

• 농업생명과학연구
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• 제45권1호
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• pp.15-20
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• 2011

본 연구는 전북 무주지역 36년생 리기다소나무 임분을 대상으로 지상부 바이오매스 추정식을 개발하고, 줄기밀도와 바이오매스 확장계수를 산출하고자 하였다. 리기다소나무의 흉고직경을 독립변수로 하고 바이오매스를 종속변수로 하는 상대생장식을 추정한 결과, 잎 (78%)과 가지 (83%)를 제외하면 모든 부위에서 결정계수가 95% 이상의 높은 설명력을 나타냈다. 리기다소나무의 바이오매스량은 줄기 목질부 $65.9 Mg\;ha^{-1}$, 줄기 수피 $9.5Mg\;ha^{-1}$, 가지 $19.6Mg\;ha^{-1}$, 잎 $7.0Mg\;ha^{-1}$, 전체 $102Mg\;ha^{-1}$로 나타났으며, 바이오매스 구성비는 줄기목질부 (64.6%) > 가지 (19.2%) > 줄기 수피 (9.3%) > 잎 (6.9%) 순으로 나타났다. 리기다소나무의 줄기밀도 $(g/cm^{3})$는 0.453으로 나타났고, 바이오매스 확장계수는 1.344로 나타났다.

• 산경연구논집
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• 제11권3호
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• pp.7-17
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• 2020

Purpose: This study reexamines the test on the pricing of accruals quality. Theory suggests that information risk is a priced risk factor. Using accruals quality as the proxy for information risk, researchers have tested the pricing of information risk. The results are inconsistent potentially because of the information shock in the realized returns that are used as the proxy for expected returns. Based on this argument, this study revisits this issue excluding information-shock-free measure of expected returns. Research design, data and methodology: This study estimates expected returns using the vector autoregression model. This method extracts information shocks more thoroughly than the methods in prior studies; therefore, the concern regarding information shock is minimized. As risk premiums are larger in recession periods than in expansion periods, recession and expansion subsamples were used to confirm the robustness of the main findings. For the pricing test, this study uses two-stage cross-sectional regression. Results: Empirical results find evidence that accruals quality is a priced risk factor. Furthermore, this study finds that the pricing of accruals quality is observed only in recession periods. Conclusions: This study supports the argument that accruals quality, as well as the pricing of information risk, is a priced risk factor.

• International Journal of Naval Architecture and Ocean Engineering
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• 제7권1호
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• pp.195-211
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• 2015

Flat plate friction lines have been used in the process to estimate speed performance of full-scale ships in model tests. The results of the previous studies showed considerable differences in determining form factors depending on changes in plate friction lines and Reynolds numbers. These differences had a great influence on estimation of speed performance of full-scale ships. This study was conducted in two parts. In the first part, the scale effect of the form factor depending on change in the Reynolds number was studied based on CFD, in connection with three kinds of friction resistance curves: the ITTC-1957, the curve proposed by Grigson (1993; 1996), and the curve developed by Katsui et al. (2005). In the second part, change in the form factor by three kinds of friction resistance curves was investtigated based on model tests, and then the brake power and the revolution that were finally determined by expansion processes of full-scale ships. When three kinds of friction resistance curves were applied to each kind of ships, these were investigated: differences between resistance and self-propulsion components induced in the expansion processes of full-scale ships, correlation of effects between these components, and tendency of each kind of ships. Finally, what friction resistance curve was well consistent with results of test operation was examined per each kind of ships.