• Journal of Biosystems Engineering
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• 제39권4호
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• pp.283-289
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• 2014

Purpose: This study was carried out to evaluate the labor requirement and the cost-reducing effects of the pick-up type pulse crop harvester compared with those of conventional harvesting for soybeans and red beans. Methods: The labor requirement and the cost to gather, thresh, and clean for conventional harvesting operations were surveyed; those for the pick-up type pulse crop harvester were estimated for soybeans and red beans. The annual capacity of the harvester and the break-even area of the two harvesting methods were also estimated. Results: For soybean harvesting, the labor requirement of 0.57 hour-persons/10 a for the pick-up type pulse crop harvester reflects a 91.9% reduction in the labor requirement of 7.00 hour-persons/10 a for conventional harvesting. Machinery costs of 51,300 won/10 a for the harvester were estimated for an annual harvesting area of 52.5 ha/year, representing a reduction of 33.3% from the 78,700 won/10 a cost of conventional harvesting. A break-even area of 28.4 ha was estimated for the two harvestings. For red bean harvesting, the labor requirement of 0.57 hour-persons/10 a for the harvester reflects a 92.6% reduction in the labor requirement of 7.66 hour-persons/10 a for conventional harvesting. For an annual harvesting area of 52.5 ha/year, annual capacity of 52.5 ha/year and machinery costs of 51,700 won/10 a were estimated for the harvester, reflecting a reduction of 44.7% in the cost of 93,500 won/10 a for conventional harvesting. A break-even area of 23.1 ha was estimated for the two harvestings. A governmental subsidy for purchasing the harvester could contribute to reducing the break-even area and harvesting costs. Conclusions: The pick-up type pulse crop harvester for soybean and red bean harvesting could reduce the labor requirement and costs of conventional harvesting, and a governmental subsidy for purchasing the harvester will improve the economics of the harvester for efficient mechanical harvesting.

• 한국세라믹학회지
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• 제30권4호
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• pp.279-288
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• 1993

A study on calcination and reduction of AUC(ammonium uranyl carbonate, (NH4)4UO2(CO3)3) has been carried out by using TG-DTA in N2, air and H2 atmospheres, respectively. Phases of various intermediate obtained during thermal analysis of AUC in different atmospheres were confirmed by XRD. Powder characteristics of each intermediate were investigated by measuring particle size and specific surface area, and also observed by SEM. As a results, regardless of applied atmosphere AUC was calcined into amorphous UO3, which was converted to $\alpha$-U3O8 Via $\alpha$-UO3 in both H2 and N2 atmosphere, but directly into $\alpha$-UO3 in air atmosphere. Further reduction of U3O8 was only detectable in hydrogen atmosphere. During calcination and reduction, average particle size was reduced to less than 30% of original value without morphology change. Specific surface area was dramatically increased with release of NH3, CO2 and H2O from AUC powder and reached maximum value around 25$0^{\circ}C$, and then gradually decreased with the increase of temperature due to sintering effect of uranium oxides such as UO3 and U3O8. It was also found that the change of average crystallite size and pore size were closely related to the changes of specific surface area of uranium oxides.

• 한국환경과학회지
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• 제24권8호
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• pp.1065-1073
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• 2015

Urbanization can be significantly affected the hydrologic cycle by increasing flood discharge and heat flux. In order to mitigate these modifications in urban areas, Low Impact Development (LID) technique has been designed and applied in Korea. In order to estimate runoff reduction rate using SWMM LID model, the characteristics of five LID techniques was firstly analyzed for water balance. Vegetated swale and green roof were not reduce flood discharge nor infiltration amount. On the other hand, porous pavement and infiltration trench were captured by infiltration function. The flood reduction rate with LID is substantially affected by their structures and properties, e.g., the percentage of the area installed with LID components and the percentage of the drainage area of the LID components.

• 한국방재학회 논문집
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• 제11권3호
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• pp.183-189
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• 2011

본 연구에서는 저수지내 퇴사저감을 위하여 댐 상류에 저사댐을 설치하여 퇴적토를 포착하는 방법의 적합성을 검토하기 위해 국내 10개 다목적댐 유역을 대상으로 저사댐을 설치할 경우의 퇴사 저감효과에 대하여 분석하였다. 총 27개 설치지점의 퇴사 저감효과를 분석한 결과, 연구대상 다목적 댐 중 대청댐유역의 본류인 금강 지점의 저사댐 설치시 퇴사 저감효과가 가장 큰 것으로 판단되었으며 저사댐 설치에 따른 수명연장효과는 미설치시 수명보다 약 60%가 연장되는 것으로 판단되었다. 또한 저사댐 설치로 인한 퇴사 저감률에 영향을 미치는 인자를 알아보기 위하여 회귀분석을 실시한 결과 유역면적비가 가장 큰 영향을 미치는 것으로 판단되었으며 유역면적비에 대한 회귀식을 도출 할 수 있었다. 본 연구결과를 통해 국내 저사댐 도입시 기대 퇴사저감 효과 산정이나 설치위치 검토를 위한 기초자료 활용될 수 있을 것으로 판단된다.

• Imaging Science in Dentistry
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• 제48권1호
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• pp.41-44
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• 2018

Purpose: To evaluate the effect of different numbers of basis images and the use of metal artifact reduction (MAR) on the production and reduction of artifacts in cone-beam computed tomography images. Materials and Methods: An acrylic resin phantom with a metal alloy sample was scanned, with 450 or 720 basis images and with or without MAR. Standard deviation values for the test areas (around the metal object) were obtained as a way of measuring artifact production. Two-way analysis of variance was used with a 5% significance level. Results: There was no significant difference in artifact production among the images obtained with different numbers of basis images without MAR (P=.985). MAR significantly reduced artifact production in the test areas only in the protocol using 720 basis images (P=.017). The protocol using 450 basis images with MAR showed no significant difference in artifact production when compared to the protocol using 720 basis images with MAR (P=.579). Conclusion: Protocols with a smaller number of basis images and with MAR activated are preferable for minimizing artifact production in tomographic images without exposing the patient to a greater radiation dose.

• 대한기계학회논문집B
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• 제21권9호
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• pp.1139-1148
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• 1997

Compression waves propagating in a high-speed railway tunnel develops large pressure fluctuations on the train body or tunnel structures. The pressure fluctuations would cause an ear discomfort for the passengers and increase the aerodynamic resistance of trains. As a fundamental research to resolve the pressure wave phenomenon in the tunnel, experiments were carried out by using a shock tube with an open end. A blockage to model trains inside the tunnel was installed on the lower wall of shock tube, thus forming a sudden cross-sectional area reduction. The compression waves were obtained by the fast opening gate valve instead of a conventional diaphragm of shock tube and measured by the flush mounted pressure transducers with a high sensitivity. The experimental results were compared with the previous theoretical analyses. The results show that the ratio of the reflected to the incident compression wave at the sudden cross-sectional area reduction increases but the ratio of the passing to the incident compression wave decreases, as the incident compression wave becomes stronger. This experimental results are in good agreements with the previous theoretical ones. The maximum pressure gradient of the compression wave abruptly increases but the width of the wave front does not vary, as it passes over the sudden cross-sectional area reduction.

• 환경영향평가
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• 제15권1호
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• pp.23-33
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• 2006

The factor of air pollution in a large industrial city is not only manufactories but also, activities related to trucks. Sihwa National Industrial Complex is located in Siheung City; due to the industries, more diverse activities related to trucks occur in Siheung City than other cities. In particular, the new residential area in Siheung City is close to the industrial complex; so, the damage of this residential area is expected that it would be more serious and vulnerable than other areas. The aim of this study is to analyze influence of the air pollution by a truck in Siheung City. ISCST3 Model and Arc View program were used for this study and Siheung City was divided into 1,000 meter by 1,000 meter grid to analyze. Furthermore, this study suggested two reduction controls of air pollution in Siheung City, and analyzed the results from these reduction managements. The results of the present condition showed that residences located in north of Sihwa Industrial Complex are influenced by air pollution material. Furthermore, air pollution by trucks has affected on the residents which is near the road in Siheung City. Therefore, this study suggested two reduction controls by the Traffic System Management. The first alternative plan is setting the truck traffic limitation zone in the road that is located in south of resident areas and many trucks traffic. Next, the second alternative plan is setting freight truck way on the most traffic road to enter the industrial complex. The reduction effect of the first alternative is good on the residential area. And, the second alternate about freight truck way is divided passenger cars into trucks. Therefore, there are increase of average speed and decrease of average concentration, and spatial reduction effects found in wide areas.

• KEPCO Journal on Electric Power and Energy
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• 제5권4호
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• pp.331-335
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• 2019

In this study we investigate catalytic activity and selectivity of mixture of Ag and ketjenblack according to their ratios by product analysis and electrochemical experiments, such as cyclic voltammetry, linear sweep voltammetry and chronoamperometry. We reveal that catalytic activity toward CO₂ reduction to CO is improved by simple mixing Ag nanoparticle and ketjenblack because addition of ketjenblack suppresses aggregation of Ag nanoparticles and brings increase in electrochemical active surface area. However, excess amount of ketjenblack rather inhibit the CO₂ reduction to CO. These observations provide clues to develop highly active Ag catalyst or electrode toward electrochemical reduction of CO₂.

• 한국물환경학회지
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• 제28권6호
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• pp.786-795
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• 2012

Water quality management should be focused on the pollution concentrated area so that the improvement of water quality can be achieved effectively for the management of Total Maximum Daily Loads (TMDLs). It is necessary to consider discharge characteristics in the TMDL plan. This study analysed discharge characteristics such as pollution generation and discharge load density, and reduction potential by each unit watershed, and categorized the unit watershed into four groups according to its discharge load characteristics. This analysis can be used as helpful information for the prioritization of pollution reduction area and selection of pollution reduction measures in the development of TMDL plans.

• 도시과학
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• 제7권2호
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• pp.1-9
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• 2018

In this study, Analysis of DRT model and contribustion based on the case of local governments adopting the Demand Responsive Transit(DRT) in order to provide transportation in public transportation service weak area. Based on the case of Yeoju Area, the contribution of the DRT was analyzed. The DRT model was established as a fixed and call type model with taxi and bus transportation. Based on the results of the happy taxi service in Yeoju Area in 2016, the contribution of DRT was analyzed. According to the happy taxi performance of Yeoju city, it was introduced to 27 villages, and operated 4,188 times. And 9,111 people used it and Yeoju Area supported about 53 million Won. The contribution of local governments was analyzed in terms of local government, users, and social aspects. On local government aspects, we analyzed the budget cuts and complaints resolution. On the user aspects, we analyzed waiting time reduction, walking time reduction, travel time reduction, comfort, punctuality, and stability. On social aspects, we analyzed taxi and regional economy activation, and convenience of mobility.