• 물과 미래
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• 제35권5호
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• pp.51-59
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• 2002

In recent years the human impact on the environment becomes increasing lift threatening, calls for the better management of resources. In field of water quality of river flow, the best way to conserve water quality is specific efforts to control the pollutant loadings and treat the loadings in the basin to reduce the discharge of pollutant loadings to river. But in general the water quality influenced by the dam discharge. Especially in dry season, it is more dominant way to improve the water quality which contaminated with the pollutant loadings from the basin. The dam discharge amounts of the 2 dams in the Keum River that maintain the down stream water quality were estimated for the year of 1999, 2001, 2006, 2011, in case of irrigation and non-irrigation seasons. The pollutant loadings for the basin are estimated with the planning of treatment plants construction schedule for every sub-basins. The river flow rates were considered low flow as 2.33 year low flow and 10 year low flow. The QUAL2E model was used as a tool of simulation.

• Advances in aircraft and spacecraft science
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• 제4권4호
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• pp.371-399
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• 2017

The motion of propeller driven airplanes, flying at constant speed on ascending or descending helical trajectories is analyzed. The dynamical abilities of the airplane are shown to result in restrictions on the ranges of the geometrical parameters of the helical path. The physical quantities taken into account are the variation of air density with altitude, the airplane mass change due to fuel consumption, its load factor, its lift coefficient, and the thrust its engine can produce. Formulas are provided for determining all the airplane dynamical parameters on the trajectory. A procedure is proposed for the construction of tables from which the flyability of trajectories at a given angle of inclination and radius can be read, with the corresponding minimum and maximum speeds allowed, the final altitude reached and the amount of fuel burned. Sample calculations are shown for the Cessna 182, a Silver Fox like unmanned aerial vehicle, and the C-130 Hercules.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2023년도 봄 학술논문 발표대회
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• pp.77-78
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• 2023

As large logistics buildings have high floor heights and long spans, these buildings are designed as PC structures, and large cranes are used to lift PC members. PC erection planning can generally cause errors depending on the field engineer's experience. To solve this problem, a basic analysis method is needed to establish a systematic PC member erection plan. Crane work can be minimized if the trajectory is easily and quickly calculated according to the location of the crane and applied to the site. Therefore, the objective of this study is a basic study of crane trajectory distance calculation for sustainable PC members erection of large logistic building. In this study, a crawler crane commonly used for lifting PC members is limited. The trajectory distance for the PC erection plan was automatically calculated using the algorithm.

• Advances in aircraft and spacecraft science
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• 제10권5호
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• pp.473-494
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• 2023

This article introduces a formalism for the analysis of airplane trajectories on which the motion is determined by specifying the power of the engines. It explains a procedure to solve the equations of motion to obtain the value of the relevant flight parameters. It then enumerates the constraints that the dynamical abilities of the airplane impose on the amount of fuel used, the speed, the load factor, the lift coefficient, the positivity and upper boundedness of the power available. Examples of analysis are provided to illustrate the method proposed, with rectilinear and circular trajectories. Two very different types of airplanes are used in the examples: a Silver Fox-like small UAV and a common Cessna 182 Skylane.

• 농촌계획
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• 제12권4호
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• pp.63-76
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• 2006

This research tried to present some basic data necessary to give effective support to urban retirees who already returned to the farm by looking into factors effecting on their adjustments to the lives before they returned to the farm and after they did so to know how well they adapt to the rural lives. For the purpose, we made a survey of 408 returners to the farm over the age of 50 for 6 days from October 18 to October 23 in 2004 using questionaires. The results show the followings. First, there are significant difference in the satisfaction with the rural life occurred by the sociological demographic changes according to 'health condition', 'subjective economic ability' and 'previous job'. Second, the difference of satisfaction with the rural lift which was taken place by the reasons before they moved to the farm is effected considerably by what made them decide to return to the farm first whether they prepared for it or not and how much money they have to do so. Therefore, to succeed in adjustment to the rural lives, their decision should be made by positive causes, they have to prepare concretely for it before they carry out their plans and they had better have enough money to move. Third, the difference of satisfaction with the rural life occurred by the reasons after they moved to the farm is effected by 'satisfaction with the forming information', 'the number of friends or neighbors', 'the frequency of meeting the friendly', 'the level of intimacy with neighbors' and 'their efforts to improve the relations with other residents'. And the sensitiveness to perceive the inconvenience according to the rural life is related strongly to the satisfaction with the rural life in the above 6 areas. Fourth, the repression analysis implemented to find how much the above 3 factors effect on the satisfaction with the rural life shows that it is 'returner's current health condition', 'farming education', 'farming fund' and 'effort to be intimate with other residents' that are very important.

• 농촌계획
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• 제24권4호
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• pp.15-25
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• 2018

This study was designed to understand the change of rural landscape and to consider problems followed by development restrictions lifted for Neobiul Village in Ansan City, Korea. Physical landscape changes were comprehended by a field study and interview with local residents, and the residents' perception regarding the landscape changes were analyzed with the REP investigation method. The results can be summarized into the following three points: First, due to the lift of development restrictions and the deregulation of land use, the number of factories and warehouses for rent increased, which became a new source of income for the village. Second, the residents' complaints increased due to the increased traffic volume and waste from a sudden influx of factories and warehouses, which could not be handled by a small farming village. Third, a mix of landscape combining both city and farming village was formed due to the influx of external capital and the need of rental income, although the residents rather wanted Neobiul Village to become a residential village than a factory location. Furthermore, even in the farmlands near the village where development restrictions have not been lifted, the level of dependence on the farming industry has decreased as a consequence of the increase in farmland rent and weekend farms. This paper confirmed that the change of rural landscape followed by lifted development restrictions affects the everyday life of residents living in Neobiul Village. This study has significant implications in that it suggests a case showing the effects of national policies such as lifting development restrictions for rural villages in suburban areas.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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• pp.89-90
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• 2002

Ball reducer (HERB Drive: High Efficient Wave Rolling Ball Drive) with waved grooves has many advantages over other types of reducers for high-reduction ratio, low noise and low energy loss, etc. The mechanism of force transmission is very similar to that of cam and follower in automobile valve train system especially in contact behaviors. In this study, we have investigated the traces of contact between ball and outer ring, and the dynamic contact behaviors of elastohydodynamic lubrication(EHL) with a certain reduction ratio. In order to verify the contact behaviors between ball and outer ring for the critical endurance lift, the contact velocity and load are computed for a cycle. During some intervals of a cycle, the contact velocity reverses its direction very suddenly. It is expected that changing the contact direction causes undesirable endurance performance because EHL film frequently col lapse at the moment of velocity reversal. From the computational investigation in this work, we hope to predict similar contact damages in other machinery due to this kind of contact behaviors, which is very typical in many contact phenomena.

• 한국염색가공학회지
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• 제8권6호
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• pp.27-32
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• 1996

This research is to investigate the reaction kinetics by air-lift bioreactor using calcium hydroxide, the neutralization agent and immobilization media, for removing ethylene glycol remained after chemical pretreatment. It was found that the optimum hydraulic retention time was obtained as 24.2hours at the optimum F/M ratio of 1.32kg-$TCOD_{Mn}$/day.kg-MLVSS, and then, infiuent $TCOD_{Mn}$ and MLVSS concentration were 3,290mg/l and 2,472mg/l, respectively. During the steady state, the kinetics constants such as maximum specific substrate removal rate, half saturation velocity coefficient, yield coefficient and endogenous respiration coefficient were estimated in the base of $TCOD_{Mn}$ as substrate concentration. And they were 1.47day$^{-1}$, 3.95mg/l, 0.391 and 0.092day$^{-1}$, respectively. And also, the oxgen use coefficients for cell synthesis, a', and energy of maintenance, b', were obtained as 0.4kg-O$_{2}$/kg-$TCOD_{Mn}$ and 0.056day$^{-1}$, at the steady state by the experimental result of oxygen uptake rate.

• 한국주거학회논문집
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• 제13권4호
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• pp.1-10
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• 2002

The purpose of this study was to contribute to planning and developing various new apartment unit plans of the future through examining the differences on the spatial behavioral patterns and the post-occupancy evaluation between DK-front type and DK-rear type. 245 households which were included 79 DK-front types and 166 DK-rear types, were collected and analyzed at Masan and Gimhae cities in Kyungnam area. The result is as follows: 1) The analysis of the spatial behavioral patterns revealed that Anbang was the room for the couple independent from guests and children. Living room was the family's room for every activity, used more frequently DK-front types than DK-rear types. The family lift cycles of households, the visual unification between Living room and DK, the closed figures of DK in DK-front types have been influenced for the activities of Living room. 2) In the post-occupancy evaluation, DK-front types were positive in the lighting of DK area and its connection with Living room, while negative in the proximity from entrance to DK, cooking convenience, and the proximity between rooms. It was explained clearly through the reasons of the rejection of DK-front types from now.

• 대한조선학회논문집
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• 제51권5호
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• pp.349-355
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• 2014

The resistance test of a high speed craft such as planing ship is performed with a high speed towing carriage instead of ordinary towing carriage because of the speed limitation. In the resistance test using high speed towing carriage, the model ship is fixed to the carriage to restrain the running attitude for enough measuring time. Such method is called fixed model test method. In the fixed model test method, to get the appropriate running attitude, the model test is iteratively repeated until the trim moment and lift force are close to zero. In this research, trim free model test method is investigated to reduce the number of iteration. And, the limitation of towing speed range in the trim free model test method is investigated.