• Korean Journal of Soil Science and Fertilizer
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• v.17 no.2
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• pp.155-160
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• 1984

This study was conducted to find out the effects of soil physical properties on workability of farm machines in the paddy fields. Various soil physical properties, workability of cultivator and tractor were investigated at three different textured soils and three levels of soil moisture conditions. The results are summarized as follows: 1. Soil strength, shear and friction resistance, plate sinkage, wheel and footprint sinkage, and slippage were greatly affected by the soil texture and moisture conditions, and the workabilities were changed by the soil physical properties. 2. Cultivator workability were high values at the range of soil shear resistance $200-450g/cm^2$, and cultivator or tractor working was difficult at below $200g/cm^2$ of the shear resistance. 3. The favorable range of soil strength for tractor working was $8-12kg/cm^2$, and $6-10kg/cm^2$ for cultivator. 4. Footprint sinkage was closely related to the values obtained by testers. It's optimum range for cultivator was 1-2cm, and tractor workability was increased by decreasing the footprint sinkage.

• Therapeutic Science for Rehabilitation
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• v.13 no.2
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• pp.53-67
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• 2024

Objective : This study aimed to identify common activities with similar participation levels between community-dwelling individuals in the United States (US) and South Korea (Study 1), and analyze the changes in activity participation patterns across the adult lifespan in South Korea (Study 2). Methods : We administered the online survey-based Activity Card Sort version 3 (ACS-3) to adults living in the US and South Korea. In Study 1, we computed the average participation level and visualized 100 activities of the ACS-3 from both the US and Korean samples. The average participation level across the four age groups in Study 2 was calculated and visualized to understand the changes in patterns of involvement across the four ACS-3 domains in a Korean sample. Results : In Study 1, data from 161 Americans and 163 Koreans were analyzed. Of the 100 activities, 48 (instrumental: 20; leisure: 13; fitness/health: 6; social: 9) demonstrated similar levels of participation between the two samples. In Study 2, data from 420 Koreans were analyzed and a tendency for decreased participation with age was found in all domains, except for the instrumental domain. Conclusion : Common daily activities may be used as a means of intervention across cultures in occupational therapy. Protective approaches and support are recommended to optimize older adults' participation in daily life.

• Journal of Bio-Environment Control
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• v.23 no.1
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• pp.26-30
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• 2014

Purpose of this study was a development of a sprayer arm auto control system that could be operated according to distance from pear trees for automation of pest control. Auto control system included two parts, hardware and software. First, controller was made with an MCU and relay switches. Two types of ultra-sonic sensors were installed to measure distance from pear trees: one on/off type that detect up to 3 m, and the other continuous type providing 0~5 V output corresponding to distance of 0~3 m. Second, an auto control algorithm was developed to control. Each spraying arm was controlled according to the sensor-based distance from the pear trees. And it could dodge obstacles to protect itself. Max and min signal values were eliminated, when five sensor signals was collected, and then signals were averaged to reduce sensor's noises. According to results of field experiment, auto control test result was better than non auto control test result. Spraying rates were 69.25% (left line) and 98.09% (right line) under non auto control mode, because pear trees were not planted uniformly. But, auto control test's results were 92.66% (left line) and 94.64% (right line). Spraying rate was increased by maintaining distance from tree.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.10
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• pp.2454-2460
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• 2013

So far, the port cargo handling capacity of general cargo was computed using simple formulae based on mathematical models. However, this simple calculation could not be able to reflect the reality. Thus, the simulation method was applied in this paper to overcome the limitation that the calculation method used in the past studies has. The process occurring from arrival to departure of a ship, which is reflecting the process rules of berth, was modeled to estimate the optimum level of handling capacity by using an example of the loading and unloading of an appropriated wharf at the harbor, and simulation was performed by developing the prototype. The actual processing capability of Mukho port was compared to the estimated capability calculated using the simulation method and the optimum level of capability could be computed by repeatedly simulating the input variable condition of the simulation prototype.

• Korean Journal of Medicinal Crop Science
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• v.11 no.5
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• pp.340-346
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• 2003

This study was carried out to improve cultivation techniques by low cost and labour saving in ginseng (Panax ginseng C. A. Meyer) seedling production, by elucidating proper ratio virgin soil and organic fertilizer, suitable height of front piller. The obtained results are as follows ; The optimal ratio of white decomposition of virgin soil and organic fertilizer was 10:1 for good yield of standard seedling, The fittest height of front piller was 150 cm because of both good seedling growth and yield. The cost for production of seedling of ginseng could be reduced by both optimal ratio of virgin soil, organic fertilizer and selection of front piller height.

• Korean Journal of Construction Engineering and Management
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• v.6 no.4 s.26
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• pp.152-163
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• 2005

Pile driving work causes a vibration problem in the construction site using pile foundation and often causes civil affairs by construction noise around the construction site. For the vibration and noise problems, the driving after drilling method rather than the direct driving method is being generalized for reducing vibration and noise. However, this method also causes civil affairs when the driving work is operated in adjacent area. This study suggests a criterion for evaluating an optimal allowed distance for pile driving work by the driving after drilling method. Actual surveys of vibration and noise for pile driving work in seven construction sites were used for developing regression analysis equations. The results can be a standard to estimate the allowed distance to avoid vibration and noise problems in pile driving work for deep foundation.

• Korean Chemical Engineering Research
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• v.48 no.4
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• pp.490-498
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• 2010

The optimum mold design and the optimum process condition were constructed upon executing process simulation of rubber injection molding with the commercial CAE program of MOLDFLOW(Ver. 5.2) in order to solve the process-problems of K company relating to air-traps and short-shots. The former occurs at the cavity edge of torque-rod-bush and the latter takes place for the injection molding of dynamic dampers. As a result the process problem relating to air traps was solved by optimizing edge-angle and the number of gates to prevent the flow congestion of flow-front and to make the flow-front movement unaffected by congestion. For dynamic dampers of K company the unmolded flaw caused by their unfilled cavity was corrected by installing the air-vent at the confronting locations of both upstream and downstream of flow-front where air traps frequently occur. Besides the unmolded flaws were rectified by altering the position of gate from the upper to the middle or by increasing the number of gates. Thus the process problems of K company relating to air-traps and short-shots of torque-rod-bush and dynamic dampers, respectively, were solved by proper altering of mold design with process simulation of rubber injection molding.

• Korean Journal of Construction Engineering and Management
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• v.5 no.5 s.21
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• pp.126-134
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• 2004

Since a construction project is a series of works that utilizes resources to accomplish the project goal for a given time period, efficient resource management is a prerequisite for the success of the project. Two major areas of resource management are resource constrained scheduling focusing on the limited resource availability and resource leveling focusing on smoothing resource usage pattern on the fixed project completion time. It is not available, however, to apply both techniques to a project at the same time. This paper proposes a model to enhance the minimum moment algorithm of resource leveling, aiming to find an efficient usage of resources and an appropriate project completion time. A survey was performed to evaluate the major five factors in the model. A case study demonstrates the value of the proposed resource leveling technique.

• Korean Journal of Construction Engineering and Management
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• v.22 no.3
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• pp.12-20
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• 2021

In order to secure construction quality and safety and prevent cost disputes, the importance of calculating 'the appropriate construction period' has recently emerged. It is necessary to analyze a considerable amount of historical data to establish the standard for calculating the construction period. However, many experts are raising questions about the use of past data due to changes in the construction business environment, such as shortening working hours, reinforcing quality regulations, and changing climate conditions. In addition, the possibility of errors increases when calculating a uniform construction period using historical statistics because the work order and productivity are very diverse according to construction conditions. Therefore, through this study, a new solution to change from the method of analyzing past data to the method of reviewing current production data through an active 'transformation of thoughts' was proposed through this study. In other words, the process of reviewing and calculating 'the appropriate construction period' was institutionalized by introducing 'process management experts' and 'construction experts by type of construction' in the design stage.

• Journal of the Korea Institute of Building Construction
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• v.11 no.1
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• pp.73-81
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• 2011

The ultimate goal of construction is to complete the given work in the most economical and safest way within the required construction period while meeting the quality standards specified in the design drawing. There are a few characteristics of finish work. First, executed in subdivided processes, finish work involves a very diverse and complex structure. Second, there are no criteria for each segmented process with regard to the appropriate time of input. Third, it is not very necessary to set priorities for lead and lag works. This study intends to provide information on the completion of a project in accordance with the required duration by setting priorities in the delay of each detailed process of finish work to minimize delay in finish work. In this study, finish work is divided into wet work and other types of finish work, and the importance of each process is classified based on the given details of each process. In addition, the study employs a survey to analyze delay factors of a designer, a constructor, and a supplier. Using the survey results, the study sets priorities in delay of final work to provide information on the completion of an apartment project within the planned construction period.