• Journal of Korean Society of Water and Wastewater
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• v.18 no.2
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• pp.228-234
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• 2004

Dissolved air flotation (DAF), in which suspended solids are removed from water by means of micro-size air bubbles raising slowly up in water and lifting solids from water (smaller than those) attached onto the micro-bubbles as well as those (larger than solids) being attached on these, have been used in water and wastewater since 1920s. The dissolved air flotation technology was originally based on the laminar flow conditions prevailing in water to be treated, but the latest development in that technology has led now to a situation, in which the flow conditions may also be turbulent ones in the modem dissolved air flotation units. Despite of that, the flotation phenomenon used in this unit operation for removal suspended solids from water or wastewater is still the same.

• Bulletin of the Korean Mathematical Society
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• v.60 no.1
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• pp.83-91
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• 2023

A ring R is called a UN ring if every non unit of it can be written as product of a unit and a nilpotent element. We obtain results about lifting of conjugate idempotents and unit regular elements modulo an ideal I of a UN ring R. Matrix rings over UN rings are discussed and it is obtained that for a commutative ring R, a matrix ring M_n(R) is UN if and only if R is UN. Lastly, UN group rings are investigated and we obtain the conditions on a group G and a field K for the group algebra KG to be UN. Then we extend the results obtained for KG to the group ring RG over a ring R (which may not necessarily be a field).

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.4
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• pp.567-574
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• 2006

This paper focuses on lossy medical image compression methods for medical images that operate on three-dimensional(3-D) irreversible integer wavelet transform. We offer an application of unbalanced tree structure algorithm to medical images, using a 3-D unbalanced wavelet decomposition and a 3-D unbalanced spatial dependence tree. The wavelet decomposition is accomplished with integer wavelet filters implemented with the lifting method. We have tested our encoder on volumetric medical images using different integer filters and 16 coding unit size. The coding unit sizes of 16 slices save considerable dynamic memory(RAM) and coding delay from full sequence coding units used in previous works. If we allow the formation of trees of different lengths, then we can accomodate more transaxial scales than three. Then the encoder and decoder can then keep track of the length of the tree in which each pixel resides through the sequence of decompositions. Results show that, even with these small coding units, our algorithm with I(5,3)filter performs as well and better in lossy coding than previous coding systems using 3-D integer unbalanced wavelet transforms on volumetric medical images.

• Journal of Practical Agriculture & Fisheries Research
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• v.26 no.2
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• pp.25-30
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• 2024

This study was conducted to develop the hanging type circular-patterned system that at maximizing the spatial efficiency of strawberry cultivation to increase yields, while also reducing labor and improving energy efficiency. The system consists of a cultivation bed units, longitudinal moving device, bed lifting device, front and rear transfer devices, lateral transfer device, nutrient supply device, and control unit. Performance testing revealed that the operational motor for longitudinal movement should have a torque of at least 0.1Nm based on the design weight and traction force of the cultivation bed unit. The power consumption required to move one cycle was calculated to be approximately 149Wh when performing harvesting or maintenance tasks for all 10 cultivation beds. Vibration angles measured during bed movement showed that the lateral transfer resulted in a roll angle ranging from -0.62° to 0.68° and a pitch angle ranging from -3.79° to 5.26°. For longitudinal transfer, the roll angle ranged from -3.37° to 3.36°, and the pitch angle ranged from -0.45° to 0.49°.

• Journal of Biosystems Engineering
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• v.33 no.3
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• pp.157-166
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• 2008

Protected horticulture is labor-intensive. It necessitates great amount of labor in many tasks including grafting, pollination and harvesting. Particularly, carrying crops involves the most intensive labor which leads to a high risk of musculoskeletal disorder. Thus, this study aims at developing an ergonomic vehicle to reduce this intensity of labor and ergonomic evaluation by applying the newly developed vehicles to REBA. 5 healthy male subjects with no records of any musculoskeletal disorder were participated in this study. The experimental units were divided into three categories: lifting, lowering and pushing tasks. The results showed that the developed vehicle received less loads in group B (arms and wrists) than in group A (trunk, neck and legs). Especially, the developed vehicle scored $1.0{\sim}4.4$ in group C on REBA while the conventional wheelbarrow got $3.0{\sim}7.6$, regardless of working postures. In conclusion, the developed ergonomic vehicle provided less loads for human bodies compared to the conventional one.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.6 no.3
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• pp.85-91
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• 2007

This study was carried out to minimize the lifting force of a two hinge type stand mechanism. This unit is designed for the display devices in order to enhance the ergonomics for effective height adjustment and maintenance at any preferred position. The unit will be very useful for the mechanism fabricated with a coil spring and disc springs as a torque generator. The maximum and the minimum torque value should be calculated initially for the smooth lift. And the reasonable torque distribution is necessary to prevent any auto lift and auto dropping at any position because the torque generated by coil spring is more sensitive than disc spring in tilting the position. Therefore, the analysis of the coil spring is requisite to issue the specific torque value depending on the distorted angle with securing reliability of a long time storage condition. After the theoretical torque value was calculated, the evaluation was carried out by making a proto-type sample, then distorted angle was updated by experiment. The result of this study can readily be applied to various units for the optimization of the smooth lift.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1454-1457
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• 2003

This study was carried out to minimize the lifting force of a two hinge type stand mechanism. This unit is designed for the display devices in order to enhance the ergonomics for effective height adjustment and maintenance at any preferred position. The unit will be very useful for the mechanism fabricated with a coil spring and disc springs as a torque generator. The maximum and the minimum torque value should be calculated initially for the smooth lift. And the reasonable torque distribution is necessary to prevent any AUTO LIFT and AUTO Drooping at any position because the torque generated by coil spring is more sensitive than disc spring in tilting the position. Therefore, the analysis of the coil spring is requisite to issue the specific torque value depending on the distorted angle with securing reliability of a long time storage condition. After the theoretical torque value was calculated, the evaluation was carried out by making a proto-type sample, then distorted angle was updated by experiment. The result of this study can readily be applied to various units for the optimization of the smooth lift.

• Korean Journal of Social Welfare
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• v.68 no.2
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• pp.53-77
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• 2016

This research is performed to verify a suggestive understanding and undertone on radical social workers's balanced practical experiences responding to the current situation to discover the new practical way of Korean social work so as to overcome the limitation of the above mentioned microscopic approach. It focuses on Giorgi's descriptive phenomenological study and further relating areas to provide information on Radical Social Workers'(RSW) social work practical and specific experiences and fundamental implication. This research has been participated with 9 RSWs, led the past democratic movement, have participated with this research. The data covers 84 meaningful units, 24 exposed topics, and 7 essential themes. The essential themes are as follow; lifting a latch into prepared changes, unavoidable destiny, drive for change from the bottom, collaborated forces of minority groups, changing the oppressive laws and institutions to more favorable ones for minorities, being patient and waiting required as birds breaking eggs to become a bird. Based on the collected data, Researchers discuss the main features and issues of our instituted social work practices.

• Ocean and Polar Research
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• v.36 no.4
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• pp.383-394
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• 2014

The surface sediments from the manganese nodule exploration area of Korea in the Clarion-Clipperton fracture zone were investigated to understand the resource potential of and emplacement mechanism for rare earth elements (REEs). The sediments are categorized into three lithological units (Unit I, II and III from top to bottom), but into two groups (Unit I/II and Unit III) based on the distribution pattern of REEs. The distribution pattern of REEs in Unit I/II is similar to that of Post-Archean Australian Shale (PAAS), but shows a negative Ce anomaly and enrichment in heavy REEs (HREEs). In Unit III, the HREE enrichment and Ce anomaly is much more remarkable than Unit I/II when normalized to PAAS, which are interpreted as resulting from the absorption of REEs from seawater by Fe oxyhydroxides that were transported along the buoyant plume from remotely-located hydrothermal vents. It is supported by the PAAS-normalized REE pattern of Unit III which is similar to those of seawater and East Pacific Rise sediments. Meanwhile, the PAAS-normalized REE pattern of Unit I/II is explained by the 4:1 mixing of terrestrial eolian sediment and Unit III from each, indicating the much smaller contribution of hydrothermal origin material to Unit I/II. The studied sediments have the potentiality of a low-grade and large tonnage REE resource. However, the mining of REE-bearing sediment needs a large size extra collecting, lifting and treatment system to dress and refine low-grade sediments if the sediment is exploited with manganese nodules. It is economically infeasible to develop low-grade REE sediments at this moment in time because the exploitation of REE-bearing sediments with manganese nodules increase the mining cost.

• Journal of Industrial Convergence
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• v.21 no.10
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• pp.103-110
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• 2023

This study is a descriptive comparative study to identify personal characteristics and nursing work characteristics according to the presence or absence of back pain of nurses in intensive care units in general hospitals and to explore major factors that affect back pain induction. A survey was conducted on nurses in the intensive care unit of a general hospital located in D City, and a total of 100 copies were used for analysis. For data analysis, descriptive statistics, chi-square test, Fisher accurate test, and logistic regression analysis were performed using IBM SPSS 24.0. The study found that 69% of intensive care unit nurses had back pain, 65.2% of which experienced back pain for more than three months in the past year, and 84.1% had back pain after working in the intensive care unit. In the back pain intensity score measured by NRS, 49% answered that they experienced 4 or more points. As factors related to back pain, gender (p=.03) were significant variables in personal characteristics, in the characteristics of nursing work, the number of patient assistance (p=.03) and the number of patient exchanges (p=.01), heavy lifting (p=.04), satisfaction with the condition of the shoes (p=<.001) was found to be a significant variable affecting back pain induction. It is considered that hospital organization and national policies are needed to prevent and manage low back pain in intensive care unit nurses.