• Journal of Korean Society of Water and Wastewater
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• v.22 no.4
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• pp.445-448
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• 2008

The application of the membrane filtration process has been increased for the drinking water treatment system because of excellent quality of treated water compared with the sand filtration process. The selection of suitable pre-treatment processes and optimum flux according to the characteristics of raw water are important factors for the design of membrane processes. In this study, the most efficient pre-treatment processes for drinking water was selected by investigating the effects of pre-treatment processes on the operational stability of the membrane filtration process. Both lab-scale and pilot-scale experiments were conducted. In the lab-scale test, the effect of pre-treatment processes on the stability of the membrane filtration process was investigated indirectly by comparing the performance of membrane flux for raw water, pre-treated water, and membrane permeated water. In the pilot-scale test, the usefulness of prefiltration processes was assessed by comparing the performance of single membrane process and hybrid coagulation-membrane process. The results indicated that the coagulation process contributed to the stabilization of trans-membrane pressure (TMP) by removing contaminants on membranes, though the pre-filtration process had little effect on the TMP.

• Aerospace Engineering and Technology
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• v.12 no.2
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• pp.180-185
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• 2013

In this study, preliminary design of human powered aircraft was performed by considering the aerodynamic performance. For this, overall weight including the aircraft and pilot was determined. Then, the main wing and horizontal/vertical tail were designed with appropriate selection of the airfoils and planform shapes. Based on these, three dimensional flow was calculated to obtain lift and drag coefficients and the position of center of gravity (CG). Consequently, it was shown that the lift and power of the aircraft satisfied the constraints of the minimum required lift and the pilot's available power. Also, the CG of the aircraft was located at aerodynamic center (AC) of the main wing, which guaranteed 26% of the static margin.

• Journal of Multimedia Information System
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• v.7 no.4
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• pp.249-256
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• 2020

Learning methods using various assistive and smart devices have been developed to enable independent learning of the disabled. Pointer control is the most important consideration for the disabled when controlling a device and the contents of an existing graphical user interface (GUI) environment; however, difficulties can be encountered when using a pointer, depending on the disability type; Although there are individual differences depending on the blind, low vision, and upper limb disability, problems arise in the accuracy of object selection and execution in common. A multimodal interface pilot solution is presented that enables people with various disability types to control web interactions more easily. First, we classify web interaction types using digital devices and derive essential web interactions among them. Second, to solve problems that occur when performing web interactions considering the disability type, the necessary technology according to the characteristics of each disability type is presented. Finally, a pilot solution for the multimodal interface for each disability type is proposed. We identified three disability types and developed solutions for each type. We developed a remote-control operation voice interface for blind people and a voice output interface applying the selective focusing technique for low-vision people. Finally, we developed a gaze-tracking and voice-command interface for GUI operations for people with upper-limb disability.

• The Journal of Korean Physical Therapy
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• v.34 no.5
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• pp.193-197
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• 2022

Purpose: The purpose of this pilot study was to assess the feasibility of a proposed study "To investigate the effects of applying a vibration stimulation to the paretic and non-paretic sides on balance and gait in stroke patients" before proceeding with the main study. Methods: A total of 30 patients who had suffered a stroke and who met the selection criteria participated in this study. However, only 14 patients completed the study. The study subjects were randomly assigned to vibration stimulation on either both sides (B group) or the paralyzed side (P group). The interventions were applied for six weeks. The patients were assessed using the Berg balance scale (BBS), Timed up and go (TUG), 10-meter walk (10 MW), and 6-minute walk (6 MW) tests. Results: There was a significant difference before and after the application of vibration stimulation in the BBS, TUG, 10MW, and 6 MW tests in the B group (p<0.05). Similarly, there was also a significant difference observed in the 10 MW and 6 MW tests in the P group (p<0.05). The difference between the two groups was not significant in the BBS, TUG, 10 MW, and 6 MW tests (p>0.05). Conclusion: This pilot study suggests that it would be feasible to conduct a large-scale randomized controlled trial (RCT) to examine the effects of applying a vibration stimulation to the paretic and non-paretic sides, on the balance and gait in stroke patients.

• Journal of Communications and Networks
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• v.18 no.6
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• pp.892-901
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• 2016

In the multi-user multiple-input multiple-output (MIMO) system, orthogonal random beamforming (ORBF) scheme is proposed to serve multiple users simultaneously in order to achieve the multi-user diversity gain. The opportunistic space-division multiple access system (OSDMA-S) scheme performs multiple weighting matrices during the training phase and chooses the best weighting matrix to be used to broadcast data during the transmitting phase. The OSDMA-S scheme works better than the original ORBF by decreasing the inter-user interference during the transmitting phase. To save more time in the training phase, a partly random multiple weighting matrices selection scheme is proposed in this paper. In our proposed scheme, the Base Station does not need to use several unitary matrices to broadcast pilot symbol. Actually, only one broadcasting operation is needed. Each subscriber generates several virtual equivalent channels with a set of pre-saved unitary matrices and the channel status information gained from the broadcasting operation. The signal-to-interference and noise ratio (SINR) of each beam in each virtual equivalent channel is calculated and fed back to the base station for the weighting matrix selection and multi-user scheduling. According to the theoretical analysis, the proposed scheme relatively expands the transmitting phase and reduces the interactive complexity between the Base Station and subscribers. The asymptotic analysis and the simulation results show that the proposed scheme improves the throughput performance of the multi-user MIMO system.

• Journal of Korea Port Economic Association
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• v.39 no.3
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• pp.123-140
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• 2023

Maritime transportation is one of the oldest means of transportation utilized by mankind, and it has significantly contributed to the advancement of civilization by efficiently transporting bulk cargo at a low cost. The study aim to identify the factors influencing the selection of shipping companies in the bulk shipping market and provide insights for improving the competitiveness of shipping-related companies. To achieve this goal, the Analytic Hierarchy Process (AHP) was employed. For the empirical analysis, previous research, interviews, and a pilot test were conducted to identify five top-level factors such as companies, vessels, operations, services, and transaction factors. Each top-level factor has four sub-factors. The results of the analysis, based on 80 valid questionnaires, are as follows: Firstly, in the selection of shipping companies, the priority of factors influencing the choice of shipping companies was as follows: vessel factors were the most important, followed by company, operations, relationship, and service factors. Secondly, when investigating the priority of sub-factors, the availability/appropriateness of vessels was the most crucial factor, followed by company characteristics, financial soundness, and the company's reputation in order. The implications of these findings suggest that shipowners should focus on securing more suitable vessels and enhancing their reputation in response to shippers' demand. Shippers, on the other hand, should consider maintaining a healthy financial structure as a crucial task in securing competitive shipping service providers.

• Geophysics and Geophysical Exploration
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• v.7 no.1
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• pp.51-55
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• 2004

This paper presents a fast and stable imaging scheme using the localized nonlinear (LN) approximation of integral equation (IE) solutions for inverting electromagnetic data obtained in a crosswell survey. The medium is assumed to be cylindrically symmetric about a source borehole, and to maintain the symmetry a vertical magnetic dipole is used as a source. To find an optimum balance between data fitting and smoothness constraint, we introduce an automatic selection scheme for a Lagrange multiplier, which is sought at each iteration with a least misfit criterion. In this selection scheme, the IE algorithm is quite attractive for saving computing time because Green's functions, whose calculation is a most time-consuming part in IE methods, are repeatedly re-usable throughout the inversion process. The inversion scheme using the LN approximation has been tested to show its stability and efficiency, using both synthetic and field data. The inverted image derived from the field data, collected in a pilot experiment of water-flood monitoring in an oil field, is successfully compared with that derived by a 2.5-dimensional inversion scheme.

• Clean Technology
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• v.28 no.1
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• pp.79-93
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• 2022

In this study, an electronics industrial wastewater activated sludge model (e-ASM) to be used as a Water Digital Twin was calibrated based on real high-tech electronics industrial wastewater treatment measurements from lab-scale and pilot-scale reactors, and examined for its treatment performance, effluent quality prediction, and optimal process selection. For specialized modeling of a high-tech electronics industrial wastewater treatment system, the kinetic parameters of the e-ASM were identified by a sensitivity analysis and calibrated by the multiple response surface method (MRS). The calibrated e-ASM showed a high compatibility of more than 90% with the experimental data from the lab-scale and pilot-scale processes. Four electronics industrial wastewater treatment processes-MLE, A2/O, 4-stage MLE-MBR, and Bardenpo-MBR-were implemented with the proposed Water Digital Twin to compare their removal efficiencies according to various electronics industrial wastewater characteristics. Bardenpo-MBR stably removed more than 90% of the chemical oxygen demand (COD) and showed the highest nitrogen removal efficiency. Furthermore, a high concentration of 1,800 mg L^-1 T MAH influent could be 98% removed when the HRT of the Bardenpho-MBR process was more than 3 days. Hence, it is expected that the e-ASM in this study can be used as a Water Digital Twin platform with high compatibility in a variety of situations, including plant optimization, Water AI, and the selection of best available technology (BAT) for a sustainable high-tech electronics industry.

• Journal of the Korean Society for information Management
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• v.33 no.3
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• pp.239-262
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• 2016

This study aims to explore ways to improve self-censorship tendency in teacher librarians by identifying factors that influence the self-censorship which appears during collection development in elementary school libraries. For this purpose, first, we examined the concept of self-censorship through a review of related literature, then carried out a series of in-depth interviews as a pilot study to develop a questionnaire, which was used for a questionnaire survey. Finally, the survey data was analyzed statistically with SPSS 21.0, a statistical package. As a result, we have discovered statistically significant relationships between self-censorship and the characteristics in collection development policies, school library committees, and the complaints related with the library collections. Based on these results, the factors on the self-censorship were identified in the perception of the school librarians. Based on these results, we suggest to reinforce the function of review and approval of book selection in the school library committee, developed and approved a collection development policy include guidelines for dealing with users' complaints related to library collection, and stipulated a regulation for school library operation to remove inappropriate books from the library collection.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.31 no.4
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• pp.521-530
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• 2021

Objectives: This was to examine and explore the elements of Size Korea 6th 3D head anthropometric database and to provide basic information for the selection of respirators in Korea. Methods: This was a pilot study for the first year of work in a two-year-project initiated at KOSHA in 2021. 3D head dimensions data were obtained from the Size Korea Center managing the Size Korea 6th 3D national anthropometry survey databases. The 3D head dimensions data, including 45 dimensions, were used in line with ISO standards (e.g., ISO/TS 16976-2) for examinations, comparisons, statistical analyses, etc. Results: A total of 3,088 subjects were finally determined in this study. The main features were: Male subjects were 52.5%; the highest age group was 15-29 at 36.7%; unhealthy weight group based on BMI was 31.7%; and survey area was the capital region. For the 6th 3D head dimensions data with 45 items, the means and standard deviations for 'Face length' were 115.9±7.5 cm for males and 107.3±6.9 cm for females respectively while those for 'Face width' item were not available since there was no such item in the data. Numerous findings were discussed accordingly. Conclusions: This study showed that there were likely requirements for improvements in the 6th 3D head anthropometric data as follows: Standardization of Korean and English terms; addition of head dimensions items missed in the Size Korea survey; and reliability of generalizability for subjects, suggesting that the study results can be used for further studies or improvement of respirator selection in Korea.