• Journal of the Korean Geotechnical Society
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• v.22 no.5
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• pp.47-57
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• 2006

The shear wave velocity is related with the stiffness of granular skeleton and mass density. The shear stiffness of the granular skeleton remains unaffected by the presence of the fluid. Bender elements are convenient shear wave transducers for instrumenting soil cells due to optimal soil-transducer coupling. This study addresses the principles of the shear wave, the design and implementation of bender elements including electromagnetic coupling prevention, directivity, resonant frequency, detection of first arrival, and near field effects. It is shown that electromagnetic coupling effects can be minimized using parallel-type bender elements. Thus, the in-plane S-wave directivity is quasi-circular. The resonant frequency of bender element installations depends on the geometry of the bender element, the anchor efficiency and the soil stiffness. One of the most cumbersome parts in the bender element test is near field effects, which affect the selection of arrival time. The selection of the first arrival within the near field Is effectively solved by the multiple reflection technique and signal matching technique. Bender elements, which requires several considerations, may be effective tools for the subsurface characterization by using S-wave.

• Journal of the Korean Geotechnical Society
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• v.22 no.10
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• pp.101-110
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• 2006

In general, environment-induced vibration propagates from the center of source to the destination through ground. In fact, the mechanism of wave propagation is highly dependent on the ground conditions, and various methods to protect structures from such a ground vibration have been proposed. The method of wall barrier has been frequently used to cut off ground vibration effectively. However, the capability of wall barrier may be affected by various factors like constituent material of it. Therefore, it is important to figure out appropriate material for the wall barrier. This study is focused on the effect of EPS on the vibration protection. Centrifuge model tests were performed. Two types of models such as a cylindrical and a rectangular wall were used. For the cylindrical type of wall, installation depth was changed, while the length of the wall varied fur the rectangular type to figure out the capability of vibration protection.

• Journal of Drive and Control
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• v.20 no.2
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• pp.40-46
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• 2023

Fresh corn, one of the main food crops, must be harvested by hand. A harvest mechanization technology is required. In this study, a tractor-attached harvester was designed and manufactured to sequentially perform stem reaping, fresh corn detaching, and collecting. The(harvester was designed so that the main device could operate through a hydraulic pump and a generator could be operated through the tractor's PTO. Factor tests were conducted according to cultivars (Ilmichal, Super sweet corn) and working speed (0.12 m/s, 0.17, 0.22). After the factor test, detached corns ratio, collected corns ratio, and damaged corns ratio were analyzed and harvest performance was evaluated. Harvesting performance was good for super sweet corn. Considering operation efficiency, 0.22 m/s was judged to be an appropriate working speed. It was found that it took two hours to work an area of 10 a.

• Knowledge Management Research
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• v.24 no.1
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• pp.223-243
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• 2023

RPA is implemented through management policy and enforced in mandatory environments to enhance performance and efficiency in various fields. However, the success of RPA implementation depends on the level of active engagement from organization members, even in a mandatory setting. This study identifies perceived ease of use, usefulness, accountability, perceived risk, and self-efficacy as variables that influence conative use behavior, which consists of reflective secondary factors such as immersion, reinvention, and learning. Data was collected from 207 office workers in various industries who have experience with RPA to test the proposed research model. The structural equation was verified using SPSS 20.0 and SmartPLS 4.0, and the analysis showed that all the proposed variables had a significant impact on conative use behavior. Our research findings provide theoretical and practical implications in knowledge management, enabling companies that implement RPA to recognize and address factors that encourage their members to actively use RPA.

• Journal of the Korea Society of Computer and Information
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• v.14 no.8
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• pp.97-106
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• 2009

ABEEK, an independent non-governmental organization, is the recognized accreditor for the educational programs in engineering and related disciplines. ABEEK has developed the standard accreditation criteria to meet diverse needs of the engineering and related communities in Korea. A student attending at the accredited program has to complete the required courses and elective courses according to the curriculum flowchart to meet the accreditation criteria for a bachelor. Therefore an efficient and effective tool is necessary to support the adviser to monitor the completion of the required courses and elective courses according to the curriculum flowchart. In this paper, we describe an adviser tool developed. To develop an adviser tool. we established databases which contain the information of courses and their relations according to the curriculum flowchart. Adviser tool was developed to analyze student's DegreeAudit and represent the current completion information on the curriculum flowchart for effective monitoring. A closed test was performed and showed the increase of efficiency to meet the accreditation criteria for a bachelor.

• Wind and Structures
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• v.34 no.3
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• pp.275-290
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• 2022

Mobile sand barriers are a new type sand-retaining structure that can be moved and arranged according to the engineering demands of sand control. When only used for sand trapping, mobile sand barriers could be arranged in single row. For the dual purposes of sand trapping and sand stabilization, four rows of mobile sand barriers can be arranged in a staggered form. To reveal the effect of plane layout, the included angle between sand barrier direction and wind direction on the characteristics of flow fields and the sand control laws of mobile sand barriers, numerical computations and wind tunnel tests were conducted. The results showed that inflows deflected after passing through staggered arrangement sand barriers due to changes in included angle, and the sand barrier combination exerted successive wind resistance and group blocking effects. An analysis of wind resistance efficiency revealed that the effective protection length of staggered arrangement sand barriers approximately ranged from the sand barrier to 10H on the leeward side (H is sand barrier height), and that the effective protection length of single row sand barriers roughly ranged from 1H on the windward side to 20H on the leeward side. The distribution of sand deposit indicated that the sand interception increased with increasing included angle in staggered arrangement. The wind-breaking and sand-trapping effects were optimal when included angle between sand barrier direction and wind direction is 60°-90°.

• Computers and Concrete
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• v.31 no.5
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• pp.457-468
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• 2023

Buildings, bridges, and dams are examples of civil infrastructure that play an important role in public life. These structures are prone to structural variations over time as a result of external forces that might disrupt the operation of the structures, cause structural integrity issues, and raise safety concerns for the occupants. Therefore, monitoring the state of a structure, also known as structural health monitoring (SHM), is essential. Owing to the emergence of the fourth industrial revolution, next-generation sensors, such as wireless sensors, UAVs, and video cameras, have recently been utilized to improve the quality and efficiency of building forensics. This study presents a method that uses a target-based system to estimate the dynamic displacement and its corresponding dynamic properties of structures using UAV-based video. A laboratory experiment was performed to verify the tracking technique using a shaking table to excite an SDOF specimen and comparing the results between a laser distance sensor, accelerometer, and fixed camera. Then a field test was conducted to validate the proposed framework. One target marker is placed on the specimen, and another marker is attached to the ground, which serves as a stationary reference to account for the undesired UAV movement. The results from the UAV and stationary camera displayed a root mean square (RMS) error of 2.02% for the displacement, and after post-processing the displacement data using an OMA method, the identified natural frequency and damping ratio showed significant accuracy and similarities. The findings illustrate the capabilities and reliabilities of the methodology using UAV to evaluate the dynamic properties of structures.

• Physical Therapy Korea
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• v.30 no.2
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• pp.92-101
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• 2023

Background: Stroke is one of the causes affecting gait and balance. Taping is considered an effective method for improving balance and gait in stroke patients. Numerous studies have confirmed the functional effects of taping in stroke patients. However, there is still no consensus regarding the use of taping to improve gait and balance. Objects: The purpose of this review was to investigate the effects of taping on the balance and gait of patients with stroke through meta-analysis of studies. Methods: PubMed, Medline, Embase, Web of Science, Cochrane Review, RISS, DBPia, and Science on were used to collect articles on Kinesio and non-elastic taping. The key terms were "Stroke", "Hemiplegia", "Taping", "Tape", "Balance", and "Gait" with cut-off of October, 2022. Taping group was compared with control groups with sham, placebo, and no taping. The outcome measures included the Berg Balance Scale (BBS), Timed Up and Go (TUG) test, and gait speed (cm/s). Eighteen studies (524 patients) were selected for the meta-analysis. Results: Overall, taping improved balance and gait in stroke patients, and Kinesio and non-elastic taping had similar effect sizes. Taping improved the BBS and TUG, and was most effective on gait speed. Contrary to the expectation that a longer duration of taping would be more affective, taping was most effective when the total taping duration was shorter than 500 minutes. In addition, the effect size of taping was greater when it was simultaneously attached to multiple locations. Conclusion: This meta-analysis supports the use of taping to improve gait and balance in stroke patients, and provides guidelines for the location, duration, and type of tape to increase taping efficiency.

• International Journal of Industrial Entomology and Biomaterials
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• v.46 no.2
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• pp.34-40
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• 2023

As agricultural production increases due to population growth, agricultural by-products that are generated at all production stages increase commensurately. Black soldier fly (BSF) (Hermetia illucens) treatment has potential as an environmentally friendly process to combat the environmental pollution caused by agricultural by-products. This study examined the utilization of BSF larvae in the decomposition of the by-products of apples and mandarins, fruits commonly produced in South Korea. The BSF test larvae were fed apple pomace or mandarin waste, and the control larvae were fed calf feed. Larval weight and size were measured at 4-day intervals until larvae reached the pre-pupal stage. Larval development time, survival rate, and BSF fecundity rate were calculated for all three substrates. Waste reduction and bioconversion ratios were also calculated. The developmental time of larvae fed with apple pomace and mandarin waste was greater than that of the control larvae. The average weight of larvae fed with the fruit by-products was less than that of the control. There was no significant difference in the survival rate of BSF larvae or the fecundity rate of BSF between the substrates used in this study. BSF larvae decomposed 48.0% and 61.5% of apple pomace and mandarin waste, respectively. The bioconversion efficiency rates of BSF larvae fed with apple pomace and mandarin waste were 9.1% and 12.1%, respectively. These results indicated that decomposition of single fruit by-products by BSF larvae is an environmentally friendly and effective bioconversion process.

• Nuclear Engineering and Technology
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• v.55 no.5
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• pp.1763-1774
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• 2023

In this study, a series of flexible neutron/gamma shielding composites are fabricated through the doping of Gd₂O₃ into the matrix of SEBS with (M_Gd2O3: M_SEBS) % from 5% to 100%. Neutron transmittance test shows an exponential attenuation with the increase of areal density of Gd, in which the transmittance T ranges from 59.1440% to 35.3026%, with standard deviation less than 2.2743%, mass attenuation coefficient 𝜇_m from 0.3194 cm²/g to 0.4999 cm²/g, and half value layer-HVL value from 2.4530 mm to 1.1313 mm. Shielding efficiency of the Gd₂O₃/SEBS composites is basically improved in comparison with that of B₄C/SEBS. The transmittance T, mass/linear attenuation coefficient 𝜇_m and 𝜇, HVL and effective atomic number Z_eff for the shielding of γ rays (39 keV, 59 keV and 122 keV) are measured and calculated with XCOM as well as MCX programs. Finally, plots of the three dimensional relationships between transmittance, doping amount and thickness are provided to the guidance for engineering shielding design. In summary, the Gd₂O₃/SEBS composite is proved to be an effective flexible neutron/low energy γ rays shielding material, which could be of potential applications in the field of nuclear technology and nuclear engineering.