• Wind and Structures
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• v.37 no.3
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• pp.191-209
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• 2023

This work investigates the subcritical free-shear prism wake at Re=22,000 by the Koopman analysis using the Dynamic Mode Decomposition (DMD) algorithm. The Koopman model linearized nonlinearities in the stochastic, homogeneous anisotropic turbulent wake, generating temporally orthogonal eigen tuples that carry meaningful, coherent structures. Phenomenological analysis of dominant modes revealed their physical interpretations: Mode 1 renders the mean-field dynamics, Modes 2 describes the roll-up of the Strouhal vortex, Mode 3 describes the Bloor-Gerrard vortex resulting from the Kelvin-Helmholtz instability inside shear layers, its superposition onto the Strouhal vortex, and the concurrent flow entrainment, Modes 6 and 10 describe the low-frequency shedding of turbulent separation bubbles (TSBs) and turbulence production, respectively, which contribute to the beating phenomenon in the lift time history and the flapping motion of shear layers, Modes 4, 5, 7, 8, and 9 are the relatively trivial harmonic excitations. This work demonstrates the Koopman analysis' ability to provide insights into free-shear flows. Its success in subcritical turbulence also serves as an excellent reference for applications in other nonlinear, stochastic systems.

• International conference on construction engineering and project management
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• 2013.01a
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• pp.592-595
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• 2013

Advent of Wireless Sensor Networks (WSN) has provided potentials to a variety of construction applications. It is well appreciated that WSNs have advantages over traditional wired system, such as ease of installation and maintenance with increased cost savings and efficiencies. However, the obstruction of wireless signal from physical objects in the heterogeneous construction environment often brings challenges to WSN measurement system. This paper analyzed the obstruction characteristic of construction environment where construction materials, equipment, and built structures obstruct the wireless signal yielding negative effect of measurement system. By adopting evaluation criteria, such as packet reception rate, field experiments have been implemented to quantitatively identify the interference of wireless signal from penetration, reflection, and network traffic under the construction environment. The results show that reliable performance of wireless sensor in construction environment depends on the optimal separation distance between a receiver and a transmitter, obstruction types, obstruction thickness, and transmission interval. In addition, the methodology and experimental results of this paper could be used in the practical design of network topology when hundreds of sensor nodes form a mesh network in the large scale construction applications.

• Nuclear Engineering and Technology
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• v.56 no.7
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• pp.2641-2649
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• 2024

Effective management of slightly used nuclear fuel (SUNF) is crucial for both technical and public acceptance reasons. SUNF management, radiotoxicity risk, and associated financial investment and technological capabilities are major concerns in nuclear power production. Reducing the volume of SUNF can simplify its management, and one possible solution is utilizing small modular reactors (SMR) and advanced fuel designs like those with thorium. This research focuses on studying the neutronic performance and radionuclide inventory of three different thorium fuel configurations. The mass of fissile material in thorium-based fuel significantly impacts Kinf, burn-up, and neutron energy spectrum. Compared to uranium, thorium as a fuel produces far fewer transuranic elements and less long-lived fission products (LLFPs) at the end of the core cycle (EOC). However, certain fission product elements produced from thorium-based fuel exhibit higher radioactivity at the beginning of the core cycle (BOC). Physical separation of thorium and uranium in the fuel block, like seed-and-blanket units (SBU) and duplex fuel designs, generate less radioactive waste with lower radioactivity and longer cycle lengths than homogeneous or mixed thorium-uranium fuel. Furthermore, the SBU and duplex feel designs exhibit comparable neutron spectra, leading to negligible differences in SUNF production between the two.

• Journal of the Korean Data and Information Science Society
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• v.20 no.5
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• pp.845-855
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• 2009

The purpose of this study was to examine the category function, the item structure, and the model-data fit of the Copenhagen neck functional disability scale (CNFDS) with neck pain subjects using Rasch rating scale analysis. The data was obtained from the assessments of 71 college students with neck pain. The 'concentration' item showed misfit and fourteen items were founds to be fits for self-reporting of disability due to neck pain. The most difficult item of the remaining 14 items was 'help' and the easiest item was 'social contact'. The subjects and items reliability of separation reliability were 0.85 and 0.97. The CNFDS for self-reporting of disability due to mild neck pain has been proved valid and reliable. This study is suggested that individuals with mild neck pain may be used the modified CNFDS that were not included 'concentration' item and were adjusted the 2 response levels.

• Journal of Korean society of Dental Hygiene
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• v.10 no.5
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• pp.877-885
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• 2010

Objectives : This study was carried out with the aim of utilizing it as basic data in a plan for oral health promotion by analyzing oral-health awareness in high school students of some districts in our country, and by analyzing physical, mental and social influential factors in oral health, through using OHIP(Oral Health Impact Profile). Methods : It surveyed by carrying out self-administered questionnaire research targeting 536 boy & girl high school students in the 1st and the 2nd grade at 3 high schools in some districts of Gyeonggi Province. Results : 1. As for experience of having not visited dental clinic, a case of having not visited accounted for 32.5%. On the other hand, a case of having visited accounted for 67.5%. As for the appearance of oral health education, only 2.8% responded as saying of having experience. 97.2% responded as saying of having not taken oral health education. 2. As for oral health state perceived by oneself, the response as saying of 'thinking it to be healthy' and that 'there is something wrong' showed the distribution of 34.1% that is the same ratio. As for oral health interest, a case of having a little interest(58.4%) or of being so much interested(12.5%) showed 70.9%. A case of having no special interest(24.8%) or of having no interest at all(4.3%) showed the level of 29.1%.3. As for oral health knowledge, the toothbrushing knowledge was the highest with 4.54 marks out of 6-point perfection. The toothbrush knowledge(4-point perfection) showed low point with 2.05 marks. 4. By gender, a case of men was high in OHIP(Oral Health Impact Profile) for the functional restriction and physical pain. On the other hand, in the remaining sphere, women were indicated to be high in OHIP. The statistically significant difference was indicated in the spheres such as physical pain, psychological discomfort, a drop in psychological ability, a drop in social ability, and social separation. 5. According to oral health state perceived by oneself, a case of thinking it to be healthy was indicated to be high in OHIP for every sphere. A case of thinking it to have gum disease was indicated to be low in OHIP for every sphere. The statistically significant difference was indicated in every sphere except the sphere of functional restriction. 6. As for a factor of having influence upon OHIP according to oral health knowledge, it was indicated that the higher toothbrush knowledge leads to having more influence upon OHIP. Conclusions : It could be known that the oral health knowledge and OHIP are varied as well according to the oral health interest level. Also, the oral health education proper for subjects is not being performed. Even as for frequency of visiting the dentist, a regular visit is failing to be made. In consideration of these points, the diversified and effective educational program is likely considered to be necessarily developed and improved that subjects can have more interest in oral health.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.9 no.1
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• pp.13-25
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• 1998

Aim：We think that the most important etiology in parent abuse is the psychodynamic and psychopathology in the family. So, we investigated the adolescents being admitted in SNMH, whose chief complaints were parent abuse. We were trying to explore families psychodynamic and psychopathology, especially mother-child interaction and to differentiate them in according to developmental psychopathology. Method：Our objects were the adolescent patients admitted in SNMH from 1987 to 1997 because they attacked parents verbally and physically. We examined 21 adolescents except those with psychosis, organic mental disorder, autism and mental retardation by means of interview or chart review. Result and Conclusion：The number of male patients was 14 and the number of female patients was 7. The most common diagnosis was conduct disorder and borderline personality disorder. The mean age was in the mid-teens. We observed 4 subgroups that were divided developmentally in object relation. 1) Symbiotic group with mother：(1) They did not separate and remain in symbiotic relationships with their mothers based on insecure attachment. Fathers were abscent emotionally and physically, and their mothers were prominent in close relationships with the patients in their family , where as the patients were the only man in the family. Adolescents entered the second separation-individuation. They expressed anger and internal tension involved with the close attachment with their mothers and also attempted separation from their mothers through physically attacking them. (2) These patients had suffered from physical illness and developmental delay since birth. Therefore the parents overprotected their children. The children had persistent infantile omnipotence and fantasies of power, so they could not deal with unrealistic states, adapt to reality, and depended on their parents overtly. They easily acted out unless their demands were fulfilled. 2) Borderline personality disorder：We observed deficiencies in care taking. Their parents had personality problems and immaturity. They coulden’t help their children to be separated in the rapproachment phase. Their conflict about dependence-independence was revived in the second separation-individuation adolescent period. We understand parent abuse as an attempt to overcome the conflict. 3) Conduct disorder：They did not build up basic attachment with their parents. They think of their parents as only a means of fulfilling their needs. When patients’ need were not fulfilled and remained in a conflicted state, they attacked their parents, unable to control their aggressions and impulses.

• Applied Chemistry for Engineering
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• v.28 no.4
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• pp.420-426
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• 2017

Recently, solvent-resistant nanofiltration membranes have been studied for the separation of solvents or solutes using a molecular weight cut-off system of the polymer which is resistant to a specific solvent. Required conditions for these membranes must have are excellent physical properties and solvent resistance. Polybenzimidazole, which is known to be one of the most heat-resistant commercially available polymers, has an excellent inherent solvent resistance and it is even insoluble in stronger organic solvents when cross-linked. Therefore, in this study, the applicability of polybenzimidazole as a solvent resistant nanofiltration membrane was discussed. The membrane was fabricated using the non-solvent induced phase separation method and showed a suitable morphology as a nanofiltration membrane confirmed by field emission scanning electron microscopy. In addition, the permeance of the solvent in the presence or absence of cross-linking was investigated and the stability was also confirmed through long operation. The permeance test was carried out with five different solvents: water, ethanol, benzene, N, N-dimethylacetamide (DMAc) and n-methyl-2-pyrrolidone (NMP); each of the initial flux was $6500L/m^2h$ (water, 2 bar), $720L/m^2h$ (DMAc, 5 bar), $185L/m^2h$ (benzene, 5 bar), $132L/m^2h$ (NMP, 5 bar), $65L/m^2h$ (ethanol, 5 bar) and the pressure between 2 and 5 bar was applied depending on the type of membrane.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.38 no.1
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• pp.43-57
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• 2002

This paper introduces an analysis method to predicting the flow characteristic of flow field around otter board In order to develope a high performance model. In this experiment, it is used a numerical analysis of flow field through CFD(Computational Fluid Dynamic), PIV method in which quantitative, qualitative evaluation is possible. In this experiment, it is used PIV method with flow filed image around otter board in order to analysis of flow characteristic. The result compared flow pattern with analysis result through CFD and also measurement result of lift and drag force coefficient carried out in CWC(Circulating Water Channel). The numerical analysis result is matched well with experiment result of PIV in the research and it is able to verify In the physical aspect. The result is as follows ; (1) It was carried out visibility experiment using laser light sheet, and picture analysis through PIV method in order to analysis fluid field of otter-board. As a result, the tendency of qualitative fluid movement only through the fluid particle's flow could be known. (2) Since PIV analysis result is quantitative, this can be seen in velocity vector distributions, instantaneous streamline contour, and average vorticity distributions through various post processing method. As a result, the change of flow field could be confirmed. (3) At angle of attack 24$^{\circ}$ where It Is shown maximum spreading force coefficient, the analysis result of CFD and PIV had very similar flow pattern. In both case, at the otter-board post edge a little boundary layer separation was seen, but, generally they had a good flow (4) As the result of post processing with velocity vector distributions, instantaneous streamline contour and average vorticity distributions by PIV, boundary layer separation phenomenon started to happen from angle of attack 24$^{\circ}$, and from over angle of attack 28$^{\circ}$, it happen at leading edge side with the width enlarged.

• Journal of the Korean Institute of Landscape Architecture
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• v.39 no.5
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• pp.12-20
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• 2011

Parks and green spaces have various functions for improving urban physical and social environments. Urban parks and green space planning have been applied in this study for the purpose of enhancing the urban environment. The most popular method for urban parks and green space planning is incrementing the quantity of parks and green spaces. However, it may not be possible to designate new parks and green spaces in a large city because of the difficulty of obtaining land. This study explores how urban parks and green space planning produces better quality urban environments without having to designate new parks and green spaces. The study evaluates existing parks and green spaces according to the satisfaction of the users. This evaluation could be a useful tool for those planning urban parks and green space systems. The study was performed in Tama Newtown, Japan, within two districts with two distinct characteristics of park systems: concentration and equality arrangement forms. For comparison, on-site questionnaires were used, with 319 residents in the area responding to the study. The data was collected and analyzed, using t-test, factor analysis, and multiple regression methods. The study found there was no difference in satisfaction factors be tween the two districts. However, differences were found within each of the districts, depending on parks and green space components. For example, the quality of green space was the most important factor for the district with a planned concentration arrangement form of parks and green spaces, but, separation of the pedestrian and vehicular systems was the most important factor in the district with a planned equality arrangement form of park system. Factors affecting the satisfaction of parks and green spaces that were common between the two sites were: accessibility, quality of park, quality of green space, and separation of pedestrian and vehicular traffics.

• Journal of Korea Water Resources Association
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• v.38 no.7 s.156
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• pp.517-526
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• 2005

In Korea, the methods of estimating groundwater recharge can categorized into two groups. One is baseflow separation method by means of groundurater recession curve, the other is water level fluctuation method by using the data from groundwater monitoring wells. Baseflow separation method is based on annual recharge and lumped concept, and water-table fluctuation method is largely dependent on monitoring wells rather than water budget in watershed. However, groundwater recharge rate shows the spatial-temporal variability due to climatic condition, land use and hydrogeological heterogeneity, these methods have various limits to deal with these characteristics. For this purpose, the method of estimating daily recharge rate with spatial variability based on distributed rainfall-runoff model is suggested in this study. Instead of representative recharge rate of large watershed, the subdivided recharge rate with heterogeneous characteristics can be computed in daily base. The estimated daily recharge rate is an advanced quantity reflecting the heterogeneity of hydrogeology, climatic condition, land use as well as physical behaviour of water in soil layers. Therefore, the newly suggested method could be expected to enhance existing methods.