• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.2
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• pp.432-445
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• 1994

From a theoretical analysis point of view, the 2-stage precipitator is decomposed into two units: charging cell and collecting cell. Collection efficiency predictions of the two-stage parallel-plate electrostatic precipitator have been performed theoretically incorporating with the charging and the collecting cells. Particle trajectorise passing the charging cell have been modeled as a simple one. Particle charge distribution at the outlet of the charging cell is calculated through integration of the present unipolar combined charging rate along the entire particle trajectory, and average charge of particles at the outlet of the charging cell is obtained from the particle charge distribution. As for the collecting cell, the diminution of particle concentration along the longitudinal direction of the collecting cell is investigated considering the conventional Deutsch's theory and the laminar theory. One should note that the collection efficiency formula derived is based on monodisperse aerosols. It has been confirmed through the analysis that predictions of particle charge by applying White's unipolar diffusion charging theory overpredict actual cases in the continuum regime, while predictions by Fuch's unipolar diffusion charging theory indicate the reasonable result in the same regime. Theoretical predictions of collection efficiency are also compared with the available experimental results. Comparisons show that the experimental results are consistently located in the collection efficiency region bounded by the two limits, the Deutsch and the laminar collection efficiencies. Finally design parameters of the 2-stage electrostatic precipitator have been investigated systematically through the one-variable-at-a-time method in terms of collection efficiency. Applied voltages on the corona wire of the charging cell and the plate of the collecting cell, and the average air velocity have been selected as the design parameters.

• The Journal of Korean Physical Therapy
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• v.30 no.2
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• pp.73-77
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• 2018

Purpose: The prefrontal lobe, supplementary motor area, cerebellum, and basal ganglia are activated during gait. In addition, gait is controlled by nerves, such as the corticospinal tract (CST) and corticoreticular pathway (CRP). In this study, the presence of an injury to the CST and CRP was identified by diffusion tensor imaging and the characteristics of the gait pattern were investigated according to inferior cerebral artery infarction. Methods: One patient and six control subjects of a similar age participated. A 69-year-old female patient had an injury to the left basal ganglia, insular gyrus, corona radiata, dorsolateral prefrontal cortex, and postcentral gyrus due to an inferior cerebral artery infarction. Diffusion tensor imaging (DTI) data was acquired 4 weeks after the stroke. The kinematic and spatio-temporal parameters of gait were collected using a three-dimensional gait analysis system. Results: On 4 weeks DTI, the CST and CRP in the affected hemisphere did not show injury to the affected and unaffected hemisphere. Gait analysis showed that the cadence of spatio-temporal parameter was decreased significantly in the patient. The angle of the knee joint was decreased significantly in the affected and unaffected sides compared to the control group. Conclusion: The results of diffusion tensor imaging showed that although the patient was evaluated to be capable of an independent gait, the quality and quantity of gait might be reduced. This study could help better understand the gait ability analysis of stroke patients and the abnormal gait pattern of patients with a brain injury.

• Journal of The Korean Astronomical Society
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• v.50 no.4
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• pp.111-124
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• 2017

The environmental dependence of the morphology of dwarf galaxies in isolated satellite systems is analyzed to understand the origin of the dwarf galaxy morphology using the visually classified morphological types of 5836 local galaxies with $z{\leq}0.01$. We consider six sub-types of dwarf galaxies, dS0, dE, $dE_{bc}$, dSph, $dE_{blue}$, and dI, of which the first four sub-types are considered as early-type and the last two as late-type. The environmental parameters we consider are the projected distance from the host galaxy ($r_p$), local and global background densities, and the host morphology. The spatial distributions of dwarf satellites of early-type galaxies are much different from those of dwarf satellites of late-type galaxies, suggesting the host morphology combined with $r_p$ plays a decisive role on the morphology of the dwarf satellite galaxies. The local and global background densities play no significant role on the morphology of dwarfs in the satellite systems hosted by early-type galaxies. However, in the satellite system hosted by late-type galaxies, the global background densities of dE and dSph satellites are significantly different from those of $dE_{bc}$, $dE_{blue}$, and dI satellites. The blue-cored dwarf satellites ($dE_{bc}$) of early-type galaxies are likely to be located at $r_p$ > 0.3 Mpc to keep their cold gas from the ram pressure stripping by the hot corona of early-type galaxies. The spatial distribution of $dE_{bc}$ satellites of early-type galaxies and their global background densities suggest that their cold gas is intergalactic material accreted before they fall into the satellite systems.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.43 no.2
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• pp.165-174
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• 2017

This study reports a synthesis of an amphiphilic linear block copolymer consisting of a hydrophobic poly (lactide) (PLA) block and a hydrophilic hyperbranched polyglycerol (hbPG) block, PLA-b-hbPG. Simple chemical modification of the hbPG block with 4-hydroxycinnamic acid (CA) led to a photo-crosslinkable block copolymer, PLA-b-hbPG-CA. Nanosized micelles of the block copolyemrs were used as drug carriers for sustainable release. The hbPG shell made of a small molecular weight hbPG block showed excellent hydrophilicity, which can minimize in vivo toxicity. The UV-crosslinked PLA-b-hbPG-CA micelles loaded with drugs colud be served as a drug delivery carrier for its biocompatibility and self-assembled structures.

• Clinical and Experimental Reproductive Medicine
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• v.26 no.3
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• pp.399-405
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• 1999

Objective: In the preparation of ICSI, cumulus and corona cells should be removed from the oocytes by using a combination of enzymatic (hyaluronidase) and mechanical (pipetting) methods. But little is known about the effects of different degrees of oocyte denudation and incubation time between denudation and sperm injection on the outcomes of ICSI. The aim of this study was to evaluate the effects of varying the degrees of oocyte denudation and the lengths of incubation time from denudation to sperm injection on the outcomes of ICSI. Methods: In experiment 1, patients (oocytes) were grouped into group A and B according to the degree of denudation, complete and partial, respectively. In experiment 2, patients (oocytes) were grouped into group I, II and III according to the length of incubation time of denuded oocytes until sperm injection as < 1, $1{\sim}2$ and >2 hours, respectively. Results: There was no significant difference between the degree of oocyte denudation on the survival, fertilization and development rates after ICSI procedure. In case of the incubation time of denuded oocytes until ICSI, survival rates was higher in group III (83.1 %) than in group I (61.5%, p<0.05) or group II (64.3%). However no statistically significant differences were found between incubation time and fertilization or development rates. Conclusions: This study reveals that the outcomes of ICSI are not affected by the degree (complete or partial) of oocyte denudation. However, the denuded oocytes with incubation period of more than 2 hours show better outcomes of ICSI than those with the incubation period of less than 2 hours.

• Journal of the Korea Convergence Society
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• v.12 no.9
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• pp.205-214
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• 2021

The purpose of this Convergence study was to provide basic data to prevent and intervene in depression of the young adult by examining the effect of COVID-19 on depression in single-person households, focusing on gender differences. The research was conducted with 198 male and 218 female young adults were sampled from the Seoul Welfare Survey(2020) and data were analyzed through hierarchical regression analysis. As a result of the analysis, negative changes in employment, income, and emotions due to Corona significantly increased the level of depression among young people. And the effects of COVID-19 sub-factors were different between male and female. Based on result, clinical and policy implications were suggested for managing with depression among youth in our society in consideration of gender differences in crisis situations such as COVID-19.

• Journal of Korea Port Economic Association
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• v.37 no.2
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• pp.55-71
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• 2021

While major alliance container carriers in the post-corona era are enjoying the largest boom in history with their fleet reduction strategy, shippers companies are in a state of deteriorating import and export price competitiveness due to increased logistics costs, and forwarders who act for shipping companies' logistics services are also experiencing the burden of rising freight rates It is in a state of overheated competition and worsening profits for attracting shippers. For this purpose, research data, literature studies, statistical data and data from overseas specialized networks were used as prior research. Online surveys and telephone interviews were conducted, and as a result, four areas of cold chain (including perishable cargo), project logistics, UN procurement logistics, and dangerous goods logistics, which were found to be particularly in high demand, were analyzed to suggest entry strategies.

• Fire Science and Engineering
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• v.33 no.1
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• pp.23-29
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• 2019

Rechargeable battery such as lithium-ion battery has been noticed as a kinds of the energy storage system in the recent energy utilization and widely used actually in various small electronic equipment and electric vehicles. However, many thermal runaway caused battery accidents occurred recently, which still is obstacle for advanced application of lithium ion battery. One of the main differences to general fires is the existence of ionized electrolyte with electron during combustion. Therefore, we simply simulated the ion addition effects of battery fires by introducing an ionized fuel in jet diffusion flames. When the ionized methane through a corona discharge was used as fuel, the overall flame stability and shape such as flame length showed no significant difference from normal methane flame, but NOx and CO emissions measured at the post flame region decreased. The ion addition effect of methane oxidation was also numerically simulated with the modeling of hydrogen addition in the mixture. It was confirmed that the hydrogen addition at a fixed temperature had a similar effects on ionization of methane and hence could be modeled successfully.

• Journal of the Korea Society of Computer and Information
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• v.26 no.4
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• pp.239-245
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• 2021

Due to the fourth industrial revolution and the Corona19, the availability of digital devices such as kiosks is a matter directly related to survival for older adults with digital divide. This paper analyzes the problems of existing information service education for older adults and proposes an IT education strategy tailored to aging and life cycle of older adults. The proposed in this study is an educational application-based IT training method that supports repetitive learning regardless of time and place, developing kiosk function as a functional game-type educational application and experimenting with post-training effectiveness. The research method proposed UI usability evaluation frame for older adults, and developed educational applications based on proposed evaluation frame, and conducted kiosk education. As a result of the experiment, the mission success rate after using the IT application was 80.6%, which is a 55.1%P improvement compared to the pre-use(25.5%). This study confirmed that the proposed education for older adults is a way to overcome the limitations of existing IT education in the current situation.

• Journal of the Korea Society of Computer and Information
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• v.25 no.12
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• pp.271-278
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• 2020

This study looked at the World Martial Arts Mastership's 'non-face promotional media strategies and methods' after the Corona-19 fandom, and found out if they could be applied to other sports events. As a method of research, the promotional media strategy of martial arts mastership was divided into types and in-depth interviews with media agents were conducted. According to the study, hosting an online martial arts competition, building an untact convention platform, and a base education facility can be a successful contest with budget support. Martial arts branding, popularization and industrialization can be a new attempt if ideas and execution personnel are sufficient. If IT technology and Chungbuk martial arts infrastructure are combined, they will be able to pioneer a new model called 'non-face-to-face-to K-sports'.