• Journal of the Korean Solar Energy Society
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• v.39 no.4
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• pp.69-77
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• 2019

Among the main functions of the grid-connected photovoltaic (PV) system, the anti-islanding operation function is a very important problem. Recently, due to the improvement in power generation efficiency and the maintenance advantages in PV system, the use of string inverter has increased so that the possibility of islanding operation has been raised. Generally, when a power system faults, the PV inverter must be disconnected from power system within 10 cycles by the anti-islanding operation function. However, in the real-time of power system, the output power of the PV system within 10cycles is effected. In this paper, we analyzed the effect of grid-connected PV system on power quality in a short time within 10 cycles on fault case of power system using the Matlab Simulink program.

• Clinical and Experimental Pediatrics
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• v.61 no.12
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• pp.381-386
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• 2018

Purpose: The use of proper safety restraint systems by children is vital for the reduction of traffic accident-related injury and death. This study evaluated the rates of use of safety restraint systems and front seats by Korean children. Methods: Based on data from the National Health and Nutrition Examination Survey from 2008 to 2015, I investigated the frequencies of safety restraint systems and front seat use by children under six and 12 years of age, respectively. Results: The percentage of respondents who said they always use safety restraint systems increased from 17.7% in 2008 to 45.0% in 2015. The rate of children who did not use the front seats at all was 47.3 % in 2008 compared to 33.4% in 2015. Multivariate logistic regression analysis showed a decrease in safety-restraint-system use as age increased (odds ratio, 0.63; 95% confidence interval [CI], 0.51-0.77). The use rate of front-passenger seat belts by the mother is significantly correlated with the safety-restraint-system use rate by children (odds ratio, 2.14; 95% CI, 1.12-4.06). Conclusion: Although the rate of safety-restraint-system use for children is increasing annually, it remains low. Additionally, the use rate of front passenger seats for children is high. To reduce the rates of injury and death of children from traffic accidents, it is necessary to educate on the appropriate use of safety restraint systems according to age and body size and to develop stronger regulations.

• Transactions of the Korean hydrogen and new energy society
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• v.30 no.3
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• pp.251-259
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• 2019

The aim of this study is to evaluate the economic feasibility of domestic on-site steam methane reforming (SMR) hydrogen refueling stations. We evaluated the levelized cost of hydrogen (LCOH) for the SMR hydrogen refueling stations, which have production capacities of 100 kg/day (SMR 100), 200 kg/day (SMR 200), and 500 kg/day (SMR 500) utilizing the scale factor. The main results indicated that the LCOH of SMR 100, SMR 200, and SMR 500 were 14,367 won/kg, 11,122 won/kg, and 8,157 won/kg, if the utilizations of hydrogen stations were 70%. These results imply that the production capacity of the domestic SMR hydrogen station should be greater than 500 kg/day to compete with other hydrogen stations when we consider the current sale price of hydrogen at the hydrogen stations.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.35 no.10
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• pp.143-153
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• 2019

In this study, a full scale 3-axes shake table test for M-bar and T-bar type ceilings commonly used in the country was conducted. Through damage inspection during the test, seismic performance of ceilings according to variables, such as clearance between wall mold and ceiling as well as existence of facilities, was evaluated. A test frame consisted of square hollow section members was used for the shake table test. The experimental method was performed as a fragility test using required response spectrum described in ICC-ES AC156. In the case of architectural nonstructural component that contain ceilings, it mainly is evaluated the performance by post-test visual inspection. For the evaluation of seismic performance of ceilings, this study classified and defined damaged items for targeted ceiling system referring to illustrative damage according to nonstructural performance levels accordance with ASCE 41 and previous studies. And proposed illustrative damage items classification was utilized to compare the degree of the damage according to experimental variables. The experiment results confirmed that differences in boundary conditions due to the clearance at wall mold and the installation of facilities had a significant effect on the seismic performance of the ceiling.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.53 no.6
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• pp.942-953
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• 2020

Achieving optimal sustainable yields (i.e., avoiding overfishing and maximizing fishery harvest at the same time) is one of the main objectives in fisheries management. Generally, management reference points (MRPs) such as fishing mortalities (Fmsy, F0.1, Fx%) have been suggested for the purpose. In this study, we intended to suggest MRPs for Korea chub mackerel Scomber japonicus stock, using a stochastic catch-at-age model (SCAA) and evaluate whether the current fishing intensity on the stock is appropriate. We used length frequency and catch-per-unit-effort data on the Korea chub mackerel stock collected from the large purse-seine fishery, and yields landed by all fisheries from years 2000 - 2019. We calculated yield per recruit and spawning potential ratio, and projected spawning stock biomass (SSB) under different fishing mortality, assuming annual recruitments were solely controlled by environmental effects (i.e., steepness of 1.0). Some of our major findings and suggestions were that the overfishing threshold would be F46%; i.e., the fishing mortality in the terminal year, 2019 was 0.257/year, which corresponded to F46%.

• Journal of International Academy of Physical Therapy Research
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• v.12 no.2
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• pp.2370-2374
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• 2021

Background: Masticating is an activity that is free from temporal or spatial constraints, with an advantage that it can be combined easily with other treatment methods. While several studies have reported a positive effect of the intervention of chewing using the jaw on postural stability, only a few studies were conducted on stroke patients. Objectives: To investigated the effects of masticating chewing gum on the static and dynamic balancing of stroke patients. Design: Randomized cross-over study design. Methods: Nineteen stroke patients were randomly assigned to the chewing group or control group. BT4 was used to measure the static and dynamic balancing abilities. Pre-test measurements were taken before mastication of chewing gum, and post-test measurements were taken after 2 days. The stroke patients in the chewing group were guided to sit on a chair and chew gum for 3 min, and their balancing abilities were simultaneously measured. The balancing abilities of the control group patients were measured while they sat at rest without masticating chewing gum. Results: The chewing group showed significant increases in the measures of static balance (i.e., C90 area, trace length, X mean, and Y mean). In the between-group comparison, the measures of static balance were significantly higher in the chewing group than in the control group. Conclusion: These findings suggest that masticating chewing gum enhanced the static balancing ability of stroke patients. Thus, gum chewing should be considered a viable clinical intervention to control posture in stroke patients.

• The Journal of Korean Institute of Information Technology
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• v.17 no.9
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• pp.123-131
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• 2019

Social network service users actively express and share their feelings about social issues and content of interest through postings. As a result, the sharing of emotions among individuals and community members in social network is spreading rapidly. Therefore, resulting in active research of emotion analysis on posting of users. However, There is insufficient research on emotion analysis for postings containing various emotions. In this paper, we propose a method that analyzes the emotions of an Instagram posts using hashtags and images. This method extracts representative emotion from user posts containing multiple emotions with 66.4% accuracy and 81.7% recall, which improves the emotion classification performance compared to the previous method.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.26 no.4
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• pp.280-295
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• 2022

This paper contains an introduction to industrial problems, solutions, and results conducted with the Korea Association of Machinery Industry. The client company commissioned the problem of upgrading the method of identifying global supply risky items. Accordingly, the factors affecting the supply and demand of imported items in the global supply chain were identified and the method of selecting risky items was studied and delivered. Through research and discussions with the client companies, it is confirmed that the most suitable factors for identifying global supply risky items are 'import size', 'import dependence', and 'trend abnormality'. The meaning of each indicator is introduced, and risky items are selected using export/import data until October 2022. Through this paper, it is expected that countries and companies will be able to identify global supply risky items in advance and prepare for risks in the new normal situation: the economic situation caused by infectious diseases such as the COVID-19 pandemic; and the export/import regulation due to geopolitical problems. The client company will include in his report, the method presented in this paper and the risky items selected by the method.

• Journal of the Korean Society for information Management
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• v.40 no.3
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• pp.99-118
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• 2023

The objective of this study is to identify performance factors in the automatic classification of records by utilizing metadata that contains the contextual information of records. For this study, we collected 97,064 records of original textual information from Korean central administrative agencies in 2022. Various classification algorithms, data selection methods, and feature extraction techniques are applied and compared with the intent to discern the optimal performance-inducing technique. The study results demonstrated that among classification algorithms, Random Forest displayed higher performance, and among feature extraction techniques, the TF method proved to be the most effective. The minimum data quantity of unit tasks had a minimal influence on performance, and the addition of features positively affected performance, while their removal had a discernible negative impact.

• Journal of Veterinary Clinics
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• v.40 no.3
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• pp.189-196
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• 2023

This study was conducted to determine genetic diversities of Eimeria spp. detected from wildlife. From January 2020 to December 2021, molecular analysis was conducted for Eimeria spp. detected from wildlife rescued in Jeonbuk province, Korea. Polymerase chain reaction targeting 18 s rRNA gene for Eimeria spp. detected from 8 domestic pigeon (Columba livia domestica), 1 Oriental turtle dove (Streptopelia orientalis), 1 Eurasian eagle owl (Bubo bubo), 1 Azure-winged magpie (Cyanopica cyanus), 1 Moorhen (Gallinula chloropus), and 1 raccoon dog (Nyctereutes procyonoides) was conducted for phylogenetic analysis. Domestic pigeon and Oriental turtle dove were bound to the same cluster. In addition, carnivorous Eurasian eagle owl and poultry were bound to the same cluster. These results suggest that Eimeria spp. can be shared between similar species regardless of species along the food chain, suggesting that wild birds could be carriers of Eimeria spp. in Korea.