• The Journal of the Korea institute of electronic communication sciences
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• v.18 no.6
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• pp.1143-1150
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• 2023

The global climate crisis and the implementation of low-carbon policies have led to a growing interest in renewable energy and a growing number of related industries. Among them, solar power is attracting attention as a representative eco-friendly energy that does not deplete and does not emit pollutants or greenhouse gases. As a result, the supplement of solar power facility is increasing all over the world. However, solar power is easily affected by the environment such as geography and weather, so accurate solar power forecast is important for stable operation and efficient management. However, it is very hard to predict the exact amount of solar power using statistical methods. In addition, the conventional prediction methods have focused on only short- or long-term prediction, which causes to take long time to obtain various prediction models with different prediction horizons. Therefore, this study utilizes a many-to-many structure of a recurrent neural network (RNN) to integrate short-term and long-term predictions of solar power generation. We compare various RNN-based very short- and long-term prediction methods for solar power in terms of MSE and R² values.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.34 no.1
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• pp.30-35
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• 2024

In order to improve the efficiency of the water splitting system for hydrogen production, the high overvoltage in the electrochemical reaction caused by the catalyst in the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) must be reduced. Among them, transition metal-based compounds are attracting attention as catalyst materials that can replace precious metals such as platinum that are currently used. In this study, nickel foam, an inexpensive metal porous material, was used as a support, and Fe-doped β-Ni(OH)₂ microcrystals were synthesized through a hydrothermal synthesis process. In addition, in order to improve OER properties, changes in the shape, crystal structure, and water splitting characteristics of Fe-Mo co-doped β-Ni(OH)₂ microcrystals synthesized by co-doping with Mo were observed. The changes in the shape, crystal structure, and applicability as a catalyst for water splitting were examined.

• Journal of Aerospace System Engineering
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• v.18 no.1
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• pp.53-63
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• 2024

Adopting an engine igniter with high efficiency and ignition performance is essential for reliable operation of liquid rocket engines. In this study, we developed a spark torch igniter for a 450 N-scale methane-oxygen liquid rocket engine by conducting numerical analyses, igniter manufacturing and validation. Specifically, we conducted a parametric study for maximizing the enthalpy at the igniter exit, specifically by adjusting the mass flow rate, nozzle area ratio, fuel-oxidizer mixture ratio, and the igniter length-to-diameter. The heat transferred via the igniter nozzle exit was computed using 3-dimensional numerical simulations. We also manufactured and tested the igniter based on a deduced design to confirm ignition performance of the designed spark torch igniter. The igniter developed through this study could contribute to the development of practical propulsion systems such as upper-stage engines of small launch vehicles.

• Health Policy and Management
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• v.34 no.1
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• pp.17-25
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• 2024

Background: This study aimed to assess the appropriate allocation of emergency medical beds across 17 provinces and presume the economic benefits associated with such allocation. Methods: To estimate the optimal allocation of emergency medical beds by province, data from the Statistics Korea's "cause of death statistics (2014-2021)," regional statistics on "area, population, gender, age," and "population projections" were utilized. The "number of emergency beds by city and district" provided by the Health Insurance Review and Assessment Service was also used. In estimating the economic benefits of preventing avoidable emergency deaths due to the expansion of emergency medical facilities, guidelines from the Korea Development Institute and the Korea Transport Institute were referenced to calculate the wage loss costs associated with emergency deaths and estimate the economic benefits. Results: The optimal ratio of emergency medical beds allocation by region was highest in Gyeonggi, Seoul, Gyeongnam, Gyeongbuk, and Busan, while Daejeon, Jeju, and Sejong showed lower ratios. Additionally, the prevention of avoidable deaths and economic benefits resulting from the increase in emergency medical facilities were highest in Gyeonggi, Seoul, Gyeongbuk, Gyeongnam, and Busan. However, when standardized by population, the prevention of avoidable deaths and economic benefits were analyzed to be highest in Gyeongbuk, Chungnam, Jeonnam, Gyeongnam, and Busan. Conclusion: The results of this study can serve as foundational data for future policy measures aimed at addressing the imbalance in the supply of emergency medical facilities across regions. Considering regional characteristics in the distribution of emergency medical facilities is expected to ultimately increase the efficiency of national finances and yield economic benefits.

• Pediatric Infection and Vaccine
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• v.31 no.1
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• pp.94-101
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• 2024

Purpose: Coronavirus disease 2019 (COVID-19) has posed a significant burden to infant and toddler's care globally, while the disease severity is generally mild in this age group. In this study, we aimed to assess epidemiological and clinical aspects of COVID-19 in infants and toddlers in Seoul, South Korea. Methods: We used Seoul Metropolitan Government's epidemiological investigation database to describe the epidemiological and clinical characteristics of COVID-19 in infants and toddlers, between March 2020 to December 2021. Results: A total of 5,025 infants and toddlers aged <5 years was diagnosed between the observed period. 2,720 (54.1%) had symptoms, and fever was the most common symptom in 1,941 (74.1%). Of the diagnosed cases, 96.4% did not have underlying diseases. In a district level, extended opening of childcare facility was associated with increased risk of COVID-19 in infants and toddlers. Conclusions: An efficient monitoring system, resembling routine clinical care, is crucial, considering the low rates of severe progression and fatality among infants and toddlers. Moreover, a well-grounded intervention based on scientific evidence, rather than unconditional closures, is necessary to establish a suitable childcare policy that ensures safety from infectious diseases while not overlooking the developmental aspects of social skills.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.11 no.4
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• pp.165-171
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• 2006

This is the research to prepare a purification program for relatively less polluted stream by using phytoremediation. We calculated a treatment amount of nutrients followed by growth of Helianthus annuus (a kind of sunflower), setting up the plant reactor in the hothouse. Moreover, to investigate a field applicability, we could find increased contents of nitrogen, carbon and hydrogen in plants by setting up a H. annuus planted artificial floating island in an irrigation canal. When we changed the dissolved inorganic nitrogen(DIN) concentration of the influent from 28.5 to 199.2 mg/l and the dissolved inorganic phosphorus(DIP) concentration of the influent from 13.3 to 25.4 mg/l, growth disorder has not appeared though it is much higher than the criterion of water for irrigation. In this case, the removal rate of DIN was $81.7\sim98.6%$, and that of DIP was $81.9\sim98.4%$ in 3 days stay on average. It has appeared that the efficient hydraulic retention time(HRT) was 48 hours. The following contents of nitrogen, carbon and hydrogen of H. annuus appeared in the artificial floating island: nitrogen was $3.2\sim7.8%$ in the trunk and $3.0\sim6.3%$ in the root. Carbon was $40.1\sim57.7%$ in the trunk and $43.4\sim53.8%$ in the root.

• Journal of The Korean Association For Science Education
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• v.26 no.3
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• pp.330-341
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• 2006

This study investigated whether science museum field trips over a duration of 7 months would effect student preference and awareness of science museums. 32 eighth and ninth graders were sampled from a middle school in Seoul and asked about their preference, awareness and the effect of the science museum visits both before and after a field trip. Findings showed a preference for science museums which dealt with themes and topics of student interest. After a field trip, student responded that science museums were information providers which yielded opportunity to explore forthcoming science feats, science in everyday life, developmental histories of science and technology, science-related news, social issues, and science rationale. Even though science museums in Korea leave much to be desired in terms of quantity and quality, field trips were positively received by students. This reception and its usefulness implied that expansion publizing and active use of formal/informal education relating to science museum facilities need to be top-priority business.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.15 no.1
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• pp.25-35
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• 2010

The biodiversity of eukaryotic plankton has commonly been used to evaluate the status of aquatic ecosystems. Therefore, an accurate and rapid method for species identification is needed to reveal the biodiversity of environmental water samples. To date, molecular methods have provided a great deal of information that has enabled identification of the hidden biodiversity in environmental samples. In this study, we utilized environmental polymerase chain reaction (PCR) and constructed the 18S nuclear ribosomal RNA clone library from environmental water samples in order to develop more efficient methods for species identification. For the molecular analysis, water samples were collected from the Seonakdong River (Gimhae Bridge) and the coast of Namhae，(Namhaedo). Colony PCR and restriction fragment length polymorphism of PCR (PCR-RFLP) were then adopted to isolate unique clones from the 18S rDNA clone library. Restriction fragment length polymorphism pattern analysis of the Gimhae Bridge sample revealed 44 unique clones from a total of 60 randomly selected clones, while analysis of the Namhae sample revealed 27 unique clones from 150 clones selected at random. A BLAST search and subsequent phylogenetic analysis conducted using the sequences of these clones revealed hidden biodiversity containing a wide range of taxonomic groups (Heterokontophyta (7), Ciliophora (23), Dinophyta (1), Chytridiomycota (1), Rotifera (1) and Arthropoda (11) in the Gimhae Bridge samples Ciliophora (4), Dinophyta (3), Cryptophyta (1), Arthropoda (19) in the Namhae samples). Therefore, the molecular monitoring method developed here can provide additional information regarding the biodiversity and community structure of eukaryotic plankton in environmental samples and helps construct a useful database of biodiversity for aquatic ecosystems.

• Journal of The Korean Association For Science Education
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• v.26 no.3
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• pp.317-329
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• 2006

In this research, a questionnaire was developed to investigate high school students' viewpoints, originating from science history, on 'motion of on object', the subjects were seventy- five 10th grade students and sixty-five 11th grade students. Results found that the highest percentage among the types of 10th grade students' thoughts was related to the Middle Ages 'Impetus' viewpoints. Percentages of 11th grade students' thoughts were highest for Middle Ages and Newton views. These results provided proof that the development of student thoughts' based on science history' are consistent with school year. Furthermore, student thought regarding 'object motion' under the conditions of no force, vacuum, or air under a weightless stage were related to progressive viewpoints on science history. However, the percentage of thoughts related to earlier viewpoints were considerable. Student thoughts on parabolic motion, circle motion, and conservation amount of motion were found to be highly significant in similarity to the viewpoints of Galilei, Descartes, and Huygens; view cultivated before Newton. Consequently, this study determined that educational efficiency could be raised by providing historically more progressive views to cope with conflictory student thoughts-thoughts related to past views in science history.

• Journal of Life Science
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• v.34 no.6
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• pp.377-384
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• 2024

Prodigiosin is a red pigment characterized by a common pyrrolylpyrromethane skeleton. It is produced by Serratia marcescens, Vibrio psychroerythrus, Hahella chejuensis, etc. Prodigiosin has been reported to possess anticancer, immunosuppressant, antifungal antimalarial, and algicidal activities. However, despite prodigiosin's diverse range of activities, its production rate is significantly low and biosynthesis conditions are difficult. Consequently, the selling price is high, and its usability is limited. This study aimed to increase the efficiency of prodigiosin production according to the culture conditions of Serratia. In this study, a bacterial strain PDGS¹²⁰⁹¹⁵ producing prodigiosin was isolated from lightly contaminated stream water in Busan and identified as a strain of Serratia sp. based on 16S rDNA gene sequence analysis and physiological characteristics. The reddish pigment from PDGS¹²⁰⁹¹⁵ was directly extracted using acidified ethanol, and a characterization analysis confirmed that it was a prodigiosin compound. The optimal conditions for pigment production were 25℃, pH 7, and 0% NaCl concentration for a duration of 14 hr. Furthermore, by treating carbon and nitrogen sources, such as fructose and beef extract, respectively, prodigiosin production increased approximately six-fold and four-fold. Among the minerals tested, 0.1% KCl was found to be the most effective for prodigiosin production. Moreover, casein was identified as the most suitable source for prodigiosin production.