• Journal of the Korean Institute of Gas
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• v.8 no.2 s.23
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• pp.15-27
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• 2004

The purpose of this paper is to improve the performance of Polymer electrolyte fuel cell(PEMFC) by studying the channel dimension of bipolar plates using commercial CFD program 'Fluent'. Simulations are done ranging from 0.5 to 3.0mm for different size in order to find the channel size which shoves the highst hydrogen consumption. The results showed that the smaller channel width, land width, channel depth, the higher hydrogen consumption in anode. When channel width is increased, the pressure drop in channel is decreased because total channel length Is decreased, and when land width is increased, the net hydrogen consumption is decreased because hydrogen is diffused under the land width. It is also found that the influence of hydrogen consumption is larger at different channel width than it at different land width. The change of hydrogen consumption with different channel depth isn't as large as it with different channel width, but channel depth has to be small as can as it does because it has influence on the volume of bipolar plates. however the hydrogen utilization among the channel sizes more than 1.0mm which can be machined in reality is the most at channel width 1.0, land width 1.0, channel depth 0.5mm and considered as optimum channel size. The fuel cell combined with 2cm${\times}$2cm diagonal or serpentine type flow field and MEA(Membrane Electrode Assembly) is tested using 100W PEMFC test station to confirm that the channel size studied in simulation. The results showed that diagonal and serpentine flow field have similarly high OCV and current density of diagonal (low field is higher($2-40mA/m^2$) than that of serpentine flow field under 0.6 voltage, but the current density of serpentine type has higher performance($5-10mA/m^2$) than that of diagonal flow field under 0.7-0.8 voltage.

• Korean Journal of Heritage: History & Science
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• v.44 no.4
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• pp.56-69
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• 2011

A Gamsil is an ritual instrument which enshrine the ancestral tablets of four lines from late great-great-grandfather and grandmother to late father and mother. This has their soul. Juja's "Garye" informs its structure pattern. It is placed in Sadang and takes the form of a perfectly square box. It partitions four rooms and enshrine an ancestral tablet room by room. They get the ancestral tablets line up from west to east. And they also enshrine the ancestral tablets without his descendant together in Gamsil. A Gamsil is a space to enshrine the ancestral tablets and to place an order within a family. A social status and A family economic power become a standard in making and managing Sadang. Kingdom in Joseon period limited the ancestral tablets considering of his degree of official rank which descendant enshrined. A official servant can be stable economically in getting a stipend and build sadang in the house. While household a little in economic enshrine the ancestral tablets at a Gamsil placed at the a space of private home. His personal circumstances make size and pattern, place change in relation to Gamsil. A Gamsil looks like house in structure and pattern. It has the immortality of the soul. And it changed from a table size to a ancestral tablet size. This Gamsil is comfortable to move and is made considering of the width and height of household. The transition of Gamsil means institutions is in close to a family economic power in social change. Kingdom in Joseon early period makes a policy of a Gamyo's build and an ancestral enshrine in basement of Juja's "Garye". The transition of Gamsil gave a common people limitted socially and institutionally the service of late four lines. Most of people enshrine the ancestral tablets of their four lines in approaching of in the late of Joseon Dinasty. They compromise on their reality and cause. The transition of Gamsil implied many different things in social ; the authenticity search and a dignity expression of his family, the foundation for the diffusion of an ancestral service, a space sharing with ancestor and descendent, the increment of a family economic power etc.

• Journal of the Korea Institute of Building Construction
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• v.22 no.6
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• pp.651-662
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• 2022

The electrochemical impedance spectroscopy(EIS) method was used to evaluate the concrete deterioration process related to chloride-induced steel corrosion with various corrosion levels(initiation, rust propagation and acceleration periods). The impressed current technique, with four total current levels of 0C, 13C, 65C and 130C, was used to accelerate steel corrosion in concrete cylinder samples with w/c ratio of 0.4, 0.5, and 0.6, immersed in a 0.5M NaCl solution. A series of EIS measurements was performed to monitor concrete deterioration during the accelerated corrosion test in this study. Some critical parameters of the equivalent circuit were obtained through the EIS analysis. It was observed that the charge transfer resistance(R_c) dropped sharply as the impressed current increased from 0C to 13C, indicating a value of approximately 10kΩcm². However, the sensitivity of R_c significantly decreased when the impressed current was further increased from 13C to 130C after corrosion of steel had been initiated. Meanwhile, the double-layer capacitance value(C_dl) linearly increased from 50×10^-6μF/cm² to 250×10^-6μF/cm² as the impressed current in creased from 0C to 130C. The results in this study showed that monitoring C_dl is an effective measurement parameter for evaluating the progress of internal concrete damages(de-bonding between steel and concrete, micro-cracks, and surface-breaking cracks) induced by steel corrosion. The findings of this study provide a fundamental basis for developing an embedded sensor and signal interpretation method for monitoring concrete deterioration due to steel corrosion at various corrosion levels.

• Journal of Korean Home Economics Education Association
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• v.34 no.4
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• pp.143-161
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• 2022

The aim of this study is to identify the learning performance of online classes using problem-based learning(PBL) for clothing and textiles majors in college with the increased use of online learning tools after the COVID-19 pandemic. In order to achieve this goal, the PBL was developed and applied to the 'Fashion Marketing and Merchandising' class conducted in real-time online at University in North Chungcheong Province, Korea for four weeks. After a four-week PBL class, a survey was conducted on 35 students in the 'Fashion Marketing and Merchandising' class and the 35 completed questionnaires were used for analysis. The measurement tools of this study were self-directed learning, cooperative learning ability, problem-solving ability, and learning achievement regarded as an important learning effect in PBL class. In addition, students' self-reflective essays were also analyzed to examine the educational effect of PBL applying online classes. As a result of this study, bivariate correlations among the four variables, students' self-directed learning, cooperative learning ability, problem-solving ability, and learning achievement were significantly positive. Furthermore, the results of multiple regression analysis showed that the three independent variables had significant effects on students' perceived learning achievement, in the order of cooperative learning ability, self-directed learning, and problem-solving ability. The students' self-reflective essays indicated that problem-based learning worksheet was helpful for identifying problems, and clarifying what they already and what they need to study more. Based on this study, it could be recommended that online class applying PBL could contribute to the improvement of student's learning performance.

• Journal of the Korean Institute of Landscape Architecture
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• v.51 no.2
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• pp.28-41
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• 2023

The objective of the study was to develop an Urban Windway Forest Creation Planning Technique for the Improvement of the Urban Environment using the case of Daejeon Metropolitan City. Through a spatial analysis of fine dust and heat waves, a basin zone, in which the concentration was relatively serious, was derived, and an area with the potential of cold air flow was selected as the target area for the windway forest development by analyzing the climate and winds in the relevant zone. Extreme fine dust areas included the areas of the Daejeon Industrial Complex Regeneration Business District in Daedeok-gu and Daedeok Techno Valley in Yuseong-gu. Heat wave areas included the areas of Daedeok industrial Complex in Moksang-dong, the Daejeon Industrial Complex Regeneration Business District in Daehwa-dong, and the high-density residential area in Ojeong-dong. As a result of measuring the wind speeds in Daejeon with an Automatic Weather System, the average wind speeds during the day and night were 0.1 to 1.7 m/s,, respectively. So, a plan of for a windway forest that smoothly induces the movement of cold air formed in outer forests at night is required. The fine dust/heat wave intensive management zones of Daejeon Metropolitan City were Daejeoncheon, Yudeungcheon, Gapcheon-Yudeungcheon, and Gapcheon. The windway forest formation plan case involved the old city center of Daejeon Metropolitan City among the four zones, the Gapcheon-Yudeungcheon area, in which the windway formation effect was presumed to be high. The Gapcheon-Yudeungcheon area is a downtown area that benefits from the cold and fresh air generated on Mt. Gyejok and Mt. Wuseong, which are outer forests. Accordingly, the windway forest was planned to spread the cold air to the city center by connecting the cold air generated in the Seosa-myeon forest of Mt. Gyejok and the Namsa-myeon forest of Mt. Wuseong through Gapcheon, Yudeungcheon, and street forests. After selecting the target area for the wind ventilation forest, a climate map and wind formation function evaluation map were prepared for the area, the status of variation wind profiles (night), the status of fine dust generation, and the surface temperature distribution status were grasped in detail. The wind ventilation forest planning concept and detailed target sites by type were identified through this. In addition, a detailed action plan was established according to the direction of creation and setting of the direction of creation for each type of wind ventilation forest.

• Journal of Life Science
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• v.33 no.2
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• pp.158-168
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• 2023

Natural products have been used to mitigate the effects of cancer and infectious diseases, as they feature diverse bioactivities, such as antioxidant, antibacterial, anti-inflammatory, and immunomodulatory effects. Here, we chose 10 natural products that are well-known as pulmonary enhancers and investigated their bactericidal effects on Streptococcus pneumoniae. In the disk diffusion assay, the growth of S. pneumoniae was significantly regulated by G. fructus treatment regardless of extraction method used. We first adopted spraying as a novel delivery method for G. fructus. Interestingly, mice exposed to G. fructus three times a day for 2 weeks were resistant to S. pneumoniae intranasal infection (shown both through body weight loss and survival rates compared to the control group). Moreover, we confirmed that exposure to G. fructus regulated the colonization of the bacteria despite the sustained inflammation in the lung after exposure to S. pneumoniae, indicating that migrated inflammatory immune cells may involve a host defense mechanism against pulmonary infectious diseases. While a similar number of granulocytes (CD11b⁺Ly6C⁺Ly6G⁺), neutrophils (CD11b⁺Ly6C^intLy6G⁺), and monocytes (CD11b⁺Ly6C^intLy6G^-) were found between groups, a significantly increased number of alveolar macrophages (CD11b⁺CD11c^hiF4/80⁺) was detected in BAL fluids of mice pre-exposed to G. fructus at 5 days after S. pneumonia infection. Taken together, our data suggest that this usage of G. fructus can induce protective immunity against bacterial infection, indicating that facial spray may be helpful in enhancing the defense mechanism against pulmonary inflammation and in evaluating the efficacy of natural products as immune enhancers against respiratory diseases.

• Korean Journal of Environment and Ecology
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• v.36 no.6
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• pp.639-650
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• 2022

Abeliophyllum distichum Nakai, a rare plant with distylous characteristics, is native to certain parts of the Korean Peninsula. It is registered on the IUCN Red List of Threatened Species as a globally endangered plant. This study was conducted to establish an appropriate local conservation management plan suitable for future A. distichum populations by comparing and analyzing the flowering characteristics and population size according to distyly based on the results of quantitative surveys in 14 regions, including 8 areas with native populations of A. distichum and 6 natural monument populations. The number of individuals appearing in each population group was surveyed, and the flowering individuals were identified by style as being either pin or thrum flower types as they were being examined and recorded on the site. In total, 13,130 individuals of A. distichum (7,003 flowering and 6,127 non-flowering individuals) were recorded, but the balance of the number of pin- and thrum-flowered individuals in each population was not significant (p<0.05), indicating an imbalanced state. In particular, the Yeongdong (YD) population was very disproportionate compared to other populations, suggesting that its genetic diversity was low and the possibility of inbreeding was high. The average flowering and fruiting rates by management unit were much higher in the natural monument populations (89.2% and 55.3%, respectively) than in the natural habitat populations (39.0% and 8.5%, respectively). It may be due to a difference in reproductive growth resulting from light inflow into the forest caused by the upper crown closure. The area of occupation (AOO) of A. distichum on the Korean Peninsula covered an area of 23,224.5 m². Although the natural monument population was smaller than the natural habitat population, its density was higher, likely as a result of the periodic management of natural monument populations, where the installation of protective facilities in certain areas restricts population spread. Conservation of A. distichum populations requires removing the natural monument populations suspected of anthropogenic and genetic disturbances and expanding the conservation priority population by designating new protected areas. Although the habitats of natural monument populations are managed by the Cultural Heritage Administration and local governments, there are no agencies that are responsible for managing natural habitat populations. Therefore, institutional improvement in the overall management of A. distichum should be prioritized.

• Analytical Science and Technology
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• v.20 no.4
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• pp.308-314
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• 2007

The analytical method of HPLC with the radial-flow electrochemical cell (RFEC) has been developed to determine doxorubicin, epirubicin, nogalamycin, daunorubicin and idarubicin simultaneously by employing a reversed-phase chromatography. Anthracyclines were detected at -0.74 V vs. a Ag/AgCl (0.01 M NaCl) reference electrode, a potential of diffusion current plateau in the mobile phase. At a $V_f$ of 1.0 mL/min doxorubicin, epirubicin, daunorubicin and idarubicin appeared at a retention time ($t_r$) of 6.4 min, 7.4 min, 12.7 min and 18.4 min, respectively, while at a $V_f$ of 0.6 mL/min, doxorubicin, epirubicin, nogalamycin, daunorubicin and idarubicin appeared at a $t_r$ of 9.9 min, 11.5 min, 13.5 min, 19.6 min and 28.7 min, respectively. The linearity between each anthracycline injected ($2.40{\times}10^{-7}M{\sim}1.42{\times}10^{-5}M$) and peak area (charge) was excellent with the square of the correlation coefficient ($R^2$) higher than 0.999. The detection limits were $1.0{\times}10^{-8}M{\sim}1.5{\times}10^{-7}M$ for the five anthracyclines. Within-day precision for the five anthracyclines were in reasonable relative standard deviations less than 3 % ($1.00{\times}10^{-6}M{\sim}1.42{\times}10^{-5}M$) except the lower concentrations less than $0.7{\mu}M$. Solid phase extractions of $1.00{\times}10^{-5}M$ epirubicin, $0.48{\times}10^{-5}M$ nogalamycin and $1.52{\times}10^{-5}M$ daunorubicin from human serum with a $C_{18}$ cartridge resulted in 97 %, 100 % and 90 % of recoveries, respectively.

• Korean Journal of Heritage: History & Science
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• v.56 no.3
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• pp.62-74
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• 2023

Much attention has been focused on the Baekpoman area due to the archaeological achievements of the past, but studies on prehistoric times when villages began to form is insufficient, and the Bronze Age village landscape was examined in order to supplement this. In the area of Baekpo Bay, the natural geographical limit connected to the inland was culturally confirmed by the distribution density of dolmens, and the generality of the Bronze Age settlement was confirmed with the Hwangsan-ri settlement. Bunto Village in Hwangsan-ri represents a farming-based village in the Baekpo Bay area, and the residential group and the tomb group are located on the same hill, and it is composed of three individual residential groups, and the village landscape had attached buildings used as warehouses and storage facilities. In the area of Baekpo Bay, it spread in the Tamjin River basin and the Yeongsan River basin where Songgukri culture and dolmen culture were integrated, and the density distribution of the villages was considered to correspond to the distribution density of dolmens. In order to examine the landscape of village distribution, the classification of Sochon-Jungchon-Daechon was applied, and it was classified as Sochon, a sub-unit constituting the village, in that the number of settlements constituting the village in the Bronze Age was mostly less than five. There are numerical differences between Jungchon and Daechon, and the distribution pattern does not necessarily coincide with the hierarchy. The three individual residential groups of Bunto Village in Hwangsan-ri are Jungchon composed of complex communities of blood relatives with each family community, and a stabilized village landscape was created in the Gusancheon area. In the area of Baekpo Bay, Bronze Age villages formed a landscape in which small villages were scattered around the rivers and formed a single-layered relationship. Dolmens (tombs) were formed between the villages and villages, and seem to have coexisted. Sochondeul is a family community based on agriculture, and it is believed that self-sufficient stabilized rural villages that live by acquiring various wild resources in rivers, mountains, and the sea formed a landscape.

• Journal of Service Research and Studies
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• v.14 no.1
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• pp.63-76
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• 2024

Multi-family housing plays a crucial role as a living and experiencing space, and its environment has a direct impact on the well-being and stability of its residents. Therefore, Crime Prevention Design (CPTED) for multi-family housing is of utmost importance. However, crime-related data in China is not disclosed to the public because of its specificity, making it difficult for researchers to conduct further in-depth studies based on accurate crime data. As a result, the establishment and application of CPTED theory in terms of crime prevention is limited and delayed. This study aims to explore three aspects of CPTED in multi-family housing as perceived by home-buying consumers. It investigated consumer perception of the CPTED, the importance of each element and ways to increase awareness of CPTED in multifamily housing in order to effectively improve multifamily crime prevention design principles and further enhance public safety. This study examined the current state and future trends of CPTED in China by analyzing relevant research reports and literature, aiming to gain insights into the crime prevention awareness of Chinese homeowners. In addition, a survey was conducted on Chinese consumers to unravel the importance of CPTED and increase awareness of its various elements in multifamily-family. This study used a Likert scale and SPSS reliability analysis to determine the cognitive status of multi-family CPTED, the importance of each element, and proposed an improvement plan based on the analysis results. As this study was limited by the difficulty of implementation and the lack of validation of its practical effectiveness, it is recommended that future research needs to validate the effectiveness of crime prevention designs and produce more practical results. Furthermore, it is crucial to utilize this study to inform the implementation of security solutions that are tailored to the unique characteristics of each district. Additionally, it is important to offer guidance on how to enhance community safety by increasing residents' awareness of security through education and information dissemination. The author hopes that the representative multi-family CPTED awareness, the importance of each element, and plans for improvement shall be summarized from this study, and provide foundational data for the future development of CPTED based on the Chinese region.