• Korean Journal of Agricultural and Forest Meteorology
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• v.25 no.3
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• pp.226-235
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• 2023

This study aimed to supplement the shortcomings of the Multiple-sensor-based Frost Observation System (MFOS). The developed frost observation system is an improvement of the existing system. Based on the leaf wetness sensor (LWS), it not only detects frost but also functions to predict surface temperature, which is a major factor in frost occurrence. With the existing observation system, 1) it is difficult to observe ice (frost) formation on the surface when capturing an image of the LWS with an RGB camera because the surface of the sensor reflects most visible light, 2) images captured using the RGB camera before and after sunrise are dark, and 3) the thermal infrared camera only shows the relative high and low temperature. To identify the ice (frost) generated on the surface of the LWS, a LWS that was painted black and three sheets of glass at the same height to be used as an auxiliary tool to check the occurrence of ice (frost) were installed. For RGB camera shooting before and after sunrise, synchronous LED lighting was installed so the power turns on/off according to the camera shooting time. The existing thermal infrared camera, which could only assess the relative temperature (high or low), was improved to extract the temperature value per pixel, and a comparison with the surface temperature sensor installed by the National Institute of Meteorological Sciences (NIMS) was performed to verify its accuracy. As a result of installing and operating the MFOS v2, which reflects these improvements, the accuracy and efficiency of automatic frost observation were demonstrated to be improved, and the usefulness of the data as input data for the frost prediction model was enhanced.

• Tunnel and Underground Space
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• v.33 no.5
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• pp.388-398
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• 2023

The changes in groundwater flow due to mining development act as a contributing factor to major issues such as ground subsidence, strength reduction and collapse. For the sustainable mining development, measures for dealing with fluctuations in seasonal underground water inflow, power losses, pump damage, and unexpected increases in inflow must be put in place. In this study, the aim is to identify the causes of underground seepage through the examination of hydrological connectivity between the study area and nearby limestone mine. A tracer tes for assessing subsurface connectivity has been planned. A variety of tracers, such as dyes and ions, were applied in lab test to select the optimal tracer material, and a hydrological model of the study area was implemented through field test. Finally, the hydrological connectivity between the external stream and underground water in the mine was analyzed.

• Korean Journal of Agricultural and Forest Meteorology
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• v.25 no.3
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• pp.218-225
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• 2023

An agrivoltaic system (AVS) is a combined system that generates power through photovoltaic panels (PVPs) installed above a field where a crop is cultivated. Although soil moisture is an important limiting factor for open-field crop production, particularly during spring season in Korea, it is not well considered in the utilization of AVS. Indeed, the application of water-energy-food nexus on the AVS should be necessary. In this study, the changes of soil moisture and temperature under the AVS was investigated in fallow paddy field during spring season. The AVS that has partial shading condition by PV panels was decreased soil temperature and increased soil moisture compared to open-field. Furthermore, the maximum of the change in soil moisture to the change in soil temperature had a negative correlation both on open-field and AVS under wet condition. It represents that the micro-climate under the AVS is in energy-limited condition. The open-field of relatively high soil temperature was in water-limited condition. The different behavior of soil moisture on the AVS should be considered for the sustainable agricultural system as related to water-energy-food nexus.

• Korean Chemical Engineering Research
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• v.62 no.2
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• pp.163-172
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• 2024

In this study, two different scenarios for ammonia liquefaction in the green ammonia manufacturing process were proposed, and the economic-feasibility and environmental impact of each scenario were analyzed. The two liquefaction processes involved gas-liquid separation before cooling at high pressure (high pressure cooling process) or after decompression without the gas-liquid separation (low pressure cooling process). The high-pressure cooling process requires higher capital costs due to the required installation of separation units and heat exchangers, but it offers relatively lower total utility costs of 91.03 $/hr and a reduced duty of 2.81 Gcal/hr. In contrast, although the low-pressure cooling process is simpler and cost-effective, it may encounter operational instability due to rapid pressure drops in the system. Environmental impact assessment revealed that the high-pressure cooling process is more environmentally friendly than the low-pressure cooling process, with an emission factor of 0.83 tCO₂eq less than the low-pressure cooling process, calculated based on power usage. Consequently, the outcomes of this study provide relevant scenario and a database for green ammonia synthesis process adaptable to various process conditions.

• Journal of the Korean Association of Geographic Information Studies
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• v.27 no.2
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• pp.61-77
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• 2024

The purpose of this study was to develop a method for rapidly diagnosing urban thermal comfort using Unmanned Aerial Vehicle (UAV) based data. The research was conducted at Changwon National University's College of Engineering site and Yongji Park, both located in Changwon, Gyeongsangnam-do. Baseline data were collected using field measurements and UAVs. Specifically, the study calculated field measurement-based thermal comfort indices PET and UTCI, and used UAVs to create and analyze vegetation index (NDVI), sky view factor (SVF), and land surface temperature (LST) images. The results showed that UAV-predicted PET and UTCI had high correlations of 0.662 and 0.721, respectively, within a 1% significance level. The explanatory power of the prediction model was 43.8% for PET and 52.6% for UTCI, with RMSE values of 6.32℃ for PET and 3.16℃ for UTCI, indicating that UTCI is more suitable for UAV-based thermal comfort evaluation. The developed method offers significant time-saving advantages over traditional approaches and can be utilized for real-time urban thermal comfort assessment and mitigation planning

• Journal of the Korean Society of Marine Environment & Safety
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• v.30 no.1
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• pp.108-117
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• 2024

In this study, simulations based on computational fluid dynamics were performed for self-propulsion performance prediction of a catamaran that has asymmetrical inside and outside hull form and numerous knuckle lines. In the simulations, the Moving Reference Frame (MRF) or Sliding Mesh (SDM) techniques were used, and the rotation angle of the propeller per time step was different to identify the difference using the analysis technique and condition. The propeller rotation angle used in the MRF technique was 1˚ and those used in the SDM technique were 1˚, 5˚, or 10˚. The torque of the propeller was similar in both the techniques; however, the thrust and resistance of the hull were computed lower when the SDM technique was applied than when the MRF technique was applied, and higher as the rotation angle of the propeller per time step in the SDM technique was smaller in the simulations for several revolutions of the propeller to estimate the self-propulsion condition. The revolutions, thrust, and torque of the propeller in the self-propulsion condition obtained using linear interpolation and the delivered power, wake fraction, thrust deduction factor, and revolutions of the propeller obtained using the full-scale prediction method showed the same trend for both the techniques; however, most of the self-propulsion efficiency showed the opposite trend for these techniques. The accuracy of the propeller wake was low in the simulations when the MRF technique was applied, and slight difference existed in the expression of the wake according to the rotation angle of the propeller per time step when the SDM technique was applied.

• The Journal of the Convergence on Culture Technology
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• v.10 no.1
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• pp.217-226
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• 2024

This study is a descriptive research study to figure out the effect of unstable an adult attachment, self-mercy and emotional recognition clarity on interpersonal skills targeting nursing freshman. From 27th of March 2023 to 7th of April 2023, data gathered from the nursing freshman of university in J city, G province were analyzed. Using IBM SPSS/25, the data was analyzed descriptive statistic t-test, ANOVA and multiple correlation analysis. Interpersonal skills have negative correlation with unstable adults attachment(r=-.19, p=.005), and also have positive correlation with self-mercy (r=.38, p<.001) and emotional recognition clarity (r=.28, p<.001). Using hierarchical multiple regression analysis of factors that effects on interpersonal skills of survey subjects, self-mercy was the factor predict one's interpersonal skills the most, extroverted, mixed and emotional recognition clarity in order. The higher self- mercy and emotional recognition clarity are, the bigger influences interpersonal skills have and 24.5% of explanatory power. For nursing school students, interpersonal skills was one of the essential qualities so various methods to improve their interpersonal skills should be figured out.

• Nuclear Engineering and Technology
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• v.55 no.12
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• pp.4447-4464
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• 2023

This paper focuses on the development of a new computational model of the CNESTEN's TRIGA Mark II research reactor using the 3D continuous energy Monte-Carlo code TRIPOLI-4 (T4). This new model was developed to assess neutronic simulations and determine quantities of interest such as kinetic parameters of the reactor, control rods worth, power peaking factors and neutron flux distributions. This model is also a key tool used to accurately design new experiments in the TRIGA reactor, to analyze these experiments and to carry out sensitivity and uncertainty studies. The geometry and materials data, as part of the MCNP reference model, were used to build the T4 model. In this regard, the differences between the two models are mainly due to mathematical approaches of both codes. Indeed, the study presented in this article is divided into two parts: the first part deals with the development and the validation of the T4 model. The results obtained with the T4 model were compared to the existing MCNP reference model and to the experimental results from the Final Safety Analysis Report (FSAR). Different core configurations were investigated via simulations to test the computational model reliability in predicting the physical parameters of the reactor. As a fairly good agreement among the results was deduced, it seems reasonable to assume that the T4 model can accurately reproduce the MCNP calculated values. The second part of this study is devoted to the sensitivity and uncertainty (S/U) studies that were carried out to quantify the nuclear data uncertainty in the multiplication factor k_eff. For that purpose, the T4 model was used to calculate the sensitivity profiles of the k_eff to the nuclear data. The integrated-sensitivities were compared to the results obtained from the previous works that were carried out with MCNP and SCALE-6.2 simulation tools and differences of less than 5% were obtained for most of these quantities except for the C-graphite sensitivities. Moreover, the nuclear data uncertainties in the k_eff were derived using the COMAC-V2.1 covariance matrices library and the calculated sensitivities. The results have shown that the total nuclear data uncertainty in the k_eff is around 585 pcm using the COMAC-V2.1. This study also demonstrates that the contribution of zirconium isotopes to the nuclear data uncertainty in the k_eff is not negligible and should be taken into account when performing S/U analysis.

• The Journal of the Convergence on Culture Technology
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• v.10 no.3
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• pp.267-278
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• 2024

This study was a descriptive research study targeting medical students to determine the impact of self-directed learning ability, self-regulated learning, and communication ability on self-efficacy in performing medical treatment. This study randomly selected medical students from Region J, located in Province G, as the approximate population, and a total of 125 copies were finally analyzed. Descriptive statistics were analyzed using t-test, ANOVA, correlation, and multiple regression analysis using IBM SPSS/25. Self-efficacy in performing medical treatment was related to self-directed learning ability (r=.61, p<.001), self-regulated learning (r=.50, p<.001), and communication ability (r=.33, p<.001). There was a positive correlation with all of them. As a result of analyzing the variables that affect the subject's self-efficacy in performing medical treatment using hierarchical multiple regression, self-directed learning ability was found to be the factor that best predicts self-efficacy in performing medical treatment, followed by self-regulated learning and communication ability. The total explanatory power was 46.6%. Acquiring specialized knowledge and becoming a doctor after graduation through clinical practice and acquiring the basic clinical practice skills necessary to successfully perform one's duties are important tasks that medical students must accomplish. Therefore, in order to improve medical students' self-efficacy in performing medical treatment, the importance of improving health care, major satisfaction, and life satisfaction must be recognized and managed. In addition, efforts to develop programs and improve systematic systems that can improve self-directed learning, self-regulated learning, and communication skills should also be supported.

• The Journal of the Convergence on Culture Technology
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• v.10 no.5
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• pp.557-567
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• 2024

This study was a descriptived research study to determine the impact of empathy, communication competence, and personality on college adaptation among nursing students attending a university in City Y. The research method was a self-administered survey targeting 200 nursing students at a university in Y City, and data were collected from April 29, 2024 to May 27, 2024. The research statistical method used was the SPSS/WIN 25.0 statistical program, and was analyzed using t-test, one-way analysis of variance, Pearson correlation, and multiple regression analysis. In the correlation between each variable, college adaptation is related to empathy(r=.522, p<.001), communication competence(r=.557, p<.001), and personality(r=.561, p<.001). And as a result of regression analysis, as a factor affecting the subjects' college adaptation, second-year students(β=-.148, p=.013) had a higher level of college adaptation than first-year students(β=-.297, p<.001). Additionally, the level of college adaptation was high in the order of empathy(β=.295, p<.001), personality(β=.230, p<.001), and communication competence(β=.157, p=.050), and the explanatory power was 47.6%(Adj R2=.476, p<.001). Therefore, in order for nursing students to adapt to college, various psychological and emotional supports must be provided at the school and department level, and various customized programs that can improve empathy, communication competence, and personality should be developed and applied by considering the characteristics of nursing students by grade.