• Journal of the Computational Structural Engineering Institute of Korea
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• v.35 no.5
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• pp.299-308
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• 2022

This study was conducted to predict the tendency for heat exchange and boil-off gas (BOG) in a liquefied hydrogen tank under sloshing excitation. First, athe fluid domain excited by sloshing was modeled using a multiphase-thermal flow domain in which liquid hydrogen and hydrogen gas are in the saturated state. Both the the volume of fluid (VOF) and Eulerian-based multi-phase flow methods were applied to validate the accuracy of the pressure prediction. Second, it was indirectly shown that the fluid velocity prediction could be accurate by comparing the free surface and impact pressure from the computational fluid dynamics with those from the experimental results. Thereafter, the heat ingress from the external convective heat flux was reflected on the outer surfaces of the hydrogen tank. Eulerian-based multiphase-heat flow analysis was performed for a two-dimensional Type-C cylindrical hydrogen tank under rotational sloshing motion, and an inflation technique was applied to transform the fluid domain into a computational grid model. The heat exchange and heat flux in the hydrogen liquid-gas mixture were calculated throughout the analysis,, whereas the mass transfer and vaporization models were excluded to account for the pure heat exchange between the liquid and gas in the saturated state. In addition, forced convective heat transfer by sloshing on the inner wall of the tank was not reflected so that the heat exchange in the multiphase flow of liquid and gas could only be considered. Finally, the effect of sloshing on the amount of heat exchange between liquid and gas hydrogen was discussed. Considering the heat ingress into liquid hydrogen according to the presence/absence of a sloshing excitation, the amount of heat flux and BOG were discussed for each filling ratio.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.33 no.3
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• pp.166-171
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• 2022

Background and Objectives Vocal fold (VF) scar is known to be the most common cause of dysphonia after laryngeal microsurgery (LMS). Steroids reduce postoperative scar formation by inhibiting inflammation and collagen deposition. However, the clinical evidence of whether steroids are helpful in reducing VF scar formation after LMS is still lacking. The purpose of this study is to determine whether intralesional VF steroid injection after LMS helps to reduce postoperative scar formation and voice quality. Materials and Method This study was conducted on 80 patients who underwent LMS for VF polyp, Reinke's edema, and leukoplakia. Among them, 40 patients who underwent VF steroid injection after LMS were set as the injection group, and patients who had similar sex, age, and lesion size and who underwent LMS alone were set as the control group. In each group, stroboscopy, multi-dimensional voice program, Aerophone II, and voice handicap index (VHI) were performed before and 1 month after surgery, and the results were statistically analyzed. Results There were no statistically significant differences in the distribution of sex, age, symptom duration, occupation and smoking status between each group. Both groups consisted of VF polyp (n=21), Reinke's edema (n=11), and leukoplakia (n=9). On stroboscopy, the lesion disappeared after surgery, and the amplitude and mucosal wave were symmetrical on both sides of the VFs in all patients. Acoustic parameters and VHI significantly improved after surgery in all patients. However, there was no significant difference between the injection and control group in most of the results. Conclusion There was no significant difference in the results of stroboscopy, acoustic, aerodynamic, and subjective evaluation before and after surgery in the injection group and the control group.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.33 no.3
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• pp.172-178
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• 2022

Background and Objectives Injection laryngoplasty is a common method for treatment of unilateral vocal fold paralysis. Unilateral vocal fold paralysis has various causes, including idiopathic, infection, stroke, neurologic condition, surgery and nerve invasion by cancer. To the knowledge of the authors, there was no study on the relationship between the causes of vocal cord paralysis and the outcome of injection laryngoplasty. Therefore, we tried to investigate the difference in the outcomes of injection laryngoplasty between vocal cord paralysis after surgery group and nerve invasion by cancer group. Materials and Method A retrospective analysis was performed for 24 patients who underwent vocal cord injection due to unilateral vocal cord paralysis caused by surgery or nerve invasion by cancer. The objective quality of the voice was assessed by acoustic voice analysis with the Multi-Dimensional Voice Program. Results Both group showed an improvement of fundamental frequemcy (F0), jitter percent, shimmer (percent), and noise to hearmonic ratio (NHR) after injection laryngoplasty. The vocal cord paralysis due to nerve invasion group showed more improvement in both the mean and median value of F0, shimmer percent and NHR than the vocal cord paralysis due to surgery group, but there was not statistically significant. Conclusion Our study did not show a statistically significant difference in outcome between vocal cord paralysis due to cancer invasion group and surgery group, but statistically tendency was suggested. The vocal cord paralysis due to nerve invasion group showed more improvement in both the mean and median value of acoustic voice analysis than surgery group.

• Korean Chemical Engineering Research
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• v.61 no.1
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• pp.123-141
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• 2023

A sufficient amount of data with quality is needed for training artificial neural networks (ANNs). However, developing ANN models with a small amount of data often appears in engineering fields. This paper presented an ANN model to improve prediction performance of the ammonia emission amount with 83 data. The ammonia emission rate included eleven inputs and two outputs (maximum ammonia loss, N_max and time to reach half of N_max, K_m). Categorical input variables were transformed into multi-dimensional equal-distance variables, and 13 data were added into 66 training data using a generative adversarial network. Hyperparameters (number of layers, number of neurons, and activation function) of ANN were optimized using Gaussian process. Using 17 test data, the previous ANN model (Lim et al., 2007) showed the mean absolute error (MAE) of K_m and N_max to 0.0668 and 0.1860, respectively. The present ANN outperformed the previous model, reducing MAE by 38% and 56%.

• Journal of the Korean Geotechnical Society
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• v.23 no.12
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• pp.83-94
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• 2007

Piled raft foundations have been highlighted as an economical design concept of pile foundations in recent years. However, piled raft foundations have not been widely used in Korea due to the difficulty in estimating the complex interaction effects among rafts, piles and soils. The authors developed an effective numerical program to analyze the behavior of piled raft foundations for practical design purposes and presented it briefly in this paper. The developed numerical program simulates the raft as a flexible plate consisting of finite elements with eight nodes and the raft is supported by a series of elastic springs representing subsoils and piles. This study imported another model to simulate pile groups considering non-linear behavior and interaction effects. The apparent stiffnesses of the soils and piles were estimated by iterative calculations to satisfy the compatibility between those two components and the behavior of piled raft foundations can be predicted using these stiffnesses. For the verification of the program, the analysis results about some example problems were compared with those of rigorous three dimensional finite element analysis and other approximate analysis methods. It was found that the program can analyze non-linear behaviors and interaction effects efficiently in multi-layered soils and has sufficient capabilities for application to practical analysis and design of piled raft foundations.

• Journal of Christian Education in Korea
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• v.74
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• pp.57-80
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• 2023

The purpose of this study is to review the practicality of Christian education for sustainable development in a rapidly changing world. The first part of this study identify the concept, meaning, and direction of implementation of "Sustainable Development," which has been studied and published around UNESCO since the early 1980s, and present practical strategies for the sustainable development of Christian education. This study chronologically selected five major reports published by UNESCO--"Our Common Future"(1987), "Agenda 21"(1992), "UN Decade of Education for Sustainable Development 2005-2014"(2002), "Roadmap for Implementing the Global Action Programme for Education for Sustainable Development 2015-2019"(2014) and "Education for Sustainable Development 2030"(2020)--and examined the concept and meaning of "Sustainable Development"(SD). At the same time, in relation to "Education for Sustainable Development"(ESD), the occurrence, change, and implementation method of "Sustainable Development Goals"(SDGs) were examined and presented. This study derived three Christian educational implications necessary to properly establish the next generation of faith, based on a leadership development strategy using the concept of sustainable development, For the sustainability of Christian education, the foundation of education based on the correct biblical interpretation of cultural mandate is first examined, and then the need for curriculum development and class design is proposed using various types of indicators and educational modules. Finally, specific practices for the development of educational leadership to revitalize Christian education are presented through a multi-dimensional approach.

• The Journal of the Convergence on Culture Technology
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• v.9 no.2
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• pp.429-436
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• 2023

Traditional Chinese music has a deep indigenous color and has its own unique way of thinking and characteristics. A consensus has already been formed that linear thinking is a major feature of traditional Chinese music, and it has been implemented in both traditional multi-tone and single-tone music. It is mainly expressed in the form of single-tone music or single-tone music. This linear thought of traditional Chinese music is formed by influencing factors in various fields. For example, it is related to national culture, geographical and natural environment, religious and philosophical background, traditional Chinese notation, individual characteristics of traditional musical instruments, Yulje, composition, and transmission methods. This thinking is different from Western classical music that pursues three-dimensional thinking, and Western music emphasizes the harmony of harmony, harmony of tone and texture, logic and identity of structure, and emphasizes the aspect of space. However, traditional Chinese music emphasizes the horizontal development of melody, the fluency of ancestors, and the continuity of structure. We aims to analyze the causes of linear thinking of traditional Chinese music so that it can be more useful in educational aspects and promote the succession and development of traditional music by transferring knowledge of ethnic music.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.6B
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• pp.597-603
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• 2006

The purpose of this study is to improve the short term rainfall forecast skill using neural network model that can deal with the non-linear behavior between satellite data and ground observation, and minimize the flood damage. To overcome the geographical limitation of Korean peninsula and get the long forecast lead time of 3 to 6 hour, the developed rainfall forecast model took satellite imageries and wide range AWS data. The architecture of neural network model is a multi-layer neural network which consists of one input layer, one hidden layer, and one output layer. Neural network is trained using a momentum back propagation algorithm. Flood was estimated using rainfall forecasts. We developed a dynamic flood inundation model which is associated with 1-dimensional flood routing model. Therefore the model can forecast flood aspect in a protected lowland by levee failure of river. In the case of multiple levee breaks at main stream and tributaries, the developed flood inundation model can estimate flood level in a river and inundation level and area in a protected lowland simultaneously.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.3B
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• pp.301-310
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• 2006

Typically, we needs enormous national budget for the flood control project and so the project usually has big influence on the national economy. Therefore, the reliable estimation of flood damage is the key issue for the economic analysis of the flood control project. This study aims to provide a GIS based technique for distributed flood damage estimation. We consider two aspects of engineering and economic sides, which are the inundation analysis and MD-FDA (Multi-Dimensional Flood Damage Analysis), for the flood damage assessment. We propose the analysis framework and data processing using GIS for assessing flood damages. The proposed methodology is applied to the flood control channel project for flood disaster prevention in Mokgamcheon/Dorimcheon streams and this study presents the detailed GIS database and the assessment results of flood damages. This study may have the worth in improving practical usability of MD-FDA and also providing research direction for combining economic side with the engineering aspect. Also this distributed technique will help decision-making in evaluating the feasibility of flood damage reduction programs for structural and nonstructural measures.

• Journal of the Microelectronics and Packaging Society
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• v.30 no.3
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• pp.20-34
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• 2023

Single or multi-layered two-dimensional (2D) materials, with thicknesses in the order of a few nanometers, have garnered substantial attention across diverse research domains owing to their distinct properties, including electrical conductivity, flexibility, and optical transparency. These materials are frequently subjected to repetitive mechanical actions in applications like electronic skin (E-Skin) and smart textiles. Moreover, they are often exposed to external factors like temperature, humidity, and pressure, which can lead to a deterioration in component durability and lifespan. Consequently, significant research efforts are directed towards developing self-healing properties in these components. Notably, recent investigations have revealed promising outcomes in the field of self-healing composite materials, with Ti₃Ci₂Ti_x MXene being a prominent component among the myriad of available 2D materials. In this paper, we aim to introduce various synthesis methods and characteristics of Ti₃Ci₂Ti_x MXene, followed by an exploration of self-healing application technologies based on Ti₃Ci₂Ti_x MXene.