• Journal of Korea Water Resources Association
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• v.57 no.9
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• pp.571-583
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• 2024

Forecasting dam inflows in the medium to long term is crucial for effective dam operation and the prevention of water-related disasters such as floods and droughts. However, the increasing frequency of extreme weather events due to climate change has made hydrological forecasting more challenging. Since 2000, seasonal weather forecasts, which provide predictions for weather variables up to about seven months ahead, and their hydrological interpretation, known as Seasonal Flow Forecasts (SFFs) have gained significant global interest. This study utilises seasonal weather forecasts from the European Centre for Medium-Range Weather Forecasts (ECMWF), converting them into inflow forecasts using a hydrological model for 12 multipurpose dams in South Korea from 2011 to 2020. We then compare the performance of these SFFs with the Ensemble Streamflow Prediction (ESP). Our results indicate that while SFFs are more effective for short-term predictions of 1-2 months, ESP outperforms SFFs for long-term predictions. Seasonally, the performance of SFFs is higher in October-November but lower from December to February. Moreover, our findings demonstrate that SFFs are highly effective in quantitatively predicting dry conditions, although they tend to underestimate inflows under wet conditions.

• Explosives and Blasting
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• v.42 no.3
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• pp.38-48
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• 2024

This study is to evaluate the applicability of high-speed, high-pressure dynamic compression technology for the powder molding of talc. To achieve this, powder molding test was conducted using a self-developed high-speed, high-pressure dynamic compression device, and the results were analyzed. Additionally, the behavior characteristics of pyrophyllite powder particles under dynamic compression were analyzed using the PFC2D. Quantitative analyses, as well as mapping and point analyses, were conducted using the SEM on pyrophyllite from the Naju ceramic Mine and the Bugok mine. The results showed that the weight ratio of composed elements in both mines was in the order of oxygen > silicon > aluminum. A pyrophyllite powder solid with a diameter of 14.5 mm and a thickness of 3 mm was successfully produced using a high-speed, high-pressure dynamic compression device capable of generating an instantaneous compressive force with a 30 kgf projectile dropped from a height of 1.5 m in about 0.4 seconds. Numerical analysis of pyrophyllite powder using PFC2D analyzed that in the numerical model, the compression ratio was approximately 56%, and the porosity decreased from 16.0% to 1.0%, indicating almost no remaining pores.

• International Journal of Stem Cells
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• v.15 no.3
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• pp.311-323
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• 2022

Background and Objectives: Human mesenchymal stem cells (MSCs) are emerging as a treatment for atopic dermatitis (AD), a chronic inflammatory skin disorder that affects a large number of people across the world. Treatment of AD using human umbilical cord blood-derived MSCs (hUCB-MSCs) has recently been studied. However, the mechanism underlying their effect needs to be studied continuously. Thus, the objective of this study was to investigate the immunomodulatory effect of epidermal growth factor (EGF) secreted by hUCB-MSCs on AD. Methods and Results: To explore the mechanism involved in the therapeutic effect of MSCs for AD, a secretome array was performed using culture medium of hUCB-MSCs. Among the list of genes common for epithelium development and skin diseases, we focused on the function of EGF. To elucidate the effect of EGF secreted by hUCB-MSCs, EGF was downregulated in hUCB-MSCs using EGF-targeting small interfering RNA. These cells were then co-cultured with keratinocytes, Th2 cells, and mast cells. Depletion of EGF disrupted immunomodulatory effects of hUCB-MSCs on these AD-related inflammatory cells. In a Dermatophagoides farinae-induced AD mouse model, subcutaneous injection of hUCB-MSCs ameliorated gross scoring, histopathologic damage, and mast cell infiltration. It also significantly reduced levels of inflammatory cytokines including interleukin (IL)-4, tumor necrosis factor (TNF)-α, thymus and activation-regulated chemokine (TARC), and IL-22, as well as IgE levels. These therapeutic effects were significantly attenuated at all evaluation points in mice injected with EGF-depleted hUCB-MSCs. Conclusions: EGF secreted by hUCB-MSCs can improve AD by regulating inflammatory responses of keratinocytes, Th2 cells, and mast cells.

• Journal of the Society of Disaster Information
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• v.20 no.3
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• pp.484-499
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• 2024

Purpose: Recently, due to the aging of safety facilities in national industrial complexes, there has been an increase in the frequency and scale of safety accidents, highlighting the need for a shift toward a prevention-centered disaster management paradigm and the establishment of a digital safety network. In response, this study aims to provide an information system that supports more rapid and precise decision-making during disasters by utilizing digital twin-based integrated control technology to predict the spread of hazardous substances, trace the origin of accidents, and offer safe evacuation routes. Method: We considered various simulation results, such as surface diffusion, upper-level diffusion, and combined diffusion, based on the actual characteristics of hazardous substances and weather conditions, addressing the limitations of previous studies. Additionally, we designed an integrated management system to minimize the limitations of spatiotemporal monitoring by utilizing an IoT sensor-based backtracking model to predict leakage points of hazardous substances in spatiotemporal blind spots. Results: We selected two pilot companies in the Gumi Industrial Complex and installed IoT sensors. Then, we operated a living lab by establishing an integrated management system that provides services such as prediction of hazardous substance dispersion, traceback, AI-based leakage prediction, and evacuation information guidance, all based on digital twin technology within the industrial complex. Conclusion: Taking into account the limitations of previous research, we used digital twin-based AI analysis to predict hazardous chemical leaks, detect leakage accidents, and forecast three-dimensional compound dispersion and traceback diffusion.

• International Journal of Stem Cells
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• v.15 no.4
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• pp.359-371
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• 2022

Background and Objectives: The goal of this study was to investigate the mechanism of mesenchymal stem cell (MSC)-derived microRNA (miR)-150-5p-expressing exosomes in promoting skin wound healing through activating PI3K/AKT pathway by PTEN. Methods and Results: Human umbilical cord (HUC)-MSCs were infected with miR-150-5p overexpression and its control lentivirus, and HUC-MSCs-derived exosomes (MSCs-Exos) with stable expression of miR-150-5p were obtained. HaCaT cells were induced by H₂O₂ to establish a cellular model of skin injury, in which the expression of miR-150-5p and PTEN and the phosphorylation of PI3K and AKT were evaluated. HaCaT cells were transfected with pcDNA3.1-PTEN or pcDNA3.1 and then cultured with normal exosomes or exosomes stably expressing miR-150-5p. Cell proliferation was inspected by CCK-8. Cell migration was detected by scratch test and cell apoptosis by flow cytometry. The starBase tool was used to predict the binding site of miR-150-5p to PTEN. Dual-luciferase reporter assay and RIP assay were applied to assess the interaction between miR-150-5p and PTEN. In H₂O₂-induced HaCaT cells, the miR-150-5p expression decreased, and PTEN expression increased in a concentration-dependent manner. MSCs-Exos promoted the growth and migration of H₂O₂-induced HaCaT cells and inhibited their apoptosis. In addition, overexpression of exosomal miR-150-5p enhanced the protective effect of MSCs-Exos on H₂O₂-induced HaCaT cells; PTEN overexpression in HaCaT cells partially restrained miR-150-5p-mediated inhibition on H₂O₂-induced injury in HaCaT cells. PTEN was a target gene of miR-150-5p. MiR-150-5p regulated PI3K/AKT pathway through PTEN. Conclusions: MSCs-derived miR-150-5p-expressing exosomes promote skin wound healing by activating PI3K/AKT pathway through PTEN.

• Proceedings of the Korea Information Processing Society Conference
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• 2007.05a
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• pp.1410-1413
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• 2007

현재 초등학교에서 실시되고 있는 ICT(Information & Communication Technology) 교육은 ICT 소양교육과 ICT 활용교육으로 구분되어 실시되고 있다. ICT 소양교육은 컴퓨터 과학을 기반으로 하여 정보기술과 통신 기술에 대한 기본적인 소양교육으로 그 내용을 구성하고 있다. 현재 초고속 통신망의 발달과 컴퓨터 사용으로 인하여 소양교육에 대한 학업 성취도는 매우 향상되어 가고 있는 실정이다. 따라서 앞으로의 ICT 교육은 활용 교육에 더 많은 노력을 기울여 전 교과에 걸쳐 정보 통신 기술을 활용하여 교육의 내용뿐만 아니라 교육의 방법 등에서 많은 변화의 필요성이 증대되고 있다. ICT 활용교육에서 컴퓨터를 활용하기 위해서는 실생활에서 습득하거나 측정된 데이터를 컴퓨터에 입력하는 과정, 데이터 로깅(data logging), 으로부터 시작 한다. 최근의 유비쿼터스 컴퓨팅 환경에서 데이터가 발생한 곳에서 즉시 받아들이고 또한 결과가 필요한 곳에서 즉시 정보를 제공하여 주는 컴퓨팅 환경을 구성하는 것이 매우 중요 하다고 본다. 이에 본 연구에서는 유비쿼터스 컴퓨팅의 기본 개념 중 하나인 실시간 데이터 로깅 기법을 응용하여 초등학교에서 ICT 활용 학습 활동 시 발생되는 각종 원시 데이터들을 컴퓨터로 가져오는 데이터로깅 모델을 제안하고, 초등학교 과학과를 중심으로 교육과정의 실험 요소들을 분석하여 이를 개발된 모델에 적용하였다. 데이터 로깅 모델 적용 결과, 손쉽게 해당 원시 데이터를 수집할 수 있었고 데이터의 처리 및 분석을 간편하게 수행하여 정확한 실험 데이터를 바탕으로 실험 결과에 대한 토의, 토론에 더욱 많은 시간을 할애할 수 있었으며 학교에서의 ICT 활용 교육의 새로운 모델을 제시하였다.다.ovoids에서도 각각의 점들에 대한 선량을 측정하였다. SAS와 SSAS의 직장에 미치는 선량차이는 실제 임상에서의 관심 점들과 가장 가까운 25 mm(R2)와 30 mm(R3)거리에서 각각 8.0% 6.0%였고 SAS와 FWAS의 직장에 미치는 선량차이는 25 mm(R2) 와 30 mm(R3)거리에서 각각 25.0% 23.0%로 나타났다. SAS와 SSAS의 방광에 미치는 선량차이는 20 m(Bl)와 30 mm(B2)거리에서 각각 8.0% 3.0%였고 SAS와 FWAS의 방광에 미치는 선량차이는 20 mm(Bl)와 30 mm(B2)거리에서 각각 23.0%, 17.0%로 나타났다. SAS를 SSAS나 FWAS로 대체하였을 때 직장에 미치는 선량은 SSAS는 최대 8.0 %, FWAS는 최대 26.0 %까지 감소되고 방광에 미치는 선량은 SSAS는 최대 8.0 % FWAS는 최대 23.0%까지 감소됨을 알 수 있었고 FWAS가 SSAS 보다 차폐효과가 더 좋은 것으로 나타났으며 이 두 종류의 shielded applicator set는 부인암의 근접치료시 직장과 방광으로 가는 선량을 감소시켜 환자치료의 최적화를 이룰 수 있을 것으로 생각된다.)한 항균(抗菌) 효과(效果)를 나타내었다. 이상(以上)의 결과(結果)로 보아 선방활명음(仙方活命飮)의 항균(抗菌) 효능(效能)은 군약(君藥)인 대황(大黃)의 성분(成分) 중(中)의 하나인 stilbene 계열(系列)의 화합물(化合物)인 Rhapontigenin과 Rhaponticin의 작용(作用)에 의(依)한 것이며, 이는 한의학(韓醫學) 방제(方劑) 원리(原理)인 군신좌사(君臣佐使) 이론(理論)에서 군약(君藥)이 주증(主症)에 주(主)로 작용(作用)하는 약물(藥物)이라는 것을 밝혀주는 것

• Journal of the Computational Structural Engineering Institute of Korea
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• v.37 no.4
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• pp.251-258
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• 2024

This study investigated the effect of bearing aging on the seismic response of a three-span continuous concrete girder bridge with pot bearings installed. The pot bearings were modeled as elastic springs in the longitudinal, transverse, and vertical directions of the bridge to reflect the stiffness of fixed and movable supports. The effect of bearing aging on the seismic response of the bridge was examined by considering two factors: a decrease in the horizontal stiffness of the fixed bearings and an increase in the horizontal stiffness of the movable bearings. The finite element model of the three-span continuous girder bridge was validated by comparing its numerical natural frequencies with the designed natural frequencies. Using artificial ground motions that conform to the design response spectrum specified by the KDS bridge seismic design code, the seismic responses of the bridge's girders and bearings were calculated, considering the bearing stiffness variation due to aging. The results of a numerical analysis revealed that a decrease in the horizontal stiffness of the fixed bearings led to an increase in the absolute maximum relative displacement of the bearings during an earthquake. This increases the risk of the mortar block that supports the bearing cracking and the anchor bolt breaking. However, an increase in the horizontal stiffness of the movable bearings due to aging decreased the absolute maximum shear on the fixed bearings. Despite the shear reduction in the fixed bearings, the aging of the pot bearings change could cause additional tensile bending stress in the girder section above the free bearings, which could lead to unexpected structural damage to the continuous bridge during an earthquake.

• The Mathematical Education
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• v.63 no.3
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• pp.467-484
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• 2024

The rapid advancement of generative AI has ushered in an era where anyone can create and freely utilize personalized chatbots without the need for programming expertise. This study aimed to develop a customized chatbot based on OpenAI's GPTs for the purpose of pre-service teacher education and to analyze its educational performance in mathematics as assessed by educators guiding pre-service teachers. Responses to identical questions from a general-purpose chatbot (ChatGPT), a customized GPTs-based chatbot, and an elementary mathematics education expert were compared. The expert's responses received an average score of 4.52, while the customized GPTs-based chatbot received an average score of 3.73, indicating that the latter's performance did not reach the expert level. However, the customized GPTs-based chatbot's score, which was close to "adequate" on a 5-point scale, suggests its potential educational utility. On the other hand, the general-purpose chatbot, ChatGPT, received a lower average score of 2.86, with feedback indicating that its responses were not systematic and remained at a general level, making it less suitable for use in mathematics education. Despite the proven educational effectiveness of conventional customized chatbots, the time and cost associated with their development have been significant barriers. However, with the advent of GPTs services, anyone can now easily create chatbots tailored to both educators and learners, with responses that achieve a certain level of mathematics educational validity, thereby offering effective utilization across various aspects of mathematics education.

• Journal of Nutrition and Health
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• v.57 no.4
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• pp.389-402
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• 2024

Propose: This study examined the antioxidant and anti-gastritis properties of a mixture comprising Ipomoea batatas (IB) extract and Dioscorea japonica (DJ) extract. Methods: The mixture of IB and DJ extracts was analyzed for its total flavonoid content (TFC), total polyphenol content (TPC), and radical scavenging activities. Gastric lesions were induced by treating rats with 1 mL of a solution containing 60% ethanol and 150 mM HCl. The rats were then divided into 5 groups: CON (normal control), HEC (treated with 150 mM HCl-60% ethanol and distilled water), IBE (treated with 150 mM HCl-60% ethanol and IB extract at 350 mg/kg body weight [BW]), ID30 (treated with 150 mM HCl-60% ethanol and a mixture of IB and DJ extracts in a 7:3 ratio at 350 mg/kg BW), and DJE (treated with 150 mM HCl-60% ethanol and DJ extract at 350 mg/kg BW). Results: The ID30 group exhibited significantly higher TFC, TPC, and radical scavenging activities than the groups treated with single extracts. This group also showed a notable decrease in the formation of gastric lesions and preservation of gastric wall mucus. In addition, the serum levels of the inflammatory marker tumor necrosis factor (TNF)-α were significantly lower in the ID30 group than in the HEC group. Conclusion: The antioxidants present in the ID30 mixture effectively reduced oxidative stress and reactive oxygen species, mitigating gastric mucosal irritation induced by alcohol and acid. Furthermore, the mixture inhibited gastric acid secretion and inflammatory marker expression, such as TNF-α, preventing tissue damage. These findings suggest that the ID30 mixture is a potential preventative treatment for gastritis.

• Journal of Bio-Environment Control
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• v.33 no.3
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• pp.139-147
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• 2024

Mealworms are used as food, so it is preferable if the larval stage lasts longer. On the other hand, to accelerate the population growth of mealworms, it is preferable if the larvae become adults quickly. The purpose of this study is to explore the effects of population density on development time of mealworms. We used a container size of 7 cm at the top, 5 cm at the bottom, and 3 cm in height. Mealworms lived in the containers at densities of 1, 2, 5, 10, and 20 per container. The containers were bedded with 1 g of wheat bran and formed two groups, fed and not fed, at each density levels. The experiments were performed three times. In all of the experiments, higher population densities resulted in shorter transformation times from larva to pupa, but the time from pupa to imago was not significantly different. In addition, given the same density, the presence of food accelerated the time to transformation to pupa, but not to imago. The data supported that a lower density is needed to prolong the larval stage, and if adults are needed at a faster rate, the density should be higher. Therefore, we conclude that the development time of mealworms can be controlled by the density which is useful information for mealworm farmers.