• Hanyang Medical Reviews
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• v.33 no.1
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• pp.10-16
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• 2013

Follicular helper T cells (Tfh) play a significant role in providing T cell help to B cells during the germinal center reaction, where somatic hypermutation, affinity maturation, isotype class switching, and the differentiation of memory B cells and long-lived plasma cells occur. Antigen-specific T cells with IL-6 and IL-21 upregulate CXCR5, which is required for the migration of T cells into B cell follicles, where these T cells mature into Tfh. The surface markers including PD-1, ICOS, and CD40L play a significant role in providing T cell help to B cells. The upregulation of transcription factor Bcl-6 induces the expression of CXCR5, which is an important factor for Tfh differentiation, by inhibiting the expression of other lineage-specific transcription factors such as T-bet, GATA3, and RORγt. Surprisingly, recent evidence suggests that CD4 T cells already committed to Th1, Th2, and Th17 cells obtain flexibility in their differentiation programs by downregulating T-bet, GATA3, and RORγt, upregulating Bcl-6 and thus convert into Tfh. Limiting the numbers of Tfh within germinal centers is important in the regulation of the autoantibody production that is central to autoimmune diseases. Recently, it was revealed that the germinal center reaction and the size of the Tfh population are also regulated by thymus-derived follicular regulatory T cells (Tfr) expressing CXCR5 and Foxp3. Dysregulation of Tfh appears to be a pathogenic cause of autoimmune disease suggesting that tight regulation of Tfh and germinal center reaction by Tfr is essential for maintaining immune tolerance. Therefore, the balance between Tfh and Tfr appears to be a critical peripheral tolerance mechanism that can inhibit autoimmune disorders.

• Proceedings of the Korean Society of Embryo Transfer Conference
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• 2002.11a
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• pp.83-83
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• 2002

The purpose of this study was to investigate the warming temperature and exposed time on the post-thaw survival rate and viability of bovine blastocyst cryopreserved by GMP vitrification. Groups of three bovine IVP blastocysts were sequentially placed into vitrification solution before being loaded into the GMP straws and immersed into LN$_2$within 20 to 25 sec. The warming rate was increased 2 times of warming temperature for improvement of post-thaw survival rates. The frozen embryos were warmed either at 35 or 70$^{\circ}C$ for 1 or 2 sec and then diluted in sucrose solution. Post-thaw blastocysts were serially washed in 0.25 and 0.15 M sucrose in holding medium (HM: TCM199 supplemented with 10% FCS) and TCM-199 for each 5 min, respectively, and then cultured in TCM199 for 24 h. The rate of re-expanded blastocyst was significantly different fer 35 and 70$^{\circ}C$ warming temporature (76.4 vs. 89.3%; P<0.05). The rate of re-expanded blastocyst at 70$^{\circ}C$ for 1 sec was significantly higher than that for 2 sec (91.1 vs. 70.9%; P<0.05). The number of nuclei counted were significantly different among control, 35 and 70$^{\circ}C$ (121${\pm}$8.5 vs. 104${\pm}$11.7 vs. 114${\pm}$10.3; P<0.05). These results indicated that the increasing of warming rate can provide high survival rates of bovine IVP blastocysts. Especially, the best viability of post-thaw blastocyst could be thaw at 70$^{\circ}C$ for 1 sec. The warming temperature and exposed time far warming was considered to be limiting factors to the viability of bovine IVP embryos. he purpose of this study was to investigate the warming temperature and expose.

• Composites Research
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• v.19 no.4
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• pp.15-22
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• 2006

One of the primary factors limiting the application of composite-metal adhesively bonded joints in structural design is the lack of a good evaluation tool for the interfacial strength to predict the load bearing capacity of boned joints. In this paper composite-steel adhesion strength is evaluated in terms of stress intensity factor and fracture toughness of the interface corner. The load bearing capacity of double lap joints, fabricated by co-cured bonding of composite-steel adherends has been determined using fracture mechanical analysis. Bi-material interface comer stress singularity and its order are presented. Finally stress intensities and fracture toughness of the wedge shape bi-material interface corner are determined. Double lap joint failure locus and its mixed mode crack propagation criterion on $K_1-K_{11}$ plane have been developed by tension tests with different bond lengths.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.97-97
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• 2020

Flooding in urban areas is caused by heavy rains for a short period of time and drains within 1 to 2 hours. It is also characterized by a small flooding area. In addition, flooding is often caused by various and complex causes such as land use, basin slope, pipe, street inlet, drainage pumping station, making it difficult to predict flooding. Therefore, this study analyzes the effect of each basin characteristic on the occurrence of flooding in urban areas by correlating various basin characteristics, whether or not flooding occurred, and rainfall(Limit Rainfall), and intends to use the data for urban flood prediction. As a result of analyzing the relationship between the imperviousness and the urban slope, pipe, threshold rainfall and limit rainfall, the pipe showed a correlation coefficient of 0.32, and the remaining factors showed low correlation. However, the multiple correlation analysis showed the correlation coefficient about 0.81 - 0.96 depending on the combination, indicating that the correlation was relatively high. In the future, I will further analyze various urban characteristics data, such as area by land use, average watershed elevation, river and coastal proximity, and further analyze the relationship between flooding occurrence and urban characteristics. The relationship between the urban characteristics, the occurrence of flooding and the limiting rainfall amount suggested in this study is expected to be used as basic data for the study to predict urban flooding in the future.

• Nuclear Engineering and Technology
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• v.55 no.7
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• pp.2621-2627
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• 2023

In Experimental Advanced Superconducting Tokamak (EAST) experiments, to achieve long pulse and high-power ICRH system operation, a new kind of ICRH antenna has been designed. One of the most critical factors in limiting the operation of long pulse and high power is the intense heat load in the front face of the ICRH antenna, especially the Faraday Screen (FS). Therefore, the cooling channels of FS need to be designed. According to thermal-hydraulic analysis, the FS tubes are divided into several groups to achieve more excellent water cooling capability. The number of series and parallel tubes in one group is chosen as six. This antenna went into service in the spring of 2021, and it is delightful that the temperature distribution of the FS tube is below 400 ℃ in 14.5 s and 1.8 MW ICRH system operation. However, the active water-cooling design was not carried out on the upper and lower plates of FS, which led to severe ablations on that region under long pulse and high power operation, and the temperature is up to 800. Therefore, the upper and lower side plates of the FS were designed with water cooling based on thermal-hydraulic analysis. During the 2022 winter experiments, the temperature of ICRH antenna FS was lower than 400 in the pulse of 200s and the power of 1 MW operation.

• Proceedings of the Korean Society of Crop Science Conference
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• 2022.10a
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• pp.272-272
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• 2022

Water and phosphorus (P) fertilizer are two of the most critical inputs in rice cultivation. Under climate change scenarios and urbanization, irrigation and fertilizer are becoming limiting factors often leading to significant decrease in yield whenever supplied scarcely. It has been shown that the Pup1 QTL confers tolerance to P starvation and improved early-stage root vigor in indica rice grown in the tropics. However, whether the QTL works in japonica rice genetic background grown in temperate regions remains to be elucidated. Here, we have introgressed the Pup1 QTL into three temperate rice varieties MS11, TR22183, and Dasan using marker-assisted backcrossing and next generation sequencing. The selected lines all harbored the full Pup1 QTL with recurrent parent genome recovery rates ranging from 66.5% to 99.8%. Evaluation of the introgression rice lines grown in South Korea under low inputs of P and water revealed early vegetative growth advantage relative to that of the recurrent parents. Under rainfed condition, Pup1 introgression lines had yield advantage ranging from 7.2 to 19.9% and 24 to 26% in P non-supplied soil and P-supplied soil, respectively compared to that of the recurrent parents suggesting that Pup1 confers enhanced yield under low P and water inputs in temperate rice genetic background grown in temperate climate. In terms of early vegetative growth, temperate Pup1 introgression lines showed a similar trend on the extent to which Pup1 promotes yield advantage in temperate rice in comparison with indica control Pup1 introgression line IR64-Pup1.

• Korean Circulation Journal
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• v.54 no.6
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• pp.295-310
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• 2024

Coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 has led to a global health crisis with substantial mortality and morbidity. To combat the COVID-19 pandemic, various vaccines have been developed, but unexpected serious adverse events including vaccine-induced thrombotic thrombocytopenia, carditis, and thromboembolic events have been reported and became a huddle for COVID-19 vaccination. Vaccine-related myocarditis (VRM) is a rare but significant adverse event associated primarily with mRNA vaccines. This review explores the incidence, risk factors, clinical presentation, pathogenesis, management strategies, and outcomes associated with VRM. The incidence of VRM is notably higher in male adolescents and young adults, especially after the second dose of mRNA vaccines. The pathogenesis appears to involve an immune-mediated process, but the precise mechanism remains mostly unknown so far. Most studies have suggested that VRM is mild and self-limiting, and responds well to conventional treatment. However, a recent nationwide study in Korea warns that severe cases, including fulminant myocarditis or death, are not uncommon in patients with COVID-19 VRM. The long-term cardiovascular consequences of VRM have not been well understood and warrant further investigation. This review also briefly addresses the critical balance between the substantial benefits of COVID-19 vaccination and the rare risks of VRM in the coming endemic era. It emphasizes the need for continued surveillance, research to understand the underlying mechanisms, and strategies to mitigate risk. Filling these knowledge gaps would be vital to refining vaccination recommendations and improving patient care in the evolving COVID-19 pandemic landscape.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.17 no.2
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• pp.65-80
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• 2022

Despite the uncertainty and risky factors of startups, the special and critical role of accelerators in carrying out professional nurturing and investment for them is becoming increasingly significant in the startup social-system. However, academic research on investment determinants that have a profound impact on the survival of accelerators is lacking, and there are only a few empirical studies on the classification and importance of factors, and they do not enjoy the benefits of theoretical studies. This study proposes a business model innovation framework based on the business model innovation theory that reflects the nature and properties of startups that are investment targets of accelerators and derives 12 investment decision factors. The framework defines that the target, direction, and performable force of startup innovation are a business model, strategy, and dynamic capability. Besides, the framework analyzes the investment decision factors of the existing accelerators based on the business model innovation framework to verify the suitability and sufficiency of the composition. As a result of the analysis, first, most of the items were faithfully composed from a static point of view of business model innovation, but it was found that the factors related to the core activities to evaluate the activity and customer relationship were insufficient. Second, from the strategic point of view, the necessity of developing factors that can encompass the definition and content of core resources, which are internal strategic factors, was raised. Third, from the dynamic point of view, it was found that many of the investment determinants of accelerators were concentrated on the lower level of dynamic competencies. This can be judged as a result of reflecting the characteristics of a startup that needs to develop a solution with few resources and a small number of team members. In addition, the roles and interrelationships between each factor are not clear, thus it was found as a limiting point for startups to view and evaluate the direction and process in which startups dynamically innovate their business models. This study is considerably differentiated in that it provides a business model innovation framework and offers a theoretical basis for investment determinants by deriving the investment determinants of accelerators based on the framework and design the foundation for subsequent research. The business model innovation framework presented in this study has great implications in that it contributes to the achievement of startups, accelerators, and startup support organizations.

• Microbiology and Biotechnology Letters
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• v.39 no.4
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• pp.382-386
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• 2011

Microbial fuel cells (MFC), devices that use bacteria as a catalyst to generate electricity, can utilize a variety of organic wastes as electron donors. The current generated may differ depending on the organic matter concentrations used, when other conditions, such as oxidant supply, proton transfer, internal resistance and so on, are not limiting factors. In these studies, a single-cathode type MFC (SCMFC) and dual-cathode type MFC (DCMFC) were used to ascertain the current's improvement through an increase in the contact area between the anode and the cathode compartments, because the cathode reaction is one of the most serious limiting factors in an MFC. Also an MFC was conducted to explore whether an improvement in electricity generation resulted from oxidizing the carbon sources and nitrates. About 250 mg $L^{-1}$ sodium acetate was fed to an anode compartment with a flow rate of 0.326 mL $min^{-1}$ by continuous mode. The current generated from the DCMFC was higher than the value produced from MFC with a single cathode. COD removal of dual-cathode MFC was also higher than that of single-cathode MFC. The nitrate didn't affect current generation at 2 mM, but when 4 and 8 mM nitrate was supplied, the current in the single-cathode and dual-cathode MFC was decreased by 98% from $5.97{\pm}0.13$ to $0.23{\pm}0.03$ mA and $8.40{\pm}0.23$ to $0.20{\pm}0.01$ mA, respectively. These results demonstrate that increasing of contact area of the anode and cathode can raise current generation by an improvement in the cathode reaction.

• Korean Security Journal
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• no.37
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• pp.137-163
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• 2013

This research will incorporate cases from U.S public schools to analyze the factors which influences the security within the school and efficient security patterns to suggest an adequate suggestion to elevate domestic school security system. This study is divided into two following models: a serious criminal offense model, which considers crimes occurred on campus as subordinate variables, and a school violence model, which considers as subordinate variables after limiting an act of delinquency and an a group action that can harm the safety of students, although they are not included in the categories of crimes. First, from analyzing the factors which influences security within school, the explanation power of serious crime offense safety model and school violence safety model is measured 12% and 11.3%. In serious crime offense safety model, the safety education for students, among the safety programs provided by schools(t=2.548, p=0.011), parent participation to school management(t=10.694, p=0.000), Security activities on campus(t=3.643, p=0.000), and CPTED activity(t=6.467, p=0.000) are statistically significant, as affecting factors on the safety from serious crimes. Similarly in school violence model, the safety education for students, among the safety programs provided by schools(t=3.228, p=0.001), parent participation to school management(t=12.034, p=0.000), security activities on campus(t=2.663, p=0.000), and CPTED activity(t=3.928, p=0.000) are statistically significant, as affecting factors on the safety from school violence. Second, according to the analytic results on figuring out the optimal pattern to heighten the security activities, the serious offence model's explanatory power was 4.4% and school violence safety model rated 3.9%. With the serious offense safety model, the activity factors which showed statistically significant in influencing safety from serious offenses were cooperation with local police force (t=2112, p=0.035), school policy management (t=3.309, p=0.001), security patrolling activity (t=2.548, p=0.011). In the school violence model, security activities initiated by the school which showed statistically significant from serious offenses were cooperation with local police force (t=2.364, p=0.018) and policy management (t=4.142, p=0.000). In accordance with the result of this study, education for students rather than education for teachers is more positive in terms of the safety on campus, and parent participation, like education, is consistently needed for the safety on campus. In case of CPTED activity, reinforcing plans should be prepared by intactly accepting examples in the USA. In case of security activity, plans that can increase visibility and reinforce cooperation with local police in a smooth way will provide a positive effect to the safety on campus.