• The Journal of the Korea Contents Association
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• v.22 no.7
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• pp.55-62
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• 2022

The perovskite solar cell is an active part of research in renewable energy fields such as solar energy, wind, hydroelectric power, marine energy, bioenergy, and hydrogen energy to replace fossil fuels such as oil, coal, and natural gas, which will gradually disappear as power demand increases due to the increase in use of the Internet of Things and Virtual environments due to the 4th industrial revolution. The perovskite solar cell is a solar cell device using an organic-inorganic hybrid material having a perovskite structure, and has advantages of replacing existing silicon solar cells with high efficiency, low cost solutions, and low temperature processes. In order to optimize the light absorption layer thin film predicted by the existing empirical method, reliability must be verified through device characteristics evaluation. However, since it costs a lot to evaluate the characteristics of the light-absorbing layer thin film device, the number of tests is limited. In order to solve this problem, the development and applicability of a clear and valid model using machine learning or artificial intelligence model as an auxiliary means for optimizing the light absorption layer thin film are considered infinite. In this study, to estimate the light absorption layer thin-film optimization of perovskite solar cells, the regression models of the support vector machine's linear kernel, R.B.F kernel, polynomial kernel, and sigmoid kernel were compared to verify the accuracy difference for each kernel function.

• Journal of Life Science
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• v.34 no.6
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• pp.418-425
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• 2024

Solid tumors are heterogeneous populations of multiple cell types. While the majority of the cells that comprise cancer are unable to divide, cancer stem cells have self-renewal and differentiation properties. Normal stem cell pathways that control self-renewal are overactivated in cancer stem cells, making cancer stem cells important for cancer cell expansion and progression. Dick first proposed the definition of cancer stem cells in acute myeloid leukemia, according to which cancer stem cells can be classified based on the expression of cell surface markers. Cancer stem cells maintain their potential in the tumor microenvironment. Multiple cell types in the tumor microenvironment maintain quiescent cancer stem cells and serve as regulators of cancer growth. Since current cancer treatments target proliferative cells, quiescent state cancer stem cells that are resistant to treatment increase the risk of recurrence or metastasis. Various signals of the tumor microenvironment induce changes to become a tumor-supportive environment by remodeling the vasculature and extracellular matrix. To effectively treat cancer, cancer stem cells and the tumor microenvironment must be targeted. Therefore, it is important to understand how the tumor microenvironment induces reprogramming of the immune response to promote cancer growth, immune resistance, and metastasis. In this review, we discuss the cellular and molecular mechanisms that can enhance immunosuppression in the tumor microenvironment.

• KIEAE Journal
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• v.16 no.1
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• pp.89-94
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• 2016

This study is part of three-dimensional(3D) heat transfer analysis program developmental process. The program is being developed without it's own built in 3D-modeller. So 3D-model must be created from another 3D-modeller such as generic CAD programs and imported to the developed program. After that, according to the 3D-geometric data form imported model, 3D-mesh created for numerical calculation. But the 3D-model created from another 3D-modeller is likely to have errors in it's geometric data such as mismatch of position between vertexes or surfaces. these errors make it difficult to create 3D-mesh for calculation. These errors are must be detected and cured in the pre-process before creating 3D-mesh. So, in this study four kinds of filters and functions are developed and tested. Firstly, 'vertex error filter' is developed for detecting and curing for position data errors between vertexes. Secondly, 'normal vector error filter' is developed for errors of surface's normal vector in 3D-model. Thirdly, 'intersection filter' is developed for extracting and creating intersection surface between adjacent objects. fourthly, 'polygon-line filter' is developed for indicating outlines of object in 3D-model. the developed filters and functions were tested on several shapes of 3D-models. and confirmed applicability. these developed filters and functions will be applied to the developed program and tested and modified continuously for less errors and more accuracy.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.32 no.1
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• pp.137-146
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• 2009

Researches on after-sales quality have centered on home electric appliances, figuring out how factors influencing after-sales service quality are causally related to customer's behavioral intentions, via consumer satisfaction as an intermediary parameter In most cases of after-sales service in home electric appliances, upon customer's request, service agents make a visit to where the appliance is installed, and check the product and do repairs. However, in case of a small portable device such as a cell phone, which people carry around at all times, most of the times customers themselves show up at the after-sales center, and demand a check-up and repairs. The main difference here is that the after-sales services are provided when a product can no longer perform its basic function and customer dissatisfaction is already up. In this case, the basic function of a product corresponds to must-be factor according to Kano model. The goal of our research is to identify critical factors for effective and efficient after-sales service, and how to monitor them on a routine basis. In our research, the quality after-sales service consists of three dimensions, interactive quality, result quality, and physical environment quality. We set up variables for each dimension, which would measure from customer's perspective key determining factors in service delivery process. Instead of focusing on customer satisfaction aspect, we focused on how after-sales service factors contribute to addressing customer complaints. Additionally, our future research would aim to verify how customer's behavioral intentions are affected, as the resolution of consumer complaints becomes more successful when adjustment of relevant quality factors improves after-sales service quality.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.63 no.2
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• pp.61-68
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• 2014

Function of battery bank stores energy for DC load in general, and DC power system of the nuclear power plant is used to supply DC loads for safety- featured instrumentation and control such as inverter, class 1E power system control and indication, and station annunciation. Class 1E DC power system must provide a power for the design basis accident conditions, and adequate capacity must be available during loss of AC power and subsequent safe shutdown of the plant. In present, batteries of Class 1E DC power system of the nuclear power plant uses lead-acid batteries. Class 1E batteries of nuclear power plants in Korea are summarized in terms of specification, such as capacity, discharge rate, bank configuration and discharge end voltage, etc. This paper summarizes standards of determining battery size for the nuclear power plant, and analyzes duty cycle for the class 1E DC power system of nuclear power plant. Then, battery cell size is calculated as 2613Ah according to the standard. In addition, this paper analyzes performance test results during past 13 years and shows performance degradation in the battery bank. Performance tests in 2001 and 2005 represent that entire battery cells do not reach the discharge-end voltage. Howeyer, the discharge-end voltage is reached in 14.7% of channel A (17 EA), 13.8% of channel B (16 EA), 5.2% of channel C (6 EA) and 16.4% of channel D (19 EA) at 2011 performance test. Based on the performance test results analysis and size calculation, battery capacity and degradation by age in Korearn nuclear power plant is discussed and would be used for new design.

• Journal of the Korean Applied Science and Technology
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• v.25 no.4
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• pp.446-458
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• 2008

Essential fatty acids (EFA) are fatty acids that must be obtained from the diet because they can not be biosynthesized by human or animals. Gamma fatty acids contain gamma-linolenic acid (GLA, 18:3n-6) and dihomo-gamma-linolenic acid (DHGLA, 20:3n-6) as intermediate metabolites of linoleic acid (LA, 18:2n-6), which is an EFA found in vegetable oils. GLA is an important essential fatty acid that is required by human and animals to function normally. Recently, studies have indicated that GLA may be an essential component of the cell membrane, as well as an active component of dietary supplements and medicine. GLA must beadministered through the diet because it is converted into DHGLA in the body quickly and completely. DHGLA is a key material involved in the metabolism of LA. GLA is biosysthesized by the rate limiting step of ${\Deltac}^6$-desaturase, which is an enzyme that desaturates LA, there by allowing it to be converted into DHGLA via chain elongation. In addition, DHGLA exerts bioactive effects via action as a precursor of eicosanoid series 1. Breast milk contains an abundant amount of GLA; however, GLA is also available directly in evening primrose oil, black currant seed oil, borage oil and hemp seed oil. In addition, GLA enriched animal and plant can be produced using biotechnology, and highly pure GLA can be extracted using supercritical fluids, such as supercritical carbon dioxide, which will allow economically feasible production of GLA for use in medicines.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2003.11a
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• pp.162-167
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• 2003

The pool $(3m{\times}6m{\times}10m)$ in Irradiated Materials Examination Facility is usually used for the purpose of taking the specimen out of cask loaded into the pool, and carrying in/out the specimen to/from the hot cell. Always, it must be cared for the water into the pool to be fine condition because all operation are worked with the naked eye during taking an irradiated materials out of the cask and plunging them in the bucket-elevator. In the aspects of the radioactive contamination control, remained substances in the water must be controlled so that the amount of substances are to be lower than the standard amount prescribed by RCA Korea Activity in a part of radioactive contamination control. This paper describes a behavior of the quality of water and the radioactive contamination of pool water for working of pool water purging system and contamination diffusion distribution bahavior of each specimens carried in/out.

• Transactions of the Korean hydrogen and new energy society
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• v.31 no.6
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• pp.596-604
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• 2020

Solid oxide electrolysis cell (SOEC) attracts much attention because of its high energy efficiency among many water-electrolysis technologies. SOEC operates at temperatures above 700℃, so that the water required for water-electrolysis must be supplied in the form of steam. When the steam to be supplied to the SOEC is generated by the SOEC system itself, an enormous amount of latent heat is required to vaporize the water, so additional energy must be supplied to the SOEC system. On the other hand, if the steam can be supplied from the outside, a small amount of energy is required to raise the temperature of the low temperature steam, so that the SOEC system can be operated without additional energy supply from outside, which enables efficient water-electrolysis. In this study, we figure out the size of heat exchanger for various steam temperature and effectiveness of heat exchanger, and propose the energy efficiency of the system.

• Journal of Advanced Navigation Technology
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• v.22 no.2
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• pp.154-162
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• 2018

The multiplier circuit is necessary to estimate degradation status of electronic cards in nuclear power plant, but its accuracy is not easy in processing those functions to multiply two input signals. What is important in multiplier circuit is that the multiplication result must be accurate and its linearity must be perfect. We developed and proposed excellent linearity multiplier circuit using operational amplifiers and transistor characteristics, and then proved its validity in this paper. We have made efforts to eliminate nonlinearity components of semiconductors with this circuit in order to ensure excellent linearity of developed multiplier circuit. We conducted multiplication operations through simulation, applying adequate values to each component in order to verify the circuit composed of that method. We showed step-by-step output signals, and then compared the logical analyses and measuring results as simulation results. We confirmed that this method is superior to existing multiplication or linearity.

• International Journal of Computer Science & Network Security
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• v.23 no.12
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• pp.235-245
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• 2023

Smart applications based on the Network of Everything also known as Internet of Everything (IoE) are increasing popularity as network connectivity requires rise further. As a result, there will be a greater need for developing 6G technologies for wireless communications in order to overcome the primary limitations of visible 5G networks. Furthermore, implementing neural networks into 6G will bring remedies for the most complex optimizing networks challenges. Future 6G mobile phone networks must handle huge applications that require data and an increasing amount of users. With a ten-year time skyline from thought to the real world, it is presently time for pondering what 6th era (6G) remote correspondence will be just before 5G application. In this article, we talk about 6G dreams to clear the street for the headway of 6G and then some. We start with the conversation of imaginative 5G organizations and afterward underline the need of exploring 6G. Treating proceeding and impending remote organization improvement in a serious way, we expect 6G to contain three critical components: cell phones super broadband, very The Web of Things (or IoT and falsely clever (artificial intelligence). The 6G project is currently in its early phases, and people everywhere must envision and come up with its conceptualization, realization, implementation, and use cases. To that aim, this article presents an environment for Presented Distributed Artificial Intelligence as-a-Services (DAIaaS) supplying in IoE and 6G applications. The case histories and the DAIaaS architecture have been evaluated in terms of from end to end latency and bandwidth consumption, use of energy, and cost savings, with suggestion to improve efficiency.