• Proceedings of the Korean Institute Of Construction Engineering and Management
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• autumn
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• pp.35-41
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• 2002

This research introduces the development of a project-level cash flow forecasting model in construction stage based on the planned earned value and the cost from a general contractors view on a jobsite. Most previous models have been developed to assist contractors in their pre-tendering or planning stage cash flow forecasts. The critical key to cash flow forecasting at the project level is how to build a cash-out model. The basic concept is to use moving weights of cost categories in a budget over project duration. The cost categories are classified to compile resources with almost the same time lags that are based on contracting payment conditions and credit times given by suppliers or venders. For cash-in, net planned monthly-earned values are simply transferred to the cash-in forecast, to be applied there with billing time and retention money. Validation of the model involves applying data from on-going 4 projects in progress for 12 months. Based on the results of the comparative analyses through the simulation of the proposed model and the existing models, the proposed model is more accurate, flexible and simpler than traditional models to the employee of construction jobsite who is not oriented financial knowledge.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.13 no.1
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• pp.107-113
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• 1995

Generally, the objectives of the geodetic network adjustments are for solving the configuration of geodetic net-works and the problem of observation plans. In this study, assuming that the configuration is fixed, for improving the accuracy of geodetic networks, we focus on choosing adjustment control points and adjustment methods. By choosing adjustment control points and adjustment methods, the adjustment result accuracy of national geodetic networks can be different. So, in this study, we introduce the algorithm that use free network adjustment concept to minimize the displacements of new station points but fixing existing control points. Then, us-ing adjustment results, we can check the errors of existing control points. After checking the errors of existing control point, in case of severe error points in existing control points, we change those points into unknown station points and repeat the algorithm to optimize the coordinates of new station points. As applying this algorithm to simulation network, we can check the errors of existing control points. And changing severe error points into unknown station points, we can decrease the errors of network and optimize the coordinates of new station points. From the results of simulation network adjustment, we think that, as applying this algorithms to sequential adjustment of geodetic network and public surveying that using national geodetic network, the accuracy of network adjustments can be improved.

• Nuclear Engineering and Technology
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• v.47 no.6
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• pp.678-699
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• 2015

Although the harsh space environment imposes many severe challenges to space pioneers, space exploration is a realistic and profitable goal for long-term humanity survival. One of the viable and promising options to overcome the harsh environment of space is nuclear propulsion. Particularly, the Nuclear Thermal Rocket (NTR) is a leading candidate for nearterm human missions to Mars and beyond due to its relatively high thrust and efficiency. Traditional NTR designs use typically high power reactors with fast or epithermal neutron spectrums to simplify core design and to maximize thrust. In parallel there are a series of new NTR designs with lower thrust and higher efficiency, designed to enhance mission versatility and safety through the use of redundant engines (when used in a clustered engine arrangement) for future commercialization. This paper proposes a new NTR design of the second design philosophy, Korea Advanced NUclear Thermal Engine Rocket (KANUTER), for future space applications. The KANUTER consists of an Extremely High Temperature Gas cooled Reactor (EHTGR) utilizing hydrogen propellant, a propulsion system, and an optional electricity generation system to provide propulsion as well as electricity generation. The innovatively small engine has the characteristics of high efficiency, being compact and lightweight, and bimodal capability. The notable characteristics result from the moderated EHTGR design, uniquely utilizing the integrated fuel element with an ultra heat-resistant carbide fuel, an efficient metal hydride moderator, protectively cooling channels and an individual pressure tube in an all-in-one package. The EHTGR can be bimodally operated in a propulsion mode of $100MW_{th}$ and an electricity generation mode of $100MW_{th}$, equipped with a dynamic energy conversion system. To investigate the design features of the new reactor and to estimate referential engine performance, a preliminary design study in terms of neutronics and thermohydraulics was carried out. The result indicates that the innovative design has great potential for high propellant efficiency and thrust-to-weight of engine ratio, compared with the existing NTR designs. However, the build-up of fission products in fuel has a significant impact on the bimodal operation of the moderated reactor such as xenon-induced dead time. This issue can be overcome by building in excess reactivity and control margin for the reactor design.

• Korea Real Estate Review
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• v.28 no.1
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• pp.105-114
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• 2018

According to Statistics Korea, South Korea has entered the realm of the "aging society" with the rapid development of the country's population. Researchers anticipate that the extremely high (73%) ratio of real estate property to total assets for mid-age to aged households in South Korea that do not have a fixed income may cause serious problems in the future. For example, the real estate market in South Korea may be bombarded with properties listed for sale, causing the average property price to drop due to the abundant supply. Although this prediction may be reasonable, this concept has excluded the idea of pension (which is crucial as it can be considered a consistent and fixed income) due to the limited amount of available data thereon; as such, it is important to include this factor to improve the pertinent research. Thus, this research was conducted using the data from the $3^{rd}$ and $5^{th}$ Korea Retirement and Income Study. For the study results, it was found that variables such as net asset, gender, education, and number of family members have the same impact as that found in the previous studies. To extend from here, two new factors were introduced: the existence of pensions and the amount of pension received by a household. From there, it was found that the existence of a consistent and fixed income such as a pension has led to an increase in housing consumption, the area of interest of the authors.

• Journal of The Korean Association For Science Education
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• v.41 no.3
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• pp.221-235
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• 2021

The purpose of this study is to investigate the learning effects according to the level of Science State Curiosity (SSC) and Science State Anxiety (SSA) in science learning situation for 5th~6th grade elementary school students. To achieve this purpose, we measured and analyzed SSC and SSA in each learning situation by dividing science learning into three situations: Confronting scientific task (I), Checking the results (II), and Learning science concepts (III). In order to identify the net effects of SSC and SSA on learning effects, science curiosity, need for cognition, science self-concept, science anxiety, and interest, which were expected to affect the learning effects, were controlled. SSC and SSA in the situation of confronting scientific tasks were defined as 'SSCI' and 'SSAI,' SSC and SSA in the situation of checking the results were defined as 'SSCII' and 'SSAII,' and SSC and SSA in the situation of learning science concepts were defined as 'SSCIII' and 'SSAIII.' In addition, the learning effects were divided into post-learning effect and delayed post-learning effect, and the degree of improvements in the post- or delayed post-test scores compared to the pre-test score were calculated and analyzed. As a result of the analysis, SSCI·SSCII had a positive effect on the post- and the delayed post-learning effect, but SSAIII had a negative effect on the post- and delayed post-learning effect, SSAI·SSAII had a negative effect on the post-learning effect. SSC had a greater effect on learning effects than SSA, and SSCII had the most influence on the post-learning effect and SSCI had the most influence on the delayed post-learning effect. As SSCIII increased, there was a tendency to do additional voluntary learning. The results of this study are expected to broaden the understanding of students' emotional states in science learning and provide a theoretical foundation for studies of state curiosity and state anxiety.

• Journal of Korea Entertainment Industry Association
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• v.14 no.3
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• pp.267-275
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• 2020

Even ordinary-looking plays can have a profound meaning. Based on this assumption, Eugene Pink (1960) has established an analytical model of play with five elements, namely "delight", "meaning", "community", "rules" and "tools." It was an effort to reflect on the true meaning of play beyond the cortical entertaining nature of play. In this study, it was carried out that all the texts containing images and performance from the EBS character "Pengsu" were selected, since he emerged as a new star in 2019. And also his play structure was analyzed by applying the Pink's model. As a result, Pengsu's play structure was confirmed to be systematic and complete as a play prototype because it was well-organized with five elements of play. It was regarded as a successful character that skillfully attracts participants to the play world. Among the components of the play, "fun" was found to be his funny appearance, sudden and unconventional behavior, "meaning" was the elimination of authoritarianism, self-esteeming and energizing, "community" was a multi-platform media user who crossed off-on-line, analog-digital-line, "rules" was to set his concept fixed as a young stranger with an ego to unreveal his identity, and "tools" was shown as his character itself and continual discourse. It shows that until now, Pengsu has a social net function of quite spreading the positive meaning of encouragement and comfort, advice and guide, consideration and forgiveness, introspection and nirvana to all members of our society, including the youth who are struggling with uncertainty and anxiety by showing rather exaggerated and stimulating performance that precisely combines these play elements.

• Journal of the Korean Institute of Landscape Architecture
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• v.50 no.5
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• pp.90-102
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• 2022

In recent years, as interest in healing increases, outdoor spaces with the concept of healing have been created. For more professional and in-depth planning and design, the perception and characteristics of outdoor healing places through social media posts were analyzed using NER. Text mining was conducted using 88,155 blog posts, and frequency analysis and clique cohesion analysis were conducted. Six elements were derived through a literature review, and two elements were added to analyze the perception and the characteristics of healing places. As a result, visitors considered place elements, date and time, social elements, and activity elements more important than personnel, psychological elements, plants and color, and form and shape when visiting healing places. The analysis allowed the derivation of perceptions and characteristics of healing places through keywords. From the results of the Clique, keywords, such as places, date and time, and relationship, were clustered, so it was possible to know where, when, what time, and with whom people were visiting places for healing. Through the study, the perception and characteristics of healing places were derived by analyzing large-scale data written by visitors. It was confirmed that specific elements could be used in planning and marketing.

• Journal of the Korean Society of Earth Science Education
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• v.16 no.2
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• pp.261-275
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• 2023

The purpose of this study was to analyze the conceptual understanding of carbon neutrality among secondary school science pre-service teachers, as well as to identify gaze patterns in visual materials. For this study, gaze tracking data of 20 pre-service secondary school science teachers were analyzed. Through this, the levels of conceptual understanding of carbon neutrality were categorized for the participants, and differences in gaze patterns were analyzed based on the degree of conceptual understanding of carbon neutrality. The research findings are as follows. First, as a result of performing modeling activities to predict carbon emissions and removals until 2100 using the concept of '2050 carbon neutrality,' 50% of the participants held a conception that carbon emissions would continue to increase. Additionally, 25% of the participants did not properly understand the causal relationship between net carbon dioxide emissions and cumulative concentrations. Second, the gaze movements of the participants regarding visual materials related to carbon neutrality were significantly influenced by the information presented in the text area, and in the case of graphs, the focus was mainly on the data area. Moreover, when visual data with the same function and category were arranged, participants showed the most interest in materials explaining concepts or visual data placed on the left side. This implies a preference for specific positions or orders. Participants with lower levels of conceptual understanding and inadequate grasp of causal relationships among elements exhibited notably reduced concentration and overall gaze flow. These findings suggest that conceptual understanding of carbon neutrality including climate change and natural disaster significantly influences interest in and engagement with visual materials.

• Journal of Industrial Convergence
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• v.21 no.5
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• pp.1-13
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• 2023

Carbon neutrality is the concept of reducing greenhouse gases emitted by human activities and making actual emissions zero through removal of remaining gases. It is also called "Net-Zero" and "carbon zero". Korea has declared a "2050 Carbon Neutrality policy" to cope with the climate change crisis. Various carbon reduction legislative processes are underway. Since carbon neutrality requires changes in industrial technology, it is important to prepare a system for carbon zero. This paper aims to understand the status and trends of global carbon neutrality technology. Therefore, ROK's web platform "www.naver.com." was selected as the data collection scope. Korean online articles related to carbon neutrality were collected. Carbon neutrality technology trends were analyzed by future signal methodology and Word2Vec algorithm which is a neural network deep learning technology. As a result, technology advancement in the steel and petrochemical sectors, which are carbon over-release industries, was required. Investment feasibility in the electric vehicle sector and technology advancement were on the rise. It seems that the government's support for carbon neutrality and the creation of global technology infrastructure should be supported. In addition, it is urgent to cultivate human resources, and possible to confirm the need to prepare support policies for carbon neutrality.

• Nuclear Engineering and Technology
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• v.55 no.4
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• pp.1540-1554
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• 2023

To use nuclear energy sustainably, spent nuclear fuel, classified as high-level radioactive waste and inevitably discharged after electricity generation by nuclear power plants, must be managed safely and isolated from the human environment. In Korea, the land area is limited and the amount of high-level radioactive waste, including spent nuclear fuels to be disposed, is relatively large. Thus, it is particularly necessary to maximize disposal efficiency. In this study, a high-efficiency deep geological repository concept was developed to enhance disposal efficiency. To this end, design strategies and requirements for a high-efficiency deep geological repository system were established, and engineered barrier modules with a disposal canister for pressurized water reactor (PWR)-type and pressurized heavy water reactor type Canada deuterium uranium (CANDU) plants were developed. Thermal and structural stability assessments were conducted for the repository system; it was confirmed that the system was suitable for the established strategies and requirements. In addition, the results of the nuclear safety assessment showed that the radiological safety of the new system met the Korean safety standards for disposal of high-level radioactive waste in terms of radiological dose. To evaluate disposal efficiency in terms of the disposal area, the layout of the developed disposal areas was assessed in terms of thermal limits. The estimated disposal areas were 2.51 km² and 1.82 km² (existing repository system: 4.57 km²) and the excavated host rock volumes were 2.7 Mm³ and 2.0 Mm³ (existing repository system: 4.5 Mm³) for thermal limits of 100 ℃ and 130 ℃, respectively. These results indicated that the area and the excavated volume of the new repository system were reduced by 40-60% compared to the existing repository system. In addition, methods to further improve the efficiency were derived for the disposal area for deep geological disposal of spent nuclear fuel. The results of this study are expected to be useful in establishing a national high-level radioactive waste management policy, and for the design of a commercial deep geological repository system for spent nuclear fuels.