• International conference on construction engineering and project management
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• 2013.01a
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• pp.467-474
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• 2013

Construction contactors must continuously seek to improve their cash flows, which reside at the heart of their financial success. They require careful planning, analysis, and optimization to avoid the risk of bankruptcy, remain profitable, and secure long-term growth. Sources of cash include bank loans and retained earnings, which are conceptually similar in that they both incur a cost of capital. Financial management therefore requires accurate yet customizable modeling capabilities that can quantify all expenses, including said cost of capital. However, currently existing cash flow models in construction engineering and management have strongly simplified the manner in which interest is assessed, which may even lead to overstating it at a disadvantage to contractors. The variable nature of cash balances, especially in the early phases of construction projects, contribute to this challenging issue. This research therefore extends a new cash flow model with an accurate interest calculation. It utilizes singularity functions, so called because of their ability to flexibly model changes across any number of different ranges. The interest function is continuous for activity costs of any duration and allows the realistic case that activities may begin between integer time periods, which are often calendar months. Such fractional interest calculation has hitherto been lacking from the literature. It also provides insights into the self-referential behavior of compound interest for variable cash balances. The contribution of this study is twofold; augmenting the corpus of financial analysis theory with a new interest formula, whose strengths include its generic nature and that it can be evaluated at any fractional value of time, and providing construction managers with a tool to help improve and fine-tune the financial performance of their projects.

• Smart Media Journal
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• v.12 no.8
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• pp.26-36
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• 2023

The purpose of this study is to propose ways to revitalize the local economy by analyzing the index changes and tourism big data before and after the opining of the KTX on the Gangneung Line in Gangneung City, where the population continues to decline. For This, the main current status of Gangneung-si and internal operation record data(DTG) of Gangneung-si were analyzed. After that, changes in the movement behavior of public transportation users before and after the opening of the KTX Gangneung Line were compared. As a result, it was possible to observe changes in tourist transportation preferences, demographic shifts, alterations in small-scale business sectors and in the travel patterns of tourists within the city of Gangneung. In particular, changes in the small business sector have shown an increase in general restaurants, leisure food establishments(cafes, etc.), and accommodation facilities following the opening of the KTX Gangneung Line. All three sectors have experienced growth concentrated in the vicinity of Gangneung Station, indicating the influence of Gangneung Station, which opened in the central part of Gangneung city, following the inauguration of the KTX Gangneung Line.

• Journal of Internet Computing and Services
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• v.24 no.5
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• pp.107-120
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• 2023

The public bicycle of Seoul, Ttareungyi, was launched at October 2015 to reduce traffic and carbon emissions in downtown Seoul and now, 2023 Oct, the cumulative number of user is upto 4 million and the number of bike is about 43,000 with about 2700 stations. However, super growth of Ttareungyi has caused the several problems, especially demand/supply mismatch, and thus the Seoul citizen has been complained about out of stock. In this point, this study conducted a real time demand forecasting model to prevent stock out bike at stations. To develop the model, the research team gathered the rental·return transaction data of 20,000 bikes in whole 1600 stations for 2019 year and then analyzed bike usage, user behavior, bike stations, and so on. The forecasting model using machine learning is developed to predict the amount of rental/return on each bike station every hour through daily learning with the recent 90 days data with the weather information. The model is validated with MAE and RMSE of bike stations, and tested as a prototype service on the Seoul Bike Management System(Mobile App) for the relocation team of Seoul City.

• Convergence Security Journal
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• v.23 no.3
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• pp.37-47
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• 2023

The growth of the metaverse has been accelerated by the increased demand for non-face-to-face interactions due to COVID-19 and advancements in technologies such as blockchain and NFTs. However, with the emergence of various metaverse platforms and the corresponding rise in users, criminal cases such as ransomware attacks, copyright infringements, and sexual offenses have occurred within the metaverse. Consequently, the need for artifacts that can be utilized as digital evidence within metaverse systems has increased. However, there is a lack of information about artifacts that can be used as digital evidence. Furthermore, metaverse security evaluation and forensic analysis are also insufficient, and the absence of attack scenarios and related guidelines makes forensics challenging. To address these issues, this paper presents artifacts that can be used for user behavior analysis and timeline analysis through dynamic analysis of Roblox, a representative metaverse gaming solution. Based on analyzing interrelationship between identified artifacts through memory forensics and log file analysis, this paper suggests the potential usability of artifacts in metaverse crime scenarios. Moreover, it proposes improvements by analyzing the current legal and regulatory aspects to address institutional deficiencies.

• The Journal of the Convergence on Culture Technology
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• v.9 no.6
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• pp.551-556
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• 2023

In this study, John Burningham's picturebooks(『Come Away from The Water, Shirley』, 『Time to Get Out of The Bath, Shirley』) was analyzed using the concept of carnival among Bakhtin's conversationalism theory. In John Burningham's picturebooks, the unconscious desire for the deviation of the main character, Shirley, is transformed into an adventure in an extraordinary imaginary world, and is depicted as a festival with laughter. Through picturebooks, children are satisfied by indirectly experiencing the forbidden behavior in reality by converting it into an event in the imaginary world. This indirect experience is very important for children to naturally resolve their dissatisfaction in reality and to develop their own original inner development. This study also suggests that providing an environment where children can easily access various picturebooks at home or early childhood education institutions plays a very important role in their growth.

• Journal of the Korean Dietetic Association
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• v.29 no.4
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• pp.199-210
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• 2023

This study was undertaken to analyze the growth, nutritional, and dietary risk factors of elementary school students belonging to the Busan Metropolitan City Office of Education and provide the basic data needed to develop an underweight and obesity prevention program. In 2021, BMI and Dietary Screening Test (DST) data of 4,046 children surveyed by the Nutrition Education Experience Center's "Diagnosis System" of the Busan Regional Office of Education were analyzed. The DST consists of 36 questions about lifestyle habits, meal quality, meal regularity, snack quality, and eating behavior. Of the children included, 6.8% were underweight, 65.4% were normal weight, 13.4% were overweight, and 14.4% were obese. Children in the obesity group had shorter sleep and meal times (P<0.001), lower vegetable and fruit consumption frequencies (P<0.001), higher fast food consumption frequencies (P<0.001), higher rates of skipping meals (P<0.01) and breakfast (P<0.001), and more frequently used smartphones and watched TV during meals (P<0.001). The underweight group had the highest scores for all eating development factors but more frequently had chewing and swallowing difficulties (P<0.001). The study confirms underweightedness and obesity are present different problems and indicates that nutrition teachers should conduct accurate studies on the eating habits and behaviors of obese and underweight students and provide individually tailored nutritional counseling.

• Journal of the Korean Applied Science and Technology
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• v.40 no.5
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• pp.1043-1054
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• 2023

Amidst the rapid growth of the vegan cosmetics market, consumer orientation towards environmental and ethical values has been intensifying. However, research on this subject remains limited. This study delves into the relationship between consumer value perception, environmental motivations, and perceived barriers influencing the purchase intentions of vegan cosmetics. Conducting a PLS-SEM analysis on a sample of 300 women with experience using vegan cosmetics, it was discerned that monetary value, social value, brand value, emotional value, quality value, and environmental knowledge play significant roles in influencing purchase intentions. The moderating effect analysis highlighted image barriers and value barriers as crucial factors. Through Importance-Performance Map Analysis, emotional value emerged as a pivotal element in strategizing to strengthen the purchasing intentions for vegan cosmetics. This research contributes both theoretically and practically to enhancing the competitive edge of the vegan cosmetics market and promoting sustainable consumption behavior.

• Journal of Marine Life Science
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• v.9 no.1
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• pp.47-52
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• 2024

Light is a major external environmental factor that influences the circadian rhythm of photosynthetic organisms and various physiological phenomena, such as growth, maturation, and behavior. The number of light-reaching organisms changes depending on the season and atmospheric conditions, and the intensity and wavelength of light differ depending on the organisms inhabiting the environment. Altered light changes the circadian rhythm of fish, which is controlled by clock genes, such as period 2 (Per2), cryptochrome 1 (Cry1), and melatonin. In this study, we set the zeitgeber time (ZT; 14 light-10 dark, LD) based on the actual sunrise and sunset times and examined Per2 and Cry1 activities, levels of aralkylamine N-acetyltransferase (AANAT), and melatonin in Pholis nebulosa, a drifting seaweed species exposed to irregular light. Per2 and Cry1 levels increased during the daytime and decreased after sunset. The AANAT levels decreased during the daytime and increased during the night. Melatonin concentration was highest around midnight (ZT21, 23:30), but exhibited similar concentrations during the daytime. While the activity of Per2, Cry1, and AANAT levels exhibited a typical circadian rhythm observed in most vertebrates, melatonin concentrations did not show a significant difference between the daytime and nighttime. These findings provide insights into the circadian rhythm patterns of organisms exposed to irregular light environments, such as P. nebulosa, which differ from those of typical fish species.

• Korean Journal of Materials Research
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• v.34 no.4
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• pp.202-207
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• 2024

In this study, we undertook detailed experiments to increase hydrogen production efficiency by optimizing the thickness of titanium dioxide (TiO₂) thin films. TiO₂ films were deposited on p-type silicon (Si) wafers using atomic layer deposition (ALD) technology. The main goal was to identify the optimal thickness of TiO₂ film that would maximize hydrogen production efficiency while maintaining stable operating conditions. The photoelectrochemical (PEC) properties of the TiO₂ films of different thicknesses were evaluated using open circuit potential (OCP) and linear sweep voltammetry (LSV) analysis. These techniques play a pivotal role in evaluating the electrochemical behavior and photoactivity of semiconductor materials in PEC systems. Our results showed photovoltage tended to improve with increasing thickness of TiO₂ deposition. However, this improvement was observed to plateau and eventually decline when the thickness exceeded 1.5 nm, showing a correlation between charge transfer efficiency and tunneling. On the other hand, LSV analysis showed bare Si had the greatest efficiency, and that the deposition of TiO₂ caused a positive change in the formation of photovoltage, but was not optimal. We show that oxide tunneling-capable TiO₂ film thicknesses of 1~2 nm have the potential to improve the efficiency of PEC hydrogen production systems. This study not only reveals the complex relationship between film thickness and PEC performance, but also enabled greater efficiency and set a benchmark for future research aimed at developing sustainable hydrogen production technologies.

• Information Systems Review
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• v.19 no.1
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• pp.123-145
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• 2017

This study empirically examines the effects of regulation on online gaming. Going beyond ad hoc heuristic approaches on individual behavior, we investigate the effects of regulation on dynamic changes of games or service providers. In particular, we propose three theoretical perspectives: social influence to investigate the regulation effect, the role of prior experience to determine the difference in the regulation effect size through users' prior experience, and network externalities to discover the difference in the regulation effect size according to the number of users on an online gaming platform. We use the vector autoregression methodology to model patterns of the co-movement of online games and to forecast game usage. We find that online gamers are heterogeneous. Therefore, policy makers should make suitable regulations for each heterogeneous group to effectively avoid generating gaming addicts without interrupting the economic growth of the online gaming industry.