• Geomechanics and Engineering
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• v.19 no.1
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• pp.11-20
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• 2019

The use of electrokinetic dissipation method to study the fluid flow law in micro-pores is of great significance to reservoir rock microfluidics. In this paper, the micro-capillary theory was combined with the coupling model of the seepage field and the current field under the excitation of the harmonic signal, and the coupling theory of the electrokinetic effect under the first-order approximation condition was derived. The dissipation equation of electrokinetic dissipation and viscous resistance dissipation and its solution were established by using Green's function method. The physical and mathematical models for the electrokinetic dissipation of reservoir rocks were constructed. The microscopic mechanism of the electrokinetic dissipation of reservoir rock were theoretically clarified. The influencing factors of the electrokinetic dissipation frequency of the reservoir rock were analyzed quantitatively. The results show that the electrokinetic effect transforms the fluid flow profile in the pores of the reservoir from parabolic to wavy; under low-frequency conditions, the apparent viscosity coefficient is greater that one and is basically unchanged. The apparent viscosity coefficient gradually approaches 1 as the frequency increases further. The viscous resistance dissipation is two orders of magnitude higher than the electrokinetic effect dissipation. When the concentration of the electrolyte exceeds 0.1mol/L, the electrokinetic dissipation can be neglected, while for the electrolyte solution (<$10^{-2}M$) in low concentration, the electrokinetic dissipation is very significant and cannot be ignored.

• The Journal of the Korea Contents Association
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• v.21 no.3
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• pp.282-300
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• 2021

The purpose of this study was to explore what social media posts tell us about family life during the COVID-19 pandemic by examining the keywords and topics underlying posts on blogs and online forums. Our criteria for web crawling were (a) blog and forum posts on Naver and Daum, the top portal sites in Korea, (b) posts between February 23 and April 19, 2020, the period of the first heightened social distancing orders, and (c) inclusion of "COVID" and "family" or "COVID" and "home." We analyzed 351,734 posts using TF-IDF values and topic modeling based on latent Dirichlet allocation. We identified and named 22 topics including COVID-19 prevention, family infection, family health, dietary life and changes, religious life, stuck at home, postponed school year, family events, travel and vacations, concerns about family and friends, anxiety and stress, disaster and damage, COVID-19 warning text messages, family support policies, Shin-cheon-ji and Daegu. The results show that COVID-19 impacted various domains of family life including health, food, housing, religion, child care, education, rituals, and leisure as well as relationships and emotions.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.44 no.4
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• pp.32-42
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• 2021

The printing process can have to print various colors with a limited capacity of printing facility such as ink containers that are needed cleaning to change color. In each container, cleaning time exists to assign corresponding inks, and it is considered as the setup cost required to reduce the increasing productivity. The existing manual method, which is based on the worker's experience or intuition, is difficult to respond to the diversification of color requirements, mathematical modeling and algorithms are suggested for efficient scheduling. In this study, we propose a new type of scheduling problem for the printing process. First, we suggest a mathematical model that optimizes the color assignment and scheduling. Although the suggested model guarantees global optimality, it needs a lot of computational time to solve. Thus, we decompose the original problem into sequencing orders and allocating ink problems. An approximate function is used to compute the job scheduling, and local search heuristic based on 2-opt algorithm is suggested for reducing computational time. In order to verify the effectiveness of our method, we compared the algorithms' performance. The results show that the suggested decomposition structure can find acceptable solutions within a reasonable time. Also, we present schematized results for field application.

• Journal of Information Technology Services
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• v.20 no.5
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• pp.89-104
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• 2021

Food delivery service combined with IT technology and HMR (Home Meal Replacement) are rapidly growing due to the COVID-19. Recently, the demand for salads along with HMR has increased among office workers in their 20s and 30s who are interested in health and beauty. Freshcode is a food startup with 6 years of experience that started selling salad products through O2O service. Freshcode applied for a patent for a service that collects orders from nearby areas and delivers them on the same day to a designated delivery address 'FCOSPOT' to save shipping costs. In March 2021, in recognition of the growth potential of the regular delivery service, Freshcode received an investment of 6 billion won in Series A. This study may have practical implications to early-stage startups and scale-up stage startups through a longitudinal case study on the growth of a single company. As for the research method, the lean startup methodology and lean canvas were used in the early stage of startup. In particular, the process of the build-measure and learn feedback-loop, which is the core of lean startup methodology, was applied to each major decision-making step. In the scale-up stage after 5 years, the business model canvas was used to schematize the growth as a food online O2O platform to verify continuous innovation. This case study has three main findings. First, the idea of 'FCOSPOT' was successfully implemented through the Lean Startup methodology. Second, Freshcode demonstrated the scalability of the differentiated business model of shared base delivery O2O. Third, a key factor of success was the digital integrated communication operation strategy that maximizes the experience for the created customers.

• Asia Marketing Journal
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• v.15 no.3
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• pp.31-52
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• 2013

The metacognitive experience of the ease or difficulty with which new, external information can be processed, referred to as 'processing fluency,' has been shown to influence a wide range of human judgments including truth judgments, familiarity judgments, risk perception, evaluation, and preference (see Alter and Oppenheimer 2009 for a review). The current research explores the possibility of a consumer's product innovativeness judgment based on the difficulty of processing new information. In specific, this study examines if the inferential link between (dis)fluency-(un)familiarity can feed into the perception of innovativeness. This study also explores how a consumer's processing motivation can moderate the consumer's reliance on processing fluency in judgments and how the influence of fluency can vary depending on judgment task orders. In an experiment, participants rated a new product's innovativeness and then indicated their product attitude (or vice versa depending on the judgment task order condition) after reading a product review article that was printed in either an easy-to-read or a difficult-to-read font (for fluency manipulation). The findings show that low need for cognition individuals infer higher product innovativeness when processing product information is difficult rather than easy, consistent with the common assumption that 'new information is more difficult to process than familiar information.' The findings also suggest that once low fluency is attributed to innovativeness, it may no longer lead to a negative response to the product. High need for cognition individuals' judgments on product innovativeness are not affected by fluency. The findings also demonstrate a judgment task order effect on the use of fluency in judgments (e.g., Xu and Schwarz 2005). This study provides the first evidence that an individual's fluency experience can be used as a source of information in product innovativeness judgments especially under low processing motivation conditions. The findings can help marketers better understand the malleability of consumer judgments and perceptions of product characteristics (e.g., product innovativeness) by demonstrating an interesting interplay of processing fluency, processing motivation, and judgment task-related contextual factors.

• Korean Journal of Ichthyology
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• v.36 no.2
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• pp.164-173
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• 2024

We collected fish from the intertidal zone of Seonyu-do Island in order to find out the composition of fish species by using hand net and kick net from March to October 2022. During the investigation period, a total of 2,707 individuals from 9 Orders, 19 Families, 45 Species were collected, and the dominant species was identified as Nuchequula nuchalis and the subdominant species was Favonigobius gymnauchen. By family group, the largest number of fishes in the Gobiidae were 13 species, followed by the Scorpaenidae and the Stichaeidae were 4 species. In this study, genus Clariger was discovered for the first time off the West sea, and it is estimated that fish living on the southern coast are moving northward due to an increase in the water temperature of the West Sea and detailed research is needed.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.29 no.1
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• pp.42-55
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• 2024

To discover unrecorded diatoms, seawater, sand, and pebbles were collected from the intertidal zone of five tidal flats from 2016 to 2023. Diatoms were isolated from the collected samples, cultured, and the ultrastructure of the cells was observed using a scanning electron microscope. 7 species of unrecorded diatoms, consisting of 3 orders, 5 families, and 7 genera, were discovered: Gomphoseptatum aestuarii, Rhoiconeis pagoensis, Seminavis exigua, Plagiolemma distortum, Staurotropis seychellensis, Biremis sigmoidea, Liriogramma sarcophagus. Among these, four genera, Rhoiconeis, Plagiolemma, Staurotropis, and Liriogramma, are reported for the first time in Korea. L. sarcophagus was separated from the central diatom Asteromphalus and transferred to Liriogramma, but its phylogenetic position has not yet been clearly established.

• Wind and Structures
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• v.38 no.3
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• pp.215-229
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• 2024

Guyed mast structures exhibit characteristics such as high flexibility, low mass, small damping ratio, and large aspect ratio, leading to a complex wind-induced vibration response mechanism. This study analyzed the time- and frequency-domain characteristics of the wind-induced response of a guyed mast structure using measured acceleration response data obtained from the Shenzhen Meteorological Gradient Tower (SZMGT). Firstly, 734 sets of 1-hour acceleration samples measured from 0:00 October 1, 2021, to 0:00 November 1, 2021, were selected to study the vibration shapes of the mast and the characteristics of the generalized extreme value (GEV) distribution. Secondly, six sets of typical samples with different vibration intensities were further selected to explore the Gaussian property and modal parameter characteristics of the mast. Finally, the modal parameters of the SZMGT are identified and the identification results are verified by finite element analysis. The findings revealed that the guyed mast vibration shape exhibits remarkable diversity, which increases nonlinearly along the height in most cases and reaches a maximum at the top of the tower. Moreover, the GEV distribution characteristics of the 734 sets of samples are closer to the Weibull distribution. The probability distribution of the structural wind vibration response under strong wind is in good agreement with the Gaussian distribution. The structural response of the mast under wind loading exhibits multiple modes. As the structural response escalates, the first three orders of modal energy in the tower display a gradual increase in proportion.

• Journal of Korea Port Economic Association
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• v.31 no.4
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• pp.39-52
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• 2015

The purpose of this paper is to empirically examine whether there are significant relations among rankings of cross-efficiency, web accessibility, and website evaluation. For this purpose, the study uses the KWAH-4 method developed by the Web Accessibility Laboratory in Korea, website evaluation method developed by the Business Development Bank of Canada (BDC), and the cross-efficiency model for 13 Asian container seaports including Korean, Chinese, and Japanese main ports in 3 years (2009, 2010, and 2013) using data for two cases: three inputs (depth, total area, and number of crane) and one output (TEU) in the first case and three inputs and two outputs (TEU and BDC overall score) in the second case. The main empirical results are as follows. First, the ranking orders of cross-efficiency, web accessibility, and website evaluation overall scores are not significantly correlated with each other. Second, if the BDC overall score is included in the output element, the correlation results are improved. However, the correlation coefficient is still low. The container port policy planners should introduce and consider the web accessibility and website evaluation scores when evaluating an efficiency-increasing plan for Korea's main container ports.

• Journal of Korea Port Economic Association
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• v.34 no.1
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• pp.51-64
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• 2018

The purpose of this paper is to analyze the productivity change of the Korean shipbuilding industry between 2001-2008 and 2008-2015 by using MPI(Malmquist Productivity Index) to decompose the sources of total factor productivity growth into technical efficiency change, scale efficiency change, pure efficiency change, technical change. The empirical results are as follows. In the first half of the year (2001-2008), productivity increased by 2.8%, which was due to technological advances rather than technical efficiency. In the second half (2008-2015), productivity change declined by -3.4%. This is attributable to the technical efficiency deterioration and technological degeneration caused by a decrease in shipbuilding orders due to the global economic downturn after the global financial crisis and the rise of Chinese shipbuilding industry. In the first half of the period, productivity change was higher than in the second half. Especially, the difference between the two periods is attributed to the technical change and it was proved by statistical verification. The policy implications of this paper suggest that the government and each DMU need to develop new technologies to cope with changes in the global shipbuilding industry environment and strategies to eliminate inefficiencies in order to increase productivity in the future.