• Journal of the Korean Data and Information Science Society
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• v.28 no.2
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• pp.371-381
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• 2017

There has never been research on Chaos analysis using real estate auction sale price rate in Korea. In this study, three Chaos analysis methodologies - Hurst exponent, correlation dimension, and maximum Lyapunov exponent - in order to capture the nonlinear deterministic dynamic system characteristics. High level of Hurst exponent and the extremely low maximum Lyapunov exponent provide the tendency and the persistence of the data. The empirical results give two meaningful facts. First, monthly time lags of the correlation dimension are coincident with the time period from the approval auction start day to the sale price fixing day. Second, its weekly time lags correspond to the time period from the last day of request for sale price allocation to the sale price fixing day. Then, this study potentially examines the predictability of the real estate auction price rate time series.

• KIPS Transactions on Software and Data Engineering
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• v.10 no.7
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• pp.263-270
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• 2021

Reinforcement learning(RL) is the method to find an optimal policy through training. and it is one of popular methods for solving lifesaving and disaster response problems effectively. However, the conventional reinforcement learning method for disaster response utilizes either simple environment such as. grid and graph or a self-developed environment that are hard to verify the practical effectiveness. In this paper, we propose the design of a disaster response RL environment which utilizes the detailed property information of the disaster simulation in order to utilize the reinforcement learning method in the real world. For the RL environment, we design and build the reinforcement learning communication as well as the interface between the RL agent and the disaster simulation. Also, we apply the dimension reduction method for converting non-image feature vectors into image format which is effectively utilized with convolution layer to utilize the high-dimensional and detailed property of the disaster simulation. To verify the effectiveness of our proposed method, we conducted empirical evaluations and it shows that our proposed method outperformed conventional methods in the building fire damage.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2004.05a
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• pp.73-78
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• 2004

For the preliminary stages of ship design it is necessary to develop a basic design, which specifies the main particulars of the vessel. based on the requirements given by the owner. An efficient design enables the shipyard to make a rough estimate of the construction costs and to put forward a favourable quote during the call for tenders. The parametric determination of the main particulars of the vessel involves the application of empirical formulae. These formulae have been created after detailed tests and research by maritime research institutions and researchers had been carried out. Here, the design of a medium sized Bulk Carrier (26000t dwt) with a service speed of 17 knots for carrying rice and rock phosphate has been illustrated. Medium sized Bulk Carriers (25,000t dwt - 50,000t dwt) are in steady demand among small shipping companies. They have a size advantage, in that port size restrictions do not affect their design tremendously. Nevertheless, structurally. they are one of the most difficult to build. During design, the rules of the maritime regulatory bodies were strictly adhered to.

• International Commerce and Information Review
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• v.11 no.3
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• pp.3-24
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• 2009

Import Agency Service Mall, providing customers not only with convenient shopping experiences but also with purchasing, warehousing, shipping, and customs clearance services, have been playing a significant role in rapidly transforming Korean consumers into global consumers. The consumers' great demand for foreign goods(services) has created Import Agency Service Mall(referred to hereafter as IASM) as a new business model of distribution and consumption, which seems to be grown rapidly. This empirical research investigates online shoppers for their trust dimensions for IASM. Consequences of the research are as follows: First, perceived reputation, web-site quality have influenced upon e-trust dimension of the IASM. Second, the level of e-trust consumers is more higher, and then the level of perceived risk is more lower. Third, perceived risk have not influenced upon intention to reuse the IASM. Fourth, the level of e-trust consumers is more higher, and then the level of intention to reuse the IASM is more higher. It is necessary for IASM to be developed its reputation and web-site quality in order to obtain customer's trust. Accordingly, this research will be helping IASM have insight for marketing strategies, and constantly should be studied about action and mind of consumer.

• Journal of Korea Foundry Society
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• v.15 no.5
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• pp.494-506
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• 1995

Test castings in plate, disc, and cubic shaped castings for 0.2wt.% carbon and stainless steel have been poured to examine the effects of the riser dimensions including riser neck on the casting soundness. Three empirical methods were chosen in risering of steel castings. A computer program of solidification analysis considering liquid and solidification contraction was developed to apply for riserdesign calculated by using their methods in plate, disc, and cubic shaped castings, and to calculate the position and dimension of shrinkage cavity in complex shaped casting. The potential of present method has been successfully demonstrated by comparing predicted cavity shapes with those obtained in a series of experimental castings. Three empirical methods can be used in a practical way to make a rapid estimation of tie minimum riser diameter, but they can not provide a criterion of casting soundness with shape and material on all occasions. The shape and position of shrinkage cavity can be successfully predicted both using the present method and using risering calculated by their methods regardless of the shape and cast material.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.30 no.3
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• pp.103-108
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• 2007

This paper presents the conceptual framework for estimating and predicting system's susceptibility to failure as function of condition parameter value which is representing the current status of performance measure using on-line performance reliability. The performance of such system depends on one parameter with a probability distribution that degrades with time gracefully. Performance reliability represents the probability that physical performance will remain satisfactory over a finite period of time or usage cycles in the future. An empirical physical performance function is constructed to incorporate explanatory variables (operating and environmental conditions) over a time or usage dimension. This function enables one to model device performance and the associated classical reliability measures simultaneously, in the performance domain and time domain. The conditional performance reliability structure developed represents a tool to predict system performance over time or usage for next usage period. By enabling such a framework, it can bring us more efficient planning and execution in system's operation control as well as maintenance to reduce costs and/or increase profits.

• Management & Information Systems Review
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• v.6
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• pp.89-115
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• 2001

Recently, administrators of Korean university are struggling to survive against rapidly changing environment. But, the customer service of university organizations are generally recognized inferior to those of business service. Thus, the measuring of service quality is the beginning of works to improve customer service in university. SERVQUAL is known the most generalized scale to measure service quality. After SERVQUAL was published as a measure of perceived service quality by PZB(1985), several arguments have been made against its validity and the other measures have been suggested by Tears(1993), Cronin and Taylor(1992). Therefore, this paper reviews about SERVQUAL controversies. Also, this paper analyzed the dimensions of service quality and its relevant concepts. For this empirical study, 288 respondents drawn from university student in Pusan area are collected and 5 hypotheses are analyzed by using regression analysis. The results of empirical study are as follows. (1) three dimensions of service quality(specialty, reliability, tangiables) are perceived from factor analysis. (2) dimensions of service quality are related to the overall service quality and customer satisfaction, especially specialty is varified as the most important dimension. (3) customer satisfaction affects repurchase intention and word-of-mouth effect positively. In conclusion, however this study have a few limitations about sampling and questionnaire, offers some strategic directions for improving the service quality of university organizations.

• Korea Trade Review
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• v.47 no.4
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• pp.233-254
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• 2022

Although there is growing literature evidence of linkages between global value chains (GVCs) and foreign direct investment (FDI), the results are mixed and ambiguous by geographic dimension, time period and sectoral scope. Moreover, bilateral approaches on these connections have been rarely analyzed. In this context, we investigate the effect of bilateral greenfield FDI and cross-border M&A on GVC linkages between host countries and source countries. We match three-year averages of bilateral FDI and UNCTAD-Eora GVC value-added data from 2005 to 2019 between 37 OECD sources and 176 host countries (37 OECD versus 139 non-OECD countries). In the structural gravity model, the empirical specification includes bilateral and country-period fixed effects and uses a Poisson Pseudo-Maximum Likelihood (PPML) estimator. We find that greenfield and M&A FDI promote forward and backward GVC linkage for all sectors between OECD countries, whereas greenfield FDI promotes backward GVC linkage between OECD and non-OECD countries. In addition, the results indicate that the degree of influence of GVCs by FDI flows is greater for forward GVC than backward GVC among OECD countries.

• Science of Emotion and Sensibility
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• v.26 no.1
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• pp.33-42
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• 2023

Previous emotion studies employing facial expressions have focused on the differences between age groups for each of the emotion categories. Instead, Kim (2021) has compared representations of facial expressions in the lower-dimensional emotion space. However, he reported descriptive comparisons without statistical significance testing. This research used representational similarity analysis (Kriegeskorte et al., 2008) to directly compare empirical datasets from young, middle-aged, and old groups and conceptual models. In addition, individual differences multidimensional scaling (Carroll & Chang, 1970) was conducted to explore individual weights on the emotional dimensions for each age group. The results revealed that the old group was the least similar to the other age groups in the empirical datasets and the valence model. In addition, the arousal dimension was the least weighted for the old group compared to the other groups. This study directly tested the differences between the three age groups in terms of empirical datasets, conceptual models, and weights on the emotion dimensions.

• Geomechanics and Engineering
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• v.9 no.5
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• pp.619-629
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• 2015

Influenced by various mining activities, fractures in rock masses have different densities, set numbers and lengths, which induce different mechanical properties and failure modes of rock masses. Therefore, precisely expressing the failure criterion of the fractured rock influenced by coal mining is significant for the support design, safety assessment and disaster prevention of underground mining engineering subjected to multiple mining activities. By adopting PFC2D particle flow simulation software, this study investigated the propagation and fractal evolution laws of the micro cracks occurring in two typical kinds of rocks under uniaxial compressive condition. Furthermore, it calculated compressive strengths of the rocks with different confining pressures and box-counting dimensions. Moreover, the quantitative relation between the box-counting dimension of the rocks and the empirical parameters m and s in Hoek-Brown strength criterion was established. Results showed that with the increase of the strain, the box-counting dimension of the rocks first increased slowly at the beginning and then exhibited an exponential increase approximately. In the case of small strains of same value, the box-counting dimensions of hard rocks were smaller than those of weak rocks, while the former increased rapidly and were larger than the latter under large strain. The results also presented that there was a negative correlation between the parameters m and s in Hoek-Brown strength criterion and the box-counting dimension of the rocks suffering from variable mining activities. In other words, as the box-counting dimensions increased, the parameters m and s decreased linearly, and their relationship could be described using first order polynomial function.