• Geophysics and Geophysical Exploration
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• v.3 no.2
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• pp.61-69
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• 2000

The free-surface boundary conditions are persistent problem in elastic wave equation modeling by finite-difference method, which can be summarized with the degradation of the accuracy of the solution and limited stability range in Poisson's ratio. In this paper, we propose the mid-point averaging scheme as an alternative way of implementing the free-surface boundary conditions, and present the solution to Lamb's problem to verify our approach.

• Journal of Korean Society for Quality Management
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• v.42 no.1
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• pp.15-32
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• 2014

This study examines the relationship between tip amount and its possible antecedents: bill size, the Big Five personality types, meal type, food quality, atmosphere, service quality, consumer gender, server gender, customer hospitality experience, race, and alcohol consumption. A survey of southeastern undergraduate students was conducted to collect information about the customer, server and customer tipping habits. While the analysis suggests that service is an important factor, it shows that other factors affect tip amount. Furthermore, these factors affect tip amounts in many different ways. Some examples of these factors include bill size, alcohol consumption, gender dynamics, meal type, food quality, and personality type. The conclusion suggests the intuition behind these factors by providing a dissection of their meaning and their importance to servers, customers, and managers alike. Purpose: This study tests restaurant customer tipping habits and some personality traits that have received limited previous attention as predictors of tipping. Methods: This study is that the tip amount was self-reported, business students at a university in a large southeastern city of USA were asked to complete a tipping journal. Results: This study was able to replicate the service-tipping relationship. Moreover, this study reiterated that server friendliness is a very powerful tool to increasing tips. Conclusion: This study strongly indicate that service has a positive relationship with tip amount, and also produce a positive relationship with emotional stability and a negative relationship to conscientiousness.

• International Journal of Computer Science & Network Security
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• v.22 no.1
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• pp.139-148
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• 2022

Research into wireless sensor networks (WSNs) is a trendy issue with a wide range of applications. With hundreds to thousands of nodes, most wireless sensor networks interact with each other through radio waves. Limited computational power, storage, battery, and transmission bandwidth are some of the obstacles in designing WSNs. Clustering and routing procedures have been proposed to address these concerns. The wireless sensor network's most complex and vital duty is routing. With the Greedy Perimeter Stateless Routing method (GPSR), an efficient and responsive routing protocol is built. In packet forwarding, the nodes' locations are taken into account while making choices. In order to send a message, the GPSR always takes the shortest route between the source and destination nodes. Weighted directed graphs may be constructed utilising four distinct distance metrics, such as Euclidean, city block, cosine, and correlation distances, in this study. NS-2 has been used for a thorough simulation. Additionally, the GPSR's performance with various distance metrics is evaluated and verified. When compared to alternative distance measures, the proposed GPSR with correlation distance performs better in terms of packet delivery ratio, throughput, routing overhead and average stability time of the cluster head.

• Korea Trade Review
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• v.47 no.5
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• pp.75-93
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• 2022

Purchasing Power Parity (hereafter, PPP) means the purchasing power of two currencies is the same when one is converted into the other one. According to previous studies on PPP, as the volatility of the real exchange rate is smaller, PPP may be more likely to hold. Since New Zealand adopted the inflation targeting policy in December 1989, many countries started to adopt it as their monetary policy frame. Previous studies on inflation targeting found that inflation targeting policy has positive effects on not only achieving price stability but also reducing the volatility of nominal/ real exchange rates. Therefore, in this study, I explored whether inflation targeting policy has positive effects on purchasing power parity subject to 19 OECD countries, applying an Exponential Smooth Transition Autoregressive (ESTAR) model during the sample periods, from 1974:Q1 to 2019:Q4. Based on the ESTAR estimate results, I found limited favorable evidence of PPP for only two countries- England and Switzerland- among 9 inflation targeters, compared to non-inflation targeters, and also I found that favorable evidence of PPP only for these two countries among 9 inflation targeters during post-inflation targeting, but not during pre-inflation targeting. These findings imply that the positive effects of inflation targeting on PPP may be questionable unlike Ding and Kim (2012) and Kim (2014)'s study.

• ETRI Journal
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• v.46 no.1
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• pp.22-34
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• 2024

Exposure to varied noisy environments impairs the recognition performance of artificial intelligence-based speech recognition technologies. Degraded-performance services can be utilized as limited systems that assure good performance in certain environments, but impair the general quality of speech recognition services. This study introduces an audiovisual speech recognition (AVSR) model robust to various noise settings, mimicking human dialogue recognition elements. The model converts word embeddings and log-Mel spectrograms into feature vectors for audio recognition. A dense spatial-temporal convolutional neural network model extracts features from log-Mel spectrograms, transformed for visual-based recognition. This approach exhibits improved aural and visual recognition capabilities. We assess the signal-to-noise ratio in nine synthesized noise environments, with the proposed model exhibiting lower average error rates. The error rate for the AVSR model using a three-feature multi-fusion method is 1.711%, compared to the general 3.939% rate. This model is applicable in noise-affected environments owing to its enhanced stability and recognition rate.

• Journal of Families and Better Life
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• v.28 no.1
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• pp.1-11
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• 2010

The purpose of this study is to compare the cognition of SIDS as the first step for decreasing the SIDS death rate for the infant and for activity of infant-care in Korea. Participants were 409 child care center directors and 146 parents from 500 child care center directors and 200 parents who using child care center facilities for their children in Seoul. For analysis of research questions, frequencies, Cronbach $\alpha$, t-test,One-way ANOVA, Scheffee test were used with SPSSWIN 15.0. Through this study, we find the child care center directors have good cognition for it, but their effort for SIDS prevention is limited, because they don't have any official prevention education from authorized training center. Even though the parents have a low awareness for SIDS prevention than child care center directors, but they have high score in endeavor for SIDS precaution. Both child care center directors and parents want to receive systematic information from government side. Our infant should have a opportunity to grow up health and stability from reducing the risk of SIDS. In western countries such as U.S.A., U.K. and Japan have studied to decrease the SIDS death rate from thirty years ago, they have already government and social organization for preventing the SIDS. Nowadays, as you know well, our country birth-rate is falling by 1.08, therefore, it is important to decrease the infant death rate for keeping with our population. Also, it is relevant to the child-welfare and the child-safety and more better the child-care.

• Membrane Journal
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• v.32 no.5
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• pp.265-274
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• 2022

Separation of oily wastewater, which is a byproduct of various industries such as petroleum refineries, is essential to not exceed the tolerance limit of wastewater streams. Ceramic membranes show potential in oily wastewater separation, due to their excellent oil removal efficiency, good chemical, thermal, and mechanical stability, and simple operation. However, widespread application of ceramic membranes is limited due to high material cost of alumina, silica, and other ceramic based materials used to fabricate them. Recent efforts to reduce material cost have been made, using fly ash and clay. This review examines the fabrication and efficiency of ceramic membranes in oily wastewater separation according to material: silica, alumina, and waste ash.

• Membrane Journal
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• v.33 no.1
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• pp.13-22
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• 2023

Despite high capacity of lithium metal anode, its uncontrollable dendrite growth results in the poor electrochemical (EC) performance (low Coulomb efficiency and limited cycle stability) and unsafe operation. In this study, we demonstrated a lithium metal anode protected with BaTiO₃/PVDF based piezoelectric layer to enhance its EC performance by utilizing the locally polarized lithium metal after volume expansions. As-formed lithium metal electrode deposited with BTO@PVDF layer exhibited an enhanced Coulombic efficiency (> 98% for 100 cycles) and facilitated lithium ion diffusions (lithium diffusion coefficient: D_Li+), revealing the effectiveness of piezoelectric layer deposited lithium metal electrode approach.

• Food Science of Animal Resources
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• v.37 no.3
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• pp.440-448
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• 2017

This study was conducted to establish the shelf life of $1^{++}$ grade Hanwoo beef by evaluating the changes in meat quality and storage stability under distribution conditions similar to those during export to Hong Kong and China. Four muscles of the loin, striploin, tenderloin, and top round muscles were obtained from 10 animals of $1^{++}$ grade Hanwoo steers. The distribution conditions were 0, 7, or 14 d of aging at $2^{\circ}C$ and continuous storage at $-18^{\circ}C$ for 0, 3, 6, or 9 mon. The lightness (CIE $L^*$) values decreased as the duration of freezer storage increased (p<0.05). The water-holding capacity of 4 muscles increased as the aging time increased when they were frozen for 3 mon (p<0.05). The cooking loss values of the four muscles were significantly increased as the duration of freezer storage increased (p<0.05). The Warner-Bratzler shear force values were significantly decreased in the loin, striploin, and top round muscles as the aging time increased (p<0.05). The changes in volatile basic nitrogen (16.67-18.49 mg%) and thiobarbituric reactive substance values (0.75-0.82 mg MA/kg meat) were significantly increased when the meat was frozen for 9 mon after 14 d of aging. On the basis of these observations, the shelf life of $1^{++}$ grade Hanwoo beef during distribution should be limited to less than 9 mon of freezer storage at $-18^{\circ}C$ after 14 d of aging at $2^{\circ}C$.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.18 no.1
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• pp.51-59
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• 2005

SLSV (single loop single vector) method is to solve the excessive computational cost problem in RBDO (reliability-based design optimization) by decoupling the nested iteration loops. However, the practical use of SLSV method to RBDO case is limited by the instability or inaccuracy of the method since it often diverges or converges to a wrong solution. Thus, in this paper, a new modified SLSV method is proposed. This method improves its convergence capability effectively by utilizing Inactive Design and Active MPP Design together with modified HMV (hybrid mean value) method. The usefulness of the proposed method is also verified through numerical examples.