• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.6
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• pp.457-461
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• 2013

In this paper, a novel method based on geometrical optics is proposed to calculate the optical characteristics of an electric field driven liquid crystal (ELC) lens. For an optimally designed ELC lens, effective refractive index is calculated and then ray tracing is carried out using Huygens' principle. From the results, the intensity distribution at the optimum viewing distance (OVD) is obtained. To confirm the validity of our work, the result is compared with that calculated by the extended Jones matrix method (EJMM). As a result, it turns out that the novel method provides more simple and rigorous simulation results than the EJMM.

• Journal of Preventive Medicine and Public Health
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• v.27 no.2 s.46
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• pp.226-229
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• 1994

In hypertensives, electrocardiographic left ventricular hypertrophy (LVH) is an independent risk factor for cardiovascular disease. Animal and human studies suggest an association between left ventricular mass and dietary sodium (Na) intake. This study determined if dietary Na intake in a homogenous ethnic population is associated with electrocardiographic LVH (S in Vl + R in $V5{\geq}5.5 mV$). Blood pressure (BP), body mass index, EKG, and 24 hour urine Na and potassium (K) excretion were determined in 40 otherwise healthy Korean patients with untreated essential hypertension on the standard Korean diet. Among these variables, only Na excretion (mmol/day) was significantly different between those with and without LVH $[LVH+:357{\pm}50,\;LVH-;\;268{\pm}25(p=0.04]$. Thus, dietary sodium intake may be predictive of electrocardiographic LVH.

• Journal of the Korean Society of Industry Convergence
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• v.27 no.2_2
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• pp.467-473
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• 2024

Metaheuristics' impact is profound across many fields, yet domestic financial portfolio optimization research falls short, particularly in asset allocation. This study delves into metaheuristics for portfolio optimization, examining theoretical and practical benefits. Findings indicate portfolios optimized via metaheuristics outperform the Dow Jones Index in Sharpe ratios, underscoring their potential to enhance risk-adjusted returns significantly. Tabu search, in comparison to Simulated Annealing, demonstrates superior performance by efficiently navigating the search space. Despite these advancements, practical application remains challenging due to the complexities in metaheuristic implementation. The study advocates for broader algorithmic exploration, including population-based metaheuristics, to refine asset allocation strategies further. This research marks a step towards optimizing portfolios from an extensive array of financial assets, aiming for maximum efficacy in investment outcomes.

• Journal of Digital Convergence
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• v.18 no.1
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• pp.121-127
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• 2020

This study analyzed through GEM-listed companies for verifying the interrelationship between positive and negative impacts on accounting information GEM-listed companies, whether venture firms operate the internal control operation system stably. Hong Kong's GEM listed company is a securities market similar to Korea's KOSDAQ market. To analyzing this study, used regression analysis method through internal control index to evaluate the operation of internal control system and discretionary accruals to evaluate the quality of accounting information. In this study, because profit adjustments used to realize through discretionary accruals, so analyzed using the modified Jones model to check whether the management deliberately transformed the company to realize future profits. In the empirical analysis, the correlation between the internal control index and the discretionary accruals to assess the quality of accounting information was able to find highly correlated. This study can provide useful guidance for evaluating the form and value of profit management of venture firms in the future, also would expect to help understand the financial environment of emerging venture firms.

• Journal of the Korea Society of Computer and Information
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• v.25 no.5
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• pp.47-56
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• 2020

The stock index is used not only as an economic indicator for a country, but also as an indicator for investment judgment, which is why research into predicting the stock index is ongoing. The task of predicting the stock price index involves technical, basic, and psychological factors, and it is also necessary to consider complex factors for prediction accuracy. Therefore, it is necessary to study the model for predicting the stock price index by selecting and reflecting technical and auxiliary factors that affect the fluctuation of the stock price according to the stock price. Most of the existing studies related to this are forecasting studies that use news information or macroeconomic indicators that create market fluctuations, or reflect only a few combinations of indicators. In this paper, this we propose to present an effective combination of the news information sentiment analysis and various macroeconomic indicators in order to predict the US Dow Jones Index. After Crawling more than 93,000 business news from the New York Times for two years, the sentiment results analyzed using the latest natural language processing techniques BERT and NLTK, along with five macroeconomic indicators, gold prices, oil prices, and five foreign exchange rates affecting the US economy Combination was applied to the prediction algorithm LSTM, which is known to be the most suitable for combining numeric and text information. As a result of experimenting with various combinations, the combination of DJI, NLTK, BERT, OIL, GOLD, and EURUSD in the DJI index prediction yielded the smallest MSE value.

• Tribology and Lubricants
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• v.19 no.4
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• pp.230-236
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• 2003

In applications such as MEMS and NEMS devices, the adhesion force and contact load may be of the same order of magnitude and the static friction coefficient can be very large. Such large coefficient may result in unacceptable and possibly catastrophic adhesion, stiction, friction and wear. To obtain the static friction coefficient of contacting real surfaces without the assumption of an empirical coefficient value, numerical simulations of the contact load, tangential force, and adhesion force are preformed. The surfaces in dry contact are statistically modeled by a collection of spherical asperities with Gaussian height distribution. The asperity micro-contact model utilized in calculation (the ZMC model), considers the transition from elastic deformation to fully plastic flow of the contacting asperity. The force approach of the modified DMT model using the Lennard-Jones attractive potential is applied to characterize the intermolecular forces. The effect of the surface topography on the static friction coefficient is investigated for cases rough, intermediate, smooth, and very smooth, respectively. Results of the static friction coefficient versus the external force are presented for a wide range of plasticity index and surface energy, respectively. Compared with those obtained by the GW and CEB models, the ZMC model is more complete in calculating the static friction coefficient of rough surfaces.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.2
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• pp.69.1-69.1
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• 2017

According to structure formation simulations, weak shocks with typical Mach number, M<3, are expected to form in merging galaxy clusters. The presence of such shocks has been indicated by X-ray and radio observations of many merging clusters. In particular, diffuse radio sources known as radio relics could be explained by synchrotron-emitting electrons accelerated via diffusive shock acceleration (Fermi I) at quasi-perpendicular shocks. Here we also consider possible roles of stochastic acceleration (Fermi II) by compressive MHD turbulence downstream of the shock. Then we explore a puzzling discrepancy that for some radio relics, the shock Mach number inferred from the radio spectral index is substantially larger than that estimated from X-ray observations. This problem could be understood, if shock surfaces associated with radio relics consist of multiple shocks with different strengths. In that case, X-ray observations tend to pick up the part of shocks with lower Mach numbers and higher kinetic energy flux, while radio emissions come preferentially from the part of shocks with higher Mach numbers and higher cosmic ray (CR) production. We also show that the Fermi I reacceleration model with preexisting fossil electrons supplemented by Fermi II acceleration due to postshock turbulence could reproduce observed profiles of radio flux densities and integrated radio spectra of two giant radio relics. This study demonstrates the CR electrons can be accelerated at collisionless shocks in galaxy clusters just like supernova remnant shock in the interstellar medium and interplanetary shocks in the solar wind.

• Journal of Korea Society of Digital Industry and Information Management
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• v.19 no.4
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• pp.179-192
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• 2023

ESG is the hottest topic in recent business management or business administration. In particular, with the release of the IPCC's 6th comprehensive report in 2023, environmental issues have been further raised around the world, and ESG management for sustainable and permanent companies is accelerating by improving social and governance structures, including the environment, and thereby enhancing corporate value. This case study is analyzed based on the theory of sustainable growth, creating shared value, and corporate social responsibility. This study focuses on the case of Samsung Biologics, which is pursuing sustainable growth and management through ESG management. Samsung Biologics is the first Korean company to win the "Terra Carta Seal" award, part of a sustainable market initiative to respond to climate change, and externally, it has acquired the Dow Jones Sustainability Index, acquired the KCGS ESG comprehensive evaluation A grade, acquired the CDP B grade, and acquired the EcoVadis Gold grade. It has joined the Sustainable Market Initiative launched by King Charles III since the World Economic Forum in 2020 to chair the Supply Chain. It has joined RE100, TCFD, and UN Global Compact to lead sustainable management through ESG activities. Therefore, we would like to take a practical approach to ESG management strategies for sustainable growth through the example of this company.

• Archives of Reconstructive Microsurgery
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• v.24 no.2
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• pp.62-67
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• 2015

Purpose: Pollicization typically involves surgical migration of the index finger to the position of the thumb. This procedure facilitates the conversion of a useless hand into a well-functioning one in patients who are not amenable to the toe-to-hand transfer. However, middle finger pollicization has been rarely reported. Materials and Methods: We reconstructed a thumb by immediate pollicization of the remnants of the middle finger in two patients who sustained a tumor and a trauma, respectively. The former, after cancer ablation was performed, has not been reported literally, and the latter involved free devitalized pollicization of the middle finger using a microsurgical anastomosis. The distal third extensor communis tendon was sutured to the proximal extensor pollicis longus tendon and the distal flexor digitorum superficialis and profundus were sutured to the proximal flexor pollicis longus. The abductor pollicis brevis tendon was sutured to the distal end of the first palmar interosseous muscle. Coaptation of the third digital nerve and the superficial radial nerve branch was performed. Results: Patients showed uneventful postoperative courses without complication such as infection or finger necrosis. Based on the principles of pollicization, a wide range of pinch and grasp movements was successfully restored. They were pleased with the functional and cosmetic results. Conclusion: Although the index finger has been the digit of choice for pollicization, we could also use the middle finger on specific occasions. This procedure provides an excellent option for the reconstruction of a mutilated thumb and could be performed advantageously in a single step.

• Journal of the Korea Convergence Society
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• v.9 no.11
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• pp.307-313
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• 2018

In this study, analyzed the effect of the introduction and operation of internal control system of a company on accounting information usefulness in a rapidly changing business environment. In order to conduct this study, we studied a comprehensive analysis on the usefulness of internal control and accounting information, and applied the research model to the purpose of this study. In this study, we analyzed the degree of the relationship between variables based on the discretionary accruals of the modified Jones model using the internal control evaluation index based on the components of the internal control system for China. In the empirical analysis, analyzed that the operation of internal control has a negative influence on discretionary accruals, which is a substitute for usability of accounting information. In addition, the risk management factors of the internal control system have a negative correlation with the usefulness of accounting information. The results of this study suggest that it is possible to present the positive function of internal control system to many firms where the introduction and operation of internal control is important, and to provide useful guidance in the study of the relationship between the operation of internal control and discretionary accruals for foreign company.