• Journal of the Optical Society of Korea
• /
• v.18 no.5
• /
• pp.546-550
• /
• 2014

To investigate the minimum near-infrared ray intensity required (quantifiable threshold value) for consistent measurements of axial length (AL) using partial coherence interferometry (PCI), we attached two polarizing lenses (PL) to two types of PCI (IOLmaster, ALscan). The near-infrared ray intensity of PCI was modified by rotating the axis of one PL at intervals of 5 degrees. The right eye of each volunteer was measured three times and the AL and signal-to-noise ratio (SNR) was recorded five times for each measurement. Reduction of light intensity was theoretically estimated using Malus' Law. AL was measured consistently with both IOLmaster and ALscan until they reached 55 degrees (1.33 % of intensity) and 60 degrees (0.77%), respectively (P = 0.343, Log-rank test). In contrast, SNR decreased as light intensity decreased. In addition, to analyze media opacities that precluded measurement of AL, we retrospectively reviewed the medical records of patients unmeasurable by PCI (ALscan) from May to November 2013. Thirty-eight of 473 eyes (8.0%) could not be measured using ALscan due to media opacities, such as severe posterior subcapsular cataract (PSC, 11 eyes), hypermature cataract (9 eyes), and vitreous hemorrhage (18 eyes). The mean grades of vitreous haze and PSC were $7.72{\pm}0.96$ and $4.45{\pm}1.04$, respectively. In conclusion, up to 0.77-1.33% of near-infrared rays decreased, and AL could be measured consistently.

• Biomaterials and Biomechanics in Bioengineering
• /
• v.2 no.2
• /
• pp.111-125
• /
• 2015

For engineers, generating a mesh in porous media (PMs) sometimes represents a smaller computational load than generating realistic stent geometries with computer fluid dynamics (CFD). For this reason, PMs have recently become attractive to mimic flow-diverter stents (FDs), which are used to treat intracranial aneurysms. PMs function by introducing a hydraulic resistance using Darcy's law; therefore, the pressure drop may be computed by test sections parallel and perpendicular to the main flow direction. However, in previous studies, the pressure drop parallel to the flow may have depended on the width of the gap between the stent and the wall of the test section. Furthermore, the influence of parameters such as the test section geometry and the distance over which the pressure drops was not clear. Given these problems, computing the pressure drop parallel to the flow becomes extremely difficult. The aim of the present study is to resolve this lack of information for stent modeling using PM and to compute the pressure drop using several methods to estimate the influence of the relevant parameters. To determine the pressure drop as a function of distance, an FD was placed parallel and perpendicular to the flow in test sections with rectangular geometries. The inclined angle method was employed to extrapolate the flow patterns in the parallel direction. A similar approach was applied with a cylindrical geometry to estimate loss due to pipe friction. Additionally, the pressure drops were computed by using CFD. To determine if the balance of pressure drops (parallel vs perpendicular) affects flow patterns, we calculated the flow patterns for an ideal aneurysm using PMs with various ratios of parallel pressure drop to perpendicular pressure drop. The results show that pressure drop in the parallel direction depends on test section. The PM thickness and the ratio of parallel permeability to perpendicular permeability affect the flow pattern in an ideal aneurysm. Based on the permeability ratio and the flow patterns, the pressure drop in the parallel direction can be determined.

• Korean journal of communication and information
• /
• v.40
• /
• pp.150-191
• /
• 2007

Defamation lawsuits of public figures against media have been an issue since Roh government set in. Dissension between the government and media has probably acted as the key factor on this problem. Accordingly, arguments on the defamation lawsuits of public figures occurred the political issues such as opposition between the Progressive and the Conservative Parties or between the ins and the outs and showed the limits to suggest an appropriate judgment or solution. This study will analyze how the court makes its judgement on their rights and the limits by understanding the characteristic and the problem of defamation lawsuits made by senior government officials including a politician, the government, the president, and etc. As results, the defamation lawsuits of politicians and senior government officials showed specially noteworthy matters in salvation (damage suits), the amount claimed, court costs, ratio of winning lawsuits, and etc. The result on the tendency of the court decision showed the following matters in confusion: it holds the media responsible for the burden of proof by applying the inappropriate criterion; The applied laws, especially in the inferior court decision, do not show the consistency of the burden of proof between the misconception/ intention (malice)/ accident/ purpose of slander on the legal principles of public figures. Therefore, this study suggests the court to apply an appropriate law, let alone regulating the Anti-SLAPP law, so that it curtails the rights of public figures; limits the salvation of damage suit; and protects the right only in the case of false accusation by applying the existing law of "the Protection of the Deceased's Defamation Law." In order to dissolve the confusion when applying the laws on the public figures, the study insists the court to positively apply the Constitutional Court made criterion on "people" and "content." The study also insists to distinguish "intention(malice)," "accident," and "purpose of slander" and variant sorts of the burden of proof should be applied to each.

• Journal of Preventive Medicine and Public Health
• /
• v.53 no.3
• /
• pp.171-174
• /
• 2020

The coronavirus disease 2019 (COVID-19) pandemic has not only caused significant challenges for health systems all over the globe but also fueled the surge of numerous rumors, hoaxes, and misinformation, regarding the etiology, outcomes, prevention, and cure of the disease. Such spread of misinformation is masking healthy behaviors and promoting erroneous practices that increase the spread of the virus and ultimately result in poor physical and mental health outcomes among individuals. Myriad incidents of mishaps caused by these rumors have been reported globally. To address this issue, the frontline healthcare providers should be equipped with the most recent research findings and accurate information. The mass media, healthcare organization, community-based organizations, and other important stakeholders should build strategic partnerships and launch common platforms for disseminating authentic public health messages. Also, advanced technologies like natural language processing or data mining approaches should be applied in the detection and removal of online content with no scientific basis from all social media platforms. Furthermore, these practices should be controlled with regulatory and law enforcement measures alongside ensuring telemedicine-based services providing accurate information on COVID-19.

• Nuclear Engineering and Technology
• /
• v.53 no.6
• /
• pp.1846-1857
• /
• 2021

Ultrasonic nondestructive testing is important for monitoring the structural integrity of dissimilar metal welds (DMWs) in pressure vessels and piping in nuclear power plants. However, there is a low probability of crack detection via inspection of DMWs using ultrasonic waves because the grain structures (grain orientations) of the weld area cause distortion and splitting of ultrasonic beams propagating in anisotropic media. To overcome this issue, the grain orientation should be known, and a precise ultrasonic wave simulation technique in anisotropic media is required to model the distortion and splitting of the waves accurately. In this study, a method for nondestructive prediction of the DMW grain orientations is presented for accurate simulation of ultrasonic wave propagation behavior in the weld area. The ultrasonic wave propagation behavior in anisotropic media is simulated via finite-element analysis when ultrasonic waves propagate in a transversely isotropic material. In addition, a methodology to predict the DMW grain orientation is proposed that employs a simulation technique for ultrasonic wave propagation behavior calculation and an optimization technique. The simulated ultrasonic wave behaviors with the grain orientations predicted via the proposed method demonstrate its usefulness. Moreover, the method can be used to determine the focal law in DMWs.

• The Journal of Asian Finance, Economics and Business
• /
• v.7 no.7
• /
• pp.463-474
• /
• 2020

This study aims to investigate the impact of COVID-19 pandemic on the stock markets of sixteen countries. Pooled OLS regression, conventional t-test and Mann-Whitney test are used to estimate the results of the study. We construct a weekly panel data of COVID-19 new cases and stock returns. Pooled OLS estimation result shows that the growth rate of weekly new cases of COVID-19 negatively predicts the return in stock market. Next, the returns on leading stock indices of these countries during the COVID-19 outbreak period are compared with returns during the non-COVID period. We use a t-test and Mann-Whitney test to compare the returns. The results reveal that investors in these countries do not react to the media news of COVID-19 at the early stage of the pandemic. However, once the human-to-human transmissibility had been confirmed, all of the stock market indices negatively reacted to the news in the short- and long-event window. Interestingly, we noticed that the Shanghai Composite Index, which was severely affected during the short-event window, bounced back during the long-event window. This indicates that the Chinese government's drastic measures to contain the spread of the pandemic regained the confidence of investors in the Shanghai Stock Market.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.9 no.2
• /
• pp.1301-1305
• /
• 1967

Ground water flow can be studied with model test. Model test of ground water works are necessary for economic and safe design of the works. Also influence of the ground water flow to the durability and safety of hydraulic structures can be studied with this model. a. Sand model ; Water flow through porous media is the principle of sand model. Darcy's formula is the basic equation, $q=k{\frac{dh}{ds}}^{\circ}. The effect of the ground water flow on the grain system itself is represented with this model only. b. Hele-Shaw model ; In this model use is made of the viscous flow analogy. Viscous fluid such as glycerine flowing through two parallel plates depends on Poiseuille law, $q=-c{\frac{dh}{ds}}$. The analogue can be used vertically and horizontally. c. Heat model ; This is based on the analogy of the Fourier's law for heat conduction and Darcy's law for ground water flow. Especially unsteady problem can be studied with this model. A difficulty of the construction of this model is the isolation, which has to prevent losses of the heat. d. Electirc model ; Ohm's law for electric current is analogous to Darcy's law. Resistance material such as metal foil, graphite block, water with salt added, gelatine with salt added, ete. is connected to electric sources and resistor, and equi-voltage line is detected with galvanometer, $N_aCl$, $CuSo_4$, etc. are used as salt in the model. e. Membrane model ; This model is based on the facts that the deflection of a thin membrane obeys Laplace's equation if there is no load in the direction perpendicular to the membrane, and if the dellection is small.

• The Korean Society of Law and Medicine
• /
• v.11 no.1
• /
• pp.271-296
• /
• 2010

Objective: Poisonous Medicinal herbs can be considered as a risk factor to public health unless they are prescribed by Doctor of traditional Korean medicine. The proper method to manage them should be prepared to prevent risk factors caused by misuse and abuse of the poisonous medicinal herbs and enhance public health. Methods: In this dissertation (paper), the definition, scope, management status, data about pharmacology and toxicity and media release regarding adverse reaction were understood after organizing documents, laws and regulations concerning poisonous medicinal herbs. Also, management methods are suggested by analyzing related examples and regulations in China, Japan and Hong Kong, where the use of herbal medicine is general. Results: Methods for items for poisonous medicinal herbs, safety information management, management based on standardization of traditional processing methodology and reorganization and revision of related laws and regulations are established. Conclusion: Proper laws and regulations are not yet established to manage poisonous medicinal herbs in Korea. In this regard, it is urgent to establish laws and regulations which can apply independently. The purpose of the laws and regulations should be to enhance management of poisonous medicinal herbs and prevent incidence of addiction and death, improving the public health.

• Journal of Ocean Engineering and Technology
• /
• v.20 no.6 s.73
• /
• pp.35-40
• /
• 2006

In recent years, there's been strong demand for seawalls that havea gentle slope and permeability that serveswater affinity and disaster prevention from wave attack. The aim of this study is to examine wave transformation, including wave run-up that propagates on the coastal structures. A numerical model based on the weak nonlinear dispersive Boussinesq equation, together with the unsteady nonlinear Darcy law for fluid motion in permeable layer, is developed. The applicability of this numerical model is examined through Deguchi and Moriwaki's hydraulic model test on the permeable slopes. From this study, it is found that the proposed numerical model can predict wave transformation and run-up on the gentle slope with a permeable layer, but can't show accurate results for slopes steeper than about 1:10.

• Earthquakes and Structures
• /
• v.13 no.5
• /
• pp.465-471
• /
• 2017

This work derives a generalized time fractional differential equation governing wave propagation in a radially vibrating non-classical cylindrical medium. The cylinder is made of a transversely isotropic hyperelastic John's material which obeys frequency-dependent power law attenuation. Employing the definition of the conformable fractional derivative, the solution of the obtained generalized time fractional wave equation is expressed in terms of product of Bessel functions in spatial and temporal variables; and the resulting wave is characterized by the presence of peakons, the appearance of which fade in density as the order of fractional derivative approaches 2. It is obtained that the transversely isotropic structure of the material of the cylinder increases the wave speed and introduces an additional term in the wave equation. Further, it is observed that the law relating the non-zero components of the Cauchy stress tensor in the cylinder under consideration generalizes the hypothesis of plane strain in classical elasticity theory. This study reinforces the view that fractional derivative is suitable for modeling anomalous wave propagation in media.