• International Journal of Vascular Biomedical Engineering
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• v.2 no.2
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• pp.27-32
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• 2004

The objective of the present study is to visualize the steady and pulsatile flow fields in a branching model by using a high-resolution PIV system. A bifurcated flow system was built for the experiments in the steady and pulsatile flows. Harvard pulsatile pump was used to generate the pulsatile velocity waveforms. Conifer powder as the tracing particles was added to water to visualize the flow fields. CCD cameras($1K{\times}1K$(high resolution camera) and $640{\times}480$(low resolution camera)) captured two consecutive particle images at once for the image processing of several cross sections on the flow system. The range validation method and the area interpolation method were used to obtain the final velocity vectors with high accuracy. The results of the image processing clearly showed the recirculation zones and the formation of the paired secondary flows from the distal to the apex of the branch flow in the bifurcated model. The results also indicated that the particle velocities at the inner wall moved faster than the velocities at the outer wall due to the inertial force effects and the helical motions generated in the branch flows as the flow proceeded toward the outer wall. Even though the PIV images from the high resolution camera were closer to the simulation results than the images from the low resolution camera at some locations, both results of the PIV experiments from the two cameras generally agreed quite well with the results from the computer simulations. Therefore, instead of using the expensive stereoscopic PIV or 3D PIV system, the three-dimensional flow fields in a bifurcated model could be easily and exactly investigated by this study.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.1
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• pp.309-317
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• 2015

Recently many companies began to realize their visions for the sustainable growth with the advent of CSV(Creating Shared Values). Michael E. Porter, a Harvard Professor, claims that placing social value creation at the core of business strategy has the potential to uncover big opportunities for individual companies and that shared value can play a significant role in increasing competitive advantages while fostering social prosperity. In consequence, the various researches have illustrated how to get the opportunity for competitive advantages from building a social value proposition into corporate strategy, and considerable studies have been promoted heavily from the managerial perspective. However, due to the lack of capability converging information technology with business strategy, any research effort to identify technological or Internet-related issues and to link the issues to CSV does not exist. With Korean being a Internet leading country, the demands of researches analyzing core technology, information, and service utilizing Internet are rapidly growing. The study aims to find out Internet-related enablers for CSV. This paper describes the concepts and features of CSV, identifies emerging Internet-related issues toward the opportunity for competitive advantage, and then depicts the rigorous research endeavors in the areas of Internet information, technology, and services. As a result, 11 papers presented and selected as the outstanding papers at APIC-IST 2014 handle the issues to be brought together, which include: Wireless and Sensor Network, Image Processing and HCI, Big Data and Business Intelligence, Security & Privacy in Internet, SNS & Communication, Smart-Learning and e-Learning, and Internet Business Strategy. The study finally recommends indispensible terms for substantially vitalizing CSV.

• The Korean Journal of Applied Statistics
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• v.17 no.3
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• pp.573-594
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• 2004

Four statistics books, one translated by statisticians and three by non-statisticians, are reviewed. They are reviewed in terms of indices and bibliographies, statistical theory and terms, and the history of statistics. In addition, book review articles appeared in daily newspapers are considered. Unfortunately, we can find many(some of them trivial, and some others serious) problems in the translations. Many problems could have been got around if the books had been translated by statisticians. So, conclusion suggested in this article is very simple: Translation of statistics books, especially books for the laymen, is a job that Korean statisticians should not shift to others. Titles of the books reviewed in this article are as follows. 1. Rao, C. Radhakrishna(1997). Statistics and Truth : Putting Chance to Work, Second edition, World Scientific. 2. Best, Joel (2001). Damnel lies and Statistics : Understanding Numbers from the Media, Politicians, and Activists, University of California Press. 3. Bennett, Deborah J. (1998). Randomness, Harvard University Press; 4. Salsburg, David (2001). The Lady Tasting Tea : How Statistics Revolutionized Science in the Twentieth Century, W. H. Freeman.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.5
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• pp.1851-1856
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• 2012

Immigration to a nation with a stronger anti-smoking environment has been hypothesized to make smoking less common. However, little is known about how environments influence risk of smoking across the lifecourse. Research suggested a linear decline in smoking over the lifecourse but these associations, in fact, might not be linear. This study assessed the possible nonlinear associations between age and smoking and examined how these associations differed by environment through comparing Koreans in Seoul, South Korea and Korean Americans in California, United States. Data were drawn from population based telephone surveys of Korean adults in Seoul (N=500) and California (N=2,830) from 2001-2002. Locally weighted scatterplot smoothing (lowess) was used to approximate the association between age and smoking with multivariable spline logistic regressions, including adjustment for confounds used to draw population inferences. Smoking differed across the lifecourse between Korean and Korean American men. The association between age and smoking peaked around 35 years among Korean and Korean American men. From 18 to 35 the probability of smoking was 57% higher (95%CI, 40 to 71) among Korean men versus 8% (95%CI, 3 to 19) higher among Korean American men. A similar difference in age after 35, from 40 to 57 years of age, was associated with a 2% (95%CI, 0 to 10) and 20% (95%CI, 16 to 25) lower probability of smoking among Korean and Korean American men. A nonlinear pattern was also observed among Korean American women. Social role transitions provide plausible explanations for the decline in smoking after 35. Investigators should be mindful of nonlinearities in age when attempting to understand tobacco use.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.10a
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• pp.281-284
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• 2008

This paper describes ASIC design of multimedia SoC Platform. The implemented Platform consists of 32-bit OpenRISC1200 Microprocessor, WISHBONE on-chip bus, VGA Controller, Debug Interface, SRAM Interface and UART. The 32-bit OpenRISC1200 processor has 5 stage pipeline and Harvard architecture with separated instruction/data bus. The VGA Controller can display RCB data on a CRT or LCD monitor. The Debug Interface supports a debugging function for the Platform. The SRAM Interface supports 18-bit address bus and 32-bit data bus. The UART provides RS232 protocol, which supports serial communication function. The Platform is design and verified on a Xilinx VERTEX-4 XC4VLX80 FPGA board. Test code is generated by a cross compiler' and JTAG utility software and gdb are used to download the test code to the FPGA board through parallel cable. Finally, the Platform is implemented into a single ASIC chip using Chatered 0.18um process and it can operate at 100MHz clock frequency.

• The Journal of Korean Society of Virology
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• v.29 no.2
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• pp.107-118
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• 1999

To characterize the molecular nature of human immunodeficiency virus (HIV)-1, we determined the full-length HIV-1 sequences from cultured peripheral blood mononuclear cells (PBMC) of a Korean long-term nonprogressor (LTNP). Without antiretroviral therapy, the individual has maintained CD4+ T counts over $500/{\mu}l$ from 1989 to 1999. Plasma viral RNA copy was 992 U/ml in 1998. Culture supernatant showed positive from culture days 9. A series of 9 overlapping PCR products were amplified from cultured PBMC and cloned About 9.2 kb from R of 5' LTR to R of 3' LTR was determined by automated sequencing. The G-to-A hypermutations were shown throughout the entire region. As a result of G to A hypermutations, premature stop codon was found in integrase coding region. Though there was no recombination between subtypes over all genomes, TATA box in both LTRs was TAAAA which is detected in subtype E instead of TATAA in subtype B. And, there were nucleotide GC insertion between $NF-{\kappa}B$ I and Sp1 III, and duplication of $TCF-1{\alpha}$ in LTR. We could not find any deletion of amino acid in Nef, Gag, Pol and Env gene. This study is the first report on molecular nature of full genomes of HIV-1 isolated in Korea.

• Journal of Physiology & Pathology in Korean Medicine
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• v.18 no.1
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• pp.69-74
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• 2004

We have examined the relaxative response to the water extract of Rheum undulatum L. (ERU) and water extract of alcohol steamed Rheum undulatum L. (SRU) with isolated thoracic aorta from sprague dawley (SD) rat. Rat thoracic aorta was investigated in vessel segments suspended for isometric tension recording by polygraph. Responses to ERU and SRU were investigated in vessels precontracted with 5-hydroxytryptamine(5-HT). We found that the thoracic aorta segments responded to ERU and SRU with a dose-dependent vasorelaxation : The thoracic aorta segments responded to ERU and SRU with a dose-dependent vasodilation. The amounts of emodin were 0.063%, 0.076% and 0.145% in ERU and SRU, respectable. The 5-HT induced contraction at 10-4M were inhibited by 85.2±4.76% and 84.0±2.91% after addition of the 0.1mg/mL water extract of ERU and SRU. The 5-HT induced contraction at 10/sup -3/M were inhibited by 100% after 10/sup -3/M emodin. In conclusion, vasodilation effect of the water extract of Rheum undulatum L. in rat thoracic aorta was not decreased according to the processing of alcohol steamed Rheum undulatum L.

• Journal of Soil and Groundwater Environment
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• v.21 no.2
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• pp.1-7
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• 2016

Ferrous slag is a by-product from steel making process and waste concrete is generated from construction activities. Large part of ferrous slag and waste concrete are recycled as construction materials. However, Ca²⁺ leaching out of ferrous slag and waste concrete in the water-contacting environment can cause a strength change. Strength can be reduced due to the dissolution of solid form of CaO which is one of the main contents of ferrous slag and waste concrete. On the other hand, strength can be enhanced due to the pozzolanic reaction of cementitious components with water. In this study, steelmaking slag, blast furnace slag, and waste concrete were aged by exposure to raining events, and the change of their compaction and shear strength characteristics was investigated. Optimum moisture content of all materials used in this study increased with aging period while maximum dry unit weight slightly decreased, implying that the relative contents of fine particles increased as the CaO solid particles were dissolved. Internal friction angle and shear strength of recycled materials also increased with aging period, indicating that the materials became denser by the decrease of void ratio attributed to the fine particles generated during the weathering process and the development of cementitious compounds increasing the bonding and interlocking forces between the particles. The results of this study demonstrated that mechanical strength of recycled materials used as construction materials has little chance to be deteriorated during their service life.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.1
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• pp.61.3-61.3
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• 2019

We report the status of KMTNet (Korea Microlensing Telescope Network) microlensing. From KMTNet event-finder, we are annually detecting over 2500 microlensing events. In 2018, we have carried out a real-time alert for only the Northern bulge fields. It was very helpful to select Spitzer targets. Thanks to the real-time alert, KMT-only events for which OGLE and MOA could not detect have been largely increased. The KMTNet event-finder and alert-finder algorithms are being upgraded every year. From these, we found 18 exoplanets and various interesting events, such as an exomoon-candidate, a free-floating candidate, and brown dwarfs, which are very difficult to be detected by other techniques including radial velocity and transit. In 2019, the KMTNet alert will be available in real-time for all bulge fields. As before, we will continue to collaborate with Spitzer team to measure the microlens parallaxes, which are required for estimating physical parameters of the lens. Thus, the KMTNet alert will be helpful to select Spitzer targets again. Also we plan to do follow-up observations for high-magnification events to study the planet multiplicity function. The KMTNet alert will play an important role to do follow-up observations for high-magnification events. Also, we will search for free-floating planets with short timescale (< 3 days) to study the planet frequency in our Galaxy.

• The Korean Journal of Pain
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• v.35 no.1
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• pp.86-96
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• 2022

Background: To explore the association between low back pain (LBP) and pelvic pain (PP) and rectus abdominis diastasis (RAD) in postpartum women and identify the characteristics and risk factors. Methods: Women diagnosed with RAD and a history of labor and delivery, between 2009 and 2018, were identified from six hospitals within the Partners Healthcare System. Univariate and multivariable binary logistic regression analyses were used to identify the risk factors associated with pain. Results: Age at onset of RAD in the non-cesarean delivery group was earlier than those in cesarean delivery (CD) group (P = 0.017). Women who underwent CD demonstrated 4.5 times greater risk of RAD than those who had no CD exposure. The cumulative composition ratio of LBP at every age stage of the period from 8 years pre-first delivery to 8 years post-first delivery was significantly higher than the other five conditions (RAD, umbilical hernia, PP, depressive disorder [DD], and strain of muscle, fascia, and tendon [SMFT]) (P for trend < 0.001). Women with DD, SMFT, and PP were more likely to have LBP (odds ratio [OR] = 1.91, 95% confidence interval [CI] 1.06 to 3.47, P = 0.032; OR = 4.50, 95% CI 1.64 to 12.36, P = 0.003; OR = 2.14, 95% CI 1.17 to 3.89, P = 0.013; respectively). Conclusions: In postpartum women with RAD, DD, SMFT, and PP were found to be risk factors contributing to the development of LBP. Race and LBP also played roles in the development of PP.