• International Journal of Computer Science & Network Security
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• 제24권9호
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• pp.21-29
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• 2024

Precoding of the orthogonal frequency division multiplexing (OFDM) with Walsh Hadamard transform (WHT) is known in the literature. Instead of performing WHT precoding and inverse discrete Fourier transform separately, a product of two matrix can yield a new matrix that can be applied with lower complexity. This resultant transform, T-transform, results in T-OFDM. This paper extends the limited existing work on T-OFDM significantly by presenting detailed account of its computational complexity, a lower complexity receiver design, an expression for PAPR and its cumulative distribution function (cdf), sensitivity of T-OFDM to timing synchronization errors, and novel analytical expressions signal to noise ratio (SNR) for multiple equalization techniques. Simulation results are presented to show significant improvements in PAPR performance, as well improvement in bit error rate (BER) in Rayleigh fading channel. This paper is Part II of a three-paper series on alternative transforms and many of the concepts and result refer to and stem from results in generalized multicarrier communication (GMC) system presented in Part I of this series.

• 한국시스템다이내믹스연구
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• 제10권3호
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• pp.105-124
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• 2009

The situation of the global food markets has been being rapidly restructured and entering on a new phase by new dynamic and driving forces. The factors such as economic growth and income increase, high energy price, globalization, urbanization, and global climate change are transforming patterns of food consumption, production, and markets. The prices and markets of world food and energy are getting increasingly linked each other. Food and fuel are the global dilemma issues associated with the risk of diverting farmland or of consuming cereals for biofuel production in detriment of the cereals supply to the global food markets. An estimated 100 million tons of grain per year are being redirected from food to fuel. Therefore, the objectives of this study are as follows: Firstly, the study examines situations of the world food and energy resources, analyzes the trends of prices of the crude oil and biofuel, and formulates the food-energy links mechanism. Secondly, the study builds a simulation model, based on system dynamics approach, for not only analyzing the global cereals market and energy market but also forecasting the global production, consumption, and stock of those markets by 2030 in the future. The model of this study consists of four sectors, i.e., world population dynamics sector, global food market dynamics sector, global energy market dynamics sector, scenario sector of world economic growth and oil price.

• 상하수도학회지
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• 제26권6호
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• pp.883-888
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• 2012

Anode electrode is one of the most important factors in microbial fuel cell (MFC). This study was conducted to investigate the effects of mediator as methylene blue (MB) and electrode surface area on the power density of MFC with sponge and carbon nano tube (CNT) electrode (SC). The SC electrode with MB (MC) showed the maximum power density increased from 74.0 $mW/m^2$ to 143.1 $mW/m^2$. The grid shaped sponge and CNT (GSC) electrode showed the maximum power density of 209.2 $mW/m^2$ due to the increase of surface area from 88.0 to 152.0 $cm^2$. The GSC electrode with MB (GMC) revealed the maximum power density of 384.9 $mW/m^2$ which was 5.2 times higher than that obtained from the MFC with SC. Therefore MB and increase of surface area led to enhance the performance of microbial fuel cell such as power density.

• Asian Pacific Journal of Cancer Prevention
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• 제15권3호
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• pp.1085-1091
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• 2014

Matrix metalloproteinases (MMPs) are a family of zinc dependent extracellular matrix (ECM) remodelling endopeptidases having the ability to degrade almost all components of extracellular matrix and implicated in various physiological as well as pathological processes. Carcinogenesis is a multistage process in which alteration of the microenvironment is required for conversion of normal tissue to a tumour. Extracellular matrix remodelling proteinases such as MMPs are principal mediators of alterations observed in the microenvironment during carcinogenesis and according to recent concepts not only have roles in invasion or late stages of cancer but also in regulating initial steps of carcinogenesis in a favourable or unfavourable manner. Establishment of relationships between MMP overproduction and cancer progression has stimulated the development of inhibitors that block proteolytic activity of these enzymes. In this review we discuss the MMP general structure, classification, regulation roles in relation to hallmarks of cancer and as targets for therapeutic intervention.

• 한국음향학회지
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• 제34권3호
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• pp.240-246
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• 2015

본 논문은 시간 연속성을 갖는 비음수 행렬 분해(Nonnegative Matrix Factorization, NMF)를 이용하여 잡음에 열화된 음성 신호의 음질을 개선하는 문제를 다룬다. 음성과 잡음 신호는 포아송 분포로 모델되며, NMF의 기본 벡터와 이득 벡터는 감마 분포로 모델된다. 이득 벡터의 시간 연속성은 음질 개선에 중요한 영향을 미치는 것으로 알려져 있다. 본 논문에서 시간의 연속성은 이득 벡터를 감마-마르코프 연쇄(Gamma-Markov chain, GMC) 사전 분포로 모델함으로써 이루어진다. 실험 결과는 제안된 알고리즘이 잡음 신호의 시간 연속성을 효과적으로 모델하는 것을 보여준다.

• 천문학회보
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• 제42권1호
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• pp.32.3-33
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• 2017

Utilizing both the existing observational data for Orion A and the TRAO $^{13}CO$, $^{12}CO$ data for $1^{\circ}{\times}1^{\circ}$ region centered on M42 collected in 2012, we found a clear piece of evidence for a collision of a cloud with the OMC-1. This cloud has a shape like a long cylinder of ${\sim}0.1pc{\times}2pc$ in size, and has a well developed train of clumps of about a few solar masses, and is situated in the dark dust complex between M42 and M43. The cloud's motion is analysed to be moving at about $2.6km\;s^{-1}$, and is calculated to transverse the Orion Nebula ~2 pc above from the nebula center, toward the direction of about $60^{\circ}$ to the line of sight. This cloud had undergone a tidal splitting about a million years ago and had formed a very thin and long cylindrical core well before being engaged in the collision. General implications of this phenomenon are discussed in relation to star formation mechanisms in the GMC.

• 천문학회지
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• 제27권2호
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• pp.147-158
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• 1994

We have obtained high angular resolution maps toward a molecular cloud associated with an HII region S287 and studied mainly kinematics of the cloud. The mapped region is 1.5 square degrees of the cloud in the transitions of $^{12}CO\;and\;^{13}CO\;J=1-0$. We have obtained a large range of mass, $1.3\times10^4M_\bigodot$, to $7.2{\times}10^4M_{\bigodot}$ using three different techniques. The S287 molecular cloud shows a very disturbed feature: velocity field of the cloud is very complicated, and shows several arcs. It is likely that the southern part of cloud is being disrupted by the residing HII region S287 as well as external perturbing sources. In addition to an HII region, five bipolar outflows are also disturbing the molecular gas significantly. The large virial mass and the very disturbed morphology may reflect the fact that the cloud is not gravitationally bound system, as in the case of nearby giant molecular cloud (GMC) G216-2.5. The several arc structure and the filamentary features are possibly driven by external strong stellar winds, and these external perturbing sources may be driving the second generation of star-forming activities on the edges of the S287 molecular cloud.

• 천문학회보
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• 제41권1호
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• pp.44.3-45
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• 2016

In this study, we identify 307 the geosynchronous magnetopause crossing (GMC) using geosynchronous satellite observation data from 1996 to 2010 as well as make an observational test of magnetopause location models using the identified events. For this, we consider three models: Petrinec and Russell (1996), Shue et al. (1998), and Lin et al. (2010). To evaluate the models, we estimate a Probability of Detection (PoD) and a Critical Success Index (CSI) as a function of year. To examine the effect of solar cycle phase, we consider three different time periods: (1) ascending phase (1996-1999), (2) maximum phase (2000-2002), and (3) descending phase (2003-2008). Major results from this study are as follows. First, the PoD values of all models range from 0.6 to 1.0 for the most of years. Second, the PoD values of Lin et al. (2010) are noticeably higher than those of the other models. Third, the CSI values of all models range from 0.3 to 0.6 and those of Shue et al. (1998) are slightly higher than those of the other models. Fourth, the predicted magnetopause radius based on Lin et al.(2010) well match the observed one within one earth radius, while that on Shue et al. (1998) overestimate the observed one by about 2 earth radii. Fifth, the PoD and CSI values of all the models are better for the solar maximum phase than those for the other phases, implying that the models are more optimized for the phase.

• 셀메드
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• 제11권3호
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• pp.12.1-12.5
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• 2021

Gestational diabetes mellitus (GDM) has become one of the major public health problems for both mothers and children globally. Internationally, the frequency of excess weight and obesity has risen dramatically in women of childbearing age. There seems to be a greater risk of having GDM in overweight or obese women, resulting in problems during pregnancy, birth and neonatal development. Hospital management is a problem for obese pregnant females with GDM and places extra burdens on the healthcare sector. GDM can result in possible risks to the wellbeing of the mother, fetus, and infant, as well as clinically significant negative effects on the mental health of the mother. For females and their developing babies, diabetes may cause problems during pregnancy. Unsatisfactory diabetes control enhances the risk of complications and other birth related issues during pregnancy. It may also cause a woman to suffer severe complications. Numerous maternal and fetal effects are associated with GDM and multiple detection and management methods are also pursued globally in order to reduce the burden of health. An overview of gestational diabetes treatment is given in this review.

• 한국산업보건학회지
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• 제8권1호
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• pp.24-35
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• 1998

Cumulative trauma disorders(CTDs) have been a growing problems for US and European industries with higher incidence rate every year. The increase and their associated costs has led companies to form committes and implement programs to address this problem. In our country, we have just started to recognize and to work on the problems in industry. This study conducted an ergonomic analysis for typical jobs of ship building industry which was not usually surveyed for CTD problem. A baseline CTD checklist which was supposed to do a risk assessment was developed and applied in this study. Initially, we considered five major parts in the checklist which consisted of personal, frequency, posture, force, and miscellaneous information. Most jobs in ship building industry were much different from typical assembly work and VDT work that have been major part of the previous CTD studies. Specifically, job characteristics in terms of frequency and posture were quite different. There were relatively long cycle time, awkward postures for whole body (not just for upper extremities). Also, CTD risk scores based on checklist were a lot higher than the scores for VDT jobs which was a case of preceding application of the checklist. Specifically, grinding jobs turned out to be the most risky one in terms of CTDs. In conclusion, usual CTD prevention guidelines are not likely to he effective in this type of industry. An individual job based interventions are strongly suggested to have a good control of CTD problems in ship building industry.