• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.9C
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• pp.829-835
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• 2002

DSL(digital subscriber line) transceiver designers have concerned the impulsive noise as well as NEXT(near-end crosstalk) and FEXT(far-end crosstalk) immunities Down as the strongest sources that limit the DSL channel capacity. In these noise environment the analysis on the performance of DSL should be needed. Therefore, in this paper we have estimated and simulated the SNR(signal-to-noise ratio) margin of DMT(discrete multi-tone) signal in Gauss, NEXT, FEXT and impulse noise environment by modeling an Middleton's Class A impulse signal with the test Cook pulses. As a result, it is known that the transmission rate of uplink is limited by noise characteristics rather than by loop length, but that of downlink limited complexly by both of noise characteristics and loop length. In conclusion, these results will be utilized as the threshold of ADSL performance in the complex noise environment including impulse noise.

• The Bulletin of The Korean Astronomical Society
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• v.40 no.1
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• pp.67.4-68
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• 2015

We present a multi-wavelength observational study of a low-mass star-forming region, L1251-C, with observational results at wavelengths from the near-infrared to the millimeter. Spitzer Space Telescope observations confirmed that IRAS 22343+7501 is a small group of protostellar objects. The extended emission to east-west direction with its intensity peak at the center of L1251A has been detected at 350 and 850 mm with the CSO and JCMT telescopes, tracing dense envelope materials around L1251A. The single-dish data from the KVN and TRAO telescopes show inconsistencies between the intensity peaks of several molecular line emission and that of the continuum emission, suggesting complex distributions of molecular abundances around L1251A. The SMA interferometer data, however, show intensity peaks of CO 2-1 and $^{13}CO$ 2-1 located at the position of IRS 1, which is both the brightest source in IRAC image and the weakest source in the 1.3 mm dust continuum map. IRS 1 is the strongest candidate for being the driving source of a newly detected the compact CO 2-1 outflow. Over the whole region ($14^{\prime}{\times}14^{\prime}$) of L125l-C, 3 Class I and 16 Class II sources have been detected, including three YSOs in L1251A. A comparison with the average projected distance among 19 YSOs in L1251-C and that among 3 YSOs in L1251A suggests L1251-C is an example of low-mass cluster formation, where protostellar objects are forming in a small group.

• Journal of Environmental Science International
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• v.23 no.2
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• pp.249-259
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• 2014

This paper investigates the characteristics of high $PM_{2.5}$ episodes occurred at Anmyeondo area in spring time, 2009. The monthly mean $PM_{2.5}$ concentration during April was the highest in the year and especially, high levels of $PM_{2.5}$ exceeding standard regulation level were sustained consecutively during 5 to 13 April. To analyze more detailed $PM_{2.5}$ characteristics, numerical simulations were carried out using CMAQ(Community Multi-scale Air Quality) with IPR(Integrated Process Rate) and DDM-3D(Decoupled Direct Method). $PM_{2.5}$ level was lower in daytime than that in nighttime due to vigorous vertical mixing during daytime. The chemical composition was showed that ratio of primary ion components such as sulfate($SO_4{^{2-}}$), nitrate($NO_3{^-}$) and ammonium($NH_4{^+}$) were nearly half of total amount of $PM_{2.5}$. Aerosol and transport process dominantly contributed to $PM_{2.5}$ concentration in Anmyeondo area and contribution rate of local emissions was nearly zero since Anmyeondo area has rare anthropogenic PM emission sources. DDM-3D analysis result showed that $PM_{2.5}$ in Anmyeondo area was influenced by emissions from Shanghai and Shandong region of China.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.28 no.6
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• pp.645-657
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• 2015

In this study floor impact noise and structure acceleration response of bare concrete slabs were predicted by using Finite Element Analysis(FEA). Prediction results were compared with experimental results to prove the accuracy of numerical model. Acoustic absorption were addressed by using panel impedance coefficients with frequency characteristics and structural modal damping of numerical model were applied by modal testing results and analysis of prediction and test results. By using frequency response function, the floor acceleration and acoustic pressure responses for various impact sources were calculated at the same time. In the FEA, the natural frequencies and the shapes of vibration and acoustic modes can be estimated through the eigen-value analysis, and it can be visually seen the vibration and sound pressure field and the contribution of major modes.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.9
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• pp.4321-4326
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• 2012

The current study aimed at exploring the knowledge and beliefs of men aged forty years and over towards prostate cancer screening and early detection in three Arab countries. The field work was conducted in three countries; Saudi Arabia, Egypt and Jordan, during the period February through December 2011. Our target population were men aged 40 years and over. It was a population-based cross sectional study comprising 400 subjects at each site. In addition to socio-demographic data, history of the present and past medical illness, practice history of prostatic cancer examination, family history of cancer prostate; participants were inquired about their knowledge and attitude towards prostate cancer and screening behavior using two different likert scales. The percentage of participants who practiced regular prostate check up ranged from 8-30%. They had poor knowledge and fair attitude towards prostate cancer screening behavior, where the mean total knowledge score was $10.25{\pm}2.5$, $10.76{\pm}3.39$ and $11.24{\pm}3.39$ whereas the mean total attitude score was $18.3{\pm}4.08$, $20.68{\pm}6.4$ and $17.96{\pm}5.3$ for Saudi Arabia, Egypt and Jordan respectively. The respondents identified the physicians as the main sources of this information (62.4%), though they were not the main motives for regular checkup. Knowledge was the only significant predictor for participants' attitude in the multiple regression models. Participants' attitudes depends mainly on level of knowledge and quantity of information provided to the patients and their families. Such attitudes should rely on a solid background of proper information and motivation from physicians to enhance and empower behaviors towards prostate cancer screening practices.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.324-326
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• 2016

In this study, we have investigated indium tin zinc oxide (ITZO) as an active channel for non-volatile memory (NVM) devices. The electrical and memory characteristics of NVM devices using multi-stack gate insulator SiO2/SiOx/SiOxNy (OOxOy) with Si-rich SiOx for charge storage layer were also reported. The transmittance of ITZO films reached over 85%. Besides, ITZO-based NVM devices showed good electrical properties such as high field effect mobility of 25.8 cm2/V.s, low threshold voltage of 0.75 V, low subthreshold slope of 0.23 V/dec and high on-off current ratio of $1.25{\times}107$. The transmission Fourier Transform Infrared spectroscopy of SiOx charge storage layer with the richest silicon content showed an assignment at peaks around 2000-2300 cm-1. It indicates that many silicon phases and defect sources exist in the matrix of the SiOx films. In addition, the characteristics of NVM device showed a retention exceeding 97% of threshold voltage shift after 104 s and greater than 94% after 10 years with low operating voltage of +11 V at only 1 ms programming duration time. Therefore, the NVM fabricated by high transparent ITZO active layer and OOxOy memory stack has been applied for the flexible memory system.

• Journal of Environmental Science International
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• v.24 no.10
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• pp.1273-1283
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• 2015

In present study, the temporal characteristics of nine selected volatile organic compounds (VOCs), including four alcohol, 2 aldehyde, and 3 ketone compounds, in high-stories urban apartments over a 2-y period were investigated. The indoor VOC concentrations had generally a decreasing trend over the 2-y follow-up period. For examples, the 2E1H indoor concentration decreased from $10.8{\mu}g/m^3$ for the first two months to $5.1{\mu}g/m^3$ for the last two months. In addition, the DCA and ACT indoor concentrations decreased from 5.0 and $14{\mu}g/m^3$ for the first two months to 2.2 and $6.4{\mu}g/m^3$, respectively, for the last two months. The indoor-to outdoor concentration ratios over the 2-y period were much greater than 1, indicating that indoor VOC concentrations were higher than the outdoor VOC concentrations. Similar to those of the individual VOCs, the indoor-to-outdoor concentration ratios of all three VOC groups were higher than 1 over the 2-y follow-up period, suggesting higher indoor concentrations of the three VOC groups than outdoor concentrations. In consistence with the results of VOC indoor concentrations, the VOC emission rates decreased gradually as time passed, due to the decreased VOC emission strengths of indoor sources. Finally, there was an initial sharp decrease in the indoor VOC concentrations followed by a slower decrease, indicating a multi-exponential decay model for the target VOCs, which was demonstrated by comparison of the residuals and the adjusted coefficient of determination associated with the one and two-exponential fits of each data set.

• Journal of Environmental Health Sciences
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• v.41 no.6
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• pp.425-437
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• 2015

Objectives: Risk assessment is a tool for predicting and reducing uncertainty related to the effects of future activities. Probability approaches are the main elements in risk assessment, but confusion about the interpretation and use of assessment factors often undermines the message of the analyses. The aim of this study is to provide a guideline for systematic reduction plans regarding uncertainty in risk assessment. Methods: Articles and reports were collected online using the key words "uncertainty analysis" on risk assessment. Uncertainty analysis was conducted based on reports focusing on procedures for analysis methods by the World Health Organization (WHO) and U.S. Environmental Protection Agency (USEPA). In addition, case studies were performed in order to verify suggested methods qualitatively and quantitatively with exposure data, including measured data on toluene and styrene in residential spaces and multi-use facilities. Results: Based on an analysis of the data on uncertainty, three major factors including scenario, model, and parameters were identified as the main sources of uncertainty, and tiered approaches were determined. In the case study, the risk of toluene and styrene was evaluated and the most influential factors were also determined. Five reduction plans were presented: providing standard guidelines, using reliable exposure factors, possessing quality controls for analysis and scientific expertise, and introducing a peer review system. Conclusion: In this study, we established a method for reducing uncertainty by taking into account the major factors. Also, we showed a method for uncertainty analysis with tiered approaches. However, uncertainties are difficult to define because they are generated by many factors. Therefore, further studies are needed for the development of technical guidelines based on the representative scenario, model, and parameters developed in this study.

• 한국디지털정책학회:학술대회논문집
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• 2004.11a
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• pp.375-387
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• 2004

The paper presents an Integrated E-Community System (IECS) for management, decision and service, designed for the e-government project of Haishu District of Ningbo, Zhejiang, China. The project need is to promote the integration of management information and service information of communities, providing a unified platform on which different departments of the district government can share and exchange community information, government officers can analyze information and make decisions, and the outside users can access and request services. To meet the project need, the IECS consists of five parts: 1) The Central DataBase (CDB) that stores all information related with management, decision and service of communities: 2) Information Extracting Subsystem (IES) that provides functions of extracting data from data sources, transforming and loading them into the CDB for system administrators; 3) Information Management Subsystem (IMS) that provides functions of querying and sharing of information for government users, and functions of information maintenance, rights and log management for system administrators: 4) Intelligent Analysis Subsystem (IAS) that provides functions of extracting analysis related data from the CDB and loading them into the DW, and functions of multi-dimensional analysis and decision-making based on the DW and OLAP for government users; 5) Information Service Website (ISW) that provides functions of promulgating and collecting of information for government users and system administrators, and functions of browsing, querying and requesting of service information for outside users. The IECS supports management, decision and service of a government based on a unified data platform--the CDB, and ensures data security by providing different workplaces and rights for different users. In the real application, the system works well.

• Journal of Korean Institute of Industrial Engineers
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• v.3 no.2
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• pp.63-72
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• 1977

The trend of computerization is significant in Korea even at its beginning stage, especially for governmental administration. However, full-fledged success of computerization in an organization is reported to be rare while the cost of computerization has been high and increasing. This paper is concerned with two features for the successful implementation of a computerized system in an organization selection criteria for the computerization among the possible candidate projects and project selection models. Due to the dearth of literature regarding successful implementation of computerization, other sources of literature with respect to R & D management, method engineering, etc. were reviewed to develop a set of factors influencing successful computerization. Thus, project selection criteria for computerization of governmental administration are developed and organized as follows: cost of computerization project including both system development and operating cost, quanitative and qualitative benefits of computerization project, probability of technical and implementation success of computerization and other organizational and political factors to be considered. These criteria are broken down into detailed sets of subcriteria to be measured. To select a project after thorough consideration of the selection criteria, a project selection model which takes into account all criteria together has to be developed. In the study three project selection models are suggested and developed. They are the checklist model, multi-stage cut-off model, and composite criteria model. A detailed procedure for each of the three models is illustrated. Although the project selection criteria and models are developed here primarily for the computerization of governmental administration, they are easily applicable to other settings of computerization. Finally, some caveats for the use of selection criteria and models are discussed.