• The Korean Journal of Applied Statistics
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• v.13 no.2
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• pp.265-274
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• 2000

Relationship between the daily mortality and total suspended particulate(TSP) for the period of 1996-1997 was examined in Seoul, Korea. Generalized additive model was adapted for the analysis to allow the seasonality and long-term time effect in the air pollution and the nonlinear relationships with weather variables such as air temperature and relative humidity. An increase of 100 Ji9/m') TSP corresponds to 0.8-5.2 percent increase of the daily mortality Unidirectional (prospective and retrospective) case-crossover design results in large bias of the estimates. Bidirectional method gives relatively unbiased estimates but the standard errors are larger Case-crossover design should be used with caution in the situation where the data have seasonal trends like air pollution study.

• Journal of Korean Society of Transportation
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• v.18 no.3
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• pp.55-76
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• 2000

We propose a general solution methodology for identifying the optimal aggregation interval sizes as a function of the traffic dynamics and frequency of observations for four cases : i) link travel time estimation, ii) corridor/route travel time estimation, iii) link travel time forecasting. and iv) corridor/route travel time forecasting. We first develop statistical models which define Mean Square Error (MSE) for four different cases and interpret the models from a traffic flow perspective. The emphasis is on i) the tradeoff between the Precision and bias, 2) the difference between estimation and forecasting, and 3) the implication of the correlation between links on the corridor/route travel time estimation and forecasting, We then demonstrate the Proposed models to the real-world travel time data from Houston, Texas which were collected as Part of the Automatic Vehicle Identification (AVI) system of the Houston Transtar system. The best aggregation interval sizes for the link travel time estimation and forecasting were different and the function of the traffic dynamics. For the best aggregation interval sizes for the corridor/route travel time estimation and forecasting, the covariance between links had an important effect.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.10
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• pp.123-129
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• 1996

LDD structure is widely accepted in fabricating short channel MOSFETs due to reduced short channel effect originated form lower drain edge electric field. However, modeling of the LDD device is troublesome because the analysis methods of LDD region known are either too complicated or inaccurate. To solve the problem, this paper presents a nonlinear resistance model for the LDD region based on teh fact that the electron mobility changes with positive gate bias because accumulation layer of electrons is formed at the surface of the LDD region. To prove the usefulness of the model, single source/drain and LDD nMOSFETs were fabricated with 0.35$\mu$m CMOS technolgoy. For the fabricated devices we have measured I$_{ds}$-V$_{gs}$ characteristics and compare them to the modeling resutls. First of all, we calculated channel and LDD region mobility from I$_{ds}$-V$_{gs}$ characteristics of 1050$\AA$ sidewall, 5$\mu$m channel length LDD NMOSFET. Then we MOSFET and found good agreement with experiments. Next, we use calculated channel and LDD region mobility to model I$_{ds}$-V$_{gs}$ characteristics of LDD mMOSFET with 1400 and 1750$\AA$ sidewall and 5$\mu$m channel length and obtained good agreement with experiment. The single source/drain device characteristic modeling results indicates that the cahnnel mobility obtained form our model in LDD device is accurate. In the meantime, we found that the LDD region mobility is governed by phonon and surface roughness scattering from electric field dependence of the mobility. The proposed model is useful in device and circuit simulation because it can model LDD device successfully even though it is mathematically simple.

• Journal of Acupuncture Research
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• v.37 no.4
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• pp.209-223
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• 2020

The purpose of this study was to evaluate the effectiveness of acupuncture treatment for the symptoms of Alzheimer's disease (AD). There were 11 databases searched for randomized controlled trials using acupuncture treatment for AD. The risk-of-bias assessment tool of the Cochrane Library was used to evaluate the quality of each study. Using the Review Manager (RevMan), a meta-analysis was performed using risk ratio, mean difference, 95% confidence interval, and random effect model. There were 32 studies selected, all of which were conducted in China. There were 16 studies where acupuncture was used as the intervention, and 23 studies used Donepezil as the control group. Acupoint GV20 was most frequently selected during the treatment. The Mini Mental State Examination (MMSE) was the most frequently used outcome variable. A period of 12 weeks was the most common treatment duration. As a result of meta-analysis (n = 25), acupuncture improved the MMSE and activities of daily living scores. Electroacupuncture improved the Alzheimer Disease Assessment Scale-Cognitive Subscale, and scalp acupuncture improved the MMSE score for AD. Acupuncture alleviates the symptoms of AD. However, further research is necessary to provide a better level of evidence.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.2
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• pp.595-600
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• 2015

Background: Accumulating evidence suggests that metformin possesses anticarcinogenic properties, and its use is associated with favorable outcomes in several cancers. However, it remains unclear whether metformin influences prognosis in prostate cancer (PCa) with concurrent type 2 diabetes (T2D). Materials and Methods: We searched PubMed, EMBASE, and the Cochrane Library from database inception to April 16, 2014 without language restrictions to identify studies investigating the effect of metformin treatment on outcomes of PCa with concurrent T2D. We conducted a meta-analysis to quantify the risk of recurrence, progression, cancer-specific mortality, and all-cause mortality. Summary relative risks (RRs) with corresponding 95% confidence intervals (CIs) were calculated. Publication bias was assessed by Begg's rank correlation test. Results: A total of eight studies fulfilled the eligibility criteria. We found that diabetic PCa patients who did not use metformin were at increased risk of cancer recurrence (RR, 1.20; 95%CI, 1.00-1.44), compared with those who used metformin. A similar trend was observed for other outcomes, but their relationships did not reach statistical significance. Funnel plot asymmetry was not observed among studies reporting recurrence (p=0.086). Conclusions: Our results suggest that metformin may improve outcomes in PCa patients with concurrent T2D. Well-designed large studies and collaborative basic research are warranted.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.21 no.4
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• pp.153-157
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• 2011

We have investigated the effect of inductively coupled plasma (ICP) treatment on the early growth stage of heteroepitaxial Ge layers grown on Si(100) substrates using low pressure chemical vapor deposition (LPCVD), The Si(100) substrates were treated by ICP process with various source and bias powers, followed by the Ge deposition, The ICP treatment led to the enhancement in the coalescence of Ge islands, The growth rate of Ge on Si(100) with ICP surface treatment is about 5 times higher than that without ICP surface treatment. A missing dimer caused by the ICP surface treatment can act as a nucleation site for Ge adatoms, which could be responsible for the improvement in growth behavior of Ge on Si(100) substrates.

• Journal of Acupuncture Research
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• v.28 no.5
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• pp.29-38
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• 2011

Objectives : Recent well-designed randomized controlled trials(RCTs) and their meta-analysis have been published on the efficacy of acupuncture in different condition. In most of them, real acupuncture is compared with sham acupuncture including invasive and non-invasive sham methods. But it is not clear how active sham methods are. These results tend to lead the conclusion that acupuncture has no more effective than sham acupuncture. In order to investigate that sham acupuncture is appropriate as a control, we reviewed several acupuncture trials using different sham acupuncture as a control. Methods : We searched Cochrane researches of acupuncture, reviewed and analyzed 25 RCTs in 42 Cochrane reviews. And especially we compared the effect of acupuncture according to the type of sham acupuncture. Results : Invasive sham acupunctures are used in 12 RCTs and non-invasive types are used in the rest. The majority of studies(19 RCTs) fail to show effects beyond a sham acupuncture. Streitberger's sham needle is a validated sham acupuncture of non-invasive type that was used in 8 trials and also no significant group differences are shown except one trial. Conclusions : Acupuncture is a complex intervention. Clinical trials of acupuncture need to be reexamined and redesigned to remove several bias. Especially, sham acupuncture as a control might be investigated for physiological effects as well as validation test including patient-blinding and de qi sensation. Other research need to be investigated and developed for acupuncture trials.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.2
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• pp.93-98
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• 2001

YMnO$_3$ films are excellent gate dielectric materials of ferroelectric random access memories (FRAMs) with MFSFET (metal -ferroelectric-semiconductor field effect transistor) structure because YMnO$_3$ films can be deposited directly on Si substrate and have a relatively low permittivity. Although the patterning of YMnO$_3$ thin films is the requisite for the fabrication of FRAMs, the etch mechanism of YMnO$_3$ thin films has not been reported. In this study, YMnO$_3$thin films were etched with Cl$_2$/Ar gas chemistries in inductively coupled plasma (ICP). The maximum etch rate of YMnO$_3$ film is 285$\AA$/min under Cl$_2$/(Cl$_2$+Ar) of 1.0, RF power of 600 W, dc-bias voltage of -200V, chamber pressure of 15 mTorr and substrate temperature of $25^{\circ}C$. The selectivities of YMnO$_3$ over CeO$_2$ and $Y_2$O$_3$ are 2.85, 1.72, respectively. The selectivities of YMnO$_3$ over PR and Pt are quite low. Chemical reaction in surface of the etched YMnO$_3$ thin films was investigated with X-ray photoelectron spectroscopy (XPS) surface of the selected YMnO$_3$ thin films was investigated with X-ray photoelectron spectroscopy(XPS) and secondary ion mass spectrometry (SIMS). The etch profile was also investigated by scaning electron microscopy(SEM)

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.10
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• pp.881-884
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• 2008

In this study, polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE) in the composition from 51/49, was deposited on platinum for a metal-ferroelectric-metal structure. From XRD patterns, the 70 nm- and 140 nm-thick PVDF-TrFE films showed the intensity peak of near $20^{\circ}$ connected to a ferroelectric phase. Moreover, the thicker film indicated the higher intensity than thinner one. The difference of the remanent polarization (2Pr) at 0 V is decreased gradually from 10.19 to $5.7{\mu}C/cm^2$ as the thickness decrease from 140 to 70 nm. However, when the thickness decreased to 50 nm, the 2Pr rapidly drop to $1.6{\mu}C/cm^2$ so the minimum critical thickness might be at least 70 nm for device. Both different thickness films, 70 and 140 nm, indicated that the characteristic of current density-voltage was measured for $10^{-6}{\sim}10^{-7}A/cm^2$ below 15 V and the thicker film maintained relatively lower current density than thinner one. From these results, we can expect that the electrical properties for the devices particularly ferroelectric thin film transistor using PVDF-TrFE copolymer were able to be on the trade-off relationship between the remanent polarization with the bias voltage and the leakage current.

• Journal of East-West Nursing Research
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• v.26 no.1
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• pp.1-16
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• 2020

Purpose: The purpose of this study was to evaluate the effectiveness of non-pharmacologic interventions for chronic nonspecific low back pain (CLBP) in adults aged 18-64 years. Methods: We searched for potentially relevant randomized controlled trials and non-randomized controlled trials through five Korean electronic databases (i.e., Korean Studies Information Service System, Research Information Sharing Service, Korean Medical Database, KoreaMed, and National Assembly Library) published from January 2010 to May 2019. Two investigators independently selected the studies based on the criteria and assessed risk of bias in the included studies. We estimated the effect size of interventions using Comprehensive Meta Analysis 3.3. Results: Of 10,151 studies, 26 studies met the inclusion criteria and 15 studies were included in the meta-analysis. Exercise reduced low back pain (Hedges's g=-1.53, 95% CI: -2.22 to -0.85) and pain-related disabilities (Hedges's g=-0.92, 95% CI: -1.40 to -0.45). We found that taping was effective in decreasing low back pain (Hedges's g=-1.12, 95% CI: -1.51 to -0.73) and pain-related disabilities (Hedges's g=-0.50, 95% CI: -0.93 to -0.07). Manual therapy yielded a marginally significant reduction in low back pain (Hedges's g=-2.32, 95% CI: -4.64 to 0.00), the therapy was not effective in decreasing pain-related disabilities. Conclusion: Although there was little evidence for the effectiveness of manual therapy in adults with CLBP, exercise and taping were effective to relieve pain and pain-related disabilities. Based on these findings, we suggest the development of non-pharmacologic interventions or a nursing intervention protocol for the CLBP management. Also, nurses should consider implementation of effective non-pharmacologic interventions for CLBP.