• Proceedings of the Materials Research Society of Korea Conference
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• 2010.05a
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• pp.54.2-54.2
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• 2010

최근까지는 주로 비정질 실리콘이 디스플레이의 채널층으로 상용화 되어왔다. 비정질 실리콘 기반의 박막 트랜지스터는 제작의 경제성 및 균일성을 가지고 있어서 널리 상용화되고 있다. 하지만 비정질 실리콘의 구조적인 문제인 낮은 전자 이동도(< $1\;cm^2/Vs$)로 인하여 디스플레이의 대면적화에 부적합하며, 광학적으로 불투명한 특성을 갖기 때문에 차세대 디스플레이의 응용에 불리한 점이 있다. 이런 문제점의 대안으로 현재 국내외 여러 연구 그룹에서 산화물 기반의 반도체를 박막 트랜지스터의 채널층으로 사용하려는 연구가 진행중이다. 산화물 기반의 반도체는 밴드갭이 넓어서 광학적으로 투명하고, 상온에서 증착이 가능하며, 비정질 실리콘에 비해 월등히 우수한 이동도를 가짐으로 디스플레이의 대면적화에 유리하다. 특히 Zinc Oxide의 경우, band gap이 3.4eV로써, transparent conductors, varistors, surface acoustic waves, gas sensors, piezoelectric transducers 그리고 UV detectors 등의 많은 응용에 쓰이고 있다. 또한, a-Si TFTs에 비해 ZnO-based TFTs의 경우 우수한 소자 성능과 신뢰성을 나타내며, 대면적 제조시 우수한 균일성 및 낮은 생산비용이 장점이다. 그러나 ZnO-baesd TFTs의 경우 일정한 bias 아래에서 threshold voltage가 이동하는 문제점이 displays의 소자로 적용하는데 매우 중요하고 문제점으로 여겨진다. 특히 gate insulator와 channel layer사이의 interface에서의 defect에 의한 charge trapping이 이러한 문제점들을 야기한다고 보고되어진다. 본 연구에서는 Zinc Oxide 기반의 박막 트랜지스터를 DC magnetron sputtering을 이용하여 상온에서 제작을 하였다. 또한, $Si_3N_4$ 기판 위에 electron cyclotron resonance (ECR) $O_2$ plasma 처리와 plasma-enhanced chemical vapor deposition (PECVD)를 통하여 $SiO_2$ 를 10nm 증착을 하여 interface의 개선을 시도하였다. 그리고 TFTs 소자의 출력 특성 및 전이 특성을 평가를 하였고, 소자의 field effect mobility의 값이 향상을 하였다. 또한 Temperature, Bias Temperature stability의 조건에서 안정성을 평가를 하였다. 이러한 interface treatment는 안정성의 향상을 시킴으로써 대면적 디스플레의 적용에 비정질 실리콘을 대체할 유력한 물질이라고 생각된다.

• The Bulletin of The Korean Astronomical Society
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• v.38 no.1
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• pp.32.2-32.2
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• 2013

We examine large-scale environmental effects on the formation and the mass growth of dark matter halos. To facilitate this, we constructed dark matter halo merger trees from a cosmological N-body simulation, which enabled us to trace the merger information and the assembly history of individual halos. In fact, since the massive halos are more likely to be distributed in denser regions than in less dense regions (Mo & White, 1996), the large-scale environment dependence of the properties of halos can be partly originated from the halo mass effect. In order to avoid such contamination, caused by the mass dependence of halo properties, we carefully measured the local overdensity as the indicator of large-scale environment, which was calculated to be as independent of halo mass as possible. Small halos (${\sim}10^{11-12}M_{\odot}$), which usually host isolated single galaxies, show a notable difference on the formation time of galaxies depending on their large-scale environments, which reconfirms halo assembly bias (Gao & White, 2007). Furthermore, we investigate how this environmental effect on small halos is correlated with the mass assembly history of galaxies by using our semi-analytic model. We found that assembly bias in small halos does not have significant effects on the formation time or on the star formation history of galaxies residing in those halos except for the individual stellar mass of galaxies at z = 0. On average, isolated galaxies in high-density regions tend to be slightly more massive than those in low-density regions. Although the observational data from the current galaxy surveys is not yet sufficient for testing this prediction, future galaxy surveys will be able to explore these small galaxies more thoroughly.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.2
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• pp.183-188
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• 2014

In this paper, the propagation effect of power supply uncertainty on the output of class-F power amplifier has been estimated. Also, a 1.9 GHz, 10 watt class-F power amplifier was measured to verify the estimation and to find the optimal biasing point. By approximating the propagation theory of uncertainties, the propagation effect of bias uncertainty was mathmatically calculated. As a result, the DC biases have propagated uncertainties of 15~70 mW. However, at the optimized bias point, the uncertainty in the output power could be dropped less than 15 mW while the output power has dropped by 0.37 dB.

• Journal of Korean Medicine Rehabilitation
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• v.26 no.3
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• pp.85-95
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• 2016

Objectives Military medicine is the study of research which includes health, sanitation, clinic, and quarantine in military personnel. This study is focused on research the acupuncture treatment of military medicine. Methods The study on acupuncture research for Military Medicine was referred from via KoreaMed, OASIS, The Journal of Korean Military Medical Association, KMbase, KAMJE, NDSL, KISS, KISTI, PubMed, MEDLINE, EMBASE, and The Cochran library. As a result, 18 research papers were found and they were analyzed according to the year of publishment, the titles of journals, the nation of research center, the types of study, the purpose of study, the outcome of measurement, the type of acupuncture, and the assessment of acupuncture effect. And then assessed the risk of bias about RCT, NRCT, prospective cohort studies, and before and after studies. Results The number of the published research papers on acupuncture was increased since 2013. The studies were mainly published in the USA and eight out of 18 were RCT. The purpose of study is mostly for musculoskeletal and psychological disease and medical decision for acupuncture. The type of the acupuncture used is not only traditional acupuncture but also the auricular acupuncture. Even though the research results about the effect of acupuncture were excellent and positive, some of studies had a high risk of bias. Conclusions The studies state about acupuncture treatment as mostly positive and effective, however, further clinical studies are required to obtain objective clinical evidence of acupuncture treatment. Furthermore, future trials would be needed to find out effective acupuncture treatments on military duty.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2001.11a
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• pp.67-67
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• 2001

The structure zone model has been used to provide an overview of the relationship between the microstructure of the films deposited by PVD and the most prominent deposition condition.s. B.AMovchan and AV.Demchishin have proposed it firstls such model. They concluded that the general features of the resulting structures could be correlated into three zones depending on $T/T_m$. Here T m is the melting point of the coating material and T is the substrate temperature in kelvines. Zone 1 ($T/Tm_) is dominated by tapered macrograins with domed tops, zone 2 ($O.3) by columnar grains with denser boundaries and zone 3 ($T/T_m>O.5$) by equiaxed grains formed by recrystallization. J.AThomton has extended this model to include the effect of the sputtering gas pressure and found a fourth zone termed zone T(transition zone) consisting of a dense array of poorly defined fibrous grains. R.Messier found that the zone I-T boundary (fourth zone of Thorton) varies in a fashion similar to the film bias potential as a function of gas pressure. However, there has not nearly enough model for explaining the change in morphology with crystal orientation of the films. The structure zone model only provide an information about the morphology of the deposited film. In general, the nucleation and growth mechanism for granular and fine structure of the deposited films are very complex in an PVD technique because the morphology and orientation depend not only on the substrate temperature but also on the energy of deposition of the atoms or ions, the kinetic mechanism between metal atoms and argon or nitrogen gas, and even on the presence of impurities. In order to clarify these relationship, AI and Mg thin films were prepared on SPCC steel substrates by PVD techniques. The influence of gas pressures and bias voltages on their crystal orientation and morphology of the prepared films were investigated by SEM and XRD, respectively. And the effect of crystal orientation and morphology of the prepared films on corrosion resistance was estimated by measuring polarization curves in 3% NaCI solution.

• The Journal of Internal Korean Medicine
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• v.41 no.3
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• pp.350-361
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• 2020

Objective: This study aimed to report the therapeutic effect of acupuncture on chemotherapy-induced peripheral neuropathy (CIPN). Methods: The articles were sourced from databases including PubMed, EMBASE, Cochrane Library, CNKI, CiNii, WHO ICTRP, JSOM, KMBASE, KISS, NDSL, and OASIS as of July 2019. The main search keywords were peripheral neuropathy and acupuncture, and only randomized controlled trials using acupuncture for therapeutic purposes were included. Cochrane's risk of bias was used to assess the risk of bias, and the Review Manager 5.3 program was used for meta-analysis. Results: Six studies with a total 394 participants were included. When combined treatment of acupuncture and usual care was compared with usual care alone, quality of life improved more significantly in the combination treatment group (SMD=-2.71, 95% CI: -5.01 to -0.41, P=0.02, I²=97%). The CIPN pain score was lower among the combination treatment group, but not to a significant degree (SMD=-2.55, 95% CI: -5.14 to 0.04, P<0.05, I²=98%). There were no severe side effects in any studies. Conclusion: Acupuncture combined with usual care may be considered to safely relieve CIPN pain and improve quality of life for cancer patients. However, as there are few randomized controlled trials studying the effect of acupuncture on CIPN, further well-designed research is needed.

• Journal of Adhesion and Interface
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• v.22 no.4
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• pp.144-152
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• 2021

Understanding charge transfer across the interface between organic semiconductor and gate insulator gives insight into the development of high-performance organic memory as well as highly stable organic field-effect transistors (OFETs). In this work, we firstly unveil a novel interfacial charge transfer mechanism, in which hole transfer from organic semiconductor to polymer insulator was nonlinearly boosted by localized states coupling. For this, OFETs based on rubrene single crystal semiconductor and Mylar gate insulator were fabricated via vacuum lamination, which allows stable repetition of lamination and delamination between semiconductor and gate insulator. The surfaces of rubrene single crystal and Mylar film were selectively degraded by photo-induced oxygen diffusion and UV-ozone treatment, respectively. Consequently, we found that the interfacial charge transfer and resultant bias-stress effect were nonlinearly boosted by coupling between localized states in rubrene and Mylar. In particular, the small number of localized states in rubrene single crystal provided fluent pathway for interfacial charge transport.

• Journal of Industrial Convergence
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• v.19 no.5
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• pp.91-102
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• 2021

The purpose of this study was to systematically review about randomized controlled trials the characteristics and effect of cognitive function intervention for patient with dementia. We searched studies published from January 2010 to June 2021 in 5 databases. A total 1,104 studies were found and included 27 studies in final analysis. Methodological quality was assessment with the Cochrane's RoB(risk of bias) tool. Mini-Mental State Examination(MMSE) was the most used as the assessment tool for identifying the cognitive function. Cognitive function intervention were exercise, art, cognitive stimulation, reminiscence, music, multimodal cognitive rehabilitation, virtual reality, horticultural, computerized cognitive training, intentional snoezelen, beauty, cooking, korean traditional familiarity program. Most of the intervention except exercise 2, virtual reality 1, beauty 1 were effective in improving cognitive function. This study provided a clinical evidence for planning and implementing intervention for cognitive function intervention. In the future, various intervention studies suitable for the characteristics of dementia should be conducted by improving the quality of research methods.

• Journal of Korean Medicine Rehabilitation
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• v.31 no.1
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• pp.109-118
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• 2021

Objectives The objective of this study was to appraise the effect of electro-acupuncture (EA) for the treatment of cervical vertigo. Methods We performed a literature search using nine electronic databases up to the end of November 2020. We included randomized controlled trials (RCTs) which appraised the effect of EA in the treatment of cervical vertigo. The risk of bias was evaluated from the Cochrane risk of bias tool. Results Thirteen appropriate RCTs were included and analyzed. The efficacy rate of the EA group was statistically higher compared with the control group treated with western medicine (p<0.00001). EA treatment significantly improved efficacy rate when combined with western medicine than western medicine alone (p<0.0001). Also EA used with combined therapy (traction, traditional chinese medicine, injection) significantly improved efficacy rate compared with combined therapy alone (p=0.02). Meta-analysis of thirteen studies demonstrated positive results for using EA for the treatment of cervical vertigo. Conclusions Based on results, EA treatment could be effective in cervical vertigo. However, it should be noted that the studies included in this research are regionally biased and small in number. Further well-designed research should be required.

• Imaging Science in Dentistry
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• v.51 no.4
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• pp.363-372
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• 2021

Purpose: This systematic review and meta-analysis assessed the diagnostic accuracy of imaging examinations for the detection of peri-implant bone defects and compared the diagnostic accuracy between titanium (Ti) and zirconium dioxide (ZrO₂) implants. Materials and Methods: Six online databases were searched, and studies were selected based on eligibility criteria. The studies included in the systematic review underwent bias and applicability assessment using the Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) tool and a random-effect meta-analysis. Summary receiver operating characteristic (sROC) curves were constructed to compare the effect of methodological differences in relation to the variables of each group. Results: The search strategy yielded 719 articles. Titles and abstracts were read and 61 studies were selected for full-text reading. Among them, 24 studies were included in this systematic review. Most included studies had a low risk of bias (QUADAS-2). Cone-beam computed tomography (CBCT) presented sufficient data for quantitative analysis in ZrO₂ and Ti implants. The meta-analysis revealed high levels of inconsistency in the latter group. Regarding sROC curves, the area under the curve (AUC) was larger for the overall Ti group (AUC=0.79) than for the overall ZrO₂ group (AUC=0.69), but without a statistically significant difference between them. In Ti implants, the AUCs for dehiscence defects(0.73) and fenestration defects(0.87) showed a statistically significant difference. Conclusion: The diagnostic accuracy of CBCT imaging in the assessment of peri-implant bone defects was similar between Ti and ZrO₂ implants, and fenestration was more accurately diagnosed than dehiscence in Ti implants.