• 한국재료학회지
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• 제26권6호
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• pp.342-346
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• 2016

To observe the bonding structure and electrical characteristics of a GZO oxide semiconductor, GZO was deposited on ITO glasses and annealed at various temperatures. GZO was found to change from crystal to amorphous with increasing of the annealing temperatures; GZO annealed at $200^{\circ}C$ came to have an amorphous structure that depended on the decrement of the oxygen vacancies; increase the mobility due to the induction of diffusion currents occurred because of an increment of the depletion layer. The increasing of the annealing temperature caused a reduction of the carrier concentration and an increase of the bonding energy and the depletion layer; therefore, the large potential barrier increased the diffusion current dna the Hall mobility. However, annealing temperatures over $200^{\circ}C$ promoted crystallinity by the defects without oxygen vacancies, and then degraded the depletion layer, which became an Ohmic contact without a potential barrier. So the current increased because of the absence of a potential barrier.

• Journal of Preventive Medicine and Public Health
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• 제55권2호
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• pp.134-143
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• 2022

Objectives: Many governments have imposed-and are still imposing-mobility restrictions to contain the coronavirus disease 2019 (COVID-19) pandemic. However, there is no consensus on whether policy-induced reductions of human mobility effectively reduce the effective reproduction number (Rt) of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Several studies based on country-restricted data reported conflicting trends in the change of the SARS-CoV-2 Rt following mobility restrictions. The objective of this study was to examine, at the global scale, the existence of regional specificities in the correlations between Rt and human mobility. Methods: We computed the Rt of SARS-CoV-2 using data on worldwide infection cases reported by the Johns Hopkins University, and analyzed the correlation between Rt and mobility indicators from the Google COVID-19 Community Mobility Reports in 125 countries, as well as states/regions within the United States, using the Pearson correlation test, linear modeling, and quadratic modeling. Results: The correlation analysis identified countries where Rt negatively correlated with residential mobility, as expected by policymakers, but also countries where Rt positively correlated with residential mobility and countries with more complex correlation patterns. The correlations between Rt and residential mobility were non-linear in many countries, indicating an optimal level above which increasing residential mobility is counterproductive. Conclusions: Our results indicate that, in order to effectively reduce viral circulation, mobility restriction measures must be tailored by region, considering local cultural determinants and social behaviors. We believe that our results have the potential to guide differential refinement of mobility restriction policies at a country/regional resolution.

• 한국의류산업학회지
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• 제21권2호
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• pp.209-219
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• 2019

This study analyzed and compared wearer mobility for different types of clothing that also included the potential to develop firefighter station uniforms using range of motion (ROM) and electromyography (EMG). This study focused on a comparison of wearer mobility affected by different materials and shapes of the station uniforms worn under firefighter turnout gear. Japanese standard uniform (UNI), stretch-wear (ST), and compression-wear (CP) were used as station uniforms for the experiment. This study analyzed wearer movements and quantified ROM and EMG. In addition, the subjective evaluation of wearer mobility and comfort were assessed for comparisons. Nine healthy male students participated in the experiment. Wearer mobility was analyzed using ROM and EMG data obtained by measuring five motions; in addition, subjective evaluations were also obtained. As compared with the standard station uniform, ROM increased 6.8 % and 7.2 % due to stretch-wear and compression-wear. The benefits of wearing stretch material or compression material to improve muscle performance (such as reduced percent of maximum voluntary contraction) were not proven. Differences between materials and designs influenced subjective wearer comfort. In particular, the wearing of compression materials was shown best in terms of wearer comfort that may also allow greater wearer mobility.

• Preventive Nutrition and Food Science
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• 제3권2호
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• pp.143-151
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• 1998

Protein -surfactant interactions have been investigate by measuring ζ-potential of $\beta$-lactoglobulin-coated emulsion droplets and $\beta$-lactoglobulin in solution in the rpesenceof surfactant, with particular emphasis on the effect of protein heat treatment(7$0^{\circ}C$, 30min). When ionic surfactant (SDS or DATEM) is added to the protein solution, the ζ-potential of the mixture is found to increase with increasing surfactant concentration, indicating surfactant binding to the protein molecules. For heat-denatured protein,it has been observed that the ζ-potential tends to be lower than that of the native protein. The effect of surfactant on emulsions is rather complicated .With SDS, small amounts of surfactant addition induce a sharp increase in zeta potential arising from the specific interaction of surfactant with protein. With further surfacant addition, there is a gradual reductio in the ζ-potential, presumably caused by the displacement of adsorped protein (and protein-surfactant complex) from the emulsion droplet surfac by the excess of SDS molecules. At even higher surfactant concentrations, the measured zeta potential appears to increase slightly, possibly due to the formation of a surfactant measured zeta potential appears to increase slightly, possibly due to the formation of surfactant micellar structure at the oil droplet surface. This behaviour contrastswith the results of the corresponding systems containing the anionic emulsifier DATEM, in which the ζ-potential of the system is found to increase continuously with R, particularly at very low surfactant concentration. Overall, such behaviour is consisten with a combination of complexation and competitive displacement between surfactant and protein occurring at the oil-water interface. In addition, it has also been found that above the CMC, there is a time-dependent increase in the negative ζ-potential of emulsion droplets in solutions of SDS, possibly due to the solublization of oil droplets into surfactant micelles in the aqueous bulk phase.

• 한국콘텐츠학회논문지
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• 제19권10호
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• pp.568-580
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• 2019

MaaS의 영향력이 주목받고 있는 가운데, 공유 모빌리티를 중심으로 모빌리티 서비스 시장이 급격히 성장하고 있다. 시장 선점을 위해서 현재 초기 확산단계에 있는 퍼스널 모빌리티 서비스 이용자의 인식과 경험을 파악하고, 향후 확장될 시장의 잠재 소비자들의 특성을 이해하는 것이 중요하다. 따라서 이 연구는 주관성 연구방법인 Q 방법론을 사용하여 퍼스널 모빌리티 이용자 유형을 분류하고 UX(User experience) 전략을 수립하고자 하였다. 제품 및 서비스 특성과 이용자의 개인적 특성 요소들을 중심으로 41개 구성하고, 잠재 사용자와 실사용자를 포함하는 30명의 P샘플을 대상으로 데이터를 수집하였다. QUANL 소프트웨어를 사용하여 수집한 데이터를 분석하였으며, 그 결과 (1)효율적인 이동 우선형(Mobility Efficiency), (2)경계하는 안전추구형(Safety First), (3)합리적인 여가활용형(Rational Utilization), (4)호기심 많은 재미추구형(Sheer Riding Pleasure)의 네 가지 심성 모형이 도출되었다.

• STI Policy Review
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• 제9권1호
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• pp.99-132
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• 2018

Developing countries face numerous challenges in the process of building science, technology, and research capacity; in particular, the formation and accumulation of skilled S&T workforce. The lack of organized and sustainable higher education options (Master and Doctoral programs), nonexistent or low-quality academic programs, and the absence of research-oriented study options are some of the strong contributors for talented students to emigrate to developed countries. At the same time, the consolidation of a global knowledge economy, the internationalization of higher education, and the competition to attract foreign talent in industrialized countries present challenges for underdeveloped nations to retain their already scarce skilled human resources. In this context, student mobility has been used as a policy mechanism to cope with S&T workforce shortages in S&T laggard nations. It has also enabled opportunities for international cooperation to play a key role. While significant literature has been devoted to studying the gains of developed nations with the arrival and potential migration of the mobilized students, few scholarly inquiries have addressed the benefits and losses experienced by their countries of origin. More importantly, limited research can be found on policy options and policy implications for developing countries to deal with the dilemmas presented by the brain-drain/brain-circulation debate. The goal of this article is to study empirical evidence of an international cooperation initiative for student mobility between the Republic of Korea and Guatemala (implemented during 2009-2015). The paper analyzes this particular international cooperation experience from the perspective of the different actors involved and attempts to draw policy implications and policy options for developing countries to deal with potential risks and gains derived from international mobility for their S&T capacity building.

• Transactions on Electrical and Electronic Materials
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• 제18권6호
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• pp.323-329
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• 2017

This reports the electrical behavior, bonding structure and Schottky contact of gallium-zinc-oxide (GZO) thin film annealed at $100{\sim}400^{\circ}C$. The mobility of GZO with high density of PL spectra and crystal structure was also increased because of the structural matching between GZO and Si substrate of a crystal structure. However, the GZO annealed at $200^{\circ}C$ with an amorphous structure had the highest mobility as a result of a band to band tunneling effect. The mobility of GZO treated at low annealing temperatures under $200^{\circ}C$ increased at the GZO with an amorphous structure, but that at high temperatures over $200^{\circ}C$ also increased when it was the GZO of a crystal structure. The mobility of GZO with a Schottky barrier (SB) was mostly increased because of the effect of surface currents as well as the additional internal potential difference.

• Journal of Communications and Networks
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• 제17권2호
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• pp.100-109
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• 2015

Mobile phone carriers face challenges from three synergistic dimensions: Wireless, social, and mobile. Despite significant advances that have been made about social networks and human mobility, respectively, our knowledge about the interplay between two layers remains largely limited, partly due to the difficulty in obtaining large-scale datasets that could offer at the same time social and mobile information across a substantial population over an extended period of time. In this paper, we take advantage of a massive, longitudinal mobile phone dataset that consists of human mobility and social network information simultaneously, allowing us to explore the impact of human mobility patterns on the underlying social network. We find that human mobility plays an important role in shaping both local and global structural properties of social network. In contrast to the lack of scale in social networks and human movements, we discovered a characteristic distance in physical space between 10 and 20 km that impacts both local clustering and modular structure in social network. We also find a surprising distinction in trajectory overlap that segments social ties into two categories. Our results are of fundamental relevance to quantitative studies of human behavior, and could serve as the basis of anchoring potential theoretical models of human behavior and building and developing new applications using social and mobile technologies.

• 한국항행학회논문지
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• 제28권4호
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• pp.442-449
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• 2024

본 연구는 도심항공교통(UAM; urban air mobility) 혹은 미래항공교통(AAM; advanced air mobility) 인프라의 통신, 항법, 감시 및 정보 시스템 인프라에 대한 사이버 위협 분석을 위한 포괄적인 프레임워크를 제안하고자 한다. 잠재적인 취약점과 위협 벡터를 검토함으로써 UAM 인프라의 보안과 회복력을 강화하려고 한다. 또한, 다양한 유형의 사이버 위협을 식별하고 분류하며, 이들 위협이 CNSi 시스템에 미치는 영향을 평가하고, 이러한 위협으로 악용될 수 있는 시스템 내의 취약점을 평가하는 상세한 사이버 위협 분석을 수행하고자 한다. 해당 연구는 UAM 시스템의 배치 및 운영에 참여하는 이해관계자들에게 귀중한 통찰을 제공하고, 궁극적으로 도시 공중 교통의 안전하고 효율적인 통합에 기여하는 것을 목적으로 한다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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• pp.112-112
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• 2012

Graphene has been considered as one of the potential post Si-materials due to its high mobility. [1] However, since graphene is semi-conductor with zero band gap, it is difficult to achieve high Ion/Ioff ratio, one of the most important requirements for commercial devices. There have been many attempts to open its band gap for high Ion/Ioff ratio, but most of them end up lowering the mobility. [2-5] Thus, we proposed and demonstrated a new device structure for graphene transistor based on one of the unique properties of graphene for high Ion/Ioff: using this approach, we were able to achieve the ratio over $10^5$. [6] Our device has several major advantages over previously proposed graphene based electronic devices. Since our device does not alter the given properties of graphene, such as opening the band gap, it has no fundamental issues on mobility degradations. In addition, our device is fully compatible with current Si technology and we were able to fabricate the devices with 6 inch wafer scale with CVD (Chemical Vapor Deposition) grown graphene. In this presentation, we will discuss about the details of our graphene device including the device structure and the detailed understanding of working mechanism. We will present device characteristics including I-V curves with $10^5$ on/off ratio. We will also present the performance of an inverter based on our devices. Finally, we will discuss the current issues and their potential solutions.