• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.1
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• pp.53-60
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• 2021

High voltage CV cables have been widely installed underground due to their convenience and urban aesthetics. However, cable accidents have occurred frequently owing to poor construction and natural degradations. This paper proposes the method to measure the multi parameter measurement for optimum diagnostics of high voltage cable connection parts and verifies its technical usefulness. This measurement is intended to diagnose degradations of cable connection parts by using simultaneous vibration and thermography as well as partial discharge(PD). The experiment in a shielded laboratory was carried out to verify the usefulness of the multi parameter measurement. The experiment defined the degradation of the cable connection part as 12 types, and produced each degradation sample. As a result of experiment, it was possible to check the correlation of vibration signals with regard to progress in some defects. In the case of thermography, the coherence with regard to the progress of some defects was found. We figure that the proposed method would be useful also in the noise environment.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.2
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• pp.134-138
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• 2021

Various types of precision plastic thin films are used widely in high-performance displays, such as smartphones. For plastic thin-films manufactured by the Roll-to-Roll process, the film thickness must be measured and managed while moving. In the Roll-to-Roll process, wrinkles are generated when tension is applied to the film, which causes an inclination on the optical axis of the thickness gauge, resulting in a loss of accuracy. Therefore, this study attempted to develop an optical interference tomography measurement system. In this study, the tilt angle of the film was measured to correct the measurement value error in the thickness gauge caused by the tilt of the film. The system was constructed so that the laser was irradiated on the tilted film, and the laser reflected from the film was formed on the PSD. The relationship between the tilt angle of the film and the output value of the PSD was obtained experimentally. Using this, a device to measure the tilt angle of the film was constructed, and angle measurements were taken at a speed of 250,000Hz.

• The Journal of the Korea Contents Association
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• v.20 no.12
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• pp.206-220
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• 2020

In the glocal era, the competitiveness of local authorities leads to national competitiveness. Even though they have competitively adopted slogans to stay competitive, the process has not been systematic. The goal of this study is to provide basic data needed to develop and utilize urban brand slogans effectively. In terms of a research scope, 48 slogans currently in use by 24 local authorities of Gyeongsangbuk-do as of April 2020 were chosen. Concerning the lingual representation of such slogans, diverse languages such as Korean, English and Sino-Korean have been used. In terms of meaning of meaning and material type, there was a lack of coherence among the slogans. In addition, they were poor in representing identity, and abstract image upgrade types were commonly found. It is anticipated that the study results would make a contribution to the development of urban brand slogans and value generation.

• Journal of Periodontal and Implant Science
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• v.52 no.1
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• pp.65-76
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• 2022

Purpose: The present study measured changes in arteriolar and venular capillary flow and structure in the gingival tissues during the development of plaque-induced gingival inflammation by combining dynamic optical coherence tomography (OCT), laser perfusion, and capillaroscopic video imaging. Methods: Gingival inflammation was induced in 21 healthy volunteers over a 3-week period. Gingival blood flow and capillary morphology were measured by dynamic OCT, laser perfusion imaging, and capillaroscopy, including a baseline assessment of capillary glycocalyx thickness. Venular capillary flow was estimated by analysis of the perfusion images and mean blood velocity/acceleration in the capillaroscopic images. Readings were recorded at baseline and weekly over the 3 weeks of plaque accumulation and 2 weeks after brushing was resumed. Results: Perfusion imaging demonstrated a significant reduction of gingival blood flow after 1 and 2 weeks of plaque accumulation (P<0.05), but by 3 weeks of plaque accumulation there was a more mixed picture, with reduced flow in some participants and increased flow in others. Participants with reduced flux at 3 weeks also demonstrated venular-type flow as determined by perfusion images and evidence of the development of venular capillaries as assessed by the velocity/acceleration ratio in capillaroscopic images. After brushing resumed, these venular capillaries were broken down and replaced by arteriolar capillaries. Conclusions: After 3 weeks of plaque accumulation, there was wide variation in microvascular reactions between the participants. Reduced capillary flow was associated with the development of venular capillaries in some individuals. This is noteworthy, as an early increase in venous capillaries is a key vascular feature of cardiovascular disease, psoriasis, Sjögren syndrome, and rheumatoid arthritis-diseases with a significant association with the development of severe gingival inflammation, which leads to periodontitis. Future investigations of microvascular changes in gingival inflammation might benefit from accurate capillary flow velocity measurements to assess the development of venular capillaries.

• Archives of Plastic Surgery
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• v.49 no.3
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• pp.304-309
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• 2022

Background Laminin 5, which is found in the basement membrane of dermal-epidermal junction (DEJ), is a major adhesive component and associated with proliferating and migrating keratinocytes. In this study, we hypothesized that the topical application of the skin care products containing the novel peptides might restore the DEJ structure by deriving deposition of laminin 5 and promoting the keratinocyte migration. Here, we evaluated the restoration of DEJ by measuring the skin thickness. Methods Single-center retrospective analysis was performed on a total of 13 patients who underwent skin care using Baume L.C.E. (France, Laboratories d' Anjou) between January and March 2021. All patients applied the skin care agent for 2 weeks only on their left hand dorsum. Before the initiation of the application and after 2 weeks, both their hands were evaluated on photography and ultrasound. And the patients were asked to rate their satisfaction with the questionnaire after 2 weeks. Results There was no obvious improvement in photographic assessment and questionnaire. The post-pre difference of skin thickness in ultrasound images was, in left hand, 0.1 ± 0.37 in distal point and 0.1 ± 0.35 in proximal point; and, in right hand, 0 ± 0.17 in distal point and 0 ± 0.15 in proximal point, respectively. The pre-post difference was statistically significant in proximal point (p = 0.035). Conclusion Topical application of novel peptide derivative comprising laminin 5 demonstrated cutaneous changes including skin thickness, as assessed by ultrasound. Further studies using other modalities including dermal density measurement, three-dimensional photography, optical coherence tomography, or skin biopsy would be helpful to determine the skin-improving effects.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.440-440
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• 2022

1970년대부터 집중 건설 된 우리나라의 다목적댐, 홍수조절댐, 용수전용댐 등의 대형 국가 수자원시설물들의 '고령화'가 급속히 진행되어 수리구조물에 대한 안정성을 주기적으로 파악할 수 있는 정밀안전모니터링 체계 구축이 시급한 시점이다. 주기적인 정밀안전모니터링 방법들 중에는 위성 등을 활용한 원격관측 기술들이 최근 시도되고 있다. 위성 영상레이더(SAR; Synthetic Aperture Radar)는 마이크로파 대역의 전자기파를 송·수신하는 능동센서로 날씨 및 주·야간에 영향을 받지 않고 지표면 관측이 가능한 장점이 있다. 특히, 고정산란체 영상레이더 간섭(PSInSAR; Permanent Scatterer Interferometry SAR)기법은 영상레이더 영상에서 긴밀도(coherence)가 상대적으로 높은 수자원시설물과 같은 고정산란체의 위상(phase) 정보를 이용하여 mm급의 측정민감도로 시계열 변위 분석이 가능하다. 또한, 여러 장의 InSAR 영상을 생성하였기 때문에 DEM 오차, 위성궤도 오차, 대기 성분에 의한 지연 오차 등을 보다 정밀하게 제거할 수 있는 장점이 있다 본 연구에서는 국내 중대형 수자원시설물의 정밀안전모니터링을 위하여 고정산란체 영상레이더 간섭 기법을 영암금호방조제, 영주댐, 소양강댐 등에 적용하여 시계열 변위 분석을 수행하였다. 2014년 11월부터 2022년 3월(현재)까지 획득된 Sentinel-1 SLC(Single Look Complex) 위성자료의 상승(Ascending) 궤도 126장 및 하강(Descending)궤도 187장을 각각 활용하였다. 두 위성궤도를 모두 활용하여 수직, 수평 변위 등 3차원 분석을 수행하였으며, 특히 소양강댐 GPS 관측 자료와 정확도 검증에서 연평균 2mm의 RMSE를 보였다. 이를 통해 위성 원격탐사 기술로도 댐, 보, 방조제와 같은 수자원시설물에 대한 시계열 변위 분석을 통한 댐 안전관리가 가능함을 보여주고 있다. 2025년 발사될 국내 C-밴드 SAR 탑재 수자원위성 개발을 통해 한반도 재방문주기를 단축시킴으로써, 한반도 전역의 수자원시설물 정밀안전진단체계 구축이 가능할 것으로 기대된다.

• Current Optics and Photonics
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• v.8 no.4
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• pp.406-415
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• 2024

The major error factors that degrade the efficiency of coherent beam combining (CBC) are numerically studied in a comprehensive manner, paying particular attention to phase, tip-tilt, polarization angle, and beam quality. The power in the bucket (PIB), normalized to the zero-error PIB, is used as a figure of merit to quantify the effect of each error factor. To maintain a normalized PIB greater than or equal to 95% in a 3-channel CBC configuration, the errors in phase, tip-tilt, and polarization angle should be less than 1.06 radians, 1.25 ㎛, and 1.06 radians respectively, when each of the three parameters is calculated independently with the other two set to zero. In a worst-case scenario of the composite errors within the parameter range for the independent-95%-normalized-PIB condition, the aggregate effect would reduce the normalized PIB to 83.8%. It is noteworthy that the PIB performances of a CBC system, depending on phase and polarization-angle errors, share the same characteristic feature. A statistical approach for each error factor is also introduced, to assess a CBC system with an extended number of channels. The impact of the laser's beam-quality factor M² on the combining efficiency is also analyzed, based on a super-Gaussian beam. When M² increases from 1 to 1.3, the normalized PIB is reduced by 2.6%, 11.8%, 12.8%, and 13.2% for a single-channel configuration and 3-, 7-, and 19-channel CBC configurations respectively. This comprehensive numerical study is expected to pave the way for advances in the evaluation and design of multichannel CBC systems and other related applications.

• Journal of Korean Elementary Science Education
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• v.25 no.spc5
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• pp.556-566
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• 2007

The purpose of this study was to develop an electroencephalogram (EEG) based differential-scale for scientifically gifted students in elementary school. For this study, signals of EEG with 19 channels were recorded during the generation of our scientific hypothesis using 22 scientifically gifted students, and with 49 average students being used as the control group. IQ, TCT and knowledge generation (KG) as constructs of the scientifically gifted were administered for both the scientifically gifted and the normal, control group elementary students. A 'gifted' value was added to paper test scores of the IQ, TCT, and KG constructs in order to make a personal standardization score for the gifted students. As a dependent variable, the groups were divided by means of the standardization scores thus produced and as an autonomous variable, various EEG parameters were presented through linear analysis, nonlinear analysis, and interdependency measures of the EEG. Multiple linear regression analysis was applied successfully to explain the EEG parameters and to show the characteristics of the scientifically-gifted. The discrimination analysis was administered through the results of multiple linear regression of the EEG parameters thus produced. This study represents the foundation of the development of an EEG based discriminant-scale for scientifically gifted students in elementary school, because it will be able to faithfully discriminate between scientifically-gifted and average students. The results of this study indicates that most of the EEG parameters produced can contribute to predicting the characteristics of the scientifically-gifted in that they express the degree of mutual information and the coherence of mutuality. Accordingly, mutual connectivity which appears to originate in the brain seems to the core of discrimination.

• Journal of the Korean Association of Geographic Information Studies
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• v.26 no.1
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• pp.89-113
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• 2023

This study aimed to identify heat wave vulnerable areas and discuss spatial typology and policy directions through spatial coincidence analysis of heat wave damage. By utilizing the climate change vulnerability assessment of the Intergovernmental Panel on Climate Change (IPCC) and Spatial Statistics Comparison Analysis, this study examined cities, counties, and districts in South Korea for five years (2015-2019), including 2018, when the heat wave was most extreme. It was determined that the number of heat wave days (exposure) was the most impactful among various factors for heat wave vulnerability. Sensitivity and adaptive capacity to heat waves were found to vary according to regional characteristics. The relationship between heat wave vulnerability and damage was categorized into four types through spatial coherence. Hot to Hot and Cold to Cold types have a positive relationship between vulnerability and damage, while Hot to Cold and Cold to Hot types have a negative relationship. The findings suggest that since different types of regions have distinct characteristics and conditions, policies and research for improvement should be directed to address each region separately. This study may be used as basic data for establishing heat-related policies in the future, as it categorizes regions by considering both heat vulnerability and damage and examines the direction of response by type.

• Journal of the Korean Society of Systems Engineering
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• v.20 no.spc1
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• pp.12-29
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• 2024

The purpose of this study is to identify the social issues discussed in Korea regarding Maritime Autonomous Surface Ships (MASS), the most advanced ICT field in the shipbuilding industry, and to suggest policy implications. In recent years, it has become important to reflect social issues of public interest in the policymaking process. For this reason, an increasing number of studies use media data and social media to identify public opinion. In this study, we collected 2,843 domestic media articles related to MASS from 2017 to 2022, when MASS was officially discussed at the International Maritime Organization, and analyzed them using text mining techniques. Through term frequency-inverse document frequency (TF-IDF) analysis, major keywords such as 'shipbuilding,' 'shipping,' 'US,' and 'HD Hyundai' were derived. For LDA topic modeling, we selected eight topics with the highest coherence score (-2.2) and analyzed the main news for each topic. According to the combined analysis of five years, the topics '1. Technology integration of the shipbuilding industry' and '3. Shipping industry in the post-COVID-19 era' received the most media attention, each accounting for 16%. Conversely, the topic '5. MASS pilotage areas' received the least media attention, accounting for 8 percent. Based on the results of the study, the implications for policy, society, and international security are as follows. First, from a policy perspective, the government should consider the current situation of each industry sector and introduce MASS in stages and carefully, as they will affect the shipbuilding, port, and shipping industries, and a radical introduction may cause various adverse effects. Second, from a social perspective, while the positive aspects of MASS are often reported, there are also negative issues such as cybersecurity issues and the loss of seafarer jobs, which require institutional development and strategic commercialization timing. Third, from a security perspective, MASS are expected to change the paradigm of future maritime warfare, and South Korea is promoting the construction of a maritime unmanned system-based power, but it emphasizes the need for a clear plan and military leadership to secure and develop the technology. This study has academic and policy implications by shedding light on the multidimensional political and social issues of MASS through news data analysis, and suggesting implications from national, regional, strategic, and security perspectives beyond legal and institutional discussions.