• Bulletin of the Korean Chemical Society
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• 제32권10호
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• pp.3730-3734
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• 2011

The degree of self-assembly and the size variation of nanotubular structures in anodic titanium oxide prepared by the anodization of titanium in ethylene glycol containing 0.25 wt % $NH_4F$ at 40 V were investigated as a function of anodization time. We found that the degree of self-assembly and the size of the nanotubes were strongly dependent on thickness deviation and thus indirectly on anodization time, as the thickness deviation was caused by the dissolution of the topmost tubular structures at local areas during long anodization. A large deviation in thickness led to a large deviation in the size and number of nanotubes per unit area. The dissolution primarily occurred at the bottoms of the nanotubes ($D_{bottom}$) in the initial stage of anodization (up to 6 h), which led to the growth of nanotubes. Dissolution at the tops ($D_{top}$) was accompanied by $D_{bottom}$ after the formed structures contacted the electrolyte after 12 h, generating the thickness deviation. After extremely long anodization (here, 70 h), $D_{top}$ was the dominant mode due to increase in pH, meaning that there was insufficient driving force to overcome the size distribution of nanotubes at the bottom. Thus, the nanotube array became disorder in this regime.

• Asian Journal of Business Environment
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• 제14권2호
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• pp.1-10
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• 2024

Purpose: The purpose of this study is to investigate the essential factors contributing to the growth and success of smart cities, providing a comprehensive analysis of key elements that are crucial in fostering the development of smart cities. This study explored the impacts of technology-driven applications, corporate involvement, the role of experts, citizen co-creation, city-led strategy governance, and sustainable urban practices on overall attitudes towards smart cities. Additionally, the study examined the impact of overall attitude on the growth trajectory of the smart cities and satisfaction. Research design, data and methodology: To collect data, this study employed an online survey conducted by a reputable research organization. Data analysis involved the use of factor analysis, ANOVA, and regression analysis. Results: This study unveiled significant impacts of technology-driven applications, corporate involvement, the role of experts, citizen co-creation, city-led strategy governance, and sustainable urban practices on the overall attitudes. Furthermore, it demonstrated that the overall attitude significantly influences the growth trajectory of smart cities. Conclusions: This study identified key driving factors for smart city development, suggesting that the consideration of sustainable urban practices emerges as the most significant factor influencing the growth of the smart cities.

• 대한인간공학회지
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• 제31권2호
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• pp.397-406
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• 2012

Objective: The aim of this study is to determine legible Korean font sizes within in-vehicle information systems(IVISs) in diving conditions. Background: Font legibility within IVISs is one of important causes on its' safe operations during driving. Several researches proposed some guidelines on the legible English font sizes within IVISs. On the contrary, appropriate Korean font sizes have been hardly known in spite of the typological differences between English and Korean. Therefore, more systematic researches for improving the legibility on Korean font size within IVISs have been required. Method: In this study, an experiment was performed with the following experimental factors: the existence of vibration, the color contrasts(white on black, black on white), the font types(HDR, CubeR, Gothic), and the font sizes(6, 8, 10, 12, 14, 16, 18, 20, 22, 24pt). To fit the experimental conditions into real driving environments, the illuminance was controlled to 15lx by using LED lamp and the distance between IVIS and participants was kept to 70cm. Moreover, all participants took the shutter glasses for employing well-known occlusion techniques. Results: The experimental results showed that 'HDR' and 'Non-vibration + Black on white' group took the shortest response time, and decreasing slopes of the response time with increasing font sizes were slowing down at 14pt then flattened out at 22pt regardless of the existence of vibration and color contrasts. Conclusion: The minimum size for legible Korean font would be about 14pt(5.47mm) and the optimum size would be about 22pt(8.59mm). Application: The guideline on the Korean font sizes from this study will be applied to design an IVIS in the future.

• 한국방사선학회논문지
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• 제17권7호
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• pp.1179-1187
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• 2023

최신 이동수단 발달과 관련하여 다양한 생체 신호 및 의료영상 측정용 의료기술 개발이 활발히 이루어 지고 있다. 특히, 인지/신경과학 분야에서 뇌파(electroencephalography, EEG) 측정의 중요성과 이동 중 차량에서의 정확한 뇌파 측정기술 개발은 매우 도전적인 분야이다. 본 연구에서는, 운전 중 뇌파를 이용한 기술에 대해 광범위하게 조사하고, 기술 연구의 동향을 분석하고자 하였다. 이를 위해, Scopus 데이터베이스를 활용하여 2000년 이후 진행된 뇌파 관련 연구를 탐색하였으며, 약 40여편의 논문을 선정하였다. 이를 통해 신호처리 기술, EEG 측정 디바이스 개발, 차량 내 운전자 상태 모니터링 기술의 현재 동향과 미래 방향을 조명하였다. 또한, 이를 위한 초소형 32채널 뇌파 측정 시스템을 설계해 보았으며, 간단히 이를 구현하여 뇌파 신호를 측정 분석함으로써 검토해 보았다. 본 연구는 운전 중 생체신호 측정 및 분석 기술이 자율주행 시대에 맞추어 운전자 케어와 건강 모니터링에 기여할 것으로 기대한다.

• 한국광학회지
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• 제11권6호
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• pp.452-456
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• 2000

동맥혈의 맥동성분에 의한 파장별 광흡수도를 측정하여 비침습적으로 산소포화도 값을 알수 있는 펄스옥시미터 장치와 신호처리방법을 개발하고 예측 알고리즘을 적용하였다. 본 장치는 광원 및 검출기로 구성된 프로브와 광신호 처리부, LED 구동회로 PC 인터페이스부로 구성되었고 데이터의 수집을 위한 구동소프트웨어 및 데이터 처리 소프트웨어를 개발하였다. 개발된 산소포화도 측정장치의 성능을 평가하는데에는 Bio-Tek 사의 펄스 옥시미터 시뮬레이터를 사용하여 다양한 알고리즘 및 데이터처리 방법들을 비교분석한 결과 맥동파형의 $In(I_p/I_v) 값을 I_{avr}$값으로 보정하는 계산 알고리즘의 방법과 진폭비보다 면적비를 이용한 계산방법이 산소포화도와의 상관관계가 우수한 것으로 나타났다. 정확한 신호 획득을 위해 개발된 맥동의 기저선 보상처리 프로그램을 inv-vivo 테스트의 데이터 처리방법에 적용하여 결과가 향상되는 것을 확인하였고 광원으로 660nm(Red)와 805nm(IR)파장을 이용한 경우보다 660nm(Red)와 940nm(IR) 파장을 이용했을 때 산소포화도와의 상관관계 및 정밀도에서 더 우수한 결과를 얻을 수 있었다.

• Transactions on Electrical and Electronic Materials
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• 제12권6호
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• pp.253-257
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• 2011

This study was carried out to solve problems such as radio frequency band depletion, confusion risk, and security loss in existing visible wireless communication systems, and to determine the applicability of next-generation networks. A light-emitting diode (LED) light communication system was implemented with a controlling switching light module using the ATmega16 micro-controller. To solve the existing modulation effect and disturbance in visible light communication, an integrated interface was evaluated with a driving light module and analyzes its reception property. A transmitter/receiver using the ATmel's micro-controller, high-intensity white LED-6 modules, and infrared sensor KSM60WLM and visible sensor TSL250RD were designed. An experiment from the initial value of distance to 2.5 m showed 0.46 V of the voltage loss, and if in long distance, external light interference occurred and light intensity was lost by external impact and thus data had to be modified or reset repeatedly. Additionally, when we used 6 modules through the remote controller's lighting dimming, data could be transmitted up to 1.76 m without any errors during the day and up to 2.29 m at night with around 2~3% communication error. If a special optical filter can reduce as much external light as possible in the integrated interface, the LED for lighting communication systems may be applied in next generation networks.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 V
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• pp.2835-2838
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• 2003

We study the characteristics of oscillating in non-autonomous condition and the conducted noise generation in a RL-photocoupler circuit. This circuit may be shown a period-doubling and a chaos dynamics under any specific conditions of input circuit. But, the relationship between input signals and output signals is different according to the amplitude of driving input voltage. Then, the oscillation noise was analyzed with respect to both the frequency and the amplitude of an external ac signal and do values. The results show that the noise-induced oscillations for falling and rising cycles induced by kick-back effect in an inductor, nonlinear capacitance, nonlinear resistance and charge storage time in a diode and an LED. We also compared the simulation with the experimental results.

• 반도체디스플레이기술학회지
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• 제6권4호
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• pp.43-47
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• 2007

In this paper, we propose a novel sensor system for measuring the arterial pulse in an oral cavity. In order to measure pulse wave in oral cavity, the proposed system is designed with reflection type arterial wave sensor, not by using transmission type arterial pulse wave sensor. Driving circuit through pulse current is designed for solving self-heating problem of LED. The effectiveness of the proposed sensor system is compared with pulse wave between pulse wave of oral cavity and other body parts as well as with characteristic measurements. The experiment shows that the proposed sensor system is adaptive to capturing consecutive and meaningful biometric signals through the variation of pulse wave changes in oral cavity when exercising. The study result expects to design and develop mobile sensors which could be adapted to healthcare devices.

• International Journal of Concrete Structures and Materials
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• 제6권3호
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• pp.199-207
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• 2012

Concrete is an economical construction material and for that reason it is widely used in buildings and infrastructures. The use of deicing salts, expansion joint failure, and freeze-thaw cycles have led to concrete bridge girders experiencing corrosion of steel reinforcement and becoming unsafe for driving. The goal of this research is to assess the effectiveness of current and possible repair techniques for the end region of damaged prestressed concrete girders. To do this, three American Association of State Highway and Transportation prestressed concrete girders were tested to failure, repaired, and retested. Three different repair materials were tested including carbon fiber, glass fiber, and surface mounted rods. Each different repair material was also tested with and without injected epoxy. Comparisons were then made to determine if injecting epoxy had a positive effect on stiffness and strength recovery as well as which repair type regained the largest percentage of original strength.

• 통상정보연구
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• 제9권4호
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• pp.91-104
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• 2007

The recent stabilization of the Internet is now driving every aspect of life into an Internet presence. In the coming years, the Internet will see growth in numbers unlike the world has ever seen. The subject of this study is the Research Study on the Products Purchase Type of On-line Shopping Mall Buyer. Also, this paper is to examine the relations between customer satisfaction and intensity of repurchase intention and complaining behavior in on-line context. On-line shopping customer depths interview it led and the online afternotes trust evaluation dimension was discovered the of useful characteristic, intention characteristic, exaggerating characteristic and on-line afternotes with or without. From these results, this paper suggests effective marketing strategy to the marketer who plans to run on-line shopping mall in the near future and also to the marketer who plans to sell products through the on-line shopping mall.