• 한국분말재료학회지
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• 제16권4호
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• pp.254-261
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• 2009

In this study, we investigated the unit process parameters in spherical $UO_2$ kernel preparation. Nearly perfect spherical $UO_3$ microspheres were obtained from the 0.6M of U-concentration in the broth solution, and the microstructure of the $UO_2$ kernel appeared the good results in the calcining, reducing, and sintering processes. For good sphericity, high density, suitable microstructure, and no-crack final $UO_2$ microspheres, the temperature control range in calcination process was $300{\sim}450^{\circ}C$, and the microstructure, the pore structure, and the density of $UO_2$ kernel could be controlled in this temperature range. Also, the concentration changes of the ageing solution in aging step were not effective factor in the gelation of the liquid droplets, but the temperature change of the ageing solution was very sensitive for the final ADU gel particles.

• 센서학회지
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• 제15권5호
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• pp.334-340
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• 2006

A compact biosignal monitoring device was developed. Electrodes for electrocardiogram (ECG) and a LED and silicon detector for photoplethysmogram (PPG) were used. A lead II type was arranged for ECG measurement and reflected light was measured at the finger tip for PPG. A single chip microprocessor (model ADuC812, Analog Device) controlled a measurement protocol and processed measured signals. PPG and ECG had a sampling rate of 300 Hz with 8-bit resolution. The maximum power consumption was 100 mW. The microprocessor computed pulse transit time (PTT) between the R-wave of ECG and the peak of PPG. To increase the resolution of PTT, analog peak detectors obtained the peaks of ECG and PPG whose interval was calculated using an internal clock cycle of 921.6 kHz. The device was designed to be operated by 3-volt battery. Biosignals can be measured for $2{\sim}3$ days continuously without the external interruptions and data is stored to an on-board memory. Our system was successfully tested with human subjects.

• 천문학논총
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• 제16권1호
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• pp.31-36
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• 2001

We present the characteristics of the 2K CCD camera at the Bohyunsan Optical Astronomy Observatory of the Korea Astronomy Observatory at the time of its development. The purpose of this paper is to support the observers who may need detailed information on the characteristics of the camera and to provide helpful information on the optimization' of a CCD camera for those who try to develop their own camera. The 2K CCD camera was optimized to have a gain of $1.8e^-/ADU$ and a read out noise of $7e^-$ from an experiment using radioactive $^{55}Fe$ X-ray source. The charge transfer efficiency was measured as 0.9999976 for serial and 0.9999942 for parallel direction, which means $0.5\%$ charge loss along the serial direction and $1.2\%$ along the parallel direction across the chip. The quantum efficiency of the camera was measured from an experiment using a homogeneous light source consisting of a halogen lamp and an integrating sphere with a monochromator. The resulting quantum efficiency of the camera peaked at the wavelength range 600-700 nm with the value of $\~0.89$.

• 천문학논총
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• 제18권1호
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• pp.75-79
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• 2003

The characteristics of the BOES (Bohyunsan Observatory Echelle Spectrograph) CCD camera is presented. In order to get optimum gain and readout noise of the CCD, we examine the variation of the gain and readout noise by changing the value of output drain voltage of the CCD and measuring the gain using transfer curve, which is defined as the plot of variance versus mean exposure level of a homogeneous light onto the CCD surface. The gain and readout noises are optimised to be 0.5e$^-$/ADU and 3e$^-$, which is good for highest signal-to-noise ratio and contrast for the low light level characteristics of the BOES. We also measure the dark count of the CCD by getting five dark images with 3600 seconds exposure time. The mean dark count from median stacked dark images is essentially zero. A table of positions of defected pixels is also presented.

• 한국분말재료학회지
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• 제14권1호
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• pp.8-12
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• 2007

The effect of a CAM (Continuous Attrition Mill) treatment on the sinterability of ex-ADU $UO_2$ powder was investigated. As the cycles of a CAM increased, the apparent density, specific surface area and O/U of the milled powder increased, but there particle sizes decreased. However the sintered density of the $UO_2$ pellet decreased as the cycles of the CAM increased. It is considered that the decrease of the sintered density is due to the formation of $U_3O_8$, which was produced by a CAM mechanism.

• 한국보건간호학회지
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• 제14권2호
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• pp.342-354
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• 2000

This study was conducted to identify the characteristics of activities of daily living(ADU) and its influencing factors in patients with chronic arthritis. The data were obtained from 104 patients with chronic arthritis in one university hospital from May to August. 2000. For analysing data. SAS program was used for t-test. ANOVA, Schefte test. Pearson correlation. and stepwise multiple regression. The results were as follows: 1. The variables which influenced self-efficacy were duration of disease. number of painful joint, quality of sleep and alcohol drinking. 2. The variables which influenced fatigue were diagnosis and number of painful joint. 3. The variables which influenced ADL were age. duration of disease. diagnosis. number of painful joint. number of exercise and alcohol drinking. 4. ADL was positive correlation with self-efficacy and negative correlation with fatigue. And self-efficacy was negative correlation with fatigue. 5. The predictors to explain ADL were self-efficacy. number of painful joint. lupus. duration of disease and religion. These predictors explained $66.01\%$ of the activites of daily living. According to these findings. the most significant influencing factor of ADL was self-efficacy. therefore the development of nursing intervention for enhancing self-efficacy would be needed. Also. it is suggested that an exercise program should be recommended as one of useful and appropriate nursing intervention for reducing fatigue and increasing ADL.

• Spatial Information Research
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• 제10권4호
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• pp.501-513
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• 2002

Eurasian otter (Lutra lutra) is one of endangered wildlife species whose population size is declining in Korea. To manage and conserve habitat for Eurasian otter, it is crucial to understand which habitat components affect otter habitat qualities. The objectives of this study were to develop a habitat suitability model of Eurasian otter in Soraksan National Park, to validate the model in Odaesan National Park. The research methods of this study were as follows. First, trace data and characters of Eurasian otter habitat were collected with Geographic Information System (GIS) data and Global Positioning System (GPS) receivers between 2000 and 2002. Second, the habitat use factors were identified as habitat characteristics of Eurasian otter and classified with habitat use and availability analyses. Third, significant factors of habitat model were extracted by Chi-square test. The last, Eurasian Otter Habitat Suitability Model (EOHSM) was employed by logistic regression method. Otter habitat use was positively associated with the reeds and shrubs areas adjacent to streams, the size of boulders, and low human disturbance in Soraksan National Park by EOHSM. This model had a classification accuracy of 74.4% at cutoff value of 0.5. Model validation showed a classification accuracy of 86.6 % at cut off value of 0.5 for otter habitat in Odaesan National Park.

• 한국측량학회지
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• 제19권2호
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• pp.189-198
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• 2001

우리는 사회가 고도로 정보화되고 정보에 대한 수요가 급증하고 있는 21세기에 살고 있다. 따라서 각 지역사회의 정보화 수준은 지역발전의 지표가 되고 있으며, GIS는 공간정보를 관리·분석할 수 있는 새로운 국가정보기반으로 부각되었다. 따라서, 많은 지자체들이 GIS의 중요성을 인식하고 GIS 기술을 사용하여 여러 업무분야에 활용하고자 효과적인 GIS구축을 위한 기본계획을 수립 중에 있다. 따라서 본 연구에서는 각 지자체의 G3S 기본계획 현황과 문제점을 분석하고 이를 토대로 GIS 기본계획 수립의 개선방향을 제시하였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 추계학술대회 논문집
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• pp.878-881
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• 2005

A Stereolithography technology is based on stacking of sliced layer from STL file that is converted from 3-dimensional CAD data. A microstereolithography technology is evolved from conventional stereolithography to fabricate microstructures. In this technology, we have to consider influence of resin flow to make refresh surface. To generate new resin surface, stage has to be moved downward deeply and upward to desired position. At this time, resin flow affects to refresh surface of resin. And resin viscosity is the key factor in simulation of resin flow. By setting optimal refresh time for resin surface, total fabrication time is reduced and there is no damage to fabricated layers. In this research, we simulate resin flow using CFD software and derive optimal stage moving time and dwelling time.

• Journal of Smart Tourism
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• 제1권3호
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• pp.31-44
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• 2021

The emergence of the digital economy and easy accessibility to Web 2.0 tools has seen an expansion of the influencer ecosystem within the travel and tourism industry. Founded on the principles of reference groups and peer reference there is a growing trend amongst industry practitioners who are now opting to move away from many of the traditional approaches used to market their products and services and are instead taking advantage of the concept of e-word-of-mouth (eWOM). Whilst there is a growing body of academic literature addressing the notion of influencer marketing, there is little understanding of influencer marketers themselves. Consequentially, this study addresses this gap in the literature through the quantitative examination of those who promote products, services, or companies by distributing eWOM through their online digital channels and presence; otherwise known as travel influencers. A quantitative research approach involving an online survey yielded 255 responses from travel influencers. The research findings indicate that those who work in this field prefer not to be awarded the label "travel influencer," focusing instead on their specific method of influencing, such as blogging and vlogging or sharing Instagram updates. The research also demonstrates how the new influencers have a strong role in generating travel urge and desire. The research contributes to the wider body of academic literature and travel industry practitioners by establishing the general profile of influencers and their increasingly specialized role in tourism and hospitality marketing.