• Journal of Industrial and Engineering Chemistry
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• 제68권
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• pp.274-281
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• 2018

Experimental studies of the hydrodynamic performance of the draft tube conical spout-fluid bed (DCSF) were conducted using pharmaceutical pellets. The experiments were carried out in a DCSF consisted of two sections: (a) a conical section with the cross section of $120mm{\times}250mm$ and the height of 270 mm, (b) a cylindrical section with the diameter of 250 mm and the height of 600 mm. The flow characteristics of solids were investigated with a high speed camera and a pezoresistive absolute pressure transducer simultaneously. These characteristics revealed different flow regimes in the DCSF: packed bed at low gas velocities, fluidized bed in draft tube at higher gas velocities until minimum spouting, and spouted bed. The stable spouting was identified by the presence of two dominant frequencies of the power spectrum density of pressure fluctuation signature: (i) the frequency band 6-9 Hz and (ii) the frequency band 12-15 Hz. The pressure drops across the draft tube as well as the annulus measured in order to better recognize the flow structure in the DCSF. It was observed that the pressure drop across the draft tube, the pressure drop across the annulus, and the minimum spouting velocity increase with the increase in the height of draft tube and distance of the entrainment zone, but with the decrease in the distributor hole pitch. Finally, this study provided novel insight into the hydrodynamic of DCSF, particularly minimum spouting and stable spouting in the DCSF which contains valuable information for process design and scale-up of spouted bed equipment.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2015년도 학술발표회
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• pp.244-244
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• 2015

Managed Aquifer Recharge (MAR) in the form of Aquifer Storage and Recovery (ASR) systems are being applied for numerous water augmentation projects both in developed and developing countries. Given the onset of Climate Change and its influence on weather patterns and land use, it has been acknowledged the utilization of this technology will be ever increasing. This technique like all others does have its drawbacks or disadvantages, whereby to overcome these drawbacks or disadvantages it is recommended that logical planning process be followed. In this study, we developed a decision framework known as "Decision framework for the planning, designing, construction/testing and implementation of subsurface water storage system" to further standardize the planning and design process of subsurface water storage system to increase the probability of having a successful ASR/ASTR project. The formulation of this framework was based on earlier frameworks, guidelines, published papers and technical reports which were compiled into a data collection database. The database of which consider both qualitative and quantitative aspect for example recharge objectives, site location, water chemistry of the native, source and recovered water, aquifer characteristics(hydraulic conductivity, transmissivity, porosity), injection/pumping rate, ecological constraints, societal restrictions, regulatory restrictions etc. The assimilation of these factors into a singular framework will benefit the broad spectrum of stakeholder as it maps the chronological order under which ASR project should be undertaken highlighting at each stage the feasibility of the project. The final stage of which should result in fully operational ASR system. The framework was applied to two case studies and through the application of a modified ASR site selection suitability index (Brown et al., 2005) a score was derived to identify the performance of each site. A high score of which meant a maximize chance of success given the reduce presence of project constraints.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2009년도 춘계학술대회
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• pp.175-179
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• 2009

본 논문에서는 전장용 아날로그 스위치 및 공조기 부하 유닛의 신뢰성 실험 중에서 EMC 스펙에 만족할 수 있도록 하는 필터 설계를 제안한다. EMC 규격에 만족하면서 전자부품들의 상호 간섭과 주변 환경의 영향을 최소화하고 제품의 품질 향상을 위해 전자파 필터를 적용하였다. 본 논문에서는 ISO/JASO 표준규격의 주파수범위인 30MHz ~ 1GHz 대역에서 스펙트럼 분석기와 간이 EMI 챔버를 이용한 시뮬레이션을 통해 특정 주파수 대역의 에너지 분포를 분석하였으며, 최적의 전자파 필터를 구현하기 위해 필터를 구성하는 소자의 용량을 결정하였다. 실제 필터 추가를 통해 노이즈가 감소한 것을 공인인증기관에서 증명하였으며, 전장용 아날로그 스위치 및 공조기 부하 유닛에 적용하여 전자파 간섭을 일으키지 않고 정상적인 동작을 수행하는 것을 확인하였다.

• Journal of the Optical Society of Korea
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• 제18권3호
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• pp.274-282
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• 2014

In this study, closely spaced Au nanoparticles which are arranged in nanocluster (heptamer) configurations have been employed to design efficient plasmonic subwavelength devices to function at the telecommunication spectrum (${\lambda}$~1550 nm). Utilizing two kinds of nanoparticles, the optical properties of heptamer clusters composed of Au rod and shell particles that are oriented in triphenylene molecular fashion have been investigated numerically, and the cross-sectional profiles of the scattering and absorption of the optical power have been calculated based on a finite-difference time-domain (FDTD) method. Plasmon hybridization theory has been utilized as a theoretical approach to characterize the features and properties of the adjacent and mutual heptamer clusters. Using these given nanostructures, we designed a complex four-branch ($1{\times}4$) Y-shape splitter that is able to work at the near infrared region (NIR). This splitter divides and transmits the magnetic plasmon mode along the mutual heptamers arrays. Besides, as an important and crucial parameter, we studied the impact of arm spacing (offset distance) on the guiding and dividing of the magnetic plasmon resonance propagation and by calculating the ratio of transported power in both nanorod and nanoshell-based structures. Finally, we have presented the optimal structure, that is the four-branch Y-splitter based on shell heptamers which yields the power ratio of 23.9% at each branch, 4.4 ${\mu}m$ decaying length, and 1450 nm offset distance. These results pave the way toward the use of nanoparticles clusters in molecular fashions in designing various efficient devices that are able to be efficient at NIR.

• Journal of the Optical Society of Korea
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• 제18권3호
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• pp.261-273
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• 2014

In this paper, metal insulator metal (MIM) plasmonic slot cavity narrow band-pass filters (NBPFs) are studied. The metal and dielectric of the structures are silver (Ag) and air, respectively. To improve the quality factor and attenuation range, two novel NBPFs based on tapered structures and double cavity systems are proposed and numerically analyzed by using the two-dimensional (2-D) finite difference time domain (FDTD) method. The impact of different parameters on the transmission spectrum is scrutinized. We have shown that increasing the cavities' lengths increases the resonance wavelength in a linear relationship, and also increases the quality factor, and simultaneously the attenuation of the wave transmitted through the cavities. Furthermore, increasing the slope of tapers of the input and output waveguides decreases attenuation of the wave transmitted through the waveguide, but simultaneously decreases the quality factor, hence there should be a trade-off between loss and quality factor. However, the idea of adding tapers to the waveguides' discontinuities of the simple structure helps us to improve the device total performance, such as quality factor for the single cavity and attenuation range for the double cavity. According to the proposed NBPFs, two, three, and four-port power splitters functioning at 1320 nm and novel ultra-compact two-wavelength and triple-wavelength demultiplexers in the range of 1300-1550 nm are proposed and the impacts of different parameters on their performances are numerically investigated. The idea of using tapered waveguides at the structure discontinuities facilitates the design of ultra-compact demultiplexers and splitters.

• 융합정보논문지
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• 제11권9호
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• pp.130-137
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• 2021

주파수를 갖는 외부 가진력에 의하여 강제 진동의 특성을 가진력의 진폭과 주파수에 따라 그 특성을 분석하였다. 변위, 속도 및 가속도를 얻기 위해 수치해석을 수행하여 주파수 응답을 얻었고 특히 주파수 영역에서 시스템 고유진동수와 가진 주파수의 발생 위치를 밝히고자 각각의 FRF의 분석을 하였다. 외부 가진에 의한 진동모델에서 변위, 속도 및 가속도의 거동과 주파수 응답함수에서 고유진동 주파수와 주변의 가진 모드 분포도 파워 스펙트럼과 실수부와 허수부의 FRF 에서 나타났으며 각 모드 특성도 구하였다. 진동의 응답은 가진 신호의 크기와 주파수를 주어 정현파의 가진력으로 외부 가진력을 근사화 하였고 이런 가진력에 의하여 발생하는 모드를 구별할 수 있었다. 상당 질량, 감쇠 및 강성을 변화시켜 수치 분석 후 외부 가진력에 의한 강제 진동 응답 특성을 체계적으로 분석하였다.

• Nuclear Engineering and Technology
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• 제53권2호
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• pp.626-636
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• 2021

Boron-neutron capture therapy (BNCT) is a cancer treatment method that exploits the high neutron reactivity of boron. Monitoring the prompt gamma rays (PGs) produced during neutron irradiation is essential for ensuring the accuracy and safety of BNCT. We investigate the imaging of PGs produced by the boron-neutron capture reaction through Monte Carlo simulations of a gamma camera with a SrI₂ scintillator and parallel-hole collimator. GAGG scintillator is also used for a comparison. The simulations allow the shapes of the energy spectra, which exhibit a peak at 478 keV, to be determined along with the PG images from a boron-water phantom. It is found that increasing the size of the water phantom results in a greater number of image counts and lower contrast. Additionally, a higher septal penetration ratio results in poorer image quality, and a SrI₂ scintillator results in higher image contrast. Thus, we can simulate the BNCT process and obtain an energy spectrum with a reasonable shape, as well as suitable PG images. Both GAGG and SrI₂ crystals are suitable for PG imaging during BNCT. However, for higher imaging quality, SrI₂ and a collimator with a lower septal penetration ratio should be utilized.

• 한국융합학회논문지
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• 제10권9호
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• pp.249-255
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• 2019

본 연구는 조현병스펙트럼 및 기타정신병적장애 진단을 받은 환자들(이하 조현병 환자)을 대상으로 목표달성척도를 적용하고 효과성을 평가하는데 있다. 연구 대상자들은 목표달성척도를 활용하여 자신의 개별목표를 설정하고 목표의 달성 정도를 정기적으로 자가 평가하였다. 연구 대상자들의 목표달성점수를 계산하여 목표달성 정도를 나타냈다. 평가를 위해 사전-사후검사를 실시하였고 선형혼합효과모형을 사용하여 목표달성척도 적용의 효과를 분석하였다. 평가결과, 연구 대상자들의 목표달성점수는 측정시점에 따라 점차 증가하였고 이러한 증가는 통계적으로도 유의미하였다. 본 연구는 조현병 환자들을 위해 자기결정을 통한 목표 설정, 목표성취 그리고 그 과정을 지원하는 것이 중요하다는 것을 보여준다. 본 연구결과를 통해 도출된 임상적 함의, 연구의 한계 등이 추가로 논의되었다.

• 한국ITS학회 논문지
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• 제18권1호
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• pp.83-90
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• 2019

LED조명의 강점을 토대로 LED조명이 보급되고 있으며, 다양한 정부정책이 시행되고 있다. 조명을 활용한 무선통신 기술인 VLC 연구가 활발히 이루어지고 있으며, 많은 연구를 통해서 고속 데이터 전송기와 같은 일반적인 LED 광원을 사용할 수 있다는 것이 증명되었다. 그러나 여전히 주요 문제 중 하나로 라디오 방송의 잡음과 유사한 빛의 간섭문제가 있다. 이에 본 논문에서는 스펙트럼 분리형 VLC 채널을 위한 광 필터를 사용하여 주변 조명의 간섭을 제거하기 위한 모델을 제안하였다. 제안한 모델의 검증을 위하여 다양한 고휘도 RGB LED 모듈을 활용하여 비교분석을 진행하였으며, 추가로 실생활에 적용되어 활용 중인 고휘도 LED 조명을 활용한 실험을 통한 적용성을 검증하였다.

• International journal of advanced smart convergence
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• 제8권3호
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• pp.27-38
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• 2019

I reviewed about dyeing fastness and functional properties of the non-mordant dyed cotton and iron mordant dyed cotton with astringent persimmon juice. In the UV-VIS spectrum of astringent persimmon juice, the maximum absorption wavelength of the juice was 272.0 nm, which was a characteristic peak of tannin. In dyeing fastness, light fastness of the non-mordant dyed cotton was a little low at grade 2~3. But by the iron mordant treatment, the light fastness was good at grade 4. Dry cleaning fastness to discoloration and contamination was excellent at grade 4~5 for both the non-mordant dyed cotton and iron-mordant dyed cotton. Their rub fastness were grade 3 and grade 2~3 respectively, in the dry condition, and grade 2~3 and grade 3 respectively, in the wet condition. In the perspiration fastness of the non-mordant dyed cotton, the discoloration from acidity and alkalinity was grade 3~4 and grade 3, respectively, and contamination from acidity and alkalinity was relatively good at grade 4. Meanwhile, in the perspiration fastness of the non-mordant dyed cotton, discoloration from acidity and alkalinity was fair, both recording grade 3~4, and contamination from acidity and alkalinity was very good, both recording grade 4~5. In the ultraviolet protection effect of the non-mordant dyed cotton and iron-mordant dyed cotton, the ultraviolet protection factor was both 50+, both of which showed an excellent ultraviolet blocking effect. And the protection rate of UV-A appeared 98.4% and 99.1%, respectively, and the protection rate of UV-B showed 98.7% and 99.2, respectively. In addition, both exhibited an excellent deodorization rate over 99.9% or more, irrespective of the passage of time. Also, both showed an excellent antimicrobial activity over 99.9% or more against Staphylococcus aureus and Klebsiella pneumoniae.