• 한국정보통신학회논문지
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• 제13권5호
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• pp.845-853
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• 2009

본 논문은 정부에서 추진중인 유비쿼터스도시의 성공적 건설을 위하여 공동주택에 설치되는 홈 네트워크설비를 포함한 전기통신설비 및 방송공동수신설비의 기술기준과 초고속 정보통신건물인증제도의 문제점을 알아보고 해결방안으로 주택법령의 주택성능 등급표시 제도보완과 유지관리를 제도화 하기위한 주택법계열의 전면적인 검토 보완 및 개정안을 제시하였다. 또한 기술기준만을 적용한 건축물과 초고속 정보통신건물 인증 2등급 이하 취득 건축물 그리고 상기 해결방안이 법제도화가 되었을 때의 건축물에 대한구내 정보통신선로 통합구축 모델을 각각 설계하여 제시하였다.

• Asian Pacific Journal of Cancer Prevention
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• 제15권13호
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• pp.5111-5116
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• 2014

Computed Tomography Colonography (CTC) is a medical imaging technology used in identifying polyps and colon cancer masses in the large intestine. The technique has evolved a great deal since its invention and has become a routine diagnostic procedure in Western countries due to its non invasiveness and ease of use. The objective of our study was to explore the possibility of CTC application in Indian hospitals. This paper gives an overview of the procedure and its commercial viability. The explanation begins with the domain aspects from gastroenterologist perspective, the new way of thinking in polyp classification, the technical components of CTC procedure, and how engineering solutions have helped clinicians in solving the complexities involved in colon diagnosis. The colon cancer statistics in India and the results of single institution study we carried out with retrospective data is explained. By considering the increasing number of patients developing colon malignancies, the practicality of CTC in Indian hospitals is discussed. This paper does not reveal any technical aspects (algorithms) of engineering solutions implemented in CTC.

• 한국도서관정보학회지
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• 제42권3호
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• pp.79-103
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• 2011

이 연구는 현장 사서의 입장에서 대학도서관 수서정리 업무에 관한 학술연구가 도서관 현장에 어떤 의미와 유용성을 가지는지 살펴보고, 그에 대한 문제점과 해결방안을 모색한 것이다. 문제의 원인을 도서관과 사서의 측면, 학계의 측면으로 나누어 분석하고 이 둘을 링크해야 하는 국가기관의 역할 부족에 대하여 생각해 보았다. 또한 학술연구가 현장에 유용성을 가지기 위해 필요한 것으로 학계와 현장 간 커뮤니케이션의 장, 사서의 현장연구적 자세, 학계의 현장에 대한 직접적 검증 행위의 반복 등을 제안하였다. 현재 사서들은 학술연구로부터 업무에 직접적인 도움을 받기 어려운 면이 많다고 하였으나, 도서관 현장과 학계는 상호간의 교류를 통해 도움을 주고 받으며 공존해 가는 것이 반드시 필요하다

• Korean Chemical Engineering Research
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• 제58권2호
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• pp.301-306
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• 2020

We investigated the individual biosorption removal of lead, copper, and nickel ions from aqueous solutions using Chara sp. algae powder in a batch mode. The impact of several parameters, such as initial concentration of the metal ions, contacting time, sorbent dose, and pH on the removal efficiency, was investigated. The maximum removal efficiency at optimum conditions was found to be 98% for Pb(II) at pH = 4, 90% for Cu(II) at pH = 5, and 80% for Ni(II) at pH = 5. The isotherm study was done under the optimum conditions for each metal by applying the experimental results onto the well-known Freundlich and Langmuir models. The results show that the Langmuir is better in describing the isotherm adsorption of Pb(II) and Ni(II), while the Freundlich is a better fit in the case of Cu(II). Similarly, a kinetic study was performed by using the pseudo-first and second-order equations. Our results show that the pseudo-second-order is better in representing the kinetic adsorption of the three metal ions.

• Environmental Engineering Research
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• 제25권3호
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• pp.426-438
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• 2020

In this study, cherry kernel shell pyrolytic charcoal was synthesized (CKSC) and composite beads were obtained by blending this pyrolytic charcoal with chitosan and Fe₂O₃ nanoparticles (Fe-C-CKSC). Cr(VI) adsorption from aqueous solutions by Fe-C-CKSC composite beads and CKSC adsorbents was studied comparatively. The effects of Cr(VI) initial concentration, adsorbent dosage, contact time, pH and temperature parameters on Cr(VI) adsorption were investigated. Adsorption reached an equilibrium point within 120 min for CKSC and Fe-C-CKSC adsorbents. The maximum Cr(VI) removal was obtained at the initial pH value of 1.56 for CKSC and 2.00 for Fe-C-CKSC. The optimum adsorbent dosage was found to be 5 g/L for CKSC and 3 g/L for Fe-C-CKSC. Based on the Langmuir model, the maximum adsorption capacities were calculated as 14.455 mg/g and 47.576 mg/g for CKSC and Fe-C-CKSC, respectively. Thermodynamic and kinetic studies were performed. As a result of adsorption kinetics calculations, adsorption was found to be consistent with the pseudo second order kinetic model. Characterization of the synthesized adsorbents was performed by SEM, BET, FTIR and elemental analysis. This study has shown that low cost adsorbents CKSC and Fe-C-CKSC can be used in Cr(VI) removal from aqueous solutions.

• Structural Engineering and Mechanics
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• 제76권3호
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• pp.325-336
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• 2020

In this study, the continuous and discontinuous contact problems of functionally graded (FG) layer resting on a rigid foundation were considered. The top of the FG layer was loaded by a distributed load. It was assumed that the shear modulus and the density of the layer varied according to exponential functions along the depth whereas the the Poisson ratio remained constant. The problem first was solved analytically and the results were verified with the ones obtained from finite element (FE) solution. In analytical solution, the stress and displacement components for FG layer were obtained by the help of Fourier integral transform. Critical load expression and integral equation for continuous and discontinuous contact, respectively, using corresponding boundary conditions in each case. The finite element solution of the problem was carried out using ANSYS software program. In continuous contact case, initial separation distance and contact stresses along the contact surface between the FG layer and the rigid foundation were examined. Separation distances and contact stresses were obtained in case of discontinuous contact. The effect of material properties and loading were investigated using both analytical and FE solutions. It was shown that obtained results were compatible with each other.

• Smart Structures and Systems
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• 제5권6호
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• pp.613-632
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• 2009

The present paper is concerned with the design of a proper patch actuator network in order to track a desired displacement of the sidewalls of a one-storey frame structure; both, for the static and the dynamic case. Weights for each patch of the actuator network found in our previous work were based on beam theory; in the present paper a refinement of these weights by modeling the sidewalls of the frame structure as thin plates is presented. For the sake of calculating the refined weights approximate solutions of the plate equations are calculated by an extended Galerkin method. The solutions based on the analytical plate model are compared with three-dimensional Finite Element results computed in the commercially available code ANSYS. The patch actuator network is put into practice by means of four piezoelectric patches attached to each of the two sidewalls of the frame structures, to which electric voltages proportional to the analytically refined patch weights are applied. Analytical and numerical results coincide very well over a broad frequency range.

• 한국표면공학회지
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• 제55권5호
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• pp.247-260
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• 2022

Since the first report on ferroelectricity in Si-doped hafnia (HfO2), this emerging ferroelectrics have been considered promising for the next-generation semiconductor devices with their characteristic nonvolatile data storage. The robust ferroelectricity in the sub-10-nm thickness regime has been proven by numerous research groups. However, extending their scalability below the 5 nm thickness with low temperature processes compatible with the back-end-of-line technology. In this review, therefore, the current status, technical issues, and their potential solutions of atomic layer deposition (ALD) of HfO₂-based ferroelectrics are comprehensively reviewed. Several technical issues in the physical scaling of the ferroelectric thin films and potential solutions including advanced ALD techniques including discrete feeding ALD, atomic layer etching, and area selective ALD are introduced.

• ETRI Journal
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• 제44권5호
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• pp.715-732
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• 2022

Despite the successful launch of Advanced Television Systems Committee (ATSC) 3.0 broadcasting worldwide, broadcasters are facing obstacles in constructing void-less large-scale single-frequency networks (SFNs). The bottleneck is the absence of decent on-channel repeater (OCR) solutions necessary for SFNs. In the real world, OCRs suffer from the maleficent feedback interference (FI) problem, which overwhelms the desired input signal. Moreover, the undesired multipaths between studio-linked transmitters and the OCR deteriorate the forward signals' quality as well. These problems crucially restrict the feasibility of conventional OCR systems, arousing the strong need for cost-worthy advanced OCR solutions. This paper presents an ATSC 3.0-specific solution of advanced OCR that solves the FI problem and refines the input signal. To this end, the FI canceler and channel equalizer functionalities are carefully implemented into the OCR system. The presented OCR system is designed to be fully compliant with the ATSC 3.0 specifications and performs a fast and efficient signal processing by exploiting the specific frame structure. The real product of ATSC 3.0 OCR is fabricated as well, and its feasibility is verified via field and laboratory experiments. The implemented solution is installed at a commercial on-air site and shown to provide substantial coverage gain in practice.

• Advances in materials Research
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• 제11권2호
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• pp.165-170
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• 2022

Acrylic resin or polymethylmethacrylate (PMMA) is one of the most attractive materials to be used for dental appliances manufacturing. It has been introduced as a biomaterial during the last century. This study aims to evaluate the compounds absorption and release through acrylic resin to be used for drug delivery as well. The study specimens were 10 pieces of heat-cured clear acrylic resin with dimensions of 10 × 10 × 2 mm. The specimens were dipped in methylene blue solution at a powder-water ratio of 1:20 for 5 days. The samples were removed and dipped in 5 ml distilled water vials for 24 hours. Then the specimens were replaced into new 5 ml vials and the process lasted for 4 days. The extracted solutions were analyzed by the visible light spectroscopy for absorbance. The statistical results showed a gradual increase in stain release from day 1 to day 4 with a significant difference between day 1 and day 4 solutions. The study showed that PMMA resin is able to absorb and release some compounds constantly and the absorption drug-loading technique is applicable to this material.