• 한국환경과학회지
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• 제17권11호
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• pp.1195-1201
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• 2008

Enhancing with non-metallic elemental nitrogen(N) is one of several methods that have been proposed to modify the electronic properties of bulk titanium dioxide($TiO_2$), in order to make $TiO_2$ effective under visible-light irradiation. Accordingly, current study evaluated the feasibility of applying visible-light-induced $TiO_2$ enhanced with N element to cleanse aromatic compounds, focusing on xylene isomers at indoor air quality(IAQ) levels. The N-enhanced $TiO_2$ was prepared by applying two popular processes, and they were coated by applying two well-known methods. For three o-, m-, and p-xylene, the two coating methods exhibited different photocatalytic oxidation(PCO) efficiencies. Similarly, the two N-doping processes showed different PCO efficiencies. For all three stream flow rates(SFRs), the degradation efficiencies were similar between o-xylene and m,p-xylene. The degradation efficiencies of all target compounds increased as the SFR decreased. The degradation efficiencies determined via a PCO system with N-enhanced visible-light induced $TiO_2$ was somewhat lower than that with ultraviolet(UV)-light induced unmodified $TiO_2$, which was reported by previous studies. Nevertheless, it is noteworthy that PCO efficiencies increased up to 94% for o-xylene and 97% for the m,p-xylene under lower SFR(0.5 L $min^{-1}$). Consequently, it is suggested that with appropriate SFR conditions, the visible-light-assisted photocatalytic systems could also become important tools for improving IAQ.

• Architectural research
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• 제13권3호
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• pp.3-10
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• 2011

The Characteristics of space are determined by several factors; however, the element that determines the physical characteristic of floors, walls, and ceiling is the structure. This study constructs a wall to analyze the direct effect that the layout of an exhibition wall has on the element of the wall followed by the structural process and visibility of descriptive analysis and examples of art museums that the shift from a perceptional wall to an experiential wall affected circulation. For elements and formation methods of the wall, first, it is made up of open and closed type exhibition spaces, and it can give abundance in qualitative space rather than a quantitative aspect. Secondly, the directivity of space changes according to the development of the visible axis, thus, directly affects the change in visibility. Thirdly, the difference between spatial structure and visual structure is the difference between the visual axis and spatial structure. The wall formation type followed by the combination method, the simple visible structure, which is the type that possesses the simple combination (Room, Zone, Cluster), repeatedly uses the same size of units of space that is orderly and has few spatial axes and the classification of simple type and simple cluster type, which has few visible axes, also exists. Also, with the complex structure of the maze type it displays the reiterated form of the cluster, which is the space with disorderly combination and has much visible axes and spatial axes. Also, these can be divided into three types: 1) Maze Cluster Type, 2) Cross Road Type, and 3) Open Flexible Type. These wall types lead the various changes in circulation, and even each of the arrangement qualities of the exhibitions should be researched according to its exhibition place type.

• 한국조경학회지
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• 제27권4호
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• pp.73-79
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• 1999

This study is on the production and the classification of a new appreciation methods of seascape through materials in the words of Korean popular songs. In advance, it is necessary to understand the popular songs as collective representation and the songs are analytic data. In this study, some essential elements of seascape in popular songs are analyzed and classified. They are; 1. visible elements-weather, time, season and object. 2. all senses-vision, audition, olfaction, tactile sense, and spatial sense. 3. the line of vision-static line of vision and dynamic line of vision. In this way data is produced, and then the result of this study makes appreciation methods of seascape developed. In this way, this study results in developed appreciation of seascape. This study on new understanding of appreciation methods of seascape is on the basis of a design method of water-front that is considered a visible scene, not a design of construction elements.

• Coupled systems mechanics
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• 제12권5호
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• pp.445-459
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• 2023

In this study, a cyclic tensile test on a notched butterfly specimen made of woven glass fiber composite was performed on a modified Arcan fixture. During the mechanical test, the sample was monitored with a hybrid stereoscopic system comprised of two visible lights and one infrared camera. The visible light cameras were employed for kinematic measurements using a finite-element-based multiview correlation technique. A semi-hybrid correlation approach was followed, providing Lagrangian temperature fields of the Region of Interest. Due to the complex composite architecture and specimen shape, localized shearing was observed during the tensile loading. Furthermore, asymmetrical damage developed around the notches as revealed by localized strains and thermal hot spots.

• 한국분말재료학회지
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• 제20권6호
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• pp.474-478
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• 2013

The most general photocatalyst, $TiO_2$ and $WO_3$, are acknowledged to be ineffective in range of visible light. Therefore, many efforts have been directed at improving their activity such as: band-gap narrowing with non-metal element doping and making composites with high specific surface area to effectively separate electrons and holes. In this paper, the method was introduced to prepare a photo-active catalyst to visible irradiation by making a mixture with $TiO_2$ and $WO_3$. In the $TiO_2-WO_3$ composite, $WO_3$ absorbs visible light creating excited electrons and holes while some of the excited electrons move to $TiO_2$ and the holes remain in $WO_3$. This charge separation reduces electron-hole recombination resulting in an enhancement of photocatalytic activity. Added Ag plays the role of electron acceptor, retarding the recombination rate of excited electrons and holes. In making a mixture of $TiO_2-WO_3$ composite, the mixing route affects the photocatalytic activity. The planetary ball-mill method is more effective than magnetic stirring route, owing to a more effective dispersion of aggregated powders. The volume ratio of $TiO_2(4)$ and $WO_3(6)$ shows the most effective photocatalytic activity in the range of visible light in the view point of effective separation of electrons and holes.

• Current Optics and Photonics
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• 제1권4호
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• pp.364-371
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• 2017

Compared to one made of glass, an aluminum mirror features light weight, compact design, low cost, and quick manufacturing. Reflective mirrors and supporting structures can be made from the same material, to improve the athermal performance of the system. With the rapid development of ultraprecise machining technologies, the field of applications for aluminum mirrors has been developed rapidly. However, most of them are rotationally symmetric in shape, and are used for infrared applications. In this paper, the design and manufacture of an off-axis aluminum mirror used for a three-mirror-anastigmat (TMA) optical system at visible wavelengths is presented. An optimized, lightweight design provides a weight reduction of more than 40%, while the surface deformation caused by earth's gravity can meet the required tolerance. The two pieces of an off-axis mirror can be diamond-turned simultaneously in one setup. The centrifugal deformation of the off-axis mirror during single-point diamond turning (SPDT) is simulated through the finite-element method (FEM). The techniques used to overcome centrifugal deformation are thoroughly described in this paper, and the surface error is reduced to about 1% of the original value. After post-polishing, the form error is $1/30{\lambda}$ RMS and the surface roughness is better than 5 nm Ra, which can meet the requirements for visible-light imaging.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2010년도 춘계학술대회
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• pp.563-565
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• 2010

저전력, 친환경 반도체 소자인 LED는 조명으로서의 역할 뿐만 아니라, 프로세서를 이용한 디지털 제어를 통하여 가시광 통신에도 활용할 수 있다. 가시광 통신(VLC)이란 가시광 대역을 사용하여 형광등이나 LED를 이용한 조명으로 눈이 인식할 수 없는 속도로 점멸시켜 정보를 보내는 통신 기술이다. 여러 분야에 활용이 가능한 가시광 통신은 공사가 진행 중인 도로에서 LED를 이용한 발광형 교통표지판에서 자동차에 정보를 전송하는데 적용할 수 있다. 이에 본 논문에서는 발광형 교통표지판에 가시광통신을 더하여 도로의 상태, 공사구간과 자동차 간의 안전거리 확보와 차선변경에 관한 정보를 제공해 준다. 그리고 안전 서비스를 제공하는 자동차 안전 프로토콜을 설계하고 실험을 통하여 통신 프로토콜을 검증한다.

• 청정기술
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• 제18권4호
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• pp.419-425
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• 2012

본 연구는 황 원소와 질소 원소가 도핑된 이산화티타늄의 특성을 조사하고 8-와트(W) 일반 램프와 가시광선 영역의 발광 다이오드 조사 조건에서 낮은 농도수준의 가스상 이소프로필 알코올(isopropyl alcohol, IPA)의 광촉매적 분해능에 대하여 조사하였다. 또한, 이소프로필 알코올의 광촉매 분해시 발생되는 아세톤의 생성에 대해서도 조사하였다. 황 원소와 질소 원소가 도핑된 이산화티타늄의 표면 조사결과, 두 촉매들은 가시광선 조사(visible light-emitting-diodes, LEDs)에 의해 효율적으로 활성화될 수 있는 것으로 나타났다. 두 촉매 모두에 대하여, 공기 유량이 감소함에 따라 이소프로필 알코올의 제거 효율이 증가하는 것으로 나타났다. 황 도핑 촉매의 경우, 유량이 0.1 L $min^{-1}$일 때 이소프로필 알코올 제거효율이 거의 100%로 나타난 반면에 유량이 2.0 L $min^{-1}$일 때 이소프로필 알코올 제거효율은 39%로 나타났다. 질소 도핑 촉매의 경우에는, 유량이 0.1 L $min^{-1}$일 때 이소프로필 알코올 제거효율이 거의 100%로 나타난 반면에 유량이 2.0 L $min^{-1}$일 때 이소프로필 알코올 제거효율은 90% 이상으로 나타났다. 이소프로필 알코올 제거 효율과는 달리, 유량 감소에 따라 아세톤 생성율은 감소하는 것으로 나타났다. 결과적으로, 아세톤 생성을 최소화하고 이소프로필 알코올 제거 효율을 높이기 위해서는 질소 도핑 촉매를 낮은 유량 조건에서 작동시키는 것이 나은 것으로 나타났다. 또한, 이소프로필 알코올 제거를 위해 가시광선 조사 발광 다이오드보다 8-와트 일반램프가 효율적인 것으로 나타났다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.374.2-374.2
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• 2016

Volatile organic compounds (VOCs) in the atmosphere are harmful materials which influence indoor air environment and human health. Titanium dioxide ($TiO_2$) is photocatalyst extensively used in degradation of organic compound. To improve the photocatalytic activity in the visible light region, doping with non-metals element or loading noble metals on the surface of $TiO_2$ is generally proposed. In this study, N- doped $TiO_2$ having photocatalytic activity in visible light region was attached noble metal such as Pt, Ag, Pd, Au by coupling method. Catalytic activities of Noble metal coupled $N-TiO_2$ powders were evaluated by the improvement of their photocatalytic activities and the degradation of VOC gas. A UV-Vis spectrophotometer was used to measure the diffuse reflectance spectra of coupled $N-TiO_2$ sample. The photocatlytic activities of as prepared samples were characterized by the decoloration of aqueous MB solution under Xenon light source (UV and visible light). To measure of decomposition VOCs, ethylbenzene was selected for target VOC material and the concentration was monitored under UVLED irradiation in a closed chamber system. Adjusting the initial concentration of 10~12 ppm, to evaluate the removal characteristics by using the coupled $N-TiO_2$.

• 한국세라믹학회지
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• 제46권6호
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• pp.621-626
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• 2009

Fe-AC/Ti$O_2$ photocatalysts were prepared by a sol-gel method. The photocatalytic properties of Fe-AC/Ti$O_2$ photocatalysts for the purification of water have been investigated. The samples were characterized by scanning electron microscopy (SEM), specific surface area (BET), X-ray diffraction analysis (XRD), and energy dispersive X-ray spectroscopy (EDX). The photocatalytic activities were evaluated by the photocatalytic oxidation of methylene blue (MB) solution. It was found that the prepared Fe-AC/Ti$O_2$ composites have an excellent photocatalytic under visible light irradiation. A small amount of Fe ions in the AC/Ti$O_2$ composites could obviously enhance their photocatalytic activity. The high activities of the Fe-AC/Ti$O_2$ composites could be attributed to the results of the synergetic effects of the enhancement of the Fe element, the photocatalytic activity of Ti$O_2$, and the adsorption of AC.