• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.408-408
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• 2014

Graphene has received attention with its high electron mobility and visual transparency as a promising material for optoelectronic and photonic applications. Combination of graphene and conducting nanostructures i.e. plasmonic structures has recently been researched for enhancing light-matter interaction and overcoming diffraction limit of light. Here we show enhanced photodetection of incoherent visible light with graphene-mediated plasmonics. Gold nanoparticles fabricated by focused ion beam was used as an active element of photodetection and graphene was utilized as an interfacing material between nanostructures and electrodes. Hot electrons generated upon plasmon decay within nanoparticles pass over the potential barrier between nanostructure and graphene and give rise to a photocurrent with built-in electric field. We report 76.7% enhancement of photocurrent under resonant irradiation of fiber-coupled halogen lamp compared to the case without light illumination. We showed wavelength-dependent current response arisen from plasmonic nanostructure, providing a good agreement with theoretical calculation.

• 소성∙가공
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• 제25권3호
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• pp.176-181
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• 2016

The exhaust tail pipe is the only visible part of the exhaust system on a vehicle. The conventional way to make the tail pipe is welding after stamping. There are various problems that occur during the stamping of stainless steel sheets such as scratching and local fracture. Problems during welding can also occur due to poor weldability. Tube hydroforming can be a solution, which eliminates these problems. The current study deals with the development of tube hydroforming for a vehicle tail pipe using finite element analysis for a free-feeding method. The current study focuses on the development of a proper load path for the tail pipe hydroforming and how bending influences the subsequent processing steps. The FE analysis results were compared with experimental results. This study shows the importance of bending and the necessity of considering bending when performing a tube hydroforming analysis.

• 한국인쇄학회지
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• 제29권3호
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• pp.17-30
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• 2011

The polarizer is an important optical element used in a variety of applications. Nano-wire grid polarizers in the form of sub-wavelength metallic gratings are an attractive alternative to conventional polarizers, because they provide high extinction ratio. This study has been carried out to fabrication of the 17inch area size nano-wire grid polarizer(NWGP) The master for NWGPs with a pitch of 200nm and the area size $730mm{\times}450mm$ were fabricated using laser interference lithography and aluminum sputtering and wet etching. And The NWGP fabrication process was using by the Roll to-Roll UV imprinting and was applied to flexible PET film. The results were a transmission of light (Tp) 46.7%, reflectance (Rs) 40.1% and Extinction ratio of above 16 for the visible light range.

• 방재기술
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• 통권29호
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• pp.39-45
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• 2000

All objects emit thermal radiation and this radiation is the basis of the techniques used to detect flames. The usual phenomena occurring in the initial stage of a fire are generally invisible products of a combustion and visible smoke. Liquid or gaseous materials do not undergo a smoldering stage such fires develop very rapidly. Also, the heat generated by the initial flames is usually not sufficient to active a heat detector. In this case the most effective criterion for automatic fire detection is the flame. In fire regulation of korea, the compulsory standard provided that a flame detector shall be installed a place of the attachment hight of detector is higher than 20 m, chemical plants, hangar, refinery, etc.. The result of the research and development are discriminated between a flame and other radiant emitters, developed PZT pyroelectric element is based on the use of photo-voltanic cell, developed IR band-pass filter that only allow a 4.3 radiation wavelength to reach the sensors and developed IR flame detector.

• 전기학회논문지P
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• 제60권2호
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• pp.82-90
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• 2011

The small precision spindle motors in the high value-added products including the visible home appliances such as DLP projector require not only the energy conversion devices but also high efficiency, low vibration and sound operation. However, the spindle motors using the conventional ball bearing and sintered porous metal bearing have following problems, respectively: the vibration by the irregularity of balls and the short motor life cycle by the ball's abrasion and higher sound noises by dry contact between shaft and sleeve. In this paper, it is proposed that the spindle motor with a fluid dynamic bearing is suitable for the motor to drive the color wheel of the DLP(digital lightening processor) in the visible home appliances. The proposed spindle motor is composed of the fluid dynamic bearing with both the radial force and the thrust force. The fluid dynamic bearing is solved by the finite element analysis of the mechanical field with the Reynolds equations. The magnetic part of spindle motor, which is a type of Brushless DC Motor, is designed by the electro-magnetic field analysis coupled with the Maxwell equation. And the load capacity and the friction loss of fluid dynamic bearing are analyzed to bearing clearance variation by the fabrication error in designed motor. The design of the proposed motor is implemented by the load torque caused by the eccentricity and the unbalance of the fluid dynamic bearing when the motors are fabricated in error. The prototype of the motor with the fluid dynamic bearing is manufactured, and experiment results show the vibration, sound, and phase current at no load and color wheel load of the motors in comparison. The high performance characteristics with the low vibration, the low acoustic noise and the optimal mechanical structure are verified by the experimental results.

• 한국환경과학회지
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• 제18권11호
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• pp.1215-1224
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• 2009

This study evaluated the applicability of visible-light-driven N- and S-doped titanium dioxide($TiO_2$) for the control of low-level dimethyl sulfide(DMS) and dimethyl disulfide(DMDS). In addition, a photocatalytic unit(PU)-adsorption hybrid was evaluated in order to examine the removal of DMS and DMDS which exited the PU and a gaseous photocatalytic byproduct($SO_2$) which was generated during the photocatalytic processes. Fourier-Tranform-Infrared(FTIR) spectrum exhibited different surface characteristics among the three-types of catalysts. For the N- and S-doped $TiO_2$ powders, a shift of the absorbance spectrum towards the visible-light region was observed. The absorption edge for both the N- and S-doped $TiO_2$ was shifted to $\lambda$ 720 nm. The N-doped $TiO_2$ was superior to the S-doped $TiO_2$ in regards to DMS degradation. Under low input concentration(IC) conditions(0.039 and 0.027 ppm for DMS and DMDS, respectively), the N-doped $TiO_2$ revealed a high DMS removal efficiency(above 95%), but a gradual decreasing removal efficiency under high IC conditions(7.8 and 5.4 ppm for DMS and DMDS, respectively). Although the hybrid system exhibited a superior characteristic to PU alone regarding the removal efficiencies of both DMS and DMDS, this capability decreased during the course of a photocatalytic process under the high IC conditions. The present study identified the generation of sulfate ion on the catalyst surface and sulfur dioxide(maximum concentrations of 0.0019 and 0.0074 ppm for the photocatalytic processes of DMS and DMDS, respectively) in effluent gas of PU. However, this generation of $TiO_2$ would be an insignificant addition to indoor air quality levels.

• 한국조경학회지
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• 제29권2호
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• pp.1-13
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• 2001

Beginning in the Wei-Chin and Liu Ch´ao era(AD. 220-589), an awareness of natural beauty emerged as the major interest of scholars which created such a social atmosphere that served as the foundation of prosperous Chinese art. During the T´ang period, the desire to achieve natural beauty began to dominate every field of art including gardening. This study covers the T´ang period when scholars began to be conscious of aesthetics. The main objective of this study is to examine the significance of natural beauty as interpreted by Wangwei, an artist representative of the period, and of Wangchuan Villa in relation to aspects of garden theory. This study is mainly based on Wangwei´s anthology, landscape painting describing Wangchuan Villa, and historical records related to the Villa. The summary of conclusions of this study is as follows: 1) Wangwei´s concept of natural beauty is a combination of objective natural beauty and pastoral beauty, which stresses the essential beauty of nature. Moreover, he considered nature as a religious Utopia. 2)Wangchuan Villa, where Wangwei stayed until his death, was a place of seclusion representing his idea of natural beauty. There, he was able to realize the paradise of Buddhism full of zen aspirations. 3)From the perspective of garden theory, Wangchuan Villa can be classified as a suburb villa in terms of location, as a landscape garden in terms of elements, and as a villa based on a typical private land system in terms of forms. In addition, it may be considered as a garden that laid the foundation to realize a field of non-visible image and non-visible landscape, which is fundamental element of scholarly garden design.

• 한국항공우주학회지
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• 제49권7호
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• pp.549-555
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• 2021

원공이 있는 복합재 적층판의 강도는 복합재 항공기기 설계 시 충격하중이 가해지는 부위의 설계 허용치로 사용된다. 일반적으로 BVID (Barely Visible Impact Damage)에 의한 강도저하는 24.0 mm 폭의 시편에 6.0 mm 지름의 원공이 있는 시편의 강도로 가정한다. 본 연구에서는 원공이 있는 복합재 적층판의 강도에 적층각이 미치는 영향을 조사하기 위해 잔류강도 시험을 수행하였다. 원공이 있는 적층판의 강도를 예측하기 위해 특성길이를 이용한 점응력 파손기준을 사용하였고, 이론해를 검증하기 위하여 유한요소해석을 수행하였다. 실험결과로부터 특성길이는 0°, ±45°와 90°층의 비율과 관련이 있음을 보였다. 또한 회귀분석을 통하여 임의의 적층 패턴에 대한 특성길이와 원공이 없는 시편의 강도를 결정하였다.

• 디자인학연구
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• 제17권2호
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• pp.15-22
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• 2004

현재의 복잡한 시각문화는 디지털 기술의 발전에 따라 이미지, 그래픽, 사진, 영화, 텔레비전 등의 영상에 따른 광범위하게 확대된 시각 세계이며, 사운드와 문자까지를 삽입하여 의미 내용을 전달하기 때문에 일반적인 언어나 문자를 넘어 정보를 전달하고 커뮤니케이션 하는 멀티미디어 적 성격을 갖는다고 할 수 있다. 이 때의 다양한 이미지들을 보는 시각은 언어와 불가분 하게 연결되며, 이미지와 시각의 상상적 질서가 문화적, 역사적으로 특정한 방식으로 구성된다고 할 수 있다. 언어는 그 시대의 사회, 문화, 역사에 따라 다르기 때문에 시각적 경험이 부분적으로라도 언어적으로 매개된다면 시각적 경험이 보편성을 갖기는 어려운 것이다. 따라서 시각 체계들간의 사회 문화적 차이를 형성하고 규정하는데 에는 언어적 질서의 역할이 크다고 할 수 있다. 이러한 시각 언어와 함께 역사적으로 다양한 시각적, 광학적 장치들 또한 많은 영향을 끼쳤는데 이 시각적 테크놀로지들은 가시적 세계 속에서 주체와 주체의 가시적인 대상들과 관계 맺는 방식을 결정하는 구체적인 물질적 실천체인 것이다. 시각언어는 이렇게 이미지들의 표상이라는 차원과 일련의 역사적인 물질적, 제도적 실천들로의 시각테크놀로지라는 차원이 결합된 것이며, 이것이 하나의 시각체제 내에서의 대상 세계를 보는 사회적인 시각 양식을 결정하였다. 따라서 본 연구는 미디어테크놀로지의 발전에 따라 변화된 개념이나 특성들에 따라 시각언어를 사회적이고 역사적인 성격을 가진 것으로 이해하고 표상의 차원으로서의 시각언어와 제도적이고 물질적인 실천으로서의 시각 테크놀로지의 차원에서 설명했다. 결국 시각 테크놀로지는 그 기능과 시각 양식에 대한 영향은 그것의 기술적 요소만으로는 설명할 수 없으며, 그것과 결부된 담론적 실천들과 물질적 제도적 실천과 분리될 수 없다. 특정 테크놀로지의 기술적 요소가 담고 있는 가능성 역시 그대로 실현되는 것이 아니라 항상 사회적 맥락에 의해 그 효과가 매개되고 제약되면서 실현된다고 할 수 있다.

• 대한환경공학회지
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• 제31권11호
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• pp.965-974
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• 2009

본 연구는 가시광선 조건에서 질소 및 황 도핑 $TiO_2$를 활용하여 악취유발 황화유기화합물질의 분해능을 평가하고, 광촉매 분해시 발생하는 촉매 비활성화와 비활성화된 촉매의 재생에 대해 조사하였다. 적외선 분광법을 이용하여 촉매 표면의 특성을 조사하였다. 가시광선을 이용한 광촉매 기술이 낮은 농도의 황화 이메틸(0.039 ppm)과 이황화 이메틸 (0.027 ppm)은 97% 이상의 높은 효율로 처리할 수 있으나, 촉매 비활성으로 인해 높은 농도(황화 이메틸, 7.8 ppm 및 이황화 이메틸, 5.4 ppm)에 대해서는 광촉매 공정 시간 5시간만에 처리 효율이 황화 이메틸은 84% 그리고 이황화 이메틸은 23%까지 매우 낮게 나타났다. 황화 이메틸에 비하여 황 원소가 하나 더 결합된 이황화 이메틸의 광촉매 분해시 촉매가 빠르게 비활성화되었다. 높은 유입 농도 조건에서 이황화 이메틸 또는 황화 이메틸의 광촉매 반응기의 출구 농도가 유 입농도와 비슷하거나, $CO_2$의 생성률이 제로에 가깝거나, FTIR 스펙트럼 상에서 촉매 표면의 비활성을 유발하는 황 이온 화합물의 피크들이 강하게 나타나, 촉매의 비활성화를 확인하였다. 광촉매 반응기의 유출구에서의 최대 $CO_2$ 농도인 8 ppm에 대해서 황화 이메틸의 광물화 효율을 계산한 결과 144%로서 100%를 초과한 것으로 나타났다. 건조-공기 및 습윤-공기 재생 방법에 비해 고온 소성에 의한 촉매의 재생효율이 높게(이황화 이메틸, 53% 그리고 황화 이메틸, 58%) 나타났으나, 이 또한 촉매 비활성을 유발시키는 황 이온 화합물과 같은 부산물들을 완전히 제거되지는 못하는 것으로 확인되었다.