• 대한화학회지
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• 제50권6호
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• pp.429-439
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• 2006

분광법의 하나인 합 진동수 발생 진동 분광법 (SFG-VS, sum frequency generation vibrational spectroscopy)은 표면의 분자에 대하여 선택적으로 높은 감도의 진동 스펙트럼을 제공한다. 이로 인해 SFG-VS 는 다양한 표면 연구에 이용되고 있다. 본 총설에서는 SFG-VS의 연구 대상, 실험 방법, 이론적 배경, 상업적 분광기로서의 가능성 등에 관하여 살펴보았다.

• Current Optics and Photonics
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• 제2권4호
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• pp.361-367
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• 2018

Ultrafast deep-ultraviolet (DUV) pulse generation from the subwavelength aperture of a plasmonic waveguide was investigated. The plasmonic nanofocusing of near-infrared (NIR) pulses was exploited to enhance DUV photoemission of surface third harmonic generation (STHG) at the amorphous $SiO_2$ dielectric. The generated DUV pulses which are successfully made from a nano-aperture using 10 fs NIR pulses have a spectral bandwidth of 13 nm at a carrier wavelength of 266 nm. This method is applicable for tip-based ultrafast UV laser spectroscopy of nanostructures or biomolecules

• International journal of advanced smart convergence
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• 제12권3호
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• pp.19-24
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• 2023

Recently, fifth generation (5G) networks are being deployed in phases all over the world, the paradigm has shifted to developing the next generation wireless technologies, which have grown exponentially in last few decades, wireless networks are promising for the demand to enormous connections. Non-orthogonal multiple access (NOMA) and intelligent reflecting surface (IRS) are considered as the key technoloies for next-generation beyond 5G (B5G) and sixth generation (6G) networks, in which IRS can play an important advance in the wireless propagation environment, and NOMA can effectively increase massive connectivity to improve user fairness. In this paper, we analyze a performance on the strongest channel user in terms of achievable data rates numerically. Then, with the achievable data rates, the signal-to-noise ratio (SNR) gain is calculated for the IRS-NOMA network over the conventional NOMA network. As a consequence, IRS-NOMA schemes have been considered as some key technologies.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.319-319
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• 2011

Hydrolysis of sodium borohydride provides a safe and clean approach to hydrogen generation. Having the proper catalytic support for controlling this reaction is therefore a valuable technology. Here we demonstrate the capability of hydroxyapatite as a novel catalytic support material for hydrogen generation. Aside from being inexpensive and durable, we reveal that Ru ion exchange on the HAP surface provides a highly active support for sodium borohydride hydrolysis, exemplifying a high total turnover number of nearly 24,000 mol $H_2$/ mol Ru. Moreover, we observe that the RuHAP support exhibits a high catalytic lifetime of approximately one month upon repeated exposure to $NaBH_4$ solutions. In addition to examining surface area effects, we also identified the role of complex surface morphology in enhancing hydrolysis by the catalytic transition metal covered surface. Particularly, we found that a polycrystalline RuHAP catalytic support exhibits shorter induction times for the initial bubble formation as well as increased hydrogen generation rates as compared to a single crystal supports. The independent factor of a complex surface morphology is believed to provide enhanced sites for gas release during the initial stages of the reaction. By demonstrating the ability to shorten induction time and enhance catalytic activity through changes in surface morphology and Ru content, we find it feasible to further explore this catalyst support in the construction of a practical hydrogen generator.

• 조명전기설비학회논문지
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• 제17권3호
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• pp.56-63
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• 2003

수표면을 전극으로 사용한 부성방전형 오존발생기를 제안하고 수표면의 바로 아래에 유전체구를 설치함으로써 오존발생특성을 향상시킬 수 있었다. 이때, 서로 다른 유전율을 갖는 유전체구를 사용하여 수표면에 형성되는 방전조건을 변화시키고자 하였다. 전류-전압특성과 오존발생특성을 조사하였고 방전현상을 관찰하기 위해 유리구슬 유전체를 사용한 경우의 방전모양을 사진 촬영하여 분석하였다. 수표면에 발생되는 수돌기의 크기는 교락현상(breakdown)의 원인이 될 수 있고 따라서 오존발생량을 감소시킨다. 본 연구에서는 수표면 바로 아래에 서로 다른 유전율을 갖는 유전체구를 투입함으로써 과도한 크기의 수돌기(Tayler cone)의 놀이를 제한할 수 있었다. 이에 따라, 유전체구를 사용하지 않은 경우보다 많은 양의 오존을 발생시킬 수 있었다. 수중에 투입되는 유전체의 유전율이 증가함에 따라 방전이 시작되는 전압을 앞당길 수 있었고 강유전체구를 사용한 경우 최대 110[ppmv]의 오존발생량을 얻을 수 있었다.

• 한국CDE학회논문집
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• 제9권1호
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• pp.1-10
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• 2004

In the process of finite element analysis, mesh generation is tedious job which consumes tremendous time. Therefore, the automation of well shaped mesh generation from the minimal boundary input data is desirable to improve reliability and accuracy of the analysis and also to reduce the process time of the entire design process. The automation of triangular mesh generation has been relatively well treated due to its robustness and ease of handling when compared to rectangular element mesh generation. In this study, the offset method developed previously for generating plane rectangular element mesh has been corrected and modified to generate triangular element mesh on the B-spline surface having arbitrary holes. The result shows that the generated triangular mesh has the average aspect ratio over 0.9. The designed arbitrary surface shape has been interactively constructed by non-uniform B-spline theory for triangular mesh generation.

• 한국정밀공학회지
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• 제28권6호
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• pp.724-731
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• 2011

Dew generation on an outer surface is considered as an important issue to be settled in the field of home appliances. In the case of a refrigerator that is subject to the dew generation problem on the surface of an outer-door of refrigeration thread, and so as to solve this problem, the electric heater is generally used for drying the dew. However, the heater inevitably requires electrical power consumption that is one of critical issues on the refrigerator. In this study, to prevent dew generation without the heater, a method of using induced heat from room temperature was proposed. In edge sides of a door, high conductive plates are installed and received the heat from outside that is relatively high temperature, and the heat is transferred onto dew generation region. Using prototypes, performance test was conducted under a certain temperature and humidity condition. The experimental results show that the surface temperature on the dew generation region was increased about $0.3{\sim}2.5^{\circ}C$ without use of any heater.

• 한국전기전자재료학회논문지
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• 제13권2호
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• pp.151-156
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• 2000

Effects of alignment layers on pretilt nagle generation and electrical characteristics in nematic liquid crystal(NLC) by using photo-alignment techniques on polyimide PI) surface with side chain were studied. The generated pretilt angle of the NLC on rubbed PI surface with 1-layer is almost the same as that with the 2-layers. However, the generated pretilt angle of the NLC on photo-induced PI surface with 2-layers is larger than that with the 1-layer. The different mechanism of pretilt generation in NLC was observed on the rubbing and photo-alignment method. Therefore, the pretilt angle of the NLC on photo-induced PI surface is attributed to surface roughness due to photo-dissociation on the polymer with UV light irradiation on PI surface. We observed the same characteristics of voltage-transmittance (V-T) and response time for 1- and 2-layers on PI surface. Consequently, we sugest that the VHR of photo-aligned TN-LCD is higher than that of the rubbing-aligned TN-LCD.

• International Journal of CAD/CAM
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• 제4권1호
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• pp.47-53
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• 2004

The subdivision surface is the limit of recursively refined polyhedral mesh. It is quite intuitive that the multi-resolution feature can be utilized to simplify generation of NC (Numerical Control) tool paths for rough machining. In this paper, a new method of parallel NC tool path generation for subdivision surfaces is presented. The basic idea of the method includes two steps: first, extending G-Buffer to a strip buffer (called S-Buffer) by dividing the working area into strips to generate NC tool paths for objects of large size; second, generating NC tool paths by parallel implementation of S-Buffer based on MPI (Message Passing Interface). Moreover, the recursion depth of the surface can be estimated for a user-specified error tolerance, so we substitute the polyhedral mesh for the limit surface during rough machining. Furthermore, we exploit the locality of S-Buffer and develop a dynamic division and load-balanced strategy to effectively parallelize S-Buffer.

• 한국전기전자재료학회논문지
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• 제14권2호
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• pp.130-132
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• 2001

The mechanisms of pretilt angle generation in nematic liquid crystal (NLC) with negative dielectric anisotropy on a rubbed polyimide (PI) surface for homeotropic alignment were studied. The pretilt angle of negative type NLC was smaller than that of the positive type NLC for all rubbing strength regions on the rubbed PI surface. The pretilt angle generated in NLC does not attributable to steric interaction between the fluorine moiety of NLC and the polymer surface on the rubbed PI surface. Consequently, the mechanism of the pretilt angle generation for homeotropic alignment is different from the one for homogeneous alignment.