SBERT 임베딩을 활용한 행렬 분해 추천 방법론

강우승,이수원,최상민 한국정보기술학회 2023 한국정보기술학회논문지 Vol.21 No.11

본 논문은 SBERT(Sentence-BERT) 임베딩을 MF(Matrix Factorization)모델에 통합한 영화 추천 방식을 제안한다. 전통적으로 MF 기반 추천 방식은 사용자 아이템 상호 작용 데이터에만 의존하기 때문에 영화의 메타데이터(제목, 장르, 개요 등)를 활용하지 않는다. 본 연구에서는 MF에서의 아이템 잠재 벡터의 표현을 SBERT 임베딩으로 대체하여 의미 정보를 효과적으로 활용할 수 있는 방식을 제안한다. 제안 방식에 대한 정확도 검증을 실제 영화 데이터에 대한 실험을 수행하고 SBERT를 활용한 메타데이터 벡터를 MF 방법에 주입한 모델과 전통적인 MF 모델과 비교한다. 그리고 실험 결과 분석을 통해 제안 방식의 우수성을 입증한다. 본 연구는 아이템의 메타데이터를 대상으로 SBERT 임베딩을 활용하여 협업 필터링 기술의 성능을 향상하는데 새로운 가능성을 제시한다. We propose a movie recommendation approach that integrates Sentence-BERT(SBERT) embeddings into Matrix Factorization(MF) models. Conventional MF-based recommender systems rely solely on rating data and do not utilize metadata such as titles, genres, or summaries. In this study, we suggest a method to effectively leverage semantic information by replacing item latent vectors in MF with SBERT embeddings. To validate the accuracy for the proposed approach, experiments are conducted on real movie dataset. We also compare the model incorporating metadata vectors generated by SBERT with conventional MF models. Through the analysis of experimental results, the superiority of the proposed approach is demonstrated. This research introduces new possibilities for enhancing the performance of collaborative filtering techniques using SBERT embeddings for item metadata.

수소 플라즈마 처리된 산화 아연 나노선의 자외선 발광 특성향상

강우승,박성훈,Kang, Wooseung,Park, Sunghoon 한국진공학회 2013 Applied Science and Convergence Technology Vol.22 No.6

ZnO nanowires were synthesized by vapor-liquid-solid (VLS) process using ZnO and graphite powders on the sapphire substrate coated with an Au film as a catalyst. ZnO nanowires had two prominent emission bands; i) near-band edge (NBE) emission band at 380 nm, and ii) a relatively stronger deep level (DL) emission band ($I_{NBE}/I_{DL}$ <1). In order for the ZnO nanowires to be utilized as an effective material for UV emitting devices, the photoluminescence intensity of NBE needs to be improved with the decreased intensity of DL. In the current study, hydrogen plasma treatment was performed to improve the photoluminescence characteristics of ZnO nanowires. With the hydrogen plasma treatment time of more than 120 sec, the extent of performance improvement was gradually decreased. However, the intensity ratio of NBE to DL ($I_{NBE}/I_{DL}$) was significantly improved to about 4 with a relatively short plasma treatment time of 90 sec, suggesting hydrogen plasma treatment is a promising approach to improve the photoluminescence properties of ZnO nanowires. Au 촉매를 코팅한 사파이어 기판 상에서 산화아연과 흑연 분말을 혼합한 분말재료를 이용하여 VLS (vapor-liquid-solid) 법으로 산화아연 반도체 나노선을 합성하였다. 제조된 산화아연 나노선은 380 nm에서 근 자외선 영역의 NBE (near-band edge) 발광과 600 nm 부근의 가시광선 영역에서 넓게 퍼져 발광하는 상대적으로 강한 DL (deep level) 발광이 확인되었다($I_{NBE}/I_{DL}$ <1). 산화아연 나노선을 효율적인 단일 파장 자외선 발광체에 적용될 수 있도록 NBE 발광을 극대화함과 동시에 DL 발광을 억제시키기 위하여 본 실험에서는 합성된 산화아연 나노선에 수소 플라즈마 처리를 하였다. 플라즈마 처리시간이 길어짐에 따라(120초 이상) 발광특성의 향상정도는 점차로 감소하였지만, 수소 플라즈마 처리를 통해 나노선 내부에 존재하는 불순물 제어 등으로 다소 짧은 시간의 플라즈마 처리로(90초 이내) DL발광대비 NBE발광의 세기가 약 4배로 향상됨을 확인 하였다($I_{NBE}/I_{DL}$ ~4).

Decoration of MgO nanowires with Gd2O3 nanoparticles: structure and photoluminescence properties

강우승,나한길,권용중,조홍연,강성용,박재영,이종무,공명호,김현우 한양대학교 세라믹연구소 2015 Journal of Ceramic Processing Research Vol.16 No.4

We decorated coated Gd2O3 nanoparticles on MgO nanowires by means of Gd sputtering and subsequent thermal annealing. The samples were characterized by X-ray diffraction, scanning electron microscope (SEM), and transmission electron microscopy. The surface roughness observed by SEM was revealed to be Gd2O3 nanoparticles in terms of TEM observation. The PL spectra exhibited a 2.9 eV-peak, which originated from the MgO nanowires, and thermal annealing produced green emission at about 2.4 eV, which is directly associated with the Gd2O3 structure. An additional weak peak at 2.0 eV was found to be related to impurities in the Gd2O3 structure.

산소 분위기 열처리에 따른 ZnO 나노선의 상온 영역에서의 수소가스 검출 특성 향상

강우승(Wooseung Kang) 한국표면공학회 2017 한국표면공학회지 Vol.50 No.2

ZnO nanowires were synthesized and annealed at various temperatures of 500-800℃ in oxygen atmosphere to investigate hydrogen gas sensing properties. The diameter and length of the synthesized ZnO nanowires were approximately 50-100 nm and a few 10s μm, respectively. H₂ gas sensing performance of the ZnO nanowires sensor was measured with electrical resistance changes caused by H₂ gas with a concentration of 0.1-2.0%. The response of ZnO nanowires at room temperature to 2.0% H₂ gas is found to be two times enhanced by annealing process in O₂ atmosphere at 800℃. In the current study, the effect of heat treatment in O₂ atmosphere on the gas sensing performance of ZnO nanowires was studied. And the underlying mechanism for the sensing improvement of the ZnO nanowires was also discussed.

Au 나노입자가 코팅된 TiO₂ 나노와이어의 에탄올가스 검출 특성

강우승(Wooseung Kang) 한국표면공학회 2015 한국표면공학회지 Vol.48 No.5

TiO₂ nanowires were synthesized by hydrothermal method for the application to ethanol gas sensor. TiO₂ nanowires were decorated with Au nanoparticles to improve the sensitivity to ethanol gas. Scanning electron microscopy and Transmission electron microscopy revealed that the synthesized nanowires had diameters and lengths of approximately 100 - 200 nm and a few micrometers, respectively. Size of the Au nanoparticles decorated on the TiO₂ nanowires was observed to be in the range of 10 - 20 nm. X-ray diffraction confirmed that the decorated nanowires were composed of anatase-, rutile-TiO₂, and Au. The sensitivities of TiO₂ nanowires sensors decorated with Au were approximately 1.1 - 3.65 times as high as those of as-synthesized TiO₂ sensors for the ethanol concentration of 5 - 100 ppm at 200℃. The mechanism of the improved ethanol gas sensing of the TiO₂ nanowires decorated with Au nanoparticles is discussed.

상온에서 UV 활성화된 ZnS 나노와이어의 NO₂ 가스 검출 특성

강우승(Wooseung Kang) 한국표면공학회 2014 한국표면공학회지 Vol.47 No.6

ZnS nanowires were synthesized in order to investigate NO₂ gas sensing properties. They were grown on the sapphire substrate using ZnS powders. SEM (scanning electron microscopy) showed the diameter and length of the ZnS nanowires were approximately in the range of 50 - 100 nm and a few 10s μm, respectively. They were also found to be composed of Wurtzite- structured single crystals from TEM (transmission electron microscopy) analysis. NO₂ gas sensing performance of the ZnS nanowire was measured with electrical resistance changes caused by NO₂ gas with a concentration of 1-5ppm. The sensor was UV treated with an intensity of 1.2 mW/cm2 to facilitate charge carrier transfer. The responses of the ZnS nanowires to the NO₂ gas at room temperature, treated with UV of two different wavelengths of 365 nm and 254 nm, are measured to be 124.53 - 206.87 % and 233.97 - 554.83%, respectively. In the current work, the effect of UV treatment on the gas sensing performance of the ZnS nanowires was studied. And the underlying mechanism for the electrical resistance changes of the ZnS nanowires by NO₂ gas was also discussed.

산화코발트 나노입자의 첨가에 따른 산화니켈 기반 반도체 산화물의 에탄올 가스 검출 특성 향상

강우승(Wooseung Kang) 한국표면공학회 2016 한국표면공학회지 Vol.49 No.4

NiO nanoparticles were synthesized by hydrothermal method for the application to ethanol gas sensor. They were composited with Co₃O₄ nanoparticles to improve the sensitivity to ethanol gas. Scanning electron microscopy revealed that the synthesized NiO nanoparticles were plate-shaped with the approximate size and thickness of 60 - 120 nm and 20 nm, respectively. On the other hand, Co₃O₄ nanoparticles mixed with NiO was observed to be spherical with the size range of 30 - 50 nm. The sensitivities of NiO sensors composited with Co₃O₄ nanoparticles at an optimal ratio of 8 : 2 were enhanced to approximately 1.44 - 1.79 times as high as those of as-synthesized NiO sensors for the ethanol concentration of 10 - 200 ppm at 200℃. The mechanism of the improved ethanol gas sensing of the NiO sensors composited with Co₃O₄ nanoparticles was discussed.

Au 촉매금속이 첨가된 NiO 나노섬유의 가스 검출 특성

강우승(Wooseung Kang) 한국표면공학회 2017 한국표면공학회지 Vol.50 No.4

NiO nanofibers with Au nanoparticles were synthesized by sol-gel and electrospinning techniques, in which the reduction process by ultraviolet exposure is included for the growth of Au nanoparticles in the electrospinning solution. FE-SEM(Field Emission Scanning Electron Microscopy), TEM(Transmission Electron Microscopy) revealed that the synthesized nanofibers had the diameter of approximately 200 nm. X-ray diffraction showed the successful formation of Au-decorated NiO nanofibers. Gas sensing tests of Au-decorated NiO nanofibers were performed using reducing gases of CO, and C6H6, C7H8, C₂H5OH. Compared to assynthesized NiO nanofibers, the response of Au-loaded NiO nanofibers to CO gas was found to be about 3.4 times increased. On the other hand, the response increases were only 1.1-1.3 times for C6H6, C7H8, and C₂H5OH.

산화아연 나노튜브의 벽 두께에 따른 에탄올 가스 검출특성

강우승(Wooseung Kang) 한국표면공학회 2017 한국표면공학회지 Vol.50 No.3

ZnO nanotubes were synthesized to investigate the effect of wall thickness on the ethanol gas sensing performance. The wall thickness of the nanotubes was varied from approximately 20 to 60 nm. Transmission electron microscopy, X-ray diffraction and SAED (Selected Area Electron Beam Diffraction) analyses showed that the synthesized nanotubes were polycrystalline structured ZnO with the diameter of approximately 200-300nm. The ZnO nanotubes sensor with an optimum wall thickness of 51.8nm showed approximately 8 times higher response, compared to that with 21.14nm wall thick nanotubes, to the ethanol concentration of 500 ppm at the temperature of 300℃. The wall thickness of 51.8nm was found to be a little larger than 46nm, which was theoretically derived Debye length. Along with the study of the wall thickness effect on the performance of the sensors, the mechanisms of gas sensing of the polycrystalline ZnO nanotubes are also discussed.

탄화규소/7091알루미늄 복합재료의 부식거동

강우승 ( Woo Seung Kang ) 한국부식방식학회(구 한국부식학회) 2012 Corrosion Science and Technology Vol.11 No.4

The effects of volume fraction (15-30%) of SiC particulate reinforcements on the corrosion behavior of SiCp/7091 Al conposites in the 3.5% NaCl solution were studied by electrochemical techniques and scanning electron microscopy. The results showed that the amount of SiC particulate reinforcements did not cause much difference in the corrosion behavior of SiCp/7091 Al composites but the corrosion rate was proportional to the amount of SiCp reinforcement, And numerous pits and severe dissolution of the matrix was observed probably due to the discontinuities and galvanic effects between Al matrix and SiC reinforcements.