• Journal of Welding and Joining
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• 제18권3호
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• pp.60-67
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• 2000

In this study, we constructed a preview-sensing visual sensor system for weld seam tracking in GMA welding. The visual sensor consists of a CCD camera, a diode laser system with a cylindrical lens and a band-pass-filter to overcome the degrading of image due to spatters and/or arc light. To obtain weld joint position and edge points accurately from the captured image, we compared Hough transform method with central difference method. As a result, we present Hough transform method can more accurately extract the points and it can be applied to real time weld seam tracking. Image processing is carried out to extract straight lines that express laser stripe. After extracting the lines, weld joint position and edge points is determined by intersecting points of the lines. Although a spatter trace is in the image, it is possible to recognize the position of weld joint. Weld seam tracking was precisely implemented with adopting Hough transform method, and it is possible to track the weld seam in the case of offset angle is in the region of $\pm15^{\circ}$.

• 한국정밀공학회지
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• 제22권11호
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• pp.82-90
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• 2005

Recently, the in-line vision inspection has become the subject of growing research area in the visual control systems and robotic intelligent fields that are required exact three-dimensional pose. The objective of this article is to study the pc based in line visual inspection with the hand-eye structure. This paper suggests three dimensional structured light measuring principle and design method of laser sensor header. The hand-eye laser sensor have been studied for a long time. However, it is very difficult to perform kinematical analysis between laser sensor and robot because the complicated mathematical process are needed for the real environments. In this problem, this paper will propose auto-calibration concept. The detail process of this methodology will be described. A new thinning algorithm and constrained hough transform method is also explained in this paper. Consequently, the developed in-line inspection module demonstrate the successful operation with hole, gap, width or V edge.

• 한국재료학회지
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• 제32권11호
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• pp.458-465
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• 2022

Interest in the use of semiconductor-based photocatalyst materials for the degradation of organic pollutants in a liquid phase has grown, due to their excellent performance and response to the light source. Herein, we fabricated a NiO-SiC-TiO₂ ternary structured photocatalyst which had reduced bandgap energy, with strong activation under UV-light irradiation. The synthesized samples were examined using XRD, SEM, EDX, TEM, DRS, EIS techniques and photocurrent measurement. The results confirmed that the two types of metal oxides were well bonded to the SiC fiber surface. The junction of the new photocatalyst exhibited a large number of photoexcited electrons and holes. The holes tended to oxidize the water and form a hydroxyl radical, which promoted the decomposition of methylene blue. The close contact between the 2D SiC fiber and metal oxide semiconductors expanded the scope of absorption wavelength, and enhanced the usability of the ternary photocatalyst for the degradation of methylene blue. Among three synthesized samples, the NiO-SiC-TiO₂ showed the best photocatalytic effect, and was considered to have excellent photoelectron transfer due to the synergy effect between the metal oxide and SiC.

• International Journal of Korean Welding Society
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• 제1권2호
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• pp.23-29
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• 2001

In this study, a preview-sensing visual sensor system is constructed far weld seam tracking in GMA welding. The visual sensor system consists of a CCD camera, a diode laser system with a cylindrical lens, and a band-pass-filter to overcome the degrading of image due to spatters and/or arc light. Among the image processing methods, Hough transform method is compared with the central difference method from a viewpoint of the capability for extracting the accurate feature position. As a result, it was revealed that Hough transform method can more accurately extract the feature positions and it can be applied to real time weld seam tracking. Image processing which includes Hough transform method is carried out to extract straight lines that express laser stripe. After extracting the lines, weld joint position and edge points are determined by intersecting the lines. Even though the image includes a spatter trace on it, it is possible to recognize the position of weld joint. Weld seam tracking was precisely implemented with adopting Hough transform method, and it is possible to track the weld seam in the case of offset angle is in the region of $\pm$ $15^{\circ}$.

• 마이크로전자및패키징학회지
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• 제27권3호
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• pp.69-72
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• 2020

본 연구에서는 SnO₂ nanoparticles (NPs) 위에 TiO₂ NPs를 코팅하여 Quantum Dots Light Emitting Diodes (QLEDs)를 제작하였다. TiO₂ NPs는 SnO₂ NPs보다 conduction band minimum (CBM) 준위가 낮다. 따라서 SnO₂ 층과 발광층의 CBM 준위 사이에 위치해 에너지 장벽을 감소시키고, 전자의 이동을 원활하게 할 것으로 예상하였다. QLEDs는 inverted 구조로 제작되었으며, SnO₂ 단일층을 사용한 경우보다 발광 특성이 향상된 것을 확인하였다. 이중 전자수송층을 적용한 이번 연구를 통해 SnO₂를 QLEDs에 전자수송층으로 적용할 수 있을 것으로 기대한다.

• KSBB Journal
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• 제15권1호
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• pp.14-21
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• 2000

본 연구는 조류의 고농도 배양을 통하여 축산폐수로부터 질소, 인등의 영양염류를 효과적으로 제거하여 환경오염을 감소시키는 것을 목적으로 한다. 이를 위하여 조류성장의 환경적 요소인 질소/인 농도비에 대한 질소와 인의 제거효율 분석 실험을 통하여 질적 질소/인 농도비를 결정하였다. 고농도 조류 배양을 위한 광도의 균일한 공급을 위하여 광섬유를 이용한 광생물반응기를 공정에 적용하였다. 제안된 광섬유를 이용한 광생물반응기는 광원으로부터 반응기 전체로 효과적인 광전달을 수행하는 것을 확인하였다. 조류 배양에서 조류의 성장과 질소, 인의 제거를 표현하기 위해서 구조적 속도식 모델을 제시하였다. 유전알고리즘을 이용한 자기구성퍼지 제어기를 구성하여 반연속식 폐수처리공정의 제어를 수행하였다. 구성된 퍼지 제어기는 폐수의 유입량 조절을 통하여 질소의 농도를 주어진 설정치로 유지되도록 운전하였다. 실험 결과에 의해 자기구성 퍼지 제어기는 원하는 질소의 농도를 잘 유지함은 물론 조류의 성장을 증진시킴을 알 수 있었다.

• 한국재료학회지
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• 제31권6호
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• pp.353-366
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• 2021

In this study, photocatalytic degradation of ammonia in petrochemical wastewater is investigated by solar light photocatalysis. Two-dimensional ultra-thin atomic layer structured MoS₂ are synthesized via a simple hydrothermal method. We examine all prepared samples by means of physical techniques, such as SEM-EDX, HRTEM, FT-IR, BET, XRD, XPS, DRS and PL. And, we use fullerene modified MoS₂ nanosheets to enhance the activity of photochemically generated oxygen (PGO) species. Surface area and pore volumes of the MoS₂-fullerene samples significantly increase due to the existence of MoS₂. And, PGO oxidation of MB, TBA and TMST, causing its concentration in aqueous solution to decrease, is confirmed by the results of PL. The generation of reactive oxygen species is detected through the oxidation reaction from 1,5-diphenyl carbazide (DPCI) to 1,5-diphenyl carbazone (DPCO). It is found that the photocurrent density and the PGO effect increase in the case with modified fullerene. The experimental results show that this heterogeneous catalyst has a degradation of 88.43% achieved through visible light irradiation. The product for the degradation of NH₃ is identified as N₂, but not NO^2- or NO^3-.

• 한국초등과학교육학회지:초등과학교육
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• 제41권2호
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• pp.283-294
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• 2022

초등학교 과학 교육과정에서 빛 개념은 중요하게 다루어지나 학생과 교사가 이해에 어려움을 갖는다는 보고가 많다. 내용 자체의 난이도 때문인지, 제시방법, 구성, 표현 등이 어려움을 유발하는 것인지 분석할 필요가 있다. 2015 초등 과학과 교육과정과 미국, 중국, 일본의 초등 교육과정과 교과서에서 나타난 빛 관련 주요개념, 빛 단원 내용구성, 사용한 소재와 광원, 광학기구를 비교하였다. 분석 결과, 네 나라의 교육과정에서 빛에 대한 주요개념의 포함 여부와 다루는 시점은 나라마다 차이가 있었다. 특히 우리나라 교육과정은 광원, 시각 개념을 도입하지 않은데 비해 볼록 렌즈에 의한 굴절 개념은 다룬다는 점에서 차이가 나타났다. 내용구성과 흐름에서도 나라별로 차이가 있었다. 한국 교육과정은 핵심 아이디어나 관점을 따라 내용이 구성되기보다 개념별로 분절적으로 제시되어 있고 개념 간 연계성이 불분명하였다. 주요개념을 설명하기 위한 소재와 광원, 광학기구에서도 국가별 차이점이 나타났는데, 빛의 이용이라는 주제에 대해 미국 교육과정은 목적을 제공하고 빛을 이용하여 이를 달성하는 방식, 중국과 한국은 개념이해를 심화하기 위한 소재를 사용하는 방식으로 나뉘었다. 이러한 분석 결과를 바탕으로 한 우리나라의 초등학교 과학 교육과정 빛 영역에 관한 시사점은 다음과 같이 도출하였다. 첫째, 개념을 순차적이고 단계적으로 도입하고, 개념 간 연계성이 잘 드러나도록 구성할 필요가 있다. 둘째, 광원에 관한 내용을 주요개념으로 포함하고, 개념 설명을 위해 사용하는 광원을 다루는 개념의 종류와 수준을 고려하여 선정할 필요가 있다. 셋째, 물체를 보는 원리를 포함할 필요가 있다. 넷째, 빛과 렌즈 단원에 포함된 굴절 개념의 소재와 내용 수준을 조정할 필요가 있다. 다섯째, 빛은 초등학교 과학 교육과정에서 포함하고 있는 여러 개념과 깊은 관련성을 가지기 때문에 통합적 접근이 필요하다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
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• pp.65-65
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• 2015

In this talk, I will introduce two topics. The first topic is the polymer light emitting diodes (PLEDs) using graphene oxide quantum dots as emissive center. More specifically, the energy transfer mechanism as well as the origin of white electroluminescence in the PLED were investigated. The second topic is the facile synthesis of eco-friendly III-V colloidal quantum dots and their application to light emitting diodes. Polymer (organic) light emitting diodes (PLEDs) using quantum dots (QDs) as emissive materials have received much attention as promising components for next-generation displays. Despite their outstanding properties, toxic and hazardous nature of QDs is a serious impediment to their use in future eco-friendly opto-electronic device applications. Owing to the desires to develop new types of nanomaterial without health and environmental effects but with strong opto-electrical properties similar to QDs, graphene quantum dots (GQDs) have attracted great interest as promising luminophores. However, the origin of electroluminescence (EL) from GQDs incorporated PLEDs is unclear. Herein, we synthesized graphene oxide quantum dots (GOQDs) using a modified hydrothermal deoxidization method and characterized the PLED performance using GOQDs blended poly(N-vinyl carbazole) (PVK) as emissive layer. Simple device structure was used to reveal the origin of EL by excluding the contribution of and contamination from other layers. The energy transfer and interaction between the PVK host and GOQDs guest were investigated using steady-state PL, time-correlated single photon counting (TCSPC) and density functional theory (DFT) calculations. Experiments revealed that white EL emission from the PLED originated from the hybridized GOQD-PVK complex emission with the contributions from the individual GOQDs and PVK emissions. (Sci Rep., 5, 11032, 2015). New III-V colloidal quantum dots (CQDs) were synthesized using the hot-injection method and the QD-light emitting diodes (QLEDs) using these CQDs as emissive layer were demonstrated for the first time. The band gaps of the III-V CQDs were varied by varying the metal fraction and by particle size control. The X-ray absorption fine structure (XAFS) results show that the crystal states of the III-V CQDs consist of multi-phase states; multi-peak photoluminescence (PL) resulted from these multi-phase states. Inverted structured QLED shows green EL emission and a maximum luminance of ~45 cd/m2. This result shows that III-V CQDs can be a good substitute for conventional cadmium-containing CQDs in various opto-electronic applications, e.g., eco-friendly displays. (Un-published results).

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 춘계학술대회 논문집
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• pp.268-271
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• 2007

A sandwich tube is a structured material that has two inner and outer circular tubes and light material between them. In this paper, a sandwich tube with a pyramidal truss core is introduced. Fabrication method and example made by brazing are shown. The behavior of the sandwich tube under lateral loading is predicted by analytical and numerical method. Comparative study between the sandwich and the monocoque tube is performed at a point of view such as strength and weight saving. As a result, proposed tube is appropriate for application to lightweight structural material