• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.171-173
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• 2002

This paper describes the open frame type high power density switching converter. It is based on active clamp forward converter with synchronous rectifier, and packaged by using the open frame and multi-layer printed circuit board (PCB) techniques to achieve the high power density. Furthermore, windings of transformer and inductor are also realized by multi-layer PCB so that it achieves the higher power density. Through the experiment on the proto-type converter of 50[W], it is confirmed that power density of $50[W/in^3]$ and maximum efficiency of over 91 [%] are obtained.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2013년도 춘계학술대회 논문집
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• pp.607-608
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• 2013

• 한국마이크로전자및패키징학회:학술대회논문집
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• 한국마이크로전자및패키징학회 2001년도 3rd Korea-Japan Advanced Semiconductor Packaging Technology Seminar
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• pp.87-119
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• 2001

Fine Pitch Technology will be accelerated among next decade. Buildup Technology is Key Technology for High Density Interconnection. Novel Base Material is critical for High Speed, Area Array Flip Chip Application. Japanese PWB Technology Roadmap will be Published soon.

• The Journal of Advanced Prosthodontics
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• 제14권3호
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• pp.150-161
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• 2022

PURPOSE. The purpose of the study was to assess the influence of build orientations and density of support structures on the trueness of the 3D printed removable partial denture (RPD) frameworks. MATERIALS AND METHODS. A maxillary Kennedy class III and mandibular class I casts were 3D scanned and used to design and produce two 3D virtual models of RPD frameworks. Using digital light processing (DLP) 3D printing, 47 RPD frameworks were fabricated at 3 different build orientations (100, 135 and 150-degree angles) and 2 support structure densities. All frameworks were scanned and 3D compared to the original virtual RPD models by metrology software to check 3D deviations quantitatively and qualitatively. The accuracy data were statistically analyzed using one-way ANOVA for build orientation comparison and independent sample t-test for structure density comparison at (α = .05). Points study analysis targeting RPD components and representative color maps were also studied. RESULTS. The build orientation of 135-degree angle of the maxillary frameworks showed the lowest deviation at the clasp arms of tooth 26 of the 135-degree angle group. The mandibular frameworks with 150-degree angle build orientation showed the least deviation at the rest on tooth 44 and the arm of the I-bar clasp of tooth 45. No significant difference was seen between different support structure densities. CONCLUSION. Build orientation had an influence on the accuracy of the frameworks, especially at a 135-degree angle of maxillary design and 150-degree of mandibular design. The difference in the support's density structure revealed no considerable effect on the accuracy.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.272-272
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• 2010

We have fabricated alumina thick films by inkjet printing technology. Two different types of ink system were formulated in order to understand their evaporation behaviors and their evaporation effects on the powder distribution on, the surface during inkjet-printed alumina thick films. Single solvent system was formulated with N,N-dimethylformamide(DMF), which led to coffee ring effects which non-uniformly distributed alumina particles on the substrate during the ink evaporation. However, Co-solvent system which consists of both Water and DMF produced relatively uniform distribution of the particles on the substrate. We believe that these two different distributions of alumina particles are attributed to the ink fluid flow directions in the ink droplets ejected from the different ceramic ink system. We have modulated inkjet parameters such as dot-to-dot distance, line-to-line distance, jetting velocity and jetting drop size in order to find out the optimum condition for the printing of alumina thick films from two different ink systems. The surface roughness, microstructures and dielectric properties of these inkjet-printed alumina thick films were investigated.

• 한국자원리싸이클링학회:학술대회논문집
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• 한국자원리싸이클링학회 2005년도 춘계임시총회 및 제25회 학술발표대회
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• pp.23-27
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• 2005

본 연구에서는 유가금속 성분이 약 45%인 폐인쇄회로기판을 사용하여 염산 용액에서 전해생성된 염소에 의한 침출 거동을 조사하였다. 폐인쇄회로기판내 유가금속 중 구리는 약 84%에 해당하였다. 전해생성된 염소에 의한 침출거동에 미치는 변수들의 영향을 조사한 결과 염소의 전핸생성 및 교반에 의한 용액으로의 용해 및 혼입 단계가 침출율에 가장 큰 영향을 주었다. 염산농도 1M, 전류밀도 $20\;mA/cm^2$, 교반속도 600 rpm, 용액온도 $50^{\circ}C$의 조건에서 99%의 침출율을 얻었다. 전해생성된 염소의 침출반응 이용율은 교반속도가 높고 전류밀도가 낮을수록 높아졌다. 반응 초기에는 알루미늄, 납, 주석 등 시료내 기타 금속성분들의 침출이 주로 일어났으며, 이러한 반응이 둔화됨에 따라 구리의 침출이 증가하였다.

• Geomechanics and Engineering
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• 제33권1호
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• pp.11-18
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• 2023

This study explores a new energy partitioning approach to determine the fracture toughness of 3-D printed pristine/recycled high density polyethylene (HDPE) blends employing the essential work of fracture (EWF) concept. The traditional EWF approach conducts a uniaxial tensile test with double-edge notched tensile (DENT) specimens and measures the total energy defined by the area under a load-displacement curve until failure. The approach assumes that the entire total energy contributes to the fracture process only. This assumption is generally true for extruded polymers that fracture occurs in a material body. In contrast to the traditional extrusion manufacturing process, the current 3-D printing technique employs fused deposition modeling (FDM) that produces layer-by-layer structured specimens. This type of specimen tends to include separation energy even after the complete failure of specimens when the fracture test is conducted. The separation is not relevant to the fracture process, and the raw experimental data are likely to possess random variation or noise during fracture testing. Therefore, the current EWF approach may not be suitable for the fracture characterization of 3-D printed specimens. This paper proposed a new energy partitioning approach to exclude the irrelevant energy of the specimens caused by their intrinsic structural issues. The approach determined the energy partitioning location based on experimental data and observations. Results prove that the new approach provided more consistent results with a higher coefficient of correlation.

• 한국통신학회논문지
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• 제19권11호
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• pp.2276-2290
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• 1994

본 논문에서는 입력된 문자에서 비교적 안정적 구조특징을 추출하고 이 구조정보를 이용하여 문자를 좀 더 세부적인 유형으로 분류한 후 인식을 행하는 문자 인식 방법을 제안한다. 본 방법은 우선 한글 문자를 스캐너로 입력받아 방향코드화하고 방향코드화된 문자로부터 방향밀도벡터를 추출하여 기본 6형식으로 분류한다. 그리고 기본형식 정보에 의해 각 문자로부터 안정된 구조특징을 추출하고 안정된 구조특징을 이용해 26가지 형태의 세부유형으로 분류하여 각 해당 자소 영역의 방향밀도벡터를 신경망에 입력하여 인식하거나 직접 해당 자소의 인식을 행한다. 한글 KS C 5601의 2350자에 대해 실험한 결과 94%의 인식률을 얻어 본 방법의 유효성을 확인할 수 있었다.

• 한국인쇄학회지
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• 제24권1호
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• pp.13-22
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• 2006

We investigated the effects of the enzyme treatment of fiber for printability of coated paper. The results could summarized as follows, 1. The samples with enzyme treatment (average 87.8%) have higher ink gloss than the blank (85.6%). Printed density showed same trends with the ink gloss. However, the ${\beta}$-Glucosidase treated sample showed the lowest printed density (2.14 %) due to the lowest thickness of the ink layer, which is influenced by coated weight and surface smoothness. 2. The samples whose base paper was Xylanase and ${\beta}$-Glucosidase treated showed higher surface strength (4.2% and 4.0%, respectively) than the blank while the samples with the Hernicellulase and ${\beta}$-Glucuronidase treatment showed lower surface strength (3.2%and 3.7%, respectively) due to the influence of air permeability. 3. Hemicellulase and ${\beta}$-Glucuronidase treated base paper, which have relatively low air permeability, showed better ink repellence (4.3 and 4.4 %, respectively) than the blank (3.8 %). 4. The blank and the Xylanase treated base paper showed high set-off, which is the last category of printability.

• 한국분말재료학회지
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• 제30권3호
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• pp.223-232
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• 2023

Metal additive manufacturing (AM) has transformed conventional manufacturing processes by offering unprecedented opportunities for design innovation, reduced lead times, and cost-effective production. Aluminum alloy, a material used in metal 3D printing, is a representative lightweight structural material known for its high specific strength and corrosion resistance. Consequently, there is an increasing demand for 3D printed aluminum alloy components across industries, including aerospace, transportation, and consumer goods. To meet this demand, research on alloys and process conditions that satisfy the specific requirement of each industry is necessary. However, 3D printing processes exhibit different behaviors of alloy elements owing to rapid thermal dynamics, making it challenging to predict the microstructure and properties. In this study, we gathered published data on the relationship between alloy composition, processing conditions, and properties. Furthermore, we conducted a sensitivity analysis on the effects of the process variables on the density and hardness of aluminum alloys used in additive manufacturing.