Development of Resin Formulation with High Abrasion Resistance for Projection 3D Printing

황보현우,전석진 한국고분자학회 2021 한국고분자학회 학술대회 연구논문 초록집 Vol.46 No.1

투영방식 3D 프린팅은 50 μm 수준의 우수한 성형 정밀도의 장점으로 정교한 형상을 요하는 산업적 부품의 제작에 강점이 있다. 특히, 내마모성 부품의 3D 프린팅은 후가공 공정의 배제로 인한 절삭가공비용 절감과 재료소모 감소로 인한 원재료비 절감 효과가 큰 장점이 있다. 그러나 3D 프린팅을 통한 내마모성 재료 제작 및 내마모특성 측정에 관한 연구는 거의 이루어지지 않았다. 본 연구에서는 마모가 많이 발생하는 환경에서 정밀 기계부품의 역할을 수행할 수 있도록 레진의 조성을 조절해 보았고, 복합재료를 사용하여 내마모성을 개선시켰다. 또한, 레진 조성물의 탄성계수, 인장강도, 신율 등 기계적 물성을 측정하였고, 마모도 시험을 통해 내마모성에 대해 평가하였다.

Digital light processing 3D printing of multi-materials with improved adhesion using resins containing low functional acrylates

황보현우,전석진 한국화학공학회 2022 Korean Journal of Chemical Engineering Vol.39 No.2

Digital light processing (DLP) 3D printing has received increasing attention due to high-resolution printing capability, mass productivity, and cheap equipment cost. Most of all, the layer resolution less than 50 m overwhelms 200-300 m layer resolution of its competitive technology, filament deposition modeling (FDM) 3D printing. Despite the advantage of the high resolution, weak mechanical properties of DLP 3D printouts have limited their industrial use. One of the easiest ways to improve mechanical property is the use of multi-materials that complement each other’s weak property. However, DLP 3D printing of multi-material printouts with reliable adhesion has been largely unexplored. In this study, we compared the mechanical properties of four pairs of multi-materials consisting of two different materials of the same thickness. A composition with highest modulus and ultimate strength was fixed as the first half layer, and the acrylate of the composition for the other half layer was modulated with a monomer having a functionality between 1 and 3. If the acrylate monomer’s functionality for the other half layer was less than three, the multi-material printout showed nearly averaged mechanical property of each material. We speculate that low functional acrylate with lower viscosity allows sufficient polymerization at the interface, enabling reliable adhesion. This approach that enables successful multi-material printing with improved adhesion and complementary mechanical properties will extend the use of DLP 3D printing in a broad range of industrial application that requires both sophisticated shape and mechanical strength.

하나은행의 빅데이터, 인공지능 기반 서비스 마케팅

황보현우 서비스마케팅학회 2023 서비스마케팅학회 학술대회 발표논문집 Vol.2023 No.05

Reinforcing Resins with Fumed Silica for DLP 3D Printing of Abrasion-resistant Parts

황보현우,김현우,권순훈,전석진 한국고분자학회 2023 폴리머 Vol.47 No.3

Digital light processing (DLP) 3D printing is attracting much attention for its ability to fabricate sophisticated industrial parts due to its excellent layer resolution of less than 100 μm. Among various industrial applications,the area where 3D printing benefits the most is the production of abrasion-resistant parts due to cost reduction and environmental friendliness. The conventional process employed mainly for the production of abrasion-resistant parts is based on cutting and grinding, which leaves a significant amount of discarded residues. In addition, the rapid wear of cutting and grinding tools highly increases machining costs. 3D printing of abrasion-resistant parts can minimize discarded parts and drastically reduce the machining costs by eliminating cutting and grinding costs. In this study, we reinforced 3D printing resins with fumed silica and confirmed the enhancement in abrasion resistance. For an abrasion test of 10000 cycles, the optimal composition of fumed silica, 3 wt%, reduced the weight loss during the Taber test to 1/3, and the impact strength increased about three times compared to the case in which silica was not introduced.We finally confirmed that the sophisticated parts could be fabricated using DLP 3D printing of fumed silica containing resins by printing gears with teeth of 1-2 mm. 3D printing technology suggested for the manufacture of abrasion-resistant parts is expected to contribute to lowering the carbon footprint in the manufacturing process through the reduction of discarded wastes and machining costs

기계 학습을 활용한 보안 이상징후 식별 알고리즘 개발

황보현우,김재경 한국전자거래학회 2022 한국전자거래학회지 Vol.27 No.1

With the development of network technologies, the security to protect organizational resources from internal and external intrusions and threats becomes more important. Therefore in recent years, the anomaly detection algorithm that detects and prevents security threats with respect to various security log events has been actively studied. Security anomaly detection algorithms that have been developed based on rule-based or statistical learning in the past are gradually evolving into modeling based on machine learning and deep learning. In this study, we propose a deep-autoencoder model that transforms LSTM-autoencoder as an optimal algorithm to detect insider threats in advance using various machine learning analysis methodologies. This study has academic significance in that it improved the possibilityof adaptive security through the development of an anomaly detection algorithm based on unsupervised learning, and reduced the false positive rate compared to the existing algorithm through supervised true positive labeling. 인터넷, 모바일 등 네트워크 기술이 발전함에 따라 내외부 침입 및 위협으로부터 조직의 자원을 보호하기 위한 보안의 중요성이 커지고 있다. 따라서 최근에는 다양한 보안 로그 이벤트에 대하여 보안 위협 여부를 사전에 파악하고, 예방하는 이상징후 식별 알고리즘의 개발이 강조되고 있다. 과거 규칙 기반 또는 통계 학습에 기반하여 개발되어 온 보안 이상징후 식별 알고리즘은 점차 기계 학습과 딥러닝에 기반한 모델링으로 진화하고 있다. 본 연구에서는 다양한 기계학습 분석 방법론을 활용하여 악의적 내부자 위협을 사전에 식별하는 최적 알고리즘으로 LSTM-autoencoder를 변형한 Deep-autoencoder 모형을 제안한다. 본 연구는 비지도 학습에 기반한 이상탐지 알고리즘 개발을 통해 적응형 보안의 가능성을 향상시키고, 지도 학습에 기반한 정탐 레이블링을 통해 기존 알고리즘 대비 오탐율을 감소시켰다는 점에서 학문적 의의를 갖는다.

DLP 3D Printing of Urethane Acrylate Based Waterborne Resin

황보현우,전석진 한국고분자학회 2021 한국고분자학회 학술대회 연구논문 초록집 Vol.46 No.2

레진의 광경화를 이용해 3D 구조물을 형성하는 DLP 3D 프린팅은 높은 성형정밀도로 인해 폭넓은 산업적 응용을 기대할 수 있다. 그러나 광경화성 레진은 휘발성이 높은 저분자량의 아크릴레이트를 포함할 뿐 아니라 후처리 공정에서 유기 용매 세척을 요하는 등 환경오염의 소지가 있고 또한 작업장에서 작업자의 건강을 위협한다. 본 연구에서는 이러한 한계를 극복하기 위해 수계 기반의 아크릴레이트로 구성되어 휘발성이 적으며 물로 세척이 가능한 레진 조성물을 제조하였고 이의 3D 프린팅을 수행하였다. 실험에 사용된 친수성 PU 와 PEGDMA 의 수계 레진조성물은 물로 세척이 가능하였으며 기존의 수계 레진보다 개선된 인장탄성율, 인장강도, 신장율을 나타내었다.

기상요인, 가격할인 및 주말효과가 의류상품 판매량에 미치는 영향

황보현우,김은희,채진미,Hwangbo, Hyunwoo,Kim, Eun Hie,Chae, Jin Mie 한국의류산업학회 2017 한국의류산업학회지 Vol.19 No.4

This study investigated the effects of influencing factors on the sales volume of apparel products. Based on previous studies, weekend effect, discount rate, and meteorological factors including daily average temperature, rainfall, sea level pressure, and fine dust were selected as independent variables to calculate their effects on sales quantity of apparel products. The daily sales data during 2015 - 2016 were collected from casual brands and outdoor brands which "A" apparel manufacturing company had operated. The actual data of "A" company were analyzed using SAS(R) 9.4 and SAS(R) Enterprise Miner 14.1. The results of this study were as follows: First, the influencing factors on total sales volume of apparel products were proved to be the weekend effect, discount rate, and fine dust. Second, the analysis of influencing factors on sales volume of apparel products according to season showed: 1) In casual brands, the average temperature had a significant influence on the sales volume of spring/summer products, and the sea level pressure affected the sales volume of summer/fall/winter products significantly. 2) In outdoor brands, the average temperature and the fine dust had a significant influence on the sales volume of all season's products. The sea level pressure affected the sales volume of summer/fall/ winter products significantly. The weekend effect and the discount effect affected the sales volume of apparel products partly. Third, the effect of rainfall was not proven significant, which was different from the results of past studies.

DLP 3D Printing of Multi-Materials with Complementary Mechanical Properties Using Low Functional Acrylates

황보현우,전석진 한국고분자학회 2022 한국고분자학회 학술대회 연구논문 초록집 Vol.47 No.1

IT 서비스 기업의 소유구조와 기업실적 간 인과관계 분석

황보현우 한국전자거래학회 2012 한국전자거래학회 학술대회 발표집 Vol.2012 No.4

Development of Resin Formulation with High Mechanical Strength for Projection 3D Printing

황보현우,전석진 한국고분자학회 2020 한국고분자학회 학술대회 연구논문 초록집 Vol.45 No.2