UV-curing kinetics and performance development of <i>in situ</i> curable 3D printing materials

Kim, Ye Chan,Hong, Sungyong,Sun, Hanna,Kim, Myeong Gi,Choi, Kisuk,Cho, Jungkeun,Choi, Hyouk Ryeol,Koo, Ja Choon,Moon, Hyungpil,Byun, Doyoung,Kim, Kwang J.,Suhr, Jonghwan,Kim, Soo Hyun,Nam, Jae-Do Elsevier 2017 European polymer journal Vol.93 No.-

<P><B>Abstract</B></P> <P>As three-dimensional (3D) printing technology is emerging as an alternative way of manufacturing, the high resolution 3D printing device often requires systems such as drop jetting printing of <I>in situ</I> UV-curable photopolymers. Accordingly, the key issue is process control and its optimization to ensure dimensional accuracy, surface roughness, building orientation, and mechanical properties of printed structures, which are based on the time- and temperature-dependent glass transition temperature (<I>T<SUB>g</SUB> </I>) of the resin system under UV-curing. In this study, the UV-cure kinetics and <I>T<SUB>g</SUB> </I> development of a commercially available UV-curable acrylic resin system were investigated as a model system, using a differential scanning photocalorimeter (DPC). The developed kinetic model included the limited conversion of cure that could be achieved as a maximum at a specific isothermal curing temperature. Using the developed model, the <I>T<SUB>g</SUB> </I> was successfully described by a modified DiBenedetto equation as a function of UV curing. The developed kinetic model and <I>T<SUB>g</SUB> </I> development can be used to determine the 3D printing operating conditions for the overlay printing and <I>in situ</I> UV curing, which could ensure high-resolution and high-speed manufacturing with various UV-curing materials.</P> <P><B>Highlights</B></P> <P> <UL> <LI> UV-cure kinetic analysis were applied to a commercial Multi-jet 3D printing material. </LI> <LI> The developed kinetic model included the limited conversion of cure by temperature. </LI> <LI> The <I>T<SUB>g</SUB> </I> was described by a modified DiBenedetto equation as a function of UV curing. </LI> <LI> The developed kinetic model showed an excellent agreement to isothermal experiments. </LI> <LI> The overlay printing time for each isothermal temperature was determined. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Transcriptome analysis of wild-type and afsS deletion mutant strains identifies synergistic transcriptional regulator of afsS for a high antibiotic-producing strain of Streptomyces coelicolor A3(2)

Kim, Min Woo,Lee, Bo-Rahm,You, SungYong,Kim, Eun-Jung,Kim, Ji-Nu,Song, Eunjung,Yang, Yung-Hun,Hwang, Daehee,Kim, Byung-Gee Springer-Verlag 2018 Applied microbiology and biotechnology Vol.102 No.7

<P>Most secondary metabolism in Actinobacteria is controlled by multi-layered, gene-regulatory networks. These regulatory mechanisms are not easily identified due to their complexity. As a result, when a strong transcriptional regulator (TR) governs activation of biosynthetic pathways of target antibiotics such as actinorhodin (ACT), additional enhancement of the biosynthesis is difficult in combination with other TRs. To find out any 'synergistic transcriptional regulators (sTRs)' that show an additive effect on the major, often strong, transcriptional regulator (mTR), here, we performed a clustering analysis using the transcriptome datasets of an mTR deletion mutant and wild-type strain. In the case of ACT biosynthesis in Streptomyces coelicolor, PhoU (SCO4228) and RsfA (SCO4677) were selected through the clustering analysis, using AfsS (SCO4425) as a model mTR, and experimentally validated their roles as sTRs. Furthermore, through analysis of synergistic effects, we were able to suggest a novel regulation mechanism and formulate a strategy to maximize the synergistic effect. In the case of the double TR mutant strain (Delta rsfA pIBR25::afsS), it was confirmed that the increase of cell mass was the major cause of the synergistic effect. Therefore, the strategy to increase the cell mass of double mutant was further attempted by optimizing the expression of efflux pump, which resulted in 2-fold increase in the cell mass and 24-fold increase in the production of ACT. This result is the highest ACT yield from S. coelicolor ever reported.</P>

Development of a simultaneous multi-residue analysis for screening and confirmation of 7 veterinary drugs in bovine milk by LC-MSMS

MinKyoung Kim,NamSun Kim,HyunJung Kwon,SungYong Ha,HeeSun Kim,JongWon Kim 한국예방수의학회 2019 예방수의학회지 Vol.43 No.2

A simple and fast analytical method based on liquid chromatography-tandem mass spectrometry was developed for detection of the veterinary drugs acetanilide, anthranilic acid, antipyrine, cyproheptadine, diphenhydramine, DLmethylephedrine, and phenacetin in bovine milk. The target analytes were extracted from milk samples by using acetonitrile followed by clean-up with C18 and liquid-liquid purification with saturated n-hexane. A reverse-phase analytical column was employed with a mobile phase comprising (A) 0.1% formic acid in distilled water and (B) 0.1% formic acid in acetonitrile to achieve the best chromatographic separation. Matrix-matched calibration curves (r2 ≥ 0.9986) were constructed using six concentrations (1, 2, 5, 10, 20, and 40 μg/kg) of drugs in the milk matrix. Recoveries at three drug-spiking levels (5, 10, and 20 μg/kg) ranged from 71.2% to 103.8% with intra-day and inter-day relative standard deviation (RSD) values of ≤ 8.6%. The calculated limits of quantification (LOQ) were 0.19-7.1 μg/kg.

Identification of key regulators for the migration and invasion of rheumatoid synoviocytes through a systems approach

You, Sungyong,Yoo, Seung-Ah,Choi, Susanna,Kim, Ji-Young,Park, Su-Jung,Ji, Jong Dae,Kim, Tae-Hwan,Kim, Ki-Jo,Cho, Chul-Soo,Hwang, Daehee,Kim, Wan-Uk National Academy of Sciences 2014 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF Vol.111 No.1

<P>Rheumatoid synoviocytes, which consist of fibroblast-like synoviocytes (FLSs) and synovial macrophages (SMs), are crucial for the progression of rheumatoid arthritis (RA). Particularly, FLSs of RA patients (RA-FLSs) exhibit invasive characteristics reminiscent of cancer cells, destroying cartilage and bone. RA-FLSs and SMs originate differently from mesenchymal and myeloid cells, respectively, but share many pathologic functions. However, the molecular signatures and biological networks representing the distinct and shared features of the two cell types are unknown. We performed global transcriptome profiling of FLSs and SMs obtained from RA and osteoarthritis patients. By comparing the transcriptomes, we identified distinct molecular signatures and cellular processes defining invasiveness of RA-FLSs and proinflammatory properties of RA-SMs, respectively. Interestingly, under the interleukin-1β (IL-1β)–stimulated condition, the RA-FLSs newly acquired proinflammatory signature dominant in RA-SMs without losing invasive properties. We next reconstructed a network model that delineates the shared, RA-FLS–dominant (invasive), and RA-SM–dominant (inflammatory) processes. From the network model, we selected 13 genes, including periostin, osteoblast-specific factor (POSTN) and twist basic helix–loop–helix transcription factor 1 (TWIST1), as key regulator candidates responsible for FLS invasiveness. Of note, POSTN and TWIST1 expressions were elevated in independent RA-FLSs and further instigated by IL-1β. Functional assays demonstrated the requirement of POSTN and TWIST1 for migration and invasion of RA-FLSs stimulated with IL-1β. Together, our systems approach to rheumatoid synovitis provides a basis for identifying key regulators responsible for pathological features of RA-FLSs and -SMs, demonstrating how a certain type of cells acquires functional redundancy under chronic inflammatory conditions.</P>

소나무림과 잣나무림의 산불 잠재위험성 비교

Sungyong Kim,Sukhee Yoon,Youseung Kim,Byungdoo Lee,Youngjin Lee,Mina Jang 위기관리 이론과 실천 2015 Crisisonomy Vol.11 No.11

본 연구에서는 우리나라를 대표하는 침엽수종 소나무림과 잣나무림을 대상으로 지표층 연료의 특성을 파악하고, 수관화 전이 잠재 위험성을 비교하고자 하였다. 이를 위해 소나무 임분과 잣나무 임분에서 지표층연료를 144 sample, 53 sample을 채취하여 분석에 이용하였으며, 국외에서 제시된 바 있는 물리적 산불수학식을 적용하여 수관화 전이 잠재위험성을 분석하였다. 본 연구 결과에 의하면, 잣나무림은 타감작용의 여파로 관목층과 초본층 연료량이 소나무림에 비해 적은 것으로 나타났으나, 낙엽,낙지층 연료량은 소나무림에 비해 많은 것으로 분석되었다. 수관화 전이 잠재위험성 분석에서는 수관화 전이 결정 강도, 수관화 전이 결정 화염길이, 수관화 전이 결정 확산속도 모두 잣나무림이 높은 결과치를 나타내었는데, 이는 잣나무림이 소나무림에 비해 수관화 전이 위험성이 낮음을 의미한다. 이러한 원인은 잣나무림이 소나무림에 비해 지표층 연료에 함유되어 있는 수분의 양이 많고, 임분의 평균지하고가 높기 때문으로 사료된다. This study aims to analyze the characteristics of surface fuel load and estimate potential crown fire transition hazards in Pinus densiflora and Pinus koraiensis stands. Surface fuels were collected from 144 samples in Pinus densiflora stands and 53 samples in Pinus koraiensis stands. A forest fire spread equation presented in foreign countries was applied to analyze the potential crown fire transition hazard in Korea. The results of the data analysis showed that the shrub fuel layer and herb fuel layer of the load in Pinus densiflora stand was less than those in Pinus koraiensis stand due to allelopathy. It is also found that dead leaves and snags fuel was higher in Pinus densiflora stand than Pinus koraiensis stand, which indicates that Pinus koraiensis stand has relatively less risk of crown fire hazard than Pinus densiflora stand

Analysis of risk propagation using the world trade network

Kim Sungyong,Yun Jinhyuk 한국물리학회 2022 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.81 No.7

An economic system is an exemplar of a complex system in which all agents interact simultaneously. Interactions between countries have generally been studied using the fow of resources across diverse trade networks, in which the degree of dependence between two countries is typically measured based on the trade volume. However, indirect infuences may not be immediately apparent. Herein, we compared a direct trade network to a trade network constructed using the personalized PageRank (PPR) encompassing indirect infuences. By analyzing the correlation of the gross domestic product (GDP) between countries, we discovered that the PPR trade network has greater explanatory power on the propagation of economic events than direct trade by analyzing the GDP correlation between countries. To further validate our observations, an agentbased model of the spreading economic crisis was implemented for the Russia–Ukraine war of 2022. The model also demonstrates that the PPR explains the actual impact more efectively than the direct trade network. Our research highlights the signifcance of indirect and long-range relationships, which have often been overlooked.

Zero-Shot Transfer Learning of a Throwing Task via Domain Randomization

Sungyong Park,Jigang Kim,H. Jin Kim 제어로봇시스템학회 2020 제어로봇시스템학회 국제학술대회 논문집 Vol.2020 No.10

Deep reinforcement learning (DRL) on continuous robot control has received a wide range of interests over the last decade. Collecting data directly from real robots results in high sample complexities and can cause safety accidents, so simulators are widely used as efficient alternatives for real robots. Unfortunately, policies trained in the simulation cannot be directly transferred to real-world robots due to a mismatch between the simulation and the reality, which is referred to as ‘reality gap’. To close this gap, domain randomization (DR) is commonly used. DR guarantees better transferability in the zero-shot setting, i.e. training agents in the source domain and testing them on the previously unseen target domain without fine-tuning. In this work, we identify the positive influence of DR on zero-shot transfer between the sim-to-sim setting with an object throwing task.

β1-integrin-dependent migration of microglia in response to neuron-released α-synuclein

Kim, Changyoun,Cho, Eun-Deok,Kim, Hyung-Koo,You, Sungyong,Lee, He-Jin,Hwang, Daehee,Lee, Seung-Jae Nature Publishing Group 2014 Experimental and molecular medicine Vol.46 No.4

<P>Chronic neuroinflammation is an integral pathological feature of major neurodegenerative diseases. The recruitment of microglia to affected brain regions and the activation of these cells are the major events leading to disease-associated neuroinflammation. In a previous study, we showed that neuron-released α-synuclein can activate microglia through activating the Toll-like receptor 2 (TLR2) pathway, resulting in proinflammatory responses. However, it is not clear whether other signaling pathways are involved in the migration and activation of microglia in response to neuron-released α-synuclein. In the current study, we demonstrated that TLR2 activation is not sufficient for all of the changes manifested by microglia in response to neuron-released α-synuclein. Specifically, the migration of and morphological changes in microglia, triggered by neuron-released α-synuclein, did not require the activation of TLR2, whereas increased proliferation and production of cytokines were strictly under the control of TLR2. Construction of a hypothetical signaling network using computational tools and experimental validation with various peptide inhibitors showed that β1-integrin was necessary for both the morphological changes and the migration. However, neither proliferation nor cytokine production by microglia was dependent on the activation of β1-integrin. These results suggest that β1-integrin signaling is specifically responsible for the recruitment of microglia to the disease-affected brain regions, where neurons most likely release relatively high levels of α-synuclein.</P>

A Study on the Secure Database Controlled Under Cloud Environment

SungYong Kim(김성용),Ji-Hong Kim(김지홍) 한국정보보호학회 2013 정보보호학회논문지 Vol.23 No.6

최근 데이터베이스의 크기가 점차 증가하고 있다. 기업에서는 데이터베이스 관리의 어려움으로 인하여 클라우드 형태로 아웃소싱하고 있으며, 이때 클라우드 서비스업체에 의해 관리되는 데이터베이스의 보안은 매우 중요하다. 데이터베이스 내의 중요 정보를 보호하기 위해서는 암호화하는 것이 최선의 방법이지만, 일단 암호화되고 난 후에는 더 이상 검색하기 어려워진다. 암호화된 데이터베이스에서의 검색 성능은 암호화 방법과 검색 방법에 의해 좌우된다. 본 논문에서는 가변길이의 키워드 인덱스와 블룸필터를 사용하여, 클라우드 서비스업체의 관리하의 데이터베이스에 대한 암호화 방법 및 효율적인 검색 방법을 제안한다. 마지막으로 제안된 방법이 데이터베이스 암호화 및 관련 응용분야에 유용하게 사용될 수 있음을 보인다. Nowadays, the databases are getting larger and larger. As the company has difficulty in managing the database, they want to outsource the database to the cloud system. In this case the database security is more important because their database is managed by the cloud service provider. Among database security techniques, the encryption method is a well-certified and established technology for protecting sensitive data. However, once encrypted, the data can no longer be easily queried. The performance of the database depends on how to encrypt the sensitive data, and on the approach for searching, and the retrieval efficiency that is implemented. In this paper we propose the new suitable mechanism to encrypt the database and lookup process on the encrypted database under control of the cloud service provider. This database encryption algorithm uses the bloom filter with the variable keyword based index. Finally, we demonstrate that the proposed algorithm should be useful for database encryption related research and application activities.

Rapid DNA Hybridization Analysis Using a PDMS Microfluidic Sensor and a Molecular Beacon

KIM, Sungyong,CHEN, Lingxin,LEE, Sangyeop,SEONG, Gi Hun,CHOO, Jaebum,LEE, Eun Kyu,OH, Chil-Hwan,LEE, Sanghoon Japan Society for Analytical Chemistry 2007 Analytical sciences Vol.23 No.4

<P>A rapid DNA analysis has been developed based on a fluorescence intensity change of a molecular beacon in a PDMS microfluidic channel. Recently, we reported a new analytical method of DNA hybridization involving a PDMS microfluidic sensor using fluorescence energy transfer (FRET). However, there are some limitations in its application to real DNA samples because the target DNA must be labelled with a suitable fluorescent dye. To resolve this problem, we have developed a new DNA microfluidic sensor using a molecular beacon. By monitoring the change in the restored fluorescence intensity along the channel length, it is possible to rapidly detect any hybridization of the molecular beacon to the target DNA. In this case, the target DNA does not need to be labelled. Our experimental results demonstrate that this microfluidic sensor using a molecular beacon is a promising diagnostic tool for rapid DNA hybridization analysis.</P>