A novel three-dimensional desalination system utilizing honeycomb-shaped lattice structures for flow-electrode capacitive deionization

Cho, Younghyun,Lee, Ki Sook,Yang, SeungCheol,Choi, Jiyeon,Park, Hong-ran,Kim, Dong Kook The Royal Society of Chemistry 2017 ENERGY AND ENVIRONMENTAL SCIENCE Vol.10 No.8

<P>A highly compact and scalable three-dimensional desalination cell was realized by utilizing honeycomb-shaped porous lattice scaffolds. It did not require a free-standing ion exchange membrane and a thick current collector. Furthermore, the porous structure can act as a structural scaffold. Therefore, it can be readily scaled-up in three dimensions allowing enhanced salt removal capacity. This provides great potential for scale-up and commercialization of desalination using the capacitive deionization technology.</P>

Sustained release of therapeutic proteins from multilayers adsorbed on the sidewalls of porous membranes

Cho, Younghyun,Hong, Jinkee Elsevier 2019 Colloids and surfaces. A, Physicochemical and engi Vol.562 No.-

<P><B>Abstract</B></P> <P>Controlled drug release system employing degradable thin films has recently received much attention owing to many potential applications in biomedical approaches. The layer-by-layer assembly is one of powerful tools to realize such controlled release system because of the ability to easily incorporate biomaterials such as DNA, proteins, and peptides within the film in mild aqueous conditions and those multilayered films undergo gradual disassembly under physiological conditions. However, it has been regarded as a challenging task to prevent the initial burst release of active agents as the multilayer films are immediately degraded from the early stage. In the present study, in order to prevent such an initial fast release, we have employed cylindrical porous structures since the effective diffusion coefficient of a solute within pores is known to be lower than the value in the bulk state, resulting from hydrodynamic and entropic restriction on the solutes due to the presence of pore walls. By varying the pore size of porous membranes, we could modulate the release kinetics of a model protein incorporated within multilayered films, allowing the release of proteins in a more sustained manner when compare with the release from a flat substrate without any additional controlled parameters.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Shear Adhesion of Tapered Nanopillar Arrays

Cho, Younghyun,Minsky, Helen K.,Jiang, Yijie,Yin, Kaiyang,Turner, Kevin T.,Yang, Shu American Chemical Society 2018 ACS APPLIED MATERIALS & INTERFACES Vol.10 No.13

<P>Tapered nanopillars with various cross sections, including cone-shaped, stepwise, and pencil-like structures (300 nm in diameter at the base of the pillars and 1.1 μm in height), are prepared from epoxy resin templated by nanoporous anodic aluminum oxide (AAO) membranes. The effect of pillar geometry on the shear adhesion behavior of these nanopillar arrays is investigated via sliding experiments in a nanoindentation system. In a previous study of arrays with the same geometry, it was shown that cone-shaped nanopillars exhibit the highest adhesion under normal loading while stepwise and pencil-like nanopillars exhibit lower normal adhesion strength due to significant deformation of the pillars that occurs with increasing indentation depth. Contrary to the previous studies, here, we show that pencil-like nanopillars exhibit the highest shear adhesion strength at all indentation depths among three types of nanopillar arrays and that the shear adhesion increases with greater indentation depth due to the higher bending stiffness and closer packing of the pencil-like nanopillar array. Finite element simulations are used to elucidate the deformation of the pillars during the sliding experiments and agree with the nanoindentation-based sliding measurements. The experiments and finite element simulations together demonstrate that the shape of the nanopillars plays a key role in shear adhesion and that the mechanism is quite different from that of adhesion under normal loading.</P> [FIG OMISSION]</BR>

Methanol extracts of Euphorbia cooperi inhibit the production of inflammatory mediators by inhibiting the activation of c?Jun N?terminal kinase and p38 in murine macrophages.

Cho, Young-Chang,Lee, In-Seon,Seo, Huiyun,Ju, Anna,Youn, Deokkyu,Kim, Younghyun,Choun, Jaehee,Cho, Sayeon SPANDIDOS PUBLICATIONS 2014 MOLECULAR MEDICINE REPORTS Vol.10 No.5

<P>Numerous Euphorbiaceae plants have been used for the treatment of diseases, including liver diseases, asthma and rheumatism. The present study evaluated the effect of methanol extracts from Euphorbia cooperi (MEC), a member of the Euphorbiaceae plant family, on the production of inflammatory cytokines interleukin (IL)?6 and tumor necrosis factor (TNF)?α, nitric oxide (NO) as well as the activation of mitogen?activated protein kinase and nuclear factor (NF)?κB signaling. Non?cytotoxic concentrations of MEC significantly reduced the production of NO and IL?6, but not TNF?α, in lipopolysaccharide (LPS)?stimulated RAW 264.7 macrophages. The decreased production of NO by MEC was due to alleviated expression of inducible NO synthase. Reporter assays with cells treated with MEC demonstrated reduced activator protein?1 (AP-1) activity, while NF?κB activity was not reduced. Furthermore, the phosphorylation levels of c?Jun N?terminal kinase (JNK) and p38 were suppressed by MEC while phosphorylation levels of inhibitor of κB were not reduced by MEC, suggesting that MEC?mediated inactivation of JNK and p38 is the underlying regulatory mechanism for inflammatory mediators in LPS?stimulated RAW 264.7 macrophages.</P>

Does Local Government Affect Community Satisfaction of the Younger Generation in Rural Areas? The Case of Jeonbuk, South Korea

Cho, Younghyun,Lee, Kyung-Young Center for Asian Public Opinion ResearchCollaborat 2021 Asian journal for public opinion research Vol.9 No.3

This study examines the relationship between public service satisfaction, trust in local government, and community satisfaction. Previous studies on community satisfaction have insufficiently dealt with public services or trust in local government and have not fully conducted an integrated analysis. To close these knowledge gaps, this study includes public service satisfaction that was constructed with the subcomponents economic support, education, and public safety and trust in local government as factors affecting community satisfaction. Moreover, this study verified the mediating effect of trust in local government between public service satisfaction and community satisfaction. Online surveys were carried out with 980 residents in Jeonbuk, Korea, and structural equation modeling (SEM) was employed. The results indicated that public service satisfaction affected community satisfaction directly or indirectly. In particular, the satisfaction with public safety influenced community satisfaction both directly and indirectly. In addition, trust in local government had a mediating effect between all sub-components of public service satisfaction and community satisfaction. Today, regional disparity between urban and rural areas in developing countries is widening. As a result, residents in rural areas are gradually moving to urban areas. Therefore, rural areas need to increase the community satisfaction of their residents. In this regard, this study suggests important policy implications for community satisfaction enhancement.

2000년대 기계공학분야 특허출원동향 분석

조영현(CHO Younghyun) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11

This paper aims to analyze recent trends in application and approval of patents in the field of mechanical engineering. This analysis is based on the International Patent Classification(IPC), a hierarchical system of patent classification. Created under the Strasbourg Agreement (1971), IPC has 8 sections from A to H, among which the section F covers the area of mechanical engineering. Through the analysis presented in this paper, we will find a significant phenomena in regards to the patents listed under the section B and section F. Conspicuously enough, the patents related to the mechanical engineering (and therefore listed under the section B and section F) tend to fall under multiple segments at the same time, especially since 2000. This not only intimates an important trends in R&D and patent applications in the field of mechanical engineering, but also lets us have critical prospects and strategical minds for the decades to come.

고분자 나노복합체 박막의 결정화 거동

조용현(Younghyun Cho) 한국고분자학회 2019 폴리머 Vol.43 No.2

고분자가 박막 형태로 존재하거나 혹은 나노입자를 함유한 나노복합체의 경우 벌크 상태와는 다른 독특한 결정화 거동을 보인다. 본 연구에서는 벌크 상태와 박막 상태, 그리고 나노입자를 함유한 나노복합체 박막 형태의 고분자 매트릭스의 결정화 거동에 대한 분석이 X-선 회절, 다양한 현미경, 고속 시차주사열량계 등의 방법을 통해 수행되었다. 친수성 나노 입자가 존재하고 박막의 두께가 감소할수록 결정화도와 결정화 온도가 감소하였다. 또한 소수성 나노입자가 나노복합체 박막의 결정화 거동에 거의 영향을 끼치지 않는 것과는 달리 spherurite 구조의 형성이 억제되고 edge-on lamellar에서 flat-on lamellar 구조로의 층 상전이 현상 또한 강하게 억제되었다. 본 연구 결과는입자와 매트릭스간 상호 작용 및 공간적 제한이 고분자 결정화에 어떻게 영향을 미치는지, 미세 구조 설계에 어떻게 사용되는지 이해하는 데 도움이 될 것이라 생각된다. In the case of nanoparticles containing polymer nanocomposite or in the form of thin film, they exhibit a unique crystallization behavior different from the bulk state. In this study, the crystallization behaviors of polymer matrix in the form of nanocomposite thin film, homogeneous thin film, and bulk polymer were analyzed by X-ray diffraction and various microscopy techniques. The crystallinity and the crystallization temperature decreased in the presence of hydrophilic nanoparticles with thinner film thickness. In addition, the formation of the spherurite structure was suppressed and the transition from the edge-on to the flat-on lamellar structure was strongly inhibited while hydrophobic nanoparticles had little effect on the crystallization behavior of the nanocomposite thin film. We believe that the results help to understand how the interactions between particles and matrix and confined geometry affect the crystallization of polymers and how they are utilized to design microstructures.

System-Level Online Power Estimation Using an On-Chip Bus Performance Monitoring Unit

Younghyun Kim,Sangyoung Park,Youngjin Cho,Naehyuck Chang IEEE 2011 IEEE transactions on computer-aided design of inte Vol.30 No.11

<P>Quality power estimation is a basis of efficient power management of electronic systems. Indirect power measurement, such as power estimation using a CPU performance monitoring unit (PMU), is widely used for its low cost and area overheads. However, the existing CPU PMUs only monitor the core and cache activities, which result in a significant accuracy limitation in the system-wide power estimation including off-chip memory devices. In this paper, we propose an on-chip bus (OCB) PMU that directly captures on-chip and off-chip component activities by snooping the OCB. The OCB PMU stores the activity information in separate counters, and online software converts counter values into actual power values with simple first-order linear power models. We also introduce an optimization algorithm that minimizes the energy model to reduce the number of counters in the OCB PMU. We compare the accuracy of the power estimation using the proposed OCB PMU with real hardware measurement and cycle-accurate system-level power estimation, and demonstrate high estimation accuracy compared with CPU PMU-based estimation method.</P>

NPU를 위한 효율적인 Fused Convolution 스케줄링 기법

이영현(Younghyun Lee),김혜준(Hyejun Kim),유용승(Yongseung Yu),조명진(Myeongjin Cho),서지원(Jiwon Seo),박영준(Yongjun Park) 대한전자공학회 2023 대한전자공학회 학술대회 Vol.2023 No.11

As the AI industry evolves, neural network processing units (NPUs) are being developed to deliver AI services faster and more efficiently. One of the most important challenges for these NPUs is task scheduling to minimize off-chip memory accesses, which incur significant performance overhead. In particular, convolutional layers can be fused with multiple layers to reduce the memory accesses, but it is difficult to find the optimal schedule due to the too large exploration space. In this paper, we propose an efficient schedule exploration algorithm to optimize the fusion of multiple convolutional layers in NPUs. The proposed algorithm organizes the fusion group exploration space in the form of a grid to explore the optimal schedule. Experimental results show that the fusion schedule explored by the proposed method reduces the latency by 7.7% and reduces the off-chip memory access by 15% compared to the baseline algorithm.

Radiation-induced changes in DNA methylation and their relationship to chromosome aberrations in nuclear power plant workers

Lee, Younghyun,Kim, Yang Jee,Choi, Young Joo,Lee, Joong Won,Lee, Sunyeong,Cho, Yoon Hee,Chung, Hai Won Informa Healthcare 2015 International Journal of Radiation Biology Vol.91 No.2

<P><I>Purpose</I>: We investigated the association between occupational radiation exposure and DNA methylation changes in nuclear power plant workers. We also evaluated whether radiation- induced DNA methylation alterations are associated with chromosome aberrations.</P><P><I>Materials and methods</I>: The study population included 170 radiation-exposed workers and 30 controls. We measured global, long interspersed nuclear element-1 (LINE-1), and satellite 2 methylation levels in blood leukocyte DNA. The analysis of chromosome aberrations was performed on peripheral lymphocytes.</P><P><I>Results</I>: Global DNA methylation levels were lower in radiation-exposed workers than in controls. The methylation levels were negatively associated with the recent 1.5-year radiation dose in a multiple linear regression model (β = − 0.0088, <I>p</I> ≤ 0.001); the levels increased proportionally with the total cumulative dose in radiation-exposed workers. LINE-1 methylation levels were higher in radiation-exposed workers than in controls and were significantly associated with the total cumulative radiation dose in a multiple linear regression model (β = − 0.031, <I>p</I> = 0.035). Global DNA methylation levels were also correlated with chromosome aberrations among workers. Workers with low global methylation levels had a higher frequency of chromosome aberrations than did subjects with high global methylation levels.</P><P><I>Conclusion</I>: Occupational exposure to low-dose radiation could affect DNA methylation levels, and the radiation-induced DNA methylation alterations may be associated with chromosome aberrations.</P>