Polyacetylenes from Panax stipuleanatus and their Cytotoxic Effects on Human Cancer Cells

Chun Liang,Mahn Cuong Nguyen,강희경,Hye-Jin Boo,양서영,김정아,Yan Ding,김영호 대한화학회 2011 Bulletin of the Korean Chemical Society Vol.32 No.9

Analysis of the Components of Guibitang and Fermented Guibi-tang and their Ability to Inhibit Angiotensin-converting Enzyme

Chun Liang,Na Young Yun,Sang Won Jung,Dong Seon Kim,Young Jae Lee,마진열 한국생약학회 2011 Natural Product Sciences Vol.17 No.4

Guibi-tang is a traditional medicine used for the treatment of colds. We investigated the levels of several compounds in Guibi-tang before and after fermentation with Lactobacillus and tested their ability to inhibit angiotensin-converting enzyme. Six known compounds (decursin, decursinol angelate, nodakenin, liquiritin, formononetin, and 6-gingerol) and 2 unidentified compounds were detected in Guibi-tang (GB) and fermented Guibi-tang (FGB) by an established HPLC-DAD method. The levels of the 6 known compounds were decreased after fermentation. FGB showed more potent inhibition of angiotensin-converting enzyme activity than GB. In conclusion, fermentation with Lactobacillus affects the content of several compounds in GB and improves its angiotensin-converting enzyme inhibitory activity.

Oleanane-triterpenoids from Panax stipuleanatus inhibit NF-kB

Chun Liang,Yan Ding,Seok Bean Song,Jeong Ah Kim,Nguyen Manh Cuong,Jin Yeul Ma,Young Ho Kim 고려인삼학회 2013 Journal of Ginseng Research Vol.37 No.1

In continuation of our research to find biological components from Panax stipuleanatus, four oleanane-type triterpenes (12 to 15) were isolated successively. Fifteen oleanane-type saponins (1 to 15) were evaluated for nuclear factor (NF)-κB activity using a luciferase reporter gene assay in HepG2 cells. Compounds 6 to 11 inhibited NF-κB, with IC50 values between 3.1 to 18.9 μM. The effects on inducible nitric oxide synthase and cyclooxygenase-2 by compounds 8, 10, and 11 were also examined using reverse transcription-polymerase chain reaction. Three compounds (8, 10, and 11) inhibited NF-κB activity by reducing the concentration of inflammatory factors in HepG2 cells.

KADRL: Knowledge-assisted deep reinforcement learning for urban traffic signal control

Chunliang (Lillian) Wu 대한교통학회 2023 대한교통학회 학술대회지 Vol.88 No.-

Traffic lights are an integral part of the modern-day traffic infrastructure that controls traffic flow by adjusting signal timings. Many efforts have been made to design efficient traffic signal control (TSC) methods to alleviate traffic congestion in the past few decades. Traditional TSC methods are mainly rule-based or model-based. They did not consider many complex and stochastic scenarios of the real world; thus, they are less likely to respond to dynamic traffic demands in a timely manner. Thanks to the rapid development of artificial intelligence, a promising learning-based paradigm, called reinforcement learning (RL), provides a new way to address intractable TSC problems by interacting with the traffic environment without a model. However, developing a scalable RL-based TSC algorithm with fast learning speed and strong robustness is still an open question. This study proposes a decentralized knowledge-assisted deep reinforcement learning (KADRL) model for multiple intersections. In the model, traffic lights at an intersection are controlled by an independent agent, guaranteeing its scalability. Also, a knowledge-assisted decision mechanism is embedded in the deep reinforcement learning (DRL) algorithm to avoid unnecessary action explorations. The proposed algorithm is tested in a simulated environment with dynamic traffic demand and compared with traditional TSC methods and state-of-the-art DRL algorithms. The experiment results show the performance of the proposed algorithm is better than traditional TSC methods and DRL-based algorithms. In addition, the robustness analysis demonstrates that the proposed algorithm is effective and stable with noisy and delayed observations.

Generic Competitive Strategies and New Product Development Speed of SMEs in International Markets: The Moderating Effect of Market Turbulence

Chunliang Yao,김은미 한국국제경영학회 2023 國際經營硏究 Vol.34 No.2

Competitive strategies have been considered as crucial strategic weapons to achieve better performance in international markets. However, few scholars have focused on effects of competitive strategies on speed of new product development (NPD). Particularly, fewer studies have combined small and medium-sized enterprises (SMEs) in international markets with the turbulent market environment to explore the relationship between competitive strategies and speed of NPD. By conducting empirical study of 205 Korean SMEs, this study found that differentiation and cost leadership strategies are positively related to NPD speed. The findings also point out that both strategies do not all positively affect NPD speed under turbulent market condition. In a highly turbulent market environment, only differentiation strategy might influence more to NPD speed of SMEs; cost leadership strategy presents less impact on NPD speed. Consequently, the results of this study suggest that SMEs should develop and adopt an appropriate competitive strategy based on the environment where they target and their own development goals.

Design, Analytical and Experimental Evaluations of Additive Manufacturing for Laser Melting of Polymer-Metal Colloids

Chunliang Kuo,Tingyu Chang,Jhihjie Liu,Chunhui Chung 한국정밀공학회 2021 International Journal of Precision Engineering and Vol.22 No.6

This paper presents a novel additive manufacturing process, namely the laser melting of polymer-metal colloids (LMC), which is advantageous for repairing features and reducing contamination sources. The developed polymer-metal colloids are conveyed via the designed spindle-driven dispensing system to demonstrate consolidations of the metallic phase onto heterogeneous substrate materials via laser melting. Modelling of the flow rate, velocity and pressure fields is linked to the geometric design of the mechanical devices in the spindle-driven process. The equilibriums of the heat transfer equations in the colloid element were initiated and presented for the estimations of input laser energy. When the input heat was absorbed by the colloid element, the average energy density could be obtained by the ratio of the overall energy density and the engaged laser scanning volume. In the experimental work of the validation tests, the polymer-metal colloid was consolidated on the substrate material with three different results: unconsolidated, partially consolidated and consolidated. The consolidation and bonding of metallic fractions on the heterogeneous substrate materials in the laser melting actions were evaluated and reported.

Relationship between Local SNS Usage and Social Capital

Chunliang Yao,주재훈,신민석 한국유통과학회 2016 유통과학연구 Vol.14 No.8

Purpose - This study aims to understand the relationship between Chinese local SNS usage and social capital building through Chinese international students in South Korea. A research model that illustrates the relationship between the SNS usage (i.e., intensity, communication and social capital building is proposed. Based on the analysis, this study will provide responses to the question of if SNS really presents the danger of trapping international consumers in their local comfort zone or enhance social capital for the users. Research design, data, and methodology - The survey questionnaire is circulated among the WeChat (a Chinese local SNS) users who are the Chinese international students studying in South Korea. The collected data is analyzed by structural equation method using SPSS and AMOS. Results - Proposed hypotheses of the positive relationships between the attachment of SNS use and both individuals’ bridging and bonding social capital are supported. It’s also supported that (1) interpersonal communication, (2) interpersonal communication with old friends, and (3) interpersonal communication for making new friends on SNS positively influence individuals’ bridging social capital. Conclusions - This paper demonstrates the importance of intensity of WeChat use and interpersonal communication that impact Chinese international students’ bridging and bonding social capital on WeChat.

Evaluations of Surface Integrity and Mechanical Performance in Laser Melting of Stainless Steel Powders with Heterogeneous Metal Substrates

Chunliang Kuo,Weijun Peng,Anchun Chiang 한국정밀공학회 2018 International Journal of Precision Engineering and Vol.19 No.3

This paper outlines advances in the processing technology of layer manufacturing in conjunction with laser melting metallic powders (stainless steel 316L) on heterogeneous metal substrates (stainless steel 316). Elemental migration of chromium and nickel in the fusion/dilution zone which led to possible strengthening mechanisms was analysed. Two-phase austenitic microstructures in the body were found to dilute into the stainless steel 316 substrate matrixes leading to the strengthening in the conjunction. Laser power was shown to be particularly significant (Fcal: 6.03, PCR: 47.9%) to produce high microhardness (~268 HV0.1) depending on the increase in ferrite content. In the confirmation runs, high tensile strength was achieved (834 MPa) with high density (7.64 g/cm3) due to the smoothened elemental migration of chrome and nickel, the strengthened matrix in the duplex structure, and the enhanced microhardness under the input high energy density.

Parametric Optimization of Density and Dimensions in Three-Dimensional Printing of Ti-6Al-4V Powders on Titanium Plates Using Selective Laser Melting

Chunliang Kuo,Chihhao Su,Anchun Chiang 한국정밀공학회 2017 International Journal of Precision Engineering and Vol.18 No.11

This work presents a powder bed-based additive manufacturing technique for the consolidation of Ti-6Al-4V powders onto commercially pure titanium plates. Experiments were conducted to investigate and explain the influence of various process parameters, including laser power (100-200 W), exposure duration (50-175 μs) and point distance (35-70 μm), on the material density and porosity of the printed body; as well as the dimensional accuracy. A process parameter array was created using fractional factorial tests (Taguchi L9) and the significance of the operating factors was analysed using ANOVA. Thermally induced deflections in the Ti plates were influenced by the volumetric energy density, variations in thermal conductivity, scanning strategy and the layup orientation in laser scanning. Furthermore, the geometry of the printed body was shown to alter the thermal stress relief, leading to asymmetric deformation of the Ti plate. Statistical regression models were used to balance the contradictory criteria of material density and dimensional accuracy (Z1 variation). The lowest dimensional variation (Z1: 0.12 mm) was produced using equal weightings (50%) for the factors dominating material density and dimensional accuracy, respectively. In contrast, setting weighting values of 80% for material density and 20% for dimensional accuracy resulted in the highest material density (4.13 g/cm3).

Wear behaviour and sustainability of coated abrasives in grinding of aluminium alloy using minimum quantity lubrication

Chunliang Kuo,Jingguo Yang,Juihung Wen 한국정밀공학회 2020 International Journal of Precision Engineering and Vol.7 No.1

The consumption of coated abrasive papers has been greatly increased in grinding of aluminium gadget housings to achieve a mirror-like finish prior to cosmetic treatments; however, the rapid abrasive wear produces low sustainability and likewise massive wastage. Prevention of adhesion wear and control of the grinding temperature of the coated abrasive papers are key challenges for prolonging abrasives’ life, but can be managed by the MQL grinding system. This work investigates the influences of coated abrasives and environmental conditions on grinding force, material removal and machined surface topography; with the corresponding abrasive wear patterns under dry conditions and the developed MQL system in the grinding of aluminium alloy (6061-T6). The developed relationship between the stress flow and thermal softening on the workpiece showed a good correlation of ~ 96.3% for controlling grinding forces and the associated thermal effects. Material removal decreased when the adhesion in the pores developed into clusters, rather than abrasion wear. The ground surface roughness decreased when the wear of the abrasives altered the cutting action into a sliding friction. With MQL, the reduction of abrasive wear showed in a retarded process of adhesion and clogging, followed by a rapid increase of abrasion and attrition wear.