高敞地域 農業用水源의 水質特性에 關한 硏究

金煥起,姜鎭錫,全鍾南 全北大學校 附設 都市및環境硏究所 1992 都市 및 環境硏究 Vol.7 No.-

This paper had study on the water quality characteristics and water quality management of water sources as agricultural water in Gochang. This study included the measurement of stream water quality, water quality of reservoir and water quality of groundwater, this investigation was tried to find out water quality standard of agricultural water into each sources. Results from water quality analysis, the water quality of stream in Gochang was measure that pH was 8.5-7.0, COD was 14.8-1.6㎎/ℓ, SS was 282.8-1.2㎎/ℓ, T-P was 2.64-0.17㎎/ℓ, T-P was 0.22-0.01㎎/ℓ, electric conductivity was 220-50㎲/㎝ and Cd, Pb, Cu was below 0.01㎎/ℓ. The water quality of reservoir in Gochang was measure that pH was 7.0-8.0, COD was 8.0-2.6㎎/ℓ, SS was 126.1-3.4㎎/ℓ, T-P was 1.13-0.456㎎/ℓ, T-P was 0.16-0.05㎎/ℓ, electric conductivity was 200-130㎲/㎝. The water quality of ground water in Gochang was measure that pH was 6.0-8.4, TS was 51.8-419.8㎎/ℓ, COD was 2.4-1.0㎎/ℓ, CO_3^- was 125.8-14.5㎎/ℓ, SO_4 was 0.46-48.3㎎/ℓ, Cl^- was 134.1-3.6㎎/ℓ, T-N was high 15㎎/ℓ Therefore, stream water and reservoir water in Gochang had adequate to agricultural water quality standard. The ground water had adequate to agricultural water quality standard in deep well and low well.

Improved conversion efficiency of CdS quantum dots-sensitized TiO₂ nanotube array using ZnO energy barrier layer

Chen, Chong,Xie, Yi,Ali, Ghafar,Yoo, Seung Hwa,Cho, Sung Oh IOP Pub 2011 Nanotechnology Vol.22 No.1

<P>We report that the use of a chemically deposited ZnO energy barrier between a CdS quantum dot sensitizer and TiO<SUB>2</SUB> nanotubes (TNTs) can improve the efficiency of quantum dots-sensitized solar cells (QDSCs). The experimental results show that the formation of the ZnO layers over TNTs significantly improved the performances of the CdS QDSCs based on the TNTs electrodes. In particular, a maximum photoconversion efficiency of 4.6% was achieved for the CdS/ZnO/TNTs electrode under UV–visible light illumination, corresponding to an increase of 43.7% as compared to the CdS/TNTs electrode without the ZnO layers. The improved CdS QDSCs efficiency is attributed to the suppressed recombination of photoinjected electrons with redox ions from the electrolyte resulting from the ZnO energy barrier layers.</P>

Enhanced Performance of Solution‐Processed TESPE‐ADT Thin‐Film Transistors

Chen, Liang‐,Hsiang,Hu, Tarng‐,Shiang,Huang, Peng‐,Yi,Kim, Choongik,Yang, Ching‐,Hao,Wang, Juin‐,Jie,Yan, Jing‐,Yi,Ho, Jia‐,Chong,Lee, Cheng‐,Chung,Chen WILEY‐VCH Verlag 2013 Chemphyschem Vol.14 No.12

<P><B>Abstract</B></P><P>A solution‐processed anthradithiophene derivative, 5,11‐bis(4‐triethylsilylphenylethynyl)anthradithiophene (TESPE‐ADT), is studied for use as the semiconducting material in thin‐film transistors (TFTs). To enhance the electrical performance of the devices, two different kinds of solution processing (spin‐coating and drop‐casting) on various gate dielectrics as well as additional post‐treatment are employed on thin films of TESPE‐ADT, and <I>p</I>‐channel OTFT transport with hole mobilities as high as ∼0.12 cm<SUP>2</SUP> V<SUP>−1</SUP> s<SUP>−1</SUP> are achieved. The film morphologies and formed microstructures of the semiconductor films are characterized in terms of film processing conditions and are correlated with variations in device performance.</P>

Improved conversion efficiency of CdS quantum dot-sensitized TiO₂ nanotube-arrays using CuInS₂ as a co-sensitizer and an energy barrier layer

Chen, Chong,Ali, Ghafar,Yoo, Seung Hwa,Kum, Jong Min,Cho, Sung Oh Royal Society of Chemistry 2011 Journal of materials chemistry Vol.21 No.41

<P>A thin layer of CuInS<SUB>2</SUB> and CdS quantum dots (QDs) is deposited on TiO<SUB>2</SUB> nanotube arrays (TNTs) to form CdS/CuInS<SUB>2</SUB>/TNTs photoelectrodes. The CuInS<SUB>2</SUB> layer is prepared by a successive ionic layer absorption and reaction method, and the CdS QDs are deposited by a chemical bath deposition method. The CuInS<SUB>2</SUB> layer acts as both a co-sensitizer and an energy barrier layer between TNTs and CdS QDs. The deposited CuInS<SUB>2</SUB> layer significantly extends the visible-light response of CdS-sensitized TNTs into 500–700 nm wavelength range. As a consequence, the photoelectrochemical response of the CdS/CuInS<SUB>2</SUB>/TNTs electrodes is much improved compared with CdS sensitized TNTs. The CdS/CuInS<SUB>2</SUB>/TNTs electrodes exhibit a maximum power conversion efficiency of 7.3%, which is a 120% improvement compared with the highest efficiency of 3.3% for CdS/TNTs electrodes in our study. The improved efficiency is mainly due to the increased absorbance and the reduced recombination between the photoinjected electrons and the redox ions from the electrolyte, resulting from the formation of a CuInS<SUB>2</SUB> layer.</P> <P>Graphic Abstract</P><P>Using CuInS<SUB>2</SUB> as a co-sensitizer and an energy barrier layer to improve conversion efficiency of CdS quantum dot-sensitized TiO<SUB>2</SUB> nanotube-arrays. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c1jm13616j'> </P>

A New D-dimer Cutoff Value to Improve the Exclusion of Deep Vein Thrombosis in Cancer Patients

Chen, Chong,Li, Gang,Liu, Yun-De,Gu, Ya-Jun Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.4

Objective: To find a more appropriate alternative to D-dimer cutoff value for the diagnosis of deep vein thrombosis (DVT) in cancer patients. Methods: A total of 711 cancer patients with symptoms suspicious of DVT were included in the study. D-dimer levels were assessed using ELISA. All patients were subjected to imaging procedures. Results: Among 711 patients with cancer, 466 (65.5%) were females and 245 (34.5%) were males, with an average age of $57.3{\pm}13.23$ years. The mean age in the DVT group was significantly higher than in the non-DVT group (P<0.05). The D-dimer levels of the DVT group were significantly higher than those of the non-DVT group (P<0.05). The incidence rate of DVT varied significantly according to cancer type (P<0.05). Increasing age and lung cancer were significantly correlated with D-dimer levels (P<0.05), and a one-year increase in age was associated with a 14.28 ng/ml increase in the D-dimer value. The optimal cutoff point for D-dimer was found to be 981 ng/ml, with a sensitivity of 86.4%, specificity of 79.4%, and accuracy of 82.6%. If the D-dimer cutoff point was set to 981ng/ml, the specificity would increase from 61.8% to 85.5% without loss of sensitivity in patients aged 40 years or younger. In patients aged more than 40 years, the new cutoff almost doubled the specificity with slightly reduced sensitivity. Conclusion: In cancer patients, a new cutoff value of 981 ng/ml effectively improved the exclusion of DVT, especially for patients aged more than 40 years.

Ginsenoside Rb1 exerts neuroprotective effects through regulation of Lactobacillus helveticus abundance and GABA_A receptor expression

Chen, Huimin,Shen, Jiajia,Li, Haofeng,Zheng, Xiao,Kang, Dian,Xu, Yangfan,Chen, Chong,Guo, Huimin,Xie, Lin,Wang, Guangji,Liang, Yan The Korean Society of Ginseng 2020 Journal of Ginseng Research Vol.44 No.1

Background: Ginsenoside Rb1 (Rb1), one of the most abundant protopanaxadiol-type ginsenosides, exerts excellent neuroprotective effects even though it has low intracephalic exposure. Purpose: The present study aimed to elucidate the apparent contradiction between the pharmacokinetics and pharmacodynamics of Rb1 by studying the mechanisms underlying neuroprotective effects of Rb1 based on regulation of microflora. Methods: A pseudo germ-free (PGF) rat model was established, and neuroprotective effects of Rb1 were compared between conventional and PGF rats. The relative abundances of common probiotics were quantified to reveal the authentic probiotics that dominate in the neuroprotection of Rb1. The expressions of the gamma-aminobutyric acid (GABA) receptors, including GABAA receptors (α2, β2, and γ2) and GABAB receptors (1b and 2), in the normal, ischemia/reperfusion (I/R), and I/R+Rb1 rat hippocampus and striatum were assessed to reveal the neuroprotective mechanism of Rb1. Results: The results showed that microbiota plays a key role in neuroprotection of Rb1. The relative abundance of Lactobacillus helveticus (Lac.H) increased 15.26 fold after pretreatment with Rb1. I/R surgery induced effects on infarct size, neurological deficit score, and proinflammatory cytokines (IL-1β, IL-6, and TNF-α) were prevented by colonizing the rat gastrointestinal tract with Lac.H (1 × 10⁹ CFU) by gavage 15 d before I/R surgery. Both Rb1 and Lac.H upregulated expression of GABA receptors in I/R rats. Coadministration of a GABA_A receptor antagonist significantly attenuated neuroprotective effects of Rb1 and Lac.H. Conclusion: In sum, Rb1 exerts neuroprotective effects by regulating Lac.H and GABA receptors rather than through direct distribution to the target sites.

Study on slope stability of waste dump with a weak layer using finite element limit analysis method

Chong Chen,Huayong Lv,Jianjian Zhao,Zhanbo Cheng,Huaiyuan Wang,Gao Xu 국제구조공학회 2024 Structural Engineering and Mechanics, An Int'l Jou Vol.89 No.3

Slope stability is generally paid more attention to in slope protection works, especially for slope containing weak layers. Two indexes of safety factor and failure model are selected to perform slope stability. Moreover, the finite element limit analysis method comprehensively combines the advantage of the limit analysis method and the finite element method obtaining the upper and lower bounds of the safety factor and the failure mode under the slope stability limit state. In this study, taking a waste dump containing a weak layer as an engineering background, the finite element limit analysis method is adopted to explore the potential failure mode. Meanwhile, the sensitivity analysis of slope stability is performed on geometrical and geotechnical parameters of the waste dump. The results show that the failure mode of the waste dump slope is two wedges if the weak layer is located on the ground surface (Model A), while the slope can be observed as three wedges failure if the weak layer is below the ground surface (Model B). In addition, both failure modes are highly sensitive to the friction angle of the weak layer and the shear strength of waste disposal, and moderately sensitive to the heap height, the dip angle and cohesion of the weak layer, while the toe cutting has limited effect on the slope stability. Moreover, the sensitivity to the excavation of the ground depends on the location of the weak layer and failure mode.

Neural Network Control of Induction Motor Speed Control System

Chong Chen 보안공학연구지원센터 2014 International Journal of Control and Automation Vol.7 No.10

Aiming at the characteristics of the inverter and induction motor system in V/F mode, a full digital control of induction motor frequency control system is designed in this paper. BP neural network is adopted to adjust the parameters of PID controller online, so as to perform closed-loop control of the system. The full digital, distant and intelligent control experimental platform is built based on three communication modes, such as OPC, MPI and PROFIBUS-DP. Practical experiments are debugged based on the system designed. The results show that, the control system has good real-time performance, strong resistance to interference, and higher dynamic and static performances and following performances.

Disturbance Observer-Based Patient-Cooperative Control of a Lower Extremity Rehabilitation Exoskeleton

Chong Chen,Shimin Zhang,Xiaoxiao Zhu,Jingyu Shen,Zhiyao Xu 한국정밀공학회 2020 International Journal of Precision Engineering and Vol.21 No.5

Many patients with stroke are suff ering lower limb locomotor dysfunctions all over the world. Body weight supported treadmilltraining has proven to be an eff ective post-stroke rehabilitation training method for these people’s recovery. Nowadays,lower extremity rehabilitation exoskeleton composed of a pair of mechanical legs has been introduced into body weightsupported treadmill training, which can guide and assist the movements of the patient’s legs. However, active movementsof the patient are hardly to be achieved when the rehabilitation exoskeleton is controlled by a commonly utilized positionbasedpassive strategy. Considering the restriction above, a weight supported rehabilitation training exoskeleton device wasdesigned in this paper to ensure the stroke patient can participate in rehabilitation training voluntarily. To realize this goal,a patient-cooperative rehabilitation training strategy based on adaptive impedance control is adopted for the swing phase inthe training. Human–exoskeleton interaction torques are evaluated by a backpropagation neural network and a disturbanceobserver whose stability is proved by Lyapunov’s law. With no additional demand of interaction torque sensors, the complexityof this system is simplifi ed and the cost is reduced. In order to promote the involvement of patient during the rehabilitationtraining, fuzzy algorithm is used to adjust the impedance parameters according to the human–exoskeleton interaction torques. The eff ectiveness of the whole rehabilitation control strategy is demonstrated by experimental results.

Ginsenoside Rb1 exerts neuroprotective effects through regulation of Lactobacillus helveticus abundance and GABA<SUB>A</SUB> receptor expression

Huimin Chen,Jiajia Shen,Haofeng Li,Xiao Zheng,Dian Kang,Yangfan Xu,Chong Chen,Huimin Guo,Lin Xie,Guangji Wang,Yan Liang 고려인삼학회 2020 Journal of Ginseng Research Vol.44 No.1

Background: Ginsenoside Rb1 (Rb1), one of the most abundant protopanaxadiol-type ginsenosides, exerts excellent neuroprotective effects even though it has low intracephalic exposure. Purpose: The present study aimed to elucidate the apparent contradiction between the pharmacokinetics and pharmacodynamics of Rb1 by studying the mechanisms underlying neuroprotective effects of Rb1 based on regulation of microflora. Methods: A pseudo germ-free (PGF) rat model was established, and neuroprotective effects of Rb1 were compared between conventional and PGF rats. The relative abundances of common probiotics were quantified to reveal the authentic probiotics that dominate in the neuroprotection of Rb1. The expressions of the gamma-aminobutyric acid (GABA) receptors, including GABAA receptors (α2, β2, and γ2) and GABAB receptors (1b and 2), in the normal, ischemia/reperfusion (I/R), and I/RþRb1 rat hippocampus and striatum were assessed to reveal the neuroprotective mechanism of Rb1. Results: The results showed that microbiota plays a key role in neuroprotection of Rb1. The relative abundance of Lactobacillus helveticus (Lac.H) increased 15.26 fold after pretreatment with Rb1. I/R surgery induced effects on infarct size, neurological deficit score, and proinflammatory cytokines (IL-1β, IL-6, and TNF-α) were prevented by colonizing the rat gastrointestinal tract with Lac.H (1×10<SUP>9</SUP> CFU) by gavage 15 d before I/R surgery. Both Rb1 and Lac.H upregulated expression of GABA receptors in I/R rats. Coadministration of a GABAA receptor antagonist significantly attenuated neuroprotective effects of Rb1 and Lac.H. Conclusion: In sum, Rb1 exerts neuroprotective effects by regulating Lac.H and GABA receptors rather than through direct distribution to the target sites.