포터블 기반 스마트 구조 응답 모니터링 시스템 개발 및 현장 적용성 평가

박상기(Sangki Park),서동우(Dong-Woo Seo),박기태(Ki-Tae Park),김호진(Hojin Kim),Thanh Bui-Tien(Thanh Bui-Tien ),Lan Nguyen-Ngoc(Lan Nguyen-Ngoc ) 한국방재안전학회 2023 한국방재안전학회 논문집 Vol.16 No.4

케이블 교량의 거동은 동적 응답에 의해 지배적이며 상대적으로 복잡하므로 교량의 상태를 평가하기 위한 장단기 현장 계측이 요구되는 경우가 빈번하다. 영구적인 SHMS(Structural Health Monitoring System)가 설치되지 않은 경우 성능평가를 위해 이동식 모니터링 시스템이 필요하다. 이 경우 교량의 위치와 형태에 따라 전력, 통신 등의 제한된 여건으로 인해 이동식 모니터링 시스템 운영에 어려움이 발생할 수 있다. 본 연구에서는 국내는 물론 동남아 지역 교량의 장 ‧ 단기 모니터링에 효과적으로 활용될 수 있는 포터블 기반의 스마트 구조응답 모니터링 시스템을 개발하였다. 개발된 시스템은 현장에서 자체 전원 공급 시스템을 이용하여 장시간 운용이 가능한 다채널 휴대용 데이터 수집 및 분석 장비이며, 실시간 데이터를 이용하여 케이블 교량의 동적 특성을 자동으로 분석할 수 있는 알고리즘을 탑재하고 있다. 개발된 시스템의 현장 적용성을 평가하기 위해 한국과 베트남의 케이블 교량에서 현장 실증을 수행하였으며, 이를 통해 개발된 시스템의 현장 운영의 신뢰성과 효율성을 확인하였고, 추가적으로 케이블 교량 모니터링 분야에서의 해외 시장 적용 가능성을 확인하였다. Because the behavior of cable bridges is dominated by dynamic response and is relatively complex, short- and long-term field monitoring are often required to evaluate the bridge condition. If a permanent SHMS (Structural Health Monitoring System) is not installed, a portable monitoring system is needed for the checking of bridge condition. In this case, it can be difficult to operate the portable monitoring system due to limited conditions such as power and communication according to the location and type of the bridge. In this study, the portable-based smart structural response monitoring system is developed that can be effectively used for short- and long-term monitoring of cable bridges in Korea and Southeast Asia. The developed system is a multi-channel portable data acquisition and analyzer that can be operated for a long time in the field using its own power supply system, and is included with the automated analysis algorithm for the dynamic characteristics of cable bridges using real-time data. In order to evaluate the field applicability of the developed system, field demonstration was conducted on cable bridges in Korea and Vietnam. Through the demonstration, the reliability and efficiency of field operation of the developed system were confirmed, and additionally, the possibility of application to overseas markets was confirmed in cable bridge monitoring field.

Improvement of Vibration Isolation Performance of Isolation System Using Negative Stiffness Structure

Thanh Danh Le,Minh Truong Ngoc Bui,Kyoung Kwan Ahn IEEE 2016 IEEE/ASME transactions on mechatronics Vol.21 No.3

<P>Improvement of the isolation effectiveness of the isolation system using negative stiffness structure (NSS) named 'system with NSS' by introducing an adaptive sliding mode control algorithm is presented in this paper. The control strategy is to employ a radial basis function neural network (RBFNN) model to approximate the equivalent control effort and a self-tuning proportional-integral-derivative (PID) algorithm is used to compensate approximate error. Moreover, a fuzzy logic inference mechanism is utilized for realizing an auxiliary control law to remove completely the chattering problem on the conventional sliding mode control. Then, the Lyapunov stability theorem is utilized to figure out the adaptive laws for updating the coefficients in the RBFNN model, PID compensator, and tuning the fuzzy parameters. Finally, four experimental cases of studies are performed to evaluate the proposed control method.</P>

A new naphthoquinone analogue and antiviral constituents from the root of <i>Rhinacanthus nasutus</i>

Ngoc, Tran Minh,Phuong, Nguyen Thi Thanh,Khoi, Nguyen Minh,Park, SeonJu,Kwak, Hee Jae,Nhiem, Nguyen Xuan,Trang, Bui Thi Thu,Tai, Bui Huu,Song, Jae-Hyoung,Ko, Hyun-Jeong,Kim, Seung Hyun Informa UK (TaylorFrancis) 2019 Natural product research Vol.33 No.3

Some Results of Recent Investigation and Application of Rubber Blends in Vietnam

Bui Chuong,Nguyen Thanh Liem,Dang Viet Hung,Nguyen Huy Tung,Nguyen Pham Duy Linh,Nguyen Thanh Nhan,Pham Ngoc Linh,Le Anh Kien,Chu Chien Huu 한국고분자학회 2021 한국고분자학회 학술대회 연구논문 초록집 Vol.46 No.1

We have investigated the change of tensile strength (TS) of Natural rubber/chloroprene rubber (NR/CR) blends during combination ageing, including heating and dynamic mechanical loading. Using model of statistical experiment, we built the equation describing the dependence of TS on four factors: temperature T, number of cyclic loadings N, contents of NR (C_NR) and chloroprene (CCR). This equation allows predict the TS change of NR/CR blends after combination ageing with accepted inaccuracy – less than 10%. We also investigated the effect of nanofillers, such as nanoclay, SiO2, Fe₃O4, on adhesion of some rubber blends to polyester and steel cords. It was found, in the case of EPDM/CIIR rubber blends, both nanoclay and SiO2 have no effect on adhesion to steel cords, while nano SiO2 may enhance adhesion to polyester cords. On other side, Fe₃O4 may remarkably enhance adhesion of NR/CR blends to steel. Mentioned results are successfully applied in some practical rubber products working under fatigue conditions, such as rubber/steel antivibration pad for locomotive, heat resistant conveyor, water dam, underwater lift bag.

Mathematical Modeling of a Variable Displacement Vane Pump for Engine Lubrication

Bui Ngoc Minh Truong,Dinh Quang Truong,Nguyen Thanh Trung,Ahn Kyoung Kwan 제어로봇시스템학회 2015 제어로봇시스템학회 국제학술대회 논문집 Vol.2015 No.10

This paper developed a complete and accurate mathematical model for a typical variable displacement vane-type oil pump to investigate the working performance of the pump. Firstly, the detailed theoretical model was built based on pump’s geometric design and dynamic analyses. Next, numerical simulations with the constructed model and experiments on the real pump system were carried out to analyze the main power loss factors in order to develop the complete model with high accuracy. The estimated pump performance using the complete pump model was finally verified by numerical simulations in comparison with the practical tests.

Effect of Phosphate-Containing Acrylic Dispersants on Rheological and Dielectric Properties of Carbon Black-Filled Epoxy System

Bui Thanh Son,Nguyen Ngoc Trung,이은성,배진영 한국고분자학회 2012 Macromolecular Research Vol.20 No.6

This article describes the use of copolymeric dispersants with an acrylic backbone and phosphate side groups for formulating carbon black (CB)-epoxy composites. Six phosphate-modified acrylic copolymer dispersants were prepared from the corresponding epoxy-containing acrylic copolymers. The phosphate-modified dispersant with the highest concentration of hydrophobic alkyl chains and typical phosphate moiety groups showed a desirable passivation effect on the CB, and was found to lower the viscosity of the CB-epoxy paste, leading to the well-cured composite after heat treatment. The thick composite film prepared by employing the CB/phosphate-containing dispersant/epoxy paste was built up on a Cu plate by a screen printing process followed by thermal curing. The dielectric properties of the 3.1 vol% CB-filled epoxy film showed a high dielectric constant (K 6280) and a rather low dissipation factor (Df, 61%) @ 1 MHz.

Adaptive Grey Predictor-based Controller for Force Control of EHA System

Dao Thanh Liem,Bui Ngoc Minh Truong,Kyoung Kwan Ahn 제어로봇시스템학회 2016 제어로봇시스템학회 국제학술대회 논문집 Vol.2016 No.10

This study aims to develop an effective control approach for force control of a typical EHA system. This control scheme is considered as an advanced combination of a feedforward neural network – based PID (FNNPID) controller and a fuzzy grey predictor (FGP), shortened as feedforward neural network fuzzy grey predictor (FNNFGP). Here, the FNNPID controller is used to drive the system to desired targets. Meanwhile, the FGP predictor with self-tuning ability of the predictor step size takes part in, first, estimating the system output in the near future to optimize the controller parameters in advance and, second, creating a compensating control signal accordingly to the system perturbations and, consequently, improving the control performance. Real-time experiments have been carried out to investigate the effectiveness of the proposed control approach.

Identification of aquifer system in the whole Red River Delta, Vietnam

Duong Du Bui,Akira Kawamura,Thanh Ngoc Tong,Hideo Amaguchi,Naoko Nakagawa,Yoshihiko Iseri 한국지질과학협의회 2011 Geosciences Journal Vol.15 No.3

The Red River Delta is one of two biggest deltas in Vietnam. People living in the delta depend entirely on groundwater for their domestic water. However, the aquifer system in the whole Red River Delta remains poorly understood due to the lack of available data. Recently, we were nominated to construct a hydrogeological database. Using these valuable data contained in this database, this paper comprehensively analyzed the best number of 778 boreholes including well logs and their hydrogeological parameters obtained from pumping tests for the first time in order to identify the entire aquifer system and characterize hydrogeological conditions in the whole delta for potential groundwater resources. Great efforts have been made to establish and analyze hydrogeological maps, cross sections, and contour maps of main aquifers’ thickness and transmissivity. As for the results, we found that groundwater mainly exists in Quaternary unconsolidated sediments as porous water forming the topmost Holocene unconfined aquifer (HUA) and the shallow Pleistocene confined aquifer (PCA) sandwiching the Holocene-Pleistocene aquitard (HPA), while cleft and karst water exist in consolidated Neogene formations and Mesozoic rocks constituting the Neogene water bearing layer (NWL) and Mesozoic fractured zones (MFZ), respectively. PCA is almost entirely distributed over the delta. It serves as the highest groundwater potential and the most important aquifer for water supply. HUA is also widely distributed about 88% over the delta and has a high groundwater potential. NWL and MFZ, placed below PCA but exposed on the surface outside the delta, are minor sources for local domestic water supply only. These findings are indispensable for further groundwater analyses needed to ensure the sustainable groundwater development for the high-security water requirements in the delta, but have never been completed sufficiently before due to the unavailability of large-scale basic data sets

Preparation and characterization of silicone resin nanocomposite containing CdSe/ZnS quantum dots

Trung, Nguyen Ngoc,Luu, Quynh‐,Phuong,Son, Bui Thanh,Sinh, Le Hoang,Bae, Jin‐,Young Wiley Subscription Services, Inc., A Wiley Company 2012 Polymer composites Vol.33 No.10

<P><B>Abstract</B></P><P>We report the preparation of the core/shell cadmium selenide/Zinc sulfide quantum dots (CdSe/ZnS QDs)‐silicone resin nanocomposite through the solution‐mixing method, followed by thermal hydrosilylation. After dispersing QDs into Dow Corning two‐component silicone resins (OE6630A and OE6630B at 1:4 mixing ratio by weight), the resins were cured at 150°C for 1.5 h to produce QD‐silicone resin nanocomposites. The curing behavior of the silicone resins resulting from the thermal hydrosilylation was studied using differential scanning calorimetry (DSC). The properties of the QD‐silicone resin nanocomposites were investigated by ultraviolet–visible (UV–vis), fluorescence, confocal laser scanning microscopy (CLSM), atomic force microscopy (AFM), and thermogravimetric analysis (TGA) measurements. The QDs that contain trioctylamine (TOA) as the original ligand can poison the Pt catalyst in the resins and inhibit the curing process by increasing the exothermic peak temperature, at which a lower heat of hydrosilylation is observed. Incorporating a small amount of CdSe/ZnS QDs (0.1 wt%) can greatly improve the thermal stability of the silicone resins. Moreover, CdSe/ZnS QDs tend to form clusters that are relatively homogeneously distributed in a cured silicone resin, offering good optical properties of 11.2 lm W<SUP>−1</SUP> luminous efficiency and 14.6% photoluminescence conversion efficiency (PCE) in light emitting device (LED) test. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers</P>

Preliminary study of doxycycline adsorption from aqueous solution on alkaline modified biochar derived from banana peel

Van-Truc Nguyen,Thanh-Binh Nguyen,Thi-Dieu-Hien Vo,Nguyen Duy Dat,Thi-Kim Quyen Vo,Xuan Cuong Nguyen,Viet-Cuong Dinh,Thi-Ngoc-Chau Le,Thi-Giang-Huong Duong,Manh-Ha Bui,Xuan-Thanh Bui 대한환경공학회 2023 Environmental Engineering Research Vol.29 No.3

This study explores the adsorption of doxycycline (DOX) from aqueous solutions onto biochar derived from banana peel, which was prepared using a potassium hydroxide activation method (KOH-BPB). The biochar properties were characterized based on morphology, surface area (SBET of 710.241 ㎡ g<SUP>−1</SUP>), functional groups, and surface charge (pHPZC = 7.7). Parameters, including initial pH, DOX concentration, and ionic strength, that influenced the DOX adsorption capacity of KOH-BPB were examined. Adsorption equilibrium of DOX on KOH-BPB was assessed through four isothermal models: the Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich models. The obtained data were most compatible with the Langmuir model (R² = 0.9879). KOH-BPB has a maximum DOX absorption capacity of 121.95 mg g<SUP>-1</SUP> which exceeds that of many comparable absorbents. The maximum DOX removal was 96.7% at pH 6, a DOX concentration of 20 mg L<SUP>-1</SUP>, and a KOH-BPB dose of 1.0g L<SUP>-1</SUP>. These findings reveal that biochar from banana peel effectively removes antibiotic residues from water. This study provides a potential, low-cost, and environmentally friendly adsorbent.