Here, we demonstrate an anion controlled molecular gate based on synthetic ion channels modified ... more Here, we demonstrate an anion controlled molecular gate based on synthetic ion channels modified with polyethyleneimine. For single conical nanochannels, addition of ATP leads to significant decrease in the rectified ion flux, representing the closure of the ionic gate. Complementary experiments performed with nanoporous membranes show that the flux of charged dye (NDS(2-)) through a cylindrical nanochannel array diminishes by the co-addition of ATP in the analyte solution.
This paper explains how mortgage market liberalization can introduce greater volatility in the ho... more This paper explains how mortgage market liberalization can introduce greater volatility in the housing market. It begins by documenting two stylized facts for OECD countries that models with perfect credit markets fail to explain: (i) housing investment is about five times as volatile as output and (ii) housing investment tends to be more volatile in economies with more liberalized mortgage
This paper presents a new type of jetting dispenser featuring piezoelectric actuator in order to ... more This paper presents a new type of jetting dispenser featuring piezoelectric actuator in order to achieve high flow rate and small dot sizes in semiconductor packaging processes. After describing structural components of the dispensing mechanism and the operating principle, a dynamic modeling is undertaken by considering the behavior of the piezostack, hydraulic magnification, dispensing needle and adhesive fluid. In the modeling, fluid models for adhesive fluid and hydraulic magnification are derived with a dumped parameter method. The governing equation of motion is then derived by integrating the fluid models with structural model. Subsequently, the dynamic behavior of the dispenser and its dispensing amount are investigated by applying several types of square wave driving voltage input and design parameter values are determined.
We present an experimental demonstration of a synthetic nanoporous membrane suitable for charge-s... more We present an experimental demonstration of a synthetic nanoporous membrane suitable for charge-selective transport of ionic species. The surfaces and walls of synthetic nanochannels, fabricated in heavy ion-tracked polyethylene terephthalate membranes are negatively charged due to the presence of carboxylate moieties. These nanofilters discriminate and gate the transport of cations while inhibiting the passage of anions. The permselectivity of these membranes is reversed by converting the carboxylic moieties into terminated amino groups. The positively charged (aminated) membranes facilitate the transport of anions. Based on the same principle, charged biomolecules (bovine serum albumin and lysozyme) are successfully filtered through these membranes. These membranes also exhibit the phenomenon of ion concentration polarization.
Byeong-Ho Son 1, a , Seung-Bok Choi 1,b , Quoc-Hung Nguyen 1,c , ... Seung-Min Hong 2,d , Soo-Jin... more Byeong-Ho Son 1, a , Seung-Bok Choi 1,b , Quoc-Hung Nguyen 1,c , ... Seung-Min Hong 2,d , Soo-Jin Lee 2,e Yong Hun Lee 2,f Min-Kyu Choi 2,g ... 1Smart Structures and Systems Lab., Department of Mechanical Engineering, Inha University, Incheon 402-751, Korea ...
This paper presents a new type of jetting dispenser driven by a ring type piezoelectric actuator.... more This paper presents a new type of jetting dispenser driven by a ring type piezoelectric actuator. By operating at very high frequencies, the dispenser is expected to provide very small dispensing dot size of low viscous adhesives (viscosity of 50cp to 500cp) at high dispensing flow rate in semiconductor packaging processes. After describing the mechanism and operational principle of the dispenser, a mathematical model of the system is derived by considering behaviors of the piezostack, the actuating spring, the dispensing needle and the adhesive fluid dynamics. In the modeling, a lumped parameter method is applied to model the adhesive whose rheological property is approximately expressed by Bingham model. The governing equation of the whole dispenser is then derived by integrating the structural model with the fluid model. Based on the proposed model, the dispenser is designed and manufactured. Subsequently, the dispensing performances such as dot size and dispensing flow rate are investigated using the proposed model and then validated by experiment.
Here, we demonstrate an anion controlled molecular gate based on synthetic ion channels modified ... more Here, we demonstrate an anion controlled molecular gate based on synthetic ion channels modified with polyethyleneimine. For single conical nanochannels, addition of ATP leads to significant decrease in the rectified ion flux, representing the closure of the ionic gate. Complementary experiments performed with nanoporous membranes show that the flux of charged dye (NDS(2-)) through a cylindrical nanochannel array diminishes by the co-addition of ATP in the analyte solution.
This paper explains how mortgage market liberalization can introduce greater volatility in the ho... more This paper explains how mortgage market liberalization can introduce greater volatility in the housing market. It begins by documenting two stylized facts for OECD countries that models with perfect credit markets fail to explain: (i) housing investment is about five times as volatile as output and (ii) housing investment tends to be more volatile in economies with more liberalized mortgage
This paper presents a new type of jetting dispenser featuring piezoelectric actuator in order to ... more This paper presents a new type of jetting dispenser featuring piezoelectric actuator in order to achieve high flow rate and small dot sizes in semiconductor packaging processes. After describing structural components of the dispensing mechanism and the operating principle, a dynamic modeling is undertaken by considering the behavior of the piezostack, hydraulic magnification, dispensing needle and adhesive fluid. In the modeling, fluid models for adhesive fluid and hydraulic magnification are derived with a dumped parameter method. The governing equation of motion is then derived by integrating the fluid models with structural model. Subsequently, the dynamic behavior of the dispenser and its dispensing amount are investigated by applying several types of square wave driving voltage input and design parameter values are determined.
We present an experimental demonstration of a synthetic nanoporous membrane suitable for charge-s... more We present an experimental demonstration of a synthetic nanoporous membrane suitable for charge-selective transport of ionic species. The surfaces and walls of synthetic nanochannels, fabricated in heavy ion-tracked polyethylene terephthalate membranes are negatively charged due to the presence of carboxylate moieties. These nanofilters discriminate and gate the transport of cations while inhibiting the passage of anions. The permselectivity of these membranes is reversed by converting the carboxylic moieties into terminated amino groups. The positively charged (aminated) membranes facilitate the transport of anions. Based on the same principle, charged biomolecules (bovine serum albumin and lysozyme) are successfully filtered through these membranes. These membranes also exhibit the phenomenon of ion concentration polarization.
Byeong-Ho Son 1, a , Seung-Bok Choi 1,b , Quoc-Hung Nguyen 1,c , ... Seung-Min Hong 2,d , Soo-Jin... more Byeong-Ho Son 1, a , Seung-Bok Choi 1,b , Quoc-Hung Nguyen 1,c , ... Seung-Min Hong 2,d , Soo-Jin Lee 2,e Yong Hun Lee 2,f Min-Kyu Choi 2,g ... 1Smart Structures and Systems Lab., Department of Mechanical Engineering, Inha University, Incheon 402-751, Korea ...
This paper presents a new type of jetting dispenser driven by a ring type piezoelectric actuator.... more This paper presents a new type of jetting dispenser driven by a ring type piezoelectric actuator. By operating at very high frequencies, the dispenser is expected to provide very small dispensing dot size of low viscous adhesives (viscosity of 50cp to 500cp) at high dispensing flow rate in semiconductor packaging processes. After describing the mechanism and operational principle of the dispenser, a mathematical model of the system is derived by considering behaviors of the piezostack, the actuating spring, the dispensing needle and the adhesive fluid dynamics. In the modeling, a lumped parameter method is applied to model the adhesive whose rheological property is approximately expressed by Bingham model. The governing equation of the whole dispenser is then derived by integrating the structural model with the fluid model. Based on the proposed model, the dispenser is designed and manufactured. Subsequently, the dispensing performances such as dot size and dispensing flow rate are investigated using the proposed model and then validated by experiment.
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