Commercial air-conditioning systems are widely used for buildings of various sizes. Design and installation of these systems follow a certain guideline developed by the manufacturer. The guideline also includes the adequate amount of refrigerant to be charged into the system. However, the guideline is often insufficient to reflect all the characteristics of installation, which results in too little or too much refrigerant. Inadequate amount of refrigerant usually causes more power consumption and reduced air-conditioning / heating capacity. This paper focuses on identifying the relationship between adequate refrigerant amount and various state variables such as condensation temperature of the air-conditioning system. This is based on regression analysis of data obtained through the experiments under controlled temperature and humidity.
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Review of the advances and applications of variable refrigerant flow heating, ventilating, and air-conditioning systems for improving indoor thermal comfort and air quality Napoleon Enteria, Odinah Cuartero-Enteria, Takao Sawachi International Journal of Energy and Environmental Engineering.2020; 11(4): 459. CrossRef
The process of tattooing to mark the position of lesions in the colon is one of important functions of the conventional endoscope. However, commercial capsule endoscope (CE) devices cannot perform the tattooing procedure because they cannot accommodate the size of the tattooing device. In this paper, we propose a compact tattooing mechanism design which can be accommodated inside the CE. Two conical springs, two triggering modules and a needle that can be installed inside a volume of 840 mm3 are employed to perform the needle insertion/withdrawal and inject the ink. A triggering module to deploy the conical springs is designed to be activated by heating a Ni-Cr wire and melting Wood’s metal. In this study, the activation time of the triggering module is investigated based on a Wood’s metal heating simulation. In order to determine the proper conical springs to ensure the activation of the tattooing mechanism, the elastic force correlation between two conical springs is studied. Then, the components of the proposed tattooing mechanism are fabricated and assembled, and an ex-vivo test is performed. Conclusively, the proposed tattooing mechanism implements the correct needle stroke and the proper ink injection into the submucosal layer of a porcine colon.
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Robotic Localization Based on Planar Cable Robot and Hall Sensor Array Applied to Magnetic Capsule Endoscope Min-Cheol Kim, Eui-Sun Kim, Jong-Oh Park, Eunpyo Choi, Chang-Sei Kim Sensors.2020; 20(20): 5728. CrossRef
This paper presents a robot hand inspired from grasp and grip mechanism of human hand. In human hand, grasp and grip are different terms: Human hand can grasp an object adaptively by individual pulling of each finger’s tendon. Once the fingers make contact with the object, the human hand can grip the object with a larger force by simultaneous pulling of the tendon of each finger. Inspired from this, we propose a mechanism decoupling flexion drive and force-magnification drive for a wire-driven robot hand. The flexion drive consists of electric motors pulling the wire of each finger to make adaptive movement of the robot hand (grasp). The force-magnification drive consist of a hydraulic cylinder that pulls the wire of each finger simultaneously (grip). We also propose adaptive grasp mechanism using spring linkage. It is possible to grasp the irregular objects of limited size without a complex control algorithm or sensor system. We experimentally verified that the grip force of the prototype robot hand exceeds 300N which is 10 times larger than the electric motor alone.
The parallel kinematic machine (PKM), which is applied Exechon mechanism, is efficiently used for manufacturing industry due to its agile movement, flexibility and high rigidity. On-Machine measurement (OMM) in high-dof manufacturing machines such as the PKM and five-axis machine tools has importantly used for processed part measurement, coordinate system set and machine performance evaluation. In this study, measurement and compensation of touch probe offset, which occurs measurement error of the OMM, are carried out for the PKM. A dependent rotational motion is occurred due to kinematic constraint, and causes non-constant offset of a touch probe. The dependent rotational motion is calculated via inverse kinematics analysis. The probe offset is accurately measured using a master ring with considering the analyzed dependent rotational motion angle. In addition, measurement procedure to eliminate the offset induced measurement error is presented. To verify the proposed technique, circular tests using a master ring and commercial touch probe on the PKM were performed. Circularity measurement deviation of a master was reduced 65% without the PKM’s kinematic error calibration.
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Sequential Measurement of Position-independent Geometric Errors in the Rotary and Spindle Axes of a Hybrid Parallel Kinematic Machine Seung-Han Yang, Dong-Mok Lee, Hoon-Hee Lee, Kwang-Il Lee International Journal of Precision Engineering and Manufacturing.2020; 21(12): 2391. CrossRef
Laparoscopic surgical instruments have been used widely since 1980s and they are still important tool to the medical field as the surgical robot systems spread. In this study we devised three types of motorized mechanism to reduce the user hand fatigue. We detailed the mechanism of each type and compared the performances with several indices such as a bending angle, response time and number of mechanical components. And also we show the movement relationships among the jaw joint, passive gimbal set and motors in the case of MPDG (Motor Drive with a Push Disk and Driven Disk of Gimbal Mechanism) type during the typical jaw joint motions. MTPS (Modified Two Parallel Semicircle Guide Mechanism) type excels others in response time and number of components while showing the increase of load and kinematic occlusion during the diagonal movement. MBDG (Motor Drive with a Ball-Screw, Link and Disk Type Gimbal Mechanism) type shows the medium level bending performance with slow response time and large number of components. Lastly MPDG type excels in jaw joint bending performance with an unstable rotation motion transfer between pushing disk and driven disk at the large disk rotation angle.
Reactors are needed to produce polymeric polymers as materials for OLED (Organic Light Emitting Diode). There are many types of reactors that assist in producing chemical reactions. One type, called a coil type, is a continuous reactor that has many advantages compared to other reactors. It can not only manufacture products continuously, but is cheaper and therefore cost efficient. A continuous coil type reactor was designed and manufactured for this study. A precise flow rate cannot be determined because of the numerous variables. An experimental flow rate is obtained when combining the following information: the valve opening angle, the revolution velocity of the screw and the temperature of the reaction. As a result, the study is considered that people who use this device will refer to this to control flow rate and time for reaction.
This paper presents a development process of an advertising accessory including a light guide to be applied to mobile devices. At first, this research is to design an optical part as a light guide to transmit the light more than 10% of the LED light from mobile devices. Secondly, it presents the mechanical design of the part to be applicable to size changes of mobile devices and to enduring external forces. By using ANSYS and OPTISWORKS, a preliminary design including to tune the applied material properties is performed to prevent from the failure of the component, to maintain the proper pressure for holding mobile devices with different thickness, and to obtain enough optical transmission efficiency. In addition, this paper introduces a manufacturing process for the advertising accessory with a chemical and mechanical polishing. In order to measure the performance of the manufactured accessory, here, measurement devices such as measuring the pressing force, luminance, and illuminance are also designed and fabricated. Several modifications are made for the purpose of improving the measured performance.
A simple and rapid method of fabricating Mg(OH)2 layer by chemical immersion was developed to improve the corrosion resistance of the magnesium alloy AZ31. The fabricated surface was superhydrophobic with a self-assembled monolayer coating of silane. The surface characteristics were evaluated by Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS) and X-ray Photoelectron Spectroscopy (XPS). The average water contact angle and sliding angle were determined to be 160° and 7° respectively as a result of wettability test. Potentiodynamic polarization indicated that both Mg(OH)2 layer and the thin layer of air were effective in improving anti-corrosion. This method which is efficient with regard to time and cost would be useful for magnesium industries and its application
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The mechanisms and advances in magnesium-based materials protection against corrosion by the superhydrophobic coatings Ludmila B. Boinovich, Kirill A. Emelyanenko, Alexandre M. Emelyanenko Surface and Coatings Technology.2024; 481: 130607. CrossRef
A pulsed-power source has the advantage of releasing a peak power over a short time interval. In this study, we implemented two types of such energy source, namely laser and dielectric break down power sources. We built the highpressure flow-output actuator utilizing such power sources in a micro-jet drug delivery system. We compared the jet speed from each power source and analyzed the drug penetration performance of the micro-jet injector. We found that hat the bubble growth rate caused by a dielectric breakdown power source per power input was three times faster than the laser power source. By using the micro-jet injector, we performed the insulin injection test using mouse models having diabetes mellitus to evaluate whether micro-jet injector has equivalent drug delivery performance when compared against conventional syringe-type injection.
In this study, a 10 kW horizontal-axis lift-type wind turbine is analyzed and verified. The three-bladed wind turbine is modeled and analyzed with FAST which is a multi-body dynamics code for a wind turbine. The turbine without any advanced over speed protection except an on/off control was simulated and experimentally verified. In the verification, the field test results were found to be well predicted by the simulation. Also, a side-furling system was proposed for the wind turbine without changing parameters of the current system much. From the dynamic simulation for verification, the furling system was found to work well up to 20 m/s with a modified torque control schedule. Although the proposed furling system could not be verified experimentally in the field, a similar 10 kW wind turbine whose experimental results are available in the literature was used for a verification. It was found from the simulation that the prediction from the simulation with the furling system was close to the experimental results in the literature.
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Development and Validation of Control Algorithm for Variable Speed Fixed Pitch Small Wind Turbine Donggeun Jeong, Taesu Jeon, Insu Paek, Deokjin Lim Energies.2023; 16(4): 2003. CrossRef
The energy saving effect of reactant plasma in Atomic Layer Deposition (ALD) of ultrathin solid oxide fuel cell electrolyte was examined by measuring electrical current in real time. Actuating a plasma generator led to a remarkable change in electric current and therefore a Plasma Enhanced ALD (PE-ALD) Yttria-Stabilized Zirconia (YSZ) supercycle demanded ~12% higher process energy than a Thermal ALD (T-ALD) YSZ supercycle. Nonetheless, because PE-ALD YSZ electrolyte providing higher growth rate and higher gas tightness needed 2 times smaller cycle number compared to T-ALD YSZ electrolyte, applying oxygen plasma in ALD of YSZ electrolyte resultantly reduced total process energy by ~44%.