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Buoyancy Control of a Scientific Submersible Using Variable Ballast System
Mojiz Abbas Trimzi,Young-Bog Ham,Byeung-Cheol An,Gi-Tae Lee,Jung-Ho Park,So-Nam Yun 유공압건설기계학회 2015 유공압건설기계학회 학술대회논문집 Vol.2015 No.10
The magnitude of buoyant force always equals the weight of liquid displaced. On basis of this principle the buoyancy of submersible has been calculated by using variable ballast tank. When the seawater is pumped into variable ballast tank the density of submersible is increased, as a result submersible dives deep into water. When water is pumped out from ballast tank and air replaces that volume, the submersible dives out towards surface because of decreased density. In this paper using sea water hydraulics, a trajectory profile showing position of deep-diving and rising submersible is produced. It is proposed that air to water ratio in variable ballast tank can effectively control the buoyancy of a submersible making it useful for deep sea exploration.
Numerical analysis and simulation of an impulse driven piezoelectric needle-free jet injector
Mojiz Abbas Trimzi,함영복,안병철,박중호,윤소남 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.8
Transdermal drug delivery using needle free jet injections entails ejection of a liquid drug through a fine nozzle at elevated pressure, thus generating a narrow high-velocity fluid jet readily penetrable into skin and tissue. The idea of a simple and compact piezoelectric powered needle free injector (NFI) is introduced in this article, which offers electric control of injection volume in microliters. An impulse of up to 3500 N-s or more is generated by the multilayer piezoelectric actuator to drive the needle-free injector. The governing equations for the force and mass balance over the syringe plunger were derived to represent the driving mechanism for a compact needlefree injector. Furthermore, simulation was carried out to witness the effect of variation in parameters like impulse force, nozzle diameter and nozzle length on the injection dynamics, and the results prove the dependence of injection characteristics on aforementioned parameters, respectively. Finally, the specifications for fabrication of 10 μl volume delivering piezoelectric-impulse driven needle-free injector were obtained through analysis of multiple simulation results.
Mojiz Abbas Trimzi(모지즈압바스),Y. B. Ham(함영복),H. A. Khan,B. C. An(안병철),J. H. Park(박중호),S. N. Yun(윤소남) 유공압건설기계학회 2017 유공압건설기계학회 학술대회논문집 Vol.2017 No.11
Applications of pressure intensifiers have been increased due to their energy efficient abilities. High intensity of pressure can be generated at the cost of relatively low inlet pressure fluid. This paper describes a model of self-reciprocating pressure intensifier which reciprocates due to air-operated pilot valve. Small orifices are introduced in the inlet of pressure intensifier to control the repeatability of the piston with optimal time delay. The reciprocations are influenced by the variation in size of orifice. Model of pressure intensifier is simulated using MATLAB Simulink and pressure profile for various orifices are plotted against time. Time delay for pressure built up against each orifice is also measured experimentally. Simulation and experimental results are compared to verify the phenomena of time delay. For both, simulation and experiment, time delay has inverse relation with orifice diameters. From simulation and experimental results, best orifice size is chosen for reliable self-reciprocations of pressure intensifiers with minimum time delay.
Simulation study of pressure change between cryogenic reservoir and pump
Byeung-Cheol An,함영복,Mojiz Abbas Trimzi,윤소남,박중호 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.2
Supercritical hydrogen storage tanks are one of the most promising hydrogen storage technologies. When liquefied hydrogen is pressurized by a cryogenic high-pressure reciprocating pump, supercritical hydrogen is produced. The most important element for supercritical hydrogen production is the management of the net positive inlet pressure (NPIP) of the cryogenic high-pressure reciprocating pump. This paper presents a numerical analysis model for predicting the NPIP of cryogenic high-pressure reciprocating pump systems using liquid nitrogen instead of hydrogen as a medium for the preliminary study of supercritical hydrogen production. An algorithm was developed to compute the pressure of a two-phase fluid in a cryo-reservoir, where boil-off gas is generated and liquid nitrogen is reduced via a pump. The waiting time to guarantee the initial pressure and the available time of the pump were simulated, and an available pump flow rate depending on the initial pressure has been confirmed.
Design of the ball-type check valve for Plunger-type high pressure volumetric seawater pump
Byeung-Cheol An,Young-Bog Ham,Mojiz Abbas Trimzi,Gi-Tae Lee,Jung-Ho Park,So-Nam Yun 유공압건설기계학회 2015 유공압건설기계학회 학술대회논문집 Vol.2015 No.10
Since the fluid pressure is applied to open-close process, the ball-type check valve is suitable in the high pressure condition. Especially, it is essential for ball-type check valve to design the response speed related with ball size, ball mass, flow rate from pump. Flow rate defines the closing time. And the closing time must to shorter than the stroke time for plunger. In this paper, we suppose the equation to calculate the response speed, and then we applied this equation to the check valve really being used. Based on this equation, the check valve will have been designed.
함영복(Young-Bog Ham),안병철(Byeung-Cheol An),Mojiz Abbas Trimzi,김종대(Jong-Dae Kim),이기태(Gi-Tae Lee),박중호(Jung-Ho park),윤소남(So-Nam Yun) 대한기계학회 2016 大韓機械學會論文集B Vol.40 No.10
마이크로 인젝션을 바이오분야에 적용하기 위해 고압생성을 통해 침투하는 방법을 채택하였다. 그러나 고압의 액체를 인젝션 할 경우 그 양을 미세하게 하기 어렵다. 이러한 문제를 해결하기 위해는 고속으로 동작하는 개폐밸브에 의한 방법이 있다. 본 연구에서는 수백 Hz로 동작가능한 압전 액추에이터로 구성된 개폐밸브를 적용하여 실험하였다. 압전밸브를 구동하는 파형을 다양하게 조절하고 노즐의 구조에 의한 영향을 알아보기 위해 5가지 서로 다른 치수의 노즐을 제작하였다. 다양한 노즐과 구동파형 변수를 조절하면서 무엇이 인젝션 볼륨과 인젝션 힘에 큰 영향을 미치는지 확인하였다. 이 실험을 통해, 인젝션 볼륨을 줄이고 인젝션 힘을 증가시키는 방법을 알아냈고 목표치가 있다면 그에 맞는 다양한 값을 결정할 수 있게 되었다. It is essential for micro jet injectors in the biomedical sector to operate under high pressure. High pressure injection, however, is accompanied by high volumes. On/Off valves that can be operated at high speeds have been used to address this problem. In this research, piezoelectric actuators which have a response frequency of the order of hundreds of kilohertz were used as the On/Off valve and experiments were applied. Researchers developed a controller to precisely manipulate the piezoelectric valve with various waveforms. They also fabricated five types of nozzles to consider the effect of nozzle type on injection. This allowed researchers to manipulate and confirm factors that can affect the injection volume and force. Results of this experiment have shown how to decrease the injection volume and increase the injection force. and it is predicted that the optimized injection volume and force value can be determined depending on the skin type.