• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.4
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• pp.68-84
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• 2000

A study to reduce the transient torque in shifting in automatic transmission has been very important issue. Recently it is really dominant to decrease the torque by using independent-acting hydraulic circuit because we can control the clutch pressure actively and elaborately. So we design the new hydraulic circuit to control the clutches in automatic transmission and make the module library of computer simulations, We apply the results to GM model automatic transmission and carry out 1longrightarrow4 shifting simulations. By this work we recognize the capability of active and elaborate clutch pressure control using new hydraulic circuit. In addition We develop the tool to simulate the powertrain system. It is easier to update and exchange the subsystem model or parameters than conventional simulation tools.

• 한국생물공학회:학술대회논문집
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• 2005.04a
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• pp.351-354
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• 2005

A new isolation and purification method was developed aiming at increasing yield and purity for homoharringtonine. This method was a simple andefficient procedures, for the isolation and purification of homoharringtonine from Cephalotaxus koreana, consisting of solvent extraction, adsorbent treatment, low-pressure chromatography, and high performance liquid chromatography (HPLC). The crude homoharringtonine was efficiently pre-purified adequately to perform HPLC through a combination withadsorbent treatment and low-pressure chromatogaphy. The homoharringtonine can be simply obtained with high purity and yield from crude homoharringtonine by HPLC. Purified homoharringtonine was characterized.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.1091-1096
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• 2004

It is necessary to consider the stability, economic environmental-friendly problems by the development of the road, supply of the automobile, environmental problem as designing the exhaust system. To reduce the noise and the vibration of the automobile. The need for stricter regulation limits emission and demand for lower fuel comsumption. According to motor vehicle company develop variable type muffler, dual muffler and active intelligence exhaust system unit. Improvement in engine performance and fuel consumption for demand information of pressure fraction and heat characteristics. To be able to determine these factor for we experiment on each case of exhaust system unit. In this study, in order to establish the optimized conditions design factors which are taking many performance as the variable valve, it shows how the standard performance and the additional element of the exhaust system effects on the engine performance.

• Journal of the Korean Society of Combustion
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• v.3 no.1
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• pp.1-10
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• 1998

Lots of techniques are adopted for a flame stabilization and a high-load combustion. But the techniques being used were passive control method which have to change combustor shape like pilot flame, flame stabilizer, pressure profile, etc. Active control method which is not necessary to transform its shape is employed. Acoustical excitation is broadly used for its convenience in changing frequency and intensity. Both acoustical excitation and flame stabilizers were adopted to study their relationship. So, we investigated flammability limits. Flame visualization. And mean temperature in the condition of various frequencies, intensities, and flame stabilizers. As a consequence, flammability limit were advanced in acoustically excited flame at some frequencies. Coherent structure was extended to the downstream region through acoustical excitation and a size of vortice was curtailed. Also width of recirculation zone was magnified. In addition, Effects of acoustical excitation was stood out at 25mm flame stabilizer rather than another ones.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.12 no.2
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• pp.25-33
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• 2016

The thermal stratification phenomenon in the nuclear power plant can cause abnormal deformation of the piping, contact with the support, damage to the support system. Repetition of the thermal stratification phenomenon or variation of the thermal boundary layer can cause thermal fatigue. Thermal stratification phenomenon in nuclear power plants is still an ongoing issue and active research has been carried out. In this paper, the current situation in Korean nuclear power plants is described, followed by the status of research and the future problems on the thermal stratification phenomenon in Korea.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.3
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• pp.19-26
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• 2004

A prior fundamental study was executed using a constant volume chamber to improve the burning properties of lean pre-mixture by the injection of active radicals generated in the sub-chamber. In consequence, RI method shows remarkable progress in the aspects of burning velocity and combustible lean limit compared with SI method. In this study, the necessary additional works have been performed to be based on the former results. We changed parameters as the initial temperature and the initial pressure of mixture. And the effects of residual gas at issue in a real engine were investigated. As a result, the effects of initial temperature were significant, but on the other hand, those of initial pressure were slight. The correlation of passage hole number between overall passage hole area was grasped. And the more detailed analysis is required on residual gas.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1996.11a
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• pp.27-41
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• 1996

In this study the heat transfer and fluid flow of the molten pool in stationary gas tungsten arc welding using argon shielding gas were investigated. Transporting phenomena from the welding arc to the base material surface, such as current density, heat flux, arc pressure and shear stress acting on the weld pool surface, were taken from the simulation results of the corresponding welding arc. Various driving forces for the weld pool convection were considered, self-induced electromagnetic, surface tension, buoyancy, and impinging plasma arc forces. Furthermore, the effect of surface depression due to the arc pressure acting on the molten pool surface was considered. Because fusion boundary has a curved and unknown shape during welding, a boundary-fitted coordinate system was adopted to precisely describe the boundary for the momentum equation. The numerical model was applied to AISI 304 stainless steel and compared with the experimental results.

• Smart Structures and Systems
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• v.19 no.6
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• pp.615-624
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• 2017

This paper experimentally investigates the feasibility of harvesting vibration energy from whistles using piezoelectric materials. The end goal of this research is to generate sufficient power from the whistle to power a small radio transmitter to relay a basic signal - for example, a distress call. First, the paper discusses the current literature in energy harvesting from acoustic resonance. Next, the concept of an active whistle is presented. Next, results from energy harvesting experiments conducted on conventional and ultrasonic whistles undergoing human-actuation and actuation by a pressure-regulated air supply are presented. The maximum power density of the conventional whistle actuated by a human at 100 dB sound pressure level is $98.1{\mu}W/cm^3$.

• Journal of Pharmaceutical Investigation
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• v.32 no.4
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• pp.241-258
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• 2002

Such osmotic drug delivery systems are based on osmosis, the diffusion of water transversely from a medium with a low osmotic pressure to a medium with a high osmotic pressure for the controlled delivery of active agents. In this review, U.S. Patents on osmotic drug delivery analyze 261 patents until December 2001. These devices form now a major market of drug delivery products. Because of their advantage and innovate idea, it appears that the future of oral drug delivery mark,εt in Korea is promising.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.103.6-103
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• 2001

Glaucoma is an eye disease which is caused by abnormal high IOP (Intra Ocular Pressure) in the eye. High IOP is caused by the aqueous humor which is produced consistently but not drained due to the malfunction of the trabecular system which has a role of draining the aqueous humor into the venous system. Currently, there are some methods to treat glaucoma, Among these, the use of implants is increasing in these days due to many problems in other methods. However, conventional implants are passive implants and have critical disadvantage. Therefore, it is needed to develop a new implant using MEMS structure which is capable of controlling the IOP actively and copes with personal difference of patients. An active glaucoma implant consists of the valve actuator, pressure sensor, controller, and power supply. In this paper the valve actuator is considered. We make experiments and simulations with the fabricated ...