• Journal of Pharmaceutical Investigation
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• v.36 no.1
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• pp.39-44
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• 2006

Tamsulosin or a salt thereof such as its hydrochloride salt has been known to have an adrenaline ${\alpha}$ receptor blocking action for urethra and prostate areas. It has been widely used as a drug which lowers the prostate pressure and improves urinary disturbance accompanied by prostate-grand enlargement, thus for the treatment of prostatic hyperplasia. To avoid dose-dependent side effects of tamsulosin upon oral administration, the development of sustained-release delivery system is essentially required, that can maintain therapeutic drug levels for a longer period of time. The aim of this study was therefore to formulate sustained-release tamsulosin granules and assess their formulation variables. We designed entric coated sustained-release tamsulosin granules for this purpose. Nano-pores in the outer controlled release membrane were needed in order to obtain initial tamsulosin release even in an acidic environment such as gastric region. In our sustained release osmotic granule system, hydroxypropylmethylcellulose in a drug-containing layer was used as a rate controller. The drug-containing granules were coated with hydroxypropylmethylcellulose phthalate (HPMCP) and Eudragit, along with glycerol triacetate as an aqueous nano-pore former. The release of tamsulosin depended heavily on the type of Eudragit such as RS, RL, NE 30D, used in the formulation of controlled release layer. These results obtained clearly suggest that the sustained-release oral delivery system for tamsulosin could be designed with satisfying drug release profile approved by the Korean Food and Drug Administration.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.12
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• pp.1128-1138
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• 2010

One of the typical problems in the precise vibration is resonance characteristics at low frequency disturbance due to a heavy mass. An electro-magnetic(EM) air spring is a kind of vibration control unit and active isolator. The EM air spring in this study aims at removing the low frequency resonance for semiconductor manufacturing. The mechanical and electronic parts in the active isolator are designed to operate under a weight of 2.5 tons. The EM spring is floated using air pressure in a pneumatic elastic chamber and actuated by EM levitation force. The actuator consists of a EM coil and a permanent magnetic plate which are installed inside of the chamber. An air mount was constructed for the experiment with a stone surface plate, 4 active air springs, 4 gap sensors, a DSP controller, and a multi-channel power amp. A PD control method and operating logic was applied to the DSP. Simulation using 1/4 model was carried out and compared with the experiments. The time duration and maximum peak at resonance frequency can be reduced sharply by the proposed system. The results show that the active system can avoid the resonance caused by the natural frequency of the passive system.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.1
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• pp.85-92
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• 2005

The motion of flexseal bearing for movable nozzle has inherent nonlinear characteristics due to floating rotational center and compression by combustion pressure of solid motor. To perform precise attitude control in spite of these characteristics, the TVC actuation system requires counter potentiometer as an extra position feedback sensor of movable nozzle to form a compensated control loop. The prototype TVC actuation system, test equipments and compensated controller are newly designed, manufactured and tested in consideration of counter potentiometer. On the basis of integration test, the inherent characteristics of movable nozzle and control characteristics of its TVC actuation system are analyzed and summarized in this paper.

• Journal of the Korean Solar Energy Society
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• v.35 no.4
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• pp.1-7
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• 2015

The operation of the natural circulation type solar heating systems with facade integrated collector was analyzed by experiment. Two different types of flat plate solar collectors were used for these experiments. One was for the normal flat plate solar collector with the size of 1m*2m and the other was for the large size solar collector with $4m^2$(1m*4m). The experiments were carried out to investigate the effect of the series or parallel connection method on the performance of the collectors. As a result, the solar thermal system which is installed on the wall or facade would be applicable for the natural circulation type if the system design reflects various parameters, including collector connecting method(series or parallel), to provide enough vertical height between collector and storage tank, and to reduce pressure loss due to collector and piping network, etc. The natural circulation type of solar thermal system as proposed in this study can increase the system reliability by removing or minimizing the use of the components such as pump, controller, sensors which may cause serious troubles of the system for a long-time operation

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.418-423
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• 2009

Unlike domestic railway transportation system in which majority of station are equipped with gate access controller and ticket office, it has been a very common practice in overseas railway transit or railway station that they use a pressure door mat, infrared-sensors or CCTV cameras so as to automatically determine the number of passenger onboard and alight and to reflect the information to their business (i.e., deployment of vehicles and human resources). The data collected by the automatic passenger counting (APC) system provides methods how to obtain the information about the number of passenger using the vehicles on the basis of date, time and stop(station) which enables large-scaled transit company to create profits through effective vehicle deployment and management of their employees. This paper addresses the basic features of the automatic passenger counting system using infrared sensor and describes those of the extended APC system in conjunction with wireless technologies such as GPS, WLAN or Cellular network.

• Journal of Korea Game Society
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• v.11 no.6
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• pp.33-42
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• 2011

In this study, game-aided human life type game design method is suggested. It mainly deals with the permissiveness of the game rules and coenesthesia of the game that are fitted with the agility of the elders such as the performance of a selective response. And 'Rolling hoops Balance Game' has been implemented by applying the game-aided human life type game. Since the pressure sensors are installed on each parts of the chair type game controller, to play the game, a gamer simply uses her hands and feet to press the sensors without requirements of the complex movements. The goal of the game are the leg muscles strength and improvement of the body balancing ability. In addition, the game graphics consists of sensory stimuli package(Namazi, Haynes, reminiscence therapy, 1994) to make friendly mood for elders. We have tested 50 elders who were more than 65 years old. 74% of them answered they were satisfied totally for the game play. It is a meaningful result that 88% of participants replied they would like to play the game again.

• Journal of Aerospace System Engineering
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• v.11 no.5
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• pp.42-49
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• 2017

The solid rocket motor(SRM) consists of a motor case, igniter, propellants, nozzle, insulation, controller, and driving device. The liquid rocket propulsion systems(LRPSs) cools the nozzle by the fuel and oxidizer but SRM does not cool the nozzle. The nozzle of SRM is high temperature condition and high velocity condition so occurs the erosion by combustion gas. This erosion occurs the change of nozzle throat and reduces thrust performance of rocket. The material of Rocket nozzle is minimization of erosion and insulation effect and endure the shear force, high temperature and high pressure. The purpose of this study is to investigate the erosion characteristics of solid rocket nozzles by each combustion time. Through the structure inspection of Graphite and C-C composite, identify the characteristics of the microstructure before and after erosion.

• Environmental Analysis Health and Toxicology
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• v.27
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• pp.12.1-12.8
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• 2012

Objectives: The aim of this study was to identify the health and environmental risk factors of air contaminants that influence environmental and respiratory diseases in Gyeongju, Pohang and Ulsan in South Korea, with a focus on volatile organic compounds (VOCs). Methods: Samples were collected by instantaneous negative pressure by opening the injection valve in the canister at a fixed height of 1 to 1.5 m. The sample that was condensed in $-150^{\circ}C$ was heated to $180^{\circ}C$ in sample pre-concentration trap using a 6-port switching valve and it was injected to a gas chromatography column. The injection quantity of samples was precisely controlled using an electronic flow controller equipped in the gas chromatography-mass spectrometer. Results: The quantity of the VOC emissions in the industrial area was 1.5 to 2 times higher than that in the non-industrial area. With regards to the aromatic hydrocarbons, toluene was detected at the highest level of 22.01 ppb in Ulsan, and chloroform was the halogenated hydrocarbons with the highest level of 10.19 ppb in Pohang. The emission of toluene was shown to be very important, as it accounted for more than 30% of the total aromatic hydrocarbon concentration. Conclusions: It was considered that benzene in terms of the cancer-causing grade standard, toluene in terms of the emission quantity, and chloroform and styrene in terms of their grades and emission quantities should be selected for priority measurement substances.

• Transactions of the Korean Society of Automotive Engineers
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• v.24 no.5
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• pp.581-587
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• 2016

Braking is a basic and an important safety feature for all vehicles, and the final braking performance of a vehicle is determined by the vehicle's ABS performance and tire performance. However, the combination of excellent ABS and tires will not always ensure good braking performance. This is due to the fact that tire performance has non-linearity and uncertainty in predicting the repeated increase and decrease of wheel slip when activating the ABS, thus increasing the uncertainty of tire performance prediction. Furthermore, existing studies predicted braking performance after using an ABS that used a wheel slip control as a controller, which was different from an actual vehicle's ABS that controlled angular acceleration, therefore causing a decrease in the prediction accuracy of the braking performance. This paper reverse-designed the ABS that controlled angular acceleration based on the information on brake pressure, etc., which were obtained from vehicle tests, and established a braking performance prediction analysis model by combining a multi-body dynamics(MBD) vehicle model and a magic formula(MF) tire model. The established analysis model was verified after comparing it with the results of the braking tests of an actual vehicle. Using this analysis model, this study analyzed the braking effect by vehicle factor, and finally designed a tire that had optimized braking performance. As a result of this study, it was possible to design the MF tire model whose braking performance improved by 9.2 %.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.11
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• pp.1131-1139
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• 2009

Combustion Instabilities are caused by a coupling between acoustic waves and unsteady heat release. They can be eliminated using passive controller such as a Helmholtz resonator. But, Helmholtz resonator is normally only effective over a narrow frequency range. In this work, Helmholtz resonator is applied for reducing the combustion oscillations and we vary the Helmholtz resonator volume using piston in oder to tune in the wide range of operating conditions. As the result, it is found that the dominant combustion oscillations can be largely reduced by optimizing the size of resonator volume. And, interesting relation for phase difference of dynamic pressure both combustor and the helmholtz resonator are presented in this paper. Also, we investigate semi-active control using Helmholtz equation and phase difference.