• 한국정보전자통신기술학회논문지
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• 제14권5호
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• pp.369-374
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• 2021

최근에 건설되는 아파트는 주방이 빌트인 방식으로 만들어지므로 가스 호스가 싱크대 내부에 보이지 않게 만들어지므로 가스가 누출될 경우 싱크대 내부에 축적되어 가스 폭발로 이어질 수 있는 위험한 방식이다. 본 연구에서는 가스레인지와 중간밸브 사이에 연결된 호스가 싱크대 내부에 있어 가스 누출 검사를 할 수 없는 구조로 되어 있어 압력센서를 이용하여 가스누출을 검사를 쉽게 할 수 있는 밸브 시스템 연구하였다. 압력 측정 방법은 중간밸브와 가스레인지를 연결하는 호스의 압력을 측정하여 I2C통신 방식으로 데이터를 수집·분석 할 수 있도록 진행하였다. 또한 가정에 공급되는 가스압력계산은 대기압력에 가스계량기의 입구에서 가스게이지 압력 평균값 22.46mbar를 더 한 값으로 계산된 것에 대한 대기 압력 오차에 대한 규명 및 미세한 가스 누출 감지를 할 수 있도록 밸브 시스템을 개발하였다.

• 한국가스학회지
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• 제16권6호
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• pp.128-135
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• 2012

본 논문에서는 가스안전에 적합한 무선 ZigBee통신모듈과 스마트 홈 가스안전기기 및 관리시스템 개발하여 가스안전관리의 효율을 향상시키는 시스템과 시나리오를 제안하였다. 제안한 시스템은 마이컴가스미터, 자동식소화기, 감지기 및 월패드로 구성된다. 마이컴미터는 가스압력, 가스유량, 지진을 모니터링한다. 자동식소화기는 가연성 가스의 누출상태, $100^{\circ}C$(차단)와 $139^{\circ}C$(화재)의 온도를 측정하며, 감지기는 연기와 일산화탄소(CO)를 검지한다. 제안한 시스템에서 가스사용중 이상상태발생시 마이컴가스미터는 경보와 함께 내부밸브를 차단시키고, 자동식소화기는 중간가스밸브를 차단하거나 소화약재를 분사시킨다. 감지기는 연기와 CO를 감지할 경우 각각 신호를 발생시켜 후속조치를 취하게 한다. 가스안전기기와 센서들은 자동적으로 조치를 취하고 그 정보를 월패드로 전달한다. 월패드는 실시간 상황정보를 서버에게 전달하고 사용자는 웹이나 모바일 앱을 통하여 서버에 접속하여 가스의 상황정보를 확인하거나 관리할 수 있다. 본 연구에서는 스마트기반 가스안전 및 위험관리의 시나리오를 고안하고 현장적용시험을 통하여 그 효율성을 증명하였다.

• 한국자동차공학회논문집
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• 제24권2호
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• pp.169-182
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• 2016

This paper is the third investigation on the evaluation methods of flow characteristics in a steady flow bench. In the previous works, several assumptions used in the steady flow bench were examined and the flow characteristics were estimated both by the conventional impulse swirl meter and a particle image velocimetry at 1.75B position. From these works, it was concluded that the assumption of the solid rotation might cause serious problems and both of the eccentricity and the velocity profile distort the flow characteristics when using the ISM at 1.75B plane. Therefore, the understanding of the detail velocity profiles is very important to keep discussing the issues about the steady flow evaluation method. For this purpose, the planar velocity profiles were measure at 1.75B position by particle image velocimetry and the characteristics were examined according to the valve angles and lifts. The results show that the planar velocity profiles of 11, 16, $21^{\circ}$ valve angle heads according to the lift are similar to each other, however, that of $26^{\circ}$ angle is an exceptional case in the all aspects. In addition, the swirl behaviors are not apparent up to 6~8 mm lift under the $21^{\circ}$ angle and somewhat arranged motions are observed over the whole plane near the highest lift. At this point, the narrower the angle, the lower the lift at which the swirl motions become clear. On the other hands, when the angle is $26^{\circ}$, the center of swirl is always farthest from the cylinder center and only the indistinct swirl is observed even if at the highest lift. Also, all the swirl centers are quite apart from the cylinder center so that the effect of eccentricity may not be negligible at 1.75B regardless the valve angle. Related to the tangential velocity along with the radial direction, the bands of the velocity distribution are very wide and the mean velocities of cylinder center basis are lower than the velocity which is assumed in the ISM evaluation. Lastly, the mean tangential velocity profiles of swirl center basis are sometimes higher than that of ISM-assumed up to 0.6 non-dimensional distance less than 6mm lift, however, as the lift increases the profiles are different according to the angles and profile $11^{\circ}$ is the most closed to the ideal profile. Consequently, the real velocity profile is far from the assumption of ISM evaluation.

• 대한기계학회논문집B
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• 제24권9호
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• pp.1185-1194
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• 2000

The characteristics of intake port flow and engine performance with swirl ratio variance in a turbocharged D.I. diesel engine were studied in this paper. The intake port flow is important factor which have influence on the engine performance and exhaust emission because the properties in the injected fuel depend on the combustion characteristics. Through these experiments it can be expected to satisfy performance and emission by optimizing the main parameters; the swirl ratio of intake port, injection timing and compression ratio. The swirl ratio for ports was modified by hand-working and measured by impulse swirl meter. For the effects on performance and emission, the brake torque and brake specific fuel consumption were measured by engine dynamometer, NOx and smoke were measured by gas analyzer and smoke meter. The results of steady flow test are as follows; as the valve eccentricity ratio are closed to cylinder wall, the flow coefficient and swirl intensity are increased. Also we realized that there is a trade-off that the increase of swirl ratio decreases mean flow coefficient and increases the Gulf factor. And the optimum parameters to meet performance and emission through engine test are as follows; the swirl ratio 2.43, injection timing BTDC 13oCA and compression ratio 15.5.

• 한국자동차공학회논문집
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• 제24권2호
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• pp.242-254
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• 2016

This paper is the forth investigation on the evaluation methods of flow characteristics in a steady flow bench. In the previous works, it was concluded that the assumption of the solid rotation might cause serious problems and both of the eccentricity and the velocity profile distort the flow characteristics when using the ISM at 1.75B plane. Also particle image velocimetry (PIV) measurement at this position showed that the real velocity profile was far from the assumption of ISM evaluation. In this paper, the planar velocity profiles were measure from 1.75B to 6.00B position by PIV and the characteristics were examined according to the valve angles and lifts for further investigations about the effect of the position on the velocity profile. The results show that $26^{\circ}$ valve angle is always an unique exceptional case in all aspects. If the valve angle is $21^{\circ}$ and below, the planar velocity profiles according to the lift and the position are similar to each other, however, the tangential velocity curves along with the radial direction have common tendencies up to $16^{\circ}$ angle. Also the well arranged swirl behaviors are generally observed at the position above 3.00B and the velocity contour lines come closer to the concentric circle as the valve lift increases. In addition, the gradient of tangential velocity along with the radial direction from the swirl center becomes stable and constant as the position goes downstream. Concurrently the velocity gradient is larger to the eccentric direction of the center. In the meantime the tangential velocity curves along with the radial direction are irregular and various at 1.75B, however, they become regular and reach higher level as the evaluation position goes downstream. At this time the curves of 4.50B are the best fitted to the ideal one. On the other hand in an exceptional case, $26^{\circ}$, the velocity contours are very complicated over 6mm valve lift regardless the position and the gradient increases to the opposite direction of the eccentric center. Also, 6.00B is a best fitting position in the geometrical cylinder center base. With respect to the swirl center, the distribution range of centers for 1.75B is different to that for the other positions and the eccentricities of this plane are larger regardless the valve angle. After 1.75B, there is no certain tendency in the center position change according to the valve angle and lift. Additionally, the eccentricities are not sufficiently small to neglecting the effect on ISM measurement.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집E
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• pp.595-600
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• 2001

Thermal mass flow meter(TMF) and thermal mass flow controller(MFC) were used to measure and to control the mass flow rate of gases. TMF and MFC were designed for specified working pressure and gas. For the case of different working pressure and gases, the flow rate measurement accuracy decreased dramatically. In this study, a TMF and MFC was tested with three different gases and pressure range from 0.2 MPa up to 1.0 MPa. Effect of specific heat causes to increase flow measurement error as much as ratio of specific heat compared with reference gas. Changing of pressure causes to increase flow rate measurement error about -0.2% as the working pressure decreased 0.1 MPa. Response time of MFC was below 3.12 s for the case of increasing of flow rate. But the response time was increased up to 6.92 s for the case of decreasing of flow rate. When the solenoid valve was fully closed, a initial delay time of output of MFC was increased up to 1.36 s.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.809-812
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• 2005

Battery is an energetic collector of solar cell system. Battery which is used in the system must have many qualities in the followings. The battery must be "Deep Cycle Battery" type. In addition, the battery is Cleary indicated the percentage of DOD. The indication of DOD is used for calculation other valve used in solar cell system. Currently, the percentage of DOD of battery is fixed by battery manufacture. If users would like to calculate is introduced % DOD, the users have to check the battery at least 12 months. This article is introduced battery deep of discharge meter by using theory of lead acid battery under deep cycle type and including the theory of DC. Current and internal resistance of battery. The data used for analyzing are collected according to the theories. The data will be calculated by monitor unit and controller systems.

• 전자공학회논문지SC
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• 제48권3호
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• pp.13-20
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• 2011

본 논문에서는 무선 ZigBee 통신모듈과 지능형 가스안전기기를 이용하여 u-홈 가스안전관리시스템을 개발하여 가스안전관리의 효율을 향상시킬 수 있는 시스템을 제안하고자 한다. 제안한 시스템은 마이컴가스미터, 자동식소화기, 감지기 및 월패드로 구성된다. 마이컴미터는 가스압력, 가스유량, 지진을 모니터링하고, 자동식소화기는 가연성 가스의 누출상태와 $100^{\circ}C$ 와 $130^{\circ}C$의 온도를 측정한다. 그리고 감지기는 연기와 일산화탄소(CO)를 검지한다. 제안한 시스템은 가스사용중 이상상태발생시 마이컴가스미터는 경보와 함께 내부밸브를 차단시키고, 자동식소화기는 중간가스밸브를 차단하거나 소화약재를 분사시킨다. 감지기는 연기와 CO를 감지할 경우 각각 신호를 발생시킨다. 가스안전기기와 센서들은 지능적 조치를 취하고 그 정보를 월패드로 전달한다. 월패드는 상황정보를 실시간으로 서버에게 전달하고 사용자는 웹기반으로 서버에 접속하여 가스의 상황정보를 확인하거나 관리할 수 있다. 본 논문은 가스안전 및 위험관리의 시나리오를 고안하고 실험을 통하여 그 효용성을 증명하였다.

• 한국초전도ㆍ저온공학회논문지
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• 제5권1호
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• pp.133-135
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• 2003

Cryogenic systems are requirement for the operation of HTS power cables. In general, HTS power cables require temperature below 77K, a temperature that can be achieved from the liquid nitrogen at latm or sub-cooled LN2 above latm. HTS power cable needs sufficient refrigeration to overcome its low temperature heat loading. This loading typically cones in two forms : (1) heat leaks from the surroundings and (2) internal heat generation. This paper explains the cooling test system of 10m HTS power cable. This system is composed of storage dewar, auto fill system, core cryostat and cold-box. Storage dewar is a LN2 storage tank and auto fill system is a LN2 supply device to the sub-cooler, Core cryostat is a LN2 flow line. Cold box is a control unit of temperature and flow rate. It is composed of control valve, flow meter, sub-cooler and circulation pump, etc..

• 한국공작기계학회논문집
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• 제15권1호
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• pp.56-62
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• 2006

An experimental investigation was performed to study the characteristics of ER(Electro-Rheological) fluid flow in a horizontal rectangular tube with or without D.C voltage. To determine some characteristics of the ER flow, 2D PIV(Particle Image Velocimetry) technique is employed for velocity measurement. This research found the mean velocity distribution with 0kV/mm, 1.0kV/mm and 1.5kV/mm for Re = 0, 0.62, 1.29 and 2.26. When the strength of the electric field increased, the cluster of ERF are clearly strong along the test tube and the flow rate decreased. In this study, the rheology of ER fluid stagnating or flowing through a dispersion meter will be investigated by PIV method. And then the ER effect, which appears at the ER valves and their appliance will be visualized.