• Journal of Korean Society of Environmental Engineers
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• v.34 no.12
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• pp.863-870
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• 2012

The market trends of automatic meter reading associated with smart water meters were investigated. Also, recent developments and field applications of key technology for automatic meter reading associated with smart water meters were analyzed. Smart water meters have been manufactured mostly in United States and Europe and have been expanded their business to Asia. Integrated water management system combining with the additional functions such as real-time consumption metering, cost notification, water conservation, leak detection, water quality monitoring, and flow control have been operated in automatic meter reading. Both water quality and quantity data measured from smart water meters and sensors were transferred to data concentration units through neighborhood area network, and then were transferred to integrated server through wide area network. The data transfer methods were determined by comprehensively considering urban scale, density of smart water meters, power supply and network topologies. Common data collection methods such as fixed network to data concentation units, vehicles drive by, people walk by, and drone fly by have been applied. The automatic meter reading associated with smart water meters are spread throughout the world, and both water and energy savings result in saving the money and reducing the greenhouse gases emission.

• Journal of Aerospace System Engineering
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• v.16 no.3
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• pp.84-92
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• 2022

The electro-hydrostatic actuator (EHA) recently has been used in flight control fields for aircraft because of its benefits of minimizing oil leakage and weight, improving safety, and etc. while independently operating the hydraulic power source and eliminating complex hydraulic piping. The aircraft of which EHA is installed inside, has the thermal management issue of EHA, because of its limited cooling source as compared with the aircraft which installs the traditional central hydraulic system. So, the thermal analysis model which predicts the thermal characteristics of EHA, is required to resolve this thermal management issue. In this study, an oil circulation circuit inside the hydraulic power module comprised of hydraulic pump and electrical motor for EHA was applied. This is for the purpose of developing the internal rotary group of hydraulic power module, which operates under the conditions of high rotation speed and hydraulic pressure. After formulating an appropriate thermal analysis model, the thermal analysis results with oil cooled or no oil cooled hydraulic control module were compared and reviewed, for the purpose of predicting the thermal characteristics of EHA.

• Korean Journal of Agricultural Science
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• v.36 no.1
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• pp.73-85
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• 2009

An investigation was conducted to get the basic data for establishing structural safety and environmental management of tomato greenhouses in Chungnam region. The contents of the investigation consisted of actual state of greenhouse structures and environmental control facilities. Most of greenhouses were arch type single-span plastic houses and they had too low height for growing tomatoes. Frameworks of multi-span greenhouses were suitable, but those of single-span were mostly insufficient. Every greenhouse had thermal curtain movable or covering fixed inside the greenhouse for energy saving, and heating facilities were mostly warm air heater. Irrigation facilities were mostly drip tube and controlled by manual operation or timer. Almost all of the greenhouses didn't install high level of environmental control facilities such as ventilator, air circulation fan, $CO_2$ fertilizer, insect screen, supplemental light, and cooling device.

• Clean Technology
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• v.21 no.3
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• pp.191-199
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• 2015

The SO_x emission from the ship diesel engines will do a negative influence to the human health and the environment. To reduce the negative environmental effect of the SO_x emission caused by the high traffic of ship movements, the SECA (SO_x emission control area) has been set on several province around world to carry out the severe emissions control and to meet the emissions control standard. To cut down the SO_x emission from the ships, the wet type scrubber is being used widely. In this work, we prepared a numerical model to simulate the spray type scrubber to study the motion of liquid droplets in the flow of the scrubber. For the analysis, the CFD (computational fluid dynamics) method was adopted. As a special topic of the study, we designed the wave plate type of mist eliminator to check the carry over of the uncontrolled water droplet to the exhaust. Numerical analysis is divided into two stages. At the first stage, the analysis was done on the basic scrubber without the mist eliminator, and then the second stage of analysis was done on the scrubber with the mist eliminator on several condition to check and compare with the basic scrubber. On the condition of the basic scrubber, 42.0% of the distributed water droplets were carried over to the exhaust. But by adding the designed droplet eliminator at the exhaust of the scrubber, only 3.4% of the distributed water droplets supplied to the scrubber was emitted to the atmosphere.

• Journal of the Korean Society of Propulsion Engineers
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• v.18 no.1
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• pp.91-96
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• 2014

KSLV-I (Korea Space Launch Vehicle-I) upper stage KM (Kick Motor) is a solid propulsion system which consists of igniter, SAD (Safety Arming Device), composite case, and submerged nozzle capable of TVC (Thrust Vector Control) actuation. Each subsystem of KM fulfilled development requirements for achieving a flight mission successfully. We confirmed the successful development of KM from the $3^{rd}$ flight test results of NARO on January 30, 2013. This article deals with the requirements of KM and the results on configuration management, mass variation, thrust axis alignment, and major test results and so on.

• Aerospace Engineering and Technology
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• v.9 no.2
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• pp.51-56
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• 2010

There are two main software in COMS ground station at the normal mode operation - stationkeeping and wheel off-loading. In this paper, ground software validation test for wheel off-loading is summarized and described. The wheel off-loading was performed the design change from E3000 heritage and analyzed. The wheel off-loading of ground software has two part; one is wheel off-loading management for parameters change at the thruster set switching time and the other is wheel off-loading set-point being sent to satellite for the reference momentum.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.1
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• pp.125-132
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• 2001

This paper proposes integrated safety diagnosis system of motor used in a ship. It carried out the safety diagnosis for insulation-resistor and current. The motor exposed to sea breeze and oil all the time is able to have problems as a over-current, reduction of the insulation-resistor and so on. These problems impact on the safety navigation, and occur a heavy casualties and loss of property. The proposed system is able to sense error of the motor before a accident occur, by verifying and controlling value of the insulation-resistor and current in working area or control room. The validity of the proposed system is verified through experiment results on the 3-Phase induction motor.

• Proceedings of the KIEE Conference
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• 2005.11b
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• pp.334-336
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• 2005

최근 생활수준의 향상과 정보통신 산업의 급속한 발전으로 인하여 전 세계적으로 전력품질에 대한 관심이 높아져, 각종 전력품질 개선장치로부터 최적 공급시스템에 이르기까지 다양한 각도에서 전력품질을 향상하기 위한 연구개발이 수행되고 있으며, 특히 정보통신기기 및 정밀제어기기 등의 보급증가로 전압품질에 대한 관심이 높아져가고 있다. 또한 전력소비는 증가하고 있지만 환경문제, 부지확보 문제로 인한 대형 발전 설비의 확충이 어렵고, 전력산업 구조개편으로 인해 분산전원의 도입이 적극 검토되고 있다. 지금까지 배전계통의 전압 관리는 배전용변전소 ULTC(Under Load Tap Changer)와 고압배전선로의 주상변압기에 의해 조정되어 왔다. 하지만 배전용변전소와 고압배전선로의 선로전압조정장치가 서로 독립적으로 운용되고 있기 때문에 선로전압조정장치의 효율성이 떨어지고 있는 실정이다. 또한 분산전원이 도입 한계량에 대한 연구도 지속적으로 이루어지고 있다. 따라서 본 논문에서는 배전계통에서의 최적 전압조정을 위한 전압조정 장치와 분산전원의 도입한계량의 협조 운용 방안을 제시하고자 한다.[1]

• Proceedings of the KIEE Conference
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• 2004.11d
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• pp.10-13
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• 2004

현재 고도의 정보화 사회에서는 계측기 및 정보통신기기의 발달로 정확한 신뢰성이 요구되고 있으나, 정전이나 순간적 전압강하와 같은 전력장애의 요인은 산업에 막대한 영향을 미치므로 경제적 손실 등의 치명적인 피해를 준다. 이 문제를 해결하는 방안으로 무정전전원장치(UPS : Uninterruptible Power Supply)의 필요성이 요구되는 현실입니다. 그러나 UPS을 사용함으로써 문제점도 야기되고 있는 주요 원인은 밧데리의 불량과 교체에 따른 환경적인 문제가 대두되고 있는 헌상입니다. 문제점을 해소하기 위한 방안으로 축전지없이 정전을 보상하는 방식을 채택시 축전지 설치장소 확보, 운영관리, 교체 등에 따른 경제적 손실을 크게 줄일 수 있으며, 또한 축전지 미사용으로 인한 환경공해 문제가 해결 할 수 있다. 이러한 문제점을 해결하고자 PS 장비의 효율성과 신뢰성 모두가 향상되고 또한 장비의 연간 유지보수 비용 절감 및 환경 공해로부터 문제를 해소 할 수 있는 다이나믹 무정전전원장치(Dynamic Uninterruptible Power Supply)의 필요성이 대두되고 있는 실정입니다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2004.11a
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• pp.253-257
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• 2004

디지털 TV 방송이 본격적으로 보급됨에 따라 2004 년 후반부터 각 방송사들은 디지털 방송네트워크의 설계를 위해 본격적인 전계강도 실측을 실시하고 있다. DTV 신호 측정에는, 가장 기준이 되는 전계강도 측정기를 비롯하여 DTV 복조기(demodulator), 각종 셋톱박스, 위성항법장치(GPS)를 이용한 지형정보시스템(GIS) 등 많은 장비가 필요하고 측정항목도 다양하여, 한 지역을 측정하는데 많은 시간이 소요될 뿐 아니라 측정자의 숙련도에 따라 측정결과의 정확도와 신뢰도가 떨어질 수 있다. 본 논문에서는 이러한 문제들을 해결하기 위해 다양한 계측장비와 운용장비의 제어를 체계적으로 관리하고 측정절차를 일반화하며 측정결과 데이터를 데이터베이스화하여 측정결과를 용이하게 파악할 수 있는 통합 측정 시스템을 제안한다. 또한, 본 시스템은 측정 뿐 아니라 지형정보시스템과 전계강도 예측시스템을 도입하여 측정지점 주변의 수신환경 분석 및 최적 수신위치의 검색정보 등을 제공하며, 다량의 측정결과에 대한 다양한 분석이 가능하여 커버리지 분석 및 송신 네트워크의 설계 등에 활용될 수 있다.