• 전기의세계
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• 제13권3호
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• pp.13-20
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• 1964

The measurements of X-ray and Gamma-ray Dose Rate have been successfully made by measuring the short circuit current of the Silicon P-N Junction Diode being irradiated. The short circuit current flows when a silicon P-N Junction Diode is irradiated by X-ray of Gammaray radiations due to photovoltaic effect. A brief analysis is given in order to verify the proportionality of a short circuit current to the Dose Rate. Using this method, measurements of X-ray Dose Rate were carried out in the range of 0.05-1600 r/m successfully. The calibration was made by comparing with Victoreen condenser r-meter. Some advantages in this Dose Rate meter over a condenser r-meter were found. One can measure a continous variation of X-ray Dose Rate with this rate meter at the control console of X-ray device.

• 드라이브 ㆍ 컨트롤
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• 제14권3호
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• pp.1-7
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• 2017

Energy consumption of conventional hydraulic excavators controlled by MCV is considerable when negative load is applied because the meter orifice and meter-out orifice are machined in one spool. Therefore, IMV is introduced to save energy use of hydraulic excavators, but existing hydraulic excavators have various advantages so it is difficult to make a clear comparison. In this study, we compare the use of an existing MCV excavator that has many advantages such as negative control, and IMV for boom up and down operation, and if IMV is used to save energy, we will examine the cause. If possible, for comparability under the same conditions, both systems use pressure balance valves to minimize power consumption when not using power in the actuator. The orifice area at each notch of each valve is calculated, and energy saving is verified by comparing the two systems through simulation.

• 대한기계학회논문집A
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• 제26권8호
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• pp.1552-1564
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• 2002

Meter-in, meter-out and bleed-off circuits are widely utilized in order to adjust the speed of a hydraulic actuator by using a flow control valve and in order to regulate the pressure of a hydraulic volume by using a simple on-off valve. In these circuits, a relief valve serves either to maintain constant system pressure or to protect the system from over-pressure loading. The relief valve of a bleed-off circuit is the second case frequently undergoing on-off action during operation. It makes the analysis of the pressure control characteristics of the circuit highly difficult. In this paper, steady-state flow rate, pressure, heat loss and efficiency of the three circuits are reexamined and basic experiments far obtaining the characteristics of a pump and relief valve are conducted. Finally, simple empirical first-order dynamic models of decreasing and increasing pressure were separately proposed and verified by comparison with experiment. As the result, the basis for the theoretical analysis of the pressure control characteristics of a bleed-off circuit using a simple on-off valve is established.

• 한국습지학회지
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• 제12권1호
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• pp.95-103
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• 2010

유량자료는 물의 순환과정을 규명하고 효율적인 수자원 개발 및 이수 치수 계획 등에 매우 귀중하게 이용된다. 그러나 이러한 유량자료를 확보하는데 많은 시간과 경비 등이 요구되기 때문에 주요 수위에서 유량자료는 수위-유량관계곡선식(Stage-Discharge Curve)을 개발하여 유량을 산정하고 있다. 따라서 수위-유량관계곡선식의 신뢰도는 유량자료의 품질에 절대적인 영향을 미치는 요인으로 작용된다. 수문학을 전공하고 연구하는 많은 학자들은 고품질의 유량자료를 생산하여 신뢰성 있는 곡선식을 개발하고자 유량측정 방법과 기준, 장비개발 및 개량 등에 관한 연구를 수행하고 있다. 현재 국내에서는 다양한 유량측정기기를 사용하여 유량자료를 생산하고 활용하고 있으나, 측정기기별 정확도 및 실험적 측정성과에 대한 연구자료가 미흡한 실정이다. 본 연구에서는 규격화된 콘크리트 수로에 일정한 유량을 흘려보내는 조건에서 다양한 측정기기를 이용하여 유속을 측정하였다. 그리고 이 측정성과를 이용하여 유량을 산정하고 비교분석하였다. 실험을 위해서 국내에서 일반적으로 사용되고 있는 측정기기로 프라이스 유속계(USGS Type AA Current Meter), 휴대용 유량계(Flow Meter), 초음파식 디지털 유속계(ADC), C2 유속계(C2 Small Current Meter), 플로우 트렉커(Flow Tracker), 마그네틱 유속계(Electromagnetic Current Meter) 등의 장비를 사용하여 유량을 산정하였으며, 각 기기별 산정된 유량을 비교 분석 하였다. 비교검토에 적용하고자 측정한 수심으로는 0.30 m, 0.35 m, 0.40 m, 0.45 m, 0.50 m, 0.55 m의 왕복측정 6-Case로 진행이 되었으며, 신뢰성과 정확도를 높이기 위해 도섭법으로 수면에서 0.6d 지점의 유량측정방법(1점법)을 적용하였다. USGS Type AA Current Meter, Flow Meter, ADC, C2 Small Current Meter는 유속측정기기의 검교정을 받았으므로 다른 실험유량측정치의 비교를 위한 기준값으로 사용하였다. 따라서 국내에서 널리 사용되는 측정기기(USGS Type AA Current Meter, Flow Meter, ADC, C2 Small Current Meter, Flow Tracker, Electromagnetic Current meter)별 검토 결과 평균유량 및 평균유속에 있어 프라이스 유속계를 기준으로 마그네틱 유속계 $\pm$ 10 % 이상, 플로우 트렉커 $\pm$ 10 % 미만, 휴대용 유량계, 초음파식 디지털 유속계 및 C2 유속계는 $\pm$ 5 % 미만의 차이가 있음을 확인할 수 있었다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1990년도 한국자동제어학술회의논문집(국제학술편); KOEX, Seoul; 26-27 Oct. 1990
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• pp.1037-1042
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• 1990

The air-fuel ratio of an internal combustion engine must be controlled with accuracy for the improvements of exhaust emission and fuel consumption. Therefore, it is necessary to measure the exact instantaneous amounts of fuel and suction air, so we carried out the experiments for measuring the air flow velocity in a suction pipe of an internal combustion engine using three types of instantaneous air flowmeter. The results obtained can be summarized as follows: (1) The laminar-flow type flowmeter is able to measure both the average and the instantaneous flow rate, but it is necessary to rectify the pulsating air flow in the suction pipe. (2) The a spark-discharge type flow velocity meter is able to measure the instantaneous air velocity, but it is necessary to choose the suitable electrode form and the spark character. (3) The tandem-type hot-wire flow velocity meter indicates the instantaneous flow velocity and its flow direction.

• 대한기계학회논문집A
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• 제21권2호
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• pp.252-260
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• 1997

In this paper, a friction compensation method using a disturbance observer is proposed for an impedance control of pneumatic manipulator. It is assumed that the generated torque by a pneumatic actuator can be estimated based on the pressure signals and the discharge volume. In order to improve the dynamic characteristics of the pneumatic actuator driven by meter out method, we construct the inner torque control system by feeding back the generated torque. In order to reduce the influence of disturbances comprising friction torque and parameter variations of plant, the impedance control system is constructed with a disturbance observer which estimates the disturbances based on the generated torque of pneumatic actuator, the angular velocity and the reaction torque. From some experiments, it is confirmed that the proposed control system is effective to improve the robustness for the friction torque in the impedance control of a pneumatic manipulator.

• 한국지능시스템학회논문지
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• 제24권4호
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• pp.424-429
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• 2014

본 논문에서는 발광광고물의 휘도를 측정하는 영상기반 휘도측정시스템을 제안한다. 제안하는 휘도측정시스템은 DSLR 카메라의 영상을 이용하여 점휘도계의 효율성과 면휘도계의 휴대성 및 경제성의 단점을 보완하며, 대상의 전체적인 휘도를 측정하는 시스템으로 영상을 입력받아 휘도분석 알고리즘을 통해 실시간으로 휘도값이 출력되도록 설계하였다. 측정 대상인 발광광고물은 설치 위치, 크기, 모양이 다양하며, 발광광고물의 휘도는 측정 거리, 각도, 색 등 다양한 조건에 따라 측정값이 달라진다. 따라서 정확한 휘도를 측정하기 위하여 측정대상물과의 거리에 따른 휘도값의 변화를 측정하였고, 측정 거리가 증가하면 휘도값이 변화하는 것을 고찰하였다. 실험을 통하여 측정 위치와 휘도값의 연관성을 수식으로 나타내었고, 제안한 방법을 평가하기 위해 점휘도계를 이용한 측정값과 비교 실험을 진행하였다.

• 한국가시화정보학회:학술대회논문집
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• 한국가시화정보학회 2002년도 추계학술대회 논문집
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• pp.117-120
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• 2002

An experimental research has been carried out for flow control of the shock wave/turbulent boundary-layer interaction utilizing aeroelastic mesoflaps. Various shapes and thicknesses of the mesoflap are tested to achieve different deflections of the flap, and ail the results are compared to the solid-wall reference case without flow-control mechanism. Quantitative variation of skin friction has been measured downstream of the interactions using the laser interferometer skin friction meter, and qualitative skin friction distribution has been obtained by observing the interference fringe pattern on the oil-film surface. A strong spanwise variation in the fringe patterns with a narrow region of separation near the centerline is noticed to form behind the shock structure, which phenomenon is presumed partially related to three-dimensional flow structures associated with both the sidewalls and the bottom test surface. The effect of the shape of the cavity is also observed and it is noticed that the shape of the cavity is not negligible.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권4호
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• pp.1493-1515
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• 2015

A smart meter is one of the core components in Advanced Metering Infrastructure (AMI) that is responsible for providing effective control and monitor of electrical energy consumptions. The multifunction tasks that a smart meter carries out such as facilitating two-way communication between utility providers and consumers, managing metering data, delivering anomalies reports, analyzing fault and power quality, simply show that there are huge amount of data exchange in smart metering networks (SMNs). These data are prone to security threats due to high dependability of SMNs on Internet-based communication, which is highly insecure. Therefore, there is a need to identify all possible security threats over this network and propose suitable countermeasures for securing the communication between smart meters and utility provider office. This paper studies the architecture of the smart grid communication networks, focuses on smart metering networks and discusses how such networks can be vulnerable to security attacks. This paper also presents current mechanisms that have been used to secure the smart metering networks from specific type of attacks in SMNs. Moreover, we highlight several open issues related to the security and privacy of SMNs which we anticipate could serve as baseline for future research directions.

• 한국공간구조학회논문집
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• 제13권2호
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• pp.101-109
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• 2013

Children are out future society members but they are not well cared to be safe from various accidents. This is due to facilities were installed upon the children's for adults which can not provide safe traffic environment for children's schooling who are not fare enough experience and matured. "The Rule of declaim for school zone and it's Management"was established in the year 1995 based on the article 11 by the "Road Traffic Low". And 15,136 school zone declared by the above rule. In this study, four elementary schools located in Nowon-gu are selected and analyzed about state of elementary school, scope of school zone, installation of street furniture, and safety signs. The analysis showed that scope of school zone is currently set in 150-meter though the regulation is within 300-meter radius. Therefore, expansion of the scope is required. It is necessary to take control of vehicle during commuting times and holograms which can be noticed in school zone have to be installed as well. Through these improvements, safety zone will be offered to children effectually.