• Journal of the Korean Society of Propulsion Engineers
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• v.19 no.5
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• pp.98-103
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• 2015

A flow passage opening device utilizing an acceleration follow-up technique allows fuel to flow continuously through a pressurized fuel tank system. It is very difficult to test the device in a real flight situation because of severe test condition and a cost problem. In this paper, therefore, the results of a basic negative g test conducted by low-speed airplane are compared with RecurDyn simulation. Dynamic behavior of the device in total flight profile of a high-speed vehicle is also analyzed by using RecurDyn to predict its performance.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.05b
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• pp.1011-1015
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• 2005

본 실험에서는 부력 조건이 달라질 때 단공방류구에서 정체수역으로 수평방류되는 부력제트의 거동을 규명하였다. LIF (Laser Induced Fluorescence) 시스템을 이용하여 수행하였는데, LIF 시스템은 고해상도의 이미지를 취득할 수 있어 데이터의 정확도가 높으며, 동시에 한 평면상의 농도장을 일시에 측정할 수 있는 장점이 있는 기술이다. LIF 시스템은 크게 세부분으로 구성되어 있는데 방출시스템, 포착시스템, 처리시스템이 그것이다. 실험 조건을 고려해서 온수를 이용하여 주변수와의 밀도차를 재현하였으며, LIF 시스템의 추적입자로 형광염료 Rhodamine B를 사용하였다. 또한, 실험 데이터 취득과정에서 필요한 검정과정을 수행하였는데, LIF 시스템에서 검정과정은 레이저 입사광의 강도가 불균등한 분포를 가지는 점과 주변수의 매질에 의한 근의 감쇠가 발생하는 문제를 해결하기 위한 것이다. LIF 시스템은 부력제트의 농도장을 매우 정밀하게 측정할 수 있는데, 방류밀도 Froude 수가 변함에 따라 측정된 순간이미지를 통해 제트의 진화과정을 상세하고 가시적으로 확인할 수 있었다. 검정과정을 거친 농도 종단면에서 중심선의 연장선이 LIF 시스템에 의해 측정된 순간이미지의 중심선 궤적과 거의 일치하는 것도 알 수 있었다. 또한 LIF 시스템을 통해서 취득된 단일수평부력제트의 궤적과 중심선 희석률을 기존의 상용모형인 VISJET과 CORMIX1에 의해 예측된 결과와 비교$\cdot$분석한 결과, 제트 중심선 궤적의 경우, LIF 시스템을 이용한 측정값은 대체로 VISJET 모형의 결과와 일치하는 것으로 밝혀졌다. 중심선 희석률의 경우, LIF 측정값은 대체로 CORMIX1 모형, Cederwall(1968)의 경험식과 일치하는 경향을 보였다.0\%$일 때가 밸브를 $60\%$와 $80\%$ 개폐시켰을 때보다 $0.3kg/cm^2,\;0.29kg/cm^2$ 낮게 나타나 밸브를 전체 개방 했을 때 관로내의 수압이 상수설계기준에 적합한 수압을 유지함을 알 수 있다. 상수관로 설계 기준에서는 관로내 수압을 $1.5\~4.0kg/cm^2$으로 나타내고 있는데 $6kg/cm^2$보다 과수압을 나타내는 경우가 $100\%$로 밸브를 개방하였을 때보다 $60\%,\;80\%$ 개방하였을 때가 더 빈번히 발생하고 있으므로 대상지역의 밸브 개폐는 $100\%$ 개방하는 것이 선계기준에 적합한 것으로 나타났다. 밸브 개폐에 따른 수압 변화를 모의한 결과 밸브 개폐도를 적절히 유지하여 필요수량의 확보 및 누수방지대책에 활용할 수 있을 것으로 판단된다.8R(mm)(r^2=0.84)$로 지수적으로 증가하는 경향을 나타내었다. 유거수량은 토성별로 양토를 1.0으로 기준할 때 사양토가 0.86으로 가장 작았고, 식양토 1.09, 식토 1.15로 평가되어 침투수에 비해 토성별 차이가 크게 나타났다. 이는 토성이 세립질일 수록 유거수의 저항이 작기 때문으로 생각된다. 경사에 따라서는 경사도가 증가할수록 증가하였으며 $10\% 경사일 때를 기준으로 $Ro(mm)=Ro_{10}{\times}0.797{\times}e^{-0.021s(\%)}$로 나타났다.천성 승모판 폐쇄 부전등을 초래하는 심각한 선천성 심질환이다. 그러나 진단 즉시 직접 좌관상동맥-대동맥 이식술로 수술적 교정을 해줌으로써 좋은 성적을 기대할 수 있음을 보여주었다.특히

• Journal of the Korea Institute of Military Science and Technology
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• v.7 no.2 s.17
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• pp.41-47
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• 2004

In this paper, simulations of the underwater discharge system with compressed air are performed to predict dynamic characteristics of the system and to find optimal opening trajectories of the expulsion valve. Major components of the system are defined and their governing equations are derived to make up the mathematical model. The compressed air discharge method is affected largely by the discharge depth, and therefore the opening trajectories according to the discharge depth should be found to satisfy the demands of discharge performances. Simulation results are compared with experimental data to confirm the validity of the system model.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.12 no.6
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• pp.554-562
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• 1987

In this paper, we have proposed the RC Wien-Bridge oscillator consisting of three oprational amplifiers in order to improve the frequency range, and the proposed oscillator has been realized a new SC Wien-Bridge oscillator for LSI realization by the forward Z transform method. The realized SC oscilltor has been affirmed that the frequency range has been improved more than Reddy's. Budak and Nay's by the analysis of pole loci as a frequency function f. Also, it has been confirmed that the designed SC oscillator has been satisfied substantially the oscillated condition by the open-loop measurements.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.47 no.4
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• pp.102-108
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• 2010

The photovoltaic system changes solar energy into DC by solar cell and this DC is inverted into AC which is used in general houses by inverter. Recently, the use of power of the photovoltaic system is increased. Therefore, the study of 3 phase solar system to transmit large power is very important. This paper proposes a method that finds simply faults and diagnoses the switch open faults of 3-phase pulse width modulation (PWM) inverter of grid-connected photovoltaic system. The proposed method in $\alpha\beta$ plane uses the patterns of trajectory image as the characteristic parameters and differenciates a normal state and open states of switches. Then, the result is made into tree. The tree is composed of 21 fault patterns and the parameters to classify faults are a shape, a trajectory area, a distributed angle, and a typical vector angle. The result shows that the proposed method diagnosed fault diagnoses, classified correctly them, and made a pattern tree by fault patterns.

• Journal of Korea Technology Innovation Society
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• v.17 no.2
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• pp.309-333
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• 2014

To meet the challenge of new type of innovation activities requires us to understand the social context of innovation and the potential needs of innovation users and, based on this, to co-construct technology and society simultaneously. Effective 'demand articulation' activities such as the understanding and utilization of user experiences and socio-technical planning are prerequisites for carrying out post-catch up innovations shaping new trajectories and contributing to solving social problems. Living Lab has recently been emerging particularly in Europe as an 'user-driven innovation model', in which users are active participants in innovation activities. The purpose of this study is to contribute to a theoretical discussion of Living Lab as an user-driven innovation model, to make a brief review of cases of Living Lab and to explore Living Lab's applicability in the Korean context. Living Lab is an open innovation model, in which end suers actively participate in innovation processes in a particular geographical space or region and would be able to solve specific problems of that space or region. In that sense, Living Lab would be able to strengthen the problem-solving capabilities of local communities and to become a pioneer in inducing and realizing a new socio-technical system. Furthermore, Living Lab could become an innovative policy tool reflecting recent major changes in innovation policy paradigms such as post-catch up innovation, demand-oriented innovation, regional innovation, societal innovation, innovation eco-system and socio-technical system transition, and thus make a contribution to exploring a new way of bringing about changes in the Korean society.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.1
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• pp.243-249
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• 2013

In waste repository environment, we can process the waste history efficiently for reuse by recording the history trajectory of the vehicle which loaded waste and the dumping position of the waste vehicle. By mapping the unloaded waste to 3D and by extracting the dumping point, a new method was implemented so as to record the final dumping position and the waste content under various experiments. In this paper, we developed the algorithm which tracking the vehicle and deciding the moment of dumping in landfills. We first trace the position of vehicle using the difference image between current image and background image and then we decide the stop point from the shape of vehicle route and detect the dumping point by comparing the dumping image with the image that vehicle is stopping. From the camera parameters, The transform method between screen coordinate and real coordinate of landfills is proposed.

• 한국노년학
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• v.37 no.1
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• pp.151-171
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• 2017

The purpose of this study is to analyze middle-aged female householders' reasons behind becoming female householders, process of adapting to female householders' life, and experiences in preparation for old age using Colaizzi's phenomenological method. The participants were 9 middle-aged women (aged from 40-59) having professions. We interviewed each participants twice, for 60 to 90 minutes at a time from September to December of 2014. The result of this study showed following 6 emergent themes: , , , , and . Regarding the result we suggest the necessity of political support such as providing information and education for female householders' successful old age.

• Journal of the Economic Geographical Society of Korea
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• v.20 no.3
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• pp.267-286
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• 2017

The main purpose of this paper is to identify the spatiality of North Korea and China border regions through investigating the exceptional characteristics of the regions with the concept of positionality, which allows us to realize the relative position between subject and object. Border regions could be identified appropriately by considering the concept of switching positionality, as it is a kind of multiple space in which its sudden closure and opening should be configured in accordance with geopolitical and geoeconomic changes centering around border line. The main arguments of this research concerned with border regions with the concept of switching positionality are fallen into three. Firstly, changes in border regions should be analyzed by investigating more broader contexts and conjunctural perspectives, and even an internal condition stemmed from locality. Secondly, trajectories of border regions could be analyzed by the assemblages of various powers. Finally, the positionality of economic actors should be examined by identifying dynamic relations between geoeconomics and geopolitics. In particular, the concept of positionality has led to a number of insights into discussions on time-space, and spatiality in relational-dialectical, socio-spatial, and power-topological perspectives. Based upon this concept of positionality, the research has identified exceptional characteristics in North Korea and China border regions. It argues that the exceptionality of the region has stemmed from the intersection between the unstability of geopolitical security and various geoeconomic benefits.

• The KIPS Transactions:PartD
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• v.11D no.6
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• pp.1247-1258
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• 2004

The LBS(Location-Based Service), which is based on individual's mobility, is required increasingly as mobile telecommunication and various infrastructures have developed rapidly. The technologies for LBS are location determination technology, service platform technology, contents provider technology and moving object database technology generally. Among these, service platform must be interoperable with location gate-way server and provide common function of billing, authentification, protect location information, privacy control, location trigger and intelligent acquisition and so on. The TTA(Telecommunications Technology Association) published specification that defines a standard protocol for safe and simple interface between LBS client and LBS platform and the OpenLS(Open Location Service) in OGC (Open GIS Consortium) released implementation specifications for providing Location based core services. In this paper, we implemented service platform for LBS which is able to interoperable with location gateway server and contents provider and is caracterized as follows. First, it could require and response location information from different types of location gateway server with same interface. Second, it complies with the standard interfaces with OpenLS 4 contents providers for core LBS. Third, it could provide location of wired phone as well as wireless mobile terminal compling with the standard protocol. Last, it could provide trajectorH information based past location as well as current location, because it is able to interoperable with moving object DBMS. This paper contributes to the construction and practical use of LBS by providing the method of implementation of service platform for LBS.