• Aerospace Engineering and Technology
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• v.4 no.1
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• pp.150-161
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• 2005

A test was performed to collect the data to validate an analytic method for vent hole sizing on the nose fairing of a launch vehicle. The bake-out chamber at KARI was used to simulate the ambient pressure drop, and pressure difference data were collected for a model with various kinds of vent holes which was installed in the chamber. The characteristics of the test facility and measurement equipments were evaluated for the measurement of the transient behaviors. The measured data were processed in consideration of the characteristics of the facility and equipments, and the effects of vent hole size and configuration on the pressure variation in the model were analyzed based on the data.

• Journal of the Korean Society of Propulsion Engineers
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• v.14 no.1
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• pp.1-10
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• 2010

Design and performance evaluation of $H_2O_2$ monopropellant thrusters to be used at reaction control of space launch vehicles were presented in this paper. Design thrust level was determined as 100, 250 Newton which is nominal thrust level for commercial space launch vehicles. Qualification thruster models including solenoid valves were developed after the reactor design were evaluated at engineering thruster models. Each thruster was evaluated by measurement of characteristic velocity, thrust, specific impulse, and pulse response times at sea level test condition.

• Journal of Internet Computing and Services
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• v.18 no.6
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• pp.25-34
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• 2017

Autoencoder is a type of deep learning method where input layer and output layer are the same, and effectively extracts and restores characteristics of input vector using constraints of hidden layer. In this paper, we propose methods of Autoencoders to remove a natural background image which is a noise to the CAPTCHA and recover only a numerical images by applying various autoencoder models to a region where one number of CAPTCHA images and a natural background are mixed. The suitability of the reconstructed image is verified by using the softmax function with the output of the autoencoder as an input. And also, we compared the proposed methods with the other method and showed that our methods are superior than others.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.4
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• pp.100-109
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• 2005

This paper introduce electromagnetic environmental requirements, test procedures and test results for the Command Telemetry Unit(CTU), which is engineering qualification model for communication satellite in geostationary earth orbit. Also, through debugging of the CTU during the Electro Magnetic Compatibility(EMC) tests, this paper evaluates characteristics of noise generated by the CTU. It is also obtained that better EMC performance can be acquired by improving electrical power converter module of the CTU.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.9 s.112
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• pp.804-810
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• 2006

In this paper, we describe a measurement technique for the backscattering coefficient and ground truth of a vegetation canopy in detail. A simple microwave backscattering model for vegetation canopies is verified by being compared with this measurement. An R-band$(1.7\sim2.0GHz)$ scatterometer system is used to measure the backscattering coefficient of a vegetated area in the Han-river park for various incidence angles and a wide range of the soil moisture contents. It is found that the model agrees quite well with the measurements for co-polarized radar backscatter, and needs a correction for cross polarized radar backscatter.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2017.06a
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• pp.22-25
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• 2017

본 논문은 " 개방형 클라우드 기반 스마트 방송 플랫폼" 표준에 따라서 개발될 수 있는 다양한 클라우드 기반 스마트 방송 애플리케이션의 형식과 관계를 규정하기 위한 애플리케이션 모델을 소개한다. 스마트 방송용 애플리케이션이 다양한 클라우드 방송 플랫폼에서 일관된 사용자 경험을 제공하며 동작하기 위해 클라우드 방송환경의 특성을 고려해야 하며, 이에 따라 애플리케이션의 형식을 분류하고 실행 및 종료 방법과 생명 주기를 정의하며 애플리케이션 사이에서 동작 관계를 규정하는 등의 모델 정립이 필요하다. 본 논문에서는 클라우드 방송 애플리케이션을 방송 수신 기능의 활성화 여부에 따라 방송 독립형 및 연동형으로 분류하고, 각 애플리케이션의 생성과 종료를 위한 생명주기와 각 애플리케이션 사이에서 우선 순위를 기반으로 한 상호 작용정책을 규정한다. 또한, 클라우드 애플리케이션의 형식 및 우선순위 등을 애플리케이션에 지정할 수 있는 관리정책을 정의한다. 이러한 모델 정의를 바탕으로 표준을 적용한 클라우드 방송 테스트 플랫폼을 구현하고 다양한 형태의 클라우드 방송 애플리케이션을 개발하여 모델 정의에 따르는 기본 동작 시나리오 및 유효성을 검증한 사례를 소개한다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.1
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• pp.99-106
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• 2011

In this study, the dynamic contact of a catenary system is analyzed by using the finite element method. We derive the equations of motion for the catenary system by taking into consideration tension on the catenaries. After establishing the weak form, they are spatially discretized with beam elements. Then, we analytically calculated the wave propagation speed for a string, bar, beam, and the catenaries subjected to tension. Further, finite element computer program for contact dynamic analyses is developed. Finally, we analyze the wave propagation response corresponding to the moving load to the contact line are calculated.

• Journal of Biomedical Engineering Research
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• v.25 no.4
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• pp.283-288
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• 2004

The finite element modeling of small female occupant for crash simulation is presented in this paper subsequently to the part I of articulated rigid body model. The limbs and internal components are additionally modeled by joining them to the articulated rigid body model for predicting the crash injuries such as bone fractures and joint dislocations. The behavioral characteristics of each limbs and internal components were validated against available cadaveric test results. Accordingly, the human model proposed in this paper could be utilized for the investigation of impact injury mechanism and further complement the lacking biofidelity of current crash dummy.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2013.06a
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• pp.189-192
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• 2013

본 논문은 "HTML5 기반 스마트 TV 플랫폼" 표준에 따라서 개발될 수 있는 다양한 스마트 TV 애플리케이션의 형식과 관계를 규정하기 위한 애플리케이션 모델을 소개한다. 스마트 TV 용 애플리케이션은 브라우저 기반의 웹 실행 환경에서 동작하지만 일반 PC 나 스마트 폰과 다른 TV 환경의 특성을 고려해야 하며, 이에 따라 앱의 형식을 분류하고 실행 방법과 생명 주기를 정의하며 애플리케이션 사이에서 동작 관계를 규정하는 등의 모델 정립이 필요하다. 본 논문에서는 스마트 TV 용 애플리케이션을 패키징 여부, 실행 방식, 방송 수신 기능의 활성화 여부, 채널 종속 여부의 4 가지 요소로 분류하여 애플리케이션의 정의, 속성, 플랫폼 실행방식 등을 기술한 애플리케이션 모델을 정의한다. 또한 각 애플리케이션의 생성과 종료를 위한 생명주기와 각 애플리케이션 사이에서 우선 순위를 기반으로 한 상호 작용 정책을 규정한다. 이러한 모델 정의를 바탕으로 스마트 TV 서비스에서 고려할 수 있는 대표적인 애플리케이션 동작 시나리오를 제시하고 유효성 검증을 위해 이를 구현한 수신기와 애플리케이션이 동작하는 사례를 소개한다.

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.8
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• pp.1084-1093
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• 2010

Large eddy simulation of turbulent premixed flame stabilized by the bluff body is performed by using sub-grid scale combustion model based on the G-equation describing the flame front propagation. The basic idea of LES modeling is to evaluate the filtered-front speed, which should be enhanced in the grid scale by the scale fluctuations. The dynamic subgrid scale models newly introduced into the G-equation are validated by the premixed combustion flow behind the triangle flame holder. The calculated results can predict the velocity and temperature of the combustion flow in good agreement with the experiment data.