• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.256-257
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• 2005

We fabricated self-assembled monolayers(SAMs) onto quartz crystal microbalance(QCM) using viologen, which has been widely used as electron acceptor and electron transfer mediator. The viologen derivative exist in three redox states, namely. These redox reactions are highly reversible and can be cycled many times without significant side reactions, respectively. We studied the characteristics of charge transfer using different electrolyte solutions by electrochemical quartz crystal microbalance (EQCM). From the data, the redox peak currents were nearly equal charges during redox reaction and existed to an excellent linear interrelation between the scan rates and first redox peak currents. The redox reactions of viologen were highly reversible and the EQCM has been employed to monitor the electrochemically induced adsorption of SAMs during the redox reactions.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.2
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• pp.126.2-126.2
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• 2011

MIRIS(Multipurpose InfraRed Imaging System)는 과학기술위성 3호의 주 탑재체이며 2012년 하반기 발사예정이다. MIRIS 우주관측 카메라는 0.9-2.0 ${\mu}m$ 영역에서 3.67 deg. x 3.67 deg. FOV로 우리 은하평면 survey 관측과 우주배경복사(CIB) 관측을 수행할 것이다. 현재 MIRIS는 비행모델 개발 마무리 단계에 있으며, 검교정 시험, 열-진공 시험, 진동 시험 등을 수행하고 나면 2011년 말 위성 본체와의 조립을 진행할 것이다. 망원경이 복사냉각(Passive Cooling)을 통해 200K 이하로 냉각되면, dewar에 설치된 소형 냉각기를 가동하여 적외선 센서를 90K 정도로 냉각한다. MIRIS 우주관측카메라에는 PICNIC($256{\times}256$ pixel) 센서를 사용하였고, 상온과 냉각된 상태에서의 노이즈 특성을 측정하였다. PICNIC 센서와 dewar내부를 냉각하기 위해 RICOR사의 K-508 micro stirling cooler를 사용하는데, cooler가 동작하면서 전자부에 영향을 주어 주된 잡음으로 나타남을 확인하였다. Cooler에서 발생하는 잡음을 최소화 하기위해 fanout B/D와 LVPS 부분을 개선하였으며, 본 발표에서는 잡음 측정 결과에 대해 논의 하고자 한다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.25 no.1
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• pp.1-8
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• 2012

This study is a basic experimental research to apply FRP (Fiber Reinforced Polymer) box members to slabs and girders among various architectural structures, which receive bending stress. We prepared prefabricated FRP member and connected it to an FRP box member as a large cross section before we conducted an experiment in diverse conditions to analyze characteristics of compressive fracture behavior. In this study, we carried out a compressive fracture behavior test according to fillers on the upper part of the FRP box member, loading methods, and connective types and thereby performed a finite element analysis. The comparison of analysis results with test results revealed that rigidity was found to be slightly low, while stress was concentrated on the fracture point of the sample.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.2
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• pp.126-133
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• 2009

In this paper, The planar waveguide slotted antenna is presented for a satellite communication of vehicles. In stead of the microstrip patch array antenna having a dielectric loss and a feeding loss, the proposed antenna has the 3-layered waveguide feeding network structure for assembling easily. Also this antenna can receive mechanically both RHCP and LHCP transmitted from a satellite using a polarizer made from a thin single layer film. The Gain of the proposed 4X8 array antenna is 27.5dB and the gain of 8X16 array antenna is 32dB.

• The Journal of the Korea institute of electronic communication sciences
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• v.12 no.6
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• pp.983-988
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• 2017

This study describes the design and implementation of OMUX(Output Multiplexer) for Satellite Communication. The OMUX unit for SHF band consists of LPF(Low Pass Filter), manifolder and Channel Filter. Through the pre-simulation analysis of space environment, the possibility of the malfunction of equipment minimized and we designed a reliable OMUX through simulation for vibration analysis generated during the launch, and compared pre-simulation of main performance results to test results about main performances of OMUX after production.

• Journal of Applied Reliability
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• v.11 no.3
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• pp.235-244
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• 2011

Hydraulic hose assemblies deliver a fluid power in various oil pressure equipment such as construction machinery, automobile, aircraft, industrial machinery, machine tools and machinery for ships. Also, they are widely used as pipes in oil pressure circuit. When we estimate their lifetime, it is essential to conduct an accelerated life test by choosing the factor that suits the usage condition of the test object since traditional test method for estimating lifetime under the influence of various external factors incurs hardship in terms of time and expenses. The objective of this study is to propose an acceleration model that takes both temperature and pressure without flexing condition into consideration. The lifetime is estimated by applying the proposed temperature-nonthermal acceleration model to the test data. And we compare the proposed temperature-nonthermal acceleration model and the accelerated life equation suggested by John(1994).

• Journal of IKEEE
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• v.21 no.3
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• pp.185-194
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• 2017

In this paper, a modular platform for wearable devices is proposed which can be easily assembled by exchanging functions according to various field and environment conditions. The proposed modular platform consists of a 32-bit RISC CPU, a 32-bit symmetric multi-core processor, and a 16-bit DSP. It also includes a plug & play features which can quickly respond to various environments. The sensing and communication modules are connected in the form of a chain. This work is implemented in a standard 130 nm CMOS technology and the proposed modular wearable platforms are verified with temperature and humidity sensors.

• Aerospace Engineering and Technology
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• v.10 no.2
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• pp.133-145
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• 2011

This paper is about the results in Qualification Management activity performed between the Autonomous Test(AT) season(August. 2008) of Launch Complex and the 2nd flight test season(June. 10, 2010) of KSLV-I. All cryogenic fluids(LOX, $LN_2$) and compressed gases(Air, $GN_2$, GHe) were qualified by qualification management activity during AT(Autonmous Test), QT(Qualification Test) season for LP(Launch Pad) and LVAB(Launch Vehicle Assembly Building) and FT(Flight Test) season of KLSV-I. As the results, total 428 times of check analysis and 111 times of full analysis were performed.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.139-141
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• 2017

By modulating the flow rate of $N_2O$ into a HR motor assembly, a control valve of a hybrid rocket engine plays a role to increase or decrease the thrust. In this study, the control valve has been designed to meet the requirements which are response speed(${\leq}$ about 1 second) and torque(${\geq}$ about $36N{\cdot}m$). Then, when analog signal 0~10V is applied, the situation where the valve is opened and closed has to be realized. To do this, the data values have to be entered into the actuator. Finally, the performance evaluation of the control valve has been performed to validate this product.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.8
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• pp.741-747
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• 2002

In this paper, NRD guide band pass filter with newly designed inductive iris structure is proposed and analyzed with its test results. In case of common NRD guide filter with air gap coupled structure, it was not easy to fabricate and process or each NRD guide dielectric resonator blocks using PTFE. However, in this our research, each dielectric resonator fabricated in a single NRD guide is coupled with inductive iris located on metal plates. The structure is suitable for mass production of a precise and reliable millimeter-wave filter applications. As a result of measurements, designed NRD guide inductive iris filter has superior performance. The pass band is 38.66~39.06 MHz with 400 MHz bandwidth, insertion loss is about 1.4 dB and return loss is below -18 dB.