• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.6
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• pp.71-76
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• 2010

In this paper, a 120 GHz local oscillator(LO) for the sub-harmonic mixer in the THz transceiver with a carrier frequency of 240 GHz was designed and fabricated. A 120 GHz local oscillator was composed of 40 GHz PLL(Phase Locked Loop), 40 GHz BPF(Band Pass Filter), frequency tripler and 120 GHz BPF. The commercial model of the frequency tripler was used. The measured result of the 40 GHz PLL showed the phase noise of -105 dBc/Hz at the 100 kHz offset frequency. The measured result of 120 GHz BPF showed the insertion loss of 1.3 dB at center frequency of 119 GHz with bandwidth of 5 GHz. The output power of 120 GHz LO was measured to 6.6 dBm.

• Aerospace Engineering and Technology
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• v.6 no.1
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• pp.190-200
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• 2007

A pyrogen type igniter was designed to satisfy the requirements of KSLV-I Kick Motor system. To insure the reliability of the igniter before the production of the flight model, we have been performed the structure, environmental, combustion tests. The hydraulic test was carried out to confirm the strength of the components of the igniter. The shock and vibration tests were considered to check whether the igniter operates normally under the severe environmental condition. The combustion tests were also performed to understand the ignition characteristics with the variation of initial condition. Finally, we confirmed that the igniter could provide the acceptable energy to ignite the propellant of kick motor at the ground test.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.654-657
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• 2011

For the successful development of korean exploraton program, KARI started development of ground test model for lunar lander from last year. In order to secure core technology for space propulsion system, Koreanization of propellant tank is proceeding and it will be used for final assembly and test for ground test model. In this paper, the development result of titanum tank shell and verification test result was presented.

• Information and Communications Magazine
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• v.33 no.1
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• pp.42-47
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• 2015

본고에서는 개인 또는 기업이 아이디어를 제품화하는 과정에서 겪게 되는 생산진입의 어려움을 해소하기 위해서 개인맞춤생산을 지원하는 개방형 제조서비스 플랫폼 (FaaS: Factory as a Service)을 제안한다. FaaS 플랫폼은 다양한 고객들의 맞춤형 제품에 대한 요구를 수용하여 가능한 대량 생산에 가까운 효율로 생산하도록 설계하였으며, 개인맞춤생산을 위한 스마트 제조기술과 제조서비스 플랫폼 기능을 제공한다. FaaS 플랫폼은 고객이 자신이 원하는 제품생산의 요구를 정확하게 지속적으로 전달하기 위해 개방성을 제공하는 FaaS 클라우드 계층과 다양한 이종 제품들을 최적의 생산 효율을 가지고 혼류생산 할 수 있도록 하는 FaaS 제조운영 계층, 그리고 3D프린터, 로봇과 같은 혁신형의 제조설비들을 IoT(Internet of Things)를 기반으로 유기적으로 연결함으로써 팩토리 전체 성능을 향상시키도록 하는 FaaS 실행제어 계층으로 구성된다. 본 고에서 제안한 FaaS 플랫폼은 향후 기술개발 결과물을 실 수요 제품을 생산하는 ICT융합형 제조서비스 스마트팩토리 실증테스트베드에 적용하여 시범운영을 통해 기술을 검증하고 확장할 계획으로 있으며, 이를 통해 창업 기업이나 중소 제조기업들이 신제품의 시장진입시간을 단축시키고, 실질적인 펀딩 효과를 가질 수 있기를 기대한다.

• Journal of the Korean Society of Propulsion Engineers
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• v.16 no.1
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• pp.64-71
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• 2012

While a conventional ECS mainly consisted of an air cycle machine and heat exchangers, a new concept of a phase change heat exchanger was added to improve the transient performance of the ECS. As a result, an ECS modeling program including the phase change heat exchanger is newly developed to estimate its effect in various flight conditions such as take-off, maneuver, cruise, and landing. The simulation result regarding a virtual flight profile has confirmed the new ECS fulfilled the requirement by showing the temperature of the cooling air returned from the bay was always kept below $80^{\circ}C$. Through this study, the new ECS concept with PCHE was verified successfully.

• Journal of the Korean Society of Propulsion Engineers
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• v.24 no.2
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• pp.52-60
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• 2020

This paper deals with an optimal output tracking control for open-cycle liquid propellant rocket engine. For this purpose, we modeled simplified mathematical model of open-cycle liquid propellant rocket engine and designed optimal output feedback control system using combustion chamber pressure. For design the closed-loop system of open-cycle liquid propellant rocket engine, we designed optimal output feedback linear quadratic tracking control system using the linearized model and demonstrated the performance of the controller through numerical simulation.

• The Transactions of the Korean Institute of Power Electronics
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• v.9 no.4
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• pp.319-325
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• 2004

The major factors that make ZEV affordable are the range and cost. The development of advanced batteries such as Ni-MH battery can solve the problem partly； on the hand the battery management system is an efficient way. Ni-MH battery and battery ECU is a key component influencing ZEV performance, such as range, acceleration and hill-climbing capability. Because most problems related to battery such as short circuit, over-discharge and overcharge occur easily during operation, it is necessary to develop a dedicated battery ECU for HEV. This paper proposes a new SOC algorithm for the HEV based on the terminal voltage and current integration. And battery ECU was designed and analyzed. Also, the validity is confirmed through experiment.

• Fire Science and Engineering
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• v.30 no.1
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• pp.74-80
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• 2016

Ubiquitous computer technology (U technology) is continually, and the trend is moving towards the miniaturization of devices, cost reduction, performance enhancement, and intelligence. It is important to improve fire safety system by the application of advanced IT technologies. In this study, a vulnerable point in fire safety was selected for improvement by U technology. The structure of the whole system and a unit system was were designed. This system is divided into 5 parts: the U-fire protection facility management system, the U-fire safety information system, the U-fire safety education system, the U-fire response system, and the U-wide area fire safety management system. The prototype system was constructed in a real building to confirm the applicability of the system.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.8
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• pp.581-588
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• 2020

The aging characteristics of exploding foil initiator (EFI) are studied. In order to observe the aging characteristics, the main components of the exploding foil initiator were classified and the failure mechanism was defined. The aging characteristics were defined in terms of power and sensitivity, and the accelerated aging test plan was established based on the activation energy calculated by HFC (Heat Flow Calorimetry) and Arrhenius theory. The performance variation was observed using the sensitivity test (Neyer test) and power test (Dent test) for the aged samples. The aging characteristic was observed on the mean exploding point of the sensitivity test, but long-enough life span was predicted considering the related specification.

• Membrane Journal
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• v.26 no.2
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• pp.152-158
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• 2016

The Chlor-alkali (CA) membrane cell is a major electrolysis system to produce valued chemicals such as chlorine gas and sodium hydroxide. The CA membrane process has been attracted in the industries, since it has relatively low energy consumption when compared with other CA processes. The key component in CA process is perfluorinated sulfonic acid ionomer membranes, which provide ion-selectivity and barrier properties to produced gases. Unfortunately, there is limited information to determine which factors should be satisfied for CA applications. In this study, the influences of PFSA membranes on CA performances are disclosed. They include ion transport behaviors, gas evolution capability, and chemical/electrochemical resistances under CA operation conditions.