• Journal of the Korean Institute of Gas
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• v.2 no.3
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• pp.88-95
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• 1998

Vibration analysis of rotating machinery can give an indication of possible faults thus allowing maintenance before further damage occurs. Current predictive maintenance system installed in Pyung-tak has the ability to diagnose the mechanical problems within the LNG Pump when the vibration exceeds preset overall alarm levels. In this study, LNG pump auto-diagnosis system based upon Windows NT and DSP Board is developed. This system analysis velocity signal acquired from dual accelerometer input monitor system to diagnose pump condition. Many plots which display machine condition are shown and features of vibration are stored in every time. If the fault is found, the system diagnoses automatically using expert system and trend monitoring. Operator checks pump condition intuitively using personal computer monitor.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.544-549
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• 2009

The purpose of this study is to investigate the field Operation Characteristics of a sea water heat source cascade heat pump system and system applicable to Building. Cascade heat pump system is composed R410A compressor, R134a compressor, EEV, cascade heat exchanger, Plate heat exchanger etc. Building area is $890m^2$ and has five floors above ground. R410A is used for a low-stage working fluid while R134a is for a high-stage. The system could runs at dual mode. One is mode of general R410A refrigeration cycle in summer and the other is cascade cycle. In order to gain a high temperature supply water in winter season, the system is designed to perform a cascade cycle. The filed test results show that the sea water heat source heat pump system exhibits a COP of about 5.5 in cooling mode along with a heating COP of about 4.0 in 1-stage heating mode. Cascade 2-stage heat pump system is enough to supply $60^{\circ}C$ water and heating COP is about 3.0

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.3
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• pp.81-86
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• 2006

This paper deals with a driving current fault monitor design methodology for a DDV actuation system which has a dual hydraulic power supply system, and triplex electric control capability. A fault existing among these redundant channels should be detected accurately and removed timely, and the remaining channels are to be reconfigured in order to compensate the role of a removed faulty channel. An integrated analysis on the aerodynamics, flight control laws, and DDV actuation system is essential for the design of an actuation system fault monitor. A method to define a fault transient boundary which specifies a maximum travel of an actuation system caused by the first faulty operation is proposed based on the top level requirement on the fault effect specified in MIL-F-8785C.

• Journal of Korea Entertainment Industry Association
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• v.15 no.7
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• pp.249-257
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• 2021

Recently, interest and demand for facial information processing technology that can provide non-face-to-face identity authentication and access management service using smart devices, which is an essential environmental improvement for multi-use facilities, is increasing as a way to prevent the spread of infectious diseases worldwide and to cope with social measures. This study defines a multi-use facility classification system and applied service field to establish a continuous access control system, and measures to improve the usability of the service platform considering scalability through a dual access control system and personal/measurement information type analysis, and accordingly We would like to propose a service roadmap. In addition, it aims to improve the physical access management system service platform, which is a multi-use facility application service that requires one-time and multiple-use authentication according to usage. It is expected that the methodology of this study can be applied as a service platform of a logical access control system type in the future.

• Journal of Electrical Engineering and Technology
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• v.1 no.3
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• pp.343-350
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• 2006

This paper introduces a new high efficient bi-directional, non-isolated DC/DC converter. Through variations of the topology of the conventional Cuk converter, an optimum bi-directional DC/DC converter is proposed. Voltage and current in the proposed DC/DC converter are continuous. Furthermore, the efficiency in both step-up and step-down mode is improved over that of the conventional bi-directional converter. To prove the validation for the proposed converter, simulations and experiments are executed with a 300W bi-directional converter.

• ETRI Journal
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• v.27 no.5
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• pp.533-538
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• 2005

We developed a pipelined scheduling technique of functional hardware and software modules for platform-based system-on-a-chip (SoC) designs. It is based on a modified list scheduling algorithm. We used the pipelined scheduling technique for a performance analysis of an MPEG4 video encoder application. Then, we applied it for architecture exploration to achieve a better performance. In our experiments, the modified SoC platform with 6 pipelines for the 32-bit dual layer architecture shows a 118% improvement in performance compared to the given basic SoC platform with 4 pipelines for the 16-bit single-layer architecture.

• 한국연소학회:학술대회논문집
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• 2006.10a
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• pp.110-116
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• 2006

A new measurement technique based on a two-color pyrometry and modulated LII signals to measure local soot particle temperatures has been proposed and examined experimentally. The theoretical review suggests that modulated LII signals of soot particles is suitable for a two-color pyrometry as long as the temperature increase due to laser heating remains relatively small. The modulated LII signals from ethylene and propylene diffusion flames were simultaneously measured at 550 and 750 nm by a dual measurement system that consists of optical fibers, PMT and lock-in amps. The local soot particle temperatures of diffusion flames could be obtained using a two-color pyrometry and modulated LII signal based new technique.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2003.10a
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• pp.103-107
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• 2003

현재 관측점간의 3차원 상대위치를 구하고 기준점의 측지학적 좌표ㆍ표고를 결정하는 작업을 수행하는 GPS(Global Positioning System) 측량은 신호가 전파인 관계로 대기권의 전파지연 오차를 포함하게 되며, 전리층 지연은 주파수에 반비례하는 특성이 있으므로 지역의 대소에 구분 없이 이주파수 수신기(dual-frequency GPS receiver)를 사용하여 정확하게 지연시간을 측정하고 그로 인한 측위정밀도의 정확성을 확보하고 있다. 본 연구는 비교적 낮은 가격인 일주파 수신기를 사용하여 기선거리별로 삼각점을 선점한 후 동일 시간에 관측을 실시하고 취득한 데이터 값을 추출한 후 기선거리에 따른 허용오차를 분석하고, 그 활용성 및 경제성과 일주파 수신기의 기선에 대한 사용 가능성을 분석하였다. 그 결과, 100km이내의 지역에서는 일주파 수신기 만으로도 충분히 만족스러운 결과를 얻을 수 있었다.

• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.2055-2057
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• 2004

The Ku band that has been using for the satellite communication and broadcasting would be changed to K/Ka bands. The satellite system requires the antenna structure to fabricate low loss and small antenna that is able to be integrated with other Rf circuits for both Rx and Tx. So we should design it with dual feed antennas at K/Ka bands, high isolation between two different feeds and broadband circular polarization. This paper proposes the LTCC(Low Temperature Co-fired Ceramic) process for integration with other Rf circuits and the Axial mode of the helical antenna to satisfy those requirements.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.772-775
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• 1997

A high speed tracking control for 6-6 Stewart platform manipulator is performed by employing the joint-axis sliding mode control based on dynamics. Because of the complex dynamics and kinematics of Stewart platform manipulator, two computer systems, consisting of a PC and a DSP, are adopted, so that real time tasks are run in synchronous and asynchronous modes. It is experimentally proven that the proposed control system leads to an easy to implement and effective control task, and it can achieve the high performance tracking control under the high speed and severe payload condition.