• 한국시스템다이내믹스연구
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• 제15권4호
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• pp.61-84
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• 2014

This study aims to explore the development and application of a simulated skills package designed to improve nursing students' knowledge integration and their system thinking(ST) skills about congestive heart failure(CHF) and to identify the change in students' ST levels using a ST-based learning approach. A simulated learning support package was developed by nurse educators and ST experts. The developed program was implemented with 35 third-year nursing students from S university in Seoul. The subjects improved their ST skills regarding CHF after intervention. Mean test scores for students completing the program were significantly higher than pre-intervention scores, including measures of direction of causality, polarity of causal relationship, feedback loop, polarity of feedback loop (reinforcing, balancing) and time delay (t=2.26~6.53, p=.030~p<.001). It is suggested that more educational programs be developed on various topics in order for nursing students to improve their ST skills as well as knowledge integration in clinical nursing practicum packages.

• Journal of information and communication convergence engineering
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• 제3권3호
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• pp.142-145
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• 2005

In this paper, a new programmable DLL (delay locked loop) based clock synthesizer is proposed. DLL has several inherent advantages, such as no phase accumulation error, fast locking and easy integration of the loop filter. This paper proposes a new programmable DLL that includes a PFD(phase frequency detector), a LSI(lock status indicator), and a VCDL(voltage controlled delay line) to generate multiple clocks. It can generate clocks from 3 to 9 times of input clock with $2{\mu}s$ locking time. The proposed DLL operating in the frequency range of 300MHZ-900MHz is verified by the HSPICE simulation with a $0.35{\mu}m$ CMOS process.

• 한국항공우주학회지
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• 제46권7호
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• pp.592-601
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• 2018

군용항공기에 장착되는 전자 장비 중 하나인 항공장착물 GPS/INS 통합항법장치는 투하전에는 항공기 날개에 가려 GPS 위성 신호의 직접적인 수신이 불가능하므로 항공기로부터 GPS 항법 데이터를 전달 받아 필터 통합에 이용하고, 투하 후에는 안테나를 통해 직접 수신한 GPS 정보를 이용하여 통합 항법을 수행한다. 이때, 무선을 이용하여 GPS 항법데이터를 전송할 경우 항공기의 별다른 개조 없이 구형 항공기에서도 운용이 가능하다. 그러나 항공기의 항법데이터가 무선을 통해 장착물의 통합항법필터에 전달되기까지 지연이 발생하게 되며, 이는 GPS 측정치와 INS 정보의 시각동기에 영향을 미쳐 통합항법 성능에 영향을 미치게 된다. 이에 본 논문에서는 무선을 통하여 GPS 데이터를 수신하는 항공장착물의 GPS/INS 통합항법시스템을 구현할 때 발생할 수 있는 생성 및 전송지연의 영향을 분석하고 이를 보상하는 알고리즘을 제안하였다.

• Journal of Electrical Engineering and Technology
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• 제7권3호
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• pp.366-375
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• 2012

This paper describes a design and temporal analysis of a hardware-in-the-loop (HIL) simulation environment for testing a motor control unit (MCU). The design concepts and main characteristics including unavoidable time delays of each component module are described. From temporal analysis results according to the module integration method, an appropriate solution is proposed to fix and minimize time delays. In order to verify the effectiveness of the proposed solution, the HIL test results are compared with the results of experiments and an offline simulation.

• 한국멀티미디어학회:학술대회논문집
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• 한국멀티미디어학회 2001년도 추계학술발표논문집
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• pp.85-90
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• 2001

본 논문에서는 한국어 숫자음 인식을 위한 시간 지연 신경망(Time delay neural network-TDNN)과 은닉 마르코프 모델(Midden Markov Model-HMM)의 결합 방법에 대해서 연구하였고 그 성능을 측정하였으며, 기존의 시스템과 비교 평가하였다. 이 알고리즘은 TDNN과 HMM의 구조적인 결합에 기반하고 있는데 TDNN의 두번째 은닉층의 출력이 HMM의 입력으로 들어가도록 구성되었다. 그러면 HMM은 TDNN의 출력으로 각 단어에 대해서 훈련과정을 거치게 된다. 이렇게 구성된 인식알고리즘은 TDNN의 뛰어난 단기간(Short-time)분류 기능과 HMM의 시간 정렬(time-warping) 능력을 동시에 갖게 된다. 위의 과정을 컴퓨터 시뮬레이션을 이용하여 구현하였으며, 한사람의 음성을 녹음하여 실험한 결과 기존의 TDNN만으로 만들어진 인식기보다는 3%, HMM만으로 구성된 인식기 보다는 5.7% 나은 성능을 얻을 수 있었다.

• Journal of Positioning, Navigation, and Timing
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• 제7권4호
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• pp.295-305
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• 2018

Network RTK is a highly practical technology that can provide high positioning accuracy at levels between cm~dm regardless of user location in the network by extending the available range of RTK using reference station network. In particular, unlike other carrier-based positioning techniques such as PPP, users are able to acquire high-accuracy positions within a short initialization time of a few or tens of seconds, which increases its value as a future navigation system. However, corrections must be continuously received to maintain a high level of positioning accuracy, and when a time delay of more than 30 seconds occurs, the accuracy may be reduced to the code-based positioning level of meters. In case of SSR, which is currently in the process of standardization for PPP service, the corrections by each error source are transmitted in different transmission intervals, and the rate of change of each correction is transmitted together to compensate the time delay. Using these features of SSR correction is expected to reduce the performance degradation even if users do not receive the network RTK corrections for more than 30 seconds. In this paper, the simulation data were generated from 5 domestic reference stations in Gunwi, Yeongdoek, Daegu, Gimcheon, and Yecheon, and the network RTK and SSR corrections were generated for the corresponding data and applied to the simulation data from Cheongsong reference station, assumed as the user. As a result of the experiment assuming 30 seconds of missing data, the positioning performance compensating for time delay by SSR was analyzed to be horizontal RMS (about 5 cm) and vertical RMS (about 8 cm), and the 95% error was 8.7 cm horizontal and 1cm vertical. This is a significant amount when compared to the horizontal and vertical RMS of 0.3 cm and 0.6 cm, respectively, for Network RTK without time delay for the same data, but is considerably smaller compared to the 0.5 ~ 1 m accuracy level of DGPS or SBAS. Therefore, maintaining Network RTK mode using SSR rather than switching to code-based DGPS or SBAS mode due to failure to receive the network RTK corrections for 30 seconds is considered to be favorable in terms of maintaining position accuracy and recovering performance by quickly resolving the integer ambiguity when the communication channel is recovered.

• Journal of Mechanical Science and Technology
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• 제17권12호
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• pp.2087-2098
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• 2003

The development of numerical mathematical model to calculate both the static and dynamic characteristics of a multi-shaft gas turbine consisting of a single combustion chamber, including advanced cycle components such as intercooler and regenerator is presented in this paper. The numerical mathematical model is based on the simplified assumptions that quasi-static characteristic of turbo-machine and injector is used, total pressure loss and heat transfer relation for static calculation neglecting fuel transport time delay can be employed. The supercharger power has a cubical relation to its rotating velocity. The accuracy of each calculation is confirmed by monitoring mass and energy balances with comparative calculations for different time steps of integration. The features of the studied gas turbine scheme are the starting device with compressed air volumes and injector's supercharging the air directly ahead of the combustion chamber.

• Journal of electromagnetic engineering and science
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• 제14권4호
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• pp.376-381
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• 2014

We present a CMOS rail-to-rail class-AB amplifier using dynamic current biasing to improve the delay response of the error amplifier in a low-dropout (LDO) regulator, which is a building block for a wireless power transfer receiver. The response time of conventional error amplifiers deteriorates by slewing due to parasitic capacitance generated at the pass transistor of the LDO regulator. To enhance slewing, an error amplifier with dynamic current biasing was devised. The LDO regulator with the proposed error amplifier was fabricated in a $0.35-{\mu}m$ high-voltage BCDMOS process. We obtained an output voltage of 4 V with a range of input voltages between 4.7 V and 7 V and an output current of up to 212 mA. The settling time during line transient was measured as $9{\mu}s$ for an input variation of 4.7-6 V. In addition, an output capacitor of 100 pF was realized on chip integration.

• 대한교통학회지
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• 제20권1호
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• pp.19-38
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• 2002

일반적으로 교통운영 시스템에 대한 효과를 평가하기 위해서 구간통행 시간, 통행속도, 지정체율 등과 같은 효과척도(MOE: measure of effectiveness)가 사용된다. 그러나, 에너지에 대한 관심이 극히 높은 상황에서는 기존의 교통측면의 효과척도 이외에 에너지소모라는 효과척도가 교통운영시스템의 MOE로서 대안평가에서 점차로 중요한 영향을 발휘할 수 있다. 본 연구는 교통운영방식별 에너지효율성에 대한 평가를 위해 (기존에 주로 사용되던 효과척도로서의 구간평균속도, 구간평균통행시간, 지정체 뿐 아니라), 에너지 소모 또한 대안평가에 사용할 수 있을 것으로 판단하여, 각 대안별 에너지 소모를 상대적으로 측정하여 볼 수 이는 절차를 개발하고 상호 그 결과를 비교하고자 하였다. 이를 위해 메조모형 시뮬레이터인 Integration이 사용되었으며, HOV 차로 운영, 신호 최적화, 차로 확장, ITS 적용에 대한 대안의 평가를 수행하였다. 이중ITS의 적용이 에너지 절감에 가장 큰 효과가 있는 것으로 나타났으며, 차로확장, 신호최적화, HOV 차로 운영 순으로 에너지 절감 효과가 나타났다. 본 연구는 차종에 대한 특성의 고려, 잠재수요에 대한 고려를 하지 않았으며, 분석 기간이 단지 첨두 1시간에 그쳤기 때문에 향후 이러한 현실적 요소에 대한 고려 및 시스템의 확대적용에 있어 보다 정확한 경제성 분석절차 및 방법론적 개선이 요구된다고 하겠다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.1734-1735
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• 2011

In case of inspection on aluminum castings, traditional RT (Radiographic Testing) method have been utilized for its advantages in interpretation, cost and perpetual storage. But it has disadvantages like time consumption in film processing, low efficiency in storage and environmental pollution. In this thesis, a DRS (Digital Radiography System) utilizing X-Ray TDI Camera (Time Delay and Integration Camera) is developed. Inspections on aluminum castings are performed using the developed Digital Radiography System, DRS and reviewed if newly developed system can substitute for the traditional method.