• Korean System Dynamics Review
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• v.15 no.4
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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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• v.3 no.3
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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.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.7
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• pp.592-601
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• 2018

The GPS/INS integrated navigation system, which is one of the electronic equipments mounted on military aircraft store, can not directly receive GPS signals by the aircraft wing before the drop, so GPS navigation data is received from the aircraft and used for filter integration, afterwards, the integrated navigation is performed using the GPS information directly received through the antenna. In this case, it is possible to operate the mount in old aircraft without any modification of the aircraft when GPS data is transmitted using wireless. However, the delay occurs while the aircraft navigation data is transmitted to the integrated navigation filter of the aircraft store via wireless, which affects the time synchronization of the GPS measurement and the INS information, affecting the integrated navigation performance. In this paper, an algorithm to analyze and compensate the effect of generation and transmission delay that can occur when implementing GPS/INS integrated navigation system of aircraft store that receives GPS data via wireless.

• Journal of Electrical Engineering and Technology
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• v.7 no.3
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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.

• Proceedings of the Korea Multimedia Society Conference
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• 2001.11a
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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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• v.7 no.4
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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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• v.17 no.12
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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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• v.14 no.4
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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.

• Journal of Korean Society of Transportation
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• v.20 no.1
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• pp.19-38
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• 2002

To evaluate the effects of transportation system operation, usually measures of effectiveness(MOE) such as travel time, space mean speed, stop/delay ratio have been used. But, energy consumption as well as the existing MOE in transportation receives more attention as an alternative MOE in transportation operation. The purpose of this study is a development of procedure, which could measure the relative energy consumption for each alternative and compare the results. A mesoscopic simulator called INTEGRATION is used to evaluate the operation of high occupancy vehicle lane, signal optimization, lane expansion, and the application of ITS. Among those, the application of ITS shows the greatest effectiveness in energy reduction, and then lane expansion, signal optimization, and the operation of high occupancy vehicle lane in the order named. Because we don't consider the characteristics of vehicle class, Potential demand and the simulation time is just for an hour. it is recommended that a procedure for precise economic analysis and an improvement in methodology are needed in the future for the expanded application of this study.

• Proceedings of the KIEE Conference
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• 2011.07a
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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.