• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.11a
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• pp.59-60
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• 2005

OFDM communication system is effective for the high data rate transmission in the frequency selective fading channel. Since OFDM has high PAPR, OFDM signal may be distorted by the nonlinear HPA. In this paper, we propose an combined SLM and PTS method for reducing the PAPR in OFDM communication system. Proposed method increased some system complex in comparison with exiting method..

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.2
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• pp.40-46
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• 2012

In this study, numerical analysis was conducted to understand the flow characteristics of lubrication system in a manual transmission installed in a commercial vehicle. Also, the analysis was conducted with the purpose of improving the heat and lubricative condition of the transmission. Discharging flow rates on each oil hole outlet according to various engine rotating speed and the length of oil hole branch was calculated. In conclusion, as engine rotating speed is high and the length of oil hole branch is long, the discharging flow rate is high by virtue of the centrifugal force. In addition, this study proposed data for optimal design of lubrication system in manual transmission for a commercial vehicle.

• Journal of IKEEE
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• v.23 no.3
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• pp.934-940
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• 2019

In this paper, we propose a Reverse Differential Chaos Shift Keying (RE-DCSK) system for low cost, high reliability and high data rate non-coherent chaos communication .In RE-DCSK, reference signals are transmitted in the first slot as in the conventional differential chaos shift modulation scheme (DCSK) and in the second slot a time inversion block strengthens the autocorrelation of the chaos signal and uses the orthogonality of the two signals to obtain the information signal. RE-DCSK enables relatively double the data rate compared to DCSK and also improves the security of communications without any additional cost of system complexity.To prove its effectiveness, we analyze it through Rayleigh fading channel and additional white Gaussian noise (AWGN) channel based on the derived BER expression. The BER performance of the proposed system is improved when compared with the CDSK and DCSK system using AWGN channel.

• Journal of Electrical Engineering and Technology
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• v.12 no.2
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• pp.937-943
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• 2017

To design an automatic steering controller with high performance for autonomous vehicle, it is necessary to have a precise model of the lateral dynamics with respect to the steering command input. This paper presents an empirical modeling of the steering system for an autonomous vehicle. The steering system here is represented by three individual transfer function models: a steering wheel actuator model from the steering command input to the steering angle of the shaft, a dynamic model between the steering angle and the yaw rate of the vehicle, and a dynamic model between the steering command and the lateral deviation of vehicle. These models are identified using frequency response data. Experiments were performed using a real vehicle. It is shown that the resulting identified models have been well fitted to the experimental data.

• Phonetics and Speech Sciences
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• v.6 no.1
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• pp.105-117
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• 2014

The purpose of this study was to (1) establish a Korean adult normative database for phonatory aerodynamic measures obtained with the KayPENTAX Phonatory Aerodynamic System (PAS) Model 6600, (2) investigate the intra-subject reliability of these measures across three testing sessions, and (3) examine the effect of gender on those measures. 170 healthy normal speakers (70 men and 100 women) between the ages 18 and 49 years participated in the study. The PAS protocol of maximum phonation and voicing efficiency were conducted and 25 measures were obtained. All aerodynamic measures taken in this study demonstrated high intra-subject reliability in clinical aspect. There were no significant effect of gender in the measures related to sound pressure and subglottal pressure. However, significant differences for gender were found for phonation time, airflow rate, expiratory volume, aerodynamic power, SPL range, pitch range, mean pitch, aerodynamic resistance, and aerodynamic efficiency. Clinicians should be aware of significant gender effects in some aerodynamic parameters when interpreting the data obtained from PAS.

• Journal of Satellite, Information and Communications
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• v.1 no.1
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• pp.40-47
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• 2006

The next-generation mobile communication system are required to provide high-data-rate and high quality transmission over hostile radio channels. Orthogonal Frequency Division Multiplexing(OFDM) technique regarded as a most promising solution in mobile environment. This paper considers the issue of efficient subcarrier allocation for OFDM system in multi-service application. Proposed algorithm can consider channel gain of each service and divide subchannel. Proposed method considers priority of service and divide more subchannels in high priority service. When proposed algorithm compares with existent algorithm, the convergence rate improves and the calculation amount is decreased.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.29 no.4
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• pp.100-106
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• 2006

We analyze a voice/data integrated traffic model of the cellular mobile communication system with hybrid guard channels for voice and handoff calls. In a multi-service integrated wireless environment, quality of service guarantee is crucial for smooth transportation of real time information. Real time voice traffic requires a guaranteed upper bounded on both delay and packet error rate, whereas data traffic does not. Voice traffic has high transmission priority over data packets. Thus one of the important problems is the design of admission control schemes which can efficiently accommodate the differential quality of service requirements. In this paper, a hybrid guard channel scheme is considered in which arriving calls are assigned channels as long as the number of busy channels in the cell is below a predetermined first threshold. When the number of busy channels reaches the first threshold, new originating data calls are queued in the infinite data buffer. Then reaches second threshold, only handoff calls are assigned the remaining channels and new originating voice calls are blocked. We evaluate the system by a two-dimensional Markov chain approach and generating function method and obtain performance measures included blocking probability and forced termination probability.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2019.05a
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• pp.240-241
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• 2019

Construction disasters have more distinctive characteristics than other industrial disasters. Since it is likely that construction disasters will spread to severe accidents, the accident mortality rate is very high compared to the disaster incidence rate. Therefore, the purpose of this study is to compare and analyze the operation status of construction risk assessment by domestic large and medium sized construction companies to prepare improvement direction of risk assessment system. The survey results for safety management experts of construction companies are as follows: Large companies have developed and utilized risk assessment systems in their respective companies, while small and medium construction companies have developed and evaluated risk factors through the Excel program. Rather than performing risk assessment tasks based on historical safety accident data, construction companies have limitations in developing risk factors and preparing solutions with suppliers for each major construction. Therefore, it is necessary to prepare a risk assessment system in the future by analyzing the types of safety accidents, such as the safety accident data of each company as well as the safety accident data.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.9
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• pp.1672-1678
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• 2007

The communication systems and characteristics of transmit are very importance a serious view of ubiquitores society. The high rate systems have to construct for data of voice, graphics and moving-video with the multimedia to transmit on the low frequency band. The rate of data are relation that there are the bandwidth of line and channels, the bit per second and communication-systems. This paper study for the error performance of 2, 4 8 level FSK to transmit amount of data in the communication systems and design to FDM system.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.5
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• pp.523-529
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• 2009

Smart sensor is known as intelligent sensor, it is different with other conventional sensors in the case of intelligent system embedded on it. Smart sensor has many benefits e.g. low-cost in usage, self-decision and self-diagnosis abilities. This sensor consists of perception element(sensing element), signal processing and technology of communication. In this work, a bridge and structure of smart sensor has been investigated to be capable to condition monitoring routine. This investigation involves low power consumption, software programming, fast data acquisition ability, and authoritativeness warranty. Moreover, this work also develops smart sensor to be capable to perform high sampling rate, high resolution of ADC, high memory capacity, and good communication for data transfer. The result shows that the developed smart sensor is promising to be applied to various industrial fields.