• Journal of Korean Society of Water and Wastewater
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• v.27 no.2
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• pp.233-239
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• 2013

Sampling rate of Hydraulic pressure data, depending on the intended use of the water distribution system is an important factor. If sampling interval of hydraulic data is short, that will be more useful but it demand a lot of expense for maintenance. In this study, based on simulation of water distribution system 2 khz data, statistical techniques of student t distribution, non-exceedance probability using the optimal sampling rate for research.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2011.11a
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• pp.78-81
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• 2011

In this paper, we propose an additional data transmission scheme using multiple-antennas with backward compatibility for legacy ATSC (Advanced Television Systems Committee) terrestrial DTV (digital television) receivers. The proposed scheme improves the data rate and bit error rate performance compared to the conventional single antenna transmission scheme for additional data. Also, the proposed scheme guarantees backward compatibility for legacy ATSC DTV receivers.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2011.11a
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• pp.247-250
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• 2011

In this paper, we propose an additional data transmission scheme using multiple-antennas with backward compatibility for legacy ATSC (Advanced Television Systems Committee) terrestrial DTV (digital television) receivers. The proposed scheme improves the data rate and bit error rate performance compared to the conventional single antenna transmission scheme for additional data. Also, the proposed scheme guarantees backward compatibility for legacy ATSC DTV receivers.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.15 no.9
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• pp.738-744
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• 1990

This paper proposed a real-time memory storage method and an improved sample data method from given data of the speech signal, so, the isolated word recognition system using a back-propagation learning algorithm of the neural netwrok is studied. The recognition rate and the error rate are compared with the new sample data sets generated from small sets of given sample data by the node nunber variatiion of each layer. In this result, the recognition rate of 95.1% was achived.

• Journal of the Optical Society of Korea
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• v.16 no.2
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• pp.107-114
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• 2012

In this paper, we propose a new modulation scheme called multi-coded variable pulse position modulation (MC-VPPM) for visible light communication systems. Two groups of signals (Pulse Width Modulation (PWM) and Pulse Position Modulation (PPM) groups) are multi-coded by orthogonal codes for transmitting data simultaneously. Then, each multi-level value of the multi-coded signal is converted to pulse width and position which results in not only an improved data rate, but also a processing gain in reception. In addition, we introduce average duty ratio and cyclic shift concepts in PWM through which dimming control for light illumination can be supported without any degradation in communication performance. Through simulation, we confirm that the proposed MC-VPPM shows a comparable BER curve and much greater achievable data rate than the conventional VPPM scheme using a visible light optical channel environment.

• ETRI Journal
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• v.5 no.3
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• pp.9-15
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• 1983

This paper describes the applicable method of part stress analysis failure rate prediction for electronic components in the MIL-HDBK-217D. The part stress analysis method requires the great amount of detailed informations, such as operating temperature, operating environment, etc. This paper calculates the failure rate of electronic components using the computer program. The program was written by Fortran V and has four basic units as follows (1) Raw data file (2) Failure rate calculation (3) Reliability modelling(Series only) (4) New data file The Functions and structure of the program are illustrated.

• Proceedings of the Korean Society of Computer Information Conference
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• 2019.07a
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• pp.327-328
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• 2019

본 논문에서는 레일리 페이딩 채널 모델하에서 평균데이터 전송률을 최대화 할 수 있는 목표 데이터 전송률을 분석하였다. 같은 무선채널환경에서 목표 데이터 전송률이 높아질수록 오류 없이 전송될 확률은 낮아진다. 반면, 목표 데이터 전송률이 낮아지면 오류 없이 전송될 확률은 높아지지만, 한번에 보내는 데이터 양이 작아지게 된다. 따라서, 주어진 무선 채널 환경을 최대로 활용하기 위해서는 오류 전송 확률과 목표 데이터 전송률을 고려하여 최대 평균 데이터 전송률을 얻기 위한 조건에 대한 분석이 선행되어야 한다. 본 논문에서는 평균 데이터 전송률을 정의하고, 이를 최대화하기 위한 목표 데이터 전송률을 분석하였다. 분석 결과는 몬테카를로 모의 시뮬레이션을 통하여 정확성을 증명하였다.

• Journal of Information Processing Systems
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• v.14 no.6
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• pp.1508-1520
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• 2018

In this paper, we propose an improved model to provide users with a better long-term prediction of waterworks operation data. The existing prediction models have been studied in various types of models such as multiple linear regression model while considering time, days and seasonal characteristics. But the existing model shows the rate of prediction for demand fluctuation and long-term prediction is insufficient. Particularly in the deep running model, the long-short-term memory (LSTM) model has been applied to predict data of water purification plant because its time series prediction is highly reliable. However, it is necessary to reflect the correlation among various related factors, and a supplementary model is needed to improve the long-term predictability. In this paper, convolutional neural network (CNN) model is introduced to select various input variables that have a necessary correlation and to improve long term prediction rate, thus increasing the prediction rate through the LSTM predictive value and the combined structure. In addition, a multiple linear regression model is applied to compile the predicted data of CNN and LSTM, which then confirms the data as the final predicted outcome.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.29 no.1
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• pp.21-26
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• 2019

Objective: The aim of this study is to analyze an excess trend for domestic permissible exposure limit of trichloroethylene based on previous literature review. Materials and Methods: The research object is a trichloroethylene among 13 chemical substances regulated with PEL(Permissible Exposure Limit) in Occupational Safety and Health Act. The information utilized from this study is the work environment measurement data from 2004 to 2013. The highest level among concentration data measured at various workplaces was selected as a representative value through data process. N.D. (Not Detected) data was considered as 1/2 of LOD(Limit Of Detection). Results: Among work environment measurement data between 2004 and 2013, the highest number of excess workplace and excess rate(24 sites & 1.15%) was observed in 2008's data when applying the PEL(50 ppm) of trichloroethylene. When they are compared with the ACGIH's TLV-TWA(10 ppm), 2008's data showed the highest number of excess workplace and excess rate(175 sites & 8.37%). The number of excess workplace and excess rate related to PEL of trichloroethylene showed increase trend in 2005 but tended to decrease after 2008. Conclusions: Based on the results obtained from this study, the exposure level of trichloroethylene in case of domestic workers is not considered as a safe phase regardless of the year of work environment measurement year. Thus, a strictly preventive management in workplace should be provided for reducing exposure level of trichloroethylene.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.19 no.2
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• pp.146-154
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• 2023

In nuclear power plants, ultrasonic test for pipe wall thickness measurement is used during periodic inspections to prevent pipe rupture due to pipe wall thinning. However, when measuring pipe wall thickness using ultrasonic test, a significant amount of measurement error occurs due to the on-site conditions of the nuclear power plant. If the maximum pipe wall thinning rate is decided by the measured pipe wall thickness containing a significant error, the pipe wall thinning rate data have significant uncertainty and systematic overestimation. This study proposes preprocessing of pipe wall thinning measurement data using support vector machine regression algorithm. By using support vector machine, pipe wall thinning measurement data can be smoothened and accordingly uncertainty and systematic overestimation of the estimated pipe wall thinning rate data can be reduced.