• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.511-515
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• 1999

The main factor decreasing speech recognition rate is the surrounding noise. To lower the noise effect, we generally used the filter bank at preprocessing stage. But, in this paper, we tried to recognize the 10 numeral numbers using 2-D LPC to extract image feature. At first, we obtained the result of speech-only recognition using 13th-order LPC coefficients and then, for distorted speech recognition results of ‘0’, ‘4’, ‘5’, ‘6’ and 9’, we added image parameters such as 12th-order 2-D LPC coefficients. At each frame, we extracted the 2-D LPC coefficients, and simulated recognizer with two parameters such as speech and image. Finally, for the numbers, such as ‘4’and ‘9’, the better results were obtained.

• Journal of Korea Society of Industrial Information Systems
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• v.6 no.4
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• pp.81-88
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• 2001

In this paper, a Korean digit recognition system based on a multilayer Perceptron is implemented. We also investigate the performance of widely used speech features, such as the Mel-scale filterbank, MFCC, LPCC, and PLP coefficients, by applying them as input of the proposed recognition system. In order to build a robust speech system, the experiments for demonstrating its recognition performance for the clean data as well as corrupt data are carried out. In experiments of recognizing 20 Korean digit, we found that the Mel-scale filterbank coefficients performs best in terms of recognition accuracy for the speech dependent and speech independent database even though noise is considerably added.

• Journal of the Korea Concrete Institute
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• v.17 no.4 s.88
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• pp.551-558
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• 2005

The setting and hardening of concrete is accompanied with nonlinear temperature distribution caused by development of hydration heat of cement. Especially at early ages, this nonlinear distribution has a large influence on the crack evolution. As a result, in order to predict the exact temperature history in concrete structures it is required to examine thermal properties of concrete. In this study, the convection heat transfer coefficient which presents thermal transfer between surface of concrete and air, was experimentally investigated with variables such as velocity of wind, curing condition and ambient temperature. At initial stage, the convection heat transfer coefficient is overestimated by the evaporation quantity. So it is essential to modify the thermal equilibrium considered with the boiling effect. From experimental results, the convection heat transfer coefficient was calculated using equations of thermal equilibrium. Finally, the prediction model for equivalent convection heat transfer coefficient including effects of velocity of wind, curing condition, ambient temperature and boiling effects was theoretically proposed. The convection heat transfer coefficient in the proposed model increases with velocity of wind, and its dependance on wind velocity is varied with curing condition. This tendency is due to a combined heat transfer system of conduction through form and convection to air. From comparison with experimental results, the convection heat transfer coefficient by this model was well agreed with those by experimental results.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.11
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• pp.999-1005
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• 2007

In case of an abnormal condition of control surface, the real-time estimation of aerodynamic derivatives are required for the reconfigurable control system to be flight for missions or return to the head office. The goal of this paper is to represent a technique of fault detection to the control surface as a base research to the fault tolerant control system for safety improvement of UAV. The real-time system identification for the fault detection to the control surface was applied with the recursive Fourier Transform and verified through the HILS and flight test. The failures of the control surface are detected by comparing the control derivatives in fault condition with the normal condition. As a result from the flight test, we have confirmed that the control derivatives of fault condition less than about 50% in the normal condition.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.40 no.1
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• pp.74-81
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• 2003

In this study, we'd implemented a real time embedded speech recognition system that requires minimum memory size for speech recognition engine and DB. The word to be recognized consist of 40 commands used in a PCS phone and 10 digits. The speech data spoken by 15 male and 15 female speakers was recorded and analyzed by short time analysis method, which window size is 256. The LPC parameters of each frame were computed through Levinson-Burbin algorithm and they were transformed to Cepstrum parameters. Before the analysis, speech data should be processed by pre-emphasis that will remove the DC component in speech and emphasize high frequency band. Baum-Welch reestimation algorithm was used for the training of HMM. In test phone, we could get a recognition rate using likelihood method. We implemented an embedded system by porting the speech recognition engine on ARM core evaluation board. The overall recognition rate of this system was 95%, while the rate on 40 commands was 96% and that 10 digits was 94%.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.11
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• pp.901-907
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• 2021

The present study introduces an artificial neural network (ANN) that can predict the missile aerodynamic coefficients for various missile nose shapes and flow conditions such as Mach number and angle of attack. A semi-empirical missile aerodynamics code is utilized to generate a dataset comprised of the geometric description of the nose section of the missiles, flow conditions, and aerodynamic coefficients. Data normalization is performed during the data preprocessing step to improve the performance of the ANN. Dropout is used during the training phase to prevent overfitting. For the missile nose shape and flow conditions not included in the training dataset, the aerodynamic coefficients are predicted through ANN to verify the performance of the ANN. The result shows that not only the ANN predictions are very similar to the aerodynamic coefficients produced by the semi-empirical missile aerodynamics code, but also ANN can predict missile aerodynamic coefficients for the untrained nose section of the missile and flow conditions.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.477-477
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• 2023

빗물이용시설은 집수면적에 내린 빗물을 모아 이용가능하도록 처리하는 시설이며, 일정 면적 이상의 건축물에는 법적으로 빗물이용시설을 설치·운영하여야한다. 빗물이용시설의 저류조 용량은 간편식과 시뮬레이션, 수문모형으로 산정가능하며, 설계계획 수립시 대상지역의 강우 특성, 사용수량 등 지역 특성과 목적을 고려하여 저류조 용량이 결정된다. 저류조 용량 산정시 시뮬레이션을 이용하는 방법은 수문모형 사용에 비하여 용이하지만, 일단위 물수지분석을 구현하는데까지 시간이 소요된다. 간편식은 집수면적에 규모계수 0.05를 곱하여 간단히 구할 수 있지만, 지역 특성과 목적이 고려되어있지 않으며 초기 계획수립 및 개략 평가를 제외하고는 활용에 제약이 존재한다. 이에따라, 본 연구에서는 지역적 특성을 고려한 빗물저류조의 적정 규모 산정을 위해 개선된 간편식을 개발하였다. 빗물이용시설 물수지 분석 Excel 도구를 개발하였으며, 해당 물수지분석 결과에 상수대체율 효율을 기준으로 지역별 적정 저류조 규모 산정을 위한 규모계수를 도출하였다. 빗물사용 용도로써 폭염저감, 미세먼지저감, 조경, 화장실을 채택하였으며, 용도별 1일 사용수량을 산정 및 적용하였다. 7개의 연구대상지역 물수지분석을 위해 연구지역의 최근 10년 강우·미세먼지·기온데이터를 기상청으로부터 적용하였으며, 집수면적은 500-2500m²까지 500m²씩 증분, 저류조용량은 5-700m³까지 5m³씩 증분하여 지역별 적정 저류조 용량 규모계수를 선정하였다. 그 결과 연구대상지역의 적정 저류조 용량산정시 완도군의 규모계수는 평균 0.058이었으며, 보령시의 규모계수는 평균 0.040으로 도출되었다. 본 연구를 통하여 다양한 용도의 빗물사용처에 따른 지역별 저류조 용량 선정을 위한 지원도구로써 사용될 것으로 판단한다.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2017.04a
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• pp.9-9
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• 2017

입자거동해석소프트웨어(EDEM)은 DEM(Discrete Element Method)기법을 이용한 입자 거동 전용 해석툴로 입자 유입량, 위치 등을 조절하여 입자거동과 관련된 제품 개발, 프로세스 최적화를 위한 비용 및 시간 절감에 활용도가 뛰어난 소프트웨어이다. EDEM을 활용하기 위해선 적용대상에 대한 물성치를 적용하여야 한다. 따라서 본 연구에서는 EDEM를 이용하여 현재 연구개발 중인 카드클리너 방식의 고추 선별기의 성능을 분석을 수행하기 위해 고추 물성측정 실험을 수행 하였다. EDEM을 이용한 입자거동해석에 필요한 개인 물성치에는 포아송비, 전단탄성계수, 밀도가 있다. 또한 입자-입자, 입자-Geometry 간의 상호관계를 위한 물성치인 반발계수, 정지마찰계수, 구름마찰계수가 필요하다. 공시 시료인 고추는 광주광역시 남구 승촌동 소재의 개인농가 Plastic 온실로 재배된 '천상'품종을 사용하였다. 푸아송 비와, 전단 탄성계수를 측정하기 위한 인장시험기기로는 만능인장시험기(TA-XT2, Stable Micro, 영국)를 이용하였으며, 인장에 의한 고추의 변형량 축정은 초고속카메라(NX4-SI, IDT, 미국)을 이용하였다. 밀도는 비중병법에 기초하여 질량과 부피를 측정하여 밀도를 계산하였다. 반발계수는 고추의 충돌 실험을 통해 변화한 높이를 이용하여 계산하였고, 충동 실험을 통해 변화한 높이는 초고속카메라를 이용하여 측정하였다. 정지마찰계수와 구름마찰계수는 고추의 미끄러짐이 시작하는 각도와 등속도 운동으로 구르는 각도를 초고속카메라를 이용하여 측정 후 계산하였다. 모든 실험은 3번 반복을 통해 평균값을 시험 결과 값으로 이용하였다. 고추의 대한 물성치 실험결과 고추의 푸아송 비는 0.294(std : 0.2), 전단탄성계수 4.624E+06 Pa, 밀도 $600kg/m^3$로 나타났다. 또한 입자-입자 간의 물성치인 반발계수는 0.383, 정지마찰계수는 0.455, 구름마찰 계수는 0.043로 나타났다. 추후 본 연구에서 측정한 고추의 물성치를 적용한 EDEM 입자거동해석 시뮬레이션을 통해 카드클리너 방식의 고추 선별기의 성능에 대한 분석을 하고자 한다.

• The Journal of the Korea Contents Association
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• v.15 no.11
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• pp.582-590
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• 2015

Road type classification and K-factors are important role when design of number of lane. In this study not only classifies road type and estimating of K-factor but also economic evaluation tries for feasibility verification. Road type analysis results, time of day traffic volume variation, weekend-factor and vacation-factor are large in recreation roads. Weekday traffic volume and weekend traffic volume are similar patterns in provincial roads. AADT is high and time of day traffic volume variation is small in urban roads. In this study compares with economic analysis that designing of number of lane between KHCM's K-factor and this study K-factor. Economic analysis results, designed roads by this study's K-factor reduce cost about 4,708 hundred million won. So this study's K-factor is economical on provincial 4 lane roads.

• Journal of agriculture & life science
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• v.43 no.5
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• pp.47-55
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• 2009

This study analyzes the correlation between noise and the size of urban forests. Under the assumption that the main cause of the noise m the city is the population density, the size of urban forests per capita and the ratio of urban forests with respect to the size of urban per 100 thousand persons are used for the calculation of correlations with noise. The results of the calculations of Pearson's and Spearman's correlation coefficients indicate that the increase in the size of urban forests has a significant effects in reducing the day-time as well as night-time noise for most regions in the cities. The size of urban forests within public parks has a significantly negative correlation with the noise. However, calculated correlation coefficients imply the increase in the size of total urban forests is more effective in reducing the noise than the increase in the urban forests in public parks.