• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.2078-2081
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• 2003

This paper presents the studies on prediction models of tropospheric scintillation. The prediction scintillation models are Karasawa and ITU-R , which can be improved for different locations and circumstances. In this paper, the investigation of average time between variance ${\sigma}_n\;^2$ and the wet part of refractivity $N_{wet}$ under various conditions of meteorological parameters have been carried out at King Mongkut’s Institute of Technology Lankrabang , Bangkok , Thailand , in the range of Ku-band (12.260 GHz) on high elevation angle from Thaicom2 satellite. From the studies results shows that average period of time of 30 days are best suitable for find out the relation between average time variance ${\sigma}_n\;^2$ and the wet part of refractivity $N_{wet}$ according to Karasawa model, the average time variance is express as ${\sigma}_n\;^2=(0.003N_{wet}-0.1313)^2$ , the appropriation model for occurrence of scintillation has been analyzed and experimental results are carried out.

• 조명전기설비학회논문지
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• 제18권5호
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• pp.83-89
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• 2004

최근 전력계통의 대형화와 중조류 설비의 증가 등으로 계통내부에서 소모되는 무효전력 급증에 따라 계통전압관리차원에서 부하역률 관리의 중요성이 새롭게 대두되고 있다. 따라서 본 논문에서는 최소자승법(Least Square Method)을 이용하여 변압기 무효전력 손실량을 산출하였으며, 유량평균법(Average Flow Method)을 사용하여 부하특성에 따른 지역별, 계절별, 시간대별 부하역률 대표모델을 수립하였다.

• 대한임베디드공학회논문지
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• 제13권2호
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• pp.83-91
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• 2018

With the development of IT (Information Technology) technology, embedded system and network technology are combined and used in various environments such as military environment as well as everyday life. In this paper, we propose a new airdropped distributed mobility model (ADMM) modeling the dispersion falling of the direct shot of a cluster bomb, and we compare and analyze some representative MANET routing protocols in ADMM in ns-3 simulator. As a result of the analysis, we show OLSR routing protocol is promising in ADMM environment in the view points of packet delivery ratio (PDR), end to end delay, and jitter. In addition, we propose a new adaptation scheme for OLSR, AND-OLSR (Average Node Distance based adaptive-OLSR) to improve the original OLSR in ADMM environment. The new protocol calculates the average node distance, adapts the period of the control message based on the average node distance increasing rate. Through the simulation study, we show that the proposed AND-OLSR outperforms the original OLSR in PDR and control message overhead.

• 산업기술연구
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• 제27권A호
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• pp.85-94
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• 2007

This study, regarding curved channel, was performed to compare and analyze hydraulic characteristics and the speed of water and water level for left bank and right bank through hydraulic model experiments and numerical analysis. Real channels that had characteristics of curved channel were selected as objectives. In order to easily operate one and two dimensional numerical analysis and comparison for total 2.4Km model channel, measuring point was set up as 200m. HEC-RAS model was applied as one dimensional numerical analysis program and SMS model was used as two dimensional numerical analysis program. In respect of speed of water, the average speed of water for right bank recorded 8.33m/s in a model experiment and 3.08m/s, 8.57m/s were average speed of water for right bank in one dimensional and two dimensional numerical analysis. The average speed of water of two dimensional numerical analysis was quite similar to that of model experiments. Also, as for water level, maximum observational errors between one and two dimensional numerical analysis for right and left bank of model experiments were 0.66m, 0.84m and 0.28m, 0.48m for each. It was found that two dimensional numerical analysis had a similar result to hydraulic model experiments. Accordingly, from the result of this study, two dimensional numerical analysis should be used rather than one dimensional numerical analysis, when numerical analysis for curved channel is conducted.

• 한국정밀공학회지
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• 제24권4호
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• pp.93-101
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• 2007

Aluminum alloy which is one of the light materials has been tried to apply to light weight vehicle body. In order to do that, welding technology is very important. In case of the aluminum laser welding, the strength of welded part is reduced due to porosity, underfill, and magnesium loss. To overcome these problems, laser welding of aluminum with filler wire was suggested. In this study, experiment about laser welding of AA5182 aluminum alloy with AA5356 filler wire was performed according to process parameters such as laser power, welding speed and wire feed rate. The tensile strength was measured to find the weldability of laser welding with filler wire. The models to estimate tensile strength were suggested using three regression models and one neural network model. For regression models, one was the multiple linear regression model, another was the second order polynomial regression model, and the other was the multiple nonlinear regression model. Neural network model with 2 hidden layers which had 5 and 3 nodes respectively was investigated to find the most suitable model for the system. Estimation performance was evaluated for each model using the average error rate. Among the three regression models, the second order polynomial regression model had the best estimation performance. For all models, neural network model has the best estimation performance.

• Journal of the Korean Data and Information Science Society
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• 제27권4호
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• pp.969-977
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• 2016

야외에서 재배되는 주요 채소류의 생산에 대한 기상변화의 영향력이 점차 커지고 있다. 기상변화로 인한 농작물 생산량의 변화는 공급과 수요의 불안정과 물가안정의 불안요소로 작용하고 있다. 본 논문에서는 패널회귀모형을 이용하여 기상상태에 따른 마늘의 생산량을 추정하였다. 2006년부터 2015년까지의 마늘 주산지 15곳의 10a당 마늘 생산량과 해당 지역의 기상자료를 사용하였다. 7가지 기상요인 (평균기온, 평균최저기온, 평균최고기온, 누적강수량, 누적일조시간, 평균상대습도, 평균지면온도)의 월별 (1월-12월)자료인 총 84개 기상변수중 다중회귀분석 단계선택방법을 통하여 7가지 기상변수를 선택하여 패널회귀모형에 사용하였다. 고정효과 모형과 확률효과 모형을 구분하는 하우스만 검정을 통하여 확률효과 모형으로 분석한 결과 평균최고기온 (1월), 누적강수량 (3월, 10월), 누적일조시간 (4월, 10월)등이 마늘 생산량 추정에 유의한 변수로 나타났다. 또한 연도별로 추정된 생산량 추정값의 추이가 실제 생산량과 동일한 추세를 보이고 있어 제안된 패널 회귀 모형이 잘 적합됨을 확인할 수 있다.

• 대한음성학회지:말소리
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• 제59호
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• pp.89-99
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• 2006

This paper proposes a new structural head-related transfer function(HRTF) model to produce sounds in a virtual environment. The proposed HRTF model generates 3-D sounds by using a head model, a pinna model and the proposed distance model for azimuth, elevation, and distance that are three aspects for 3-D sounds, respectively. In particular, the proposed distance model consists of level normalization block distal region model, and proximal region model. To evaluate the performance of the proposed model, we setup an experimental procedure that each listener identifies a distance of 3-D sound sources that are generated by the proposed method with a predefined distance. It is shown from the tests that the proposed model provides an average distance error of $0.13{\sim}0.31$ meter when the sound source is generated as if it is 0.5 meter $\sim$ 2 meters apart from the listeners. This result is comparable to the average distance error of the human listening for the actual sound source.

• 한국경영과학회지
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• 제24권2호
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• pp.109-119
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• 1999

The average shadow price is a substitute for the traditional marginal shadow price. It can serve as a standard for decision making problems about the economic resources where the marginal analysis gives no useful information. This paper treats the average shadow price in pure integer programming and shows some stability properties of it. This implies that the values of the average shadow prices once computed are reliable within some extent of the data perturbations of the integer programming model.

• Journal of the Korean Data and Information Science Society
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• 제18권4호
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• pp.945-953
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• 2007

In this paper, we propose a smoothing and thus noise-reducing method of data sequences for stock price prediction with hidden Markov models, HMMs. The suggested method just uses simple moving average. A proper average size is obtained from forecasting experiments with stock prices of bank sector of Korean Exchange. Forecasting method with HMM and moving average smoothing is compared with a conventional method.

• 대한치과교정학회지
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• 제39권1호
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• pp.6-17
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• 2009

본 연구의 목적은 레이저 스캔 디지털 모형과 콘 빔 CT (CBCT) 영상을 모형 분석에 사용할 수 있는지를 평가하는 것이었다. 이를 위해 인접면에 금속 수복물을 갖지 않는 영구치열기의 20명의 교정환자에서 CBCT 영상, 석고 모형, 디지털 모형을 제작하여 각각에서 모형 분석을 시행한 후 그 계측치들을 비교하였다. 연구 결과 디지털 모형과 석고 모형을 비교 시, 치아 폭경 계측치 차이의 평균은 0.01-0.20 mm였으며, 치열궁 길이 부조화 계측치 차이의 평균은 상악 0.41 mm, 하악 0.82 mm였고, Bolton 부조화 값 차이의 평균은 전치부에서 0.17 mm, 전체에서 0.44 mm로 나타났다. CBCT 영상과 석고 모형을 비교 시 치아 폭경 계측치 차이의 평균은 0.01-0.22 mm였으며, 치열궁 길이 부조화 계측치 차이의 평균은 상악 0.43 mm, 하악 0.32 mm였고, Bolton 부조화 값 차이의 평균은 전치부에서 0.35 mm, 전체에서 1.25 mm로 나타났다. 디지털 모형과 CBCT 영상의 모형 분석을 석고 모형의 모형 분석에 비교해 볼 때 몇몇 계측치 들에서 유의한 차이가 있었으나 그 차이가 크지 않으므로 임상에서 활용 가능할 것으로 판단된다.