• Journal of Biosystems Engineering
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• 제29권2호
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• pp.109-120
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• 2004

To obtain basic information for precision agriculture, spatial variability of rice growth condition was evaluated in 100m ${\times}$100m paddy field. The rice growth condition of four hundred locations in the field were investigated to analyze the spatial variability of their properties ; SPAD, plant length and tiller number. Geostatistical analysis was carried out to examine within-field spatial variability using semivariograms and kriged maps as well as descriptive statistics. Descriptive statistics showed that the coefficient of variation for SPAD, plant length, and tiller number exceeded 5.70 %, suggesting a relatively high variability. Geostatistical analysis indicated a high spatial dependence for all the properties except for the second tiller number. The range of spatial dependence was about 20 m for SPAD, plant length, and tiller number. Based on the results of spatial dependence, kriged maps were prepared for the properties to analyse their spatial distribution in the field. The results reflected the history of field management. In conclusion, the need for site-specific field management and possibility of precision agriculture were demonstrated even in an almost flat paddy field.

• Journal of Biosystems Engineering
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• 제33권5호
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• pp.355-361
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• 2008

As agricultural machinery has become larger and tillage practices have changed in recent decades, compaction as a result of wheel traffic and tillage has caused increasing concern. If strategies to manage compaction, such as deep tillage, could be applied only where needed, economic and environmental benefits would result. For such site-specific compaction management to occur, compacted areas within fields must be efficiently sensed and mapped. We previously developed an on-the-go soil strength profile sensor (SSPS) for this purpose. The SSPS measures within-field variability in soil strength at five soil depths up to 50 cm. Determining the variability structure of SSPS data is needed for site-specific field management since the variability structure determines the required intensity of data collection and is related to the delineation of compaction management zones. In this paper, soil bin data were analyzed by a spectral analysis technique to determine the variability structure of the SSPS data, and to investigate causes and implications of this variability. In the soil bin, we observed a repeating pattern due to soil fracture with an approximate 12- to 19-cm period, especially at the 10-cm depth, possibly due to cyclic development of soil fracture on this interval. These findings will facilitate interpretation of soil strength data and enhance application of the SSPS.

• 한국운동역학회지
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• 제17권1호
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• pp.129-134
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• 2007

The purpose of this study was to determine the variability of components of the vertical ground reaction force signal to seek the suitable number of attempt datum to be analyzed during running at 2m/s and 4m/s. For this study, six subjects (height mean:$174.5{\pm}4.4cm$, weight $671.5{\pm}116.4N.$, age:$25.0{\pm}yrs.$) were selected and asked to run at least 3 times each run condition randomly. FFT(fast Fourier transform) was used to analyze the frequency domain analysis of the vertical ground reaction forces signal and an accumulated PSD (power spectrum density) was calculated to reconstruct the certain signal. To examine the deviation of the vertical ground reaction between signals collected from an different number of attempt, variability of frequency, magnitude of passive peak, time up to the passive peak and maximum load rate were determined in a coefficient of variance. The variability analysis revealed that when analyze the vertical reaction force components at 2m/s speed running, which belongs to slow pace relatively, it would be good to calculate these components from signal of one attempt, but 4m/s speed running needs data collected from two attempts to decrease the deviation of signal between attempts. In summary, when analyzing the frequency and passive peak of the vertical reaction force signal during the fast run, it should be considered the number of attempt.

• 정보처리학회논문지D
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• 제16D권5호
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• pp.791-800
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• 2009

최근 서비스 지향 아키텍처 (Service Oriented Architecture SOA) 기반의 애플리케이션 개발에 맞게 비즈니스 프로세스의 유연성을 확보하고 재사용을 증진시키기 위하여 비즈니스 프로세스 패밀리 모델 (Business Process Family Model: BPFM)이 제시되었다. BPFM은 소프트웨어 프로덕트 라인 방법의 가변성 분석 기법을 사용하여 비즈니스 프로세스 군 (family)에서 나타날 수 있는 가변성을 분석하여 이를 명시적으로 표현하고 있는 모델이다. BPFM으로부터 여러 개의 비즈니스 프로세스 모델 (Business Process Model: BPM)을 개발하기 위해서는 가변성 결정 및 가지치기(Decision and Pruning) 과정을 거쳐야 한다. 이 때 가변성 사이에는 서로 협력적 또는 배타적인 관계를 가질 수 있고 이는 가변성 결정과 가지치기에 영향을 미치게 되는데, 현재 제시된 BPFM에는 이러한 바인딩 정보에 대해서 고려하지 않고 있다. 본 논문에서는 비즈니스 프로세스 군에서 식별될 수 있는 가변성들 사이의 의존관계 유형을 분석하고 이러한 가변성 정보를 독립된 의존관계 분석모델로 표현하는 방법을 제시한다. 또한 추출된 모델을 기반으로 하나의 가변성 결정으로부터 영향을 받는 다른 가변성들을 추적하여 선결정 처리 할 수 있는 방법을 제공한다. 본 방법을 이용함으로써 가변성 결정회수를 줄일 수 있고, 또한 잘못된 가변성 결정으로 인한 BPM의 기능 불일치를 해소할 수 있음을 사례연구를 통해 보인다.

• 한국운동역학회지
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• 제32권3호
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• pp.87-93
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• 2022

Objective: The purpose of this research was to investigate the age-related changes in whole-body motor variability during sit-to-stand (STS) task. It has been reported that children perform motor tasks less accurately with greater variability as compared to adults. However, it is still unknown how they utilize the abundant degrees of freedom and accomplish voluntary actions. Uncontrolled manifold (UCM) analysis has been used to partition motor variabilities into two independent variability components, task-relevant variability (V_ORT) and task-irrelevant variability (V_UCM). We investigated what differences exist between children and adults with respect to these two motor variability components in relation to motor development stages. Method: Ten 6-year-old children (height: 116.2 ± 4.3 cm, weight: 23.1 ± 3.9 kg, motor development assessment percentile score: 77.5 ± 18.6%), ten 10-year-old children (height: 138.7 ± 7.2 cm, weight: 35.8 ± 10.3 kg, motor development assessment percentile score: 73.9 ± 12.7%), and ten young adults (age: 23 ± 1.6 year-old, height: 164.3 ± 11.4 cm, weight: 60.8 ± 12.0 kg) participated in this study. Each participant performed STS ten times, and a motion capture system was used to capture the whole-body kinematics. Each segment centers of mass and the whole-body center of mass were calculated, and UCM analysis was used to quantify motor variabilities, V_ORT and V_UCM. One-way ANOVA was used for statistical analysis. Results: We found that children produced more motor variabilities in V_ORT and V_UCM in all three dimensions, anterior-posterior, medial-lateral, and vertical. As age increased, both, V_ORT and V_UCM significantly decreased (p<.05). Conclusion: The greater V_ORT found in children compared to adults indicates that the repeatability over repetitions improves through development, while the greater V_UCM found in children suggests that children better utilize the abundant degrees of freedom during STS compared to adults.

• 대한한의진단학회지
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• 제12권2호
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• pp.96-106
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• 2008

Background and purpose : Health is characterized by variability and a loss variability is associated with aging and disease. Normal healthy respiratory patterns are characterized by breath to breath variability. Cold-Heat score are quantified indices in Korean Medicine. The aim of this study is to analyze relations between 9 respiratory indices (including breath to breath variability) and cold-heat score by questionnaire. Method : Respiratory data were measured during 15 minutes and transferred to text file. We calculated 9 respiratory parameters in use of MATLAB7.1. After then we did correlation analysis of 9 respiratory indices and cold-heat score Results and conclusion : EIratio is showed significant correlation with Cold score and weighted Heat score.

• 한국지반공학회논문집
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• 제33권5호
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• pp.25-35
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• 2017

액상화는 지진에 의해 발생하는 대표적인 피해 중 하나로 이에 대한 가능성을 평가하기 위한 많은 방법들이 개발되었으며, 최근에는 지반이 갖는 불확실성을 합리적으로 고려하기 위한 확률론적 접근방법에 대한 연구가 이루어지고 있다. 본 연구에서는 지반의 물성치가 갖는 공간 변동성을 고려하여 확률론적 해석을 수행하고자 서로 다른 변동특성을 갖는 세 지점의 CPT 데이터를 활용하여 콘관입 저항치에 대한 공간 변동성을 평가하였다. 이후, 각 지점의 공간 변동성을 고려한 콘관입 저항치의 확률장을 생성하였으며, CPT기반 액상화 평가방법을 통하여 액상화에 의해 유발되는 침하량의 확률론적 해석을 수행하였다. 연구결과, 공간변동성이 고려되지 않을 경우 지반의 불확실성을 과대평가할 수 있으며, 기준 허용 침하량에 따라 약 30%까지 큰 확률론적 차이가 발생할 수 있는 것으로 나타났다.

• 대한토목학회논문집
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• 제30권3B호
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• pp.295-303
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• 2010

식생의 변화는 강수, 기온, 유출 등의 수문기상변수들의 변화와 상당히 밀접한 연관성을 가지고 있다. 식생의 변화에 대한 분석은 곧 기후변화의 지역적 영향을 이해하는데 큰 도움이 될 것이다. 따라서 본 연구에서는 우리나라 지역에 대해서 NOAA/AVHRR 정규식생지수(NDVI)의 시공간변화도를 분석하였다. Mann-Kendall 검정을 이용한 연평균 정규식생지수의 추세분석결과는 대상기간(1982년~2006년)동안 대부분의 유역에서 통계적 유의성을 가진 선형적인 추세변화는 없는 것으로 나타났으나, 금강유역에서 통계적 신뢰수준 90%의 하향추세가 있었다. 또한 EOF 분석을 이용한 주성분분석결과 북쪽지역으로 갈수록 표고가 높을수록 식생의 변화도가 큰 것으로 나타났다. 이는 지형변화에 상관성이 높은 연평균 정규식생지수의 공간분포와 달리 위경도 변화에 대응하는 분산분포 변화특성에 기인한 것으로 판단된다. 계절별로는 6월~9월까지의 정규식생지수가 높게 나타났으며, 이 기간 중에서 7월경에 다소 감소하는 경향을 보여주었다. 유역별로는 한강유역의 정규식생지수가 가장 높았으며, 제주도가 가장 낮은 것으로 나타났다.

• 응용통계연구
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• 제23권2호
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• pp.317-323
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• 2010

Measures are very useful tools for comparing the shape variability in statistical shape analysis. For examples, the Procrustes statistic(PS) is isolated measure, and the mean Procrustes statistic(MPS) and the root mean square measure(RMS) are overall measures. But these measures are very subjective, complicated and moreover these measures are not statistical for comparing the shape variability. Therefore we need to study some tests. It is well known that the Hotelling's $T^2$ test is used for testing shape variability of two independent samples. And for testing shape variabilities of several independent samples, instead of the Hotelling's $T^2$ test, one way analysis of variance(ANOVA) can be applied. In fact, this one way ANOVA is based on the balanced samples of equal size which is called as BANOVA. However, If we have unbalanced samples with unequal size, we can not use BANOVA. Therefore we propose the unbalanced analysis of variance(UNBANOVA) for testing shape variabilities of several independent samples of unequal size.

• 한국시뮬레이션학회논문지
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• 제20권2호
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• pp.1-10
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• 2011

본 연구에서는 대기행렬네트워크 성과측정 방법 중의 한 가지로서 널리 이용되는 분해법의 구성요소로 제안된 변동성 함수 의 이론적 근거를 살펴보고 성과척도 측정의 정확도 제고를 위하여 회귀분석을 통한 변동성 함수의 모수추정 개선방안을 제안하고자 한다. 이를 위하여 변동성이 높은 도착과정과 서비스 과정이 포함된 직렬 대기행렬 네트워크에서의 이탈과정의 자동상관계수 함수를 추정하여 분해법에 사용할 수 있는 방안을 알아본다.