• Journal of Biosystems Engineering
• /
• v.40 no.2
• /
• pp.115-123
• /
• 2015

Purpose: A sampling scheme may significantly affect the accuracy of a sensor. This study was conducted to investigate the effects of sampling point locations on optical reflectance measurements of Chinese cabbage and kale plant leaves. Methods: Variability and similarity of multiple measurements for different parts of the leaves were compared. Results: The results indicate that the variability between the average and individual reflectance spectra was smaller for the blade part than for the vein part. Furthermore, the reflectance for the blade part over the upper leaf area was greater and more stable than those for the other parts for both the cabbage and kale leaf samples. Conclusions: The results provide guidelines for optical reflectance measurements of Chinese cabbage and kale plants. The effects of the number of sampling points, the number of leaves, and the relationships between optical reflectance and leaf components remain to be investigated in the future.

• Korean Journal of Agricultural Science
• /
• v.47 no.3
• /
• pp.615-624
• /
• 2020

An effective sampling method is necessary to monitor potato tuber moths (Phthorimaea operculella) because they are the biggest concern in potato-cultivating areas. In this study, a sequential sampling method was developed based on the results of field surveys of potato tuber moths in South Korea. Potato tuber moths were collected in fields cultivating potatoes at six sites, and their spatial distribution was investigated using the Taylor power law. The optimal sampling size and cumulative number of potato tuber moths in traps to stop sampling were determined based on the spatial distribution pattern and mean density of the collected potato tuber moths. Finally, the developed sampling method was applied to propose a control action, and its sampling efficiency was compared with that of the traditional sampling method using a binomial distribution. The potato tuber moths tended to aggregate; the optimal number was approximately 5 - 16 traps for sampling, and the number varied with the mean density of potato tuber moths according to the sampling sites. In addition, one, two, and three sites might require the following actions: Continued sampling, control, and no control, respectively. Sampling with the binomial distribution showed the minimum sample size was 12 when considering the economic threshold level. Here, we propose an effective sampling method that can be applied for future monitoring and field surveys of potato tuber moths in South Korea.

• Communications for Statistical Applications and Methods
• /
• v.22 no.5
• /
• pp.435-443
• /
• 2015

Two phase sampling design is useful to increase estimation efficiency using deep stratification, improved non-response adjustment and reduced coverage bias. The same sampling units are commonly used for the first and the second phases in complex two-phase sampling design. In this paper we consider a sampling scheme where the first phase sampling units are clusters and the second phase sampling units are list samples. Using selected clusters in first phase requires that we list up elements in the selected clusters from the first phase and then use the list as a secondary sampling frame for the second phase sampling design. Then we select second phase samples from the listed sampling frame. We suggest an estimator based on the complex two-phase sampling design with different sampling units of each phase. Also the estimated variances of the estimator obtained by using classic and replication variance methods are considered and compared using simulation studies. For real data analysis, 2010 Korea Farm Household Economy Survey (KFHES) and 2011 Korea Agriculture Survey (KAS) are used.

• Korean Journal of Agricultural Science
• /
• v.41 no.3
• /
• pp.169-175
• /
• 2014

Objective of this study was to investigate effects of pre-processing method and number of sampling leaves on stability of the reflectance measurement for Chinese cabbage and kale leaves. Chinese cabbage and kale were transplanted and cultivated in a plant factory. Leaf samples of the kale and cabbage were collected at 4 weeks after transplanting of the seedlings. Spectra data were collected with an UV/VIS/NIR spectrometer in the wavelength region from 190 to 1130 nm. All leaves (mature and young leaves) were measured on 9 and 12 points in the blade part in the upper area for kale and cabbage leaves, respectively. To reduce the spectral noise, the raw spectral data were preprocessed by different methods: i) moving average, ii) Savitzky-Golay filter, iii) local regression using weighted linear least squares and a $1^{st}$ degree polynomial model (lowess), iv) local regression using weighted linear least squares and a $2^{nd}$ degree polynomial model (loess), v) a robust version of 'lowess', vi) a robust version of 'loess', with 7, 11, 15 smoothing points. Effects of number of sampling leaves were investigated by reflectance difference (RD) and cross-correlation (CC) methods. Results indicated that the contribution of the spectral data collected at 4 sampling leaves were good for both of the crops for reflectance measurement that does not change stability of measurement much. Furthermore, moving average method with 11 smoothing points was believed to provide reliable pre-processed data for further analysis.

• Journal of Animal Science and Technology
• /
• v.46 no.5
• /
• pp.719-728
• /
• 2004

The aims of this study were to estimate genetic parameters for carcass traits on Hanwoo(Korean Native Cattle) and to compare two different statistical algorithms for estimating genetic parameters. Data obtained from 1526 steers at Hanwoo Improvement Center and Hanwoo Improvement Complex Area from 1996 to 2001 were used for the analyses. The carcass traits considered in these studies were carcass weight, dressing percent, eye muscle area, backfat thickness, and marbling score. Estimated genetic parameters using EM-REML algorithm were compared to those by Bayesian inference via Gibbs Sampling to find out statistical properties. The estimated heritabilities of carcass traits by REML method were 0.28, 0.25, 0.35, 0.39 and 0.51, respectively and those by Gibbs Sampling method were 0.29, 0.25, 0.40, 0.42 and 0.54, respectively. This estimates were not significantly different, even though the estimated heritabilities by Gibbs Sampling method were higher than ones by REML method. Since the estimated statistics by REML method and Gibbs Sampling method were not significantly different in this study, it is inferred that both mothods could be efficiently applied for the analysis of carcass traits of cattle. However, further studies are demanded to define an optimal statistical method for handling large scale performance data.

• Asian-Australasian Journal of Animal Sciences
• /
• v.4 no.1
• /
• pp.79-83
• /
• 1991

Diurnal variation in faecal chromic oxide levels was estimated from 4 hourly faecal sampling of 56 wethers allotted to one of six different feeding patterns. Sampling occurred on days 6 and 7 (Period 1) after a controlled release device was administered, and was repeated on days 14 and 15 (Period 2) following re-randomisation of the wethers to the feeding patterns. Increasing the frequency of feeding tended to be associated with higher faecal chromic oxide levels (p < 0.05), particularly in wethers fed thrice daily at 8 hour intervals. There was no interaction between feeding pattern and period, sampling day or time within-day. There were significant period x time within-day (p < 0.05) and day x time within-day (p < 0.001) interactions, indicating that variation in faecal chromic oxide between sample times was not consistent. This implies that sampling at any time of day is unlikely to result in a biased estimate of pasture intake, providing sufficient samples are collected. Significant period (p < 0.001) and period x day (p < 0.01) effects were associated with slow faecal chromic oxide equilibration in period 1. Equilibration did not occur until after day 7, indicating a need for caution when commencing sampling.

• Asian-Australasian Journal of Animal Sciences
• /
• v.8 no.2
• /
• pp.163-169
• /
• 1995

This study was conducted 1) to compare the nutrient content and mineral composition of the Philoppine indigenous sheep and goats diets when grazed in common pasture during rainy season, 2) to determine the influence of sampling methods on nutrient content and mineral composition of upland (UP) and lowland (LP) native pastures, and 3) to compare these two pasture types in terms of nutrient and mineral composition. Experiment 1 used sis esophageally fistulated animals, three each for sheep and goats. Weekly extrusa collection was done for a period of three months. Experiment 2 was conducted in UP and LP; these were sampled thrice by three methods, plucking, clipping and use of three esophageally fistulated sheep. Results of Experiment 1 indicated that the diets of sheep were greater in crude protein(CP; p < 0.01) and ether extract(EE; p < 0.05) but lower in crude fiber (CF) and acid detergent lignin (ADL; p < 0.05) than that of goat diets. All other nutrient fractions including mineral composition were not significantly different from each other. Significant findings of Experiment 2 were: CP content of UP was in the order fistulated > plucked > clipped (p < 0.05); CP content of LP was greater (p <0 .05) in fistulated and plucked samples; and ash content was greater (p < 0.05) in fistulated samples of both pastures. The CP of UP was different (p < 0.05) from each sampling method but the CP of LP and ADL of both pastures were greater (p < 0.05) in clipped samples. Most minerals either macro or microminerals were greater in fistulated samples of both pastures. Pooled data of the two pastures showed that LP had better nutrient characteristics and greater mineral composition. Based from this study, there were few differences between the diets of indigenous sheep and goats when grazed in common pasture. Also, sampling methods influenced the nutrient composition of indigenous sheep diets.

• Journal of Forest and Environmental Science
• /
• v.35 no.3
• /
• pp.205-211
• /
• 2019

The objective of this research was to assess the amount of carbon stock of coarse woody debris (CWD) in Bombo-Lumene Reserve. Data on lying CWD was collected on 35 circular sampling plots using Line Intersect Sampling (LIS) method. A total of 230 samples CWD (${\geq}10cm$ diameter) were inventoried. The mean carbon stocks of CWD was $29.48Mg\;C\;ha^{-1}$, ranging from 4.32 to $73.54Mg\;C\;ha^{-1}$. The CWD carbon stocks displayed a wide range of variation in decay states. The allocation of CWD among the decay class of all the CWD samples reveals that the most important classes were class 1 and class 3 with 323.66 and $321.96Mg\;C\;ha^{-1}$, followed by class 4 with 264.56 and the last one was class 2 with $121.72Mg\;C\;ha^{-1}$. The results suggested that the dead wood component is important in carbon sequestration and should be taken into consideration for quantification of carbon stocks not only in Bombo-Lumene Reserve, but in all forest ecosystems in the Democratic Republic of Congo.

• Korean Journal of Environmental Agriculture
• /
• v.13 no.3
• /
• pp.359-372
• /
• 1994

A simplified closed static chamber method was devised for measurement of methane flux from paddy fields. Compared to automatic methane measuring system(AMMS) this chamber method provides availability with moderate costs of setup and maintenance, while it also provides the time-effectiveness compared to other closed top-type chamber method. It accomodates 30 chambers within 2 hours sampling period with two persons. And it provide a rapid and accurate analysis of methane, 30-40 samples per hour. Modified method for $N_2O$ measurements provides a precise and accurate analysis of nitrous oxide without upgrading additional heating zones for gas sampling(switching) valves.

• Journal of the Korean Statistical Society
• /
• v.2 no.1
• /
• pp.17-23
• /
• 1973

No Abstract, See Full Text