• Title/Summary/Keyword: sampling variability

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Simulation for Irrigation Management of Corn in South Texas

  • Ko, Jong-Han;Piccinni, Giovanni
    • KOREAN JOURNAL OF CROP SCIENCE
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    • v.53 no.2
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    • pp.161-170
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    • 2008
  • Interest is growing in applying simulation models for the South Texas conditions, to better assess crop water use and production with different crop management practices. The Environmental Policy Integrated Climate (EPIC) model was used to evaluate its application as a decision support tool for irrigation management of com (Zea mays L.) in South Texas of the U.S. We measured actual crop evapotranspiration (ETc) using a weighing lysimeter, soil moisture using a neutron probe, and grain yield by field sampling. The model was then validated using the measured data. Simulated ETc using the Hargreaves-Samani equation was in agreement with the lysimeter measured ETc. Simulated soil moisture generally matched with the measured soil moisture. The EPIC model simulated the variability in grain yield with different irrigation regimes with $r^2$value of 0.69 and root mean square error of $0.5\;ton\;ha^{-1}$. Simulation results with farm data demonstrate that EPIC can be used as a decision support tool for com under irrigated conditions in South Texas. EPIC appears to be effective in making long term and pre-season decisions for irrigation management of crops, while reference ET and phenologically based crop coefficients can be used for inseason irrigation management.

A study on local facial features using LDP (LDP를 이용한 지역적 얼굴 특징 표현 방법에 관한 연구)

  • Cho, Young Tak;Jung, Woong Kyung;Ahn, Yong Hak;Chae, Ok Sam
    • Convergence Security Journal
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    • v.14 no.5
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    • pp.49-56
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    • 2014
  • In this paper, we proposed a method for representing local facial features based on LDP (Local Directional Pattern). To represent both PFF (Permanent Facial Features) and TFF (Transient Facial Features) effectively, the proposed method configure local facial feature vectors based on overlapped blocks for each facial feature in the forms of various size and shape. There are three advantages - it take advantages of geometric feature based method; it shows robustness about detection error using movement characteristics of each facial feature; and it shows reduced sampling error because maintain spatial information caused by block size variability. Proposed method shows better classification accuracy and reduced amount of calculation than existing methods.

Population genetic structure and genetic variability of the marbled sole Pleuronectes yokohamae on the coast of Gyeongsangnam-do, Korea

  • Lee, So-Jeong;Lee, So-Gwang;Gwak, Woo-Seok
    • Animal cells and systems
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    • v.16 no.6
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    • pp.498-505
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    • 2012
  • This study uses the mitochondrial DNA control region to identify the genetic diversity and population structure of the marbled soles (Pleuronectes yokohamae) that inhabit Jinhae Bay and Yokji Island in the nearby sea and the adjacent waters of Namhae, Hansan Island, and Jaran Bay. Direct sequencing of the PCR products revealed 379 bp sequences with 83 variable nucleotide sites, defining a total of 91 haplotypes. The haplotype diversity was high, ranging from $0.917{\pm}0.031$ to $0.983{\pm}0.008$, and nucleotide diversity ranged from $0.015{\pm}0.008$ to $0.024{\pm}0.012$. In addition, 48 haplotypes (52.7%) were unique. Pairwise $F_{ST}$ values were very low, with the maximum value occurring between PYH (Hansan Island) and PJI (Jinhae Bay) ($F_{ST}$ = 0.011). Therefore, no significant genetic differentiation was evident between any pair of sampling localities.

Probabilistic Finite Element Analysis of Eigenvalue Problem(Buckling Reliability Analysis of Frame Structure) (고유치 문제의 확률 유한요소 해석(Frame 구조물의 좌굴 신뢰성 해석))

  • 양영순;김지호
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 1990.10a
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    • pp.22-27
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    • 1990
  • Since an eigenvalue problem in structural analysis has been recognized as an important process for the assessment of structural strength, it is usually to be carried out the eigenvalue analysis or buckling analysis of structures when the compression behabiour of the member is dorminant. In general, various variables involved in the eigenvalue problem have also shown their variability. So it is natural to apply the probabilistic analysis into such problem. Since the limit state equation for the eigenvalue analysis or buckling reliability analysis is expressed implicitly in terms of random variables involved, the probabilistic finite element method is combined with the conventional reliability method such as MVFOSM and AFOSM for the determination of probability of failure due to buckling. The accuracy of the results obtained by this method is compared with results from the Monte Carlo simulations. Importance sampling method is specially chosen for overcomming the difficulty in a large simulation number needed for appropriate accurate result. From the results of the case study, it is found that the method developed here has shown good performance for the calculation of probability of buckling failure and could be used for checking the safety of the calculation of probability of buckling failure and could be used for checking the safely of frame structure which might be collapsed by either yielding or buckling.

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UNCERTAINTY AND SENSITIVITY STUDIES WITH THE PROBABILISTIC ACCIDENT CONSEQUENCE ASSESSMENT CODE OSCAAR

  • HOMMA TOSHIMITSU;TOMITA KENICHI;HATO SHINJI
    • Nuclear Engineering and Technology
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    • v.37 no.3
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    • pp.245-258
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    • 2005
  • This paper addresses two types of uncertainty: stochastic uncertainty and subjective uncertainty in probabilistic accident consequence assessments. The off-site consequence assessment code OSCAAR has been applied to uncertainty and sensitivity analyses on the individual risks of early fatality and latent cancer fatality in the population outside the plant boundary due to a severe accident. A new stratified meteorological sampling scheme was successfully implemented into the trajectory model for atmospheric dispersion and the statistical variability of the probability distributions of the consequence was examined. A total of 65 uncertain input parameters was considered and 128 runs of OSCAAR with 144 meteorological sequences were performed in the parameter uncertainty analysis. The study provided the range of uncertainty for the expected values of individual risks of early and latent cancer fatality close to the site. In the sensitivity analyses, the correlation/regression measures were useful for identifying those input parameters whose uncertainty makes an important contribution to the overall uncertainty for the consequence. This could provide valuable insights into areas for further research aiming at reducing the uncertainties.

Monitoring Shoreline Changes at the Songdo Beach, Pohang, during 2003-2010, using Google Earth (Google Earth를 활용한 포항 송도해수욕장의 해안선 변화 감시(2003-2010))

  • Choi, Jin Ho;Um, Jung-Sup
    • Journal of Environmental Impact Assessment
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    • v.20 no.3
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    • pp.257-267
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    • 2011
  • This paper examines the spatial and temporal variability in the shoreline boundary caused by artificial structures in Songdo Beach of South Korea. Quickbird Images of 2003, 2005, 2007, and 2010 extracted from Google Earth were used to identify changing trends of shoreline boundary. The most significant changes were observed in area where groins were extensively established, inducing the sand beach much narrower than before in almost 75% of the area($15070.72m^2$ in 2003 to $3877.46m^2$ in 2010). The Google Earth made it possible to identify area-wide patterns of shoreline change subject to many different type of artificial structures, which cannot be acquired by traditional field sampling. Groin heights, lengths and profiles can be modified during maintenance operations if the Google Earth monitoring indicates that the initial layout is not operating properly as a physical barrier to control sediment transport. It is anticipated that this research could be used as a valuable reference to confirm the outputs from past field researches for coastal processes to respond to storms in more visual and quantitative manner.

A Pilot study to estimate the efficacy of foot reflexology on insomnia in cancer patient (암환자의 불면에 대한 발반사요법의 효과 : 예비임상연구)

  • Jung, Hyun jung
    • Journal of Korean Traditional Oncology
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    • v.26 no.1
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    • pp.49-59
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    • 2021
  • Objective: Insomnia is a very common symptom of cancer and has a substantial effect on the patients' quality of life. This study aimed to identify the effects of foot reflexology on insomnia in cancer patients. Methods: The study employed a before-after test design on a single group of 13 cancer patients with insomnia, selected by convenience sampling in Daegu. The foot reflexology treatment comprised 30-min sessions twice a week over four weeks. Pittsburgh Sleep Quality Index (PSQI) and Insomnia Severity Index (ISI) were measured at the baseline, at 2 and 4 weeks, and after 4 weeks post treatment completion. Brief Fatigue Inventory-Korean (BFI-K), Functional Assessment of Cancer Therapy-General (FACT-G), and Heart Rate Variability (HRV) were measured at baseline, post-treatment, and 4 weeks after completing treatments. Results: Thirteen patients (mean age 44.77 ± 6.70 years), with thyroid, breast or cervical cancer, were included in the study. Post-treatment, PSQI (from 12.33 ± 3.17 to 8.54 ± 3.43, p<0.001), ISI (from 20.33 ± 3.88 to 13.38 ± 4.23, p<0.001), FACT-G (from 49.6 ± 13.27 to 61.35 ± 14.45, p<0.001), and BFI (from 6.46 ± 0.91 to 5.00 ± 2.02, p<0.001) scores improved significantly over those at the baseline. Conclusion: Foot reflexology can be a good alternative treatment to improve insomnia, fatigue, and quality of life in cancer patients

Trace Element in the Indian Ocean: Current Research Trends and Future Needs (인도양에서 미량원소 연구 동향 및 향후 연구 방향)

  • Kim, Intae
    • Ocean and Polar Research
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    • v.43 no.4
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    • pp.335-352
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    • 2021
  • Trace elements in the ocean have been known as essential micronutrients for the primary production of phytoplankton and the growth of marine organisms. The GEOTRACES program beginning in the mid-2000 provided a new understanding of the distribution, origin and behavior of trace elements in the ocean, together with the establishment of both clean seawater sampling and trace element analysis techniques. The Indian Ocean, one of the major oceans, is relatively the least explored area, despite playing an important role in global climate variability. Although trace element observations have recently been conducted in the Indian Ocean by Japanese-and Indian scientists, relatively not much study has been done compared to the Atlantic, Pacific and Polar Regions. Recently, together with the launch of R/V Isabu, a 5,000-ton grade large- and comprehensive research vessel, the observations of trace elements has been conducted in the Indian Ocean for the first time in Korea since 2018. In this paper, we introduce the key results of currently conducted GEOTRACES expedition in the Indian Ocean to present future trace element research directions in the Indian Ocean, and also reviewed the preliminary results in the Indian Ocean studies from Korea. In the 2020s, new Indian Ocean GEOTRACES projects are planned around European countries, and it is time for Korea to prepare for the next phase of the trace element study in the Indian Ocean in line with these international trends.

A Bayesian state-space production model for Korean chub mackerel (Scomber japonicus) stock

  • Jung, Yuri;Seo, Young Il;Hyun, Saang-Yoon
    • Fisheries and Aquatic Sciences
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    • v.24 no.4
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    • pp.139-152
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    • 2021
  • The main purpose of this study is to fit catch-per-unit-effort (CPUE) data about Korea chub mackerel (Scomber japonicus) stock with a state-space production (SSP) model, and to provide stock assessment results. We chose a surplus production model for the chub mackerel data, namely annual yield and CPUE. Then we employed a state-space layer for a production model to consider two sources of variability arising from unmodelled factors (process error) and noise in the data (observation error). We implemented the model via script software ADMB-RE because it reduces the computational cost of high-dimensional integration and provides Markov Chain Monte Carlo sampling, which is required for Bayesian approaches. To stabilize the numerical optimization, we considered prior distributions for model parameters. Applying the SSP model to data collected from commercial fisheries from 1999 to 2017, we estimated model parameters and management references, as well as uncertainties for the estimates. We also applied various production models and showed parameter estimates and goodness of fit statistics to compare the model performance. This study presents two significant findings. First, we concluded that the stock has been overexploited in terms of harvest rate from 1999 to 2017. Second, we suggest a SSP model for the smallest goodness of fit statistics among several production models, especially for fitting CPUE data with fluctuations.

Portable Soil pH Sensor Using ISFET Electrode

  • Hong, Youngsin;Chung, Sun-Ok;Park, Jongwon;Hong, Youngki
    • Journal of information and communication convergence engineering
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    • v.20 no.1
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    • pp.49-57
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    • 2022
  • Fertilizers have long been used to increase crop yields; however, farmers are still having difficulties in managing fertilizers for growing crops as well as economic problems. The conventional method of soil sampling and laboratory analysis to determine soil pH is time consuming and costly; therefore, a portable pH sensor is developed to characterize spatial or temporal variability within fields via rapid and dense data acquisition. The portable pH sensor comprises an electrode unit, a portable console, and a USB connector. The soil water content (SWC) and electrical conductivity (EC) affect the electrical resistance of soil. An artificial test soil is performed to evaluate the effect of SWC and EC on soil pH. The test results show that stable pH measurements are achieved at SWCs greater than 20 mL (16.3%). Regardless of the SWC, the electric potential difference (EPD) remains at 2.5 g of NaCl. As the EC increases in the soil samples, the EPD increases.