• 한국토양비료학회지
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• 제47권4호
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• pp.225-234
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• 2014

This study was carried out to investigate the sustainable agriculture of no-tillage technique including recycling of the ridge and the furrow of a field for following crops in Korea. No-tillage systems affect soil physical properties such as three phase (solid, liquid, and air phase) and distribution of soil granular. Solid ratio of subsoil in 3-year of no-tillage (NT) treatment was remarkably lower than that in conventional (CT, 2-year of no-tillage + 1-year of tillage) treatment, while air ratio of subsoil in NT remarkably increased. Bulk density of subsoil in NT remarkably decreased. Porosity of subsoil in NT remarkably increased. Deviation of air phase, bulk density, and porosity of top soil and subsoil in NT remarkably decreased in NT compared with CT. Solid phase ratio and liquid phase ratio in NT and CT had positive (+) correlation. Solid phase ratio and air phase ratio in NT and CT had negative (-) correlation, also liquid phase ratio and air ratio had negative (-) correlation. Bulk density and liquid ratio in soil had positive (+) correlation at top soil and subsoil in NT. Bulk density and air ratio in soil had negative (-) correlation in NT and CT. Porosity and liquid phase ratio had negative (-) correlation, r =1), the significant value was lower in NT than in CT. Porosity and air phase ratio had positive (+) correlation (r =1).

• 원예과학기술지
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• 제28권6호
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• pp.1066-1071
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• 2010

자기보고식 설문평가와 컴퓨터 기반 심박변이도(Heart rate variability, HRV) 분석평가를 통해 원예치료가 우울증 환자의 정서개선에 미치는 효과를 알아보았다. 자기보고식 설문 평가는 정신적 스트레스, 신체적 스트레스, 불안, 우울 등 4가지 평가도구를 사용하였다. HRV 분석평가는 standard deviation of the N-N intervals(SDNN), square root of mean squared difference of successive N-N intervals(RMSSD), total power(TP), low-frequency/high-frequency ratio(LF/HF ratio)의 4개 분석지표를 이용하였다. 동일한 병원 소속 우울증 환자 30명을 대상으로 실험을 수행하였다. 이 가운데 실험군 15명을 대상으로 주 1회씩 12회 원예치료 프로그램을 실시하였고, 대조군에는 실시하지 않았다. 그 결과, 원예치료를 실시 한 실험군의 경우 자기보고식 설문평가는 물론 HRV 분석평가에서도 원예치료 후 우울 정서 개선 효과가 확인되었다. 특히 자기보고식 평가에서는 정신적 스트레스, 불안, 우울 척도에서 통계적으로도 유의한 효과가 나타났으며($p$<0.001), HRV 분석평가의 경우 TP 지표에서 통계적 유의성이 확인되었다($p$<0.05). SDNN, RMSSD, LF/HF ratio 지표 역시 눈에 띄게 호전되었으나 통계적 유의성은 없었다. 비록 HRV의 모든 분석지표들이 통계적 유의성을 나타내지는 않았지만, 이 연구를 통해 HRV 측정으로 원예치료 효과를 객관화된 수치로 제시할 수 있는 가능성을 확인하였다. 또한 주관적 평가와 객관적 평가를 도입한 본 실험 결과 원예치료가 우울증 환자의 심리적, 신체적 재활에 효과적임이 입증되었다.

• 한국농공학회지
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• 제31권4호
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• pp.96-110
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• 1989

To suggest the fundamental data for the estimation of crop evaportranspiration by the ca- lculated coefficients for estimating the radiation suitable to the different regions of korea in application of Penman equcation, the daily data such as sc(skycover), n(actual sunshine hours), N(possible sunshine hours), Rs(horizontal solar radiation) and Ra(extraterrestial solar radiation) for 10 years (from 1977 to 1986) collected from 19 meteorological stations were analysed. The results are summarized as follows : 1. The coefficients a, b and c for estimating the radiation taken by the regression method with the daily and monthly mean data of the skycover and the ratio of Rs to Ra were shown as a=0.619, b= -0.0202, c= -0.0023 and a=0.64, b=0.0377 c=0.0001 in ave- rage respectively. 2. The coefficients a and b for estimating the radiation analysed by the regression and arithmetic method from the daily ratio of sunshine hours and Rs to Ra were shown as a= 0.157, b= 0.529, and a=0.119, b= 0.726 in average, respectively. 3. The coefficients a and b for estimating the radiation calculated by the regression me- thod based on the monthly ratio of sunshine hours and radiation were shown as a=0. 319 and b= 0.557 in average. 4. The values of a and b for estimating the radiation taken from the relationship between the daily ratio of sunshine hours and radiation showed high significance level. 5. The standard deviation and the coefficient of variance between the radiation calculated from the coefficients by the regression and arithmetic method with the daily data and the actual radiation were analysed and compared to the results by the coefficients of the modified Penman method (a=0.18, b=0.55) and by those of the F.A.O inodified Penman method(a=0.25, b=0.5). The standard deviation and the coefficient of varia- nce by the regression method in this study showed the lowest value. 6. From the above results, it is suggested that regression method using the coefficients taken from the relationship between the ratio of sunshine hours and the ratio of radia- tion based on the daily data has the highest accuracy in estimating the radiation. 7. The average reference crop evapotranspiration estimating by the modified Penman me- thod using the coefficients a and b derived by the regression method from the daily meterological data was closer to the actual evapotsranspiration of grass measured in Suwon area than the estimated evapotranspiration by the modified Penman method and the F.A.O modified Penman method.

• 천문학회지
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• 제29권spc1호
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• pp.313-314
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• 1996

Assuming that the solar activity and the solar cycle phenomena may be manifestations of global torsional MHD oscillations, we compute the Alfven wave travel times along the field lines in the five models of magnetic field described in the following text. For all these models, we compute standard deviation and it's ratio to mean Alfvenic wave travel times. The last two models yield the smallest relative bandwidth for the frequencies of the MHD oscillations. However, the last model is the only admissible one which can sustain global Alfvenic oscillations with well defined frequency for the fundamental mode

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2006년 창립20주년기념 정기학술대회 및 국제워크샵
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• pp.127-134
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• 2006

Based on a weakly non-Gaussian theory the occurrence probability of freak waves is formulated in terms of the number of waves in a time series and the surface elevation kurtosis. Finite kurtosis gives rise to a significant enhancement of freak wave generation in comparison with the linear narrow banded wave theory. For fixed number of waves, the estimated amplification ratio of freak wave occurrence due to the deviation from the Gaussian theory is 50% - 300%. The results of the theory are compared with laboratory and field data.

• Communications for Statistical Applications and Methods
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• 제2권2호
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• pp.288-295
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• 1995

In this paper a hypotheses test procedure based on the least absolute deviation estimators for the unknown parameters in nonlinear regression models is investigated. The asymptotic distribution of the proposed likelihood ratio test statistic are established voth under the null hypotheses and a sequence of local alternative hypotheses. The asymptotic relative efficiency of the proposed test with classical test based on the least squares estimator is also discussed.

• 오토저널
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• 제9권1호
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• pp.69-76
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• 1987

This paper deals with the theoretical prediction and cyclic variation of combustion characteristics in a four stroke, single0cylinder, diesel engine. Theoretical calculations employed a simple empirical model of analysis of energy equation for the thermodynamic system of engine cylinder. The cyclic variation of combustion characteristics is investigated, in term of frequency distribution and standard deviation of peak characteristics, as obtained by combustion analyzer system. The results of theoretical prediction are shown to be in close agreement with the experimental data. The effect of fuel injection timing, engine speed, cooling water temperature, and the compression ratio on the cyclic variations of combustion characteristics were discussed.

• 대한한방내과학회지
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• 제28권4호
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• pp.769-778
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• 2007

Background & Object : Postprandial epigastric fullness is one of common symptoms in functional dyspepsia, but its pathophysiological mechanism has still been unknown. In this study, its association between postprandial epigastric fullness and pyloric valve disturbance was studied through analysis of bowel sounds and electrogastrography. Methods : Bowel sounds and electrogastrography were recorded together for fasting 15 min and postprandial 40 min. Parameters of bowel soundincluding motility index, sound to sound interval, standard deviation of sound to sound interval, sounds per minute, % of bowel sound, sound length, intensity, dominant frequency of sounds, and postprandial / fasting ratio of dominant frequency of sounds were analyzed with a specialized program. By electrogastrography, regularity of slow waves and power ratio were obtained. Results : Significances of bowel sounds appeared in motility index (p=0.046), dominant frequency of fasting (p=0.048), postprandial (p=0.003), and the ratio of postprandial/fasting (p=0.000); those of EGG parameters were shown in postprandial regularity of slow waves (p=0.006) and power ratio (p=0.011). Conclusion : Pyloric valve disturbance was a cause of postprandial epigastric fullness in patients with functional dyspepsia. Analysis of bowel sound might be useful in diagnosing its existence.

• 소성∙가공
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• 제14권7호
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• pp.601-606
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• 2005

A hole expansion process is an important process in producing a hub-hole in a wheel disc of a vehicle. In this process, the main parameter is the formability of a material that is expressed as the hole expansion ratio. In the process, a crack is occurred in the upper edge of a hole as the hole is expanded. Since prediction of the forming limit by hole expansion experiment needs tremendous time and effort, an appropriate fracture criterion has to be developed for finite element analysis to define forming limit of the material. In this paper, the hole expansion process of a hub-hole is studied by finite element analysis with ABAQUS/standard considering several ductile fracture criteria. The fracture mode and hole expansion ratio are compared with respect to the various fracture criteria. These criteria do not predict its fracture mode or hole expansion ratio adequately and show deviation from experimental results of hole expansion. A modified ductile fracture criterion is newly proposed to consider the deformation characteristics of a material accurately in a hole expansion process. A fracture propagation analysis at the hub-hole edge is also performed for high accuracy of prediction using the new fracture criterion proposed.

• 대기
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• 제26권3호
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• pp.461-471
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• 2016

A quality check algorithm for the Weather Information Service Engine pulsed Doppler wind lidar is developed from a view point of spatial and temporal consistencies of observed wind speed. Threshold values for quality check are determined by statistical analysis on the standard deviation of 3-component of wind speed obtained by a wind lidar, and the vertical gradient of horizontal wind speed obtained by a radiosonde system. The algorithm includes carrier-to-noise ratio (CNR) check, data availability check, and vertical gradient of horizontal wind speed check. That is, data sets whose CNR is less than -29 dB, data availability is less than 90%, or vertical gradient of horizontal wind speed is less than $-0.028s^{-1}$ or larger than $0.032s^{-1}$ are classified as 'doubtful', and flagged. The developed quality check algorithm is applied to data obtained at Bucheon station for the period from 1 to 30 September 2015. It is found that the number of 'doubtful' data shows maxima around 2000 m high, but the ratio of 'doubtful' to height-total data increases with increasing height due to atmospheric boundary height, cloud, or rainfall, etc. It is also found that the quality check by data availability is more effective than those by carrier to noise ratio or vertical gradient of horizontal wind speed to remove an erroneous noise data.