• Journal of Sericultural and Entomological Science
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• v.9
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• pp.15-19
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• 1969

Experiments were carried out to make clear the relationships among some morphological characters of four-varieties of mulberry trees. Simple correlation coefficients and particial correlation coefficients were calcultated among the characters, namely branch length, branch diameter, leaf number per branch, leaf area per branch, node number per branch, total branch wt. branch weight except leaves and leaf weight per branch of the mulberry trees. The results obtained are summarized as follows: 1. Variances of the characters and covariances between the each characters are shown in table 1, and simple correlation coefficients among various characters are shown in table 2. It was observed that there were close relationships between yield (leaf weight) and branch length, branch diameter, leaf number per branch, leaf are per branch, node number per branch, total branch weight and branch weight except leaves, respectively. 2. Partial correlation coefficients among some characters are shown in table 3. From this table, it was also observed that leaf yield of mulberry trees and leaf area are more closely related more than leaf yield and the other characters of mulberry trees in four different varieties. From the experimental studies, it was recognized that the four characters, namely branch length, branch diameter, leaf number and leaf area, should be very useful characters in the estimation of mulberry leaf yield as they could be measured. or counted easily before harvest of mulberry leaves, and are affected more in mulberry 1eaf yields than the other characters.

• International Journal of Highway Engineering
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• v.10 no.2
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• pp.183-191
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• 2008

This study evaluated influence of the loading head dimension on characteristics of deformation strength ($S_D$) of asphalt mixtures. Kim test and Wheel tracking (WT) test were conducted to evaluate $S_D$ characteristics with relation to WT results for various mixtures. The $S_D$ values and coefficient of variation of $S_D$ values of r=10mm were smaller than those of r=10.5mm. It was also found that $S_D$ values obtained using r=10mm loading head showed high correlations with rut parameters of WT test. It was indicated that the aggregate size and radius (r) of round cut were statistically significant variables on $S_D$ at = 0.05 level in the analysis of variance. However, in interaction of r and aggregate size showed no significance within $10{\sim}19mm$ aggregate size at the same level. Therefore, it was concluded that the diameter (D) of 40mm and the bottom edge radius (r) of 10mm was suitable dimension of loading head for deformation strength test.

• Journal of Korean Society of Forest Science
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• v.95 no.3
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• pp.250-255
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• 2006

Pinus densiflora is a dominant conifer species in Korea and also distributed in regions of Japan and eastern China. Success in the establishment and productivity of forest tree plantation is largely determined by selection of species and seed source. The provenance tests of Pinus densiflora in Korea are underway. However, the information of the growth performance of Japanese and Chinese provenances are insufficient. Therefore, this study was conducted to evaluate the growth performance of Pinus densiflora Japanese provenances. Data were collected from a provenance trial including established by Korea Forest Research Institude at Chungju in 1970. Six Japanese provenances ($31^{\circ}90^{\prime}{\sim}40^{\circ} 27^{\prime}$ in latitude and $128^{\circ}47^{\prime}{\sim}141^{\circ}80^{\prime}$ in longitude) were included in this trial. Pyeongchang provenance at Kangwon province in Korea was used for reference provenance. At nursery stage, the height and diameter at root collar of six Japanese provenances were smaller than those of Pyeongchang provenance. Among Japanese provenances, Kasahara provenance showed higher growth performance than those of others. The provenance rankings of growth performance were fluctuated until age 11. However, the growth performance of Japanese provenances showed higher than those of reference provenance after age 17. Kirishima-yama provenance showed best growth performance. Simple correlation analysis was conducted to investigate the geographic factors affecting growth performance. The height growth showed negative corelation with latitude of seed origin. Generally, Japanese provenences of Pinus densiflora were well adapted and grown in Chungju. However, it was suggested that further studies on other sites need to generalize the results of this study.

• Korean Journal of Soil Science and Fertilizer
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• v.29 no.2
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• pp.199-206
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• 1996

Vegetation succession and changes in soil chemical properties were investigated in 10 abandoned rice fields in Kyunggi Province in 1995. Annual weeds were dominant at the first year of abandonment, later on Perennial weeds became dominant as the period of abandonment progressed. The number of Salicaceae(willow family) increased rapidly as the abandonment period further progressed. In cultivated fields, soil pH and cation contents are slightly higher in subsurface layer than surface layer. In abandoned fields, however, pH of surface layer was getting higher than subsurface soil layer with the lapse of time. Similar trends were observed in case of exchangeable Ca and Mg contents.

• Journal of the Korean Geotechnical Society
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• v.28 no.2
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• pp.43-55
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• 2012

In this study, the resistance bias factors are calculated to determine the resistance factor of Gravel Compaction Piles which is one of the soft ground improvement methods. In order to calculate resistance bias factors for gravel compaction piles, two ultimate bearing capacities were analyzed. One is the ultimate bearing capacity in 2.54 cm settlement measured using data of the field loading test on 41 piles and the other is the ultimate bearing capacity calculated using the seven equations concerning bulging failure. The results of analysis show that the probability density function of the calculated ultimate bearing capacities has a lognormal distribution. Resistance bias factor and the coefficient of variation for Greenwood equation are 0.91 and 0.38, respectively, and for those of Hughes & Withers are 1.19 and 0.39. The two equations are suitable for calculating resistance factors for LRFD of soil improvement using gravel compaction piles.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.410-411
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• 2015

765kV 송전선로와 선하 건조물은 최하단 도체의 높이 28m를 적용하고 대지저항률은 $100{\Omega}m$, IEEE 변전소 설계지침인 Std-80에 따라 건조물에 접촉하는 사람의 인체저항은 $1000{\Omega}m$, 대지를 딛고 있는 사람의 한쪽 발 접지저항은 직경 8cm의 원판 접지저항을 적용한다. 이렇게 구성된 모델에서 선로중심에서 건조물까지 이격거리 변동에 따라 인체 유도전류를 측정하고자 한다. 본 연구에서는 전기안전 실증시험을 위해 765kV 가공송전선로 직하에 목조 및 샌드위치 판넬 2가지 시험용 가옥을 설치하였다. 전기설비기술기준에 의거하여 선하직하 이격거리가 28m일 때 발생할 수 있는 전자계 특성과 재질에 따른 전자계가 미치는 영향을 비교 분석하고 장기 유도장해 실측 데이터를 확보하고자 그림 1과 같이 구축 설계하였다. 이를 통해 송전선로에 의해 선로중심으로부터 구축된 모의가옥까지 이격거리에 따라 유도되는 전류를 측정하고 그 크기가 인체에 미치는 유도전류 한계치 초과 여부에 대해 검토함으로써 안전성 여부에 대해 측정 및 검토하고자 시험게획을 수립하였다. 또한 선로 고장 시 대지전위상승에 의한 선하 건조물 안정성 검토 및 낙뢰서지 유입에 의한 전기안전 시험 구성을 하였다.

• Journal of the Korean Society for Marine Environment & Energy
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• v.10 no.3
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• pp.173-180
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• 2007

Oscillating wave amplitude in a bottom-mounted OWC chamber designed for wave energy converter is investigated by applying characteristic wave conditions in Korean coastal water. The effects of shape parameters of OWC chamber in a view of wave energy absorbing capability are analyzed. Both experimental and numerical approaches are adopted and their results are compared to optimize the shape parameters which can result in a maximum power production under given wave distribution. The experiment was carried out in a wave flume under 2-D assumption of OWC chamber. The numerical scheme employed a hybrid Green integral equation which adopts the Rankine Green function inside chamber to take account of fluctuating air pressure, while it uses the Kelvin Green function in outer domain. Air duct diameter, chamber width, and submerged depths of front skirt and back wall of chamber changes the magnitude and peak frequency of wave absorption significantly.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.2
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• pp.371-378
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• 2020

Rainfall is one of the most active forces that cause soil erosion. The action of rain on the soil exerts an erosive power caused by the impact of the drops, which fall with variable speed and kinetic energy, depending directly on the diameter of the drop. The objective of this study is to determine algorithms capable of estimating rainfall erosivity for the region of Maceió-AL. For this purpose, erosion rains were collected between 2003 and 2006 using a RD-69 disdrometer, which continuously and automatically measures rainfall distribution in a range of 1 min. The determination of algorithms in the form of power equation to estimate was adjusted with one and two independent variables (amount of rainfall, duration and maximum intensity).

• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.6
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• pp.11-19
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• 2013

An experimental study was conducted to investigate fuel injection characteristics through swirl injectors when the fuel was heated to very high temperature conditions. Three swirl injectors with different orifice diameters and swirler geometries were used to measure the flow coefficient (${\alpha}$) for the injection pressure ranges between 3 and 10 bar and the fuel temperature from 50 to $270^{\circ}C$. The results showed that the variation characteristics of ${\alpha}$ with respect to cavitation number ($K_c$) were highly dependent on both the orifice diameter and the swirler geometry. In addition, the characteristics of ${\alpha}$ variation with respect to AR, the area ratio of the flow through the swirler and the orifice, has revealed that the effect of boiling is retarded but the slope of decreasing ${\alpha}$ after the boiling effect is present tumbles as AR increases.

• Water for future
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• v.27 no.3
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• pp.115-121
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• 1994

Cohesie sediment movement in estuarine systems is strongly affected by the phenomena of aggregation and flocculation. Aggregation is the process where primary particles are clustered together in tightly-packed formations; flocculation is the process where aggregates and single particles are bonded together to form large particle groups of very low specific density. The size, shape and strength of the flocculants control the rate of deposition and the processes of pollutant exchange between suspended sediments and ambient water. In estuarine waters, suspended sediments above the lutocline form the mobile suspension zone while below the lutocline they form the stationary suspension zone. Suspended particles in the mobile zone are generally in a dispersed state and the controlling forces are the Brownian motion and the turbulent flow fluctuations. In the stationary suspension zone, the driving force is the gravity. This paper discusses the settling and particle flocculation characteristics under quiescient flow conditions. Particles are entering the study domain randomly. Particles in the mobile suspension zone are simulated by using the Smoluchowski's model. Flocs created in the mobil suspension zone are moving into the stationary suspension zone where viscosity and drag effects are important. Utilizing the concepts of the maximum Feret's diameter and the Minkowski's sausage logic, the fractal dimension of the flocs within the stationary suspension is estimated and then compared with results obtained by other studies.