• Bulletin of the Society of Naval Architects of Korea
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• v.31 no.3
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• pp.64-68
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• 1994

이 글에서는 활주형선의 단면형상 및 장-폭비와 저항특성과의 관계를 실험적으로 살펴보았다. 본 연구는 5단계로 구성된 연구 계획중 졔 1단계 연구로써 수행되었으며 본 연구를 통하여 단면형상 및 장-폭비의 변화에 따른 저항특성, 종방향 경상(trim), 그리고 침하량(sinkage)의 변화에 대한 초기 결론을 내릴 수 있다. 이러한 초기 결과를 가지고 활주형선의 일반적인 특성에 대한 어떤 분명한 결론을 내리기에는 부족하다고 하겠으나 앞으로 남은 연구를 효율적, 성공적으로 이끌어 가기 위한 초석이 된다고 할 수 있겠다.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.34 no.3
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• pp.283-286
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• 1998

For the systematic study on the resistance characteristics of the planing hull, the experimental studies on the correlation between geometrical characteristics of the subject hull forms and their hydrodynamic characteristics are carried out. This study is the first stage to develop the advanced planing hull type fishing boat and involves the followings; -Resistance characteristics for typical four different section types, -Resistance characteristics for different length-beam ratio

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.3
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• pp.243-247
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• 2015

The characteristics of the fluid force reduction of a square prism having a small triangular prism at the upstream side was investigated by measuring of lift and drag on the square prism The experimental parameters were the width ratios (H/B=0.2~0.6) of triangular prisms to the prism width and the gap ratios (G/B=0~3) between the square prism and the triangular prism. The drag reduction rate of the square prism was increased and then decreased with G/B in case of the same H/B, and was increased with H/B in case of the same G/B. The maximum drag reduction rate was represented by 78.5% at H/B=0.6 and G/B=1.5. The lift reduction rate of the square prism was hardly not affected by the width and gaps ratios, the average value was about 52.4%.

• Journal of the Korean Geotechnical Society
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• v.36 no.12
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• pp.69-76
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• 2020

Since the mechanically stabilized earth walls have a form of retaining wall compatible with a narrow section, the geogrid overlaps according to the separation distance between the walls. There is a problem that the overall behavior may occur in the state of being integrated with the stress change due to the interaction of the geogrid. Therefore, a careful approach is required at the design stage, but there are currently no design criteria or guidelines in Korea. This study investigated the optimal reinforcement length ratio according to the retaining wall width to height ratio (width to height ratio, Wb/H) for these back-to-back mechanically stabilized earth walls. Retaining wall width ratio is 1.1H, 1.4H, 1.7H, 2.0H for Case II of the FHWA design standard, and the height is 3.0 m, 5.0 m, 7.0 m, and 10.0 m, which are most commonly applied. Through numerical analysis, the appropriateness of the FHWA design standard and the optimal reinforcement length ratio according to the height of the retaining wall and the width of the retaining wall were proposed.

• Journal of Korean Society of Steel Construction
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• v.17 no.5 s.78
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• pp.561-568
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• 2005

The object of this paper is to determine appropriateness for use of high-strength tensile bar as a tension web member. The gap K-joint of tensile bar types were compared with gap K-joint of square hollow section (SHS) types. For the same width-to-thickness ratio ($2{\gamma}=33.3$ ), tests were performed on four specimens of the SHS type and eight specimens of the tensile bar type. The comparison of capacity with the experimental results showed a capacity of the SHS type joint to be higher than that of the tensile bartype joint for the same brace-to-chord width ratio. Moreover, the capacity of the SHS type joints increased proportionally to the width ratio ${\beta}$), while tensile bar type joints increased as the tension width ratio (${\beta}2$). In failure mode, SHS-type specimens showed local buckling of the compression brace and plastic failure was observed between the tension brace and chord face, and with the tensile bar type specimens there appeared punching shear failure of the chord face at the toe of the connection plate. It is, therefore, concluded that width-to-thickness ratio should be lower than that of the hollow-section type and the relation between tension and compression width ratio should be considered.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 1997.06a
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• pp.99.1-100
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• 1997

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.7
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• pp.900-908
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• 2014

The Characteristics of the flowfields of a square prism having a small vertical plate at the upstream side was investigated by measuring of fluid force on the square prism and by visualization of the flow fields using PIV. The experimental parameters were the width ratios(H/B=0.2~0.6) of vertical plates to the prism width and the gap ratios (G/B=0~3) between the prism and the vertical plate. The drag reduction rate of the square prism was increased with H/B in case of the same G/B, and was increased and then decreased with G/B in case of the same H/B. The lift reduction rate of the square prism was hardly not affected by the width and gaps ratios, the average value was about 48.1%. In case of a square prism having a small vertical plate, the stagnation regions were represented in the upstream and downstream sides of the square prism.

• Journal of the Korean GEO-environmental Society
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• v.4 no.3
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• pp.51-59
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• 2003

Loading tests were carried out for model geocell to study the reinforcing effect by variation of tensile strength, cell height, soil density and embedded depth of geocell. From the result, it could be seen that the ultimate bearing capacity of the geocell system was influenced rather by the connection strength than by the tensile strength of geocell material. Bearing capacity increased with the increase of height to width ratio of geocell for the same relative density, strength and embedded depth. And the bearing capacity ratio(BCR) was higher at low relative density of sand than that of high relative density. The increase of bearing capacity was higher at geocell with high tensile strength than that of low tensile strength. And the influence was clear at higher relative density. Also the BCR was higher at shallow embedded depth of geocell. Without consideration of tensile strength of material, the application of bearing capacity formula suggested by Koerner seems not suitable for the special case with low tensile strength of geocell material.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.7
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• pp.435-443
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• 2017

The Characteristics of the flowfields of a square prism having a small square prism were investigated by measuring of lift and drag on the square prism and visualizing the flowfield using PIV. The experimental parameters were the width ratios(H/B=0.2~0.6) of small square prisms to the prism width and the gap ratios (G/B=0~3) between the prism and the small square prism. The drag reduction rate of the square prism initially increased and then decreased with the G/B ratio for the same H/B ratio, and increased with the H/B ratio for the same G/B ratio. The maximum drag reduction rate of 98.0% was observed at H/B=0.6 and G/B=1.0. The lift reduction rate of the square prism was not affected by the width and gap ratios; the total average value was approximately 66.5%. In case of a square prism having a small square prism, the stagnation regions were represented in the upstream and downstream sides of the square prism.

• Current Research on Agriculture and Life Sciences
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• v.6
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• pp.25-30
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• 1988

Seven rice varieties and $42F_1$ hybrids of $7{\times}7$ diallel cross were used in genetic analysis for grain size, weight and shape. Effects of average heterosis for grain length and shape showed significantly negative values. GCA, SCA and RCA variances were significant for all characters and also additive variance was more important than dominance variance for grain length, width, thickness and weight. GCA effects of BG 2 and Arborio were highly positive for grain size and weight, and those of BG 2 and Nagdongbyeo were highly negative for grain shape. Partial dominance was observed for all characters. The direction of dominance was negative for grain length, width and shape, and ambidirections for grain thickness and weight. The effective gene number was two for grain length and shape. Both narrow and broad sense heritability were high in all characters.