• Journal of the Society of Naval Architects of Korea
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• v.47 no.2
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• pp.113-121
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• 2010

Recently, as container ships become larger and faster, rudder cavitations are more frequently observed near the gap between the horn and rudder plates of the ships to cause serious damages to the rudder surface of the ship. The authors already have suggested through a series of model experiments and numerical computations that employment of an appropriate blocking device for gap flow may retard the gap cavitation. For examples, a cam device installed near the outer edges of the vertical gap or a water-injection device combined with a pair of half-round bars installed inside the gap can considerably reduce the gap cavitation. However, it is also found that effective blocking of the flow through the vertical gap results in growth of the cavitation near the horizontal gap instead. In the present study, effectiveness of the simultaneous blocking of the flow through the horizontal and vertical gaps of a horn type rudder in minimizing the damage by gap cavitation is studied. Additional blocking disks are inserted inside the horizontal gaps on the top and bottom of the pintle block and numerical computations are carried out to confirm the combined effect of the blocking devices.

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 1998.11a
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• pp.293-299
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• 1998

조선업 및 화학공장 등 산업현장의 화재사고 중 용접$\cdot$용단작업시 불티에 의해 주위의 가연성물질을 착화시켜 화재, 폭발 사고를 일으키는 원인이 되고 있다. 이들 불꽃은 수평방향 및 틈새, 배관구멍 또는 마루나 댁의 작은 개구부 등을 통하여 비산되고 상당시간 훈소화재 형태를 유지하다 발화되어 화재의 원인이 되고 있다. 특히, 용단작업시 비산되는 불티는 $1,600^{\circ}C$ 이상의 고온체로서 산소 압력에 따라 다르나 약 11 m(산소압력, 7 kg/$cm^2$)까지 비산되어 이 반경내에 있는 가연물에 착화될 수 있으므로 이에 대한 예방대책이 필요한 작업공정이다. (중략)

• Journal of the Korean Wood Science and Technology
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• v.16 no.4
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• pp.48-53
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• 1988

This study was carried out to investigate the effects of pressing time and spreading amount, moisture content, gap-distance with butt to butt joint and adhesives on bonding strength in manufacturing the laminated wood with Pitch pine (Pinus rigida). The results obtained were as follows: 1) The pressing time of 12 hours, 10 kilogram per square centimeter of pressure and 200 gram per square meter of spreading amount were required to reach over 50 kilogram per square centimeter (block shear strength) in manufacturing the laminated wood by aqueous vinyl urethane adhesive. 2) The bonding strength decreased with the increase of moisture content of wood. The block shear strength, however, showed over 100 kilogram per square centimeter when the strength test was carried out after air-drying the laminated wood in high moisture content (30-70%). 3) Regardless of direction of load, every flexural property decreased with the increase of gap-distance with butt to butt joint. However, little of every flexural property was changed at 0.5 millimeter of joint-gap distance. The flexural property of vertically laminated wood (perpendicular to glue line to load direction: 1) showed more than that of horizontally laminated wood (parallel to glue line to load direction: //). 4) Among five adhesives used at this experiment, the bonding strength of aqueous vinyl urethane adhesive was the highest in dry bond and wet tests.