• Journal of the Society of Naval Architects of Korea
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• v.57 no.4
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• pp.213-220
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• 2020

In the present paper, implosion responses of two adjacent cylindrical tubes under external hydrostatic pressure were experimentally investigated. The cylinder models were fabricated of aluminium alloy 6061-T6 commercial tubes. In the experiment, a pair of two-cylinders were placed inside of a support frame in a medium-size pressure chamber, whose design pressure was 6.0MPa. The distance between the two-cylinders was 30 millimeter measured from outer shell at the mid-length. The implosion tests were performed with water and compressed nitrogen gas as the pressurizing media. The ambient static pressure of the chamber and local dynamic pressure near the two-imploded models were measured simultaneously. It was found that the energy released during an implosion from the first, weaker cylinder triggered the instability of the second, stronger cylinders. In other words, the resulting shock wave of the first implosive impact from the weaker cylinder could cause the premature failure of the neighboring stronger cylinders. The non-contact implosion phenomena from the two-cylindrical tube were clearly observed.

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 1993.07a
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• pp.86-89
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• 1993

본인은 1992년 12월 7일 부터 1993년 3월 31일 까지 일본 성 산하 항만기술연구소에서 신형방파제의 실험에 참여할 기회를 가졌으며, 이 기간동안 일본의 북단 북해도(Hokkaido)에서 남단 Okinawa 까지 항만시설, 특히 신형방파제의 건설현장과 설치운영 현장에 초점을 두고 살펴보았다. 신형방파제에 관한 실험은 항만기술연구소 수공부 내파연구실(구 방파제연구실)에서 실시하였는데 이 연구실은 30년 가까이 방파제에 관한 연구와 실험을 수행한 곳으로 Goda, Tanimoto 등이 실장으로 있었던 세계적인 수준의 연구실이라 할 수 있다. (중략)

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.89-89
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• 2015

항만 및 어항 구조물을 구성하는 다양한 해안구조물은 파랑의 천수효과, 굴절, 회절, 부분반사, 해저마찰, 쇄파의 영향 등을 고려해야하며 파고 및 파향 등의 해양특성의 검토가 반드시 이루어져야 한다. 실제의 해양파가 방향스펙트럼을 갖는 다방향 불규칙파라는 것은 잘 알려져 있으며, 기존의 해안구조물의 내파설계 또는 천해역의 파랑변형 검토에 있어서도 실제 해양파에 보다 가까운 다방향 불규칙파를 이용한 수리모형실험에 의해 파랑현상을 정도 높게 재현하는 것은 매우 중요하다. 본 연구에서는 실제 해양파를 정도 높게 재현할 수 있는 다방향 불규칙파 조파장치를 사용하여 구조물 전면해역에서의 파랑스펙트럼을 재현하고, 심해에서 발달된 파랑이 천해로 진행될 때 지형에 의해 발생되는 천수변형과 구조물 주위에서 나타나는 파랑변형의 현상을 고려하여 항내로 유입되는 파랑의 분포 특성을 검토하였다. 특히, 다방향 불규칙파로 인한 항내 파고분포 특성을 검토하기 위하여 동일 파랑에 대한 규칙파 및 불규칙파랑을 조파하여 그 결과를 상호 비교하였다. 아울러, 정온수역유지를 위한 월파현상을 수리적으로 재현할 수 있는 3차원 수리모형실험 수행하여 월파현상이 항내정온도에 미치는 영향을 고찰, 해석하여 항만 시설물 계획시 안정한 정박 및 이용에 대한 가능한 정온유지여부를 검토하였다.

• The Korean Journal of Malacology
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• v.28 no.1
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• pp.1-6
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• 2012

We studied that the effect of stocking density on growth and survival rate of the scallop, Chlamys farreri (initial shell height 32.97 mm and total weight 5.63 g) from June 2002 to October 2003 in the west coast of Korea. C. farreri is usually the west coast of Korea and northern China in the natural habitat of the coastal species. Range of surface water temperature in the study area was $4.3^{\circ}C$ to $25.3^{\circ}C$, salinity 29.2 psu to 32.1 psu, dissolved oxygen 5.32 mg/L to 7.51 mg/L and pH was 7.84 to 8.12, respectively. The stocking densities were 20, 30, 40 and 50 individuals per a compartment of suspension cage in culture beginning. After 16 months from initiation, ranges of shell height and mean total weight were from 64.35 mm to 76.23 mm and from 41.53 g to 64.85 g. The survival rate was from 82% to 100%. The growth rate of the scallop was negatively correlated with the stocking density. The growth of the shell height and total weight were decreased with decreasing of water temperature. Most of mortality of scallop occurred during March to April and September to October. Survival rate in the stocking density was decreased by density increase and was highest in 20 individual a compartment.

• The Korean Journal of Malacology
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• v.28 no.2
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• pp.117-123
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• 2012

We studied that the effects of mesh size and material of cages on the growth of C. farreri (initial shell height 38.6 mm and shell total weight 7.2 g) held in suspension cage from September 2005 to October 2006. The experiment was performed with two mesh sizes (1 cm and 2 cm) and two materials (net and plastic) of cages in same densities. After 13 months from culture beginning, ranges of shell height and total weight were from 69.7 mm to 73.9 mm and from 36.1 g to 47.0 g, respectively. The survival rate was from 93% to 100%, respectively. The growth rates of the scallop were positively correlated with the mesh size. In the growth rate according to culture material, the growth of scallop in the plastic cage was faster than that in the net cage from September 2005 to June 2006, but the growth in the plastic was slower than that in the net cage for obstruction by attaching organisms from June to October 2006.