• Journal of Korea Water Resources Association
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• v.36 no.2
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• pp.273-284
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• 2003

In this paper, the reasons of damages and the case study are review in which bridge pier with debris accumulation, and safety Influence factors by debris around the bridge piers are review. Also experiment Is conducted for the characteristic of flow around piers by different area and angle of debris and the basic characteristics was review for safe design of bridge and embankments. As result of review of several standards of design, hydraulic structure's freeboard is simply decided by discharge, so it needs more detail standards. And as result of experiment, in the case of that water depth is deep and velocity is slow, variation of water depth Is more increase as increasing of debris. Therefore the variation regime of flow characteristics like velocity and water depth by debris is more large in the stream of small or medium size, which streams have large water depth and slow velocity so Froude Number Is expressed as small in the flood. Also when Froude Number is about 0.5, the water elevation is over freeboard in the standard if the debris over 20%. Therefore when hydraulic structure is constructed in the stream of small or medium size, it need to conduct more detail experiments about influence of debris, distribution of velocity and variation of elevation, and than the more safe freeboard will be presented using the experimental results.

• Journal of Korean Port Research
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• v.7 no.1
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• pp.89-114
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• 1993

ICLL 66 is the most widely ratified instrument of the IMO and is, along with the International Convention on Safety of life at Sea (SOLAS), the primary document setting forth internationally agreed ship safety standards. ICLL 66 set freeboard requirement based on experience gained from the first Load Line Convention in 1930 and on contemporary developments in ship design. Reexamination of ICLL 66 is indicated by the proliferation of novel ship designs for which it lacks adequate regulations and by significant advancements in analytical seakeeping and deck wetness prediction techniques now available to the designer. In this paper, the Freeboard Advisory Group reviews these issues against the changing climate of the marine industry and maritime administrations, discusses the state of the art in analytical seakeeping programs, and outlines a series of recommendations for the establishment of a new international load line convention for the next century. The steps needs for an international program at IMO are discussed and a new convention is proposed.

• Journal of Ocean Engineering and Technology
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• v.36 no.6
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• pp.364-379
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• 2022

Coastal communities have been vulnerable to extreme coastal flooding induced by hurricanes and tsunamis. Many studies solely focused on the overland flow hydrodynamic and loading mechanisms on individual inland structures or buildings. Only a few studies have investigated the effects of flooding mitigation measures to protect the coastal communities represented through a complex series of building arrays. This study numerically examined the performance of flood-mitigation measures from tsunami-like wave-induced overland flows. A computational fluid dynamic model was utilized to investigate the performance of mitigation structures such as submerged breakwaters and seawalls in reducing resultant forces on a series of building arrays. This study considered the effects of incident wave heights and four geometrically structural factors: the freeboard, crest width of submerged breakwaters, and the height and location of seawalls. The results showed that prevention structures reduced inundation flow depths, velocities, and maximum forces in the inland environment. The results also indicated that increasing the seawall height or reducing the freeboard of a submerged breakwater significantly reduces the maximum horizontal forces, especially in the first row of buildings. However, installing a low-lying seawall closer to the building rows amplifies the maximum forces compared to the original seawall at the shoreline.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.17 no.3
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• pp.178-187
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• 2005

A reliability analysis model f3r studying the influence of joint distribution of wave heights and periods on wave un-up is presented in this paper. From the definition of failure mode related to wave run-up, a reliability function may be formulated which can be considered uncertainties of water level. In particular, the reliability analysis model can be directly taken into account statistical properties and distributions of wave periods by considering wave period in the reliability function to be a random variable. Also, variations of wave height distribution conditioned to mean wave periods can be taken into account correctly. By comparison of results of additional reliability analysis using extreme distributions with those resulted from joint distribution of wave height and periods, it is found that probabilities of failure evaluated by the latter is larger than those by the former. Although the freeboard of sloped-breakwater structures can be determined by extreme distribution based on the long-term measurements, it may be necessary to investigate additionally into wave run-up by using the present reliability analysis model formulated to consider joint distribution of a single storm event. In addition, it may be found that the effect of spectral bandwidth parameter on reliability index may be little, but the effect of wave height distribution conditioned to mean wave periods is straightforward. Therefore, it may be confirmed that effects of wave periods on the probability of failure of wave run-up may be taken into account through the conditional distribution of wave heights. Finally, the probabilities of failure with respect to freeboard of sloped-breakwater structures can be estimated by which the rational determination of crest level of sloped-breakwater structures may be possible.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.18 no.1
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• pp.17-23
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• 1982

The corrosion loss of the shell plates and the bulkead plates of the oil tankers, nationalities of which belong to korea are determined and analyzed. The thickness of the plates are determined by use of the ultrasonic thickness meters at the check points set along the fore and aft line and the perpendicular to it. Difference between the original thickness and the determined one are given as the corrosion loss at the present age. 1. On the shell plates (1) The total mean of the corrosion loss shows the greatest value on the load water line in every age classes of the vessels. (2) The total mean of the corrosion loss on the fore and aft line shows little difference, even though it is slightly greater at the fore part, in every age classes of the vessels. (3) The corrosion loss along the perpendicular grows greater in the order of upper bilge line, light water line, freeboard line and load water line at 16 ages of the vessels, and the loss changes in the order of light water line, upper bilge line, freeboard line and load water line at 20 ages of the vessels. (4) The total mean of the corrosion loss along the light water line and upper and lower water line shows the greatest value on the fore part. That along the freeboard line and the load water line shows the greatest value on the midship part and on the after part, respectively. 2. On the bulkhead plates (1) The total mean of the corrosion loss shows the greatest value on the top part at the every age classes of the vessels. (2)The corrosion loss along the perpendicular grows greater in the order of the lower, center and upper part at every age classes of the vessels. (3) The total mean of the corrosion loss at the top part grows greater in the order of the transverse bulkhead of the side oil tank, that of center oil tank, longitudinal bulkhead of center oil tank, and transverse bulkhead of side water tank at the 20 ages of the vessels.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1998.05a
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• pp.173-176
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• 1998

FCC (Fluid Catalystic Cracking) 장치는 중질유의 원유와 잔사유로부터 가솔린과 heating oil. 디젤연료 제조 등에 사용되고 있다. 이 장치는 50년 동안 fine-powder 유동화에 중요하게 응용되고 있으며, 현재 세계적으로 약 350여 개의 장치가 조업되고 있다. FCC 장치에서 미세한 분해촉매는 촉매에 의한 중질유의 분해가 일어나는 상승관 (riser)과 촉매의 재생이 일어나는 재생반응기(regenerator) 사이에서 높은 속도로 순환되고 있다. (중략)

• Journal of Ocean Engineering and Technology
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• v.29 no.1
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• pp.62-69
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• 2015

Coastlines are protected by breakwater structures against the erosion of sand or other materials along beaches due to wave action. This research examined the use of physical modeling to determine the effects of the tetrapod size and vertical walls of a rubble mound on the volume of wave overtopping under irregular wave conditions in coastal areas in Busan Yacht Harbor. In this analysis model, the structures were studied using irregular waves and the JONSWAP wave energy spectrum. To understand the effects of the tetrapod size and heights of the vertical wall, the study considered vertical walls of 0, 1.78, 6.83, and 9.33 cm with armor double layered material tetrapods of 8, 12, 16, and 20 tons. An extensive number of experiments covering a relatively large range of variables enabled a comprehensive discussion. First, in the presence of a short vertical wall, the water level played a key role in the overtopping discharge. In such circumstances, the values of the wave overtopping discharge decreased with increasing freeboard size. In the presence of a tall freeboard and middle, the value of the wave overtopping discharge was equally influenced by the vertical wall factor. Moreover, the tetrapod size decreased by an increase in the vertical wall factor, and relationship between them resulted in a short wall height. From an engineering point of view, considering a small water level may allow the choice of a shorter vertical wall, which would ultimately provide a more economical design.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.47 no.3
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• pp.241-247
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• 2011

Marine casualties of vessel are said to be in most case caused by human error, but it would be valid for the assumption that the ship is built with high quality and then should be acceptable to the safety standards. It means that the inherent characteristics of a ship should be the first consideration on the safety of ship. Therefore it is basically necessary for navigator to grasp the inherent stability of his ship and ensure that the ship complies with the minimum statutory standards of stability. This study is to realize the stability of the Korean offshore large purseiner varying with loading conditions by the inclining data and some calculations. The author compared the stability of the ship with IMO criteria and domestic rule, and proposed some improvement for the safety of the ship. The results are summarized as follows ; The values of GM of the ship according to the loading condition in navigation satisfy both of the IMO criteria and the domestic rule, but in case of the area under the GZ curves between the heel angles of $30^{\circ}$ and $40^{\circ}$, and the heel angle occuring the maximum righting lever not satisfy the IMO rule at the fishing ground departure and arrival conditions in the haul in net situation. The initial metacentric height of the ship is very large, but the range of stability and the occurring angle of the maximum GZ are very small, so even small inclining can bring about the beam end. The best method of improvement for that is to increase the freeboard of the model among the variables.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.3
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• pp.451-461
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• 2016

The objective of this study is to illustrate the methods and procedures for estimating the failure probability of small fill dams subjected to earthquake events and to estimate the seismic failure probability of the Korean disaster risk fill dams where geotechnical information is not available. In this study, first of all, seismic failure probabilities of 7 disaster risk small fill dams, where geotechnical information is available, were evaluated using event tree analysis. Also, the methods and procedures for evaluating probabilities are illustrated. The relationship between dam height and freeboard for 84 disaster risk small dams, for which the safety diagnosis reports are available, was examined. This relationship was associated with the failure computation equation contained in the toolbox of US Army corps of engineers. From this association, the dam height-freeborard critical curve, which represents 'zero' failure probability, was derived. The seismic failure probability of the Korean disaster risk fill dams was estimated using the critical curve and the failure probabilities computed for 7 small dams.

• Journal of Korea Water Resources Association
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• v.51 no.4
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• pp.371-381
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• 2018

Domestic agricultural reservoir dam facilities are difficult to manage water resources because of the in summer rainfall increase due to aging and climate change, it is expected that the dam risk will be large due to the overflow. In this study, author selected study basin in order to evaluate hydrological safety of agricultural reservoir dam facilities. And calculated the probable rainfall, Present PMP, Future PMP considering climate change. Also, author carried quantitative analysis out for increasing rainfall due to climate change, analyze freeboard assessment of agricultural reservoir by calculate flood discharge, reservoir flood routing according to rainfall scenarios. As a result of evaluate hydrological safety of agricultural reservoir dam facilities using Future PMP considering climate change, Gosam, Kumkwang, Miho, Cheongcheon reservoir had the Highest Water Level over the design flood level, it is analyzed that it would be vulnerable to overflow risk.