• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.36 no.3
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• pp.195-201
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• 2000

This paper discusses methods for the stable bottom detection and the optimum bottom offset which enable to separate the fish echoes from the bottom echoes with echo integration of demersal fish. In preprocessing of the echo signal, the bottom detection has to be done stably against the fluctuation of echo level and the bottom offset has to be set to a minimum height such that near bottom fish echoes are included Two methods of bottom detection, namely echo level threshold method and maximum echo slope method were compared and analyzed. The echo level method works well if the ideal threshold level was given but it sometimes misses the bottom because of the fluctuation of the echo. Another method to detect the bottom which uses maximum echo slope indicates the simple and stable bottom detection. In addition, the bottom offset has to be set near to the bottom but not to include the bottom echo. Optimum bottom offset should be set a few samples before the detected bottom echo which relates the beginning of pulse shape and acoustic beam pattern to the bottom feature.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2008.11a
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• pp.103-106
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• 2008

Because the physical·chemical properties of bottom ash are inferior, most bottom ash is disused. But the use of bottom ash helps in reducing environmental pollution and solving some bottom ash waste problems. So, we have been investigating about the optimum mixture, hardening mechanism, curing condition and environmental safety of a paste composed of a bottom ash and alkali. optimal mixing proportion of bottom ash solid was cement 5%, water 30%, NaOH 10%. After curing during 28days, bottom ash solid can be achieved compressive strength 15.13MPa. As a result, Compressive strength tests of alkali-activated bottom ash have potential as a replacement of coarse aggregate.

• Journal of the Korea Concrete Institute
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• v.14 no.2
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• pp.223-230
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• 2002

The main intent of this research was to determine the feasibility of utilizing recycling bottom ash as CLSM (controlled low-strength material). CLSM is a cementitious material, commonly a blend of portland cement, fly ash, sand, and water, that is usually flowable and self-leveling at the time of placement. The durability characteristics of mixtures made bottom ash we compared with those of fly ash CLSM in order to evaluate the effectiveness and suitability of bottom ash as material in CLSM. A comprehensive evaluation of the bottom ash in CLSM and mix proportions indicated that the bottom ash are capable of performing as CLSM mixtures. The durability characteristic of CLSM incorporating the bottom ash under various physical and chemical causes of deterioration were investigated. Test results indicated that CLSM using bottom ash has acceptable durability performance. CLSM incorporating with bottom ash were also found to be environmentally safe.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.489-492
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• 2008

This study analyzed the fundamental properties and strength properties of concrete utilizing Bottom Ash as coarse aggregate for concrete. As a result, compared to non-mixture, the slump decreases about 4.5${\sim}$54.2% as the mixing ratio of Bottom Ash increases. However, influence of the air contents is very little. The bleeding shows similar slump characteristics, and the primary stage of bleeding decreases as the mixing ratio of Bottom Ash increases. As the mixing ratio of Bottom Ash increases, the compressive strength decreases. When Bottom Ash is mixed by 40%, compressive strength decreases about 1.1${\sim}$5.3%. Even when Bottom Ash is mixed over 60%, compressive strength decreases sharply and is revealed about 85.2${\sim}$87.7% of non-mixture concrete strength. To utilize Bottom Ash in large quantities, it is thought that the improvement method of strength has to be discussed such as mixing strengthening element.

• Journal of Korean Port Research
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• v.6 no.2
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• pp.43-64
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• 1992

This study discusses the interacting with deep water waves approaching from deep water based on the linear wave theory and steep sloping sea bottom floor by the numerical procedure. The results of particular interest are particle velocity and acceleration in x, y, z direction wave height amplification factor reflection coefficient and dimensionless pressure distribution on the steep sloping bottom with respect to the various incident wave angle. The wave loads relative to various bottom slopes, incident wave angles and wave periods on submerged breakwater and pipe are represented in comparison with mild sloping bottom the wave load parameters on the steep sloping bottom seemed to be influenced by variation of incident wave angle. In general the particle velocities and accelerations in x, y, z directions on the steep sloping bottom represented larger value or about two than those on the mild sloping bottom according to incident wave angle. However, the wave height amplification factors did not show distinct difference, but the slight variation with respect to the various incident angle showed on mild sloping bottom. The reflection coefficient increased with respect to increase of the incident angle on the steep sloping bottom the results also indicate that the very steep sloping beach produces a rather substantial amount of reflection as we expected. No significant variation of wave pressure was shown on the steep sloping bottom but it represented a certain amount of variation on the mild sloping bottom according to the various incident wave angle. The analysis at the OTEC site also showed similar results.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2001.10a
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• pp.154-157
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• 2001

Through this study we investigated the causes of bottom crack. We then redesigned petaloid bottom to prevent bottom crack. We examined the material property variations according to the stretch ratio of PET and analyzed stretches of bottom in blowing processes. We also performed crack test to observe a crack phenomena. The effective stress and maximum principal stress were examined by computer simulation. We concluded that the bottom crack occurs because of not only insufficient strength of material due to the insufficient stretch of PET but also coarse design of petaloid shape. The highest maximum principal stress occurred at valley in petaloid bottom of bottle and this strongly affected the crack in bottom. We redesigned petaloid shape to minimize maximum principal stress, and this result in increasing the crack resistance.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.49 no.3
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• pp.393-403
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• 2016

A steady, strong southward flow was observed in the lower layer beneath the Tsushima Warm Current in the deepest trough of the Korea Strait. Known as the Korea Strait Bottom Cold Water (KSBCW), this bottom current had a mean velocity of 24 cm/s and temperatures below 8–10℃. The direction of the bottom current was highly stable due to the topographic effects of the elongated trough. To determine the path of the southward bottom current, ADCP (Acoustic Doppler Current Profiler) data from 14 stations between 1999 and 2005 were examined. Persistent southward flows with average speeds of 4–10 cm/s were observed at only three places to the north of the strait where the bottom depths were 100–124 m. The collected data suggest a possible course of the southward bottom current along the southeast Korean coast before entering the deep trough of the Strait.

• Steel and Composite Structures
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• v.47 no.2
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• pp.203-216
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• 2023

The composite beam connections often encountered fracture failure in the welded bottom flange joint, and a bottom flange bolted connection has been proposed to increase the deformation ability of the bottom flange joint. The seismic performance of the bottom flange bolted composite beam connection was suffered from both the composite action of concrete slab and the asymmetric load transfer mechanisms between top and bottom beam flange joints. Thus, this paper presents a comprehensive numerical study on the working mechanism of the bottom flange bolted composite beam connections. Three available modelling methods and a new modelling method on the flange-stud-slab interactions were compared. The efficient numerical modeling method was selected and then applied to the parametric study. The influence of the composite slab, the bottom flange bolts, the shear composite ratio and the web hole shape on the seismic performance of the bottom flange bolted composite beam connections were investigated. A hogging strength calculation method was then proposed based on numerical results.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.44 no.5
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• pp.80-86
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• 2012

The disposal of the bottom ash originated from a thermoelectric power plant which used the pulverized coal, has been an important issue of the power plants. In order to find the possible way of recycling of the bottom ash, the applicability of the bottom ash as an inorganic filler for paper making was investigated in this study. The pretreatment with acid were applied for upgrading the properties of bottom ash. The effects of the addition of the bottom ash to the different pulp stocks, Sw-BKP, DIP(Deinked Pulp), Sw-UBKP were evaluated in terms of the change in paper properties. The brightness and tensile strength decreased as the increase of the amount of the bottom ash addition. The bulk and the opacity were increased by the addition of bottom ash. The pretreatment of bottom ash resulted in the increase of improvement of the brightness and the strength properties comparing with those of untreated bottom ash.

• Elastomers and Composites
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• v.38 no.4
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• pp.354-362
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• 2003

The use of a petaloid design for the bottom of carbonated poly(ethylene terephthalate)(PET) bottles is widely spread. This study investigated the causes of bottom cracks. The tensile yield stress variations of PET according to the crystallinity and stretch ratio were examined, then the stretch ratio and strength in the bottom area of a blown bottle were analyzed. A crack test was also performed to observe the cracking phenomena. The distribution of the effective stress and maximum principal stress were both examined using computer simulation to seek the influence of the bottom design on crack. It was concluded that the bottom cracks occurred because of inadequate material strength due to the insufficient stretching of PET, plus the coarse design of a petaloid bottom. The stretch ratio at the bottom during bottle blowing should be higher than the strain hardening point of PET to produce enhanced mechanical strength. The cracks in the bottom of the PET bottles occurred through crazing below the yield stress. The maximum principal stress was higher in the valleys of the petaloid bottom than in the rest bottom area, and the maximum principal stress had a strong effect on the cracks.