• 수산해양기술연구
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• 제36권3호
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• pp.195-201
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• 2000

계량어군탐지기를 이용하여 저서어를 대상으로 에코적분을 행하는 경우, 적분범위의 하한을 결정하기 위해 설정하는 해저기준이나 해저오프셋은, 저서어 자원량추정의 중요한 요인 중의 하나이다. 해저부근의 어군에코의 해석으로부터 해저기준의 결정방법과 최적 오프셋에 관하여 고찰한 결과, 다음과 같은 결과를 보였다. 1) 적분층의 폭을 5m로 하여, 적분범위를 1샘플링씩 해저방향으로 이동하면서, 해저부근의 S$\sub$a5m/의 변화를 본 결과, 해저부근의 어군에코를 적분하기 위해서는, 적분범위의 하한을 가능한 해저까지 접근시켜야 한다. 2) 에코레벨의 역치로서 해저검출을 행한 경우, 역치가 클수록 해저 검출 불능횟수가 증가하고, 작을수록 해저 오검출 횟수가 늘어 났다. 3) 에코레벨의 최대변화점을 해저기준으로 한 해저검출법은, 그 정도가 매우 높았으며, 나아가 에코레벨의 변동에 대해 아주 안정한 해저기준 알고리 즘으로 적합하였다. 4) 이 해저검출 알고리즘에 의하면, 최적해저오프셋은 해저 기준으로부터 0.4ms이내였고, 이것은 펄스파형과 해저지형에 대한 음향빔에 의존한다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2008년도 추계 학술논문 발표대회
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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.

• 콘크리트학회논문집
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• 제14권2호
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• pp.223-230
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• 2002

본 연구의 목적은 저강도 고유동 재료(CLSM)로서 매립처리 되는 bottom ash의 재활용 가능성을 실험하는데 있다. 저강도 고유동 재료는 포틀랜드 시멘트, 플라이애시, 모래, 물의 혼합으로 만들어지는 결합성 재료로서 재료의 타설과 동시에 유동성과 셀프레벨링성을 나타낸다. 플라이애시만을 사용한 배합이 bottom ash가 저강도 고유동 재료로서 사용가능한 내구성능을 나타내는지 비교하기 위하여 같이 실험되었다. bottom ash를 사용한 배합의 내구성능은 해로운 물리, 화학적 환경에서 실험되었으며 그 결과로서 bottom ash를 사용한 저강도 고유동 재료의 내구성능은 비구조 부재의 충전을 위한 적용분야에서 사용가능하게 나타났다. 또한 bottom ash를 첨가한 저강도 고유동 재료는 환경적으로도 안전하게 나타났다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2008년도 춘계 학술발표회 제20권1호
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• pp.489-492
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• 2008

본 연구에서는 공공 및 민간의 전력수요가 증가함에 따라 화력발전소에서 다량으로 발생하고 있는 석탄재의 약 10${\sim}$15%정도를 차지하는 Bottom Ash를 유효재활용하기 위하여 Bottom Ash 굵은골재 혼입에 따른 콘크리트의 기초적 물성 및 강도특성을 분석하였다. 그 결과, Bottom Ash 굵은골재의 혼입률이 증가할수록 슬럼프는 감소하는 경향을 나타내었으며, 혼입하지 않은 경우에 비하여 약 4.5${\sim}$54.2%정도 감소하였다. 이에 비하여 공기량은 Bottom Ash 굵은골재를 혼입함에 따라 거의 영향이 없고 그 차이는 미소한 것으로 나타났다. 블리딩의 경우는 슬럼프의 경향과 유사하였으며 Bottom Ash 굵은골재의 혼입률이 증가함에 따라 초기의 블리딩이 현저하게 감소하였다. 또한, 압축강도는 Bottom Ash 굵은골재의 혼입률이 증가할수록 감소하였으며 혼입률 40%까지는 혼입하지 않은 경우에 비하여 약 1.1${\sim}$5.3%정도 감소하였고, 혼입률 60% 이상에서 급격히 감소하여 압축강도는 Plain의 약 85.2${\sim}$87.7%정도 발현하였다. 따라서, 콘크리트용 굵은골재로서 Bottom Ash 굵은골재를 대량으로 활용하기 위해서는 강도향상의 보강요소를 사용하는 것이 검토되어야 할 것으로 판단된다.

• 한국항만학회지
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• 제6권2호
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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.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2001년도 추계학술대회 논문집
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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.

• 한국수산과학회지
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• 제49권3호
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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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• 제47권2호
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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.

• 펄프종이기술
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• 제44권5호
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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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• 제38권4호
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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.