• International Journal of Naval Architecture and Ocean Engineering
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• 제6권4호
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• pp.1024-1040
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• 2014

The theoretical background and a numerical solution procedure for a time domain hydroelastic code are presented in this paper. The code combines a VOF-based free surface flow solver with a flexible body motion solver where the body linear elastic deformation is described by a modal superposition of dry mode shapes expressed in a local floating frame of reference. These mode shapes can be obtained from any finite element code. The floating frame undergoes a pseudo rigid-body motion which allows for a large rigid body translation and rotation and fully preserves the coupling with the local structural deformation. The formulation relies on the ability of the flow solver to provide the total fluid action on the body including e.g. the viscous forces, hydrostatic and hydrodynamic forces, slamming forces and the fluid damping. A numerical simulation of a flexible barge is provided and compared to experiments to show that the VOF-based flow solver has this ability and the code has the potential to predict the global hydroelastic responses accurately.

• 한국식품조리과학회지
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• 제13권2호
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• pp.185-191
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• 1997

The effects of five hydrated emulsifiers with or without specified proteins (flour, egg) and/or polydextrose on the reduced-calorie cake as baked product model systems were compared. The small molecule amphiphiles (SMA) used were monoglycerides (MG), sorbitan monostearate (SMS), polysorbate (PS) 60, sucrose ester (SE) F7O, and SE Fl60. All flour batters with each emulsifier and supplements had similar low foam drainages (0.00∼1.03$m\ell$) indicating those systems were fairly stable in the presence of flour protein. The cake batter using starch instead of flour without egg and polydextrose and with some emulsifiers had relatively large amount of drainages (4.20∼5.87$m\ell$). When the egg and polydextrose were added to the blank cake batters using starch, foam drainages tended to show relatively low scores (0.13∼1.48$m\ell$) indicating the cake batter dispersion system is stabilized. Starch cakes made with SE F70 without egg or polydextrose(blank) unexpectedly had high volume index of 199.

• 한국수산과학회지
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• 제35권2호
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• pp.140-145
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• 2002

본 연구는 사육조 용적 2.5$m^3$ 규모의 pilot-scale 순환석과식 양어장에 나일 틸라피아를 2, 5, $7\%$의 밀도로 사육하면서 사육조내의 수질과 포말분리기에 의해 배출된 포말농축액의 수질을 분석하여 병류 공기구동식 포말분리기의 실제 어류를 사육하는 양어장에서 나타내는 효율을 측정하고자 하였다 사육밀도가 증가함에 따라 단백질, 총 부유 고형물, 화학적 산소요구량 등 각 수질 인자의 농도가 증가하였으며 포말 농축액의 유출량도 증가하였다. 사육조의 단백질 농도는 사육밀도가 $5\%$에서 $7\%$로 높아짐에 따라 16.6 g/$m^3$에서 21.9 g/$m^3$으로 증가하였으며 일간 제거량은 0.99 g/day에서 2.5 g/day로 증가하였으나 포말의 단백질 농도는 50.6 g/$m^3$에서 36.6 g/$m^3$으로 감소하여 농축비는 3.2에서 1.9로 감소하였다. 사육밀도의 변화에 따른 총 부유 고형물과 화학적 산소 요구량의 일간 제거량, 농축비와 포말 농축액의 농도의 변화는 단백질 제거특성과 그 형태가 유사하였다 총 부유 고형물의 일간 제거량은 사육밀도 $2\%$일 경우 0.2g/d, $5\%$에서는 0.8 g/d 7%에서는 1.5 g/d로 사육밀도와 비례하여 증가하였으며 화학적 산소요구량의 일간 제거량은 사육밀도 $2\%$일 경우 1.6 g/d, $5\%$에서는 4.2 g/d, $7\%$에서는 7 g/d로 나타났다. 총 부유 고형물과 화학적 산소 요구량의 농축비와 제거량은 단배질과 비슷한 경향을 보였으며 총 부유 고형물과 화학적 산소 요구량의 농축비의 경우 $2\%$의 사육 밀도에서 각각 10.2, 8.4의 가장 높은 값을 나타내어 포말분리기가 양어장 순환수 처리에 효율적임을 알 수 있었다.

• 한국대기환경학회지
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• 제14권1호
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• pp.43-62
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• 1998

This study was carried out to investigate the influence of different sampling methods on the measured concentrations of polycyclic aromatic hydrocarbons (PAH) both in the vapor and particulate phases, and to evaluate the effects of ambient temperature and sampling duration on the losses of PAH associated with particle samples due to volatilization. The experimental protocol of this study is consisted of two parts. The first part is related to the comparison of PAH concentrations measured by 4 different sampling systems, each of which involves different sampling principles for comparison purposes, including a medium-volume sampler with XAD-2 adsorbent, a high-volume sampler with polyurethane foam (PUF), two identical low-volume samplers: one with XAD-2 and the other with PUF, respectively. The second part of this study is to quantitatively estimate the losses of particulate PAH samples by volatilization during sampling, using two identical low-volume samplers: one was used for changing the filters every 3 hrs, 6 hrs, 12 hrs, and 24 hrs sampling, while the other was maintained for continuous 48 hours sampling without changing the filter. The concentrations of volatile PAH including 2-3 rings appeared to be significantly affected by the type of adsorbent. Measured levels of these lower-molecular weight PAH by XAD-2 adsorbent were much higher than those by PUF for both high-volume and low-volume sampling. PUF was found to give rise to unknown components that interfered with the PAH analysis, even after extensive clean-up. In addition, the retention efficiency of PUF for lower molecular weight PAH was subject to a large variation, being significantly influenced by sampling conditions such as ambient temperature. However, the effect of sampling methods with different adsorbents on the measured levels of semi-volatile compounds including 4 rings PAH such as fluoranthene, pyrene, BaA and chrysene, was not so much significant as more volatile PAH compounds. It was also clear from this study that volatilization losses of the semi-volatile PAH collected on the filters were inevitably occurred during prolonged sampling, and hence the results obtained from conventional sampling methods may not be expected to yield an accurate distribution of PAH between the vapor and particulate phases.

• 자원리싸이클링
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• 제29권1호
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• pp.53-61
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• 2020

본 연구는 시멘트 대비 산업부산물을 90% 이상 대체한 친환경 결합재를 이용하여 저강도·고유동을 갖는 지반보수용 기포콘크리트 소재를 개발하기 위한 연구로서, 산업부산물을 다량 활용시 발생하는 기포콘크리트의 초기 침하율 및 체적변화를 개선하기 위하여 CSA(Calcium sulfo aluminate)를 소량 대체하여 기초특성을 평가하였다. 기포콘크리트용 친환경 결합재 대비 CSA의 대체율은 2.5, 5, 10%로, 굳지않은 특성, 경화특성, 공극구조 및 수화물을 분석하였다. 실험결과 친환경 결합재 사용시의 높은 침하깊이를 CSA 2.5% 사용만으로도 개선할 수 있었으며, 그로인해 경화 후에도 타설된 시험체의 상중하의 중량편차도 개선되었다. CSA 첨가에 따라 공극구조도 작고 균일한 사이즈의 독립기포 형성에 기여하였으며, 초기강도는 개선되었다. 그러나 CSA의 혼입률의 증가에 따라 장기강도는 감소하였으나, 5% 이하를 사용할 경우 목표강도를 만족하였다. 이로써 산업부산물을 다량 활용한 친환경 결합재에 CSA의 2.5% 첨가만으로도 목표성능의 저강도 고유동을 갖는 지반 보수용 기포콘크리트 제조가 가능한 것을 확인하였다.

• 한국건축시공학회지
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• 제15권1호
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• pp.9-16
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• 2015

친환경 건설 재료의 일환으로 고로슬래그 미분말을 다량치환한 콘크리트에 대해 재생골재를 이용해 잠재수경성 반응을 활성화 시켜 콘크리트로서의 활용방안 모색과 탄산화를 저감시킬 목적으로 다양한 기밀성 향상재를 표면에 부착하여 탄산화 저감효과를 측정하였다. 재생골재의 사용은 표면의 모르타르 및 미수화 시멘트로 인해 고로슬래그 미분말을 다량 치환한 콘크리트에 양호한 영향을 미친 것으로 판단되었다. 콘크리트 표면의 기밀성 향상재에 따른 탄산화 저감 효과는 기밀성 향상재 종류와 상관없이 콘크리트 표면에 효과적으로 부착되어 있는 경우라면 모두 양호한 탄산화 저감 성능을 나타내었다. 그러므로 시공이 용이하고 취급이 간편하며 콘크리트 표면에서 장기간 양호한 내구성을 발휘하는 기밀성 향상재로 선시공 1중 에어캡이 가장 양호한 방법으로 판단되었으며, 추가적으로 단열성능을 고려하였을 때에는 선시공 2중 에어캡이 효율적인 방법으로 생각해 볼 수 있었다.

• 한국환경보건학회지
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• 제35권4호
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• pp.322-333
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• 2009

In this study, a measurement method was evaluated for the determination of polycyclic aromatic hydrocarbons (PAHs) in the ambient atmosphere. PAHs were sampled by high-volume samplers, and were then analysed with a GC/MS system. Particulate PAHs were collected on $8"{\times}10"$ quartz fiber filter, while vapor phase PAHs were adsorbed on polyurethane foam (PUF). Target compounds included a total of 36 PAHs, which are known to be frequently detected in the urban atmosphere. It was not necessary to clean-up samples before samples were analyzed using GC/MS, and the overall performance of the method was tested by a variety of quality control and quality assurance schemes. It is generally known that the clean-up procedure can negatively affect the recovery of samples. Precision and accuracy was evaluated using SRM provided by US NIST, and the results were generally satisfactory and reliable. However, the GC/MS method appeared not to be adequate for 6-rings PAHs, such as coronene, due to its lower sensitivity. In addition, collection efficiencies for low molecular compounds, such as 2-rings PAHs, were poor because of the lower retention volume of the PUF adsorbent. As a result, it was concluded that the method based on high-volume sampling and GC/MS analysis can give very reliable data by simultaneous sampling of both particulate and vapor phases for 3-rings to 5-rings PAHs of environmental concern.

• Journal of Advanced Marine Engineering and Technology
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• 제33권2호
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• pp.244-251
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• 2009

Porous media have especially large surface area per volume, which contain complex fluid passage. If porous media can be applied to cool a CPU or an electronic device with large heat dissipation, it could result in heat transfer enhancement due to the enlargement of the heat transfer area and the flow disturbance. This study is aimed to identify the heat transfer and pressure drop characteristics of high-porosity metal foams in a horizontal channel. Experiment is performed with the various heat flux, velocity and pore density conditions. Permeabilities, which is deduced from Non-Darcy flow model, become lower with increasing pore density. Nusselt number also decreases with higher pore density. High pore density with same porosity case shows higher pressure loss due to the increase of surface area per unit volume. The fiction factor decreases rapidly with increase of Reynolds number in Darcy flow region. However, it converges to a constant value of the Ergun coefficient in Non-Darcy flow region.

• Journal of Advanced Research in Ocean Engineering
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• 제2권2호
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• pp.48-60
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• 2016

Accurate simulation of free-surface wave flows around a ship is very important for better hull-form design. In this paper, a computational fluid dynamics (CFD) code which is based on the open source libraries, OpenFOAM, was developed to predict the wave patterns around a ship. Additional anti-diffusion source term for minimizing a numerical diffusion, which was caused by convection differencing scheme, was considered in the volume-fraction transport equation. The influence of the anti-diffusion source term was tested by applying it to free-surface wave flow around the Wigley and KCS model ships. In results, the wave patterns and hull wave profiles of the Wigley and KCS model ships for various anti-diffusion coefficients showed quite close patterns. While, the band width of the water volume-fraction values between 0.1 to 0.9 at the Wigley and KCS model hull surfaces was narrowed by considering the anti-diffusion term. From the results, anti-diffusion source term decreased free-surface smearing.

• 한국식품조리과학회지
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• 제20권4호
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• pp.387-395
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• 2004

The effect of commercial Doenjangs (Korean soybean pastes) on sponge cake making was studied. When Doenjang was added to e99 foams at levels of 5, 10, 15 and 20%, there were no big differences in viscosity or stability of egg foams up to 15%, and thus in cake volume index, compared to those of control (without Doenjang). In the results of preference rank test, cake with 10% Doenjang was preferred to the other cakes. Therefore, it was decided that the addition of 10% Doenjang was suitable for sponge cake making. When seven commercial Doenjang products were used at 10%, there were differences in physical and sensory properties. The decreased viscosity of egg foams reduced their stability and so decreased the quality of the sponge cakes with low volume index and low texture scores. The use of Doenjangs improved the flavor of sponge cake and so countervailed the undesirable egg flavor. Especially, “C” Doenjang product, which increased the viscosity and stability of egg foams, produced good foaming ability and the highest physical and sensory quality, thus the higher overall acceptable scores than the control. It was probably due to its high amount of protein hydrolysate above 10-KDa. Consequently, the suitable amount of Doenjang was fixed at 10% and “C” Doenjang product was chosen as the best among the commercial products for sponge cake making.