Earticle

인공습지는 오염물질 저감기능을 포함하는 여러 가지 생태서비스 기능 때문에 다양하게 적용되고 있다. 그러나 인공습 지에 많은 입자상 물질이 유입하게 되면 유지관리의 어려움과 기능의 저하를 초래한다. 따라서 본 연구는 인공습지 내 입자상 물질의 제거효율 향상을 위한 침강지내 최적 baffle 설치방안을 도출하고자 수행되었다. 최적 저류판 설치방안 은 침강지내 유체와 입자의 흐름을 해석함으로써 도출가능하며, 이를 위해 전산유체역학(Computational Fluid Dynamics, CFD) 이론을 활용하였다. 연구결과는 baffle이 유속을 저하시키고 입자상 물질의 침강효율을 증가시키는 것으로 나타났으며, 경사각을 가진 저류판보다는 수직 저류판이 효과적인 것으로 나타났다. 이러한 연구결과를 활용하 여 공공지역 비점오염저감시설로 설치된 소규모 하이브리드 인공습지의 침강지 효율개선 방안을 도출하였다. 수직각을 이용한 저류판을 설치할 경우 침강효율이 1.2~1.3배 정도 증가하는 것으로 나타났다. 이러한 침강지 내 저류판의 설치 에 따른 결과는 인공습지의 전반적인 저감 효율을 증가시킬 뿐만 아니라 유지관리 빈도를 줄임으로써 비용효율적 인공 습지 설계에 기여할 것으로 평가된다.

Constructed wetlands are widely applied in urban and rural areas for various purposes such as pollutants reduction, acquisition of eco-spaces and habitats, flooding reduction, acquisition of water resources and environmental education. Since the design of constructed wetlands utilizes ecosystems, special consideration must be given to ecological mechanisms, environmental mechanisms and hydrological mechanisms. To ensure the sustainable functionality of constructed wetlands, it is necessary to achieve stable flow rate and velocity, and remove sediments to ensure sufficient space for detention. To enhance the efficiency of constructed wetland sedimentation basins, this study determined the optimal position for baffle installation, and applied Computational Fluid Dynamics (CFD) to the cross-sectional design of wetlands. CFD analysis revealed that the decrease in flow velocity with baffle installation enhanced the efficiency of sedimentation of particulate matters. Vertical baffles had higher sedimentation efficiency than those with an inclined angle. When vertical baffles were installed in the sedimentation basin of a hybrid constructed wetland to reduce non-point source pollutants in urban areas, the average flow velocity within the basin decreased by 10~30%, while the sedimentation efficiency improved by 1.3~1.5 times. The application of CFD to constructed wetlands is expected to improve the cost efficiency of designing hybrid constructed wetlands with high removal efficiency.

본 연구에서는 비용효율적인 인공습지의 설계를 위하여 초기 침강지 내 다양한 도류벽형태에 따른 인공습지의 사수역 및 입자상 물질의 제거효율을 전산유체역학(Computational Fluid Dynamics, CFD)을 통해 연구하였다. 그 결과, 초기 침강지에서 도류벽의 형태는 유입 유속에 영향을 미치며, 침전률에도 큰 영향을 미치는 것으로 분석되었다. 2 ㎛ 와 5 ㎛ 와 같은 미세한 입자에서는 수평으로 설치한 도류벽에서 침전률이 높았으며, 10 ㎛ 와 20 ㎛ 크기의 큰 입자는 수직형 도류벽에서도 높은 침전률을 나타내었다. 또한, 수직형 도류벽의 경우 좁은 면적에 침전이 집중적으로 이루어지기에 다른 형태에 비해 유지관리가 효율적일 것으로 판단되었다. 이에 인공습지의 설계 목적에 따라 가장 적절한 도류벽의 형태를 선정하여 설계해야 할 것으로 보여진다.

In this study, the removal efficiency of the wetland in terms of particulate matter and dead water zone through the application of baffles in the sedimentation were simulated with the use of Computational Fluid Dynamics (CFD) to determine the design of a cost-effective constructed wetland. As a result, it was analyzed that the application of the baffle in the sedimentation tank affect the flow and sedimentation rate. Fine particles such as 2 ㎛ and 5 ㎛ showed high sedimentation rate when the baffles are installed horizontally. large particles such as 10 ㎛ and 20 ㎛ showed also high deposition rate when the baffles are installed vertically. In addition, the vertical baffles is considered to be more efficient than other baffle types in terms of maintenance since the particulate matter are concentrated in narrow areas. Therefore, it is considered that the selection of the most applicable type of baffle depends on the design purpose of the wetland to be constructed.

In this study, numerical analysis is conducted to investigate the flow characteristics of a turning type flood gate fishway with various design factors. The shapes of the fishway are circular and rectangular type. Baffles are installed to reduce the velocity in the fishway, and the gap and rotational arrangement of the baffles are set as design factors. To reduce the maximum velocity, a cavity-shaped break region is installed to examine the flow characteristics according to the presence of the break region. As a result, in the condition where the shape of the fishway is rectangular, the outlet average flow velocity is larger than that in the circular condition. The highest flow velocity occurs when the baffle is rotated in 90-degree arrangement. As the baffle gap increases, the average velocity increases. The cavity-shaped break region creates a recirculation zone in the fishway, and as a result, shows a decrease in the maximum velocity of up to 5.8%.

수리동력학적 강우유출수 처리장치(HSS)는 입자에 회전류를 가하여 강우유출수내입자물질들을 처리하는 장치이다. 실험실 규모의 HSS장치의 운전결과와 전산유체역학모의에 의해 예측한 입자유속분포를 비교분석하였다. 입자추적기법을 이용하여 HSS장치에서의 입자제거효율을 예측하였다. 유속장을 분석한 결과 HSS장치에 직각으로 유입되는 지점에서 유속이 가장 빠르며 하부로 이송되며 유속은 감소하는 경향을 나타내었다. HSS 장치에서 유입수를 본체의 내통으로 유입시켜 원심력을 증대시키고, 유입부 유도판을 부착하여 원심가속도를 증가시켜 입자분리효율을 10% 이상 향상시킬 수 있는 것으로 나타났다. RNG κ-ε모델에 의해 HSS장치내 유속장 분포는 입자영상유속계(PIV)로 측정한 유속장 분포와 유사한 결과가 나타났다. 전산유체역학모의 결과는 PIV측정으로 검증할 수 있으며, 전산유체역학 모의에 의한 유속장 해석 및 입자추적기법은 HSS장치의 사전설계에 중요한 도구로 활용될 수 있다.

Hydrodynamic stormwater separator (HSS) is a storm runoff treatment device, which separates solids pollutants from water using swirling motion. The particle velocity distribution in a laboratory scale HSS has been simulated using computational fluid dynamics models and the removal efficiencies were compared with measurement results. This work simulated the particle velocity tracking pattern to efficiency prediction in a HSS. The results show that the highest velocity occurred at the tangential inlet and the velocity decreases rapidly as the flow spirals within the HSS and a near stagnant zone occurred at the bottom. The baffle at inside skirt was found that entrainment of resuspened particles into the overflow could be minimized. In case of HSS with baffle, the removal efficiency was higher than HSS without baffle about 10%. The flow field in a laboratory scale hydrodynamic separator has been simulated using a RNG κ-ε turbulent models and the simulated flow flied is found to be consistent with the data obtained PIV measurement. The CFD simulation results were verified by the PIV measurements. The CFD simulated flow field will be useful tool to analysis the behavior of particles in the hydrodynamic stormwater separator.

연속주조 공정에서 턴디쉬는 불순물(슬래그)를 용강에서 부상 분리시켜 용강이 청정하게 주조되게 하는 데 필수적이다. 턴디쉬는 또한 레이들 교체 중에는 주조 공정이 중단되지 않도록 용강을 저장하는 용기 기능도 한다. 따라서 턴디쉬 내의 유동 제어 부재 (즉, 배플, 댐, 위어 등)의 배열과 그 배열이 용강의 유동 패턴에 미치는 효과를 이해하는 것이 고청정도 강을 달성하는 기본적이고도 본질적인 부분이다. 본 연구에서는 1/3 축소 턴디쉬 수모델로 유동 제어 부재의 4가지 배열을 시뮬레이션하여 각각에 상응하는 실제 턴디쉬에서의 용강 유동 패턴의 특징을 비교하였다.

The tundish is necessary to separate impurities (slag) from the molten steel and to keep the steel to be cast pure in continuous casting (CC) process. The tundish also serves as a storage vessel for the molten steel during a ladle change in order not interrupt the casting process. Therefore, understanding of the arrangement of the flow control devices (i.e. baffles, dams, weirs and so on) and thus its effect to the flow pattern of the molten steel within the tundish is basic and essential parts of accomplishing the highest cleanliness of the steel. In this study, a 1/3 reduced tundish water model with four arrangements of flow control devices within the tundish was used to simulate and compare the characteristics of corresponding molten steel flow behaviors in prototype.

Jabon (Anthocephalus cadamba) is a promosing fast growing wood species that is widely planted in community forests and industrial plantation forests but the wood has a relatively low density, durability, and mechanical properties which limited its application as structural timbers. One of the alternative utilizations of jabon wood is by converting into wood pellet for bioenergy. The aim of this study was to improve the properties of wood pellets from jabon through rapid torrefaction using Counter-Flow Multi Baffle (COMB) reactor, a pilot plant for torrefaction of biomass with a capacity of 20 kg/h that has a main advantage of performing torrefaction within a short period of time. Wood pellets were classified according to its length and then torrefied at 300°C with a residence time of 3 min. Torrefied pellets (black pellets) were succesfully produced. The initial moisture content of the long and short pellets of 12.76% and 12.47% decreased up to 2.85% and 2.61% after torrefaction. Water immersion test for 1 min, 5 min, 30 min, 1 h, 6 h, 12 h, and 24 h showed that the raw pellets (control) fully disintegrated after 30 min, while black pellets showed no significant disintegration even after 24 h test which is an advantage for long period storage of pellets. The initial calorific values of long and short pellets of 17.69 MJ/kg and 17.35 MJ/kg increased up to 31.79 MJ/kg and 32.02 MJ/kg after torrefaction. The results proposed that rapid torrefaction using COMB could provide a great improvement in bioenergetic properties of wood pellets from fast growing species as jabon wood.

본 해설에서는 광산배수 처리시설을 비롯하여 다양한 수처리시설에 널리 적용되는 장방형 침전조의 처리 효율을 향상시키기 위한 연구 결과들을 종합하여 상부 배플의 적용 방안 등을 제시하였다. 그리고 산화조에서 지그재그형 배플의 적용성이 높은 것과 해당 배플을 종방향으로 설치하는경우 횡방향 설치 대비 증가하는 효율을 제시하였다. 한편, 다양한 매질반응조에서는 자연유하가필요한 경우 공통적으로 SAPS 형태의 넓은 면적과 수직흐름이 필요하다는 연구 결과를 제시하고, 그럼에도 불구하고 펌프가 적용되는 경우 다양한 구조를 적용할 수 있는 가능성을 나타내었다.

This review summarizes research findings aimed at improving the treatment efficiency of rectangular settling tanks, which are widely used in various water treatment facilities, including mine drainage treatment systems. It provides design options for applying hanging baffles and demonstrates that the zigzag baffles are highly applicable in oxidation tanks. Longitudinal installation of the baffles provides greater efficiency compared to transverse installation. Furthermore, this study demonstrates that when gravity flow is required in media reactors, a wide area and vertical flow in the form of the Successive Alkalinity Producing System (SAPS) are necessary. Nevertheless, when pumping is employed, the possibility arises of applying a broader range of structural configurations.

Physical stimulation of agitation with a baffle or an impeller has been reported to improve cephalosporin C (CPC) production and cell growth. CPC concentration increased about 30% when it compared with baffle flasks without glass beads. And also fragmentation rate constant, which can be used to estimate the tensile strength of fungal hyphae, was expressed by numerical values of 40% or above. The variation of pH had no relationship with influence between CPC production and the number of the glass bead in baffle flasks. Morphological modification of number of units, the sum of number of differentiated hypae or arthrospores, was found to have similar figures of the variation of CPC concentration. And mean area of an arthrospore was minimun at 3 days.

Emission regulation for an SI engine is becoming stricter continuously. If blow-by gas, which contains oil mist, recirculates in a cylinder, it cause severe harmful emissions and engine problems. Thus an SI engine also needs the oil separator to separate oil mist in blow-by gas. Comparing SI engine with CI engine, SI engine has a small quantity of blow-by gas, so it needs highly efficient oil separator. Baffle plate is very easy to produce and it has low back pressure among the many kind of oil separators. In this paper, a model was developed that adopted baffle plate and porous plate. Flow characteristics, oil separation performance and back pressure with various position and shape of baffle plate was calculated by CFD. As results, the more flow that faced to baffle plate cause increase of efficiency. And modified oil separator can have low back pressure and high oil separation efficiency.

A numerical study has been performed to investigate the thermal Performance of Solar heating system with baffle type of storage tank by using the commercial code TRNSYS. As a result, the solar fraction depends strongly on the efficiency and heat loss coefficient of solar collector as well as the heating capacity of house and the water temperature supplied to the shower. In addition, the solar fraction has been basically ranked to higher level in baffle type of storage tank than typical type of single storage tank for the range of operation condition.

This study investigated the effects of regional down insulation on thermal sensation, thermal comfort, and shivering responses during cold exposure while wearing a baffle-type padded jacket. Eight healthy young males (23.4 ± 2.5 y) participated in nine trials in a climate chamber set at ?9.7 ± 1.0°C, each lasting 60 min in a seated posture. The experimental padded winter jacket was divided into eight compartments (chest, front waist, abdomen, upper back, lower back, hips, upper arms, and forearms), and insulation was selectively removed from one compartment per trial, with the fully filled jacket serving as the control. Whole-body and local thermal sensation and comfort were assessed every 10 min using standardized categorical scales, and shivering frequency and location were recorded. Removal of insulation from the chest, abdomen, or hips did not significantly affect whole-body thermal sensation or thermal comfort. In contrast, removing insulation from the upper back or upper arms significantly increased local cold sensation (p < 0.05) and reduced thermal comfort. Clothing insulation measured by a thermal manikin decreased only slightly (≤ 0.07 clo) when any single compartment was unfilled, suggesting minimal overall thermal impact. These results indicate that maintaining insulation at the upper back and upper arms is critical for preserving thermal sensation/comfort and reducing shivering, whereas partial insulation reduction at the chest or abdomen is possible without compromising overall thermal perception. The findings provide practical insights for designing energy-efficient winter jackets that minimize down usage while maintaining wearer comfort and supporting behavioral thermoregulation.

Simultaneous measurement of velocity and concentration fields in a stirred mixer flow using a combined Stereo-PIV/Planar-LIF technique is carried out. Instantaneous velocity fields and concentration fields represent the local flow characteristics. A baffle is perpendicularly attached to the Wall to remove inactive region which shows very slow dispersion. It is found that the baffle produces tip vortex and breaking the divided streamline, so that mixing efficiency could be increases significantly.

This paper presents phenomena of vibration and noise due to acoustic resonance in tube bank of a large fossil power plant. The phenomena of acoustic resonance may arise when the vortex shedding frequency coincides with the acoustic natural frequency. In this system dominant frequency of vibration and noise was 37.5Hz. The $3^{rd}$ acoustic natural frequency calculated was 37.2 Hz. When the difference of vortex shedding frequency and acoustic natural frequency is within ${\pm}20%$, acoustic resonance could occur. If system is the state of acoustic resonance, vibration and noise become large. In order to prevent acoustic resonance, anti-noise baffle should be installed in the tube bank. In the case of installing baffle, we should consider the number of baffle and the effect of acoustic mode due to baffle extension length. To do this, we did acoustic mode analysis. After installing anti-noise baffle, acoustic resonance was disappeared and vibration magnitude and noise level was reduced dramatically.

An off-axis telescope has several advantages in optical performance comparing with a conventional on-axis telescope. However, in general, an off-axis telescope has a narrow field of view due to the linear astigmatism caused by the asymmetric structure. It was shown in the previous work that the linear astigmatism can be eliminated by properly configuring parameters in a confocal off-axis reflector system. Furthermore, the third order aberrations of a confocal off-axis telescope can be minimized by optimizing the shape of the mirrors. Despite many advantages, the confocal off-axis telescopes have been evaded because of difficulties of off-axis mirror fabrication, alignment process and unaccustomed off-axis baffle design. The baffle for the off-axis telescope should be designed considering that the effects of stray lights are different because of the asymmetry of off-axis system. In this poster, the design, manufacturing, and test for the baffle and housing of an off-axis telescope are presented.

A baffle system for an airglow photometer, which will be on board the Korea Sounding Rocket-III(KSR-III), has been designed to suppress strong solar scattered lights from the atmosphere below the earth limb. Basic principles for designing a baffle system, such as determination of baffle dimensions, arrangement of vanes inside a baffle tube, and coating of surfaces, have been reviewed from the literature. By considering the constraints of the payload size of the KSR-III and the incident angle of solar light scattered from the earth limb, we first determined dimensions of a two-stage baffle tube for the airglow photometer. We then calculated positions and heights of vanes to prohibit diffusely reflected lights inside the baffle tube from entering into the photometer. In order to evaluate performance of the designed baffle system, we have developed a ray tracing program using a Monte Carlo method. The program computed attenuation factors of the baffle system on the order of $10^{-6}$ for angles larger than $10^{\circ}$, which satisfies the requirements of the KSR-III airglow experiment. We have also measured the attenuation factors for an engineering model of the baffle system with a simple collimating beam apparatus, and confirmed the attenuation factors up to about $10^{-4}$. Limitation of the apparatus does not allow to make more accurate measurements of the attenuation factors.