Deposition efficiency of barium hexaferrite by aerosol deposition

Johnson, Scooter D.,Schwer, Douglas,Park, Dong-Soo,Park, Yoon-Soo,Gorzkowski, Edward P. Elsevier 2017 Surface & coatings technology Vol.332 No.-

<P><B>Abstract</B></P> <P>We present results of barium hexaferrite powder mass consumption across a wide range of starting powder quantities and deposition times. From these results we develop a transfer efficiency figure of merit to describe deposition efficiency and growth rates applicable to aerosol deposition and similar spray deposition techniques. We find that the transfer efficiency of barium hexaferrite was 0.082% and the transfer efficiency rate coefficient was 0.056min<SUP> −1</SUP> with a decay factor of −0.773. As a means to further understanding the deposition efficiency we present flow simulations of an aerosol deposition system using different particle sizes and standoff distances. We find that impact with the substrate strongly depends on the particle size, particle location within the nozzle, and standoff distance. We find that the values in the simulation are consistent with those used to produce films with the aerosol deposition system used at the Naval Research Laboratory and consistent with values found in the literature. We find that to improve the transfer efficiency nozzle design must be optimized, particle size must be carefully selected, standoff distance must be selected, and the powder in the aerosol chamber must be delivered at an optimal rate. These factors may be individually tuned to contribute to the final transfer efficiency figure of merit that can be used to assess the efficiency of the aerosol deposition process.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Mass consumption of powder in aerosol deposition is related to film thickness. </LI> <LI> A deposition efficiency figure of merit is developed for aerosol deposition. </LI> <LI> Fluid dynamic simulations show that particle impact depends on particle size. </LI> <LI> Fluid dynamic simulations show that particle impact depends on standoff distance. </LI> <LI> Deposition efficiency is related to mass consumption and to particle impact. </LI> </UL> </P>

Influences of deposition strategies on thermo-mechanical characteristics of a multilayer part deposited by a wire feeding type DED process

Bih Lii Chua,안동규,김재구 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.12

Variation in process parameters and deposition strategies has produced different thermo-mechanical characteristics in a part fabricated by a wire feeding type directed energy deposition (DED) process. The purpose of this paper is to select a proper deposition strategy to fabricate a straight wall part using a wire feeding type DED process. The deposition strategies include different deposition directions, deposition patterns and interpass time. In order to investigate the influences of deposition strategies on thermo-mechanical characteristics of fabricated part, three-dimensional finite element analyses (FEAs) have been proposed. A volumetric heat flux has been applied to simulate the transient heat transfer phenomena of the DED process. Influences of different deposition strategies on thermo-mechanical characteristics of fabricated part have been discussed. From the result of residual stress distribution, an appropriate deposition strategy has been selected for the multi-layer deposition. Results of FEAs have been verified through comparison of vertical displacements between estimated results from FEAs and those of experiments.

Effect of particle size on various substrates for deposition of NiO film via nanoparticle deposition system

Kim, H.,Yang, S.,Ahn, S.H.,Lee, C.S. Elsevier Sequoia 2016 THIN SOLID FILMS - Vol.600 No.-

We report the deposition mechanism of NiO particles using a nanoparticle deposition system. To understand the effects of particle size and substrates on the deposition, nano-, 100-nm-, sub-micro-, and micro-sized NiO particles were deposited on Si wafers, Ni-coated Si wafers, and fluorine-doped tin oxide (FTO)-coated glass. It was found that 100-nm- and nano-sized NiO particles were deposited, forming loosely compacted coating layers, by the breaking up of agglomerates, regardless of the type of substrate. In contrast, sub-micro- and micro-sized NiO particles formed dense and compact coating layers by deformation and fracturing on the Si and Ni-coated Si wafers. Moreover, sub-micro- and micro-sized NiO particles were not deposited on FTO glass; this was likely attributable to the NiO being harder than FTO glass and the micro-sized NiO particles would likely have rebounded on impact, resulting in no deposition. Thus, the deposition mechanism of NiO particles may be greatly related to the relative hardness difference between the NiO particles and the substrate. Moreover, it was found that different particle sizes resulted in different friction and mobility, based on response angle measurements, influencing the deposition mechanism(s), especially at the interface. When the particle size was greater than 100nm, the deposition was due primarily to deformation and fracturing during the collision with the substrate. In particular, the 100-nm-sized NiO particles showed both mechanisms, a two-step process, with deformation or fracturing at the interface between the substrate and particles, followed by a loosely compacted coating layer forming, preserving the original particle shape. Thus, it was confirmed that the 100-nm-sized NiO particles were at or near a boundary for deposition mechanisms. The effects of particle size and substrate for dry deposition were explained successfully by assessing the deposition behavior using analytical tools.

대기오염 입자의 인테 호흡기내 비대칭 국부침전 특성에 관한 연구

구재학,김종숭 한국대기환경학회 2003 한국대기환경학회지 Vol.19 No.5

Particle deposition in human lungs was investigated theoretically by using asymmetric five-lobe lung model. The volumes of each of the five lobes were different, thereby forming and asymmetric lung structure. The tidal volume and flow rate of each lobe were scaled according to lobar volume. The total and regional deposition with various breathing patterns were calculated by means of tracking volume segments and accounting for particle loss during inhalation and exhalation. The deposition fractions were obtained for each airway generation and lung lobe, and dominant deposition mechanisms were investigated for different size particles. Results show that the tidal volume and flow rate have a characteristic influence on particle deposition. The total deposition fraction increases with an increase in tidal volume for all particle sizes. However, flow rate has dichotomous effects: a higher flow rate results in a sharp increase in deposition for large size particles, but decreased deposition for small size particles. Deposition distribution within the lung shifts proximally with higher flow rate whereas deposition peak shifts to the deeper lung region with larger tidal volume. Deposition fraction in each lobe was proportional to its volume. Among the three main deposition mechanisms, diffusion was dominant for particles<0.5㎛ whereas sedimentation and impaction were most influential for larger size particles. Impaction was particularly dominant for particles>8㎛. The results may prove to be useful for estimating deposition dose of inhaled pollutant particles at various breathing conditions.

공탁법상 주요쟁점에 관한 연구

오시영 한국민사집행법학회 2008 民事執行法硏究 : 韓國民事執行法學會誌 Vol.4 No.-

공탁에 대한 법적 성질 및 개념에 대한 학설 및 판례의 입장에 대하여 살펴 보았으며 그 중 절충설의 견해가 현실적으로 가장 타당하다고 보았다. 또한 현 행 공탁법의 운영과 관련하여 문제가 되고 있는 공탁의 근거에 대한 엄격성의 완화 필요성, 일부변제공탁의 허용 여부, 부동산공탁의 허용 여부, 공탁금의 소 멸시효 적용 여부, 공탁금이자의 적정성 여부 등에 대하여 살펴보았다. 개인적으로는 공탁절차가 공법적 영역에서 법원(공탁공무원)의 후견적 기능 의 수행이라는 면 때문에 엄격하게 운영되어야 할 필요성이 크다는 점을 인 정하면서도 공탁의 본질이 공탁자와 피공탁자 사이의 재산권 분쟁을 해결하 는 수단이라는 점을 중시하여 사적자치의 법리가 최대한 보장되는 것이 바람 직하다고 본다. 이러한 기본원리를 근거하여, 일부변제공탁을 허용하는 것이 금전채권이 분할채권의 원칙에 의해 운영되는 민법에 공탁법이 부응하는 것 으로 타당하며, 부동산공탁 역시 금지규정이 없으므로 허용하는 것이 타당하 다고 생각한다. 공탁금에 대한 소멸시효의 법리는 국민의 재산권 존중이라는 헌 법정신에 비추어 볼 때 더 이상 존치시킬 이유가 없다고 할 것이므로 폐지 하는 것이 바람직하며, 공탁금이자 역시 그 이율이 너무 낮아 공탁한 국민의 재산권이 피해를 보고 공탁물보관소인 금융기관만 과도한 이익을 보는 면이 크다. 따라서 사법부가 이에 대한 관심을 가지고 금융기관의 공탁금 운영과 관련한 손익분기점을 연구하여 실질적인 불이익이 국민에게 돌아가지 않도록 공탁금금리수준을 합리적으로 상향조정할 필요가 있다고 본다. 국가우월사상이 팽배했던 19세기에 제정된 외국의 공탁법을 그대로 계수한 우리로서는 민주주의사회로 바뀐 21세기인 오늘날 사법부가 적극적으로 국민 의 재산권을 보호해줄 수 있도록 공탁금에 대한 인식을 전환할 필요성이 크 다고 하겠다. 이 연구가 공탁금과 관련하여 국민의 재산권 보장을 위한 작은 초석이 되었으면 한다. Eclectic view is actually considered as most appropriate after a review of theories and cases about deposition. Also, it was reviewed in this article about the necessity of easing strict grounds of deposition, whether to permit partial payment deposition, deposition of real estate, extinctive prescription of deposition, adequacy of deposition interest. In my opinion, it is desirable to ensure the principle of private autonomy considering that deposition is one of methods to settle property right, even though it is necessary to strictly operate the deposition process because of the parental function of the court. Based on this principle, it is right to permit partial payment deposition to comply with the Civil Act, and to permit real estate deposition because there is no prohibition provisions about it. It is necessary to allow the principle of extinctive prescription of deposition considering a property right of the people. Deposition interest rates is much lower, so it infringes property rights of the people. Therefore, it is necessary to rationally raise the interest rate of deposition after research on the break-even point of deposition management. The judicature should change perceptions on the deposit money to actively protect the property right of the people. I hope this article would be helpful in the protection of people’s property rights regarding the deposition money.

Assessment of Radionuclide Deposition on Korean Urban Residential Area

Lee, Joeun,Han, Moon Hee,Kim, Eun Han,Lee, Cheol Woo,Jeong, Hae Sun The Korean Association for Radiation Protection 2020 방사선방어학회지 Vol.45 No.3

Background: An important lesson learned from the Fukushima accident is that the transition to the mid- and long-term phases from the emergency-response phase requires less than a year, which is not very long. It is necessary to know how much radioactive material has been deposited in an urban area to establish mid- and long-term countermeasures after a radioactive accident. Therefore, an urban deposition model that can indicate the site-specific characteristics must be developed. Materials and Methods: In this study, the generalized urban deposition velocity and the subsequent variation in radionuclide contamination were estimated based on the characteristics of the Korean urban environment. Furthermore, the application of the obtained generalized deposition velocity in a hypothetical scenario was investigated. Results and Discussion: The generalized deposition velocities of ¹³⁷Cs, ¹⁰⁶Ru, and ¹³¹I for each residence type were obtained using three-dimensional (3D) modeling. For all residence types, the deposition velocities of ¹³¹I are greater than those of ¹⁰⁶Ru and ¹³⁷Cs. In addition, we calculated the generalized deposition velocities for each residential types. Iodine was the most deposited nuclide during initial deposition. However, the concentration of iodine in urban environment drastically decreases owing to its relatively shorter half-life than ¹⁰⁶Ru and ¹³⁷Cs. Furthermore, the amount of radioactive material deposited in nonresidential areas, especially in parks and schools, is more than that deposited in residential areas. Conclusion: In this study, the generalized urban deposition velocities and the subsequent deposition changes were estimated for the Korean urban environment. The 3D modeling was performed for each type of urban residential area, and the average deposition velocity was obtained and applied to a hypothetical accident. Based on the estimated deposition velocities, the decision-making systems can be improved for responding to radioactive contamination in urban areas. Furthermore, this study can be useful to predict the radiological dose in case of large-scale urban contamination and can support decision-making for long-term measurement after nuclear accident.

Evaluate Dry Deposition Velocity of the Nitrogen Oxides Using Noah-MP Physics Ensemble Simulations for the Dinghushan Forest, Southern China

Qi Zhang,Ming Chang,Shengzhen Zhou,Weihua Chen,Xuemei Wang,Wenhui Liao,Jianing Dai,ZhiYong Wu 한국기상학회 2017 Asia-Pacific Journal of Atmospheric Sciences Vol.53 No.4

There has been a rapid growth of reactive nitrogen (Nr) deposition over the world in the past decades. The Pearl River Delta region is one of the areas with high loading of nitrogen deposition. But there are still large uncertainties in the study of dry deposition because of its complex processes of physical chemistry and vegetation physiology. At present, the forest canopy parameterization scheme used in WRF-Chem model is a single-layer “big leaf” model, and the simulation of radiation transmission and energy balance in forest canopy is not detailed and accurate. Noah-MP land surface model (Noah-MP) is based on the Noah land surface model (Noah LSM) and has multiple parametric options to simulate the energy, momentum, and material interactions of the vegetation-soil-atmosphere system. Therefore, to investigate the improvement of the simulation results of WRF-Chem on the nitrogen deposition in forest area after coupled with Noah-MP model and to reduce the influence of meteorological simulation biases on the dry deposition velocity simulation, a dry deposition single-point model coupled by Noah- MP and the WRF-Chem dry deposition module (WDDM) was used to simulate the deposition velocity (Vd). The model was driven by the micro-meteorological observation of the Dinghushan Forest Ecosystem Location Station. And a series of numerical experiments were carried out to identify the key processes influencing the calculation of dry deposition velocity, and the effects of various surface physical and plant physiological processes on dry deposition were discussed. The model captured the observed Vd well, but still underestimated the Vd. The self-defect of Wesely scheme applied by WDDM, and the inaccuracy of built-in parameters in WDDM and input data for Noah-MP (e.g. LAI) were the key factors that cause the underestimation of Vd. Therefore, future work is needed to improve model mechanisms and parameterization.

경험공식 및 다중회귀모형을 이용한 붕괴 저수지(습지) 비퇴사량 추정

김동현(Kim, Donghyun),이하늘(Lee, Haneul),배영혜(Bae, Younghye),주홍준(Joo, Hongjun),김덕환(Kim, Deokhwan),김형수(Kim, Hung Soo) 한국습지학회 2021 한국습지학회지 Vol.23 No.4

댐 저수지(dam reservoir wetland)나 농업용 저수지 습지(irrigation reservoir wetland) 같은 시설물은 준공되고 시간이 지남에 따라 침식(erosion), 유사이송(sediment transport), 그리고 유사가 침전(sediment deposition)되어 퇴적이발생하게 된다. 장기간 유사가 퇴적되면 홍수 및 가뭄 조절 기능에 영향을 주기 때문에 퇴적 문제는 저수지 습지의유지 관리를 위해 매우 중요하다. 그러나 퇴사에 관한 연구는 가용 자료의 부족으로 인해 주로 경험공식에 의해 추정되어 왔다. 본 연구의 목적은 실측자료 및 경험공식과 더불어 다중회귀모형을 개발하여 비퇴사량(sediment deposition rate)을 산정하고 비교하고자 하였다. 또한, 저수지 습지의 퇴사(reservoir wetland sedimentation) 및 노후화로 인해 2020년 긴 장마에 따른 홍수피해가 발생한 64개소의 저수지 습지에 적용하여 잠재적인 붕괴 원인을 파악하고자 하였다. 대상 저수지는 실측 정보가 있는 한국의 경상남도 밀양시(Miryang city, Gyeongsangnam province) 에 위치한 가곡(GaGog) 저수지 등 10개소를 선정하였다. 저수지 유효저수용량 실측자료를 이용하여 비퇴사량을 산정하였고 기존에 개발된 총 4가지 경험공식과 물리적/기후적 특성 등을 고려한 다중회귀모형을 개발하여 비퇴사량을산정하였다. 비퇴사량 산정 결과, 본 연구에서 개발한 다중회귀모형의 오차가 0.21(㎥ /㎢ / yr)부터 2.13(㎥ /㎢ / yr) 으로 가장 낮았다. 따라서 다중회귀모형에 의해 추정한 비퇴사량을 토대로 저수지 습지의 유효저수용량에 대한 변화를 분석하였는데 유효저수용량이 0.21(%)부터 16.56(%)까지 감소한 것으로 파악되었다. 또한, 월류 피해가 발생한저수지 습지의 비퇴사량은 파이핑 피해 등이 발생한 저수지의 비퇴사량 보다 상대적으로 높았다. 즉, 저수지 바닥에비퇴사량이 축적되면 허용할 수 있는 유효저수용량이 부 As facilities such as dam reservoir wetlands and agricultural irrigation reservoir wetlands are built, sedimentation occurs over time through erosion, sedimentation transport, and sediment deposition. Sedimentation issues are very important for the maintenance of reservoir wetlands because long-term sedimentation of sediments affects flood and drought control functions. However, research on resignation has been estimated mainly by empirical formulas due to the lack of available data. The purpose of this study was to calculate and compare the sediment deposition rate by developing a multiple regression model along with actual data and empirical formulas. In addition, it was attempted to identify potential causes of collapse by applying it to 64 reservoir wetlands that suffered flood damage due to the long rainy season in 2020 due to reservoir wetland sedimentation and aging. For the target reservoir, 10 locations including the GaGog reservoir located in Miryang city, Gyeongsangnam province in South Korea, where there is actual survey information, were selected. A multiple regression model was developed in consideration of physical and climatic characteristics, and a total of four empirical formulas and sediment deposition rate were calculated. Using this, the error of the sediment deposition rate was compared. As a result of calculating the sediment deposition rate using the multiple regression model, the error was the lowest from 0.21(㎥ /㎢ / yr) to 2.13(㎥ /㎢ / yr). Therefore, based on the sediment deposition rate estimated by the multi-regression model, the change in the available capacity of reservoir wetlands was analyzed, and the effective storage capacity was found to have decreased from 0.21(%) to 16.56(%). In addition, the sediment deposition rate of the reservoir where the overflow damage occurred was relatively higher than that of the reservoir where the piping damage occurred. In other words, accumulating sediment deposition rate at the bottom of the reservoir would result in a lack of acceptable effective water capacity and reduced reservoir flood and drought control capabilities, resulting in reservoir collapse damage.

Numerical Simulations of Dry and Wet Deposition over Simplified Terrains

T. Michioka,H. Takimoto,A. Sato 한국대기환경학회 2017 Asian Journal of Atmospheric Environment (AJAE) Vol.11 No.4

To evaluate the deposition amount on a ground surface, mesoscale numerical models coupled with atmospheric chemistry are widely used for larger horizontal domains ranging from a few to several hundreds of kilometers; however, these models are rarely applied to high-resolution simulations. In this study, the performance of a dry and wet deposition model is investigated to estimate the amount of deposition via computational fluid dynamics (CFD) models with high grid resolution. Reynolds-averaged Navier-Stokes (RANS) simulations are implemented for a cone and a two-dimensional ridge to estimate the dry deposition rate, and a constant deposition velocity is used to obtain the dry deposition flux. The results show that the dry deposition rate of RANS generally corresponds to that observed in wind-tunnel experiments. For the wet deposition model, the transport equation of a new scalar concentration scavenged by rain droplets is developed and used instead of the scalar concentration scavenged by raindrops falling to the ground surface just below the scavenging point, which is normally used in mesoscale numerical models. A sensitivity analysis of the proposed wet deposition procedure is implemented. The result indicates the applicability of RANS for high-resolution grids considering the effect of terrains on the wet deposition.

Genetic, management, and nutritional factors affecting intramuscular fat deposition in beef cattle - A review

Park, Seung Ju,Beak, Seok-Hyeon,Jung, Da Jin Sol,Kim, Sang Yeob,Jeong, In Hyuk,Piao, Min Yu,Kang, Hyeok Joong,Fassah, Dilla Mareistia,Na, Sang Weon,Yoo, Seon Pil,Baik, Myunggi Asian Australasian Association of Animal Productio 2018 Animal Bioscience Vol.31 No.7

Intramuscular fat (IMF) content in skeletal muscle including the longissimus dorsi muscle (LM), also known as marbling fat, is one of the most important factors determining beef quality in several countries including Korea, Japan, Australia, and the United States. Genetics and breed, management, and nutrition affect IMF deposition. Japanese Black cattle breed has the highest IMF content in the world, and Korean cattle (also called Hanwoo) the second highest. Here, we review results of research on genetic factors (breed and sex differences and heritability) that affect IMF deposition. Cattle management factors are also important for IMF deposition. Castration of bulls increases IMF deposition in most cattle breeds. The effects of several management factors, including weaning age, castration, slaughter weight and age, and environmental conditions on IMF deposition are also reviewed. Nutritional factors, including fat metabolism, digestion and absorption of feed, glucose/starch availability, and vitamin A, D, and C levels are important for IMF deposition. Manipulating IMF deposition through developmental programming via metabolic imprinting is a recently proposed nutritional method to change potential IMF deposition during the fetal and neonatal periods in rodents and domestic animals. Application of fetal nutritional programming to increase IMF deposition of progeny in later life is reviewed. The coordination of several factors affects IMF deposition. Thus, a combination of several strategies may be needed to manipulate IMF deposition, depending on the consumer's beef preference. In particular, stage-specific feeding programs with concentrate-based diets developed by Japan and Korea are described in this article.