• 전력전자학회:학술대회논문집
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• 전력전자학회 2017년도 전력전자학술대회
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• pp.126-127
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• 2017

An accurate State Of Charge (SOC) estimation of battery is the most important technique for Electric Vehicles (EVs) and Energy Storage Systems (ESSs). In this paper a new integrated Unscented Kalman Filter-Particle Filter (UKF-PF) is employed to estimate the SOC of a $LiFePO_4$ battery cell and a significant improvement is obtained as compared to the other methods. The parameters of the battery is modeled by the second order Auto Regressive eXogenous (ARX) model and estimated by using Recursive Least Square (RLS) method to calculate value of each element in the model. The proposed algorithm is established by combining a parameter identification technique using RLS method with ARX model and an SOC estimation technique using UKF-PF.

• 대한의용생체공학회:의공학회지
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• 제25권1호
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• pp.1-4
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• 2004

조직공학은 생명과학, 의학, 공학의 기본개념 및 기술을 바탕으로 생체조직을 대체할 수 있는 인공조직 및 장기를 제작하여 이식함으로써 생체의 기능을 유지, 향상 또는 복원하는 것을 목표로 하는데 여기에 사용되는 기본 재료가 장기나 조직의 형태를 만들도록 돕는 scaffold이다. Scaffold를 만드는데 있어서 Solvent-casting과 Particulate leaching 기법은 다공성 폴리머 scaffold의 제조에서 널리 쓰이는 방법인데 여기 쓰이는 particle에는 소금과 젤라틴 둥이 사용되고 있다. 소금은 얻기가 쉽고 다루기에도 편리하다는 장점 때문에 가장 일반적으로 사용되고 있으며 젤라틴은 소금에 비하여 세포의 초기 접착과 증식에 유리하다는 이유로 최근에 많이 사용되고 있으나 이에 관한 비교실험은 아직 보고 된 바 없다. 본 연구에서는 소금과 젤라틴으로 만들어진 두 가지 scaffold를 비교해 보았으며 그 결과 젤라틴 scaffold가 초기상태의 세포 접합과 증식에 있어서 좋은 결과를 보였고 같은 공극율일 때 공극의 연결 상태가 훨씬 더 우수한 결과를 보였다.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2006년 제4회 한국유체공학학술대회 논문집
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• pp.383-386
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• 2006

In this study, we propose a new fast algorithm for calculating short range forces in molecular dynamics, This algorithm uses a new hierarchical tree data structure which has a high adaptiveness to the particle distribution. It can divide a parent cell into k daughter cells and the tree structure is independent of the coordinate system and particle distribution. We investigated the characteristics and the performance of the tree structure according to k. For parallel computation, we used orthogonal recursive bisection method for domain decomposition to distribute particles to each processor, and the numerical experiments were performed on a 32-node Linux cluster. We compared the performance of the oct-tree and developed new algorithm according to the particle distributions, problem sizes and the number of processors. The comparison was performed sing tree-independent method and the results are independent of computing platform, parallelization, or programming language. It was found that the new algorithm can reduce computing cost for a large problem which has a short search range compared to the computational domain. But there are only small differences in wall-clock time because the proposed algorithm requires much time to construct tree structure than the oct-tree and he performance gain is small compared to the time for single time step calculation.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 춘계학술대회 논문집
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• pp.295-298
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• 2009

Oxygen ionic conductors of CeScSZ electrolyte in SOFC unit cell are applied to anode and cathode as well as electrolyte to have the triple-phase-boundaries of electrochemical reaction, and it is required to decrease the sintering temperature of anode-supported electrolyte by the nanoscale of CeScSZ electrolyte powder. In this report, nanoscale CeScSZ electrolyte powder was synthesized by chemical synthesis method. The particle size, surface area and morphology of the powder were observed by SEM and BET. Thin film electrolyte of under $10{\mu}m$ was fabricated by tape casting using the synthesized CeScSZ electrolyte powder, and ionic conductivity and gas permeability of electrolyte film were evaluated. Finally the SOFC unit cell was fabricated using the anode-supported electrolyte prepared by a tape casting method and co-sintering, in which the active layer, measuring $20{\mu}m$, was introduced in the anode layer to provide a more efficient reaction. Electrochemical evaluations of the SOFC unit cell, including measurements such as power density and impedance, were performed and analyzed.

• 한국컴퓨터그래픽스학회논문지
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• 제23권1호
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• pp.17-24
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• 2017

미시적인 관점에서 물표면 주위에 위치한 물 입자와 공기 입자는 끊임없이 서로 상호작용을 한다. 이러한 상호작용은 대량의 작은 물 입자들이 엷게 흩날리는 상황이 표현되는 폭포나 바다에서 명확하게 나타난다. 즉, 엷게 퍼진 작은 물 입자들로 인해 물과 공기사이의 표면경계가 불분명해지며 이 부분에서 공기와 물 입자간의 상호작용으로 인해 급격한 와류현상이 나타나게 된다. 그러나 기존 입자 기반 물 시뮬레이션에서는 유동에 의해 나타나는 자기와류 (self-trubulent)에만 집중하였고, 자유표면 근처에서 공기에 의해 표현되는 부차적인 와류 현상에 대해서는 고려하지 못했다. 유체표면의 움직임에 집중된 모델링으로 인해 대량의 작은 물 입자들이 엷게 흩날리는 장면을 사실적으로 연출하기에는 한계가 있다. 우리는 1) 물 표면에서 공기의 역할을 담당하는 공기 입자 층을 적응적으로 생성하고, 2) 물과 공기를 서로 다른 상 (phase)으로 모델링하여 자유표면 근처에서 발생하는 와류를 사실적으로 표현하는 기법을 제안한다. 결과적으로, 우리는 공기에 의해 표현되는 와류를 입자기반 프레임워크에서 효율적으로 다루어 계산속도 및 결과측면에서 기존기법보다 개선된 결과를 얻었다.

• 한국전기전자재료학회논문지
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• 제24권8호
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• pp.669-673
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• 2011

The charged particle type display is a kind of the reflectivity type display and shows an image by absorption and reflection of external light source, which has keep an image without additional electric power because of bistability. In this paper, we made a device whose cell gap is $56\;{\mu}m$ and also analyzed driving and memory characteristics by applied driving voltages. As a result, we found that the driving voltage and memory effect depend on q/m(charge to mass ratio) of charged particle. In this case of breakdown voltage, the devices showed degradation of reflectivity and memory effect due to irregular movement of overcharged particles. In addition, contrast ratio of the device varies with memory effect. Thus, we consider that device needs uniform q/m for improvement of electric and optical properties and memory effect.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 춘계학술대회 논문집
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• pp.299-302
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• 2009

Oxygen ionic conductors of YSZ electrolyte in SOFC unit cell are applied to anode and cathode as well as electrolyte to have triple-phase-boundaries(TPB) of electrochemical reaction, and it is required to decrease the sintering temperature of anode-supported electrolyte by the nanoscale of YSZ powder.In this report, nanoscale YSZ powder was synthesized by the chemical co-precipitation method. The particle size, surface area and morphology of the powder were observed by SEM and BET. Thin film electrolyte of under 10㎛ was fabricated by tape casting using the synthesized YSZ powder, and ionic conductivity and gas permiability of electrolyte film were evaluated. Finally, the SOFC unit cell was fabricated using the anode-supported electrolyte prepared by a tape casting method and co-sintering. Electrochemical evauations of the SOFC unit cell, including measurements such as power density and impedance, were performed and analyzed.

• Geomechanics and Engineering
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• 제9권6호
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• pp.815-827
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• 2015

The mechanical behavior of soil and soil-rock mixture is investigated via the discrete element method. A non-overlapping combination method of spheres is used to model convex polyhedron rock blocks of soil-rock mixture in the DEM simulations. The meso-mechanical parameters of soil and soil-rock interface in DEM simulations are obtained from the in-situ tests. Based on the Voronoi cell, a method representing volumtric strain of the sample at the particle scale is proposed. The numerical results indicate that the particle rotation, occlusion, dilatation and self-organizing force chains are a remarkable phenomena of the localization band for the soil and soil-rock mixture samples. The localization band in a soil-rock mixture is wider than that in the soil sample. The current research shows that the 3D discrete element method can effectively simulate the mechanical behavior of soil and soil-rock mixture.

• Archives of Pharmacal Research
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• 제21권5호
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• pp.521-526
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• 1998

The physicochmical properties of recombinant hepatitis B surface antigen (r-HBsAg), which was expressed in C127 mammalian cell were studied. Using roller bottle culture in DMEM supplemented with fetal bovine serum, 10-15 mg/L of r-HBsAg was produced with about 31% of purification yield. The purity of r-HBsAg by HPLC was 99.8% and electron microscopic examination showed homogeneous spherical particle with 22 nm in diameter, a morphological characteristic of HBsAg. The density of r-HBsAg by CsCI density gradient method was 1.19g/ml and the isoelectric point by Mono $P^{TM}$ HR 5/20 column was 4.6. The analysis of subunit protein pattern using SDS-PAGE followed by scanning densitometry gave 81.3% of S protein and 18.7% of pre-S protein. fluorophore-assisted-carbohydrate-electrophoresis analysis showed the relative amount of carbohydrate to protein was 1.7% and it smajr component was N-acetyl glucosamine, which was about 39% of total carbohydrate. The relative amount of lipid to protein determined by vanillin phosphoric acid method was 32.5% and its major component was phospholipid, which was about 70% of total lipid. The physicochemical properties of C127 mammalian cell-derved r-HBsAg are similar to those of p-HBsAg, suggesting that the r-HBsAg can be used in developing a new preventive vaccine against hepatitis B.

• Applied Science and Convergence Technology
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• 제24권6호
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• pp.284-288
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• 2015

Anionic small molecules are hard to penetrate the cell membranes because of their negative charges. Encapsulation of small molecules into liposome particles can provide target specific delivery of them. In our previous study, siRNA could be efficiently encapsulated into liposome particles using an asymmetric preparation method of liposomes. In this study, the same method was applied for encapsulation of small anionic fluorescent chemicals such as calcein and indocyanine green (ICG). More than 90% fluorescent chemicals were encapsulated in the asymmetric liposome particles (ALPs). No intracellular fluorescent signal was observed in the tumor cells treated with the unmodified calcein/ALPs and ICG/ALPs, whereas the surface modification with a cell-penetrating polyarginine peptide (R8 or R12) allows cellular uptake of the ALPs. The results demonstrate that the ALPs encapsulating small anionic drugs will be useful for target-specific delivery after modification of target-specific ligands.