• 멤브레인
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• 제29권1호
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• pp.51-60
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• 2019

분리막 소재의 투과도와 선택도 사이의 trade-off 관계로 인해 여전히 많은 연구가 필요하다. 특히 고분자 분리막에 무기물 나노입자가 들어가 있을 때, 기체투과 거동의 학문적 이해는 여전히 부족하다. 따라서 본 연구에서는 분리막 소재로 가장 많이 사용되는 PDMS에 2~5 nm의 기공을 가지고 있으며 직경이 약 5 nm 크기의 aluminosilicate hollow nanoparticles인 allophane을 이용하여 복합매질 분리막을 제조하여 기체투과특성을 연구하였다. 대표적인 분리막 소재인 PDMS에 친수성 allophane, 그리고 나노입자에 undecylenic acid로 표면을 개질한 allophane을 막 내부에 고르게 분산시켜 함량 별로 복합매질 분리막을 제조하였다. 나노입자가 분산된 혼합매질 분리막 내에서 기체의 투과 특성을 파악하고, 이에 따른 기체투과 거동과 나노입자가 가지고 있는 기공의 역할을 평가하고자 하였다. 표면개질된 allophane을 첨가함에 따라 기체 투과도와 산소/질소 그리고 이산화탄소/메탄의 선택도가 동시에 점진적으로 향상되는 결과를 얻었다.

• 대한전기학회논문지:시스템및제어부문D
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• 제49권7호
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• pp.399-406
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• 2000

We propose an nonlinear demodulation algorithm for undersampled multicomponent AM(Amplitude Modulation), FM(Frequency Modulation) and AM-FM signals. First, we derive respectively undersampling frequency of the AM, FM and AM-FM using undersampling scheme, and separate respectively monocomponent signals from multicomponent signals using periodic algebraic separation algorithm. In this case augmented separation matrix is very regular and sparse, it has a special structure. The proposed demodulation algorithm detects respectively message signals of the IA(Instantaneous Amplitude) and IF(Instantaneous Frequency) from descrete monocomponent AM, FM and AM-FM signals with an undersampling frequency to be controllable. Verifying the RMS(Root Mean Squares) errors of the detected signals, we show that the performance is excellent.

• Korea-Australia Rheology Journal
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• 제12권1호
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• pp.77-81
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• 2000

Rheological behavior of thermoset/thermoplastic blends of epoxy/polyethersulphone (PES) was monitored during curing of the epoxy resin. During the isothermal curing of the mixture, a fluctuation in viscosity just before the abrupt viscosity increase was observed. This fluctuation is found to be due to the phase separation of PES from the matrix epoxy resin during the curing. The experimentally observed viscosity fluctuation is simulated with a simple two phase suspension model in terms of the increase in domain size. The viscosity profiles obtained experimentally at different isothermal curing temperatures are in good agreement with the predictions from the simple model taking into account the viscosity change due to the growth of PES domain and the network formation of the epoxy matrix.

• 한국세라믹학회지
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• 제46권3호
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• pp.301-305
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• 2009

The novel carbon coating process for interlayer of fiber reinforced ceramic composites between fiber and matrix was performed by carbonizing phenolic resin solution that coated on fiber surface in $N_2$ atmosphere at $600^{\circ}C$ to improve the strength and fracture toughness of CMC(ceramic matrix composite). 160 nm carbon layer was coated on fiber surface with 5 vol% of phenolic resin solution. Since the process temperature ($600^{\circ}C$) is lower than chemical vapor deposition($900{\sim}1000^{\circ}C$), the strength and toughness could be preserved. Furthermore the coating thickness uniformity was improved to 8% of deviation along the stacking sequence. Therefore, prevention from fiber degradation during coating process and controlling coating thickness uniformity along the preform depth were achieved by coating with phenolic resin carbonizing method.

• 멤브레인
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• 제26권1호
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• pp.38-42
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• 2016

올레핀/파라핀 혼합 기체의 분리를 위한 올레핀 촉진 수송 분리막의 제조를 위해 amide 작용기를 가지며 glassy한 특성을 보이는 polyvinylpyrrolidone (PVP) 고분자를 분리막의 matrix로서 사용하였다. 분리막의 기체 투과 실험은 propylene과 propane 50 : 50의 부피비로 혼합된 기체를 사용하였고, bubble meter와 gas chromatography를 사용해 투과도와 선택도를 측정하였다. 또한 SEM image와 FT-IR을 통해 막의 특성을 조사하였다. 100시간의 장시간 성능 측정 결과 선택도는 약 15, 투과도는 약 1.3 GPU 이상을 각각 유지하였다. 기존의 poly(2-ethyl-2-oxazoline) $(POZ)/AgBF_4/Al(NO_3)_3$ 분리막과 비교함으로써, 고분자 matrix로서의 PVP 특성을 확인하였다.

• Animal Bioscience
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• 제36권3호
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• pp.429-440
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• 2023

Objective: 12-oxo-5Z,8Z,10E,14Z-eicosatetraenoic acid (12-KETE), a metabolite of arachidonic acid, is a strong candidate signal for placenta separation following calf discharge at delivery. In the present study, the effects of 12-KETE on bovine trophoblast cells were investigated to determine its function in the placentome at delivery. Methods: Bovine trophoblast cells derived from blastocysts were used. They were cocultured with or without fibroblasts derived from bovine placentome and/or bovine uterine epithelial cells. 12-KETE was added to the culture medium. Results: Bovine trophoblast cells contained binucleate cells and strongly expressed caudal type homeobox 2 (CDX-2) genes. Addition of 12-KETE to the trophoblast cell colony without feeder cells or that on a fibroblast monolayer induced rapid exfoliation of the colony. After 12-KETE addition, trophoblast cells emitted strong fluorescence caused by the degradation of dye-quenched collagen, indicating that 12-KETE activated matrix metalloproteinase of the trophoblast cells. Exfoliated cell colonies were stained with YOPRO-1, but not propidium iodide (PI). Moreover, DNA fragmentation and Bcl-2 associated X protein (Bax) gene (apoptosis stimulator) upregulation were observed in exfoliated cells, indicating that 12- KETE induced trophoblast cell apoptosis. These results were consistent with previous in vivo observations; however, even a lower concentration of 12-KETE activated trophoblast protease. Meanwhile, fibroblasts derived from the bovine placentome converted arachidonic acid to 12-KETE. Conclusion: These observations indicate that 12-KETE may serve as a signal for placenta separation at delivery.

• Journal of Information Processing Systems
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• 제15권2호
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• pp.359-373
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• 2019

For clustering large-scale data, which cannot be loaded into memory entirely, incremental clustering algorithms are very popular. Usually, these algorithms only concern the within-cluster compactness and ignore the between-cluster separation. In this paper, we propose two incremental fuzzy compactness and separation (FCS) clustering algorithms, Single-Pass FCS (SPFCS) and Online FCS (OFCS), based on a fuzzy scatter matrix. Firstly, we introduce two incremental clustering methods called single-pass and online fuzzy C-means algorithms. Then, we combine these two methods separately with the weighted fuzzy C-means algorithm, so that they can be applied to the FCS algorithm. Afterwards, we optimize the within-cluster matrix and betweencluster matrix simultaneously to obtain the minimum within-cluster distance and maximum between-cluster distance. Finally, large-scale datasets can be well clustered within limited memory. We implemented experiments on some artificial datasets and real datasets separately. And experimental results show that, compared with SPFCM and OFCM, our SPFCS and OFCS are more robust to the value of fuzzy index m and noise.

• 대한기계학회논문집
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• 제17권5호
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• pp.1106-1114
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• 1993

본 연구에서는우수한 섬유강화 고분자복합판의 제조 및 개량을 섬유구조의 분리. 배향의 관점에서 연구한다. 유리섬유매트는 유리섬유를 50mm의 길이로 균일하 게 절단하여 공기중에서 분산시켜 6~7mm두께로 만들고,이 유리섬유매트를 바늘의 종류와 스트레칭 횟수에 따라 니들펀칭하여 유리섬유의 매트구조를 변화시킨다. 유리 섬유의 매트구조 별로 모재와 적층시킨 다음 열압축프레스를 사용하여 1차로 시이트를 제작하고, 이 제작된 시이트를 가열로로 가열하여 2차 고온압축 프레스성형한다. 이 때 섬유와 모재의 분리 및 배향의 상관관계를 나타내는 상관계수를 구하고, 이 계수에 미치는 매트 구조의 영향에 대한 실험결과를 보고한다.

• Journal of Microbiology and Biotechnology
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• 제22권5호
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• pp.654-658
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• 2012

Osteoarthritis (OA) is the most common rheumatic pathology. One of the major objectives of OA research is the development of early diagnostic strategies such as those using proteomic technology. Synovial fluid (SF) in OA patients is a potential source of biomarkers for OA. The efficient and reliable preparation of SF proteomes is a critical step towards biomarker discovery. In this study, we have optimized a pretreatment method for twodimensional gel electrophoresis (2DE) separation of the SF proteome, by enriching low-abundance proteins and simultaneously removing hyaluronic acid, albumin, and IgG. SF samples pretreated using this optimized method were then evaluated by 1DE and 2DE separation followed by immunodetection of cartilage oligomeric matrix protein (COMP), a known OA biomarker, and by the identification of 3 proteins (apolipoprotein, haptoglobin precursor, and fibrinogen D fragment) that are related to joint diseases.

• 한국음향학회지
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• 제31권5호
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• pp.332-339
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• 2012

빔공간 변환(beamspace transform) 기법은 공간 영역의 신호를 입사각 혹은 그 사인함수의 영역으로 변환하는 기법으로, MUSIC과 같은 음원 정위 및 추적(source localization and tracking) 문제나 적응 빔형성(adaptive beamforming)과 같은 문제에서 많이 사용되는 기법이다. 다채널 음원 분리 기법에 사용될 때에는, 음원의 정보 뿐만아니라 해당 음원의 이미지(image)를 재구성하여야 하므로 역변환 기법 또한 중요하다. 본 논문에서는 멀티 채널 음원 분리 기법을 위한 빔공간 변환 기법과 그 역변환 기법에 대하여 고찰하였으며, 특히 빔공간-영역 다채널 비음수 행렬 분해 기법에 적용되었을 때 그 성능에 미치는 영향을 중점적으로 살펴보았다.