안정성을 고려한 미디언 형 예측기

서정우,송종관 慶星大學校 1998 論文集 Vol.19 No.2

The subset averaged midian(SAM) predictors are applied to the differential pulse code modulation(DPCM) coding of images. It is observed that DPCM systems with SAM predictors can isolate, not propagate, transmission errors in reconstructing input signals at the receiver. A condition which guarantees the stability of a DPCM decoder with the SAM predictor is derived. We design SAM predictors minimizing the prediction error variance under the constraints that guarantees both the decoder stability and the channel error isolation characteristics.

Poster Session : PS 0970 ; Endoscopic Nested Y-Shaped Self-Expanding Metal Stent Placement for Advanced Hilar Cholangiocarcinoma: A Study of a Novel Stent with a Unique Mesh Structure

( Jongkwan Jung ),( Kyo Sang Yoo ),( Dongsoo Han ),( Changsoo Eun ),( Youngouk Ro ),( Sunmin Kim ),( Yeongjae Byeon ),( Jiyeon Kim ) 대한내과학회 2014 대한내과학회 추계학술대회 Vol.2014 No.1

Background: Hilar malignant biliary obstruction poses particular challenges for endoscopists. Although endoscopic placement of SEMS is generally accepted as a palliative treatment in unresectable hilar cholangiocarcinoma, endoscopic placement of SEMS has been considered very diffi cult and complex. The aim of this study was to evaluate the technical and clinical effi cacy of endoscopic placement of a newly designed SEMS with a nested Y-shaped confi guration for hilar malignant biliary obstruction. Methods: 39 patients were enrolled for this study. The used SEMS was a newly designed self-expandable nitinol stent with a nested Y-shaped configuration. Due to the unique mesh structure, it has superior widening center section with cross mesh structure between both end sections with hook and cross structure. The stents were placed with a nested technique. The 2nd uncoated SEMS was then deployed along the guidewire access through the interstices of the fi rst SEMS. Technical & functional success, early complications, and clinical outcome were evaluated. Results: Technical success was achieved in 32 patients. Mean procedure time was 26.6±10.0 minutes. All patients with successful placement of the stents showed a signifi cant decrease in serum bilirubin level. There was neither any early complication nor procedure-related mortality. Late complication occurred in 7 patients, and all of them were related to stent occlusion from tumor ingrowth. In case with stent occlusion, revision with additional metal stents in 2 cases, placement of plastic stents in 2 cases and PTBD in 4 cases. The mean stent patency period was 130 days. Conclusions: Endoscopic placement of a newly designed SEMS with a nested Y-shaped confi guration is easy, safe, and reasonably effective in achieving bilateral drainage of malignant biliary hilar obstruction.

Evaluation of fouling in nanofiltration for desalination using a resistance-in-series model and optical coherence tomography

Park, Jongkwan,Lee, Sungyun,You, Jeongyeop,Park, Sanghun,Ahn, Yujin,Jung, Woonggyu,Cho, Kyung Hwa Elsevier 2018 The Science of the total environment Vol.642 No.-

<P><B>Abstract</B></P> <P>Resistance-in-series models have been applied to investigate fouling behavior. However, it is difficult to model the influence of morphology on fouling behavior because resistance is indirectly calculated from the water flux and transmembrane pressure. In this study, optical coherence tomography (OCT) was applied to evaluate the resistance of the fouling layer based on fouling morphology. Sodium alginate, humic acid, and bovine serum albumin (BSA) with high salts concentrations (conductivity: 23 mS/cm) were used as model foulants. At the same total fouling resistance, BSA showed the highest cake layer thickness (BSA (114.5 μm) > humic acid (53.5 μm) > sodium alginate (20.0 μm)). However, a different order was found for the cake layer resistance (BSA > sodium alginate > humic acid). This indicates that fouling thickness is not correlated with cake layer resistance. According to the Carman–Kozeny equation, fouling layer porosity decreased in the following order: humic acid (0.30) > BSA (0.21) > sodium alginate (0.20). In addition, we provided a specific value that was calculated using the ratio between the fouling thickness and cake layer resistance. The results show that alginic acid induced a stronger cake layer resistance, despite its thin fouling layer, whereas BSA showed a relatively low potential for inducing cake layer resistance. The results obtained in this study could be used for estimating and predicting fouling behavior.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Property of fouling layer was investigated by the membrane resistance value and fouling thickness. </LI> <LI> Humic acid, sodium alginate, and BSA fouling layers in brackish water were visualized via OCT. </LI> <LI> Gel/cake layer and adsorbed/pore blocking fouling types were distinguished by 2D OCT images. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

자동차 공조기의 오일량과 냉매충진량에 따른 성능평가

선종관(Jongkwan Sun),채수남(Sunam Chae),정동수(Dongsoo Jung) 대한설비공학회 2001 대한설비공학회 학술발표대회논문집 Vol.2001 No.-

응답스펙트럼해석을 통한 경사말뚝이 설치된 잔교식 안벽의 내진성능 평가

윤정원(Yun, Jung-Won),한진태(Han, Jin-Tae),김종관(Kim, JongKwan) 한국지반공학회 2021 한국지반공학회논문집 Vol.37 No.12

Evaluating the effects of organic matter bioavailability on nanofiltration membrane using real-time monitoring

Park, Sanghun,You, Jeongyeop,Ahn, Yujin,Jung, Woonggyu,Kim, Jihye,Lee, Sungyun,Park, Jongkwan,Cho, Kyung Hwa Elsevier 2018 Journal of membrane science Vol.548 No.-

<P><B>Abstract</B></P> <P>We studied the influence of bioavailability of organic matter on membrane fouling layer development by comparing the filtration performance of two feed waters (wetland water and graywater). Dissolved organic carbon (DOC) concentration, size exclusion chromatography (SEC), and fluorescence excitation-emission matrix (FEEM) were used to characterize the bioavailability of organic matter in these water samples during the nanofiltration process. The wetland sample contained a high proportion of humic acid- and fulvic acid-like matter with low bioavailability, whereas the graywater sample comprised substantial amounts of aromatic proteins and microbial byproduct-like matter with high bioavailability. In addition, the molecular size distribution revealed that the wetland sample contained a large portion of recalcitrant organic matter, whereas the graywater sample contained easily bioavailable organic matter. After the filtration experiment, the DOC of the wetland sample decreased to 4.8mgC/L, whereas the graywater sample resulted in a lower DOC concentration of 3.4mgC/L. Optical coherence tomography (OCT) illustrated real-time variations in the fouling layer morphology, providing both 2D and 3D images. In addition, confocal laser scanning microscopy (CLSM) quantified the bacterial volume in the fouling layer. The wetland sample yielded a bacterial volume of 11.8µm<SUP>3</SUP>/μm<SUP>2</SUP> from a total fouling volume of 103µm<SUP>3</SUP>/μm<SUP>2</SUP>, whereas the graywater sample yielded a bacterial volume of 53.2µm<SUP>3</SUP>/μm<SUP>2</SUP> from a total fouling layer volume of 134µm<SUP>3</SUP>/μm<SUP>2</SUP>. Fitting of the two-phase Monod model to the fouling layer growth on the membrane resulted in lower-yield coefficients (i.e., the volumes produced per unit amount of substrate, <SUB> Y xs </SUB> ) of 7.46 and 27.95µm<SUP>3</SUP>/μm<SUP>2</SUP> in wetland water and higher-yield coefficients of 13.17 and 47.53µm<SUP>3</SUP>/μm<SUP>2</SUP> in the graywater at first and second phase, respectively. This study addresses the quantitative evaluation of the organic matter bioavailability in terms of membrane fouling using OCT images and a two-phase Monod model.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The difference of bioavailability of DOM influenced the amount of fouling layer growth. </LI> <LI> In situ OCT monitoring provided 2D and 3D morphology of the fouling layer and quantified the volume. </LI> <LI> Two-phase Monod model evaluated the influence of bioavailability of DOM on fouling layer growth. </LI> </UL> </P>

Arctic Primary Aerosol Production Strongly Influenced by Riverine Organic Matter

Park, Jiyeon,Dall’Osto, Manuel,Park, Kihong,Kim, Jung-Hyun,Park, Jongkwan,Park, Ki-Tae,Hwang, Chung Yeon,Jang, Gwang Il,Gim, Yeontae,Kang, Sujin,Park, Sanghun,Jin, Yong Keun,Yum, Seong Soo,Simó American Chemical Society 2019 Environmental science & technology Vol.53 No.15

<P>The sources of primary and secondary aerosols in the Arctic are still poorly known. A number of surface seawater samples-with varying degrees of Arctic riverine and sea ice influences-were used in a sea spray generation chamber to test them for their potential to produce sea spray aerosols (SSA) and cloud condensation nuclei (CCN). Our interdisciplinary data showed that both sea salt and organic matter (OM) significantly influenced the SSA production. The number concentration of SSA in the coastal samples was negatively correlated with salinity and positively correlated with a number of OM tracers, including dissolved and chromophoric organic carbon (DOC, CDOM), marine microgels and chlorophyll <I>a</I> (Chl-<I>a</I>) but not for viral and bacterial abundances; indicating that OM of riverine origin enhances primary aerosol production. When all samples were considered, transparent exopolymer particles (TEP) were found to be the best indicator correlating positively with the ratio number concentration of SSA/salinity. CCN efficiency was not observed to differ between the SSA from the various samples, despite differences in organic characteristics. It is suggested that the large amount of freshwater from river runoff have a substantial impact on primary aerosols production mechanisms, possibly affecting the cloud radiative forcing.</P> [FIG OMISSION]</BR>