간이 수소 품질 검사의 분석 오차 감소를 위한 절차

남웅식(Woong-Sik Nam),신국선(Kook-sun Shin),민경석(Kyung-Seok Min) 한국가스학회 2023 한국가스학회 학술대회논문집 Vol.2023 No.5

Continuous erythrocyte removal and leukocyte separation from whole blood based on viscoelastic cell focusing and the margination phenomenon

Nam, Jeonghun,Yoon, Jung,Kim, Jeeyong,Jang, Woong Sik,Lim, Chae Seung Elsevier 2019 Journal of chromatography A Vol.1595 No.-

<P><B>Abstract</B></P> <P>The removal of erythrocytes from whole blood is an essential step during sample preparations intended for biomedical analyses and clinical diagnoses. To address the limitations of present methods, such as centrifugation and chemical lysis, we propose a novel microfluidic device for erythrocyte removal with high-efficiency and leukocyte separation from bulk flows of highly concentrated erythrocytes using a viscoelastic non-Newtonian fluid. The proposed device is designed based on the principle of viscoelasticity-induced particle migration toward the center of the microchannel. In addition, we based the functionality of our device on a bio-inspired phenomenon known as margination according to which erythrocytes migrate to the axial center of blood vessels. Fluorescent particles (10 μm) were added to blood suspensions of various concentrations (hematocrit) of erythrocytes in viscoelastic polymer solutions. Optimal hematocrit and flow rate conditions were determined for erythrocyte removal and for the separation of 10 μm particles. We also demonstrated the capability of our device to separate leukocytes with high efficiency (˜94%) and with a high-enrichment factor (10-fold).</P> <P><B>Highlights</B></P> <P> <UL> <LI> Continuous leukocyte separation from high-hematocrit blood sample is proposed. </LI> <LI> Effect of in vivo-margination and viscoelastic lateral migration is used. </LI> <LI> From the blood sample with 25% hematocrit, leukocytes were successfully separated. </LI> <LI> Our device could achieve 94% of separation efficiency and 10-fold enrichment. </LI> </UL> </P>

The Role of Radiation Therapy on Local Recurrence of Rectal Cancer

Woong Ki Chung,Sung Ja Ahn,Taek Keun Nam,Byung Sik Nah,Young Jin Kim 대한방사선종양학회 1992 Radiation Oncology Journal Vol.10 No.2

Ninety five patients of rectal cancer treated with surgery with or without adjuvant radiation therapy since January 1982 to December 1990 at the Chonnam University Hospital were analysed retrospectively regarding local failure. Of these 95 patients 72 patients were treated with surgery alone and remaining 23 patients received postoperative radiation therapy to pelvis. There were 45 men and 50 women with 53 years of median age. Minimum follow-up period was 19 months and median was 47 months (range, 19-125 months). Kaplan-Meier method was used to calculate actuarial risk of local recurrence and survival rate. Comparison between two groups was evaluated by Log rank test. Of total 95 patients twenty seven patients (28.4%) developed local recurrence and 13 patients (17.3%) developed local and distant metastasis concomitantly. Eighty nine percent (24/27) of patients developed local recurrence within 24 months. Pelvic organ adjacent to the primary tumor area was the most common site of initial local recurrence. Of 72 patients treated with surgery alone local recurrence developed in 24 patients. Of 17 patients with stage A and B1(Gunderson - Sosin modification of Dukes' staging system) 6 patients experienced local recurrence (31.2%). The local recurrence rate of B2 and B3 group was 29.9% (7/33) and that of C2 and C3 was 54.7% (11/19), respectively. There was statistically significant difference between two groups (p<0.05). Of 23 patients treated with definitive surgery and radiation therapy 10% (1/10) recurred in B2 and B3 patients. This was slightly lower than C2 and C3 patients (22.2%, 2/10) of similar policy, but revealed no statistically significant difference (p>0.05). In the patients of B2+3 local failure rate decreased when radiation therapy was added (29.9%) vs 10%, p>0.05) and also similar results in C2+3 group (34.7% vs 22.2%, p<0.05). The local failure rate in relation to distance from the anal verge had verge had no statistically significant difference.

Assessment of tumor regression by consecutive pelvic magnetic resonance imaging and dose modification during high-dose-rate brachytherapy for carcinoma of the uterine cervix.

Nam, Taek-Keun,Nah, Byung-Sik,Choi, Ho-Sun,Chung, Woong-Ki,Ahn, Sung-Ja,Kim, Seok-Mo,Song, Ju-Young,Yoon, Mi-Seon The Korean Cancer Association 2005 Cancer Research and Treatment Vol.37 No.3

<P>To assess tumor regression, as determined by pelvic magnetic resonance imaging (MRI), and evaluate the efficacies and toxicities of the interim brachytherapy (BT) modification method, according to tumor regression during multi-fractionated high-dose-rate (HDR) BT for uterine cervical cancer.</P>

과립세포성 육종(Granulocytic Sarcolma) 8례에 관한 임상적 고찰

정남식,박필원,윤진우,한지숙,고윤웅,배혜상,김길영 大韓血液學會 1982 大韓血液學會誌 Vol.17 No.2

Non-electrical powered continuous cell concentration for enumeration of residual white blood cells in WBC-depleted blood using a viscoelastic fluid

Nam, Jeonghun,Jang, Woong Sik,Lim, Chae Seung Elsevier 2019 Talanta Vol.197 No.-

<P><B>Abstract</B></P> <P>White blood cells (WBCs) are one of the critical components whose number has to be reduced before blood transfusion, failing which adverse transfusion effects may occur in patients. However, due to the extremely low concentration of residual WBCs (r-WBCs) in WBC-depleted blood, it is difficult to quantify r-WBCs accurately without using expensive and voluminous instruments. Therefore, the development of a continuous cell concentration technique is required to produce a countable number of cells from rare cells, which cannot normally be detected. In this paper, we present a viscoelastic microfluidic device for sheathless, continuous concentration of WBCs. The device performance was evaluated using polystyrene particles with different sizes at various flow rate conditions in a non-Newtonian fluid compared to a Newtonian fluid. Large particles with a blockage ratio higher than 0.1 were tightly focused at the center and collected at the center outlet with a 98% collection ratio. Meanwhile, the viscosity effect of lysed blood samples with various hematocrits was considered. Finally, diluted WBCs with various dilution ratios were concentrated by ~18-fold and continuous concentration of WBCs in lysed blood samples was performed using a non-electrical powered hand pump sprayer. Without using an external power source, center-focused WBCs were collected at the center outlet at approximately 150 μl/min and the final number of WBCs was increased to 1.8 × 10<SUP>4</SUP> cells/ml from undetectable levels.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A viscoelastic microfluidic device for white blood cell concentration is proposed. </LI> <LI> Size-based flow characteristics of particles were examined at different flow rates. </LI> <LI> 10 µm particles were focused at the center and collected with a 98.7% collection ratio. </LI> <LI> White blood cells with various dilution ratios were concentrated by 18-fold. </LI> <LI> Using a non-electrical powered hand pump, white blood cells were concentrated to 1.8 × 10<SUP>4</SUP> cells/ml from undetectable levels. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Micromixing using a conductive liquid-based focused surface acoustic wave (CL-FSAW)

Nam, Jeonghun,Jang, Woong Sik,Lim, Chae Seung Elsevier 2018 Sensors and actuators. B, Chemical Vol.258 No.-

<P><B>Abstract</B></P> <P>Acoustic manipulation of fluids and particles has gained much attention in microfluidics, owing to its advantages of non-invasive manipulation and low power consumption. Microchannel mixing has been limited to diffusion-based mixing, because of low Reynolds number that has a low mixing efficiency. In this study, we firstly introduce a conductive liquid-based focused surface acoustic wave (CL-FSAW) device for mixing. Using the concentrated acoustic force of CL-FSAW, rapid and efficient mixing of deionized water and fluorescent particle suspension was demonstrated in a microfluidic channel. Effects of the applied voltage and the flow rate on the mixing efficiencies were investigated. As the flow rate decreased or the applied voltage increased, the mixing efficiency increased. At 21V, mixing efficiencies were higher than 90% at a flow rate lower than 120μLmin<SUP>−1</SUP>. In addition, our device was applied to silver nanoparticle synthesis at the optimal mixing condition (100μLmin<SUP>−1</SUP> and 21V).</P> <P><B>Highlights</B></P> <P> <UL> <LI> Using the concentrated acoustic force of a conductive liquid-based focused surface acoustic wave (CL-FSAW) device, rapid and efficient mixing can be achieved. </LI> <LI> In the CL-FSAW mixer, high efficiency mixing performance can be achieved (efficiency ∼97%) at a flow rate of <I>Q</I> ≤80μLmin<SUP>−1</SUP> with an applied voltage of 21V. </LI> <LI> For further application, CL-FSAW mixer device was applied to continuous synthesis of monodispersed silver nanoparticles at <I>Q</I> =100μLmin<SUP>−1</SUP> and <I>V</I> =21V. </LI> </UL> </P>

Characteristics of overlooked synchronous gastric epithelial neoplasia after endoscopic submucosal dissection

Nam, Hyeong Seok,Kim, Hyung Wook,Choi, Cheol Woong,Kang, Dae Hwan,Park, Su Bum,Kim, Su Jin,Choi, Jung Sik Wolters Kluwer Health 2018 Medicine Vol.97 No.39

<P><B>Abstract</B></P><P>Since endoscopic submucosal dissection (ESD) has been accepted as the treatment of choice for early gastric cancer (EGC) without risk of lymph node metastasis, synchronous gastric epithelial neoplasia is no longer rare in the clinical practice. Knowledge about the characteristics associated with synchronous gastric epithelial neoplasia is of great importance to prevent delayed diagnosis.</P><P>Between November 2008 and December 2014, a retrospective study was conducted in a single tertiary referral hospital. Consecutive patients who underwent ESD due to EGC or high-grade dysplasia were analyzed to evaluate the incidence of synchronous gastric epithelial neoplasia and the factors associated with synchronous and overlooked synchronous lesions.</P><P>A total of 488 patients were analyzed in this study. Synchronous lesions were found in 59 patients (12.1%) during the mean 37.7 months of follow-up. Among 77 synchronous lesions, 25 lesions (32.4%) were overlooked at the time of initial ESD. Age of ≥ 65 years, moderate to severe endoscopic atrophic gastritis, and elevated morphology of primary lesions were associated with synchronous gastric epithelial neoplasia. An important factor associated with overlooked lesions is the non-elevated morphology of lesions.</P><P>Careful endoscopic examination of the whole stomach is necessary in patients who are older and who have moderate to severe atrophic gastritis and elevated morphology of lesions to prevent delayed diagnosis of synchronous gastric epithelial neoplasia, especially non-elevated lesions.</P>

Ceramide is Involved in $MPP^+-induced$ Cytotoxicity in Human Neuroblastoma Cells

Nam, Eun-Joo,Lee, Hye-Sook,Lee, Young-Jae,Joo, Wan-Seok,Maeng, Sung-Ho,Im, Hye-In,Park, Chan-Woong,Kim, Yong-Sik The Korean Society of Pharmacology 2002 The Korean Journal of Physiology & Pharmacology Vol.6 No.6

To understand the cytotoxic mechanism of $MPP^+,$ we examined the involvement of ceramide in $MPP^+-induced$ cytotoxicity to human neuroblastoma SH-SY5Y cells. When SH-SY5Y cells were exposed to $MPP^+,\;MPP^+$ induced dose-dependent cytotoxicity accompanied by 2-fold elevation of intracellular ceramide levels in SH-SY5Y cells. Three methods were used to test the hypothesis that the elevated intracellular ceramide is related to $MPP^+-induced$ cytotoxicity: $C_2-ceramide$ was directly applied to cells, sphingomyelinase (SMase) was exogenously added, and oleoylethanolamine (OE) was used to inhibit degradation of ceramide. Furthermore, inhibition of ceramide-activated protein phosphatase (CAPP), the effector of ceramide, using okadaic acid (OA) attenuated cell death but treatment of fumonisin $B_1,$ the ceramide synthase inhibitor, did not alter the cytotoxic effect of $MPP^+.$ Based on these, we suggest that the elevation of intracellular ceramide is one of the important mediators in $MPP^+-induced$ cell death.

LOW TEMPERATURE OXIDATION OF CO OVER SUPPORTED PdCl2-CuCl2 CATALYSTS

Nam, In Sik,Koh, Dong Jun,Song, Jae Hwal,Ham, Sung Won,Chang, Rae Woong,Park, Eun Duck,Lee, Jae Sung,Kim, Young Gul 한국화학공학회 1997 Korean Journal of Chemical Engineering Vol.14 No.6

PdCl₂-CuCl₂catalyst supported on activated carbon was examined for the low temperature oxidation of CO. The catalyst developed in the present study was active and stable at ambient conditions if water were existing in the feed gas stream. The addition of Cu(NO₃)₂into the PdCl₂-CuCl₂catalyst significantly enhanced the CO oxidation activity. X-ray diffraction study revealed that the role of Cu(NO₃)₂was to stabilize active Cu(Ⅱ) species, Cu₂Cl(OH)₃, on the catalyst surface which maintains the redox property of palladium. When HCl and SO₂were also existing in the feed, they easily inactivated the catalyst. It was found that HCl and SO₂inhibited the formation of active Cu(Ⅱ) species on the catalyst surface.