• Tribology and Lubricants
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• v.39 no.5
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• pp.197-202
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• 2023

Recently, research on experimental and analytical techniques utilizing microfluidic devices has been pursued. For example, lab-on-a-chip devices that integrate micro-devices onto a single chip for processing small sample quantities have gained significant attention. However, during sample preparation, unnecessary gases can be introduced into the internal channels, thus, impeding device flow and compromising specific function efficiency, including that of analysis and separation. Several methods have been proposed to mitigate this issue, however, many involve cumbersome procedures or suffer from complexities owing to intricate structures. Recently, some approaches have been introduced that utilize hydrophobic device structures to remove gases within channels. In such cases, the permeability of gases passing through the structure becomes a crucial performance factor. In this study, a method involving the deposition and sintering of diluted Ag-ink onto a silicon wafer surface is presented. This is followed by unstructured nano-pattern creation using a Metal Assisted Chemical Etching (MACE) process, which yields a nanostructured surface with unstructured pillar shapes. Subsequently, gas permeability in the spaces formed by these surface structures is investigated. This is achieved by experiments conducted to incorporate a pressure chamber and measure gas permeability. Trends are subsequently analyzed by comparing the results with existing theories. Finally, it can be confirmed that the significance of this study primarily lies in its capability to effectively evaluate gas permeability through unstructured pillar-like nanostructures, thus, providing quantitative values for the appropriate driving pressure and expected gas removal time in practical device operation.

• The Journal of the Korea Contents Association
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• v.14 no.5
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• pp.251-261
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• 2014

Primary percutaneous coronary intervention (PCI) has been found to be superior, in terms of hospital mortality and long-term outcome, compared with thrombolytic therapy in patients with acute myocardial infarction (AMI). However, the clinical benefits of primary PCI have not been precisely evaluated in elderly patients.1,974 patients (Group I: n=1,018, $age{\geq}65years$, $73.8{\pm}5.99years$; Group II: n=956, age<65years, $52.8{\pm}7.96years$) who underwent primary PCI for AMI at Chonnam National University Hospital between 2006 and 2010 were analyzed according to their clinical, angiographic characteristics for hospital and one-year survival. Group I had a higher percentage of women, diabetes mellitus, hypertension, multi-vessel disease and lower prevalence of current smoking, hyperlipidemia, familial history than Group II. Culprit lesions were at the left anterior descending artery, left circumflex artery, right coronary artery and left main artery in 42.8% vs. 45.0%, 34.1% vs. 29.6%, 14.6% vs 14.6, 2.7% vs. 1.6%, respectively (p=0.007). Stent diameter was smaller in group I ($3.17{\pm}0.39$ vs. $3.29{\pm}0.42mm$, p=0.001). In-hospital mortality was higher in group I (8.4 vs. 1.9%, p<0.001). There were significant differences in the rates of major adverse cardiac events between the two groups during one-year clinical follow-up (20.1 vs.14.0%, p<0.001). On multiple logistic regression analysis, systolic blood pressure<100mmHg, serum $creatinine{\geq}1.3mg/dL$, Killip class> I, multivessel disease, left ventricular ejection fraction <40% and cerebro vascular disease were independent predictors of one-year motality in patients over 65 years after PCI.

• The Korean Journal of Blood Transfusion
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• v.24 no.3
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• pp.233-240
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• 2013

Background: A previous history of transfusion has been known to be associated with production of anti-HLA class I antibodies. However, platelet glycoproteins are the main target of idiopathic thrombocytopenic purpura (ITP). The mechanism of antibody production is known to differ significantly between glycoproteins and anti-HLA class I. The aim of this study was to evaluate the clinical significance of anti-HLA class I antibodies in childhood ITP. Methods: Enrollment for the normal control group targeted 48 people who visited Gyeongsang National University Hospital from 1990 to 2010, and 48 young children with ITP. Anti-glycoproteins and anti-HLA class I antibodies were tested using the Modified Antigen Capture Enzyme-linked immunosorbent assay (MACE) kit. Results: The positive rate of anti-HLA antibodies was significantly different [36/39 (92.3%) vs 29/46 (63%)] [ITP group vs normal control group] (P=0.002). The mean positive S/C ratio of anti-HLA antibodies was also significantly different (3.55 vs 1.51) [ITP group vs normal control group] (P=0.0000). The positive rate of anti-HLA did not differ significantly between the transfused group and the non-transfused group [12/12 (100%) vs 24/27 (88%)] [transfused ITP vs non-transfused ITP]. The mean positive S/C ratio of anti-HLA antibodies did not differ significantly between the transfused ITP group and the non-transfused ITP group (4.30 vs 3.25) [transfused ITP vs non-transfused ITP]. Consecutive testing showed that positive rate and positive S/C ratio of anti-HLA antibodies did not change significantly between sampling times in both groups [transfused ITP vs non-transfused ITP] (P=1.00 and P=0.15). Conclusion: Anti-HLA class I antibodies may be involved in childhood ITP. Transfusion did not affect the course of childhood ITP.

• Journal of Chest Surgery
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• v.41 no.2
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• pp.202-209
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• 2008

Background: The introduction of Drug Eluting Stents (DES) decreased the number of patients referred for coronary artery bypass grafting (CABG). The impact of DES on CABG (Step 1) was studied and compared with the 1-year outcome after CABG with DES (Step 2). Material and Method: Surgical results for patients who underwent off-pump CABG (OPCAB) before the introduction of DES(n=298) were compared with those who underwent OPCAB after the introduction of DES (n=288) (Step 1). Postoperative 30-day and 1-year results were also compared between the patients who underwent percutaneous coronary intervention (PCI) using DES (n=220) and those who underwent OPCAB (n=255) (Step 2). Result: Since the introduction of DES, the ratio of CABG versus PCI decreased. In the CABG group, the number of high risk patients such as elderly patients (age 62 vs. 64, p=0.023), those with chronic renal failure (4% vs. 9%, p=0.021), calcification of the ascending aorta (9% vs. 15%, p=0.043), or frequency of urgent or emergent operations (12% vs. 22%, p=0.002) increased. However, there were no differences in the cardiac death and graft patency rates between the two groups (step 1). During the one-year follow up period, the rate of target vessel revascularization (12.3% vs. 2.4%, p<0.001) and major adverse cardiac events (MACE: death, myocardial infarct, TVR) were higher in the DES than the CABG group (13.6% vs 4.3%) (stage 2). Conclusion: Introduction of DES decreased the number of patients referred for surgery, and increased the comorbidity in patients who underwent CABG. DES increased the rate of target vessel revascularization, and the occurrence of MACE during the 1-year follow-up. However, there was no difference in the incidence of myocardial infarction and cardiac death between the two groups.

• Journal of Korean Neurosurgical Society
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• v.30 no.3
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• pp.334-341
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• 2001

Objective : We have currently changed treatment strategies to methotrexate(MTX)-based preirradiation chemotherapy with subsequent planned radiation for the initial therapy of primary central nervous system lymphoma (PCNSL). The aim of this study was to evaluate the results of treating PCNSL with chemotherapy plus radiotherapy (CRT) or radiotherapy(RT) alone. Method and Material : This study involved 10 females and 3 males patients with a mean age of 54.2 years. All patients underwent surgery, open(8 cases) or stereotactic biopsy(5 cases) for histological diagnosis. Eleven tumors were diffuse large B-cell lymphomas. Tumor volume change in the follow-up images and survival time were evaluated in patients treated with CRT and RT alone. In the beginning, two patients received ProMACE-Cytabom chemotherapeutic regimen, but did not complete the course and died of progressive tumor 8 and 9 months after diagnosis, respectively. One patient died at 6 months before chemotherapy. These three were excluded from the survival analysis. Five patients(RT group) completed full courses of cranial irradiation with or without boost. For the current combined modality treatment, high-dose MTXbased chemotherapy(systemic and intrathecal MTX, IV vincristine, and oral procarbazine) followed by whole brain irrdiation to 45Gy to tumor was introduced in 5 patients of CRT group. Result : A complete response was achieved in three of five who received RT only and in all of five who received CRT. All patients in CRT groups are in disease free status at a mean 23 months following therapy. The RT group patients refused any additional salvage therapy at tumor relapse and survived at mean 20 months from diagnosis. The Karnofsky performance status improved in eight of ten patients with treatment. The treatment toxicity included leukoencephalopathy in RT group and severe leukopenia, transient hepatitis, avascular necrosis of femoral head, hearing loss, and amenorrhea in CRT group, respectively. Conclusion : The combined modality therapy of MTX-based chemotherapy plus radiotherapy for PCNSL may enhance tumor response and improve patient survival. The patients who received CRT should be carefully followed up because of the higher risk of treatment-induced late neurotoxicity.

• Journal of the Korean Data and Information Science Society
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• v.25 no.4
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• pp.737-743
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• 2014

This experiment was conducted to compare heterogeneity for the variance in dairy cattle population and to induce homogeneity of variance using 502,228 performance test records of dairy cattle. The estimates of heritability for milk yields, fat yields and protein yields were 0.28, 0.26 and 0.24, respectively and the estimate of average breeding value by birth year was lower in HV (heterogenous variance) model than in animal model, collectively. The average breeding values of milk yields, fat yields and protein yields for 545 sire bulls applicable to the criteria of interbull MACE programme were 453.54kg, 10.75kg and 14.33kg, respectively and when the heterogeneity was adjusted they were 432.06kg, 10.15kg and 13.40kg, respectively, which were lower in all milk traits collectively. In animal model, coefficients of phenotypic correlation between dataset I and II were 0.839 in milk yields, 0.821 in fat yields, and 0.837 in protein yields, while in HV model, they were 0.841 in milk yields, 0.820 in fat yields, and 0.836 in protein yields, showing similar results in 2 models. When compared using animal model and HV model, the regression coefficient for ratio of number of daughters by calving year of milk yields increased from 15.157 to 16.105 and that of fat yields increased from =0.227 to =0.196, but that of protein yields decreased from 0.630 to 0.586.

• Journal of Applied Biological Chemistry
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• v.63 no.1
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• pp.111-116
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• 2020

Total polyphenol contents, flavonoid contents, 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging activities of ethanol extracts of 20 herbal plants (sage, turmeric, mace, bayleaf, fenugreek, oregano, blackpepper, whitepepper, clove, marjoram, cinnamon, coriander, basil, dillseed, mustard, cadamon, thyme, celery, rosemary, cumin) were analyzed for the screening of high flavonoid-containing plant resource. Thyme extract, showing the highest flavonoid content and a high degree of antioxidant activity, was selected as a bioactive cosmetic material. The total polyphenols and flavonoids contents of thyme extracts were measured as 6.90 mg chlorogenic acid equivalent (CAE)/100 g and 1.71 mg naringin equivalent (NE)/100 g, respectively, and DPPH radical scavenging activities was 90%. Among the tested organic solvents, hexane gave the highest extraction yield. Thus hexane was selected as the most suitable solvent for the extraction of thyme. Response surface method was used to obtain optimized extraction conditions for thyme: reaction temperature of 35.9 ℃, raw material to hexane ratio of 1.63:25 (w/v), and reaction time of 192 min. These predicted extraction conditions was validated by a total flavonoid extraction experiment showing a value equivalent to 96.3% of the predicted total flavonoid content. It is expected that the optimized solvent extraction conditions could be used for the production of flavonoid using thyme.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.2
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• pp.90-90
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• 2014

The Immersion Grating Infrared Spectrometer (IGRINS) is the first astronomical spectrograph that uses a silicon immersion grating as its dispersive element. IGRINS fully covers the H and K band atmospheric transmission windows in a single exposure. It is a compact high-resolution cross-dispersion spectrometer whose resolving power R is 40,000. An individual volume phase holographic grating serves as a secondary dispersing element for each of the H and K spectrograph arms. On the 2.7m Harlan J. Smith telescope at the McDonald Observatory, the slit size is $1^{{\prime}{\prime}}{\times}15^{{\prime}{\prime}}$. IGRINS has a plate scale of 0.27" pixel-1 on a $2048{\times}2048$ pixel Teledyne Scientific & Imaging HAWAII-2RG detector with a SIDECAR ASIC cryogenic controller. The instrument includes four subsystems; a calibration unit, an input relay optics module, a slit-viewing camera, and nearly identical H and K spectrograph modules. The use of a silicon immersion grating and a compact white pupil design allows the spectrograph collimated beam size to be 25mm, which permits the entire cryogenic system to be contained in a moderately sized ($0.96m{\times}0.6m{\times}0.38m$) rectangular Dewar. The fabrication and assembly of the optical and mechanical components were completed in 2013. From January to July of this year, we completed the system optical alignment and carried out commissioning observations on three runs to improve the efficiency of the instrument software and hardware. We describe the major design characteristics of the instrument including the system requirements and the technical strategy to meet them. We also present the instrumental performance test results derived from the commissioning runs at the McDonald Observatory.

• Journal of Chest Surgery
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• v.38 no.6 s.251
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• pp.410-414
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• 2005

There are several options for choosing a graft in CABG, we routinely chose LIMA for LAD and great saphenous vein for other target vessels. To evaluate the posoperative graft patency, we have studied the results using a 16 slices multi-detector computed tomography. Material and Method: From 1995 to 2003, 80 CABG patients who did not complain any event of MACE have been examined by 16-MDCT, mostly in an out patient clinic. Result: There were 61 men and 19 women. MDCT was used as early as 7 days to 9 years post-operatively with a median follow-up period of 6.5 years, and mean follow-up peiod of $31.5\pm25.4$ months. Mean age was $58.4\pm12.6$ years old in men and $61.5\pm17.2$ years old in women. 72180 patients received LIMA to LAD, and all other patients received vein grafts for bypass. The target vessel of vein grafts were 8 in LAD, 47 in RCA, 60 in diagonals, and 61 in obtuse marginals. Among them 42 sequential anastomoses were performed. The mean graft number was $3.1\pm1.8$ grafts. 5 year graft patency rate of each grafts was as followings; $93.1\%$ in LIMA to LAD, $94.9\%$ in vein to diagonals, $92.1\%$ in vein to obtuse marginals, and $79.2\%$ in vein to RCA. Sequential grafting showed better graft patency than the isolated grafting $(95.2\%\;vs\;78.7\~95.0\%)$. Conclusion: In this study, CABG with LIMA and saphenous veins showed satisfactory longterm results. 16-MDCT provided good images for follow-up study after CABG. Additionally, as radiologic tools (64-MDCT, MRI) improve more in the future, they can be used for diagnosing preoperative anatomical coronary disease as well as cardiac functions.

• Journal of the Korean Society of Radiology
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• v.13 no.3
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• pp.381-389
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• 2019

Although the development of Drug-eluting stent (DES) improved the ISR significantly more than the Bare metal stent (BMS), the coronary stent restenosis (ISR) treatment still has a high recurrence rate. This study is compared the efficacy of DEB with that of DES implantation in patients with ISR. Among 4,316 patients who underwent coronary stent implantation at the Chonnam National University Hospital between November 2012 and December 2016, 187 patients developed ISR on follow-up coronary angiography ($66.3{\pm}11.0years$, 123 males) were enrolled and divided into two groups according to revascularization method as group I (DEB group; n=127) and group II (DES group; n=60). Primary end point was defined as major adverse cardiac events (MACEs), composite of cardiac death (CD), myocardial infaction (MI), target lesion revascularization (TLR) and stent thrombosis (ST) during two-year follow-up between the two groups. There were no differences in the baseline characteristics and angiographic findings except that prevalence of device length was shorter ($21.1{\pm}5.3$ vs. $25.3{\pm}9.6 mm$, p<0.002) in group I.Two-year MACE were not different in the two groups (8.7%vs.10.0%, p=0.789). The incidences of cardiac death (0%vs.0%, p=1.000), MI (1.6%vs.6.7%, p=0.085), TLR(8.7% vs. 10.0%, p=0.789) and ST (0% vs. 0%, p=1000). DEB demonstrated comparable risk reduction for MACEs compared with DES in patients with ISR during two-year follow-up. DEB might be good alternative for the treatment of ISR in patients with ISR.