• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.3
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• pp.578-584
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• 2017

$SiO_2$ buffer layer (100 nm) has been deposited on PET substrate by electron beam evaporation. And then, IZTO (In-Zn-Sn-O) thin film has been deposited on $SiO_2$/PET substrate with different RF power of 30 to 60 W, working pressure, 1 to 7 mTorr, by RF magnetron sputtering. Structural, electrical and optical properties of IZTO thin film have been analyzed with various RF powers and working pressures. IZTO thin film deposited on the process condition of 50 W and 3 mTorr exhibited the best characteristics, where figure of merit was $4.53{\times}10^{-3}{\Omega}^{-1}$, resistivity, $4.42{\times}10^{-4}{\Omega}-cm$, sheet resistance, $27.63{\Omega}/sq.$, average transmittance (400-800 nm), 81.24%. As a result of AFM, all the IZTO thin film has no defects such as pinhole and crack, and RMS surface roughness was 1.147 nm. Due to these characteristics, IZTO thin film deposited on $SiO_2$/PET structure was found to be a very compatible material that can be applied to the next generation flexible display device.

• YAKHAK HOEJI
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• v.56 no.2
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• pp.136-143
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• 2012

Type 2 Diabetes Mellitus (T2DM) is characterized by high blood glucose in the context of insulin resistance and relative insulin deficiency. Diabetes is often initially managed by increasing exercise and dietary modification. As the condition progresses, medications may be needed such as oral sulfonylurea or others. Recently, dipeptidyl peptidase 4 (DPP- 4) Inhibitor is new drug which can control blood glucose by increasing the active levels of incretin hormone in the body. However, researches have been carried out for mostly Caucasian and Japanese, not for Koreans at all. Therefore, this study was to evaluate the efficacy and safety of DPP-4 inhibitor (Sitagliptin, Vildagliptin) in patients with T2DM in Koreans. This study was carried out retrospectively with reviewing of medical records from the 141 patients who received sitagliptin or vildagliptin over 24 week periods from January 2009, to December 2009. Information including demographics, concomitant medication, disease duration, and exercise was evaluated. $HbA_{1c}$, random blood glucose, post prandial 2 hour glucose, blood pressure, AST, ALT, serum creatinine, total cholesterol, triglyceride levels were also collected at baseline and endpoint (at 24 weeks). In each post-treatment group, $HbA_{1c}$, random blood glucose and post prandial 2 hour glucose levels were decreased significantly from baseline in the sitagliptin group (-0.82%, -28.76 mg/dl, -46.65 mg/dl) and vildagliptin group(-1.22%, -27.96 mg/dl, -67.2 mg/dl). Greater $HbA_{1c}$ mean reductions from baseline to 24 weeks were seen in patients with higher baseline values (>7.0%), with shorter disease durations (${\leq}1$ year) compared with those with lower baseline values (<7.0%), with longer disease durations (>1 year) in both sitagliptin and vildagliptin groups. The incidences of hypoglycemia, headache and upper respiratory infection were 0%, 8.7%, 5.8% in sitagliptin group and 2.8%, 8.3%, 6.9% in vildagliptin group. In conclusion, our results showed DPP-4 inhibitor provided similar efficacy compared with sulfonylurea after 24 weeks of treatment and were safer than sulfonylurea in hypoglycemia for Korean T2DM. Also vildagliptin was associated with significant improvement in $HbA_{1c}$ reduction in Korean patient with subgroup (body mass index<25 $kg/m^2$, metformin dose${\geq}$1000 mg, p<0.05) compared to sitagliptin. Therefore, even though DPP-4 inhibitor use for Korean needs to be studied more consistently in the future, DPP-4 inhibitor is a safe and effective drug for Korean T2DM based on our result.

• Journal of the Korean Vacuum Society
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• v.15 no.4
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• pp.380-386
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• 2006

In this study, we had designed and fabricated the plasma focus device which can generate the light source for EUV(Extreme Ultra Violet) lithography. And we also have investigated the basic electrical characteristics of currents, voltages, resistance and inductance of this system. Voltage and current signals were measured by C-dot and B-dot probe, respectively. We applied various voltages of 1.5, 2, 2.5 and 3 kV to the anode electrode and observed voltages and current signals in accordance with various Ar pressures of 1 mTorr to 100 Torr in diode chamber. It is observed that the peak values of voltage and current signals were measured at 300 mTorr, where the inductance and impedance were also estimated to be 73 nH and $35 m{\Omega}$ respectively. The electron temperature has been shown to be 13000 K at the diode voltage of 2.5 kV and this gas pressure of 300 mTorr. It is also found that the ion density Ni and ionization rate 0 have been shown to be $N_i = 8.25{\times}10^{15}/cc$ and ${\delta}$= 77.8%, respectively by optical emission spectroscopy from assumption of local thermodynamic equilibrium(LTE) plasma.

• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.5
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• pp.9-15
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• 2010

Recently, the high-compressive strength concrete where the use is extending was weak in fire because of spalling that was occurring with rise of internal vapor pressure by high temperature. For preventing spalling of high-strength concrete in fire, Organic fibers have been using in concrete generally. By melting of organic fibers in concrete in fire, the internal moistures of concrete moves quickly to the outside, and so, preventing of spalling of high-strength concrete. But this method will be able to prevent the spalling of high-strength concrete, but makes the decrease of the concrete strength after fire. This study make a comparison between properties of preventing of spalling and remaining compressive strength of concrete using intumescence Alkali-Silicates fire-resistant material and that of concrete with organic fibers. Using organic fibers for preventing of spalling of concrete are P.P and Nylon fibers, and anti-fire intumescence material for protection of concrete surface is alkali-silicate materials. Fire resistance test executed as long as 3 hr under the flame temperature $1,200^{\circ}C$ over. In the case of concrete with P.P fibers, don't occurred the spalling, but the remaining compressive strength will not be able to measure, the concrete using intumescence Alkali-Silicates system fire-resistant material is not only preventing of the spalling but also the remaining compressive strength maintained until the maximum 96%.

• Membrane Journal
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• v.15 no.2
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• pp.147-156
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• 2005

It is well-known that polyethersulfone (PES) has high $CO_2$ selectivity over $N_2\;(or\;CH_4)$ and excellent pressure resistance of $CO_2$ plasticization among muy commercialized engineering plastics[1-4]. Asymmetric PES hollow fiber membranes for flue gas separation were developed by dry-wet spinning technique. The dope solution consists of PES, NMP and acetone. Water and water/NMP mixtures are used in outer and inner coagulants, respectively. Gas permeation rate (i.e., permeance) and $CO_2/N_2$ selectivity were measured with pure gas, respectively and the micro-structure of hollow fiber membranes was characterized by scanning electron microscopy. The effects of polymer concentration, ratio of NMP to acetone, length of air gap, evaporation condition and silicone coating were investigated on the $CO_2/N_2$ separation properties of the hollow fibers. Optimized PES hollow fiber membranes exhibited high permeance of $25\~50$ GPU and $CO_2/N_2$ selectivity of $30\~40$ at room temperature and have the apparent skin layer thickness of about $0.1\;{\mu}m$. The developed PES hollow fiber membranes, would be a good candidate suitable for the flue gas separation process.

• Korean Journal of Social Welfare
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• v.65 no.2
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• pp.255-285
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• 2013

The aim of this study is to demonstrate how Self-Sufficiency Promotion Centers (SSP Centers) run by social movement groups have struggled to defend their voluntary identities in conflict with SSP Centers operated by professional social welfare centers. Since political democratization, social movement groups have been increasing invited to run frontline public welfare agencies in South Korea, and Self-Sufficiency Program is one of the representative policies in which social movement groups have actively partaked. But many critical scholars have warned that such institutionalization of social movements into social welfare system is likely to dampen their voluntary nature and force them to render their hegemonic power to professional social welfare institutions. In contrast to the critical viewpoint, however, this study unveils how social movement-based SSP Centers have strived to tackle the professionalization pressure by deploying various survival strategies at the micro level. Through a historical discourse analysis on the frontline conflicts between social movement-based and social welfare-based SSP Centers, this study contends that social movement groups in Self-Sufficiency Program can still maintain their traditional spirit despite the obvious professionalization phenomenon.

• Biomedical Science Letters
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• v.12 no.4
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• pp.375-383
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• 2006

The physiological responses following stress are different in individual or personality. We performed this study to clarify gender differences in influences of noise stress on physiological factors. 70 healthy subjects, which was divided man (n=30) and woman (n=40) groups, were exposed to 85 decibels of excavator noise for 15 minutes. Cardiac factors such as heart rate (HR), systolic and diastolic blood pressures (SBP and DBP, respectively), and heart rate-systolic pressure product (RPP) were determined. Transcranial Doppler ultrasound (TCD) was used to measure mean blood flow velocity (Vm), pulsatility index (PI), and resistance index (RI) in the middle, anterior and posterior cerebral arteries (MCA, ACA and PCA, respectively) before and during noise exposure. Cortisol level and hematological variables were also measured before (baseline) and immediately after the end of noise exposure. In the both groups HR, SBP, and RPP significantly decreased during noise exposure (P<0.05) but not significantly different between two groups (P>0.05). Vms of three cerebral arteries in man group decreased, whereas Vm of PCA in woman group fell during noise exposure (P<0.05). Vm, PI and RI in MCA and ACA during noise exposure were low in man group compared with woman group (P<0.05). Vm of PCA was low, whereas PI and RI of PCA were high in man group compared with woman group during noise exposure (P<0.05). Total leukocyte and red blood cell (RBC) counts slightly decreased during noise exposure but not significant (P>0.05). Levels in hematological variables decreased but not significant changed following noise exposure. Decreased rate of total leukocyte in man group was higher (P<0.05). Cortisol levels in the both groups decreased immediately after the end of noise exposure, while the decreased rate in man group was greater than that in woman group (p<0.05). These findings indicate that a transient exposure to experimental excavator noise may cause decreased changes in cardiac factors, cerebral hemodynamics and cortisol levels and the changes may be greater in men than in women.

• Journal of Preventive Medicine and Public Health
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• v.41 no.1
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• pp.39-44
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• 2008

Objectives : This study was conducted to investigate the associations of non alcoholic fatty liver with metabolic syndrome and the serum carotenoids. Methods : This study was conducted in a general hospital in South Korea from November, 2004 to August, 2005. The study subjects were 350 sampled persons who were aged from 40 years and older (males : 180, females : 170). They were grouped into the normal, mild and severe groups according to fat accumulation in their livers, as determined by ultrasonography. We analyzed the association between non alcoholic fatty liver and metabolic syndrome by multiple logistic regression analysis and we analyzed the association between non alcoholic fatty liver and the serum carotenoids by a general linear model(ANCOVA). Results : After adjustment for the effect of potential covariates, the prevalence of metabolic syndrome was associated with fat accumulation in the liver (p trend <0.001). If the odds ratio of normal group is 1.00, then that of the mild group is 2.80 (95% C.I=1.17-6.71) and that of the severe group is 7.29 (95% C.I=2.76-19.30). The prevalence of metabolic alterations fitting the criteria of metabolic syndrome, according to the class of fat accumulation in the liver, was significantly increased, except for criteria of high blood pressure, a large waist circumference and low HDL (high density lipoprotein) cholesterol level (p trend <0.001). The level of serum ${\beta}$-carotene was decreased according to the class of fat accumulation in the liver (p trend=0.036), but the levels of serum ${\alpha}$-carotene, lycopene, ${\beta}$-cryptoxanthin and lutein were not decreased. Conclusions : This study shows that non alcoholic fatty liver was associated with metabolic syndrome and with the serum ${\beta}$-carotene level.

• Journal of IKEEE
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• v.11 no.4
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• pp.152-157
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• 2007

AlGaN/GaN high electron mobility transistors (HEMTs) were fabricated and the effect of ${N_2}O$ plasma on the electrical characteristics of the devices was investigated. The HEMT exposed to ${N_2}O$ plasma formed by 40 W of RF power in a chamber with pressure of 20 mTorr at a temperature of $200^{\circ}C$, exhibited a reduction of gate leakage current from 246 nA to 1.2 pA by 10 seconds treatment. The current between the two isolated active regions reduced from 3 uA to 7 nA and the sheet resistance of the active layer was lowered also. The variations of electrical characteristics for HEMT were occurred within a short time expose of 10 seconds and the successive expose did not influence on the improvements of gate leakage characteristics and conductivity of the active region. The reduced leakage current level was not varied by successive $SiO_2$ deposition and its removal. The transconductnace and drain current of AlGaN/GaN HEMTs were increased also by the expose to the ${N_2}O$ plasma.

• Journal of the Korean Geotechnical Society
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• v.27 no.3
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• pp.41-54
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• 2011

The present study analyzes the stability of waterfront quay wall under the combined action of earthquake and tsunami. Adopting the limit equilibrium method, the stability of waterfront quay wall is checked for both the sliding and overturning. Forces due to tsunami are compared with the proposed formula and the 3-D one-field Model for immiscible TWO-Phase flows (TWOPM-3D). Variations of the stability of wall are also proposed by the parametric study including tsunami water height, horizontal seismic acceleration coefficient, internal friction angle of soil, friction angle between the wall and the soil and the pore water pressure ratio. The present study about the stability of wall is also compared with the case when earthquake and tsunami are not considered. As a result, the result of numerical analysis about the tsunami force is similar to that of proposed formula. When earthquake and tsunami are simultaneously considered, the stability of wall in passive case significantly decreases and tsunami forces in active case are affected as a resistance force on the wall and so the stability of wall increases.