• Journal of Electrical Engineering and Technology
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• v.13 no.4
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• pp.1638-1643
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• 2018

Multi-layer ceramic capacitors as decoupling capacitor were fabricated by dielectric composition with a high dielectric constant. The fabricated decoupling capacitors were embedded in the PCB of the 10G RF transceiver module and evaluated for the characteristics of electrical noise by the level of AC input voltage. In order to further improve the electrical properties of the $BaTiO_3$ based composite, glass frit, MgO, $Y_2O_3$, $Mn_3O$, $V_2O_5$, $BaCO_3$, $SiO_2$, and $Al_2O_3$ were used as additives. The electrical properties of the composites were determined by various amounts of additives and optimum sintering temperature. As a result of the optimized composite, it was possible to obtain a density of $5.77g/cm^3$, a dielectric constant of 1994, and an insulation resistance of $2.91{\times}10^{12}{\Omega}$ at an additive content of 5wt% and a sintering temperature of $1250^{\circ}C$. After forming a $2.5{\mu}m$ green sheet using the doctor blade method, a total of 77 layers were laminated and sintered at $1180^{\circ}C$. A decoupling capacitor with a size of $0.6mm(W){\times}0.3mm(L){\times}0.3mm(T)$ (width, length and thickness, respectively) and a capacitance of 100 nF was embedded using a PCB process for the 10G RF Transceiver modules. In the range of AC input voltage 400mmV @ 500kHz to 2200mV @ 900kHz, the embedded 10G RF Transceiver modules evaluated that it has better electrical performance than the non-embedded modules.

• Korean Journal of Agricultural and Forest Meteorology
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• v.2 no.4
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• pp.167-174
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• 2000

A glass chamber experiment was conducted to evaluate the impact of ozone (O$_3$) on the physiology of two soybean, Glycine max L. cultivars, 'Hwanggum' and 'Jangyub'. Thirty-day old plants with 1-2 nodes were exposed to $O_3$ of <10 and 150 n1 1$^{-1}$ in the chambers for 8 h d$^{-1}$ for 3 days. Net photosynthesis, stomatal conductance, chlorophyll a, chlorophyll b and total chlorophyll contents, and foliar injury (% injured leaves) were measured. Although foliar damage was more severe on Jangyub than on Hwanggum, net photosynthesis was decreased by 60% on Hwanggum and 13% on Jangyub due to the $O_3$ treatment. Stomatal conductance on Jangyub was twice higher than that on Hwanggum and it was not changed by the $O_3$ treatment. Whereas, stomatal conductance on Hwanggum was 60-80% decreased by $O_3$, Chlorophyll contents did not change due to the $O_3$ treatment or variety. We can conclude that the reduction of net photosynthesis by $O_3$ was mainly due to the decreases of stomatal conductance and Rubisco (ribulose-1,5-bisphosphate carboxylase/oxygenase) activity on dark reaction. And foliar injury and chlorophyll content did not contribute to the net photosynthetic decrease. The gas-exchange variables measured 24 h after the termination of $O_3$ fumigation showed that there was no significant recovery within a day. Since the physiological responses on Jangyub were not much affected by the $O_3$ treatment, this variety could be $O_3$ resistant.

• Polymer(Korea)
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• v.24 no.3
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• pp.314-325
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• 2000

Thermal degradation of thermoplasitc polyurethane modified polycarbonate has been investigated by means of DSC, GPC and FT-IR techniques. The polyurethanes used in this study are TPU-35 and TPU-53 containing 35.5 and 53.4 wt% of hard segments, respectively. The more content of hard segment, the higher the glass transition temperature (T$_{g}$) of TPU was observed. On the other hand, the T$_{g}$ of the TPU modified PC decreased with the content of TPU and the annealing temperature regardless of the hard segment contents. The latter behavior nay arise from the thermal degradation of TPU upon annealing process: the observed thermal degradation temperatures were at 240 and 25$0^{\circ}C$ for the PC/TPU-35 and PC/TPU-53, respectively. The molecular weight, molecular weight distribution and viscosity agree well with the DSC measurement, which implicates a thermal degradation of TPU. In addition, thermal stability of the TPU modified PC linearly decreased with an incorporation of TPU. Transesterification or any interaction was not observed using FT-IR: the evidence was no frequency shift or any variance betwere the carbonyl stretching and NH group. For the specimens prepared below the degradation temperature, the enhancement of the thickness dependent impact strength of the PC/TPU blend was observed, and the morphology of the two blends was compared.d.

• Restorative Dentistry and Endodontics
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• v.23 no.1
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• pp.316-327
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• 1998

This study was designed to examine the tissue levels of interleukin-$1{\alpha}$(IL-$1{\alpha}$), interleukin-$1{\beta}$(IL-$1{\beta}$) and tumor necrosis factor-${\alpha}$(TNF-${\alpha}$) in inflamed human dental pulps and periapical lesions, and to determine the relationship between each cytokine and pulpal and periapical pathosis. The pulps used in this experiment, were obtained in routine endodontic treatment and the periapical lesions in periapical surgery after clinical diagnoses were performed. These specimens were divided into four groups as normal pulp group(control group, n=9), acute pulpitis group(n=g), chronic pulpitis group(n= 10) and periapical lesion group(n= 18) and stored in liquid N2. For extract preparation, tissues were finely minced with a scalpel, and the fragments were incubated in $0.5m\ell$ homogenizing buffer (0.1 mol/L potassium chloride, 0.02 mol/L TRIS; pH=7.6) for two hours and grinded with glass homogenizer. Debris was removed by centrifugation and supernatants were immediately tested with enzymelinked immunosorbent assay (ELISA, R&D Co., Minneapolis, USA). Following results were obtained; 1. The concentrations of IL-$1{\alpha}$ in all experimental groups were significantly higher than in control group(p<0.05). And the concentrations of IL-$1{\alpha}$ in periapical lesion group were somewhat higher than in two pulpitis groups, but the differences among those groups were not stastically significant (p>0.05). 2. The concentrations of IL-$1{\beta}$ in all experimental groups were significantly higher than in control group (p<0.05), and all the experimental groups expressed similar concentrations. 3. The concentrations of TNF-${\alpha}$ in all experimental groups were higher than in control group but only the differences between chronic pulpitis group and control group were statistically significant(p<0.05). And the concentrations of TNF-${\alpha}$ in acute and chronic pulpit is groups were higher than in periapical lesion group but only the differences between chronic pulpitis group and periapical lesion group were statistically significant (p<0.05). 4. There was significant correlation only between IL-$1{\alpha}$ and IL-$1{\beta}$ in periapical lesion group (p<0.05).

• Journal of the Korean Applied Science and Technology
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• v.38 no.2
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• pp.476-487
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• 2021

To prepare acrylic resin coatings containing 70% of solids, we used n-butyl methacrylate(BMA), methyl methacrylate(MMA), 2-hydroxyethyl methacrylate(2-HEMA), and acetoacetoxyethyl acrylate(AAEA), caprolactone acrylate(CLA) as raw materials, the glass transition temperature(T_g) of acrylic copolymer was adjusted around 50 ℃. The viscosity and molecular weight of the acrylic resins was increased with increasing OH values. Di-tert-amyl peroxide was found to be the suitable initiator to get high-solids acrylic resins. The optimum reaction conditions found in the study are 5 wt% of initiator, 4 wt% of chain transfer agent, 4 hrs of dropping time, and 140 ℃ of reaction temperature. The structure of the synthesized resins were characterized by FT-IR and ¹H-NMR spectroscopy. Number average molecular weight of 1900~2600 and molecular wight distribution of 1.4~2.1 were obtained. Crosslinked acrylic urethane clear coatings were obtained by curing reaction between the synthesized acrylic resins and hexamethylene diisocyanate trimer(Desmodur N-3300), the equivalent ratio of NCO/OH was 1.2/1.0. The physical properties from the following studies were carried out: viscosity(Zahn cup #2), adhesion, drying time, pot-life, pensil hardness, and 60° specular gloss. Various properties of the acrylic urethane clear coatings were also evaluated on the coating specimens. Adhesion property to a substrate, drying time, pot-life, pencil hardness, and 60° specular gloss of prepared paint showed quite good properties. Futhermore, prepared paint containing 10% of CLA showed quite good properties for adhesion, low viscosity and high hardness.

• Applied Chemistry for Engineering
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• v.34 no.3
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• pp.285-290
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• 2023

Poly-lactic acid (PLA) is the most promising polymer in additive manufacturing as an alternative to acrylonitrile butadiene styrene (ABS). Since it is produced from renewable resources such as corn starch and sugar beets, it is also biocompatible and biodegradable. However, PLA has a couple of issues that limit its use. First, it has a comparatively low glass transition temperature of around 60 ℃, such that it exhibits low thermal resistance. Second, PLA has low impact strength because it is brittle. Due to these problems, scientists have found methods to improve the crystallinity and ductility of PLA. Polyethylene glycol (PEG) is one of the most studied plasticizers for PLA to give it chain mobility. However, the blend of PLA and PEG becomes unstable, and phase separation occurs even at room temperature as PEG is self-crystallized. Thus, it is necessary to investigate the optimal mixing ratio of PLA-PEG at the molecular scale. In this study, molecular dynamics will be conducted with various ratios of L-type PLA (PLLA) or DL-type PLA-PEG (PDLA-PEG) systems by using BIOVIA Materials Studio.

• Safety and Health at Work
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• v.14 no.2
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• pp.141-152
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• 2023

Objective: We performed a meta-analysis of epidemiological results for the association between occupational exposure as a firefighter and cancer as part of the broader evidence synthesis work of the IARC Monographs program. Methods: A systematic literature search was conducted to identify cohort studies of firefighters followed for cancer incidence and mortality. Studies were evaluated for the influence of key biases on results. Random-effects meta-analysis models were used to estimate the association between ever-employment and duration of employment as a firefighter and risk of 12 selected cancers. The impact of bias was explored in sensitivity analyses. Results: Among the 16 included cancer incidence studies, the estimated meta-rate ratio, 95% confidence interval (CI), and heterogeneity statistic (I²) for ever-employment as a career firefighter compared mostly to general populations were 1.58 (1.14-2.20, 8%) for mesothelioma, 1.16 (1.08-1.26, 0%) for bladder cancer, 1.21 (1.12-1.32, 81%) for prostate cancer, 1.37 (1.03-1.82, 56%) for testicular cancer, 1.19 (1.07-1.32, 37%) for colon cancer, 1.36 (1.15-1.62, 83%) for melanoma, 1.12 (1.01-1.25, 0%) for non-Hodgkin lymphoma, 1.28 (1.02-1.61, 40%) for thyroid cancer, and 1.09 (0.92-1.29, 55%) for kidney cancer. Ever-employment as a firefighter was not positively associated with lung, nervous system, or stomach cancer. Results for mesothelioma and bladder cancer exhibited low heterogeneity and were largely robust across sensitivity analyses. Conclusions: There is epidemiological evidence to support a causal relationship between occupational exposure as a firefighter and certain cancers. Challenges persist in the body of evidence related to the quality of exposure assessment, confounding, and medical surveillance bias.

• Korean Journal of Radiology
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• v.21 no.6
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• pp.736-745
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• 2020

Objective: To identify the initial chest computed tomography (CT) findings and clinical characteristics associated with the course of coronavirus disease 2019 (COVID-19) pneumonia. Materials and Methods: Baseline CT scans and clinical and laboratory data of 72 patients admitted with COVID-19 pneumonia (39 men, 46.2 ± 15.9 years) were retrospectively analyzed. Baseline CT findings including lobar distribution, presence of ground glass opacities, consolidation, linear opacities, and lung severity score were evaluated. The outcome event was recovery with hospital discharge. The time from symptom onset to discharge or the end of follow-up (for those remained hospitalized) was recorded. Data were censored in events such as death or discharge without recovery. Multivariable Cox proportional hazard regression was used to explore the association between initial CT, clinical or laboratory findings, and discharge with recovery, whereby hazard ratio (HR) values < 1 indicated a lower rate of discharge at four weeks and longer time until discharge. Results: Thirty-two patients recovered and were discharged during the study period with a median length of admission of 16 days (range, 9 to 25 days), while the rest remained hospitalized at the end of this study (median, 17.5 days; range, 4 to 27 days). None died during the study period. After controlling for age, onset time, lesion characteristics, number of lung lobes affected, and bilateral involvement, the lung severity score on baseline CT (> 4 vs. ≤ 4 [reference]: adjusted HR = 0.41 [95% confidence interval, CI = 0.18-0.92], p = 0.031) and initial lymphocyte count (reduced vs. normal or elevated [reference]: adjusted HR = 0.14 [95% CI = 0.03-0.60], p = 0.008) were two significant independent factors that influenced recovery and discharge. Conclusion: Lung severity score > 4 and reduced lymphocyte count at initial evaluation were independently associated with a significantly lower rate of recovery and discharge and extended hospitalization in patients admitted for COVID-19 pneumonia.

• Journal of the Microelectronics and Packaging Society
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• v.31 no.3
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• pp.1-9
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• 2024

This paper addresses the significance of Cu/Polymer Hybrid Bonding technology in the advancement of semiconductor packaging. As the demands of the AI era increase, the semiconductor industry is exploring heterogeneous integration packaging technologies to achieve high I/O counts, low power consumption, efficient heat dissipation, multifunctionality, and miniaturization. The conventional Cu/SiO₂ Hybrid Bonding structure faces limitations such as achieving compatibility with CMP processes to attain surface roughness below 1nm and the occurrence of bonding defects due to particles. However, Cu/Polymer Hybrid Bonding technology, utilizing polymers, is gaining attention as a promising alternative to overcome these challenges. This study focuses on the deposition, patterning, and material properties of polymers essential for Cu/Polymer Hybrid Bonding, highlighting the advantages and potential applications of this technology compared to existing methods. Specifically, the use of polymers with low glass transition temperatures (Tg) is discussed for their benefits in low-temperature bonding processes and improved mechanical properties due to their high coefficients of thermal expansion. Furthermore, the study explores surface property modifications of polymers and the enhancement of bonding mechanisms through plasma treatment. This research emphasizes that Cu/Polymer Hybrid Bonding technology can serve as a critical breakthrough in developing high-performance, low-power semiconductor devices within the industry.

• Tuberculosis and Respiratory Diseases
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• v.55 no.1
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• pp.41-58
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• 2003

Background : The resurgence of tuberculosis and the widespread emergence of multidrug-resistant M. tuberculosis have emphasized the importance of rapid and accurate diagnostic procedures. Recently, the oligonucleotide chip has proven to be a useful tool in the rapid diagnosis of infectious diseases. The purpose of this study was to rapidly and accurately detect specific mutations in the rpoB, katG and rpsL genes associated with rifampin, isoniazid and streptomycin resistance in M. tuberculosis, respectively, using a single oligonucleotide chip. Method : For detection of drug-resistance, 7 wild-type and 13 mutant-type probes for rifampin, 2 wild-type and 3 mutant-type probes for isoniazid, and 2 wild-type and 2 mutant-type probes for streptomycin were designed and spotted onto glass slides. Fifty-five cultured samples of M. tuberculosis were amplified by PCR, and then underwent hybridization and scanning. Direct sequencing was done to verify the results from the oligonucleotide chip and to analyze the types of mutations. Result : Thirty-five cases out of 40 rifampin-resistant strains(~88%) had mutations in the rpoB gene. One case had a new mutation(D516F, GAC R TTC) and another known mutation together. Twenty cases out of 42 isoniazid-resistant strains(~50%) had mutations in the katG gene, while 7 cases out of 9 streptomycin-resistant strains(~78%) had mutations in the rpsL gene. From these results, the oligonucleotide chip was confirmed to be able to detect the most frequent mutations from the genes associated with rifampin, isoniazid and streptomycin resistance. The results proved that the drug-resistance detection probes were specific. When the results from the oligonucleotide chip and DNA sequencing were compared, the types of mutations were exactly matched. Conclusion : The diagnostic oligonucleotide chip with mutation specific probes for drug resistance is a very reliable and useful tool for the rapid and accurate diagnosis of drug resistance against rifampin, isoniazid and streptomycin in M. tuberculosis infections.