• Korean Chemical Engineering Research
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• v.50 no.6
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• pp.1015-1020
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• 2012

Lignite of low rank coal and petroleum coke of high sulfur content can be high potential energy sources for coal gasification process because of their plentiful supply. The steam gasification of lignite, anthracite, and pet coke has been carried out in both an atmospheric thermobalance reactor and a lab-scale fludized bed reactor (0.02 m i.d. ${\times}$ 0.6 m height). The effects of gasification temperature ($600{\sim}900^{\circ}C$) and partial pressure of steam (0.15~0.95 atm) on the gasification rate and on the heating value of product gas have been investigated. The modified volumetric reaction model was applied to the experimental data to describe the behavior of carbon conversion, and to evaluate kinetic parameters of char gasification. The results shows that higher temperature bring more hydrogen in the product syngas, and thus increased gas heating value. The feed rate of steam is needed to be optimized because an excess steam input would lower the gasification temperature which results in a degradation of fuel quality. The rank of calorific value of the product gas was anthracite > lignite > pet coke. Their obtained calorific value at $900^{\circ}C$ with 95% steam feed were 10.0 > 6.9 > 5.7 $MJ/m^3$. This study indicates that lignite and pet coke has a potential in fuel gas production.

• Journal of the Korean Electrochemical Society
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• v.15 no.3
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• pp.181-189
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• 2012

We developed a new high-yield synthesis method of free-standing germanium nanocrystals (Ge NCs) by means of the gas-phase photolysis of tetramethyl germanium in a closed reactor using an Nd-YAG pulsed laser. Size control (5-100 nm) can be simply achieved using a quenching gas. The $Ge_{1-x}Si_x$ NCs were synthesized by the photolysis of a tetramethyl silicon gas mixture and their composition was controlled by the partial pressure of precursors. The as-grown NCs are sheathed with thin (1-2 nm) carbon layers, and well dispersed to form a stable colloidal solution. Both Ge NC and Ge-RGO hybrids exhibit excellent cycling performance and high capacity of the lithium ion battery (800 and 1100 mAh/g after 50 cycles, respectively) as promising anode materials for the development of high-performance lithium batteries. This novel synthesis method of Ge NCs is expected to contribute to expand their applications in high-performance energy conversion systems.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.23 no.3
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• pp.263-269
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• 2001

Median cleft of the lower lip and/or mandible is a rare congenital anomaly, first mentioned by Couronne in 1819. Monroe(1966), Fujino(1970), Ranta(1984) and Oostrom(1996) conducted comprehensive reviews and list cases in literature. Median cleft varies greatly, from a simple vermilion notch to a complete cleft of the lip involving the tongue, the chin, the mandible, the supporting structures of the median of the neck, and the manubrium sterni. The associated anomalies include ankyloglossia, cleft tongue, neck contraction, heart lesion, absence of hyoid bone, and so on. The etiology of median cleft is unknown. Various possibilities, such as failure of mesodermal penetration into the midline, failure of fusion of mandibular processes, external factors apart from the embryogenic pattern such as pressure, position in utero, circulatory failure caused placental adhesion, diseases in pregnancy, and so on, have been discussed. A 8-year-old girl was referred to the Dept. of Oral & Maxillofacial Surgery, Kyungpook National University Hospital and had been aware of the fact that at birth "she had something wrong with her mouth." Shortly after birth she had been examined by a plastic surgeon and at that time surgical procedure had been performed to release the tongue from the lower jaw and lip at local hospital. On admission, she had a slight notching of lower lip and two fibrous frenum ran from the lip along the ventral surface of the tongue, diastema between her mandibular central incisors, and slightly constricted bifid mandible associated independent movement of the two halves of mandible. The patient had autogenous iliac bone graft to reconstruct the mandibular midline defect. The postoperative result was uneventful. In future, the correction of the soft tissue deformities such as notching of the lower lip and partial ankyloglossia will be required for the esthetic and functional improvement.

• Journal of the Korean Ceramic Society
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• v.33 no.11
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• pp.1260-1266
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• 1996

The effects of SiO2 MnO2 and sintering atmospheres (O2, N2) on the piezoelectric properties and densification behaviors of Pb0.98Cd0.02Zr0.36Ti0.39Ni0.083Nb0.167O3 were investigated. The addition of SiO2 to the system enhanced the rate of densification but supressed the rate of grain growth. On the other hand the addition of MnO2 to the system did not nearly affect the rate of densification but increased slightly the rate of grain growth The densification of Pb0.98Cd0.02Zr0.36Ti0.39Ni0.083Nb0.167O3 containing of SiO2 or MnO2 was promoted with increasing the partial pressure of O2. The relative dielectric constant ($\varepsilon$r) and piezoelectric constant (d33) of Pb0.98Cd0.02Zr0.36Ti0.39Ni0.083Nb0.167O3 containing of SiO2 or MnO2 sintered under O2 atmosphere were higher than under N2 atmosphere. Whereas the mechanical quality factor (Qm) of specimens sintered under O2 atmosphere were lower than under N2 atmosphere. Thus the sintering atmosphere of O2 and N2 in Pb0.98Cd0.02Zr0.36Ti0.39Ni0.083Nb0.167O3 containing of SiO2 or MnO2 acted as donor and acceptor respectively. As the amount of SiO2 increased the relative dielectric constant ($\varepsilon$r) and piezoelectric constant (d33) of Pb0.98Cd0.02Zr0.36Ti0.39Ni0.083Nb0.167O3 but the mechanical quality factor (Qm) did not nearly change, In the case of the addition of MnO2 to the system the relative dielectric constant ($\varepsilon$r) and piezoelectric constant (d33) of Pb0.98Cd0.02Zr0.36Ti0.39Ni0.083Nb0.167O3 sintered under O2 atmosphere decreased rapidly with increasing the amount of MnO2 but they were unchanged with increasing the amount of MnO2 under N2 sintering atmosphere. Therefore the differences of the relative dielect-ric constant ($\varepsilon$r) and piezoelectric constant (d33) due to sintering atmosphere were diminished as the amount of MnO2 increased.

• Tuberculosis and Respiratory Diseases
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• v.81 no.4
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• pp.319-329
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• 2018

Background: Bronchoalveolar lavage (BAL) is a necessary procedure for diagnosis of various lung diseases. High-flow nasal cannula (HFNC) oxygen delivery was recently introduced. This study aimed to investigate the safety and effectiveness of HFNC oxygen supply during BAL procedure in patients with acute respiratory failure (ARF). Methods: Patients who underwent BAL while using HFNC at a partial pressure of oxygen in arterial blood/fraction of inspired oxygen ($PaO_2/FiO_2$; PF) ratio of 300 or below among patients who had been admitted from March 2013 to May 2017 were retrospectively investigated. Results: Thirty-three BAL procedures were confirmed. Their baseline PF ratio was $166.1{\pm}46.7$. $FiO_2$ values before, during, and after BAL were $0.45{\pm}0.12$, $0.74{\pm}0.19$, and $0.57{\pm}0.14$, respectively. Flow (L/min) values before, during, and after BAL were $26.5{\pm}20.3$, $49.0{\pm}7.2$, and $40.8{\pm}14.2$, respectively. Both $FiO_2$ and flow during and after the procedure were significantly different from those before the procedure (both p<0.001). Oxygen saturation levels before, during, and after BAL measured by pulse oximeter were $94.8{\pm}2.9$, $94.6{\pm}3.5$, and $95.2{\pm}2.8%$, respectively. There were no significant differences in oxygen saturation among the three groups. Complications of BAL procedure included transient hypoxemia, hypotension, and fever. However, there was no endotracheal intubation within 24 hours. Baseline PF ratio in "without HFNC" group was significantly higher than that in "with HFNC" group. There were no differences in complications between the two groups. Conclusion: The use of HFNC during BAL procedure in ARF patients was effective and safe. However, there were no significant differences in oxygen saturation level and complications comparing "without HFNC" group in mild ARF. More studies are needed for moderate to severe ARF patients.

• Journal of the Korean Chemical Society
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• v.31 no.5
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• pp.406-412
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• 1987

The electrical conductivities of ${\alpha}-Fe_2O_3$ containing 2.5 and 5.0mol% of cadmium were measured from 300 to $900^{\circ}C$ under oxygen pressures of 10$^{-7}$ to 10$^{-1}$ atmosphere. Plots of log ${\sigma}$ vs. 10$^3$/T show the extrinsic conductivity at oxygen pressure higher than $5{\times}10$^{-2}$atm. The transition points appear at about 550$^{\circ}$C and the activation energies are 1.34 eV for the intrinsic region and 0.50 eV for the extrinsic region on 5mol% Cd-doped ${\alpha}-Fe_2O_3$. The extrinsic conductivity disappears at oxygen partial pressures lower than $5{\times}10$^{-2}$ atm, and the intrinsic conductivity predominates. The electrical conductivities decrease with increasing mol% of cadmium doped. The predominant defect of ${\alpha}-Fe_2O_3$ doped with Cd is believed to be Fe${2+}$ interstitial for the intrinsic, however, oxygen vacancy predominates for the extrinsic region. The electrical conduction mechanisms are proposed and the conduction band model is suggested for the extrinsic region.

• Journal of Plant Biology
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• v.35 no.4
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• pp.317-322
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• 1992

The nitrogen fixation activity and environmental factors of Lespedeza bicli!oy Turcz, forming annual root nodules by symbiotic Rhizobium sp. were analyzed in the field conditions during the growing period. Seasunal changes of $N_2-fixation$ activity showed the maximum value of $120\;\mu\textrm{M}\;C_2_H4{\cdot}noduie\;g\;fw^{-1}{\cdot}hr^{-1}$ during the active growing period (June) and varied significantly depending on the growth phase and environmental factors. The maximum activities were attained at the conditions of pH 7, $30^{\circ}C$ of temperature, 18 Kpa of oxygen partial pressure and inhibited by water stress and nitrogen sources. The habitat soil was weak acidic and poor in nitrogen, phosphorus and organic matter contents. The leaf area ratios and chlorophyll contents were ranged from 442 to $48;\textrm{cm}^2{\cdot}g\;dw^{-1}$ and from 33 to $38\;\mu\textrm{g}\;chI{\cdot}\textrm{cm}^2$. Nitrogen contents in each organ showed the maximum of 46, 19 and $11\;mg{\cdot}g\;dw^{-1}, respectively for leaf, rool and stem in the early period. The highest phosphorus contents were 4.2, 1.2 and $0.6\;mg{\cdot}g\;dw^{-1}$, respectively for leaf. root and stem in early growing period. The allocation ratios of nitrogen quantity showed 60% for leaves and 73% for roots during the active and late growth period, and 22% [or stems in average. The allocalion ralios o[ phosphorus quantity showed 58% for leaves during the most productive period, 70% for roots in the pre-growth stage and 26% for stems in average.verage.

• Tuberculosis and Respiratory Diseases
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• v.81 no.3
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• pp.247-255
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• 2018

Background: Patients with acute respiratory failure secondary to tuberculous destroyed lung (TDL) have a poor prognosis. The aim of the present retrospective study was to develop a mortality prediction model for TDL patients who require mechanical ventilation. Methods: Data from consecutive TDL patients who had received mechanical ventilation at a single university-affiliated tertiary care hospital in Korea were reviewed. Binary logistic regression was used to identify factors predicting intensive care unit (ICU) mortality. A TDL on mechanical Ventilation (TDL-Vent) score was calculated by assigning points to variables according to ${\beta}$ coefficient values. Results: Data from 125 patients were reviewed. A total of 36 patients (29%) died during ICU admission. On the basis of multivariate analysis, the following factors were included in the TDL-Vent score: age ${\geq}65$ years, vasopressor use, and arterial partial pressure of oxygen/fraction of inspired oxygen ratio <180. In a second regression model, a modified score was then calculated by adding brain natriuretic peptide. For TDL-Vent scores 0 to 3, the 60-day mortality rates were 11%, 27%, 30%, and 77%, respectively (p<0.001). For modified TDL-Vent scores 0 to ${\geq}3$, the 60-day mortality rates were 0%, 21%, 33%, and 57%, respectively (p=0.001). For both the TDL-Vent score and the modified TDL-Vent score, the areas under the receiver operating characteristic curve were larger than that of other illness severity scores. Conclusion: The TDL-Vent model identifies TDL patients on mechanical ventilation with a high risk of mortality. Prospective validation studies in larger cohorts are now warranted.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.22 no.3
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• pp.122-126
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• 2012

The properties of Al-doped ZnO (AZO) films were investigated as a function of $H_2/(Ar+H_2)$ gas ratio using an AZO (2 wt% $Al_2O_3$) ceramic target in a radio frequency (RF) magnetron sputtering system. The deposition process was done at $200^{\circ}C$ and in $2{\times}10^{-2}$ Torr working pressure and with various ratios of $H_2/(Ar+H_2)$ gas. During the AZO film deposition process, partial $H_2$ gas affected the AZO film characteristics. The electron resistivity (${\sim}9.21{\times}10^{-4}\;{\Omega}cm$) was lowest and mobility (${\sim}17.8\;cm^2/Vs$) was highest in AZO films when the $H_2/(Ar+H_2)$ gas ratio was 2.5 %. When the $H_2/(Ar+H_2)$ gas ratio was increased above 2.5 %, the electron resistivity increased and mobility decreased with increasing $H_2/(Ar+H_2)$ gas ratio in AZO films. The carrier concentration increased with increasing $H_2/(Ar+H_2)$ gas ratio from 0 % to 7.5 %. This phenomenon was explained by reaction of hydrogen and oxygen and additional formation of oxygen vacancy. The average optical transmission in the visible light wavelength region over 90 % and an orientation of the deposition was [002] orientation for AZO films grown with all $H_2/(Ar+H_2)$ gas ratios.

• Journal of Advanced Marine Engineering and Technology
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• v.41 no.4
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• pp.362-367
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• 2017

This study was conducted to compare the particulate removal efficiency of the developed diesel particulate filter using various measurement methods in a high-speed marine diesel engine. A four-stroke mechanical marine diesel engine is used for the test, which has a maximum output of 403 kW and is coupled to an AC dynamometer to control engine speed and load. The test was conducted based on four steady-state engine operating conditions of E3 engine test cycle for the measurement of PM and soot removal efficiency using partial dilution method considered as gravimetric method and filter smoke number method as light absorption method, respectively. As a result of the removal efficiency measurement according to the application of diesel particulate filter, particulate matter was reduced from 76% to 91% and the soot was reduced by more than 90% while meeting the permissible engine back pressure. From these results, the applicability of diesel particulate filter adopted in high-speed marine diesel engines could be confirmed. In addition, based on the result that the particulate removal efficiency varies with different measurement methods, the necessity of unification of these methods could be identified.