• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.11 no.4
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• pp.408-413
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• 2018

In this paper, the particle size, bulk density, friction coefficient and angle of repose were measured for the automatic processing of solar salt, which was classified with 5 levels of moisture content (16.5, 13.2, 8.2, 4.9, 3.7%). Average diameter was 1.98~1.60mm according to moisture content, and bulk density increased with increasing moisture content. As a result of measuring the coefficient of dynamic friction, the maximum value was shown in the stainless steel plate according to the material, and ABS plate and acrylic plate were lower in the order. Movement occurred at the moisture content of 8.2% or less, and the empty angle of repose was increased and the filling angle of repose was decreased as the moisture content increased.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.3D
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• pp.413-420
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• 2011

An experiment was conducted to suggest the road pavement material combining wooden chip crushed from little useful roots and branches from logging sites or wood waste from construction sites with urethane resin. For the specimen, the mass ratio of urethane resin to construction wood waste chip/lumber waster chip was set to three different levels of 0.5, 0.75, and 1.0, which was measured, mixed with mixer, and molded; 7 days after, tensile strength test, elasticity test using golf balls and steel balls, permeability coefficient measurement, and flammability test were executed. As the result, the tensile strength of the specimen at the dry state in the air exhibited the range of 0.2-1.1MPa, and there was no change after 7 days of aging. When submerged in water, however, the strength was partially diminished; the diminishing rate was greater for less urethane resin usage, and therefore it appears desirable to set the mass ratio of resin to the wood waste chip over 0.75 to consider the moisture intrusion by precipitation and such. As the result of elasticity test, the GB and SB coefficients of the specimen using wood waste chips and urethane resin were measured to be low at below 20%, exhibiting excellent elasticity as road pavement material. Also, the permeability coefficient was over 0.5mm/sec for specimens of all combinations, exceeding the standard value required after construction for permeable pavement material, and the flammability of wood-type pavement material was evaluated to have no practical issues.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.1
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• pp.77-81
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• 1998

A bacteriological study of sea water in Deukryang Bay was conducted to evaluate sanitary conditions of the bay and compliance of waters with the recommended bacteriological criteria for the designated area of shellfish cultivation. Sea water samples were collected at the established sampling stations (fig. 1) from May 1995 to November 1996. During the study period, coliform group, fecal coliform, classification of coliform group with IMViC reactions and pathogenic vibrios were analyzed. Coliform group and feral coliform MPN's were ranged from $<\;3.0\~4600/100m{\ell}\;and\;<\;30\~1,100/100m{\ell}$, respectively. The bacteriological criteria of sea water in shellfish growing area should be less than 70 per l00ml of sea water for median value of coliform MPN, and below $10\%$ of the samples which contain over than 230 for coliform MPN or over than 43 for fecal coliform MPN, Most of the waters from 26 sampling stations were complied water coliform criteria recommended for designated shellfish growing area. Then, the ratios of the samples with move than 230/10ml of coliform group MPN and more than 43/100ml of fecal coliform MPN were $7.4\%$ and $8.5\%$, respectively. The bacterial density of the sea water was deeply affected by rainfall amount. For example, coliform bacterial counts of sea watery after 48 hours from 93 mm rainfall were $6\~7$ times higher than those of without rainfall. During the study period, infectious bacteria such as Vibrio cholerae, Salmonella sp. an d Shigella sp. were not detected from the samples, but detection ratios of Vibrio parahaemolyticus and Vibrio vulnificus were $15\~20\%$ in summer months.

• Journal of Chitin and Chitosan
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• v.23 no.4
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• pp.285-292
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• 2018

In this study, for the purpose of decomposing food waste, the strain was screened from traditional fermented food and soils. The enzyme activity (protease, amylase, cellulase, lipase) experiment was carried out using the paper disc method in 212 strains isolated from 5% NaCl media. Among them, only the strains having enzyme activity of more than 2 (soil) or more than 4 (traditional fermented food) with the halozone of enzyme activity of 15 mm or more were selected first, and microorganism identification through 16S rRNA sequencing was performed. Finally, were identified such as Bacillus subtilis, Bacillus amyloliquefaciens, Bacillus siamensis, Bacillus licheniformis, Bacillus aquimaris, Bacillus megaterium, Bacillus koreensis, Bacillus stratoshericus, Bacillus aryabhattai, Bacillus safensis, Marinobacter hydrocarbonoclasticus. 11 species of mixed strains were confirmed that the culture time was 24 hours, the incubation temperature was $30^{\circ}C$ and the optimum pH was 7.0. In order to confirm the degree of decomposition of standard food wastes (100 g) by treating 11 kinds of mixed strains (25%), solid content of more than $2000{\mu}m$ was determined to be 103 g for the sterilized water group and 18 g for the mixed strains group. And the rest was decomposed to a size of less than $2000{\mu}m$.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.11
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• pp.144-150
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• 2019

In this study, resistance spot welding was performed using a high tensile steel plate SGAFC 780. The shear tensile strength, fracture profile, nugget diameter, and simulation were compared according to the conditions. After the nugget diameter calibration, the minimum diameter of welding was more than 4.3mm when the welding current was 8kVA or more. At 9kVA and above 10kVA, the minimum nugget diameter of 4.3mm was satisfied. On the other hand, due to the high current and time, the fly phenomenon occurred and the deep indentation remained. An evaluation of the weldability confirmed that there was an interval that was evaluated as weld failure due to the creep phenomenon, which satisfied the tensile shear strength and minimum nugget diameter. On the other hand, areas that have sufficient load bearing capacity even when drift has occurred were also identified. The simulation results show that the error rate was less than 4.2% when comparing the nugget diameter in the simulation and the experimental results in the appropriate weld zone, and confirmed the reliability of the simulation.

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.157-157
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• 2019

This study derived the Flood-Inducing-Rainfall (FIR) and the Flood-Inducing-Runoff (FIRO) from the radar-gage composite data to be used as the basis of the flood warning initiation for the urban area of Seoul. For this, we derived the rainfall depth-duration relationship for the 261 flood events at 239 watersheds during the years 2010 and 2011 based on the 10-minute 1km-1km radar-gauge composite rainfall field. The relationship was further refined by the discrete ranges of the proportion of the flooded area in the watershed (FP) and the coefficient variation of the rainfall time series (CV). Then, the slope of the straight line that contains all data points in the depth-duration relationship plot was determined as the FIR for the specified range of the FP and the CV. Similar methodology was applied to derive the FIRO, which used the runoff depths that were estimated using the NRCS Curve Number method. We found that FIR and FIRO vary at the range of 37mm/hr-63mm/hr and the range of 10mm/hr-42mm/hr, respectively. The large variability was well explained by the FP and the CV: As the FP increases, FIR and FIRO increased too, suggesting that the greater rainfall causes larger flooded area; as the rainfall CV increases, FIR and FIRO decreased, which suggests that the temporally concentrated rainfall requires less total of rainfall to cause the flood in the area. We verified our result against the 21 flood events that occurred for the period of 2012 through 2015 for the same study area. When the 5 percent of the flooded area was tolerated, the ratio of hit-and-miss of the warning system based on the rainfall was 44.2 percent and 9.5 percent, respectively. The ratio of hit-and-miss of the warning system based on the runoff was 67 percent and 4.7 percent, respectively. Lastly, we showed the importance of considering the radar-gauge composite rainfall data as well as rainfall and runoff temporal variability in flood warning system by comparing our results to the ones based on the gauge-only or radar-only rainfall data and to the one that does not account for the temporal variability.

• Journal of Korean Neurosurgical Society
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• v.62 no.4
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• pp.422-431
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• 2019

Objective : In an aging society, the number of patients with symptomatic degenerative spondylolisthesis (DS) is increasing and there is an emerging need for fusion surgery. However, few studies have compared transforaminal lumbar interbody fusion (TLIF) and lateral lumbar interbody fusion (LLIF) for the treatment of patients with DS. The purpose of this study was to investigate the clinical and radiological outcomes between TLIF and LLIF in DS. Methods : We enrolled patients with symptomatic DS at L4-5 who underwent TLIF with open pedicle screw fixation (TLIF group, n=41) or minimally invasive LLIF with percutaneous pedicle screw fixation (LLIF group, n=39) and were followed-up for more than one year. Clinical (visual analog scale and Oswestry disability index) and radiological outcomes (spondylolisthesis rate, segmental sagittal angle [SSA], mean disc height [MDH], intervertebral foramen height [FH], cage subsidence, and fusion rate) were assessed. And we assessed the changes in radiological parameters between the postoperative and the last follow-up periods. Results : Preoperative radiological parameters were not significantly different between the two groups. LLIF was significantly superior to TLIF in immediate postoperative radiological results, including reduction of spondylolisthesis rate (3.8% and 7.2%), increase in MDH (13.9 mm and 10.3 mm) and FH (21.9 mm and 19.4 mm), and correction of SSA ($18.9^{\circ}$ and $15.6^{\circ}$) (p<0.01), and the changes were more stable from the postoperative period to the last follow-up (p<0.01). Cage subsidence was observed significantly less in LLIF (n=6) than TLIF (n=21). Fusion rate was not different between the two groups. The clinical outcomes did not differ significantly at any time point between the two groups. Complications were not statistically significant. However, TLIF showed chronic mechanical problems with screw loosening in four patients and LLIF showed temporary symptoms associated with the surgical approach, such as psoas and ileus muscle symptoms in three and two cases, respectively. Conclusion : LLIF was more effective than TLIF for spondylolisthesis reduction, likely due to the higher profile cage and ligamentotactic effect. In addition, LLIF showed mechanical stability of the reduction level by using a cage with a larger footprint. Therefore, LLIF should be considered a surgical option before TLIF for patients with unstable DS.

• Journal of the Mineralogical Society of Korea
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• v.16 no.4
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• pp.333-339
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• 2003

A new mineral, Zn analogue of rancieite (Chimooite), has been discovered at the Dongnam mine, Korea. It occurs as compact subparallel fine­grained flaky or acicular aggregates in the massive manganese oxide ores which were formed by supergene oxidation of rhodochrosite­sulfide ores in the hydrothermal veins trending NS­N25E and cutting the Pungchon limestone of the Cambrian age. The flakes of chimooite are 0.2 mm for the largest one, but usually less than 0.05 mm. The acicular crystals are elongated parallel to and flattened on (001). This mineral shows gradation to rancieite constituting its marginal part, thus both minerals are found in one and the same flake. Color is bluish black, with dull luster and brown streak in globular or massive aggregates. Cleavage is perfect in one direction. The hardness ranges from 2.5 to 4. Under reflected light it is anisotropic and bireflectant. It shows reddish brown internal reflection. Chemical analyses of different parts of both minerals suggest that rancieite and chimooite constitute a continuous solid solution series by cationic substitution. The empirical chemical formula for chimooite has been calculated following the general formula, $R_2_{x}$ M $n^{4+}$$_{9­x}$ $O_{18}$ $.$n$H_2O$ for the 7 $\AA$ phyllomanganate minerals, where x varies from 0.81 to 1.28 in so far studied samples, thus averaging to 1.0. Therefore, the formula of Zn­rancieite is close to the well­known strochiometric formula $_Mn_4^{4+}$ $O_{9}$ $.$4$H_2O$. The mineral has the formula (Z $n_{0.78}$N $a_{0.15}$C $a_{0.08}$M $g_{0.01}$ $K_{0.01}$)(M $n^{4+}$$_{3.98}$F $e^{3+}$$_{0.02}$)$_{4.00}$ $O_{9}$ $.$3.85$H_2O$, thus the ideal formula is (Zn,Ca)M $n^{4+}$$_4$ $O_{9}$ $.$3.85$H_2O$. The mineral has a hexagonal unit ceil with a=2.840 $\AA$ c=7.486 $\AA$ and a : c = 1 : 2.636. The DTA curve shows endothermic peaks at 65, 180, 690 and 102$0^{\circ}C$. The IR absorption spectrum shows absorption bands at 445, 500, 1630 and 3400 c $m^{1}$. The mineral name Chimooite has been named in honour of late Prof, Chi Moo Son of Seoul National University.ity.versity.ity.y.

• Tuberculosis and Respiratory Diseases
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• v.43 no.2
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• pp.190-200
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• 1996

Background : Mechanical ventilation constitutes the last therapeutic method for acute respiratory failure when oxygen therapy and medical treatment fail to improve the respiratory status of the patient. This invasive ventilation, classically administered by endotracheal intubation or by tracheostomy, is associated with significant mortality and morbidity. Consequently, any less invasive method able to avoid the use of endotracheal ventilation would appear to be useful in high risk patient. Over recent years, the efficacy of nasal mask ventilation has been demonstrated in the treatment of chronic restrictive respiratory failure, particularly in patients with neuromuscular diseases. More recently, this method has been successfully used in the treatment of acute respiratory failure due to parenchymal disease. Method : We assessed the efficacy of Bilevel positive airway pressure(BiPAP) in the treatment of acute exacerbation of chronic obstructive pulmonary disease(COPD). This study prospectively evaluated the clinical effectiveness of a treatment schedule with positive pressure ventilation via nasal mask(Respironics BiPAP device) in 22 patients with acute exacerbations of COPD. Eleven patients with acute exacerbations of COPD were treated with nasal pressure support ventilation delivered via a nasal ventilatory support system plus standard treatment for 3 consecutive days. An additional 11 control patients were treated only with standard treatment. The standard treatment consisted of medical and oxygen therapy. The nasal BiPAP was delivered by a pressure support ventilator in spontaneous timed mode and at an inspiratory positive airway pressure $6-8cmH_2O$ and an expiratory positive airway pressure $3-4cmH_2O$. Patients were evaluated with physical examination(respiratory rate), modified Borg scale and arterial blood gas before and after the acute therapeutic intervention. Results : Pretreatment and after 3 days of treatment, mean $PaO_2$ was 56.3mmHg and 79.1mmHg (p<0.05) in BiPAP group and 56.9mmHg and 70.2mmHg (p<0.05) in conventional treatment (CT) group and $PaCO_2$ was 63.9mmHg and 56.9mmHg (p<0.05) in BiPAP group and 53mmHg and 52.8mmHg in CT group respectively. pH was 7.36 and 7.41 (p<0.05) in BiPAP group and 7.37 and 7.38 in cr group respectively. Pretreatment and after treatment, mean respiratory rate was 28 and 23 beats/min in BiPAP group and 25 and 20 beats/min in CT group respectively. Borg scale was 7.6 and 4.7 in BiPAP group and 6.4 and 3.8 in CT group respectively. There were significant differences between the two groups in changes of mean $PaO_2$, $PaCO_2$ and pH respectively. Conclusion: We conclude that short-term nasal pressure-support ventilation delivered via nasal BiPAP in the treatment of acute exacerbation of COPD, is an efficient mode of assisted ventilation for improving blood gas values and dyspnea sensation and may reduce the need for endotracheal intubation with mechanical ventilation.

• The Journal of Korean Society for Radiation Therapy
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• v.27 no.2
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• pp.175-181
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• 2015

Purpose : To evaluate Contralateral Breast Doses with Supine and Prone Positions for tangential Irradiation techniques for left-sided breast Cancer Materials and Methods : We performed measurements for contralateral doses using Human Phantom at each other three plans (conventional technique, Field-in-Field, IMRT, with prescription of 50 Gy/25fx). For the measurement of contralateral doses we used Glass dosimeters on the 4 points of Human Phantom surface (0 mm, 10 mm, 30 mm, 50 mm). For the position check at every measurements, we had taken portal images using EPID and denoted the incident points on the human phantom for checking the constancy of incident points. Results : The contralateral doses in supine position showed a little higher doses than those in prone position. In the planning study, contralateral doses in the prone position increased mean doses of 1.2% to 1.8% at each positions while those in the supine positions showed mean dose decreases of 0.8% to 0.9%. The measurements using glass dosimeters resulted in dose increases (mean: 2.7%, maximum: 4% of the prescribed dose) in the prone position. In addition, the delivery techniques of Field-in-field and IMRT showed mean doses of 3% higher than conventional technique. Conclusion : We evaluated contralateral breast doses depending on different positions of supine and prone for tangential irradiations. For the phantom simulation of set-up variation effects on contralateral dose evaluation, although we used humanoid phantom for planning and measurements comparisons, it would be more or less worse set-up constancy in a real patient. Therefore, more careful selection of determination of patient set-up for the breast tangential irradiation, especially in the left-sided breast, should be considered for unwanted dose increases to left lung and heart. In conclusion, intensive patient monitoring and improved patient set-up verification efforts should be necessary for the application of prone position for tangential irradiation of left-sided breast cancer.