• Journal of Korea Water Resources Association
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• v.41 no.3
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• pp.305-314
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• 2008

Urban sewer systems are designed to operate in open-channel flow regime and energy loss at circular manholes are usually not significant. However, the energy loss at manholes, often exceeding the friction loss of pipes under surcharge flow, is considered as one of the major causes of inundation in urban area. Therefore, it is necessary to analyze the head loss associated with manholes, especially in surcharge flow. Hydraulic experimental apparatus which can be changed the invert type(CASE A, B, C) and step height(CASE I, II, III) was installed for this study. The range of the experimental discharges were from $1.0{\ell}/sec$ to $5.6\;{\ell}/sec$. As the manhole diameter ratio($D_m/D_{in}$) increases, head loss coefficient increases due to strong horizontal swirl motion. Head loss coefficient was maximum because of strong oscillation of water surface when the range of manhole depth ratios($h_m/D_{in}$) were from 1.0 to 1.5. The average head loss coefficients for CASE A, B, and C were 0.45, 0.37, and 0.30, respectively. Accordingly, U-invert is most effective for energy loss reduction at circular manhole. This head loss coefficients could be available to design the urban sewer system with surcharge flow.

• Food Science and Preservation
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• v.22 no.5
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• pp.629-635
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• 2015

The effect of temperature on the quality and characteristics of Valencia oranges were studied during storage at low ($4^{\circ}C$, LT) and room ($20^{\circ}C$, RT) temperature. Hardness decreased beginning on the 10th day of storage, regardless of temperature, and showed a more considerable reduction in the peel than the flesh. The total soluble solids (TSS) and titratable acidity (TA) decreased from the 30th day at LT and the 10th day at RT, but the TSS/TA ratio did not change during storage. The vitamin C content decreased from the 20th day at LT and the 10th day at RT, and the total phenol content decreased from the 10th day of storage. In a sensory evaluation, the scores changed less for taste than for color and flavor during storage. The quality of Valencia oranges under two different temperatures was similar on the 30th day at LT and on the 10th day at RT. The TSS (r = 0.9453) and vitamin C content (r = 0.9104) were highly related to sensory properties. These results suggested that TSS and vitamin C are potential indicators of quality for the selection of Valencia oranges during storage.

• Food Science and Preservation
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• v.24 no.1
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• pp.1-7
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• 2017

This study was conducted to investigate the effects of egg shell calcium treatments on short-term storage of cut Kimchi cabbage. Egg shell ash powder (ESP-2) had the greatest calcium contents. Calcium solubility was greater in citric acid than acetic acid and ascorbic acid. Cut Kimchi cabbages ($3{\times}3cm$) were treated with 0.5%, 1.0%, and 2.0% egg shell powder (ESP-1), and egg shell ash powder (ESP-2), and 0.5% citric acid, put inside polyethylene (PE) bags, and stored at $5^{\circ}C$ for 6 weeks. Weight loss was about 99.85-99.90%, and the ratio was the lowest upon 0.5% ESP-2 treatment (p<0.05). The reduction ratios of soluble solids were 21.3-43.4%, and decreased in the order of 1.0% ESP-2 treatment and 0.5% ESP-1. The $L^*$ values decreased, whereas $a^*$ and $b^*$ values of Hunter colorimetry increased in all treatments. ${\Delta}E$ values were lowest upon 0.5% ESP-2 treatment. 0.5% ESP-2 treatment showed better quality characteristics than other treatments. Thus, egg shell calcium treatments could effectively enhance the shelf-life of cut Kimchi cabbage.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.10 no.3
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• pp.237-242
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• 2016

The major advantage of slip-ring technology in Spiral CT is that it facilitates continuous rotation of the x-ray tube, so that volume data can be acquired from a patient quickly. Not only for such a fast scan, but also for the dose reduction purpose, high signal-to-noise ratio and fast data acquisition system is required. In this study, we have built a multi-channel photodetector and multi-channel data acquisition system for CT application. The detector module consisted of CdWO4 crystal and Si photodiode in 16 channels. For the performance test of the preamplifier stage, both the transimpedance and switched integrator types are optimized for the photodetector modules. Switched integrator showed better noise performance in the limited bandwidth which is suitable for the current CT application. The control sequence for data acquisition and 20 bit ADC is designed with VHDL(Very High Speed Integrated Circuit Hardware Description Language) and implemented on FPGA(Field Programmable Gate Array) chip. Our Si photodiode detector module coupled to CdWO4 crystal showed comparable signal with other commercially available photodiode for CT. Switched integrator type showed higher SNR but narrower bandwidth compared to transimpedance preamplifier. Digital hardware is designed by FPGA, so that the control signal could be redesigned without hardware alteration.

• Korean Journal of Weed Science
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• v.7 no.1
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• pp.52-57
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• 1987

To know the effects of weeding periods (weeding from 12 days, 28 days and 42 days after seeding to harvest, and weeding from seeding to 14 days, 28 days and 42 days after seeding) and growing conditions such as transparent polyethylene film mulch (P.E. mulch) and bare soil on growth and yield of peanuts, "Yeongho-Tangkong" was planted on May 10, 1984. Under P.E. mulch, the number of weeds was higher, but the weed dry weight was lower than in bare soil by the middle of July. Sixty days after seedings, the length of main stems in weedy check plots was longer, but shoot dry weight was lower compared to weed free plot. In the correlation coefficients between weed dry weight and the shoot dry weight of peanut on July 14, the growth retardation of peanuts due to weeds was showed earlier under P.E. mulch than in bare soil. Shoot dry weight, shelling ratio, number of seeds per pod, 100 pod weight, and seed yield were higher under P.E, mulch compared to bare soil. But weed dry weight, length of branches, number of pod bearing branches, number of pods per square meters, and pod yield were similar between P.E. mulch and bare soil. Shoot dry weight of peanuts, length of branches, number of pod bearing branches, number of pods per square meters, pod yield, 100 pod weight, 100 seed weight, and seed yield in weed free plots from 28 days after seeding to harvest (28 DAS-Harvest) were higher compared to weed free plots from 42 DAS-Harvest. However, in the weed free plot from seeding to 42 days after seeding seed yield was lower than that of the continuous weeding plot due to lower number of pod bearing branches and number of pods per square meters. When weed was not controlled at the later growth stages of peanuts, reduction in seed yield due to weeds was greater in bare soil than that under P.E. mulch.

• Journal of the Korea Institute of Building Construction
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• v.15 no.3
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• pp.281-289
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• 2015

Carbonation of concrete causes reduction of pH and subsequently causes steel corrosion for reinforced concrete structure. However, for plain concrete structure or PC product, it can lead to a decrease in porosity, high density, improvement of concrete, shrinkage-compensation. Recently, based on this theory, research of $CO_2$ curing effect has been performed, but it was mainly focused on its effects on compressive strength using only ordinary portland cement. Researches on $CO_2$ curing effect for concrete containing $CO_2$ reactive materials such as ${\gamma}-C_2S$, MgO haven't been investigated. Therefore, this study has performed experiments under water-binder ratio 40%, and the replacement ratios of ${\gamma}-C_2S$ and MgO were 90%. Micro-chemical analysis, measurement of compressive strength according to admixtures and $CO_2$ curing were investigated. Results from this study revealed that higher strength was measured in case of $CO_2$ curing compared with none $CO_2$ curing for plain specimen indicating difference between 1.08 and 1.26 times, in case of ${\gamma}-C_2S$ 90, MgO 90 specimen, incorporating high volume replaced as much as 90%, it was proven that when applying $CO_2$ curing, higher strength which has difference between 14.56 and 45.7 times, and between 6.5 and 10.37 times was measured for each specimen compared to none $CO_2$ curing. Through micro-chemical analysis, massive amount of $CaCO_3$, $MgCO_3$ and decrease of porosity were appeared.

• Tuberculosis and Respiratory Diseases
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• v.83 no.4
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• pp.276-282
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• 2020

Background: Flexible bronchoscopy is one of the essential procedures for the diagnosis and treatment of pulmonary diseases. The purpose of this study was to identify the risk factors associated with the occurrence of hypoxia in adults undergoing flexible bronchoscopy under sedation. Methods: We retrospectively analyzed 2,520 patients who underwent flexible bronchoscopy under sedation at our tertiary care university hospital in South Korea January 1, 2013-December 31, 2014. Hypoxia was defined as more than 5%-point reduction in the baseline percutaneous oxygen saturation (SpO₂) or SpO₂ <90% for >1 minute during the procedure. Results: The mean age was 64.7±13.5, and 565 patients developed hypoxia during the procedure. The mean sedation duration and midazolam dose for sedation were 31.1 minutes and 3.9 mg, respectively. The bivariate analysis showed that older age, a low forced expiratory volume in one second (FEV₁), use of endobronchial ultrasound, the duration of sedation, and the midazolam dose were associated with the occurrence of hypoxia during the procedure, while the multivariate analysis found that age >60 (odds ratio [OR], 1.32), a low FEV₁ (OR, 0.99), and a longer duration of sedation (>40 minutes; OR, 1.33) were significant risk factors. Conclusion: The findings suggest that patients older than age 60 and those with a low FEV₁ tend to develop hypoxia during the bronchoscopy under sedation. Also, longer duration of sedation (>40 minutes) was a significant risk factor for hypoxia.

• Journal of Korean Foot and Ankle Society
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• v.2 no.1
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• pp.19-29
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• 1998

The characteristics of the patients after the calcaneal fracture that were associated with an unsatisfactory outcome were subtalar incongruity, decreased Bohler angle ratio of the fractured to the normal side, an age of more than fifty years, work involving strenuous labor, and increased time missed from work due to the injury. The purpose of this study was to examine the reliability of measurements of the range of motion of the subtalar joint. To determine reliability, evaluates of the correlatioinship between the degree of the displacement of the subtalar joint and Circle draw test after the calcaneal fracture. Fifty patients who had had fifty five calcaneal fractures were managed with open reduction and internal fixation. The results were reviewed retrospectively, between 4months and three years after the operation, with use of an evaluation system for the subtalar joint and with plain radiographs. At follow up evaluation, the result was assessed on the basis of restoration of anatomy and function of the subtalar joint. We evaluated the subtalar joint with plain films that consist of anteroposterior projection, lateral projection, calcaneal axial view, and Broden's view, and the measurements of the displacement of the subtalar joint surface after the calcaneal fracture. And we evaluated the range of motion of the subtalar joint with Circle draw test for physical evaluation. Circle draw test was evaluated and demonstrated the motion of flexion-supination-adduction and extension-pronation-abduction of the subtalar joint. And there are correlationship between the degree of the displacement and range of motion of the subtalar joint after the calcaneal fracture. The report critically reviews methords used to measure Circle draw test for physical examination of the follow up after the calcaneal fracture.

• Korean Chemical Engineering Research
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• v.43 no.3
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• pp.425-431
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• 2005

New type of supercapacitor using high surface area activated carbons mixed with high conductivity polypyrrole (Ppy) has been prepared in order to achieve low impedance and high energy density. Mixed carbons of BP-20 and MSP-20 were used as the active electrode material, and polypyrrole doped with 2-naphthalenesulfonic acid (2-NSA) and carbon black (Super P) as conducting agents were added to activated carbons in order to enhance good electric conductivity. Electrodes prepared with the activated electrode materials and the conducting agents were added to a solution of organic binder [P(VdF-co-HFP) / NMP]. The ratio of optimum electrode composition was 78 : 17 : 5 wt.％ of (MSP20 : BP-20=1 : 1), (Super P : Ppy=10 : 7) and P(VdF-co-HFP) respectively. The performance of unit cell with addition of 7 wt％ Ppy have shown specific capacitance of 28.02 F/g, DC-ESR of $1.34{\Omega}$, AC-ESR of $0.36{\Omega}$, specific energy of 19.87 Wh/kg and specific power of 9.77 kW/kg. With addition of Ppy, quick charge-discharge of unit cell was possible because of low ESR, low charge transfer resistance and quick reaction rate. And good stability up to 500 chargedischarge cycles were retained about 80％ of their original capacity. It was concluded that the specific capacitance originated highly from compound phenomena of the pseudocapacitance by oxidation-reduction of polypyrrole and the nonfaradaic capacitance by adsorption-desorption of activated carbons.

• Korean Chemical Engineering Research
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• v.44 no.6
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• pp.609-613
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• 2006

Ba2-xSrxSiO4:Eu2+ phosphor particles with the high photoluminescence (PL) intensity under long wavelength ultraviolet (UV) were prepared by spray pyrolysis. The photoluminescence, morphological and crystalline characteristics of $Ba_{2-x.}Sr_{x.}SiO_4:Eu^{2+}$ phosphor particles prepared by spray pyrolysis were investigated. $Ba_{2-x.}Sr_{x.}SiO_4:Eu^{2+}$ phosphor particles prepared by spray pyrolysis had various colors from bluish green to yellow by changing the ratio of barium and strontium of the host material. In case of x=0, the main emission peak of $Ba_2SiO_4:Eu^{2+}$ phosphor was 500 nm. In case of x=2, the main emission peak of $Sr_2SiO_4:Eu^{2+}$ phosphor was 554nm. $Ba_{2-x.}Sr_{x.}SiO_4:Eu^{2+}$ phosphor particles obtained by spray pyrolysis had spherical shape and hollow structure. On the other hand, the post-treated $Ba_{2-x.}Sr_{x.}SiO_4:Eu^{2+}$ phosphor particles had large size and irregular shape. The $Ba_{1.488}Sr_{0.5}SiO_4:Eu_{0.012}{^{2+}}$ phosphor particles had the maximum PL intensity after post-treatment at temperature of $1300^{\circ}C$ for 3h under reduction atmosphere.