• Journal of Korean Society of Steel Construction
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• v.16 no.5 s.72
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• pp.609-619
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• 2004

An investigation was conducted on the activities around Europe in order to solve the problem of the thermal bridging of steel studs, which had caused a significant disadvantage. This study included the following: diminishing the contact area between the studs and the sheathing, lengthening the heat transfer route, replacing the steel web with a less conductive material, and placing foam insulation in locations where the thermal shorts are most critical. Although energy efficiency is usually the focus of such foreign cases because their stud application is mostly limited to low-rise residential buildings, both structural and thermal performance are taken into consideration in this study because these target middle-story buildings. A hybrid stud composed of steel and polymer was also developed. This hybrid stud, which is 150 SL in size, is made of a galvanized steel sheet (SGC58) and a glass fiber reinforced polymer (GFRP) withepoxy bonding. A total of 32 specimens were manufactured. Its parameters comprise two types of connection detail,s: the thickness of steel (1.0mm and 1.2mm) and of the GFRP (4mm-4ply and 6mm-6ply), and the ratio of the length to the depth (L/D = 3, 6, 9, 12). Steel stud specimens with the same conditions were compared to the hybrid stud. The test revealed that in the case of the steel specimen with a thickness of 1.0mm, the maximum load of hybrid studs increased an average of 1.62 times comparedto that of the steel stud. In the case of the steel specimen with a thickness of 1.2mm, on the other hand, the average increase was 1.46times. All specimens showed full composite action until the collapse.

• Applied Chemistry for Engineering
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• v.19 no.2
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• pp.173-178
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• 2008

Calcium lactate was prepared by reacting lactic acid with precipitated calcium carbonate (PCC) which was prepared by carbonation process (calcite) and solution process (aragonite). Effects of PCC morphology (calcite and aragonite) on calcium lactate by the solution process were investigated experimentally. Despite the slow forming rate at the initial stage, the final yield of calcium lactate appeared higher when calcite was used. Therefore, the maximum yield of calcium lactate using aragonite was 85.0% and that using calcite was 88.7%, respectively. For both cases, the optimum temperature for the preparation appeared at around $60^{\circ}C$. Furthermore, the increase in lactic acid concentration over 2.0 mol% increased slurry viscosity and deteriorated mass transfer, which resulted in low yield of calcium lactate for both cases. SEM analyses showed that the prepared calcium lactate appeared as plate-like crystal form, irrespective of PCC morphologies, reaction temperatures, and concentrations of lactic acid.

• Journal of Energy Engineering
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• v.24 no.4
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• pp.124-129
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• 2015

An experimental study was performed estimating COP(Coefficient of Performance) of air-conditioning cycle using inverter scroll compressor with and without $Al_2O_3$ nano particle. All experiments were done for various compressor speeds from 1000~4000 rpm and used the inverter controller called CANDY to change the compressor rpm. The air-conditioning cycle components in the apparatus were used as same with components of YF hybrid car. To estimate the COP, this study measured the temperature and pressure at inlets and outlets of compressor, condenser, and evaporator. And also measured the compressor input power using Powermeter. Through the experiments, the maximum error to estimate COP was shown about ${\pm}6.09%$ at 3500rpm. The COP of refrigeration cycle with $Al_2O_3$ nano-particle was similar with that of the base cycle without nano-particle between 1000~3000 rpm of the compressor speed. But, This study showed that the COP of the cycle with $Al_2O_3$ over 3000 rpm of the compressor speed was higher than that of the base cycle due to the higher heat transfer rate increased in the evaporator from the higher oil flow rate inside the cycle as well known. Those results can be used the basic and fundamental data to design the air-conditioning cycle using inverter scroll compressor with $Al_2O_3$ nano particle.

• Journal of the Korean Geotechnical Society
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• v.30 no.8
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• pp.13-24
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• 2014

A series of trapdoor model tests was systematically performed in order to investigate soil arching. The mobilized soil arching was clearly observed by change of the vertical earth pressure loaded on trapdoor of soil container box. A slow decent of the loading plate at the trapdoor results in loosening zone over the trapdoor and the stress in this loosening zone was transferred to the stationary zone in the vicinity of the trapdoor. In particular, it was observed that the vertical earth pressure rapidly decreased in the loosening zone and increased in the stationary zone at the trapdoor. Both the maximum decreasing rate of the vertical earth pressure in the loosening zone and the increasing rate of the vertical earth pressure in the stationary zone were not influenced by the ground density, but affected by the size of the trapdoor. The loosening zone could be defined by the elliptical configuration, in which the major axis was twice as long as the height of the loosening zone at the center of trapdoor and the minor axis was the same as the width of trapdoor. The height of loosening zone at the center of trapdoor was one and a half times as long as the width of trapdoor loading plate.

• KSBB Journal
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• v.24 no.3
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• pp.303-311
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• 2009

A scaling up study for the exopolysaccharide (EPS) production by submerged culture of Ganoderma lucidum was carried out in jar fermenter systems (2.6, 20 and 75 L) under bi-staged pH process. Profiles of dissolved oxygen (DO) and volumetric coefficient of oxygen transfer ($k_La$) as a function of operating variables (agitation speed and aeration rate) was investigated, and a correlation between $k_La$ and operating variables was analysed statistically. Under bi-staged pH process, no limitation of DO was observed at agitation speeds tested in the range of 200 and 600 rpm, and the highest EPS production was obtained at the level of DO of $40{\sim}80%$. From the regression analysis, the relation between $k_La$, gas velocity (Vs), stirrer speed (N) and impeller diameter (Di) could be expressed as : $$k_La=0.555{\times}Vs^{0.42}{\times}(N^3{\times}Di^2)^{0.33}\;(R^2=0.925,\;p<0.05)$$ It was found that under 2.6 L jar fermenter, the optimum agitation speed and aeration rate was 400 rpm and 1 vvm, respectively, obtaining the EPS production of 15.43 g/L. Under the submerged cultivation of G. lucidum in jar fermenters of $2.6{\sim}75\;L$, the similar EPS yields at each fermenter were achieved during scaling up based on $k_La$, and $k_La$ value for maximum EPS production was $85.4{\pm}26.70\;h^{-1}$.

• Journal of Radiation Protection and Research
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• v.37 no.2
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• pp.90-95
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• 2012

A radio-tracer experiment was performed in a greenhouse to investigate the effectiveness of the simultaneous application of K and Ca as a countermeasure for reducing the radiocaesium and radiostrontium uptake by rice. Paddy soil (loam of pH 6.5) in soil boxes was spiked with $^{137}Cs$ and $^{85}Sr$, and treated with K and Ca in the forms of KCl and $Ca(OH)_2$, respectively, at agrochemical grades before transplanting. For the seeds of the control plants, soil-to-plant transfer factors (TF, $m^2\;kg^{-1}-dry$) of $^{137}Cs$ and $^{85}Sr$ were $7.4{\times}10^{-5}$ and $2.1{\times}10^{-4}$, respectively, whereas the corresponding values for the straws were $2.6{\times}10^{-4}$ and $2.2{\times}10^{-2}$, respectively. The TF values of $^{137}Cs$ and $^{85}Sr$ kept decreasing as the level of the simultaneous application of K and Ca (K/Ca, $g\;m^{-2}$) increased up to 33.6/322 and 48.0/460, respectively. The maximum rate of the decrease was around 60% for both radionuclides. Nearly 60% reduction in the TF value of $^{85}Sr$ was observed even at the dosage of 33.6/322, which was considered the optimum dosage based on crop productivity as well as reduction in the radiocaesium and radiostrontium uptake by rice. The optimum dosage may depend on various factors so further experiments need to be made for many different conditions.

• The Journal of Korean Academic Society of Nursing Education
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• v.7 no.2
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• pp.264-274
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• 2001

About the patients who visited the emergency department of a hospital, investigative study was performed to assess and to classify them with triage tool, and to estimate the characteristics of them. 210 patients older than 15 years were investigated. Among them 11 patients who had responded inappropriately were excluded and remaining 210 patients were chosen as study subjects. Investigation had been performed for 30 days from Jan. 10, 2001 to Feb. 9, 2001. The triage tool was designed through the modification of triage tools developed by Kim and Choi. The data were analyzed with the SPSS program using mean, standard deviation, frequency, percentage, ANOVA and Scheffe's test. The results were as follows: 1. Of the characteristics of the study subjects, mean age of patients were 55.76 years and 70-79 years group which included 41 patients(20.6%) were most numerous. 101 (51.8%) patients visited emergency room by 119 emergency service and 91(45.7%) patients walked with assistance. 127 patients were cared in internal medicine department. 2. The distribution of triage scores were from minimum 6 points to maximum 18 points with mean $13.76{\pm}2.58$ points. 3. Triage scores had significant relationship with age(F=13.349,P=0.000), visiting method (F=8.832, P=0.000), walking status(F=28.185, p=0.000), care department(F=2.596, P=0.019), and preexisting disease(F=12.012, P=0.000). 4. After trage there were no urgent patient, 35 emergent patients(17.6%),109 subemergent patients(54.8%), and 55 nonemergent patients (27.6%). The result of emergency care were 80 admission(40.2%), 59 discharge (29.6%), 34 ICU admission(17.1%), 14 transfer to other hospital(7%), 10 operation (5%), and 2 death (2%). 5. About the time required for triage, mean duration to triage were $7.54{\pm}2.28$ mins in emergent patients, mean $7.23{\pm}2.50$ mins in subemergent patients and mean $6.49{\pm}2.19$ mins in nonemergent patients. There were no differences in duration to triage according to the severity of triage. 6. Time required in emergency treatment were mean $116.23{\pm}88.10$ in emergent patients mean $101.61{\pm}73.27$ in subemergent patients and mean $81.56{\pm}61.01$ in nonemergent patients. There were no significant difference among groups. This study depicted that triage scores were below the middle level and there were many geriatric patients in this hospital. Among the characteristics of patients, age, visiting method, walking status, care department, and accompanying disease could be data for triage of emergency patients. With triage score of a patient, the outcome of emergency care of a patient could be anticipated and this could be basal data in determining the priority of emergency nursing.

• Journal of the Microelectronics and Packaging Society
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• v.12 no.2 s.35
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• pp.155-159
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• 2005

In this report, Polymer light emitting diodes (PLEDs) with an ITO/PEDOT:PSS/MEH-PPV/Al structure were prepared by spin coating method on the glass substrate patterned ITO (indium tin oxide), using PEDOT:PSS(poly(3,4=ethylenedioxythiophene):poly(styrene sulfolnate)) as the hole transfer material and MEH-PPV(poly(2-methoxy-5-(2-ethyhexoxy)-1,4-phenylenvinylene)) having a different concentration (0.1, 0.3, 0.5, 0.7, 0.9, 1.5 wt$\%$) as the emitting material. The electrical and optical properties of the prepared PLED samples were investigated. The good electrical and optical properties were observed for the PLED samples with a MEH-PPV concentration ranging from 0.5 to $0.9 wt\%$. However, the current and luminance values for PLED sample with $1.5 wt\%$ of MEH-PPV decreased greatly. The maximum luminance and light efficiency for the PLEDs with concentration of $0.5 wt\%$ MEH-PPV were $409 cd/m^2$ and 4.90 Im/W at 9 V, respectively. The emission spectrums were found to be $560{\~}585 nm$ in wavelength showing orange color.

• Journal of the Korean Chemical Society
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• v.39 no.9
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• pp.705-714
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• 1995

A new analytical luminescence method for the Eu+3 and Tb+3 ions was studied using the luminescence enhancement by the treatment of the o-phenanthroline on the nylon membrane. Compared to the specific emission intensities of the ions in aqueous(or ethanol) solution, if the aqueous ion is spotted on the nylon membrane, the luminescence intensities were extremely enhanced. There was additional enhancement effect of the luminescence intensities of the ions on the nylon membrane, if the ion on the nylon membrane is treated with o-phenanthroline. Based on the luminescence enhancement, the detection limits were lowered by more than 7 order of magnitude compared to that of solution sample, and also lowered by about 1 order of magnitude compared to that of previous TLC method. The dynamic ranges and correlation coefficients of the calibration curves near the detection limit were 2∼3 order and ∼0.99, respectively. It was also shown that the luminescence intensity was in its maximum when the ion on the nylon is treated with ∼4 mole ratio of o-phenanthroline. The energy-transfer mechanism was explained for the theoretical background of the luminescence enhancement.

• Journal of the Korean Geotechnical Society
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• v.21 no.5
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• pp.33-43
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• 2005

This work reports results of our study on the dynamic responses of the buried pipelines both along the axial and the transverse directions under various boundary end conditions. In order to investigate the effect of the boundary end conditions for the dynamic responses of the buried pipeline, we have devised a computer program to find the solutions of the formulae on the dynamic responses (displacements, axial strains, and bending strains) under the various boundary end conditions considered in this study, The dynamic behavior of the buried pipelines for the forced vibration is found to exhibit two different forms, a transient response and a steady state response, depending on the time before and after the transfer of a seismic wave on the end of the buried pipeline. We have observed a resonance when the mode wavelength matches the wavelength of the seismic wave, where the mode number(k) of resonance f3r the axial direction. On the other hand, we have not been able to observe a resonance in the analysis of the transverse direction, because the dynamic responses are found to vanish after the seventh mode. From the results of the dynamic responses at many points of the pipeline, we have found that the responses appeared to be dependent critically on the boundary end conditions. Such effects are found to be most prominent especially for the maximum values of the displacement, the strain and its position.