• Particle and aerosol research
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• v.13 no.2
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• pp.79-85
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• 2017

This study identified the loss of minimum fluidization velocity and pressure in accordance with the superficial velocity of $NiO/MoO_3/MoS_2$, a rare metallic oxide and high value-added material in the lab-scale fluidized bed reactor (L=0.25 m, D=0.05 m). The average pressure loss in L/D 1, 2, and 3 of $NiO/MoO_3/MoS_2$ within the scope of superficial gas velocity between 0.07 and 0.45 m/s based on the L/D 1, 2, and 3 of the specimen was shown to be 290~1952 Pa at decreasing flux and 253~1925 Pa at increasing flux. The comparison between the theoretical value proposed by Wen and the test data showed a difference between 0.021~0.36 magnification. Based on these results, this study was able to determine the operation conditions where rare metallic oxides could be applied in real phenomena.

• Journal of Korean Home Economics Education Association
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• v.18 no.2 s.40
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• pp.29-45
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• 2006

This study was to investigate the perception of middle school students on the management of the curriculum $\ulcorner$Technology Home Economics$\lrcorner$ according to the 7th National Curriculum. The subjects were 494 third grade students from middle schools located in Seoul, in order to inquire into their perceptions through the questionnaire. The collected data was analyzed with the descriptive statistics, Pearson Chi-Square, t-test, and one-way ANOVA by SPSS Win ver. 12.0 program. The major findings were as follows: Firstly there were gender differences on the interests for the subject of $\ulcorner$Technology Home Economics$\lrcorner$. The girls who were interested in the subject were much more numerous than the boys, but only in the technology part of it, the boys were more interested than the girls. Secondly the students recognized that the experiment & practice for learning $\ulcorner$Technology Home Economics$\lrcorner$ was important. They, however, recognized that its operation in school was not enough to understand the contents. The higher a student viewed the importance of the experiment & practice on $\ulcorner$Technology Home Economics$\lrcorner$, the higher his perception of its usefulness in real life. Thirdly the highest ranking of its usefulness for the contents of the subject $\ulcorner$Technology Home Economics$\lrcorner$ was identified as 'the Computer and Information Processing' and 'the Nutrients and Diet in Adolescence'. These findings suggest that the importance of the experiment & practice was enhanced and the gender differences on the usefulness of the experiment & practice on the each units were considered in order to increase the degree of the students' interest and usefulness of the $\ulcorner$Technology Home Economics$\lrcorner$

• Korean Chemical Engineering Research
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• v.44 no.6
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• pp.623-630
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• 2006

The slag viscosity is an important factor determining the operation temperature of entrained flow type of gasifiers. The temperature of critical viscosity, $T_{cv}$, for 5 crystalline slags was predicted by empirical models and FactSage equilibrium calculations, and the validity of each method was tested. Two empirical models were employed: one using $T_h$ from the ash fusion test, and the other using the concentrations of 5 major components. The first model using $T_h$ over-predicted $T_{cv}$ by $20{\sim}100^{\circ}C$, while the model based on the slag composition under-predicted $T_{cv}$ by $80{\sim}120^{\circ}C$. In the equlibrium calculations, $T_{cv}$ was obtained from the liquidus temperature. When the 4-major component concentrations were used in the calculation, the predicted temperatures were higher than the observed. The liquidus temperature was very sensitive to the concentrations of minor components, and the addition of MgO and $Na_2O$ lowered the liquidus temperature. The results with 4 major and 3 minor components most closely described experimentally observed $T_{cv}$. In the case that a chromia refractory was used, it was shown that $Cr_2O_3$ concentration in the slag also needs to be included for more accurate prediction of $T_{cv}$.

• Journal of Life Science
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• v.15 no.4 s.71
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• pp.584-589
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• 2005

To investigate factors affecting the removal of phosphorus from the practical wastewater in the F-STEP PROCESS using a loess ball and Chromobacterium WS 2-14, first, the loess ball size and calcining temperature, initial pH, initial phosphorus concentration, working temperature, and aeration were studied. A $2\~4mm$ of loess ball made at $960^{\circ}C$ of calcining temperature was the most suitable one for the removal of phosphorus. When the initial pH was increased from 3.0 to 6.0, the removal efficiency of phosphorus was increased. Especially, at 6.0 of initial pH, the maximum removal efficiency of phosphorus was $88.7\%$. The maximum removal efficiency of phosphorous was gained, 1.8mg/h when the initial concentration of phosphorous was 5.0mg/1. When the operating temperature was $30^{\circ}C$, the maximum removal efficiency of phosphorus was obtained. In the case of aeration, when it was increased from 0.5 to 5.0L/min, the removal efficiency of phosphorus was increased. On the other hand, above 7.0 L/min, the removal efficiency of phosphorus did not increased. Using the optimum operation conditions, pilot tests for the effective removal efficiency of phosphorus were carried out for 65 days. The average removal efficiency of phosphorus was $92.0\%$. The average removal efficiency of COD, BOD, and SS were 77.1, 74.2, and $86.4\%$, respectively. from the results, it can be concluded that F-STEP PROCESS using loess ball might be useful process for phosphorus removal.

• Journal of the Korean Society of Safety
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• v.31 no.3
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• pp.8-15
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• 2016

The purpose of this study is to design a model with the structural stability so as not to lose the operational function due to structural plastic or fail of a sliding blast door by blast pressure to this aim, a numerical simulation was performed using full-size experiments and M&S (Modeling & Simulation) of the sliding blast door. The sliding blast door ($W3,000{\times}H2,500mm$) under the blast load is in the form of a sliding type 2-way metal grill, which was applied by a design blast pressure (reflected pressure $P_r$) of 17 bar. According to the experimental results of a real sliding blast door under blast load, the blast pressure reached the sliding blast door approximately 4.3 ms after the explosion and lasted about 4.0 ms thereafter. The maximum blast pressure($P_r$) was 347.7 psi (2,397.3 kPa), it is similar to the UFC 3-340-02 of Parameter(91 %). In addition, operation inspection that was conducted for the sliding blast door after real test showed a problem of losing the door opening function, which was because of the fail of the Reversal Bolt that was installed to prevent the shock due to rebound of the blast door from the blast pressure. According to the reproduction of the experiment through M&S by applying the blast pressure measurement value of the full-size experiments, the sliding blast door showed a similar result to the full-size experiment in that the reversal bolt part failed to lose the function. In addition, as the pressure is concentrated on the failed reversal bolt, the Principal Tensile Failure Stress was exceeded in only 1.25 ms after the explosion, and the reversal bolt completely failed after 5.4 ms. Based on the result of the failed reversal bolt through the full-size experiment and M&S, the shape and size of the bolts were changed to re-design the M&S and re-analyze the sliding blast door. According to the M&S re-analysis result when the reversal bolt was designed in a square of 25 mm ($625mm^2$), the maximum pressure that the reversal bolt receives showed 81% of the principal tensile failure stress of the material, in plastic stage before fail.

• Journal of the Institute of Convergence Signal Processing
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• v.17 no.2
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• pp.83-92
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• 2016

In this paper, we introduce the results of the testing and observation systems for performance wideband expansion in the Korean VLBI Network(KVN). The KVN performs VLBI observations to 1024 Mbps data rate, and 8192 Mbps observing for four simultaneous observation is now evaluating for normal operation. The VLBI stations in several world countries developed their own wideband observing systems to observe the celestial objects with high precision and high resolution or are working with several countries. The KVN is planning to introduce a high-speed sampler, OCTAD, for sampling directly up to 2048 MHz bandwidth for RF signal of K/Q/W/D band in the frequency band without conversion. Therefore, as a preliminary study for the performance scalability of the KVN then through the close cooperation with National Astronomical Observatory of Japan (NAOJ), the OCTAD high-speed sampler and OCTADISK2 high-speed recorder were installed in the KVN Yonsei station, and verify the performance through a wideband.

• The Korean Journal of Pain
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• v.7 no.1
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• pp.100-105
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• 1994

This is a study of decrease in both stump pain and unidentified complaints after removal of neuroma on an amputated left thigh. The patient was a 44 year old woman who received an operation after a motorcycle accident 20th of March, 1991. She started a rehabilitation program in early June of the same year. How ever the patient complained of a squeezing pain on the amputated area. This symptom became more severe after the removal of the nails in September. The pain was perceived as a mental problem and the patient was released from the previous hospital. The pain continued and on the 9th of March, 1992, the patient was introduced to our pain clinic. The patient complained about the cold sensation and pressure pain of the amputated area at the beginning. Later she also expressed various unidentified complaints. No improvement resulted after conducting an epidural block and a lumbar sympathetic ganglion block. MMPI test showed psychological instability. Local injection showed some positive effects, which led to considerations concerning the possibility of neuroma. After confirming the existence of neuroma through CT and MRI, neuromectomy was performed. After the removal of neuroma, the unidentified complaints as well as the stump pain decreased.

• Journal of Energy Engineering
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• v.16 no.4
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• pp.155-163
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• 2007

To insure nuclear reactor safety, the reactivity of control rods should be calculated by measuring the criticality of reactor core and it is regularly performed during the annual physics test period. Also, the core criticality should be monitored during the start-up operation to avoid reactivity induced accidents. Many research works on control rod reactivity measurement and subcriticality measurement have been accomplished throughout the world for decades and recently a new method named "Modified Neutron Source Multiplication Method (MNSM)" was proposed in Japan which is known to be improved overcoming limitations of traditional Neutron Source Multiplication Method (NSM). In this study, MNSM was tested in calculation of subcriticalities and in evaluation of application validity using the educational reactor in Kyung Hee University, AGN-201. For this study, a revised nuclear data library and a neutron transport code system TRANSX - PARTISN were established. Correction factors for various control rod positions were produced using the k-effective values and the corresponding flux distributions and adjoint flux distributions. Experimental values of the core criticality were obtained using the neutron count rates of the BF3 proportional counters. The results showed that the expected reactivity worth of control rods by MNSM agreed well with the theoretical values and the correction factors contributed much for this purpose.

• Journal of Energy Engineering
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• v.23 no.2
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• pp.149-157
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• 2014

The steam generator tubes of nuclear power plants have various types of corrosion failures during the plant operation. The stress corrosion cracking which occurs on the outer surface of tube is called the secondary side stress corrosion cracking and mainly occurs in the expansion-transition area of tube. The causes are the concentration of impurities by the sludge pile-up related to the geometry of its region and the residual stress by tube expansion in the process of steam generator manufacturing. Especially the directionality and sizes of residual stresses are differed according to the tube expansion methods and the direction and the frequency of tube cracks depend on their characteristics. In bases on the plant experiences, it is notified that circumferential cracks of tubes expanded with explosive expansion method are dominantly occurred compared to those of tubes done with hydraulic expansion one. Therefore in this study, according to tube expansion methods frequencies and sizes of tube cracks with specific direction are compared by means of accelerated immersion test and also the crack morphology and the specific chemicals from water-chemistry environment are observed through the fracture surface examination.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.11
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• pp.1192-1197
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• 2006

Adsorbability of ionic and nonionic pharmaceuticals was studied using granular activated carbon(GAC). In a batch adsorption test of muticomponent solution, 500 mg/L of GAC dose removed all target compounds between 94 and 98% at initial concentration of 10 ${\mu}g/L$. Adsorption of ionic pharmaceuticals increased as pH was lowered toward to pKa, however adsorption capacity of nonionic pharmaceuticals showed insignificant variation with the changing pH. The enhanced adsorption capacity of ionic pharmaceuticals at lower pH was attributed to the corresponding increase in the molecular form of ionic pharmaceuticals with carboxylic group at low pH. In addition, decrease of pH increased hydrogen ion concentration in the bulk solution and the protons bound to the available sites on the carbon enhanced the removal of the ionic pharmaceuticals from solution. After 40 days of continuous operation, GAC column showed the removal of target compounds were removed by $93{\sim}99%$ at 15 min of EBCT mainly due to adsorption mechanism of GAC. At shorter EBCT than 15 min, breakthrough of CA, IBP and GFZ occurred earlier than the other ionic and nonionic pharmaceuticals. effect of EBCT on adsorption of nonionic pharmaceuticals was greater than ionic ones. This study showed that persitent pharmaceuticals found in drinking water treatment could be effectively controlled by adsorption in GAC process.