• Applied Chemistry for Engineering
• /
• v.10 no.4
• /
• pp.568-575
• /
• 1999

Two different digestion procedures for the simultaneous determination of major and platinum-group element(PGE) in spent automobile catalysts containing PGE and silicates by inductively coupled plasma atomic emission spectrometry(ICP-AES) are compared. Combinations of mixed aids using HF, $HNO_3$, HCl, $HClO_4$, $H_2O_2$, and $H_3BO_3$ are utilized for the hot plate dissolution method and the closed-vessel microwave digestion method, The latter method has been shown to be relatively superior in terms of recovery, analysis time, and amount of aqua regia (3 parts HCl + part $HNO_3$ required to dissolve PGE in comparison with conventional open vessel hot-plate dissolution. The best results were drawn from the following conditions: In closed Teflon PFA vessels under microwave heating with temperature/pressure regulation, a 0.25 g portion of sample was digested in 2 mL of HF, 2 mL of $HNO_3$ and 6mL of HCl under the pressure of 200 psi(13.79 bar) at $180^{\circ}C$ for 1hr, followed by a second digestion stage with 16 mL of 5%(w/v) boric acid under the pressure of 20 psi(1.38 bar) at $100^{\circ}C$ for 10 min. After the microwave heating, the sample was post-treated with 10 mL of aqua regia twice by hot-plate heating. This condition gives the PGE recovery within 85~110% and the relative standard deviations within 2%. The method developed can therefore be regarded as an alternative method for routine analysis of spent automobile catalysts.

• Bulletin of the Korean Chemical Society
• /
• v.35 no.5
• /
• pp.1375-1378
• /
• 2014

In this study, maghemite (${\gamma}-Fe_2O_3$) nanoparticles were produced using gelatin protein as an effective mediator. Size, shape, surface morphology and magnetic properties of the prepared ${\gamma}-Fe_2O_3$ nanoparticles were characterized using XRD, FT-IR, TEM, SEM and VSM data. The effects of furnace temperature and time of heating together with the amount of gelatin on the produced gelatin-$Fe_3O_4$ nanocomposite were examined to prove the fundamental effect of gelatin; both as a capping agent in the nanoscale synthesis and as the director of the spinel ${\gamma}-Fe_2O_3$ synthesis among possible $Fe_2O_3$ crystalline structures.

• Solar Energy
• /
• v.12 no.1
• /
• pp.81-87
• /
• 1992

The purpose of this study was to investigate the fluid flow characteristics of heat storage in sensible heat storage system for use In cooling and heating of buildings. Heat storage material was gravels and experiments were performed in the condition of constant temperature. The experimental parameters were fluid velocity and size of gravels. The experimental results of the heat storage quantity and the heat storage efficiency by the variation of packing size and fluid velocity were as the follows : The maximum value of the heat storage capacity and heat storage efficiency and the minimum arriving time for maximum heat storage were observed when the packing ratio was 72.5% and the fluid velocity was 0.14m/s.

• Proceeding of Spring/Autumn Annual Conference of KHA
• /
• 2008.11a
• /
• pp.255-260
• /
• 2008

The purposes of this study were to determine the actual state of the indoor air quality by TVOC concentration and residents' responses and to analyze the influencing factors of IAQ in newly built university dormitory. The field measurements on the levels of TVOC and HCHO were carried out three times at an interval of 4 weeks in 3 rooms of a dormitory. The questionnaire survey on the residents that inquired into the lifestyle, the consciousness related to IAQ, and the responses of SHS was fulfilled. According to the results, the level of TVOC was approximately $0.14{\sim}18.5ppm$ and HCHO was $0.23{\sim}6.89ppm$ during 3 month since construction completion, which are seriously in excess of standard level, and seemed to be on the decrease as time goes by. The factors influencing the differences of the levels of TVOC or HCHO were the amount of ventilation including infiltration, heating temperature, relative humidity, or the use of living things including chemical. However, the residents rarely felt the responses of SHS and did not be conscious of the importance of ventilation.

• Journal of the Korean Institute of Telematics and Electronics A
• /
• v.33A no.6
• /
• pp.127-135
• /
• 1996

To increase the sensitivity and the selectivity of the sensors to TMA gas, the composition ratio and the growth conditions of the ZnO films are studied. Annealing of the ZnO films in the various time ranges and temperatures in the oxygen is carried out to enhance the stbility of the electrical resistance. Pt/Ti heater deposited on backside of the substrates in used to control the operating temperature of th esensor. The ZnO thin film sensors doped to 4.0 wt% $Al_{2}$O$_{3}$ 1.0wt.% TiO$_{2}$ and 0.2wt.% V$_{2}$O$_{5}$ exhibited a high sensitivity and an excellent selectivity for TMA gas. The sensors made with the thin films annealed at 700$^{\circ}$C for 60 minutes in the oxygen atmosphere had a good stability and linearity. The heater deposited in the ratio of 1 to 1 (Pt:Ti) had a good heating properties. The sensors fabricated using above conditions showed a good response to the actual gases of a mackerel at a step of deterioration after death.

• Journal of Soil and Groundwater Environment
• /
• v.21 no.3
• /
• pp.14-20
• /
• 2016

Remediation of crude oil contaminated soil is complicate and hard to apply traditional methods because of its persistency, durability, and high viscosity. Therefore, in this study, the efficiency of crude oil contaminated soil remediation was tested by developing a pilot-scale thermal desorption system using the indirect heating method with an exhaust gas treatment. Under optimal condition drawed by temperature and retention time, the remedial efficiency of crude oil contaminated soil and treatability of exhaust gas were analyzed. Total Petroleum Hydrocarbon (TPH) concentration of crude oil contaminated soil was decreased to 69.7 mg/kg on average and the remedial efficiency was measured at 99.60%. Through the exhaust gas, 86.0% of Volatile Organic Compounds (VOC) was degraded and 97.16% of complex malodor was reduced under the suggested optimum operation condition. This study provides important basic data to be useful in scaling up of the indirect thermal desorption system for the remediation of crude oil contaminated soil.

• Korean Journal of Computational Design and Engineering
• /
• v.4 no.4
• /
• pp.318-326
• /
• 1999

Recently, electronic systems including computers have been rapidly shrinking in size while at the same time the complexity and the capability of these systems continue to grow/sup [1]/. Thus, system volumes have decreased as system power has increased, resulting in dramatic increases in system heat density. The high temperature of the computer system is considered as the major reason for low performance and shortening life of the product. It is necessary to solve this problem due to the heat density increased and to develop the design skill of the computer cabinet according to miniaturization. M4500 desk-top computer was selected for analyzing the thermal management inside cabinet. The cabinet volume, the configuration of the heating devices, the size and location of air ventilation, and the fan selection have been investigated as the important parameters to find out an optimal cabinet design. The objectives of this project were to analyze which design parameters would affect cooling performance by thermal strategy, to design an optimal model, and to measure the temperatures of the main parts to confirm the effect of the thermal design. The temperatures of each part of the optimal model were compared with those of the existing model. As a result. the volume of this miniaturized model was about 16% smaller than that of M4500 without any change in operating performance.

• Proceedings of the KIEE Conference
• /
• 1997.07d
• /
• pp.1603-1605
• /
• 1997

$LiNiO_2$ is prepared by heating LiOH $H_2O$ and $Ni(OH)_2$ (mole ratio 1:1). In this study, we investigated X-ray diffraction, and charge/discharge property heat treatment condition and conductive agent sort and volume of $LiNiO_2$ prepared at various temperature and time. All $LiNiO_2$ prepared at this study showed hexagonal structure. In charge/discharge capacities, heated at $O_2$ than air and $750^{\circ}C$ than $700^{\circ}C$, specific capacity is higher. Therefore, when preliminary heat at $650^{\circ}C$ $O_2$ and heat at $750^{\circ}C$ carried out, charge/discharge property is best.

• Journal of the Korean housing association
• /
• v.20 no.6
• /
• pp.135-143
• /
• 2009

The purposes of this study were to determine the actual state of the indoor air quality by measuring TVOC Concentration and surveying residents' responses in a newly built university dormitory and to analyze the influencing factors of IAQ. Field measurements on the concentrations of TVOC and HCHO were carried out three times at 4 week intervals in 3 rooms of a dormitory. A questionnaire survey was conducted on residents which inquired into the resident's lifestyle, their consciousness of IAQ, and the responses to SHS. According to the results, TVOC concentrations were 0.14~18.5 ppm and HCHO concentrations were 0.23~6.89 ppm during the 3 months following the completion of construction, showing a serious state in which standard levels are exceeded, though these levels seemed to decrease over time. The factors influencing the differences in the levels of TVOC and HCHO were the ventilation volume including infiltration, the heating temperature, relative humidity, or the use of living matter that include chemical ingredients. However, the residents rarely felt the symptoms of SHS and were not conscious of the importance of ventilation.

• Journal of Powder Materials
• /
• v.26 no.5
• /
• pp.369-374
• /
• 2019

The properties of powder metallurgy products are related to their densities. In the present work, we demonstrate a method to apply artificial neural networks (ANNs) trained on experimental data to predict the bulk density of barium titanates. The density is modeled as a function of pressure, press rate, heating rate, sintering temperature, and soaking time using the ANN method. The model predictions with the training and testing data result in a high coefficient of correlation (R2 = 0.95 and Pearson's r = 0.97) and low average error. Moreover, a graphical user interface for the model is developed on the basis of the transformed weights of the optimally trained model. It facilitates the prediction of an infinite combination of process parameters with reasonable accuracy. Sensitivity analysis performed on the ANN model aids the identification of the impact of process parameters on the density of barium titanates.