• Journal of Navigation and Port Research
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• v.39 no.6
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• pp.523-528
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• 2015

In this study, we investigated the effects of sulfuric acid on the synthesis of calcium borate in the artificial boron-containing brine (bittern) saturated with calcium hydroxide. For the study, we attempted to synthesize calcium borate under various conditions such as reaction temperature, reaction time, and cooling temperature after heating, and then to examine the recovery and purity of the calcium borate according to the presence or absence of sulfuric acid at each condition. The XRD analysis confirmed that, regardless of the presence of sulfuric acid, the calcium borate ($Ca_2B_2O_5{\cdot}H_2O$) was synthesized, while, in the presence of sulfuric acid, the calcium sulfate ($CaSO_4{\cdot}0.5H_2O$) was produced as a by-product. In all the experiments performed by varying the reaction temperature and time, the recovery and purity of the calcium borate without sulfuric acid were observed higher than those with it. The results indicated that the addition of sulfuric acid increased the solubility of the calcium hydroxide, but the calcium sulfate produced as a by-product could decrease the recovery and purity of the calcium borate by preventing the synthesis. In this study, the artificial boron-containing brine (bittern) (500 mg-B/L) was saturated with calcium hydroxide in the absence of sulfuric acid, and then the solution was heated at $80-105^{\circ}C$ for less than 10 minutes to synthesize the calcium borate. The recovery and purity of calcium borate were measured as high as 80 % and 96 %, respectively.

• Resources Recycling
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• v.16 no.4
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• pp.3-9
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• 2007

Dismantlement of lithium primary batteries without explosion is required to recycle the lithium primary batteries which could be exploded by heating too much or crushing. In the present study, the optimum discharging condition was investigated to dismantle the batteries without explosion. When the batteries were discharged with $0.5kmol{\cdot}m^{-3}$ sulfuric acid, the batteries became inert after 4 days at $35^{\circ}C$ and after 1 day at $50^{\circ}C$, respectively. This result shows that higher temperature accelerates inert of the batteries. Because loss of metals recycled increases when the batteries are discharged only with the sulfuric acid, discharging process using acid solution and water was newly proposed. When the batteries were discharged with water during 24 hours after discharging with $0.5kmol{\cdot}m^{-3}$ sulfuric acid during 6 hours, the batteries discharged were dismantled without explosion. Because decrease in loss of metals was accomplished by new process, the recycling process of the batteries could become economic by the 2-step discharging process.

• Journal of the Korean Wood Science and Technology
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• v.40 no.1
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• pp.10-18
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• 2012

A high airtightness is required for the residential spaces constructed recently to save cooling and heating energy through improving insulation performance. Because the chances to release steam formed by human activity in building and inflow of water vapor in outdoor air to residential space are reduced, the natural humidity control performance of interior materials has become more important. In this study, hygroscopic performance of thermo-physically treated wood (Pinus koraiensis) was estimated. At various relative humidity condition, the water vapor adsorption and desorption rates of wooden materials were measured as well as equilibrium moisture content. Effects of roughness and surface microstructure as physical factors and functional groups as chemical factors on the hygroscopicity were analyzed. It is expected that the results from this study and further study of measuring moisture generation in residential spaces could contribute to install a system for evaluating the hygrothermal performance of wooden building.

• Journal of the Korean Society of Food Science and Nutrition
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• v.7 no.1
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• pp.43-52
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• 1978

It is well known that water holding capacity plays an important role in processing such meat products as frankfurter-type sausage and fish meat paste products as kamaboko and fish sausage. Consumer qualities of meat products, such as appearance, flavor, as well as drip and shrinkage on cooking, depend greatly on the degree of water binding. In this paper, the water holding capacities of fish paste and salt added paste of white corvenia, Argyrosomus argentatus and file fish, Novodon modestus were measured by centrifuging and press method before and after cooking. And the effects of the addition of phosphates and starch to enhance water binding and stabilize gel formation were also discussed. In addition, the experimental conditions which are suitable to determine the water binding of fish meat paste product were suggested. The results were expressed in percent of water absorbed by the filter paper when pressed or released by pressor or centrifuge to the weight of sample. From the results. a proper condition to measure the water holding capacity of fish meat paste was that 3.0 g of sample which was previously added with 10 percent water was centrifuged at 13,400 G or 12,000 rpm for 15 minutes for the centriguging method and for press method, 0.3 g sample with 10 percent of water added was extracted by an oil pressor at $30\;kg/cm^2$ for 1 minute. Water holding capacity of fresh paste of white corvenia was relatively higher than that of file fish and the difference between species of fish was greater than the difference between measurments by two methods. Sodium chloride had a great effect on enhancing the water holding capacity of fish meat paste giving better effect when 3.0 percent of salt was added. Phosphates used except calcium phosphate revealed a certain enhancement in water binding, yielding best effect at 0.3 percent addition, and metaphosphate seemed to be more effective in order. The addition of corn starch, however, appeared to be not so effective for enhancement of water binding in fresh-salt-added fish meat paste but in cooked fish paste which might be attributed to absorption of water by starch grain and swelling during the heating and consequently enforced gel strength of cooked fish paste. And the water holding capacity of cooked fish paste was proportionally related to its gel strength.

• Journal of the Korean GEO-environmental Society
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• v.22 no.11
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• pp.15-21
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• 2021

Losses of both life and property increased from damage to underground pipe such as heat transmission pipe buried underground in downtown because pipes are gradually aging. Considering the characteristics of the heat transmission pipe, which is not exposed to the outside and difficult to immediately identify problems such as damage, it is realistic to indirectly check the condition of the facility based on the historical information that is periodically collected through facility maintenance. In this study, a methodology for estimating the damage probability was developed by examining the history information of the heat transmission pipe, deriving an evaluation factor that is related to the damage probability. The contribution factor of the damage probability were reviewed by analyzing not only the guidelines for maintenance of heat transmission pipe of advanced European countries and domestic district heating companies, but also the cases of waterworks with similar characteristics. Evaluation factors were selected by considering not only the correlation with the damage probability but also the possibility of securing data. Based on 1999, when the construction technology and standards of heat transmission pipe changed, the damage probability estimation function according to the period of use was divided into the case of being buried before 1998 and the case of being buried after 1999, and presented. In addition, the damage probability was corrected by assigning weights according to the measured data for each evaluation factor such as the diameter, use, and management authority.

• Journal of Korea Foundry Society
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• v.39 no.2
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• pp.26-31
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• 2019

In this study, the mechanical characteristics and microstructure of hypereutectic Al-17Si-5Fe extruded alloys prepared by a rapid solidification process (RSP) were investigated. The hypereutectic Al alloy was fabricated by means of RSP and permanent casting. For RSP, the Al alloy melted at $920^{\circ}C$, cooling the specimens at a rate of $10^6^{\circ}C/s$ when the RSP was used, thus allowing the refining of primary Si particles more than when using permanent casting, at a rate of about 91%. We tested an extrusion RSP billet and a permanent-cast billet. Before the hot-extrusion process, heating to $450^{\circ}C$ took place for one hour. The samples were then hotextruded with a condition of extrusion ratio of 27 and a ram speed of 0.5 mm/s. Microstructural analyses of the extruded RSP method and the permanent casting method were carried out with OM and SEM-EDS mapping. The mechanical properties in both cases were evaluated by Vickers micro-hardness, wear resistance and tensile tests. It was found that when hypereutectic Al-17Si-5Fe alloys were fabricated by a rapid solidification method, it becomes possible to refine Si and intermetallic compounds. During the preparation of the hypereutectic Al-17Si-5Fe alloy by the rapid solidification method, the pressure of the melting crucible was low, and at faster drum speeds, smaller grain alloy flakes could be produced. Hot extrusion of the hypereutectic Al-17Si-5Fe alloy during the rapid solidification method required higher pressure levels than hot extrusion of the permanent mold-casted alloy. However, it was possible to produce an extruded material with a better surface than that of the hot extruded material processed by permanent mold casting.

• Korean Journal of Heritage: History & Science
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• v.50 no.3
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• pp.88-109
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• 2017

As the technique to remove Paraloid B-72, which is known as an irreversible material, the method using organic solvent and heating, though the ways vary depending on the kind of material to be removed, has been usually used, but it has yet to apply to mud mural because of the technical limit in processing and the potential risk of damage and, moreover, the removal efficiency which also remains unproven. Thus, in a bid to seek the way to safely remove Paraloid B-72 contained in mural, the test was conducted in a way of applying a compress method, which is deemed most efficient. The solvents which are proven to be Paraloid B-72 were applied to the absorbents such as active carbon fiber and methyl cellulose and then were eluted to the surface of mud mural sample which was prepared in the same size and condition for a certain time before evaluating the stability and removal efficiency. Such test was intended to identify the applicability to the mural of Mireukjeon Hall at Geunsansa Temple, which had been treated with Paraloid B-72 for preservation in the past. As a result, the way of mixing the absorbent such as active carbon fiber and Xylene alone or with other quick vaporable solvents proved to be most efficient in removing Paraloid B-72 from mud mural and particularly Acetone:Xylene(1:1wt%) was found to be the most stable among others. Such a test outcome is expected to be a useful data for removing Paraloid B-72 from the mural of Mireukjeon Hall at Geunsansa Temple as well as for restoring other mural cultural assets in the coming days.

• Journal of Korea Society of Waste Management
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• v.35 no.7
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• pp.616-626
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• 2018

The quality standards of solid refuse fuel (SRF) define the values for 12 physico-chemical properties, including moisture, lower heating value, and metal compounds, according to Article 20 of the Enforcement Rules of the Act on Resource Saving and Recycling Promotion. These parameters are evaluated via various SRF Quality Test Methods, but problems related to the heavy metal content have been observed in the microwave acid digestion method. Therefore, these methods and their applicability need improvement. In this study, the appropriate testing conditions were derived by varying the parameters of microwave acid digestion, such as microwave power and pre-treatment time. The pre-treatment of SRF as a function of the microwave power revealed an incomplete decomposition of the sample at 600 W, and the heavy metal content analysis was difficult to perform under 9 mL of nitric acid and 3 mL of hydrochloric acid. The experiments with the reference materials under nitric acid at 600 W lasted 30 minutes, and 1,000 W for 20 or 30 minutes were considered optimal conditions. The results confirmed that a mixture of SRF and an acid would take about 20 minutes to reach $180^{\circ}C$, requiring at least 30 minutes of pre-treatment. The accuracy was within 30% of the standard deviation, with a precision of 70 ~ 130% of the heavy metal recovery rate. By applying these conditions to SRF, the results for each condition were not significantly different and the heavy metal standards for As, Pb, Cd, and Cr were satisfied.

• Korean Journal of Metals and Materials
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• v.46 no.2
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• pp.65-68
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• 2008

Generally CCM (cold crucible melting) is not suitable for melting glass. However, in this study we described the quantitative relationship between the basic property of glass and power balance, the power absorption in the melt, the losses in the coil and the cold crucible, for melting glass in CCM. The dependence of power balance on the applied frequency and the electric conductivity has been found. Above 300 kHz, the glass (B) contained alkali ion which has the low resistance $3.0{\Omega}{\cdot}cm$ at $900^{\circ}C$ and $1.36{\Omega}{\cdot}cm$ at $1,100^{\circ}C$ was melted easily and 60% of the overall power was absorbed in the melt and 30% and 10% of the overall power was lost in the cold crucible and coil respectively. Under the same condition, the glass (A) contained non-alkali ion was not melted easily and 50% of the overall power was absorbed in the melt and 40% and 10% of the overall power was lost in the cold crucible and coil respectively. In conclusion, the small absorbed power of the overall power in melt prevented a successful melting as for glass A, and the successful melting depends on the relative size of the absorbed power in melt irrespective of the melting volume. Hence, as typical for direct induction heating method(CCM), the successful melting strongly depended on the chosen working frequency based on electric conductivity of glass, power balance and the control of the critical power which was absorbed in melt.

• Journal of the Korean Society of Radiology
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• v.16 no.6
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• pp.787-797
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• 2022

The purpose of this study was to confirm the reduction of pain and symptom relief of Parkinson's disease by vertically stimulating the spine through the application of a mechanical bed capable of thermal and massage stimulation. For this purpose, after confirming the segmental motion of the spine due to the use of a medical combination stimulation bed for Parkinson's disease patients, VAS, ODI, gait ability, and spiral drawing tests were performed, and the relationship between the variables was identified. In the 10-day visual analog scale and evaluation of low back pain dysfunction, the average trend of decreasing after bed use was confirmed. For walking ability, a decrease in the moving time and an increase in the moving distance were observed. In the spiral drawing test, the mean test time after using bed was significantly lower than before. As a result, it suggested the possibility of using it as an auxiliary method for recovery and pain relief of Parkinson's disease patients due to spinal segmental movement with mechanical heating and massage. However, this study is a preliminary study, and there is a small number of subjects, so additional research is needed that considers the number and condition of future subjects in detail.