• Journal of the Korean Chemical Society
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• v.8 no.3
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• pp.113-120
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• 1964

The critical examination of the spectrophotometric method for determining microgram quantities of phosphate by the n-butyl acetate extraction as molybdophosphoric acid and subsequent development of the molybdenum blue has been made. In this procedure from 2 to 8 ${\mu}g$. of phosphate-phosphorus can be determined under optimum conditions. The final concentration of ammonium molybdate and the final acidity of perchloric acid for the formation of heteropoly acid are suitable to be ranges of 0.5 to 1.1% and 0. 5 to 1. 1 N respectively, and subsequently extracted with 10 ml. of n-butyl acetate. The extract is developed to molybdenum blue with 5.0 ml. of 1. 3% stannous chloride in 1N hydrochloric acid. The color is stable for at least one hour in the use of perchloric acid for the condensation. In order to determination of submicrogram amounts of phosphate, the sensitivity of the molybdenum blue method is hardly sufficient, a sensitive and stable molybdenum(V)-thiocyanate complex method has been investigated. By the procedure less than 1.2 ${\mu}g$. of phosphate-phosphorus can be determined with an accuracy of less than 5% the relative error. The molybdenum(Ⅵ) extracted by the above procedure is reduced to molybdenum(V) in the extract directly with a solution of 4 to 10% of stannous chloride, 0.5 to 1.5 mM of copper, and 0.1 to 0.9 N of perchloric acid as final concentration in 4.3 to 6.3 N of hydrochloric acid or 9.0 to 13.0 N of sulfuric acid by heating for one minute in boiling water, after cooling, the molybdenum(V)-thiocyanate complex color is developed by adding 6.0 M ammonium thiocyanate solution making the final concentration to be in a range of 0.4 to 0.9 M. This procedure the very sensitive, reliable, and stable can be applied to determining submicrogram amounts of phosphate in natural waters with a precision of 1.6 ${\times}\;10^{-2}$ the standard deviation as absorbance.

• Korean Journal of Food Science and Technology
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• v.41 no.1
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• pp.16-20
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• 2009

To develop health functional foods using high amylose rice flours, the properties of flours prepared from domestic high amylose rice varieties, Goamy2 and Goamy, and imported rice from Thailand were investigated. After soaking the rice grains and drying, the dry-milled rice flours were passed through a 120-mesh sieve. The protein and total starch contents of the Goamy2 rice flour were lowest, but its crude lipid and ash contents were highest among the flours. In addition, apparent amylose content, water binding capacity, and total dietary fiber were highest in the Goamy2 flour (36.2, 255.0, and 9.2%, respectively). The Thai rice flour had the highest swelling power, whereas the Goamy2 flour had the lowest swelling power and solubility. By Rapid visco-analysis, the Thai flour showed the highest peak and total setback viscosities and lowest breakdown viscosity. The pasting pattern of the Goamy2 flour was different from that of the other flour, where low viscosity was maintained during heating and cooling. Goamy and Thai rice flours showed an A type crystallinity, but Goamy2 flour showed a B type crystallinity similar to high amylose maize starch. The Goamy2 flour presented a dull and yellowish color, and the lowest lightness (L) value and the highest yellowness (+b) value.

• 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.

• Journal of the Korean Institute of Rural Architecture
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• v.24 no.3
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• pp.23-30
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• 2022

In this study, in order to grasp the current situation of indoor environmental pollution and indoor ventilation in one-room around the university in the post-corona era, we analyzed the experimental data and conducted a questionnaire survey on university students. By analyzing the content, the effects of formaldehyde, dust and other pollution on the human body, which are usually not easily detectable, are digitized and more easily taken into account. Among the experimental results, the concentration of VOC and HCHO, gas pollutants among indoor pollutants, exceeded the recommended criteria of the Ministry of Environment in most studio apartments. Overall, the average CO₂ concentration was lower than the Ministry of Environment's maintenance standard (1000ppm), but it was relatively high in summer and winter, and it is believed to be caused by cooling and heating in an enclosed space. The levels of PM2.5 and PM10, particulate pollutants, increased in November and December, and it is believed that ventilation defects due to degradation in external temperature. There was no clear difference between the two types, and there was a very high correlation between PM2.5 and PM10, HCHO and VOC. It was found that temperature was closely correlated with all sources except CO₂, and humidity was closely correlated with all sources except PM2.5 and PM10. Health risk assessment was conducted for formaldehyde. The average ECR of studio R2 in May was 3.91E^-4, and the ECR figure in September was 3.65E^-4, which was very high compared to other residential spaces. The R2 level was calculated as 4 people per 10,000 people in the lifetime risk of cancer of residents, exceeding the allowable risk. R8 also showed higher ECR results than other spaces after R2, especially in October, 2.01E^-4, six times higher than R7 measured in October, and 1.87E^-4 in July, four times higher than R9.

• Nuclear Engineering and Technology
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• v.56 no.3
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• pp.803-811
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• 2024

Nuclear accidents such as Fukushima Daiichi have highlighted the potential of passive safety systems to replace or complement active safety systems as part of the overall prevention and/or mitigation strategies. In addition, passive systems are key features of Small Modular Reactors (SMRs), for which they are becoming almost unavoidable and are part of the basic design of many reactors available in today's nuclear market. Nevertheless, their potential to significantly increase the safety of nuclear power plants still needs to be strengthened, in particular the ability of computer codes to determine their performance and reliability in industrial applications and support the safety demonstration. The PASTELS project (September 2020-February 2024), funded by the European Commission "Euratom H2020" programme, is devoted to the study of passive systems relying on natural circulation. The project focuses on two types, namely the SAfety COndenser (SACO) for the evacuation of the core residual power and the Containment Wall Condenser (CWC) for the reduction of heat and pressure in the containment vessel in case of accident. A specific design for each of these systems is being investigated in the project. Firstly, a straight vertical pool type of SACO has been implemented on the Framatome's PKL loop at Erlangen. It represents a tube bundle type heat exchanger that transfers heat from the secondary circuit to the water pool in which it is immersed by condensing the vapour generated in the steam generator. Secondly, the project relies on the CWC installed on the PASI test loop at LUT University in Finland. This facility reproduces the thermal-hydraulic behaviour of a Passive Containment Cooling System (PCCS) mainly composed of a CWC, a heat exchanger in the containment vessel connected to a water tank at atmospheric pressure outside the vessel which represents the ultimate heat sink. Several activities are carried out within the framework of the project. Different tests are conducted on these integral test facilities to produce new and relevant experimental data allowing to better characterize the physical behaviours and the performances of these systems for various thermo-hydraulic conditions. These test programmes are simulated by different codes acting at different scales, mainly system and CFD codes. New "system/CFD" coupling approaches are also considered to evaluate their potential to benefit both from the accuracy of CFD in regions where local 3D effects are dominant and system codes whose computational speed, robustness and general level of physical validation are particularly appreciated in industrial studies. In parallel, the project includes the study of single and two-phase natural circulation loops through a bibliographical study and the simulations of the PERSEO and HERO-2 experimental facilities. After a synthetic presentation of the project and its objectives, this article provides the reader with findings related to the physical analysis of the test results obtained on the PKL and PASI installations as well an overall evaluation of the capability of the different numerical tools to simulate passive systems.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.8 no.4
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• pp.319-327
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• 2010

A nuclear plant ESF ACS simulator was designed, built, and verified to perform experiment related to ESF ACS of nuclear power plants. The dimension of 3D CAD model was based on drawings of the main control room(MCR) of Yonggwang units 5 and 6. The CFD analysis was performed based on the measurement of the actual flow rate of ESF ACS. The air flowing in ACS was assumed to have $30^{\circ}C$ and uniform flow. The flow rate across the HEPA filter was estimated to be 1.83 m/s based on the MCR ACS flow rate of 12,986 CFM and HEPA filter area of 9 filters having effective area of $610{\times}610mm^2$ each. When MCR ACS was modeled, air flow blocking filter frames were considered for better simulation of the real ACS. In CFD analysis, the air flow rate in the lower part of the active carbon adsorber was simulated separately at higher than 7 m/s to reflect the measured value of 8 m/s. Through the CFD analyses of the ACSes of fuel building emergency ventilation system, emergency core cooling system equipment room ventilation cleanup system, it was confirmed that all three EFS ACSes can be simulated by controlling the flow rate of the simulator. After the CFD analysis, the simulator was built in nuclear grade and its reliability was verified through air flow distribution tests before it was used in main tests. The verification result showed that distribution of the internal flow was uniform except near the filter frames when medium filter was installed. The simulator was used in the tests to confirm the revised contents in Reg. Guide 1.52 (Rev. 3).

• Korean Journal of Remote Sensing
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• v.37 no.6_3
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• pp.1985-1999
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• 2021

The purpose of this study is to apply urban heat island reduction techniques(green roof, cool roof, and cool pavements using heat insulation paint or blocks) recommended by the Environmental Protection Agency (EPA) to our study area and determine their actual effects through a comparative analysis between land cover objects. To this end, the area of Mugye-ri, Jangyu-myeon, Gimhae, Gyeongsangnam-do was selected as a study area, and measurements were taken using a drone DJI Matrice 300 RTK, which was equipped with a thermal infrared sensor FLIR Vue Pro R and a visible spectrum sensor H20T 1/2.3" CMOS, 12 MP. A total of nine heat maps, land cover objects (711) as a control group, and heat island reduction technique-applied land covering objects (180) were extracted every 1 hour and 30 minutes from 7:15 am to 7:15 pm on July 27. After calculating the effect values for each of the 180 objects extracted, the effects of each technique were integrated. Through the analysis based on daytime hours, the effect of reducing heat islands was found to be 4.71℃ for cool roof; 3.40℃ for green roof; and 0.43℃ and -0.85℃ for cool pavements using heat insulation paint and blocks, respectively. Comparing the effect by time period, it was found that the heat island reduction effect of the techniques was highest at 13:00, which is near the culmination hour, on the imaging date. Between 13:00 and 14:30, the efficiency of temperature reduction changed, with -8.19℃ for cool roof, -5.56℃ for green roof, and -1.78℃ and -1.57℃ for cool pavements using heat insulation paint and blocks, respectively. This study was a case study that verified the effects of urban heat island reduction techniques through the use of high-resolution images taken with drones. In the future, it is considered that it will be possible to present case studies that directly utilize micro-satellites with high-precision spatial resolution.

• Clean Technology
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• v.19 no.3
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• pp.264-271
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• 2013

In this study, we optimized the removal condition of contaminants attached on the scrap surface to recycle the scrap generated from the Zr alloy tube manufacturing process back to the nuclear grade. The main contaminant is remnant of watersoluble cooling lubricant that is used in the pilgering manufacture during the tube production, and it is assumed to be compressed and carbonized on the surface of tube. Zirlo alloy tube of ${\phi}9.50mm$, which has high occurrence frequency of scrap, was selected as the object to be cleaned, and cleaning abilities of reagents were evaluated by measuring the characteristics of contaminants remained and by analyzing the surface of the tube after cleaning process. For evaluation of each cleaning agent, we selected two types of sodium hydroxide series and three types of potassium hydroxide series. Furthermore, to confirm dependence on tempe-rature and ultrasonic intensities, cleaning at the room temperature, $40^{\circ}C$, and $60^{\circ}C$ was conducted, and results showed that higher the cleaning temperature and higher the ultrasonic intensity, better the cleaning effect. As a result of the bare-eye inspection, while the use of sodium hydroxide provided satisfactory condition on the tube surface, the use of potassium hydroxide series provided satisfactory condition on the tube surface only when the ultrasonic intensity was over 120 W. In the cleaning effect analysis using the gravimetric method, cleaning efficiency of sodium hydroxide series was as high as 97.6% ($60^{\circ}C$, 120 W), but since the tube surface condition was poor after the use of potassium hydroxide, the gravimetric method was not appropriate. In the analytical result of surface contaminants on the tube surface, C, O, Ca, and Zr were detected, and mainly C and O dominated the proportion of contaminants. It was also found that the degree of cleaning on the tube affected the componential ratio of C and O; if the degree of cleaning is high, or if cleaning is well-conducted, the proportion of C is decreased, and the proportion of O is increased. Based on these results, optimal cleaning for application in the industry can be expected by categorizing cleaning process into three steps of Alkali cleaning, Rinsing, and Drying and by adjusting cleaning parameters in each step.

• Journal of Bio-Environment Control
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• v.15 no.2
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• pp.125-137
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• 2006

Pleurotus eryngii is one of the most promising mushrooms produced on the domestic farms. The quality as well as quantity of Eryngii is sensitively affected by micro climate factors such as temperature, relative humidity, $CO_2$ concentration, and light intensity. To safely produce high-quality Eryngii all the yew round, it is required that the environmental factors be carefully controlled by well designed structures equipped with various facilities and control systems. At the commercial mushroom cultivation houses of permanent frame type (A, B), this study was carried out to find out reasonable range of each environmental factor and yield together with economic and safe structures influencing on the optimal productivity of Eryngii. This experiment was conducted for about two-year ken Nov. 2003 to Dec. 2005 in cultivation house. Ambient temperature during the experiment period was not predominantly different from that of a normal year. The capacity of the hot water boiler and the piping systems were not enough. Because the capacity of electric heater and air circulation were not enough, air temperatures in cultivation house before improvement of system were maintained somewhat lower than setting temperature, and maximum air temperature difference between the upper and lower growth stage during a heating time period was about 5.1. But the air temperatures after system improvement were maintained within the limits range of setting temperature without happening stagnant of air. Air temperature distribution was generally distributed uniform. Relative humidity in cultivation house before , improvement was widely ranged about $44{\sim}100%$. But as the relative humidity after improvement was ranged approximately $80{\sim}100%$, it was maintained within the range of relative humidity recommended. And $CO_2$ concentration was maintained about $400{\sim}3,300mg{\cdot}L^{-1}$ range. The illuminance in cultivation house was widely distributed in accordance with position, and it was maintained lower than the recommended illuminance range $100{\sim}200lx$. The acidity of midium was some lower range than the recommend acidity range of pH $5.5{\sim}6.5$. The yield was relatively ununiform. In case of bottle capacity of 1,300cc, the mushroom of the lowest grade was less than 3%. The consumption electric energy was quite different according to the cultivation season. The electric energy consumed during heating season was much more than that of cooling season.

• The Journal of Korean Academy of Prosthodontics
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• v.40 no.1
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• pp.1-17
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• 2002

The purpose of this study is to examine the possibility of thermal injury to bone tissues during an implant site preparation under the same condition as a typical clinical practice of $Br{\aa}nemark$ implant system. All the burs for $Br{\aa}nemark$ implant system were studied except the round bur The experiments involved 880 drilling cases : 50 cases for each of the 5 steps of NP, 5 steps of RP, and 7 steps of WP, all including srew tap, and 30 cases of 2mm twist drill. For precision drilling, a precision handpiece restraining system was developed (Eungyong Machinery Co., Korea). The system kept the drill parallel to the drilling path and allowed horizontal adjustment of the drill with as little as $1{\mu}m$ increment. The thermocouple insertion hole. that is 0.9mm in diameter and 8mm in depth, was prepared 0.2mm away from the tapping bur the last drilling step. The temperatures due to countersink, pilot drill, and other drills were measured at the surface of the bone, at the depths of 4mm and 8mm respectively. Countersink drilling temperature was measured by attaching the tip of a thermocouple at the rim of the countersink. To assure temperature measurement at the desired depths, 'bent-thermocouples' with their tips of 4 and 8mm bent at $120^{\circ}$ were used. The profiles of temperature variation were recorded continuously at one second interval using a thermometer with memory function (Fluke Co. U.S.A.) and 0.7mm thermocouples (Omega Co., U.S.A.). To simulate typical clinical conditions, 35mm square samples of bovine scapular bone were utilized. The samples were approximately 20mm thick with the cortical thickness on the drilling side ranging from 1 to 2mm. A sample was placed in a container of saline solution so that its lower half is submerged into the solution and the upper half exposed to the room air, which averaged $24.9^{\circ}C$. The temperature of the saline solution was maintained at $36.5^{\circ}C$ using an electric heater (J. O Tech Co., Korea). This experimental condition was similar to that of a patient s opened mouth. The study revealed that a 2mm twist drill required greatest attention. As a guide drill, a twist drill is required to bore through a 'virgin bone,' rather than merely enlarging an already drilled hole as is the case with other drills. This typically generates greater amount of heat. Furthermore, one tends to apply a greater pressure to overcome drilling difficulty, thus producing even greater amount heat. 150 experiments were conducted for 2mm twist drill. For 140 cases, drill pressure of 750g was sufficient, and 10 cases required additional 500 or 100g of drilling pressure. In case of the former. 3 of the 140 cases produced the temperature greater than $47^{\circ}C$, the threshold temperature of degeneration of bone tissue (1983. Eriksson et al.) which is also the reference temperature in this study. In each of the 10 cases requiring extra pressure, the temperature exceeded the reference temperature. More significantly, a surge of heat was observed in each of these cases This observations led to addtional 20 drilling experiments on dense bones. For 10 of these cases, the pressure of 1,250g was applied. For the other 10, 1.750g were applied. In each of these cases, it was also observed that the temperature rose abruptly far above the thresh old temperature of $47^{\circ}C$, sometimes even to 70 or $80^{\circ}C$. It was also observed that the increased drilling pressure influenced the shortening of drilling time more than the rise of drilling temperature. This suggests the desirability of clinically reconsidering application of extra pressures to prevent possible injury to bone tissues. An analysis of these two extra pressure groups of 1,250g and 1,750g revealed that the t-statistics for reduced amount of drilling time due to extra pressure and increased peak temperature due to the same were 10.80 and 2.08 respectively suggesting that drilling time was more influenced than temperature. All the subsequent drillings after the drilling with a 2mm twist drill did not produce excessive heat, i.e. the heat generation is at the same or below the body temperature level. Some of screw tap, pilot, and countersink showed negative correlation coefficients between the generated heat and the drilling time. indicating the more the drilling time, the lower the temperature. The study also revealed that the drilling time was increased as a function of frequency of the use of the drill. Under the drilling pressure of 750g, it was revealed that the drilling time for an old twist drill that has already drilled 40 times was 4.5 times longer than a new drill The measurement was taken for the first 10 drillings of a new drill and 10 drillings of an old drill that has already been used for 40 drillings. 'Test Statistics' of small samples t-test was 3.49, confirming that the used twist drills require longer drilling time than new ones. On the other hand, it was revealed that there was no significant difference in drilling temperature between the new drill and the old twist drill. Finally, the following conclusions were reached from this study : 1 Used drilling bur causes almost no change in drilling temperature but increase in drilling time through 50 drillings under the manufacturer-recommended cooling conditions and the drilling pressure of 750g. 2. The heat that is generated through drilling mattered only in the case of 2mm twist drills, the first drill to be used in bone drilling process for all the other drills there is no significant problem. 3. If the drilling pressure is increased when a 2mm twist drill reaches a dense bone, the temperature rises abruptly even under the manufacturer-recommended cooling conditions. 4. Drilling heat was the highest at the final moment of the drilling process.