• Korean Chemical Engineering Research
• /
• v.56 no.1
• /
• pp.85-95
• /
• 2018

In this research, a biofilter system equipped with a biofilter process and a humidifier composed of a fluidized aerobic and an anoxic reactor, was constructed to treat odorous waste air containing hydrogen sulfide, ammonia and VOC, frequently generated from pig and poultry housing facilities, compost manufacturing factories and publicly owned facilities. Its optimum operating condition was revealed and discussed. In the experiment of complex feed, the ammonia of fed-waste air was removed by ca. 75% and more than 20% at the stage of the humidifier and the biofilter, respectively. The toluene of the fed-waste air was removed by ca. 20% and more than 70% at the stage of the humidifier and the biofilter, respectively. Therefore the water-soluble ammonia and the water-insoluble toluene were treated mainly at the stage of the humidifier and the biofilter, respectively. In addition, hydrogen sulfide was almost absorbed at the stage of the humidifier so that it was not detected at the biofilter process. In the experiment of ammonia-containing feed, the ammonia of fed-waste air was removed by ca. 65% and 35% at the stage of the humidifier and the biofilter, respectively. Its removal efficiency of ammonia at the stage of the humidifier was 10% less than that in the experiment of complex feed, due to no supply of such carbon source as toluene required in the process of denitrification. In the experiments of complex feed, ammonia-containing feed with and without (instead, glucose) the addition of yeast extract, the absorption rates of ammonia-nitrogen were ca. 0.28 mg/min, 0.23 mg/min and 0.27 mg/min, respectively. The corresponding denitrification rates in the anoxic reactor were 0.42 mg/min, 0.55 mg/min and 0.27 mg/min, respectively. In addition, in the modeling of bubble column(the fluidized aerobic reactor of the humidifier) process, the value of specific surface area(a) of bubbles multiplied by enhanced mass transfer coefficient (E $K_y$) was evaluated to be 0.12/hr.

• Proceedings of the KWS Conference
• /
• 2002.10a
• /
• pp.612-619
• /
• 2002

The dynamic behavior of Al-Mg alloys plasma was very unstable and this instability was closely related to the unstable motion of keyhole during laser irradiation. The keyhole fluctuated both in size and shape and its fluctuation period was about 440 ${\mu}{\textrm}{m}$. This instability has been estimated to be caused by the evaporation phenomena of metals with different boiling point and latent heats of vaporization. Therefore, the authors have conducted the spectroscopic diagnostics of plasma induced in the pulsed YAG laser welding of Al-Mg alloys in air and argon atmospheres. In the air environment, the identified spectra were atomic lines of Al, Mg, Cr, Mn, Cu, Fe and Zn, and singly ionized Mg line, as well as strong molecular spectrum of AlO, MgO and AIH. It was confirmed that the resonant lines of Al and Mg were strongly self-absorbed, in particular in the vicinity of pool surface. The self-absorption of atomic Mg line was more eminent in alloys containing higher Mg. These facts showed that the laser-induced plasma was relatively a low temperature and high density metallic vapor. The intensities of molecular spectra of AlO and MgO were different each other depending on the power density of laser beam. Under the low power density irradiation condition, the MgO band spectra were predominant in intensity, while the AlO spectra became much stronger in higher power density. In argon atmosphere the band spectra of MgO and AlO completely vanished, but AlH molecular spectra was detected clearly. The hydrogen source was presumably the hydrogen solved in the base Metal, absorbed water on the surface oxide layer or H$_2$ and $H_2O$ in the shielding gas. The temporal change in spectral line intensities was quite similar to the fluctuation of keyhole. The time average plasma temperature at 1 mm high above the surface of A5083 alloy was determined by the Boltzmann plot method of atomic Cr lines of different excitation energy. The obtained electron temperature was 3, 280$\pm$150 K which was about 500 K higher than the boiling point of pure aluminum. The electron number density was determined by measuring the relative intensities of the spectra1lines of atomic and singly ionized Magnesium, and the obtained value was 1.85 x 1019 1/㎥.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.44 no.3
• /
• pp.283-290
• /
• 2024

Currently, the quality standards for recycled aggregates in Korea are very high, at almost the same level as natural aggregates, so recycled aggregates cannot be widely used for concrete. In particular, it is necessary to evaluate how the moisture conditions and curing conditions of recycled aggregates with high absorption rates and wearing rates affect the compressive strength of concrete. Therefore, in this study, we wanted to investigate the effects on compressive strength through experiments using the moisture conditions and curing conditions of recycled coarse aggregate as variables, and compare the compressive strength characteristics of natural coarse aggregate concrete. As a result of this experimental study, the effect of compressive strength on concrete using recycled coarse aggregates according to curing conditions was similar to that of natural aggregate concrete, and the compressive strength showed a low strength of about 13 to 17 %. The effect of the moisture conditions of recycled coarse aggregates was that in the case of wet curing, concrete using wet aggregate showed slightly higher compressive strength than concrete using dry aggregate, but in the case of air curing, on the contrary, dry recycled aggregate concrete was relatively higher than wet aggregate concrete.

• Korean Journal of Remote Sensing
• /
• v.14 no.1
• /
• pp.53-68
• /
• 1998

Observation of hydrometeors' behavior in the atmosphere is important to understand weather and climate. By conventional observations, we can get the distribution of water vapor at limited number of points on the earth. In this study, the precipitable water has been estimated from the split window channel data on GMS-5 based upon the technique developed by Chesters et al.(1983). To retrieve the precipitable water, water vapor absorption parameter depending on filter function of sensor has been derived using the regression analysis between the split window channel data and the radiosonde data observed at Osan, Pohang, Kwangiu and Cheju staions for 4 months. The air temperature of 700 hPa from the Global Spectral Model of Korea Meteorological Administration (GSM/KMA) has been used as mean air temperature for single layer radiation model. The retrieved precipitable water for the period from August 1996 through December 1996 are compared to radiosonde data. It is shown that the root mean square differences between radiosonde observations and the GMS-5 retrievals range from 0.65 g/$cm^2$ to 1.09 g/$cm^2$ with correlation coefficient of 0.46 on hourly basis. The monthly distribution of precipitable water from GMS-5 shows almost good representation in large scale. Precipitable water is produced 4 times a day at Korea Meteorological Administration in the form of grid point data with 0.5 degree lat./lon. resolution. The data can be used in the objective analysis for numerical weather prediction and to increase the accuracy of humidity analysis especially under clear sky condition. And also, the data is a useful complement to existing data set for climatological research. But it is necessary to get higher correlation between radiosonde observations and the GMS-5 retrievals for operational applications.

• Korean Journal of Weed Science
• /
• v.13 no.1
• /
• pp.44-54
• /
• 1993

This experiment was conducted to understand the environmental factors affecting growth and tuber formation such as temperature, day length, tight intensity, water condition and cutting time of Eleocharis kuroguwai Ohwi. Plant height, shoot number and dry weight of E. kuroguwai were higher at high temperature, 25/$25^{\circ}C$ (day/night), while nitrogen content was higher at low temperature, 20/$15^{\circ}C$. Plant height was more affected by water temperature, while shoot number and dry weight were more affected by air temperature. Contents and absorption of nitrogen, phosphorus, and potassium in top parts of E. kuroguwai were higher under greater difference between air and water temperatures, i.e., 18/$28^{\circ}C$ and 28/$18^{\circ}C$. The number and weight of tubers were increased under greater difference between air and water temperatures, i.e, 18/$28^{\circ}C$ and 28/$18^{\circ}C$, while they were inhibited at low or high air/water temperatures (18/$18^{\circ}C$ or 28/$28^{\circ}C$). Tubers of E. kuroguwai were formed at 8-or 12-hour day length, however, no tuber was formed at l6-hour day length. Photoinductive period for tuber initiation of E. kuroguwai was between 30 and 45 days after emergence, and the induction period of short-day treatment was less than 10 days. Tuber number and weight were reduced by shading due to inhibition of the growth of top and underground parts. Number of days from planting to tuber initiation was shortned as planting time was delayed and plant height, dry weight, and tuber number were also reduced by delayed planting. Tuber number at l0 to 15cm water depth was decreased 63 to 75% as compared with 1 to 5cm water depth. Tuber number and dry weight were not affected by the size of tubers at planting. Due to the reduced growth of top and underground parts, tuber number and dry weight of E. kuroguwai were decreased by delayed shoot cutting. The critical cutting time to inhibit the growth of E. kuroguwai was about 70 days after emergence.

• Journal of the Korean Society of Radiology
• /
• v.10 no.5
• /
• pp.327-335
• /
• 2016

The study is enforce to study image quality evaluation of condition provide the IEC and combination of clinical conditions each quality of radiation that image quality to assess the conditions provided to IEC in the clinical environment to conduct image quality assessment of the digital radiography system in the detector have environmental limits. First, image quality evaluation was evaluated by measuring the MTF, NPS using four quality of radiation and Using MCNPX simulation lastly DQE make a image quality evaluation after calculating the particle fluence to analyze spectrum quality of radiation. Second, Using MCNPX simulation of four quality of radiation was evaluated absorbed dose rate about electronic 1 per unit air, water, muscle, bone by using Radiation flux density and energy, mass-energy absorption coefficient of matter. Results of evaluation of image quality, MTF of four quality of radiation was satisfied diagnosis frequency domain 1.0 ~ 3.0 lp/mm of general X-ray that indicated 1.13 ~ 2.91 lp/mm spatial frequency. The NPS has added filter, spatial frequency 0.5 lp/mm at standard NPS showed a tendency to decrease after increase. Unused added filter, spatial frequency 0.5 lp/mm at standard NPS showed a certain NPS result value after decrease. DQE in 70 kVp / unuesd added filter(21 mm Al) / SID 150 cm that patial frequency 1.5 lp/mm at standard showed a tendency to decrease after certain value showed. Patial frequency in the rest quality of radiation was showed a tendency to decrease after increase. Results of evaluation of absorbed dose, air < water < muscle < bone in the order showed a tendency to increase. Based on the results of this study provide to basic data that present for the image quality evaluation method of a digital radiation imaging system in various the clinical condition.

• KIEAE Journal
• /
• v.17 no.1
• /
• pp.69-75
• /
• 2017

Purpose: Heat transfer analysis of recently developed 'slim type double-skin system window' were presented. This window system is designed for curtain wall type façade that main energy loss factor of recent elegant buildings. And the double skin system is the dual window system integrated with inner shading component, enclosed gap space made by two windows when both windows were closed and shading component effectively reflect and terminate solar radiation from outdoor. Usually double-skin system requires much more space than normal window systems but this development has limited by 270mm, facilitated for curtain wall façade buildings. In this study, we estimated thermophysical phenomena of our double-skin curtain wall system window with solar load conditions at the summer season. Method: A fully 3-Dimentional analysis adopted for flow and convective and radiative heat transfer. The commercial CFD package were used to model the surface to surface radiation for opaque solid region of windows' frame, transparent glass, fluid region at inside of double-skin and indoor/outdoor environments. Result: Steep angle of solar incident occur at solar summer conditions. And this steep solar ray cause direct heat absorption from outside of frame surface rather than transmitted through the glass. Moreover, reflection effect of shading unit inside at the double-skin window system was nearly disappeared because of solar incident angle. With this circumstances, double-skin window system effectively cuts the heat transfer from outdoor to indoor due to separation of air space between outdoor and indoor with inner space of double-skin window system.

• Asian Journal of Atmospheric Environment
• /
• v.6 no.4
• /
• pp.259-267
• /
• 2012

To clarify the effects of black carbon (BC) particles on growth and gas exchange rates of Asian forest tree species, the seedlings of Fagus crenata, Castanopsis sieboldii, Larix kaempferi and Cryptomeria japonica were exposed to BC particles with sub-micron size for two growing seasons from 1 June 2009 to 11 November 2010. The BC particles deposited after the exposure to BC were observed on the foliar surface of the 4 tree species. At the end of the experiment, the amount of BC accumulated on the foliar surface after the exposure to BC aerosols were 0.13, 0.69, 0.32 and 0.58 mg C $m^{-2}$ total leaf area in F. crenata, C. sieboldii, L. kaempferi and C. japonica seedlings, respectively. In August 2010, the exposure to BC particles did not significantly affect net photosynthetic rate under any light intensity, stomatal diffusive conductance to water vapour ($g_s$), stomatal limitation of photosynthesis, response of $g_s$ to increase in vapour pressure deficit and leaf temperature under light saturated condition in the leaves or needles of the seedlings. These results suggest that the BC particles deposited on the foliar surface did not reduce net photosynthesis by shading, did not increase leaf temperature by absorption of irradiation light, and did not induce plugging of stomata in the leaves or needles of the seedlings. There were no significant effects of BC particles on the increments of plant height and stem base diameter during the experimental period and the whole-plant dry mass at the end of the experiment. These results indicate that the exposure to BC particles with sub-micron size for two growing seasons did not significantly affect the growth and leaf or needle gas exchange rates of F. crenata, C. sieboldii, L. kaempferi and C. japonica seedlings.

• Water for future
• /
• v.5 no.2
• /
• pp.17-29
• /
• 1972

The persent study aims at finding out a means of prevention cool spell damages on the hilly areas. The irrigation plots of 24 hour stored water warm water way and warm water plots, cool water way are respectively established to find out water temperature and influnce on the growing rice plants. The results obtained are summed up as follows. 1. Warm water areas consisted of $5 m^2 Q=0.93 1{\ell}/sec$, V=31 cm/sec, S=1/1, 000, L=81.6m, B=5cm, h=6cm, t=4min 33sec, drops=9 areas, are constructed to help the water temperature of $14.5^{\circ}C$ rise to that of $21.6^{\circ}C$. This indicates lower temperature than $23^{\circ}C$ of critical water temperature in irrigation facilities by $1.45^{\circ}C$ and than $26.2^{\circ}C$ of balanced water temperature of Seoul arears by $4.6^{\circ}C$. But this does not give much influance on rice plant cultivation. 2. The rising of water temperature is influened according to the temperature, solar radiation but the water temperature changes according to the heat absorption of organized materials, weather and terraces. The difference of water temperature could be found in the first growing stage. 3. Through the warm water way of water rises to the temperature of $21.6^{\circ}C$ which also rises to the temperature of around $30^{\circ}C$ in the paddy field of submerged irrigation. The rice plants are comparatively free from prolonged cool damage, reproduction abstructive damage. 4. The water temperature in rice field in proportion to temperature influence of weather condition but the water temperature approaches to that of weather in the days of later growing stage and water temperature become lower than the air temperature in the fruit stage. 5. The water in the submreged field is $10^{\circ}C$ warmer than in the warm water way during the first growing stage period but the water temperature in the warm water way is warmer in the later growing stage period. The cool water of $14.5^{\circ}C$ is warmed to $30.1^{\circ}C$ and rice plants cultivation is free from other damages. 6. The 12% increased production or 570.98kg/10a is made cool water plot by rising the temperature of water from $14.5^{\circ}C$ to $21.6^{\circ}C$ making the water run through warm water way. 7. The damage inflicted by the cool water irrigation during the first growing stage period is the obstruction of peak tillering stage and the obstruction of heading the later growing stage period and the obstruction of fruiting and number of panides per fill.

• Korean Journal of Food Science and Technology
• /
• v.26 no.3
• /
• pp.305-309
• /
• 1994

Precooked powder of redbean porridge (RP) was prepared by the series of process extrusion, drying, milling and blending with a mixture of whole redbean flour and corn starch and others. The optimum process and quality of products for RP were investigated. After extrusion under the moisture content 24 to 26%, twin screw speed 350 rpm, extrusion temperature 150 to $155^{\circ}C$ and feed rate 60 kg/hr, the product had a higher quality with its natural redbean flavor/color. During the extrusion process, extrusion temperature and specific mechanical energy increased from 150 to $198^{\circ}C$ and from 134 to 144 kwh/ton respectively, as the amount of addition water decreased from 6 to 2 kg/hr. By the hot air drying of redbean extrudate (RE). it could be dried below to 4% moisture content, of which level considered as an optimal moisture content for anti-caking of the powdered product, at $80^{\circ}C$ for 4hrs and at $100^{\circ}C$ for 1.5 hrs respectively. In the sieve analysis of extrudate powder, when the product milled through a mesh size of 0.5 mm or 1.0 mm, about 80% or 65% of the feed was passed a 65 mesh screen respectively. Moisture absorption of final blended products was formed a cake under 100% of relative humidity after 13 hrs of storage. As the amount of RE powder reduced, the flavor score of products decreased by sensory evaluation of products prepared by the different ratio of RE powder, corn starch and sugar.