• Analytical Science and Technology
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• v.19 no.6
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• pp.535-543
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• 2006

Being used widely in semiconductor and display manufacturing, $NF_3$ is internationally considered as one of the regulated compounds in emission. Numerous companies have been continuously trying to reduce the emissions of $NF_3$ to comply with the global environmental regulation. This work is made to report the destruction and removal efficiency (DRE) of electrically heated scrubbers and the use rate in process chambers installed in three main LCD manufacturing companies in Korea. As the measurement techniques for $NF_3$ emission, mass flow controlled helium gas was continuously supplied into the equipment by which scrubber efficiency is being measured. The partial pressures of $NF_3$ and helium were accurately measured for each sample using a mass spectrometer, as it is emitted from inlet and outlet of the scrubber system. The results show that the DRE value for electrically heated scrubbers installed before 2004 is less than 52 %, while that for the new scrubbers modified based on measurement by scrubber manufacturer has been sigificentely improved upto more than 95 %. In additon, we have confirmed the efficiency depends on such variables as the inlet gas flow rate, water content, heater temperature, and preventative management period. The use rates of $NF_3$ in process chambers were also affected by the process type. The use rate of radio frequency source chambers, built in the $1^{st}$ and $2^{nd}$ generation process lines, was determined to be less than 75 %. In addition, that of remote plasma source chambers for the $3^{rd}$ generation was measured to be aboove 95 %. Therefore, the combined application of improved scrubber and the RPSC process chamber to the semiconductor and display process can reduce $NF_3$ emmision by 99.95 %. It is optimistic that the mission for the reduction of greenhouse gas emission can be realized in these LCD manufacturing companies in Korea.

• Magazine of the Korean Society of Agricultural Engineers
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• v.17 no.1
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• pp.3642-3654
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• 1975

The purpose of this thesis is to derive a unit hydrograph which may be applied to the ungaged watershed area from the relations between directly measurable unitgraph properties such as peak discharge(qp), time to peak discharge (Tp), and lag time (Lg) and watershed characteristics such as river length(L) from the given station to the upstream limits of the watershed area in km, river length from station to centroid of gravity of the watershed area in km (Lca), and main stream slope in meter per km (S). Other procedure based on routing a time-area diagram through catchment storage named Instantaneous Unit Hydrograph(IUH). Dimensionless unitgraph also analysed in brief. The basic data (1969 to 1973) used in these studies are 9 recording level gages and rating curves, 41 rain gages and pluviographs, and 40 observed unitgraphs through the 9 sub watersheds in Nak Oong River basin. The results summarized in these studies are as follows; 1. Time in hour from start of rise to peak rate (Tp) generally occured at the position of 0.3Tb (time base of hydrograph) with some indication of higher values for larger watershed. The base flow is comparelatively higher than the other small watershed area. 2. Te losses from rainfall were divided into initial loss and continuing loss. Initial loss may be defined as that portion of storm rainfall which is intercepted by vegetation, held in deppression storage or infiltrated at a high rate early in the storm and continuing loss is defined as the loss which continues at a constant rate throughout the duration of the storm after the initial loss has been satisfied. Tis continuing loss approximates the nearly constant rate of infiltration (${\Phi}$-index method). The loss rate from this analysis was estimated 50 Per cent to the rainfall excess approximately during the surface runoff occured. 3. Stream slope seems approximate, as is usual, to consider the mainstreamonly, not giving any specific consideration to tributary. It is desirable to develop a single measure of slope that is representative of the who1e stream. The mean slope of channel increment in 1 meter per 200 meters and 1 meter per 1400 meters were defined at Gazang and Jindong respectively. It is considered that the slopes are low slightly in the light of other river studies. Flood concentration rate might slightly be low in the Nak Dong river basin. 4. It found that the watershed lag (Lg, hrs) could be expressed by Lg=0.253 (L.Lca)0.4171 The product L.Lca is a measure of the size and shape of the watershed. For the logarithms, the correlation coefficient for Lg was 0.97 which defined that Lg is closely related with the watershed characteristics, L and Lca. 5. Expression for basin might be expected to take form containing theslope as {{{{ { L}_{g }=0.545 {( { L. { L}_{ca } } over { SQRT {s} } ) }^{0.346 } }}}} For the logarithms, the correlation coefficient for Lg was 0.97 which defined that Lg is closely related with the basin characteristics too. It should be needed to take care of analysis which relating to the mean slopes 6. Peak discharge per unit area of unitgraph for standard duration tr, ㎥/sec/$\textrm{km}^2$, was given by qp=10-0.52-0.0184Lg with a indication of lower values for watershed contrary to the higher lag time. For the logarithms, the correlation coefficient qp was 0.998 which defined high sign ificance. The peak discharge of the unitgraph for an area could therefore be expected to take the from Qp=qp. A(㎥/sec). 7. Using the unitgraph parameter Lg, the base length of the unitgraph, in days, was adopted as {{{{ {T}_{b } =0.73+2.073( { { L}_{g } } over {24 } )}}}} with high significant correlation coefficient, 0.92. The constant of the above equation are fixed by the procedure used to separate base flow from direct runoff. 8. The width W75 of the unitgraph at discharge equal to 75 per cent of the peak discharge, in hours and the width W50 at discharge equal to 50 Per cent of the peak discharge in hours, can be estimated from {{{{ { W}_{75 }= { 1.61} over { { q}_{b } ^{1.05 } } }}}} and {{{{ { W}_{50 }= { 2.5} over { { q}_{b } ^{1.05 } } }}}} respectively. This provides supplementary guide for sketching the unitgraph. 9. Above equations define the three factors necessary to construct the unitgraph for duration tr. For the duration tR, the lag is LgR=Lg+0.2(tR-tr) and this modified lag, LgRis used in qp and Tb It the tr happens to be equal to or close to tR, further assume qpR=qp. 10. Triangular hydrograph is a dimensionless unitgraph prepared from the 40 unitgraphs. The equation is shown as {{{{ { q}_{p } = { K.A.Q} over { { T}_{p } } }}}} or {{{{ { q}_{p } = { 0.21A.Q} over { { T}_{p } } }}}} The constant 0.21 is defined to Nak Dong River basin. 11. The base length of the time-area diagram for the IUH routing is {{{{C=0.9 {( { L. { L}_{ca } } over { SQRT { s} } ) }^{1/3 } }}}}. Correlation coefficient for C was 0.983 which defined a high significance. The base length of the T-AD was set to equal the time from the midpoint of rain fall excess to the point of contraflexure. The constant K, derived in this studies is K=8.32+0.0213 {{{{ { L} over { SQRT { s} } }}}} with correlation coefficient, 0.964. 12. In the light of the results analysed in these studies, average errors in the peak discharge of the Synthetic unitgraph, Triangular unitgraph, and IUH were estimated as 2.2, 7.7 and 6.4 per cent respectively to the peak of observed average unitgraph. Each ordinate of the Synthetic unitgraph was approached closely to the observed one.

• Clinical and Experimental Pediatrics
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• v.52 no.4
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• pp.494-498
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• 2009

Purpose : Applicability of transcatheter closure of atrial septal defect (ASD) has been expanded by accumulation of clinical experiences and evolutions of the device. This study was performed to evaluate the safety and efficacy of transcatheter closure of ASD with Amplatzer septal occluder (ASO) in young children less than 3 years of age. Methods : From May 2003 to December 2005, 295 patients underwent transcatheter closure of ASD with ASO in the Severance Cardiovascular Hospital, Yonsei University Health System. Among them, 51 patients less than 3 years of age were enrolled in this study. We investigated procedural success rate, rate of residual shunt, frequency of complications, procedure/fluoroscopy time, and need of modified techniques for device implantation. Results : The median age was 2.1 years and median body weight was 12 kg. Implantation of device was successful in 50 patients (98%). Seven patients (15%) showed a small residual shunt 1 day after the procedure, but complete occlusion had been documented at 6 month follow-up in all patients (100%). The pulmonary to systemic flow ratio (Qp/Qs), peak systolic pulmonary artery pressure, and peak systolic right ventricular pressure had decreased significantly after closure of ASD. There were 2 complications including device embolization (1, 2%) and temporary groin hematoma (1, 2%). Conclusion : Transcatheter closure of ASD with ASO can be performed with satisfactory results and acceptable risk even in young children less than 3 years of age. We could suggest that even in very young children with ASD, there is no need to wait until they grow to a sufficient size for the transcatheter closure.

• Journal of the Korean Geosynthetics Society
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• v.12 no.4
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• pp.67-76
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• 2013

Landfill require special care due to the dangers of nearby surface water and underground water pollution caused by leakage of leachate. The leachate does not leak due to the installation of the geomembrane but sharp wastes or landfill equipment can damage the geomembrane and therefore a means of protecting the geomembrane is required. In Korea, in accordance with the waste control act being modified in 1999, protecting the geosynthetics liner on top of the slope of landfill and installing a drainage layer to fluently drain leachate became mandatory, and technologies are being researched to both protect the geomembrane and quickly drain leachate simultaneously. Therefore, this research has its purpose in studying the drainage functions of leachate and protection functions of the geomembrane in order to examine the application possibilities of Geo-Multicell-Composite (GMC) as a Leachate Collection Removal and Protection System (LCRPs) at the slope on top of the geomembrane of landfill by observing methods of inserting filler with high-quality water permeability at the drainage net. GMC's horizontal permeability coefficient is $8.0{\times}10^{-4}m^2/s$ to legal standards satisfeid. Also crash gravel used as filler respected by vertical permeability is 5.0 cm/s, embroidering puncture strength 140.2 kgf. A result of storm drain using artificial rain in GMC model facility, maxinum flow rate of 1,120 L/hr even spray without surface runoff was about 92~97% penetration. Further study, instead of crash gravel used as a filler, such as using recycled aggregate utilization increases and the resulting construction cost is expected to savings.

• Korean Journal of Animal Reproduction
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• v.23 no.2
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• pp.165-174
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• 1999

Boar semen can be frozen successfully. However, there is a large variability in the extent of damage boar semen samples experiences during cryopreservation. This experiment was undertaken to find out factors that affect a post-thaw viability of boar spermatozoa. For this purpose, cryodiluents(BF5, LEY, Soejima and M-Soejima), cryoprotectants(glycerol. ethylene glycol, and propylene glycol), pre-freezing method(dryice-pellet, dryice-straw and L$N_2$vapour-st-raw) and total time required for freezing(2. 5, and 7 h) were compared as a factors. To investigate quality of semen during freezing process, motility(%), normal apical ridges(%, NAR), and proportion of living sperm(%) by flow cytometic analysis were assessed after collection, cooled, pre-frozen and post-thawing. Post-thaw motility of semen diluted with M-Soejima was 52.0%, respectively. When heparin, caffeine or heparin＋caffeine was added to 2nd cryodiluent of M-Soejima during freezing process, the highest motility after thawing was shown at the addition of caffeine (2mM), with 61.7$\pm$2.9% of motility. M-Soejima with heparin or caffeine was significantly higher than that of controI(p＜0.05). The result using glycerol(Gly), ethylene glycol(EG), propylene glycol(PG), and their mixture (Gly＋EG and Gly＋PG) as cryoprotectants, the highest motility was shown at the mixture treatment with Gly plus PG. However, the highest proportion of live spermatozoa was shown at Gly＋EG, there was no significantly difference among treatments(p＞0.05). When semen was pre-frozen with three manners(dryice-pellet, dryice-straw, and L$N_2$ vapor-straw), motility(%) of post-thaw spermatozoa was the highest in the L$N_2$ vapor-straw pre-freezing method of M-Soejima cryodiluent with 57.5% of motility, For a simple, economical and timesaving approach to freezing boar semen, total time required for freezing were 2, 5, and 7 hours, post-thaw motility were 43.8, 45.0 and 38.8%, NAR were 19.5, 22.7 and 28.5%, and viability were 20.8, 19.9 and 22.1%, respectively. This data suggests that boar semen diluted with M-Soejima cryodiluent contained caffeine, using mixture of glycerol and propylene glycol or ethylene glycol as cryoprotectants, frozen with 2 hours, can be taken better motility, NAR, and proportion of live spermatozoa.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.11
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• pp.1007-1018
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• 2009

Hydrocyclone is widely used in industry, because of its simplicity in design, high capacity, low maintenance and operational cost. The separation action of a hydrocyclone treating particulate slurry is a consequence of the swirling flow that produces a centrifugal force on the fluid and suspended particles. In spite of hydrocyclone have many advantage, the application for treatment of urban stormwater case study were rare. We conducted a laboratory scale study on treatable potential of micro particles using hydrocyclone filter (HCF) that was a combined modified hydrocyclone with perlite filter cartridge. Since it was not easy to use actual storm water in the scaled-down hydraulic model investigations, it was necessary to reproduce ranges of particles sizes with synthetic materials. The synthesized storm runoff was made with water and addition of particles; ion exchange resin, road sediment, commercial area manhole sediment, and silica gel particles. Experimental studies have been carried out about the particle separation performance of HCF-open system and HCF-closed system. The principal structural differences of these HCFs are underflow zone structure and vortex finder. HCF was made of acryl resin with 120 mm of diameter hydrocyclone and 250 mm of diameter filter chamber and overall height of 800 mm. To determine the removal efficiency for various influent concentrations of suspended solids (SS) and chemical oxygen demand (COD), tests were performed with different operational conditions. The operated maximum of surface loading rate was about 700 $m^3/m^2$/day for HCF-open system, and 1,200 $m^3/m^2$/day for HCF-closed system. It was found that particle removal efficiency for the HCF-closed system is better than the HCF-open system under same surface loading rate. Results showed that SS removal efficiency with the HCF-closed system improved by about 8~20% compared with HCF-open system. The average removal efficiency difference for HCF-closed system between measurement and CFD particle tracking simulation was about 4%.

• Tuberculosis and Respiratory Diseases
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• v.66 no.4
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• pp.288-294
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• 2009

Background: A lung hyperinflation, or air trapping, caused by expiratory flow-limitation contributes to dyspnea in patients with chronic obstructive pulmonary disease (COPD). Forced expiratory volume in 1 second ($FEV_1$) has served as an important diagnostic measurement of COPD, but does not correlate with patient-centered outcomes such as dyspnea. Therefore, this study was performed to investigate the role of radiologic quantity in evaluating the dyspnea in patients with COPD by measuring lung hyperinflation in chest x-ray and high resolution chest tomography (HRCT). Methods: Fifty patients with COPD were enrolled in this study. Their subjective dyspnea score (modified Borg scale dyspnea index), spirometry, and lung volume were measured. Simultaneous hyperinflations of chest x-ray score ("chest score") and degree of emphysema of HRCT ("HRCT score") were measured. The "chest score" were composed of lung length, retrosternal space width, and height of the arc of the diaphragm and "HRCT score" were composed of severity and extent of emphysema. Results: The mean age of patients was 69 years old and their mean $FEV_1$ was 51.7%. The Borg score significantly correlated with parameters of spirometry and lung volume, including FVC, $FEV_1$, $FEV_1$/FVC, RV, RV/TLC, and DLCO. The Borg score correlated well with "HRCT score", but did not correlate with "chest score". Also, the Borg scale correlates inversely with body mass index. Conclusion: The quantity of emphysema on chest HRCT may serve as an objective marker of dyspnea in patients with COPD.

• Journal of Bio-Environment Control
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• v.29 no.4
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• pp.464-472
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• 2020

We suggest a hydroponic cultivation system combined with a plasma generator to investigate the changes in the growth and functional substance content of lettuces during the cultivation period. Lettuce seedlings of uniform size were planted in semi-DFT after seeding for 3 weeks, and the plasma-activated water was intermittently operated for 1 hour at an 8 hours cycle for 4 weeks. Lettuces grew with or without plasma-activated water with the nutrient solution in hydroponics culture systems. Among the reactive oxygen species generated during plasma-activated water treatment, brown spots and necrosis appeared in the individuals closer to the plasma generating device due to O₃, and there was no significant difference in the growth parameters. While the rutin and total phenolic content of the lettuce shoot grown in the nutrient solution were higher than that of the plasma-activated water, epicatechin contents in plasma-activated water were significantly greater than the nutrient solution. However, in the roots, all kinds of secondary metabolites measured in this work, rutin, epicatechin, quercetin, and total phenolic contents, were significantly higher in the plasma-activated water than the control. These results were indicated that the growth of lettuce was decreased due to the reactive oxygen species such as ozone in the plasma-activated water, but the secondary metabolites in the root zone increased significantly. It has needed to use this technology for the cultivation of root vegetables with the modified plasma-activated water systems to increase secondary metabolite in the roots.

• Journal of the Korea Organic Resources Recycling Association
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• v.14 no.4
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• pp.113-120
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• 2006

Wastewater generated through the food waste recycling process have known high concentration, BOD 20,000~150,000 mg/L, which has to treat to the proper level because of a ban on reclamation. But it is impossible to treat less than 10 days by existing water treatment plant. Ecodays Ltd. is to treat this wastewater during 2~4 days by ER-1, which can simultaneously induce the modified PFR(Plug Flow Reactor) of the oxygen transfer rate, MLVSS concentration, and influent concentration to top from bottom of reactor. We tested the pilot test about low concentration food wastewater(BOD 16,500 mg/L) and high concentration food wastewater(64,431 mg/L) at the food waste recycling plant of H-Gun(20t/d). Hydraulic retention time(HRT) of ER-1 for low concentration food wastewater is 2.5day. In low concentration conditions, ER-1 treatment efficiency is to appear BOD 99%, COD 98%, TN 97%, and TP 96%. While ER-1 process for high concentration food wastewater treatment is composed 2 stages, which are to be HRT 2.5day for law wastewater and HRT 1.5 day for secondary treatment. In high concentration conditions, ER-1 treatment efficiency is to appear BOD 97%, COD 84%, TN 66%, and TP 95%. It is treated without temperature control about high temperature($50^{\circ}C$) to appear low treatment efficiency in high concentration conditions.

• Journal of the Mineralogical Society of Korea
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• v.25 no.4
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• pp.185-195
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• 2012

Due to the high reduction and sorption capacity as well as the large specific surface area, nanosized mackinawite (FeS) is useful in reductively transforming chlorinated organic pollutants and sequestering toxic metals and metalloids. Due to the dynamic nature in its colloid stability, however, nanosized FeS may be washed out with the groundwater flow or result in aquifer clogging via particle aggregation. Thus, these nanoparticles should be modified such as to be built into permeable reactive barriers. This study employed coating methods in efforts to facilitate the installation of permeable reactive barriers of nanosized mackinawite. In applying the methods, nanosized mackinawite was coated on non-treated silica sand (NTS) and chemically treated silica sand (CTS). For both silica sands, the maximum coating of mackinawite occurred around pH 5.4, the condition of which was governed by (1) the solubility of mackinawite and (2) the surface charge of both silica and mackinawite. Under this pH condition, the maximum coating by NTS and CTS were found to be 0.101 mmol FeS/g and 0.043 mmol FeS/g respectively, with such elevated coatings by NTS likely linked with impurities (e.g., iron oxides) on its surface. Arsenite sorption experiments were performed under anoxic conditions using uncoated silica sands and those coated with mackinawite at the optimal pH to compare their reactivity. At pH 7, the relative sorption efficiency between uncoated NTS and coated NTS changed with the initial concentration of arsenite. At the lower initial concentration, uncoated NTS showed the higher sorption efficiency, whereas at the higher concentration, coated NTS exhibited the higher sorption efficiency. This could be attributed to different sorption mechanisms as a function of arsenite concentration: the surface complexation of arsenite with the iron oxide impurity on silica sand at the low concentration and the precipitation as arsenic sulfides by reaction with mackinawite coating at the high concentration. Compared to coated NTS, coated CTS showed the lower arsenite removal at pH 7 due to its relatively lower mackinawite coating. Taken together, our results indicate that NTS is a more effective material than CTS for the coating of nanosized mackinawite.