• Membrane and Water Treatment
• /
• v.6 no.5
• /
• pp.365-378
• /
• 2015

Herein, the preparation of anion exchange membrane (AEM) from brominated poly(2,6-dimethyl 1,6-phenylene oxide) BPPO and dimethylaniline (DMA) by phase-inversion process is reported. Anion exchange membranes (AEMs) are prepared by varying the DMA contents. Prepared AEMs show high thermal stability, water uptake (WR) around 202% to 226%, dimensional change ratios of 1.5% to 2.6% and ion exchange capacities (IECs) of 0.34 mmol/g to 0.82 mmol/g with contact angle of $59.18^{\circ}$ to $65.15^{\circ}$. These membranes are porous in nature as confirmed by SEM observation. The porous property of membranes are important as it could reduce the resistance of transportation of ions across the membranes. They have been used in diffusion dialysis (DD) process for recovery of hydrochloric acid (HCl) from the mixture of HCl and ferrous chloride ($FeCl_2$). Presence of $-N+(CH_3)_2C_6H_5Br^-$ as a functional group in membrane matrix facilitates its applications in DD process. The dialysis coefficients of hydrochloric acid ($U_H$) of the membranes are in range of 0.0016 m/h to 0.14 m/h and the separation factors (S) are in range of 2.09 to 7.32 in the $HCl/FeCl_2$ system at room temperature. The porous membrane structure and presence of amine functional group are responsible for the mechanism of diffusion dialysis (DD).

• Economic and Environmental Geology
• /
• v.30 no.1
• /
• pp.35-49
• /
• 1997

The coal formation of the Deokpyeong area are interbedded along metapelites of the Ogcheon Supergroup, which are composed mainly of graphite, quartz, muscovite and associated with small amounts of biotite, chlorite, pyrite and barite. The ratios of $SiO_2/Al_2O_3$, $Al_2O_3/Na_2O$ and $K_2O/Na_2O$ of the coaly metapelite are variable and wide range from 1.80 to 10.21, from 27.8 to 388.8 and from 7.6 to 61.8, respectively. These coal formation were deposited in basin of marine environments, and the REE of these rocks are not influenced with metamorphism and hydrothermal alterations on the basis of $Al_2O_3$ versus La, La against Ce, the ratios of La/Ce (0.19 to 0.99) and Th/U (0.02 to 4.75). These rocks also show much variation in $La_N/Yb_N$ (1.19 to 22.89), Th/Yb (0.14 to 21.43) and La/Th (0.44 to 13.67), and their origin is explained by derivation from a mixture of sedimentary and igneous rocks. The wide range in trace and REE element characteristics as Co/Th (0.12 to 2.78), La/Sc (0.33 to 10.18), Sc/Th (0.57 to 5.73), V/Ni (8 to 2347), Cr/V (0.02 to 0.67) and Ni/Co (1.56 to 32.95) of these coaly metapelites argues for inefficient mixing of the various source lithologies during sedimentation. Deep to pale green barium-vanadium muscovites (vanadium-oellacherite) have been found in this coal formations. Modes of occurrence and grain size of muscovite are heterogeneous, but most of the barium and vanadium-bearing muscovites occur along the boundaries between graphite and quartz grains, ranging from 200 to $350{\mu}m$ in length and from 40 to $60{\mu}m$ in width. Results of X-ray diffraction data of the minerals characterized to be monoclinic system with $a=5.249{\AA}$, $b=8.939{\AA}$, $c=20.924{\AA}$ and ${\beta}=95.894^{\circ}$. Representative chemical formula of the muscovite was $(Na_{0.09}K_{1.44}Ba_{0.46})(Al_{2.75}Ti_{0.07}V_{0.56}Fe_{0.08}Mg_{0.50})(Si_{6.12}Al_{1.88})O_{22}$. The V possibly substitute octahedral Al, and the Ba is coupled substitution of $K^+Si^{4+}=Ba^{2+}Na^+Ca^{2+}$, which compositional ranges of V and Ba are from 0.42 to 0.69 and from 0.34 to 0.56 based on $O_{22}$, respectively. Formation mechanism of the barium-vanadium muscovites in the coaly metapelite is shown that the formed by high pressure and temperature from regional metamorphism origanated during diagenesis at the interface between a basinal brine and organic matter.

• Journal of Korean Academy of Nursing
• /
• v.12 no.1
• /
• pp.39-52
• /
• 1982

Nosocomial infection is important in the management of the nursing care and has been found to be related with the airborne microbes contamination. The purpose of this study is to identify the differences of the airborne microbes between hospitals, nursing units, days and times and to identify the difference in the types of microorganisms between hospitals, nursing units, days and times. This study was conducted from May 25, to July 10, 1981, according to R. Koch's methods for quantative samplings of airborne microbes and the results of this study were reviewed in a statistical method. The following conclusions were obtained: 1. There was a significant difference in the types of airborne microbes between 8 hospitals (F=5.0491, p<0.01) 2. There was a significant difference in the types of airborne microbes between surgical, medical, nursery, 1.C.U., operating theatre and outpatient nursing unit. (F=2.1764, p<0.05) 3. There was not a significant difference in the types of airborne microbes between Monday, Thursday and Saturday (F= 1.6365, p>0.05) 4. There was a significant difference in the types of airborne microbes between AM 7 : 00, AM 11：00 and PM 3 : 00. (F=7.2951, p<0.01) 5. 4061 colonies were divided into more 48 types and the classification was as follows. gram positive cocci (2024 colonies) 49.3% gram positive bacillus (1211 colonies) 29.8% gram negative bacillus (577 colonies) 14.2% fungus(200colonies) 4.9% gram negative cocci (41 colonies) 1.0% other's(8 colonies) 0.3% 6. There was a significant difference of airborne microbes between 8 hospitals. (F=7.7943, P<0.01) 7. There was not a significant difference of airborne microbes between 6 nursing units. (F= 1.8461, P>0.05) outpatient nursing unit : 12.6 colonies surgical nursing unit. 10.4 colonies Medical nursing unit : 9.8 colonies nursery nursing unit : 9.4 colonies operating theatre nursing unit：8.2 colonies Intensive care nursing unit : 7.8 colonies 8. There was not a significant difference of airborne microbes between Monday, Thursday and Saturday. (F=1.4371, p>0.05). Saturday : 11.0 colonies Monday : 9.1 colonies Thursday : 9.1 colonies 9. There was a significant difference of airborne microbes between A. M. 7 ; 00, A. M. 11 : 00 and P .M. 3：00 (F=7.6658, p<0.05) P. M. 3 : 00 : 12.2 colonies A. M. 11 : 00 : 10.0 colonies A. M. 7 : 00 : 7.1 colonies.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2010.08a
• /
• pp.91-91
• /
• 2010

본 논문은 펄스 직류전원 (Pulse DC) 플라즈마 소스와 반응성 가스인 $CF_4$와 불활성 가스인 Ar를 혼합하여 산업에서 널리 사용되는 유기고분자인 Polymethylmethacrylate (PMMA), Polyethylene terephthalate (PET), 그리고 Polycarbonate (PC) 샘플을 건식 식각한 결과에 대한 것이다. 각각의 샘플은 감광제 도포 후에 자외선을 조사하는 포토레지스트 방법으로 마스크를 만들었다. 펄스 직류전원 플라즈마 시스템을 사용하면 다양한 변수를 줄 수 있다는 장점이 있다. 공정 변수는 Pulse DC Voltage는 300 - 500 V, Pulse DC reverse time $0.5{\sim}2.0\;{\mu}s$, Pulse DC Frequency 100~250 kHz 이었다. 변수 각각의 값이 높아질수록 고분자의 식각률이 높아졌다. 특히, PMMA의 식각률이 가장 높았으며 PET, PC 순이었다. 샘플 중 PC의 식각률이 가장 낮은 이유는 고분자 결합 중에 이중결합의 벤젠 고리 모양을 포함하고 있어 분자 결합력이 비교적 높기 때문으로 사료된다. 기계적 펌프만을 사용한 공정 전 압력은 30 mTorr이었다. 쓰로틀 밸브를 완전 개방한 상태에서 식각 공정 중 진공 압력은 $CF_4$ 가스유량이 늘어날수록 증가하였다. 식각률 역시 $CF_4$ 가스유량(총 가스 유량은 10 sccm)이 많을수록 증가함을 보여주었다 (PMMA: 10 sccm $CF_4$에서 330 nm/min, 3.5 sccm $CF_4$/6.5 sccm Ar에서 260 nm/min., PET: 10 sccm $CF_4$에서 260 nm/min, 3.5 sccm $CF_4$/6.5 sccm Ar에서 210 nm., PC: 10 sccm $CF_4$에서 230 nm, 3.5 sccm $CF_4c$/6.5 sccm Ar에서 160 nm). 이는 펄스 직류전원 플라즈마 식각에서 $CF_4$와 Ar의 가스 혼합비를 조절함으로서 고분자 소재의 식각률을 적절히 변화시킬 수 있다는 것을 의미한다. 표면 거칠기는 실험 후 표면단차 측정기와 전자 현미경 등을 이용하여 식각한 샘플의 표면을 측정하여 알 수 있었다. 실험전 기준 샘플 표면 거칠기는 PMMA는 1.53nm, PET는 3.1nm, PC는 1.54nm 이었다. 식각된 샘플들의 표면 거칠기는 PMMA는 3.59~10.59 nm, PET은 5.13~11.32 nm, PC는 1.52~3.14 nm 범위였다. 광학 발광 분석기 (Optical emission spectroscopy)를 이용하여 식각 공정 중 플라즈마 발광특성을 분석한 결과, 탄소 원자 픽 (424.662 nm)과 아르곤 원자 픽 (751.465 nm, 763.510 nm)의 픽의 존재를 확인하였다. 이 때 탄소 픽은 $CF_4$ 가스에서 발생하였을 것으로 추측한다. 본 발표를 통해 펄스 직류전원 $CF_4$/Ar의 고분자 식각 결과에 대해 보고할 것이다.

• Asian-Australasian Journal of Animal Sciences
• /
• v.15 no.2
• /
• pp.222-237
• /
• 2002

Effects of high and low levels of feeding with or without protected protein on the performance of lactating goats were studied. Twenty four German Fawn goats either from 1st ($43.37{\pm}3.937$ kg and 2 year old) or 3rd $62.64{\pm}6.783$ kg and 4-5 year old) parity were used for the trial. Feeding levels were 7.2 (I) and 5.2 (II) MJ ME/litre of milk of 3.5% fat in addition to that of the maintenance allowance. At each feeding level, diet had either unprotected (U) or formaldehyde protected (P) soya-meal. Thus, four diets were IU, IP, IIU and IIP, having six animals in each. The diets were composed of hay and pellet (10:4:1 of beet pulp : barley : soya-meal). Effect of feeding level, protein protection, parity, health status and kid number on intake, milk yield, milk composition, growth rate of goats were recorded across the 21 weeks of study. High feeding level resulted increase (p<0.001) in estimated metabolizable energy (ME) and metabolizable protein (MP) availability. Dietary inclusion of protected soya-meal increased (p<0.001) the estimated MP but not the ME availability. Animals in 1st parity ate more (p<0.001) DM (111 vs. 102 g/kg $W^{0.75}$/d) than those in 3rd parity. Animals with twin kids (110 g/kg $W^{0.75}$/d) had higher (p<0.001) DM intake than those with single kid (102 g/kg $W^{0.75}$/d). Fat (4%) corrected milk (FCM) yield was not effected by high (1,924 g/d) or low (1,927 g/d) feeding level but increased (p<0.001) with protected (2,166 g/d) compared with unprotected (1,703 g/d) soya-meal. FCM yield for four dietary combinations were 1,806, 2,078, 1,600 and 2,254 g/d for diets IU, IP, IIU and IIP, respectively. For unit increase (g) in estimated MP availability relative to ME (MJ) intake, FCM yield increased ($1,418{\pm}275.6$) g daily ($r^2$=0.58; p<0.001). Milk fat (3.14 vs. 3.54%; p<0.001) and protein (2.94 vs. 3.04% p<0.05) contents were lower at high than the low feeding level. Protected protein increased (p<0.001) the fat, lactose and net energy (NE) content of milk. Milk urea concentration of 175, 183, 192 and 204 mg/l for diets IU, IP, IIU and IIP, respectively indicated lower RDP content of these diets. The RDP contents were 6.97, 6.70, 7.30 and 6.83 g/MJ of ME for diets IU, IP, IIU and IIP, respectively. Live weight change over the experimental period were 41, 6, 17 and 19 g/d. Absence of any positive response of high feeding was probably due to inefficient rumen fermentation resulting from inadequate RDP supply. Protected protein improved production performance apparently by increasing MP:ME ratio in the absorbed nutrient.

• Food Science of Animal Resources
• /
• v.31 no.1
• /
• pp.47-53
• /
• 2011

Salmonella enterica serovar Typhimurium (ST) is one of the most common serovars isolated from humans and animals. It has been suggested that ST infections in Koreans are largely due to the consumption of contaminated pork and beef. To investigate the genotypes, phage types, and antimicrobial resistance patterns for ST isolates of different origins, a total of 70 ST strains, including 19 isolates from humans, 44 isolates from pigs, and 6 isolates from cattle, were analyzed using pulsedfield gel electrophoresis (PFGE), phage typing, and antimicrobial susceptibility tests. Forty-three distinct PFGE patterns were generated from 70 ST isolates, which were grouped into 14 PFGE groups (from A to N) at the level of 75% similarity. The most prevalent group was the A (A1-A17 subtypes) group, encompassing 54.5% (38/70) of ST isolates. ST isolates from pigs and cattle mostly belong to groups A and L, whereas ST isolates from humans mostly belong to groups F and C. Antimicrobial susceptibility tests using 11 antimicrobial agents showed that resistance to tetracycline (TE) (81.4%) was highly prevalent, followed by streptomycin (S) (64.3%) and nalidixic acid (NA) (31.4%) resistance. A total of seventeen antimicrobial resistance patterns were observed. Only 8.6% of isolates, including a reference strain, were susceptible to all antimicrobial agents tested. The most prevalent resistance pattern was TE-S (37.1%), which was seen in 66.6% of bovine, 40.8% of swine and 21.1% of human isolates. Three ST isolates from humans (15.9%) showed resistance to 7-8 antimicrobials. The most predominant phage type (PT) was U302 (64.3%), followed by DT170 (10.0%). PFGE types did not coincide with antimicrobial resistance patterns and phage types; therefore, the combination of those types allowed for further differentiation between tested ST isolates.

• Korean Journal of Weed Science
• /
• v.14 no.1
• /
• pp.34-41
• /
• 1994

To better understand the allelopathic effect of sorghum(Sorghum vulgare L.), the inhibitory activities of water extracts of the stem, leaf and root, and of residues of the stem to major crops and weeds associated with them were evaluated. The allelopathic activity of sorghum plants was species specific, and depended on source and concentration. Germination, and shoot and root length of all test species were inhibited by the different concentrations of the stem extract. Among the crop species, radish showed the most inhibition, followed by wheat and rice. Maize was the least sensitive species. Of the weed species, Ipomoea triloba was most inhibited, followed by Echinochloa colona and Rottboellia cochinchinensis. The water extracts of leaves, stems, and roots significantly inhibited germination and seedling growth in E. colona and radish. The stem extract gave the greatest inhibitory effect on E. colona while all three extracts produced similar response in radish. In the greenhouse trial, sorghum stem residue placed on the soil surface as mulch significantly inhibited seedling growth in E. colona and radish, but not that in rice.

• The Journal of Korean Academy of Prosthodontics
• /
• v.46 no.2
• /
• pp.209-216
• /
• 2008

Statement of problem: It is difficult about assessing the loosening tendency of conical connection type implant after cyclic loading with diamond like carbon coating one-piece abutments, and also about the retightening effect. Purpose: This study was performed to investigate the influence of one-piece abutment screw retightening after $5.0{\times}10^{4}$ cyclic loading and Diamond like coating Material and methods: Thirty two ITI implant were divided to 4 groups. Group 1,3-titanium abutment, group 2,4 - diamond like carbon coated abutment. Group 1,2 - $20.0{\times}10^{4}$ cyclic loading after $5.0{\times}10^{4}$ cyclic loading, Group 3,4- after $20.0{\times}10^{4}$ Cyclic loading. After cyclic loading, periotest values were taken and removal torque values of abutments were measured with a digital torque gauge. Results: 1. The removal torque of group 2 after $5.0{\times}10^{4}$ cyclic loading is slightly greater than the other groups but not significantly higher than others (P>0.05). 2. The final removal torque values after $20.0{\times}10^{4}$ cyclic loading of group 1 is bigger than group 3, and group 2 is bigger than group 4, but not significantly higher (P>0.05). 3. The final removal torque values after $20.0{\times}10^{4}$ cyclic loading of all groups are not significantly different (P>0.05).

• Journal of Preventive Medicine and Public Health
• /
• v.22 no.3 s.27
• /
• pp.328-336
• /
• 1989

27 shipyard welders were diagnosed as pneumoconiosis and suspected pneumoconiosis(1976-1988) by chest radiographs and were observed over three years. 27 welders were divided into three groups by the state of exposure to welding fume i.e. cessation, decresase or continuity of exposure. And we observed the changing pattern of the chest radiographs of 27 welders with the passage of time. The results were as follows; 1. Grour I (ceased exposure to welding fume) were 10 cases(3 cases: suspected pneumoconiosis,7 cases: pneumoconiosis). Chest radiographs of all cases were improved. The shape and size of small opacities was improved in 6 cases(85.7%) and did not changed in 1 case(14.3%) out of 7 pneumoconiosis welders. 2. Group II (decreased exposure to welding fume) were S cases(2 cases: suspected pneumoconiosis, 3 cases: pneumoconiosis). Chest radiographs were progressed in 2 cases(40%), did not changed in 1 case(20%), were improved in 2 cases(40%) out of 5 cases. The shape and size of small opacities was progressed in 1 case(33.3%) and was improved in 2 cases(66.7%) out of 3 pneumoconiosis welders. 3. Group III(continued expoxsure to welding fume) were 12 cases(1 case: suspected pneumoconiosis, 11 cases: pneumoconiosis). Chest radiographs were progressed in 9 cases(75%), did not changed in 3 cases(25%) out of 12 cases. The shape and size of small opacities was progressed in 1 case(9.1%) and did not changed in 10 cases(90.9%) out of 11 pneumoconiosis welders. 4. The average duration for development into suspected pneumoconiosis was 6.6 years and for progression of each one category after that was 2.2 years(p<0.01). The radiological appearance of pneumoconiosis had disappeared or decreased after cessation of exposure to the welding fume. So that, early detection and control e.g., change of department of pneumoconiosis of welders by screening program will be important for medical surveillance of welders.

• The Journal of Korean Society for School & Community Health Education
• /
• v.22 no.4
• /
• pp.49-60
• /
• 2021

Objectives: Laboratories have various latent physical, chemical, biological, and ergonomical factors according to the diversification and fusion of research and development activities. This study aims to investigate the chemical exposure concentrations of college laboratories and evaluate their health risks, and use them as basic data to promote the health of college students. Methods: The sampling and analysis of harmful chemicals in the air in laboratories were performed using Method 1500 of the U.S. National Institute for Occupational Safety and Health (NIOSH)의 Method 1500. The harmful chemicals in the laboratories were divided into carcinogenic and non-carcinogenic chemicals. Risk assessment was performed using the cancer risk (CR) for carcinogenic chemicals and using the hazard index (HI) for non-carcinogenic chemicals. Results: The harmful chemicals in college laboratories consisted of acetone, diethyl ether, methylene chloride, n-hexane, ethyl acetate, chloroform, tetrahydrofuran, toluene, and xylenes. They showed the highest concentrations in laboratories A (acetone 0.001~2.34ppm), B (chloroform 0.95~6.35ppm), C (diethyl ether 0.08~8.68ppm), and D (acetone 0.07~14.96ppm). The risk assessment result for non-carcinogenic chemicals showed that the HI of methylene chloride was 2.052 for men and 2.333 for women, the HI of N-hexane was 4.442 for men and 5.05 for women. Thus, the HI values were higher than 1. The risk of carcinogenic chemicals is determined by an excess cancer risk (ECR) value of 1.0×10^-5, which means that one in 100,000 people has a cancer risk. The ECRs of chloroform exceeded 1.0×10^-5 for both men and women, indicating the possibility of cancer risk. Conclusion: College laboratories showed the possibility of non-carcinogenic health risks for methylene chloride, n-hexane, tetrahydrofuran (THF), toluene, and xylenes, and carcinogenic health risks for chloroform, methylene chloride. However, this study used the maximum values of measurements to determine the worst case, and assumed that the subjects were exposed to the corresponding concentrations continuously for 8 hours per day for 300 days per year. In consideration of the nature of laboratory environment in which people are intermittently exposed, rather than continuously, to the chemicals, the results of this study has an element of overestimation.