• Applied Chemistry for Engineering
• /
• v.7 no.5
• /
• pp.877-887
• /
• 1996

The ideal membranes for membrane-covered oxygen probes system should be selectively permeable for oxygen and chemically inert, and have good mechanical strength. Polysulfone(PSf) was selected to develop the membrane for membrane-covered oxygen electrodes system. PSf membranes have properties such as good reproducibility, good mechanical strength, chemical inertness, and high heat resistance. PSf membranes were cast from polymer solution on the glass plate at constant temperature, and casting solvents used were tetrahydrofuran(THF), methylene chloride, and N-methyl-2-pyrrolidone(NMP). Tricresyl phosphate(TCP) as plasicizer was added to PSf to increase the softness of membrane. The permeation characteristics were observed for pure oxygen and nitrogen through pure PSf membranes by variable volume method and membrane-covered electrode system. The permeability coefficients of oxygen and nitrogen measured by variable volume method were slightly decreased with increasing of upstream pressure. The permeation properties of PSf membrane using methylene choride as casting solvent were not affected by the PSf amount of polymer solution. The permeability coefficients of oxygen and nitrogen for PSf membrane containing TCP were very slightly lower than those for pure PSf membrane, but ideal separation factors were slightly higher. The flexibility of PSf membrane containing 2wt% TCP was better than that of pure PSf membrane. It was expected that this increase in flexibility would solve the difficulty of fixing the membrane to the cathode. The membrane-covered oxygen probes system was composed of anode, cathode and electrolyte. The type of the anode was Ag/AgCl half-cell, that of cathode was Ag, and the electrolyte was 4N KCl solution. The result of sampled current voltametry for PSf membrane showed the plateu region at -0.3V~-1.0V. The correlation coefficient of oxygen partial pressure versus current for PSf membrane was relatively high, 0.99949. It was concluded that PSf membrane was the good candidate for the membrane-covered oxygen probes system.

• Journal of Soil and Groundwater Environment
• /
• v.12 no.2
• /
• pp.9-19
• /
• 2007

This study investigated the interaction between groundwater and stream water systems, which is caused by the artificial weir on streambed, enforcing external stresses on the groundwater system. The study area is in Nami Natural Recreation Woods located in Chungcheongnam-do Geumsan-gun Nami-myeon Geoncheon-ri. In this study both of hydrophysical methods (hydraulic head) and hyrdochemical investigations (pH, EC, major ion analysis) were applied. In order to identify the relationship between each of study results, cross-correlation analysis is performed. From results of hydrophysical methods, water level fluctuation at BH-14, installed by the weir, shows the double-recession pattern much more frequently and much higher amplitudes than the fluctuation at each of other monitoring wells. Using the results by hydrochemical investigations, hydrochemical properties at BH-14 is similar to the hydrochemical characteristics in stream water. To analyze the interrelationships between the results from each of applied methods, cross-correlation analysis was applied. Results from the correlation analyses, water levels at BH-14 and stream weir showed the highest cross-correlation in hydrophysical aspects. On the other hand, the correlation between stream weir and bridge was the highest in hydrochemical aspects. The difference between the results from each of methods is due that the hydrophysical response at BH-14, such as water level, is induced by the pressure propagation-not with mass transfer, but the hydrochemical interaction, caused by mass transport, takes much more times. In conclusion impermeable artificial weir on streambed changes the interfacial condition between the stream and surrounding aquifers. The induced water flux into the groundwater system during flood period make water level at BH-14 increase instantly and groundwater quality higly similar to the quality of stream water. Referred similarities in both of water level and water quality at BH-14 become much higher when water level at weir grow higher.

• Research in Community and Public Health Nursing
• /
• v.7 no.2
• /
• pp.420-436
• /
• 1996

The goal of this study is to explore different risk factors for smoking and look at the relationships between knowledge, attitudes, and behavioral intentions regarding smoking among schoolchildren, in order to reduce teenage smoking. To achieve this goal a self-administered questionaire regarding smoking was provided to schoolchildren in the 7th and 8th grades in one junior high school in Jerusalem. The schoolchildren were exposed to 10-12 hours of a smoking prevention intervention program. The questionaire focused primarily on the personal characteristics, social environment, knowledge, attitudes, practices, and behavioral intentions of the children. Crosstabs were performed on each variable to determine if significant associations exist among the different variables. The statistical computer, package, SPSS PC, was used to manipulate the data along with Chi-square test. The findings were as follows : About 11% of the children aged 12-14 have ever smoked or are smoking currently, and about 24.0% of those who ever smoked started smoking at the age of 10. Boys smoke more(p<.01), poorer students(by self-perception of school performance) smoke more, and those who had peers who were smokers were more likely to smoke(p<.05). The percentage of the children who reported that either father or mother smoked was about 30%, but no statistical association was found between parental smoking and children's smoking, although trends were noted in the expected direction, i.e. more smokers among children of smokers. Only 1.1% of the children intended to smoke in the future, and 98.0% of the children indicated that they can or they might be able to withstand social pressure. Seventy percent of the children demonstrated medium to high knowledge about smoking, Males, 8th graders, better students, and those without friends who smoke had higher social pressure showed more negative attitudes(p<.01). Those with non-smoking siblings showed more negative behavioral intentions regarding smoking(p<.01), and better students showed more negative behavioral intentions. Those who had higher knowledge scores showed more negative attitudes towards smoking, but not significantly so. Those who had very negative behavioral intentions showed highly significant negative attitudes towards smoking(p<.01).

• Journal of Chest Surgery
• /
• v.41 no.5
• /
• pp.568-572
• /
• 2008

Background: Minimally invasive surgery is currently popular, but this has been applied very sparingly to cardiac surgery because of some limitations. Our study evaluated the safety and efficacy of atrial septal defect (ASD) closure through a video-assisted mini-thoracotomy. Material and Method: Fifteen patients were analyzed. Their mean age was $31{\pm}6$ years. The mean ASD size was $24{\pm}5mm$ and there were 3 cases of significant tricuspid regurgitation. The working window was made through the right 4th intercostal space via a $4{\sim}5cm$ inframammary skin incision, CPB was conducted with performing peripheral cannulation. After cardioplegic arrest, the ASDs were closed with a patch (n=11) or direct sutures (n=4), and the procedures were assisted by using a thoracoscope. There were 3 cases of tricuspid repair and 1 case of mitral valve repair. The mean CPB time and aortic occlusion time were $160{\pm}47\;and\;70{\pm}26 $minutes, respectively. Result: There was no mortality, but there were 3 minor complications (one pneumothorax, one wound dehiscence and one arrhythmia). The mean hospital stay was $5.9{\pm}1.8$ days. The mean follow-up duration was $10.7{\pm}6.4$ months. The follow-up echocardiogram noted no residual ASD or significant tricuspid regurgitation. Three patients suffered from pain or numbness. Conclusion: This study showed satisfactory clinical and cosmetic results. Although the operative time is still too long, more experience and specialized equipment would make this technique a good option for treating ASD.

• Korean Journal of Environment and Ecology
• /
• v.18 no.3
• /
• pp.306-315
• /
• 2004

Yangjae stream, stretching through Seocho-gu and Gangnam-gu, is a representative city stream with its environmentally friendly stream makeover project model, launched in 1995. The district of Gangnam-gu, the subject of this study, is under high pressure from the residents for its use as a huge residential areas close to the stream. The study has two main purposes. The first is to identify the condition and characteristic of utilization of Yangjae stream which is currently being increased in use by the stream restoration. Secondly, the study aims to suggest the environment-friendly management to accomplish arrangement of the naturally friendly stream based on the identification survey, The result from the user survey with 303 valid answer sheets show that the people from neighboring residential areas use this stream a lot doing exercising(51.8%) and taking a walk(24.4%) in their free time. Also regular use rate is high, and people are likely to use it alone(30.4%) or as a family(28.4%). With regard to the need of facility increase, even though the respondents required resting places in the shade(80.8%) most, overall, additional introduction of facilities was analyzed as unnecessary(78.8%). safety issue(22.0%) and a lack of convenience facilities(17.6%) and resting places in the shade(16.6%) are pointed as main problems while the users are generally satisfied(59.5%) with the stream. Improving walk-way and planting trees for shade on the slope were designed as a solution for these problems. For securing safety through improvement of walk-way, the scattering of pressure of current walk with building new walk using berms was presented. In order to increase safety on the walk-way(see above figure), the study proposes to build a new walk-way with berms to disperse excessive pressure. It also suggests the tree planting to provide shade in the stream and to make a provision for the planting of forest trees in the current law.

• The Journal of the Petrological Society of Korea
• /
• v.7 no.2
• /
• pp.77-97
• /
• 1998

We analyzed geochemical and radiogenic isotope data to investigate the genesis and source characteristics of the Onjeongri granite in the northern part of the Gyeongsang Basin. Field observation and K-Ar ages confirm late Cretaceous intrusion (ca. 87 Ma) of the Onjeongri granite. The hornblende geobarometery gives less than 2 kbar for the emplacement pressure of the Onjeongri granite. Geochemical and isotopic compositions suggest that the Onjeongri granite was formed in a relatively immature arc system. $SiO_2$ contents show a negative linear relationship with initial $^{87}Sr/^{86}Sr$ ratios, and an apparent positive correlation with $^{207}Pb/^{204}Pb$ ratios, suggesting an incomplete mixing or assimilation. However, the isotopic data known for any exposed rocks of the study area do not fit as an endmember, implying that the contaminant might reside in the lower crust. A review of published isotopic ages, geochemical, and Sr and Nd isotopic data for the Cretaceous to Tertiary granites in the Gyeongsang Basin indicates the followings. 1) Granitic magmatism in the Gyeongsang Basin were episodic. 2) Granitic rocks in the basin were derived from young (< 0.9 Ga) lower crust, and their isotopic signatures reflect heterogeneous source region. Geochemical and isotopic signatures of granitic rocks in the basin are difficult to explain by upper crustal contamination. 3) Granites in the Gyeongsang Basin have closely related to those in the San in Belt of the Inner Zone of Southwest Japan in terms of age, petrography, and isotopic and geochemical composition. 4) Sr-Nd isotopic signatures of the Onjeongri granite are relatively primitive compared with granitic rocks in the other parts of the Gyeongsang Basin and in the Inner Zone of Southwest Japan.

• The Journal of the Petrological Society of Korea
• /
• v.15 no.1 s.43
• /
• pp.25-38
• /
• 2006

Metamophic rocks of Samcheog area, northeastern Yeongnam massif, was studied petrochemically. This area includes Precambrian Hosanri Formation (schists and gneisses) and granitoid (Icheon granitic gneiss, leucocratic granite and Hongjesa granite), Cambrian sedimentary rocks, and Cretaceous sedimentary and acidic volcanic rocks. Hosanri formation is composed of quartz+plagioclase+K-feldspar+biotite+muscovite+granet${\pm}$cordierite${\pm}$sillimanite. Mineral assemblage of biotite granitic gneiss, which is massive granodioritic rock with weak foliation, is similar to Hosanri formation. According to mineral assemblages, metamorphic rocks of studied area can be divided into two metamorphic zones (garnet and sillimanite zones). From Icheonri area, major, trace and rare earth element data of biotite granitic gneiss and luecocratic granite suggest that source rock is politic rocks of Hosanri formation and source magma was formed by anatexis and experienced fractionation of plagioclase. Trace element diagram show collisional environment such as syn-collisional, volcanic arc granite. Orientation of faults in study area have three maximum concentrations, $N54^{\circ}\;W/77^{\circ}\;SW,\;N49^{\circ}\;W/81^{\circ}\;NE\;and\;N10^{\circ}\;W/38^{\circ}\;NE$. Structure analysis suggests that faults in study area ware formed by uplift and compression. Faulting age is guessed after Tertiary because some shear joints is developed in dikes to intrusive Cretaceous acidic volcanic rock. Hosanri formation and Icheon granitic gneiss had experienced similar deformation history because they have maximum concentration to foliations, $N89^{\circ}\;E/55^{\circ}\;SE\;and\;N80^{\circ}\;E/45^{\circ}\;SE$, respectively.

• Journal of Chest Surgery
• /
• v.31 no.7
• /
• pp.679-683
• /
• 1998

From June 1995 to May 1997, we have implanted 52 Sorin Bicarbon mechanical valves in 41 patients. They were 16 men and 25 women, and their mean age was 47.4${\pm}$14.8(range; 18∼74 y.o.). 35(27 mm∼31 mm) were in mitral position, 15(19 mm∼25 mm) in aortic position, and 2(31 mm) in tricuspid position. 3 CABGs and a tumor excision were taken concomittantly. 35 patients were primary operation, and 6 were re-do operations. By intraoperative transesophageal doppler echocardiography, transvalvular peak/mean pressure gradient was 6.1${\pm}$2.7/2.4${\pm}$1.4 mmHg in mitral position and 27.6/10.7 mmHg in aortic position. The effective valve opening area in mitral position was 3.2${\pm}$0.6 cm2. Follow-up was total 508.6 patient-months, and mean follw-up was 12.7${\pm}$9.2 months. NYHA class was improved from 2.6${\pm}$0.6 to 1.2${\pm}$0.3 in average postoperatively. During that period, there was no operative death. 2 late non-valve related deaths were occurred. One was died of COPD, and the other was possible acute myocardial infarction. Among 7 postoperative complications, one valve related complication(minimal paravalvular leakage) was noticed. In conclusion, Sorin Bicarbon mechanical valve is believed one of the safe choice in clinical settings. It showed excellent hemodynamic and mechanical functions, and very low postoperative valve related complications in short term clinical experience.

• Journal of Yeungnam Medical Science
• /
• v.24 no.2
• /
• pp.206-215
• /
• 2007

Background : The prone position is often used for operations involving the spine and provides excellent surgical access. The complications associated with the prone position include ocular and auricular injuries, and musculoskeletal injuries. In particular, the prone position during general anesthesia causes hemodynamic changes. To evaluate the cardiovascular effects of the prone position in surgical patients during general anesthesia, we investigated the effects on hemodynamic change of the prone position with the Jackson spinal surgery table. Materials and Methods : Thirty patients undergoing spine surgery in the prone position were randomly selected. After induction of general anesthesia, intra-arterial and central venous pressures (CVP) were monitored and cardiac output was measured by $NICO^{(R)}$. We measured stroke volume, cardiac index, cardiac output, mean arterial pressure, heart rate, CVP and systemic vascular resistance (SVR) before changing the position. The same measurements were performed after changing to the prone position with the patient on the Jackson spinal surgery table. Results : In the prone position, there was a significant reduction in stroke volume, cardiac index and cardiac output. The heart rate, mean arterial pressure and CVP were also decreased in the prone position but not significantly. However, the SVR was increased significantly. Conclusion : The degree of a reduced cardiac index was less on the Jackson spinal surgery table than other conditions of the prone position. The reduced epidural pressure caused by free abdominal movement may decrease intraoperative blood loss. Therefore, the Jackson spinal surgery table provides a convenient and stable method for maintaining patients in the prone position during spinal surgery.

• Clinical and Experimental Pediatrics
• /
• v.46 no.1
• /
• pp.37-41
• /
• 2003

Purpose : Although air enema reduction has been known as a good method of diagnosis and treatment of intussusception, it could develop colon perforation. However, there have been few studies about this complication. So we analyzed the risk factors of colon perforation during air enema reduction in patients with intussusception. Methods : We reviewed the charts of 12 colon perforation patients during air enema reduction of intussusception, who were admitted to Gil Medical Center from Jan. 1990 to Dec. 2001. Their age, sex, major symptoms, length of time till hospital visit, types of intussusception, operative findings and pathologic reports were reviewed. Results : Among 657 cases, 596 patients(90.7%) were successfully treated, but 12 patients(1.83%) failed in air enema reduction and had colon perforation. In patients with colon perforation the male to female ratio was 11 : 1, and average age was 5.3 months. The most common symptom at the time of hospital visit was vomiting(91.7%). Cyclic irritability(75.0%), bloody stool(75.0%) and abdominal mass(41.7%) were also noted. The average length of time between symptom onset and hospital visit was 44.7 hours. Types of intussusception were predominantly ileocolic, ileocecal, and ileoileocolic. The site of perforation was most commonly found at the proximal part of intussusception including ascending colon(50%) and transverse colon(50%). Most cases were uncomplicated, and had a single perforation. Pathologic reports showed hemorrhagic necrosis and mesenteric laceration at the site of colon perforation. Complications of colon perforation were tension pneumoperitonium(58.3%), requiring immediate decompression. Conclusion : The chance of colon perforation during air enema reduction increases in cases with small bowel obstruction on simple abdominal x-ray of a patient younger than 6 months, delay in time till hospital visit and higher air pressure during reduction. Therefore more careful investigation is needed in these cases.