• Journal of Korea Soil Environment Society
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• v.4 no.1
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• pp.109-118
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• 1999

Recently, transport parameters of conservative solutes such as KCl in a porous medium have been successfully determined using time domain reflectometry (TDR) . This study was initiated to Investigate the applicability of TDR technique to monitoring the fate of a heavy metal ion in a sandy soil and the distribution of its concentration along travel distance with time. A column test was conducted in a laboratory that consists of monitoring both resident and flux concentrations of $ZnCl_2$in a sandy soil under a breakthrough condition. A tracer of $ZnCl_2$(10 g/L) was injected onto the top surface of the sample as pulse type as soon as a steady-state condition was achieved. Time-series measurements of resistance and electrical conductivity were performed at 10 cm and 20 cm of distances from the inlet boundary by horizontal-positioning of parallel TDR metallic rods and using an EC-meter for the effluent exiting the bottom boundary respectively. In addition. Zn ions of the effluent were analyzed by ICP-AES. Since the mode and position of concentration detected by TDR and effluent were different, comparison between ICP analysis and TDR-detected concentration was made by predicting flux concentration using CDE model accommodating a decay constant with the transport parameters obtained from the resident concentrations. The experimental results showed that the resident concentration resulted in earlier and higher peak than the flux concentration obtained by EC-meter, implying the homogeneity of the packed sandy soil. A close agreement was found between the predicted from the transport parameters obtained by TDR and the measured $ZnCl_2$concentration. This indicates that TDR technique can also be applied to monitoring heavy metal concentrations in the soil once that a decay constant is obtained for a given soil.

• Journal of Chest Surgery
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• v.41 no.6
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• pp.695-702
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• 2008

Background: The choice between a bioprosthetic and a mechanical valve is an important decision in cardiac valve surgery, and the durability of the tissue valve is a major decision factor. We retrospectively evaluated the midterm results of bioprosthetic valve replacement in the mitral position. Material and Method: The subjects were all patients who had undergone mitral bioprosthesis replacement between July 1989 and August 200.7. Among the 216 patients, there were 236 surgical cases. The mean age was $63{\pm}15$ years, and the male to female ratio was 1 : 3. We retrospectively analyzed hospital and outpatient records such that the total follow-up duration amounted to 760.2 patient-years, and the mean follow-up duration was $41.9{\pm}40.7$ months (range $0{\sim}212$ months). Result: Early death occurred in 18 patients (8.3%), and 13 of these underwent concomitant cardiac procedures. The survival rate after 5 years was $79.9{\pm}3.5%$, and the survival rate after 8 years was $65.5{\pm}5.5%$, while freedom from structural valve deterioration (SVD) was $96.2{\pm}2.2%$ at 5 years and $85.9{\pm}5.3%$ at 8 years. Freedom from reoperation was $90.6{\pm}1.7%$ at 5 years and $90.4{\pm}4.2%$ at 8 years, while freedom from reoperation for SVD was $98.1{\pm}1.2%$ at 5 years and $92.3{\pm}4.1%$ at 8 years. On multivariate analysis of preoperative risk factors, small valve size (between 25mm and 27mm) was a significant risk factor for reoperation, and low LV ejection fraction (<40%) was a significant risk factor for SVD and mortality. Conclusion: Survival and freedom from reoperation for SVD in mitral bioprosthesis replacement had acceptable midterm results, but freedom from SVD Was relatively low. In particular, since SVD increased sharply at the eighth postoperative year, frequent follow-up and echocardiograms around that time will be helpful for the early detection of SVD. It will be necessary to conduct further studies involving long-term follow-up and more patients.

• Journal of Technology Innovation
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• v.24 no.1
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• pp.113-142
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• 2016

T-50 exportation to Indonesia embodied an objective of governmental policy and became a catalyst accelerating the exportation of domestic defense industries. Defense industry exportation is recognized as a new growth engine creating economic interests and it became an important policy of the government. This study will suggest an effective direction for the support policy of the defense industry exportation through analysis on factors behind the success of the T-50 exportation to indonesia in the view of policy network. Policy network theory has its efficacy and workability in analyzing what kind of results are yielded from each policy actor's attributes and their interaction during the execution and establishment of the support policy for the defense exportation. The type of policy network of the T-50 exportation to Indonesia was a policy community. Many governmental ministries, defense industry which is the group of interest, and experts from the research institutes have established the Korea Defense Trade Support Center(KODITS) for accomplishing common policy goal with mutually shared sentiment, and sought for a strategy for the success of the defense industry exportation having official and unofficial meeting centering around the KODITS. Although there were oppositions and conflicts among major actors, though forming a cooperative relationship among majority of the actors, policy-wise decision making for the exportation of the T-50 to Indonesia was efficiently carried out. The cooperative relationship was the key in the success of the T-50 exportation. Considering that the policy community from cooperative mutual interaction is efficient in reaching the goal of the defense industry exportation support policy, this study suggests operating government-wise temporary Task Force(TF) to succeed in big exportation projects such as the T-X exportation to the U.S. In addition, institutional and procedural supplementation such as regular meetings among the head of related governmental ministries and etc. are required in order to enhance the mutually cooperative relationship withing the TF.

• Journal of the Mineralogical Society of Korea
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• v.17 no.1
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• pp.61-73
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• 2004

The purposes of this study are to investigate the occurrence, the hydrochemical characteristics and the origin of the $CO_2$-rich springs from the Kangwon Province, and to reanalyze the previous studied results of other researchers. The $CO_2$-rich water samples were collected at 13 locations in the Kangwon Province. The $CO_2$-rich water shows a high $CO_2$ concentration ($P_{CO2}$ 0.787 to 4.78 atm), weak acidic pHs, electrical conductivity values ranging from 422 to 2,280 $\mu$S/cm, and high Fe and F contents. The chemical compositions of $CO_2$-rich water from this study area are classified into three types; $Ca-HCO_3$, Ca(Na)-$HCO_3$, $Na-HCO_3$ types. The chemical data of $CO_2$-rich waters and their host rocks indicate that $Na-HCO_3$ type water are mainly influenced by biotite, K-feldspar granite, and Ca(Na)-HC $O_3$, type water is chiefly influenced by gneiss and carbonate minerals in granite. F and Fe contents of $CO_2$-rich waters are abundant in $Na-HCO_3$, and $Ca-HCO_3$ types, respectively. The results of this study suggest that the chemical composition $CO_2$-rich water is mainly controlled by the mineralogical composition of aquifer host rocks. Oxygen and deuterium isotope data indicate that $CO_2$-rich water is meteoric origin. The $\delta^{13}$C values (-0.3$\textperthousand$ to -6.2$\textperthousand$ PDB) suggest that dissolved carbonates are mainly derived from a deep-seated $CO_2$ and partly from carbonate minerals.

• Progress in Medical Physics
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• v.15 no.1
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• pp.30-38
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• 2004

Purpose: To develop a whole body frame for the purpose of reducing patient motion and minimizing setup error for extra-cranial stereotactic radiotherapy, and to evaluate the repositioning setup error of a patient in the frame. Materials and Methods: The developed whole body frame is composed of a base plate, immobilizer, vacuum cushion, ruler and belts. The dimension of the base plate is 130 cm in length, 50 cm in width and 1 cm in thickness. The material used in the base plate of the frame was bakelite and the immobilizer was made of acetal. In addition, Radiopaque angio-catheter wires were engraved on the base plate for a coordinate system to determine the target localization. The measurement for radiation transmission and target localization is peformed in order to test the utilization of the frame. Also, a Matlab program analyzed the patients setup error by using the patient's setup images obtained from a CCTV camera and digital record recorder (DVR). Results: A frame that is useful for CT simulation and radiation treatment was fabricated. The frame structure was designed to minimize collisions from the changes in the rotation angle of the gantry and to maximize the transmission rate of the Incident radiation at the lateral or posterior oblique direction. The lightening belts may be used for the further reduction of the patient motion, and the belts can be adjusted so that they are not in the way of beam direction. The radiation transmission rates of this frame were measured as 95% and 96% at 10 and 21 MV, respectively. The position of a test target on the skin of a volunteer is accurately determined by CT simulation using the coordinate system in the frame. The estimated setup errors by Matlab program are shown 3.69$\pm$1.60, 2.14$\pm$0.78 mm at the lateral and central chest, and 7.11 $\pm$2.10, 6.54$\pm$2.22 mm at lateral and central abdomen, respectively. The setup error due to the lateral motion of breast is shown as 6.33$\pm$ 1.55 mm. Conclusion: The development and test of a whole body frame has proven very useful and practical in the radiosurgery for extra-cranial cancers. It may be used in determining target localization, and it can be used as a patient immobilization tool. More experimental data should be obtained in order to improve and confirm the results of the patient setup error.

• Applied Chemistry for Engineering
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• v.24 no.5
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• pp.551-557
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• 2013

In the present study, pristine carbon nanotube (p-CNT) and thiolated carbon naotube (t-CNT) electrodes were investigated to improve their detectabilities for cadmium (Cd) and lead (Pb). In addition, we evaluate which reaction mechanism is used when the electrolyte contains both Cd and Pb metals. Square wave stripping was employed for analyzing the sensitivity for the metals. A frequency of 30 Hz, a deposition potential of -1.2 V vs. Ag/AgCl and a deposition time of 300 s were used as optimal SWSV parameters. t-CNT electrodes show the better sensitivity for both Cd and Pb metals than that of p-CNT electrodes. In case of Cd, sensitivities of p-CNT and t-CNT electrodes were $3.1{\mu}A/{\mu}M$ and $4.6{\mu}A/{\mu}M$, respectively, while the sensitivities for Pb were $6.5{\mu}A/{\mu}M$ (p-CNT) and $9.9{\mu}A/{\mu}M$ (t-CNT), respectively. The better sensitivity of p-CNT electrodes is due to the enhancement in the reaction rate of metal ions that are facilitated by thiol groups attached on the surface of CNT. When sensitivity was measured for the detection of Cd and Pb metals present simultaneously in the electrolyte, Pb indicates better sensitivity than Cd irrespective of electrode types. It is ascribed to the low standard electrode potential of Pb, which then promotes the possibility of oxidation reaction of the Pb metal ions. In turn, the Pb metal ions are deposited on the electrode surface faster than that of Cd metal ions and cover the electrode surface during deposition step, and thus Pb metals that cover the large portion of the surface are more easily stripped than that of Cd metals during stripping step.

• Korean Journal of Agricultural Science
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• v.9 no.1
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• pp.260-268
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• 1982

The study has been carried out to investigate the relationship of certain factors to the private owners' attitudes toward forest management. The dependent variable is the attitude toward forest management, and the six independent variables are owner's age, educational level, forestland area, socioeconomic status, communicational and sociopsychological factors. The dependent variables were measured by Likert attitude scale. The data used in the study were obtained from 262 common-and model-forest owners, and analyzed primarily by multiple correlation statistical technique. Major findings of the study are summarized as follows; 1. The average score of common-owners' attitudes toward forest management is significantly lower than that of model-owners'. The scores of such independent variables as age, forestland area, socioeconomic status and communication of common-owners are also significantly lower than those of model-owners', while the significant difference of sociopsychological scores is not recognized between two owner groups. 2. The common-owners' attitudes toward forest management are negatively correlated with age variable, arid positively with other independent variables. On the other hand, the model-owners' are negatively correlated with education variable, arid positively with age, communicational and sociopsychological factors. 3. The multiple correlation coefficient between common-owner' management-attitude scores and six independent variables is 0.6971. About 41 percent of the variance of this attitude cart be explained by sociopsychological factor, and other 7 percent by communicational variable. In case of model-owners, the multiple correlation coefficient is 0.5207, and about 16.2 percent of the variance of the attitude can be explained by sociopsychological factor and 6 percent by age variable. 4. The multiple correlation coefficient between the attitude scores of all-owners arid such seven different personality factors as fatalistic, trustful, cooperative, ambitious, conservative, scientific and traditional familism personalities is 0.6566. In this case, 15 percent of the variance of the management-attitude can be explained by ambitious personality, and 11.2 percent by traditional familism. 5. The private forest owners' attitudes toward forest management are greatly affected by sociopsychological and communicational factors. The emphasis should be therefore put on the forestry extension works to induce private owners to management practices.

• The Journal of the Petrological Society of Korea
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• v.7 no.2
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• pp.69-76
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• 1998

$^{40}Ar/^{39}Ar$ analytical data of hornblende and muscovite separates from granitic rocks in southwestern region of Ogcheon belt shows fellowing tectonic implication, $^{40}Ar/^{39}Ar$ data of 5 samples yield apparent age spectra and $^{37}Ar_{ca}/^{39}Ar_k$ and $^{38}Ar_{CI}/^{39}Ar_k$ plateaus for more than 60% of the $^{39}Ar$ release. Except for HN-100, the $^{36}Ar/^{40}Ar$ versus $^{39}Ar/^{40}Ar$ corelalation diagrams indicate the presence of one distint line. Muscovite of sample PKJ-44 yield flate apparent age plateau for > 60% of the $^{39}Ar_k$ release. In the high temperature steps, the $^{37}Ar_{ca}/^{39}Ar_k$ values are irregular with a correlative increase in $^{38}Ar_{CI}/^{39}Ar_k$, suggesting some Ca and CI rich phase, tapped between the silicate sheet is being argon degassed. The $^{40}Ar/^{39}Ar$ total gas age and the high temperature age of HN-100 is 918.2 Ma and 1360 Ma, respectively. The former affectted by recystallized age of Daebo Orogeny, and the latter indicated age of hornblende closure temperature for cooling stage of amphibole xenolith in granite gneiss. Three rock types of Kwangju granites show about 165 Ma hornblende and muscovite ages with some degassed argon at low temperature steps. These ages of 4 samples indicate also recrystallized age by Daebo Orogeny. In $^{40}Ar/^{39}Ar$ mineral age, Rb/Sr whole age and K/Ar mineral age, discordant ages of southwestern region of Ogcheon belt suggesting cooling rates approaching 3~4$^{\circ}C$/m. y. Such slow cooling rates can be produced by uplift rate of 100m/m.y. or slightly slower than isothem-migration rate derived from the hornblende samples. We conclude that the strongest Orogeny and igneous activity of southwestern region of Ogcheon belt are middle proterozoic era (about 1360 Ma) and middle Jurassic period (about 165 Ma).

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.11 no.2
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• pp.110-115
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• 2008

Purpose: Intussusceptions are one of the most common causes of intestinal obstruction in infants and young children. Although it is easily treated by non-operative reduction using barium, water or air, this treatment is very stressful for young patients and may cause bowel perforation, peritonitis and shock. In this study, we identified the risk factors associated with the failure of non-operative reduction, to identify a group of children that would benefit from the procedure and those who would not. Methods: We reviewed the medical records of patients with intussusception who were treated at the Korea University Medical Center Ansan hospital from March 1998 to July 2006. Three hundred fourteen children with intussusception were identified. Among them, non-operative reductions were performed in three hundred. Clinical and radiological variables were compared according to the failure or success of the non-operative reduction. Results: Non-operative reductions were successful in 243 (81%) and failed in 57 (19%). The group that had failed procedures had a younger age (12.3${\pm}$17.2 months vs. 18.0${\pm}$15.8 months, p=0.03), longer symptom duration before reduction (33.6${\pm}$29.0 hr vs. 21.5${\pm}$20.3 hr, p<0.01), more vomiting and lethargy (p<0.01), but less abdominal pain and irritability (p<0.01), compared with the group that had a successful procedure. Logistic regression analysis showed that the factors associated with the failure of non-operative reductions were a younger age, less than 6 months of age (odds ratio: 2.5, 95% confidence interval: 1.2~5.2, p=0.01), duration of symptoms, longer than 24 hrs before reduction (odds ratio: 2.1, 95% confidence interval: 1.2~4.2, p=0.03), bloody stool (odds ratio: 4.8, 95% confidence interval: 1.9~12.2, p<0.01), lethargy (odds ratio: 3.4, 95% confidence interval: 1.1~10.4, p=0.04), and abdominal pain or irritability (odds ratio: 0.2, 95% confidence interval: 0.1~0.4, p<0.01). Conclusion: For children with intussusception, an age younger than 6 months, and duration of symptoms more than 24 hrs before reduction, as well as the presence of bloody stools, lethargy and abdominal pain or irritability were variables associated with failure of a non-operative reduction. Knowledge of these variables should be considered in making clinical decisions for therapeutic interventions.

• Radiation Oncology Journal
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• v.20 no.2
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• pp.186-192
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• 2002

Purpose : Measurement of transmission dose is useful for in vivo dosimetry. In this study, previous algorithm for estimation of transmission dose was modified for use in cases with tissue deficit. Materials and Methods : The beam data was measured with flat solid phantom in various conditions of tissue deficit. New algorithm for correction of transmission dose for tissue deficit was developed by physical reasoning. The algorithm was tested in experimental settings with irregular contours mimicking breast cancer patients using multiple sheets of solid phantoms. Results : The correction algorithm for tissue deficit could accurately reflect the effect of tissue deficit with errors within ${\pm}1.0\%$ in most situations and within ${\pm}3.0\%$ in experimental settings with irregular contours mimicking breast cancer treatment set-up. Conclusion : Developed algorithm could accurately reflect the effect of tissue deficit and irregularly shaped body contour on transmission dosimetry.