• Journal of Chest Surgery
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• v.37 no.4
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• pp.313-321
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• 2004

Excellent clinical results of the arterial switch operation and the limited availablity of the intraventricular rerouting has recently made an arterial switch operation to become the therapeutic method of choice for the repair of double-outlet right ventricle (DORV) with subpulmonary ventricular septal defect (VSD). The early and midterm outcomes of arterial switch operation for this anomaly were evaluated. Material and Method: Between August 1994 and July 2002, 13 patients underwent an arterial switch operation for the correction of double-outlet right ventricle with subpulmonary VSD at Dong-A university hospital.. The 50% rule was used to define DORV. Median age and mean body weight were 27 days (range, 3-120 days) and 3.8$\pm$0.7kg (range, 2.92-5.3kg) respectively. Aortic arch anomalies were associated in 6 cases (46.2%), which were all repaired through one-stage operation. The relationship of the great arteries were side-by-side in 8 cases (61.5%) and anteroposterior in 5 (38.5%). Coronary artery patterns were 1 LCx-2R in 6 cases, retropulmonary left coronary artery (LCA) in 6, and intramural LCA in 1 respectively. The enlargement of VSD was required in 1 patient and the patch enlargement of right ventricular outflow tract was performed in another one patient. The Lecompte maneuver was used in all but 3 patients with a side by side relationship of the great arteries. Result: Overall postoperative hospital mortality was 23.1 % (3/13). All operative deaths were occurred in the patients with aortic arch anomalies. There was one late death related to the postoperative complication of the central nerve system during the mean follow-up of 41.3$\pm$30.7 months. Pulmonary valvar stenosis (＞30mmHg of pressure gradient) developed in 1 patient (10%) and left pulmonary artery stenosis in 2 (20%), among them, one required reoperation 52 months after repair. There was an asymptomatic patient with moderate aortic regurgitation. 5-year survival rate including operative deaths was 68.3%. Conclusion: Although the operative mortality is high in the patients with aortic arch anomaly, the arterial switch operation for DORV with supbpulmonary VSD can be performed with low operative mortality and low reoperation rate in the patients Without arch anomaly. The arterial switch operation can be considered a good option for this complex anomaly.

• KDI Journal of Economic Policy
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• v.32 no.1
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• pp.131-169
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• 2010

I develop a matching model in which risk-averse workers face borrowing constraints and make a labor force participation decision as well as a job search decision. A sharp distinction between unemployment and out of the labor force is made: those who look for work for a certain period but find no job are classified as the unemployed and those who do not look for work are classified as those out of the labor force. In the model, the job search decision consists of two steps. First, each individual who is not working obtains information about employment opportunities. Second, each individual who decides to search has to take costly actions to find a job. Since individuals differ with respect to asset holdings, they have different reservation job-finding probabilities at which an individual is indifferent between searching and not searching. Individuals, who have large asset holdings and thereby are less likely to participate in the labor market, have high reservation job-finding probability, and they are less likely to search if they have less quality of information. In other words, if individuals with large asset holdings search for job, they must have very high quality of information and face very high actual job-finding probability. On the other hand, individuals with small asset holdings have low reservation job-finding probability and they are likely to search for less quality of information. They face very low actual job-finding probability and seem to remain unemployed for a long time. Therefore, differences in the quality of information explain heterogeneous job search decisions among individuals as well as higher job finding probability for those who reenter the labor market than for those who remain in the labor force. The effect of the extended maximum duration of unemployment insurance benefits on the aggregate labor market and the labor market flows is investigated. The benchmark benefit duration is set to three months. As maximum benefit duration is extended up to six months, the employment-population ratio decreases while the unemployment rate increases because individuals who are eligible for benefits have strong incentives to remain unemployed and decide to search even if they obtain less quality of information, which leads to low job-finding probability and then high unemployment rate. Then, the vacancy-unemployment ratio decreases and, in turn, the job-finding probability for both the unemployed and those out of the labor force decrease. Finally, the outflow from nonparticipation decreases with benefit duration because the equilibrium job-finding probability decreases. As the job-finding probability decreases, those who are out of the labor force are less likely to search for the same quality of information. I also consider the matching model with two states of employment and unemployment. Compared to the results of the two-state model, the simulated effects of changes in benefit duration on the aggregate labor market and the labor market flows are quite large and significant.

• Tunnel and Underground Space
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• v.30 no.4
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• pp.382-393
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• 2020

The engineered barrier system of high-level radioactive waste disposal must maintain its performance in the long term, because it must play a role in slowing the rate of leakage to the surrounding rock mass even if a radionuclide leak occurs from the canister. In particular, it is very important to clarify gas dilation flow phenomenon clearly, that occurs only in a medium containing a large amount of clay material such as a bentonite buffer, which can affect the long-term performance of the bentonite buffer. Accordingly, DECOVALEX-2019 Task A was conducted to identify the hydraulic-mechanical mechanism for the dilation flow, and to develop and verify a new numerical analysis technique for quantitative evaluation of gas migration phenomena. In this study, based on the conventional two-phase flow and mechanical behavior with effective stresses in the porous medium, the hydraulic-mechanical model was developed considering the concept of damage to simulate the formation of micro-cracks and expansion of the medium and the corresponding change in the hydraulic properties. Model verification and validation were conducted through comparison with the results of 1D and 3D gas injection tests. As a result of the numerical analysis, it was possible to model the sudden increase in pore water pressure, stress, gas inflow and outflow rate due to the dilation flow induced by gas pressure, however, the influence of the hydraulic-mechanical interaction was underestimated. Nevertheless, this study can provide a preliminary model for the dilation flow and a basis for developing an advanced model. It is believed that it can be used not only for analyzing data from laboratory and field tests, but also for long-term performance evaluation of the high-level radioactive waste disposal system.

• The Journal of Engineering Geology
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• v.22 no.4
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• pp.387-398
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• 2012

Korean agricultural areas that employ water curtain cultivation (WCC) have recently suffered extensive groundwater shortages due to an increase in the number of facilities. The primary focus of this study is to measure the daily groundwater use and discharge rates in the Cheongweon and Chungju pilot areas, while the second focus is to estimate the total amount of groundwater used in WCC areas nationwide in Korea. Taking into consideration several factors, including motor type, outflow abilities of wells, records of daily minimum temperatures below $0^{\circ}C$, and the number of running wells according to weather variations, we estimated that $53,138m^3/ha$ of groundwater had been used in the 4-hectare Cheongweon pilot area during the winter period of late 2011 through early 2012. On a prorated areal basis, we can calculate that the total groundwater used nationwide was 0.57 billion $m^3$ in WCC areas of $10,746m^2$. This value is equivalent to 33.7% of the total agricultural groundwater use (1.69 billion $m^3$) in Korea. During 9-22 February 2012, the daily water discharge rate in the 4-ha Cheongweon pilot area ranged from 2,079 to $2,628m^3$, averaging $2,341m^3$. Combining this value with meteorological records for 94 days with a daily minimum temperature below $0^{\circ}C$ results in an estimated groundwater volume of $54,990m^3/ha$ for the pilot area during the 2011-2012 winter period. The total amount of groundwater used nationwide in WCC areas would then be 0.59 billion $m^3$, equivalent to 34.9% of the total agricultural groundwater use in Korea. In the Chungju area, the groundwater discharge rate was estimated to be less than 805 $m^3$/ha. This value, combined with weather data for 108 days with a daily minimum temperature below $0^{\circ}C$ in this area, can be applied to infer that the total groundwater volume used in WCC areas nationwide is no more than 55% of the total agricultural groundwater use in Korea.

• Journal of the Korean Institute of Landscape Architecture
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• v.40 no.1
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• pp.100-109
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• 2012

Removal rates of $PO_4-P$ and TP in a free water surface wetland system were investigated. The system was established in 2008 on a floodplain in the middle reach of the Gwangju Stream flowing through Gwangju City. Its dimensions were 46 meters in length and 5 meters in width. Two year old Typha angustifloria L. growing in pots were planted on half of the area and Zizania latifolia Turcz on the other half in 2008. Stream water was funneled into the wetlands by gravity flow, and its effluent was discharged back into the stream. The influent volume was controlled by valves and water depth was adjusted by wires. Volume and water quality of inflow and outflow were analyzed from January to December in 2010. Inflow into the system averaged approximately $710m^3/day$ and hydraulic residence time was about 1.5 hours. Average influent and effluent $PO_4-P$ concentration were 0.144 and 0.103mg/L, respectively, and $PO_4-P$ abatement amounted to 28.6%. Influent and effluent TP concentration averaged 0.333 and 0.262mg/L, respectively, and TP retention reached to 20.7%.$PO_4-P$ removal rate(%) during plant growing season(31.448) was significantly high(p<0.001) when compared with that during plant non-growing season(25.829). TP abatement rate(%) during plant growing season(27.230) was also significantly high(p<0.001) when compared with that of the non-growing season(14.856). Major phosphorous removals in the system resulted from adsorption of phosphorous in the litter-soil layers; sedimentation of particulate phosphorous and Ca, Al, Fe bounded phosphates; and absorption of phosphorous by emergent plants. The adsorption and sedimentation occurred throughout the year, however, the absorption took place during plant growing season. This resulted in higher removals of $PO_4-P$ and TP during plant growing season.

• The Korean Journal of Pharmacology
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• v.28 no.2
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• pp.129-136
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• 1992

As it has been reported that the depolarization-induced acetylcholine (ACh) release is modulated by activation of presynaptic $A_1-adenosine$ heteroreceptor in hippocampus and various lines of evidence indicate the involvement of adenylate cyclase system in $A_1-adenosine$ post-receptor mechanism in hippocampus, it was attempted to delineate the role of adenylate cyclase system in the $A_1-receptor-mediated$ control of ACh release in this study. Slices from rat hippocampus were incubated with $[^3H]-choline$ and the release of the labelled products was evoked by electrical stimulation $(3\;Hz,\;5\;Vcm^{-1},\;2\;ms,\;rectangular\;pulses)$, and the influence of various agents on the evoked tritium-outflow was investigated. $N^6-cyclopentyladenosine$ (CPA), a specific $A_1-adenosine$ receptor agonist, in concentrations ranging from 0.1 to $10\;{\mu}M$, decreased the $[^3H]-ACh$ release in a dose-dependent manner without the changes of basal rate of release. 8-cyclopentyl-1,3-dipropylxanthine $(DPCPX,\;1{\sim}10\;{\mu}M)$, a selective $A_1-receptor$ antagonist, increased the $[^3H]-ACh$ release in a dose-related fashion with slight increase of basal tritium-release. And the CPA effects were significantly inhibited by DPCPX $(2\;{\mu}M)$ pretreatment and the dose-response curve produced by CPA was shifted to the right. The responses to N-ethylmaleimide $(NEM,\;10\;&\;30\;{\mu}M)$, a SH-alkylating agent of G-protein, were characterized by increments of the evoked ACh-release and the basal release, and the CPA effect were completely abolished by NEM pretreatment. Forskolin, a specific adenylate cyclase activator, in concentrations ranging from 0.3 to $10\;{\mu}M$, increased the evoked ACh-release in a dose-dependent manner and the CPA effects were inhibited by forskolin. These results indicate that the $A_1-adenosine$ heteroreceptor plays an important role in ACh-release via nucleotide-binding protein Gi in the rat hippocampus and that the adenylate cyclase system might be participated in this process.

• The Korean Journal of Physiology
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• v.25 no.2
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• pp.189-200
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• 1991

During the past few years it has been proposed that lithium clearance can be used as a reliable measure for the outflow of tubular fluid from the proximal tubule. This study was aimed to characterize the inflow dependent reabsorption of Na in renal tubule beyond the proximal tubule. For this purpose, lithium clearance was used as a measure for the inflow from the proximal tubule and the changes in reabsorption fraction of Na and water were determined in rabbits. Rabbits were pretreated with hypotonic saline solutions for an hour (50 mM/L NaCl, 20 ml/hr/kg). And then a hypertonic solution of 500 mM/L NaCl (20 ml/kg) was administered intraperitoneally in conjunction with a bolus of LiCl solution (2 mM/kg, i.v.) for conditioning the $C_{Li}$ and urine flow rate. To rule out the effect of $Li^+$ on tubular functions, a bolus of NaCl solution (2 mM/kg, i.v.) was administered. Fifteen, thirty, and sixty minutes after injection of hypertonic saline arterial blood and urine samples were taken. Urinary and plasma concentrations as well as urinary output of $Li^+,\;Na^+\;and\;K^+$ were measured. From these $C_{Li},\;C_{Na}$ and the reabsorption fraction of Na and water $(Fr_{Na}\;&\;FrH_2O)$ were calculated. These results were compared with those from control groups in which the same amount of isotonic saline (145 mM/L NaCl) and of 15% dextran solution were administered in the same way as that in experimental group. Followings are the results obtained. 1) The plasma concentration of $Na^+$ in rabbits injected with hypertonic saline reached the peak value after 15 min and thereafter no significant change was observed. Hematocrit values did not show any change, while urinary excretion of $Na^+$ increased markedly during the first 15 min and decreased thereafter. These results were not affected by an injection of a small amount of LiCl. 2) The clearances of $Li^+,\;Na^+\;and\;K^+$ in rabbits injected with hypertonic saline and LiCl solution decreased. 3) In spite of the variation in $C_{Li},\;Fr_{Na}$ did not show any significant change while $FrH_2O$ increased gradually. 4) $C_{Li}$ decreased also in rabbits received isotonic saline. $Fr_{Na}$ tended to be higher than that in hypertonic saline group, while $FrH_2O\;and\;Fr_{Na}$ did not associated with the decrease in $C_{Li}$. 5) $C_{Li}$ of the rabbits received dextran solution fluctuated persistently and $Fr_{Na}\;and\;FrH_2O$ did not change in along with $C_{Li}$ although $Fr_{Na}$ had a tendency to be higher than that in hypertonic saline group. 6) From the above results it was concluded that: (a) In rabbits with normal body store of $Na^+$, the $Fr_{Na}$ of renal tubule beyond proximal tubule. calculated from $C_{Li}$ as a measure of inflow from proximal tubule is constant in spite of variations in $C_{Li}$. (b) The $FrH_2O$ calculated from $C_{Li}$ is dependent largely upon ADH rather than inflow from proximal tubule. (c) When there is a decrease in plasma $Na^+$ concentration or ineffective body fluid. $Li^+$ reabsorption may occur in the thick segnent of Henle's loop and hence the determination of $Fr_{Na}$ and $FrH_2O$ will not be easy one, but $Fr_{Na}$ is constant under the same experimental conditions.

• The Korean Journal of Pharmacology
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• v.30 no.3
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• pp.263-272
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• 1994

Since it was been reported that the depolarization-induced ACh release is inhibited by activation of presynaptic $A_1-adenosine$ heteroreceptor in hippocampus, a large body of experimental data on the post-receptor mechanism of this process has been accumulated. But, the post-receptor mechanism of presynaptic $A_1-adenosine$ receptor on the ACh release has not been clearly elucidated yet. Therefore, it was attempted to clarify the post-receptor mechanisms of the $A_1-adenosine$ receptor-mediated control of ACh release in this study. Slices from rat hippocampus were equilibrated with $^3H-choline$ and the release of the labelled products was evoked by electrical stimulation (3 Hz, 5 $VCm^{-1}$, 2ms, rectangular pulses), and the influence of various agents on the evoked tritium-outflow was investigated. Adenosine, in concentrations ranging from $0.3{\sim}300\;{\mu}M$, decreased the ACh release in a dose-dependent manner, without affecting the basal rate of release. The adenosine effects were significantly inhibited by $DPCPX\;(2\;{\mu}M)$, a selective $A_1-receptor$ antagonist. The responses to N-ethylmaleimide $(10&30{\mu}M)$, a SH-alkylating agent of G-protein, were characterized by increments of the evoked ACh-release and the basal release, and the adenosine effects were completely abolished by NEM pretreatment. PDB $(1{\sim}10\;{\mu}M)$, a specific protein kinase C (PKC) activator, increased, whereas PMB $(0.03{\sim}1\;mg)$, a PKC inhibitor, decreased the evoked ACh-release, and the adenosine effects were not affected by these agents. Nifedipine $(1\;{\mu}M)$, a $Ca^{2+}\;-channel$ blocker of dihydropyridine analogue, significantly inhibited the adenosine effect, but glibenclamide, a $K^+-channel$ blocker, did not. Finally, 8-bromo cyclic AMP $(100\;&\;300{\mu}M)$, a membrane-permeable analogue of cAMP, did not alter the ACh release, but adenosine effects were inhibited by pretreatment with large dose of 8-br-cAMP $(300\;{\mu}M)$. These results indicate that the decrement of the evoked ACh-release by $A_1-adenosine$ receptor is mediated by the G-protein, and nifedipine-sensitive $Ca^{2+}-channel$ and adenylate cyclase system are coupled partly to this effect, and that protein kinase C and glibenclamide-sensitive $K{^+}-channel$ are not involved in this process.

• Korean Journal of Ecology and Environment
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• v.46 no.4
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• pp.488-498
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• 2013

A three-dimensional hydrodynamic model was applied to the Lake Euiam. The lake has three inflows, of which Gongji Stream has the smallest flow rate and poorest water. The dam-storage volume, watershed area, lake shape and discharge type of the Chuncheon Dam and the Soyang Dam are different. Therefore, it is difficult to analyze the water plume and mixing pattern due to the difference of the two dams regarding the amount of outflow and water temperature. In this study, we analyzed the effects of different characteristics on temperature and conductivity using the model appropriate for the Lake Euiam. We selected an integrated system supporting 3-D time varying modeling (GEMSS) to represent large temporal and spatial variations in hydrodynamics and transport of the Lake Euiam. The model represents the water temperature and hydrodynamics in the lake reasonably well. We examined residence time and spreading patterns of the incoming flows in the lake based on the results of the validated model. The results of the water temperature and conductivity distribution indicated that characteristics of upstream dams greatly influence Lake Euiam. In this study, the three-dimensional time variable water quality model successfully simulated the temporal and spatial variations of the hydrodynamics in the Lake Euiam. The model may be used for efficient water quality management.

• Childhood Kidney Diseases
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• v.11 no.1
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• pp.51-58
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• 2007

Purpose : To assess the early complication of laparoscopic peritoneal dialysis catheter implantation in children. Methods : Medical record review was carried out on 21 laparoscopic and 16 conventional peritoneal dialysis catheter implantations which were performed in 31 children under 18 years of age between 2002 and 2006. All medical records were retrospectively analyzed. The patients were followed until 2 months after catheter placement. Patient characteristics and catheterrelated complications, such as significant bleeding, leakage, obstruction, migration, insertion site infection and peritonitis during the first 60 days after implantation were recorded. Results : After conventional operation, dialysate leakage occurred in 2 of 16 cases and all cases improved after conservative management. In 1 case, significant bleeding occurred and re-operation was performed. Three cases of obstruction due to migration were reported, 2 cases underwent reoperation and 1 case improved without intervention. After laparoscopic surgery, outflow obstruction occurred in 1 out of 21 cases, which was caused by adhesion after several reinsertions of the catheter and recurrent peritonitis. No migration was noted after laparoscopic surgery. There was no significant difference in the complication rate between the two groups. Conclusion : Laparoscopic peritoneal dialysis catheter placement is feasible in children of all age groups, with at least equivalent functional results compared to conventional surgery. The additional advantage of laparoscopic catheter insertion is the option to identify and eliminate anatomical risk factors, such as intra-abdominal adhesions, and to perform partial omentectomy without additional incisions.