• Journal of the Korean GEO-environmental Society
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• v.8 no.3
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• pp.59-65
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• 2007

Excess pore pressures in low permeability soils may not dissipate quickly enough and decrease the effective stresses inside the soil, which in turn may cause a reduction of the shear strength at the interface between the soil and the reinforcement in MSE walls. For this condition the dissipation rate of pore pressures is most important and it varies depending on wall size, permeability of the backfill, and reinforcement length. In this paper, a series of numerical analysis has been performed to investigate the effect of those factors. The results show that for soils with a permeability lower than $10^{-3}cm/sec$, the consolidation time gradually increases. The increase in consolidation time indicates the decrease in effective stress thus it will result in decrease in pullout capacity of the reinforcement as verified by the numerical analyses. It is also observed that larger consolidation time is required for longer reinforcement length (longer drainage path).

• Journal of Korean Society on Water Environment
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• v.23 no.5
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• pp.748-755
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• 2007

To develop an efficient pump operating rule for a retard basin, it is necessary to estimate inflow to the retard basin accurately which is affected by the backwater effect at the outlet of the conduit. The magnitude of the backwater effect is dependent on the water depth of a retard basin; however, the depth is determined by the amount of inflow and outflow. Thus, a real time simulation system that is able to simulate urban runoff and the pump operation with the consideration of the backwater effect is required to estimate the actual inflow to a retard basin. With this system, the efficient pump operating rule can be developed to diminish the possible flood damage on urban areas. In this study, a realtime simulation system is developed using the SWMM 5.0 DLL and Visual Basic 6.0 equipped with EXCEL to estimate inflow considering the backwater effect. The realtime simulation can be done by updating realtime input data such as minutely observed rainfall and the depth of a retard basin. Using those updated input data, the model estimates actual inflow, the amount of outflow discharged by pumps and gates, the depth of each junction, and flow rate at a sewer pipe on realtime basis. The developed model was applied to the Joonggok retard basin and demonstrated that it can be used to design a sewer system and to estimate actual inflow through the inlet sewer to reduce the inundation risk. As results, we find that the model can contribute to establish better operating practices for the pumps and the flood drainage system.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.495-508
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• 2010

Vertical drains are commonly used to accelerate the consolidation process of soft soils, such as dredged materials. The installation of vertical drain provides a radial drainage path to water in the deposit soil in addition to the vertical direction. An estimation of time rate of settlement is considerably complicated when vertical drains are installed to enhance consolidation process of dredged material because the vertical drains are commonly installed before self-weight consolidation is ceased. In this paper, the vertical drain theory developed by Barron(1948) is applied to analyze the non-linear consolidation behavior considering radial drainage. The overall average degree of self-weight consolidation of the dredged soil under the condition that the water is drained in both radial and vertical directions is estimated using the Carillo(1942) formula. In addition, the Morris(2002) theory and the one-dimensional non-linear finite strain numerical model, PSDDF, are applied to analyze the self-weight consolidation in case of only the vertical drainage is considered. The new analysis approach proposed herein can simulate properly the time rate of the self-weight consolidation of dredged materials that is facilitated with vertical drains.

• Korean Journal of Head & Neck Oncology
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• v.27 no.1
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• pp.54-58
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• 2011

Objectives : There are many reports on attempts to minimize complications and recurrences of tumor by several techniques for benign parotid tumor resection. The purpose of our study is to find out meaning of procedure without identifying main trunk of facial nerve compared to conventional parotidectomy. Material and Methods : We classified 121 patients into two groups. Patients who were underwent superficial parotidectomy or partial superficial parotidectomy were included in idenitification group(IF group), and patients who were treated with conservative partial parotidectomy or extracapsular dissection without identification of main trunk of facial nerve were included in the non-identification group(NF group). We analyzed the location of tumor, operation time, mean drainage duration, complication, recurrence and cosmetic satisfaction in two groups. Results : NF group has shorter operation time and mean drainage duration than IF group, however there is no significant difference in complication and recurrence between two surgical techniques. The Cosmetic satisfaction was similar between two groups. Conclusion : Limited parotidectomy without finding main trunk of facial nerve may be reliable option for benign parotid tumors because it has advantages such as less operation time and mean drainage duration without increasing in recurrence or complication rate.

• Korean Journal of Heritage: History & Science
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• v.52 no.4
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• pp.124-141
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• 2019

This research explored the relationship between the water quality issue of Wolji Pond (Anapji Pond) with the maintenance of the channel flow circulation system. The water supply and drainage system closely related to the circulation system of pond has been reviewed, rather than the existing water supply and drainage system that has been analyzed in previous studies. As a result of reviewing the water supply system, it has been learned that the water supply system on the southeastern shore of Wolji Pond, being the current water supply hole, has been connected to the east side garden facility (landscaping stone, curved waterway, storage facility of water) between the north and south fence and the waterway. This separate facility group seems to have been a subject of the investigation of the eastern side of Wolji Pond, with the landscaping stones having been identified in the 1920's survey drawings. The water supply facility on the southeastern shore, being the suspected water supply hole, seems to have some connection with the granite waterway remaining on the building site of Imhaejeon (臨海殿) on the southern side of Wolji Pond. It is inferred that it provides clean water, seeing that the slope towards the southwestern shore of Wolji Pond becomes lower, the landscaping stones have been placed in the filter area, and it is present in the 1920's survey drawings and the water supply hole survey drawing of 1975. The water drainage facility on the northern shore is composed of five stages. The functions of the wooden waterway and the rectangular stone water catchment facility seem not to be only for the water drainage of Wolji Pond. In light of the points that there are wood plugs in the wooden waterway and that there is a water catchment facility in the final stage, it is judged that the water of Balcheon Stream (撥川) may be charged in reverse according to this setup. Namely, the water could enter and exit in either direction in the water drainage facility on the northern shore It also seems that the supply to the wooden waterway could be opened and shut through the water catchment facility of rectangular stone group as well. The water drainage facility on the western shore is very similar to the water drainage facility on the northern shore, so it is difficult to avoid the belief that it existed during the Silla Dynasty, or it has been produced by imitating the water drainage facility on the northern shore at some future point in time. It seems to have functioned as the water drainage facility for the supply of agricultural water during the Joseon Dynasty. The water supply and drainage facilities in Wolji Pond have been understood as a systematized distribution network that has been intertwined organically with the facility of Donggung Palace, which was the center of the Silla capital. Water has been supplied to each facility group, including Wolji Pond, through this structure; it includes the drainage system connecting to the Namcheon River (南川) through the Balcheon Stream, which was an important canal of the capital center.

• Journal of Korean Tunnelling and Underground Space Association
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• v.19 no.6
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• pp.1059-1075
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• 2017

The objective of this study was to evaluate the freezing and thawing resistance of the existing drainage system for leakage treatment of underground concrete structures operating in cold regions. The freezing and thawing test was conducted on 4 types of drainage system specimens to evaluate the freezing and thawing resistance of the drainage system. The freezing and thawing resistance was evaluated on 4 types of Hotty-gel, as a waterproofing material, connection methods and on two methods to fix the drainage board with Hotty-gel on the surface of cement concrete specimen. One cycle of the freeze-thaw testing was 48 hours (24 hours of freezing and 24 hours of thawing), and the temperatures of freezing and thawing were at $-18^{\circ}C$ and $10^{\circ}C$, respectively. Among the 4 types of Hotty-gel connection methods, leakage occurred after 28 cycles (8 weeks) of freeze-thawing only in the Hotty-gel connection method with the 'V' groove applied to the corner of the drainage board. No leakage occurred in the 3 types of Hotty-gel connection methods. In two fixing methods, leakage occurred in the method of fixing the drainage board on the cement concrete specimen using the washer, screw and plastic wall plug. Leakage occurred at one point after 10 cycles (3 weeks) of freezing and thawing. After 28 cycles (8 weeks) of freezing and thawing, leakage point increased to 5 points. As time passed, the leak point was not increased, but the amount of leakage was increased at each leak point. The Hotty-gel connection method with cross-sectional diagonal shape was evaluated to be the highest in the production efficiency considering the production time and manufacturing method of the Hotty-gel connection shape. In the construction efficiency considering the construction time and construction method, the fixing method of air nailer, fixed nail and washer was superior to that of the washer, screw and plastic wall plug.

• Journal of Chest Surgery
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• v.37 no.12
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• pp.983-986
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• 2004

Background: The indications of closed thoracostomy drainage in management of primary spontaneous pneumothorax is well known, but there is no special specification for the size to be inserted. Recently, various minimally invasive operational techniques have been introduced and researched. According to the trend, we tried to ascertain the efficacy of 12 Fr. chest tubes instead of the existing 24 Fr. chest tubes. Material and Method: Patients who were younger than 30 years old and diagnosed as primary spontaneous pneumothorax and treated with closed thoracostomy drainage were enrolled in this study. We retrospectively compared group A who were drained with 24 Fr. chest tubes from January to May 2003 with group B with 12 Fr. chest tubes from November 2003 to April 2004 on procedure time for closed thoracostomy drainage, duration of chest tube drain, duration of hospital stay, complication, and recurrence. Result: The male to female ratio was 16 : 3 in group A and 18 : 2 in group B. The mean age of patients of group A was 21.7$\pm$4.0 and group B was 20.0$\pm$3.7. The mean procedure time for closed thoracostomy drainage in group A (21.6$\pm$2.9 minutes) was significantly longer than group B (10.8$\pm$1.9 minutes)(p < 0.05). The mean duration of chest tube drain was 3.8$\pm$ 1.7 days in group A and 4.3$\pm$2.2 in group B, and the mean duration of hospital stay was 5.6$\pm$1.9 days in group A and 5.2$\pm$1.5 days in group B. There was no complication in both groups and 6 cases in group A (35%) and 5 cases in group B (25%) were operated because of recurrence and persistent air leakage. In conclusion, there was no statistical difference except for the procedure time for closed thoracostomy drainage between two groups. Conclusion: We concluded that there were no significant differences in efficacy between 12 Fr. chest tube and 24 Fr. chest tube in closed thoracostomy drainage for primary spontaneous pneumothorax and we found advantages of 12 Fr. chest tube in shortening procedure time because of easy and simple techniques.

• Journal of Chest Surgery
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• v.42 no.1
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• pp.59-62
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• 2009

Background: Pleural drainage following video-assisted thoracic surgery has traditionally been achieved with largebore, semi-rigid chest tubes. Recent trends in thoracic surgery have been toward less invasive approaches for a variety of diseases. The purpose of this study was to evaluate the safety and efficacy of drainage by means of small, soft, and flexible 14Fr Blake drains. Material and Method: Between December 2007 and March 2008, 14Fr silastic Blake drains were used for drainage of the pleural cavity in 37 patients who underwent a variety of video-assisted thoracic surgical procedures at our institution. Result: The average postoperative length of hospital stay was 3.26 days (range, 2~12 days), Blake drains were left in the pleural space for an average of 3.15 days (range, 1~7 days), and the average amount of drainage was 43.8 ml/day. The maximal amount of blood removed daily by a Brake drain was as much as 290 mL. There were no drain-related complications. Blake drains seemed to cause less pain while in place, and particularly at the time of removal. Conclusion: The use of a Blake drain following minor thoracic surgery appeared to be safe and effective in drainage of fluid or air in the pleural space, and were associated with minimal discomfort.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.69 no.2
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• pp.78-87
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• 2024

The risk of global warming is increasing due to rapid climate change and increased greenhouse gas (GHG) emissions. Among the greenhouse gases, methane has a strong warming effect; in particular, 51.2% of the agricultural sector's methane emissions are from flooded rice fields. According to the current standard rice cultivation method, rice is grown during the maximum tillering stage with an intermittent drainage period of approximately 2 weeks. During the flooding period, methane-producing bacteria are active, but the activity of methane-producing bacteria and the amount of methane gas produced are reduced when the soil becomes oxidized through watering. Accordingly, this study used multiple-sensing technology to analyze the growth response according to the intermittent drainage period and to identify the extended intermittent drainage period with less impact on rice production. The equipment used for growth observations included NDVI, PRI, and IR sensors. The results confirmed that growth indices related to stress, such as NDVI and PRI, were not significantly different from those of the control when treated within 3 weeks of drainage, but drastically decreased when the drainage period was extended beyond 4 weeks. These results appear to result from the fact that soil water content (volumetric water content) also dropped to below 20% 4 weeks after irrigation, creating actual drought stress conditions. The 22^nd day after treatment, when the soil moisture content reached 20%, was considered the point in time when drought stress conditions were formed. The point at which the SPAD value decreased to 0.6% of normal was estimated to be 23.5 days after treatment by using the regression equation between NDVI and SPAD.

• Journal of the Korean Society of Safety
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• v.30 no.4
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• pp.79-85
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• 2015

Onboard fire extinguishing system is important to protect cargo and human lives and every oil tanker has foam type fire extinguishing system. Because of environmental problem, agent which contains materials such as Perfluorinated compounds are regulated and the development of the environmental friendly agent is required. The protein foam has less environmental pollution problem and has an excellent fire extinguish performance to oil fire. In the research, bivalency metal salts were added as stabilizer to increase fire resistance and stability of the foam. Ferrous sulfate, Iron chloride and Nickel chloride were used and to adjust to vessel, sea water was applied. As a stabilizer increased, the expansion ratio was raised. However 25% drainage time was decreased over 2.0 wt.% which is knowable that the foam brokes easily. The amount of generated foam was measured to check fluidity of foam and it appeared that when $FeSO_4$ 1.2 wt.% was added, the amount of generated foam reached large and also the 25% drainage time was high. To evaluate the fire extinguishing performance for oil fire, the small scale oil fire test was executed. When $FeSO_4$ 1.2 wt.% was added, fire extinguishing time was in its shortest which informs fluidity of foam and stability are important factors on fire extinguishing efficiency.