• Journal of Advanced Marine Engineering and Technology
• /
• v.40 no.6
• /
• pp.510-515
• /
• 2016

Recently, corrosion occurred on the piles of a marine bridge located on the NamHae expressway in Korea. A sacrificial anode cathodic protection system was installed to prevent corrosion damage in the marine bridge. In the case of the marine bridge in this study, the sacrificial anode cathodic protection system was applied at the tidal and splash zones of the piles because the upper part of the structure was not corroded, and because corrosion occurs at the tidal and splash zones due to sea tides. To verify the performance of the sacrificial anode cathodic protection system 8 years later, cathodic protection (CP) current, CP potential, and degree of depolarization were measured. The experimental results on the performance of the sacrificial anode cathodic protection system from a total of 60 piles were classified into 4 categories: good CP effect results (13 piles), partial CP effect results (27 piles), temporarily erroneous results (5 piles), and need for maintenance because of delamination (15 piles). It was determined that additional repairs are required, such as the application of bulk anodes and jacket casings, for piles where the CP effect is poor.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.32 no.6B
• /
• pp.345-354
• /
• 2012

The main objective of this study is evaluating experimentally roughness coefficients of the Korean riparian vegetations based on the n-VR analysis to suggest the practical guideline for Manning's roughness coefficients for the channel design. Hydraulic experiments were conducted for Phragmites japonica Steud., Miscanthus sacchariflorus (Maxim.) Benth., and Phragmites communis Trin. under both submerged and un-submerged conditions, and the n-VR relationships are developed for each grass. Three vegetations tested in this study can be considered as same group showing similar roughness characteristics, though these grasses are strongly affected by vegetation stiffness. Vegetation roughness are also affected by the growth state of plants according to experimental results of Phragmites communis Trin.

• Journal of the Korean Society for Precision Engineering
• /
• v.31 no.7
• /
• pp.643-649
• /
• 2014

In order to demonstrate the possibility of applying an ionic polymer metal composite (IPMC) to a finger exoskeleton, pinching motion analysis was performed for a thumb-index finger dummy actuated by IPMC actuators. The IPMC actuators of 5mm in width and 40mm in length with 2.4mm thickness generated 1.52N of blocking force for the applying voltage of 4.0V. Three actuators were installed on the three rotary joint of an index finger, and one actuator was installed on one proximal joint. Positions of each joint and finger tip were recorded on the video camera, and motion was analyzed. Power supply to the index finger actuators preceded power supply to the thumb actuator, and key pinching motion was accomplished in 180s. Tip pinching was accomplished in 135s as power supply to the thumb preceded power supply to the index finger.

• Journal of Chest Surgery
• /
• v.43 no.6
• /
• pp.797-799
• /
• 2010

The pneumomediastinum after a dental treatment occurs rarely and shows almost good prognosis, however it is potentially life-threatening complication. Here we report a case of pneumomediastinum, occurred by air bubbles originated from dental high speed equipment, via head and neck fascial space with literatures review.

• Journal of Korean Society on Water Environment
• /
• v.20 no.2
• /
• pp.132-144
• /
• 2004

The purpose of this study was to evaluate alternatives for stable operation of WWTP(Wastewater Treatment Plant) with a higher rate of inflows and a higher concentration of pollutants during wet weather to minimize the pollution loads being discharged into receiving waters. 3Q(Q: dry weather flow) of a base flow is normally intercepted and flows into WWTP as it was current practice. It is revealed by simulation that the bypassing alternative of 1Q through secondary treatment and 2Q into the stream after primary treatment was as good as it is expected. The bypass pollution loads were in the range of 23.9 ~ 38.5 % of the total loads flowing into the WWTP indicating that the bypassed flows need an extra treatment such as stormwater detention reservoir, high-rate coagulation with sedimentation, and step-feed. The high-rate coagulation with sedimentation was the most effective with respect to removal of the pollution loads.

• Journal of Chest Surgery
• /
• v.24 no.5
• /
• pp.463-469
• /
• 1991

Post-anastomotic leakage and stenoses remain major complications and are still responsible for many mortalities after esophageal reconstructive procedures. If the hand-suture is used, anastomotic leaks developed frequently than stenoses. But post-anastomotic leakages are more critical than post-anastomotic stenoses. If the stapler is used, anastomotic stenoses will develop frequently and not critical than anastomotic leakages. The stapler suture method is easier and quicker than the hand suture method in the esophageal anastomotic procedures. But the disadvantages of the stapler suture method is that there is not reachable site with anastomotic stapler the thoracic inlet region and the cost is expensive. We have treated 44 cases of the surgical complications after esophageal reconstructive procedure with conservative and surgical treatment for 10 years from January, 1980 to December, 1989. The anastomotic site stenoses were 8 cases in the hand-suture methods and 4 cases in the stapler-suture methods. The anastomotic leaks were 8 cases in hand-suture methods and 5 cases in stapler-suture methods. There were one death in the surgical repair of four post-operative anastomotic stenoses and two deaths in the surgical repair of three post-operative anastomotic leakages. Ever though we consider that there is more anastomotic leakage than stenoses after the hand-suture methods in esophageal reconstructive procedures. the cost with long stay in the intensive care unit to treat anastomotic leakage after the hand-suture, would be more expensive than-the cost of the treatment of the anastomotic stenoses after auto-suture.

• Journal of Chest Surgery
• /
• v.28 no.11
• /
• pp.1025-1031
• /
• 1995

Thirty patients who underwent esophageal resections due to esophageal carcinoma and benign strictures, and esophagovisceral anastomoses were performed by hand suture in 11 patients[Group I and by using the end to end anastomosis[EEA stapler in 19 patients[Group II . Anastomoses were performed in the thoracic cavity in 24 patients[Right 19, Left 5 and in the cervical area in 6 patients. There was one operative mortality[3.3% in a cancer patient who underwent Ivor-Lewis operation using EEA stapler. She expired on POD 38 days due to renal failure and sepsis. There were two anastomotic leakage in the sutured group and no anastomotic leakage in the stapled group. Late anastomotic strictures occurred in 10 patients[52.6% in the stapled group compared to 2 patients[18.1% in the sutured group. Most of the patients with late anastomotic strictures responded to one or two trials of TTS dilations. Using EEA stapler in performing esophagovisceral anastomosis is a safe method with acceptable range of complication rate, and total admission period after the operation for group I was 30.3 days compared to 25.4 days in group II although it had no clinical significance. The follow up was possible in 23 patients; 5 patients in group I died within mean 12.6 months and 9 patients in group II within mean 14.2 months.

• Journal of the Korean Operations Research and Management Science Society
• /
• v.39 no.3
• /
• pp.51-61
• /
• 2014

In this paper, we deal with developing a cost estimation relationships (CER) for Korean maneuverable weapons systems using historical production cost. To develop the CER, we collected the historical data of the production cost of four tanks and five armored vehicles. We also analyzed the Required Operational Capability (ROC) of the weapons systems and chose cost drivers that can compare operational capabilities of the weapons systems We used Forward selection, Backward selection, Stepwise Regression and $R^2$ selection as the cost drivers which have the greatest influence with the dependent variables. And we used Principle Component Regression, Robust Regression and Weighted Regression to deal with multicollinearity and outlier among the data to develop a more appropriate CER. As a result, we were able to develop a production cost CER for Korean maneuverable weapons systems that have the lowest cost errors. Thus, this research is meaningful in terms of developing a CER based on Korean original cost data without foreign data and these methods will contribute to developing a Korean cost analysis program in the future.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 1999.05a
• /
• pp.280-285
• /
• 1999

In this paper, we have analyzed a performance of fast frequency hopping communication systems when a rayleigh fading caused by envelope variations of a signal received in multipath channel is, but it is not considered that intentional or unintentional jamming can be. The multipath fading channel and rayleigh fading are confirmed by theoretical analysis. In fading or non-fading, the performance of this system is studied. When the path diversity is applied to this system, the performance is shown to be superior to non-diversity systems about 20dB. for modulation methods, BFSK was compared with DPSK.

• Journal of Biomedical Engineering Research
• /
• v.19 no.3
• /
• pp.215-224
• /
• 1998

This paper is fundamental study to develope the extracorporeal liver support system for patient with fulminant hepatic failure(FHF) or being expected for orthotopic liver transplantation. The polyurethane foam, which is composed of the density of 33kg/m3, the average pore diameter of 500${\mu}{\textrm}{m}$, the closed window of 60-70%, was manufactured with the prepolymer of 15% NCO-, Hepatocytes were inoculated to form spheroids in polyurethane foam. The time of spheroid formation in BSA(Bovine Serum Albumin) coated polyurethane foam was shorter than that in raw polyurethane foam. To verify the function of hepatocyte spheroids, we measured ammonia removal rate, urea and albumin secretion rate. Polyurethane foam was suitable for culture of hepatocyte spheroids. And culture of hepatocyte spheroids in polyurethane foam has high possibility in using as an extracorporeal liver support system.