• Clinics in Shoulder and Elbow
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• v.24 no.3
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• pp.135-140
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• 2021

Background: We hypothesized in this study that the characteristics of retear cases vary according to surgeon volume and that surgical outcomes differ between primary and revision arthroscopic rotator cuff repair (revisional ARCR). Methods: Surgeons performing more than 12 rotator cuff repairs (RCRs) per year were defined as high-volume surgeons, and those performing fewer than 12 RCRs were considered low-volume surgeons. Of the 47 patients who underwent revisional ARCR at our clinic enrolled in this study, 21 cases were treated by high-volume surgeons and 26 cases by low-volume surgeons. In all cases, the interval between primary surgery and revisional ARCR, degree of "acromial scuffing," number of anchors, RCR technique, retear pattern, fatty infiltration, retear size, operating time, and clinical outcome were recorded. Results: During primary surgery, significantly more lateral anchors (p=0.004) were used, and the rate of use of the double-row repair technique was significantly higher (p<0.001) in the high- versus low-volume surgeon group. Moreover, the "cut-through pattern" was observed significantly more frequently among the cases treated by high- versus low-volume surgeons (p=0.008). The clinical outcomes after revisional ARCR were not different between the two groups. Conclusions: Double-row repair during primary surgery and the cut-through pattern during revisional ARCR were more frequent in the high- versus low-volume surgeon groups. However, no differences in retear site or size, fatty infiltration grade, or outcomes were observed between the groups.

• Journal of Gastric Cancer
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• v.13 no.1
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• pp.44-50
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• 2013

Purpose: Laparoscopic gastrectomy has been adopted for the treatment of gastric cancer, and despite the technical difficulties, totally laparoscopic distal gastrectomy has been considered less invasive than laparoscopy-assisted distal gastrectomy. Although there have been many reports regarding the feasibility and safety of totally laparoscopic distal gastrectomy at large volume centers, few reports have been conducted at low-volume centers. The purpose of this study is to try to assess the feasibility and safety of totally laparoscopic distal gastrectomy at a low volume center through the analysis of short-term outcomes of totally laparoscopic distal gastrectomy compared with laparoscopy-assisted distal gastrectomy. Materials and Methods: The clinical data and short-term surgical outcomes of 35 patients who had undergone laparoscopy-assisted distal gastrectomy between April 2007 and March 2010, and 37 patients who underwent totally laparoscopic distal gastrectomy between April 2010 and August 2012 were retrospectively reviewed. Results: There was no significant difference in the demographic and clinical data. However the reconstruction method and extent of lymphadenectomy showed statistically significant differences. Operation time and estimated blood loss did not show significant differences. Surgical and medical complications did not show significant differences but postoperative courses including time-to-first oral intake and postoperative hospital stay were significantly increased. Conclusions: Our study shows that totally laparoscopic distal gastrectomy is technically feasible at a low volume center. Therefore, totally laparoscopic distal gastrectomy can be considered as one of the surgical treatment for early gastric cancer. However the possibility that totally laparoscopic distal gastrectomy may have less benefit should also be considered.

• Journal of Gastric Cancer
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• v.10 no.4
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• pp.241-246
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• 2010

Purpose: Laparoscopy-assisted gastrectomy (LAG) has become a technically feasible and safe procedure for early gastric cancer treatment. LAG is being increasingly performed in many centers; however, there have been few reports regarding LAG at low-volume centers. The aim of this study was to report our early experience with LAG in patients with gastric cancer at a low-volume center. Materials and Methods: The clinicopathologic data and surgical outcomes of 39 patients who underwent LAG for gastric cancer between April 2007 and March 2010 were retrospectively reviewed. Results: The mean age was 68.3 years. Thirty-one patients had medical co-morbidities. The mean patient ASA score was 2.0. Among the 39 patients, 4 patients underwent total gastrectomy and 35 patients underwent distal gastrectomy. The mean blood loss was 145.4 ml and the mean operative time was 259.4 minutes. The mean time-to-first flatus, first oral intake, and the postoperative hospital stay was 2.8, 3.1, and 9.3 days, respectively. The 30-day mortality rate was 0%. Postoperative complications developed in 9 patients, as follows: anastomotic leakage, 1; wound infection, 1; gastric stasis, 2; postoperative ileus, 1; pneumonia, 1; cerebral infarction, 1; chronic renal failure, 1; and postoperative psychosis, 1. Conclusions: LAG is technically feasible and can be performed safely at a low-volume center, but an experienced surgical team and careful patient selection are necessary. Furthermore, for early mastery of the learning curve for LAG, surgeons need education and training in addition to an accumulation of cases.

• Macromolecular Research
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• v.11 no.3
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• pp.189-193
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• 2003

pH- and temperature-sensitive bifunctional hydrogels composed of N-isopropylacrylamide (NiPAAm) and a sulfadimethoxine monomer (SDM) derived from sulfadimethoxine were prepared. These hydrogels exhibit simultaneous pH- and temperature-induced volume-phase transitions. The pH-induced volume-phase transition behavior is produced by the ionization/deionization of SDM and is very sharp. In the high pH region, the ionization of SDM induces swelling of the hydrogels. In the low pH region, the deionization of SDM induces deswelling of the hydrogels. The temperature-induced volume-phase transition behavior of the bifunctional hydrogels exhibits negative thermosensitivity because of the NiPAAm component. The hydrogels swell even at low pH as the temperature decreases. The hydrogels swell at low temperature and high pH, and deswell at high temperature and low pH. The volume of the hydrogels dependl on the balance of the swelling and deswelling produced by the two competing stimuli, pH and temperature.

• KIEAE Journal
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• v.15 no.5
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• pp.5-12
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• 2015

Purpose: Retention and infiltration of small and frequently-occurring rainfall by LID facilities account for a large proportion of the annual precipitation volume. Based on 4 standard facilities such as Porous Pavement, Infiltration Trench, Cylindrical Infiltration Well, Rectangular Infiltration Well by Seoul Metropolitan Handbook of the Prior Consultation for LID. The total retention volume of each facility was calculated according to the type and size. The Purpose of this study is to find out the quantitative relationship between Percentile Rainfall Event and Design Volume of Infiltration Facilities. Methode: For the estimation of Percentile Rainfall Event, Daily Precipitation of Seoul from 2005 to 2014 was sorted ascending and the distribution of percentile was estimated by PERCENTILE spreadsheet function. The managed Rainfall Depth and Percentile of each facility was calculated at the several sizes. In response to the rainwater charge volume of 5.5mm/hr by the Category "Private large site", the 3 types of facilities were planned for example. The calculated Rainfall Depth and Percentile were 54.4mm and 90% by the use of developed Calculation-Module based on the Spreadsheet program. Result: With this Module the existing Designed Infiltration volume which was introduced from Japan was simply converted to the Percentile-Rainfall-Event used in USA.

• Journal of Korean Society on Water Environment
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• v.22 no.2
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• pp.342-348
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• 2006

Changes in water quality and algal growth according to the differences in the inflow volume were investigated in the Daecheong Lake from 1998 to 2001. Until year 2000, inflow volume considerably depended on the rainfall throughout the basin. However, the correlation was low since 2001 when water storage in the upstream Yongdam Lake was started. According to inflow volume-TP relationship analyses, significant correlation was found at up- and middle-stream sites, excluding down-stream site of the Daechong Lake. For chlorophyll-a, correlation was found with flow volume at all sites except for Choo-So. In a dry year, although nutrients loads were relatively lower than those in rainy years, there were higher concentrations of chlorophyll-a and massive bloom of Microcystis. Limiting factors for algal growth seems to be not the volume of nutrients load but retention time and physical disturbance of the water body influenced by inflow volume. Thus, in the Daecheong lake, it would be more important to focus on the management of eutrophication in dry years than in rainy ones.

• Korean Journal of Materials Research
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• v.30 no.4
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• pp.184-196
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• 2020

In this study, effects of carbon and nickel on microstructure and low temperature Charpy impact properties of HSLA (high strength low alloy) steels are investigated. To understand the complex phase transformation behavior of HSLA steels with high strength and toughness before and after welding processes, three kinds of HSLA steels are fabricated by varying the carbon and nickel content. Microstructure analysis, low temperature Charpy impact test, and Vickers hardness test are performed for the base metals and CGHAZ (coarse-grain heat affected zone) specimens. The specimens with the lowest carbon and nickel content have the highest volume fraction of AF, the lowest volume fraction of GB, and the smallest GB packet size. So, the low temperature Charpy absorbed energy of the CGHAZ specimen is the highest. The specimens with increased carbon and nickel content have the lowest volume fraction of AF, the highest volume fraction of GB, and the largest GB packet size. So, the low temperature Charpy absorbed energy of the CGHAZ specimen is the lowest.

• Journal of Gastric Cancer
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• v.17 no.3
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• pp.246-254
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• 2017

Purpose: The significance of hospital volume remains inconsistent and controversial. In particular, few studies have examined whether hospital volume is associated with the outcome of gastrectomy for gastric cancer in East Asia. This study examined the effect of hospital volume on the short-term surgical and long-term oncological outcomes of patients undergoing curative gastrectomy for gastric cancer. Materials and Methods: Between 2009 and 2011, 1,561 patients underwent curative gastrectomy for gastric cancer at Seoul St. Mary's Hospital (n=1,322) and Bucheon St. Mary's Hospital (n=239). We defined Seoul St. Mary's Hospital as a high-volume center and Bucheon St. Mary's Hospital as a low-volume center. Results: The extent of resection, rate of combined resection, tumor stage, operating time, and hospital stay did not differ significantly between the 2 hospitals. In addition, the hospital volume was not significantly associated with the 30-day morbidity and mortality. When the overall and disease-free survival rates of the patients were stratified according to stage, hospital volume was not significantly associated with prognosis at any stage. Conclusions: Hospital volume might not be a decisive factor with respect to the surgical and oncological outcomes of patients if well-trained surgeons perform gastrectomy for gastric cancer.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.17-17
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• 2010

This paper address technical issues in calibrating discharge coefficients of sonic nozzles used to measure the volume flow rate of low vacuum dry pumps. The first challenging issue comes from the technical limit that their calibration results available from the flow measurement standard laboratories do not fully cover the low vacuum measurement range although the use of sonic nozzles for precision measurement of gas flow has been well established in NMIs. The second is to make an ultra low flow sonic nozzlesufficient to measure the throughput range of 0.01 mbar-l/s. Those small-sized sonic nozzles do not only achieve the noble stability and repeatability of gas flow but also minimize effects of the fluctuation of down stream pressures for the measurement of the volume flow rate of vacuum pumps. These distinctive properties of sonic nozzles are exploited to measure the pumping speed of low vacuum dry pumps widely used in the vacuum-related academic and industrial sectors. Sonic nozzles have been standard devices for measurement of steady state gas flow, as recommended in ISO 9300. This paper introduces two small-sized sonic nozzles of diameter 0.03 mm and 0.2 mm precisely machined according to ISO 9300. The constant volume flow meter (CVFM) readily set up in the Vacuum center of KRISS was used to calibrate the discharge coefficients of the machined nozzles. The calibration results were shown to determine them within the 3% measurement uncertainty. Calibrated sonic nozzles were found to be applicable for precision measurement of steady state gas flow in the vacuum process. Both calibrated sonic nozzles are demonstrated to provide the precision measurement of the volume flow rate of the dry vacuum pump within one percent difference in reference to CVFM. Calibrated sonic nozzles are applied to a new 'in-situ and in-field' equipment designed to measure the volume flow rate of low vacuum dry pumps in the semiconductor and flat display processes.

• Korean Journal of Materials Research
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• v.29 no.4
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• pp.211-220
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• 2019

In this study, three kinds of bainitic steel plates are manufactured by varying the chemical compositions and their microstructures are analyzed. Tensile and Charpy impact tests are performed at room and low temperature to investigate the correlation between microstructure and mechanical properties. In addition, heat affected zone (HAZ) specimens are fabricated by a simulation of welding processes, and the HAZ microstructure is analyzed. The base steel that has the lowest carbon equivalent has the highest volume fraction of acicular ferrite and the lowest volume fraction of secondary phases, so the strength is the lowest and the elongation is the highest. The Mo steel has a higher volume fraction of granular bainite and more secondary phases than the base steel, so the strength is high and the elongation is low. The CrNi steel has the highest volume fraction of the secondary phases, so the strength is the highest and elongation is the lowest. The tensile properties of the steels, namely, strength and elongation, have a linear correlation with the volume fraction of secondary phases. The Mo steel has the lowest Charpy impact energy at $-80^{\circ}C$ because of coarse granular bainite. In the Base-HAZ and Mo-HAZ specimens, the hardness increases as the volume fraction of martensite-austenite constituents increases. In the CrNi-HAZ specimen, however, hardness increases as the volume fraction of martensite and bainitic ferrite increases.