• 콘크리트학회논문집
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• 제17권1호
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• pp.141-147
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• 2005

The development of automobile, vessel, rail road, and machine industry leads an increase of foundry production used as their components, which cause a by-product, waste foundry sand (WFS). The amount of the WFS produced in Korea is over 700,000 tons a year, but most WFS has been buried itself and only $5{\~}6\%$ WFS is recycled as construction materials. Therefore, it is necessary for most WFS to research other ways which can be used in a higher value added product. The study on recycling it as a fine aggregate for concrete or green sand has been in progress in America and Japan since 1970s and 1980s respaectively. In this study, two types of WFS were used as a fine aggregate for concrete. Nine types of concrete aimed at the specified strength of 30 MPa were mixed with washed seashore coarse sand in which salt was removed, and WFS and then appropriate mixture proportion of concrete was determined. Moreover, basic properties such as air contents, setting time, bleeding, workability and slump loss of the fresh concrete with WFS were tested and compared with those of the concrete mixed without WFS. In addition, both compressive strength of hardened concrete at each ages and tensile strength of it at the age of 28 days were measured and discussed.

• Journal of Chest Surgery
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• 제26권7호
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• pp.526-531
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• 1993

Sixty-one consecutive patients with coronary artery bypass graft for myocardial revascularization were retrospectively reviewed to analyze various pattern of postoperative complication and death during hospital stay from Nov. 1988 to Oct. 1992. Fortytwo of the patients were male and nineteen female. The mean age was 56 and 51 years in male and female. Preoperative diagnosises were unstable angina in 14 of patients, stable angina in 28, postmyocardial infarction state in 15, and state of failed percutaneous transluminal coronary angioplasty in 4. 141 stenosed coronary arteries were bypassed with use of 20 pedicled internal mammary artery and 124 reversed saphenous vein grafts. Postoperative complications and perioperative death were as follows: 1. Of 61 patients undergoing operation, peri and postoperative over all complication occured in 15 patients [ 25% ]; newly developed myocardial infarction in 4, intractable cardiac arrhythmia including atrial fibrillation and frequent ventricular premature contraction in 3, bleeding from gastrointestinal tract in 2, persistent vegetative state as a sequele of brain hypoxia in 1, wound necrosis in 1, left hemidiaphragmatic palsy in 3 and poor blood flow through graft in 2. 2. Operative mortality was 8%[5 patients]. 3 out of these died in operating room; 1 patient by bleeding from rupture of calcified aortic wall, 1 by air embolism through left atrial vent catheter, 1 by low cardiac output syndrome. 2 patients died during hospital stay; 1 by acute respiratory distress syndrome with multiuple organ failure, 1 by brain death after delayed diagnosis of pericardial tamponade.

• International Journal of Oral Biology
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• 제40권2호
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• pp.93-101
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• 2015

The efficacy of air-polishing on subgingival debridement, as compared to scaling and root planning (SRP), was evaluated clinically and microbiologically. Fifteen patients diagnosed as chronic periodontitis, and having single-root tooth over 5 mm of pocket depth symmetrically in the left and right quadrant, were investigated. Subgingival debridement was performed by SRP and air-polishing. The results were evaluated and compared clinically and microbiologically. Probing pocket depth (PPD), bleeding on probing (BOP), relative attachment level (RAL) and change of gingival crevicular fluid (GCF) were assessed before treatment, and at 14 and 60 days after treatment. Microbial analysis was done pre-treatment, post-treatment, and at 14 and 60 days after treatment. Results of air polishing showed that post treatment, the PPD and BOP decreased, and attachment gain was observed. There was no clinical difference when compared to SRP. The volume of GCF decreased at 14 days, and increased again at 60 days. Compared to SRP, there was a statistical significance of the volume of GCF at 60 days in air-polishing. In the microbial analysis, high-risk bacteria that cause periodontal disease were remarkably reduced. They decreased immediately after treatment, but increased again with the passage of time. Thus, our results show that subgingival debridement by air-polishing was effective for decrease of pocket depth, attachment gain, decrease of GCF and inhibition of pathogens. Further studies are required to compare air-polishing and SRP, considering factors such as degree of pocket depth and calculus existence.

• 한국건축시공학회지
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• 제7권3호
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• pp.83-90
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• 2007

This study is to investigate the effects of nylon(NY) and cellulose(CEL) fiber contents on the mechanical properties of the concrete. The results were summarized as following. Test showed that increase of NY and CEL fiber contents decreased fluidity of fresh concrete, so the loss of the fluidity would be considered when they were over added. Air contents were slight increased, but they satisfied the target air content. Bleeding capacity of concrete containing fiber significantly was declined. In addition, concrete containing higher amounts of fiber retarded setting time remarkably. Plastic shrinkage crack was reduced with the use of fiber due to increasing fiber contents and changing fiber classes, and NY fibers to prevent the plastic shrinkage crack effectively. Compressive and tensile strength of almost specimens were increased when air contents of the fresh concrete were fixed according to fiber contents, and flexural strength was increased according to fiber contents. For the impact strength of specimens, the specimen containing $0.6kg/m^3$ of NY fibers, showed the most favorable impact strength, The fiber reinforced concrete using NY fibers exhibited superior mechanical performance, and it was considered that $0.6kg/m^3$ of was desirable as the most favorable adding amount.

• Journal of Chest Surgery
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• 제27권3호
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• pp.221-225
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• 1994

Video-assisted thoracic surgery[VATS] has recently evolved as an alternative to thoracotomy for several thoracic disorders. Between March 1993 and September 1993, 42 patients underwent VATS at Gil General Hospital. They were diagnosed as spontaneous pneumothorax in 34[81.0%], mediastinal mass in 5, congenital lobar emphysema in 1, traumatic hemothorax in 1, and sarcoidosis in 1. For pneumothorax, wedge resection of bullae or blebs was done in 18 patients, wedge resection and limited parietal pleulectomy in 13, and only pleulectomy in 2. And excision for mediastinal mass in 5, hematoma evacuation for chronic hemothorax in 1, biopsies of mediastinal lymph node and lung for confirming sarcoidosis in 1, and lobectomy of left upper lobe for congenital lobar emphysema in the child of 12 years. The period of chest tube drainage and postoperative hospitalization averaged 3.8 days [range, 1 to 11 days] and 5.9 days [range, 2 to 18 days]. Three complications occurred in 3 patients with pneumothorax [7.1%, 2 recurrent pneumothorax and 1 postoperative bleeding], and the conversion to open thoracotomy was done in 1 due to massive air leak. The causes of postoperative air leak were speculated and the techniques for saving expensive Endo-GIA staplers are described in this paper. VATS is safe and offers the benefits of reduced postoperative pain and rapid recovery. Our experience indicates a markedly expanded role for VATS in the diagnosis and treatment of various thoracic diseases.

• Journal of Medicine and Life Science
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• 제17권1호
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• pp.16-20
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• 2020

Spontaneous hemopneumothorax is a rare disease, and it can cause life threatening condition. It is characterized by the accumulation of more than 400 mL of blood and air in the pleural cavity without any other apparent causes. A previously healthy 22-year-old female patient presented with acute chest pain and dyspnea. Chest X-ray and computed tomography revealed a massive hemopneumothorax in the left hemithorax. The images showed a completely collapsed left lung with right-sided tracheal deviation, several pleural adhesion bands, and fluid collection with air-fluid level. We emergently performed a closed thoracostomy, and then 560 mL of fresh bloods were initially drained. We considered an emergent video-assisted thoracoscopic surgery for pulmonary wedge resection and bleeding control because of the massive hemothorax. However, the patient's vital signs were stabilized after blood transfusion and supportive cares for re-expansion pulmonary edema. The patient discharged from the hospital on 11^th in-hospital day after removal of the chest tube, and there had not been any recurrence of the pneumothorax for 10 months. We suggest that treatment strategy should be decided upon individually based on the patient's condition and clinical course of the disease.

• 동력기계공학회지
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• 제17권5호
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• pp.58-63
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• 2013

In this study, the effect of deep ocean condenser inlet temperature ($T_{DOI}$), condenser inlet pressure ($P_{cond,in}$), and thermal diffusivity on system efficiency of some selected refrigerants was analyzed using HYSYS. The proposed DOTEC cycle is similar to the reheat Rankine cycle but eliminates irreversibilities by bleeding a fraction of the steam between certain stages of the turbine. The evaporator inlet mass flow rate, inlet temperature of turbine 1, turbine efficiency and inlet and outlet temperature of heat source were imposed. The working fluids considered are sorted in ascending order of their molecular weights as R717, R600a and R152a. Results indicated that a fluid with a lower boiling point temperature like R717 needs a corresponding high heat source and/or evaporator inlet pressure. Also, the response of thermal diffusivity closely follows the change in TDOI as an increase in $T_{DOI}$ increases $P_{cond,in}$ which reduces thermal diffusivity and system efficiency. Furthermore, the fluid with the nominal boiling point temperature has the highest efficiency with efficiency decreasing with an increase in TDOI.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2008년도 춘계 학술발표회 제20권1호
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• pp.489-492
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• 2008

본 연구에서는 공공 및 민간의 전력수요가 증가함에 따라 화력발전소에서 다량으로 발생하고 있는 석탄재의 약 10${\sim}$15%정도를 차지하는 Bottom Ash를 유효재활용하기 위하여 Bottom Ash 굵은골재 혼입에 따른 콘크리트의 기초적 물성 및 강도특성을 분석하였다. 그 결과, Bottom Ash 굵은골재의 혼입률이 증가할수록 슬럼프는 감소하는 경향을 나타내었으며, 혼입하지 않은 경우에 비하여 약 4.5${\sim}$54.2%정도 감소하였다. 이에 비하여 공기량은 Bottom Ash 굵은골재를 혼입함에 따라 거의 영향이 없고 그 차이는 미소한 것으로 나타났다. 블리딩의 경우는 슬럼프의 경향과 유사하였으며 Bottom Ash 굵은골재의 혼입률이 증가함에 따라 초기의 블리딩이 현저하게 감소하였다. 또한, 압축강도는 Bottom Ash 굵은골재의 혼입률이 증가할수록 감소하였으며 혼입률 40%까지는 혼입하지 않은 경우에 비하여 약 1.1${\sim}$5.3%정도 감소하였고, 혼입률 60% 이상에서 급격히 감소하여 압축강도는 Plain의 약 85.2${\sim}$87.7%정도 발현하였다. 따라서, 콘크리트용 굵은골재로서 Bottom Ash 굵은골재를 대량으로 활용하기 위해서는 강도향상의 보강요소를 사용하는 것이 검토되어야 할 것으로 판단된다.

• Journal of Periodontal and Implant Science
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• 제52권2호
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• pp.116-126
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• 2022

Purpose: This study evaluated the efficacy of treating periodontitis using subgingival nano-hydroxyapatite powder with an air abrasion device (NHAPA) combined with scaling and root planing (SRP). Methods: A total of 28 patients with stage III periodontitis (grade B) were included in this study, although 1 was lost during follow-up and 3 used antibiotics. The patients were divided into a test group and a control group. All patients first received whole-mouth SRP using hand instruments, and a split-mouth approach was used for the second treatment. In the test group, the teeth were treated with NHAPA for 15 seconds at 70% power per pocket. Subgingival plaque samples were obtained from the 2 deepest pockets at the test and control sites before treatment (baseline) and 3 months after treatment. The full-mouth plaque index (PI), gingival index (GI), papillary bleeding index (PBI), bleeding on probing (BOP), probing depth (PD) and clinical attachment level (CAL) were recorded at baseline and at 1- and 3-month post-treatment. Real-time polymerase chain reaction was used to determine the colonisation of Treponema denticola (Td), Porphyromonas gingivalis (Pg), and Aggregatibacter actinomycetemcomitans in the subgingival plaque. Results: From baseline to the first month, the test group showed significantly larger changes in BOP and CAL (43.705%±27.495% and 1.160±0.747 mm, respectively) than the control group (36.311%±27.599% and 0.947±0.635 mm, respectively). Periodontal parameters had improved in both groups at 3 months. The reductions of PI, GI, BOP, PD, and CAL in the test group at 3 months were greater and statistically significant. The total bacterial count and Td and Pg species had decreased significantly by the third month in both groups (P<0.05). Conclusions: Applying NHAPA in addition to SRP improves clinical periodontal parameters more than SRP alone. Subgingival NHAPA may encourage clot adhesion to tooth surfaces by increasing surface wettability.

• Journal of Trauma and Injury
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• 제36권4호
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• pp.435-440
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• 2023

Mesenteric injury occurs rarely in cases associated with blunt abdominal trauma. Despite its low incidence, mesenteric injury can lead to fatal outcomes such as hypovolemic shock due to hemoperitoneum or sepsis due to intestinal ischemia, or perforation-related peritonitis. For mesenteric injuries, especially those involving massive bleeding, intestinal ischemia, and perforation, the standard treatment is surgery. However, in the case of operative management, it should be borne in mind that there is a possibility of complications and mortality during and after surgery. The usefulness of transcatheter arterial embolization (TAE) is well known in solid organs but is controversial for mesenteric injury. We present a 75-year-old man with mesenteric injury due to blunt abdominal trauma. Initial abdominal computed tomography showed no hemoperitoneum, but a mesenteric contusion and pseudoaneurysm with a diameter of 17 mm were observed near the origin of the superior mesenteric artery. Since there were no findings requiring emergency surgery such as free air or intestinal ischemia, it was decided to perform nonoperative management with TAE using microcoils in hybrid emergency room system. TAE was performed successfully, and there were no complications such as bleeding, bowel ischemia, or delayed bowel perforation. He was discharged on the 23rd day after admission with percutaneous catheter drainage for drainage of mesenteric hematoma. The authors believe that treatment with TAE for highly selected elderly patients with mesenteric injuries has the positive aspect of minimally invasive management, considering the burden of general anesthesia and the various avoidable intraoperative and postoperative complications.