• Journal of the Korea Concrete Institute
• /
• v.24 no.5
• /
• pp.509-516
• /
• 2012

The aims of this research is to develop a fire resistant admixture to enhance high-pressured pumping of high-strength concrete (HSC) with a compressive strength of 60~80 MPa. Generally, the efficiency of HSC high-pressured pumping is dramatically reduced due to entanglement of short fibers added to prevent fire spalling. Therefore, the fire resistant admixture that can facilitate pumping of fire resistant HSC is urgently needed presently. The fire resistant HSC mix is comprised of Polypropylene fiber, Nylon fiber and Polymer powder. The test results showed that the slump-flow was improved by approximately 70% of the HSC without fire resistant admixture. However, the air void content was increased slightly due to the addition. The standard design compressive strength at 28-days was satisfied, while its flexural strength was similar to the concrete without the admixture. Since the flexural strength was 12~15% of its compressive strength, the general trend of flexural to compressive strength ratio in normal concrete was maintained. Even though its elastic modulus was decreased by adding the admixture, the study results showed that the concrete can be used for construction since all of the test results exceeded the code requirements.

• Journal of Chest Surgery
• /
• v.38 no.7 s.252
• /
• pp.461-467
• /
• 2005

Pleura, diaphragm, pericardial fat pad, intercostal muscles and omentum can be used to protect and revascularize the bronchial suture line of tracheal transplantation, lung transplantation and pulmonary resection. The purpose of the present study is to compare the influence of the pleura, diaphragm and omentum in survival of isolated tracheal segments in the experimental animals. Material and Method: Sprague-Dawley rats weighing 250- 350g were used. The animals were divided in three groups; the pleura, omentum and diaphragm. Following intraperitoneal anesthesia, endotracheal intubation was performed. Then the trachea was exposed. A three-ring sec- tion of cervical trachea was excised. The resected trachea was implanted at each sites. After 2 weeks, rats were sacrificed. Histopathological examination of the tracheal segments was performed. For comparison of each groups, histopathological viability of resected tracheal segment was scored by three tissue layers; epithelium, submucosa, and cartilage. The results were presented as average score. Result: In histopathological examination, submucosa and cartilage using tracheal segment necrosis scoring system. The pleural group showed well preserved tissue. There was minimal necrosis and inflammation compared with other groups. In the pleural group, tracheal necrosis scores were $2.17\pm0.983$at epithelium, $1.67\pm0.516$ at submucosa and $2.17\pm0.753$ at cartilage. At the omental group, scores were $1.00\pm0.00,\;1.60\pm0.548\;and\;1.80\m0.447$. In the diaphragmatic group, scores were $1.40:\pm0.894,\;2.40\pm0.547\;and\;2.20\pm0.447$. Total necrosis score were $6.00\pm1.789$ in the pleural group, $4.40\pm0.894$ in the omental group and $6.00\pm1.414$ in the diaphragmatic group. Conclusion: There were no significant viability differences in terms of total necrosis score for the viability of resected tracheal segment. But the best result was achieved in the omental group. Therefore, omental wrapping on tracheal graft site will be beneficial for the prevention of graft necrosis.

• Tuberculosis and Respiratory Diseases
• /
• v.48 no.6
• /
• pp.853-869
• /
• 2000

Background : Following several decades of decline, the incidence of tuberculosis has recent1y begun to increase in many countries of this the control of this disease has been impeded by the emergence of multi-drug resistant tuberculosis (MDR-TB). The development of rapid diagnostic methods and effective new drugs are needed to control MDR-TB. One of the new drugs for MDR-TB is rifabutin (RBU) which has been known to be effective in some patients with MDR-TB. A few reports showed that some types of mutations of the rpoB gene, which were known to be present in 96-98% of rifampicin-resistant M. tuberculosis, were associated with the rifampicin-resistant but RBU-susceptible phenotype. This study was performed to investigate the correlation between RBU susceptibility and the patterns of rpoB gene mutations in Korean MDR-TB. Methods : Sixty-five clinical isolates of multi-drug resistant Mycobacterium tuberculosis, gathered from patients who visited the Asan Medical Center from July 1997 to June 1999, were investigated. Clinical responses to rifabutin-containing regimen were evaluated. An RBU susceptibility test and sequencing analysis of rpoB gene were performed, and the results were analyzed to confirm which mutations correlated with RBU-susceptible MDR-TB. Results : Fifty-three of 56 (95%) clinical isolates of MDR-TB had 60 mutations of the rpoB gene. The most frequent mutations were found at codon 531 (43%), and two mutations were combined in seven clinical isolates. Five of 53 (10%) clinical isolates showed the RBU-susceptible phenotype, and in them the characteristic patterns of point mutations were found at codon 509, 516, and 526. Conclusion : The frequency and pattern of mutations of the rpoB gene of Korean MDR-TB isolates were similar to those in western countries, where the prevalence of tuberculosis is low, but some show RBU-susceptible phenotypes. RBU-susceptible MDR-TB isolates showed the characteristic pattern of mutations of the rpoB gene which could be used to rapidly diagnose RBU susceptibility.

• Journal of Veterinary Clinics
• /
• v.28 no.5
• /
• pp.516-518
• /
• 2011

A survey was conducted to examine the normal intestinal bacterial flora of captive Oriental white storks (Ciconia boyciana) maintained at the Korea Institute of Oriental White Stork Rehabilitation Research, Cheongwon, South Korea. From the cloaca of 44 healthy storks, 44 fecal samples were collected and cultured under aerobic and anaerobic conditions. The 16S ribosomal RNA gene sequences and the heat shock protein 60 gene were cloned and sequenced for bacterial identification. Under aerobic conditions, Enterococcus faecalis, Escherichia coli, Bacillus spp., Enterococcus avium, Enterococcus gallinarum, Pseudomonas spp., Alcaligenes spp., Enterobacter spp., Corynebacterium spp., and Proteus mirabilis were identified. Under anaerobic conditions, E. coli, Clostridium tertium, En. faecalis, and P. mirabilis were identified. E. coli, En. faecalis, or both were isolated from all samples. These results will add to the information available on this stork species and help for the interpretation of fecal culture results.

• Journal of radiological science and technology
• /
• v.39 no.4
• /
• pp.509-516
• /
• 2016

A dental panoramic radiography which usually uses low level X-rays is subject to the Nuclear Safety Act when it is installed for the purpose of education. This paper measures radiation dose and spatial dose rate by usage and thereby aims to verify the effectiveness of radiation safety equipment and provide basic information for radiation safety of radiation workers and students. After glass dosimeter (GD-352M) is attached to direct exposure area, the teeth, and indirect exposure area, the eye lens and the thyroid, on the dental radiography head phantom, these exposure areas are measured. Then, after dividing the horizontal into a $45^{\circ}$, it is separated into seven directions which all includes 30, 60, 90, 120 cm distance. The paper shows that the spatial dose rate is the highest at 30 cm and declines as the distance increases. At 30 cm, the spatial dose rate around the starting area of rotation is $3,840{\mu}Sv/h$, which is four times higher than the lowest level $778{\mu}Sv/h$. Furthermore, the spatial dose rate was $408{\mu}Sv/h$ on average at the distance of 60 cm where radiation workers can be located. From a conservative point of view, It is possible to avoid needless exposure to radiation for the purpose of education. However, in case that an unintended exposure to radiation happens within a radiation controlled area, it is still necessary to educate radiation safety. But according to the current Medical Service Act, in medical institutions, even if they are not installed, the equipment such as interlock are obliged by the Nuclear Safety Law, considering that the spatial dose rate of the educational dental panoramic radiography room is low. It seems to be excessive regulation.

• Journal of the Korean Society of Food Culture
• /
• v.7 no.4
• /
• pp.309-321
• /
• 1992

A study was designed to assess the current status of infant feeding and weaning practice through an retrospective survey on feeding method, a period of weaning and various kinds of weaning food. Analysing a few influential environmental factors while assessing the level of knowledge today's mothers have on infant nutrition. The results are as follows: 1. As random samples for this study, a total of 516 mothers having infants under the age of 3 were surveyed. Among them, 235 were from Seoul and 281 were from Kyongi province (Yongin, Suwon, Bupyong, Poil, Kihung, Ansan(Chungbuk)). 2. Among the infants who fell under the category of normality (Kaup index $15{\sim}18$), the infants from Seoul area amounted to 60.7%, surpassing the percentage of the infants from Kyongi province, 41.9%. The percentage of the infants belong to a group of under nutrition (Kaup index <13) was relatively higher than that of the infants in a group of overnutrition (Kaup index >20). 3. 16.1% of mother surveyed were breast-fed, 54.6% were formula-fed and 29.3% were mixed-fed. The result indicated that the percentage of breast-fed infants of high-educated, working mothers were relatively lower than those of low-educated housewives. 4. Most of the respondents knew the significance or the necessity of supplementary food in terms of weaning. 5. 98.8% of those surveyed responded that the mother's adequate knowledge on weaning was necessary. 70.1% of them replied that they wanted to get various and in-depth information in printed materials such as books or other kinds of publications. They, also showed deep interest in recipe of weaning food. 6. The average period when those surveyed began weaning of their infants was $4.3{\pm}1.8$ months. The tendency of earlier weaning in 3 months was founded among 41.1% of them. About half of the respondents, 52.3%, started weaning of their infants in $4{\sim}6$ months. In overall, 93.4% of them set on weaning in less than 6 months after babies were born. The survey, in addition, revealed an interesting fact that earlier weaning of infants was shown in the group of high-educated mothers. 7. According to the study, finishing period of weaning was $13.3{\pm}5.4$ months on average. Only 38.9% of the respondents ended weaning of their infants in 12 months, the proper period recommended by renowned experts. In general, the infants on formula-feeding finished their weaning later than those on breast-feeding (p<0.05).

• Journal of Life Science
• /
• v.22 no.4
• /
• pp.516-523
• /
• 2012

The purpose of this study was to investigate the effect of exercise and/or L-arginine on abdominal fat, IGF-1 on GH/IGF-1 axis, fibrinogen, and PAI-1 in aged and obese rats. Male Sprague-Dawley rats were treated with a D-galactose aging inducing agent (50 mg/kg) given intraperitoneally for 12 weeks. Thirty-two male Sprague-Dawley rats were treated and divided into four groups: aging-high fat diet group (AG+HF), AG+HF with L-arginine intake group (AG+LA), AG+HF with exercise group (AG+EX), and AG+EX with L-arginine intake group (AG+LA+EX). The experimental rats underwent treadmill training (60 min/day, 6 days/week at 0% gradient) for 12 weeks. L-arginine was given orally (150 mg/kg/day) for 12 weeks. After the experiment, blood was collected from the left ventricle and abdominal fat was extracted. The results showed that GH was significantly increased in AG+EX and AG+AL+EX. IGF-1 was significantly increased in both the AG+AL+EX and AG+EX group ($p$<0.05), while fibrinogen and PAI-1 were not significantly different among the groups. Abdominal fat was significantly decreased in the AG+LA, AG+EX, and AG+LA+EX groups ($p$<0.05) compared with the AG+HF group. In conclusion, this study suggests that exercise alone or L-arginine alone or a combination not only increases the GH and IGF-1 concentration, but also decreases the abdominal fat mass.

• Investigative Magnetic Resonance Imaging
• /
• v.8 no.1
• /
• pp.32-41
• /
• 2004

Purpose : To measure the NMR relaxation properties of MnPC, to observe the characteristics of liver enhancement patterns on MR images in experimentally implanted rabbit VX2 tumor model, and to estimate the possibility of tissue specific contrast agent for MnPC in comparison with the hepatobiliary agent. Materials and Methods : Phthalocyanine (PC) was chelated with paramagnetic ions, manganese (Mn). 2.01 g (5.2 mmol) of phthalocyanine was mixed with 0.37 g (1.4 nlmol) of Mn chloride at $310^{\circ}C$ for 36 hours and then purified by chromatography ($CHCl_3:\;CH_3OH=98:2$, volume ratio) to obtain 1.04 g $(46\%)$ of MnPC (molecular weight = 2000 daltons). The T1/T2 relaxivity (R1/R2) for MnPC were determined at a 1.5 T (64 MHz) MR spectrometer. VX2 tumor model was experimentally implanted in the liver parenchyma of rabbits. All MR studies were performed on 1.5 T. The human extremity radio frequency coil of a bird cage type was employed. MR images were acquired at 17 to 24 days after VX2 carcinoma implantation.4 mmol/kg MnPC and 0.01 mmol/kg Mn-DPDP were injected via the ear vein of rabbits. T1-weighted images were obtained with spin-echo (TR/TE=516/14 msec) and fast multiplanar spoiled gradient recalled (TR/TE : 80/4 msec, $60^{\circ}$ flip angle) pulse sequence. Fast spin-echo (TR/TE=1200/85 msec) was used to obtain the T2-weighted images. Results : The value of T1/T2 relaxivity (R1/R2) of MnPC was $7.28\;mM^{-1}S^{-1}$ and $55.56\;mM^{-1}S^{-1}$ respectively at 1.5 T (64 MHz). Because the T2 relaxivity of MnPC that bonded strongly, covalently manganese with phthalocyanine was very high, the signal intensity of liver parenchyma was decreased on postcontrast T2-weighted images and we could easily distinguish the VX2 carcinoma within the liver parenchyma. When MnPC was administrated intravenously, the tumor margin delineation was more remarkable than Mn-DPDP-enhanced images. The enhancement of liver parenchyma with MnPC persisted at relatively high levels over at least one hour after injection of the contrast agents. Conclusion : The hepatic uptake and biliary excretion of MnPC, which are similar to Mn-DPDP, suggest that this agent is a new liver-specific agent. Also, MnPC seems to be used as a dual contrast agent (T1 and T2) with high T2 relaxivity. However, it is warranted that MnPC needs further investigation as a potential contrast agent for MR imaging of the liver. That is, further characterizations of MnPC are needed in vivo and in vitro before clinical trials. The diagnostic potential of MnPC will also have to be examined more in the animal models of additional types.

• The Korean Journal of Physiology and Pharmacology
• /
• v.17 no.6
• /
• pp.511-516
• /
• 2013

Bladder cancer is the seventh most common cancer in men that smoke, and the incidence of disease increases with age. The mechanism of occurrence has not yet been established. Potassium channels have been linked with cell proliferation. Some two-pore domain $K^+$ channels (K2P), such as TASK3 and TREK1, have recently been shown to be overexpressed in cancer cells. Here we focused on the relationship between cell growth and the mechanosensitive K2P channel, TREK2, in the human bladder cancer cell line, 253J. We confirmed that TREK2 was expressed in bladder cancer cell lines by Western blot and quantitative real-time PCR. Using the patch-clamp technique, the mechanosensitive TREK2 channel was recorded in the presence of symmetrical 150 mM KCl solutions. In 253J cells, the TREK2 channel was activated by polyunsaturated fatty acids, intracellular acidosis at -60 mV and mechanical stretch at -40 mV or 40 mV. Furthermore, small interfering RNA (siRNA)-mediated TREK2 knockdown resulted in a slight depolarization from $-19.9mV{\pm}0.8$ (n=116) to $-8.5mV{\pm}1.4$ (n=74) and decreased proliferation of 253J cells, compared to negative control siRNA. 253J cells treated with TREK2 siRNA showed a significant increase in the expression of cell cycle boundary proteins p21 and p53 and also a remarkable decrease in protein expression of cyclins D1 and D3. Taken together, the TREK2 channel is present in bladder cancer cell lines and may, at least in part, contribute to cell cycle-dependent growth.

• Korean Journal of Radiology
• /
• v.23 no.5
• /
• pp.505-516
• /
• 2022

Objective: To evaluate whether artificial intelligence (AI) for detecting breast cancer on mammography can improve the performance and time efficiency of radiologists reading mammograms. Materials and Methods: A commercial deep learning-based software for mammography was validated using external data collected from 200 patients, 100 each with and without breast cancer (40 with benign lesions and 60 without lesions) from one hospital. Ten readers, including five breast specialist radiologists (BSRs) and five general radiologists (GRs), assessed all mammography images using a seven-point scale to rate the likelihood of malignancy in two sessions, with and without the aid of the AI-based software, and the reading time was automatically recorded using a web-based reporting system. Two reading sessions were conducted with a two-month washout period in between. Differences in the area under the receiver operating characteristic curve (AUROC), sensitivity, specificity, and reading time between reading with and without AI were analyzed, accounting for data clustering by readers when indicated. Results: The AUROC of the AI alone, BSR (average across five readers), and GR (average across five readers) groups was 0.915 (95% confidence interval, 0.876-0.954), 0.813 (0.756-0.870), and 0.684 (0.616-0.752), respectively. With AI assistance, the AUROC significantly increased to 0.884 (0.840-0.928) and 0.833 (0.779-0.887) in the BSR and GR groups, respectively (p = 0.007 and p < 0.001, respectively). Sensitivity was improved by AI assistance in both groups (74.6% vs. 88.6% in BSR, p < 0.001; 52.1% vs. 79.4% in GR, p < 0.001), but the specificity did not differ significantly (66.6% vs. 66.4% in BSR, p = 0.238; 70.8% vs. 70.0% in GR, p = 0.689). The average reading time pooled across readers was significantly decreased by AI assistance for BSRs (82.73 vs. 73.04 seconds, p < 0.001) but increased in GRs (35.44 vs. 42.52 seconds, p < 0.001). Conclusion: AI-based software improved the performance of radiologists regardless of their experience and affected the reading time.