• Journal of Technologic Dentistry
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• v.33 no.1
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• pp.93-102
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• 2011

Purpose: The study aimed to evaluate working environment for dental technician by measuring dust level, ventilation conditions and the use of personal protective equipment and to provide basic information required to improve working environment and develop health education programs for dental technician. Methods: A total of 240 dental technician who are registered with the Daegu Association of Dental technician and working at 34 dental laboratories participated in the study. And the dust level was measured at 21 different spots in 16 dental laboratories out of 34. Results: Of 34 dental laboratories, 31 (91.2%) were equipped with a ventilator, but the remaining 3 (8.8%) did not have a ventilator. By the number of ventilator, 1 to 3 ventilators were found in 22 dental laboratories (71.0%), 4 to 6 ventilators were in 7 laboratories (22.5%) and more than 7 ventilators in 2 laboratories(6.5%). According to the frequence of changing filters in dust collector, 20 dental laboratories (58.9%) changed filters every four weeks, 10 laboratories (29.4%) changed them every six weeks and 4 laboratories (11.7%) changed them every eight weeks. Of total respondents, 114 (61.3%) said they wore a mask all the time while working, 56 (29.6%) said they frequently wore a mask, 19 (10.1%) said they did not wear a mask. As for the type of masks, 159 (84.1%) used a disposable mask, 25 (13.2%) used a cotton mask and 5 (2.7%) used an anti-dust mask. For dust sat on their outfits while working, 102 (54.0%) shook their uniforms inside workplace to keep dust off the uniforms, 64 (33.9%) did not anything until they wash their uniforms and 23 (12.1%) shook their uniforms outside workplace to keep dust off the uniforms. Of total respondents, 182 (96.3%) had a particle in their eyes while carrying out grinding work. Based on the measurement of floating dust at workplace, 3 dental laboratories showed dust concentration exceeding the minimum level of 10 mg/$m^3$ allowed under the permit for environment. Of those, 1 laboratory had the dust concentration that was more than 1.5 times higher than the minimum level. Dust concentration was higher in laboratories that used a dust collector with 0.5 horse power and changed filters more than 3 weeks ago. Dust comprised of nickel (more than 70%), chrome (9%) and others. The mean chrome concentration was more than twice higher than the minimum permissible level of 0.5 mg/$m^3$. There were two laboratories that showed chrome concentration exceeding the level of 0.4 mg/$m^3$. Like dust concentration, chrome level was higher in laboratories that used a dust collector with 0.5 horse power and changed filters more than 3 weeks ago. There were six laboratories that had nickel concentration exceeding the minimum permissible level of 1 mg/$m^3$. Of those, one laboratory had nickel concentration that was more than three times higher than the minimum permissible level. Nickel concentration was also higher in laboratories that used a dust collector with 0.5 horse power and changed filters more than 3 weeks ago. Conclusion: It is not likely that heavy metal concentrations found in the study constitute respiratory dust. It is however necessary for health of dental technician to apply the Industrial Safety and Healthy Law to dental laboratories and make recommendations for the use of personal protective equipment, installation of a proper number of ventilators, more frequent change of filters in dust collector and improved ventilation for polishing work. At the same time, dental technician need education on how to use personal protective equipment and how to efficiently remove dust from their uniforms.

• Sleep Medicine and Psychophysiology
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• v.6 no.1
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• pp.52-60
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• 1999

Objectives: With the object of finding the appropriate conditions and algorithms for dimensional analysis of human EEG, we calculated correlation dimensions in the various condition of sampling rate and data aquisition time and improved the computation algorithm by taking advantage of bit operation instead of log operation. Methods: EEG signals from 13 scalp lead of a man were digitized with A-D converter under the condition of 12 bit resolution and 1000 Hertz of sampling rate during 32 seconds. From the original data, we made 15 time series data which have different sampling rate of 62.5, 125, 250, 500, 1000 hertz and data acqusition time of 10, 20, 30 second, respectively. New algorithm to shorten the calculation time using bit operation and the Least Trimmed Squares(LTS) estimator to get the optimal slope was applied to these data. Results: The values of the correlation dimension showed the increasing pattern as the data acquisition time becomes longer. The data with sampling rate of 62.5 Hz showed the highest value of correlation dimension regardless of sampling time but the correlation dimension at other sampling rates revealed similar values. The computation with bit operation instead of log operation had a statistically significant effect of shortening of calculation time and LTS method estimated more stably the slope of correlation dimension than the Least Squares estimator. Conclusion: The bit operation and LTS methods were successfully utilized to time-saving and efficient calculation of correlation dimension. In addition, time series of 20-sec length with sampling rate of 125 Hz was adequate to estimate the dimensional complexity of human EEG.

• Tuberculosis and Respiratory Diseases
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• v.40 no.4
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• pp.390-394
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• 1993

Background: Bronchiectasis is characterized by chronic sputum production and complications such as hemoptysis and repeated infections. Even though some patients are cured by surgical resection of bronchiectatic lesions, most bronchiectasis patients can not be treated surgically because of multiple site involvement, and they are treated by medical measures such as postura1 drainage and antibiotics when indicated. Recently there have been some reports that low-dose longterm erythromycin treatment is effective on bronchiectsis, and it is well known that low-dose longterm erythromycin treatment is the treatment of choice in diffuse panbronchiolitis which is characterized by chronic sputum production and dyspnea. To evaluate the efficacy of erythromycin, we tried erythromycin on twenty five stable bronchiectasis patients for more than six months. Methods: We tried erythromycin 250 mg b.i.d. for more than 6 months. We checked respiratory symptoms, chest PA, spirometry, and side effects before treatment and after 3 and 6 months of treatment. Results: 1) 32% of the patients showed marked improvement of symptoms and PFT. 32% showed slight improvement of symptoms with little change of PFT, and 36% showed no change of symptoms and signs. 2) Analysis of the patients showing marked improvement revealed that most of them had diffuse bronchiectasis and paranasal sinus involvement. Conclusion: These results suggest that low-dose longterm erythromycin treatment can be tried on diffuse bronchiectasis patients with sinus involvement. And further studies will be followed on the mechanism of erythromycin in bronchiectasis.

• Tuberculosis and Respiratory Diseases
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• v.43 no.6
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• pp.936-944
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• 1996

Background: Neutrophils or monocytes separated in vitro by the adherence to plastic surface are known to be activated by surface adherence itself and subsequent experimental data might be altered by surface adherence. Adhesion molecules and gene transcription of the inflammatory mediators are known to be associated in this process. To evaluate whether adhesion molecule and transcriptional activation of the inflammatory substances are also involved in the activation of human alveolar macrophage by the adherence procedure, we designed this experiment. Method : Bronchoalveolar lavage was performed in the person whose lung of either side was confirmed to be nonnal by chest cr and alveolar macrophage was harvested. To measure the expression of Interleukin-8(IL-8) mRNA, manganese superoxide dismutase(SOD) mRNA and CD11/CD18 mRNA in human alveolar macrophage of both adherence state and suspension state, Northern blot analysis was done at 0, 2, 4, 8 and 24hrs after the adherence to plastic surface and during suspension state. Then, phorbol myristate acetate(pMA) and N-formyl-methionyl-leucyl-phenylalanine(fMLP) were added respectively in the same experimental condition. Result : 1) Human alveolar macrophages in the adherent state induced IL-8 mRNA and SOD mRNA expression which was maximal at 8 hours after the adherence to plastic surface. But we could not observe the upregulation of CD18 mRNA by surface adherence. 2) PMA induced these mRNA expression both in the adherent cell and the nonadherem cells, but the induction of mRNA expression by fMLP occurred only in the adherent cells. Conclusion: These results suggest that adherence of huamn alveolar macropahge is an important cell-activating event that may play a critical role in the modulation of lung inflammatory respones.

• Clean Technology
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• v.18 no.4
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• pp.390-397
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• 2012

Removal characteristics of lead-contaminated soil at the military shooting range located in the Changwon city were studied experimentally using soil washing process. As a washing solution, hydrogen chloride (HCl) concentrations of 0.001, 0.01, 0.1 and 0.2 N were used, and soil : solution ratios were 1 : 2, 1 : 3, 1 : 4, and 1 : 5. Particle diameter of contaminated soil of 4-0.075 mm, and washing period of 5, 10, 15, 20, 30, 60, and 120 min were used as operating parameters. The optimum concentration of HCl solution was 0.1 N (56.3% of Pb removal efficiency) with 15 minutes operation period in views of economics, and the optimum soil : solution ratio was determined as 1 g : 3 mL for 69.7% of Pb removal efficiency with 0.1 N HCl and 15 minutes washing period. As washing period increased, removal efficiency was increased until 20 min of the removal efficiency of 75.3%, and then almost stable. Pb removal efficiency in soil particle diameters of 0.075 mm or more was ranged from 77.0% to 82.0%, but it was decreased to 52.8% in diameter of less than 0.075 mm. Therefore, the optimum cut-off size of the soil particle diameter was found less than 0.075 mm. Combined HCl solution and ultrasonic washing method showed better removal efficiency compared to only water or HCl washing method for particle sizes above 0.075 mm.

• Tuberculosis and Respiratory Diseases
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• v.43 no.2
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• pp.210-220
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• 1996

Background : Neutrophils or monocytes separated in vitro by the adherence to plastic surface are known to be activated by surface adherence itself and subsequent experimental data might be altered by surface adherence. In the process of surface adherence, adhesion molecules have a clear role in intracellular signal pathway of cellular activation. Human alveolar macrophages(HAM) are frequently purified by the adherence procedure after bronchoalveolar lavage. But the experimental data of many reports about alveolar macrophages have ignored the possibility of adhesion-induced cellular activation. Method : Bronchoalveolar lavage was performed in the person whose lung of either side was confirmed to be normal by chest CT. With the measurement of hydrogen peroxide release from adherent HAM to plastic surface and non-adherent HAM with or without additional stimulation of phorbol myristate acetate(PMA) or N-formyl-methionyl-leucyl-phenylalanine (fMLP), we observed the effect of the adherence to plastic surface. We also evaluated the effect of various biological surfaces on adhesion-induced activation of HAM. Then, to define the intracellular pathway of signal transduction, pretreatment with cycloheximide, pertussis toxin and anti-CD11/CD18 monoclonal antibody was done and we measured hydrogen peroxide in the culture supernatant of HAM. Results : 1) The adherence itself to plastic surface directly stimulated hydrogen peroxide release from human alveolar macrophages and chemical stimuli such as phorbol myristate acetate(PMA) or N-formyl-methionyl-leucyl-phenylalanine(fMLP) colud not increase hydrogen peroxide release in these adherent macrophages which is already activated. 2) PMA activated human alveolar macrophages irrespective of the state of adhesion. However, fMLP stimulated the release of hydrogen peroxide from the adherent macrophages, but not from the non-adherent macrophages. 3) HAM adherent to A549 cell(type II alveolar epithelium-like human cell line) monolayer released more hydrogen peroxide in response to both PMA and fMLP. This adherence-dependent effect of fMLP was blocked by pretreatment of macrophages with cycloheximide, pertussis toxin and anti-CD18 monoclonal antibody, Conclusion : These results suggest that the stimulatory effect of PMA and fMLP can not be found in adherent macrophage because of the activation of human alveolar macrophage by the adherence to plastic surface and the cells adhered to biologic surface such as alveolar epithelial cells are appropriately responsive to these stimuli. It is also likely that the effect of fMLP on the adherent macrophage requires new protein synthesis via G protein pathway and is dependent on the adhesion between alveolar macrophages and alveolar epithelial cells by virtue of CD11/CD18 adhesion molecules.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.19 no.1
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• pp.94-131
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• 2007

A review on the papers published in the Korean Journal of Air-Conditioning and Refrigerating Engineering in 2004 and 2005 has been done. Focus has been put on current status of research in the aspect of heating, cooling, air-conditioning, ventilation, sanitation and building environment. The conclusions are as follows. (1) Most of fundamental studies on fluid flow were related with heat transportation of facilities. Drop formation and rivulet flow on solid surfaces were interesting topics related with condensation augmentation. Research on micro environment considering flow, heat, humidity was also interesting for comfortable living environment. It can be extended considering biological aspects. Development of fans and blowers of high performance and low noise were continuing topics. Well developed CFD and flow visualization(PIV, PTV and LDV methods) technologies were widely applied for developing facilities and their systems. (2) The research trends of the previous two yews are surveyed as groups of natural convection, forced convection, electronic cooling, heat transfer enhancement, frosting and defrosting, thermal properties, etc. New research topics introduced include natural convection heat transfer enhancement using nanofluid, supercritical cooling performance or oil miscibility of $CO_2$, enthalpy heat exchanger for heat recovery, heat transfer enhancement in a plate heat exchanger using fluid resonance. (3) The literature for the last two years($2004{\sim}2005$) is reviewed in the areas of heat pump, ice and water storage, cycle analysis and reused energy including geothermal, solar and unused energy). The research on cycle analysis and experiments for $CO_2$ was extensively carried out to replace the Ozone depleting and global warming refrigerants such as HFC and HCFC refrigerants. From the year of 2005, the Gas Engine Heat Pump(GHP) has been paid attention from the viewpoint of the gas cooling application. The heat pipe was focused on the performance improvement by the parametric analysis and the heat recovery applications. The storage systems were studied on the performance enhancement of the storage tank and cost analysis for heating and cooling applications. In the area of unused energy, the hybrid systems were extensively introduced and the life cycle cost analysis(LCCA) for the unused energy systems was also intensively carried out. (4) Recent studies of various refrigeration and air-conditioning systems have focused on the system performance and efficiency enhancement. Heat transfer characteristics during evaporation and condensation are investigated for several tube shapes and of alternative refrigerants including carbon dioxide. Efficiency of various compressors and expansion devices are also dealt with for better modeling and, in particular, performance improvement. Thermoelectric module and cooling systems are analyzed theoretically and experimentally. (5) According to the review of recent studies on ventilation systems, an appropriate ventilation systems including machenical and natural are required to satisfied the level of IAQ. Also, an recent studies on air-conditioning and absorption refrigeration systems, it has mainly focused on distribution and dehumidification of indoor air to improve the performance were carried out. (6) Based on a review of recent studies on indoor environment and building service systems, it is noticed that research issues have mainly focused on optimal thermal comfort, improvement of indoor air Quality and many innovative systems such as air-barrier type perimeter-less system with UFAC, radiant floor heating and cooling system and etc. New approaches are highlighted for improving indoor environmental condition as well as minimizing energy consumption, various activities of building control and operation strategy and energy performance analysis for economic evaluation.

• Journal of The Korean Society of Grassland and Forage Science
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• v.32 no.3
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• pp.245-252
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• 2012

This study was carried out to investigate the effects of three different locations of Sorghum ${\times}$ sorghum hybrid (SSH) silage on nutritive values and qualities of SSH square bale silage (SSBS) and gunny bag silage (GBS). SSH "SS405" was sown at early May, harvested at heading stage and ensiled. Samples of SSH silage used in this study were collected in three different locations (outer, middle and inner). The content of crude protein (CP) in GBS showed a slightly decreased trend, as compared to SSBS. However, the contents of neutral detergent fiber (NDF) was significantly different between SSBS and SBS (p<0.05). However, The contents of CP, NDF, acid detergent fiber (ADF) and total digestible nutrient (TDN), and in vitro dry matter digestibility (IVDMD) were not different between the parts of SSH silage. Nutritive values of SSBS and SBS were not influenced by inoculation of lactic bacteria. The content of lactic acid in SSBS was decreased as compared to SBS, but there was no significant difference between SSBS and SBS. The content of acetic acid in SSBS was significantly decreased (p<0.05), as compared to SBS. In addition, the contents of lactic acid, acetic acid and butyric acid were not different between the parts of SSH silage. Therefore we suggest that nutritive values and quality of SSBS and SBS were not influenced by parts of sampling collected from these silages.

• Journal of Gastric Cancer
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• v.7 no.3
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• pp.132-138
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• 2007

Purpose: In Korea, the number of laparoscopy-assisted distal gastrectomies for early gastric cancer patients has been on the increase. Although minimally invasive surgery is more beneficial, no reported case of a total laparoscopic gastrectomy has been reported because of difficulty with intracorporeal anastomosis. This study attempts, through our experience, to determine the safety and feasibility of a total laparoscopic gastrectomy with various types of intracorporeal anastomosis using laparoscopic linears stapler in treating early gastric carcinomas. Materials and Methods: We investigated the surgical results and clinicopatholgical characteristics of 81 patients that underwent a totally laparoscopic distal gastrectomy at our department between June 2004 and May 2007. The intracorporeal anastomoses were performed by using laparoscopic linear staplers. Results: The mean operative time was 287 minutes, the mean anastomotic time was 40 minutes, and the mean number of laparoscopic linear staplers used for an operation was 7.5. The mean time to the first flatus, the first food intake, and discharge from hospital was 2.9, 3.6, and 10.3 days respectively. There were 11 cases of postoperative complications, but no case of postoperative mortality or conversion to an open procedure. In 75 patients with an adenocarcinoma, the mean number of lymph nodes harvested was 38.1 and the stage distribution was as follows: stage I, 72 patients; stage II, 2 patients; stage IV, 1 patient. During the mean follow-up period of 14 months, 5 patients died of other causes and there were no cases of cancer recurrence. Conclusion: A total laparoscopic gastrectomy with intracorporeal anastomosis by using a laparoscopic linear stapler was found to be safe and feasible. We were able to obtain acceptable surgical outcomes in terms of minimal invasiveness.

• Journal of Gastric Cancer
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• v.7 no.3
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• pp.139-145
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• 2007

Purpose: An uncut Roux-en-Y gastrojejunostomy has been known to be effective in preventing bile reflux gastritis in the remnant stomach and the Roux stasis syndrome. Materials and Methods: To evaluate the usefulness of a totally laparoscopic uncut Roux-en-Y gastrojejunostomy (TLuRYGJ) after a distal gastrectomy, we reviewed the medical records of 19 consecutive patients that underwent a TLuRYGJ at our institution, and 11 consecutive patients who underwent a totally laparoscopic Billroth I gastrectomy (TLB-I) during the same period. Results: Postoperative gastrointestinal symptoms related to the postgastrectomy syndrome and the Visick classification at six months after surgery were not different in the two groups; however, there was no case of symptomatic bile reflux gastritis and only one case of delayed gastric empting, for which medication was required, in the TLuRYGJ group. The endoscopic findings of the remnant stomach for bile reflux gastritis at six months after surgery were better in the TLuRYGJ group than in the TLB-I group. Conclusion: A TLuRYGJ was found to be effective in preventing bile reflux gastritis and the Roux stasis syndrome.