• Journal of Energy Engineering
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• v.22 no.1
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• pp.51-57
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• 2013

As energy becomes an important source of power for national competitive force, not only Government administrations but also private sectors are striving to save energy. The purpose of this study is to compare and evaluate energy consumption of the corridor with and without window when improving the energy environment by installing door and window on the open area of entrance for one-side corridor type apartment. The energy usage was examined through this improvement process and the energy consumption amount was compared and analyzed by simulation before and after the installation. It is desired for this study to contribute to the government's green remodeling project.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.1
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• pp.69-75
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• 2009

This paper studies the aerodynamic performance that the vent mixer-new conceptual supersonic mixer-showed with its geometric characteristics. The hole is 2 mm with 2 mm's distance from the wall in case 1 and with no distance in case 2. In case 3 die hole is 1 mm. Case 1 and case 2 showed the same total pressure recovery ratio, of which the case 3 was lower than that. While cases 1-3 had the same reattachment length, the shear layer was thicker in cases 1 and 2 than in case 3. Within the recirculation zone, cases 1 and 2 had lower pressure loss and higher velocity gradient difference than case 3-they enhance mixing between air and fuel. Separation bubble which is developed by the inflow into the recirculation zone has a significant effect on the total pressure recovery ratio in the combustor. Also separation bubble influences pressure distributions and recirculation flows in the recirculation zone. Therefore, inflow rate of air into the recirculation zone mainly affects the performance of vent mixer.

• Smart Structures and Systems
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• v.16 no.2
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• pp.281-294
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• 2015

Bolted joint connection is the most commonly used connection element in structures and devices. The loosening due to external dynamic loads cannot be observed and measured easily and may cause catastrophic loss especially in an extreme requirement and/or environment. In this paper, an innovative Real-time Cross-Correlation Method (RCCM) for monitoring of the bolted joint loosening was proposed. We apply time reversal process on stress wave propagation to obtain correlation signal. The correlation signal's peak amplitude represents the cross-correlation between the loosening state and the baseline working state; therefore, it can detect the state of loosening. Since the bolt states are uncorrelated with noise, the peak amplitude will not be affected by noise and disturbance while it increases SNR level and increases the measured signals' reliability. The correlation process is carried out online through physical wave propagation without any other post offline complicated analyses and calculations. We implemented the proposed RCCM on a single bolt/nut joint experimental device to quantitatively detect the loosening states successfully. After that we implemented the proposed method on a real large structure (reaction wall) with multiple bolted joint connections. Loosening indexes were built for both experiments to indicate the loosening states. Finally, we demonstrated the proposed method's great anti-noise and/or disturbance ability. In the instrumentation, we simply mounted Lead Zirconium Titanate (PZT) patches on the device/structure surface without any modifications of the bolted connection. The low-cost PZTs used as actuators and sensors for active sensing are easily extended to a sensing network for large scale bolted joint network monitoring.

• Journal of Veterinary Clinics
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• v.18 no.2
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• pp.116-123
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• 2001

This study was undertaken to find out the effect of Korean safflower seed powder on histopathological changes of cadmium toxicity in mice. Fifty BALB/c mice were divided into a control group(A) and four experimental groups(B, C, D, E) : group A received tap water and basal diet, group B received tap water and diet supplemented with 3% Korean safflower seed powder alone, group C received basal diet and 300 $\mu\textrm{g}$/g of cadmium, group D and E received basal diet supplemented with 3% and 10% Korean safflower seed powder and 300$\mu\textrm{g}$/g of cadmium respectively. Cadmium dissolved in tap water was used, and the Korean safflower seed powder were mixed with feed. All mice were dissected on the 56th day. Histopathological changes in liver, kidney, lung, cortical osseous tissue of femoral shaft, bone trabecular of femur, and epiphyseal cartilage plate of femur were observed. Group B showed no significant changes compared with the control group. But group C showed the unclearness of specific cells in liver, the loss of architecture and focal necrosis of hepatocyte, the glomerular swelling, degeneration and necrosis of convoluted tubules, desquamation and vacuolization of the greater part of the renal tubular epithelium, the marked congestion and thickness of the wall of alveolus in lung, slightly thinning of the cortical osseous tissue in femoral shaft, reduction of cancellous bone volume and marked narrowness of bone trabecular, marked thinning of epiphyseal cartilage plate and irregular arrangement of columnar structure of cartilage cells. On the other hand, Korean safflower seed powder-treated group showed a little convalescent changes and maintained their normal architectures in liner, kidney, lung, cortical osseous tissue of femoral shaft, bone trabecular of femur and epiphyseal cartilage plate of femur.

• Korean Journal of Microbiology
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• v.53 no.3
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• pp.193-199
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• 2017

This study was aimed to evaluate the antimicrobial activity of Penicillium purpurogenum ED76 on several clinically important microorganisms. The endophytic fungus P. purpurogenum ED76 was previously isolated from Swietenia macrophylla leaf. The antimicrobial efficacy of P. purpurogenum ED76 dichloromethane extract was determined via disc diffusion and broth microdilution assay. A kill curve study was conducted and the morphology of extract treated bacterial cells were viewed under scanning electron microscope. The dichloromethane extract showed significant inhibitory activity on 4 test bacteria and 2 test yeasts. The minimal inhibitory concentration of the extract ranged from 125 to $1,000{\mu}g/ml$, which indicates the different susceptibility levels of the test microorganisms to the fungal extract. The kill curve study has revealed a concentration-dependent inhibition for all test microorganisms. With the increase of the extract concentration, the microbial growth was significantly reduced. The scanning electron micrograph of dichloromethane extract-treated Staphylococcus aureus cells showed the total damage of the cells. The cell wall invagination of the bacterial cells also indicates the loss of cellular materials and metabolic activity. The gas chromatography mass spectrometry analysis of the extract also showed that the major compound was stigmasterol, which constitutes 45.30% of the total area. The dichloromethane extract of P. purpurogenum ED76 exhibited significant inhibitory activity on several clinically important bacteria and yeasts. The study proposed a possible mode of action that the extract cause significant damage to the morphology of S. aureus cells.

• Journal of Chest Surgery
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• v.29 no.3
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• pp.311-314
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• 1996

Eighteen patients (13 female and ave male) aged from 15 to 62 years (mean age 42.6 years) underwent excision of cardiac myxoma(17 left atrial, one right atrial) between 1985 and 1994 at Pusan National University hospital. All patients complained of exertional dyspnea and most had a few additional symtoms including palpitation, chest pain, syncope, general weakness, weight loss, fever, cough and epigastric disconyort. The diagnosis was made by echocardiography alone in left atrial myxomas but a myxoma in right atrium was diagnosed incidentally during mitral valve replacement for rheumatic valvular heart disease. The tumor attachment sites were fossa ovalis in 13, other interatrial septum in 4, mitral valve annulus in one and free wall of left atrium in two cases. The tumor was excised successfully via right atriotomy in 8 and biatriotomy in 10 cases. There was no hospital nor late death, and no recurrent case during the follow up period. Curative surgical excision of cardiac myxoma can be performed with low morbidity and very low r currence rate.

• Journal of Periodontal and Implant Science
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• v.42 no.4
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• pp.127-135
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• 2012

Purpose: The aim of this study was to compare the clinical outcome of open flap debridement (OFD) with a biphasic calcium phosphate (BCP) graft to that of OFD without BCP graft for the treatment of intrabony periodontal defects (IBDs). Methods: The study included 25 subjects that had at least one intrabony defect of 2- or 3-wall morphology and an intrabony component ${\geq}4$ mm as detected radiographically. Subjects were randomly assigned to treatment with (BCP group, n=14) or without BCP (OFD group, n=11). Clinical parameters were recorded at baseline and 6 months after surgery and included the plaque index, gingival index, probing depth (PD), clinical attachment level (CAL), and gingival recession (REC). A stringent plaque control regimen was enforced for all of the patients during the 6-month observation period. Results: In all of the treatment groups, significant PD reductions and CAL gains occurred during the study period (P<0.01). At 6 months, patients in the BCP group exhibited a mean PD reduction of $3.7{\pm}1.2$ mm and a mean CAL gain of $3.0{\pm}1.1$ mm compared to the baseline. Corresponding values for the patients treated with OFD were $2.5{\pm}0.8$ mm and $1.4{\pm}1.0$ mm, respectively. Compared to OFD group, the additional CAL gain was significantly greater in the patients in BCP group (P=0.028). The additional PD reduction was significant for the BCP group (P=0.048). The REC showed a significant increase in both groups, and the amount of recession was significantly smaller in the BCP group than OFD group (P=0.023). In radiographic evaluation, the height of the bone fill in the BCP group was significantly greater than OFD group. Conclusions: The clinical benefits of BCP found in this study indicate that BCP may be an appropriate alternative to conventional graft materials.

• Journal of Periodontal and Implant Science
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• v.44 no.2
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• pp.50-56
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• 2014

Purpose: The aims of this study were to measure the distance of the intraosseous vascular anastomosis in the anterolateral wall of the maxillary sinus from different reference points, and to correlate the location of the intraosseous vascular anastomosis with the tooth position and the residual bone height of the maxilla. Methods: Computed tomography (CT) images were taken from 283 patients undergoing dental implants placement in the posterior maxilla. Three horizontal lines were drawn at the ridge crest, maxillary sinus floor, and the position of the anastomosis. A vertical second line at the center of each tooth was drawn perpendicular to the horizontal lines. The distance from the ridge crest to the maxillary sinus floor and the distance from the maxillary sinus floor to the bony canal were measured from the intersections of the horizontal and vertical lines. The residual alveolar bone height was used to categorize three groups: group 1,<4 mm; group 2, between 4 and 8 mm; and group 3, >8 mm. Results: The residual bone height values of different tooth positions were significantly different (P=0.0002). The distance from the maxillary sinus floor to the intraosseous vascular anastomosis was significantly different between groups 1 and 3 (P=0.0039). At the molar sites, a moderate negative correlation was found between the residual bone height and the distance from the maxillary sinus floor to the intraosseous anastomosis. The distances of the alveolar ridge crest and the maxillary sinus from the intraosseous vascular anastomosis were not significantly different between sexes. Conclusions: Within the limitations of this study, sites with a higher residual bone height in the molar regions were at a relatively high risk of artery damage during window osteotomy preparation; therefore, we recommend taking more precautions when using a lateral approach for sinus elevation.

• KIEAE Journal
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• v.16 no.6
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• pp.167-172
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• 2016

Purpose: The solar water heater with natural circulation has been used for several decades in the world as it is automatically operated without a pump and controller and is easy to maintain and repair. After the subsidy was offered from 2012, the solar water heater with natural circulation is becoming increasingly popular in Korea. Recently, the development of a wall-integrated solar water heater, which improves the applicability of buildings and prevents the overheating in the summer, is being developed. On the other hand, the design and performance evaluation data of solar water heaters are very inadequate, and analysis of heat and flow is required to develop a new type of solar water heater. Method: Therefore, in this study, we proposed a new simplified system analysis model that reflects heat and pressure loss from the test results of KS B ISO 9806-1 (Solar collector test method), assuming that the collector is a simple pipe system, the validity of which was verified through experiments. Result: As a result, first, the RMSE of the system circulation flow rate and the average temperature of the inlet and outlet of the collector according to the experimental results and the simulation are 0.05563 and 0.88530, respectively, which are very consistent. Secondly, the mass flow rate is increased linearly with the increase of the solar radiation, and the mass flow rate is 0.0104 ~ 0.0180kg/s in the range of $200{\sim}380W/m^2$ of solar irradiance. Compared with the test flow rate 0.0764kg / s of the test collector, it showed a level of less than 20%.

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.451-454
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• 2006

This paper describes the results of cold flow test and hot firing tests of an uni-element coaxial swirl injector and hot firing tests of a subscale combustor, as to the development effort of coaxial swirl injector for high performance liquid rocket engine combustor. A major design parameter for coaxial swirl injector is the recess number of a bi-swirl injector. The results of hot firing tests of the uni-element injector combustor and the sub-scale combustor are analyzed to investigate the effect of the recess number influencing on the combustion performance and pressure fluctuation. The test results of a cold flow test of the unielement combustor shows that it was shown that the change in recess number has significant effect on mixing characteristics and efficiency, while the effect of recess number on atomization characteristic is not The results of a series of firing tests using unielement and subscale combustor show that the recess length significantly affects the hydraulic characteristics, the combustion efficiency, and the dynamics of the liquid oxygen/kerosene bi-swirl injector. As a point of combustion performance, combustion efficiencies are 90% for unielement combustor and 95% for subscale combustor. The difference in the characteristic velocities between the unielement combustor and the subscale combustor may be caused by the difference in thermal loss to the combustor wall and the relative lengths of the combustion chamber. For a mixed type coaxial swirl combustor, the pressure drop across the injector increases as recess number becomes larger. The low frequency pressure fluctuation observed in unielement combustor can be related to the propellant mixing characteristics of the coaxial bi-swirl injector. The effect of the recess number on the pressure fluctuation inside the combustion chamber is more significant in un i-element combustor than the subscale combustor, of which the phenomena are also observed in time domain and frequency domain.