• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.10
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• pp.645-651
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• 2016

Effects of pressure-side winglet width on the tip leakage flow and aerodynamic loss downstream of a turbine blade with a pressure-side squealer rim have been investigated for the tip gap-to-span ratio of h/s = 1.36%. The pressure-side squealer has a fixed height-to-span ratio of $h_p/s=3.75%$ and the pressure-side winglet, which is installed at an elevation of tip surface, has width-to-pitch ratios of w/p = 2.64%, 5.28%, 7.92% and 10.55%. The results show that with increasing w/p, aerodynamic loss in the passage vortex region decreases, whereas that in the leakage flow region increases. As a result, the mass-averaged loss coefficient all over the measurement plane tends to decrease minutely with the increment of w/p. It is concluded that the pressure-side winglet for the pressure-side squealer tip can hardly contribute to the tip-leakge loss reduction.

• Gut and Liver
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• v.12 no.6
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• pp.633-640
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• 2018

Background/Aims: Obesity is a risk factor for gastroesophageal reflux disease (GERD), with several studies demonstrating positive associations between body mass index (BMI) and GERD symptoms. However, little is known about the effect of BMI changes on erosive esophagitis (EE). In this study, we investigated whether BMI reduction could resolve EE. Methods: A retrospective cohort study was performed to assess the natural course of EE according to changes in BMI. Participants undergoing health check-ups from 2006 to 2012 were enrolled, and 1,126 subjects with EE were included. The degree of esophagitis was measured by upper endoscopy and serially checked over a 5-year follow-up. Logistic regression and Cox proportional hazards models were used to investigate the association between BMI reduction and EE resolution. Results: Substantial weight loss is associated with EE resolution. The adjusted odds ratio for EE resolution was 1.44 (95% confidence interval [CI], 1.09 to 1.92) among participants with a decrease in BMI compared to those with no decrease in BMI. The EE resolution rate was related to the degree of BMI reduction. The effect of weight loss on EE resolution was higher among subjects who lost more weight. Compared with subjects with no decrease in BMI, the hazard ratios for EE resolution were 1.09 (95% CI, 0.89 to 1.35), 1.31 (95% CI, 1.01 to 1.72) and 2.12 (95% CI, 1.44 to 3.12) in subjects with BMI reductions of ${\leq}1$, 1-2, and >$2kg/m^2$, respectively. Conclusions: EE resolution is associated with a decrease in BMI, and weight loss is potentially an effective GERD treatment.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.7
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• pp.831-840
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• 1999

In this work, an aerothermodynamic calculation model for cooled axial flow turbine blades with trailing edge ejection is suggested and a mean line performance analysis of a turbine stage with nozzle cooling is carried out. A unique model regarding the interaction between coolant and main gas is proposed, while existing correlations are adopted to predict viscous loss and blade outflow angle. The interactions considered are the heat transfer from main gas to coolant and the temperature and pressure losses by the mixing of two streams due to the trailing edge coolant ejection. For a stator blade without ejection, trailing edge loss calculated by the trailing edge analysis is compared with that calculated by loss correlation. The effect of heat transfer effectiveness of coolant passage on the mixing loss is analyzed. For a model turbine stage with nozzle cooling, parametric analyses are carried out to investigate the effect of main design variables(coolant mass flow ratio, temperature and ejection area) on the stage performance.

• Journal of Korean Medical Science
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• v.33 no.50
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• pp.320.1-320.8
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• 2018

Background: Muscle mass and muscle function are related to depressed mood in studies of adults. Like adults, Korean students are highly likely to suffer from decreased muscle mass due to social conditions. In this study, we evaluated the muscle mass status of Korean adolescents and assess the effect of muscle on depressive mood. Methods: A total of 1,233 adolescent boys and girls participants from the Korea National Health and Nutrition Examination Survey were enrolled in our study. Participants underwent dual-energy X-ray absorptiometry for assessment of appendicular muscle mass and completed questionnaires regarding depressed mood, stress, suicidal ideations, and attempts. Results: There was no difference in depressive mood according to muscle mass among boys (P = 0.634); girls with decreased muscle mass had a greater tendency for depressed mood compared to girls with optimal muscle mass (P = 0.023). After adjusting for age, waist circumference-to-height ratio, smoking status, alcohol consumption, frequency of physical activity, self-reported obesity, weight-loss efforts, and monthly household income, girls with low muscle mass (LMM) were 2.60 times more at risk of developing depression than girls with normal muscle mass (95% confidence interval [CI], 1.05-6.49; P = 0.040). This trend was similar for girls with LMM with obesity (95% CI, 1.00-11.97; P = 0.049). Conclusion: Adolescent girls who have insufficient muscle mass are more likely to report depressed mood than girls who have ideal muscle mass. Interventions for maintaining proper muscle mass are required.

• Journal of the Korean Society of Propulsion Engineers
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• v.4 no.3
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• pp.1-10
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• 2000

In order to predict the performance of subsonic/sonic ejector system and to provide fundamental data for a cost effective design, one dimensional gas dynamics theory was applied to the subsonic and sonic ejector systems with the second throat. In the current theoretical analyses, ejector throat area ratio, mass flow ratio and secondary stagnation pressure were derived as a function of the operating pressure ratio of the ejector, and the discharge coefficient of the primary nozzle and the loss coefficient of the diffuser were incorporated into the whole performance of the ejector system. The results of theoretical analysis can be applied to practical industrial use of subsonic and sonic gas ejector systems.

• Journal of the Korean Society of Safety
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• v.32 no.3
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• pp.28-33
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• 2017

In this study, the composite material of expandable graphite was made to the material development for improving such as a composite material of the sandwich panels or material properties of a fire door and was tested by the ISO 1182, ISO 5660-1(Cone calorimeter Method). For the test, the composite material of expandable graphite, what the expandable graphite ratio was increased by respectively 0g~30g, was classified A1,A2, A3, A4, and made to the test specimens. Through cone calorimeter test, peak heat release rate(HRR) and total heat release(THR), expanded thickness and expansion rate of each composite material of expandable graphite, and fire prone crack and mass loss rate after burning was measured. Thus, the effect of the addition of the expandable graphite and whether is suitable for reference as a fire retardant, was analyzed. Consequently the correlation of THR and fire retardant performance rate was confirmed.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.6
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• pp.620-627
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• 2009

Shaking table test was carried out to obtain dynamic characteristics of TLCDs with uniform and non-uniform sections for both horizontal and vertical tubes. The input to the table is harmonic acceleration with constant magnitude. The output is horizontal dynamic force which is measured by load cell installed below the TLCD. Transfer functions are experimentally obtained using the ratio of input and output. Natural frequency, the most important design factor, is compared to that by theoretical equation for TLCDs with five different water levels. System identification process is performed for experimentally obtained transfer functions to find the dynamic characteristics of head loss coefficient and effective mass of TLCDs. It is found that their magnitudes are larger for a TLCD with non-uniform section than with uniform section and natural frequencies are close to theoretical ones.

• Bulletin of the Korean Chemical Society
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• v.18 no.8
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• pp.874-880
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• 1997

Various classes of phospholipids were investigated for the structural determination of fatty acyl groups by fast atom bombardment tandem mass spectrometry (FAB-MS/MS). Phospholipids were desorbed by FAB as molecules chelated with sodium ion (or ions). Collision-induced dissociation (CID) of intact sodium adduct molecular ions ([M+Na]+, [M-H+2Na]+ or [M+Na-2H]-) produced a series of homologous fragment ions via the charge-remote fragmentation along the fatty acid chains. These ions were found useful to locate the double bond positions even for the polyunsaturated fatty acid chains. The regiospecificity of the acyl chain linkages in phosphatidylcholine (PC) could also be determined based on the ratio of relative abundance of the product ions (i.e., [M+Na-85-R2COOH]+ vs [M+Na-85-R1COOH]+) in CID-MS/MS of [M+Na]+. These are generated by the loss of fatty acyl groups at sn-1 and sn-2, respectively, together with the choline group. In all the phospholipid compounds investigated, loss of the fatty acid at the sn-2 position was dominant. The present method was applied to the structural determination of molecular species of phosphatidylglycerols (PG) isolated from cyanobacterium Synechocystis sp. PCC 6803.

• Journal of Korean Medicine for Obesity Research
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• v.17 no.1
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• pp.10-19
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• 2017

Objectives: The aim of study was to investigate the effect of herbal medicine on obesity and to define which seasonal factor could be utilized to make an obesity treatment program more effective. Methods: Three hundred and forty-four subjects were recruited and data were analyzed for weight, body fat, muscular volume, body fat ratio, body mass index (BMI) change and treatment duration. At first, age classification was performed for the comparisons. Moreover, starting season of treatment was categorized to determine it's influence over the treatment. Results: It was found the administration of herbal medicine could diminish every analyzed fields of entire patients. Compared among age groups, there were no significant differences of all fields. However, the categorization of start season showed significant differences of weight, BMI change and treatment duration. In addition, the analysis of assumed 10% weight loss elicited patients started treatment in spring and winter should spend 12 and 13 weeks and summer would be 9.5 weeks. Conclusions: It was found herbal medicine would be effective for female obesity and expected patients could achieve 5.91 kg weight loss for 65.88 days treatment. Summer group had significant shorter treatment duration and it was presumed summer group had more concentration for achievement. Days required for assumed 10% weight loss was calculated to be 84 days in spring, 67 days in summer, 96 days in winter. Hereafter, further controlled study with more numbers of patients should be needed to determine the goal of medical treatment for obesity.

• The Journal of Korean Obstetrics and Gynecology
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• v.29 no.3
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• pp.35-46
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• 2016

Objectives: The aim of this study was to investigate the effect of herbal medicine on obesity and overweight female patients and to gather the information of a proper treatment goal for anti-obesity program in Korean medicine clinic.Methods: 230 subjects were recruited and those data were analyzed for body-mass index (BMI), treatment duration, weight, body fat, muscle volume and body fat/weight loss ratio. It was compared among age groups and severity of obesity.Results: It was achieved to loss 12-13 kg for 105.8 days thru obesity program of Korean medicine clinic. There were no significant differences for BMI loss, weight loss, body fat loss, muscle volume gain and treatment duration among age groups. It was found that there were significant differences among overweight, obesity and severe obesity group for BMI loss, weight loss, body fat loss and muscle volume gain except treatment duration. It was assumed the weight loss for 1 month was 3.2 kg, 4.2 kg, 4.5 kg for each severity group respectively.Conclusions: It was found herbal medicine treatment would be effective for female obesity and expected the patients could achieve 12-13 kg weight loss for 15 weeks treatment including 8-12 weeks herbal medicine administration and BMI loss per month could be 1.22 kg/m², 1.60 kg/m² and 1.70 kg/m² for severity of obesity respectively. Hereafter, further controlled study with more numbers of patients should be needed to determine the goal of medical treatment for obesity.