• Journal of KSNVE
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• v.8 no.2
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• pp.239-250
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• 1998

Traditionally, intake noise from internal combustion engine has not recevied much attention compared to exhaust noise. But nowadays, intake noise is a major contributing factor to automotive passenger compartment noise levels. The main objective of this paper is to identify the mechanism of generation, propagation and radiation of the intake noise. With a simplest geometric model, one of the main noise sources for the intake stroke is found to be the pressure surge, which is generated after intake valve closing. The pressure surge, which has the nonlinear acoustic behavior, propagates and radiates with relatively large amplitude. In this paper, unsteady compressible Navier-Stokes equations are employed for the intake stroke of axisymmetric model having a single moving cylinder and a single moving intake valve. To simulate the periodic motion of the piston and the valve, unsteady deforming mesh algorithm is employed and Thompson's non-reflecting boundary condition is applied to the radiation field. In order to resolve the small amplitude waves at the radiation field, essentially non-oscillatory(ENO) schemes with an artificial compression method (ACM) are used.

• 한국연소학회:학술대회논문집
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• 2002.11a
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• pp.215-222
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• 2002

It has been well acknowledged that intake system plays great role in the performance of reciprocating engine. Well-designed intake system is expected to not only increase engine efficiency but also decrease engine emission, which is one of the most urgent issues in the automotive society. Thorough understanding of the flow in intake system helps great to design adequate intake system. Even though both experimental and numerical methods are used to study intake flow, numerical analysis is more widely used due to its merits in time and economy. Intake system of In-line 6-Cylinder CNG engine was chosen for the analysis ICEM CFD HEXA was used to create 3-D structured grid and FIRE code was used for the flow analysis in the intake system. Due to the complexity of the geometry standard ${\kappa}-{\varepsilon}$ turbulence model was applied. Numerical analysis was performed for various inlet and outlet boundary conditions under both steady and transient flow. Inlet mass flow rate and outlet pressure variation were changing parameters with respect to engine speed. Flow parameters, such as velocity, pressure and flow distribution, were evaluated to provide adequate data of this intake system.

• Korean Journal of Community Nutrition
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• v.19 no.6
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• pp.537-549
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• 2014

Objectives: This study was conducted to examine blood pressure and other characteristics of a high sodium intake group assessed with 24-hr urine analysis and the dietary factors related to the risk of high sodium intake among Korean adults. Methods: A cross-sectional study was conducted with adults aged 20-59 years. Subjects who completed 24-hr urine collection (N = 205) were divided into 3 groups (tertile) according to the sodium intake estimated with 24-hour urine analysis. We compared the blood pressure, BMI and dietary related factors of the 3 groups (low, medium, high sodium intake group) with General Linear Model (GLM) and Duncan's multiple range test (p < 0.05). The risk factors related to high sodium intake were assessed with odds ratio (p < 0.05). Results: The sodium intake (mg/day) of the 3 groups were $3359.8{\pm}627.9$, $4900.3{\pm}395.1$ and $6770.6{\pm}873.9$, respectively, corresponding to daily salt intake (g/day) 8.5, 12.4 and 17.2, respectively. High sodium group showed significantly elevated age, BMI and systolic/diastolic blood pressure. Being male gender was associated with significantly increased risk of sodium intake (OR = 1.972; 95%CI: 1.083-3.593). The other factors related to high sodium intake were higher BMI (${\leq}25$) (OR = 2.619; 95% CI: 1.368-5.015), current alcohol consumption (OR = 1.943; 95%CI: 1.060-3.564), and having salty soybean paste with salt percentage > 14% (OR = 3.99; 95% CI: 1.404-6.841). The dietary attitude related to increased risk of high sodium intake included 'enjoy dried fish and salted mackerel' (p < 0.001) and 'eat all broth of soup, stew or noodle' (p < 0.001). Conclusions: Because high sodium intake was associated with higher blood pressure, nutrition education should focus on alcohol consumption, emphasis on related dietary factors such as using low salt soybean paste, improvements in the habit of eating dried fish and salted mackerel or eating all broth of soup, stew or noodle.

• Journal of the Korean Society of Food Science and Nutrition
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• v.24 no.1
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• pp.24-29
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• 1995

Purpose of this study was to investigate correlation between blood pressure (systolic and diastolic) and dietary sodium, potassium intake pattern in the family members of normal cerebrovascular (CVA) disease, excluding patients themselves. Both mean values of systolic (125.8$\pm$23.7 vs 119.3$\pm$19.2mmHg) and diastolic(76.1$\pm$16.7 vs 71.6$\pm$12.5mmHg) bllood pressure in the family members of cerebrovascular disease patients were significantly higher than those of normal subjects. Systolic blood pressure was positively correlated with age, weibght, sodium in soybean paste, potassium in hotpepepr paste, soybean paste and meats in normal subjects group. In the family members of cerebrovascular patient, systolic blood pressure was possively correlated with age, weight, sodium in soy sauce, drinking water and potassium in soups. Interestingly, table salt intake was positively correlated with systosolic blood pressure in the family members of cerebrovascular disease patients. Diastolic bolld pressure was positively correlated with age, weight, table salt intake potassium in hotpepper paste and soybean paste in normal subjects group. Diastolic blood pressure was positively correlated with age, weight and table salt intake in the family members of cerebrovascular disease patients. Urinary potassium excretion was negatively correlated with both systolic and diastolic blood pressure in the family members of cerebrovascular disease patients.

• Nutrition Research and Practice
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• v.6 no.5
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• pp.421-428
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• 2012

Several studies revealed that low calcium intake is related to high prevalence of cardiovascular diseases such as hypertension. The prevalence of hypertension is high in Koreans along with their low dietary calcium consumption. Thus, the aim of this study was to evaluate the status of calcium intake between the hypertension and normotension groups and to investigate the correlation between dietary calcium intake and blood pressure, blood lipid parameters, and blood/urine oxidative stress indices. A total of 166 adult subjects participated in this study and were assigned to one of two study groups: a hypertension group (n = 83) who had 140 mmHg or higher in systolic blood pressure (SBP) or 90 mmHg or higher in diastolic blood pressure (DBP), and an age- and sex-matched normotension group (n = 83, 120 mmHg or less SBP and 80 mmHg or less DBP). The hypertension group consumed 360.5 mg calcium per day, which was lower than that of the normotension group (429.9 mg) but not showing significant difference. In the hypertension group, DBP had a significant negative correlation with plant calcium (P < 0.01) after adjusting for age, gender, body mass index (BMI), and energy intake. In the normotension group, total calcium and animal calcium intake were significantly and positively correlated with serum triglycerides. No significant relationship was found between calcium intake and blood/urine oxidative stress indices in both groups. Overall, these data suggest reconsideration of food sources for calcium consumption in management of the blood pressure or blood lipid profiles in both hypertensive and normotensive subjects.

• Journal of the East Asian Society of Dietary Life
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• v.23 no.3
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• pp.282-296
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• 2013

The study classified 83 obese adults by constitution and had them follow a strict diet according to their constitution in order to see if the Yin-Yang method would be effective on the metabolic syndrome, which is one of the main causes of death in Korea. Overall, the application of both Yin and Yang methods improved the following factors: weight, body fat percentage, systolic blood pressure, diastolic pressure, neutral fats and total cholesterol. In particular, the Yin constitution group of men showed more improvements than the Yang constitution group. Furthermore, waist circumference and the prevalence rate of systolic blood pressure, diastolic pressure, total cholesterol and metabolic syndrome were decreased noticeably. Total energy intake was increased in both men and women after the constitutional diet, along with the increase of nutrient intake, such as dietary fiber, vitamins and minerals, among others. Among various nutrients, vitamin A, vitamin C, thiamine, vitamin B6, folic acid, calcium, phosphorus, potassium, magnesium and iron intake were increased noticeably after the constitutional diet. In addition, subjects' intake of all nutrients, except for magnesium, satisfied the nutrition intake standards. Further, the nutrients adequacy ratio (NAR) and the mean adequacy ratio (MAR) improved for both men and women. The intake of potatoes, starch, greens and mushrooms increased noticeably, whereas the intake of meat, dairy, drinks and alcohol decreased after the constitutional diet. For the Yin constitution, the intake of Yin foods noticeably decreased, where as the intake of Yang foods decreased for the Yang constitution. In conclusion, the constitutional diet effectively improves the metabolic syndrome. Among many nutrients, the intake of dietary fiber, vitamins A, C and E, potassium and magnesium is positively associated with the improvement of metabolic syndrome biomarkers.

• Journal of Power System Engineering
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• v.13 no.4
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• pp.11-17
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• 2009

This paper deals with the effects of pulsating flow on volumetric efficiency, which may be generated during the gas exchange procedure, due to piston motion, valve event on intake and exhaust stroke and unsteady flow of turbocharger of a three-cylinder four stroke turbo-charged diesel engine. Consequently, volumetric efficiency affects significantly the engine performance; torque characteristics, fuel economy and further to emission and noise level. As the expansion ratio became larger the engine speed varies and torque increases, the pressure pulsation in an exhaust gas pipe acts as an increasing factor of intake air charging capacity totally. The phase and amplitude of pressure pulsation in the intake system only affects volumetric efficiency favorably, if it is well matched and tuned effectively to the engine. Thus, to verify the exact phase and amplitude of the pressure variation is the ultimate solution for the air-flow ratio assessment in the intake stroke. Some experimental results of pressure diagrams in the intake pipe and gas-flow of turbine in-outlet are presented, under various kinds of operating condition.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.04a
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• pp.581-587
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• 2014

Intake silencers of high performance and with less pressure drop are developed for a household oxygen generator. First, the acoustic power of the target oxygen generator are experimentally evaluated according to ISO code. Then, the transmission loss of and the flow characteristics inside the existing intake silencer are predicted and analyzed. On a basis of these results, two intake silencers are proposed, which are designed to induce the swirling flow inside the intake silencer and thus to reduce the flow loss. The predicted TL and the pressure drop for these two new silencers are compared to the existing one, which shows that the proposed ones have higher TLs as well as less pressure drop. The reason for these improvements are explained by investigating the flow characteristics of the new silencers in detail.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.24 no.11
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• pp.846-853
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• 2014

High performance intake silencer with low pressure drop are developed for a household oxygen generator. First, the acoustic power of the target oxygen generator are experimentally evaluated according to ISO code. Then, the transmission loss of and the flow characteristics inside the existing intake silencer are predicted and analyzed. On a basis of these results, two intake silencers are proposed, which are designed to induce the swirling flow inside the intake silencer and thus to reduce the flow loss. The predicted TL and the pressure drop for these two new silencers are compared to the existing one, which shows that the proposed ones have higher TL as well as low pressure drop. The reason for these improvements are explained by investigating the flow characteristics of the new silencers in detail.

• Journal of Nutrition and Health
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• v.32 no.6
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• pp.671-680
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• 1999

In order to investigate the relationship between plasma renin activity and metabolism of Ca and Na in blood pressure, the habitual dietary intakes of Na and Ca urinary excretion of Ca, Na and K, and plasma level of renin activity, aldosterone, and indices of Ca metabolism were measured in 27 untreated hypertensive women and 30 age-matched normal women on a free diet. Hypertensive subjects were classified into high renin hypertensive (HH), medium renin hypertensive(HM) and low renin showed no significant difference among normotensive, LH, MH and HM groups. It appeared that 25-(OH) Vit D3 level of HH group was significantly higher than LH group(p<0.05). There was significant difference in habitual intake of Ca between normotensive and LH groups. However, habitual intake of Na showed no significant difference among normotensive, LH, MH and HH group. Positive correlation of systolic and diastolic blood pressure with PTH(r=0.324, r=0.375) and urinary Ca(r=0.496, r=0.278) and a negative correlation of systolic blood pressure with habitual Ca intake(r=-0.371) existed(p<0.05). A relative magnitude of factors affecting hypertension was analyzed by multiple regression analysis. Overall results about relative influence of independent variables to dependent variable (systolic blood pressure) indicated that urinary Ca was the higher correlation in all subjects(p<0.0001), followed by age and aldosterone. PTH showed a significant correlation for relative influence on diastolic blood pressure in all subjects. The above results indicated that renin-aldosterone system and Ca regulating hormone had a mutual relationship in hypertension.