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Hyo-Seo Kwak,Chul Kim 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.11
A rack module is used to load a tube trailer with Compressed natural gas (CNG) pressure vessels and transport them. While driving, vibration is inevitable due to rough road surface and engine torque. Furthermore an automotive collision could lead to the destruction of the rack module and pressure vessels, and cause gas leakage or the explosion of the pressure vessels. In this study, the structural integrity of a rack module, whose total weight is about 28.6 tons including 20 high pressure vessels, is evaluated by both crash test and impact analysis. The fatigue failure of the rack module is predicted under impact loading caused by collision and under repeated loading due to vibration.
Kwak, Hyo-Seo,Li, Sheng-Huan,Kim, Chul Korean Society for Precision Engineering 2016 International Journal of Precision Engineering and Vol.17 No.8
An internal gerotor pump is used to enhance the oil hydraulics of machine tools, automotive engines and compressor. In particular, this type of pump is used to supply lubricants in an automotive engine. Recently, improvements in automobile fuel efficiency and the reduction of noise have become critical issues. Thus, gerotor internal oil pumps have been studied for high flow rate and low noise through designs of multiple combined lobe shapes. In this study, in order to address the problems of existing oil pumps, design of a new lobe shape with 2-ellipses was developed in order to decrease a sharp change of curvature. Performance parameters of an improved gerotor (2-ellipses) were calculated and compared with those of the existing gerotor (circle and 3-ellipses). Also, we performed a computational fluid dynamics (CFD) analysis of an oil pump with the improved gerotor 2-ellipses-combined lobe shape. By using the commercial software ANSYS CFD, geometric parameters relating to the port shape, which affect the performance of flow rate and irregularity, were investigated. A re-design of the port shape was performed in order to improve fuel efficiency and reduce the noise of the oil pump.
타원 1-타원형 인벌루트-타원 2 로브 형상의 제로터 최적 설계
곽효서(Hyo Seo Kwak),이승환(Sheng Huan Li),김철(Chul Kim) 대한기계학회 2015 大韓機械學會論文集A Vol.39 No.12
제로터(Gerotor) 오일펌프는 구조가 간단하고 1 회전당 토출량이 많기 때문에 소형화에 유리하며, 자동차의 엔진 윤활유 공급원 및 자동 변속기의 유압원으로 널리 사용되고 있다. 최근 자동차 산업에서는 연비향상 및 소음저감이 가장 중요한 문제로 대두되는데, 내접형 기어펌프 측면에서는 제로터의 치형설계 및 포트형상 설계를 통하여 이를 대처하고 있다. 이에 본 논문에서는 유량맥동이 매우 작은 값을 가지도록 조합된(타원 1-타원형 인벌루트-타원 2) 외부로브 형상에 대하여 치형의 기구학적 조건을 만족하는 식을 유도하여 내부로브 형상을 창출하였으며, 이에 대한 첨점 및 루프가 발생하지 않는 설계인자 범위를 결정하였다. 또한 설계인자의 변화가 치형의 형상 및 성능인자(유량, 유량맥동)에 미치는 영향을 파악하여 최적의 치형을 구하고자 하였다. A gerotor can be manufactured in a miniature size because it has a high discharge per cycle and a simple structure. Gerotors are widely used for the lubrication oil of an engine and as the hydraulic source of an automatic transmission. Recently, improvements in fuel efficiency and noise reduction have come to the fore in the automobile industry, and it has been necessary for better fuel efficiency to continuously improve the flow rate and noise of internal gear pumps through the optimal design of the gerotor and port shape. In this study, gerotors were generated based on the equations derived for a lobe shape with multiple profiles (ellipse 1-elliptical involute-ellipse 2). The ranges of the design parameters were considered to prevent a cusp and loop. In addition, the optimal lobe shape was obtained by determining the influence of the lobe shape on the performances (flow rate, irregularity, etc.), according to the values of the design parameters.
Ursolic acid in health and disease
Seo, Dae Yun,Lee, Sung Ryul,Heo, Jun-Won,No, Mi-Hyun,Rhee, Byoung Doo,Ko, Kyung Soo,Kwak, Hyo-Bum,Han, Jin The Korean Society of Pharmacology 2018 The Korean Journal of Physiology & Pharmacology Vol.22 No.3
Ursolic acid (UA) is a natural triterpene compound found in various fruits and vegetables. There is a growing interest in UA because of its beneficial effects, which include anti-inflammatory, anti-oxidant, anti-apoptotic, and anti-carcinogenic effects. It exerts these effects in various tissues and organs: by suppressing nuclear factor-kappa B signaling in cancer cells, improving insulin signaling in adipose tissues, reducing the expression of markers of cardiac damage in the heart, decreasing inflammation and increasing the level of anti-oxidants in the brain, reducing apoptotic signaling and the level of oxidants in the liver, and reducing atrophy and increasing the expression levels of adenosine monophosphate-activated protein kinase and irisin in skeletal muscles. Moreover, UA can be used as an alternative medicine for the treatment and prevention of cancer, obesity/diabetes, cardiovascular disease, brain disease, liver disease, and muscle wasting (sarcopenia). In this review, we have summarized recent data on the beneficial effects and possible uses of UA in health and disease managements.
Seo, Dae Yun,Ko, Jeong Rim,Jang, Jung Eun,Kim, Tae Nyun,Youm, Jae Boum,Kwak, Hyo-Bum,Bae, Jun Hyun,Kim, Amy Hyein,Ko, Kyung Soo,Rhee, Byoung Doo,Han, Jin MDPI AG 2019 INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES Vol.20 No.24
<P>Diabetes mellitus is associated with cardiovascular, ophthalmic, and renal comorbidities. Among these, diabetic cardiomyopathy (DCM) causes the most severe symptoms and is considered to be a major health problem worldwide. Exercise is widely known as an effective strategy for the prevention and treatment of many chronic diseases. Importantly, the onset of complications arising due to diabetes can be delayed or even prevented by exercise. Regular exercise is reported to have positive effects on diabetes mellitus and the development of DCM. The protective effects of exercise include prevention of cardiac apoptosis, fibrosis, oxidative stress, and microvascular diseases, as well as improvement in cardiac mitochondrial function and calcium regulation. This review summarizes the recent scientific findings to describe the potential mechanisms by which exercise may prevent DCM and heart failure.</P>