Numerical Simulation of Mold Filling Processes of Castings by using of Predictor-two step Corrector-VOF

Sun, Xun,Wang, Junqing,Hwang, Ho-Young,Choi, Jeong-Kil 한국주조공학회 2002 한국주조공학회지 Vol.22 No.6

수정된 SIMPLE법과 VOF의 결합으로 predictor-two step corrector-VOF라고 불리는 새로운 알고리즘이 주조 시 용탕 충전과정을 해석하기 위해 개발되었다. 운동량보존으로부터 유도된 새 2단계 속도 경계조건 처리법은 용탕의 자유표면을 추적하는 데 사용되었다. 본 연구에서는 2개의 예제 계산을 통해 계산정확도와 속도에 대한 Courant 수의 영향을 살펴보았다. 그 결과 적당한 Courant 수의 증가는 계산 정확도의 감소 없이 용탕 계산 속도를 향상시킬 수 있는 것으로 나타났다. 또한 만족할 만한 계산 정확도와 효율이 이 알고리즘의 실제 제품 해석을 통해 얻어졌다.

Multi-objective optimization of a Stairmand cyclone separator using response surface methodology and computational fluid dynamics

Sun, Xun,Kim, Sung,Yang, Seung Deok,Kim, Hyun Soo,Yoon, Joon Yong Elsevier Sequoia 2017 Powder technology Vol.320 No.-

<P><B>Abstract</B></P> <P>The performance of a cyclone is generally assessed using the pressure drop and the collection efficiency of the cyclone. In the present paper, a multi-objective optimization of a classic Stairmand cyclone separator is executed using the response surface methodology (RSM), combined with computational fluid dynamics (CFD) techniques for minimizing the pressure drop and maximizing the collection efficiency. Ten cyclone geometrical factors are considered in this work. Three of them are studied using the RSM according to the results of the preceding screening experiments. The second-order response surface models for each response are successfully carried out using the central composite design (CCD) in the RSM. The desirability function approach is used to optimize the geometrical factors of the cyclone. In comparison to the reference model, the optimal cyclone model decreases the pressure drop by 20.70% and the cut-off size by 75.38%. The accuracies of the response surface models are confirmed and the correctness of the optimal cyclone model is also validated using CFD; the results indicate excellent performance and reliability of the response surface model and the RSM optimization result. According to the analyses of the obtained flow fields, there are several reasons why decreases in the cut-off size with a lower pressure drop are found in the optimal model. The primary reasons for improvements are optimized values of relevant geometrical factors, the production of a distinct, undisturbed downward flow, an increase in the tangential velocity at the near wall region, and a decrease in the peak tangential velocity.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A multi-objective optimization of a Stairmand cyclone is executed. </LI> <LI> Nine geometrical factors and two objective functions are considered. </LI> <LI> Response surface methodology and computational fluid dynamics are utilized. </LI> <LI> The reasons leading to improve the performance are explained in detail. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Numerical investigation of the effect of surface roughness on the flow coefficient of an eccentric butterfly valve

Xun Sun,김현수,양승덕,김철규,윤준용 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.6

Butterfly valves are used widely as flow controllers in many industrial applications. In order to design and select an appropriate valvefor a particular application, it is important to predict correctly its flow coefficient. The flow coefficient of a valve can be affected by anumber of factors. This study presents a numerical investigation of the effect of friction on the flow coefficient of a triple eccentric butterflyvalve with various valve opening degrees. Since the Reynolds number and cavitation can affect the flow coefficient under certainconditions, these effects are discussed and analyzed based on previously reported experimental data before studying the effects of friction. Under the test conditions recommended in IEC 60534-2-3, it is found that the effects of the Reynolds number and cavitation are quitesmall and can be ignored. The flow coefficients obtained from numerical simulations that take into account friction are found to be ingood agreement with the experimentally determined ones. The differences in the flow coefficients obtained from numerical simulationsthat consider friction and those that ignore it are discussed. There is a maximum difference of 17 % for a fully open valve. The resultsshow that increases in the roughness height significantly increase the frictional pressure drop. The effect of the roughness height on thefrictional pressure drop and total pressure drop can be fitted well using fitting functions for fixed opening degree. It is found that the effectof the roughness can cause the determined flow coefficient to be different from the actual value. Thus, the measured flow coefficientsand pressure drops for such valves can be determined with accuracy through experimental techniques and numerical simulationsthat account for the effect of roughness.

Optimizing the Novel Formulation of Liposome-Polycation-DNA Complexes (LPD) by Central Composite Design

Sun, Xun,Zhang, Zhirong The Pharmaceutical Society of Korea 2004 Archives of Pharmacal Research Vol.27 No.7

LPD vectors are non-viral vehicles for gene delivery comprised of polycation-condensed plasmid DNA and liposomes. Here, we described a novel anionic LPD formulation containing protamine-DNA complexes and pH sensitive liposomes composed of DOPE and cholesteryl hemisuccinate (Chems). Central composite design (CCD) was employed to optimize stable LPD formulation with small particle size. A three factor, five-level CCD design was used for the optimization procedure, with the weight ratio of protamine/DNA ($X_1$), the weight ratio of Chems/DNA ($X_2$) and the molar ratio of Chems/DOPE in the anionic liposomes ($X_3$) as the independent variables. LPD size ($Y_1$) and LPD protection efficiency against nuclease ($Y_2$) were response variables. Zeta potential determination was utilized to define the experimental design region. Based on experimental design, responses for the 15 formulations were obtained. Mathematical equations and response surface plots were used to relate the dependent and independent variables. The mathematical model predicted optimized $X_1-X_3$ levels that achieve the desired particle size and the protection efficiency against nuclease. According to these levels, an optimized LPD formulation was prepared, resulting in a particle size of 185.3 nm and protection efficiency of 80.22%.

Optimizing the Novel Formulation of Liposome-Polycation-DNA Complexes (LPD) by Central Composite Design

Xun Sun,Zhirong Zhang 대한약학회 2004 Archives of Pharmacal Research Vol.27 No.7

LPD vectors are non-viral vehicles for gene delivery comprised of polycation-condensed plasmid DNA and liposomes. Here, we described a novel anionic LPD formulation containing protamine- DNA complexes and pH sensitive liposomes composed of DOPE and cholesteryl hemisuccinate (Chems). Central composite design (CCD) was employed to optimize stable LPD formulation with small particle size. A three factor, five-level CCD design was used for the optimization procedure, with the weight ratio of protamine/DNA (X1), the weight ratio of Chems/ DNA (X2) and the molar ratio of Chems/DOPE in the anionic liposomes (X3) as the independent variables. LPD size (Y1) and LPD protection efficiency against nuclease (Y2) were response variables. Zeta potential determination was utilized to define the experimental design region. Based on experimental design, responses for the 15 formulations were obtained. Mathematical equations and response surface plots were used to relate the dependent and independent variables. The mathematical model predicted optimized X1-X3 levels that achieve the desired particle size and the protection efficiency against nuclease. According to these levels, an optimized LPD formulation was prepared, resulting in a particle size of 185.3 nm and protection efficiency of 80.22%.

바로크 스타일 회화작품이 현대 아트메이크업 디자인에 미치는 영향분석

조정,김혜균 한국브랜드디자인학회 2021 브랜드디자인학연구 Vol.19 No.1

과거의 예술 영감은 오늘날의 디자인과 일상생활에 심대한 영향을 끼쳤다. 다시 말해 디자인은 우리 주변의 삶과 항상 밀접하게 연관되어 있으며 서로 분리되어 있지 않다. 이런 예술사적 배경에서 메이크업 디자인은 소비자들의 미적 감성과 감성을 자극하는 분야가 되기도 한다. 이러한 메이크업 디자인의 발달은 소비자들의 욕구를 충족시켜 오늘날의 사회문화에 순응하고 있다. 본 연구는 고전주의 시절 바로크 스타일 회화의 미적 특징을 알아보고 화가 피터 루벤스의 회화에 참고할 만한 요소를 분석하는 것이 연구의 목적이다. 이를 토대로 바로크 스타일을 현대 메이크업 디자인에 접목해 보는 것이 본 연구의 최종적인 목적이라 할 수 있다. 이론적인 배경에 관하여 국내외 전문 문헌 선행연구 및 인터넷 데이터, 회화 작품 조사 연구를 살펴봤다. 또한 바로크풍의 미학적 특징을 보다 정확하게 분석하기 위해 바로크풍의 대표 화가인 작품을 선택했다. 이를 위해 오브제로 사용된 메이크업 디자인, 색채 분석, 전체적인 스타일링 세 가지 방식으로 기존의 단일 창작 개념에서 벗어나 새로운 미의식을 창출할 수 있는 토대를 마련하고 7개의 메이크업 디자인을 제작 연출하고 제시하였다. 연구결과. 바로크 스타일을 바탕으로 한 현대 메이크업 디자인의 특징은 다음과 같다. 첫째, 다양한 오브제가 사용되어 메이크업 디자인에 미적 감각을 불어넣는 작용을 하였고 둘째, 색채 분석에서 바로크적인 과장과 질감, 생동감 있는 색상의 사용, 강렬한 명암을 보여주며 셋째, 화려한 의상과 간단한 메이크업의 강력한 대비로 아름다운 미를 추구하였다. The artistic inspiration of the past had a profound effect on today's design and daily life. In other words, design is always closely related to life around us and is not separated from each other. Against this periodic backdrop, makeup design can also be a field that stimulates consumers' aesthetic and emotional feelings. However, the development of make-up design should also meet the needs of consumers and adapt to today's social culture. The purpose of the study is recognize the aesthetic features of Baroque style painting in classical times and to analyze the elements to refer to in the painting of painter Peter Rubens. Based on, the purpose of this study is incorporate Baroque style into modern makeup design. The research of this paper is done through theoretical background and data and analysis. On the theoretical background, we looked at domestic and foreign professional literature data and internet data and research on painting works. He also chose the work, which is the representative artist of Baroque style, to more accurately analyze the aesthetic characteristics of Baroque style. To this end, the object was used to create seven makeup designs in three ways: makeup design, color analysis, and overall styling. It has laid the foundation for creating a new sense of beauty away from the existing single creative ideology.

수질계측시스템의 버블트랩에 대한 수치해석적 연구

쑨쉰(Sun Xun),이웅엽(Woong Yup Lee),김현수(Hyun Soo Kim),양승덕(Seung Deok Yang),윤준용(Joon Yong Yun) 대한기계학회 2015 대한기계학회 춘추학술대회 Vol.2015 No.11

The present paper utilized the CFD (computation fluid dynamics) technique to investigate the bubble flow in a bubble trap. The distributions of bubble and pressure of the flow field resulting from the simulation for various shapes and bubble sizes were studied, respectively. The simulations indicate the basic characteristic and the variation of the bubble flow in the device. The main mechanism which can eliminate the bubbles in the device were illuminated.

캐비테이션 가열 장치의 로터 면에 위치한 딤플 및 형상에 관한 수치해석적 연구

손손(SUN Xun),신명섭(Myung Seob Shin),이웅엽(Woong Yup Lee),이여진(Yeo Jin Lee),엄애선(Ae Som Om),윤준용(Joon Yong Yun) 대한기계학회 2014 대한기계학회 춘추학술대회 Vol.2014 No.11

This paper presents numerical investigation of local cavitation phenomena of water due to the rotor with highly rotational speed which in the heater. The standard k-epsilon turbulence model, the Mixture multiphase model and the Schnerr ? Sauer cavitation model were selected. The simulations provided insight into the flow field characteristics inside the heater. The pressure fields and the volume fractions of vapor were predicted respectively for different shapes of rotor. Through the comparison of each case, the optimum solution of the generation of vapor was obtained, which means the best design for heating.

수력학적 공동현상을 이용한 온수 발생 장치에서의 회전체 형상에 대한 수치해석적 연구

손손(Xun Sun),신명섭(Myung Seob Shin),이웅엽(Woong Yup Lee),엄애선(Ae Som Om),윤준용(Joon Yong Yoon) 한국유체기계학회 2017 한국유체기계학회 논문집 Vol.20 No.2

Depression and the Risk of Breast Cancer: A Meta-Analysis of Cohort Studies

Sun, Hui-Lian,Dong, Xiao-Xin,Cong, Ying-Jie,Gan, Yong,Deng, Jian,Cao, Shi-Yi,Lu, Zu-Xun Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.8

Background: Whether depression causes increased risk of the development of breast cancer has long been debated. We conducted an updated meta-analysis of cohort studies to assess the association between depression and risk of breast cancer. Materials and Methods: Relevant literature was searched from Medline, Embase, Web of Science (up to April 2014) as well as manual searches of reference lists of selected publications. Cohort studies on the association between depression and breast cancer were included. Data abstraction and quality assessment were conducted independently by two authors. Random-effect model was used to compute the pooled risk estimate. Visual inspection of a funnel plot, Begg rank correlation test and Egger linear regression test were used to evaluate the publication bias. Results: We identified eleven cohort studies (182,241 participants, 2,353 cases) with a follow-up duration ranging from 5 to 38 years. The pooled adjusted RR was 1.13(95% CI: 0.94 to 1.36; $I^2=67.2%$, p=0.001). The association between the risk of breast cancer and depression was consistent across subgroups. Visual inspection of funnel plot and Begg's and Egger's tests indicated no evidence of publication bias. Regarding limitations, a one-time assessment of depression with no measure of duration weakens the test of hypothesis. In addition, 8 different scales were used for the measurement of depression, potentially adding to the multiple conceptual problems concerned with the definition of depression. Conclusions: Available epidemiological evidence is insufficient to support a positive association between depression and breast cancer.