VaRI 공정 유동해석 간소화 방법에 대한 연구

김영민 ( Yeongmin Kim ),이정완 ( Jungwan Lee ),김정수 ( Jungsoo Kim ),안세훈 ( Sehoon Ahn ),오영석 ( Youngseok Oh ),이진우 ( Yi Jin Woo ),김위대 ( Wiedae Kim ),엄문광 ( Moon-kwang Um ) 한국복합재료학회 2021 Composites research Vol.34 No.4

VaRI(Vacuum assisted Resin Infusion) 공정은 공정비용이 저렴하며, 크기가 큰 복합재 제작에 적합한 OoA(Out of Autoclave) 공정이다. VaRI 공정에서는 원할한 수지 주입을 위해 섬유 상단에 유로망을 적층한다. 수지는 이 유로망을 따라 섬유의 면 방향으로 빠르게 공급되고, 공급된 수지는 다시 섬유의 두께방향으로 함침된다. 면방향의 유동과 두께방향의 유동이 동시에 일어나기 때문에 수지의 유동을 예측하기 힘들며, 수지 주입과정을 예측하기 위해 3D 수치해석 프로그램이 사용되고 있다. 하지만, 3D로 해석하기 위해서 섬유와 유로망의 두께방향에 많은 Element가 필요하고, 이로 인해 제품의 크기가 클수록 해석시간이 오래 걸린다. 따라서 본 연구에서는 3D 유동해석을 2D 해석으로 간소화하여 유동해석에 소요되는 시간을 줄이는 방법을 제시하였다. 3D 유동해석과 간소화된 2D 유동해석을 동일조건에서 비교하여 효용성을 검증하였고, 충진시간 오차율은 약 7%, 유동해석시간 감소율은 약 95%로 나타났다. 또한 3D 해석에서 섬유 상, 중, 하단 간의 유동 전진 거리의 차이가 일정하다는 것을 활용하여 간소화된 2D 유동해석에서도 상, 중, 하단의 유동 전진 거리를 예측할 수 있었다. VaRI(Vacuum assisted Resin Infusion) process, which is cost effective and suitable for manufacturing large-sized composites, is an OoA(Out-of Autoclave) process. For rapid resin infusion in the VaRI process, a DM(distribution media) is placed on top of the fabric. The resin is rapidly supplied in plane direction of the fiber along the DM, and then the supplied resin is impregnated in the out-of-plane direction of fiber. It is difficult to predict the flow of resin because the flow of in-plane direction and the out-of-plane direction occur together, and a 3D numerical analysis program is used to simulate the resin infusion process. However, in order to analyze in 3D, many elements are required in the out-of-plane direction of fabric. And the product size is larger, the longer the analysis time needs. Therefore, in this study, a method was suggested to reduce the time required for flow analysis by simplifying the 3D flow analysis to 2D flow analysis. The usefulness was verified by comparing the 3D flow analysis with the simplified 2D flow analysis at the same conditions. The filling time error was about 7% and the reduction of flow analysis time was about 95%. In addition, by utilizing the constant difference in the flow front between the top, middle, and bottom of the fabric of the 3D analysis, the flow front of the top, middle, and bottom of the fabric can be also predicted in the 2D flow analysis.

Multiple sulfur isotopes and chemical compositions of precipitation in Seoul, Korea

Yeongmin Kim,Insung Lee,Chungwan Lim,James Farquhar 대한지질학회 2013 대한지질학회 학술대회 Vol.2013 No.10

Cu and S isotopic signatures of the Erdenetiin Ovoo porphyry Cu-Mo deposit, northern Mongolia: Implications for their origin and mineral exploration

Kim, Yeongmin,Lee, Insung,Oyungerel, Sodnom,Jargal, Luvsanchultem,Tsedenbal, Tserenjav Elsevier 2019 Ore geology reviews Vol.104 No.-

<P><B>Abstract</B></P> <P>The copper (δ<SUP>65</SUP>Cu) and sulfur (δ<SUP>34</SUP>S) isotope compositions of ore minerals from the Erdenetiin Ovoo porphyry Cu-Mo deposit in northern Mongolia were measured. The δ<SUP>65</SUP>Cu values of Cu (I) sulfide minerals ranged from 0.14‰ to 2.69‰, suggesting that Cu predominantly originated from magmatic sources, whereas Cu (II) minerals such as chrysocolla, malachite and azurite presented much larger variations of δ<SUP>65</SUP>Cu values from −1.01‰ to 10.0‰. The small difference between the primary and secondary Cu sulfide minerals indicates an insignificant influence of Cu isotope fractionation processes during their formation, which may be explained by large mass transport and/or the involvement of biogenic activities. The δ<SUP>65</SUP>Cu values of primary chalcopyrite suggest source heterogeneity and/or the occurrence of isotope fractionation under a high-temperature environment. The positive Δ<SUB>Cu (II) mineral − Cu (I) mineral</SUB> values imply little transport of Cu in the deposit, with a rough mass balance and fast redox reaction.</P> <P>The δ<SUP>34</SUP>S values of the primary sulfide minerals (pyrite, molybdenite and chalcopyrite) clustered near 0‰, indicating that the sulfur is mainly derived from a homogeneous magmatic source. By contrast, the δ<SUP>34</SUP>S values of secondary Cu sulfide minerals ranged from −3.2‰ to −0.3‰, with an average of −1.6‰. The lower δ<SUP>34</SUP>S values are likely influenced by either S isotope fractionation processes or input of sulfur with different S isotope compositions during their formation.</P> <P>The measured δ<SUP>65</SUP>Cu and δ<SUP>34</SUP>S values of these ore minerals suggest a large mass transportation of Cu to an adjacent location, indicating little possibility of a hidden Cu occurrence in the Erdenetiin Ovoo deposit area.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We measured the δ<SUP>65</SUP>Cu and δ<SUP>34</SUP>S values of major ore minerals in the Erdenetiin Ovoo porphyry Cu-Mo deposit, northern Mongolia. </LI> <LI> We examined the Cu isotope fractionation processes among Cu minerals during their formation. </LI> <LI> We discussed the implication of Cu and S isotopic signatures on their sources and mineral exploration. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Utilization of Waste Wood as a Source for Renewable Energy in Daejeon, Korea

( Yeongmin Kim ),( Jaehyuk Hyun ),( Kiseok Lee ) 한국폐기물자원순환학회(구 한국폐기물학회) 2015 한국폐기물자원순환학회 3RINCs초록집 Vol.2015 No.-

Meeting government’s policy direction, this study will contribute to energy efficiency, increase of economic feasibility, and reduction of global warming through recycling waste energy along with securing and distributing new and renewable energy. The purpose of this study was to investigate plan of stable disposal, plan of utilizing it in a variety of ways, and plan of recycling combustible waste resource energy, based on the analysis of the amount and characteristics of waste wood generated in Daejeon metropolitan city. The findings of this study provided that waste wood in Daejeon metropolitan was characterized as useful resource as incinerating disposal through simple crushing, and was adopted without generating other synthesized or special process. The results based on criteria analysis of solid refuse fuel showed that moisture was assessed according to criteria for fluff type and caloric value well had above 3,000Kcal/Kg based on low-heating value, while items of ash component, chlorine, sulfur, and heavy metal were all below criteria. Using wood pellet manufactured in Daejeon metropolitan city, the results of comparative analysis of generating efficiency in new model of waste incineration facilities and conventional waste incinerator in Sinil-dong, and SRF exclusive power plant show that cost-saving effect can be expected the most in SRF exclusive power plant, followed by conventional waste incinerator in Sinil-dong and a new model of waste incineration.

Tracing metabolic flux in vivo: basic model structures of tracer methodology

Kim Il-Young,Park Sanghee,Kim Yeongmin,Kim Hee Joo,Wolfe Robert R. 생화학분자생물학회 2022 Experimental and molecular medicine Vol.54 No.-

Molecules in living organisms are in a constant state of turnover at varying rates, i.e., synthesis, breakdown, oxidation, and/or conversion to different compounds. Despite the dynamic nature of biomolecules, metabolic research has focused heavily on static, snapshot information such as the abundances of mRNA, protein, and metabolites and/or (in)activation of molecular signaling, often leading to erroneous conclusions regarding metabolic status. Over the past century, stable, non-radioactive isotope tracers have been widely used to provide critical information on the dynamics of specific biomolecules (metabolites and polymers including lipids, proteins, and DNA), in studies in vitro in cells as well as in vivo in both animals and humans. In this review, we discuss (1) the historical background of the use of stable isotope tracer methodology in metabolic research; (2) the importance of obtaining kinetic information for a better understanding of metabolism; and (3) the basic principles and model structures of stable isotope tracer methodology using 13C-, 15N-, or 2H-labeled tracers.

Multiple oxygen (¹⁶O, ¹⁷O and ¹⁸O) and sulfur (³²S, ³³S, ³⁴S and ³⁶S) isotope signatures of the dissolved sulfate from Deception Island, Antarctic Peninsula: Implications on sul

Kim, Yeongmin,Lee, Insung,Seo, Jung Hun,Lee, Jong Ik,Farquhar, James Elsevier 2017 Chemical geology Vol.466 No.-

<P><B>Abstract</B></P> <P>Oxygen (<SUP>16</SUP>O, <SUP>17</SUP>O and <SUP>18</SUP>O) and sulfur (<SUP>32</SUP>S, <SUP>33</SUP>S, <SUP>34</SUP>S and <SUP>36</SUP>S) isotope ratios of and major ion (Na<SUP>+</SUP>, Ca<SUP>2+</SUP>, Cl<SUP>−</SUP>, NO<SUB>3</SUB> <SUP>−</SUP> and SO<SUB>4</SUB> <SUP>2−</SUP>) concentrations in lakes, ponds and creeks from Deception Island, Antarctic Peninsula were analyzed to study the sources of sulfate, its oxidation, and the surficial processes of the dissolved sulfate. The positive relationship between the δ<SUP>34</SUP>S<SUB>sulfate</SUB> (8.1‰ to 17.3‰) and the Cl<SUP>−</SUP>/SO<SUB>4</SUB> <SUP>2−</SUP> molar ratio suggests mixing of sulfate from atmospheric deposition and from oxidation of sulfide minerals. The average sea salt fraction (28%) and δ<SUP>34</SUP>S<SUB>nss</SUB> values (from 5.6‰ to 15.9‰) indicate that a combination of sea salt and marine biogenic sulfide provide the high δ<SUP>34</SUP>S end-member of the dissolved sulfates. The relatively low δ<SUP>18</SUP>O<SUB>sulfate</SUB> (from −4.6‰ to 0.7‰) of Deception Island water suggests a role of local water in the formation of sulfate. Slightly negative but mass-dependent Δ<SUP>17</SUP>O<SUB>sulfate</SUB> values imply that atmospheric oxidation by O<SUB>3</SUB> and H<SUB>2</SUB>O<SUB>2</SUB> are negligible, while these values might suggest a significant role of oxidation by molecular oxygen and OH. The distinctly low δ<SUP>34</SUP>S<SUB>sulfate</SUB> value of two samples (DCW-2 and DCW-3) suggests the input of sulfate from sulfide oxidation. Slight elevation of δ<SUP>34</SUP>S<SUB>sulfate</SUB> values up to 17.3‰ compared to a typical atmospheric value indicates a minimal role for dissimilatory microbial sulfate reduction of Deception Island water and sediments. Both Δ<SUP>33</SUP>S<SUB>sulfate</SUB> and Δ<SUP>36</SUP>S<SUB>sulfate</SUB> values are homogeneous and near zero, implying that the dominant atmospheric oxidation process is tropospheric and that there are minimal to no contributions of stratospheric sulfate to Deception Island water.</P>

A comparative performance analysis on daylighting for two different types of solar concentrators: Dish vs. Fresnel lens

Kim, Yeongmin,Jeong, Hae Jun,Kim, Wonsik,Chun, Wongee,Han, Hyun Joo,Lim, Sang Hoon Elsevier 2017 ENERGY Vol.137 No.-

<P><B>Abstract</B></P> <P>This study introduces the experimental work done to analyze the performance of active daylighting systems, which consist of small individually operated solar concentrators. Each system is capable of precise solar tracking thanks to the double axis solar tracker designed and constructed for lightness and easy operation. A solar tracking algorithm was implemented with AVR based on both closed and open loop control algorithms. Two different types of solar concentrators (developed for the system) were tested to assess their photometric characteristics in collecting and delivering solar rays to a deep plan office space for better lighting. To measure illuminance at different times of the day, a number of photo sensors were installed on the task planes at a height of 85 cm above the floor. The luminance values on different walls (including task planes) were also measured at a regular interval of 30 min to assess their variation with time and solar altitude. These photometric data enabled a systematic performance evaluation of the systems employed in the present study. The experimental results demonstrated the applicability of the daylighting systems employed in this work in bringing natural daylight to the interior, especially, to those spaces too deep for conventional daylighting apertures.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Two different types of solar concentrators are compared for daylighting performance. </LI> <LI> A series of measurements were performed side by side for an actual office space. </LI> <LI> Some practical suggestions are made when using a daylighting system in view of energy efficiency. </LI> <LI> Results are introduced leading to an innovative fiber optic system to harvest daylight in buildings. </LI> </UL> </P>

Thermal-flow analysis of a simple LTD (Low-Temperature-Differential) heat engine

Kim Yeongmin,Kim Won Sik,Jung Haejun,Chen Kuan,Chun Wongee 한국에너지학회 2017 에너지공학 Vol.26 No.1

해수온도차발전 적용을 위한 자기열량효과 발전시스템 성능연구

김영민(Yeongmin Kim),양용우(Yong Woo Yang),고윤정(Yoonjung Ko),오승진(Seung Jin Oh) 대한설비공학회 2022 대한설비공학회 학술발표대회논문집 Vol.2022 No.6

This study aimed to performance analysis of a magnetocaloric effect power generation system that can be operate at a low temperature difference of ocean thermal energy conversion system. The major components of the system are gadolinium(Gd) and permanent magnet, rotational motion is generated by the interaction of gadolinium with a permanent magnet. The electromagnetic and piezoelectric generator were connected to the gadolinium rotor, and the power generation performance by rotational motion was measured. The electromagnetic generator generated an output of open voltage 2V and a short circuit current 6mA when the temperature difference between hot and cold water was about 6.5℃ and the rotation speed was 130rpm. Under the same conditions, the piezoelectric generator produced an open circuit voltage and a short circuit current of 8V and 8.2μA, respectively.

Hot mirror를 이용한 고밀도 태양광의 광분리에 관한 기초실험 연구

김영민(Yeongmin Kim),모용현(Yonghyun Mo),신상웅(Sangwoong Shin),오승진(Seungjin Oh),천원기(Wongee Chun) 한국에너지학회 2014 에너지공학 Vol.23 No.4