Sn-xAg-0.5Cu 무연 솔더 볼의 파단특성 연구

정종설,이용성,신기훈,정성균,장동영 한국공작기계학회 2008 한국공작기계학회 춘계학술대회논문집 Vol.2008 No.-

This paper presents a study on the failure characteristics of SnAgCu lead-free solder balls. To estimate the effect of Ag, three types of SnAgCu balls are first prepared by varying the weight percent of Ag (1.0, 3.0, 4.0 wt%) and then analyzed by reliability tests such as thermal shock, high speed ball shear, and drop tests. Thermal shock test reveals that the higher the weight percent of Ag is, the longer the fatigue life becomes. To the contrary, high speed ball-shear test and drop test show that the shear strength and the fracture toughness of solder balls are inversely proportional to the weight percent of Ag, respectively. Reasons for these observations will be further investigated in the future work.

기판 레벨 플립칩의 반복 굽힘 시험기의 개발

이용성,정종설,신기훈,정성균 한국공작기계학회 2007 한국공작기계학회 추계학술대회논문집 Vol.2007 No.-

Circuit board assemblies experience various mechanical loadings during assembly and in actual use. The repeated cyclic bending can cause electrical failures due to circuit board cracks, solder interconnects cracks, and the component cracks. This paper presents a cylic bending tester developed especially for evaluating the reliability of board level flip chips under the repeated cyclic bending. The tester employs the concept of 4-point bending test and complies to JEDEC standard No. 22B113 that is intended to evaluate and compare the performance of surface mount electronic components in an accelerated test environment. The performance of the tester will be estimated through the cross check of the test results in the future work.

障碍者 Recreation의 成立史에 관한 考察 : Avedon의 三國志 [引用]을 중심으로

金成龍,薛甲石 군산대학교 1989 論文集 Vol.16 No.-

In this study the authors investigated into the quotations of chinese "Sam Kuk Chi" cited by Avedon E.M.in his book "Therapeutic Recration Service Prentice Hall Inc 1974" As a result of the Preceding the followings are dedicated" (1)Chinese "Sam Kuk Chi" cited by Avedon Was not from Original one as an official History he quoted it from a novel of Sam Huk Chi being translated into English. (2)It is hard to say that Hua To engaged in a game of wei-chi during the opera-tion in the novel was the historycal precedent as recreative therapy or therapeutic recreation because this was neither prescribed by kuan Yu nor play "Go" for restoring physical conditions by Hua To, (3)It is hard to say that "the sports of Five Amimals" Cited by Avedon is the Historyical precedlent as therapeutic recreation because which is a kind of medical gymnastic Called Dau Yim"

보드 레벨 플립칩의 4점 굽힘 시험 시 파단 특성 연구

이용성,정종설,이재헌,신기훈,정성균 한국공작기계학회 2008 한국공작기계학회 춘계학술대회논문집 Vol.2008 No.-

In general, circuit board assemblies experience various mechanical loadings during assembly and in actual use. The repeated cyclic bending can cause electrical failures due to circuit board cracks, solder interconnects cracks, and the component cracks. In this paper, we report on the failure characteristics of board level flip chips under the repeated cyclic bending. We first describe a new 4-point bending tester, which is developed according to JEDEC standard No.. 22B113. The performance of the tester is then estimated through actual experiments . Test results reveal that the cracks first occur on the outer balls around 20,000 cycles and gradually propagate to the inner balls where cracks are found around 70,000 cycles.

Degradation of the Retinoblastoma Tumor Suppressor Protein by the Human Papillomavirus-16 E7 Variants

Seong Ho Tae,Chul Hee Choi,Eun Ju Choi,Young Lae Cho,Je Chul Lee,Sung Yong Seol,Dong Taek Cho,Yoo Chul Lee 대한미생물학회 2005 Journal of Bacteriology and Virology Vol.35 No.2

A new method of fabricating robust freeform 3D ceramic scaffolds for bone tissue regeneration

Seol, Young‐,Joon,Park, Dong Yong,Park, Ju Young,Kim, Sung Won,Park, Seong Jin,Cho, Dong‐,Woo Wiley Subscription Services, Inc., A Wiley Company 2013 Biotechnology and bioengineering Vol.110 No.5

<P><B>Abstract</B></P><P>Fabrication of three‐dimensional (3D) scaffolds with appropriate mechanical properties and desired architecture for promoting cell growth and new tissue formation is one of the most important efforts in tissue engineering field. Scaffolds fabricated from bioactive ceramic materials such as hydroxyapatite and tricalcium phosphate show promise because of their biological ability to support bone tissue regeneration. However, the use of ceramics as scaffold materials is limited because of their inherent brittleness and difficult processability. The aim of this study was to create robust ceramic scaffolds, which have a desired architecture. Such scaffolds were successfully fabricated by projection‐based microstereolithography, and dilatometric analysis was conducted to study the sintering behavior of the ceramic materials. The mechanical properties of the scaffolds were improved by infiltrating them with a polycaprolactone solution. The toughness and compressive strength of these ceramic/polymer scaffolds were about twice those of ceramic scaffolds. Furthermore, the osteogenic gene expression on ceramic/polymer scaffolds was better than that on ceramic scaffolds. Through this study, we overcame the limitations of previous research on fabricating ceramic scaffolds and these new robust ceramic scaffolds may provide a much improved 3D substrate for bone tissue regeneration. Biotechnol. Bioeng. 2013; 110: 1444–1455. © 2012 Wiley Periodicals, Inc.</P>

Growth characteristics and saponin content of mountain-cultivated ginseng (Panax ginseng C. A. Meyer) according to seed-sowing method suitable for cultivation under forest

Seong Hyeon Yong,Yeong Rong Seo,Hak Gon Kim,박동진,Yuwon Seol,Eunji Choi,Jeong Hee Hong,MYUNG SUK CHOI 한국산림과학회 2020 Forest Science And Technology Vol.16 No.4

Mountain-cultivated ginseng (MCG) is a very important health functional material in Korea and the USA. In this study, the growth and saponin of MCG change according to the sowing method were investigated. Six methods of sowing according to the natural cultivation method that grows in the Sancheong mountain ginseng farm were investigated. Germination rate and budding rate were different according to the sowing method. The growth characteristics of the MCG were also different in the sowing method. Among the six sowing methods, the length of leaves was the widest in BFS. The width of the leaves was wide in DFS and DS. The weight of the shoot was the heaviest in BFS, and the DF was the lightest. Root diameter was highest in BFS and DFS covering both fallen leaves and soil. Total fresh weight was the highest at 4.03 g in BFS, followed by DFS. The S/R ratio of DF was lower than that of the other methods. This suggests that the S/R ratio is lowered because the growth of the ground part is worse. The treatment group with the highest crude saponin content was BF and the lowest treatment group was BS. Shoot and root growth tended to increase with growing period, saponin content increased slightly within 1–3 years, but decreased slightly after that. In particular, the ratio of PD/PT, which has a great influence on the efficacy of ginseng, was also different according to the sowing method. The seed sowing method identified in this study will greatly contribute to the improvement of the survival rate decrease over the cultivation period, and it will also con�tribute to the production of high-quality MCG.

Effect of TongbBiEum(TBE) on Hyperlipidemia Induced by a Sucrose-rich Diet

Yong-Seong Oh,Yoon-Sik Kim,In-Chan Seol 대한한의학회 2003 대한한의학회지 Vol.24 No.4

Objectives : This study was aimed to elucidate the effects of TBE on hyperlipidemia. Methods : We studied the effects of TBE on hyperlipidemia through gene expressions related with lipid metabolism, serum triglyceride as well as total and HDL-cholesterol levels, and perceived histological changes. Results : The present studies demonstrate that TBE can reduce the rise in plasma cholesterol, TG levels induced by a high cholesterol diet and also reverse pre-established hypercholesterolemia and hypertriglycemia. In TBE group total cholesterol levels decreased, TG levels decreased, but HDL-cholesterol levels decreased. In the analysis of absolute and relative liver weight, TBE inhibited the weight gain induced by high cholesterol diet. In the histological observations, lipid droplet and apoptotic change in the TBE treated group were less compared with control group. In the serum biochemical analysis, the difference of serum AST and ALT changes among groups was not shown, but TG and total cholesterol levels were less and HDL level decreased compared with control group. In the gene expression related with TG and cholesterol metabolism, DGAT decreased slightly but ACAT more decreased as compared with control and Lipidil group. Conclusion : From this study, we can infer that TBE possesses hypolipidemic effect by inhibiting the intestinal absorption and storage of exogenous and endogenous cholesterol. Objectives : This study was aimed to elucidate the effects of TBE on hyperlipidemia. Methods : We studied the effects of TBE on hyperlipidemia through gene expressions related with lipid metabolism, serum triglyceride as well as total and HDL-cholesterol levels, and perceived histological changes. Results : The present studies demonstrate that TBE can reduce the rise in plasma cholesterol, TG levels induced by a high cholesterol diet and also reverse pre-established hypercholesterolemia and hypertriglycemia. In TBE group total cholesterol levels decreased, TG levels decreased, but HDL-cholesterol levels decreased. In the analysis of absolute and relative liver weight, TBE inhibited the weight gain induced by high cholesterol diet. In the histological observations, lipid droplet and apoptotic change in the TBE treated group were less compared with control group. In the serum biochemical analysis, the difference of serum AST and ALT changes among groups was not shown, but TG and total cholesterol levels were less and HDL level decreased compared with control group. In the gene expression related with TG and cholesterol metabolism, DGAT decreased slightly but ACAT more decreased as compared with control and Lipidil group. Conclusion : From this study, we can infer that TBE possesses hypolipidemic effect by inhibiting the intestinal absorption and storage of exogenous and endogenous cholesterol.

Optimization Conditions for Cryopreservation of Deutzia paniculata Nakai, Endangered Plant

Seol, Yuwon,Yong, Seong Hyeon,Choi, Eunji,Jeong, Mi Jin,Suh, Gang Uk,Lee, Cheul Ho,Choi, Myung Suk Institute of Forest Science 2020 Journal of Forest Science Vol.36 No.4

As the importance of biological resources increases, the conservation technology is becoming important for rarities. This study was conducted to establish an efficient cryopreservation conditions for the Deutzia paniculata, endangered plant species, by using both cryopreservation methods of vitrification and encapsulation. As a result, the sucrose pretreatment seed viability showed up to 30.7% in the treatments. The cryoprotectant treatment improved the viability of the seeds, and was found to be excellent in the vitrification method using PVS3. The vitrification method had over 10% higher germination rate than the seeds preserved by encapsulation. In addition, the germination rate showed a significant difference according to the cryopreservation treatment time, and the germination rate of seeds decreased very much as the long time became longer. Plants germinated from preserved seed in liquid nitrogen showed poor growth compared to untreated, and good growth in PVS3 120 minutes. In addition, the growth of germinated plants by liquid nitrogen treatment time was better in the vitrification method. These results are expected to be useful for long-term preservation of D. paniculata, endangered plants.

Effects of TongBiEum(TBE) on Hyperlipidemia Induced by a Sucrose-rich Diet

Yong-Seong Oh,Yoon-Sik Kim,In-Chan Seol 대한한의학회 2003 대한한의학회지 Vol.24 No.4