Effect of Ar Plasma Treatment for Surface of Insert Metal on Property of TLP Bonding Joint for Power Module

Baek Seungju,Yu Dong-Yurl,Son Jun-Hyuk,Bang Junghwan,Kim Jungsoo,Kim Min-Su,Lee Han-Bo-Ram,고용호 대한용접접합학회 2020 대한용접·접합학회지 Vol.38 No.4

In this study, we investigated the effect of plasma treatment for the surface of an insert bonding metal on the prop�erties of a transient liquid phase (TLP) bonding joint for a power module. Sn preforms, as the insert bonding metal for the TLP bonding, were used with and without Ar plasma treatment. To investigate the effect of Ar plasma treat�ment, the TLP bonding for two structures of Cu-finished Si chip/Sn preform/organic solderability preservative (OSP)-finished direct bond copper (DBC) substrate (Cu/Sn/Cu), and Ni-finished Si chip/Sn preform/Ni(P)-finished DBC substrate (Ni/Sn/Ni) was performed with 1 MPa at 300 ℃ and the bonding times were 10, 30, and 60 min, respectively. After the TLP bonding, we observed interfacial reactions and formations of intermetallic compounds (IMCs) under various bonding conditions. To evaluate mechanical properties, a shear test was also performed. Compared to the TLP bonding joint that used bare Sn preforms without Ar plasma treatment, growth of IMCs at the bonding joint that used Sn preforms with Ar plasma treatment occurred faster, and the IMCs could be formed through the entire joint despite the bonding time of 10 min. Meanwhile, by increasing the bonding time, Cu6Sn5 and Cu3Sn were formed at the Cu/Sn/Cu TLP bonding joint, whereas Ni3Sn4, Ni-Sn-P, and Ni3P were observed at the Ni/Sn/Ni joint. In the case of the Cu/Sn/Cu joint, we observed that increasing Cu3Sn formation while increasing the bonding time could be beneficial to the shear strength of the joint. Further, shear strengths of the joint were not sig�nificantly changed under the bonding conditions after Ni3Sn4, Ni-Sn-P, and Ni3P IMCs were formed at the entire joint of the Ni/Sn/Ni.

SiO₂ nanodot arrays using functionalized block copolymer templates and selective silylation

Kim, Su Min,Ku, Se Jin,Kim, Jin-Baek IOP Pub 2010 Nanotechnology Vol.21 No.23

<P>Silicon oxide nanodot arrays were fabricated using functionalized block copolymer templates and selective silylation. A polystyrene-<I>b</I>-poly(acrylic acid/acrylic anhydride) (PS-<I>b</I>-PAA/AN) thin film containing spherical nanodomains was used as a template to build nanoscopic silica structures. A PS-<I>b</I>-PAA/AN thin film was prepared by acid-catalyzed thermal deprotection of polystyrene-<I>b</I>-poly(<I>tert</I>-butyl acrylate) on an SU-8 resist film containing a photoacid generator. This resulting film has excellent solvent and thermal resistance due to crosslinked anhydride linkages in carboxyl-functionalized PAA/AN block domains. Silicon was introduced by spin-spraying of hexamethyldisilazane (HMDS) over the entire surface of a self-assembled PS-<I>b</I>-PAA/AN thin film. HMDS was selectively reacted with carboxylic acid groups in spherical domains of a PAA/AN block. SiO<SUB>2</SUB> nanodot arrays were generated by oxygen reactive ion etching. </P>

광중합형 수복용 복합레진의 인장강도에 미치는 thermal cycling과 시효 처리의 영향

백상현,채민수,이주형,김태조,배태성 대한치과기재학회 1998 대한치과재료학회지 Vol.25 No.1

The improvement in the mechanical properties of restorative composites has contributed to their increased use in recent years. In spite of their growing popularity, composites still have low resistance to fracture and wear in oral environments. This study was performed to examine whether the tensile strengths of light-cured restorative composites were affected by thermal cycling and aging in water. Five commerically available light-activated composites(Heliomolar : HM, Aelitefil : AF, Amelogen : AG, Clearfil AP-X : CF, Z100 : ZH) were used. Rectangular tension test specimens were fabricated in a teflon mold giving 5 mm in gauge length and 2mm in thickness. All samples were divided into 3 groups. Group 1 was stored in a desiccator for 10 days. Group 2 was immersed in a 37℃ distilled water for 10 days. Group 3 was subjected to 10,000 thermal cycles between 5℃ and 55℃, and the immersion time in each bath was 15 seconds per cycle. Tensile testing was carried out at a crosshead speed of 0.5 mm/min and fracture surfaces were observed with scanning electron microscope. The results obtained were summarized as follows; 1. The strength data fit to single-mode Weibull distribution(r²> 0.86) and Weibull parameters decreased after thermal cycling test. 2. The highest characteristics strength was observed in the CF group but the highest Weibull modulus was obtained in the AF group after thermal cycling test. 3. The highest tensile strength value of 83.92 MPa was obtained in the CF group and the lowest value of 13.91 MPa was obtained in the AG group. Tensile strengths showed no significant difference between HM and AG groups but other groups showed the significant differences in each group(p<0.05). 4. According to the microscopic observation of the fracture surfaces, fractures of large fillers were observed in the hybrid composites of the AF and CF groups.

광중합형 수복용 복합레진의 강도에 미치는 Thermal Cycling의 영향

백상현,채민수,배태성 대한치과기재학회 1996 대한치과재료학회지 Vol.23 No.1

This study was performed to investigate the effects of thermal cycling on the strength of light cured restorative composite resins. Five commerically available light-activated composite resins(Photo Clearfil A : CA. Lite-Fil A : LF, Clearfil Photo Posterior : CP, Prisma AP.H. : PA, Z100 : ZH) were used. The specimens of 12mm in diameter and 0.7mm in thickness were made, and a thermal cycling test of 1000 cycles at 15 seconds dwell time each in 5℃ and 55℃ baths was performed. In order to investigate the deterioration of composite resins in the thermal cycling test, the bi-axial flexure strengths were measured, and the surface after thermal cycling test were examined by SEM. The results obtained were summarized as follows; 1. Biaxial flexure strength significantly decreased due to the thermal cycling(P<0.01). 2. Biaxial flexure strengths showed the maximum value of 125.65MPa for ZH group and the minimum value of 64.86MPa for ZA group, after thermal cycling test, Biaxial fleure strengths of ZH and CP group were higher then those of PA, CF, and CA groups after thermal cycling test(p<0.05). 3. Fracture surfaces showed that the composite resin failure developed along the matrix and the filler/resin interface region, and the cracks propagated in the conical shape from the maximum tensile stress zone.

대학생 흡연자의 금연경험에 따른 건강신념차이

구정일,김민정,김동희,백정희,안현실,은가희,우혜령,이명희,이수현,김수지 이화여자대학교 간호과학대학 2003 이화간호학회지 Vol.- No.37

It has been generally known that smoking is one of the worst factor increasing disease and mortality in human health since in 1950's and nowadays. But regardless of various proofs about social or economical problems due to smoking, current smoking rate has not been decreased in our country. Until now, most of tobacco use and its addiction researches have been focused on the adolescent or adult women smokers not on the university students. Therefore, the purpose of this study was to investigate smoking cessation of university smokers and analyze the health belief-perceived sensitivity, severity, benefits and barriers- difference, then to provide basic data for effective smoking cessation strategy for university smokers. The subjects were comprised of 181 university smokers from 15 universities in Seoul. The data were collected by structured questionaires. The questionaires were designed to measure general characteristics, smoking cessation and health belief, based on Ahn(2003)'s result on the Study of Smoking attitude, Behavior and Smoking Cessation of Adult Male and Lee(1987)'s result on Relationships Between the Health Belief Model and Smoking Habits. The data were collected from May 5 to 16. The collected data were analyzed by SPSS program. The actual number, percentiles, means, standard deviation, t-test and ANOVA were done. The result of this study were as follows; 1. The general characteristics of the subjects of this study The range of age was from 18 to 34 and the averaging age was 23. The subjects of this study were 141 males and 40 females. The religions were Christianity 25.4%(46), Buddhism 12.7%(23), Catholic 23.2%(42), no religion 37.0%(67). The residential forms were living with family 59.1%(107), cooking food for oneself 28.7%(52), dormitory 5.0%(9), boarding house 1.7%(3). Smoking starting age were university 43.1 %(78), high school 29.8%(54), middle school 14.9%(27), in the army 6.1 %(11), elementary school 1.1 %(2). 2. The smoking cessation of the subjects 80% of current smokers showed quitting smoking decision and 20% have not tried. The frequency of quitting smoking decision were from 1 to above 8 and mean was 3.06. As for smoking cessation plan, 54.7%(99) current smokers answered yes, 3.9%(7) said no, 35.4%(64) had no idea and 6.1 %(11) didn't answer. As for the reason of never quitting smoking decision, 71.42%(25 among total 35) have no need to quit smoking and the others said difficulty of smoking cessation. As for the main reason of smoking cessation decision, 54.7%(99) answered for the health, 7.2%(13) family advice, 15.5%(28) girl/boy friend's advice, 1.7%(3) to save money. As for the reason to fail smoking cessation, 56.7%(68) were will-lack, 17.5%(21) stress, 15%(18) smoking mood, 10%(12) withdrawl symptom. As for the smoking cessation method, 85.0%(125) were oneself-will, 2.7%(4) way acquired by mass-media, 2%(3) doctor's prescription, 2%(3) religion's help, 0.7%(1) smoking cessation school. As for the difficulty in smoking cessation, 42.2%(62) were drinking meeting, 23.1 %(34) no alternative of stress release, 12.2%(18) withdrawl symptom, 11.6%(17) having nothing to do, 7.5%(11) friend's encouragement. As for the most difficult cigarette to quit, 67.8%(99) were all-day smoking except the first smoking in the morning, 32.2%(47) the first smoking in the morning. 3. Health belief as for general characteristics Gender - The total point in benefits showed higher in male(28.5177) than female(26.6750). There was significant difference(t=.778, p<.05). The total point in health belief showed higher in male (105.8298) than female(l00.5000). So there was significant difference(t=.345, p<.05). Age - There was significant difference in benefits between age(10's-25.83, 20's-28.39, 30's-32.00)(F=3.73, p<.05). Smoking starting age - There was significant difference in total point of sensitivity and health belief(sensitivity F=4.00, p<.Ol, health belief F=2.843, p<.05). As for sensitivity, subjects who started smoking in the army showed the highest(33.36) and ones in high school showed the lowest(26.96). The total point in health belief showed the highest in elementary school(l19.00) and the lowest in high school(100.98). 4. Health belief as for smoking cessation There was significant difference in health belief as for smoking cessation(t=0.189, p=0.OO2). Sensitivity point showed higher in smoking quitting trial smokers(29.2) than non-trial smoker (26.9). Severity point showed higher in trial smokers (30.7) than non-trial smokers(28.9). Benefit point showed higher in trial smokers(28.6) than non-trial smokers(26.2). There was no significant difference in barriers point.

순무(Brassica campestris ssp. rapa) 뿌리로부터 지질화합물의 분리 및 동정

방면호,오영준,유종수,한민우,정해곤,정태숙,최명숙,이경태,김세영,백남인 경희대학교식량자원개발연구소 2007 硏究論文集 Vol.26 No.1

순무 뿌리로부터 활성 물질을 분리 동정 하기 위하여 80% MeOH 수용액으로 추출하고 이를 여과, 감압 농축하여 MeOH추출물을 얻었다. 이를 EtOAc분획, n-BuOH분획, H_(2)O분획으로 나누었으며, EtOAc분획에 대해 silica gel column chromatography를 실시하여 3종의 지질화합물을 분리 정제하였다. ^(1)H-NMR, ^(13)C-NMR, DEPT spectrum 및 Mass spectrum등을 통하여 palmitic acid methyl ester(compound 1), linolenic acid methyl ester(compound 2), linoleic acid methyl ester(compound 3)으로 구조를 결정하였다. In order to isolate and identify the active compound from the Brassica campestris ssp rapa, the roots and the root skin were extracted with 80% aqueous MeOH, and the concentrated extract was partitioned with EtOAc, n-BuOH and H_(2)O. From the EtOAc fraction, three compounds were isolated through the repeated silica gel column chromatographies. From the result of spectral data including NMR and MS, the chemical structures of the compound were determined as palmitic acid methyl ester (compound 1), linolenic acid methyl ester (compound 2), linoleic acid methyl ester (compound 3).

ART2를 이용한 세라믹 영상에서의 다양한 결함 검출

김주혁(Ju-Hyeok Kim),한민수(Min-Su Han),우영운(Young-Woon Woo),김광백(Kwang-Baek Kim) 한국컴퓨터정보학회 2013 한국컴퓨터정보학회 학술발표논문집 Vol.21 No.2

본 논문에서는 비파괴 검사를 통하여 얻은 세라믹 영상에 퍼지 기법과 ART2 기법을 적용하여 결함을 검출하는 방법을 제안한다. 제안된 방법은 세라믹 소재로 얻어진 영상에서 결함의 구간을 설정하기 위해 퍼지 스트레칭 기법을 적용하여 명암도를 대비시킨다. 명암 대비가 강조된 영상에서 퍼지 이진화 기법을 적용한 후, 상/하 경계선에 가장 많이 분포된 곳을 Max, Min으로 설정하고, Max+20, Min-20을 결함 구간으로 설정한다. 설정한 결함 구간 내의 비파괴 세라믹 영상에서 ART2 알고리즘 기법을 적용하여 세라믹 영상의 결함을 검출한다. 본 논문에서 제안된 방법을 비파괴 세라믹 영상을 대상으로 실험한 결과, 제안된 방법이 기존의 세라믹 결함 검출 방법보다 비파괴 세라믹 영상에서 다양한 형태의 결함이 검출되는 것을 확인하였다.

The effects of low level light therapy on inflammatory mediators in human annulus fibrosus during the intervertebral disc degeneration

Min Ho Hwang(황민호),Jae Hee Shin(신재희),Hyo Geun Nam(남효근),Hyeong Guk Son(손형국),Seung Min Baek(백승민),Chang Min Yoo(유창민),Jeong Hun Park(박정훈),Jin su Jeong(정진수),Jae won Lee(이재원),Hyuk Choi( 최혁) 대한전자공학회 2016 대한전자공학회 학술대회 Vol.2016 No.6

Intervertebral disc degeneration (IVD) is one of the important causes of low back pain and is associated with inflammation induced by interaction between macrophages and the human annulus fibrosus (AF) cells. Low level light therapy (LLLT) has been widely known to regulate inflammatory reaction. However, the effect of LLLT on macrophage-mediated inflammation in the AF cells has not been studied till date. The aim of this study is to mimic the inflammatory microenvironment and to investigate the anti-inflammatory effect of LLLT at a range of wavelengths (405, 532 and 650 nm) on the AF treated with macrophage-like THP-1 cells conditioned medium (MCM) containing proinflammatory cytokines and chemokines (interleukin-1beta, tumor necrosis factor-alpha, interleukin-6 and 8). We observed that AF cells exposed to MCM secrete significantly higher concentrations of IL-6, IL-8, IL-1b and TNF-a. LLLT markedly inhibited secretion of IL-6 at 405 nm in a time-dependent manner. Level of IL-8 was significantly decreased at all wavelengths in a time-dependent manner. We showed that MCM can induce the inflammatory microenvironment in AF cells and LLLT selectively suppressed IL-6 and 8 levels. The results indicate that LLLT is a potential method of IVD treatment and provide insights into further investigation of its antiinflammation effect on IVD.

COI-Based Genetic Structure of an Exotic Snapping Turtle Chelydra serpentina Imported to South Korea

Su Youn Baek,ChoRong Shin,Kyung Min Kim,Eun-Hwa Choi,Jihye Hwang,Jumin Jun,Taeseo Park,Hyun Jong Kil,Ho Young Suk,Mi-Sook Min,Yoonseong Park,YoungSup Lee,Ui Wook Hwang 한국동물분류학회 2020 Animal Systematics, Evolution and Diversity Vol.36 No.4

A common snapping turtle Chelydra serpentina inhabiting North America is internationally protected as an endangered species. It is known that the individuals of common snapping turtles were imported to South Korea as pets, and after being abandoned, some inhabit the natural ecosystem of South Korea like wild animals. No genetic survey has yet been performed for the common snapping turtles imported to South Korea. Hereby, cytochrome c oxidase subunit I (COI) information, which is 594 bp long, was determined for a total of 16 C. serpentina individuals, of which one was found in nature, twelve legally imported and their descendants, and the other three were provided from the Kansas Herpetological Society, USA. The obtained data were combined with thirteen COI sequences of C. serpentina retrieved from NCBI GenBank for the subsequent population genetic analyses. The results showed that there exist five haplotypes with high sequence similarity (only three parsimoniously informative sites). In the TCS and phylogenetic analyses, all the examined C. serpentina samples coincidently formed a strong monoclade with those collected mostly from Kansas State, USA, indicating that the imported ones to South Korea are from the central North America. In addition, there found the amino acid changes and the high degree of nucleotide sequence differences between C. serpentina and C. rossignoni with some important morphological characters. It is expected that the present results could provide an important framework for systematic management and control of exotic snapping turtles imported and released to nature of South Korea.

Preharvest Methyl Jasmonate and Salicylic Acid Treatments Improve the Nutritional Qualities and Postharvest Storability of Tomato

Min Woo Baek,Shimels Tilahun,Han Ryul Choi,Jong Whan Lee,Su Ho Tae,Se Min Chang,Cheon Soon Jeong 한국원예학회 2023 한국원예학회 학술발표요지 Vol.2023 No.5