• Restorative Dentistry and Endodontics
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• v.16 no.1
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• pp.60-73
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• 1991

The purpose of this study is to evaluate the effects of etching time, environmental temperature and humidity on the adhesion of composite resin to glass-ionomer cement. Two chemical cure composite resins (Clearfil F II and Microrest AP) and two glass-ionomer cements (Fuji ionomer Type I and KET AC-CEM) were used as the experimental materials. The experiment is performed in 3 stages: The first stage is to bond composite resins to glass-ionomer cements, and the surface was not etched, and etched for 20 seconds, 40 seconds, and 60 seconds. Then specimens are stored in distilled water at $37^{\circ}C$ for 24 hours to measure tensile strength. The second stage is to choose the one group that had the highest tensile strength from the first stage and prepare two experimental groups: One group with composite resin bonded to glass-ionomer cement without etching and bonding agent application and the other with composite resin bonded to glass-ionomer cement with etching but without any bonding agent application. The specimens are stored in distilled water at $37^{\circ}C$ for 24 hours and tensile strength is measured. The third stage is to choose group that had the highest tensile strength from the first stage experiment, and bond composite resin to glass-ionomer cement at $24^{\circ}C$ 44%, $30^{\circ}C$ 44%, $30^{\circ}C$ 80%, and $32^{\circ}C$ 92%. The storage time of specimens is to bond immediately after storage, then changed to 30 sec., 60 sec., and 120 sec.. Specimens are stored in distilled water at $37^{\circ}C$ for 24 hours and their tensile strength are measured again. The following results were obtained: 1. As the etching time increases, the tensile bond strength between glass-ionomer cement and composite resin increase, and the tensile bond strength is the highest when acid etched for 60 minutes (P < 0.05). 2. After acid etching for 60 minutes, the tensile strength of the group with bonding agent was stronger than that without bonding agent application (P < 0.05). 3. The tensile strength of Clearfil F II was stronger than that of Microrest AP. 4. It was observed that the tensile bond strength is not affected by different storage time with different temperature and humidity. 5. As the humidity was increased, the tensile bond strength between glass-ionomer cement and composite resin decreased (P < 0.05).

• Journal of the Korea Concrete Institute
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• v.27 no.2
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• pp.157-167
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• 2015

Cement composites subjected to high-velocity projectile shows local failure and it can be suppressed by improvement of flexural toughness with reinforcement of fiber. Therefore, researches on impact resistance performance of cement composites are in progress and a number of types of fiber reinforcement are being developed. Since bonding properties of fiber with matrix, specific surface area and numbers of fiber are different by fiber reinforcement type, mechanical properties of fiber reinforced cement composites and improvement of impact resistance performance need to be considered. In this study, improvement of flexural toughness and failure reduction effect by impact of high-velocity projectile have been evaluated according to fiber type by mixing steel fiber, polyamide, nylon and polyethylene which are have different shape and mechanical properties. As results, flexural toughness was improved by redistribution of stress and crack prevention with bridge effect of reinforced fibers, and scabbing by high-velocity impact was suppressed. Since it is possible to decrease scabbing limit thickness from impact energy, thickness can be thinner when it is applied to protection. Scabbing of steel fiber reinforced cement composites was occurred and it was observed that desquamation of partial fragment was suppressed by adhesion between fiber and matrix. Scabbing by high-velocity impact of synthetic fiber reinforced cement composites was decreased by microcrack, impact wave neutralization and energy dispersion with a large number of fibers.

• Journal of the Korea Concrete Institute
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• v.23 no.3
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• pp.339-346
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• 2011

The effects of mineral admixtures on the bonding properties of cement mortar to polyolefin based synthetic fiber were evaluated. The mineral admixtures consisted of 0%, 5%, 10%, and 15% fly ash, blast furnace slag, and metakaolin in cement. Bond interactions between the cement mortar and the polyolefin based synthetic fiber were determined by Dog-bone bond tests. Bond tests of the polyolefin based synthetic fiber showed an increase in pullout load with the strength of the cement mortar. Also, the interface toughness of polyolefin based synthetic fiber in cement mortar increased as the fly ash, blast furnace slag, and metakaolin contents increased. The microstructure of polyolefin based synthetic fiber surface was examined after the pullout test to analyze the frictional resistant force according to the replacement ratio of fly ash, blast furnace slag, and metakaolin during the pullout process of polyolefin based synthetic fiber in cement mortar. The scratched of polyolefin based synthetic fibers increased with the replacement ratio of fly ash, blast furnace slag, and metakaolin. Also, the interface toughness was enhanced by adhesion forces induced by the fly ash, blast furnace slag, and metakaolin.

• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.4
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• pp.379-387
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• 2016

In this study, a survey was conducted on the required measurement and waterproofing performance for residential building underground structure leakage prevention system. According to the results of the survey, it has been determined that leakage problem is considered to be quite severe, and many respondents have agreed. The legal guidelines and regulation systems do not reflect properly on the environmental requirements or conditions, resulting in continued leakage problem. In regards to this, a standardized waterproofing technique that can be used in underground areas of residential structures is required as an obligation and the development of high performance waterproofing method that allows for wet concrete surface adhesion and a guideline, design and maintenance method that allows the control of overall situational control of leakage is required.

• Journal of Periodontal and Implant Science
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• v.32 no.1
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• pp.143-160
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• 2002

타이태늄은 뛰어난 생체적합성과 적절한 물리적 성질을 바탕으로 치과 및 정형외과 영역의 매식재로 널리사용되어져 왔으며, 골과 매식재 사이의 골 융합 정도를 증가시킬 목적으로 물리, 화학적인 방법을 이용한 타이태늄의 표면처리에 관한 많은 연구들이 진행되어 왔다. 최근에는 부착단백질 또는 성장인자를 이용한 생체재료의 표면개질을 통하여 조직적합성 및 치유 능의 개선을 위한 시도들이 있어왔다. Fibronectin(FN)은 주요 세포외기질중의 하나로 생체 내 널리 분포하여 세포의 부착, 이동 및 증식에 관여하는 거대 당단백으로, RGD및 PHSRN 펩타이드 서열이 세포의 인테그린과 결합하여 세포의 활성을 조절하는 것으로 알려져 있다. 이 연구에서는 FN으로 처리된 타이태늄이 조골세포의 부착, 증식 및 분화에 미치는 영향과 이에 따른 석회화 정도에 미치는 영향을 관찰하여 부착분자를 이용한 타이태늄 표면개질의 효과를 규명하고자 하였다. 상업용 순수 타이태늄을 gold thiol법을 이용하여 표면처리 후, 혈장 FN(plasma FN, pFN)과 유전자재조합법을 이용하여 얻은 FN조각(FN type III 7-10, FNIII 7-10)을 피복한 시편을 실험군으로, 아무런 처리를 하지 않은것(smooth surface, SS)과 산 부식(Sandblasted and acid etched, SLA)처리된것을 대조군으로 이용하였다. 배양된 조골세포주(MC3T3-E1)를 사용하여 타이태늄 표면 처리에 따른 세포의 증식, 형태변화, 알칼리성 인산분해효소(ALPase) 생산 및 세포면역형광법을 이용한 분화정도를 시간 경과에 따라 관찰하였다. 조골세포증식의 경우 FNIII 7-10 처리군에서 pFN 처리군 및 대조군에 비해 시간경과에 따라 유의성있는 세포수의 증식이 관찰되었으며(p<0.05), ALPase 생성의 경우에도 FNIII 7-10 처리 군에서 아무 처리도 하지 않은 군에 비해 유의성 있게 높은 효소의 생성이 관찰되었다(p<0.05). 주사전자현미경을 이용한 세포의 형태관찰결과 아무 처리도 하지 않은 군에서는 마름모형태를 나타내었으며, 산 부식 처리된 군에서는 세포가 가시모양의 형태를 보인 반면 FN으로 처리된 두 군에서는 세포의 부착 및 펴짐이 매우 발달되어 있는 모습이 관찰되었다. 세포의 분화정도를 관찰하기 위하여 국소부착키나제(focal adhesion kinase, FAK), 및 actin stress fiber의 분포양상을 세포면역형광법을 이용하여 관찰한 결과 FN으로 표면처리된 두 군에서 아무런 처리도 하지않은 군 및 산 부식처리 한 군에 비해 프라크의 발현이 높게 나타났으며 잘 발달된 actin stress fiber의 소견을 나타내었다. 이 실험의 결과들은 gold thiol 법을 이용한 표면처리 후 FN부착을 통한 타이태늄의 표면개질이 조골세포의 부착, 증식 및 분화에 중요한 역할을 담당하여 석회화 정도를 촉진시키는 것을 보여주었으며, 이런 결과들은 더 짧은 FN조각을 이용한 다른 생체재료의 표면개질에 폭 넓게 응용할 수 있으리라 생각된다.

• Journal of Biomedical Engineering Research
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• v.20 no.1
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• pp.99-106
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• 1999

Ultra-high molecular weight polyethylene (UHMWPE) was crosslinked in the melt state to enhance wear resistance, Dicumyl peroxide (DCP) and triallyl cyanurate (TAC) was used as a crosslinking agent and a promoter, respectively. With increasing amount of DCP and TAC used, gel content of crosslinked UHMWPE (XUMPE) increased, while the melting temperature, crystallizaiton temperature, crystallinity, and tensile properties decreased. The results of pin-on-disk wear test and ball-on-disk test with small applied load showed reduced wear volumes of XUMPE from that of the unmodified UHMWPE. As the wear mechanism effected in the experimental condition of this study was thought to be deformation rather than adhesion or fatigue, a new parameter, the ratio of maximum contact stress to yield stress, was proposed to correlate well with observed wear resistance. In ball-on-disk wear test with larger applied load, XUMPE showed higher wear volumes than that of the unmodified UHMWPE which were accompanied with increased friction coefficients and surface roughness of the wear tracks. When contact stress was well above yield stress, the failure of XUMPE, as well as deformation, was thought to be much accelerated.

• Journal of the Korean Vacuum Society
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• v.9 no.3
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• pp.197-206
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• 2000

The deposition characteristics of MOCVD Cu using the (hfac)Cu(1,1-COD)(1,1,1,5,5,5-hexafluoro-2,4-pentadionato Cu(I) 1,5-cyclooctadine) have been investigated in terms of the effects of carrier gas such as hydrogen and argon as well as the effects of H(hfac) ligand addition. MOCVD Cu using a hydrogen carrier gas led to a higher deposition rate and lower resistivity than an argon carrier gas system. The improvement in the surface roughness of the MOCVD Cu films and the (111) preferred orientation texture was obtained by using a hydrogen carrier gas. However, the adhesion characteristics of the films showed relatively weaker compared to the Ar carrier gas system, probably due to the larger amount of F content in the films, which was confirmed by the AES analyses. When an additional H(hfac) ligand was added, the deposition rate was significantly enhanced in the case of an argon + H(hfac) carrier gas system while significant change in the deposition rate of MOCVD Cu was not observed in the case of the hydrogen carrier gas system. However, the addition of H(hfac) in both carrier gases led to lowering the resistivity of the MOCVD Cu films. In conclusion, this paper suggests the deposition mechanism of MOCVD Cu and is expected to contribute to the enhancement of smooth Cu films with a low resistivity by manipulating the deposition conditions such as the carrier gas and addition of H(hfac) ligand.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.229-229
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• 2010

With the scaling down of ultra large integrated circuits (ULSI) to the sub-50 nm technology node, the need for an ultra-thin, continuous and conformal diffusion barrier and Cu seed layer is increasing. However, diffusion barrier and Cu seed layer formation with a physical vapor deposition (PVD) method has become difficult as the technology node is reduced to 30 nm and beyond. Recent work on self-forming barrier processes using PVD Cu alloys have attracted great attention due to the capability of conformal ultra-thin barrier formation using a simple technique. However, as in the case of the conventional barrier and Cu seed layer, PVD of the Cu alloy seed layer will eventually encounter the difficulty in conformal deposition in narrow line trenches and via holes. Atomic layer deposition (ALD) has been known for its good step coverage and precise thickness control, and is a candidate technique for the formation of a thin conformal barrier layer and Cu seed layer. Conformal Cu-Mn seed layers were deposited by plasma enhanced atomic layer deposition (PEALD) at low temperature ($120^{\circ}C$), and the Mn content in the Cu-Mn alloys were controlled form 0 to approximately 10 atomic percent with various Mn precursor feeding times. Resistivity of the Cu-Mn alloy films decreased by annealing due to out-diffusion of Mn atoms. Out-diffused Mn atoms were segregated to the surface of the film and interface between a Cu-Mn alloy and $SiO_2$, resulting in self-formed $MnO_x$ and $MnSi_xO_y$, respectively. No inter-diffusion was observed between Cu and $SiO_2$ after annealing at $500^{\circ}C$ for 12 h, indicating an excellent diffusion barrier property of the $MnSi_xO_y$. The adhesion between Cu and $SiO_2$ was enhanced by the formation of $MnSi_xO_y$. Continuous and conductive Cu-Mn seed layers were deposited with PEALD into 32 nm $SiO_2$ trench, enabling a low temperature process, and the trench was perfectly filled using electrochemical plating (ECD) under conventional conditions. Thus, it is the resultant self-forming barrier process with PEALD Cu-Mn alloy film as a seed layer for plating Cu that has further potential to meet the requirement of the smaller than 30 nm node.

• Journal of Veterinary Clinics
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• v.24 no.3
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• pp.315-319
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• 2007

Transgastric endoscopic cholecystectomy was successfully accomplished in a 1-year-old, 15 kg, female, mongrel dog. Single-working channel flexible gastric endoscope was used with the aid of one abdominal laparoscopic port. Gastrotomy was performed using endoscopic needle knife at the ventral antral region. Through the gastric incision endoscope was advanced and retroflexed for the visualization of gallbladder. For the better exposure of surgical field, gentle traction was applied at the fundus of the gallbladder using laparoscopic grasping forceps. Cystic duct and artery was ligated using endoclips. After transecting the duct and artery, gallbladder was dissected using endoscopic coagulating grasping forceps and needle knife. Resected gallbladder was retrieved through the mouth and gastric incision site was sutured using endoclips. There was no evidence of bile leakage or stomach leakage on postoperative day (POD) 3. On POD 16, gastric endoscopy and laparoscopy was performed. Gastric endoscopy revealed complete adhesion of incision site. The content of the peritoneum appeared healthy, with no sign of infection, bile staining, or organ injury. The omentum was adhered over resected gallbladder fossa and the serosal surface of gastrotomy site. This is the first report of NOTES cholecystectomy in the dog and provides new concept of cholecystectomy of the dog.

• Korean Journal of Materials Research
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• v.9 no.3
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• pp.288-294
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• 1999

In the flip chip interconnection using solder bump, the Under Bump Metallurgy (UBM) is required to perform multiple functions in its conversion of an aluminum bond pad to a solderable surface. In this study, various UBM systems such as $Al 1\mu\textrm{m} / Ti 0.2\mu\textrm{m} / Cu 5\mu\textrm{m}, Al 1\mu\textrm{m} / Ti 0.2\mu\textrm{m} / Cu 1\mu\textrm{m}, al 1\mu\textrm{m}/Ni 0.2\mu\textrm{m} / Cu 1\mu\textrm{m} and Al 1\mu\textrm{m}/Pd 0.2\mu\textrm{m} / Cu 1\mu\textrm{m}$ for flip chip interconnection using the low melting point eutectic 63Sn-37Pb solder were investigated and compared to their metallurgical properties. $100\mu\textrm{m}$ size bumps were prepared for using an electroplating process. The effects of the number of reflows and aging time on the growth of intermetallic compounds(IMC) were investigated. $Cu_6Sn_5$ and $Cu_3Sn$ IMC were abserved after aging treatment in the UBM system with thick coper $(Al 1\mu\textrm{m}/Ti 0.2\mu\textrm{m}/Cu 5\mu\textrm{m})$. However only the $Cu_6Sn_5$ was detected in the UBM system with $1\mu\textrm{m}$ thick copper even after 2 reflow and 7 day aging at $150^{\circ}C$. Complete Cu consumption by Cu-Sn IMC growth gives rise to a direct contact between solder inner layer such as Ti, Ni and Pd, and hence to possibly cause reactions between two of them. In this study, however, only for the Pd case, IMC of PdSn. was observed by Cu consumption. UBM interfacial reactions with s이der affected the adhesion strength ot s이der balls after s이der reflow and annealing treatment.