• 전기화학회지
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• 제3권2호
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• pp.85-89
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• 2000

Lithium ion Battery(LIB)의 음극 활물질로써 리튬을 대체하기 위한 노력으로 phenol resin을 탄화시킨 탄소재료를 사용하였다. Phenol resin을 소성하면 축합반응을 일으키면서 탄화되어 무정형 탄소가 된다. 무정형 탄소는 층간거리가 넓어 리튬의 삽입과 탈리가 용이하지만 탄소간의 결합력이 약하여 구조적 붕괴가 일어난다. 이러한 문제를 해결하기 위해 세공형성제로서 $ZnCl_2$를 사용하였다. $ZnCl_2$는 생성된 물질에서 3차원적 망상구조로 성장하는 개방세공을 형성하는 세공형성제로서 뿐만 아니라, 벌크 첨가제가 도핑된 느슨한 구조를 형성하는 미세세공 형성제로서 작용하였다. SEM을 통해서 구조적 차이를 알 수 있었으며, XRD분석으로 층간의 거리를 알 수 있었다. CV측정을 통해 두 가지 샘플에 대한 산화와 환원 반응의 차이를 알아보았다.

• 대한약침학회지
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• 제16권2호
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• pp.46-54
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• 2013

Objective: This study was undertaken to isolate a fibrin(ogen)olytic enzyme from the snake venom of Gloydius blomhoffii siniticus and to investigate the enzymatic characteristics and hemorrhagic activity of the isolated enzyme as a potential pharmacopuncture agent. Methods: The fibrinolytic enzyme was isolated by using chromatography, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and fibrin plate assay. The characteristics of the enzyme were determined by using fibrin plate assay, protein hydrolysis analysis, and hemorrhage assay. Its amino acid composition was determined. Results: The fibrin(ogen)olytic enzyme with the molecular weight of 27 kDa (FE-27kDa) isolated from G. b. siniticus venom consisted of two heterogenous disulfide bond-linked polypeptides with the molecular weights of 15 kDa and 18 kDa. When more than $20{\mu}g$ of FE-27kDa was applied on the fibrin plate, fibrinolysis zone was formed as indicating its fibrinolytic activity. The fibrinolytic activity was inhibited completely by phenylmethanesulfonylfluoride (PMSF) and ethylenediaminetetraacetic acid (EDTA) and partially by thiothreitol and cysteine. Metal ions such as $Hg^{2+}$ and $Fe^{2+}$ inhibited the fibrinolytic activity completely, but $Mn^{2+}$ did not. FE-27kDa preferentially hydrolyzed ${\alpha}$-chain of fibrinogen and slowly hydrolyzed ${\beta}$-chain, but did not hydrolyze ${\gamma}$-chain. High-molecular-weight polypeptides of gelatin were hydrolyzed partially into polypeptides with molecular weights of more than 45 kDa. A dosage of more than $10{\mu}g$ of FE-27kDa per mouse was required to induce hemorrhage beneath the skin. Conclusion: FE-27kDa was a serine proteinase consisting of two heterogeneous polypeptides, hydrolyzed fibrin, fibrinogen, and gelatin, and caused hemorrhage beneath the skin of mouse. This study suggests that the potential of FE-27kDa as pharmacopuncture agent should be limited due to low fibrinolytic activity and a possible side effect of hemorrhage.

• Journal of Welding and Joining
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• 제34권1호
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• pp.21-25
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• 2016

The automotive vehicle is made through the following processes such as press shop, welding shop, paint shop, and general assembly. Among them, the most important process to determine the quality of the car body is the welding process. Generally, more than 400 pressed panels are welded to make BIW (Body In White) by using the RSW (Resistance Spot Welding) and GMAW (Gas Metal Arc Welding). Recently, as the needs of light-weight material due to the $CO_2$ emission issue and fuel efficiency, new joining technologies for aluminum, CFRP (Carbon Fiber Reinforced Plastic) and etc. are needed. Aluminum parts are assembled by the spot welding, clinching, and SPR (Self Piercing Rivet) and friction stir welding process. Structural adhesive boning is another main joining method for light-weight materials. For example, one piece aluminum shock absorber housing part is made by die casting process and is assembled with conventional steel part by SPR and adhesive bond. Another way to reduce the amount of the car body weight is to use AHSS (Advanced High Strength Steel) panel including hot stamping boron alloyed steel. As the new materials are introduced to car body joining, productivity and quality have become more critical. Productivity improvement technology and adaptive welding control are essential technology for the future manufacturing environment.

• 한국진공학회지
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• 제18권6호
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• pp.453-458
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• 2009

SiOC 박막을 BTMSM과 산소의 혼합가스를 사용하여 CVD 방법으로 증착하였다. 박막의 특성은 가스 유량비에 따라서 변하였다. 유전상수는 MIS 구조를 이용하여 C-V 측정법에 의하여 얻었다. 결합의 말단을 구성하는 Si-$CH_3$ 결합 사이의 공간효과에 의해서 기공이 만들어지며, 기공의 형성에 의해서 박막의 두께가 증가하였다. 그러나 분극의 감소에 의해서 만들어지는 SiOC 박막은 두께가 감소하면서 유전상수도 감소되었다. 열처리 후 유전상수는 수산기의 기화에 의해서 감소되었다. 박막의 두께는 분극의 감소에 의한 유전상수의 감소와 연관이 있었다. 굴절률은 박막의 두께에 반비례하는 경향성이 있으며, 박막의 두께와 굴절률의 경향성은 열처리 후에도 변하지 않았다.

• 대한치과기공학회지
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• 제31권3호
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• pp.21-26
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• 2009

Purpose: Standards of alloy for porcelain fused to metal crown be classified by metallic factor and biological factor. Metallic factors consist of stability of alloy composition and mechanical strength and surface characteristics for chemical bond. Biological factors be considered properties of metallic elements and problems originated by toxicity and hypersensitive reaction. Alloys considered such controversial points are the most suitable alloy for dental instrument. Method: Alloys added Be and Nb using Ni-Cr alloy which has been widely used for dental instrument be selected and classified experimental group. Non-addition Be and Nb to Ni-Cr alloy classify control group and addition Be alloy is Be-experimental group, addition Nb alloy is Nb-experimental group. Specimens for cytotoxicity analysis gave effect to washing and sterilization. and then made an experiment on elution with cell medium after disinfection. It conducted specimens within cell medium with 24hours, 48hours, 72hours, respectively. It cultured human dermal fibroblast(HDF) using cell medium for cytotoxicity test and then investigated elution rate through spectroscopic analysis by MTT-assay. Result: As results of cytotoxicity test by MTT-assay, cultured cell rate of VII measured more low numerical value within elution medium for 24hours focused on control group. Also, cultured cell rate of K3 alloys observed low value for 48hours, 72hours than value of control group. Conclusion: According to final result that synthesize above results, Ni-Cr alloy added Be and Ni has little difference in Cytotoxicity by MTT-assay.

• 대한기계학회논문집
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• 제7권3호
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• pp.263-269
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• 1983

Underwater welding by a gravity arc welding process was investigated by using six types of coated electrodes and SM41A steel plates of 10 mm thickness as base metal and it was ascertained that this process may be put to practical use. Main results obtained are summarized as follows: 1. Angle of electrode affects no influence on bead appearance and the proper range of welding current and diameter of electrode for the high titanium oxide type is relatively wider than that for the ilmenite type. And the lime titania type, high titanium oxide type and ilmenite type of domestic coated arc welding electrodes of .phi.4 mm could attain the soundest underwater welded joints which contain no welding imperfection. 2. According to macro-structure, micro-structure and hardness distribution inspectionson underwater welded joint, the area between the HAZ and the surface of the weld in neighbourhood of the bond has the maximum hardness value. The structure of these parts is martensite and bainite. Other parts contain mocro-ferrite, micro-pearlite structure, which contain soundness of welded joint free from weld imperfection. 3. On consideration of both tensile strength of more than 100% joint efficiency and sufficient impact value, the welding condition which can get optimal welding strength is heat input of 1,400-1,500 J/mm, current of 200-215 ampere (voltage of 32-33 volts) in the case of lime titania type electrode. 4. Underwater welding strength (tensile strength, impact strength) depends on heat input (or current) quantitatively and they have the relationship of parabolic function. Each experimental equation has a high reliability and its percent of mean error is 4.14%. 5. It is suggested that the optimal design of weld strength by welding condition (current, heat input) could be utilized for a quality control of underwater welding.

• 대한화학회지
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• 제17권3호
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• pp.154-162
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• 1973

치환된 염화벤젠술포닐 $XC_6H_4SO_2Cl$(X:p-MeO, H, p-Cl, p-Br, p-NO_2)의 할라이드 교환 반응을 무수 아세톤 중에서 행하여 반응속도 상수와 활성화 계수를 구하였다. 금속 할라이드의 이온쌍 $M^{+}X^{-}$의 반응성은 할라이드 이온에 비하여 무시할 수 있음을 보았다. EH 친핵성도가 전자를 밀어내는 치환기를 가진 경우에 $Cl>Br^{-}>I^{-}$이고, 전자를 끌어주는 치환기를 가진 경우에는 $Cl>I^{-}>Br^{-}$이었다. 이들 결과와 Hammett그림표가 위로 볼록한 것을 결합 약화 과정이 크게 기여하는 단순 $S_N2$메커니즘으로 설명하였다.

• 열처리공학회지
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• 제19권4호
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• pp.200-207
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• 2006

In addition to the basic properties of the base and top coating agents, corrosion resistance of non-chrome magni 565 coating and characteristics of coating film when coated to steel substrate were studied. The system had a good wettability at room temperature. Moreover, both the contact angle and surface tension were affected little by the viscosity of coating agent and surface roughness of the steel substrate. And the samples coated with optimal conditions showed a great corrosion resistance in salt spray test with 1500 hours or longer of initial appearance time of rust. The coating film was composed of overlapping layer of zinc and aluminium flakes, and the thickness of base coat increased with an increase of base coat viscosity. Based on the C-F peaks of 1,1-Difluoroethaen homo-polymer, it was thought that the base coat was an inorganic polymer bond layer. Meanwhile, the top coat showed C-F peaks of polytetrafluoroethylene with C-H peaks of phenol in FT-IR analysis. From the lower weight loss of base coat in TG analysis, it was thought that cross linking density of base coat was larger than that of top coat. It was thought that the small exothermic reactions observed in DSC curves were due to the thermosetting resins contained in the coating agents. Compared to the non-coated specimen, the coated sample showed more higher polarization resistance and corrosion potential with lower corrosion current density.

• 조명전기설비학회논문지
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• 제16권4호
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• pp.8-14
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• 2002

현대의 뇌보호시스템은 낙뢰로 인한 감전이나 건축물, 전기·전자기기의 파손과 같은 위험성을 제거하는 것이 요구되지만 종래의 뇌보호설비는 단지 인명의 피해나 건축물을 보호하는 것이 주된 역할이었다. 오늘날 컴퓨터, 정보통신설비 등을 효과적으로 보호할 수 있는 뇌보호설비가 필수적 요건으로 대두되었다. 본 논문에서는 뇌과전압으로부터 컴퓨터와 전자장비를 보호할 수 있는 기술을 개발할 목적으로 인하도선의 종류와 설치기법에 따라서 인하도선에 유도되는 전위상승 억제에 대한 연구를 수행하였다. 그 결과 인하도선의 전위상승에 의한 측면방전과 위험성을 줄이기 위해서는 인하도선으로 낮은 특성임피던스를 가지는 동축케이블이 적당하며, 인하도선과 금속관을 상단과 하단에서 본딩하는 방법이 효과가 높게 나타났다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.193.1-193.1
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• 2014

This study was to investigate the electronic structure and optical properties of Na doped into NiO thin film using XPS and REELS. The films were grown by electron beam evaporation with varying the annealing temperature. The relationship between the electrical characteristics with the local structure of NiO thin films was also discussed. The x-ray photoelectron results showed that the Ni 2p spectra for all films consist of Ni 2p3/2 which indicate the presence of Ni-O bond from NiO phase and for the annealed film at temperature above $200^{\circ}C$ shows the coexist Ni oxide and Ni metal phase. The reflection electron energy loss spectroscopy spectra showed that the band gaps of the NiO thin films were slightly decreased with Na-doped into films. The Na-doped NiO showed relatively low resistivity compared to the undoped NiO thin films. In addition, the Na-doped NiO thin films deposited at room temperature showed the best properties, such as a p-type semiconducting with low electrical resistivity of $11.57{\Omega}.cm$ and high optical transmittance of ~80% in the visible light region. These results indicate that the Na doping followed by annealing process plays a crucial in enhancing the electrical and optical properties of NiO thin films. We believe that our results can be a good guide for those growing NiO thin films with the purpose of device applications, which require deposited at room temperature.