• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
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• pp.534-538
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• 2002

Dissimilar friction stir welding of aluminum (AI) alloy 1050 and magnesium (Mg) alloy AZ31 was successfully done in the limited welding parameters. The dissimilar weld showed good quality and facility compared to conventional fusion weld. Transverse cross section perpendicular to the welding direction had no defects. The weld was divided into base material of Al alloy, an irregular shaped stir zone and base material of Mg alloy. The irregular shaped stir zone was roughly located around the initial weld center. The weld interface near plate surface shifted from initial weld centerline to the advancing side. Hardness profile of the weld was heterogeneous, and the hardness value of the stir zone was raised to about 150 Hv to 250 Hv. The mixed phase was identified to intermetallic compound $Mg_{17}$Al$_{12}$ using x-ray diffraction method, energy dispersive x-ray spectroscopy (EDX) and electron probe micro analysis (EPMA). The formation of intermetallic compound $Mg_{17}$Al$_{12}$ during FSW causes the remarkable increase in hardness value in the stir zone.one.

• 대한치과기공학회지
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• 제31권4호
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• pp.15-23
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• 2009

The aim of this study was to evaluate the bond strength of using a Au bonding agent applied on cp-Ti and nonprecious metal-gold-ceramic system. Metallic frameworks(diameter: 5mm, height: 20mm)(N=56, n=7per group) cast in Ni-Cr alloy, Co-Cr alloy and cp-Ti were obtained using acrylic templates and airborne particle abraded with $110{\mu}m$ aluminum oxide. Au bonding agent was applied on wash opaque firing as intermediate layer. SEM and SEM/EDS line profile were performed on the cutting the cross-section of the metal substrate-porcelain with intermediate Au coating. Groups were tested using shear bond strength(SBS) testing at 0.5mm/min. The mean SBS values for the ceramic-Au layer-metal combination were significantly higher than those ceramic-metal combination. While ceramic-Au layer-cp-Ti combinations failed to increase bond strength instead of using a titanium bonding porcelain. The appication of using Au intermediate layer significantly improve the bond strength combination with metal-ceramic system.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집 Vol.14 No.1
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• pp.209-212
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• 2001

Polyimide(PI) films have been considered as the interlayer dielectric materials due to low dielectric constant, low water absorption, high gap-fill and planarization capability. The PI mm Was etched with using inductively coupled plasma (ICP). The etching characteristics such as etch rate and selectivity were evaluated to gas mixing ratio. High etch rate was $8300{\AA}/min$ and vertical profile was approximately acquired $90^{\circ}$ at $CF_{4}/(CF_{4}+O_{2})$ of 0.2. The selectivies of polyimide to PR and $SiO_{2}$ were 1.2, 5.9, respectively. The etching profiles of PI films with an aluminum pattern were measured by a scanning electron microscope (SEM). The chemical states on the PI film surface were investigated by x-ray photoelectron spectroscopy (XPS). Radical densities of oxygen and fluorine in different gas mixing ratio of $O_{2}/CF_{4}$ were investigated by optical emission spectrometer (OES).

• 한국재료학회지
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• 제14권6호
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• pp.436-442
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• 2004

Elastic and plastic deformation behaviors of the high purity aluminum and the silica glass were studied using nanoindentation and finite element analysis(FEA) techniques. Berkovich- and cone-type indenters were used for the nanoindentation test. Deformation behaviors and nanoindent profiles of elastic, elastic-plastic or plastic materials were clearly visualized by FEA simulation. Effects of the penetration depth and strain hardening on the deformation behavior were examined. Pile-up and sink-in behaviors were studied by using FEA technique. Degree of pile-up or sink-in was found to be a function of the ratio of elastic modulus to yield strength of materials. FEA was found to be an effective method to study deformation behaviors of materials under nanoindentation, especially in the case when pile-up or sink-in phenomena occurred.

• 대한기계학회논문집A
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• 제33권7호
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• pp.693-699
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• 2009

This paper shows mechanical properties and behaviors of macro- and micro-structures on friction stir welded specimen with 6061-T6 aluminum alloy plate. It apparently results in defect-free weld zone jointed at welding conditions like the traverse speed of 267mm/min, tool rotation speed of 2500rpm, pin inserted depth of 4.5mm and tilting angle of $2^{\circ}$ with tool dimensions such as tool pin diameter of 5mm, shoulder diameter of 15mm and pin length of 4.5mm. The tensile stress ${\sigma}_T=228MPa$ and the yield point ${\sigma}Y=141MPa$ are obtained at the condition of traverse speed of 267mm/min and tool rotation speed of 2500rpm. With the constant rotation speed, the higher traverse speed become, the higher tensile stress and yielding point become. Vickers hardness for welding zone profile were also presented.

• Biomolecules & Therapeutics
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• 제2권4호
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• pp.347-360
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• 1994

The general and some pharmacological actions of DWP 301 were investigated in animals and the following results were obtained. In central nervous system, DWP 301 had no effects on the pentobarbital induced anaesthesia, rotarod test, traction test, analgesic action, anticonvulsant action in mice and body temperature in rat. But DWP 301 showed a little decrease of locomotor activity at a dose of 3,000 mg/kg. From these results, DWP 301 was considered to have little pharmacological effect on the central nervous system. Furthermore, DWP 301 had no influences on the normal blood pressure and heart rate. DWP 301 showed no effect on the isolated guinea pig ileum, trachea, right atrium, and nonpregnant rat uterus. But, in the isolated guinea pig vas deference, DWP 301 had showed inhibitory effect on the contractions produced by norepinephrine. DWP 301 showed rise of gastric juice pH and decrease of urine volume. Also, DWP 301 had no effect on the gastrointestinal motility and blood aggregation. From these results, it is concluded that the general pharmacological effect of DWP 301 are similar to or weaker than M and AGA.

• 한국재료학회지
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• 제31권11호
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• pp.601-607
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• 2021

Laser cladding a surface treatment process that grants superior characteristics such as toughness, hardness, and corrosion resistance to the surface, and rebuilds cracked molds; as such, it can be a strong tool to prolong service life of mold steel. Furthermore, compared with the other similar coating processes - thermal spray, etc., laser cladding provides superior bonding strength and precision coating on a local area. In this study, surface characteristics are studied after laser cladding of low carbon steel using 18%Cr-2.5%Ni-Fe powder (Rockit404), known for its high hardness and excellent corrosion resistance. A diode laser with wavelength of 900-1070 nm is adopted as laser source under argon atmosphere; electrical power for the laser cladding process is 5, 6, and 10 kW. Fundamental surface characteristics such as crossectional microstructure and hardness profile are observed and measured, and special evaluation, such as a soldering test with molten ALDC12 alloy, is conducted to investigate the corrosion resistance characteristics. As a result of the die-soldering test by immersion of low carbon alloy steel in ALDC12 molten metal, the clad layer's soldering thickness decreases.

• 천문학회보
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• 제46권1호
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• pp.38.1-38.1
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• 2021

본 발표에서는 Transformable Reflective Telescope(TRT kit)의 새로운 버전을 소개한다. TRT kit는 기본형인 뉴턴식 반사망원경에서 부경 교체를 통해 카세그레인식, 그레고리식으로 간단하게 변형 할 수 있는 광학 실험장치이다. 본 장치는 주로 망원경 교육이나 광학계 개발에 필요한 실험에 활용된다. 모듈화 설계를 통해서 여러 종류의 광학계를 쉽게 탈착하여 다양한 실험을 할 수 있다. 광기계부는 정밀하게 제작된 알루미늄 프로파일과 Isogrid구조를 채택하여 경량화 구조로 설계되었다. 이러한 경량부품들을 통해 이전 버전보다 50~70%의 중량 감소율을 달성하였다. 유한요소해석 결과 경량화된 뉴턴식 TRT kit는 이전 버전과 비교해서 자체 하중에 의한 최대 구조 변형이 0.11mm에서 0.023mm로 감소하였다. 부경 지지대 설계에는 자체 하중으로 인한 변형을 최소화하기 위해 트러스 (Truss) 구조가 도입되었다. 부경부의 자체 하중으로 인한 변형은 기존의 80㎛에서 21㎛로 감소하였다. 또한, 십자 레이저 정렬 장치가 추가되어 뉴턴식과 카세그레인식에서 공차 1.5' 이내로 광학계 정렬이 가능하다.

• 한방재활의학과학회지
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• 제31권2호
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• pp.1-14
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• 2021

Objectives We evaluated the improving effects of Taeksa-tang (TST) using 3T3-L1 cells and C57BL/6 mice were fed on a high-fat diet. Methods The anti-radical activities of TST were studied using 2,2-diphenyl-1-picrylhydrazyl and 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid). The content of total polyphenol was measured using Folin-Ciocalteu reagent, whereas aluminum chloride colorimetric method was used for the content of total flavonoid. Moreover, the factors related to lipid profile and the protein expressions such as 𝛽-oxidation and anti-oxidant enzyme were analyzed using serum and western blotting of 3T3-L1 cells. Additionally, we examined lipolysis through glycerol appearance in mouse adipose tissue. Results TST treatment showed strong free radical scavenging activities with half maximal inhibitory concentration and the presence of a amount of total polyphenol and total flavonoid. TST treatment significantly increased factors related to 𝛽-oxidation such as carnitine palmitoyl transferase-1 and uncoupling protein 2 via the phosphorlyation of liver kinase B1 (LKB1) and AMP-activated protein kinase (AMPK). Moreover, the protein expressions of anti-oxidant enzyme and lipolysis were significantly elevated by TST administration. In addition, TST supplementation lowered serum malondialdehyde, triglyceride, and total cholesterol levels compared with the control group. Taken together, these data suggest that TST treatment regulated lipid parameters via the increase of 𝛽-oxidation by LKB1-AMPK signaling pathway. Conclusions TST may have a potential remedy in the prevention and treatment of obesity. Therefore, this study may provide the scientific basis for TST use.

• 대한수의학회지
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• 제40권3호
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• pp.551-561
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• 2000

Swine respiratory diseases have induced severe economic losses in swine industry worldwide. Several methods have been developed and applied to prevent and control the disease. However, those are still problematic in swine industry. Recently, the use of egg yolk antibodies with several advantages was introduced and applied to control diseases in animal as well as human. As the first step of the use of egg yolk antibodies in the control of the swine respiratory diseases, we investigated the immunogens of the causative agensts of the diseases and immune response in egg yolk of hens immunized with them. Bacterial antigens prepared from Bordetella bronchiseptica, Pasteurella multocida 3A and 4D, and Actinobacillus pleuropneumaniae serotype 2 and 5 were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, Western blot and toxicity test in mice. The antigens were injected into laying hens in order to produce antibodies against them in egg yolk. After chickens were immunized three times in 2 weeks interval, the profile of antibody production was examined by ELISA. The production of antibody in egg yolk was started in 2 weeks after the first injection, reached peak in 6-8 weeks and maintained until 12 weeks. Of two adjuvants used in this study, ISA70 was more effective than aluminum hydroxide gel in enhancing immunogenecity, laying rates and safety in hens. These results suggested that egg yolk antibodies could be a good source for production of antibodies specific to pathogenic bacteria inducing respiratory diseases of swine.