• 대한치과기공학회지
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• 제30권2호
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• pp.31-37
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• 2008

A variety of the porcelain fused to gold(PFG) have been developed to which porcelain can be fused. PFG alloys developed for this purposed have a high melting point and do not discolor when combined with porcelain. The design of the compositions of PFG is very important to esthetic restorative materials applying to porcelain. The purpose of this study is on the change of physical and mechanical characteristics in PFG 18K alloy by the small additional elements. Principal results are as follows. The high Au alloy containing 18Karat gold contents is respectively Au(75%), Pd(10%), Pt(4%), Ag(4%), In(2%), Sn(2%), Cu(2%), Ti(1%). These alloys are composed mainly of gold, platinum, silver and palladium with a few percent of the additional elements. By the addition of small amounts of elements such as In, Sn, Ti, the fine grain castings are produced in gold alloy and the small addition of platinum is very effective in increasing of hardness and strength. These gold alloys are representative of the changes to be expected as a result of heat treatment. These changes in strength and hardness values are sufficient to demonstrate a significant difference in performance between a as-casted and a heat-treated. These alloys have mechanical properties characteristics of Type and Type gold alloys. These alloys are useful to porcelain-metal restorations and dental laboratory. Also the porcelain fused to metal(PFM) alloys containing gold are commonly use for dental purposes in dental laboratory.

• 대한금속재료학회지
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• 제48권10호
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• pp.951-956
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• 2010

This study examined the effect of copper and sulfuric acid concentrations on the surface morphology and physical properties of copper plated on a polyimide (PI) film. Electrochemical experiments with SEM and a four-point probe were performed to characterize the morphology and mechanical characteristics of copper electrodeposited in the composition of an electrolyte. The resistivity and peel strength were controlled using a range of electrolyte compositions. A lower resistivity and high flexibility were obtained when an electrolyte with 20 g/l of copper was used. However, a uniform surface was obtained when a high current density that exceeded $20mA/cm^2$ was applied, which was maintained at copper concentrations exceeding 40 g/l. Increasing sulfuric acid to >150 g/l decreased the peel strength and flexibility. The lowest resistivity and fine adhesion were detected at a $Cu^{2+}:H_2SO_4$ ratio of 50:100 g/l.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.596-601
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• 2004

In this paper, we describe a study on the influence of the frequency variation of normal vibration using an integrated tactile display. It is necessary to consider this study because we want to find a method of displaying finer texture and know that the perception of fine textures is heavily influenced by temporal variation. Our tactile display system used in this experiment can simulate the micro shapes and roughness of surface textures by individual drives of a 6x8 pin array. Two experiments are performed. The first is a psychophysical experiment on the definition and range decision of roughness, and through the experiment, we clear up the meaning of roughness. The second is the main experiment about the frequency variation of normal vibration. We find the correlation between the vibration frequency and the texture and the condition for better display and perception of fine surfaces. The experimental results yielded two pieces of information. One is that lateral movement affects texture discrimination, and another is that normal vibration can make the perceived texture feel finer than real texture. That is, the vibrating stimulus is more effective for displaying a fine surface than static pressure, and it makes possible to display finer texture, exceeding the physical limit of the device.

• 펄프종이기술
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• 제32권2호
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• pp.1-7
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• 2000

In the previous experiment, it was found that OCC pre-treatment with Hobart mixer at 20-25％ consistency for 3 hrs or more followed by the application of the equal refining time, caused the increase of tensile strength, burst strength, compressive strength and tear resistance, compared to the no pre-treated. Four completely different fibers, which were Hw-BKP, Sw-BKP, White ledger, and OCC were selected for this experiment to investigate the effect of mechanical pre-treatment process on different fibers. From the experiment, it was found that the mechanical pre-treatment did not decrease fiber length at all, but decreased freeness, com-pared to the no pre-treated, when the same refining time was applied. WRVs of the pre-treated fibers were higher than the no pre-treated at the same freeness level. It was speculated that the mechanical pre-treatment induced only hydrophilic nature of fibers without damaging fiber length by delaminating fiber walls. The fiber surface area and the physical strength differences of handsheets will be discussed in the next publication.

• 한국세라믹학회지
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• 제47권1호
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• pp.82-85
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• 2010

Recently, thin film processes for oxides and metal deposition, such as physical vapor deposition (PVD) and chemical vapor deposition (CVD), have been widely adapted to fabricate solid oxide fuel cells (SOFCs). In this paper, we presented two research area of the use of such techniques. Gadolinium doped ceria (GDC) showed high ionic conductivity and could guarantee operation at low temperature. But the electron conductivity at low oxygen partial pressure and the weak mechanical property have been significant problems. To solve these issues, we coated GDC electrolyte with a nano scale yittria-doped stabilized zirconium (YSZ) layer via atomic layer deposition (ALD). We expected that the thin YSZ layer could have functions of electron blocking and preventing ceria from the reduction atmosphere. Yittria-doped barium zirconium (BYZ) has several orders higher proton conductivity than oxide ion conductor as YSZ and also has relatively high chemical stability. The fabrication processes of BYZ is very sophisticated, especially the synthesis of thin-film BYZ. We discussed the detailed fabrication processes of BYZ as well as the deposition of electrode. This paper discusses possible cell structure and process flow to accommodate such films.

• 한국의류학회지
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• 제20권1호
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• pp.157-169
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• 1996

Polyester yarns and fabrics containing three levels of $TiO_2$ delusterant were hydrolyzed with NaOH and examined for physical and morphological changes. The mechanical propertis and hand values of alkaline hydrolyzed polyester fabrics were measured using KES-FB system. Also, the relationship between the morphology and the mechanical property of alkaline hydrolyzed polyester fabrics was analyzed. The results are as follows: 1. At an initial stage of alkaline treatment, the concentration of $TiO_2$ did not affect the weight loss of the treated yarns. But by increasing treatment time, the effect of the concentration of $TiO_2$ on the weight loss of the fiber became more pronounced. The weight loss were increased in the following order; fulldull> semidull> clear 2. The effect of hydrolysis on yarn tensile strength seems to be more related to the size of the pits on the fibers rather than the number of pits. 3. Axially oriented pits occurred along the hydroyzed, delustered fiber surfaces, while such pitting was absent on hydrolyzed fiber containing no $TiO_2$. The number of voids across the surface of a fiber increased with an increase in the amount of TiOa incorporated into the fibers. The size of the voids depended on the treatment time of hydrolysis rather than the concentration of TiOa. 4. The mechanical properties and hand values of polyester fabrics were changed by alkaline treatment but were identical regardless of the concentration of TiOa. While the mechanical properties of polyester fabrics depended on the structural change of the fibers and the yarns within the fabrics as the fiber diameter became progressively smaller rather than the size and number of pits.

• 터널과지하공간
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• 제25권3호
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• pp.231-243
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• 2015

본 연구에서는 최근 재개발되고 있는 정선지역의 철광산에서 현장 초기지압 시험과 수많은 암석 실내시험을 실시하였다. 본 광산의 측압계수는 심도가 깊어질수록 작아지는 경향을 보였으며 평균값은 1.10으로 나타났다. 본 광산에 주로 분포하는 네 가지 암종인 백운암, 규장암, 화강암, 철광석에 대한 실내시험을 통해 암석의 단위중량, 공극률, 흡수율, 탄성파속도, 일축압축강도, 영률, 포와송비, 인장강도, 쇼어경도, 내부마찰각, 점착력 등의 각종 역학적 특성을 조사하였다. 실내시험 결과의 통계분석을 통해 암종별 물성을 비교하였고 물성 상호간의 관련성을 검토하였는데, 철광석보다는 규장암이나 화강암의 강도특성이 더 컸으며 암석 물성 간의 일반적인 상관관계와는 반대되는 현상도 발견되었다. 또한 Mohr-Coulomb 파괴조건과 Hoek-Brown 파괴조건을 적용하여 네 가지 암석의 파괴조건을 해석하였다.

• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 2000년도 춘계학술발표논문집
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• pp.69-69
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• 2000

In the previous experiment, it was found that OCC pre-treatment with Hobat mixer at 20-25% consistency for 3 hrs or more followed by the application of the equal refining time, caused the increase of tensile strength, burst strength, compressive strength and tear resistance, compared to the no pre-treated. Four completely different fibers, which were Hw-BKP, Sw-BKP, White ledger, and OCC were selected for this experiment to investigate the effect of mechanical pre-treatment process on different fibers. From the experiment, it was found that the mechanical pre-treatment did not decrease fiber length at all, but decreased freeness, compared to the no pre-treated, when the same refining time was applied WRVs of the pre-treated fibers were higher than the no pre-treated at the same freeness level. It was speculated that the mechanical pre-treatment induced only hydrophilic nature of fibers without damaging fiber length by delaminating fiber walls. The fiber surface area and the physical strength differences of handsheets will be discussed in the next publication.

• Journal of Advanced Marine Engineering and Technology
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• 제40권9호
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• pp.774-779
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• 2016

본 연구에서는 선박의 곡 외판 구조에 TMCP 강재의 사용 범위 확대 가능성을 연구하고자 노말라이징강 및 TMCP 강 DH32 재질 강재에 선상가열 후 기계적 물성 시험을 실시하여 DNV 선급 및 IACS 규정의 품질 요구 기준에 적합한지 연구하였다. TMCP강재 인장시험에서 요구기준 YS = 315 MPa 대비 385 Mpa로서 약 18% 높게 나타났고, TS = 440 ~ 570 MPa 기준 대비 525 MPa로 요구 기준에 적합하였다. 샤르피 V-노치 $-20^{\circ}C$ 충격시험에서도 요구 기준에 적합하였으며 경도시험에서 평균 T : 216, L : 275로서 규정인 Hv10 = 130 ~320 범위에 만족 하였다.

• 한국세라믹학회지
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• 제41권3호
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• pp.210-215
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• 2004

하수슬러지 소각재, 폐도자기 파편, 폐유약 및 저급점토를 이용하여 1,00$0^{\circ}C$에서 2시간 소성하여 투수블록용 다공질 세라믹스를 제조하여 제조인자에 따른 물리 $.$역학적 특성, 투수특성 및 동결음해특성을 조사하였다. 폐도자기 파편의 크기가 동일한 시편은 소성온도와 소각재의 첨가량이 증가함에 따라 부피비중과 압축강도는 증가하였으나, 기공률과 투수성은 감소하였다. 소성온도와 소각재의 첨가량이 동일한 시편은 폐도자기 파편의 크기가 증가하면 부피비중과 압축강도는 감소하고 기공률과 투수성은 증가하였다. 폐도자기 파편의 크기가 1∼2 mm이고 1,00$0^{\circ}C$에서 2시간 소성한 30A60F시편은 부피비중 2.17, 기공률 46.2%, 압축강도 221 kgf/$\textrm{cm}^2$ 및 통과전하량이 3,150 coulombs이었으며, 동결융해 저항성이 우수하여 투수블록으로 사용이 가능하였다. 투수블록 시편에 함유된 중금속은 허용기준치보다 낮아 무해하였다.