• Journal of Welding and Joining
• /
• 제18권5호
• /
• pp.90-97
• /
• 2000

Effect of alloy elements on joinability of insert metal for liquid phase diffusion bonding of heat resistant alloys was investigated in this study. Also, optimum chemical composition of insert metal was explained using interpolation method. The insert metals utilized was commercial Ni-base amorphous foils and newly developed Ni-base filler metals with B, Si and Cr in this study. Melting point and critical interlayer width(CIW) decreased with increasing additional amount of B, Si and Cr, melting point lowering element of the insert metal. Optimized chemical composition of insert metals could be estimated by interpolation method. The optimum amount of B, Si, Cr addition into the insert metal were found to be about 3%, 4% and 3%, respectively. The measured characteristic values, melting point, microhardness in the bonded interlayer and CIW of the insert metals were the almost identical to ones of the calculated results by interpolation method.

• Journal of the Korean Wood Science and Technology
• /
• 제43권4호
• /
• pp.421-428
• /
• 2015

본 연구는 5개 종자 산지(Carleton, Simcoe, Chatham, Bancroft, Unknown)의 루브라참나무(Quercus rubra)를 대상으로 해부학적 성질을 조사하여, 이들의 종자산지 간 및 생장속도와의 관계를 규명하였다. 루브라참나무는 환공재로서 공권부는 대형도관이 1~3열로 배열하다가 공권 외부는 소형도관이 방사상으로 배열하였다. 산지 간에는 조재부 목섬유 길이, 조재부 도관의 직경에서만 차이가 있었다. 생장속도와는 목섬유 길이 및 도관요소 직경에서 만재부는 상관관계가 없고, 조재부는 부의 상관이었다. 도관요소 길이는 생장속도와 조, 만재에서 관계가 없었다. 조, 만재부에서의 구성요소 비율은 목섬유, 방사조직은 만재부에서 높았고, 도관요소는 조재부에서 높았다. 방사조직 높이는 11~15개 범위였다.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 1999년도 춘계학술대회 논문집
• /
• pp.226-231
• /
• 1999

A composition brake shoe composed of iron, graphite, kevlar, barium sulphate, etc. was developed for Diesel locomotives. The density distribution of the shoe depends on groove shapes of the shoe (or punch shape). In this study, we investigated the influence of the punch shape on the density distribution, stresses, etc. The inclination of the groove exerts more influence on the density distribution than the groove filet radius.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2004년도 춘계학술발표회
• /
• pp.197-202
• /
• 2004

In order to design accurately sand compaction pile (SCP) method with low replacement area ratio, it is important to understand the mechanical interaction between sand piles and clays and its mechanism during consolidation process of the composition ground. In this paper, a series of numerical analyses on composition ground improved by SCP with low replacement area ratio were carried out, in order to investigate the mechanical interaction between sand piles and clays. The applicability of numerical analyses, in which an elasto-viscoplastic consolidation finite element method was applied, could be confirmed comparing with results of a series of model tests on consolidation behaviors of composition ground improved by SCP. And, through the results of the numerical analyses, each mechanical behaviors of sand piles and clays in the composition ground during consolidation was elucidated, together with stress sharing mechanism between sand piles and clays.

• 한국대기환경학회지
• /
• 제25권2호
• /
• pp.122-132
• /
• 2009

Adsorption of toluene by activated carbon fiber (ACF) coated with dielectric heating element and desorption by applying microwave were investigated. In order to prepare adsorbent so that VOC can be desorbed by microwave heating, fine dielectric heating element with nano size was coated on the surface of the ACF using hybrid binder. Eight adsorbents (ACF-DHE, Activated Carbon Fiber coated with Dielectric Heating Element) were prepared with different amount of dielectric heating element, kinds of hybrid binder, and solvent. In order to investigate adsorption characteristics, BET surface area, pore volume, and average pore size were measured for each adsorbent including ACF. Breakthrough experiments with toluene concentration, flow rate, bed length using fixed bed reactor were performed to investigate adsorbality of adsorbent, and results were compared with that of the ACF. Desorption reactor was constructed with modified microwave oven to investigate heating effect on ACF-DHE by applying microwave power. Each adsorbent saturated with toluene were put into desorption reactor. Composition of desorbed gas generated by applying controlled microwave power to reactor was measured. Up to now, hot air desorption method has been used. Experimental results showed that desorption method with new adsorbent prepared by coating dielectric heating element on ACF can be used for industrial application.

• International Journal of Korean Welding Society
• /
• 제5권1호
• /
• pp.10-14
• /
• 2005

An element of Pure Weld Metal(PWM) is important factor to understand the Flux's conduct in Submerged Arc Welding(SAW). To get the element of PWM, pile-up welding over than 10 layers have been used in the past. But, it took a long time to analyze the elements of PWM in this method. Therefore, in this study, instead of pile-up welding over than 10 layers, one pass bead welding is used to predict an element of PWM using mathematical formula which got to be derived. As a results that applied the formula, there was no differences between theoretical and experimental value except the element Mn and Si.

• Structural Engineering and Mechanics
• /
• 제37권3호
• /
• pp.321-330
• /
• 2011

Long-term properties of concrete affect structures in many respects, not excepting dynamic behaviors. This paper investigates the influence of concrete creep on the dynamic behaviors of concrete filled steel tube (CFT) arch bridges, by means of combining the analytical method for the creep of axially compressed CFT members, which is based on Model B3 for concrete creep, with the finite element model of CFT arch bridges. By this approach, the changes of the stress and strain of each element in the bridge with time can be obtained and then transformed into damping and stiffness matrices in the dynamic equation involved in the finite element model at different times. A numerical example of a long-span half-through CFT arch bridge shows that creep influences the natural vibration characteristics and seismic responses of the bridge considerably, especially in the early age. In addition, parameter analysis demonstrates that concrete composition, compressive strength and steel ratio have an obvious effect on the seismic response of the CFT arch bridge.

• 암석학회지
• /
• 제17권3호
• /
• pp.133-143
• /
• 2008

지표지질의 지구화학적 변화 추적과 고고학 유물의 원료(점토질 토양)의 기원지를 밝혀내기 위한 도구로서의 희토류원소의 역할을 확인하고자 하였다. 실험용 지질시료로는 화강암과 편마암 그리고 이들로부터의 화학적 풍화과정을 거친 풍화암과 풍화토양을 선택하여 이들의 화학조성변화를 비교하였고, 고고학적 응용을 위한 시료로는 점토질 토양과 이를 이용하여 제조한 토기 및 도기를 채취하여 이들의 화학조성변화를 비교하였다. 연구결과에 의하면, 일반적인 화학조성간의 상대적인 비교로는 암석-풍화암-토양 혹은 점토질 토양-토기-도기로의 변화에 따른 지구화학적 특성변화의 상관성이 없는 반면에 PAAS(Post Archean Australian Shale)로 규격화한 희토류원소 분포도는 거의 동일한 양상을 띄었다. 이는 희토류원소의 분포도가 다른 지구화학적 연구기법에 기법에 비해 퇴적물의 기원물질 혹은 고고학적 유물의 재료를 밝혀내는데 더 유용함을 지시해준다고 볼 수 있다.

• 한국환경과학회지
• /
• 제27권7호
• /
• pp.543-554
• /
• 2018

From November 2013 to December 2016, ambient fine particulate matter ($PM_{2.5}$) was sampled in the downtown area of Jeju City, South Korea, which has seen rapid urbanization. The atmospheric concentrations of elements were measured in the $PM_{2.5}$ samples. This study focused on Cd, Cr, Cu, Mn, Ni, Pb, As, Sb, Sn, V, and Zn. The concentrations of Al, Na, K, Fe, Ca, Mg, Sr, and La were also obtained for reference. The objectives of this study were to examine the contributions of these elements to $PM_{2.5}$ concentrations in downtown Jeju City, and to investigate the inter-element relationships and the elemental sources by using enrichment factors and principal components analysis (PCA). A composition analysis showed that the 19 elements constituted 6.65 % of the $PM_{2.5}$ mass, and Na, K, Al, Fe, Ca, Mg, and Zn constituted 98 % of the total ion mass. Seasonal trend analysis for the sampling period indicated that the concentrations of the elements increased from November to April. However, no substantial seasonal variations were found in the concentrations of the elements. The composition ratios of some elements (Cu/Zn, Cu/Cd, Cu/Pb, V/Ni, and V/La) were found to be out of range when compared to the literature from other urban areas. The ratios between the elements and the PCA results showed that local contaminant sources in Jeju City rarely influence the composition of $PM_{2.5}$. This suggests that the major sources of $PM_{2.5}$ in Jeju City may include long-range transport of fine particulate matter produced in other areas.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2009년도 제38회 동계학술대회 초록집
• /
• pp.359-359
• /
• 2010

Self-organized nanostructures of dots, holes or ripples produced by energetic ion bombardment have been reported in a wide variety of substrates. Ion bombardment on an alloy or compound also draws much attention because it can induce a surface composition modulation with a topographical surface structure evolution. V. B. Shenoy et al. further suggested that, in the case of alloy surfaces, the differences in the sputtering yields and surface diffusivities of the alloy components will lead to a lateral surface composition modulation [1]. In the present work, the classical molecular dynamics simulation of Ar bombardment on metallic alloys at room temperature revealed that this bombardment induces a surface composition modulation in layer-by-layer mode. In both the $Co_{0.5}Cu_{0.5}$ alloy and the CoAl B2 phase, the element of higher-sputtering yield is accumulated on the top surface layer, whereas it is depleted in lower layers. A kinetic model considering both the rearrangement and the sputtering of the substrate atoms agrees with the puzzling simulation results, which revealed that the rearrangement of the substrate atoms plays a significant role in the observed composition modulation.