• 펄프종이기술
• /
• 제36권1호
• /
• pp.16-23
• /
• 2004

Recently the increased concerns about the cost reduction and environmental protection make the paper industry increase the closure level of papermaking system, which results in the buildup of organic and inorganic materials in the papermaking process water. Increase of the system closure causes deterioration of additive performance and provokes diverse problems in papermaking process and product quality. To investigate the effects of process water quality on the physical properties of fine papers handsheets were prepared with process water containing various amounts of inorganic and organic contaminants including calcium or sodium ions and oxidized or cationic starches. Inorgainc and organic materials did not show any significant effect on the physical properties of handsheets. Recycled GCC showed the same trends as inorganic and organic materials. The performance of cationic starch was deteriorated, however, in the recycled white water, which resulted in the reduction of tensile index of handsheets.

• Steel and Composite Structures
• /
• 제24권2호
• /
• pp.239-248
• /
• 2017

Friction dampers are displacement dependent energy dissipation devices which dissipate earthquake energy through friction mechanism and widely used in improving the seismic behavior of new structures and rehabilitation of existing structures. In this paper, the cyclic behavior of a friction damper with different friction materials is investigated through experimental tests under cyclic loading. The damper is made of steel plates, friction pads, preloaded bolts and hard washers. The paper aims at investigating the hysteretic behavior of three friction materials under cyclic loading to be utilized in friction damper. The tested friction materials are: powder lining, super lining and metal lining. The experimental results are studied according to FEMA-356 acceptance criteria and the most appropriate friction material is selected by comparing all friction materials results.

• 기술사
• /
• 제30권6호
• /
• pp.144-152
• /
• 1997

Development of diamond wheel with fine grains and multi-pore structures were newely attempted to be studied in this paper. Wheels, that are employed for the smooth and mirrow finishing of die materials such as tungsten carbide alloy using tool and die materials, must have both performances to remove tool marks efficiently and to contact elastically with curved surfaces. Diamond abrasive grains were bonded firmly by a melamine to prevent the decrease of machining efficiency due to grain sinking within the bond materials. Also, highly foamed structures were developed to increase the flexibility of the wheel, and to induce active self-sharpening by increasing contact pressure between the wheel and work sufaces. In this paper, melamine-bonded diamond wheels are trial manufactured, then the forming method of wheels are explained.

• 한국레이저가공학회지
• /
• 제10권3호
• /
• pp.11-14
• /
• 2007

A trepanning optics is the optical system which makes focus laser beam rotate and incline to the material processing surface. The trepanning optics is used in order to improve the quality of laser drilling process and control the taper of drilling diameter. In order to make trepanning optics, we can use the eccentricity of lens, scanner using two mirror, dove prism, or wedge. Among these method, in this paper wedge is used for trepanning optics. The wedge trepanning optics has advantage on the high speed of rotation. In this paper, we design the wedge trepanning optics using ray tracing. ements and engine design variables of system to satisfy the customer's requirements.

• Journal of the Korean Wood Science and Technology
• /
• 제43권5호
• /
• pp.691-699
• /
• 2015

To evaluate the possibility of charcoal as Green Infrastructure (GI) materials, data such as moisture content, amount of adsorbed water, and amount of evaporation were collected. Some data from previous study were referenced to find out if correlations exist between results in this study and previous study. Only porosity was directly related to moisture content. Two mechanical charcoal had better abilities than traditional charcoal in all three categories. Mechanical black charcoal chips produced by National Forestry Cooperative Federation (NFCFC) adsorbed 333.3% of water in thirty minutes, 297.5% in five minutes, and evaporated around 75% water in four days. This ability is much higher than other five charcoal. Even though results of test showed various degrees and NFCFC was the best as GI materials, data of charcoal were also within acceptable range based on generally accepted characteristics of GI materials.

• 한국자동차공학회논문집
• /
• 제13권2호
• /
• pp.142-148
• /
• 2005

In this paper, the stress singularity on interface of friction welded dissimilar materials was investigated by using 2-dimensional elastic boundary element method. It is required that stress distributions and stress singularities on an interface for friction welded dissimilar materials analize to establish strength evaluation. The stress singularity index ($\lambda$) and stress singularity factor ($\Gamma$) were calculated from the results of stress analysis. The stress singularities on variations for shapes and thickness of friction welded flashes were analized and discussed. This paper suggested that the strength evalution by using the stress singularity factors as fracture parameters, considering the stress singularity on an interface edge of friction welded dissimilar materials were very useful.

• 한국정보디스플레이학회:학술대회논문집
• /
• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
• /
• pp.893-895
• /
• 2009

In this paper, we described the unique and novel method to prepare two kinds of electro-active particles, black and white particles with different polarity. The surface of the particles was characterized to be uniform and clean by adopting spray dryer as a tool for genesis of particles; neither surfactants nor high dielectric medium like water was employed during particle preparation step. The other purpose of this study is to investigate the factors that contribute high driving voltage of particlebased display like QR-LPD. We extracted parameters interaction between particle and electrode, and between oppositely charged particles. Here we reported an excellent behavior of particle-based display that showed low operating voltage, high contrast ratio as high as 8:1 without scarification of quick response time. By optimizing the particle size, charge per mass, selection of external additive sets, a lower driving voltage as low as 40V for the particles with $10{\mu}m$ volume average diameter was obtained.

• 산업경영시스템학회지
• /
• 제28권3호
• /
• pp.10-17
• /
• 2005

In this paper, the life cycle assessment(LCA) methodology is applied to Personal Computer's basic materials in order to analyze the impact to the environment. LCA data collection is carried out taking into account on main materials of PC's parts and component. And the impact assessment is the environmental burden on three factor into air emission(CO2, SOx, NOx), five factor into water emission(BOD, COD, SS, N, P), and three factor on transported substance(cl, NH4, SO4). According to the result, the environmental burden of PC's basic materials was proved to be used total energy 6,285Mj and emitted CO2 259.8kg, SOx 3,571g, NOx 330g, COD 1,328g, P 246g, N 2,434g. And this paper was presented the problems of its disposition-incinerating, landfill, and recycling.

• Steel and Composite Structures
• /
• 제51권3호
• /
• pp.261-270
• /
• 2024

This paper proposes an effective method for optimizing the structure of functionally graded isotropic and incompressible linear elastic materials. The main emphasis is on utilizing a specialized polytopal composite finite element (PCE) technique capable of handling a broad range of materials, addressing common volumetric locking issues found in nearly incompressible substances. Additionally, it employs a continuum model for bi-directional functionally graded (BFG) material properties, amalgamating these aspects into a unified property function. This study thus provides an innovative approach that tackles diverse material challenges, accommodating various elemental shapes like triangles, quadrilaterals, and polygons across compressible and nearly incompressible material properties. The paper thoroughly details the mathematical formulations for optimizing the topology of BFG structures with various materials. Finally, it showcases the effectiveness and efficiency of the proposed method through numerous numerical examples.

• 한국재료학회:학술대회논문집
• /
• 한국재료학회 2000년도 제1회 신소재 심포지엄(차세대 광소재 심포지엄)
• /
• pp.77-85
• /
• 2000

Photosensitive amorphous materials are attractive for the formation of several optical elements by a specific laser beam irradiation. For example the optical fiber gratings prepared by UV laser irradiation are one of the key elements for the recent worldwide progress of wavelength division mutiplexing optical fiber network. This paper reviews the representative studies on the photosensitive materials and the origin of photosensitivity in amorphous oxide materials.