• 한국가구학회지
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• 제20권1호
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• pp.82-94
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• 2009

In this study, I suggest dyed-Glued laminated woods by using birch woods which are relatively cheaper than others. Since the dyed-Glued laminated woods which have the various colors to satisfy people's tastes and the dignified grains in the old woods enable us to product freely, these can provide us with stability of supply through replacing rare materials. The making wooden furniture designed with dyed-Glued laminated woods has these following characteristics. (1) This method which uses various colored woods can fulfill consumers' tastes through dyeing wooden plates, instead of using domestic woods which have limited colors-white, yellow and black. (2) Gathering wooden plates made by setting them into various frames enables us to get in large quantities of the materials with good grains, which we can only take from old woods. (3) Producing culture products using various colors and grains has enabled us to satisfy consumers and to create pro-environmental pieces. In conclusion, this study can be an alternative idea to forest resources which have been decreasing, and be an application method of using cheaper birch woods as well. Gathering and dyeing wooden plates might bring about the economic effect and be of much help to the expansion as furniture materials as well as interior ones.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2005년도 International Meeting on Information Displayvol.II
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• pp.1534-1535
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• 2005

Highly luminescent efficiency phosphors have been successfully produced by surface modification and microwave irradiation treatment. The SEM image and XRD analysis reveal that the surface morphology of the white-light phosphors can be notably modified by microwave irradiation and exhibit with better crystalline property. The VUV PL spectra show that the microwave irradiation treatment can effectively enhance the luminescent efficiency by a factor of 1.5 times for intensity compared to that without microwave treatment. A further improvement in all visible emission can be made by modifying surface composition through MgO coating on the phosphor powder. These results demonstrate that such a simple approach can provide for improving luminescent efficiency of phosphors for the optoelectronic devices.

• 마이크로전자및패키징학회지
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• 제20권4호
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• pp.65-68
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• 2013

A novel bumping process using solder bump maker (SBM) is developed for fine-pitch flip chip bonding. It features maskless screen printing process. A selective solder bumping mechanism without the mask is based on the material design of SBM. Maskless screen printing process can implement easily a fine-pitch, low-cost, and lead-free solder-on-pad (SoP) technology. Its another advantage is ternary or quaternary lead-free SoP can be formed easily. The process includes two main steps: one is the thermally activated aggregation of solder powder on the metal pads on a substrate and the other is the reflow of the deposited powder on the pads. Only a small quantity of solder powder adjacent to the pads can join the first step, so a quite uniform SoP array on the substrate can be easily obtained regardless of the pad configurations. Through this process, an SoP array on an organic substrate with a pitch of 130 ${\mu}m$ is, successfully, formed.

• Advanced Composite Materials
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• 제17권4호
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• pp.373-407
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• 2008

This paper will examine the possibilities of the virtual tests of composite structures by simulating mechanical behaviors by using supercomputing technologies, which have now become easily available and powerful but relatively inexpensive. We will describe mainly the applications of large-scale finite element analysis using the direct numerical simulation (DNS), which describes composite material properties considering individual constituent properties. DNS approach is based on the full microscopic concepts, which can provide detailed information about the local interaction between the constituents and micro-failure mechanisms by separate modeling of each constituent. Various composite materials such as metal matrix composites (MMCs), active fiber composites (AFCs), boron/epoxy cross-ply laminates and 3-D orthogonal woven composites are selected as verification examples of DNS. The effective elastic moduli and impact structural characteristics of the composites are determined using the DNS models. These DNS models can also give the global and local information about deformations and influences of high local in-plane and interlaminar stresses induced by transverse impact loading at a microscopic level inside the materials. Furthermore, the multi-scale models based on DNS concepts considering microscopic and macroscopic structures simultaneously are also developed and a numerical low-velocity impact simulation is performed using these multi-scale DNS models. Through these various applications of DNS models, it can be shown that the DNS approach can provide insights of various structural behaviors of composite structures.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.295-296
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• 2006

High hardness of P/M parts can be obtained in the cooling section of the sintering furnace by using sinter hardenable materials, thus the post-sintering heat treatment can be eliminated. However, the sinter hardened materials would have difficulties in secondary machining if it is required, which will limit the applications of sinter hardenable materials in the machined parts. Recent development in warm compaction technology can enable us not only to achieve the high green density up to $7.4\;g/cm^3$, but also the high green strength which is needed for green machining. Therefore by using warm compaction technology, the green machining can be applied to sinter hardenable materials for the high density, strength and hardness P/M parts. In the present study, a pre-alloyed steel powder, ATOMET4601, was used by mixing with 2.0% copper, 1.0% nickel, 0.9% graphite and a proprietary lubricant using a binder treatment process - FLOMET. The specimens were compacted and green machined with different machining parameters. The machined surface finish and part integrity were evaluated in selecting the optimal conditions for green machining. The possibility of applying the green machining to the high-density structural parts was explored.

• ETRI Journal
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• 제41권3호
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• pp.396-407
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• 2019

Laser-assisted bonding (LAB) is an advanced technology in which a homogenized laser beam is selectively applied to a chip. Previous researches have demonstrated the feasibility of using a single-tier LAB process for 3D through-silicon via (TSV) integration with nonconductive paste (NCP), where each TSV die is bonded one at a time. A collective LAB process, where several TSV dies can be stacked simultaneously, is developed to improve the productivity while maintaining the reliability of the solder joints. A single-tier LAB process for 3D TSV integration with NCP is introduced for two different values of laser power, namely 100 W and 150 W. For the 100 W case, a maximum of three dies can be collectively stacked, whereas for the 150 W case, a total of six tiers can be simultaneously bonded. For the 100 W case, the intermetallic compound microstructure is a typical Cu-Sn phase system, whereas for the 150 W case, it is asymmetrical owing to a thermogradient across the solder joint. The collective LAB process can be realized through proper design of the bonding parameters such as laser power, time, and number of stacked dies.

• 방사성폐기물학회지
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• 제20권2호
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• pp.171-183
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• 2022

The parent and daughter nuclides in a radioactive decay chain arrive at secular equilibrium once they have a large half-life difference. The characteristics of this equilibrium state can be used to estimate the production time of nuclear materials. In this study, a mathematical model and algorithm that can be applied to radio-chronometry using the radioactive equilibrium relationship were investigated, reviewed, and implemented. A Bateman equation that can analyze the decay of radioactive materials over time was used for the mathematical model. To obtain a differential-based solution of the Bateman equation, an algebraic numerical solution approach and two different matrix exponential functions (Moral and Levy) were implemented. The obtained result was compared with those of commonly used algorithms, such as the Chebyshev rational approximation method and WISE Uranium. The experimental analysis confirmed the similarity of the results. However, the Moral method led to an increasing calculation uncertainty once there was a branching decay, so this aspect must be improved. The time period corresponding to the production of nuclear materials or nuclear activity can be estimated using the proposed algorithm when uranium or its daughter nuclides are included in the target materials for nuclear forensics.

• Corrosion Science and Technology
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• 제18권6호
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• pp.277-284
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• 2019

External corrosion control of buried pipe can be achieved by the combination of barrier coating and cathodic protection. Coating damage and deterioration can be induced by many reasons; damage during handling and laying, enhanced failure at low temperatures, failure during commissioning and operation, disbanding due to inadequate surface cleaning, rock penetration during installation and service etc. This work focused on the effect of survey conditions on the reliability of coating flaw detection of buried pipes. The effects of applied voltage and anode location on the detection reliability of coating flaw of buried pipe in soil with the resistivity of ca. 25.8 kΩ·cm were discussed. Higher applied voltage increased the detection reliability, regardless of buried depth, but deeper burial depth reduced the reliability. The location of the anode has influenced on the detection reliability. This behaviour may be induced by the variation of current distribution by the applied voltage and buried depth. From the relationship between the applied voltage and reliability, the needed detection potential to get a desire detection reliability can be calculated to get 100% detection reliability using the derived equation.

• 한국축산시설환경학회지
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• 제12권1호
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• pp.41-44
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• 2006

2중필름 온실계사에서 육계를 사육하였을 때 발생하는 계분을 처리할 수 있는 수동 교반형 퇴비화시스템을 개발하였으며, 교반빈도가 퇴비화 온도에 미치는 효과를 분석하였다. 병원균 사멸에 필요한 $55^{\circ}C$ 이상의 온도를 유지한 기간은 무교반에서 88시간 1회/4일의 교반에서는 179 시간, 1회/2일의 교반에서는 200 시간으로 교반회수가 빈번할수록 그 기간이 길어지는 것으로 나타났다.

• Design & Manufacturing
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• 제12권2호
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• pp.34-39
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• 2018

The biggest topics in the automobile industry are light weightening and fuel efficiency improvement. There's a lot of research going on. It is focused on light weight materials. Light weight material is seen as the best way to reduce fuel consumption and to solve the problem of environmental pollution and resource depletion. For the light weight materials, new materials such as aluminum, magnesium, and carbon-hardening materials can be found. Research on the joining techniques of dual materials, improvement of material properties by improving the method of manufacture of existing materials, and studies on ultra-high strength steel sheets are expected to take up the most weight in lightweight materials. As the strength of the ultra-high strength steel sheets increases during forming, it is difficult to obtain dimensional precision due to the increase in elastic restoring force compared to mild or high strength steel sheets. Spring back is known to be affected by a number of factors due to poor plastic molding, and can be divided into the effects of the material spraying and the process. The study on the plasticitic variables were studied as plasticitic factors that can be controlled by a part company. Tensile testing of ultra-high strength materials was conducted to derive properties for plasticitic analysis and to analyze spring back with two factors controlling the height of the bead and blank holding force by adding tensile force and controlling the flow rate.