• Journal of Advanced Marine Engineering and Technology
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• v.33 no.2
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• pp.244-251
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• 2009

Porous media have especially large surface area per volume, which contain complex fluid passage. If porous media can be applied to cool a CPU or an electronic device with large heat dissipation, it could result in heat transfer enhancement due to the enlargement of the heat transfer area and the flow disturbance. This study is aimed to identify the heat transfer and pressure drop characteristics of high-porosity metal foams in a horizontal channel. Experiment is performed with the various heat flux, velocity and pore density conditions. Permeabilities, which is deduced from Non-Darcy flow model, become lower with increasing pore density. Nusselt number also decreases with higher pore density. High pore density with same porosity case shows higher pressure loss due to the increase of surface area per unit volume. The fiction factor decreases rapidly with increase of Reynolds number in Darcy flow region. However, it converges to a constant value of the Ergun coefficient in Non-Darcy flow region.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.1499-1504
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• 2004

The effects of absorbing materials on the characteristics of supersonic jet noise were experimentally investigated using a convergent-divergent nozzle with a design Mach number of 2.0. Overall sound pressure levels (OASPL) and noise spectra were obtained at far-field locations. Schlieren optical system was used to visualize the flow-fields of supersonic jets. In order to investigate the effect of absorbing materials, baffle plates of different materials (metal, grass wool and polyurethane foam) were installed at the exit of the nozzle. Experiment was carried out over a wide range of nozzle pressure ratios from 2.0 and 18.0, which corresponds to over- and under-expanded conditions. The results obtained show that the screech tone amplitude and the overall sound pressure level reduce by using the baffle plates of absorbing materials, compared with the metal baffle plate. It is also found that the characteristics of supersonic jet noise are strongly dependent on the size of baffle plate.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.209-212
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• 2001

Aircraft industry is developed very fast so titanium scrap was generated to manufacture. Titanium scrap was wasted and used to deoxidize cast iron so we are study recycling of it. In this research were studied that metal hydride of reacted in hydrogen chamber of AMS4900, 4901, return scrap titanium alloy and sponge titanium granule. The temperature of hydrogenation was 40$0^{\circ}C$ in the case of pure sponge titanium but return scrap titanium alloy were step reaction temperature at 40$0^{\circ}C$ and 50$0^{\circ}C$, and after the hydride of titanium alloy were crushed by ball mill for 5h. Titanium hydride contains to 4wt.% of hydrogen theoretically as theory. It was determined by heating and cooling curve in reaction chamber. The result of XRD was titanium hydride peak only that it was similar to pure titanium. Titanium hydride Powder particle size was about 45${\mu}{\textrm}{m}$, and recovery ratio was 95w% compared with scrap weight for a aluminum foam agent.

• 한국전산유체공학회:학술대회논문집
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• 2010.05a
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• pp.446-447
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• 2010

최근 개발된 니켈 초합금 금속폼은 기존의 매연저감장치 신소재로 여겨지고 있다. 금속폼은 세가지 두드러진 특징을 갖고 있다. 첫째, 금속폼은 큰 기공의 다공성 매질로써 매연을 포집하여 축적할 수 있는 용량이 기존 필터에 비해 상대적으로 크며 그로인하여 재생 시 연소 안전성이 두드러진다. 둘째, 복잡하고 굴곡있는 기공 구조와 큰 비표면적은 물질전달 특성을 향상시켜 촉매 적용 시 촉매의 전환성능을 향상시키고 그로 인하여 귀금속 촉매량을 줄일 수 있는 장점이 있다. 셋째, 금속폼은 다양한 기공크기를 가지며, 다양한 조합의 금속폼을 개발할 수 있어 요구 성능에 따른 최적의 필터 설계를 가능케 한다. 이번연구에서는, 금속폼의 필터 성능을 다양한 실험을 통하여 측정 평가하며, 이런 이해를 기반으로 필터로 제작하여 엔진실험벤치에서 그 성능을 검증하였다. 필터의 성능은 수트 포집효율과 그에 따른 필터의 압력강하와 촉매 활성 능력으로 평가되었다. 이러한 실험과 병행하여 금속폼에서의 수트 포집과정을 모델링하고 이를 상용 프로그램인 CFD-ACE+에 추가하여 설계전용 프로그램을 개발하였으며, 엔진실험결과와 비교 검증하였다. 본 논문에서는 금속폼의 높은 매연축적용량과 향상된 물질전달 특성이 어떻게 필터의 귀금속 촉매와 체적을 줄일 수 있는지 제시하고 있다.

• Membrane Journal
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• v.8 no.4
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• pp.191-202
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• 1998

The emission standards for diesel particulates have been continued to become tighter. This article reviews the pore and how to filtering characteristics and how to design the ceramic honeycomb filter which is generally used for diesel particulate filter. And the properties and fabrication methods of other particulate filters, i.e. ceramic fiber candle filter, ceramic foam filter, ceramic cross-flow filter and metal filter, are presented in this review. The results show that though the various filters have been developed and tested in the field, the more efforts are needed for the commercilaization of the diesel particulate filter.

• Journal of the Korea Institute of Military Science and Technology
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• v.10 no.3
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• pp.120-128
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• 2007

In order to reduce the lead-time and cost, the technology of rapid prototyping(RP) has been widely used. This paper describes the methodology to fabricate a large object by using the principle of rapid prototyping. By laminating thick and sloping polystyrene foam plates, we can make the large model which has three dimensional, continuous surfaces faster and easier than conventional processes. Estimated error was much smaller than other RP products which have stepped effect. For accuracy improvement and post processing, machined metal plates are added between the thick plates. To keep the continuity of surface and strengthen the model, pilot holes and guide rods are applied. By the methodology described in this paper, a missile body with flush air intake was fabricated.

• Applied Chemistry for Engineering
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• v.7 no.5
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• pp.813-822
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• 1996

In order to reduce carbon dioxide, one of the major greenhouse gases, a new type of copolymer, poly(alkylene carbonate) has been synthesized. The alternating copolymers have been obtained from carbon dioxide and various epoxides with zinc carboxylate as a catalyst. The number-average molecular weight of the polymer is about 50,000 and polydispersity is rather broad(5~10). The polymers are amorphous, and glass-clear materials that exhibit unusually facile and clean thermal decomposition behavior. Complete decomposition with no carbon residue is observed at elevated temperature even in an inert atmosphere. Terpolymers with bulkier epoxides improve the physical properties of the copolymer with simple epoxides. The decomposition properties of the polymer provide versatile applications such as ceramic, metal, and electronic binders and lost-foam casting. Further application of the polymer for the barrier film or the plasticizer will be investigated.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.18 no.1
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• pp.58-63
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• 2010

Introduction : Head trauma is the main cause of death in aircraft crash. In a Michigan study of structurally survivable, fatal accidents, 80% of the fatally injured had received head trauma. We tried to develop a new helmet for passengers, and perform its efficiency test. Methods : An aircraft helmet requires an excellent protection against head trauma, lightness, and small volumes. In addition, it must be wearable, fire resistant, and non toxic when it is burning. We developed two new helmets made from silicone foam which met all theses requirements. One was thin (2.5cm), and the other was thick (6.3cm). These looked like a motorcycle helmet and had only a soft silicone as liner material without an outer hard shell. Therefore we can carry them easily inside aircrafts. The standard test for helmet is Snell's drop test. It measures the impact acceleration of head shaped metal wearing helmet during we drop it at certain heights. Impact sites were total 5 sites (front, back, right, left and top) for each helmet. All these sites were impacted twice. Results : The thickness of impact sites varied from 2.5cm to 6.3cm. The impact acceleration of 2.5cm thickness site when it was dropped from 1.0 meter was 379g. But, that of 6.3cm thickness site when it was dropped from 1.5 meter was only 163g. Unfortunately, both helmets didn't meet the Snell Standard for motorcycle helmets. Discussion : If we add suitable outer hard shell, and change its thickness and design, the efficiency will be increased. A study indicated that helmet could reduce the risk of head trauma up to 85%. We made helmet for passengers in aircraft crash for the first time. If we improve its weak points, it will decrease the frequency of head trauma in aircraft craft.

• Clean Technology
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• v.20 no.3
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• pp.277-282
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• 2014

In this study, PU-LMO was made by immobilization of LMO on urethane foam (PU) with using an EVA as a binder. PU-LMO was characterized by using X-Ray Diffractometer (XRD) and Scanning Electron Microscopy (SEM). The optimal ratio of EVA/LMO for preparation of PU-LMO was 0.26 gEVA/gLMO. The adsorption of lithium ions by PU-LMO was found to follow the pseudo-second-order kinetic model. The equilibrium data fitted well with Langmuir isotherm model and the maximum removal capacity of lithium ions was 17.09 mg/g. The PU-LMO was found to have a remarkably high selectivity of lithium ions and high adsorption capacity because the distribution coefficient ($K_d$) of lithium ion was higher than those of other metal ions.

• Applied Biological Chemistry
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• v.39 no.4
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• pp.282-286
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• 1996

To effectively utilize fish skin gelatin as a material for quality improvement in surimi gel from fish with a red muscle, conger eel skin gelatin was modified with succinic anhydride, and funtional properties such as emulsifying activity and emulsifying stability were determined. The degree of chemical modification incresed up to 0.3 g of succinic anhydride/g of gelatin, above this adding ratio a nearly constant value was reached. The maximum amount of modification was about 90%. The emulsifying activity and emulsifying stability of gelatin gradually increased up to 89.8% of succinylation extent, little changed above of succinylation extent. The other functional properties as solubility, water holding capacity, foam expansion and foam stability were improved following succinylation with 0.3 g of succinic anhydride/g of gelatin. Amino acid composition of succinylated gelatin was similar to that of unmodified gelatin. Heavy metal contents such as cadmium, lead, copper and zinc of succinylated gelatin were lower than those of unmodified gelatin.