Activated magnetite (Fe3O4-δ) has the capability of decomposing CO2 proportional to the δ-value at comparativelylow temperature of 300oC. To enhance the CO2 decomposition capability of Fe3O4-δ, (Fe1-xCox)3O4-δ and (Fe1-xMnx)3O4-δ weresynthesized and then reacted with CO2. Fe1-xCoxC2O4·2H2O powders having Fe to Co mixing ratios of 9:1, 8:2, 7:3, 6:4, and5:5 were synthesized by co-precipitation of FeSO4·7H2O and CoSO4·7H2O solutions with a (NH4)2C2O4·H2O solution. The samemethod was used to synthesize Fe1-xMnxC2O4·2H2O powders having Fe to Mn mixing ratios of 9:1, 8:2, 7:3, 6:4, 5:5 with aMnSO4·4H2O solution. The thermal decomposition of synthesized Fe1-xCoxC2O4·2H2O and Fe1-xMnxC2O4·2H2O was analyzedin an Ar atmosphere with TG/DTA. The synthesized powders were heat-treated for 3 hours in an Ar atmosphere at 450oCto produce activated powders of (Fe1-xCox)3O4-δ and (Fe1-xMnx)3O4-δ. The activated powders were reacted with a mixed gas(Ar:85%, CO2:15%) at 300oC for 12 hours. The exhaust gas was analyzed for CO2 with a CO2 gas analyzer. The decom-position of CO2 was estimated by measuring CO2 content in the exhaust gas after the reaction with CO2. For (Fe1-xMnx)3O4-δ,the amount of Mn2+ oxidized to Mn3+ increased as x increased. The δ value and CO2 decomposition efficiency decreased asx increased. When the δ value was below 0.641, CO2 was not decomposed. For (Fe1-xCox)3O4-δ, the δ value and CO2decomposition efficiency increased as x increased. At a δ value of 0.857, an active state was maintained even after 12 hoursof reaction and the amount of decomposed CO2 was 52.844cm3 per 1g of (Fe0.5Co0.5)3O4-δ.

A general synthetic method to make Fe3O4-δ (activated magnetite) is the reduction of Fe3O4 by H2 atmosphere. However, this process has an explosion risk. Therefore, we studied the process of synthesis of Fe3O4-δ depending on heat-treatment conditions using FeC2O4·2H2O in Ar atmosphere. The thermal decomposition characteristics of FeC2O4·2H2O and the δ-value of Fe3O4-δ were analyzed with TG/DTA in Ar atmosphere. β-FeC2O4·2H2O was synthesized by precipitation method using FeSO4·7H2O and (NH4)2C2O4·H2O. The concentration of the solution was 0.1 M and the equivalent ratio was 1.0. β-FeC2O4·2H2O was decomposed to H2O and FeC2O4 from 150˚C to 200˚C. FeC2O4 was decomposed to CO, CO2, and Fe3O4 from 200˚C to 250˚C. Single phase Fe3O4 was formed by the decomposition of β-FeC2O4·2H2O in Ar atmosphere. However, Fe3C, Fe and Fe4N were formed as minor phases when β-FeC2O4·2H2O was decomposed in N2 atmosphere. Then, Fe3O4 was reduced to Fe3O4-δ by decomposion of CO. The reduction of Fe3O4 to Fe3O4-δ progressed from 320˚C to 400˚C; the reaction was exothermic. The degree of exothermal reaction was varied with heat treatment temperature, heating rate, Ar flow rate, and holding time. The δ-value of Fe3O4-δ was greatly influenced by the heat treatment temperature and the heating rate. However, Ar flow rate and holding time had a minor effect on δ-value.

Activated magnetite (Fe3O4-δ) was applied to reducing CO2 gas emissions to avoid greenhouse effects. Wet and dry methods were developed as a CO2 removal process. One of the typical dry methods is CO2 decomposition using activated magnetite (Fe3O4-δ). Generally, Fe3O4-δ is manufactured by reduction of Fe3O4 by H2 gas. This process has an explosion risk. Therefore, a non-explosive process to make Fe3O4-δ was studied using FeC2O4·2H2O and N2. FeSO4·7H2O and (NH4)2C2O4·H2O were used as starting materials. So, α-FeC2O4·2H2O was synthesized by precipitation method. During the calcination process, FeC2O4·2H2O was decomposed to Fe3O4, CO, and CO2. The specific surface area of the activated magnetite varied with the calcination temperature from 15.43 m2/g to 9.32 m2/g. The densities of FeC2O4·2H2O and Fe3O4 were 2.28 g/cm3 and 5.2 g/cm3, respectively. Also, the Fe3O4 was reduced to Fe3O4-δ by CO. From the TGA results in air of the specimen that was calcined at 450˚C for three hours in N2 atmosphere, the δ-value of Fe3O4-δ was estimated. The δ-value of Fe3O4-δ was 0.3170 when the sample was heat treated at 400˚C for 3 hours and 0.6583 when the sample was heat treated at 450˚C for 3 hours. Fe3O4-δ was oxidized to Fe3O4 when Fe3O4-δ was reacted with CO2 because CO2 is decomposed to C and O2.

최근 온라인 게임엔진이 개발되고 그에 따른 맵핑기법과 함께 그것을 표현할 수 있는 콘텐츠의 중요성을 높아지고 있다. 이런 용도로 활용될 수 있는 패턴 콘텐츠는 많은 경우 제목에 의존하여 검색, 관리되어 왔다. 콘텐츠로서 디자인을 명세할 때 키워드만을 사용하는 방법은 디자인의 중요한 정보들, 예를 들면 조형요소와 같은 정보를 누락시킬 수 있다는 점에서 제한적일 수밖에 없다. 더구나 게임 맵핑에서 필요로하는 추상 패턴과 같이 적절한 제목을 부여하기 힘든 이미지의 경우는 키워드 위주로 접근이 더욱 문제가 될 것이다. 본 논문은 기이러한 문제를 개선하기 위하여 조형이론에 근거한 이미지의 구조 요소를 위주로 명세하는 방법을 제안한다. 이를 통해 사용자는 이미지의 특성 요소를 시각적으로 확인할 수 있다. 이미지 명세와 더불어 본 연구에서는 패턴 이미지를 전용으로 등록, 검색할 수 있는 시스템을 구축함으로써 제안된 방법의 유용성을 확인한다.

The effect of the precipitator (NaOH, NH4OH) and the amount of the precipitator (150, 200, 250, 300 ml) on the formation of Fe3(PO4)2, which is the precursor used for cathode material LiFePO4 in Li-ion rechargeable batteries was investigated by the co-precipitation method. A pure precursor of olivine LiFePO4 was successfully prepared with coprecipitation from an aqueous solution containing trivalent iron ions. The acid solution was prepared by mixing 150 ml FeSO4(1M) and 100 ml H3PO4(1M). The concentration of the NaOH and NH4OH solution was 1 M. The reaction temperature (25˚C) and reaction time (30 min) were fixed. Nitrogen gas (500 ml/min) was flowed during the reaction to prevent oxidation of Fe2+. Single phase Fe3(PO4)2 was formed when 150, 200, 250 and 300 ml NaOH solutions were added and 150, 200 ml NH4OH solutions were added. However, Fe3(PO4)2 and NH4FePO4 were formed when 250 and 300 ml NH4OH was added. The morphology of the Fe3(PO4)2 changed according to the pH. Plate-like lenticular shaped Fe3(PO4)2 formed in the acidic solution below pH 5 and plate-like rhombus shaped Fe3(PO4)2 formed around pH 9. For the NH4OH, the pH value after 30 min reaction was higher with the same amount of additions of NaOH and NH4OH. It is believed that the formation mechanism of Fe3(PO4)2 is quite different between NaOH and NH4OH. Further investigation on this mechanism is needed. The prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and the pH value was measured by pH-Meter.

CGI(Computer-generated Image) 기술은 이미지 생성을 자동화한다는 측면에서 디자이너에게 도움을 줄 수 있다. CGI를 활용하는 과정에서 두 가지 중요한 활동은 이미지의 제작과 관리이다. 다양성을 추구하는 디자이너에게 추상이미지의 자동 생성과 같은 기법은 자유로운 형태의 이미지 획득에 많은 도움을 줄 수 있다. 이와 더불어 중요한 이슈는 방대한 분량의 이미지를 적절한 메커니즘을 통해 관리하는 것이다. 추상이미지는 특성상 이미지에 대응하는 검색어 설정이 어려우며, 분류 역시 까다로운 문제로 남아있다. 본 논문은 디자이너에게 친숙한 조형 요소와 감성 요소를 분류와 표현의 정보로 이용함으로써 자동 생산된 추상 이미지를 효과적으로 분류하고 표현하는 방법을 제안한다. 추상이미지에 대한 적절한 분류와 표현은 이미지 데이타베이스 구축 및 검색에 있어 간결하고 효과적인 기술로 활용할 수 있으며 대규모 컨텐츠 관리에 도움을 줄 수 있다.

CGI (Computer Generated Images) 기술은 컴퓨터에 의한 자동 이미지를 생성하고 활용하는 기술로, 컴퓨터 게임 및 맞춤형 그래픽스 응용에 활용이 기대되는 기술이다. 본 논문은 CGI 중 추상 이미지에 대해 감성 정보를 정의할 수 있는 체계를 제안하고, 이를 활용하는 저작 시스템을 설계한다. 감성정보를 표현하기 위해 본 논문은 XML 확장을 정의하여 CGI의 형태, 색채, 감성 정보를 표현하며, 검색 인터페이스를 설계하여 적절한 수준의 감성이미지 검색하여 새로운 이미지 저작에 활용할 수 있도록 한다. 감성이미지는 사용자 감성에 반응하는 맞춤형 컴퓨터 게임, 감성형 스크린세이버 등 다양한 감성 그래픽 응용에 활용될 수 있다.

The effect of ferrous/ferric molar ratio on the formation of nano-sized magnetite particles was investigated by a co-precipitation method. Ferrous sulfate and ferric sulfate were used as iron sources and sodium hydroxide was used as a precipitant. In this experiment, the variables were the ferrous/ferric molar ratio (1.0, 1.25, 2.5 and 5.0) and the equivalent ratio (0.10, 0.25, 0.50, 0.75, 1.0, 2.0 and 3.0), while the reaction temperature (25˚C) and reaction time (30 min.) were fixed. Argon gas was flowed during the reactions to prevent the Fe2+ from oxidizing in the air. Single-phase magnetite was synthesized when the equivalent ratio was above 2.0 with the ferrous/ferric molar ratios. However, goethite and magnetite were synthesized when the equivalent ratio was 1.0. The crystallinity of magnetite increased as the equivalent ratio increased up to 3.0. The crystallite size (5.6 to 11.6 nm), median particle size (15.4 to 19.5 nm), and saturation magnetization (43 to 71 emu.g-1) changed depending on the ferrous/ferric molar ratio. The highest saturation magnetization (71 emu.g-1) was obtained when the equivalent ratio was 3.0 and the ferrous/ferric molar ratio was 2.5.

The chemical formula of magnetite (Fe3O4) is FeO·Fe2O3, t magnetite being composed of divalent ferrous ion andtrivalent ferric ion. In this study, the influence of the coexistence of ferrous and ferric ion on the formation of iron oxide wasinvestigated. The effect of the co-precipitation parameters (equivalent ratio and reaction temperature) on the formation of ironoxide was investigated using ferric sulfate, ferrous sulfate and ammonia. The equivalent ratio was varied from 0.1 to 3.0 andthe reaction temperature was varied from 25 to 75. The concentration of the three starting solutions was 0.01mole. Jarosite wasformed when equivalent ratios were 0.1-0.25 and jarosite, goethite, magnetite were formed when equivalent ratios were 0.25-0.6. Single-phase magnetite was formed when the equivalent ratio was above 0.65. The crystallite size and median particle sizeof the magnetite decreased when the equivalent ratio was increased from 0.65 to 3.0. However, the crystallite size and medianparticle size of the magnetite increased when the reaction temperature was increased from 25oC to 75oC. When ferric and ferroussulfates were used together, the synthetic conditions to get single phase magnetite became simpler than when ferrous sulfatewas used alone because of the co-existence of Fe2+ and Fe3+ in the solution.

In this study, we investigated the unit process parameters in spherical kernel preparation. Nearly perfect spherical microspheres were obtained from the 0.6M of U-concentration in the broth solution, and the microstructure of the kernel appeared the good results in the calcining, reducing, and sintering processes. For good sphericity, high density, suitable microstructure, and no-crack final microspheres, the temperature control range in calcination process was , and the microstructure, the pore structure, and the density of kernel could be controlled in this temperature range. Also, the concentration changes of the ageing solution in aging step were not effective factor in the gelation of the liquid droplets, but the temperature change of the ageing solution was very sensitive for the final ADU gel particles

The effects of thermal treatment conditions on ADU (ammonium diuranate) prepared by SOL-GEL method, so-called GSP (Gel supported precipitation) process, were investigated for kernel preparation. In this study, ADU compound particles were calcined to particles in air and Ar atmospheres, and these particles were reduced and sintered in 4%-/Ar. During the thermal calcining treatment in air, ADU compound was slightly decomposed, and then converted to phases at . At , the phase appeared together with . After sintering of theses particles, the uranium oxide phases were reduced to a stoichiometric . As a result of the calcining treatment in Ar, more reduced-form of uranium oxide was observed than that treated in air atmosphere by XRD analysis. The final phases of these particles were estimated as a mixture of and .

A Fe(OH)2 suspension was prepared by mixing iron sulfate and a weak alkali ammonia solution. Following this, iron oxides were synthesized by passing pure oxygen through the suspension (oxidation). The effects of different reaction temperatures (30˚C, 50˚C, 70˚C) and equivalent ratios (0.1~10.0) on the formation of iron oxides were investigated. An equilibrium phase diagram was established by quantitative phase analysis of the iron oxides using the Rietveld method. The equilibrium phase diagram showed a large difference from the equilibrium phase diagram of Kiyama when the equivalent ratio was above 1, and single Fe3O4 phase only formed above an equivalent ratio 2 at all reaction temperatures. Kiyama synthesized iron oxide using iron sulfate and a strong alkali NaOH solution.

이온성 고분자에 비이온성 고분자를 섞어 이온 함량을 조절함으로써 다양한 전하량을 갖는 이온성 막을 제조하였다. 비이온성 고분자로는 폴리비닐알콜, 음이온성 고분자로는 알긴산 나트륨, 양이온성 고분자로는 키토산을 사용하였으며, 이들 이온성 고분자막을 사용하여 여러 전해질 수용액에 대한 투과 및 분리특성을 관찰하였다. 막 내부에 이온성 고분자 함량이 많을수록 친수성 특성을 보였으며, 순수투과 및 용액투과 속도가 증가함을 관찰할 수 있었고, 또한 투과속도는 막의 팽윤 거동에 의해 결정됨을 확인할 수 있었다. 용질 배제율의 경우는 막과 투과용질간의 정전기적 인력, 즉 Donnan exclusion에 의해 결정이 되며, 정전기적 인력이 비슷한 경우는 분자체 효과에 의해 분리됨이 관찰되었다.

분무건조법으로 용사용 원적외선 세라믹/알루미늄 복합분말을 제조하여 플라즈마 용사법으로 알루미늄 모재에 용사한 후, 미세구조, 결정상, 열충격저항성 그리고 분광복사율을 조사하였다. 분무건조된 복합분말의 입형은 구형으로 34~105μm . 영역에서 높은 복사율을 보였다. 그러나 알루미늄 첨가량이 증가할수록 원적외선 방사특성은 감소하였다. 결과적으로 용사법으로 원적외선 방사특성의 큰 손실 없이 방사체를 제조하기 위해서는 20~30%wt%Al를 첨가하여 복합분말을 제조하는 것이 가장 효율적이라고 판단된다.

20wt%NiCr이 크래드된 크롬카바이드 분말과 7wt%NiCr이 기계적으로 혼합된 크롬카바이드 분말을 이용하여 HVOF 용사된 용사층의 특성(미세조직, 결정상, 경도값 그리고 erosion rate)을 비교하였다. 용사상태의 미세조직강의 특성은 크래드분말의 경우에 primary Cr3C2상이 용사층에는 남아 있었으나 혼합분말의 경우에는 primary Cr3C2 상은 용사층에 거의존재하지 않았다. 또한 XRD 분석결과 두 분말 모두 용사과정에서 크롬카바이드의 분해는 일어났으나 분해율은 크래드분말의 경우가 혼합분말보다 낮았다. 용사상태에서 경도값은 혼합분말의 경우가 높았으며 1000˚C까지 열처리 후 혼합분말의 경도값은 1665까지 증가하였으나 크래드분말은 600˚C를 정점으로 감소하는 경향을 보였다.

수소를 연료로 하여 HVOF 용사된 크롬카바이드 용사층의 산화거동을 이해하기 위해 용사분말의 제조방법이 서로 다른 두 종류의 용사용 분말을 (Cr3C2-20wt%NiCr로 구성된 크래드 분말과 Cr3C2-7wt%NiCr로 구성된 혼합분말)이용하여 F/O비를 3.2, 3.0, 2.8 로 변화시켜 용사한 후, 1000˚C 까지 등온 산화실험 후, 산화특성을 고찰하여 크롬카바이드 용사층의 F/O비에 의존하는 산화거동을 비교 검토하였다. 그 결과 NiCr이 20wt% 크래드된 분말로 용사된 용사층과 NiCr이 7wt% 혼합된 분말로 용사된 용사층은 전혀 다른 산화거동을 보였다. 혼합분말의 경우에 1000˚C에서 50시간 등온산화실험 후, F/O=3.2의 조건인 경우에는 산화물이 표면 요철을 따라 비교적 균일하게 성장한 반면 F/O=3.0과 F/O=2.8의 경우에는 용사층 표면이 다공성의 산화물이 형성되었으며, 또한 Ni, Cr으로 이루어진 복합산화물인 oxide cluster로 성장하였다. 반면에 크래드 분말로 용사된 용사층의표면 산화물 층은 다공성을 변화되지 않았다. 이러한 용사분말의 제조방법에 따라 산화거동이 차이를 보이는 것은 용사 중에 발생하는 카바이드분해와 밀접한 관계가 있는 것으로 생각되며 또한 일반적으로 알려진 크롬카바이드 소결체 보다 산화율이 높았다. 이러한 결과로 볼 때, 환원성의 수소의 양에 따른 용사층의산화거동에 대해서도 연구가 필요할 것으로 생각된다.