The theoretical capacity of silicon-based anode materials is more than 10 times higher than the capacity of graphite, so silicon can be used as an alternative to graphite anode materials. However, silicon has a much higher contraction and expansion rate due to lithiation of the anode material during the charge and discharge processes, compared to graphite anode materials, resulting in the pulverization of silicon particles during repeated charge and discharge. To compensate for the above issues, there is a growing interest in SiOx materials with a silica or carbon coating to minimize the expansion of the silicon. In this study, spherical silica (SiO2) was synthesized using TEOS as a starting material for the fabrication of such SiOx through heating in a reduction atmosphere. SiOx powder was produced by adding PVA as a carbon source and inducing the reduction of silica by the carbothermal reduction method. The ratio of TEOS to distilled water, the stirring time, and the amount of PVA added were adjusted to induce size and morphology, resulting in uniform nanosized spherical silica particles. For the reduction of the spherical monodisperse silica particles, a nitrogen gas atmosphere mixed with 5 % hydrogen was applied, and oxygen atoms in the silica were selectively removed by the carbothermal reduction method. The produced SiOx powder was characterized by FE-SEM to examine the morphology and size changes of the particles, and XPS and FT-IR were used to examine the x value (O/Si ratio) of the synthesized SiOx.

YAG phosphor powders were fabricated by the atmospheric plasma spraying method with the spray-dried spherical YAG precursor. The YAG precursor slurry for the spray drying process was prepared by the PVA solution chemical processing utilizing a domestic easy-sintered aluminum oxide (Al2O3) powder as a seed. The homogenous and viscous slurry resulted in dense granules, not hollow or porous particles. The synthesized phosphor powders demonstrated a stable YAG phase, and excellent fluorescence properties of approximately 115% compared with commercial YAG:Ce3+ powder. The microstructure of the phosphor powder had a perfect spherical shape and an average particle s ize of a pprox imately 30 μm. As a r esult of t he PKG t est of t he YAG p hosphor p owder, t he s ynthesized phosphor powders exhibited an outstanding luminous intensity, and a peak wavelength was observed at 531 nm.

Infrared radiation (IR) refers to the region of the electromagnetic radiation spectrum where wavelengths range from about 700 nm to 1 mm. Any object with a temperature above absolute zero (0 K) radiates in the infrared region, and a material that transmits radiant energy in the range of 0.74 to 1.4 um is referred to as a near-infrared optical material. Germanatebased glass is attracting attention as a glass material for infrared optical lenses because of its simple manufacturing process. With the recent development of the glass molding press (GMP) process, thermal imaging cameras using oxide-based infrared lenses can be easily mass-produced, expanding their uses. To improve the mechanical and optical properties of commercial materials consisting of ternary systems, germanate-based heavy metal oxide glasses were prepared using a melt-cooling method. The fabricated samples were evaluated for thermal, structural, and optical properties using DSC, XRD, and XRF, respectively. To derive a composition with high glass stability for lens applications, ZnO and Sb2O3 were substituted at 0, 1, 2, 3, and 4 mol%. The glass with 1 mol% added Sb2O3 was confirmed to have the optimal conditions, with an optical transmittance of 80 % or more, a glass transition temperature of 660 °C, a refractive index of 1.810, and a Vickers hardness of 558. The possibility of its application as an alternative infrared lens material to existing commercial materials capable of GMP processing was confirmed.

YAG (Yttrium Aluminum Garnet, Y3Al5O12) has excellent plasma resistance and recently has been used as an alternative to Y2O3 as a chamber coating material in the semiconductor process. However, due to the presence of an impurity phase and difficulties in synthesis and densification, many studies on YAG are being conducted. In this study, YAG powder is synthesized by an organic-inorganic complex solution synthesis method using PVA polymer. The PVA solution is added to the sol in which the metal nitrate salts are dissolved, and the precursor is calcined into a porous and soft YAG powder. By controlling the molecular weight and the amount of PVA polymer, the effect on the particle size and particle shape of the synthesized YAG powder is evaluated. The sintering behavior of the YAG powder compact according to PVA type and grinding time is studied through an examination of its microstructure. Single phase YAG is synthesized at relatively low temperature of 1,000 ℃ and can be pulverized to sub-micron size by ball milling. In addition, sintered YAG with a relative density of about 98 % is obtained by sintering at 1,650 ℃.

Effective control of the heat generated from electronics and semiconductor devices requires a high thermal conductivity and a low thermal expansion coefficient appropriate for devices or modules. A method of reducing the thermal expansion coefficient of Cu has been suggested wherein a ceramic filler having a low thermal expansion coefficient is applied to Cu, which has high thermal conductivity. In this study, using pressureless sintering rather than costly pressure sintering, a polymer solution synthesis method was used to make nano-sized Cu powder for application to Cu matrix with an AlN filler. Due to the low sinterability, the sintered Cu prepared from commercial Cu powder included large pores inside the sintered bodies. A sintered Cu body with Zn, as a liquid phase sintering agent, was prepared by the polymer solution synthesis method for exclusion of pores, which affect thermal conductivity and thermal expansion. The pressureless sintered Cu bodies including Zn showed higher thermal conductivity (180 W/m·K) and lower thermal expansion coefficient (15.8×10−6/℃) than did the monolithic synthesized Cu sintered body.

In this work, ultra-fine calcium oxide (CaO) powder derived from eggshells is used as the starting material to synthesize mineral trioxide aggregate (MTA). The prepared CaO powder is confirmed to have an average particle size of 500 nm. MTAs are synthesized with three types of fine CaO-based powders, namely, tricalcium silicate (C3S), dicalcium silicate (C2S), and tricalcium aluminate (C3A). The synthesis behavior of C3S, C2S and C3A with ultra-fine CaO powder and the effects of C3A content and curing time on the properties of MTA are investigated. The characteristics of the synthesized MTA powders are examined by X-ray diffraction (XRD), field emission-scanning electron microscope (FE-SEM), and a universal testing machine (UTM). The microstructure and compressive strength characteristics of the synthesized MTA powders are strongly dependent on the C3A wt.% and curing time. Furthermore, MTA with 5 wt.% C3A is found to increase the compressive strength and shorten the curing time.

일본에서는 2000년 고준위방사성폐기물의 심층처분을 위한「특정방사성폐기물의 최종 처분에 관한 법률」을 제정하고 부지선정을 착수하였으나, 부지선정 절차에 참여를 원하는 지자체가 존재하지 않았다. 따라서, 일본 정부는 2015년 문헌조사 단계에 새로운 부지선정을 절차를 개발하고, 지자체의 공모를 촉진하고자 2017년 6월 28일 심층처분을 위한 전국규모 과학적 특성 지도를 발간하였다. 이 지도는 심층처분장 초기 혹은 개념단계에 고려되는 요건 및 기준 등을 제공하고 심층처분을 위한 적합성을 분석함으로써, 공공의 이해도 증진과 지자체와의 의견교환 등을 위해서 유용하게 활용되고 있다.

구상나무는 아고산대에 한정되어 생육하는 것으로 알려져 있는데 최근 국립공원 내에서 고사하는 개채가 많이 발견되고 개체 수 또한 줄어들고 있는 실정이다. 따라서 본 연구는 쇠퇴 현상을 보이고 있는 구상나무 군락의 토양 환경 특성 파악을 통하여 추후 국립공원 내 구상나무 군락의 보전방안 마련 및 관리를 위한 기초자료를 제공하고자 수행되었다. 국립공원 내 구상나무군락의 토양 환경 특성을 파악하기 위하여 소백산 비록봉(1지점), 덕유산 서봉(1지점), 향적봉(4지점) 그리고 지리산 노루목(1지점), 돼지평전(1지점), 반야봉(2지점), 벽소령(1지점), 세석평전(1지점), 영신봉(1지 점), 임걸령(1지점), 장터목(1지점), 제석봉(2지점)에 존재 하는 구상나무 군락을 조사 대상지로 선정하였다. 토양의 물리적 특성을 분석한 결과 평균 토심은 소백산에서 68cm, 덕유산에서 41cm 그리고 지리산에서 44cm로 나타났으며, 특히 지리산 돼지평전과 벽소령 지역 내 구상나무군락의 경우에는 10cm 이하로 매우 낮게 조사되어 매우 열악한 토양 환경을 보이고 있었다. 0~10cm 깊이에서 가비중 평균은 소백산에서 0.38g/㎤, 덕유산에서 0.48g/㎤, 지리산에서 0.62g/㎤로 분석되어 우리나라 산림토양(정진현 등, 2002) A층 평균 0.88g/㎤ 그리고 B층 평균 1.01g/㎤보다 낮은 수준을 보이고 있었으며, 토심이 깊어질수록 가비중은 증가하는 경향을 보이고 있었다. 토양 수분함량의 경우에는 0~10cm 깊이에서 평균 39.69%~47.57%로 나타났다. 토양의 화학적 특성을 분석한 결과 토양 산도(pH)는 소백산에서 평균 4.90, 덕유산에서 4.59 그리고 지리산에서 4.69로 우리나라 산림의 토양 산도(pH) A층 평균 5.48 그리고 B층 평균 5.52보다 매우 낮게 나타났다. 토양 내 유기물 함량은 소백산에서 평균 9.08%, 덕유산에서 12.92% 그리고 지리산에서 12.68%로 양호한 수준이었으며, 모든 조사 지점에서 우리나라 산림토양 내 A층 유기물 평균 4.49%, B층 평균 2.03% 보다도 높은 함량을 보이고 있었다. Miller and Donahue(1990)에 의하면 유기물은 토양 중 양이온 치환용량(C.E.C.)의 30~70%를 제 공하며 부식으로 인하여 양이온치환 입지가 제공되는 것으로 알려져 있는데, 본 연구대상지의 양이온 치환용량을 분석한 결과 유기물 함량이 상대적으로 높았던 덕유산과 지리산에서 각각 22.05cmolc･kg-1과 19.69cmolc･kg-1로 높게 나타났다. 그리고 유기물 함량이 상대적으로 낮았던 소백산에서 17.58cmolc･kg-1로 조사되었는데, 이는 우리나라 산림토양 내 A층 양이온 치환용량 평균 12.5cmolc･kg-1, B층 평균 10.7cmolc･kg-1 보다는 높은 수준을 보이고 있었다. 유기물과 밀접한 관계를 가지고 있는 전질소 함량의 경우에도 소백 산에서 평균 0.52%, 덕유산에서 0.58% 그리고 지리산에서 0.59%로 조사되어 우리나라 산림토양 내 A층 전질소 평균 0.19%, B층 평균 0.09% 보다도 높은 함량을 보이고 있었다. 치환성양이온 K+은 덕유산과 지리산 조사 지역에서 평균 0.20cmolc･kg-1로 조사되어 우리나라 산림토양 A층 평균 0.22cmolc･kg-1, B층 평균 0.21cmolc･kg-1과 유사한 수치를 보였으나, 소백산 구상나무림의 경우에는 0.10cmolc･kg-1으로 다소 낮은 수치를 보였다. 하지만 치환성 양이온 Na+, Ca2+, Mg2+의 경우에는 우리나라 산림토양과 비교하여 매우 낮은 수치를 보이고 있었으며, 김창환(2012)이 보고한 지리 산 국립공원 내 구상나무림의 토양 조사 결과와 비교하여도 다소 낮은 수준이었다. 따라서 본 조사 대상지인 지리산, 덕유산, 소백산 국립공원 내 구상나무 임분의 건전한 생육을 위해서는 토양 산도의 개선과 치환성 양이온 부족 문제에 대한 개선 대책이 필요할 것으로 판단된다.

In2O3 doped WO3 powders were prepared by a polymer solution route and their NO2 gas sensing properties were analyzed. The synthesized powders showed nano-sized particles with specific surface areas of 6.01~21.5 m2/g and the particle size and shape changed according to the content of In2O3. The gas sensors fabricated with the synthesized powders were tested at operating temperatures of 400~500 oC and 100~500 ppm concentrations of NO2 atmosphere. The particle size and In2O3 content affected on the initial sensor resistance in an air atmosphere. The highest sensitivity (8.57 at 500 oC), which was 1.77 higher than the sensor consisting of the pure WO3 sample, was measured in the 0.5 mol% In2O3 doping sample. In addition, the response time and recovery time were improved by the addition of In2O3.

Spherical-type zirconia granules are successfully fabricated by a spray-drying process using a water solvent slurry, and the change in the green density of the granule powder compacts is examined according to the organic polymers used. Two organic binders, polyvinyl alcohol (PVA) and 2-hydroxyethyl methacrylate (HEMA), which are dissolved in a water solvent and have different degrees of polymerization, are applied to the slurry with a plasticizer (polyethylene glycol). The granules employing a binder with a higher degree of polymerization (PVA) are not broken under a uniaxial press; consequently, they exhibit a poor green density of 2.4 g/cm3. In contrast, the granule powder compacts employing a binder with a lower degree of polymerization (HEMA) show a higher density of 2.6 g/cm3 with an increase in plasticizer content. The packing behavior of the granule powders for each organic polymer system is studied by examining the microstructure of the fracture surface at different applied pressures.

2ZrO2·P2O5 powder, which is not synthesized by solid reaction method, was successfully synthesized through PVA solution method. In this process, the firing temperature and the PVA content strongly affected the crystallization behavior and final particle size. A stable α-phase 2ZrO2·P2O5 was synthesized at a firing temperature of 1200 oC and holding time of 4 h. β-phase 2ZrO2·P2O5 was observed, with un-reacted ZrO2 phases, for firing temperatures lower than 1200 oC. In terms of the PVA content effect, the powder prepared with a PVA mixing ratio of 12:1 showed stable α-phase 2ZrO2·P2O5; however, the β-phase was found to co-exist at relatively higher PVA content. The synthesized α-phase 2ZrO2·P2O5 powder showed an average particle size of 100~250 nm and an average thermal expansion coefficient of −2.5 × 10−6/oC in the range of room temp. ~800 oC.

본 연구는 남해군 금산에 분포하고 있는 식생의 구조를 파악하기 위해 2014년과 2015년에 실시되었다. 본 연구 조사지의 식생을 식물사회학적 방법과 DCCA ordination으로 분석한 결과, 10개의 자연림(졸참나무군락, 개서어나무군 락, 신갈나무군락, 소나무군락, 곰솔군락, 소사나무군락, 굴참나무군락, 느티나무군락, 서어나무군락, 히어리군락)과 2개의 식재림(편백군락 및 삼나무군락)으로 구분되었다. 또한 복곡저수지 아래 계곡부에는 환경부지정 보호야생식물인 히어리가 아교목상으로 군락을 형성하고 있었으며, 복곡저수지 인근 천하저수지 위쪽 임도에서는 끈끈이주걱이 발견되 었다. 식재림을 제외한 전체 군락에서 나타난 중요치는 졸참나무가 가장 높았으며(45.7), 중요치가 높은 주요 종에 대한 흉고직경급을 분석한 결과 졸참나무, 신갈나무 및 개서어나무는 정규분포형을 나타내고 있어 현재의 우점도를 유지할 것으로 보인다. 연구대상지내 군락의 토양을 분석한 결과, 평균 토양 pH는 4.28∼4.76으로 나타났다. DCCA ordination 분석 결과, 졸참나무군락은 해발고와 상관없이 고르게 분포하는 것으로 나타났고, 곰솔군락 및 소나무군락은 다른 군락들 보다 해발고가 낮고 남사면에 주로 분포하였다.

A low thermal expansion ceramic, cordierite (2MgO·2Al2O3·5SiO2), was synthesized using pyrophyllite. Pyrophyllite usually consists of SiO2 and Al2O3, which are the main components of cordierite. MgCO3 and Al(OH)3 were added in various amounts to pyrophyllite and fired for synthesis and sintering. α-cordierite crystallized from 1000 oC with mixing of 20 wt% MgCO3 and 1.7 wt% Al(OH)3, and un-reacted cristobalite was also detected with the cordierite. As the temperature was increased to 1400 oC, the cordierite yield was gradually increased. Powder compacts of the synthesized cordierite were sintered between 1250 oC ~ 1400 oC; the sintered samples showed a low thermal expansion coefficient of 2.1 × 10−6/ oC and typical sintering behavior. It is anticipated that it will be possible to synthesize cordierite ceramics on a mass production scale using the mineral pyrophyllite.

사용후핵연료 최종처분을 위해 심층처분은 세계적으로 가장 선호되는 방법이다. 이를 위해 선진국들은 자국 여건에 가장 잘 부합되는 고유의 처분시스템 개발에 주력하고 있거나, 일부 확보하여 상용처분사업에 적용하 고 있다. 현재까지 알려진 대부분의 심층처분시스템은 공학적 및 천연방벽으로 구성된 다중방벽시스템이다. 이들 처분시스템은 수 천 년 ~ 수 십만 년 이상의 성능기간이 대하여 성능·안전성의 입증이 확인되어야 후속 상용처분사업에 적용 가능하다. 입증 현안과제들은 처분시스템의 상능·안전성 확보를 위해 수행되는 모든 행 위 즉, 조사, 분석, 해석, 평가, 설계, 건설, 운영 및 폐쇄에 이르는 전 과정에 있어서 추진 과정과 결과에 대한 실현 가능성과 실증에 필요한 내용들이 해당된다. 이를 위해 대부분의 선진국들은 자국내 분포하는 대표적인 선호암종 지역에서 지하연구시설(URL)을 건설하여 실증·시연프로그램을 수행하거나 완성단계에 있다. 이 과 정과 결과들은 후속되는 최종처분장 부지선정 과정에 평가기준으로 활용될 것이며, 최종처분시설의 성능·안 전성평가에 필수적으로 적용하게 된다. 지하연구시설은 또한 규제-일반대중-전문가 등 다양한 이해당사자들 로 하여금 심층처분의 안전성 수준에 대한 이해제고와 토론의 마당으로서 핵심적인 역할과 기능을 할 것으로 기대된다.

Since there had been the first human outbreak of novel influenza A/H1N1 in Mexico, it has become pandemic throughout the world. In the Republic of Korea, the first human case was on May, 2009 and National Veterinary Research and Quarantine Service (NVRQS) has started monitoring novel influenza A/H1N1 on domestic swine farms. The first positive case was detected on 14, Dec, 2009 and until now, we have had total 17 positive cases. From the first case, we did epidemiological investigation on introduction and transmission of virus to pigs. We have concluded that virus had been introduced from humans to pigs, possibly from October to November, 2009 in our country. There were direct and indirect factors including the vehicles transporting veterinary medicine, feed, etc. related to transmission of virus from farm to farm. However, breeding pigs seem to be extrinsic to transmitting factors. Upon the epidemiological investigation, the off-limits of visitors to farms and the disinfection is thought to be critical for blocking the introduction and transmission of novel influenza A/H1N1. In addition, collecting and analyzing the genetic informations of influenza virus is important for predicting and handling the new pandemic influenza in the future.

This paper describes an investigation of an outbreak of foot-and-mouth disease (FMD) in Republic of Korea in January 2010. In this paper, we investigated introduction to the index farm from overseas countries, transmission from index farm to other outbreak farms. The introduction factors were divided direct, indirect factors or airborne spread factor. Based on the epidemiological data, clinical information and other data, in these introduction factors, it was likely that outbreak of FMD in index farm was due to international goods or employees from overseas countries (including China). There were other suggested causes in index farm. But it was less likely that outbreak of FMD in index farm have occurred by other causes. The transmission factors from index farm to other farms were also divided direct, indirect factors or airborne spread factor. In these transmission factors it was possible to make assumptions from index farm to other outbreak farms that the FMD virus was transmitted through animal treatment, persons concerned and persons (who were) attended farmers’ assembly.