We report on the efficient detection of NO gas by an all-oxide semiconductor p-n heterojunction diode structure comprised of n-type zinc oxide (ZnO) nanorods embedded in p-type copper oxide (CuO) thin film. The CuO thin film/ZnO nanorod heterostructure was fabricated by directly sputtering CuO thin film onto a vertically aligned ZnO nanorod array synthesized via a hydrothemal method. The transport behavior and NO gas sensing properties of the fabricated CuO thin film/ ZnO nanorod heterostructure were charcterized and revealed that the oxide semiconductor heterojunction exhibited a definite rectifying diode-like behavior at various temperatures ranging from room temperature to 250 oC. The NO gas sensing experiment indicated that the CuO thin film/ZnO nanorod heterostructure had a good sensing performance for the efficient detection of NO gas in the range of 2-14 ppm under the conditions of an applied bias of 2 V and a comparatively low operating temperature of 150 oC. The NO gas sensing process in the CuO/ZnO p-n heterostructure is discussed in terms of the electronic band structure.

Ultrafiltration membranes are capable of acting as barriers to bacteria, viruses, spores, pollens, colloidal suspensions, high molecular weight solutes, pathogens and pesticides. Pore structure characterization of these include through pore throat diameter, bubble point pore diameter, mean flow pore diameter, pore distribution and liquid permeability. Liquid Liquid Porometery is a novel technique for measuring pores in the Ultrafiltration range without any damage or rupture to the membrane. Liquid Liquid Porometer uses two immiscible & saturated wetting liquids. Pores are filled with first liquid and second liquid is pressurized to displace the first liquid and flow through the pores. The amount of liquid flowing out is measured. Second liquid flow rate and differential pressure are measured. Pore distributions are computed like those in Capillary Flow Porometer.

본 연구에서는 높은 제거성능을 가지는 분리막 개발하기 위해, 상전이법을 이용하여 이중구조의 중공사형 한외여과막을 제조하였다. 방사조건에서 에어갭, 내부응고제를 조절하여 중공사를 제조하였다. 분리막의 단면과 표면 모폴로지는 전계방출형주사현미경(FE-SEM)을 이용하여 관찰 할 수 있었으며, 수투과도와 제거성능 평가는 0.2cm2 의 테스트 모듈을 제작하여 각각 측정하였다. 50nm PS latex bead를 이용하여 분리막의 공칭공경을 측정하였다. 측정결과 50nm 이하의 공칭공경을 가지는 것을 확인 할 수 있었으며, 박테리아 제거성능은 log 6 이상의 높은 값을 나태내는 것을 확인하였다.

Poly(vinylidene chloride) (PVDC)-derived nanoporous carbons were prepared by various activation methods: heat-treatment under an inert atmosphere, steam activation, and potassium hydroxide (KOH) activation at 873, 1073, and 1273 K. The pore structures of PVDC-derived nanoporous carbons were characterized by the N2 adsorption technique at 77 K. Heat treatment in an inert atmosphere increased the specific surface area and micropore volume with elevating temperature, while the average micropore width near 0.65 nm was not significantly changed, reflecting the characteristic pore structure of ultramicroporous carbon. Steam activation for PVDC at 873 and 1073 K also yielded ultramicroporosity. On the other hand, the steam activated sample at 1273 K had a wider average micropore width of 1.48 nm, correlating with a supermicropore. The KOH activation increased the micropore volume with elevating temperature, which is accompanied by enlargement of the average micropore width from 0.67 to 1.12 nm. The average pore widths of KOH-activated samples were strongly governed by the activation temperature. We expect that these approaches can be utilized to simply control the porosity of PVDC-derived nanoporous carbons.

A nano-porous structure of tin oxide was prepared using an anodic oxidation process and the sample's electrochemical properties were evaluated for application as an anode in a rechargeable lithium battery. Microscopic images of the as-anodized sample indicated that it has a nano-porous structure with an average pore size of several tens of nanometers and a pore wall size of about 10 nanometers; the structural/compositional analyses proved that it is amorphous stannous oxide (SnO). The powder form of the as-anodized specimen was satisfactorily lithiated and delithiated as the anode in a lithium battery. Furthermore, it showed high initial reversible capacity and superior rate performance when compared to previous fabrication attempts. Its excellent electrode performance is probably due to the effective alleviation of strain arising from a cycling-induced large volume change and the short diffusion length of lithium through the nano-structured sample. To further enhance the rate performance, the attempt was made to create porous tin oxide film on copper substrate by anodizing the electrodeposited tin. Nevertheless, the full anodization of tin film on a copper substrate led to the mechanical disintegration of the anodic tin oxide, due most likely to the vigorous gas evolution and the surface oxidation of copper substrate. The adhesion of anodic tin oxide to the substrate, together with the initial reversibility and cycling stability, needs to be further improved for its application to high-power electrode materials in lithium batteries.

Mamestra brassicae nucleopolyhedrovirus-K1 (MabrNPV-K1) was isolated from naturally infected Mamestra brassicae (Lepidoptera: Noctuidae) larvae in Korea. Restriction endonuclease fragment analysis using EcoRI, PstI, and BamHI estimated that the total genome size of MabrNPV-K1 is about 150 Kb. The full genome sequences of MabrNPV-K1 were determined, analyzed and compared to those of other baculoviruses. The MabrNPV-K1 genome consisted of 152,471 bp and had an overall G + C contents of 39.90 %. Computer-assisted analysis predicted 159 open reading frames (ORFs) of 150 nucleotides or greater that showed minimal overlap. The gene content and arrangement in MabrNPV-K1 were most similar to those of Mamestra configurata nucleopolyhedrovirus-B (MacoNPV-B), including three polh, p10 and lef-8 gene homologues. The MabrNPV-K1 genome contains four homologous repeat regions (hr1,hr2,hr3,hr4) that account for 3.1% of the genome. The genomic positions of MabrNPV-K1 regions hr1– hr4 are conserved with the genomic positions of MacoNPV-B hr1–hr4. This indicates that the position of MabrNPV–K1 hrs is conserved with regard to both the upstream and downstream genes. Given that hrs share higher similarity within a virus strain than any hrs between species, this evidence further indicates that hrs play a fundamental role in viral life cycle and replication process appears to be tightly linked to functional conservation. The dot plot analysis, percent identity of the gene homologues and a phylogenetic analysis suggested that MabrNPV-K1 is a Group II NPV that is closely related to MacoNPV but with a distinct genomic organization.

The study was done to change the morphology and pore size of SBA-15 silica, and the characteristics of SBA-15 silica were investigated with TG-DSC, XRD, SEM, TEM and N2 adsorption-desorption under changing aging conditions. SBA-15 silica having a 2D-hexagonal structure was synthesized and confirmed by SEM and TEM. The structure of mesoporus silica SBA-15 showed a pore having regularly formed hexagonal structure and a passage having a cylindrical shape. This result is in good agreement with the pore forming in XRD and cylindrical shape of the structure in N2 adsorption-desorption isotherm. SBA-15 silica showed a large BET surface area of 603-698 m2/g, a pore volume of 0.673-0.926 cm3/g, a large pore diameter of 5.62-7.42 nm, and a thick pore wall of 3.31-4.37 nm. This result shows that as the aging temperature increases, the BET surface area, pore volume, and pore diameter increase but the pore wall thickness decreases. The BET surface areas in SM-2 and SM-3 are as large as 698 m2/g. However, SM-2 has a large surface area and forms a thick pore wall, when the aging temperature is 100˚C and is synthesized into stable mesoporous SBA-15 silica.

Titanium oxide(TiO2) 박막을 금속 알콕사이드 물질인 (Ti(OC3H7)4(titanium isopropoxide)를 이용하여 p-Si(100) 기판위에 상압 화학 기상 증착법으로 증착시켰다. (TiO2) 박막의 증착기구는 단순경 계층 이론으로 잘 설명되었으며, 화학반응 지배 기구 영역에서 겉보기 활성화 에너지는 18.2kcal/mol이었다. 증착된 박막은 250˚C이상에서 anatase상의 결정질 박막이었으며, 고온에서 열처리를 했을 경우에 rutile상으로 전이하였다. 박막의 상전이에는 열처리 온도외에도 열처리 시간과 박막의 두께가 영향을 미쳤다. 정전용량-전압특성을 조사해 본 결과 전형적인 MOS 다이오드구조의 특성을 보였으며, 비유전율 상수는 약 80정도였다. 제조한 (TiO2) 박막의 열처리 공정 후에는 정전용량이 감소하였으며, 첨가물을 사용한 박막은 열처리 전과 같았다. 이때 VFB는 -0.5 ~ 1.5V였다. 전기전도 특성을 알아보기 위하여 전류-전압특성을 조사하였으며 증착된 박막의 전도기구는 hopping mechanism이었다. 전기적 특성을 개선하기 위해서 후열처리 방법과 박막 증착시 Nb, Sr을 첨가하였으며, 모두 누설전류의 감소와 정전파괴전압의 증가를 가져왔다.

Electrohydrodynamic Atomization 급냉응고장치를 이용하여 고순도 실리콘 미세분말을 제조하여 투과전자현미경으로 미세조직과 그 응고상을 조사한 결과 직경이 60nm 이하인 분말에서 비장질상이 발견되었다. 비정질 실리콘의 원자구조를 분석하기 위하여 비정질 분말에서 얻은 전자회절 데이타를 이용하여 radial distribution function을 계산하여 해석한 결과, 실리콘의 결정구조인 다이아몬드 입방격자에서 발견되는 기본적 정사면체 배열이 비정질 실리콘의 2번째 근접원자간 거기까지 유지됨을 알 수 있었으며 이로부터 비정질 실리?이 단범위 규칙성을 갖는 tetrahedrally coordinated random network 원자배열로 이루어짐을 알았다.