Ce3+-doped yttrium aluminum gallium garnet (YAGG:Ce3+), which is a green-emitting phosphor, was synthesizedby solid state reaction using α-phase or γ-phase of nano-sized Al2O3 as the Al source. The processing conditions and thechemical composition of phosphor for the maximum emission intensity were optimized on the basis of emission intensity undervacuum UV excitation. The optimum heating temperature for phosphor preparation was 1550oC. Photoluminescence propertiesof the synthesized phosphor were investigated in detail. From the excitation and emission spectra, it was confirmed that theYAGG:Ce3+ phosphors effectively absorb the vacuum UV of 120-200nm and emit green light positioned around 530nm. Thecrystalline phase of the alumina nanoparticles affected the particle size and the luminescence property of the synthesizedphosphors. Nano-sized γ-Al2O3 was more effective for the achievement of higher emission intensity than was nano-sized α-Al2O3. This discrepancy is considered to be because the diffusion of Al3+ into Y2O3 lattice is dependent on the crystalline phaseof Al2O3, which affects the phase transformation of YAGG:Ce3+ phosphors. The optimum chemical composition, having themaximum emission intensity, was (Y2.98Ce0.02)(Al2.8Ga1.8)O11.4 prepared with γ-Al2O3. On the other hand, the decay time of theYAGG:Ce3+ phosphors, irrespective of the crystalline phase of the nano-sized alumina source, was below 1 ms due to theallowed 5d→4f transition of the Ce3+ activator.

Red-emitting Eu3+-activated (Y0.95-xAlx)VO4 (0<x≤0.12) nanophosphors with the particle size of ~30nm and thehigh crystallinity have been successfully synthesized by a hydrothermal reaction. In the synthetic process, deionized water asa solvent and ethylene glycol as a capping agent were used. The crystalline phase, particle morphology, and thephotoluminescence properties of the excitation spectrum, emission intensity, color coordinates and decay time, of the prepared(Y0.95-xAlx)VO4:Eu3+ nanophosphors were compared with those of the YVO4:Eu3+. Under 147nm excitation, (Y0.95-xAlx)VO4nanophosphors showed strong red luminescence due to the 5D0-7F2 transition of Eu3+ at 619nm. The luminescence intensityof YVO4:Eu3+ enhanced with partial substitution of Al3+ for Y3+ and the maximum emission intensity was accomplished at theAl3+ content of 10mol%. By the addition of Al3+, decay time of the (Y,Al)VO4:Eu3+ nanophosphor was decreased in comparisonwith that of the YVO4:Eu3+ nanophosphor. Also, the substitution of Al3+ for Y3+ invited the improvement of color coordinatesdue to the increase of R/O ratio in emission intensity. For the formation of transparent layer, the red nanophosphors werefabricated to the paste with ethyl celluloses, anhydrous terpineol, ethanol and deionized water. By screen printing method, atransparent red phosphor layer was formed onto a glass substrate from the paste. The transparent red phosphor layer exhibitedthe red emission at 619nm under 147nm excitation and the transmittance of ~80% at 600nm.

The electrocatalytic characteristics of oxygen reduction reaction of the PtxM(1-x) (M = Co, Cu, Ni) supported on multi-walled carbon nanotubes (MWNTs) have been evaluated in a Polymer Electrolyte Membrane Fuel Cell (PEMFC). The PtxM(1-x)/MWNTs catalysts with a Pt : M atomic ratio of about 3 : 1 were synthesized and applied to the cathode of PEMFC. The crystalline structure and morphology images of the PtxM(1-x) particles were characterized by X-ray diffraction and transmission electron microscopy, respectively. The results showed that the crystalline structure of the Pt alloy particles in Pt/MWNTs and PtxM(1-x)/MWNTs catalysts are seen as FCC, and synthesized PtxM(1-x) crystals have lattice parameters smaller than the pure Pt crystal. According to the electrochemical surface area (ESA) calculated with cyclic voltammetry analysis, Pt0.77Co0.23/MWNTs catalyst has higher ESA than the other catalysts. The evaluation of a unit cell test using Pt/MWNTs or PtxM(1-x)/MWNTs as the cathode catalysts demonstrated higher cell performance than did a commercial Pt/C catalyst. Among the MWNTs-supported Pt and PtxM(1-x) (M = Co, Cu, Ni) catalysts, the Pt0.77Co0.23/MWNTs shows the highest performance with the cathode catalyst of PEMFC because they had the largest ESA.

For possible applications as luminescent materials for white-light emission using UV-LEDs, Ba2Mg(PO4)2:Eu2+ phosphors were prepared by a solid state reaction. The photoluminescence properties of the phosphor were investigated under ultraviolet ray (UV) excitation. The prepared phosphor powders were characterized to from a single phase of a monoclinic crystalline structure by a powder X-ray diffraction analysis. In the photoluminescence spectra, the Ba2Mg(PO4)2:Eu2+ phosphor showed an intense emission band centered at the 584 nm wavelength due to the f-d transition of the Eu2+ activator. The optimum concentration of Eu2+ activator in the Ba2Mg(PO4)2 host, indicating the maximum emission intensity under the excitation of a 395 nm wavelength, was 5 at%. In addition, it was confirmed that the Eu2+ ions are substituted at both Ba2+ sites in the Ba2Mg(PO4)2 crystal. On the other hand, the critical distance of energy transfer between Eu2+ ions in the Ba2Mg(PO4)2 host was evaluated to be approximately 19.3 A. With increasing temperature, the emission intensity of the Ba2Mg(PO4)2:Eu phosphor was considerably decreased and the central wavelength of the emission peak was shifted toward a short wavelength.

We have synthesized Eu3+-doped YVO4 phosphors by using a hydrothermal method and investigatedtheir luminescent properties. Aqueous solutions of Y2O3, V2O5, Eu2O3, and nitric acid with various pH valueswere used as the precursors. The crystallinity, surface condition, and emission characteristics were examinedusing XRD, FT-IR, and photo-excited spectrometer. Eu3+ incorporation followed by the efficient red emissionstrongly depends on the acidity of solution media. The emission intensity becomes stronger as the pH valuesincrease to 7 and then gradually decreases. This phenomenon might be related to the hydroxyl quenchingeffect, which is induced by surface bound OH- groups.

Eu3+-activated R3GaO6 (R=Y, Gd) phosphors were prepared in a conventional solid-state reactionand their optical properties were investigated. These compounds exhibit strong red emission under lightexcitation at 254nm. The emission spectra are dominated by peaks appearing around 610-630nm that areinduced by the electric dipole transition of 5D0→7F2 of Eu3+. In addition, the appropriate CIE (CommissionInternationale de l’clairage) chromaticity coordinates, (x=0.656, y=0.336) for Y3GaO6 and (x=0.655, y=0.334)for Gd3GaO6, become closer to the NTSC (National Television System Committee) standard values. With theoptimized activator concentrations, the maximum emission brightness is approximately 80% of Y2O3:Eu3+typical red-emitting phosphor with improved color purity under an excitation condition of 254nm.

According to progress rapidly digitalization, networked and mobilization of electronics industry, there are demands for being smaller, thinner, more light, and more efficient complex functions of electronic devices which are wireless devices, semi-conductors, packages and mobile devices. Therefore, the solder resist on a printed circuit board have been required with the high resolution and the eco-friendly materials in the surface treatments such as high heating process and coating process with electrolysis. In this study, the photoinitiator initiator and monomers of the solder resist were prepared with their contents for reducing the occurrence of the under-cut. We investigated the sample surface by UV/VIS spectrometer, FT-IR, OM after HASL and ENIG process. From our results, it is possible to get a high adhesion of resist with optimal contents between the photoinitiator initiator and monomers after surface treatments.

To investigate characterization of EMF(Electromagnetic Field) emission from VDT(Visual Display Terminal) in computer room, we were divided into 3 types of placement monitors which are 1) back side of monitor faced the ground(back view type), 2) arrangement of monitors was a line type(two sides type), and 3) disposition of monitors was s straight(horizontal line type). We also measured monitors classified types at the front, side and back by distance and evaluated by TCO(The Swedish Confederation of profession Employers) and MPR-2(Measure and Proof Radiation Board) guide line. Magnetic field emission level by the type of VDT, it was indicated that MF(Magnetic Field) level was below the backgrounds level when CRT moved away about 70~90cm, LCD moved away about 40~50cm. We evaluated MF emission level by the number of VDT, it did not show any relationship. Finally, estimated MF emission level by the placement of VDT, it was showed the MF level less than the background level, when VDT moved away 40~50cm in all dispositions with exception of 2 sites. Background level of case was higher than emitted from VDT, so that did not effect on MF level by distance. However, we find out that as distance increased, MF emission level decreased significantly in all cases. We measured MF emission level of one monitor and others (back and forth) monitor in line type. Below the background level when one monitor type moved away 70cm, others monitor type moved away 40cm. However, other monitor types affected MF level which is located back monitor. The data demonstrate that avoiding excessive MF exposure from VDT using computer room, to have a space between user and VDT at least 50㎝.

In this paper, exposure levels of electromagnetic field were measured in residential environments and from appliances. First, the measurements of residential environments were taken in central locations in bedroom, living room, and kitchen in each home. Both arithmetic and geometric mean of normal-power condition are higher than low-power condition (all electrical devices turned off/unplugged), and the background fields in homes show a geometric mean of about 0.022 uT. Second, we measured broadband magnetic fields of domestic appliances at various distances. The highest magnetic field is 44.3 uT from the microwave oven, and the lowest is 1.4 uT from the Kimchi Refrigerator. The magnitude of magnetic fields from appliances dropped off at a rate inversely proportional to distance, but the ratio of drop-off on Korean appliances is lower than US and UK

The present study investigated the hypothesis that a extremely low frequency magnetic field (ELF-MF) partially suppresses the synthesis of human growth hormone (HGH) in a group of 28 primary schoolchildren living nearby and 60 primary schoolchildren aged 12 years living far away from overhead transmission power lines from December 2003 to April 2004 in Seoul, Korea. The mean personal exposure levels of the primary schoolchildren living nearby overhead transmission power line were 0.37 μT, whereas the levels for the primary schoolchildren living away from overhead transmission power line was 0.05 μT. From simple analyses, the mean growth hormone levels in the primary schoolchildren living nearby were lower than away from overhead transmission power line, and statistically significant differences in the levels of the growth hormone (p = 0.0316), whereas not statistically significant differences in the levels of the growth hormone related to the distance from residence to power line less and more than 100 m by cut-off point (p = 0.4017). In conclusion, these results may indicate that urinary levels of nocturnal growth hormone are altered in primary schoolchildren exposed to extremely low frequency magnetic field at overhead transmission power line.

Electromagnetic fields of all frequencies represent one of the most common and fastest growing environmental influences, about which anxiety and speculation are spreading. All populations are now exposed to varying degrees of electromagnetic field, and the levels will continue to increase as technology advances. The objectives of this study were to measure and analyze emitting characteristics of extremely low frequency electromagnetic field at micro-environments. We measured magnetic field at microenvironments such as home, school, educational institute, internet pc game room for children attending the primary school. The range of time weighted average (TWA) of 60 Hz EMF in micro-environment were 0.26∼ 7.62 mG and the highest TWA 7.62 mG was measured in PC room possessed more than 50 computers. We will measure personal exposure levels of primary students and analyze correlation between major micro-environments and personal exposure level.

기판온도 320˚C에서 알루미나 기판 위에 형성한 NTC 써미스터용 Mn-Ni계 산화물 박막의 산소가스 농도 변화와 막 형성 후 열처리에 따른 미세구조, 결정상 비저항, B정수 변화에 관하여 연구하였다. 미세구조는 주상 구조(columnar structure)를 지녔으며 열처리 온도가 증가함에 따라 700˚C 부근에서 등축 결정립 (equiaxed grain) 형태의 미세구조로 바뀌기 시작하였다. 박막의 결정상은 대부분 입방 스피넬 (cubic spinel) 상과 입방 Mn2O3, 상이 공존하였으며 산소농도 0.16%~0.7%의 경우 800˚C에서 열처리하였을 때 입방 스피넬 상만이 존재하였다. 분위기 산소의 농도가 증가함에 따라 비저항과 B정수도 급격하게 감소하다가 다소 증가하였으며, 600˚C-700˚C 로 열처리할 경우 이 값들이 대체로 낮고 안정된 특성을 보였다.

RF magnetron sputter로 알루미나 기판 위에 증착한 NTC 써미스터용 Mn-Ni계 산화물 박막의 기판온도 변화와 열처리에 따른 미세구조, 결정상, 비저항, B정수 변화에 관하여 연구하였다. 미세구조는 178˚C이하에서 증착한 막의 경우 fibrous microcrystalline이었고, 320˚C와 400˚C에서는 columnar grain 구조로 바뀌었다. 또한, 900˚C에서 열처리한 박막의 경우 equiaxed grain 형태의 미세구조를 나타내었다. 박막의 결정상은 대부분 입방 스피넬(cubic spinel)상과 Mn2O3 상이 공존하였고, 400˚C에서 증착한 경우 700˚C이상에서 열처리하면 입방 스피넬의 단상으로 바뀌었다. 기판온도가 증가함에 따라 비저항과 B정수도 급격하게 감소하였으며, 600˚C~700˚C로 열처리할 경우 이 값들이 대체로 낮고 안정된 특성을 보였다. 본 연구의 박막 시편들은 모두 NTC 써미스터의 특성을 나타내었다.

콩 모자이크 바이러스계통 SMV-G7의 감염에 의하여 모자이크 병징이 나타나는 함안 품종과 괴저병징이 나타나는 광교를 공시하여 (99평)의 포장 중앙 (1평)에 함안을 파종, 접종한 후 주변 시험구(1평씩 99구)에는 광교를 파종하여 SMV의 발생생태를 조사하였다. 광교에서 SMV 이병주율은 7월 13일에 가장 심하였고 황색수반으로 채집한 진딧물 밀도는 6월 22일에 가장 높게 나타났으며 함안과 인접한 시험구의 SMV 이병주율은 평균 , 포장전체의 이병주율은 평균 로 나타났다. 풍향과 바이러스 이병율을 분석한 결과 SMV의 전파는 바람부는 쪽으로 일정한 gradient를 형성하여 SMV 전파에 중요한 요인으로 나타났다

1981년 전북고창, 전남영광, 경북달성, 경남진양 지역에서 참깨병해의 발생과 피해를 조사한 결과 참깨역병의 피해가 가장 심하였다. 참깨역병의 발생은 포장에 따라 차이가 컸으며 발병이 심한 포장에서는 발병주율이 나 되었다. 참깨역병을 일으키는 병원균 Phytophthora spp.는 유주자낭의 형태적특성과 참깨에 대한 특이적인 병원성에 의하여 Phytophthora nocitianae var. parasitica (Dastur) Waterhouse로 동정되었다. 참깨역병의 병징은 줄기가 암갈색으로 변색, 부패되어 식물체가 도태고사하는 특징을 보였다.

A sequential planting method was developed to identify durable blast resistance in Korean rice cultivars. Two types of rice cultivars were investigated by a sequential planting after inoculation of mixed 26 rice blast isolates. Daesanbyeo and Gihobyeo, sh