MgTiO3에 CaTiO3, MgO, CaO를 첨가하여 고주파 유전특성을 조사하였다. 온도계수가 zeo ppm/˚C에 접근하는 (Mg0.915Ca0.085)TiO3 조성에서 유전상수값은 22, Qxf 값은 50000, MgO를 0.1mol 첨가한 조성에서는 유전상수는 17, Qxf값은 131000, CaO를 8mol% 첨가한 조성에서 유전상수는 20, Qxf 값은 52000을 나타내엇다. MgTiO3에 CaTiO3를 단독으로 첨가하는 경우보다 MgO와 CaO를 동시에 첨가할 때 보다 높은 Q값을 갖는 MgTiO3계 세라믹스를 제조할 수 있었다.

(Ba, Sr)TiO3계에 저융점의 Glass물질을 첨가하여 저온소결이 가능하며, 고유전율을 갖는 유전체 재료를 제조하여, 그 특성을 조사하였다. 본 연구에서는 고유전율의 (Ba, Sr)TiO3계에 PbO함량이 서로 다른 Glass물질을 첨가하여 조성변화에 따른 저온소결거동 및 유전특성을 조사하였으며, 적층형 세라믹 Capacitor(MLCC)에 응용하기 위하여 다양한 조성으로 제조하였다. PbO-ZnO-B2O2계 Glass 성분을 첨가하여 소결온도를 1350˚C에서 1050˚C까지 낮출수 있었으며, 4wt% glass 첨가로 1150˚C 이하에서 2시간 소결한 저온소결용 재료는 실온에서 8000정도의 높은 비유전율과 0.005의 낮은 유전손실 그리고 광역온도범위에서 유전상수의 안정성을 가진 우수한 특성을 나타내며, 입자크기가 1~3 μm 정도로 치밀한 미세구조를 가지고 있다. 본 연구의 저온소결용 유전체 재료는 Z5U 규격을 만족시키고 기존의 BaTiO3계 재료에 비해 낮은 소결온도를 가지므로 MLCC에 응용시 내부전극으로 Ag-Pd alloy 사용이 가능한 것으로 밝혀졌다.

A site 복합 페로브스카이트 구조인 (Na1/2 La1/2)TiO3 세라믹스의 고주파 유전특성을 조사하였다. 1000˚C에서 4시간 하소하고 1350˚ ~ 1450˚C에서 소결했을 때 치밀한 소결체가 되었다. NLT의 겉보기 밀도는 4.95g/cm3, 상대밀도는 96.4%였으며, 격자상수(a)가 3.873Å인 단순 입방정 구조였다. NLT의 유전율은 밀도가 높아짐에 따라 증가하였고 품진계수 Q는 평균 결정립 크기가 커짐에 따라 증가하였다. 1400˚C에서 4시간 소결한 NLT는 εr=125, Q=2842(fo=3 GHz), τf=465의 유전특성을 나타내었다.

Ozone concentrations in water and air, and resulting disinfective properties, were measured following generation by either an ozone generator or a low-temperature dielectric barrier discharge plasma generator. In freshwater, ozone concentrations of 0.81 and 0.48 mg/L O3 were observed after the ozone and plasma generators had been operated for five minutes, respectively. Higher levels of dissolved O3 were attained more easily with the ozone generator. In seawater, both systems were capable of creating concentrations greater than 3.00 mg/L O3 after 5minutes of operation. Higher ozone levels were attained more easily in seawater than in freshwater. Rates of bacterial sterilization in seawater after three minutes were 96% and 88%, using the plasma and ozone generators, respectively. In freshwater, higher concentrations of ozone were released into the atmosphere by the ozone generator than by the plasma generator. In creating equivalent levels of dissolved ozone in freshwater, the plasma generator released 4.5 times more ozone into the atmosphere than did the ozone generator. This shows that ozone generators are more effective than plasma generators for creating ozonated water. For the same concentration of dissolved ozone in seawater, more ozone was released into the atmosphere using the ozone generator than using the plasma generator. Therefore, with regard to air pollution, plasma generators seem to be less expensive than ozone generators.

We studied the ozone concentrations generated by low-temperature dielectric barrier discharge plasma reactor after adding air and phytoplankton to control the ozone concentrations in seawater. We also examined the numbers of bacteria and Vibrio spp. after treatment using the plasma reactor. As the airflow rate was increased, more ozone was removed. Although marked variation in the ozone decrease was observed with and without airflow, the rate of ozone removal did not increase proportionately with the airflow rates. The ozone concentration decreased with increasing organic matter and time. The amount of organic matter seems to be an important factor decreasing the dissolved ozone concentration in liquid. The ozone concentration was 0.07, 0.32, 1.28, and 2.3 mg/L when operating the plasma reactor for 30, 60, 180, and 300 s, respectively; i.e., the ozone concentration increased with the reactor operating time. The initial numbers of bacteria and Vibrio spp. were 800 and 480 CFU/mL, respectively. After operating the plasma reactor at a flow rate of 6 L/min for 30 s, no bacteria or Vibrio spp. were detected. The disinfection effect of this plasma reactor seems to be superior to that of a conventional ozone generator.