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곽준혁,최낙진,반태현,임연태,김재창,허증수,이덕동,Kwak Jun-Hyuk,Choi Nak-Jin,Bahn Tae-Hyun,Lim Yeon-Tae,Kim Jae-Chang,Huh Jeung-Soo,Lee Duk-Dong 한국군사과학기술학회 2004 한국군사과학기술학회지 Vol.7 No.2
Semiconductor thick film gas sensors based on tin oxide are fabricated and their gas response characteristics are examined for four simulant gases of chemical warfare agent (CWA)s. The sensing materials are prepared in three different sets. 1) The Pt or Pd $(1,\;2,\;3\;wt.\%)$ as catalyst is impregnated in the base material of $SnO_2$ by impregnation method.2) $Al_2O_3\;(0,\;4,\;12,\;20\;wt.\%),\;In_2O_3\;(1,\;2,\;3\;wt.\%),\;WO_3\;(1,\;2,\;3\;wt.\%),\;TiO_2\;(3,\;5,\;10\;wt.\%)$ or $SiO_2\;(3,\;5,\;10\;wt.\%)$ is added to $SnO_2$ by physical ball milling process. 3) ZnO $(1,\;2,\;3,\;4,\;5\;wt.\%)$ or $ZrO_2\;(1,\;3,\;5\;wt.\%)$ is added to $SnO_2$ by co-precipitation method. Surface morphology, particle size, and specific surface area of fabricated sensing films are performed by the SEM, XRD and BET respectively. Response characteristics are examined for simulant gases with temperature in the range 200 to $400^{\circ}C$, with different gas concentrations. These sensors have high sensitivities more than $50\%$ at 500ppb concentration for test gases and also have shown good repetition tests. Four sensing materials are selected with good sensitivity and stability and are fabricated as a sensor array A sensor array Identities among the four simulant gases through the principal component analysis (PCA). High sensitivity is acquired by using the semiconductor thick film gas sensors and four CWA gases are classified by using a sensor array through PCA.
곽준혁 ( Jun Hyuk Kwak ),오용성 ( Yong Sung Oh ) 한국산림과학회 2003 한국산림과학회지 Vol.92 No.2
The Korean hybrid poplar, Populus alba×glandulosa, was used as raw material for the making of particleboard (PB). Two types of PBs were manufactured with synthesized urea-formaldehyde resin using a 162℃ hot-press for 4 and 5 minutes with a 6 percent resin solids level on an ovendried particle weight basis. The PBs were tested for physical strength and dimensional stability properties using ASTM D 1037 procedures. The PB test results showed that physical strength and dimensional stability properties were not significantly different by PB type and press time. All PB panels exceeded the minimum strength requirement according to Korean Standard KS F 3104 for PB Type 8.0. The results indicated that Korean hybrid poplar is a suitable raw material for PB.
PVDF/ZnO Nanopillar 복합재료를 이용한 압전필름 스피커의 성능향상
곽준혁 ( Jun-hyuk Kwak ),허신 ( Shin Hur ) 한국센서학회 2016 센서학회지 Vol.25 No.6
In this study, we fabricated and evaluated the performance of film speaker using PVDF/ZnO NP composite structure. PVDF piezo-electric films were fabricated and characterized by XRD and SEM. ZnO nanopillars were prepared by hydrothermal synthesis on pre-pared PVDF piezoelectric films. We analyzed and tested the acoustic signal characteristics of the piezoelectric film. In order to fabricate an acoustic structure with a wide frequency range from low to high frequency, we have fabricated various types of film speakers and investigated the frequency characteristics. As a result, the fundamental piezoelectric properties of PVDF show that the piezoelectric con-stant due to ZnO NP increases. And the overall acoustic signal level is also increased by 10% or more. We investigated frequency gen-eration from 500 Hz to 10 KHz using different sizes with PVDF/ZnO NP composite film speaker.
최낙진 ( Nak Jin Choi ),반태현 ( Tae Hyun Ban ),곽준혁 ( Jun Hyuk Kwak ),임연태 ( Yeon Tae Lim ),주병수 ( Byung Su Joo ),김재창 ( Jae Chang Kim ),허증수 ( Jeung Soo Huh ),이덕동 ( Duk Dong Lee ) 한국센서학회 2004 센서학회지 Vol.13 No.3
N/A Thin film gas sensor based on tin oxide was fabricated and its characteristics were examined: Target gas is acetonitrile (CH₃CN) that is simulant gas of blood agent gas. Sensing materials are SnO₂, SnO₂/Pt, and (Sn/Pt)oxidation with thickness from 1000 Å to 3000 Å. Sensor was consisted of sensing electrode with interdigit (IDT) type in front side and a heater in back side. Its dimension was 7 x 10 x 0.6 mm². Fabricated sensor was measured as flow type and monitored real time using PC. The optimal sensing material for CH₃CN was {Sn(3000 Å)/Pt(30 Å)}oxidation and its sensitivity and operating temperature were 30%, 300℃ in CH₃CN₃ ppm.