은수원사시나무와 저밀도 폴리에틸렌으로 제조된 목질플라스틱패널의 성능

곽준혁,오용성 한국목재공학회 2004 목재공학 Vol.32 No.1

은수원사시나무 파티클과 저밀도 폴리에틸렌을 50:50, 60:40, 70:30의 3종류 혼합비율로 열압온도 145℃와 열압시간 5분에서 목질플라스틱패널을 제조하였다. 본 연구에서 목질플라스틱패널을 제조하는데 왁스와 접착제 등 어떤 첨가제도 사용하지 않았다. 제조한 목질플라스틱패널의 밀도, 박리강도, 휨탄성계수, 휨파괴계수, 두께팽창률 및 물흡수율에 대한 성질을 측정하여 패널의 성능을 평가하였다. 성능평가한 data를 SAS programing package에 의해 통계분석한 결과에 의하면 목질플라스틱패널의 박리강도, 휨파괴계수 등의 성질은 목재/폴리에틸렌 혼합비율이 50:50으로 제조된 패널이 다른 혼합비율인 60:40과 70:30으로 제조된 패널보다 5% 수준에서 높게 나타났다. 목질플라스틱패널의 치수안정화를 기준으로 볼 때, 목재/폴리에틸렌 최적의 혼합 비율이 60:40이라는 결과를 보여줬다. Wood/polyethylene panels were manufactured from Populus alba × glandulosa particles and low density polyethylene particles at three mixing rates, 50:50, 60:40, and 70:30. A total of 15 wood/polyethylene panels was made at 145 C and 5 minutes hot-press time. Wood/polyethylene panels were tested for internal bond, bending, and dimensional stabilities such as thickness swell and water absorption. Panel performance data were analyzed using the SAS programing package. The test results of the wood/polyethylene panels showed that as the polyethylene mixing rates were increased, the panel property values increased Based on panels' dimensional stabilities, the optimum wood/polyethylene mixing ratio appeared to be 60:40.

증량된 요소수지 접착제와 소나무 간벌재로 제조된 파티클보드의 성질

오용성,곽준혁 한국목재공학회 2003 목재공학 Vol.31 No.1

증량제로서 카제인과 콩을 첨가한 요소수지 접착제와 소나무 간벌재 파티클로 실험실 파티클보드를 제조하였다. 소나무 간벌재 파티클로 제조된 파티클보드를 성능 평가한 결과 소나무 간벌재는 파티클보드의 원료로서 적합하다. 증량된 요소수지로 접착된 파티클보드는 증량제의 첨가량이 증가함에 따라 기계적인 성능은 감소하는 경향이었다. 그러나 요소수지 접착제의 고형분량에 대해 카제인은 15%까지 콩은 20%까지 첨가하여 파티클보드 제조에 사용할 수 있다. Particleboards (PBs) were made from pinus densiflora thinning particle with urea-formaldehyde (UF) resin added casein and soybean as extender. The performance test results of the PB made showed that Pinus densiflora thinning log was suitable raw material for PB. As the extender addition in the UF resin was increased, the mechanical performance of the PB, bonded with the extended UF resin, were significantly decreased. However, casein and soybean can be used up to 15% and 20% of the UF resin solids resectively.

폐목재로 제조된 파티클보드의 성능평가

오용성,차재경,곽준혁 한국목재공학회 2002 목재공학 Vol.30 No.4

현재 폐목재의 발생량은 국내의 연간 목재사용량의 40% 정도의 수준으로 국내의 목재자급율을 고려해볼 때, 목재패널산업에서의 이런 폐목재의 재활용은 많이 장려되어야 한다. 본 연구는 폐목재로부터 얻어진 파티클과 실험실에서 합성한 요소수지를 폐목재파티클의 전건무게에 대해 6% 첨가하여 열압온도 162℃와 열압시간 5분에서 파티클보드를 제조하고 ASTM D 1037 방법에 의해 파티클보드의 성능을 평가하였다. 파티클보드의 성능을 평가한 결과는 KS F 3104 파티클보드 8.0형의 최소요구를 만족시키는 것이다. 이런 파티클보드의 성능평가 결과는 폐목재가 파티클보드의 원료로 적합하다는 것을 보여준다. The generation of wastewood is currently about 40% level of the amount of domestic wood use. When the rate of wood self-supply is considered, the recycling of wastewood in wood panel products industry should be encouraged. This study was evaluated the performance of particleboard (PB) made from wastewood. PBs were manufactured with the synthesized urea-formaldehyde resin at 5 minutes hot-press time, and at 162℃ press temperature with 6 percent resin solids level on an ovendry wastewood particle weight basis. The PBs were tested by the procedure of ASTM D 1037. Test results exceeded the minimum strength requirement according to KS F 3104 Particleboard type 8.0. The PB's performance showed that wastewood is suitable raw material for PB.

Fabrication of Si₃N₄-Based Artificial Basilar Membrane with ZnO Nanopillar Using MEMS Process

Kwak, Jun-Hyuk,Jung, Youngdo,Song, Kyungjun,Hur, Shin Hindawi Limited 2017 Journal of sensors Vol.2017 No.-

<P>This paper presents the fabrication of Si3N4-based artificial basilar membrane (ABM) with ZnO nanopillar array. Structure of ABMs is composed of the logarithmically varying membrane fabricated by MEMS process and piezonanopillar array grown on the Si3N4-based membrane by hydrothermal method. We fabricate the bottom substrate containing Si3N4-based membrane for inducing the resonant motions from the sound wave and the top substrates of electrodes for acquiring electric signals. In addition, the bonding process of the top and bottom substrate is performed to build ABM device. Depending on sound wave input of the specific frequency, specific location of the ABM produces a resonant behavior. Then a local deformation of the piezonanopillar array produces an electric signal between top and bottom electrode. As experimental results of the fabricated ABM, the measured resonant frequencies are 2.34 kHz, 3.97 kHz, and 8.80 kHz and the produced electrical voltages on each resonant frequency are 794 nV, 398 nV, and 89 nV. Thus, this fabricated ABM device shows the possibility of being a biomimetic acoustic device.</P>

Performance Test and Evaluations of a MEMS Microphone for the Hearing Impaired

( Jun Hyuk Kwak ),( Han Mi Kang ),( Young Hwa Lee ),( Young Do Jung ),( Jin Hwan Kim ),( Shin Hur ) 한국센서학회 2014 센서학회지 Vol.23 No.5

In this study, a MEMS microphone that uses Si3N4 as the vibration membrane was produced for application as an auditory device using a sound visualization technique (sound visualization) for the hearing impaired. Two sheets of 6-inch silicon wafer were each fabricated into a vibration membrane and back plate, after which, wafer bonding was performed. A certain amount of charge was created between the bonded vibration membrane and the back plate electrodes, and a MEMS microphone that functioned through the capacitive method that uses change in such charge was fabricated. In order to evaluate the characteristics of the prepared MEMS microphone, the frequency flatness, frequency response, properties of phase between samples, and directivity according to the direction of sound source were analyzed. The MEMS microphone showed excellent flatness per frequency in the audio frequency (100 Hz-10 kHz) and a high response of at least -42 dB (sound pressure level). Further, a stable differential phase between the samples of within -3 dB was observed between 100 Hz-6 kHz. In particular, excellent omnidirectional properties were demonstrated in the frequency range of 125 Hz-4 kHz.

Design of the Impedance tube for Underwater Sound Absorber with Metamaterial

Jun-Hyuk Kwak,Jong Jin Park,Kyung-Shik Kim,Kyungjun Song,Hakjoo Lee 한국소음진동공학회 2018 한국소음진동공학회 학술대회논문집 Vol.2018 No.4

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.

파티클보드의 원료로서 은수원사시나무의 평가

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.

Disturbance Observer Based Adaptive Integral Sliding Mode Control of High-DOF Robot

Jun-Hyuk Kim(김준혁),Gunpyung Kwak(곽군평),SeungKyu Park(박승규) 대한전기학회 2020 대한전기학회 학술대회 논문집 Vol.2020 No.7

Melanocortins induce interleukin 6 gene expression and secretion through melanocortin receptors 2 and 5 in 3T3-L1 adipocytes

Jun, Dong-Jae,Na, Kyung-Yoon,Kim, Wanil,Kwak, Dongoh,Kwon, Eun-Jeong,Yoon, Jong Hyuk,Yea, Kyungmoo,Lee, Hyeongji,Kim, Jaeyoon,Suh, Pann-Gill,Ryu, Sung Ho,Kim, Kyong-Tai Society for Endocrinology 2010 Journal of molecular endocrinology Vol.44 No.3

<P>Interleukin 6 (IL6) is a pleiotropic cytokine that not only affects the immune system, but also plays an active role in many physiological events in various organs. Notably, 35% of systemic IL6 originates from adipose tissues under noninflammatory conditions. Here, we describe a previously unknown function of melanocortins in regulating <I>Il6</I> gene expression and production in 3T3-L1 adipocytes through membrane receptors which are called melanocortin receptors (MCRs). Of the five MCRs that have been cloned, MC2R and MC5R are expressed during adipocyte differentiation. α-Melanocyte-stimulating hormone (α-MSH) or ACTH treatment of 3T3-L1 adipocytes induces <I>Il6</I> gene expression and production in a time- and concentration-dependent manner via various signaling pathways including the protein kinase A, p38 mitogen-activated protein kinase, cJun N-terminal kinase, and IκB kinase pathways. Specific inhibition of MC2R and MC5R expression with short interfering <I>Mc2r</I> and <I>Mc5r</I> RNAs significantly attenuated the α-MSH-induced increase of intracellular cAMP and both the level of <I>Il6</I> mRNA and secretion of IL6 in 3T3-L1 adipocytes. Finally, when injected into mouse tail vein, α-MSH dramatically increased the <I>Il6</I> transcript levels in epididymal fat pads. These results suggest that α-MSH in addition to ACTH may function as a regulator of inflammation by regulating cytokine production.</P>