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      • KCI우수등재
      • KCI등재

        버섯 폐배지와 고흡수성 폴리머를 이용한 인공경량 토양 개발

        박장우,박기병,이준석,이은영 한국폐기물자원순환학회 2013 한국폐기물자원순환학회지 Vol.30 No.7

        This study is about making artificial soil for wall greening using Spent Mushroom substrates (SMS) & Superabsorbent polymer (SAP). and developing new material for wall greening whilst monitoring the physico-chemistry & germination ability of the plant, plant growth and developmental condition of the artificial soil. It was found that the larger the particle size of the superabsorbent polymer the more absorption increased. This showed the plant’s germination rate in soil when Spent Mushroom substrates & Superabsorbent polymer (SAP) were mixed. In the Bermuda grass, the Artificial soil (SMS & SAP 0.5%) showed a 100% germination rate over a period exceeding 7 days compared to Peat-moss that showed a 94% germination rate. In the Kentucky blue grass, however, there was no difference between the Peat-moss and Artificial soil. When general perlite soil was compared with artificial soil in the chicory seed, the Artificial soil showed better results than the general perlite soil in length, leaf volume and fresh-weight. In the plant length, it showed an increase of over 105% (SAP 0.5% or more), 187% (SAP 1% or more). in the leaf volume, an increase of over 123% (SAP 0.5% or more), 145% (SAP 1% or more), in the fresh-weight an increase of over 130% (SAP 0.5% or more), 285% (SAP 1% or more). The artificial soil (SMS & SAP 1%) showed an excellent result in the plant growth and development. Thus, it was found that artificial soil using the SMS & SAP were the only suitable soil materials for wall greening hence suggesting that it could be used for the greening of a blighted area or desert and a variety of agriculture.

      • KCI등재

        제작 오차를 고려한 트랙터 캐빈의 구조 해석

        박장우 한국융합학회 2017 한국융합학회논문지 Vol.8 No.5

        트랙터는 각종 작물을 생산하는 농용작업 외에 건설작업, 임야작업, 가정용 등에 사용되는 다목적 작업차 량으로 경작용의 가래, 쟁기, 써레, 수확기 등을 견인하는 농업 작업에 없어서는 안 되는 필수 장비이다. 트랙터 운전 자의 작업공간인 캐빈은 트랙터가 전도되었을 때 운전자가 입게 될 피해를 최소화하고 운전자가 전락하여 상해를 입지 않도록 보호하여야 한다. 일반적으로 캐빈은 프레임과 판들의 용접으로 제작되기 때문에 용접상태에 따라 구 조물의 강성이 크게 영향을 받게 된다. 본 연구에서는 유한요소 해석을 이용하여 캐빈의 제작 시 예상되는 구조물의 용접 오차가 캐빈 구조물의 정적, 동적 강성에 미치는 영향을 파악하고, 캐빈의 강성을 확보하기 위한 방안을 제시 하고자 한다. A cabin of the agricultural tractor is designed to protect the driver from vibration transmitted due to the irregular ground and overturning of the tractor. The cabin is usually manufactured by welding frames and plates. Consequently, the welded state of the frame and plate affects the stiffness of the cabin structure. In this paper, the static and dynamic stiffness characteristics of the cabin are identified through finite element analysis and effects of the structure production error are investigated to insure the structural stiffness of the cabin.

      • KCI등재

        다중 사용자 간섭을 고려한 TH-BPSK UWB 통신 시스템의 정확한 BER 계산

        박장우,최용석,조경룡,Park, Jang-Woo,Choi, Yong-Seok,Cho, Kyung-Ryong 한국정보통신학회 2005 한국정보통신학회논문지 Vol.9 No.5

        다중 사용자 간섭을 고려한 BPSK 데이터 변조 방식을 갖는 초광대역(Ultra-Wide Bandwidth, UWB) 시간 도약(time hopping, TH) 다중 통신 시스템의 정확한 비트 오율(bit error rate: BER)을 계산하는 방법을 제시하였다. UWB-TH BPSK 신호는 약간의 수정을 통하여 기존의 DS-CDMA 신호와 유사함을 보였다. 또한 다중 사용자 간섭(multiple user interference, MUI)는 특성 함수 기법을 이용하여 정확하게 기술하였다. 이들을 바탕으로 TH-BPSK 다중 통신 시스템의 BER을 정확히 계산하였다. 또한, MUI에 대한 기존의 가우시안 근사에 비하여 상당히 정확한 결과를 얻을 수 있는 간단한 근사식을 함께 제시하였다. 본 논문에서 제시한 BER 계산식의 정확성 및 타당성은 시뮬레이션 결과와 비교함으로써 확인하였다. The bit error probability of UWB Time-Hopping(TH) multiple access communication systems combined with BPSK is calculated with a high accuracy including the multiple user interference(MUI). This paper finds that with some manipulations, the TH-BPSK UWB signal can be modified to the similar form of the DS-CDMA signal. The MUI in the system is explained by the characteristic function technique. Above two descriptions have been bases on the derivation of the exact BER expression of the system. We also propose the approximate expression for the BER, which has enough accuracy compared with the expression from the Gaussian approximation of the MUI. The comparison of the results from the proposed expressions with the simulation results gives the confirmation for the validity and accuracy of the proposed expressions.

      • KCI등재

        탄산칼슘과 남은 음식물을 활용한 버섯배지에서 느타리버섯 균사의 성장 효과

        박장우,박기병,문준혁,이준석,이은영 한국폐기물자원순환학회 2012 한국폐기물자원순환학회지 Vol.29 No.6

        This study is about a kind of organic waste, food waste, and was conducted by using an alternative medium for the cultivation of oyster mushrooms to examine applicability. The study investigated the cultivation characteristics for major cultivated varieties of oyster mushrooms and the growth characteristics within food waste mediums. In addition, NaCl desalinization of food waste is being pointed out as a problem when using the medium, therefore, the effects of the medium's composition were examined by using calcium carbonate. Calcium carbonate is used for desalinization of NaCl. This study investigated the use of a total of 6 cultivars of the oyster mushroom, the Suhan (PL.1), Chiak No. 5 (PL.2), Chiak No. 7 (PL.3), Samgu No. 5 (PL.4), Samgu No. 8 (PL.5), Jangan No. 5(PL.6). In terms of medium, the optimum growth of the mycelium of the oyster mushroom was observed in the PDA medium. The optimal culture conditions was pH 6.0 in Samgu No. 8 (PL. 5) and pH 5.5-6.6 in another cultivar. In terms of food waste, the mycelium’s growth were investigated and found insufficient in the bulk of cultivars. but Chiak No. 7 (PL.3) was superior to that of other cultivars relative to the mycelium’s growth. (Mycelium’s growth: Chiak No. 7 (PL.3) = Jangan No. 5 (PL.6) > Samgu No. 8 (PL.5) > Samgu No. 5 (PL.4) > Suhan (PL.1) > Chiak No. 5 (PL.2)). In the test of desalinization using Calcium carbonate, the early salt concentration was 4.3%. When treating the calcium carbonate (1 ~ 10%) in the food waste, a change of salt concentration less than 5% of the calcium carbonate could be observed. Also, when treating the calcium carbonate (1 ~ 10%, w/w) in the food waste medium, a great change of EC could not be observed either. Therefore, the addition of calcium carbonate to food waste does not affect the growth of the mushroom, thus we had to speculate about the possibility of using food waste in the cultivation of oyster mushrooms.

      • KCI등재

        Non-data Aided Timing Phase Recovery Scheme for Digital Equalizationof Chromatic Dispersion and Polarization Mode Dispersion

        박장우,정원주,박종선,김성철 한국광학회 2009 Current Optics and Photonics Vol.13 No.3

        In this paper we propose an electronic domain timing phase selection scheme for the optical communication systems suffering from inter-symbol-interference (ISI) distortion due to chromatic dispersion (CD) or polarization mode dispersion (PMD). In the presence of CD/PMD a proper timing phase selection is important for discrete time domain equalizers, since different timing phases produce different nonlinear ISI channels of different severity. The proposed timing phase recovery scheme based on dispersion minimization (DM) practically approximates the optimal minimum mean squared error (MMSE) timing phase without training signals which reduces overall throughput substantially, especially in time-varying channels such as PMD. The simulation results show that the proposed DM timing agrees with MMSE timing phase, under proper normalization of the received signals, for various dispersion and OSNR.

      • KCI등재

        Performance Analysis of Electrical MMSE Linear Equalizers in Optically Amplified OOK Systems

        박장우,정원주 한국광학회 2011 Current Optics and Photonics Vol.15 No.3

        We analyze the linear equalizers used in optically amplified on-off-keyed (OOK) systems to combat chromatic dispersion (CD) and polarization mode dispersion (PMD), and we derive the mathematical minimum mean squared error (MMSE) performance of these equalizers. Currently, the MMSE linear equalizer for optical OOK systems is obtained by simulations using adaptive approaches such as least mean squared (LMS) or constant modulus algorithm (CMA), but no theoretical studies on the optimal solutions for these equalizers have been performed. We model the optical OOK systems as square-law nonlinear channels and compute the MMSE equalizer coefficients directly from the estimated optical channel, signal power, and optical noise variance. The accuracy of the calculated MMSE equalizer coefficients and MMSE performance has been verified by simulations using adaptive algorithms.

      • Hot Carrier 현상에 의한 Bulk DTMOS의 RF성능 저하

        박장우,이병진,유종근,박종태,Park Jang-Woo,Lee Byoung-Jin,Yu Jong-Gun,Park Jong-Tae 대한전자공학회 2005 電子工學會論文誌-SD (Semiconductor and devices) Vol.42 No.2

        본 논문에서는bulk dynamic threshold voltage MOSFET(B-DTMOS)와 bulk MOSFET(B-MOS)에서 hot carrier 현상으로 인한 RF 성능 저하를 비교하였다. Normal 및 moderate 모드에서 B-DTMOS의 차단주파수 및 최소잡음지수의 열화가 B-MOS 소자 보다 심하지 않음을 알 수 있었다. 실험 견과로부터 hot carrier에 의한 RF 성능 저하가 DC 특성 열화 보다 심함을 알 수 있었다. 그리고 처음으로 hot carrier 현상으로 인한 B-DTMOS 소자의 RF 전력 특성 저하를 측정하였다. This paper reports the hot carrier induced RF performance degradation of bulk dynamic threshold voltage MOSFET (B-DTMOS) compared with bulk MOSFET (B-MOS). In the normal and moderate mode operations, the degradations of cut-off frequency $(f_{T})$ and minimum noise figure $(F_{min})$ of B-DTMOS are less significant than those of B-MOS devices. Our experimental results show that the RF performance degradation is more significant than the U performance degradation after hot carrier stressing. Also, the degradation characteristics of RF power Performance of B-DTMOS due to hot carrier effects are measured for the first time.

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