• Journal of Forest and Environmental Science
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• v.23 no.2
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• pp.119-122
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• 2007

Actually, about 45% of total costs for wastewater treatment in a papermaking mill is spent for sludge disposal and the cost of chemicals used to improve the dewaterability of sludge takes much part of it. In order to reduce sludge disposal cost and to improve the efficiency of sludge treatment, it is necessary to minimize the amount of water contained within the sludge and hence to improve the dewaterability of the sludge. The objective of this study was to elucidate the way of improving the dewaterability of sludge. Three types of wastewater from a tissue paper mill, a printing paper mill and a newsprint mill were used and two types of high molecular weight flocculants (anionic PAM and cationic PAM) were used to treat the wastewater. Dewaterability of sludge was evaluated by measuring floc strength.

• Proceedings of the Korea Information Processing Society Conference
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• 2014.11a
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• pp.449-452
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• 2014

최근 이동통신 사업자들은 All-IP 기반의 서비스를 개발하고 상용화하기 위해 힘쓰고 있다. 그 이유는 All-IP 기반의 서비스가 LTE의 넓은 대역폭을 사용하여 기존 서비스와는 현저한 차별성을 가지고 있기 때문이다. 음성통화를 LTE 기반으로 제공하는 VoLTE 서비스도 그 중의 하나로서 현재 이동통신 3사 모두 상용화하여 이 새로운 고음질 및 고화질 커뮤니케이션 서비스에 대해 마케팅을 벌이고 있다. 하지만 VoLTE 서비스는 보안에 대한 충분한 고려가 이루어지지 않은 상태로 상용화되었으며, VoLTE에서 사용되는 SIP(Session Initiation Protocol) 프로토콜을 악용한 여러 유형의 공격에 매우 취약하다. 본 논문에서는 VoLTE 서비스에 대한 보안 위협 중 가장 기본이 되는 스캐닝 공격에 대해 기술하고 이를 탐지할 수 있는 방안을 제시한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2018.10a
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• pp.37-38
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• 2018

자동차 시스템의 전자화로 자동차에서 소프트웨어가 차지하는 비중은 점차 증가하고 있다. 소프트웨어는 안전필수 시스템에서 중요한 위치를 차지하며, 소프트웨어의 오동작은 심각한 손실 또는 재난을 일으키는 원인이 될 수 있다. 최근 자동차 시스템은 자율주행차량을 목표로 하여 센서융합과 협조제어가 많아지고 있다. 센서와 협조제어 정보는 시스템의 자율화에 중요한 부분을 차지하지만 현재 산업구조에서는 관련 부분에 대한 검증이 쉽지 않다. 본 논문에서는 현재 상황에서 발생할 수 있는 현상들을 살펴보고 안전한 자동차 개발을 위해 우리가 나아가야 할 방향을 고찰한다.

• Journal of the Korean Wood Science and Technology
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• v.26 no.4
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• pp.86-91
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• 1998

The drainage was used to determine the specific filtration resistance for wood and non-wood fibers. The drainage rate is also affected by factors that can be changed on consistency, pressure drop across the mat, basis weight, additives, and viscosity. Recent development of theoretical studies in flow through porous media and filtration operation emphasize the urgent need for more accurate data for porosity and specific filtration resistance. This study was investigated to determine specific filtration resistance of Hw, Sw-BKP and Kenaf fiber by filtration experimental. Freeness levels selected were 150,250,and $350m\ell$ CSF. The average specific filtration resistance decreased as freeness increased and resistance of Sw-BKP was greater than that of Hw-BKP. The filtrate and porosity increased and specific filtration resistance decreased as particle size of fiber increased.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.33 no.3
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• pp.44-51
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• 2001

Sedimentation characteristics such as SS, $BOD_5$, COD removal efficiency of waste water in the toilet paper mill using milk carton were examined. Optimum dosage of coagulant, rapid mixing time and slow mixing time were determined by turbidity, SS, COD, $BOD_5$ and then equation for treatment efficiency was suggested. Mechanical strength of floc was determined by turbidity. For the coagulant, polyacrylamide (PAM) is more efficient for removing pollution than the aluminium sulfate. Effective mixing ratios of PAM and aluminum sulfate to remove pollution are 70:30 and 30:70. The lowest turbidity was showed when rapid mixing at 300 rpm after coagulant injection was applied. That which indicates the highest point of flocs mechanical strength.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.41 no.3
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• pp.13-21
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• 2009

Pulp and paper industry is a typical plant industry which usually consume lots of water and energy. Recently, environmental issues have become more important due to climate changes around the world, and reinforcement in the regulatory content in transfer and management of chemical material and that in environmental regulations for waste water and air. Paper industry is a source material recycle industry which recycle or reuse waste paper, recyclable wood, planned plantation or lumber from thinning and waste wood. Hence it can be said that paper industry is the representative industry for earth environment and of 21th century.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.40 no.1
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• pp.41-46
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• 2008

In this study, dewaterability, one of the important properties of wastewater sludge, was investigated using a simple capillary suction time (CST) measurement method. It turned out that one could use the results of CST to find optimum flocculants ratio to improve drainage in wastewater treatment for the printing paper, tissue paper, and newsprint paper mill. Since the optimum ratio of flocculants could be determined with the value of CST, COD removal efficiency could be improved and optimum floc strength could be achieved with precise ratio of flocculants. It was thus that using CST for determining the optimum ratio of flocculants could be economical by reducing the amount of flocculants. Dewaterability could be measured within several seconds using the values of CST in a precise way. The dewaterability could also be useful in investigating the optimum ratio of flocculants.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.127.1-127.1
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• 2013

Recent experimental evidence that fluorinated graphene creates local magnetic moments around F adatoms has not been supported by semilocal density-functional theory (DFT) calculations where the adsorption of an F adatom induces no magnetic moment in graphene. Here, we show that such an incorrect prediction of the nonmagnetic ground state is due to the self-interaction error inherent in semilocal exchange-correlation functionals. The present hybrid DFT calculation for an F adatom on graphene predicts not only a spin-polarized ground state with a spin moment of ${\sim}1{\mu}_B$, but also a long-range spin polarization caused by the bipartite nature of the graphene lattice as well as the induced spin polarization of the graphene states. The results provide support for the experimental observations of local magnetic moments in fluorinated graphene.

• The Journal of Korea Robotics Society
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• v.16 no.3
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• pp.245-249
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• 2021

In this paper, we present novel simulation contents for drone racing and autonomous flight of drone. With Depth camera and SLAM, we conducted mapping 3 dimensional environment through RTAB-map. The 3 dimensional map is represented by point cloud data. After that we recovered this data in Unreal Engine. This recovered raw data reflects real data that includes noise and outlier. Also we built drone racing contents like gate and obstacles for evaluating drone flight in Unreal Engine. Then we implemented both HITL and SITL by using AirSim which offers flight controller and ROS api. Finally we show autonomous flight of drone with ROS and AirSim. Drone can fly in real place and sensor property so drone experiences real flight even in the simulation world. Our simulation framework increases practicality than other common simulation that ignore real environment and sensor.

• IEMEK Journal of Embedded Systems and Applications
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• v.13 no.6
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• pp.279-288
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• 2018

As a result of the technological advances in the E / E system, automotive system can provide advanced functions for safety and comfort. In addition, mechanical systems is changed to the electronic system. And the systems perform cooperative functions through communication. So the E / E system becomes more complicated as the size of the system increases. In order to secure the safety of complicated E / E system, ISO26262 standard require that Freedom from Interference and Sufficient Independence be met. In this paper, we propose a software scheduling method that can guarantee the independence between decomposed components after software decomposition and software development of ASIL D level EPB (Electronic Parking Brake) system.