• Journal of the Korean Wood Science and Technology
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• 제21권3호
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• pp.30-36
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• 1993

Wood chips of oak (Quercus mongolica) and larch (Larix leptolepis) were treated with a relatively low pressure steam(10~20 kg/$cm^2$) for 10~20 min (first-stage),and then increased pressure up to 30kg/$cm^2$ for 30 second (second-stage), and steam pressure was released intentionally to air. Main components of exploded wood were separated with 1% NaOH and hot water-methanol. In this work, the more effective low pressure explosion condition and separation method of wood main component were investigated. The results can be summarized as follows; 1. The yields of exploded wood were generally decreased with increasing steam pressure and reaction time. 2. The proper condition of steam explosion in low pressure for the separation of wood main components was 15kg/$cm^2$-10 min, in oak wood and 20kg/$cm^2$-10 min., then 30kg/$cm^2$-0.5 min, in larch wood. 3. The 23% of elude hemicellulose was obtained from the exploded oak wood which was treated with optimal condition. 4. In the case of hot water-methanol extraction, the ratio of delignification was 14~23% in the exploded larch wood and 42~55% in the exploded oak wood. 5. The methanol was more effective than 1% sodium hydroxide solution for extraction of lignin from exploded wood.

• 한국컴퓨터정보학회논문지
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• 제13권5호
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• pp.163-170
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• 2008

컴포넌트에 대한 의존도 및 활용도가 증가하면서 컴포넌트의 보안성 강화를 위한 필요성이 증가하고 있다. 컴포넌트는 재사용을 통한 소프트웨어의 개발 생산성을 향상시키는 이점을 제공한다. 이러한 이점에도 불구하고 컴포넌트의 보안 취약성은 재사용에 제한을 한다. 이의 개선을 위해 컴포넌트의 보안성을 높이는 경우에 가장 문제가 되는 부분이 재사용성에 대한 제한이 확대된다는 것이다. 따라서 컴포넌트의 재사용성과 보안성을 동시에 고려하는 컴포넌트의 모델이 제공되어야 한다. 이의 해결책으로 정보은폐와 수정의 용이성을 제공하여 보안성과 재사용을 확대할 수 있도록 재사용 모델을 결합하고 포장 및 애스펙트 모델을 통합한 컴포넌트 재사용 확대를 위한 관심사의 분리보안 모델을 제안하고 응용시스템을 구축하여 모델의 적합성을 검증하였다. 이의 응용은 핵심 및 보안 관심사의 분리를 통한 컴포넌트 기능의 확장과 수정의 용이성을 제공함으로써 보안성을 높이는 동시에 재사용성을 확대한다.

• 한국물환경학회지
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• 제37권1호
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• pp.10-19
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• 2021

In the flotation process to remove microplastic (MP) particles, the attachment and separation efficiency is determined by the basic physicochemical characteristics of MP particles as well as bubbles. To evaluate the flotation characteristics of MP particles, we carried out a series of simulations using the population balance (PB) model. The initial attachment coefficient (αo) of MP particles was in the range of 0.2-0.275, and it was slightly lower than that of typical particles, such as clay, debris and algae particles, which exist in water bodies, αo, 0.3-0.4. The relative bubble number (RBN) attached to the surface of the typical number of bubbles was 0.30 and 0.32 for MP 30 ㎛ and MP 58 ㎛, respectively. In comparison, the RBN of larger MP particles (138 ㎛) was as high as 0.53. Furthermore, smaller microbubbles were required to separate properly or additional treatment needed to be applied to enhance collision and attachment efficiency since the flotation of MP particles was found to be difficult to treat as high-rate. As a result of comparing the removal rate (experimental value) of MP particles obtained from the batch-type flotation apparatus and the flotation removal rate (predicted value) of MP obtained through the PB model, the final particles by the particle size of MP overall except for the initial separation time area. With respect to the removal efficiency, the observed and predicted values were similar, and it was confirmed that the floating separation characteristics and evaluation of the MP particles through the PB model could be possible.

• 한국항행학회논문지
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• 제26권2호
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• pp.47-53
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• 2022

최근 국방 기술이 발달함에 따라 다양한 항공기 무장/장착물이 국내에서 개발되고 있다. 그 중에서 항공기 발사용 순항 유도무기(유도탄)는 다양한 시험을 통해서 신뢰성 및 안전성을 확보한 후 항공기에 장착할 수 있다. 항공기로부터 분리된 유도탄은 항공기와 충돌을 회피하기 위해서 지정된 시간에 날개의 구속을 해제하고, 지정된 방향으로 날개를 제어해야한다. 이를 확인하기 위해서 안전 분리 절차에 따라 MIL-STD-1760 신호를 제어하고, 구속해제 성능을 검증할 수 있는 점검 시스템이 필요하다. 특히, 점검 시스템은 구속해제를 위한 파이로 회로를 점검하는 기능과 MIL-STD-1760 신호를 제어해서 구동 성능을 점검하는 기능이 필요하다. 또한, 항공기로부터 분리된 환경을 유도탄에 모의할 수 있어야한다. 본 논문은 지상에서 유도탄에 장착된 파이로 회로 및 구동 성능을 안전 분리 절차에 따라 검증할 수 있는 점검 시스템을 제시하였고, 비행시험을 통해서 항공기로부터 정상적으로 분리되는 것을 확인할 수 있었다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.395-400
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• 2004

In most physical processes, the transfer function includes time-delay, and in the general distributed control system using computer network, there exists inherent time-delay caused by the spatial separation between controllers and actuators. This work deals with the synthesis of a discrete-time controller for a nonlinear system and proposes a new effective method to compensate the influence of input time-delay. The controller is synthesized by using input/output linearization. Under the circumstance that input time-delay exists, the system response has more overshoot and tends to diverge. For these reasons, the controller has to produce future input value that will be needed for the system. In order to calculate the future input value, some predictors are adopted. Using the discretization via Euler's method, numerical simulations about the Van der Pol system are performed to evaluate the performance of the proposed method.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.548-552
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• 2005

In most physical processes, the transfer function includes a time-delay, and in the general distributed control system using a computer network, an inherent time-delay exists due to the spatial separation between controllers and actuators. Under the circumstance where an input time-delay exits, the system response overshoots and tends to diverge. For this reasons described above, a controller design method is proposed for a discrete nonlinear system including input time-delay, which adopts the time-discretization using Taylor series. Controllers are synthesized using an input/output linearization method. Finally, several cases of the computer simulations were conducted, and the results validate the proposed methods.

• JSTS:Journal of Semiconductor Technology and Science
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• 제5권4호
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• pp.243-248
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• 2005

The UAV (Unmanned Aerial Vehicle) systems like unmanned autonomous helicopters are used in various missions of flight navigation and used to collect the environmental information of the surroundings. To realize the full functionalities of the UAV, the software part becomes a challenging problem. In this paper embedded real-time software architecture for unmanned autonomous helicopter is proposed that guarantee real-time performance of hard-real time tasks and re-configurability of soft-real time and non-real time tasks. The proposed software architecture has four layers: hardware, execution, service agent and remote user interface layer according to the reactiveness level for external events. In addition, the layered separation of concurrent tasks makes different kinds of mission reconfiguration possible in the system. An Unmanned autonomous helicopter system was implemented (Kyosho RC Helicopter) in our lab to test and evaluate the performance of the proposed system.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2007년도 추계학술대회 논문집
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• pp.333-336
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• 2007

This paper deals with assessment of potential interference between grounding electrodes using ETM(Electrolytic Tank Modeling) method. When a test current flowed through grounding electrode, potential rise was measured and analyzed using an electrolytic tank in real time. In order to analyze the potential interference between grounding electrodes, ETM method was studies. Potential interference between isolated grounding electrodes was evaluated as functions of the separation distance between grounding electrodes and the configuration of grounding electrode to be induced. It was found that the separation distance between grounding electrodes in reducing the potential interference was a major factor.

• 한국환경과학회지
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• 제9권6호
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• pp.517-522
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• 2000

Separation of strontium ion from synthetic seawater in the contained liquid membrane permeator with two micro-porous films was performed. The permeator consisted of a liquid membrane and two cells for aqueous solutions. The liquid membrane consisted of $D_2EHPA(di-2-ethylhexy1-phosphoric acid)$ and DCH18C6 (dicyclohexano-18-crown-6),diluted to 30 vol% with kerosine and was trapped between two micro-porous hydrophilic films. This liquid membrane separated two aqueous solutions, one of which was synthetic seawater and the other of which was the stripping solutions consisting of 1mol/L $H_2SO_4$ solution. The effects of various operating parameters on the extraction rate and equilibrium extraction ratio of strontium ion from synthetic seawater were experimentally examined. The addition of DCH18C6 to the $D_2EHPA$ solution caused synergy effect on the extraction of strontium ion. The permeator extracted strontium ion from synthetic seawater effectively with high membrane life time.

• 한국환경과학회지
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• 제10권6호
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• pp.401-405
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• 2001

For the purpose of developing a new process f3r the elimination of oil components from oily waste water, experimental researches using oil gelling agent were performed. The process is composed of three units, that is, decantator, gelling column and adsorption column. 10g of gelling agent in the gelling column could effectively absorb 15.65g of oil from ship washing waste water and 16.93g of oil from steel industry waste water. COD in waste waters dramatically diminished not in the gelling column but in the adsorption column. The .gelling is hindered by other organic components in waste water, and the optimum space time f3r the gelling column Is 20min. 1g of gelling agent absorbed 3.7-4.0g of oil from waste waters with 25 min in the batch operation.