• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.43.4-43
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• 2001

This paper deals with motion identification using artificial neural network (ANN) and its application to automatic ship berthing. As ship motions are expressed by multi-term non-linear model, it is very difficult to find optimal methods for automatic ship berthing especially under environmental disturbances. In this paper, metier identification was used to estimate the effect of environmental disturbances and then the differences between values of identification and state variables are used to estimate the effect of environmental disturbances. A rule based-algorithm using the difference is suggested to cope with the effect of the disturbances. The algorithm adjusts the value of input units of ANN, which control a ship to keep desired route ...

• 한국환경복원기술학회지
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• 제11권3호
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• pp.74-86
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• 2008

To assessment the disturbances of the Namgang caused by dam construction, upstream area was selected for the reference reach and downstream area was selected for the comparison reach. And these reaches were surveyed and analyzed according to the assessment criteria of the river disturbances.The artificial factors of river disturbances were classified as river improvement works, dam construction and aggregate dredging. The indexes were physical factors as like epifaunal (bottom), embeddedness, velocity/depth regime, sediment deposition, channel flow status, channel alteration, frequency of riffles, bank stability, vegetative protection, riparian zone etc.The assessment results showed 46% of the assessment criteria which was serious status in dam downstream area and 89.5% of it which was excellent status in dam upstream.Finally, the results showed that physical river environment in downstream area was disturbed by the discharge control and the interception of sediment discharge by dam, consequently this disturbance give rise to impact of ecosystem in river.

• 한국군사과학기술학회지
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• 제11권2호
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• pp.53-65
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• 2008

This paper proposes the qualitative method for planning the operation of multi-AUVs with environmental disturbances, which is considered to be a very difficult task. In this paper we use an extension collision map as a collision free motion planner. The tool was originally developed for the multiple ground vehicles with no internal/external disturbance. In order to apply the method to a water environment where there are tides and waves, and currents, we analyze the path deviation error of AUVs caused by external disturbances. And we calculate safety margin for the collision avoidance on the extension collision map. Finally, the simulation result proves that the suggested method in this paper make multi-AUVs navigate to the goal point effectively with no collision among them.

• 환경생물
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• 제27권4호
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• pp.375-383
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• 2009

본 연구는 경기도 고양시와 김포시 인근의 한강하구지역에 도래하여 월동하는 재두루미의 도래 및 취식지역 이용현황, 잠재식이물, 주간 일주행동 그리고 방해요인에 대한 조사를 통하여 이 지역 재두루미의 월동생태에 대한 기초자료 구축과 지속적인 서식을 위한 보전방안을 마련하기 위하여 실시하였다. 재두루미는 본 지역에서 2월 중순에 최대개체수인 162개체가 확인되었고, 3월 중순에 모두 번식지역으로 이동하였다. 월동기간 동안 한강 주변 김포시와 고양시의 농경지역인 홍도평, 이화동, 평동 그리고 송포동지역을 취식지역으로 이용하였으며, 월동지 전체의 이용가능일수(ECC)는 334일(121~909일)이었다. 재두루미는 오전에 취식지역으로 이동하여 먹이 활동을 하였으며, 방해요인이 발생하면 한강의 갯벌로 이동하여 먹이 활동을 하거나 휴식을 취했다. 일주행동은 취식, 경계, 이동, 깃다듬기, 안락, 사회 및 기타행동으로 나누어 조사 하였으며, 월동지에서는 취식의 비율이 가장 높았다. 또한 일주행동 중 취식, 경계, 이동 그리고 깃다듬기는 취식지역별로 유의적인 차이가 나타났다. 통계적으로 유의한 차이를 나타내었다. 취식지역에서 재두루미의 월동에 방해를 주는 요인은 총 348회가 관찰되었으며, 차량, 사람, 자전거 및 오토바이와 같은 인위적인 방해요인과 소음, 동물, 기타의 자연적인 요인이 있었다. 방해요인은 이화동 (134회), 홍도평 (109회), 송포동 (64회) 그리고 평동(44회)의 순으로 관찰되었으며, 인위적인 방해요인(228회)이 자연적인 방해요인(120회)에 비해 많았다. 특히, 그 중에서 차량에 의한 방해의 빈도가 가장 높았다.

• Environmental Engineering Research
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• 제12권5호
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• pp.197-200
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• 2007

Advanced control is getting increasingly demanded in water and wastewater treatment systems. Various case studies have shown significant savings in operating costs, including energy costs, and remarkably short payback times. It has been demonstrated that instrumentation, control and automation (ICA) may increase the capacity of biological nutrient removing wastewater treatment plants by 10-30% today. With further understanding and exploitation of the mechanisms involved in biological nutrient removal the improvements due to ICA may reach another 20-50% of the total system investments within the next 10-20 years. Disturbances are the reason for control of any system. In a wastewater treatment system they are mostly related to the load variations, but many disturbances are created also within the plant. In water supply systems some of the major disturbances are related the customer demand as well as to leakages or bursts in the pipelines or the distribution networks. Hardly any system operates in steady state but is more or less in a transient state all the time. Water and energy are closely related. The role of energy in water and wastewater operations is discussed. With increasing energy costs and the threatening climate changes this issue will grow in importance.

• 한국해양바이오학회지
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• 제2권1호
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• pp.1-10
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• 2007

Coral reefs are among the most dynamic and various ecosystems on tropical ecosystem. They provide a large number of important ecosystem services. Despite their importance, they appear to be one of the most susceptible marine ecosystems. Dramatic decreasing of coral reefs has been reported from every part of the world. Indonesia contains 18% of coral reefs of world's total. Unfortunately the status of coral reefs in Indonesia is already in critical and poor condition. Coral reefs communities in Indonesia are subjected to a variety of environmental disturbance. Threats to Indonesia's coral reefs resources can be divided into two main types: anthropogenic and natural disturbances. The major anthropogenic disturbances on coral reefs in Indonesia are destructive fishing, pollution, coastal development, mining and harvesting live fish and coral, tourism. The natural disturbances such as cyclones, volcanic eruptions, earthquakes, tsunami and predator also contribute to coral reefs destruction in Indonesia. In my paper I tried to compare between natural and anthropogenic disturbances on coral reefs in Indonesia and raised these questions: (i) how the natural disturbances differ from anthropogenic area (ii) which type of disturbances has caused the greatest impact on coral reef ecosystem. My finding is that both of anthropogenic and natural disturbances give major impact on coral reefs in Indonesia. The important issue here is coral reef resilience could be disturbed by synergistic effects between various anthropogenic and natural disturbances. This phenomenon has significant conservation and management implication. The appropriate management should be conducted to protect coral reefs ecosystem in Indonesia. Mangrove management will succeed only when local people are involved and get sustainable benefits from mangrove ecosystem. Community based management and Integrated Coastal Zone Management (ICZM) are type of management that can be applied on coral reef ecosystems in Indonesia.

• Journal of Power Electronics
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• 제16권4호
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• pp.1324-1335
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• 2016

This article explores the speed regulation problem of permanent magnet synchronous motor (PMSM) systems subjected to unknown time-varying disturbances. A continuous sliding mode control (CSMC) technique is introduced for the speed loop to enhance the robustness of PMSM systems and eliminate the chattering phenomenon caused by high-frequency switch function in the conventional control law. However, the high control gain of the CSMC law in the presence of strong disturbances leads to large steady-state speed fluctuations for PMSM systems. In many application fields, PMSM systems are affected by time-varying disturbances instead of constant disturbances. For example, electric bicycles are usually affected by changing environmental disturbances, including wind speeds, road conditions, etc. These disturbances may be in the form of constant, ramp, and parabolic disturbances. Hence, a generalized proportional integral (GPI) observer is employed to estimate these types of disturbances. Then, the disturbance estimation method and the aforementioned CSMC method are combined to establish a composite sliding mode control method called the CSMC+GPI method for the speed loop of PMSM systems. Contrary to the conventional sliding mode control technique, the proposed method completely eliminates the chattering phenomenon caused by the switching function in the conventional control law. Moreover, a small control gain for the CSMC+GPI method is chosen by feed-forwarding estimated values to the speed controller. Hence, the steady-state speed fluctuations are small. The effectiveness of the proposed control scheme is verified by simulation and experimental result.

• 전자공학회논문지B
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• 제33B권9호
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• pp.1-12
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• 1996

In this paper, we propose an adaptive gait by which a quadruped walking robot can walk against external disturbances. This adaptive gait mechanism makes it possible for a quadruped walking robot to change its gait and accommodate external disturbances form various external environmental factors. Under the assumption that external disturbances can be converted to an external force acting on the body of a quadruped walking robot, we propose a new criterion for the stability margin of a waling robot by using an effective mass center based on the zero moment point under unknown external force. And for a solution of an adaptive gait against external disturbances, an method of altitude control and reflexive direction control is suggested. An algorithmic search method for an optimal stride of the quadruped mehtod, the gait stability margin of a quadruped walking robot is optimized in changing its direction at any instance for and after the reflexive direction control. To verify the efficiency of the proposed approach, some simulaton results are provided.

• 대한조선학회논문집
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• 제54권2호
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• pp.102-112
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• 2017

Many studies on dynamic positioning control algorithms using fixed feedback gains have been carried out to improve station keeping performance of dynamically positioned vessels. However, the control algorithms have disadvantages in that it can not cope with changes in environmental disturbances and response characteristics of vessels motion in real time. In this paper, the Fuzzy Gain Scheduling - PID(FGS - PID) control algorithm that can tune PID gains in real time was proposed. The FGS - PID controller that consists of fuzzy system and a PID controller uses weighted values of PID gains from fuzzy system and fixed PID gains from Ziegler - Nichols method to tune final PID gains in real time. Firstly, FGS - PID controller, control allocation algorithm, FPSO and environmental disturbances were modeled using Matlab/Simulink to evaluate station keeping performance of the proposed control algorithm. In addition, simulations that keep positions and a heading angle of vessel with wind, wave, current disturbances were carried out. From simulation results, the FGS - PID controller was confirmed to have better performances of keeping positions and a heading angle and consuming power than those of the PID controller. As a consequence, the proposed FGS - PID controller in this paper was validated to have more effectiveness to keep position and heading angle than that of PID controller.

• Journal of Forest and Environmental Science
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• 제26권3호
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• pp.161-170
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• 2010

A study was conducted for indentifying the floral biodiversity of woody species by calculating four diversity indices using data collected from 4 stands of different age groups and disturbance regimes in two areas of Madhupur tract. Results showed that highest species diversity in the old growth secondary coppice forest (>60 years) under moderate anthropogenic disturbances of Madhupur National Park area (delete (D=0.74, H'=3.36) followed by old growth secondary forest stands (>40 years) under moderate disturbances at Bhawal National Park area (D=0.65, H'=2.81). Plant species diversity of the young enrichment plantations (<20 years and <15 years) under high anthropogenic disturbances in both the areas are much low (D=0.54 and H'=2.16 and D=0.52 and H'=1.92 respectively), which indicate high anthropogenic disturbances coupled with introduction of invasive exotics that are rival for endemic species are detrimental for conservation of biological diversity of tropical moist deciduous forests of Madhupur tract in Bangladesh.