• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.1225-1228
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• 2004

Principles and mechanism of energy transduction of dielectric polymer materials are well known from the various smart material related publications. However their introduction to industrial actuator applications is limited mainly due to difficulties guarantee controllability and reliability. Most of the previous publications have elaborates energy transduction physics of chunk of polymer while development of construction methods for feasible actuators made of the material is rarely proposed. In the present article, a conceptual design of multi-DOF linear polymer actuator construction that is to be controllable with moderate level of control work os introduced. In addition, numerical models that are developed with a unified energy based approach are presented not only for basic working mechanism analysis of the polymetric soft actuator but for providing analytical foundation to expend the concept toward design of multi-DOF actuator controls.

• KIEAE Journal
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• 제2권2호
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• pp.23-31
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• 2002

The purpose of this study is to suggest an environmentally friendly energy system of ecological architecture, with the reference to foreign cases, judge feasibility of it. The ecological architecture is very similar to the natural ecosystem. There is growing international scientific consensus that human activities are having a discernible effect on the global climate. Therefore, with a precise understanding of the concept of ecological approach and concrete perception of the necessity it, an establishment of planning which recognizes the ecological architecture as a organism a same time, ensures diversity, stability and cycling stemmed from the ecosystem to various activities through a ecological structure shall bring the introduction of substantial ecological architecture into domestic realm. As a result, in this Age of industrial science, We are proposing useful materials and suggestion regarding the ecological architecture planning of korean cities, by preestimating the characteristics of a city heading toward the Age of the new ecological environment.

• 태양에너지
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• 제18권2호
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• pp.31-49
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• 1998

본 고에서는 지금까지 연구 개발 된 제반 태양열 냉방시스템의 개요 및 원리와 기술현황에 대하여 소개하였다. 소개된 기술은 $LiBr-H_2O,\;H_2O-NH_3,\;CaCl_2-NH_3$을 이용한 태양열 흡수식 냉방시스템; 활성탄, 실리탄, 실리카겔 등을 이용하는 제습냉방(desiccant cooling)시스템; Ranking engine을 이용하는 증기압축식 냉방시스템; $Zeolite-H_2O$, 실리카겔-$H_2O$, 실리카겔-메탄을 활성탄-메탄을 등 "고체흡착제-냉매"를 이용한 태양열 흡착식 냉동시스템 등이다. 이들 기술들을 실용화 단계에 있거나 실용화 단계에는 못 미치나 상당한 기술개발이 되어있는 분야이다. 또한 각 시스템별 비교분석이 가능하도록 대략적인 효율과 장단점이 소개되었다.

• Journal of Power Electronics
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• 제16권2호
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• pp.748-759
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• 2016

The microgrid concept is a promising approach for injecting clean, renewable, and reliable electricity into power systems. It can operate in both the grid-connected and the islanding mode. This paper addresses the two main challenges associated with the operation of a microgrid i.e. control and protection. A control strategy for inverter based distributed generation (DG) and an energy storage system (ESS) are proposed to control both the voltage and frequency during islanding operation. The protection scheme is proposed to protect the lines, DG and ESS. Further, the control scheme and the protection scheme are coordinated to avoid nuisance tripping of the DG, ESS and loads. The feasibility of the proposed method is verified by simulation and experimental results.

• Nuclear Engineering and Technology
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• 제30권2호
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• pp.140-147
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• 1998

Basic concept of a cold neutron source for a 30 MW heavy water moderated reactor (HANARO) is developed. The source is a cold bottle located in a vertical hole near the reactor core. Since the bottle does not have sufficient volume for cooling, the optimum liquid mixture ratio is studied between liquid hydrogen and liquid deuterium. We also studied the variation of the gain depending on the volume of the bottle. The calculation is performed by a coupled MCNP model and by a semi-analytic approach. For the current geometry, 80% liquid deuterium mixture with liquid hydrogen gives the highest gain at 10 A neutron wave.

• 한국정보통신학회논문지
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• 제12권8호
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• pp.1377-1383
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• 2008

3차원 메쉬 매개변수화는 기하학적 모델링과 컴퓨터그래픽스의 여러 응용분야에서 핵심적인 문제이다. 메쉬 매개변수화 방법에는 크게 두 가지의 패러다임, 에너지 최소화 방법과 볼록 조합법이 있다. 일반적으로 볼록 조합법은 간단한 개념과 일대일 대응 때문에 널리 이용되고 있다. 그러나 이 방법은 경계선 근처의 높은 왜곡이 생긴다는 문제와 선형 시스템 구성에 있어 다소 많은 시간이 소요되는 문제를 가지고 있다. 또한 이 방법은 다루는 메쉬 의 기하학 정보에 따라 선형시스템의 안정성이 해손 될 수도 있다. 본 논문에서는 볼록 조합법이 갖고 있는 선형시스템 안정성 문제와 시간 복잡도 문제를 중간값 좌표계를 이용하여 해결한다. 빠른 시간에 안정적으로 처리가 가능하기 때문에 보다 실용적이라 할 수 있다.

• 한국해양공학회지
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• 제32권6호
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• pp.502-510
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• 2018

In order to accumulate data to lower the friction coefficient of a press mold, tribological tests were performed before and after coating SM45C with a PVC/PO film and plasma coating (CrN, concept). The ultrasonic nanocrystal surface modification (UNSM)-treated material had a nano-size surface texture, high surface hardness, and large and deep compressive residual stress formation. Even when the load was doubled, the small amount of abrasion, small weight of the abrasion, and width and depth of the abrasion did not increase as much as those of untreated materials. A comparison of the weight change before and after the tribological test with the CrN and the concept coating material and that of the untreated material showed that the wear loss of the concept coating material and P-UNSM treated material (that is, the UNSM treated material treated with the concept coating) showed a tendency to decrease by approximately 55-75%. Concept 100N had a lower friction coefficient of about 0.6, and P-UNSM-30-100N showed almost the same curve as concept 100N and had a low coefficient of friction of about 0.6. The concept multilayer coating had a thickness of $5.32{\mu}m$. In the beginning, the coefficient of friction decreased because of the plasma coating, but it started to increase from about 250-300 s. After about 350 s, the coefficient of friction tended to approach the friction coefficient of the SM45C base metal. The SGV-280F film-attached test specimen was slightly pushed back and forth, but the SM45C base material was not exposed due to abrasion. The friction coefficient was 0.22, which was the lowest, and the tribological property was the best in this study.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1993년도 봄 학술발표회 논문집
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• pp.65-72
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• 1993

Steel fiber reinforced concrete(SFRC) which is made by short, randomly distributed steel fibers in concrete is superior in its tensile mechanical properties to plain concrete in enhancement of tensile strength and tensile ductility. These improvements are attributed to crack arresting mechanism and formation of longer crack paths due to fibers , which as a consequence lead to increase in energy absorption capacity of SFRC. In the post-peak region under tensile stresses, major macrocrack forms at critical section. The opening of this macrocrack is mainly resisted by both of the fiber pull-out bridging the cracked surfaces and the resistance by matrix softening. In this study, micromechaincal approach has been made in order to simulate tensile behavior of SFRC and based on which the theoretical model is presented. This model reflects the features of both the composite material concept and the spacing concept in predicting tensile strength of SFRC. The model also takes into account for the effects of matrix tensile softening and fiber bridging by pull-out on the resistance for the post-peak behavior of SFRC. It has been shown that the developed model satisfactory predicts the experimental results.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 춘계학술대회 논문집
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• pp.467-470
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• 2009

Variable loads along the drive-train are attributed to frequent failures of gears, bearings, and other components. Wind parameters cannot be controlled and therefore any turbine load-reducing remedies must be established based on proper insights into the wind-turbine interactions. A novel control concept to performance optimization of wind turbines is presented. This proposed concept is based on analysis of the turbine status reflected in the SCADA data. Modern computational techniques are used to optimize performance of a wind turbine from tree basic perspectives: drive-train, power output, and power quality. The proposed approach demonstrates that gains in the metrics representing the three perspectives and the corresponding control goals can be significantly improved for any wind turbine. The solution is applicable different turbine types operating in different wind regimes, e.g., winds of different speeds and variability. Simple and transparent parameters allow an operator to determine a balance between the operations and maintenance, technical, business objectives. The proposed modeling framework was embedded in software. The software tool has been tested on the data collected from 1.5 MW wind turbines.

• International Journal of Advanced Culture Technology
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• 제3권1호
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• pp.78-85
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• 2015

In Thailand, the electricity consumption is very high with the intention of reduce high temperature in the building. Since 2000, a lot of people paying attention to Green-Building concept. A similar concept is natural building, which is usually on a smaller scale and tends to focus on the use of natural materials that are available locally. Therefore, the Earth-Block (EAB) product is appropriated approach to reduce energy consumption in the buildings. The EAB is produced with environmentally friendly process, which does not release harmful pollution and effective cost. The main significant character is durable materials for building construction. This study aims to develop the new thermal insulation by using soil-cement with vetiver grass fibre. Additionally, it describes the innovative systems used in production of EAB materials by mixing the soil-cement with vetiver grass fibre. This paper reveals lowest costs, space configurations changing and greater design flexibility for constructing the building.