• 농업과학연구
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• 제32권2호
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• pp.181-195
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• 2005

This study is to provide a comprehensive overview of the changing vegetable sector of Chinese agriculture and to analyse the competitiveness of Chinese vegetable production. China now produces more than 60% of the world's vegetable supply and that 150 million people are engaged in vegetable production, processing and marketing since the reform of vegetable industry structure started in the late 1980s. As a labour abundant industry, China also features more comparative advantages in the vegetable trade. Although China's vegetable exports still accounts for only 1% of total production, the 5 million tons of export in 2003 makes China one of the largest vegetable players in the international markets. When estimating competitiveness of China's vegetable industry, China's producers' prices for vegetables are founded to be only from 10%~40% of what they are in Korea, while most of China's vegetables have also strong competitiveness in quality. As China joined the WTO in 2001 and expects to increase market share in vegetable trade, the development strategy for Korea's vegetable industry are suggested as follows; 1) focusing on the technology for the growth of vegetable productivity, 2) developing the higher value added vegetable industry through processing, 3) expanding the exported area and leading vegetable varieties.

• 음성과학
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• 제7권2호
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• pp.113-126
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• 2000

A comparative phonetic analysis of Yodel singing and Belcanto singing by the electroglottographic(EGG) measurement was done in three singers. One professional tenor singer(SDI) who is also well trained in Yodel singing, another yodler(KWS) who is not so trained in Belcanto singing, and the other training tenor singer(CSK) who is not well trained both yodel and Belcanto singing. Closed quotient(CQ), speed quotient(SQ) and fundamental frequency (F0) at the initial modal part(I) , middle falsetto part(M), and final modal part(F) of the same phrase were measured by EGG machine and program(Kay model 4338). In the middle part, not only CQ but also SQ of the Yodel singing were much smaller than that of Belcanto singing in all three singers. However, accuracy of parameters in Belcanto singing of the yodler(KWS) and both Yodel singing and Belcanto singing of the training singer(CSK) were inferior to that of trained tenor singer(SDI). Possible advantages of utilizing Yodel singing training under the guidance of feedback control by the EGG for hyperfunctional voice disorders such as vocal nodules were discussed.

• KIEAE Journal
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• 제3권1호
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• pp.45-56
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• 2003

New and innovative technologies for utilizing daylight in buildings have been developed for saving energies and improving visual environments. This study describes the most up-to date information available about the application and evaluation of advanced daylighting systems to enhance daylighting in non-residential buildings from IEA's Task 21. IEA's Task 21 consists on 4 subtasks such as "Performance Evaluation of Daylighting Systems(subtask A)", "Daylighting Responsive Controls(subtask B)", "Daylighting Design Tools(subtask C)" and "Case Studies(subtask D)". For the study, the configurations and characteristics of IEA's advanced daylighting systems are comparatively analyzed. As results, innovative daylighting systems are designed to redirect sunlight or skylight to areas which it is required without glare. These systems use optical devices that initiate reflection or refraction of sunlight and skylight. And they can be designed to actively track the sun or passively control the direction of sunlight and skylight. The comprehensive overview of innovative daylighting systems presented in this study helps designer to understand the advantages of daylighting in building and choose a suitable system for building in the earliest stage of the design process.

• 한국지능시스템학회논문지
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• 제8권2호
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• pp.50-59
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• 1998

This paper presents stabilization and adaptive control of flexible single link robot manipulator system by self-recurrent neural networks that is one of the neural networks and is effective in nonlinear control. The architecture of neural networks is a modified model of self-recurrent structure which has a hidden layer. The self-recurrent neural networks can be used to approximate any continuous function to any desired degree of accuracy and the weights are updated by feedback-error learning algorithm. When a flexible manipulator is rotated by a motor through the fixed end, transverse vibration may occur. The motor toroque should be controlled in such a way that the motor rotates by a specified angle, while simultaneously stabilizing vibration of the flexible manipuators so that it is arresed as soon as possible at the end of rotation. Accurate vibration control of lightweight manipulator during the large changes in configuration common to robotic tasks requires dynamic models that describe both the rigid body motions, as well as the flexural vibrations. Therefore, a dynamic models for a flexible single link robot manipulator is derived, and then a comparative analysis was made with linear controller through an simulation and experiment. The results are proesented to illustrate thd advantages and imporved performance of the proposed adaptive control ove the conventional linear controller.

• 한국추진공학회지
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• 제6권3호
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• pp.37-43
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• 2002

지금까지 많은 열전달 계수의 측정에 관한 연구가 수행되고 있다. 본 논문에서는 액정을 이용하여 국소 열전달 계수를 측정하는 방법을 다루고 있다. 과도방법과 정상방법을 사용하여 실린더 표면의 지역적인 열전달 계수를 측정하였다. 정상상태일 때는 금박막 필름으로 실린더를 코팅하여 실험하였고, 과도방법일 때는 삽입기법과 바이패스 기법으로 각각 실험하였으며, 두 경우 모두 열풍동을 이용하여 실린더를 가열시키는 방법과 냉각시키는 방법으로 각각 실험하였다. 이와 같은 실험으로 과도방법과 정상방법을 이용하여 실린더표면에서의 대류열전달계수의 측정실험을 수행하고, 각 방법들에 대한 비교분석을 통해 액정을 이용한 열전달 측정방법의 특징들을 살펴보았다.

• 동의생리병리학회지
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• 제30권6호
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• pp.370-375
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• 2016

Recent advances in systems biology are shedding a new light on the traditional medicine research. The systems biology highlights the way each component interacts with each other within a system, and the network behavior that emerges from such interactions. This feature of systems biology can accent the systemic aspects of Korean medicine such as the mechanism of action of herbal formulae, pattern differentiation, and the meridian systems, as both the Korean medicine and the systems biology theorize the human physiological functions and phenomena from a holistic point of view. This paper outlines the meaning of the recent Korean medicine research using the systems biology methodology. We discuss the methodologies of the two fields in a comparative manner, and overview the advantages and limitations of the integrated approaches. Finally, we suggest the future prospects for the systems biology inspired approaches to the Korean medicine research. The systems biology may provide a new modernized research methodology for the Korean medicine that can highlight its unique features.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.133-135
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• 2004

As a result of the recent advances in magnetic materials, the Magnetic Amplifier(Magamp) technique is one of the reliable and cost-effective postregulation method for multiple-output power supply. This is true for high-current postregulated output since at highter output current the efficiency of linear postregulation is unacceptably low, while the complexity of more efficient switch mode postregulator is associated with a significant cost. Magamp have some advantages of higher power density, simple control circuit, good regulation, high frequency and high performance. In this paper, Operation principle of proposed approach and a performance of magamp control circuit with TL431 is described. The comparative analysis of magamp circuit and buck regulator circuit with 20W load condition is conducted. Experimental verifications on multi-output flyback converter are conducted. Simulations and experimental results show that the proposed approach is efficiency and voltage regulation of the auxiliary output is excellent.

• 정보화연구
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• 제10권2호
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• pp.237-249
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• 2013

그간 우리나라에서는 한국은행, 삼성경제연구소, 대한상의 등에서 기업가정신 측정모델을 발표한 바 있으나, 각 기관의 임의적인 측정모델 개발 및 단편적인 조사로 인해, 우리나라 기업가정신 측정 및 이해에 혼선이 초래되었다. 아울러, 기업가정신지수에 대한 국내외 비교연구의 부재로 글로벌 기업가정신지수 모델 수립이 현실적으로 어려웠다. 이에 본 연구에서는 무엇보다 기존 기업가정신 지수 관련 국내외 연구에 대한 선행연구분석과 이를 기초로 한 기업가정신 지수 모델, 즉, 기업가정신의 객관적 측정과 국제적 비교를 가능하게 하는 공통지표를 제시했다. 무엇보다 기존 연구 내용 및 장단점을 체계적으로 정리, 향후 기업가정신 지수의 방향성을 제안했다.

• Structural Engineering and Mechanics
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• 제46권5호
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• pp.735-753
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• 2013

The wind load is always the dominant load of cooling tower due to its large size, complex geometry and thin-wall structure. At present, when computing the wind-induced response of the large-scale cooling tower, the wind pressure distribution is obtained based on code regulations, wind tunnel test or computational fluid dynamic (CFD) analysis, and then is imposed on the tower structure. However, such method fails to consider the change of the wind load with the deformation of cooling tower, which may result in error of the wind load. In this paper, the analysis of the large cooling tower based on the iterative method for wind pressure is studied, in which the advantages of CFD and finite element method (FEM) are combined in order to improve the accuracy. The comparative study of the results obtained from the code regulations and iterative method is conducted. The results show that with the increase of the mean wind speed, the difference between the methods becomes bigger. On the other hand, based on the design of experiment (DOE), an approximate model is built for the optimal design of the large-scale cooling tower by a two-level optimization strategy, which makes use of code-based design method and the proposed iterative method. The results of the numerical example demonstrate the feasibility and efficiency of the proposed method.

• Smart Structures and Systems
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• 제3권4호
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• pp.405-422
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• 2007

A new hybrid damping technique for vibration reduction in flexible structures, wherein a combination of layers of hard passive damping alloys and active (smart) magnetostrictive material is used to reduce vibrations, is proposed. While most conventional vibration control treatments are based exclusively on either passive or active based systems, this technique aims to combine the advantages of these systems and simultaneously, to overcome the inherent disadvantages in the individual systems. Two types of combined damping systems are idealized and studied here, viz., the Noninteractive system and the Interactive system. Frequency domain studies are carried out to investigate their performance. Finite element simulations using previously developed smart beam elements are carried out on typical metallic and laminated composite cantilever beams treated with hybrid damping. The influence of various parameters like excitation levels, frequency (mode) and control gain on the damping performance is investigated. It is shown that the proposed system could be used effectively to dampen the structural vibration over a wide frequency range. The interaction between the active and passive damping layers is brought out by a comparative study of the combined systems. Illustrative comparisons with 'only passive' and 'only active' damping schemes are also made. The influence and the mode dependence of control gain in a hybrid system is clearly illustrated. This study also demonstrates the significance and the exploitation of strain dependency of passive damping on the overall damping of the hybrid system. Further, the influence of the depthwise location of damping layers in laminated structures is also investigated.