• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.5
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• pp.481-486
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• 2012

We discuss the design, fabrication, and testing of a large-displacement electromagnetic actuator with the meander springs partially exposed to a magnetic field. We compared two prototypes: a prototype (F) of the conventional actuator with the meander springs fully exposed to a magnetic field and a prototype (P) of the proposed actuator with the meander springs partially exposed to a magnetic field. For a 5 Hz square input current varying from 10.40 mA, P showed an increase of $16.9{\pm}1.2%$ in the amplitude, which was greater than the increase in the case of F. Thus, we experimentally demonstrated the large-displacement actuation performance of the proposed actuator in a small volume and at low currents (below 40 mA). The proposed electromagnetic actuator can be used for low-power and large-displacement manipulation of optical switches and optical choppers.

• Fisheries and Aquatic Sciences
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• v.1 no.1
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• pp.113-121
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• 1998

A relationship between sea level variations in the Korea Strait (the western and the eastern channels) and the Tokara Strait in the Kuroshio region is examined using daily-mean sea level data from 1966 to 1986. The seasonal variation of the sea level difference (SLD) between Izuhara and Pusan (the western channel) is most periodic: the positive anomalies appear from summer to autumn, and the negative anomalies from winter to spring year to year, whereas SLDs neither between Hakata and Izuhara (the eastern channel) nor between Naze and Nishinoomote (the Tokara Strait) show such a periodic variation. Much similarity has been found between SLDs in the eastern channel and the Tokara Strait, and in particular they were closely correlated in a special event of the Kuroshio region, such as a large meander of the Kuroshio. This paper shows that the periodic seasonal variation of the SLDs in the western channel should be less related to the Kuroshio region. This result also implies that the variation of SLD in the western channel is largely influenced by local factors, such as the bottom cold water in the western channel in summer, rather than from the Kuroshio region.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.34 no.2
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• pp.1-15
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• 2016

This study aims at the consideration of the usages of traditional waterscape elements, which are difficult to define their concepts and their differences and it has been proceeded mainly with analysis of literature. It elicited various waterscape types by extracting the place names associated with the watersacpe elements from the chapter "Sancheon" of the volumes Gyeongsang-province in "Sinjeung Donggukyeojiseungram", which is a government-compiled geography book in the early period of Joseon Dynasty, and drew the features of each waterscape element by interpreting the dictionary definition and the original text and studying the similar examples. The results of study are drawn as follows. 1. The chapter "Sancheon" includes 22 types of waterscape elements and they are classified by means of locations and water-flow forms: River Landscape, Lake & Pond Landscape, Coast landscape. 2. River landscape maintaining constant natural water-flow constitutes the linear type, related to the class of stream, which includes 'Su(water)', 'Gang(river)', 'Cheon(stream)' and 'Gye(brook)' and the dotty type, created by the nature of trenched meander rivers, which includes 'Tan(beach)', 'Roe(rapids)', 'Pok(waterfall)' and 'Jeo(sandbank)'. 3. Lake & Pond Landscape forming water collected in a certain area constitutes 'Ho(lake)', which is a broad and calm spot created around mid and down stream of river, 'Yeon(pool)', 'Dam(pond)', 'Chu(small pond)', which are naturally created on the water path around mid and down stream of river, 'Ji(pond)', 'Dang(pond)', 'Taek(swamp)', which is collected on a flatland and 'Cheon(spring)', 'Jeong(spring)' which means gushing out naturally. 4. Coast Landscape includes 'Ryang', 'Hang', which are the space between land and an island or islands, 'Got(headland)' which sticks out from the coast into the sea, 'Jeong(sandbank)' which forms sandy beaches and 'Do' which shows high appearance frequency by reflecting the geographical importance of islands. This study comprehended the diversity of traditional waterscape elements and drew the fact that they are the concept reflecting the differentiated locational, scenic and functional features. That way, it understood the aesthetic sense on nature, which ancestors had formed with the interests in natural landscape and the keen observation on it, became the basic idea elucidating the characteristic on Korean traditional gardens, which minimize the artificiality and make nature the subject.