• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.7
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• pp.1298-1303
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• 2008

Respiration is induced by muscular contraction of the chest and abdomen, resulting in the abdominal volume change. Thus, continuous measurement of the abdominal dimension enables to monitor breathing activity. Conductive rubber cord has been previously introduced and tested to develop wearable application for respiratory measurements. This study implemented respiratory monitoring system with the conductive rubber cord in the patient's pants in purpose of quantitative estimation of tidal volume. Air mixed with $0{\sim}5%$ $CO_2$ was inhaled and the respiratory air flow rate, abdominal dimension change, and end tidal $CO_2$ concentration were simultaneously measured in steady state. $CO_2$ inhalation significantly increased the tidal volume in normal physiological state with the subject unawared. The tidal volume estimated from the abdominal dimension change linearly correlated with the tidal volume measured by a pneumotachometer with a correlation coefficient of 0.88. Customized calibration for each subject resulted in relative errors less than 10%. Therefore, the tidal volume was accurately estimated by measuring the abdominal dimension change.

• Journal of Korean Port Research
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• v.12 no.1
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• pp.95-104
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• 1998

Water pollution in a semi-enclosed sea area such as a bay due to stagnancy of water has been a serious water environmental problem. Recently, some kinds of new methods to activate the tidal exchange between an inner bay and an outer sea area by control of a tidal residual current have been proposed. However, these methods have several problems, that is, I). deterioration in a natural view due to building of huge structures, II). increase of risk of navigation in case of a submerged structure, III). limition of sea area where a tidal current can be controlled and IV). difficulty in removing those structures in case of occurrence of an unexpected impact on water environment. In this paper, a new method is proposed, which can solve all the above problems, to purify water quality in a semi-enclosed bay by creation and control of a pattern of a tidal residual current. The tidal residual current is controlled by unsymmetric structures, which change the properties of resistance according to the direction of flow, arranged on the sea bottom. In this study, several numerical and hydraulic experiments of tidal current and particle-tracking for various arrangements of bottom roughness in a semi-enclosed model bay were carried out. As a result of experiments, it becomes clear that it is possible to generate a new tidal residual current and to activate a tidal exchange by only operation of bottom roughness arrangement.

• Journal of Ocean Engineering and Technology
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• v.23 no.2
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• pp.18-27
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• 2009

This study was conducted to examine the effect of wind on the circulation of seawater in Gamak Bay, which contains numerous farms for fish and shellfish but suffers a significant loss by fisheries nearly annually from harmful algal blooms. In numerical experiments with a simplified bathymetry for Gamak Bay, the wind in summer appeared to more strongly influence the east-westward flow than the south-northward flow. In winter, this trend was nearly similar to the summer but seemed to have a greater effect on the flow at the north-west of the bay than the flow at the south mouth of the bay. On the other hand, in numerical experiments with a realistic bathymetry for Gamak Bay, the wind in summer appeared to more strongly influence the east-westward flow than the south-northward flow. Furthermore, the effect of the wind was stronger at the south mouth of the bay than at the north-west of the bay. In contrast, the wind in winter affected the east-westward flow more strongly and its effect appeared stronger at the north-west of the bay than at the south mouth of the bay. In addition, the effect of the wind tended to increase with distance from the east to the west. Therefore, the tidal currents in Gamak Bay proved to be strongly influenced by the wind, in particular east-westward. However, some measures are urgently required to improve the water quality of the bay, since the south-northward flow turned out to be obstructed by an east-westward shoal located in the middle of the bay.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2005.04a
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• pp.271-275
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• 2005

The horizontal heat-pulse flowmeter was used to measure grounwater flow in volcanic rocks at sites in eastern part of Jeju Island, Korea. Three boreholes, Handong-1, Jongdal-1, and Susan-1, which are located at close distance from the coastline, were selected from the sea water intrusion monitoring wells. To evaluate the direction and velocity of the groundwater flow, 6 to 8 measuring points for each borehole were chosen. There are two major flow directions at Handong-1, which are toward north-east and south-east directions and velocity ranges from $2.2{\sim}3.0cm/hr\;and\;0.6{\sim}1.0cm/hr$, respectively. For Jongdal-1, two major flow directions were detected that are east and north-west and velocity ranges from $1.2{\sim}2.0cm/hr$. For Susan-1, major flow is toward east direction and the ,velocity ranges from $2.2{\sim}2.7cm/hr$ at depth $60{\sim}70m$,\;and\;0.8{\sim}0.9cm/hr$ at depth $70{\sim}80m$. In order to evaluate the tidal effect on groundwater flow, direction and velocity were measured at specific depth with time, At depth 57m of Susan-1, the velocity increased during the tidal variation, The flow direction and velocity varies with different depths, and they are also affected by tidal fluctuation. Thereafter, care must be taken when flow direction and velociy is estimated indirectly by using hydraulic head at monitoring wells.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.161-161
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• 2011

The design methodology of the sluice caisson structure is one of important factor that is closely related to the efficiency in tidal power generation. When the sluice caisson is designed to maximize the water discharge capability, it is possible to minimize the number of sluice caissons for attaining the water amount required for achieving the target power generation, which results in reduction of the construction cost for the sluice caisson structure. The discharge capability of sluice caisson is dependent on the geometrical conditions of an apron structure which is placed in both sides of the sluice caisson. In this study, we investigated numerically the variation of water discharge capability of sluice caisson according to the geometrical conditions of apron. Flow fields are simulated with FLOW-3D software using VOF method.

• Proceedings of the Korea Water Resources Association Conference
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• 2004.05b
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• pp.992-996
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• 2004

천해역(shallow sea area)에서의 조류 형태(tidal flow regime)는 주로 만(bay)이나 해안선(shoreline)의 형태, 해저 지형(bottom topography), 수로(channel), 천퇴(sand bar)나 간석지(tidal flat) 등의 지형적인 요인에 의해 결정된다. 본 연구는 복잡한 지형적 변화 및 천해특성에 기인된 조석(tide)의 현상이 뚜렷이 나타나는 금강하구(Keum River Estuary)를 하구둑(Estuary Dike) 건설 전${\cdot}$후(Before and After Constructed)의 수심(depth)변화 및 유속(current)변화를 수치실험(numerical experiments)으로 고찰했다.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2004.11a
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• pp.143-148
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• 2004

In order to see physical characteristics of water masses and tidal currents in Gamak Bay, some field surveys have been conducted using ADCP, Aanderaa current meter and CTD from May 17 to June 3, 2004. The northwest of the bay appeared to have a high temperature and a high salinity so that it coincided with the previous results. The distribution of temperature and salinity seemed to reflect the characteristics of water masses. At the south mouth of the bay, a northwestward-southeastward flow was dominant at the surface layer while a northeastward-southwestward flow was dominant at the bottom layer.

• Journal of Navigation and Port Research
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• v.30 no.10 s.116
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• pp.861-867
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• 2006

In connection with redevelopment of Busan North Port, there has been lots of studies and efforts for the development of superannuated North general piers into a center of marine tourism and waterfront for the citizens of Busan. Recently it has moved to the stage of execution, after several trials to find concrete solutions. On the other hand, the change of flow field and tidal exchange cuased by redevelopment is one of the important investigation subjects. This study deals with the change of flow field and water exchange after redevelopment using numerical simulation technique, based on the general data which were collected and analyzed. As a result of simulation, the speed of tidal currents are tended to decrease near the North and inner-port and increase at the main waterway. Furthermore, the tidal exchange had a tendency to be small both before and after redevelopment by about 77% in a quasi steady state, which is about 15 days after.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.1
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• pp.425-431
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• 2006

In connection with redevelopment of Busan North Port, there has been lots of studies and efforts for the development of superannuated North general piers into a center of marine tourism and waterfront for the citizens of Busan. Recently it has moved to the stage of execution, after several trials to find concrete solutions. On the other hand, the change of flow field and tidal exchange cuased by redevelopment is one of the important investigation subjects. This study deals with the change of flow field and water exchange after redevelopment using numerical simulation technique, based on the general data which were collected and analyzed. As a result of simulation, the speed of tidal currents are tended to decrease near the North and inner-port and increase at the main waterway. Furthermore, the tidal exchange had a tendency to be small both before and after redevelopment by about 77% in a quasi steady state, which is about 15 days after.

• Journal of the Korean Society of Marine Environment & Safety
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• v.19 no.6
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• pp.582-596
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• 2013

In order to estimate the tide and flow properties around the archipelago, around Dolsan, Choyak, Geogeom and Jindo which located in the southwestern waters of the south sea of Korea, tidal currents, residual flows and tidal energy dissipation were investigated by using 2-dimensional numerical model. The maximum speeds of tidal currents are small around Dolsando(31.92 cm/s) and large around Jindo(87.55 cm/s). The residual flow is fastest around Choyakdo where many channels and islands as compared with other study areas. The area around Jindo has the highest currents speed, but shows the flat movements. The margins between the maximum and the minimum dispersion rates of tidal energy in the areas are estimated and designate the order of values around Dolsando($392.6{\times}10^7$ erg/s), Geogeumdo($125.7{\times}10^7$ erg/s) and Jindo($23.1{\times}10^7$ erg/s) sequently. These circumstances are same as in the amplitude of M2 constituent. This means that rapid depth changes and narrow channels play an important role in tide and tidal currents energy in archipelago.