• 수산해양기술연구
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• 제56권4호
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• pp.299-315
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• 2020

Tuna fisheries were applied to an integrated ecosystem-based fishery risk assessment method using indexes of target species status, inhabited species in a target ecosystem, habitat quality and socio-economic benefit of affected fisheries. This study suggested more effective and efficient management measures to break away from traditional management methods, such as limitation of catch and fishing effort. The results presented that the objective risk index (ORI_S) on sustainability of bigeye and yellowfin tunas by purse seine fishery was estimated high due to the high catch ratio of small fishes. The ORIs of biodiversity (ORI_B) and habitat quality (ORI_H) of purse seine fishery were also estimated at a high level from using fish-aggregating devices (FAD). However, due to skipjack tuna's high catches, the ORI of socio-economic benefit (ORI_E) was estimated at a very low level. Due to the high bycatch rate, ORI_B was high, and ORI_S and ORI_H were evaluated at a low level in longline fishery. Due to strengthern of fishing restrictions and increase of fishing costs, the ORI_E was assessed to be very high. The ecosystem risk index (ERI) for two tuna fisheries was assessed low, but the overall FAD management by purse seine fishery is necessary at the ecosystem level.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2001년도 유체기계 연구개발 발표회 논문집
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• pp.404-410
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• 2001

A new thermal type fluid level transmitter was designed and tested at the HITROL R&D institute. The relation of heat transfer and electric resistance was adopted as an operation principle. The length of a fabricated level transmitter was two meters and a water under normal temperature was used as a working fluid for the experiment Finally, the new product could have a high precision, acceptable accuracy and reasonable response time. Foreign-made level transmitter of this type is under in use for measuring water level of containment building in nuclear power plants so far. It is expected that new product will substitute it.

• 한국환경보건학회지
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• 제19권3호
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• pp.46-51
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• 1993

In order to survery the risk of air-borne lead to human, the relation between air-borne lead level and blood lead level was examined by using of the kinetic model and statistical model. The results of this survey were as follows: 1. The pathways of lead intake were food and water, mainly. 2. Though blood lead level of Korean urbanire was higher than that of American or Japanese, it was not so severe as to influence human health. 3. The lead content in food and water was high, and so it is needed to confirm the cause of high content was whether second contamination by air pollution or not.

• 한국지형학회지
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• 제24권1호
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• pp.39-50
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• 2017

This study was conducted to analyze the variation of hydro-geomorphological environment along Baekgok wetland, which experiencing periodical inundation, in that water-level fluctuation of reservoir caused by irrigation. Since the field data is unavailable, modeling techniques, involving models such as HSPF and TELEMAC-2D, have been applied to simulate hydrological cycle in watershed and hydrodynamics in channel scale. The result of simulation indicates that the water-level of reservoir determines both the water surface extension and water depth in the wetland. Furthermore, it also shows that water-level functions as a spatial limit factor for a fluvial environment and woody vegetation such as willow. The fact of which the scale of water-level fluctuation being larger than an average topographical relief along the wetland can explain the result. While the water-level kept high, the wetland is submerged and waterbody becomes lentic. In contrast, while the water-level is lowered, fluvial phenomena of which being dependent on flow rate and channel shape become active. Hence, the valid fluvial process is likely to take place only for 4 months annually just near the channel, and it advances to a conclusion expecting a deposition to be dominant among the wetland except for such area. It is anticipated that such understanding can contribute to establishing plans to preserve the geomorphological and ecological value of the Baekgok wetland.

• 한국조경학회지
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• 제32권5호
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• pp.63-72
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• 2004

This study was carried out to analyze effects of soil, water level and shading on growth of sweet flag(Acorus calamus var. angustatus). Three types of soil were used, which included sandy, silty loam and paddy loam soil. Three levels of shading were applied in the experiment: no shading, 55％ shading and 75％ shading. The water levels were also adjusted to three levels in the experiment. The results are summarized as follows; 1. The cultivation of sweet flag in sandy soil with low water level resulted in decreased fresh weight compared to that at planting. This result indicates that the water level should be maintained higher than the soil surface for sweet flag growth in sandy soil. 2. 5 out of 72 sweet flags died in paddy loam soil. Water saturation of soil easily reduced paddy loam soil, and root growth of sweet flags in reduced soil condition were restricted, resulting in the dead plants. 3. The growth of sweet flag in paddy loam soil was worse than those in silty loam, indicating that reduced soil conditions in paddy loam is harmful to root growth. In planting sweet flags in paddy loam, improved soil aeration in paddy loam soil is necessary for good growth of sweet flag. 4. The maintaining of high water levels is better than that of low water levels in sweet flag cultivation. During winter, soil near the water surface froze and sweet flags in frozen soil were stressed physiologically. Maintaining high water levels prevents soil from being frozen which is good for the growth of sweet flags. 5. There was not significant difference in the growth of the sweet flag between non-shading and 55％ shading. It thus appears that sweet flags can grow soundly under shading rate lower than 55％.

• 한국환경과학회지
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• 제17권2호
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• pp.257-267
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• 2008

Groundwater recharge characteristics in a fractured granite area, Mt. Geumjeong, Korea. was interpreted using bedrock groundwater and wet-land water data. Time series analysis using autocorreclation, cross-correlation and spectral density was conducted for characterizing water level variation and recharge rate in low water and high water seasons. Autocorrelation analysis using water levels resulted in short delay time with weak linearity and memory. Cross-correlation function from cross-correlation analysis was lower in the low water season than the high water season for the bedrock groundwater. The result of water level decline analysis identified groundwater recharge rate of about 11% in the study area.

• International Journal of Contents
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• 제14권4호
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• pp.57-64
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• 2018

Among many UNESCO world heritage sites in Korea, "Historic Village: Hahoe" is adjacent to Nakdong River and it is imperative to monitor the water level near the village in a bid to forecast floods and prevent disasters resulting from floods.. In this paper, we propose a recurrent neural network with multiple hidden layers to predict the water level near the village. For training purposes on the proposed model, we adopt the sixth-order error function to improve learning for rare events as well as to prevent overspecialization to abundant events. Multiple hidden layers with recurrent and crosstalk links are helpful in acquiring the time dynamics of the relationship between rainfalls and water levels. In addition, we chose hidden nodes with linear rectifier activation functions for training on multiple hidden layers. Through simulations, we verified that the proposed model precisely predicts the water level with high peaks during the rainy season and attains better performance than the conventional multi-layer perceptron.

• 한국방재학회:학술대회논문집
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• 한국방재학회 2008년도 정기총회 및 학술발표대회
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• pp.683-686
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• 2008

Flood damage has been increased due to the abnormal climate and extreme rainfall. So, quantitative and qualitative hydrologic data should be improved in oder to enhance accuracy of hydrologic forecast. However, research regarding hydrologic data have not been thorough enough. Therefore, in this study, monte carlo simulation was applied to rainfall runoff model to improve the reliability of runoff analysis and risk analysis. Rainfall-Stage-Discharge curve was developed as a consequence of MCS and it is possible to get correct rating curve for high water level.

• Computers and Concrete
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• 제19권5호
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• pp.527-535
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• 2017

In this study, an aging deformation statistical model for a unique high and steep rock slope was proposed, and the aging characteristic of the slope deformation was better reflected. The slope displacement was affected by multiple-environmental factors in multiple scales and displayed the same tendency with a rising water level. The statistical model of the high and steep rock including non-aging factors was set up based on previous analyses and the study of the deformation and residual tendency. The rule and importance of the water level factor as a non-aging unit was analyzed. A partitioned statistical model and mutation model were established for the comprehensive cumulative displacement velocity with the monitoring study under multiple factors and multiple parameters. A spatial model was also developed to reflect and predict the whole and sectional deformation character by combining aging, deformation and space coordinates. A neural network model was built to fit and predict the deformation with a high degree of precision by mastering its feature of complexity and randomness. A three-dimensional finite element model of the slope was applied to approach the structure character using numerical simulations. Further, a three-dimensional finite element model of the slope and dam was developed, and the whole deformation state was analyzed. This study is expected to provide a powerful and systematic method to analyze very high, important and dangerous slopes.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2020년도 봄 학술논문 발표대회
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• pp.132-133
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• 2020

The aim of this study is to evaluate the combination effect of amorphous steel fiber and polypropylene fiber on spalling of the 150MPa level ultra high strength concrete. Considering spalling has a great relationship with water vapor pressure, this paper is focusing on water vapor pressure. The test specimens were heated accordance with ISO-834 Standard Curve using electric heating furnace, the depth of 10mm water vapor pressure formation was tend to get faster and spalling damage become severe when the mixing proportion of amorphous steel fiber increase. When using ultra high strength concrete reinforced with amorphous steel fiber, further research about proper mixing proportion of polypropylene fiber.