• Economic and Environmental Geology
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• v.49 no.6
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• pp.445-458
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• 2016

Most of water curtain cultivation (WCC) area in Korea has been inveterately suffering from the gradual draw-down of groundwater level and related shortage of water resources at the late stage of WCC peak time. To solve this problem, artificial recharge techniques has been recently applied to some WCC area. This study introduces infiltration gallery, which is one of the artificial recharge methods, and tentatively examined the effectiveness of three galleries installed at Sangdae-ri WCC area of Cheongju City. Seven galleries are set up at each empty space between eight vinyl houses in this area and its dimension is designed as 50 cm in each width and height and 300 cm in each length. Installation process was including bed excavation, backfill with gravels and silica sands, and completion of gallery by equipment of piezometer and covering with non-woven cloth. For each B, C, D gallery, 3 types of test including preliminary, four step and one long-term injection were performed. The first preliminary test showed the rough relations between injection rates and water level rise as follows; 20 cm and 30 cm level rise for $33.29{\sim}33.84m^3/d$ and $45.60{\sim}46.99m^3/d$ in B gallery; 0 cm, 16 cm and 33 cm level rise for $21.1m^3/d$, $33.98m^3/d$ and $41.69m^3/d$ in C gallery; 29 cm and 42 cm level rise for $48.10m^3/d$ and $52.23m^3/d$ in D gallery. Afterwards, more quantitative results estimating effectiveness of artificial recharge were reasoned out through stepped and long-term injection tests, which is expected to be employed for estimating water quantity re-injected into the aquifer through these galleries by natural injection over the period of WCC peak time.

• Journal of Korean Society of Steel Construction
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• v.9 no.2 s.31
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• pp.205-220
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• 1997

The objective of this study is to investigate the structural behavior of concrete-filled steel tubular column-H beam connections with exterior stiffeners. As a preliminary test, simple tensile test on the column to H-beam flange connections stiffened were conducted The paramaters of tensile test are the thickness(T=9, 12, 15m) and the width(W=50, 75, 100, 150mm) of exterior stiffeners. The simple tensile test were conducted to 7 kinds of specimens. Estimating the load, displacement, and strain from each kind, results of simple tensile test were compared with results of second test. On the basis of simple tensile test, test on the column to H-km connections stiffened with the sames under monotonic and cyclic load were conducted. Specimens of 5 for the second experiment were made. In analysis, comparing each strengthes and stiffnesses we estimated deformation capacity. Comparing and estimating each yielding strength ratios and maxium-strength ratios on the basis of yield line theory, new strength formula of beam-to-column connections was suggested.

• KIISE Transactions on Computing Practices
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• v.23 no.2
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• pp.110-115
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• 2017

We propose a new indoor positioning algorithm named Cut-off algorithm. This algorithm cuts off candidates of beacons and reference points in advance, before looking for K neighbor reference points which are guessed to be closest to the user's actual location. The algorithm consists of two phases: off-line phase, and on-line phase. In the off-line phase, RSSI and UUID data from beacons are gathered at reference points placed in the indoor environment, and construct a fingerprint map of the data. In the on-line phase, the map is reduced to a smaller one according to the RSSI data of beacons received from the user's device. The nearest K reference points are selected using the reduced map, which are used for estimating user's location. In both phases, relative ranks of the peak signals received from each beacon are used, which smoothen the fluctuations of the signals. The algorithm is shown to be more efficient in terms of accuracy and estimating time.

• Journal of Korean Society of Steel Construction
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• v.9 no.3 s.32
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• pp.377-390
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• 1997

The objective of this study is to investigate the structural behavior of concrete-filled steel tubular column to H-beam connections with reinforced bar. As a preliminary test, simple tensile test on the column to H-beam connections stiffened were conducted. The parameters of tensile test are the diameters of each rebars. The simple tensile test were conducted to 5 kinds of specimens. Estimating the load. displacement and strain for specimens, the result of tensile test were compared with the results of main test. On the basis of simple tensile test, tests are conducted to montonic and cyclic loading column to H-beam connections with the same diameters of rebars. Specimens of 5 are made for monotonic and cyclic loading test. In analysis, estimating the yielding strength and maximum strength of specimens on the basis of yield line theory, strength formula of beam-to column connections with concrete-filled steel tubular column was suggested.

• Journal of the Korean GEO-environmental Society
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• v.13 no.8
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• pp.35-43
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• 2012

Construction of sheet pile retaining walls in urban and coastal regions has resulted in sheet pile walls in close proximity to laterally loaded pile foundations. However, there is currently little information available in the literature to assist engineers for quantifying the response of sheet pile walls. This study provides a quantitative method for estimating sheet pile wall response due to loads imposed from a nearby laterally loaded pile. Three dimensional finite element analyses using commercial software, ABAQUS, were performed to assess the response of a sheet pile wall and nearby laterally loaded pile. The soils were modeled using Drucker-Prager constitutive model with associated flow rule, and the sheet pile wall and pile foundation were assumed to behave linear elastic. Four parameters were investigated: sheet pile wall bending stiffness, distance from the pile face to the wall, excavation depth in front of the sheet pile wall, and elastic modulus of the soil. Results from the analyses have been used to develop preliminary design charts and simple equations for estimating the maximum horizontal displacement and maximum bending moment in the sheet pile wall.

• The Korean Journal of Physiology and Pharmacology
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• v.26 no.3
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• pp.195-205
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• 2022

Determining blood loss [100% - RBV (%)] is challenging in the management of haemorrhagic shock. We derived an equation estimating RBV (%) via serial haematocrits (Hct₁, Hct₂) by fixing infused crystalloid fluid volume (N) as [0.015 × body weight (g)]. Then, we validated it in vivo. Mathematically, the following estimation equation was derived: RBV (%) = 24k / [(Hct₁ / Hct₂) -1]. For validation, non-ongoing haemorrhagic shock was induced in Sprague-Dawley rats by withdrawing 20.0%-60.0% of their total blood volume (TBV) in 5.0% intervals (n = 9). Hct₁ was checked after 10 min and normal saline N cc was infused over 10 min. Hct₂ was checked five minutes later. We applied a linear equation to explain RBV (%) with 1 / [(Hct₁ / Hct₂) -1]. Seven rats losing 30.0%-60.0% of their TBV suffered shock persistently. For them, RBV (%) was updated as 5.67 / [(Hct₁ / Hct₂) -1] + 32.8 (95% confidence interval [CI] of the slope: 3.14-8.21, p = 0.002, R² = 0.87). On a Bland-Altman plot, the difference between the estimated and actual RBV was 0.00 ± 4.03%; the 95% CIs of the limits of agreements were included within the pre-determined criterion of validation (< 20%). For rats suffering from persistent, non-ongoing haemorrhagic shock, we derived and validated a simple equation estimating RBV (%). This enables the calculation of blood loss via information on serial haematocrits under a fixed N. Clinical validation is required before utilisation for emergency care of haemorrhagic shock.

• Journal of the Korean Geotechnical Society
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• v.15 no.1
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• pp.15-29
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• 1999

This study presents an analytical method of estimating the developed horizontal active thrusts against GRS-RW( Geosynthetic Reinforced Soil Retaining Wall) system adapted to the case of distanced surcharge. In addition, the design charts that could be used for preliminary design of GRS-RW system are presented. The proposed method of analysis uses two body translation mechanism as well as force polygon concept. taking into account the effect of facing's rigidity. Besides. the effect of tension cracks in c-\Phi$ soils, seismic effects and horizontal distance from the back face of wall to uniformly distributed surcharge loadings are also included. The results of horizontal active thrusts obtained from the developed method of analysis are compared with those from Jarquio's modified Boussinesq equation.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.5
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• pp.416-422
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• 2016

This paper presents preliminary performance analysis of a satellite formation flying testbed, which is under development by Astrodynamics and Control Laboratory, Department of Astronomy, Yonsei University. A model reference adaptive controller (MRAC) with a first-order reference model is chosen to enhance the response of reaction wheel system which is subject to uncertainties caused by unmodelled dynamics and measurement noise. In addition, an on-line parameter estimation (OPE) technique based on the least square is combined to eliminate the effect of angular measurement noise by estimating the moment of inertia. Both numerical simulations and hardware experiments with MRAC support the effectiveness and applicability of the adaptive control scheme, which maintains the tracking error below $0.25^{\circ}$ for the entire time span. However, the high frequency control input generated in hardware experiment strongly suggests design modifications to reduce the effect of deadzone.

• Journal of Sensor Science and Technology
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• v.9 no.4
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• pp.256-267
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• 2000

In this paper, we studied the ultrasonic urine volume sensor of urinary alarm system for home use to detect the time of urination as a assistive methodology for the incontinence patients and the correlation between urine volume and bladder interwall distance by using developed sensor. The developed sensor was designed to minimize the measurement error by using ultrasound with 2.25 MHz center frequency which provides higher resolution as well as longer penetration depth. To verify usefulness of the developed sensor, we performed a preliminary experiment of estimating bladder volume from the measured distance between interior and posterior wall of bladder. In the preliminary experiment, bladder volume estimated from the result using a commercial ultrasonography system. The experimental results show there exists god correlation between the actual urine volume and the measured interwall distance of the bladder. In conclusion, the developed ultrasound bladder volume sensor can be applied to an urine alarm system which provides patient the exact time of urination, it will be contribute in health care and welfare society.

• Korean Journal of Construction Engineering and Management
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• v.21 no.3
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• pp.48-56
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• 2020

Prediction of construction cost in the planning stage that provides basic information for feasibility study, budgeting, and planning is an important factor for successful project execution. In this study, a prediction model was developed for the purpose of improving the accuracy of estimating the construction cost of Hanok in the planning stage. The cost of this model is estimated by two methods. First, the cost of wood work, which accounts for the largest portion of the total construction cost, is estimated by calculating the approximate quantity under various conditions (structure type, roof type, plane type, etc.). Second, the cost of the rest work sections except the wood work is estimated by using the unit cost model. The predictive model was verified by two case projects, and the error rate of total construction cost was -4%(case 1) and -6%(case 2). These results showed an error rate in the range that can be applied to practice in the planning stage.