• Journal of Ocean Engineering and Technology
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• v.35 no.4
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• pp.266-272
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• 2021

Mooring systems are among the most important elements employed to control the motion of floating offshore structures on the sea. Considering the use of polymer material, a new method is proposed to address the creep characteristics rather than the method of using a tension load cell for measuring the tension of the mooring line. This study uses a synthetic mooring rope made from a polymer material, which usually consists of three parts: center, eye, and splice, and which makes a joint for two successive ropes. We integrate the optical sensor into the synthetic mooring ropes to measure the rope tension. The different structure of the mooring line in the longitudinal direction can be used to measure the loads with the entire mooring configuration in series, which can be defined as SMART (Smart Mooring and Riser Truncation) mooring. To determine the characteristics of the basic SMART mooring, a SMART mooring with a diameter of 3 mm made of three different polymer materials is observed to change the wavelength that responds as the length changes. By performing the longitudinal tension experiment using three different SMART moorings, it was confirmed that there were linear wavelength changes in the response characteristics of the 3-mm-diameter SMART moorings. A 54-mm-diameter SMART mooring is produced to measure the response of longitudinal tension on the center, eye, and splice of the mooring, and a longitudinal tension of 100 t in step-by-step applied for the Maintained Test and Fatigue Cycle Test is conducted. By performing a longitudinal tension experiment, wavelength changes were detected in the center, eye, and splice position of the SMART moorings. The results obtained from each part of the installed sensors indicated a different strain measurement depending on the position of the SMART moorings. The variation of the strain measurement with the position was more than twice the result of the difference measurement, while the applied external load increased step-by-step. It appears that there is a correlation with an externally generated longitudinal tensional force depending on the cross-sectional area of each part of the SMART mooring.

• KIPS Transactions on Computer and Communication Systems
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• v.11 no.12
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• pp.437-444
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• 2022

Recently, research on mobile edge services has been conducted to handle computationally intensive and latency-sensitive tasks occurring in wireless networks. However, MEC, which is fixed on the ground, cannot flexibly cope with situations where task processing requests increase sharply, such as commuting time. To solve this problem, a technology that provides edge services using UAVs (Unmanned Aerial Vehicles) has emerged. Unlike ground MEC servers, UAVs have limited battery capacity, so it is necessary to optimize energy efficiency through load balancing between UAV MEC servers. Therefore, in this paper, we propose a load balancing technique with consideration of the energy state of UAVs and the mobility of vehicles. The proposed technique is composed of task offloading scheme using genetic algorithm and task migration scheme using Q-learning. To evaluate the performance of the proposed technique, experiments were conducted with varying mobility speed and number of vehicles, and performance was analyzed in terms of load variance, energy consumption, communication overhead, and delay constraint satisfaction rate.

• Proceedings of the KIEE Conference
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• 1999.07c
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• pp.1478-1480
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• 1999

The accurate analysis of power system requires detailed load model. There are two basic approaches in modeling the load characteristics. One is to directly measure the voltage and frequency sensitivity of the load P and Q at substations and feeders. The other is to build up a composite load model from each load component. Each of these methods has advantages and disadvantages. This paper presents load composition for KEPCO's power system to develop load models by the component-based load modeling.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.104.1-104
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• 2001

This paper presents a technique to development load control and management system in order to limits a maximum load demand and saves electric energy consumption. The computer programming proper load forecasting algorithm associated with programmable logic control and digital power meter through inform of multidrop network RS 485 over the twisted pair, over all are contained in this system. The digital power meter can measure a load data such as V, I, pf, P, Q, kWh, kVarh, etc., to be collected in statistics data convey to data base system on microcomputer and then analyzed a moving linear regression of load to forecast load demand Eventually, the result by forecasting are used for compost of load management and shedding for demand monitoring, Cycling on/off load control, Timer control, and Direct control. In this case can effectively reduce the electric energy consumption cost for 10% ...

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.5
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• pp.403-408
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• 2012

In this paper, we propose useful load flow algorithms called FEDL (fast enhanced decoupled load flow). The proposed load flow method can improve the convergence characteristics particularly when the P-Q coupling becomes significant and the power system operating states deviate from the conditions required for stable convergence of the FDL by reflecting in part the effects of the off-diagonal terms in the Jacobian. In our test with IEEE AEP-30 bus system and RTS-96 73-bus system, it converge even when the fast decoupled load flow (FDL) and its variations keeping load flow matrices constant experience convergence problems. Test results show promising performances of the proposed algorithms in their convergence characteristics both in number of iterations and overall convergence speeds.

• Journal of Korean Society on Water Environment
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• v.31 no.6
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• pp.653-664
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• 2015

TPLMS (Total water pollutant load management system) that is the most powerful water-quality protection program have been implemented since 2004. In the implementation of TPLMS, target water-quality and permissible discharged load from each unit watershed can be decided by water-quality modeling. And NPS (Non-point sources) discharge coefficients associated with certain (standard) flow are used on estimation of input data for model. National Institute of Environmental Research (NIER) recommend NPS discharge coefficients as 0.15 (Q₂₇₅) and 0.50 (Q₁₈₅) in common for whole watershed in Korea. But, uniform coefficient is difficult to reflect various NPS characteristics of individual watershed. Monthly NPS discharge coefficients were predicted and estimated using surface flow and water-quality from HSPF watershed model in this study. Those coefficients were plotted in flow duration curve of study area (Palger stream and Geumho C watershed) with monthly average flow. Linear regression analysis was performed about NPS discharge coefficients of BOD, T-N and T-P associated with flow, and R² of regression were distributed in 0.893~0.930 (Palger stream) and 0.939~0.959 (Geumho C). NPS Discharge coefficient through regression can be estimated flexibly according to flow, and be considered characteristics of watershed with watershed model.

• Journal of the Korean Geotechnical Society
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• v.21 no.3
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• pp.19-25
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• 2005

A tunnel that uses the RMR method or the Q-system is called a 'modem tunnel' because the New Austrian Tunneling Method (NATM) is not employed, even though shotcrete and rock bolts are used as support. It is known that the modem tunnel, which is supported by shotcrete, is basically different from the conventional tunnel, which is supported by steel ribs. In order to preserve the load-carrying capacity of the rock mass, loosening and excessive rock deformations must be minimized. Although it is known that this can be achieved by applying shotcrete in the case of the modem tunnel, this has not been clearly demonstrated. In order to inspect the distinctions between the conventional tunnel and the modern tunnel, their support characteristics and the rock loads of the rock mass classifications are compared. Terzaghi's rock load classification was used as the conventional tunnel's representative rock mass classification. The RMR method and the Q-system were adopted as the modem tunnel's representative rock mass classification. The study's results show that the load-carrying capacity of shotcrete, when used as the main support in the modern tunnel, is greater than the load-capacity of the steel ribs used in the conventional tunnel. Because it has been verified that the rock loads of their rock mass classifications are not different, then, according to the rock mass classifications, the load-carrying capacity of the rock mass of the modern tunnel, which uses shotcrete, is not greater than that of the conventional tunnel.

• Journal of Nutrition and Health
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• v.42 no.7
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• pp.622-630
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• 2009

The purpose of this study was to establish an association between glycemic index (GI), glycemic load (GL), dietary carbohydrates and diabetes with the context of the current population dietary practice in Korea. The subjects of 3,389 adults (male 1,430, female 1,959) were divided into normal (serum fasting glucose < 100 mg/dL), impaired glucose tolerance (100 ${\leq}$ serum fasting glucose < 126 mg/dL), diabetes (serum fasting glucose > 126 mg/dL) by serum fasting glucose. Anthropometric and hematologic factors, and nutrient intakes, dietary glycemic index (DGI), dietary glycemic load (DGL) were assessed. Multiple logistic regression model was used to determine the odds ratios (ORs) and 95% confidence intervals for relationship of DGI, DGL, carbohydrates intakes, and diabetes. DGI and DGL were not significantly correlated with impaired glucose tolerance and diabetes. However, the risk of impaired glucose tolerance and diabetes showed a tendency to increase as increase of DGI after multivariate adjustment (age, education, income, region area, diabetes family history, smoking, drinking, exercise, energy intake) in male. The risk of impaired glucose tolerance and diabetes showed a tendency to increase in the DGI 71.1-74.8 after multivariate adjustment in female. DGL was inversely related to impaired glucose tolerance and diabetes in male. In female, however, DGL was positively related to impaired glucose tolerance and diabetes. In particular, the risk of diabetes increased positively in level of DGL 260.5, and remained after multivariate adjustment (Q5 vs Q1：2.38, 0.87-6.48). When percent energy intakes from carbohydrates were more than 70%, the risk of impaired glucose tolerance and diabetes increased in both male and female. In particular, when percent energy intakes from carbohydrates were more than 69.9%, the risk of diabetes increased positively in male (Q4 vs Q1：2.34, 1.16-4.17). In conclusion, above 70% energy intakes from carbohydrates appeared to be a risk factor of diabetes. It seemed that the meal with high GI and GL value must be avoided it. And also, the macronutrients of the meal must be properly balanced. In particular, it may be said that it is a preventive way for treatment of the diabetes to avoid eating carbohydrates of much quantity.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.10
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• pp.61-68
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• 2001

Turbine blade in nuclear plant is subject to cyclic bending fatigue by high steam pressure. Especially, fatigue fracture is caused by low stress below yielding stress. Photograph by SEM doesn't have striation but photograph by AFM has striation on the fatigue fractured surface of 12% Cr steel used in turbine blade. Surface roughness $R_q$ has the linear relation with respect to stress intensity factor range ΔK and is increased linearly according to load amplitude $\textit{\Delta}P$. In this study loading condition applied to turbine blade is predicted by the relation between the gradient of $R_q$ to $\textit{\Delta}K$ and load amplitude $\textit{\Delta}P$.

• Water for future
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• v.9 no.1
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• pp.86-100
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• 1976

To study influences on the downstream, and the Gunsan harbor by setting up estuary of the Gumgang, available data which were collected from the measuring stations which were established within the river basin of which results attained are as follows: 1. The discharge can be calculated as the relationship between the discharge and precipitation in the basin is $R=4{\times}10^{-4}p^2$ or R=P-600 2. The discharge flow in to small resevoirs in the basin can be estimated as $QR=QS\frac{PR-600}{PS-600}(\frac{AR}{AS})$ 3. This daily average discharge at Kongju is 31% less than the during maximum probable discharge and that in Okcheon is 48% less than the daily maximum probable flood. 4. The maximum probable flood from the small stream in the basin can be estimated by a $Q=82.45A^{0{\cdot}464}$ 5. Sediments can be computed with Qs (suspended load)=1.41 $Q^{1{\cdot}42}$ and Qb (bed load)=165.2 $Q^{0{\cdot}705}$. 6. By setting up the specific estuary the tidal movement will be reduced to 93.6% on the average and the sedimentation is reduced to 96.0%. Upon review of overall analysis, the dead wate level of estuary of Gumgang will completely sedimented in next 30 years, therefore, the dredging work at Gunsan harbor is reduced to 73.6%, it is considered that life length will be extended about 52years taking account the existing condition.