• KSCE Journal of Civil and Environmental Engineering Research
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• v.12 no.2
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• pp.191-203
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• 1992

This paper dealt with the statistical values including mean, standard deviation, variance and coefficient of variation for 14 soil parameters available of Lade's double work-hardening model in order to predict the behaviour of granular soil. 27 sets of all 14 parameters for Baekma river sand were determined by regression using raw data acquired from 12 isotropic compression tests and 9 triaxial compression tests with the variation of confining pressure of 1, 2, and $4kg/cm^2$ respectively 3 times performed during this study. The characteristics of each parameters were investigated. By determining the range of the upper and lower bound dependent on the increase and decrease of the standard deviation from mean value of parameters, sensitivity of all the parameters was scrutinized, by which in turn the influence of experimental error generated inevitably during tests on the determination of soil parameters was also examined.

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.6
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• pp.894-905
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• 2010

A habitat evaluation method was used to estimate the optimum suitability of the study area for the target algae. Habitat evaluation was carried out using an habitat evaluation procedure (HEP) so that the optimum suitability was quantitatively estimated for carrying out marine afforestation in the study area. According to the results of the suitability analysis, the variation of light and wave conditions according to depth showed the factors with the largest impact to involve the spatial distribution of suitable locations within the area. The total suitable area selected was calculated to be 18ha. The quality of the target algae (Ecklonia cava Kjellman) habitat was analyzed using an habitat suitability index (HSI) model of the HEP, which showed 0.55-0.907 (the maximum value being 1.0). This indicated that artificial reefs for afforestation should be installed to zonation type because the suitable area selected (The HSI value was 0.55~0.907) was distributed within the same depth line.

• Journal of Advanced Navigation Technology
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• v.23 no.6
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• pp.577-583
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• 2019

A dynamic system is called positive if any trajectory of the system starting from non-negative initial states remains forever non-negative for non-negative controls. In this paper, we consider the new stability condition for the positive time-varying linear discrete interval systems with time-varying delay and unstructured uncertainty. The delay time is considered as time-varying within certain interval having minimum and maximum values and the system is subjected to nonlinear unstructured uncertainty which only gives information on uncertainty magnitude. The proposed stability condition is an improvement of the previous results which can be applied only to time-invariant systems or had no consideration of uncertainty, and they can be expressed in the form of a very simple inequality. The stability conditions are derived using the Lyapunov stability theory and have many advantages over previous results using the upper solution bound of the Lyapunov equation. Through numerical example, the proposed stability conditions are proven to be effective and can include the existing results.

• Journal of Cadastre & Land InformatiX
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• v.44 no.2
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• pp.139-153
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• 2014

The world geodetic system transformation of cadastral record have to minimize differences of boundary and area being in cadastral record according to transformation for that is direct connected with the land owner and property protection. However it is very difficult to accurately maintain the before and after transformation because coordinate transformation is generally using a mathematical conversion formula. At present, Helmert model by using 4-parameter is official coordinate transformation model for Cadastral Resurvey Project but scale factor is most sensitive to changes of area and relative position in the same parcel. In this study, it was proposed 3-parameter method using by scale factor fixing through the application of a Helmert in order to avoid changing the area difference and keeping the error within the tolerance range of the boundary which is related to the boundary point coordinate region.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.10
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• pp.1973-1980
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• 2017

In the case of a small UUV operating an active synthetic aperture sonar, various velocity disturbances may occur on the path due to the influence of external underwater environment, and this causes phase errors in coherent synthetic aperture processing, which has a large influence on the detected image. In this paper, when a periodic sinusoidal velocity disturbance is generated in the traveling direction, the phase generated by the round trip slope range at each position is estimated the cross correlation coefficient for multiple received signals and compensated the position variation in the overlapped DPC by the average value within the maximum allowable width. Through simulations, it has been confirmed that the images degraded by the velocity disturbance amplitude and fluctuating frequency of the UUV are removed from the false targets and the performance of azimuth resolution is improved by the proposed phase compensation method.

• Journal of the Korea Concrete Institute
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• v.22 no.5
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• pp.625-632
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• 2010

The moduli of concrete has been determined by various testing methods. The impact resonance (IR) method has been shown to be truly a simple nondestructive testing method which produces consistent results. It is possible to determine not only the modulus but also damping ratio from the IR test. However, the values of elastic modulus and damping ratio of concrete from the test is known to be affected by various test conditions including, specimen support condition, impact steel ball size and sampling rate. In this study, the optimum IR test conditions are suggested and validated experimentally. The test results showed that the recommended test conditions yielded a variation of resonant frequency within ${\pm}0.3%$ and damping ratio ${\pm}10.0%$. In addition, the modulus from the IR test was comparable to that from a static test when the effect of strain amplitude was properly taken into account.

• Korean Journal of Environmental Biology
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• v.18 no.4
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• pp.447-456
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• 2000

Genus Prorocentrum of dinoflagellate has been known as representative causative algae of red tide in Masan-Jinhae Bay. Prorocentrum populations- P. dentatum Stein, p. micans Ehrenberg, P. minimum (Pavillard) Schiller and P. triestinum Schiller- were monitored from January 1990 to August 1997, Prorocentrum populations usually have bloomed during the water stratification periods from June to August. Water temperature ranged from 24$^{\circ}C$ to 28$^{\circ}C$ and salinity from 24$\textperthousand$ to 34$\textperthousand$ during the Prorocentrum blooms. Bloom magnitude of Prorooentrum populations gradually increased from offshore to inshore area of coastal embayment and this populations tended to concentrate from surface to 2.5m depth. Prorocentrum algal blooms have become more frequent and intense than those of 1980s and early 1990s. P. minimum was the most persistent species in terms of bloom frequency and cellular abundance.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.9
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• pp.1605-1614
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• 1992

The effects of % overload (% O.L), baseline stress intensity factor range (.DELTA. $K_{b}$) and dimension-less crack depth (a/W) are examined for the retardation behaviors after a single overload and high-low block loads in 7075-T73 aluminum alloy. And wheeler model, which is one of the fatigue life prediction models, is modified to predict retardation life using these test results. The retardation cycles( $N_{d}$) increased with a decrease in a/W and an increase in % O.L. and (.DELTA. $K_{b}$) These effects are more severe after high-low block loads than single overload. In the case of single overload, the main mechanisms of the retardation are the crack closure and the relaxation of K due to crack branching. But in the case of high-low block loads, that of the main mechanism is the crack closure caused by the accumulated compressive residual stree at the crack tip, which is related with the contact of fracture surfaces. Test results were multiple regression analyzed and got regressed shaping correction factors, (n)$_{REG}$, as function of %O.L., a/W and (.DELTA. $K_{b}$) Wheeler model is modified by using these (n)$_{REG}$. The number of delay cycles calculated by modified Wheeler model were in good agreement with the test results of this study.y.udy.y.y.y.

• Journal of Korean Society of Steel Construction
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• v.10 no.2 s.35
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• pp.221-232
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• 1998

This study presents a fatigue line with a plastic rotational angle to a great extent of plastic strain of Low-Cycle-Fatigue period, such as earthquake, etc. This fatigue line with a plastic rotational angle is measured and analysed more simply in practice rather than Woehler's fatigue line which is developed in stress variation of the structure. It shows that the slope of fatigue line with a plastic rotational angle is equal to that with plastic strain through the experiments by proving the correlation that the plastic strain ratio is directly proportional to the plastic rotational angle in plastic hinge. The theory is induced by Manson and Coffin strain fatigue line, and the experiments are tested by ECCS. The location of the plastic hinge is achieved and accurate plastic strain ratio is calculated through FEM.

• Journal of Korean Society of Transportation
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• v.24 no.2 s.88
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• pp.169-178
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• 2006

Traffic assignment has been used both for predicting travel demands and for evaluating the tools for alleviating congestion on road network in advance. Some assignment models have been proposed such as equivalent mathematical minimization method, variational inequality problem, nonlinear complementary problem and fixed point method, in following the principle of Wardrop (1952) that no driver can not Improve his travel cost by unilaterally changing his route. Recently Jin(2005a) presented a traffic assignment model based on dynamic process. This paper proposes a solution algorithm for the model of Jin and assesses the performances. Compared to the Frank-Wolfe method, which has been wildly used for solving the existing assignment models, the proposed algorithm is expected to be more efficient because it does not need to evaluate the objective function. Two numerical examples are used for assessing the algorithm, and they show that the algorithm converges to user equilibrium of Wardrop.