• Journal of Korean Society of Coastal and Ocean Engineers
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• v.7 no.4
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• pp.368-378
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• 1995

Using two-dimensional depth-integrated tidal computation model. tidal charts of eight major tidal constituents (M$_2$, S$_2$, $K_2$, $N_2$, $K_1$, $O_1$, P$_1$, Q$_1$) are presented for Namhaedo area. Computed distributions of tides were compared with observations. Subsequently, the model was run for one month to derive harmonic constants of tides and tidal currents, thus for formulating predictive data tables. Data tables are then used as PC-based rapid estimation of tides in this area.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.6
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• pp.132-140
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• 2019

In this study, a specimen composed of columns, walls, beams, and slabs was fabricated to investigate the estimated reliability using nondestructive test method for the location of structural members of reinforced concrete single layer structures. And for accurate analysis in the comparison process with the existing estimation formula, we try to analyze the reliability through statistical approach by using error rate comparison and Confidence interval estimation. As a result, The average error rate of the core test was 18.8% compared with the result of estimating the compressive strength using the ultrasonic pulse velocity method. The average error rate of the core test results compared with the result of estimating the compressive strength using the rebound hardness method was 20.1%, confirming the field applicability. it is judged that the reliability of the compressive strength estimation can be derived from the wall member to make a quick and efficient structure safety diagnosis using the ultrasonic pulse velocity method. In addition, it is judged that the reliability of the compressive strength estimation can be derived from the beam member to make a quick and efficient structure safety diagnosis using the rebound hardness method.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.925-926
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• 2007

전자계 및 열/유동 해석 프로그램을 활용한 수치해석적 방법으로 변압기 외함의 자계손실과 온도상승을 계산하는 경우, 많은 시간이 소요되기 때문에, 설계 또는 고객 요구시 신속한 대응이 어렵다. 따라서 3차원 간이 계산법을 정립하여 신속 정확한 해석적 방법으로 접근할 필요가 있었다, 본 연구에서는 권선의 누설자속에 의해 발생하는 변압기 외함의 자계손실을 계산하고 이에 따른 온도상승을 추정하고자 하였다. 또한, 실제 변압기의 온도상승 시험을 통해 온도상승 계산 결과의 정확성을 검증하고자 하였다.

• Journal of the Korea Institute of Military Science and Technology
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• v.5 no.2
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• pp.185-194
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• 2002

To extract relative ranges from LOS(line of sight) information, we propose a passive ranging filter which is suitable for anti-ship missiles in HOJ(home on jam) mode. The proposed filter is devised to cope with the case that a passive ranging filter may include a large initial range estimation error since modem jammers are capable of very long range jamming. In addition, under the assumption that the missile motion is dominant over the HOJ engagement situation, the engagement geometry is modeled by a second order system. A new passive ranging filter is proposed by constructing an extended Kalman filter(EKF) based on the model. And then a least square initial state error estimation algorithm is attached to the EKF. Simulation results show that the proposed filter has a good range estimation performance with small computational load.

• Geophysics and Geophysical Exploration
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• v.24 no.4
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• pp.171-179
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• 2021

We outline a process for estimating Cole-Cole parameters from time-domain induced polarization (IP) data. The IP transients are all inverted to 2D Cole-Cole earth models that include resistivity, chargeability, relaxation time, and the frequency exponent. Our inversion algorithm consists of two stages. We first convert the measured voltage decay curves into time series of current-on time apparent resistivity to circumvent the negative chargeability problem. As a first step, a 4D inversion recovers the resistivity model at each time channel that increases monotonically with time. The desired intrinsic Cole-Cole parameters are then recovered by inverting the resistivity time series of each inversion block. In the second step, the Cole-Cole parameters can be estimated readily by setting the initial model close to the true value through a grid search method. Finally, through inversion procedures applied to synthetic data sets, we demonstrate that our algorithm can image the Cole-Cole earth models effectively.

• Journal of Korean Society of Transportation
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• v.28 no.5
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• pp.65-75
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• 2010

The objective of this paper is to quantify economic values of parcel service attributes (safety, reliability, quickness, and kindness and customer service) using the contingent choice method and to investigate impact factors (such as sex, age, and education), which influence choice of desirable parcel services. As empirical results, the marginal willingness-to-pay for multiple attributes of parcel service is calculated as about 2,349.6 KRW for the safety attribute, about 829.3 KRW for the reliability attribute, about 588.5 KRW for the quickness attribute, and about 358.8 KRW for the kindness and customer service attribute, according to the estimation model without covariates. The overall results indicate that the safety attribute ranks highest among parcel service attributes, followed by the reliability attribute, quickness attribute, and kindness and customer service attribute. These results can be useful in the decision-making process for establishing desirable pricing policies for parcel service.

• Proceedings of the KIEE Conference
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• 1998.07c
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• pp.1200-1202
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• 1998

전력 사업자들은 일반 수용가에 대한 공급 신뢰도를 개선하기 위해서 배전 자동화 시스템을 도입, 실시간 고장구간 탐색 및 계통 재구성을 추진하고 있다. 그러나. 고장 감지기 자체의 오동작이나 통신상의 오류, 다중사고의 가능성 등 불확실성을 포함하고 있기 때문에 비상시 사고구간 추정에 많은 노력과 시간비용이 요구될 수 있다. 따라서. 본 연구에서는 확률론과 휴리스틱 탐색법을 이용하여 배전자동화 시스템에 수집된 정보가 불확실성을 포함하는 경우에도 신속하게 사고 예비 후보 지역을 제시함으로써 고장구간 추정시간을 최소화 할 수 있는 전문가 시스템이 개발된다.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.1
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• pp.43-49
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• 2018

The aim of the research is to analyze the feasibility of rapid quality evaluation method for blast furnace slag using hydrometer based on the former research of the prediction method for concrete compressive strength using hydrometer. Using this method, it is expected to provide a new application for blast furnace slag quality evaluation easily and rapidly during the receiving inspection. According to the experimental results, the settling time period of hydrometer was delayed with increased fineness of blast furnace slag. By using the regression equation of y = 198 120 x - 193 936(R=0.9398) obtained from the correlation between density of suspension at three minutes and fineness, it was possible to evaluate the quality of blast furnace slag fineness rapidly. Therefore, for ready-mixed concrete receiving inspection, the suggested method can be used as a cheap, a simple, and a rapid inspection method.

• Economic and Environmental Geology
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• v.43 no.6
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• pp.615-623
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• 2010

Seismic refraction survey is a geophysical method that delineates subsurface velocity structure using direct wave and critically refracted wave. The generalized reciprocal method(GRM) is an inversion technique which uses travel-time data from several forward and reverse shots and which can provide the geometry of irregular inclined refractors and structures underlain by hidden layer such as low velocity zone and thin layer. In this study, a simple Excel-GRM routine was tested for fast mapping of the interface between weathering layer and bedrock during the survey, with employing a pair of forward and reverse shots. This routine was proved to control the maximum dip of approximately $30^{\circ}C$ and maximum velocity contrast of 0.6, based on the panel tests in terms of dipping angle and velocity contrast for the two-layer inclined models. In contrast with conventional operation of five to seven shots with sufficient offset distance and indoor data analysis thereafter, this routine was performed in the field shortly after data acquisition. Depth to the bedrock provided by Excel-GRM, during the field survey for Cheongju granite area, correlates well with the elevation of the surface of soft rock from the drill core and SPS logging data. This cost-effective routine developed for quickly delineating the bedrock surface in the field survey will be readily applicable to mapping of weathering zone in narrow zone with small variation of elevation of bedrock.

• Journal of the Earthquake Engineering Society of Korea
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• v.16 no.1
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• pp.37-45
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• 2012

In an effort to further exploit the peak ground-motion acceleration (PGA) information per second available in real time by the enacted law, bracketed summations of the PGA per second ($BSPGA_k$) for 30 seconds based on the records with a rate of 100 samples were compared with the cumulative absolute velocity (CAV) and earthquake intensities based on a worldwide database of records from small-to-large earthquakes. The CAV, currently in use as an earthquake damage indicator for nuclear power plants due to its strong correlation with the earthquake intensity, has the disadvantage of requiring a massive amount of digital data with a rate of more than 100 samples per second. The comparative study shows that the $BSPGA_k$ is well correlated with the CAV over the wide range of strong ground-motion levels, which suggests that the $BSPGA_k$ is one of the new promising ground-motion parameters especially useful for rapid earthquake alert notifications through an earthquake monitoring network. Based on the domestic database of records from small-to-moderate earthquakes with felt reports, it is also observed that the $BSPGA_k$ is comparable to the CAV and better than the PGA in predicting the intensity by using the correlation relation.