• Journal of the Society of Naval Architects of Korea
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• v.31 no.1
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• pp.14-21
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• 1994

The studios on the stability of damaged ships have been carried out continuously to prevent frequent damages or sinkings which cause large loss of life and fortunes. For dry cargo ships, continuing losses have resulted in new legislation of the probabilistic damage stability. IMO has developed requirements for the subdivison and damage stability of dry cargo ships based on probabilistic concepts. The calculation of the probabilistc damage stability is a complicated and iterative job hence development of computer programs is indispensable. In this research, programming of the probabilistic damage stability according to new requirements has been done and the results were compared with those carried out by the other foreign packages. New algorithm using a grid model in a transversal section was introduced to reduce efforts in preparing input data for damage scenarios and as a result, has brought significant improvement in efficiency and performance.

• Geomechanics and Engineering
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• v.36 no.2
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• pp.131-143
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• 2024

Shield tunneling construction commonly crosses underground pipelines in urban areas, resulting in soil loss and followed deformation of grounds and pipelines nearby, which may threaten the safe operation of shield tunneling. This paper investigated the pipeline deformation caused by double curved shield tunnels in soil-rock composite stratum in Nanjing, China. The stratum settlement equation was modified to consider the double shield tunneling. Moreover, a three dimensional finite element model was established to explore the effects of hard-layer ratio, tunnel curvature radius, pipeline buried depth and other influencing factors. The results indicate the subsequent shield tunnel would cause secondary disturbance to the soil around the preceding tunnel, resulting in increased pipeline and ground surface settlement above the preceding tunnel. The settlement and stress of the pipeline increased gradually as buried depth of the pipeline increased or the hard-layer ratio (the ratio of hard-rock layer thickness to shield tunnel diameter within the range of the tunnel face) decreased. The modified settlement calculation equation was consistent with the measured data, which can be applied to the settlement calculation of ground surface and pipeline settlement. The modified coefficients a and b ranged from 0.45 to 0.95 and 0.90 to 1.25, respectively. Moreover, the hard-layer ratio had the most significant influence on the pipeline settlement, but the tunnel curvature radius and the included angle between pipeline and tunnel axis played a dominant role in the scope of the pipeline settlement deformation.

• Journal of the Microelectronics and Packaging Society
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• v.12 no.2 s.35
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• pp.105-109
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• 2005

A compact antenna switch module for GSM/DCS dual band applications based on multilayer low temperature co-fired ceramic (LTCC) substrate is presented. Its size is $4.5{\times}3.2{\times}0.8 mm^3$ and insertion loss is lower than 1.0 dB at Rx mode and 1.2 dB at Tx mode. To verify the stability of the developed module to the process window, each block that is diplexer, LPF's and bias circuit is measured by probing method in the variation with the thickness of ceramic layer and the correlation between each block is quantified by calculating the VSWR In the mean while, two types of bias circuits -lumped and distributed - are compared. The measurement of each block and the calculation of VSWR give good information on the behavior of full module. The reaction of diplexer to the thickness is similar to those of LPF's and bias circuit, which means good relative matching and low value of VSWR, so total insertion loss is maintained in quite wide range of the thickness of ceramic layer at both band. And lumped type bias circuit has smaller insertion itself and better correspondence with other circuit than distributed stripline structure. Evaluated ceramic module adopting lumped type bias circuit has low insertion loss and wider stability region of thickness over than 6um and this can be suitable for the mass production. Stability characterization by probing method can be applied widely to the development of ceramic modules with embedded passives in them.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.9
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• pp.401-406
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• 2016

When measuring live cable faults and their location based on reflectometry, a coupler is placed between the cable and the test system. This coupler prevents damage to the test circuits by indirectly measuring the live voltage of the cable using reflectometry. It also provides a coupling path that allows the transmission and receive signal to pass into the cable. In this study, we design and construct a contact coupler to locate faults in both dead and live cables using reflectometry. The proposed coupler is of the inductive coupling type and is constructed after the calculation of the signal transmission loss by simulation. The performance of the developed coupler is tested by measuring the transmission loss and frequency flatness. The results showed that the transmission signal loss is less than -1.98dB in the frequency bandwidth above 1 Mhz. The reflectometry system was designed based on sequence time domain reflectometry (STDR) and spread spectrum time domain reflectometry (SSTDR) in order to apply it to the detection of faults and their location in live cables and tests on live cables were performed. The test results showed that the proposed coupler can be used in a reflectometry system for live cable fault detection.

• Journal of the Korea Convergence Society
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• v.10 no.6
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• pp.7-14
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• 2019

In this paper, we propose a Cascade Classifier face detection method using the Haar-like feature, which is complemented by the Flood Fill algorithm for lossy areas due to illumination and shadow in YCbCr color space extraction. The Cascade Classifier using Haar-like features can generate noise and loss regions due to lighting, shadow, etc. because skin color extraction using existing YCbCr color space in image only uses threshold value. In order to solve this problem, noise is removed by erosion and expansion calculation, and the loss region is estimated by using the Flood Fill algorithm to estimate the loss region. A threshold value of the YCbCr color space was further allowed for the estimated area. For the remaining loss area, the color was filled in as the average value of the additional allowed areas among the areas estimated above. We extracted faces using Haar-like Cascade Classifier. The accuracy of the proposed method is improved by about 4% and the detection rate of the proposed method is improved by about 2% than that of the Haar-like Cascade Classifier by using only the YCbCr color space.

• Journal of the Korean association of regional geographers
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• v.9 no.3
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• pp.373-384
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• 2003

This study analyses the soil loss due to cropland increase in the Hoeryeung area of northeast Korea, using Landsat images of 1987 TM and 2001 ETM, together with DTED, soil and geological maps, and rainfall data of 20 years. Items of land cover and land use were categorized as cropland, settlement, forest, river zone, and sand deposit by supervised classification with spectral bands 1, 2 and 3. RUSLE model is used for estimation of soil loss, and AML language for calculation of soil loss volumes. Fourier transformation method is used for unification of the geographical grids between Landsat images and DTED. GTD was selected from 1:50,000 topographic map. Main sources of soil losses over 100 ton/year may be the river zone and settlement in the both times of 1987 and 2001, but the image of the 2001 shows that sources areas have developed up to the higher mountain slopes. In the cropland average, increases of hight and gradient are 24m and $0.8^{\circ}$ from 1987 to 2001. In the case of new developed cropland, average increases are 75m and $2.5^{\circ}$, and highest soil loss has occurred at the elevation between 300 and 500m. The soil loss 57 ton of 1987 year increased 85 ton of 2001 year. Soil loss is highest in $30{\sim}50^{\circ}$ slope zones in both years, but in 2001 year, soil loss increased under $30^{\circ}$ zones. The size of area over 200 ton/year, indicating higher risk of landslides, have increased from $28.6km^2$ of 1987 year to $48.8km^2$ of 2001 year.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.1
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• pp.251-258
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• 1990

Optimal design of heat exchanger for closed CO$_{2}$ gas turbine plant of three processes selected from the result of cycle analysis have been discussed previously paper(I) has been carried out under specified inlet and outlet conditions. Independent variables such as number of parallel connection, tube diameter, shell side and tube side pressure loss as well as dependent variables such as shell diameter, number of tubes, number of serial connections were all characterized according to the standardization or so. Search method was used to construct a computer simulation together with the calculation of heat transfer rate by logarithmic mean temperature difference method. Strength analysis of major parts was carried to examine their dimensions satisfying heat transfer and pressure loss requirements.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.869-872
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• 2005

The purpose of this study is on the prediction of the acoustic performance of the lined rectangular plenum chamber which can be used in the HVAC systems. The lined plenum chamber is modeled as a piston driven rectangular tube without mean flow and the acoustic pressure in the lined chamber is obtained by superposing the three dimensional pressure due to each of uniformly and harmonically fluctuating pistons. The arbitrary locations of inlet/outlet ports as well as the acoustic higher order modes generated at the area discontinuities of the port chamber interfaces are taken into consideration. The four-pole parameters can be derived by imposing the proper boundary conditions on each inlet and outlet ports. The lining material on the internal wall is assumed to be a bulk-reacting model. A single weak variation statement which satisfies the fluctuating rigid piston condition and the pressure and displacement continuity condition at the interface between the lining material and the airway was developed. The set of cosine functions were used as the admissible function when applying the Rayleigh-Ritz method. Computed results are compared with those predicted by using the locally-reacting lining material and experimental results, respectively. There are a good agreement shown between the results by the Rayleigh-Ritz method and the experiment results. The derived transfer matrices can be easily combined with other four-pole parameters of different types of mufflers for the calculation of the whole system performance.

• Korean Journal of Soil Science and Fertilizer
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• v.16 no.2
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• pp.106-111
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• 1983

As calculation of R factor value in the Universal Soil-Loss Equation is tedious, a new simple method (IAS Index) to approximate the R factor value is proposed. Although the several methods have been tested to get R value, no one fits our conditions. IAS Index is simply calculated by summing up the amount of rainfall over two months with maximum $EI_{30}$ values. The Index is highly correlated to $EI_{30}$ value in western part of peninsular. The difference is less than 10% between $EI_{30}$ value and IAS Index. Therefore, R factor can be estimated from IAS index, summing up the rainfall amount of June and August in this region. However, IAS Index works poorly in other region, especially, eastern coastal side. The large difference may be partly due to side distribution of $EI_{30}$ value, which means no special $EI_{30}$ peaks during heavy rainy months. In this case, IAS Index is not applicable directly.

• Journal of Wetlands Research
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• v.14 no.3
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• pp.317-328
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• 2012

The objects of this study are to perform appropriateness analysis of USLE(universal soil loss equation) model and to accumulate the data measured in field. The basin area of Bongdong station is $342.27km^2$. This study simulated sediment outflows in the basin and performed a comparative analysis of simulated outputs with actual measurement values. Also annual rainfall was used to calculate rainfall-runoff erosivity factor which can influence soil erosion. The calculation of annual average soil erosion was made by soil erosion maps. The maps with a resolution of ($30m{\times}30m$) were created by multiplication of factors(R, LS, K, C, P) from ArcView Map Calculator. In this paper, it was shown that soil erosion was not occur in the most of basin.