• Journal of the Ergonomics Society of Korea
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• v.31 no.1
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• pp.151-156
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• 2012

Objective: In 2010, the rate of injuries and illnesses in the shipbuilding industry was 1.20, about 1.74 times higher than the average of overall industries(0.69). Musculoskeletal disorders(MSDs) became a major problem since 2000 in shipbuilding industry. The purpose of this study was to provide efficient implementation management through evaluating the economic effectiveness of the Musculoskeletal Disorders Prevention Program(MDPP). Successfully implementing the MDPP in the workplace may decrease the risk of MSDs and therefore reduce MSDs related costs. Methods: Occupational accident index (frequency rate, severity rate, and frequency severity indicator), estimated direct costs, and total occupational accident occurrence rate were provided by analysis of MSDs, statistical analysis of MDPP decreed companies, and data analysis of implementation. Results: The study shows the number of MSDs for MDPP decreed companies decreased 76.2% from 2,319 in 2004 to 551 in 2008. Above all, the number of MSDs decreased 78.7% in Shipbuilding industries. Forty companies (85.1%) showed a decreasing tendency and 27.7% of those had an $R^2$ > 0.7. Similar results were found in severity rate and frequency severity indicator. From these results, it appears there are a number of advantages in implementing the MDPP. Conclusion: MDPP effectiveness was demonstrated by analysing implementation and occupational accident index. A more effective and efficient implementation would take into account business sector, size, policy, and organization of the company.

• Steel and Composite Structures
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• v.37 no.4
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• pp.391-404
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• 2020

Human-induced vibration could present a serious serviceability problem for large-span and/or lightweight floors using the high-strength material. This paper presents the results of heel-drop, jumping, and walking tests on a large-span composite steel rebar truss-reinforced concrete (CSBTRC) floor. The effects of human activities on the floor vibration behavior were investigated considering the parameters of peak acceleration, root-mean-square acceleration, maximum transient vibration value (MTVV), fundamental frequency, and damping ratio. The measured field test data were validated with the finite element and theoretical analysis results. A comprehensive comparison between the test results and current design codes was carried out. Based on the classical plate theory, a rational and simplified formula for determining the fundamental frequency for the CSBTRC floor is derived. Secondly, appropriate coefficients (β_rp) correlating the MTVV with peak acceleration are suggested for heel-drop, jumping, and walking excitations. Lastly, the linear oscillator model (LOM) is adopted to establish the governing equations for the human-structure interaction (HSI). The dynamic characteristics of the LOM (sprung mass, equivalent stiffness, and equivalent damping ratio) are determined by comparing the theoretical and experimental acceleration responses. The HSI effect will increase the acceleration response.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.2059-2064
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• 2004

Texture analysis is an important role for automatic visual insfection. This paper presents an application of wavelet extension and Gray level co-occurrence matrix (GLCM) for detection of defect encountered in textured images. Texture characteristic in low quality images is not to easy task to perform caused by noise, low frequency and small dimension. In order to solve this problem, we have developed a procedure called wavelet image extension. Wavelet extension procedure is used to determine the frequency bands carrying the most information about the texture by decomposing images into multiple frequency bands and to form an image approximation with higher resolution. Thus, wavelet extension procedure offers the ability to robust feature extraction in images. Then the features are extracted from the co-occurrence matrices computed from the sub-bands which performed by partitioning the texture image into sub-window. In the detection part, Mahalanobis distance classifier is used to decide whether the test image is defective or non defective.

• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.9
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• pp.270-275
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• 2012

This paper describes design of a variable-N frequency synthesizer for RF PLL with $0.13{\mu}m$ silicon CMOS technology being used as an application of the UWB system like MBOA. To get good performance of speed and noise super dynamic circuits was used, and to get variable-N division ratio MOSFET switching circuits was used. Especially to solve narrow bandwidth problem of the dynamic circuits load resistance value of unit divider block was varied. Simulation results of the designed circuit shows very fast and wide operation characteristics as 5~26GHz frequency range.

• Journal of Korea Multimedia Society
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• v.21 no.2
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• pp.211-223
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• 2018

To understand the meaning of data is a common goal of research on unstructured data. Among these unstructured data, there are difficulties in analyzing the meaning of unstructured data related to corpus and sentences. In the existing researches, the researchers used LSA to select sentences with the most similar meaning to specific words of the sentences. However, it is problematic to examine many sentences continuously. In order to solve unstructured data classification problem, several search sites are available to classify the frequency of words and to serve to users. In this paper, we propose a method of classifying documents by using the frequency of similar words, and the frequency of non-relevant words to be applied as weights, and storing them in terms of a multi-pattern storage. We use Tensorflow's Softmax to the nearby sentences for machine learning, and utilize it for unstructured data analysis and the inference of traffic information.

• Journal of Magnetics
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• v.21 no.3
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• pp.442-449
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• 2016

In this paper, an effective numerical analysis method is proposed for calculating dosimetry of the wireless power transfer system operating low-frequency ranges. The finite-difference time-domain (FDTD) method is widely used to analyze bio-electromagnetic field problems, which require high resolution, such as a heterogeneous whole-body voxel human model. However, applying the standard method in the low-frequency band incurs an inordinate number of time steps. We overcome this problem by proposing a modified finite-difference time-domain method which utilizes a quasi-static approximation with the surface equivalence theorem. The analysis results of the simple model by using proposed method are in good agreement with those from a commercial electromagnetic simulator. A simulation of the induced electric fields in a human head voxel model exposed to a wireless power transmission system provides a realistic example of an application of the proposed method. The simulation results of the realistic human model with the proposed method are verified by comparing it with the conventional FDTD method.

• Composites Research
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• v.13 no.1
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• pp.61-68
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• 2000

A new approach is presented for the analysis of transient waves propagating in anisotropic composite laminates. The wavelet transform (WT) using the Gabor wavelet is applied to the time-frequency analysis of dispersive flexural waves. It is shown that the peaks of the magnitude of WT in time-frequency domain is related to the arrival times of group velocity. Experiments are performed using a lead break as the simulated fracture source on the surface of quasi-isotropic and unidirectional laminates. For predictions of the dispersion of the flexural mode, Mindlin plate theory is shown to give good agreement with the experimental results. Based on the frequency-dependent arrival times and angular dependence of group velocities of flexural waves, the problem of source location in anisotropic laminates is considered and the results are given.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.6
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• pp.669-676
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• 2008

The adaptive resource optimization problem in multi-input multi-output orthogonal frequency division multiple access (MIMO-OFDMA) systems is addressed. This paper, adaptive modulation and coding(AMC) and power control algorithms is proposed with SFC(Space-Frequency Coding), which aims to maximize the system capacity based on the CQI(Channel Quality Information). Firstly, power level is decided to each sub-channels with received feedback signal to noise ratio(SNR). In the second step, sub-carriers are allocated according to modulation type. Simulation results show that the proposed algorithm achieves a better performance than conventional algorithm in terms of capacity.

• Korean Journal of Community Nutrition
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• v.8 no.3
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• pp.311-318
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• 2003

The aim of this study was to assess the nutrient intakes of the elderly subjects in Korea. Dietary assessment was carried out using a semi-quantitative food frequency questionnaire (SQFFQ) developed by our laboratory, which included 98 commonly consumed food items selected from 1998 National Health and Nutritional Survey for Korean population. Subjects (n = 2,660) aged 50yr and over were recruited in Seoul, 6 metropolitan cities, and 8 mid-size cities. Calcium and riboflavin intakes of the elderly subjects aged 65 yr and over (n = 1,974) were much lower compared with Korean RDA. Nutrient intakes of the three age group (50-64 yr, 65-74 yr, 75 yr and over) were decreased as age increased in male and female elderly. Nutrient intakes of male elderly, 75 yr and over, were significantly decreased while in female elderly nutrient intakes were gradually decreased as age increased. Over 30% of the elderly subjects did not meet 75% RDA for calcium, iron, vitamin A, and riboflavin. The proportion of the elderly subjects whose intakes were below 75% RDA was much higher than the elderly whose intakes were above 125% RDA, especially among the elderly aged 75 yr and over. This study revealed that the Korean elderly had inadequate intakes for many nutrients. This will cause a serious nutritional problem for the elderly.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.1122-1127
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• 2004

an isolated droplet combustion exposed to pressure perturbations in stagnant gaseous environment is numerically conducted. Governing equations are solved for flow parameters at gas and liquid phases separately and thermodynamic parameters at the interfacial boundary are matched for problem closure. For high-pressure effects, vapor-liquid interfacial thermodynamics is rigorously treated. A series of parametric calculations in terms of mean pressure level and wave frequencies are carried out employing a n-pentane droplet in stagnant gaseous air. Results show that the operating pressure and driving frequency have an important role in determining the amplitude and phase lag of a combustion response. Mass evaporation rate responding to pressure waves is amplified with increase in pressure due to substantial reduction in latent heat of vaporization. Phase difference between pressure and evaporation rate decreases due to the reduced thermal inertia at high pressure. In addition to this, augmentation of perturbation frequency also enhances amplification of vaporization rate because the time period for the pressure oscillation is much smaller than the liquid thermal inertia time. The phase of evaporation rate shifts backward due to the elevated thermal inertia at high acoustic frequency.