• Asian Pacific Journal of Cancer Prevention
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• v.16 no.16
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• pp.7291-7294
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• 2015

Purpsoe: To investigate the diagnostic value of quantitative analysis of a tissue diffusion and virtual touch tissue imaging quantification (VTIQ) technique with acoustic radiation force impulse (ARFI) elastography for assessing enlarged cervical lymph nodes. Materials and Methods: Fifty-six enlarged cervical lymph nodes confirmed by pathologic diagnoses were covered in the study. According to the results of pathologic diagnosis, patients were classified into benign and malignant groups. All the patients were examined by both conventional ultrasonography and elastography. AREA% and shear wave velocity (SWV) in ROI of different groups were calculated and compared using ROC curves. Cut-off points of AREA% and SWV were determined with receiver operating characteristic curves. Results: Final histopathological results revealed 21 cases of benign and 35 cases of malignant lymph nodes. The mean values of AREA% and SWV in benign and malignant groups were $45.0{\pm}17.9%$ and $2.32{\pm}0.57m/s$, and $61.3{\pm}21.29%$ and $4.36{\pm}1.25$)m/s, respectively. For the parameters of elastography, "AREA%" and SWV demonstrated significant differences between groups (p=0.002). AREA% was positively correlated with SWV with a correlation coefficient of 0.809 (P<0.001). Conclusions: Stiffness of different lymph node diseases in patients may differ. Elastography can evaluate changes sensitively and provide valuable information to doctors. The study proved that the VTIQ elastography technique can play an important role in differential diagnosis of lymph nodes.

• The Journal of the Acoustical Society of Korea
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• v.32 no.4
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• pp.361-368
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• 2013

As one way to describe the behavior of a vibrating string, analogies to a transmission line have been made based on the fact that they have oppositely travelling waves on each of them. In such analogies, a rigid end to the string has been represented as an open circuit, and the displacement of the string as the current on the transmission line. However it turns out that the rigid end corresponds to a short circuit, the displacement to the voltage by the theory of the transmission line, and it is confirmed by experiments with circuit simulations. Based on these discoveries, a transmission line based plucked string model comprising a transmission line, two piecewise linear current sources, and switches is proposed. The proposed model is validated by showing that the voltage at the arbitrarily chosen location, and the voltage calculated over an infinitesimal portion at the end of the transmission line are consistent with the displacement at the corresponding location and the force on the rigid end of the string from the well known difference form of a wave equation governing the behavior of the string with its fundamental frequency tuned to that for the proposed model, respectively. Moreover, the applicability of the proposed model to modeling string and wind instruments is presented.

• Ocean and Polar Research
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• v.39 no.3
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• pp.205-211
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• 2017

This paper seeks to provide a dynamic analysis of a 150 ton winch based on ocean environmental data. The winch model that was subjected to analysis was modeled from CAD to each subsystem by the commercial software DAFUL. The winch model has tree brake systems (disk brake, band brake and ratchet brake). The rotation motion of the motor and contact elements of the brake are applied to the winch model in order to analyze its dynamic characteristics. In addition, a crane-barge was modeled to apply ocean environmental data. The motion data of the crane-barge was produced by means of the RAO(Response Amplitude Operator) of the barge and wave spectrum. The reaction force of the translational joint was measured instead of the tension of the cable. The brake performance of the winch was produced and assessed based on the operating motion of the crane-barge.

• Journal of the Korean association of regional geographers
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• v.22 no.3
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• pp.714-729
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• 2016

National citizenship has been empathized by nation-state since modern times. But with recent wave of globalization, the force of national citizenship is gradually reducing. Globalization requires citizens of global citizenship needed in the global village on the one hand, and of cultural citizenship suited in multicultural society on the other hand. The trend shows that the geographical focus of citizenship is shifted or expanded from the political domain to the social and cultural domain. Moreover, with concerns of personal everyday life citizenship is extended from standard personality by Western view to inclusion and exclusion in micro everyday space, non-Western view based on social difference of gender, class, ethnicity etc. New spaces of citizenship, cultural citizenship and everyday citizenship which empathizes personal right and difference is emerging instead of national citizenship based on personal allegiance and duty of the state. This means that the state has not only a task of establishment of common national citizenship, but also a challenge to recognize of diversity of citizens.

• Journal of Conservation Science
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• v.31 no.3
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• pp.267-278
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• 2015

In this study, the elastomer cover, a new contact material, was developed to establish the customized ultrasonic measurement considering surface irregularities of stone cultural heritages. The cover exhibits high elastic force and wear resistance because it has tensile strength of 17MPa and elongation of 625%. In addition, as a result of comparative experiments for the seven types according to transducers and contact materials including the elastomer cover, rock surface irregularities significantly affect attenuation of ultrasonic velocity. The phenomenon was more noticeable in the chiseling finish and indirect transmission measurement rather than the dabbed finish and direct transmission measurement. However, the Type F using the exponential transducer and elastomer cover showed stable P-wave velocity and high amplitude regardless of the surface irregularities. This because the elastomer cover sufficiently sticks to surface irregularities and removes pores between a transducer and a rock specimen. Therefore, the Type F should be used for the ultrasonic measurement of stone cultural heritages with surface irregularities.

• Journal of the Society of Naval Architects of Korea
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• v.37 no.1
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• pp.67-81
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• 2000

An accurate and efficient numerical method for two-dimensional nonlinear radiation problem has been developed. The wave motion due to a moving body is described by the assumption of ideal fluid flow, and the governing Laplace equation can be effectively solved by the higher-order boundary element method with the help of the GMRES (Generalized Minimal RESidual) algorithm. The intersection or corner problem is resolved by utilizing the so-called discontinuous elements. The implicit trapezoidal rule is used in updating solutions at new time steps by considering stability and accuracy. Traveling waves caused by the oscillating body are absorbed downstream by the damping zone technique. It is demonstrated that the present method for time marching and radiation condition works efficiently for nonlinear radiation problem. To avoid the numerical instability enhanced by the local gathering of grid points, the regriding technique is employed so that all the grids on the free surface may be distributed with an equal distance. This makes it possible to reduce time interval and improve numerical stability. Special attention is paid to the local flow around the body during time integration. The nonlinear radiation force is calculated by the "acceleration potential technique". Present results show good agreement with other numerical computations and experiments.

• Geotechnical Engineering
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• v.9 no.1
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• pp.7-20
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• 1993

The first Korean earthquake resistant design code was enacted in 1988. In the code, the soil factor which takes into account both the soil amplification factor and the soil -structare interaction effect is divided into three groups : soil factor, 5 : 1.0, 1.2 and 1.5. In order to assist in choosing the soil factors appropriately in the earthquake resistant design, the local site effects on the based shear force induced by earthquakes are considered in depth for typical soil conditions in Korea. The depth of the alluvial and/or weathered zone is usually not deep and the fresh rock is found at depth shallower than 20 meters, and even at about 10 meters around Seoul. One dimensional wave propagation theory and the elastic half space method are used to obtain the soil -structure interaction effect as well as the soil amplification effect. The kinematic interaction effect due to scattering of waves by pile foundation is also considered. Finally, the soil factor is recommended for each soil condition from loose state to dense, and also from shallow soil depth to deep, so that the designer can choose the factor with-out difficulty.

• Korean Journal of Social Welfare
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• v.64 no.2
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• pp.55-83
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• 2012

Self-employment rate is high in Korean labor market, while the income gap within self-employed is also high. Although, there are very few studies that addressed on the income inequality of self-employed. Thus, this study has measured the earnings inequality of self-employed by generalized entropy indices and decomposed inequality factor and trend. The empirical study is based on Korea Welfare Panel Study wave 1~4. The main result from this analysis is summarized in three points. Firstly, earnings inequality of self-employed is severely high and the earnings polarization within self-employed has become more serious in Korea. Secondly, this study provides the evidence that the main factor of earnings inequality of self-employed is the status of self-employment, education level, age group, workplace scale and industry. Thirdly, the contribution of relative changes in the incomes of the status of self-employment is the largest to the inequality trend. In terms of education level, age group and industry, the increase of inequality within group(pure effect) mainly attributes to the rise of earnings inequality of self-employed and the change effect of group composition contributes to deterioration of inequality.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.3
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• pp.231-236
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• 2015

Investigations into cavity flows have been conducted for decades now, most of them being about zero-pressure-gradient flows entering a cavity on a straight wall. However, the flow over curved walls in real-life situations has not been fully investigated. As cavity flows on curved walls exert centrifugal force, these walls are likely to possess different features from straight walls. To verify this possibility, this study investigated cavity flows on curved walls. Using numerical method, the effect of two variables, namely, radius of curvature on a curved wall and inlet Mach number, were investigated for subsonic and supersonic cavity flows. The result demonstrates that the value of the peak pressure generated inside the cavity increases with the decrease in the radius of curvature on a curved wall or an increase in the inlet Mach number. The total pressure loss in the cavity also results in an increase in the cavity drag.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.942-945
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• 2005

Micron-sized metal wires are widely used in industries such as filtration, catalyst and composite materials, etc. In the wire drawing process, the die that is used conventionally is an effective and, at the same time, sensitive component. However, a typical array of the dies has caused many problems in the wire drawing process, e.g., large frictional force on the interface between wire and the resulting high heat generation, precise adjustment of the dies, extended cooling system, die abrasion, etc.. Because of these problems, there have been many works that are aiming at improving the efficiency of wire drawing process by analyzing the die geometry and by applying advanced die material to prolong the die life or even at developing a dieless wire drawing system. This paper is dealing with developing a new wire drawing system that is applicable to reduce the wire drawing steps with high draw ratio. The new wire drawing system does not use the dies, but use the self-induced heater that works on the basis of the resonant phenomenon of wire material. The electromagnetic wave is the heating source. The results of the study on the diameter reduction and microwave flow analysis show that the heating effectiveness of the wire is influenced by the energy distribution in the microwave propagation chamber. We can obtain diameter-reduced wires by using microwave in the dieless drawing process. Microwave as a heating source is capable of producing wires without applying dies in wire drawing process.