• Earthquakes and Structures
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• v.16 no.1
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• pp.69-82
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• 2019

As the residual displacement and/or drift demands are commonly used for seismic assessment of buildings, the estimation of these values play a very critical role through earthquake design philosophy. The residual displacement estimation of fixed base structures has been the topic of numerous researches up to now, but the effect of soil flexibility is almost always omitted. In this study, residual displacement demands are investigated for SDOF systems with period range of 0.1-3.0 s for near-field and far-field ground motions for both fixed and interacting cases. The elastoplastic model is used to represent non-degrading structures. Based on time history analyses, a new simple yet effective equation is proposed for residual displacement demand of any system whether fixed base or interacting as a function of structural period, lateral strength ratio and spectral displacement.

• The Journal of the Acoustical Society of Korea
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• v.38 no.5
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• pp.511-521
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• 2019

In this study, we theoretically study the acoustic scattering of an obliquely incident plane wave from a finite elastic cylindrical shell. A heuristic scattering method of Ye [Z. Ye, J. Acoust. Soc. Am. 102, 877-884 (1997)] for a finite fluid cylinder is extended into a finite elastic cylindrical shell since no analytic solutions exist in the finite cylinder. The elastic cylindrical shell is modeled with the 3D elastic wave theory considering internal fluid. Using the derived analytic solution, we observe the effect of the internal fluid on the scattering field, the scattering field for the Rayleigh parameter, and the far-field scattering function for the elastic property of the cylindrical shell.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.05a
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• pp.527-528
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• 2017

Current-voltage characteristics of source-overlapped gate tunnel field-effect transistor (SOG-TFET) with different channel doping concentration are proposed. Due to the gaussian doping in which the channel region near the source is highly doped and that far from the source is lightly doped, the ambipolar current was reduced, compared with the uniformly-doped SOG-TFET. On-current is almost similar in P-P-N and P-I-N structure but subthreshold swing (SS) of P-P-N TFET enhanced 5 times higher than those of P-I-N TFET. off-current and ambiploar current of the proposed SOG-TFET decrease 10 times and 100 times than those of the uniformly-doped SOG-TFET.

• Journal of the Korean Ceramic Society
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• v.56 no.6
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• pp.549-557
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• 2019

More than two decades of world-wide research efforts have resulted in several classes of potentially important materials. Among them are incipient piezoelectrics, which are especially useful for actuator applications. However, relatively large electric fields are required for activating the large incipient electromechanical strains. So far, many attempts have been made to reduce the required electric field by intentionally inhomogenizing the electric field distribution in the microstructure through core-shell and composite approaches. Here, we show that electric field concentration can be realized simply by adjusting electrode patterns. We have investigated the effect of electrode patterning on the incipient electromechanical strain properties of an exemplarily chosen lead-free relaxor system, revealing that electrode patterning does have a significant role on the strain properties of the given lead-free relaxor system. We believe that this approach would make a new strategy for ones to consider bringing the functional properties of electroceramics beyond their conventional limit.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.16 no.2
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• pp.143-152
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• 2021

Recently, universities are being requested to educate a wider range of technical and social skills in order to respond to the government's policy for promoting youth employment and the industrial demand arising from social changes. Accordingly, field practice at universities is being further strengthened. It is important to analyze whether the work experience and information that students gained through field practice can improve their confidence in their career path, and can serve as a motive for not only employment but also start-up after graduation. In this study, the motivational aspect which leads to action by improving students' confidence in their career path is investigated. In addition, the influence of field practice experience on employability and entrepreneurial intention is also analyzed by setting a self-directed career attitude as a variables. The results of this study are as follows. First, the field practice experience of college students has a significant effect on employability, but does not directly affect their entrepreneurial intention. Second, it is confirmed that the higher the self-directed career attitude of students with experience of field practice has a positive (+) effect on the employability. Third, the higher the self-directed career attitude has also a positive (+) effect on entrepreneurial intention. This study shows the influence of field practice on employability and entrepreneurial intention beyond the limit of the existing research that was divided into employment and start-up. Theoretical basis for analyzing whether universities can achieve practical results simultaneously in government policy for employment and start-up is also provided.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.522-522
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• 2015

In this study, the effect of threshold applied to the radar rain rate on the comparison of the radar and rain gauge rain rate was theoretically examined. The result derived was also evaluated theoretically, using the Bernoulli random field, and empirically, using Mt. Kwanak weather radar data. The results are summarized as follows. (1) In the application to the Bernoulli random field, it was found that the comparison of the radar and rain gauge rain rate with threshold does not introduce any systematic bias. (2) The same results could also be derived in the application to Mt Kwanak weather radar data. In all cases with several radar bin sizes and thresholds considered, the bias was estimated to be far less than 10% of the mean of the rain gauge rain rate. (3) However, in the comparison with threshold applied to both the radar and rain gauge rain rate, the bias was estimated to be higher than 20%. That is, the systematic bias was introduced. This result indicates that the comparison with threshold applied to both the radar and rain gauge rain rate should not be used.

• Journal of The Korean Society of Agricultural Engineers
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• v.49 no.1
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• pp.79-88
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• 2007

We investigated the characteristics of temperature variations under different land covers (paddy field, upland, urban park, and urban residential area) during hot summer (July 15 to August 19, 2005). The temperatures were monitored using data loggers at one hour intervals in study sites. The mean temperature generally increased with the distance from edge of paddy fields, being $1.5^{\circ}C$ higher at a site 170-m far from paddy fields than at a paddy field area at 22 h. The mean daily temperatures in the study period followed the ordo. of paddy field $(26.6^{\circ}C)$ < upland $(27.0^{\circ}C)$ < park $(27.5^{\circ}C)$ < residential area $(28.0^{\circ}C)$. The paddy field area has shown remarkable cooling effects compared to the residential area: Mean duration of temperature below $25^{\circ}C$ in the paddy field area was longer (8.6 hrs) than in the residential area; The time to fall to below $25^{\circ}C$ in the paddy field area was sooner (22.4 hr) than in the residential area; Mean daily minimum temperature in the paddy field area was much lower $(2.4^{\circ}C)$ than in the residential area. More research is needed to better clarify the mechanism of cooling effect of a paddy field area by investigating heat balance of a paddy field.

• Advances in nano research
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• v.1 no.4
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• pp.203-210
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• 2013

So far, all reviews and control approaches of spin relaxation have been done on lateral single electron quantum dots. In such structures, many efforts have been done, in order to eliminate spin-lattice relaxation, to obtain equal Rashba and linear Dresselhaus parameters. But, ratio of these parameters can be adjustable up to 0.7 in a material like GaAs under high-electric field magnitudes. In this article we have proposed a single electron QD structure, where confinements in all of three directions are considered to be almost identical. In this case the effect of cubic Dresselhaus interaction will have a significant amount, which undermines the linear effect of Dresselhaus while it was destructive in lateral QDs. Then it enhances the ratio of the Rashba and Dresselhaus parameters in the proposed structure as much as required and decreases the spin states up and down mixing and the deviation angle from the net spin-down As a result to the least possible value.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.25 no.1
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• pp.33-39
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• 2015

This paper investigates the underwater acoustic radiation from a periodically stiffened cylindrical shell excited resiliently mounted machinery. Underwater acoustic radiation is important to a submarine. Generally, submarine structure can be modeled as stiffened cylindrical shell immersed in water. Analytical model is derived for the far-field acoustic radiation from machinery installed inside cylindrical shell. The analytical model includes the effect of fluid loading and interactions between periodic ring stiffeners. Transmitted force from machine to a shell through isolator can be different by the impedance of shell. In this paper the effect of a shell impedance for acoustic radiation is investigated. Impedance of a shell should be considered if thickness of a shell is thin.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.04a
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• pp.644-649
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• 2014

Analytical model is derived for the far-field acoustic radiation from machinery installed inside cylindrical shell. The analytical model includes the effect of fluid loading and interactions between periodic ring supports. Transmitted force from machine to a shell can be different by the impedance of shell. In this paper the transmitted force from machinery to a infinite shell through vibration isolator is considered by the impedance of shell. The effect of the shell impedance for acoustic radiation is investigated.