• International journal of steel structures
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• v.18 no.4
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• pp.1210-1218
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• 2018

A new type of earthquake-resisting element that consists of a steel plate shear wall with slits is introduced. The infill steel plate is divided into a series of vertical flexural links with vertical links. The steel plate shear walls absorb energy by means of in-plane bending deformation of the flexural links and the energy dissipation capacity of the plastic hinges formed at both ends of the flexural links when under lateral loads. In this paper, finite element analysis and experimental studies at low cyclic loadings were conducted on specimens with steel plate shear walls with multilayer slits. The effects caused by varied slit pattern in terms of slit design parameters on lateral stiffness, ultimate bearing capacity and hysteretic behavior of the shear walls were analyzed. Results showed that the failure mode of steel plate shear walls with a single-layer slit was more likely to be out-of-plane buckling of the flexural links. As a result, the lateral stiffness and the ultimate bearing capacity were relatively lower when the precondition of the total height of the vertical slits remained the same. Differently, the failure mode of steel plate shear walls with multilayer slits was prone to global buckling of the infill steel plates; more obvious tensile fields provided evidence to the fact of higher lateral stiffness and excellent ultimate bearing capacity. It was also concluded that multilayer specimens exhibited better energy dissipation capacity compared with single-layer plate shear walls.

• Journal of the Earthquake Engineering Society of Korea
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• v.27 no.1
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• pp.37-47
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• 2023

A new clamped mechanical splice system was proposed to develop structural performance and constructability for precast concrete connections. The proposed mechanical splice resists external loading immediately after the engagement. The mechanical splices applicable for both large-scale rebars for plants and small-scale rebars for buildings were developed with the same design concept. Quasi-static lateral cyclic loading tests were conducted with reinforced and precast concrete members to verify the seismic performance. Also, shaking table tests with three types of seismic wave excitation, 1) random wave with white noise, 2) the 2016 Gyeongju earthquake, and 3) the 1999 Chi-Chi earthquake, were conducted to confirm the dynamic performance. All tests were performed with real-scale concrete specimens. Sensors measured the lateral load, acceleration, displacement, crack pattern, and secant system stiffness, and energy dissipation was determined by lateral load-displacement relation. As a result, the precast specimen provided the emulative performance with RC. In the shaking table tests, PC frames' maximum acceleration and displacement response were amplified 1.57 - 2.85 and 2.20 - 2.92 times compared to the ground motions. The precast specimens utilizing clamped mechanical splice showed ductile behavior with energy dissipation capacity against strong motion earthquakes.

• Journal of the Microelectronics and Packaging Society
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• v.18 no.3
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• pp.59-65
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• 2011

According to the trends of electronic package to be smaller, thinner and more integrative, Flip Chip Ball Grid Array (FCBGA) become more used for mobile phone. However, the flip chip necessarily generate the heat by the electrical resistance and generated heat is increased due to reduced distribution area of the heat in accordance with the miniaturization trend of the package. Thermal issues can result in problems of devices that are sensitive to temperature and stress. Then the heat can generate problems to the system. In this paper, in order to improve the thermal issues of FCBGA, thermal characteristics of FCBGA was analyzed qualitatively by using the general heat transfer module of Comsol 3.5a and In order to solve thermal issues, flip chip with new micro structure is proposed by the simulation. and also by comparing existing model and analyzing variables such as pitch, height of the pattern and shape of the heat spreader, the improvement of heat dissipation characteristics about 18% was confirmed.

• The Bulletin of The Korean Astronomical Society
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• v.38 no.2
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• pp.39.1-39.1
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• 2013

We use high-resolution hydrodynamic simulations to study nonlinear gas responses to imposed non-axisymmetric stellar potentials in barred-spiral galaxies. The gas is assumed to be infinitesimally thin, isothermal, and unmagnetized. We consider various spiral-arm models with differing strength and pattern speed, while fixing the bar parameters. We find that the extent and shapes of spiral shocks as well as the related mass drift depend rather sensitively on the pattern speed. In models where the arm pattern is rotating more slowly than the bar, the gaseous arms extend from the bar ends all the way to the outer boundary, with a pitch angle slightly smaller than that of the stellar counterpart. The arms drive mass inflows at a rate of ${\sim}0.5-2.5M{\odot}/yr$ to the bar region to which the shock dissipation, external torque, and self-gravitational torque contribute about 50%, 40%, and 10%, respectively. About 85% of the inflowing mass is added to bar substructures such as an inner ring, dust lanes, and a nuclear ring. while the remaining 15% encircles the bar region. On the other hand, models where the arms corotate with the bar exhibit mass outflows, rather than inflows, over most of the arm region. In these models, spiral shocks are much more tightly wound than the stellar arms and cease to exist in the region where $M{\bot}/sinp*{\geq}25-40$, where $M{\bot}$ denotes the Mach number of a rotating gas perpendicular to the arms with pitch angle p*. We demonstrate that the distributions of line-of-sight velocities and densities can be a useful diagnostic tool to distinguish if the arms and bar corotate or not.

• Korean Journal of Environmental Agriculture
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• v.34 no.2
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• pp.120-127
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• 2015

BACKGROUND: Supervised residue trials were conducted to establish pre-harvest residue limit(PHRL), a criterion to ensure the safety of the pesticide residue in the crop harvest, of amisulbrom for winter-grown cabbage in two fields. Following to application of amisulbrom on the crop, time-course study was carried out to obtain the amisulbrom dissipation of statistical significance which enabled to calculate the predicted values of PHRL. METHOD AND RESULTS: During cultivation under greenhouse condition, samples of winter-grown cabbage were collected at 0, 1, 3, 5, 7 and 10 days after amisulbrom application, and subjected to residue analysis. Analytical method was validated by recoveries ranging 93.7~100.0% as well as limit of quantitation(LOQ) of 0.04 mg/kg. Amisulbrom residues in winter-grown cabbage gradually decreased as time elapsed. The dissipation rate of the residue would be affected by intrinsic degradation along with dilution by the cabbage growth. The decay pattern was well fitted by the simple first-order kinetics. CONCLUSION: Biological half-lives of amisulbrom in winter-grown cabbage ranged 3.7~4.1 days in two field conditions. Based on the regression of amisulbrom dissipation, PHRLs of amisulbrom in winter-grown cabbage were recommended as 8.86~9.47 and 4.21~4.35 mg/kg for 10 and 5 days before harvest, respectively.

• Korean Journal of Environmental Agriculture
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• v.23 no.3
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• pp.142-147
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• 2004

Dissipation pattern of tebuconazole was evaluated by establishing application methods of the fungicide, paper-bagging of grape during growth and washing of grape after harvest. Application times increased from three to five resulted in high levels of residues in grape. Tebuconazole in grapes was present in different residual patterns with periods after final treatment ranging from 7 to 25 days. Significant differences in the residual patterns were also found when tebuconazole was treated during three different application periods, possibly due to meteorological condition and/or grape growth during each period. At the range from 2.5 g to 7.5 g of grape granules, residues were higher in small-sized grape than in big-sized grape and were mostly distributed on the peel of the grapes. Paper-bagging was a critical factor for reducing the fungicide residue on the peel. flesh of bagged and no-bagged grape had very low level of residues, 0.01 mg/kg and 0.05 mg/kg, respectively. Residues on grape was effectively eliminated with the washing methods suggested, a consecutive sinking-washing system Using of detergent solution during washing showed maximum residue reduction from grape. The washing methods showed effective action on the removal of lower content providing complete elimination, or almost, of the residues.

• Korean Journal of Environmental Agriculture
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• v.34 no.3
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• pp.223-229
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• 2015

BACKGROUND: It is important to understand residual patterns of pesticides applied on crops for ensuring their safety in agricultural products. However, there are few studies on the residual patterns of pesticides in minor crops, which are small in cultivation area. In this study, residual amounts of bifenthrin and chlorfenapyr sprayed on perilla leaf as a minor crop were investigated to know their residual patterns. METHODS AND RESULTS: Bifenthrin and chlorfenapyr were sprayed 2 or 3 times on perilla leaves at a week interval prior to harvest, and the perilla leaves were collected at 0, 1, 3, 5 and 7 days after the final application of pesticides. Recoveries for residual analysis of pesticides spiked on perilla leaves with concentrations of 0.1 and 0.5 mg/kg were 81.9-104.8%. The residual amounts of pesticides interpreted using first order kinetics model show that dissipation constants of bifenthrin and chlorfenapyr in perilla leaves were 0.0724-0.0535 and $0.0948-0.0821day^{-1}$, respectively. In addition, the dissipation half-lives in perilla leaves were 9.6-12.9 days for bifenthrin and 7.3-8.4 days for chlorfenapyr. When pre-harvest residue limits (PHRL) of bifenthrin and chlorfenapyr at 10 days before harvest calculated on the basis of the dissipation constants and maximum residue limits of the pesticides were calculated as 17.1 for bifenthrin and 15.9 mg/kg for chlorfenapyr. CONCLUSION: Therefore, the PHRL calculated using the time-dependant residual patterns of pesticides in perilla leaves and their regression analysis may be used as experimental evidences in order to ensure the safety of pesticides in perilla leaves before harvest.

• Korean Journal of Environmental Agriculture
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• v.30 no.4
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• pp.446-452
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• 2011

BACKGROUND: To investigate the dissipation patterns of 3 pesticides, azoxystrobin, difenoconazole and iprodione, on green garlic after field treatment pesticides were treated as foliar treatment by single application at recommended and double the recommended rates. METHODS AND RESULTS: Residue samples were harvested at 0, 1, 2, 5, 7 and 10 days post-treatment for azoxystrobin and 0, 1, 2, 5, 7, 10, 15 and 21 days post-treatment for difenoconazole and iprodione. After preparation the fortified samples were extracted and analyzed by gas chromotography-electron capture detector (GC-ECD) to determine the residue levels. Recoveries ranged from 87 to 109% for azoxystrobin, difenoconazole and iprodione at two different levels. The limit of Quantification (LOQ) values were 0.002 mg/kg for azoxystrobin and difenoconazole and 0.01 mg/kg for iprodione. CONCLUSION(S): Half-lives of azoxystrobin, difenoconazole and iprodione in green garlic after treatment were 1.2, 3.8 and 3.2 days at recommended and 1.4, 3.3 and 3.2 at double the recommended rate, respectively. Residue level of azoxystrobin, difenoconazole and iprodione in green garlic were below the maximum residue limits (MRLs) at 0 day, 0 day and 5 days, respectively. Therefore, these pesticide were considered that residues was satisfied to the requirement of domestic trade related to the consumer safety.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.6
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• pp.64-72
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• 2022

In this study, in order to confirm the seismic performance of reinforced concrete frames retrofitted with Wall Friction Damper(WFD), the test was conducted by setting two-story Reinforced concrete frames (reference specimen, OMF-N and specimen retrofitted with internal H-shaped steel frame and WFD, OMF-ALL(H)) as main variables. The WFD Seismic Retrofit Method is a mixture of strength improvement and energy dissipation methods. To prevent the pre-destruction of existing structure by friction force before sufficient energy dissipation of WFD, the internal H-shaped steel frame and chemical anchor that penetrates the side of the beam were used to install WFD. According to the test results, the OMF-N specimen showed an brittle failure pattern caused by the shear force of the R/C column after the maximum strength was expressed. The OMF-ALL(H) specimen showed that the reduction of pinching effect and the failure of the RC column occurred. Also, the maximum strength, cumulative energy dissipation and ductility of OMF-ALL(H) increased 3.01 times, 7.2 times and 1.72 times for OMF-N. As a results, test results revealed that the WFD Seismic Retrofit Method installed on Reinforced concrete structure improves the seismic performance and the strengthening effect is valid.

• The Korean Journal of Pesticide Science
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• v.21 no.1
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• pp.17-25
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• 2017

Dissipation pattern and biological half-lives of fungicides boscalid and pyraclostrobin were calculated on jujube. The pesticides were sprayed on jujube in two different field at the standard rate, respectively. The raw agricultural commodities were harvested at 0 (2 hr), 1, 3, 5, 7, 10 and 14 days after treatment, and analyzed by HPLC/DAD. The method limit of quantification (MLOQ) was $0.02mg\;kg^{-1}$ for boscalid and pyraclostrobin. The recovery ranged 101.8~109.3% with below 5% of CV (Coefficient of variation) for boscalid and 104.2~115.4% with below 5% of CV for pyraclostrobin. An average initial deposit at field 1 and field 2 samples were observed 0.40 and $0.48mg\;kg^{-1}$ for boscalid and, 0.76 and $0.57mg\;kg^{-1}$ for pyraclostrobin, respectively. The biological half-lives of field 1 and field 2 were 11.0 and 13.2 day for boscalid, and 6.1 and 12.7 days for pyraclostrobin.