• Transactions of the Korean Society of Automotive Engineers
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• v.24 no.3
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• pp.273-278
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• 2016

This study makes a relative comparison of the results of tensile test and quasi-static analysis using AGL(Adjuster Guide Loop) model that plays a role in adjusting the height of shoulder belt, of the components of the vehicle seatbelt system and attempts to propose a method of reducing the error rate of the quasi-static analysis technique effectively. This study selects two major factors affecting the result of an analysis, draws the result of analysis through the method of experimental design, one of the statistical techniques and understands the contribution rate of the major factors affecting the result of the analysis through ANOVA(Analysis of Variance).

• The Korean Journal of Ecology
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• v.22 no.6
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• pp.337-342
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• 1999

Rotifer grazing rates in both species and community levels on bacteria and phytoplankton were determined by using representative models (fluorescent beads: 0.75$\mu m$ for bacteria and 10 $\mu m$ for phytoplankton) at biweekly intervals. One-year study at the lower part of the Nakdong River (Mulgum) indicated that the seasonal pattern of rotifer biomass was similar to that of total zooplankton biomass. Total mean biomass of rotifers was significantly higher than that of other groups (rotifers, 148$\pm $327 $\mu g$C/l; cladoceran. 25$\pm 69$$\mu g$C/l; copepodids. 58$\pm 159$$\mu g$C/l). For laboratory grazing experiments. mean specific filtering rate (SFR: $ml\cdot \; l^{-1}\cdot \; day^{-1}$) for rotifers varied from 0.001 to 0.726, and > 90% individuals of rotifer species took up fluorescent microspheres. The high SFRs were achieved by Brachionus angularis, B. calyciflorus, and Filinia longiseta. Community filtering rates (CFRs, $ml\cdot \; l^{-1}\cdot \; day^{-1}$) varied in the range from 2 ~ 1,670. Rotifer filtering rates on phytoplankton were much higher than bacterial filtering rates, especially in the late growing season (May. June, and November). Rotifers appear to be important in transferring both bacterial and phytoplankton carbon to higher trophic levels at the lower Nakdong River.

• Transactions of Materials Processing
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• v.18 no.4
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• pp.317-322
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• 2009

Superplastic deformation behavior of a Zn-0.3 wt.% Al was investigated. Grain sizes of $1{\mu}m$ and $10{\mu}m$ were obtained by a thermomechanical treatment. A series of load relaxation and tensile tests were conducted at various temperatures ranging from RT ($24^{\circ}C$) to $200^{\circ}C$. A large elongation of 1400% was obtained at room temperature in the specimens with the grain size of $1{\mu}m$. In the case of specimens with the grain size of $10{\mu}m$, relatively lower elongation at room temperature was obtained and, as the temperature increases above $100^{\circ}C$, a high elongation of about 400 % has been obtained at $200^{\circ}C$ under the strain rate of $2{\times}10^{-4}/s$. Dynamic materials model (DMM) has been employed to explain the contribution from GBS of Zn-Al alloy. Power dissipation efficiency for GBS was evaluated as above 0.4 and found to be very close to the unity as strain rate decreased and temperature increased, suggesting that GBS could be regarded as Newtonian viscous flow.

• Journal of Korea Foundry Society
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• v.36 no.4
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• pp.117-125
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• 2016

The effects of the Zn content on the microstructure and corrosion behavior in 1M NaCl solution were investigated in Mg-(0~6)%Zn casting alloys. The MgZn phase was scarcely observed in the Mg-1%Zn alloy, while the Mg-(2~6)%Zn alloy consisted of ${\alpha}$-(Mg) and MgZn phases. With an increase in the Zn content, the amount of the MgZn phase was gradually increased. Immersion and electrochemical corrosion tests indicated that the Mg-1%Zn alloy had the lowest corrosion rate among the alloys, and a further increase in the Zn content resulted in the deterioration of the corrosion resistance. Microstructural examinations of the corroded surfaces and EIS analyses of surface corrosion films revealed that the best corrosion resistance at 1%Zn was associated with the absence of MgZn phase particles in the microstructure and the contribution of Zn element to the formation of a protective film on the surface. A micro-galvanic effect by the MgZn particles led to the increased rate of corrosion at a higher Zn content.

• Asian-Australasian Journal of Animal Sciences
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• v.22 no.7
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• pp.931-936
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• 2009

Body weights of 862 Angora goats between birth and 36 months of age, recorded on a semiyearly basis from 1988 to 2000, were used to estimate genetic, permanent environmental and phenotypic covariance functions. These functions were estimated by fitting a random regression model with 6th order polynomial for direct additive genetic and animal permanent environmental effects and 4th and 5th order polynomial for maternal genetic and permanent environmental effects, respectively. A phenotypic covariance function was estimated by modelling overall animal and maternal effects. The results showed that the most variable coefficient was the intercept for both direct and maternal additive genetic effects. The direct additive genetic (co)variances increased with age and reached a maximum at about 30 months, whereas the maternal additive genetic (co)variances increased rapidly from birth and reached a maximum at weaning, and then decreased with age. Animal permanent environmental (co)variances increased with age from birth to 30 months with lower rate before 12 months and higher rate between 12 and 30 months. Maternal permanent environmental (co)variances changed little before 6 months but then increased slowly and reached a maximum at about 30 months. These results suggested that the contribution of maternal additive genetic and permanent environmental effects to growth variation differed from those of direct additive genetic and animal permanent environmental effects not only in expression time, but also in action magnitude. The phenotypic (co)variance estimates increased with age from birth to 36 months of age.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.199-203
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• 2011

본 논문은 북한강 상류의 국내 최대 다목적댐인 소양호 유역을 대상으로 하였으며, 오염물질 항목에 대한 배수구역별 오염부하량을 산정하여 유황변화에 따른 오염부하량의 유달특성을 관찰하였으며, 배수구역별 유달오염부하량의 기여율을 산정하였다. 배수구역의 오염부하량 유달특성을 관찰한 결과 BOD, SS, T-P의 경우 인북천 유역에서 높은 유달률을 보였으며, T-N의 경우 내린천 유역과 합강 유역의 시가지에서 높은 유달률을 보여 배수구역별 오염총량관리를 위한 중점관리 수질항목을 제시할 수 있었다. 다음으로 배수구역별 유황변화 및 계절변화에 따른 오염부하량의 기여율을 산정한 결과, 전반적으로 BOD와 T-P의 경우 인북천 유역에서 높은 기여율을 보였으며, SS는 강우기간에는 내린천 유역, 비강우기간에는 인북천 유역에서 T-N은 내린천과 북천 유역에서 높은 기여율을 보였다. T-N과 T-P는 호소수 부영양화 조절을 위한 제한 영양소임을 고려할 때 본 유역에 대한 오염원의 집중적인 관리가 필요한 것을 알 수 있다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.400-403
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• 2003

Etching characteristics of (Pb,Sr)$TiO_3$(PST) thin films were investigated using inductively coupled chlorine based plasma system as functions of gas mixing ratio, RF power and DC bias voltage. It was found that increasing of Ar content in gas mixture lead to sufficient increasing of etch rate and selectivity of PST to Pt. The maximum etch rate of PST film is $562\;{\AA}$/min and the selectivity of PST film to Pt is 0.8 at $Cl_2/(Cl_2+Ar)$ of 20 %. It was proposed that sputter etching is dominant etching mechanism while the contribution of chemical reaction is relatively low due to low volatility of etching products.

• Journal of Labour Economics
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• v.23 no.2
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• pp.107-126
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• 2000

In this study I am concerned with the impact of training for the unemployed on reemployment in Korea. The data is based on the survey that was conducted on those who participated in training programs in 1998 and those who did not. The matching criteria was the length of the spell of nonemployment that preceded entry to training programs. This data design allows to apply the quasi-experimental evaluation method. My estimation results indicate that the participation in training raises the hazard rate into reemployment, but training characteristics such as training contents, agencies do not affect the hazard rate significantly. This results imply that training participation increases reemployment possibility by preventing withdrawal of participants from the labor market, but training programs make little contribution to improving skills.

• Journal of The Korean Astronomical Society
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• v.37 no.4
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• pp.225-232
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• 2004

Shocks are ubiquitous in astrophysical environments and cosmic-rays (CRs) are known to be accelerated at collisionless shocks via diffusive shock acceleration. It is believed that the CR pressure is important in the evolution of the interstellar medium of our galaxy and most of galactic CRs with energies up to ${\~}\;10^{15}$ eV are accelerated by supernova remnant shocks. In this contribution we have studied the CR acceleration at shocks through numerical simulation of 1D, quasi-parallel shocks for a wide range of shock Mach numbers and shock speeds. We show that CR modified shocks evolve to time-asymptotic states by the time injected particles are accelerated to moderately relativistic energies, and that two shocks with the same Mach number, but with different shock speeds, evolve qualitatively similarly when the results are presented in terms of a characteristic diffusion length and diffusion time. We find that $10^{-4} - 10^{-3}$ of the particles passed through the shock are accelerated to form the CR population, and the injection rate is higher for shocks with higher Mach number. The time asymptotic value for the CR acceleration efficiency is controlled mainly by shock Mach number, and high Mach number shocks all evolve towards efficiencies ${\~}50\%$, regardless of the injection rate and upstream CR pressure. We conclude that the injection rates in strong quasi-parallel shocks are sufficient to lead to significant nonlinear modifications to the shock structures, implying the importance of the CR acceleration at astrophysical shocks.

• Environmental Engineering Research
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• v.25 no.3
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• pp.418-425
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• 2020

In this study soft computing techniques including, Artificial Neural Network (ANN) and Adaptive Neuro-Fuzzy Inference System (ANFIS) were investigated for the prediction of Cr(VI) transport efficiency by novel Polymer Inclusion Membranes (PIMs). Transport experiments carried out by varying parameters such as time, film thickness, carrier type, carier rate, plasticizer type, and plasticizer rate. The predictive performance of ANN and ANFIS model was evaluated by using statistical performance criteria such as Root Mean Standard Error (RMSE), Mean Absolute Error (MAE), and Coefficient of Determination (R²). Moreover, Sensitivity Analysis (SA) was carried out to investigate the effect of each input on PIMs Cr(VI) removal efficiency. The proposed ANN model presented reliable and valid results, followed by ANFIS model results. RMSE and MAE values were 0.00556, 0.00163 for ANN and 0.00924, 0.00493 for ANFIS model in the prediction of Cr(VI) removal efficiency on testing data sets. The R² values were 0.973 and 0.867 on testing data sets by ANN and ANFIS, respectively. Results show that the ANN-based prediction model performed better than ANFIS. SA demonstrated that time; film thickness; carrier type and plasticizer type are major operating parameters having 33.61%, 26.85%, 21.07% and 8.917% contribution, respectively.