• Journal of Energy Engineering
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• v.24 no.1
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• pp.164-171
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• 2015

Although coal-fired power generation has played a role as base load unit, it has incurred various social costs in the process of generating and providing electricity. It is necessary to extend the proportion of low-carbon power generations, and reduce the ratio of coal-fired power generation to cope with global climate changes. This study, therefore, attempts to estimate the public's willingness-to-pay (WTP) for substitution of supplied electricity from hydro-electricity generation, a representative renewable energy, for coal-fired power generation. To this end, we apply the contingent valuation (CV) method, widely used technique when valuing non-market goods, to elicit the public's WTP. In addition, a spike model is employed to consider zero WTPs. After the empirical analysis with 1,000 households CV survey data, the results show that mean household's WTP for replacing supplied electricity from hydro-electricity generation with coal-fired power generation is estimated to be about 54 KRW per kWh. The results of this study are expected to contribute to determining energy-mix and provide benefit information of hydro-electricity generation.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.10
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• pp.2197-2204
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• 2009

In this paper, we analyze the performance of the sphere decoding algorithm at MIMO system. The BER performance of this algorithm is the same as that of ML receiver, but computational complexity of SD algorithm is much less than that of ML receiver. The independent signals from each transmit antennas are modulated by using the QPSK and 16QAM modulation in the richly scattered Rayleigh flat-fading channel. The received signals from each receivers is independently detected by the receiver using Fincke & Pohst SD algorithm, and the BER output of the algorithm is compared with those of ZF, MMSE, SIC, and ML receivers. We also investigate the Viterbo & Boutros SD algorithm which is the modified SD algorithm, and the BER performance and the floting point operations of the algorithms are comparatively studied.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.10
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• pp.2073-2081
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• 2002

In product design and manufacturing, axiomatic design provides a systematic approach for the decision-making process. Two axioms have been defined such as the Independence Axiom and the Information Axiom. The Information Axiom states that the best design among those that satisfy the independence axiom is the one with the least information content. In other words, the best design is the one that has the highest probability of success. On the other hand, the Taguchi robust design is used in the two-step process; one is "reduce variability," and the other is "adjust the mean on the target." The two-step can be interpreted as a problem that has two FRs (functional requirements). Therefore, the Taguchi method should be used based on the satisfaction of the Independence Axiom. Common aspects exist between the Taguchi method and Axiomatic Design in that a robust design is induced. However, different characteristics are found as well. The Taguchi method does not have the design range, and the probability of success may not be enough to express robustness. Our purpose is to find the one that has the highest probability of success and the smallest variation. A new index is proposed to satisfy these conditions. The index is defined by multiplication of the robustness weight function and the probability density function. The robustness weight function has the maximum at the target value and zero at the boundary of the design range. The validity of the index is proved through various examples.gh various examples.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.551-554
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• 2005

The method of the reduction of the automotive induction noise can be classified by the method of passive control and the method of active control. However, the passive control method has a demerit to reduce the effect of noise reduction at low frequency (below 500Hz) range and to be limited by a space of the engine room. Whereas, the active control method can overcome the demerit of passive control method. The algorithm of active control is mostly used the LMS (Least-Mean-Square) algorithm because the LMS algorithm can easily obtain the complex transfer function in real-time. Especially, When the Filtered-X LMS (FXLMS) algorithm is applied to an ANC system. However, the convergence performance of LMS algorithm goes bad when the FXLMS algorithm is applied to an active control of the induction noise under rapidly accelerated driving conditions. Thus Normalized FXLMS algorithm was developed to improve the control performance under the rapid acceleration. The advantage of Normalized FXLMS algorithm is that the step size is no longer constant. Instead, it varies with time. But there is one additional practical difficulty that can arise when a nonstationary input is used. If the input is zero for consecutive samples, then the step size becomes unbounded. So, in order to solve this problem. the Correlation FXLMS algorithm was developed. The Correlation FXLMS algorithm is realized by using an estimate of the cross correlation between the adaptation error and the filtered input signal to control the step size. In this paper, the performance of the Correlation FXLMS Is presented in comparison with that of the other FXLMS algorithms based on computer simulations.

• The Korean Journal of Food And Nutrition
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• v.30 no.5
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• pp.1068-1079
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• 2017

This study was applied to the PCA (Primary Components Analysis) for the sixteen table setting at the 2017 Yeongju local food contest. In this contest, we have developed a seonbibansang and a temple one-dish meal. As a result of the correlation analysis, the applicability and composition were 0.7980, harmony and taste were 0.7747 and easiness and composition were 0.7435. In the Primary Component $Y_1$, all the variables $X_1{\cdots}X_{10}$ mean that the quality of the food had positive values greater than zero. The second Primary Component $Y_2$ has a large positive value while $X_4$, $X_5$, $X_6$, $X_7$, $X_9$ have negative values. $Y_2$ is a value representing the sanitation variable, and can be considered a traditional and characteristic table setting natural to the native food in Yeongju. In addition, we developed an-hyangbansang and seonmyoaecheong food content by applying PCA factors (the elements of harmony, ease and sanitation). Table setting of an-hyangbansang provided energy 61.5%, protein 20.0% and fat 18.5% and seonmyoaecheong provided energy 62.7%, protein 15.4% and fat 22.2%. This satisfied the necessary amount of caloric nutrient intake that could be provided in a meal. Especially through story-telling, a modern interpretation - or rebranding - of local and traditional foods could make these traditional food products familiar to consumers currently. The developed table setting is felt to be conductive to the possible commercialization and introduction of traditional food into the mainstream commercial food service industry.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.10
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• pp.47-53
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• 2019

This study examined the effects of risk aversion on the Self-Insurance-cum-Protection activity (SICP) in a two period model, which is in contrast to existing studies that focused on an one period model. The assumption that there is a time difference between making an effort and incurring loss helps examine the effects of risk aversion in the long-term period. An increase in risk aversion always increases the efforts of SICP, whereas existing studies require additional restrictions to both the loss and cost function. Second, an increase in risk aversion always increases the efforts on self-insurance and self-protection. This result is in contrast to that of existing studies in that an increase in risk aversion increases the efforts of self-insurance, whereas the effects on the efforts of self-protection are unclear. Lastly, when there exists a background risk with zero mean and risk aversion increases in a two period model, the prudence condition of the utility function is a sufficient condition to increase the efforts of SICP.

• Korean Journal of Materials Research
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• v.29 no.10
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• pp.647-655
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• 2019

In order to analyze the effect of hot asymmetric rolling on the microstructure and texture of aluminum alloy and to investigate the effect of the texture on the formability and plastic anisotropy of aluminum alloy, aluminum 6061 alloy is asymmetrically rolled at room temperature, $200^{\circ}C$, $350^{\circ}C$, and $500^{\circ}C$, and the results are compared with symmetrically rolled results. In the case of asymmetric rolling, the equivalent strain (${\varepsilon}_{eq}$) is greatest in the upper roll part where the rotational speed of the roll is high and increases with increasing rolling temperature. The increase rate of the mean misorientation angle with increasing temperature is larger than that during symmetrical rolling, and dynamic recrystallization occurs the most when asymmetrical rolling is performed at $500^{\circ}C$. In the case of hot symmetric rolling, the {001}<110> rotated cube orientation mainly develops, but in the case of hot asymmetric rolling, the {111}<110> orientation develops along with the {001}<100> cube orientation. The hot asymmetric rolling improves the formability (${\bar{r}}$) of the aluminum 6061 alloy to 0.9 and reduces the plastic anisotropy (${\Delta}r$) to near zero due to the {111}<110> shear orientation that develops by asymmetric rolling.

• Journal of the Korean earth science society
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• v.40 no.4
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• pp.353-381
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• 2019

The general world model for homogeneous and isotropic universe has been proposed. For this purpose, we introduce a global and fiducial system of reference (world reference frame) constructed on a (4+1)-dimensional space-time, and assume that the universe is spatially a 3-dimensional hypersurface embedded in the 4-dimensional space. The simultaneity for the entire universe has been specified by the global time coordinate. We define the line element as the separation between two neighboring events on the expanding universe that are distinct in space and time, as viewed in the world reference frame. The information that determines the kinematics of the geometry of the universe such as size and expansion rate has been included in the new metric. The Einstein's field equations with the new metric imply that closed, flat, and open universes are filled with positive, zero, and negative energy, respectively. The curvature of the universe is determined by the sign of mean energy density. We have demonstrated that the flat universe is empty and stationary, equivalent to the Minkowski space-time, and that the universe with positive energy density is always spatially closed and finite. In the closed universe, the proper time of a comoving observer does not elapse uniformly as judged in the world reference frame, in which both cosmic expansion and time-varying light speeds cannot exceed the limiting speed of the special relativity. We have also reconstructed cosmic evolution histories of the closed world models that are consistent with recent astronomical observations, and derived useful formulas such as energy-momentum relation of particles, redshift, total energy in the universe, cosmic distance and time scales, and so forth. The notable feature of the spatially closed universe is that the universe started from a non-singular point in the sense that physical quantities have finite values at the initial time as judged in the world reference frame. It has also been shown that the inflation with positive acceleration at the earliest epoch is improbable.

• Safety and Health at Work
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• v.12 no.2
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• pp.249-254
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• 2021

Introduction: Workplace violence (WPV) is a major occupational and health hazard for nurses. It affects nurses' physical and psychological well-being and impacts health service delivery. We aimed to assess the prevalence and describe the consequences of WPV experienced by nurses working in an emergency department in Kenya. Methods: We conducted a descriptive cross-sectional study among emergency nurses at one of the largest tertiary hospitals in Kenya. We collected data using a structured questionnaire adapted from the 'WPV in the Health Sector, Country Case Studies Research Instruments' questionnaire. We described the prevalence and effects of WPV using frequencies and percentages. Results: Of the 82 participating nurses, 64.6% were female, 57.3% were married and 65.8% were college-educated (65.8%). Participants' mean age was 33.8 years (standard deviation: 6.8 years, range: 23-55). The overall lifetime prevalence of WPV was 81.7% (n = 67, 95% confidence interval [CI]: 71.6%-88.8%) and the 1-year prevalence was 73.2% (n = 63, 95% CI: 66.3-84.8%). The main WPV included verbal abuse, physical violence, and sexual harassment. Most incidents were perpetrated by patients and their relatives. No action was taken in 50% of the incidents, but 57.1% of physical violence incidents were reported to the hospital security and 28.6% to supervisors. Perpetrators of physical violence were verbally warned (42.9%) and reported to the hospital security (28.6%). Conclusion: Workplace violence is a significant problem affecting emergency nurses in Kenya. Hospitals should promote workplace safety with zero-tolerance to violence. Nurses should be sensitised on WPV to mitigate violence and supported when they experience WPV.

• Animal Bioscience
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• v.34 no.4
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• pp.471-481
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• 2021

Objective: A comprehensive study was conducted to study the effects of partition of variance on accuracy of genetic parameters and genetic trends of economic traits in Vanaraja male line/project directorate-1 (PD-1) chicken. Methods: Variance component analysis utilizing restricted maximum likelihood animal model was carried out with five generations data to delineate the population status, direct additive, maternal genetic, permanent environmental effects, besides genetic trends and performance of economic traits in PD-1 chickens. Genetic trend was estimated by regression of the estimated average breeding values (BV) on generations. Results: The body weight (BW) and shank length (SL) varied significantly (p≤0.01) among the generations, hatches and sexes. The least squares mean of SL at six weeks, the primary trait was 77.44±0.05 mm. All the production traits, viz., BWs, age at sexual maturity, egg production (EP) and egg weight were significantly influenced by generation. Model four with additive, maternal permanent environmental and residual effects was the best model for juvenile growth traits, except for zero-day BW. The heritability estimates for BW and SL at six weeks (SL6) were 0.20±0.03 and 0.17±0.03, respectively. The BV of SL6 in the population increased linearly from 0.03 to 3.62 mm due to selection. Genetic trend was significant (p≤0.05) for SL6, BW6, and production traits. The average genetic gain of EP40 for each generation was significant (p≤0.05) with an average increase of 0.38 eggs per generation. The average inbreeding coefficient was 0.02 in PD-1 line. Conclusion: The population was in ideal condition with negligible inbreeding and the selection was quite effective with significant genetic gains in each generation for primary trait of selection. The animal model minimized the over-estimation of genetic parameters and improved the accuracy of the BV, thus enabling the breeder to select the suitable breeding strategy for genetic improvement.